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Sample records for system himalayan orogen

  1. Earthquake activity along the Himalayan orogenic belt

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    Bai, L.; Mori, J. J.

    2017-12-01

    The collision between the Indian and Eurasian plates formed the Himalayas, the largest orogenic belt on the Earth. The entire region accommodates shallow earthquakes, while intermediate-depth earthquakes are concentrated at the eastern and western Himalayan syntaxis. Here we investigate the focal depths, fault plane solutions, and source rupture process for three earthquake sequences, which are located at the western, central and eastern regions of the Himalayan orogenic belt. The Pamir-Hindu Kush region is located at the western Himalayan syntaxis and is characterized by extreme shortening of the upper crust and strong interaction of various layers of the lithosphere. Many shallow earthquakes occur on the Main Pamir Thrust at focal depths shallower than 20 km, while intermediate-deep earthquakes are mostly located below 75 km. Large intermediate-depth earthquakes occur frequently at the western Himalayan syntaxis about every 10 years on average. The 2015 Nepal earthquake is located in the central Himalayas. It is a typical megathrust earthquake that occurred on the shallow portion of the Main Himalayan Thrust (MHT). Many of the aftershocks are located above the MHT and illuminate faulting structures in the hanging wall with dip angles that are steeper than the MHT. These observations provide new constraints on the collision and uplift processes for the Himalaya orogenic belt. The Indo-Burma region is located south of the eastern Himalayan syntaxis, where the strike of the plate boundary suddenly changes from nearly east-west at the Himalayas to nearly north-south at the Burma Arc. The Burma arc subduction zone is a typical oblique plate convergence zone. The eastern boundary is the north-south striking dextral Sagaing fault, which hosts many shallow earthquakes with focal depth less than 25 km. In contrast, intermediate-depth earthquakes along the subduction zone reflect east-west trending reverse faulting.

  2. Tectonic implications of U-Pb zircon ages of the himalayan orogenic belt in nepal

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    DeCelles; Gehrels; Quade; LaReau; Spurlin

    2000-04-21

    Metasedimentary rocks of the Greater Himalaya are traditionally viewed as Indian shield basement that has been thrust southward onto Lesser Himalayan sedimentary rocks during the Cenozoic collision of India and Eurasia. Ages determined from radioactive decay of uranium to lead in zircon grains from Nepal suggest that Greater Himalayan protoliths were shed from the northern end of the East African orogen during the late Proterozoic pan-African orogenic event. These rocks were accreted onto northern Gondwana and intruded by crustal melts during Cambrian-Ordovician time. Our data suggest that the Main Central thrust may have a large amount of pre-Tertiary displacement, that structural restorations placing Greater Himalayan rocks below Lesser Himalayan rocks at the onset of Cenozoic orogenesis are flawed, and that some metamorphism of Greater Himalayan rocks may have occurred during early Paleozoic time.

  3. Active shortening within the Himalayan orogenic wedge implied by the 2015 Gorkha earthquake

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    Whipple, Kelin X.; Shirzaei, Manoochehr; Hodges, Kip V.; Ramon Arrowsmith, J.

    2016-09-01

    Models of Himalayan neotectonics generally attribute active mountain building to slip on the Himalayan Sole Thrust, also termed the Main Himalayan Thrust, which accommodates underthrusting of the Indian Plate beneath Tibet. However, the geometry of the Himalayan Sole Thrust and thus how slip along it causes uplift of the High Himalaya are unclear. We show that the geodetic record of the 2015 Gorkha earthquake sequence significantly clarifies the architecture of the Himalayan Sole Thrust and suggests the need for revision of the canonical view of how the Himalaya grow. Inversion of Gorkha surface deformation reveals that the Himalayan Sole Thrust extends as a planar gently dipping fault surface at least 20-30 km north of the topographic front of the High Himalaya. This geometry implies that building of the high range cannot be attributed solely to slip along the Himalayan Sole Thrust over a steep ramp; instead, shortening within the Himalayan wedge is required to support the topography and maintain rapid rock uplift. Indeed, the earthquake sequence may have included a moderate rupture (Mw 6.9) on an out-of-sequence thrust fault at the foot of the High Himalaya. Such internal deformation is an expected response to sustained, focused rapid erosion, and may be common to most compressional orogens.

  4. Magnitude of crustal shortening and structural framework of the easternmost Himalayan orogen, northern Indo-Burma Ranges of northeastern India

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    Haproff, P. J.; Yin, A.

    2016-12-01

    Along-strike variation in crustal shortening throughout the Himalayan orogen has been attributed to (1) diachronous, eastward-increasing convergence, or (2) localized controls including pre-collisional stratigraphic configuration and climate. In this study, we present new geologic maps and balanced cross-sections across the easternmost segment of the Himalayan orogen, the N-S-trending N. Indo-Burma Ranges of northeastern India. First order structures are NE-dipping, km-wide ductile thrust shear zones with mylonitic fabrics indicating top-to-the SW motion. Major structures include the Mayodia klippe and Hunli window, generated during folding of the SW-directed Tidding thrust and duplexing of Lesser Himalayan rocks (LHS) at depth. Reconstruction of two balanced cross-sections yields minimum shortening estimates of 70% (48 km) and 71% (133 km), respectively. The widths of the orogen for each transect are 21 km and 54 km, respectively. Our percent strain values are comparable to that of western Arunachal Himalaya, reflecting eastward-increasing strain due to counterclockwise rotation of India during convergence or along-strike variation in India's subduction angle. However, shortening magnitudes much less than that of the Sikkim (641 km), Bhutan (414-615 km), and western Arunachal Himalaya (515-775 km) could signal eastward increasing shortening of a unique Himalayan stratigraphic framework, evidenced by few GHC rocks, absence of Tethyan strata, and an extensive subduction mélange and forearc complex.

  5. Millennial lag times in the Himalayan sediment routing system

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    Blöthe, Jan Henrik; Korup, Oliver

    2013-11-01

    Any understanding of sediment routing from mountain belts to their forelands and offshore sinks remains incomplete without estimates of intermediate storage that decisively buffers sediment yields from erosion rates, attenuates water and sediment fluxes, and protects underlying bedrock from incision. We quantify for the first time the sediment stored in >38 000 mainly postglacial Himalayan valley fills, based on an empirical volume-area scaling of valley-fill outlines automatically extracted from digital topographic data. The estimated total volume of 690(/-242+452) km is mostly contained in few large valley fills >1 km, while catastrophic mass wasting adds another 177(±31) km. Sediment storage volumes are highly disparate along the strike of the orogen. Much of the Himalaya's stock of sediment is sequestered in glacially scoured valleys that provide accommodation space for ∼44% of the total volume upstream of the rapidly exhuming and incising syntaxes. Conversely, the step-like long-wave topography of the central Himalayas limits glacier extent, and thus any significant glacier-derived storage of sediment away from tectonic basins. We show that exclusive removal of Himalayan valley fills could nourish contemporary sediment flux from the Indus and Brahmaputra basins for >1 kyr, though individual fills may attain residence times of >100 kyr. These millennial lag times in the Himalayan sediment routing system may sufficiently buffer signals of short-term seismic as well as climatic disturbances, thus complicating simple correlation and interpretation of sedimentary archives from the Himalayan orogen, its foreland, and its submarine fan systems.

  6. Linkages Between Critical Wedges and Crustal Channels Using 2-D Coupled Thermomechanical Finite Element Models: Implications for Himalayan Orogenic Evolution

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    Sparks, S. A.; Thigpen, J. R.

    2017-12-01

    In continental tectonics, questions remain regarding the dominant mechanisms of shortening accommodation during orogen evolution. Two quantitatively-supported models, critical wedge and channel flow, have been applied to the Himalaya and proposed for other large collisional systems. These two models represent fundamentally distinct mechanisms for accommodating shortening in collisional systems and until recently have been viewed as mutually exclusive. While there remains support for these mechanisms being incompatible end-members, in more recent studies it has been proposed that either: (1) both geodynamic mechanisms may operate simultaneously yet in spatially distinct parts of the larger composite orogenic system or (2) both mechanisms are present yet they operate at temporally distinct intervals, wherein the orogen progressively develops through stages dominated by mid-crustal channel flow followed by shallow thrust stacking and duplex development. In both scenarios, the mechanism active at each stage in orogen evolution is presumably dependent upon local to regional scale rheological conditions (as a function of orogen dynamic and thermal evolution) that are likely to be transient in both space and time. However, questions regarding the dynamic, mechanical, and thermal-kinematic relationships of such a system remain. Also, while field observations and deformation records derived from analyses of transects within the Himalaya can be interpreted in such a way to be consistent with a unified model, numerical models that predict the behavior of interactions between the end-member models have - until now - not existed. Here, we present results from 2-D coupled thermomechanical finite-element numerical experiments that examine the necessary conditions for mechanical compatibility between the channel and critical wedge by focusing on the role of rheology. These model results will eventually allow us to make preliminary comparisons between model-derived stress

  7. Seismic model of the upper mantle beneath the Alpine-Himalayan orogenic belt from tomographic inversion of the ISC data

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    Koulakov, Ivan

    2010-05-01

    A new seismic model of P and S anomalies in the upper mantle beneath the Alpine-Himalayan orogenic belt is presented. Travel-time data from the ISC catalogue have been inverted using a linearized approach. A large amount of global data for more than 40 years enables good ray coverage which ensures high quality of synthetic tests (e.g. checkerboard tests). At the same time, these data are very noisy, and the noise seems often to be biased. The data quality varies in different parts of the study area that makes adequate simulating of real situation in synthetic modeling almost impossible. To validate our results, we present the result of independent inversion of two data subsets (with odd and even events) that allows us revealing robust features which are not affected by random factors. The presented seismic model reveals some important features which can be attributed to geodynamical processes controlling the collision process. In the Mediterranean part we observe complex shapes of the subducting African lithosphere. In particular, the Calabrian slab looks as an elongated (~700 km long and ~100 km thick) "sausage" which penetrates to the depth of 300-400 km. In Asia we observe a few high velocity patterns which can be attributed to the process of the lithosphere recycling in the collision belts. Beneath Zagros (Iran) a slab-shaped anomaly coincides with active seismicity down to 100 km depth and probably marks the final stage of the Tethyan subduction. A trace of suspended old slab is observed beneath Tien Shan. We observe an almost isometrical bright high-velocity anomaly beneath Pamir - Hindukush. We interpret this pattern as a drop of delaminating material triggered by eclogitization of the lower part of thickened crust, and not as a subducting lithosphere as often proposed. Based on our tomographic models, we claim that the delamination is the major mechanism of the lithosphere recycling in the continent-continent collision areas. Today we have a chance to

  8. Adoption of Geospatial Systems towards evolving Sustainable Himalayan Mountain Development

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    Murthy, M. S. R.; Bajracharya, B.; Pradhan, S.; Shestra, B.; Bajracharya, R.; Shakya, K.; Wesselmann, S.; Ali, M.; Bajracharya, S.; Pradhan, S.

    2014-11-01

    Natural resources dependence of mountain communities, rapid social and developmental changes, disaster proneness and climate change are conceived as the critical factors regulating sustainable Himalayan mountain development. The Himalayan region posed by typical geographic settings, diverse physical and cultural diversity present a formidable challenge to collect and manage data, information and understands varied socio-ecological settings. Recent advances in earth observation, near real-time data, in-situ measurements and in combination of information and communication technology have transformed the way we collect, process, and generate information and how we use such information for societal benefits. Glacier dynamics, land cover changes, disaster risk reduction systems, food security and ecosystem conservation are a few thematic areas where geospatial information and knowledge have significantly contributed to informed decision making systems over the region. The emergence and adoption of near-real time systems, unmanned aerial vehicles (UAV), board-scale citizen science (crowd-sourcing), mobile services and mapping, and cloud computing have paved the way towards developing automated environmental monitoring systems, enhanced scientific understanding of geophysical and biophysical processes, coupled management of socio-ecological systems and community based adaptation models tailored to mountain specific environment. There are differentiated capacities among the ICIMOD regional member countries with regard to utilization of earth observation and geospatial technologies. The region can greatly benefit from a coordinated and collaborative approach to capture the opportunities offered by earth observation and geospatial technologies. The regional level data sharing, knowledge exchange, and Himalayan GEO supporting geospatial platforms, spatial data infrastructure, unique region specific satellite systems to address trans-boundary challenges would go a long way in

  9. Mesozoic alkaline plutonism: Evidence for extensional phase in Alpine-Himalayan orogenic belt in Central Alborz, north Iran

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    Roghieh Doroozi

    2017-12-01

    Full Text Available The Kamarbon Jurassic alkaline basic intrusion crops out in Central Alborz, north Iran, along the northern margin of the Alpine-Himalayan belt. The intrusion includes foid gabbros at the margins and foid monzodiorites towards the center. The foid monzodiorites are considered as the evolved melts after the fractional crystallization mostly of olivine and clinopyroxene from a foid gabbro parental magma. Based on mass balance calculation the evolution of the Kamarbon alkaline gabbro could be explained by 19.2% fractionation of clinopyroxene, 13.8% of olivine, 3% of plagioclase and 1.0% Ti-Magnetite, with 63% of residual liquid. REE inversion modeling indicates that the Kamarbon intrusion magma was generated by low degrees (<3% of partial melting from a garnet-bearing mantle source. In primitive mantle-normalized incompatible element diagrams, the Kamarbon rocks show enrichment in LILE elements (Ba, Rb, Sr and Th, HFSE elements (Nb, Ta, Ti, Zr and Hf and P and depletion in K, Y and HREE (Yb, Lu which are similar to patterns of HIMU-OIBs or intraplate alkaline magmas. According to the existence of extensional phases and occurrence of different rifting during late Triassic to middle Jurassic in Central Alborz, the formation of Kamarbon intrusion could be related to an intracontinental rifting.

  10. A Paleozoic Japan-type subduction-accretion system in the Beishan orogenic collage, southern Central Asian Orogenic Belt

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    Song, Dongfang; Xiao, Wenjiao; Windley, Brian F.; Han, Chunming; Tian, Zhonghua

    2015-05-01

    Magmatic arcs ascribed to oceanic lithosphere subduction played a dominant role in the construction of the accretionary Central Asian Orogenic Belt (CAOB). The Beishan orogenic collage, situated between the Tianshan Orogen to the west and the Inner Mongolia Orogen to the east, is a key area to understanding the subduction and accretionary processes of the southern CAOB. However, the nature of magmatic arcs in the Beishan and the correlation among different tectonic units along the southern CAOB are highly ambiguous. In order to investigate the subduction-accretion history of the Beishan and put a better spatial and temporal relationship among the tectonic belts along the southern CAOB, we carried out detailed field-based structural geology and LA-ICP-MS zircon U-Pb geochronological as well as geochemical studies along four cross-sections across crucial litho-tectonic units in the central segment of the Beishan, mainly focusing on the metamorphic assemblages and associated plutons and volcanic rocks. The results show that both the plutonic and volcanic rocks have geochemical characteristics similar to those of subduction-related rocks, which favors a volcanic arc setting. Zircons from all the plutonic rocks yield Phanerozoic ages and the plutons have crystallization ages ranging from 464 ± 2 Ma to 398 ± 3 Ma. Two volcanic-sedimentary rocks yield zircons with a wide age range from Phanerozoic to Precambrian with the youngest age peaks at 441 Ma and 446 Ma, estimated to be the time of formation of the volcanic rocks. These new results, combined with published data on ophiolitic mélanges from the central segment of the Beishan, favor a Japan-type subduction-accretion system in the Cambrian to Carboniferous in this part of the Paleo-Asian Ocean. The Xichangjing-Niujuanzi ophiolite probably represents a major suture zone separating different tectonic units across the Beishan orogenic collage, while the Xiaohuangshan-Jijitaizi ophiolitic mélange may represent a

  11. The Alpine-Carpathian-Dinaridic orogenic system: correlation and evolution of tectonic units

    NARCIS (Netherlands)

    Schmid, S.M.; Bernoulli, D.; Fügenschuh, B.; Matenco, L.C.; Schefer, S.; Schuster, R.; Tischler, M.; Ustaszewski, K.

    2008-01-01

    A correlation of tectonic units of the Alpine-Carpathian-Dinaridic system of orogens, including the substrate of the Pannonian and Transylvanian basins, is presented in the form of a map. Combined with a series of crustal-scale cross sections this correlation of tectonic units yields a clearer

  12. Tibet- Himalayan Analogs of Pan-African Shear Zones : Implications for Neoproterozoic Tectonics

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    Attoh, K.; Brown, L. D.

    2009-12-01

    Large-scale shear zones are distinct features of Tibet-Himalayan orogen and the Pan-African Trans-Saharan belt. Prominent examples in the Pan-African-belt extend for ~2500 km from the Sahara to the Gulf of Guinea and are characterized by right-slip movements. The NS shear zones, such as 4°50’-Kandi shear zone (KSZ) are complemented by NE-SW shear zones that preserve a record of sinistral movements and are represented by the Central Cameroon shear zone (CCSZ) in the eastern part of the Pan-African domain. The West African shear zones project into similar structures in the Borborema Province of northeast Brazil. In addition, the Pan-African belt preserves structures and rock assemblages that indicate subduction-collision tectonics We propose that structures of Tibet-Himalayan collisional orogen are instructive analogs of the Pan-African structures where: (i) the Pan-African front corresponds to the Main Himalayan thrust and it’s splays; (ii) the main Pan-African suture zone is analogous to the Indus-Tsangpo suture in the Tibet-Himalayan belt; (iii) the 4°50’-KSZ corresponds to Karakoram and it’s linkages with Jiali fault system and (iv) left-slip CCSZ and related shear zones are analogs of Altyn Tagh and Kumlun faults and their splays. This suggests the operation of escape-type tectonics in the Neoproterozoic belt of West-Africa and predicts the nature of the deep structures in the Cenozoic Tibet-Himalayan orogen.

  13. Link between Indian monsoon rainfall and physical erosion in the Himalayan system during the Holocene

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    Joussain, Ronan; Liu, Zhifei; Colin, Christophe; Duchamp-Alphonse, Stéphanie; Yu, Zhaojie; Moréno, Eva; Fournier, Léa.; Zaragosi, Sébastien; Dapoigny, Arnaud; Meynadier, Laure; Bassinot, Franck

    2017-09-01

    Mineralogical and geochemical analyses conducted on cores located on the active channel-levee system of the northern Bengal Fan are used to establish changes in the weathering pattern and the sediment transport of the Himalayan system, and evaluate the effect of Indian summer monsoon rainfall during the Holocene. Our data indicate that during the Holocene, sediments from the northern Bengal Fan originate mainly from the G-B river system without any significant changes in the relative contribution of these rivers. From 9.8 to around 6 ka, relatively low smectite/(illite+chlorite) ratios and relatively high K/Si* ratios indicate high physical denudation rates of the Himalayan highlands together with a rapid transfer of the detrital material to the Bengal Fan. The period between 9.2 and 7 ka is associated to lower values of K/Si* and corresponds to the maximum of Indian monsoon rainfall which indicates a more important chemical weathering material that rapidly transits by the G-B river system without a long storage in the Indo-Gangetic plain. From 6.0 ka to present day, higher smectite/(illite+chlorite) ratio and lower K/Si* ratio document a gradual increase of sediments originated from the Indo-Gangetic plain, characterized by higher degree of chemical weathering. During the last 2.5 ka, the drastic increase in the smectite/(illite+chlorite) ratio could be associated to enhanced alteration of the plain soils due to anthropogenic activity. The comparison of mineralogical and geochemical data with previous reconstructions of the Indian monsoon dynamic indicates a rapid response of erosion and sediment transfer of the G-B river system to changes of monsoon rainfall intensity.

  14. Determining bioclimatic space of Himalayan alder for agroforestry systems in Nepal

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    Santosh Kumar Rana

    2018-02-01

    Full Text Available Himalayan alder species are proven to be very useful in traditional as well as contemporary agroforestry practice. These nitrogen-fixing trees are also useful in the land restoration. Therefore, understanding the distribution of Himalayan alder and the potential zone for plantation is meaningful in the agroforestry sector. Suitable climatic zones of Alnus spp. were modelled in MaxEnt software using a subset of least correlated bioclimatic variables for current conditions (1950–2000, topographic variables (DEM derived and Landuse Landcover (LULC data. We generated several models and selected the best model against random models using ANOVA and t-test. The environmental variables that best explained the current distribution of the species were identified and used to project into the future. For future projections, ensemble scenarios of climate change projection derived from the results of 19 Earth System Models (ESM were used. Our model revealed that the most favorable conditions for Alnus nepalensis are in central Nepal in the moist north-west facing slope, whereas for Alnus nitida they are in western Nepal. The major climatic factor that contributes to Alnus species distribution in Nepal appears to be precipitation during the warmest quarter for A. nepalensis and precipitation during the driest quarter for A. nitida. Future projections revealed changes in the probability distribution of these species, as well as where they need conservation and where they can be planted. Also, our model predicts that the distribution of Alnus spp. in hilly regions will remain unchanged, and therefore may represent sites that can be used to revitalize traditional agroforestry systems and extract source material for land restoration.

  15. Global navigation satellite system detection of preseismic ionospheric total electron content anomalies for strong magnitude (Mw>6) Himalayan earthquakes

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    Sharma, Gopal; Champati ray, Prashant Kumar; Mohanty, Sarada; Gautam, Param Kirti Rao; Kannaujiya, Suresh

    2017-10-01

    Electron content in the ionosphere is very sensitive to temporary disturbances of the Earth's magnetosphere (geomagnetic storm), solar flares, and seismic activities. The Global Navigation Satellite System (GNSS)-based total electron content (TEC) measurement has emerged as an important technique for computations of earthquake precursor signals. We examined the pre-earthquake signatures for eight strong magnitude (Mw>6: 6.1 to 7.8) earthquakes with the aid of GNSS-based TEC measurement in the tectonically active Himalayan region using International GNSS Service (IGS) stations as well as local GNSS-based continuously operating reference stations (CORS). The results indicate very significant ionospheric anomalies in the vertical total electron content (vTEC) a few days before the main shock for all of the events. Geomagnetic activities were also studied during the TEC observation window to ascertain their role in ionospheric perturbations. It was also inferred that TEC variation due to low magnitude events could also be monitored if the epicenter lies closer to the GNSS or IGS station. Therefore, the study has confirmed TEC anomalies before major Himalayan earthquakes, thereby making it imperative to set up a much denser network of IGS/CORS for real-time data analysis and forewarning.

  16. West-directed thrusting south of the eastern Himalayan syntaxis indicates clockwise crustal flow at the indenter corner during the India-Asia collision

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    Haproff, Peter J.; Zuza, Andrew V.; Yin, An

    2018-01-01

    Whether continental deformation is accommodated by microplate motion or continuum flow is a central issue regarding the nature of Cenozoic deformation surrounding the eastern Himalayan syntaxis. The microplate model predicts southeastward extrusion of rigid blocks along widely-spaced strike-slip faults, whereas the crustal-flow model requires clockwise crustal rotation along closely-spaced, semi-circular right-slip faults around the eastern Himalayan syntaxis. Although global positioning system (GPS) data support the crustal-flow model, the surface velocity field provides no information on the evolution of the India-Asia orogenic system at million-year scales. In this work, we present the results of systematic geologic mapping across the northernmost segment of the Indo-Burma Ranges, located directly southeast of the eastern Himalayan syntaxis. Early research inferred the area to have experienced either right-slip faulting accommodating northward indentation of India or thrusting due to the eastward continuation of the Himalayan orogen in the Cenozoic. Our mapping supports the presence of dip-slip thrust faults, rather than strike-slip faults. Specifically, the northern Indo-Burma Ranges exposes south- to west-directed ductile thrust shear zones in the hinterland and brittle fault zones in the foreland. The trends of ductile stretching lineations within thrust shear zones and thrust sheets rotate clockwise from the northeast direction in the northern part of the study area to the east direction in the southern part of the study area. This clockwise deflection pattern of lineations around the eastern Himalayan syntaxis mirrors the clockwise crustal-rotation pattern as suggested by the crustal-flow model and contemporary GPS velocity field. However, our finding is inconsistent with discrete strike-slip deformation in the area and the microplate model.

  17. Orogen styles in the East African Orogen: A review of the Neoproterozoic to Cambrian tectonic evolution

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    Fritz, H.; Abdelsalam, M.; Ali, K. A.; Bingen, B.; Collins, A. S.; Fowler, A. R.; Ghebreab, W.; Hauzenberger, C. A.; Johnson, P. R.; Kusky, T. M.; Macey, P.; Muhongo, S.; Stern, R. J.; Viola, G.

    2013-10-01

    distinctly different orogen styles. The Arabian-Nubian Shield is an accretion-type orogen comprising a stack of thin-skinned nappes resulting from the oblique convergence of bounding plates. The Eastern Granulite-Cabo Delgado Nappe Complex is interpreted as a hot- to ultra-hot orogen that evolved from a formerly extended crust. Low viscosity lower crust resisted one-sided subduction, instead a sagduction-type orogen developed. The regions of Tanzania and Madagascar affected by the Kuungan Orogeny are considered a Himalayan-type orogen composed of partly doubly thickened crust.

  18. Prospects of solar photovoltaic–micro-wind based hybrid power systems in western Himalayan state of Himachal Pradesh in India

    International Nuclear Information System (INIS)

    Sinha, Sunanda; Chandel, S.S.

    2015-01-01

    Highlights: • Good prospects of PV–wind hybrid systems are found in western Himalayan Indian state. • A 6 kWp roof mounted PV–micro wind hybrid system at Hamirpur location is studied. • Optimum PV–wind hybrid system configurations are determined for 12 locations in the region. • Comparative analysis of hybrid systems is carried out using ANN, NASA and measured data. • Methodology can be used for assessing the potential of hybrid power systems worldwide. - Abstract: The western Himalayan state of Himachal Pradesh is known as the hydro-power state of India with associated social and environmental problems of large hydro power plants. The reduced water inflow in the rivers during extreme winters affects power generation in the state. Therefore solar and wind resources need to be utilized to supplement power generation requirements. With this objective the prospects of photovoltaic–micro wind based hybrid systems are studied for 12 locations of the state. The NASA data, Artificial Neural Network predicted and ground measured data are used in the analysis of Hamirpur location whereas for remaining 11 locations estimated, NASA and Artificial Neural Network predicted data are used, as measured solar and wind data are not available for most of the locations in the state. Root Mean Square Error between three input data types are found to range from 0.08 to 1.89. The results show that ANN predicted data are close to measured/estimated data. A 6 kWp roof mounted photovoltaic–micro wind hybrid system at Hamirpur with daily average energy demand of 5.2 kWh/day is studied. This system specifications are used to obtain optimum PV–micro wind based hybrid power system configurations for all locations. The optimum configuration for Hamirpur is found to be a 5 kWp micro wind turbine, 2 kW converter, 10 batteries and 8 kWp PV system whereas for other 11 locations a 5 kWp micro wind turbine, 2 kW converter, 10 batteries and 2–9 kWp PV systems are obtained. The

  19. Evolution of the Paleogene succession of the western Himalayan foreland basin

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    B.P. Singh

    2013-03-01

    Full Text Available The Paleogene succession of the Himalayan foreland basin is immensely important as it preserves evidence of India-Asia collision and related records of the Himalayan orogenesis. In this paper, the depositional regime of the Paleogene succession of the Himalayan foreland basin and variations in composition of the hinterland at different stages of the basin developments are presented. The Paleogene succession of the western Himalayan foreland basin developed in two stages, i.e. syn-collisional stage and post-collisional stage. At the onset, chert breccia containing fragments derived from the hanging walls of faults and reworked bauxite developed as a result of erosion of the forebulge. The overlying early Eocene succession possibly deposited in a coastal system, where carbonates represent barriers and shales represent lagoons. Up-section, the middle Eocene marl beds likely deposited on a tidal flat. The late Eocene/Oligocene basal Murree beds, containing tidal bundles, indicate that a mixed or semi-diurnal tidal system deposited the sediments and the sedimentation took place in a tide-dominated estuary. In the higher-up, the succession likely deposited in a river-dominated estuary or in meandering rivers. In the beginning of the basin evolution, the sediments were derived from the Precambrian basement or from the metasediments/volcanic rocks possessing terrains of the south. The early and middle Eocene (54.7–41.3 Ma succession of the embryonic foreland possibly developed from the sediments derived from the Trans-Himalayan schists and phyllites and Indus ophiolite of the north during syn-collisional stage. The detrital minerals especially the lithic fragments and the heavy minerals suggest the provenance for the late Eocene/Oligocene sequences to be from the recycled orogenic belt of the Higher Himalaya, Tethyan Himalaya and the Indus-suture zone from the north during post-collisional stage. This is also supported by the paleocurrent

  20. Timing of initiation and fault rates of the Yushu-Xianshuihe-Xiaojiang fault system around the eastern Himalayan syntaxis.

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    Hervé Leloup, Philippe; Replumaz, Anne; Chevalier, Marie-Luce; Zhang, Yuan-Ze; Paquette, Jean-Louis; Wang, Guo-Can; Bernet, Matthias; van der Beek, Peter; Pan, Jiawei; Metois, Marianne; Li, Haibing

    2017-04-01

    In eastern Tibet, the left-lateral strike-slip Yushu-Xianshuihe-Xiaojiang fault system (YXX-FS) is 1400 km long, veering from N100° to N175° broadly following a small circle whose pole is located in the eastern Himalayan syntaxis. Several competing models are proposed to explain the geological evolution of eastern Tibet, and in particular of the YXX-FS: fault following slip-lines in a plastic media, book-shelf fault in a large right-lateral shear zone, or fault bounding a lower channel flow veering around the syntaxis. In this contribution we document the timing of onset of the YXX-FS, its propagation through time, its rate at various time-scales; and discuss how these relate to the deformation models. The YXX-FS comprises four segments from east (Tibetan Plateau) to west (Yunnan): Yushu-Ganzi, Xianshuihe, Anninghe, and Zemuhe-Xiaojiang. It is one of the most tectonically active intra-continental fault system in China along which more than 20 M>6.5 earthquakes occurred since 1700. Slip-rates of 3.5 to 30 mm/yr along the YXX-FS have been suggested by matching geological offsets of 60-100 km with initiation ages of 2 to 17 Ma. Late Quaternary rates deduced from morphological offsets, InSAR, paleoseismology and GPS also show a large range: between 3 and 20 mm/yr. The timing of initiation of the Yushu-Ganzi segment has been constrained at 12.6±1 Ma and its total offset to 76 - 90 km (Wang et al., 2009) yielding a rate of 6.6+0.8-0.7 mm/yr. By measuring the offsets of moraine crests and fan edges across the fault using LiDAR and kinematic GPS, and dating their surfaces using 10Be, we determined slip-rates of 7+1.1-1.0 mm/yr, 3 - 11.2 mm/yr and 8.5+0.8-0.7 mm/yr at three different sites. This suggests a constant rate of 6-8 mm/yr along the fault segment since 13Ma. The timing of initiation of the Xianshuihe segment was thought to be prior to 12.8±1.4 Ma (Roger et al., 1995), but new field studies and geochronological ages suggest that the fault initiated later. Using

  1. Lesser Himalayan sequences in Eastern Himalaya and their deformation: Implications for Paleoproterozoic tectonic activity along the northern margin of India

    Directory of Open Access Journals (Sweden)

    Dilip Saha

    2013-05-01

    Full Text Available Substantial part of the northern margin of Indian plate is subducted beneath the Eurasian plate during the Caenozoic Himalayan orogeny, obscuring older tectonic events in the Lesser Himalaya known to host Proterozoic sedimentary successions and granitic bodies. Tectonostratigraphic units of the Proterozoic Lesser Himalayan sequence (LHS of Eastern Himalaya, namely the Daling Group in Sikkim and the Bomdila Group in Arunachal Pradesh, provide clues to the nature and extent of Proterozoic passive margin sedimentation, their involvement in pre-Himalayan orogeny and implications for supercontinent reconstruction. The Daling Group, consisting of flaggy quartzite, meta-greywacke and metapelite with minor mafic dyke and sill, and the overlying Buxa Formation with stromatolitic carbonate-quartzite-slate, represent shallow marine, passive margin platformal association. Similar lithostratigraphy and broad depositional framework, and available geochronological data from intrusive granites in Eastern Himalaya indicate strikewise continuity of a shallow marine Paleoproterozoic platformal sequence up to Arunachal Pradesh through Bhutan. Multiple fold sets and tectonic foliations in LHS formed during partial or complete closure of the sea/ocean along the northern margin of Paleoproterozoic India. Such deformation fabrics are absent in the upper Palaeozoic–Mesozoic Gondwana formations in the Lesser Himalaya of Darjeeling-Sikkim indicating influence of older orogeny. Kinematic analysis based on microstructure, and garnet composition suggest Paleoproterozoic deformation and metamorphism of LHS to be distinct from those associated with the foreland propagating thrust systems of the Caenozoic Himalayan collisional belt. Two possibilities are argued here: (1 the low greenschist facies domain in the LHS enveloped the amphibolite to granulite facies domains, which were later tectonically severed; (2 the older deformation and metamorphism relate to a Pacific type

  2. Diversity, risk mediation, and change in a Trans-Himalayan agropastoral system

    NARCIS (Netherlands)

    Mishra, C.; Wieren, van S.E.; Prins, H.H.T.

    2003-01-01

    We describe the diversity and dynamism of social, agricultural, and livestock husbandry practices in a traditional mountain production system in the Indian Trans-Himalaya. These are interpreted in the context of their role in mediating environmental risk. The production system is a little known

  3. Geomorphology of the Ganges fluvial system in the Himalayan foreland: an update

    Directory of Open Access Journals (Sweden)

    Rajiv Sinha

    2004-12-01

    Full Text Available The Ganges is one of the largest fluvial systems in the world rising from the loftiest Himalaya and draining into the Bay of Bengal. Together with the Brahmaputra, it also constitutes the largest delta in the world before finally meeting the sea. The Ganges system passes through a variety of terrain from the rugged mountains through the flat alluvial plains and the sea margin, and also transects variable climatic zones. As a result, the processes, landforms and stratigraphy are strikingly different in different zones of the system. This paper attempts to provide an update on our understanding of this very large and diverse system. A global effort has been made in the last few decades, and the research has focused on a variety of themes. The mountainous catchments have attracted attention in view of the extent of glaciation and extensive erosional processes. The alluvial plains of the Ganges symbolizes the life line of one of the world's largest population. Consequently, a number of studies have been carried out on the morphology, hydrology including flooding history and sediment transport behaviour of the river system. The alluvial stratigraphy of the large valleys and the interfluves in the plains has provided insight about the sedimentation pattern and response to climate change. The deltaic plain is the final destination of this huge sediment dispersal system before it drains into the sea, and it also records the influence of sea level changes apart from the upstream catchment controls over a period of time.

  4. Mass elevation and lee effects markedly lift the elevational distribution of ground beetles in the Himalaya-Tibet orogen.

    Science.gov (United States)

    Schmidt, Joachim; Böhner, Jürgen; Brandl, Roland; Opgenoorth, Lars

    2017-01-01

    Mass elevation and lee effects markedly influence snow lines and tree lines in high mountain systems. However, their impact on other phenomena or groups of organisms has not yet been quantified. Here we quantitatively studied their influence in the Himalaya-Tibet orogen on the distribution of ground beetles as model organisms, specifically whether the ground beetle distribution increases from the outer to the inner parts of the orogen, against latitudinal effects. We also tested whether July temperature and solar radiation are predictors of the beetle's elevational distribution ranges. Finally, we discussed the general importance of these effects for the distributional and evolutionary history of the biota of High Asia. We modelled spatially explicit estimates of variables characterizing temperature and solar radiation and correlated the variables with the respective lower elevational range of 118 species of ground beetles from 76 high-alpine locations. Both July temperature and solar radiation significantly positively correlated with the elevational ranges of high-alpine beetles. Against the latitudinal trend, the median elevation of the respective species distributions increased by 800 m from the Himalayan south face north to the Transhimalaya. Our results indicate that an increase in seasonal temperature due to mass elevation and lee effects substantially impact the regional distribution patterns of alpine ground beetles of the Himalaya-Tibet orogen and are likely to affect also other soil biota there and in mountain ranges worldwide. Since these effects must have changed during orogenesis, their potential impact must be considered when biogeographic scenarios based on geological models are derived. As this has not been the practice, we believe that large biases likely exist in many paleoecological and evolutionary studies dealing with the biota from the Himalaya-Tibet orogen and mountain ranges worldwide.

  5. Orogen migration and tectonic setting of the Andrelândia Nappe system: An Ediacaran western Gondwana collage, south of São Francisco craton

    Science.gov (United States)

    Campos Neto, Mario da Costa; Basei, Miguel Angelo Stipp; Assis Janasi, Valdecir de; Moraes, Renato

    2011-12-01

    The southern Brasília Orogen is organized in a pile of nappes that records the Neoproterozoic history of the subduction and collision between passive and active margins, respectively belonging to the São Francisco and Paranapanema Plates. The whole pile of allochthons comprises the rootless Andrelândia Nappe System (the upper kyanite-bearing granulite of Três Pontas-Varginha Nappe, the intermediate high-pressure amphibolite-to eclogite facies of Liberdade Nappe and the lower Andrelândia Nappe) that is located below an Andean-type magmatic arc (Socorro-Guaxupé Nappe) and overrides the Lima Duarte Nappe and the Carrancas Nappe System. The tectonic units of the Andrelândia Nappe System seem to be exotic to the São Francisco Plate. The retroeclogite of the Liberdade Nappe yielded a 670 Ma SHRIMP U-Pb age in zircon, that is interpreted as the age of N-MORB-type basic magmatism. Detrital zircon grains of proximal flysh deposits of wackes in the Andrelândia Nappe present similar ages that reflect the crystallization in its source area. Both, rocks present Nd isotopic juvenile signatures with T DM in the range of 1.4 to 1.1 Ga. Rhyacian orthogneisses occur as slices in the Liberdade Nappe and have Nd isotope signature of juvenile source. The building of the collision pile of the whole system of nappes was diachronic and records a continuous outward migration of the orogen. The main structure is a middle crust-level duplex. The propagation of the structure and the metamorphism advanced progressively from the upper to the lower nappes, as is shown by U-Pb monazite ages in the range of 618-595 Ma for the Andrelândia Nappe System and 590-575 Ma for the Carrancas and Lima Duarte nappes.

  6. Structure and evolution of the drainage system of a Himalayan debris-covered glacier, and its relationship with patterns of mass loss

    Science.gov (United States)

    Benn, Douglas I.; Thompson, Sarah; Gulley, Jason; Mertes, Jordan; Luckman, Adrian; Nicholson, Lindsey

    2017-09-01

    We provide the first synoptic view of the drainage system of a Himalayan debris-covered glacier and its evolution through time, based on speleological exploration and satellite image analysis of Ngozumpa Glacier, Nepal. The drainage system has several linked components: (1) a seasonal subglacial drainage system below the upper ablation zone; (2) supraglacial channels, allowing efficient meltwater transport across parts of the upper ablation zone; (3) sub-marginal channels, allowing long-distance transport of meltwater; (4) perched ponds, which intermittently store meltwater prior to evacuation via the englacial drainage system; (5) englacial cut-and-closure conduits, which may undergo repeated cycles of abandonment and reactivation; and (6) a "base-level" lake system (Spillway Lake) dammed behind the terminal moraine. The distribution and relative importance of these elements has evolved through time, in response to sustained negative mass balance. The area occupied by perched ponds has expanded upglacier at the expense of supraglacial channels, and Spillway Lake has grown as more of the glacier surface ablates to base level. Subsurface processes play a governing role in creating, maintaining, and shutting down exposures of ice at the glacier surface, with a major impact on spatial patterns and rates of surface mass loss. Comparison of our results with observations on other glaciers indicate that englacial drainage systems play a key role in the response of debris-covered glaciers to sustained periods of negative mass balance.

  7. Ginger and the beetle: Evidence of primitive pollination system in a Himalayan endemic alpine ginger (Roscoea alpina, Zingiberaceae).

    Science.gov (United States)

    Paudel, Babu Ram; Shrestha, Mani; Dyer, Adrian G; Li, Qing-Jun

    2017-01-01

    The Himalayan endemic alpine genus Roscoea, like other members of ginger family, exhibits the combination of floral traits that would fit pollination by long distant foragers such as bees, birds or flies. We studied the pollination biology of Roscoea alpina, observed potential floral visitors and determined their foraging behaviour, visitation frequency and pollination efficiency, to seek evidence in support of the pollination syndrome hypothesis. We also measured the floral spectra of R. alpina flowers to evaluate if signals fit with the currently known framework for observed floral visitors. We found that R. alpina have autonomous selfing and pollinator-mediated crossing, but lack apomixis. We observed that a beetle (Mylabris sp.), and a moth (Macroglossum nycteris) visit the flowers of R. alpina for pollen and nectar feeding respectively. Our field observations, the stigmatic pollen count and fruit set data indicated that the visit by the beetle was legitimate, while that of the moth was illegitimate. Emasculated flowers visited by beetles set as many fruits and seeds/fruit as auto-selfed and naturally pollinated flowers, while emasculated flowers excluded from beetle visits did not set fruit and seed; indicating that a single visit of a beetle to the flowers of R. alpina can facilitate pollination. We found that flower spectral signal of R. alpina does not fit typical spectra previously reported for beetle or bee-visited flowers. Our results suggest that, to ensure reproductive success in alpine habitat, R. alpina has evolved autonomous selfing as a predominant mode of reproduction, while beetle pollination would promote genetic diversity of this plant species. The visitation of beetles to the flowers of R. alpina, despite floral signal mismatch with the classically associated beetle vision, suggests that a different visual processing may operate in this plant-pollinator interaction at high altitudes.

  8. Active faults and related Late Quaternary deformation along the Northwestern Himalayan Frontal Zone, India

    Directory of Open Access Journals (Sweden)

    T. Nakata

    2003-06-01

    Full Text Available Numerous newly-identified traces of active faults in the Himalayan foothill zone along the HFF around Chandigarh, in Pinjore Dun, along the piedmont zone of the Lower Siwalik hill front and within the Lower Tertiary hill range reveal the pattern of thrust and strike-slip faulting, striking parallel to the principal structural trend (NNW-SSE of the orogenic belt. The active Chandigarh Fault, Pinjore Garden Fault and Barsar thrust have vertically dislocated, warped and backtilted fluvial and alluvial-fan surfaces made up of Late Pleistocene-Holocene sediments. West- and southwest-facing fault scarplets with heights ranging from 12 to 50 m along these faults suggest continued tectonic movement through Late Pleistocene to recent times. Gentle warping and backtilting of the terraces on the hanging wall sides of the faults indicate fault-bend folding. These active faults are the manifestation of north-dipping imbricated thrust faults branching out from the major fault systems like the Main Boundary Fault (MBF and Himalayan Frontal Fault (HFF, probably merging down northward into a décollement. The Taksal Fault, striking NNW-SSE, shows prominent right-lateral movement marked by lateral offset of streams and younger Quaternary terraces and occupies a narrow deep linear valley along the fault trace. Right stepping along this fault has resulted in formation of a small pull-apart basin. Fault scarplets facing ENE and WSW are the manifestation of dip-slip movement. This fault is an example of slip-partitioning between the strike-slip and thrust faults, suggesting ongoing oblique convergence of the Indian plate and northward migration of a tectonic sliver. Slip rate along the Taksal Fault has been calculated as 2.8 mm/yr. Preliminary trench investigation at the base of the Chandigarh Fault Scarp has revealed total displacement of 3.5 m along a low angle thrust fault with variable dip of 20° to 46° due northeast, possibly the result of one

  9. Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements

    DEFF Research Database (Denmark)

    Singh, Ajit; Thomsen, Kristina Jørkov; Sinha, Rajiv

    2017-01-01

    Urbanism in the Bronze-age Indus Civilisation (similar to 4.6-3.9 thousand years before the present, ka) has been linked to water resources provided by large Himalayan river systems, although the largest concentrations of urban-scale Indus settlements are located far from extant Himalayan rivers....

  10. Himalayan Adaptation, Water, and Resilience | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Himalayan Adaptation, Water, and Resilience. This research project will serve to help poor and vulnerable women, men, and children learn to adapt to and manage climate change in Asia's Hindu Kush Himalayan region. Why the Himalayan region is important. The region, stretching from central Afghanistan to northern ...

  11. Metallogenic relationships to tectonic evolution - the Lachlan Orogen, Australia

    Science.gov (United States)

    Bierlein, Frank P.; Gray, David R.; Foster, David A.

    2002-08-01

    Placing ore formation within the overall tectonic framework of an evolving orogenic system provides important constraints for the development of plate tectonic models. Distinct metallogenic associations across the Palaeozoic Lachlan Orogen in SE Australia are interpreted to be the manifestation of interactions between several microplates and three accretionary complexes in an oceanic back-arc setting. In the Ordovician, significant orogenic gold deposits formed within a developing accretionary wedge along the Pacific margin of Gondwana. At the same time, major porphyry Cu-Au systems formed in an oceanic island arc outboard of an evolved magmatic arc that, in turn, gave rise to granite-related Sn-W deposits in the Early Silurian. During the ongoing evolution of the orogen in the Late Silurian to Early Devonian, sediment-hosted Cu-Au and Pb-Zn deposits formed in short-lived intra-arc basins, whereas a developing fore-arc system provided the conditions for the formation of several volcanogenic massive sulphide deposits. Inversion of these basins and accretion to the Australian continental margin triggered another pulse of orogenic gold mineralisation during the final consolidation of the orogenic belt in the Middle to Late Devonian.

  12. Assessing the Influence of Orogenic Inheritance on the Architecture, Time Evolution and Magmatic Budget of Hyper-extended Rift Systems: a Combined Mapping and Numerical Modelling Approach

    Science.gov (United States)

    Chenin, P.; Manatschal, G.; Lavier, L. L.; Erratt, D.

    2014-12-01

    The aim of this PhD thesis is to assess the influence of inherited structures and heterogeneities on the architecture and tectonic evolution of hyper-extended rift systems, with special focus on the North Atlantic. We propose a new mapping approach using simple and robust observation-based criteria to identify key features of rift systems, namely: 1) structural elements of rift domains; 2) age of the major rift events; and 3) key structures and heterogeneities inherited from previous orogenic phases. We distinguish between 3 major rift domains: 1) the not or barely thinned proximal domain; 2) the unequivocal oceanic domain characterized by steady-state seafloor spreading; and, between them 3) the hyper-extended domain concentrating most of the deformation using gravity, magnetic and reflection and refraction seismic data. Previous studies mapped these domains along the magma-poor Iberia-Newfoundland and Bay of Biscay. One objective of this PhD is to extend this mapping further to the North, along the Irish, Scottish and Norwegian margins, into domains with polyphase rifting and magmatic additions. In addition, we assign an age to the two most important events in the development of rifted margins, namely the necking and the breakup. This approach requires us to determine how these two events are recorded in the stratigraphy and how they can be mapped in seismic sections. In order to highlight potential links between both rift domain architecture and timing of rifting and orogenic inheritance we map the structures and heterogeneities inherited from previous collision events that may have influenced significantly subsequent rifting. We consider features that: 1) are important enough to have had a potential impact on subsequent deformation; 2) are preserved through time; and 3) bear the potential to be reactivated. Based on these data, we try to link the architecture and evolution of the North Atlantic rift system with the nature and in-depth location of weak features

  13. Himalayan gneiss dome formation in the middle crust and exhumation by normal faulting: New geochronology of Gianbul dome, northwestern India

    Science.gov (United States)

    Horton, Forrest; Lee, Jeffrey; Hacker, Bradley; Bowman-Kamaha'o, Meilani; Cosca, Michael A.

    2015-01-01

    A general lack of consensus about the origin of Himalayan gneiss domes hinders accurate thermomechanical modeling of the orogen. To test whether doming resulted from tectonic contraction (e.g., thrust duplex formation, antiformal bending above a thrust ramp, etc.), channel flow, or via the buoyant rise of anatectic melts, this study investigates the depth and timing of doming processes for Gianbul dome in the western Himalaya. The dome is composed of Greater Himalayan Sequence migmatite, Paleozoic orthogneiss, and metasedimentary rock cut by multiple generations of leucogranite dikes. These rocks record a major penetrative D2 deformational event characterized by a domed foliation and associated NE-SW–trending stretching lineation, and they are flanked by the top-down-to-the-SW (normal-sense) Khanjar shear zone and the top-down-to-the-NE (normal sense) Zanskar shear zone (the western equivalent of the South Tibetan detachment system). Monazite U/Th-Pb geochronology records (1) Paleozoic emplacement of the Kade orthogneiss and associated granite dikes; (2) prograde Barrovian metamorphism from 37 to 33 Ma; (3) doming driven by upper-crustal extension and positive buoyancy of decompression melts between 26 and 22 Ma; and (4) the injection of anatectic melts into the upper levels of the dome—neutralizing the effects of melt buoyancy and potentially adding strength to the host rock—by ca. 22.6 Ma on the southwestern flank and ca. 21 Ma on the northeastern flank. As shown by a northeastward decrease in 40Ar/39Ar muscovite dates from 22.4 to 20.2 Ma, ductile normal-sense displacement within the Zanskar shear zone ended by ca. 22 Ma, after which the Gianbul dome was exhumed as part of a rigid footwall block below the brittle Zanskar normal fault, tilting an estimated 5°–10°SW into its present orientation.

  14. Extreme heterogeneity in Sr isotope systematic in the Himalayan ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 110; Issue 2. Extreme heterogeneity in Sr isotope systematic in the Himalayan leucogranites: A possible mechanism of partial melting based on thermal modeling. Dilip K Mukhopadhyay. Volume 110 Issue 2 June 2001 pp 161-169 ...

  15. The tectonometamorphic evolution of the Apuseni Mountains (Romania): Geodynamic constraints for the evolution of the Alps-Carpathians-Dinaride system of orogens

    Science.gov (United States)

    Reiser, Martin; Schuster, Ralf; Fügenschuh, Bernhard

    2015-04-01

    New structural, thermobarometric and geochronological data allow integrating kinematics, timing and intensity of tectonic phases into a geodynamic model of the Apuseni Mountain, which provides new constraints for the evolution of the Alps-Carpathians-Dinaride system of orogens. Strong differences in terms of deformation directions between Early and Late Cretaceous events provide new constraints on the regional geodynamic evolution during the Cretaceous. Geochronological and structural data evidence a Late Jurassic emplacement of the South Apuseni Ophiolites on top of the Biharia Nappe System (Dacia Mega-Unit), situated in an external position at the European margin. Following the emplacement of the ophiolites, three compressive deformation phases affected the Apuseni Mountains during Alpine orogeny: a) NE-directed in-sequence nappe stacking and regional metamorphic overprinting under amphibolite-facies conditions during the Early Cretaceous ("Austrian Phase"), b) NW-directed thrusting and folding, associated with greenschist-facies overprinting, during the early Late Cretaceous ("Turonian Phase") and c) E-W internal folding together with brittle thrusting during the latest Cretaceous ("Laramian Phase"). Major tectonic unroofing and exhumation at the transition from Early to Late Cretaceous times is documented through new Sm-Nd Grt, Ar-Ar Ms and Rb-Sr Bt ages from the study area and resulted in a complex thermal structure with strong lateral and vertical thermal gradients. Nappe stacking and medium-grade metamorphic overprinting during the Early Cretaceous exhibits striking parallels between the evolution of the Tisza-Dacia Mega-Units and the Austroalpine Nappes (ALCAPA Mega-Unit) and evidences a close connection. However, Late Cretaceous tectonic events in the study area exhibit strong similarities with the Dinarides. Thus, the Apuseni Mountains represent the "missing link" between the Early Cretaceous Meliata subduction (associated with obduction of ophiolites

  16. Age and geochemistry of Silurian gabbroic rocks in the Tongbai orogen, central China: implications for the geodynamic evolution of the North Qinling arc–back-arc system

    NARCIS (Netherlands)

    Wang, H.; Wu, Y.B.; Qin, Z.W.; Zhu, L.Q.; Liu, Q.; Liu, X.C.; Gao, J.; Wijbrans, J.R.; Gong, H.J.; Yuan, H.L.

    2013-01-01

    The tectonic properties of the Erlangping unit and the subduction polarity of oceanic basins in the North Qinling-Tongbai orogen have been the focus of debate for more than twenty years. The resolution of these controversies hinges on the refined constraints on the location and nature of

  17. Himalayan hydro on the horizon

    International Nuclear Information System (INIS)

    Sharp, Timothy

    2000-01-01

    The prospects for development of hydro in the Himalayas has been enhanced by privatisation and the urgent need for clean electricity in the north of India. There are various hurdles to be overcome before the projects are likely to move forward in earnest before 2005, and these are mentioned. The demand for electricity in India is said to be enormous. At present, there is much polluting industry along the Himalayas. As throughout the Indian privatisation dilemma, the critical issues for development of Himalayan hydro come down to credible commercial power markets and finance. With regard to finance and administrative changes, the Indian government is carrying out a number of actions and these are itemised. The US is vigorously promoting the development of Himalayan hydro as a key to much needed regional co-operation and the World Bank is supportive

  18. The annual invasive plant, Impatiens glandulifera (Himalayan Balsam) as a trigger for high-magnitude soil erosion in temperate river systems

    Science.gov (United States)

    Greenwood, Philip; Kuhn, Nikolaus

    2015-04-01

    The invasive plant, Impatiens glandulifera (common English name: Himalayan Balsam), is now found in most temperate European countries, as well as across large parts of North America and on some Australasian islands. As a ruderal species, it favours damp, fertile soils that experience frequent disturbance. Riverbanks and the riparian zone thus represent prime habitat. Its ability to out-compete most perennial vegetation yet tendency to suddenly die during seasonally cold weather has led to claims that it may promote soil erosion, particularly along inland watercourses. Despite the strong implication, this was only recently proven during an investigation conducted over one dieback and regrowth cycle in 2012/13 along a watercourse in northwest Switzerland. Here we reinterpret those initial findings and also present additional data from the same watercourse which now covers three die-off and regrowth cycles, as well as data over two die-off and regrowth cycles from a river system in southwest UK. Results from all monitoring campaigns strongly support the original conclusion that I. glandulifera promotes significant soil erosion along contaminated sections of riverbank and riparian zone. More specifically, however, approximately one third of the total number of contaminated locations monitored (n=41) recorded net ground surface retreat that exceeded, by at least one order of magnitude, equivalent annual erosion rates documented on cultivated hillslopes in temperate regions. Not only does I. glandulifera induce repeat cycles of colonization and die-off, therefore, but collectively, the results generated so far strongly infer that under certain circumstances, this cycle of events can commonly trigger severe or even extreme erosion. Seasonally induced soil loss of this magnitude, particularly along short sections of watercourses, is unsustainable in the long-term and may lead to key fluvial features undergoing profound morphological and structural changes. Such an effect

  19. Characterization of smallholder pig production system: productive and reproductive performances of local and crossbred pigs in Sikkim Himalayan region.

    Science.gov (United States)

    Nath, B G; Pathak, P K; Ngachan, S V; Tripathi, A K; Mohanty, A K

    2013-10-01

    The present study was conducted to know the smallholder pig production system in tribal areas of Sikkim State, India. Two hundred tribal farmers were selected randomly from the North and East District of the state. Information on socio-economic characteristics of farmers (gender, occupation, educational status, and farming experience), management practices, disease prevalence, and economics in pig production was collected. The study recorded the mean land holding as 1.2 ± 0.8 ha, and the number of pigs per farm was 5.0 ± 0.28. Pigs were mainly kept as a source of income, and 70 % of farmers reared crossbreed pigs. Ninety percent (90 %) of respondents practiced the intensive system of management whereby kitchen wastes along with cooked mixture comprising maize bhusa, mustard oil cake, pseudostem of banana, tuber, stem, and plant leaves were used to feed their animals. About 40.5 % of farmers procured their breeding stock from government farms that had good records and utilized veterinary services like timely vaccination and deworming. The diseases prevalent in the study area were swine fever, diarrhea, helminthoses, sarcoptic mange, pneumonia, etc. The litter sizes at birth (local, 4.3 ± 0.45; crossbreed, 7.2 ± 0.33), at weaning (local, 2.79 ± 0.24; crossbreed, 6.1 ± 0.21), and age at first farrowing (local, 365.39 ± 7.96 days; crossbreed, 337.24 ± 8.79 days) were recorded. Production costs of meat extracted from local and crossbred pigs were 1.08 $/kg and 0.86 $/kg, respectively.

  20. The Evolution of Eastern Himalayan Syntaxis of Tibetan Plateau

    Science.gov (United States)

    Zhang, S.; Wu, T.; Li, M.; Zhang, Y.; Hua, Y.; Zhang, B.

    2017-12-01

    Indian plate has been colliding with Eurasian plate since 50Ma years ago, resulting in the Tethys extinction, crust shortening and Tibetan plateau uplift. But it is still a debate how the Tibetan Plateau material escaped. This study tries to invert the distributions of dispersion phase velocity and anisotropy in Eastern Himalayan Syntaxis (EHS) based on the seismic data. We focused on the seven sub-blocks around EHS region. Sub-block "EHS" represents EHS corner with high velocity anomalies, significantly compressed in the axle and strike directions. Sub-blocks "LSD", "QTB" and "SP-GZB" are located at its northern areas with compressions also, and connected with low-velocity anomalies in both crustal and upper mantle rocks. Sub-block "ICB" is located at its southern area with low velocity anomaly, and connected with Tengchong volcano. Sub-blocks "SYDB" and "YZB" are located at its eastern areas with high velocity anomalies in both crustal and upper mantle rocks. Our results demonstrated that significant azimuthal anisotropy of crust (t£30s) and upper mantle (30s£t£60s). Crustal anisotropy indicates the orogenic belt matched well with the direction of fast propagation, and upper mantle anisotropy represents the lattic-preferred orientation (LPO) of mantle minerals (e.g. olivine and basalt), indicating the features of subducting Indian plate. Besides, Red River fault is a dextral strike fault, controlling the crustal and mantle migration. There is a narrow zone to be the channel flow of Tibetan crustal materials escaping toward Yunnan area. The evolution of EHS seems constrained by gravity isostatic mechanism. Keywords: Tibetan Plateau; Eastern Himalayan Syntaxis; Red River fault; crustal flow; surface wave; anisotropy

  1. Poverty, development, and Himalayan ecosystems.

    Science.gov (United States)

    Sandhu, Harpinder; Sandhu, Sukhbir

    2015-05-01

    The Himalayas are rich in biodiversity but vulnerable to anthropogenic pressures. They are also host to growing number of rural poor who are dependent on forest and ecosystem services for their livelihood. Local and global efforts to integrate poverty alleviation and biodiversity conservation in the Himalayas remain elusive so far. In this work, we highlight two key impediments in achieving sustainable development in the Himalayas. On the positive side, we also highlight the work of Ashoka Trust for Research in Ecology and the Environment (ATREE), a research organization based in India that seeks to integrate biodiversity concerns with livelihood security. For impediments, we draw on two examples from the Darjeeling district, India, in Eastern Himalayan region to illustrate how development organizations are failing to simultaneously address poverty and environmental issues. Based on the success of ATREE, we then propose a conceptual framework to integrate livelihood generating activities with sustainable and equitable development agenda. We recommend developing a Hindu-Kush Himalayan Ecosystem Services Network in the region to formulate a strategy for further action. We conclude by offering measures to address the challenge of integrating livelihood and environment issues through this network.

  2. Detrital fission-track-compositional signature of an orogenic chain-hinterland basin system: The case of the late Neogene Quaternary Valdelsa basin (Northern Apennines, Italy)

    Science.gov (United States)

    Balestrieri, M. L.; Benvenuti, M.; Tangocci, F.

    2013-05-01

    Detrital thermochronological data collected in syn-tectonic basin deposits are a promising tool for deciphering time and processes of the evolution of orogenic belts. Our study deals with the Valdelsa basin, one of the wider basins of central Tuscany, Italy. The Valdelsa basin is located at the rear of the Northern Apennines, a collisional orogen whose late Neogene Quaternary development is alternatively attributed to extensional and compressional regimes. These contrasting interpretations mostly rely on different reconstructions of the tectono-sedimentary evolution of several basins formed at the rear of the chain since the late Tortonian. Here, we explore the detrital thermochronological-compositional signature of tectonic and surface processes during the Valdelsa basin development. For this aim, detrital apatite fission-track analysis of 21 sand samples from the latest Messinian Gelasian fluvial to shallow marine basin deposits, has been accompanied by a clast composition analysis of 7 representative outcrops of the conglomerate facies. The grain-age distributions of the sediment samples are generally characterized by two distinct components, one younger peak (P1) varying between 5.5 ± 2.8 and 9.5 ± 1.0 Ma and one older peak (P2) varying from 15.0 ± 8.0 to 41.0 ± 10 Ma. By comparison with some bedrock ages obtained from the E-NE basin shoulder, we attributed the P2 peak to the Ligurian Units and the P1 peak to the Macigno Formation (Tuscan Units). These units are arranged one upon the other in the complex nappe pile forming the Northern Apennines orogen. While the gravel composition indicates a predominant feeding from the Ligurian units all along the sedimentary succession with a subordinate occurrence of Macigno pebbles slightly increasing upsection, the P1 peak is present even in the oldest collected sandy sediments. The early P1 occurrence reveals that the Macigno was exposed in the E-NE basin shoulder since at least the latest Messinian-early Zanclean

  3. Understanding Himalayan erosion and the significance of the Nicobar Fan

    Science.gov (United States)

    McNeill, Lisa C.; Dugan, Brandon; Backman, Jan; Pickering, Kevin T.; Pouderoux, Hugo F. A.; Henstock, Timothy J.; Petronotis, Katerina E.; Carter, Andrew; Chemale, Farid; Milliken, Kitty L.; Kutterolf, Steffen; Mukoyoshi, Hideki; Chen, Wenhuang; Kachovich, Sarah; Mitchison, Freya L.; Bourlange, Sylvain; Colson, Tobias A.; Frederik, Marina C. G.; Guèrin, Gilles; Hamahashi, Mari; House, Brian M.; Hüpers, Andre; Jeppson, Tamara N.; Kenigsberg, Abby R.; Kuranaga, Mebae; Nair, Nisha; Owari, Satoko; Shan, Yehua; Song, Insun; Torres, Marta E.; Vannucchi, Paola; Vrolijk, Peter J.; Yang, Tao; Zhao, Xixi; Thomas, Ellen

    2017-10-01

    A holistic view of the Bengal-Nicobar Fan system requires sampling the full sedimentary section of the Nicobar Fan, which was achieved for the first time by International Ocean Discovery Program (IODP) Expedition 362 west of North Sumatra. We identified a distinct rise in sediment accumulation rate (SAR) beginning ∼9.5 Ma and reaching 250-350 m/Myr in the 9.5-2 Ma interval, which equal or far exceed rates on the Bengal Fan at similar latitudes. This marked rise in SAR and a constant Himalayan-derived provenance necessitates a major restructuring of sediment routing in the Bengal-Nicobar submarine fan. This coincides with the inversion of the Eastern Himalayan Shillong Plateau and encroachment of the west-propagating Indo-Burmese wedge, which reduced continental accommodation space and increased sediment supply directly to the fan. Our results challenge a commonly held view that changes in sediment flux seen in the Bengal-Nicobar submarine fan were caused by discrete tectonic or climatic events acting on the Himalayan-Tibetan Plateau. Instead, an interplay of tectonic and climatic processes caused the fan system to develop by punctuated changes rather than gradual progradation.

  4. Radiation countermeasures from Himalayan herbs - an update

    International Nuclear Information System (INIS)

    Madhu Bala

    2012-01-01

    A successful radioprotector is the one, which essentially renders protection from the multi-organ dis-function syndrome (MODS) caused by the total body exposure to ionizing radiation. Our rationale is that and instead of a single molecule, a group of molecules/compounds working synergistically can combat the MODS more effectively. Plant extracts offer natural combinations of a plethora of compounds, which act through different mechanisms and are, therefore, the ideal choice. Plants of Himalayan regions have survived under extreme climatic conditions through millions of years and are expected to harbor a battery of anti-stress adaptive molecules offering survival benefits. Our group is actively engaged in developing composite herbal radioprotective preparations from Himalayan Plants. This group is working to develop radiation countermeasures by tapping the essential complex phytochemicals from the plants inhabiting extreme climatic zones of Himalayas. In our laboratory, systematic studies were undertaken to investigate some of these plants located at high altitude regions of Himalayas viz. Hippophae rhamnoides, Rhodiola imbricata and Podophylium hexandruin. The most effective preparation from each of these plants individually, could provide more than 80% survival benefit to the irradiated (10 Gy) mice population against zero per cent survival in non-drug treated irradiated (10 Gy) mice population. It was observed that whole extracts of plant provided much better protection than the partial extracts/fractions. It was also observed that some of the partial extracts/fractions although, provided much higher survival benefits, yet were found to be unsuitable for drug development due to much higher mutagenic and/or recombinogenic effects in comparison to the whole extracts, One of the preparations from leaves of Hippophae rhamnoides (drug) showed more than 90% survival benefits in the irradiated mice population. Only one time intra-peritoneal administration of the drug

  5. Structure and evolution of the drainage system of a Himalayan debris-covered glacier, and its relationship with patterns of mass loss

    Directory of Open Access Journals (Sweden)

    D. I. Benn

    2017-09-01

    Full Text Available We provide the first synoptic view of the drainage system of a Himalayan debris-covered glacier and its evolution through time, based on speleological exploration and satellite image analysis of Ngozumpa Glacier, Nepal. The drainage system has several linked components: (1 a seasonal subglacial drainage system below the upper ablation zone; (2 supraglacial channels, allowing efficient meltwater transport across parts of the upper ablation zone; (3 sub-marginal channels, allowing long-distance transport of meltwater; (4 perched ponds, which intermittently store meltwater prior to evacuation via the englacial drainage system; (5 englacial cut-and-closure conduits, which may undergo repeated cycles of abandonment and reactivation; and (6 a "base-level" lake system (Spillway Lake dammed behind the terminal moraine. The distribution and relative importance of these elements has evolved through time, in response to sustained negative mass balance. The area occupied by perched ponds has expanded upglacier at the expense of supraglacial channels, and Spillway Lake has grown as more of the glacier surface ablates to base level. Subsurface processes play a governing role in creating, maintaining, and shutting down exposures of ice at the glacier surface, with a major impact on spatial patterns and rates of surface mass loss. Comparison of our results with observations on other glaciers indicate that englacial drainage systems play a key role in the response of debris-covered glaciers to sustained periods of negative mass balance.

  6. Time-scales of erosion and weathering processes in the Himalayan river system: Element and isotope approach using the U-series

    International Nuclear Information System (INIS)

    Granet, M.

    2007-06-01

    The time-scales of erosion and weathering processes are key parameters which need to be determined to understand the response of the reliefs to external forcing like tectonics, climate and human activities. They were recovered by using U-series nuclides analyzed in sediments and suspended materials carried by the Himalayan rivers of the Ganges and Brahmaputra basins. In the Ganges basin, the time-scales of weathering determined from the study of coarse sediments carried by the Kali Gandaki range from several ky, where the uplift is located, to 350 ky. Such values indicate that the bed-rocks are in situ weathered for a long period before the weathering residual products get transported in the rivers as coarse sediments. At the outlet of the high range, these sediments are carried by the tributaries of the Ganges, the Gandak and Ghaghara, during a transfer period of about 100 ka. The study of the sediments at the outlet of the Brahmaputra tributaries allows to propose time-scales of weathering ranging from 110 to 270 ky. Such long periods confirm that during their transfer in the plains, the sediments are temporarily trapped at several places in the basins. In the Ganges and Brahmaputra rivers, the time-scales of sedimentary transfer are 575 and 160 ky, respectively. These values, which are of the same order as their response times, are much longer than the timescales of the Quaternary climate oscillations. It confirms the buffering action of the asiatic alluvial plains for the high-frequency sediment flux variations in response to external forcing in the chain. The study of suspended materials suggests that their chemical compositions result from the mixing of coarse river sediments with fine particles from various locations in the basin which are affected by vegetation recycling. By contrast to coarse sediments, the time-scales of transfer for the suspended materials are fast, e.g. a few ky, pointing the potential of U-series nuclides to assess particle transport

  7. Simulation of a Himalayan cloudburst event

    Indian Academy of Sciences (India)

    Intense rainfall often leads to floods and landslides in the Himalayan region even with rainfall amounts that are considered comparatively moderate over the plains; for example, 'cloudbursts', which are devastating convective phenomena producing sudden high-intensity rainfall (∼10 cm per hour) over a small area.

  8. The eastern Central Asian Orogenic Belt: formation and evolution

    Science.gov (United States)

    Xu, Bei; Xu, Wenliang

    2017-08-01

    The Central Asian Orogenic Belt (CAOB) extends from the northern Eurasian continent in the west via Mongolia, Inner Mongolia and northeast part of China to the Russia Far East in the east. It is characterized by complex trench-arc-basin subduction system, exotic terrane (microcontinents) accretion, massive generation of juvenile crust during the Neoproterozoic-Phanerozoic (e.g., Jahn et al., 2000, 2004; Sengör et al., 1993). A lot of papers about formation and evolution of the CAOB have been published and new field observations and geochemical data for key areas of the CAOB challenge to previous assessments. Several areas previously defined as juvenile are now shown to have mixed crustal compositions. For example, Kröner et al. (2014, in press) estimated that the distribution of various crustal provinces is truly juvenile crustal material ca. 20%, mixed crust ca. 30%, old crust ca. 50%,respectively, in the CAOB, similar to those in other accretionary orogens through Earth history. A two-stage model for the evolution of the CAOB has been suggested based on recent data from the Eastern Tianshan and Beishan (Gao et al., 2011; Su et al., 2011; Chen et al., 2016; Wang et al., 2017), which suggests the process of the formation and evolution of the CAOB includes closure of the Paleo Asian ocean (PAO), formation of orogenic belt before the late Paleozoic and crustal extension and magmatism resulted from plume upon the young orogenic belt after the late Paleozoic. This new model changes previous concept that the CAOB developed through the Paleozoic and is supported by recent researches on the eastern CAOB.

  9. Topographic evolution of orogens: The long term perspective

    Science.gov (United States)

    Robl, Jörg; Hergarten, Stefan; Prasicek, Günther

    2017-04-01

    The landscape of mountain ranges reflects the competition of tectonics and climate, that build up and destroy topography, respectively. While there is a broad consensus on the acting processes, there is a vital debate whether the topography of individual orogens reflects stages of growth, steady-state or decay. This debate is fuelled by the million-year time scales hampering direct observations on landscape evolution in mountain ranges, the superposition of various process patterns and the complex interactions among different processes. In this presentation we focus on orogen-scale landscape evolution based on time-dependent numerical models and explore model time series to constrain the development of mountain range topography during an orogenic cycle. The erosional long term response of rivers and hillslopes to uplift can be mathematically formalised by the stream power and mass diffusion equations, respectively, which enables us to describe the time-dependent evolution of topography in orogens. Based on a simple one-dimensional model consisting of two rivers separated by a watershed we explain the influence of uplift rate and rock erodibility on steady-state channel profiles and show the time-dependent development of the channel - drainage divide system. The effect of dynamic drainage network reorganization adds additional complexity and its effect on topography is explored on the basis of two-dimensional models. Further complexity is introduced by coupling a mechanical model (thin viscous sheet approach) describing continental collision, crustal thickening and topography formation with a stream power-based landscape evolution model. Model time series show the impact of crustal deformation on drainage networks and consequently on the evolution of mountain range topography (Robl et al., in review). All model outcomes, from simple one-dimensional to coupled two dimensional models are presented as movies featuring a high spatial and temporal resolution. Robl, J., S

  10. Orogenic, Ophiolitic, and Abyssal Peridotites

    Science.gov (United States)

    Bodinier, J.-L.; Godard, M.

    2003-12-01

    "Tectonically emplaced" mantle rocks include subcontinental, suboceanic, and subarc mantle rocks that were tectonically exhumed from the upper mantle and occur:(i) as dispersed ultramafic bodies, a few meters to kilometers in size, in suture zones and mountain belts (i.e., the "alpine," or "orogenic" peridotite massifs - De Roever (1957), Thayer (1960), Den Tex (1969));(ii) as the lower ultramafic section of large (tens of kilometers) ophiolite or island arc complexes, obducted on continental margins (e.g., the Oman Ophiolite and the Kohistan Arc Complex - Coleman (1971), Boudier and Coleman (1981), Burg et al. (1998));(iii) exhumed above the sea level in ocean basins (e.g., Zabargad Island in the Red Sea, St. Paul's islets in the Atlantic and Macquarie Island in the southwestern Pacific - Tilley (1947), Melson et al. (1967), Varne and Rubenach (1972), Bonatti et al. (1981)).The "abyssal peridotites" are samples from the oceanic mantle that were dredged on the ocean floor, or recovered from drill cores (e.g., Bonatti et al., 1974; Prinz et al., 1976; Hamlyn and Bonatti, 1980).Altogether, tectonically emplaced and abyssal mantle rocks provide insights into upper mantle compositions and processes that are complementary to the information conveyed by mantle xenoliths (See Chapter 2.05). They provide coverage to vast regions of the Earth's upper mantle that are sparsely sampled by mantle xenoliths, particularly in the ocean basins and beneath passive continental margins, back-arc basins, and oceanic island arcs.Compared with mantle xenoliths, a disadvantage of some tectonically emplaced mantle rocks for representing mantle compositions is that their original geodynamic setting is not exactly known and their significance is sometimes a subject of speculation. For instance, the provenance of orogenic lherzolite massifs (subcontinental lithosphere versus upwelling asthenosphere) is still debated (Menzies and Dupuy, 1991, and references herein), as is the original setting

  11. Tectonic stress evolution in the Pan-African Lufilian Arc and its foreland (Katanga, DRC): orogenic bending, late orogenic extensional collapse and transition to rifting

    Science.gov (United States)

    Kipata, M. L.; Delvaux, D.; Sebagenzi, M. N.; Cailteux, J.; Sintubin, M.

    2012-04-01

    Between the paroxysm of the Lufilian orogeny at ~ 550 Ma and the late Neogene to Quaternary development of the south-western branch of the East African rift system, the tectonic evolution of the Lufilian Arc and Kundelungu foreland in the Katanga region of the Democratic Republic of Congo remains poorly unknown although it caused important Cu-dominated mineral remobilizations leading to world-class ore deposits. This long period is essentially characterized by brittle tectonic deformations that have been investigated by field studies in open mines spread over the entire arc and foreland. Paleostress tensors were computed for a database of 1450 fault-slip data by interactive stress tensor inversion and data subset separation, and the relative succession of 8 brittle deformation events established. The oldest brittle structures observed are related to the Lufilian brittle compressional climax (stage 1). They have been re-oriented during the orogenic bending that led to the arcuate shape of the belt. Unfolding the stress directions from the first stage allows to reconstruct a consistent NE-SW direction of compression for this stage. Constrictional deformation occurred in the central part of the arc, probably during orogenic bending (Stage 2). After the orogenic bending, a sequence of 3 deformation stages marks the progressive onset of late-orogenic extension: strike-slip deformations (stages 3-4) and late-orogenic arc-parallel extension (stage 5). It is proposed that these 3 stages correspond to orogenic collapse. In early Mesozoic, NW-SE compression was induced by a transpressional inversion, interpreted as induced by far-field stresses generated at the southern active margin of Gondwana (stage 6). Since then, this region was affected by rift-related extension, successively in a NE-SW direction (stage 7, Tanganyika trend) and NW-SE direction (stage 8, Moero trend).

  12. Potential flood volume of Himalayan glacial lakes

    Directory of Open Access Journals (Sweden)

    K. Fujita

    2013-07-01

    Full Text Available Glacial lakes are potentially dangerous sources of glacial lake outburst floods (GLOFs, and represent a serious natural hazard in Himalayan countries. Despite the development of various indices aimed at determining the outburst probability, an objective evaluation of the thousands of Himalayan glacial lakes has yet to be completed. In this study we propose a single index, based on the depression angle from the lakeshore, which allows the lakes to be assessed using remotely sensed digital elevation models (DEMs. We test our approach on five lakes in Nepal, Bhutan, and Tibet using images taken by the declassified Hexagon KH-9 satellite before these lakes experienced an outburst flood. All five lakes had a steep lakefront area (SLA, on which a depression angle was steeper than our proposed threshold of 10° before the GLOF event, but the SLA was no longer evident after the events. We further calculated the potential flood volume (PFV; i.e., the maximum volume of floodwater that could be released if the lake surface was lowered sufficiently to eradicate the SLA. This approach guarantees repeatability to assess the possibility of GLOF hazards because it requires no particular expertise to carry out, though the PFV does not quantify the GLOF risk. We calculated PFVs for more than 2000 Himalayan glacial lakes using visible band images and DEMs of ASTER data. The PFV distribution follows a power-law function. We found that 794 lakes did not have an SLA, and consequently had a PFV of zero, while we also identified 49 lakes with PFVs of over 10 million m3, which is a comparable volume to that of recorded major GLOFs. This PFV approach allows us to preliminarily identify and prioritize those Himalayan glacial lakes that require further detailed investigation on GLOF hazards and risk.

  13. Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements.

    Science.gov (United States)

    Singh, Ajit; Thomsen, Kristina J; Sinha, Rajiv; Buylaert, Jan-Pieter; Carter, Andrew; Mark, Darren F; Mason, Philippa J; Densmore, Alexander L; Murray, Andrew S; Jain, Mayank; Paul, Debajyoti; Gupta, Sanjeev

    2017-11-28

    Urbanism in the Bronze-age Indus Civilisation (~4.6-3.9 thousand years before the present, ka) has been linked to water resources provided by large Himalayan river systems, although the largest concentrations of urban-scale Indus settlements are located far from extant Himalayan rivers. Here we analyse the sedimentary architecture, chronology and provenance of a major palaeochannel associated with many of these settlements. We show that the palaeochannel is a former course of the Sutlej River, the third largest of the present-day Himalayan rivers. Using optically stimulated luminescence dating of sand grains, we demonstrate that flow of the Sutlej in this course terminated considerably earlier than Indus occupation, with diversion to its present course complete shortly after ~8 ka. Indus urban settlements thus developed along an abandoned river valley rather than an active Himalayan river. Confinement of the Sutlej to its present incised course after ~8 ka likely reduced its propensity to re-route frequently thus enabling long-term stability for Indus settlements sited along the relict palaeochannel.

  14. Role of glaciers in watershed hydrology: a preliminary study of a "Himalayan catchment"

    Directory of Open Access Journals (Sweden)

    R. J. Thayyen

    2010-02-01

    Full Text Available A large number of Himalayan glacier catchments are under the influence of humid climate with snowfall in winter (November–April and south-west monsoon in summer (June–September dominating the regional hydrology. Such catchments are defined as "Himalayan catchment", where the glacier meltwater contributes to the river flow during the period of annual high flows produced by the monsoon. The winter snow dominated Alpine catchments of the Kashmir and Karakoram region and cold-arid regions of the Ladakh mountain range are the other major glacio-hydrological regimes identified in the region. Factors influencing the river flow variations in a "Himalayan catchment" were studied in a micro-scale glacier catchment in the Garhwal Himalaya, covering an area of 77.8 km2. Three hydrometric stations were established at different altitudes along the Din Gad stream and discharge was monitored during the summer ablation period from 1998 to 2004, with an exception in 2002. These data have been analysed along with winter/summer precipitation, temperature and mass balance data of the Dokriani glacier to study the role of glacier and precipitation in determining runoff variations along the stream continuum from the glacier snout to 2360 m a.s.l. The study shows that the inter-annual runoff variation in a "Himalayan catchment" is linked with precipitation rather than mass balance changes of the glacier. This study also indicates that the warming induced an initial increase of glacier runoff and subsequent decline as suggested by the IPCC (2007 is restricted to the glacier degradation-derived component in a precipitation dominant Himalayan catchment and cannot be translated as river flow response. The preliminary assessment suggests that the "Himalayan catchment" could experience higher river flows and positive glacier mass balance regime together in association with strong monsoon. The important role of glaciers in this precipitation dominant system is

  15. Deformation mechanisms in the frontal Lesser Himalayan Duplex in ...

    Indian Academy of Sciences (India)

    Figure 2. Tectonic map of the part of Darjiling–Sikkim. Himalaya around Rangit window. GHC, Greater Himalayan crystalline complex; LHS, Lesser Himalayan sequence; GWS,. Gondwana ... port parallel N–S section to study the Jorthang horse located in the ... pressure solution planes (Ps Pl) parallel to the axial plane of.

  16. Assessment of CORDEX-South Asia experiments for monsoonal precipitation over Himalayan region for future climate

    Science.gov (United States)

    Choudhary, A.; Dimri, A. P.

    2018-04-01

    Precipitation is one of the important climatic indicators in the global climate system. Probable changes in monsoonal (June, July, August and September; hereafter JJAS) mean precipitation in the Himalayan region for three different greenhouse gas emission scenarios (i.e. representative concentration pathways or RCPs) and two future time slices (near and far) are estimated from a set of regional climate simulations performed under Coordinated Regional Climate Downscaling Experiment-South Asia (CORDEX-SA) project. For each of the CORDEX-SA simulations and their ensemble, projections of near future (2020-2049) and far future (2070-2099) precipitation climatology with respect to corresponding present climate (1970-2005) over Himalayan region are presented. The variability existing over each of the future time slices is compared with the present climate variability to determine the future changes in inter annual fluctuations of monsoonal mean precipitation. The long-term (1970-2099) trend (mm/day/year) of monsoonal mean precipitation spatially distributed as well as averaged over Himalayan region is analyzed to detect any change across twenty-first century as well as to assess model uncertainty in simulating the precipitation changes over this period. The altitudinal distribution of difference in trend of future precipitation from present climate existing over each of the time slices is also studied to understand any elevation dependency of change in precipitation pattern. Except for a part of the Hindu-Kush area in western Himalayan region which shows drier condition, the CORDEX-SA experiments project in general wetter/drier conditions in near future for western/eastern Himalayan region, a scenario which gets further intensified in far future. Although, a gradually increasing precipitation trend is seen throughout the twenty-first century in carbon intensive scenarios, the distribution of trend with elevation presents a very complex picture with lower elevations

  17. Assessment of CORDEX-South Asia experiments for monsoonal precipitation over Himalayan region for future climate

    Science.gov (United States)

    Choudhary, A.; Dimri, A. P.

    2017-07-01

    Precipitation is one of the important climatic indicators in the global climate system. Probable changes in monsoonal (June, July, August and September; hereafter JJAS) mean precipitation in the Himalayan region for three different greenhouse gas emission scenarios (i.e. representative concentration pathways or RCPs) and two future time slices (near and far) are estimated from a set of regional climate simulations performed under Coordinated Regional Climate Downscaling Experiment-South Asia (CORDEX-SA) project. For each of the CORDEX-SA simulations and their ensemble, projections of near future (2020-2049) and far future (2070-2099) precipitation climatology with respect to corresponding present climate (1970-2005) over Himalayan region are presented. The variability existing over each of the future time slices is compared with the present climate variability to determine the future changes in inter annual fluctuations of monsoonal mean precipitation. The long-term (1970-2099) trend (mm/day/year) of monsoonal mean precipitation spatially distributed as well as averaged over Himalayan region is analyzed to detect any change across twenty-first century as well as to assess model uncertainty in simulating the precipitation changes over this period. The altitudinal distribution of difference in trend of future precipitation from present climate existing over each of the time slices is also studied to understand any elevation dependency of change in precipitation pattern. Except for a part of the Hindu-Kush area in western Himalayan region which shows drier condition, the CORDEX-SA experiments project in general wetter/drier conditions in near future for western/eastern Himalayan region, a scenario which gets further intensified in far future. Although, a gradually increasing precipitation trend is seen throughout the twenty-first century in carbon intensive scenarios, the distribution of trend with elevation presents a very complex picture with lower elevations

  18. GEOPHYSICS. Layered deformation in the Taiwan orogen.

    Science.gov (United States)

    Huang, T-Y; Gung, Y; Kuo, B-Y; Chiao, L-Y; Chen, Y-N

    2015-08-14

    The underthrusting of continental crust during mountain building is an issue of debate for orogens at convergent continental margins. We report three-dimensional seismic anisotropic tomography of Taiwan that shows a nearly 90° rotation of anisotropic fabrics across a 10- to 20-kilometer depth, consistent with the presence of two layers of deformation. The upper crust is dominated by collision-related compressional deformation, whereas the lower crust of Taiwan, mostly the crust of the subducted Eurasian plate, is dominated by convergence-parallel shear deformation. We interpret this lower crustal shearing as driven by the continuous sinking of the Eurasian mantle lithosphere when the surface of the subducted plate is coupled with the orogen. The two-layer deformation clearly defines the role of subduction in the formation of the Taiwan mountain belt. Copyright © 2015, American Association for the Advancement of Science.

  19. Himalayan Mountain Range, India/China

    Science.gov (United States)

    1981-01-01

    The frontier between India (Kashmir) and China (Tibet) (33.5N, 79.5E) lies across the narrow land bridge between the two lakes near the center of this photo. Many of the peaks in this region of the Karakoram and Latakh ranges of the Himalayan Mountains, exceed 20,000 ft. making it one of the most remote regions of the Earth. The large end lake is the Kako in China and the long narrow lake is the Pangong in India.

  20. Molecular characterization of the Himalayan mink

    DEFF Research Database (Denmark)

    Benkel, Bernhard F.; Rouvinen-Watt, Kirsti; Farid, Hossain

    2009-01-01

    the hypothesis that the color pattern in question-light-colored body with dark-colored points (ears, face, tail, and feet)-is due to a mutation in the melanin-producing enzyme tyrosinase (TYR) that results in temperature-sensitive pigment production. Our study shows that marbled mink carry a mutation in exon 4......A rare color variant of the American mink (Neovison vison), discovered on a ranch in Nova Scotia and referred to as the "marbled" variety, carries a distinctive pigment distribution pattern resembling that found in some other species, e.g., the Siamese cat and the Himalayan mouse. We tested...

  1. Constraints on the geometry and recent evolution of the Main Himalayan Thrust in western Nepal from U-Th/He thermochronology

    Science.gov (United States)

    Harvey, J. E.; Burbank, D.; Hourigan, J. K.

    2014-12-01

    Recent work has revealed an along-strike topographic discontinuity in the Himalaya of western Nepal. We interpret this discontinuity as reflecting a change in geometry and architecture of the Main Himalayan Thrust (MHT). Specifically, the ~4-km high Greater Himalayan mountainfront that characterizes much of the central Himalaya diffuses into a gentler, two-step mountainfront in western Nepal. This observation suggests that the belt of rapid rock uplift that has been identified along much of the range front (commonly interpreted as a result of of transport of the orogenic wedge over a mid-crustal ramp in the MHT) widens or bifurcates into two bands in western Nepal. This tectonic discontinuity could perhaps be explained by recent southward migration of the Main Himalayan Thrust ramp in western Nepal, a hypothesis supported by the presence of several high-elevation, low-relief landscape remnants between the two topographic steps. In an effort to test the above hypothesis, we will present a suite of apatite and zircon U-Th/He cooling ages collected along several relief transects in western Nepal. Transects were situated such that they will capture exhumation histories above the southern and northern topographic steps as well as the high elevation, low-relief plateau between them. Exhumation rates and histories will be interpreted with the aid of thermo-kinematic modeling. This work will: 1) provide important constraints on possible tectonic models explaining the anomalous topography of western Nepal; 2) allow comparison with cooling ages collected along strike to the NW and E; and 3) ultimately provide insight into the mechanisms of orogen growth and evolution. If this work confirms the presence of a bifurcation or recent forward propagation of the MHT in western Nepal, it will have key implications for the seismic hazard presented by the plate boundary as well as for our understanding of the longevity of mid-crustal structures within the Himalaya.

  2. Craton-derived alluvium as a major sediment source in the Himalayan Foreland Basin of India

    DEFF Research Database (Denmark)

    Sinha, R.; Kettanah, Y.; Gibling, M.R.

    2009-01-01

    foreland basin may reflect avulsion of orogenic rivers along the craton margin, in addition to dynamic transverse drainage systems from the Himalaya that pushed the axial drainage to the basin's feather edge. The wide spread of cratonic sediment would have been enhanced by slow subsidence in the distal...

  3. Accretionary and collisional orogenesis in the south domain of the western Central Asian Orogenic Belt (CAOB)

    Science.gov (United States)

    Cai, Keda; Long, Xiaoping; Chen, Huayong; Sun, Min; Xiao, Wenjiao

    2018-03-01

    The Central Asian Orogenic Belt (CAOB) was the result of long-lived multi-stage tectonic evolution, including Proterozoic to Paleozoic accretion and collision, Mesozoic intracontinental modification, and Cenozoic rapid deformation and uplift. The accretionary and collisional orogenesis of its early history generated a huge orogenic collage consisting of diverse tectonic units including island arcs, ophiolites, accretionary prisms, seamounts, oceanic plateaus and micro-continents. These incorporated orogenic components preserved valuable detailed information on orogenic process and continental crust growth, which make the CAOB a key region to understanding of continental evolution, mantle-crust interaction and associated mineralization. The western CAOB refers to the west region in North Xinjiang of China and circum-Balkash of Kazakhstan, with occurrences of the spectacular Kazakhstan orocline and its surrounding mountain belts. Because orogenic fabrics of this part mostly preserve their original features caused by the interactions among the southern Siberian active margin in the north and the Tarim Craton in the south, the western CAOB can be regarded as an ideal region to study the processes of the accretionary and collisional orogenesis and associated mineralization. Since a large number of researchers have been working on this region, research advances bloom strikingly in a short-time period. Therefore, we, in this special issue, focus on these new study advances on the south domain of the western CAOB, including the Kazakhstan collage system, Tianshan orogenic belt and Beishan region, and it is anticipated that this issue can draw more attention from the international research groups to be interested in the studies on orogenesis of the CAOB.

  4. The giant Jiaodong gold province: The key to a unified model for orogenic gold deposits?

    Directory of Open Access Journals (Sweden)

    David I. Groves

    2016-05-01

    Full Text Available Although the term orogenic gold deposit has been widely accepted for all gold-only lode-gold deposits, with the exception of Carlin-type deposits and rare intrusion-related gold systems, there has been continuing debate on their genesis. Early syngenetic models and hydrothermal models dominated by meteoric fluids are now clearly unacceptable. Magmatic-hydrothermal models fail to explain the genesis of orogenic gold deposits because of the lack of consistent spatially – associated granitic intrusions and inconsistent temporal relationships. The most plausible, and widely accepted, models involve metamorphic fluids, but the source of these fluids is hotly debated. Sources within deeper segments of the supracrustal successions hosting the deposits, the underlying continental crust, and subducted oceanic lithosphere and its overlying sediment wedge all have their proponents. The orogenic gold deposits of the giant Jiaodong gold province of China, in the delaminated North China Craton, contain ca. 120 Ma gold deposits in Precambrian crust that was metamorphosed over 2000 million years prior to gold mineralization. The only realistic source of fluid and gold is a subducted oceanic slab with its overlying sulfide-rich sedimentary package, or the associated mantle wedge. This could be viewed as an exception to a general metamorphic model where orogenic gold has been derived during greenschist- to amphibolite-facies metamorphism of supracrustal rocks: basaltic rocks in the Precambrian and sedimentary rocks in the Phanerozoic. Alternatively, if a holistic view is taken, Jiaodong can be considered the key orogenic gold province for a unified model in which gold is derived from late-orogenic metamorphic devolatilization of stalled subduction slabs and oceanic sediments throughout Earth history. The latter model satisfies all geological, geochronological, isotopic and geochemical constraints but the precise mechanisms of auriferous fluid release, like many

  5. The Himalayan Seismogenic Zone: A New Frontier for Earthquake Research

    Science.gov (United States)

    Brown, Larry; Hubbard, Judith; Karplus, Marianne; Klemperer, Simon; Sato, Hiroshi

    2016-04-01

    The Mw 7.8 Gorkha, Nepal, earthquake that occurred on April 25 of this year was a dramatic reminder that great earthquakes are not restricted to the large seismogenic zones associated with subduction of oceanic lithosphere. Not only does Himalayan seismogenesis represents important scientific and societal issues in its own right, it constitutes a reference for evaluating general models of the earthquake cycle derived from the studies of the oceanic subduction systems. This presentation reports results of a Mini-Workshop sponsored by the GeoPrisms project that was held in conjunction with the American Geophysical Union on December 15, 2015, designed to organize a new initiative to study the great Himalaya earthquake machine. The Himalayan seismogenic zone shares with its oceanic counterparts a number of fundamental questions, including: a) What controls the updip and downdip limits of rupture? b) What controls the lateral segmentation of rupture zones (and hence magnitude)? c) What is the role of fluids in facilitating slip and or rupture? d) What nucleates rupture (e..g. asperities?)? e) What physical properties can be monitored as precursors to future events? f) How effectively can the radiation pattern of future events be modeled? g) How can a better understanding of Himalayan rupture be translated into more cost effective preparations for the next major event in this region? However the underthrusting of continental, as opposed to oceanic, lithosphere in the Himalayas frames these questions in a very different context: h) How does the greater thickness and weaker rheology of continental crust/lithosphere affect locking of the seismogenic zone? i) How does the different thermal structure of continental vs oceanic crust affect earthquake geodynamics? j) Are fluids a significant factor in intercontinental thrusting? k) How does the basement morphology of underthrust continental crust affect locking/creep, and how does it differ from the oceanic case? l) What is the

  6. Brittle tectonic history document the late- to post-orogenic evolution in the Lufilian Arc, RDCongo

    Science.gov (United States)

    Kipata, Louis; Delvaux, Damien; Ntabwoba Sebagenzi, Mwene; Cailteux, Jean-Jacques; Sintubin, Manuel

    2013-04-01

    Pan-African orogenic processes in Centra Africa involve intracontinental collision but also late-orogenic and intraplate processes that occurred in dominantly brittle conditions and can be documented by fault kinematic analysis and paleostress reconstructions. The Congo and Tanzania cratons in Central Africa are surrounded by Pan-African belts orogenic belts which all entered almost synchronously in collision stage in the early Paleozoic. While their tectonic history up to the collision stage is increasingly better documented by ductile deformation and metamorphic studies, their late evolution remain poorly known as soon as they enter in the brittle deformation regime. This results in an incomplete understanding of the orogenic processes, especially when the transition from ductile to the brittle regime occurred at the end of the orogenic compression. In this case, the last compressional stages and the entire late orogenic extension and extensional collapse stages remain undocumented. This is the case for the Lufilian orogeny which developed along the southern margin of the Congo Craton in Central Africa during the pan-African and was marked by a collisional event with crustal thickening and white schist formation at 550-530 Ma. The Lufilian Arc which forms the external part of the Lufilian orogeny developed as an arcuate fold-and-thrust belt. Its foreland is formed by the Kundelungu plateau, between the Bangweulu block and the Kibaran belt. This entire region is also tectonically active, as part of the incipient SW branch of the East African rift system. The long period between the paroxysm of the Lufilian orogeny and the late Neogene to Quaternary rifting has been investigated by fault-kinematic analysis and paleostress reconstruction in open mines spread over the entire arc and foreland. Paleostress tensors were computed from 23 sites totaling 1900 fault-slip data by interactive stress tensor inversion and data subset separation, and a succession of 8 brittle

  7. Besshi-type mineral systems in the Palaeoproterozoic Bryah Rift-Basin, Capricorn Orogen, Western Australia: Implications for tectonic setting and geodynamic evolution

    Directory of Open Access Journals (Sweden)

    Franco Pirajno

    2016-05-01

    Full Text Available In this contribution we use VMS mineral systems in the Bryah rift-basin to constrain the tectonic setting of the widespread mafic and ultramafic magmatism that characterises the rift-basin in question. Two distinct, but temporally closely associated, lithostratigraphic sequences, Narracoota and Karalundi Formations, are discussed. The Karalundi Formation is the main host of VMS mineral systems in the region. The Karalundi Formation consists of turbiditic and immature clastic sediments, which are locally intercalated with basaltic hyaloclastites, dolerites and banded jaspilites. We propose that the basaltic hyaloclastites, dolerites and clastics and jaspilites rocks, form a distinct unit of the Karalundi Formation, named Noonyereena Member. The VMS mineral systems occur near the north-east trending Jenkin Fault and comprise the giant and world-class DeGrussa and the Red Bore deposits. The nature of these deposits and their intimate association with terrigenous clastic rocks and dominantly marine mafic volcanic and subvolcanic rocks, as well as the common development of peperitic margins, are considered indicative of a Besshi-type environment, similar to that of present-day Gulf of California. Our Re-Os age data from a primary pyrite yielded a mean model age of 2012 ± 48 Ma, which coincides (within error with recent published Re-Os data (Hawke et al., 2015 and confirms the timing of the proposed geodynamic evolution. We propose a geodynamic model that attempts to explain the presence of the Narracoota and Karalundi Formations as the result of mantle plume activity, which began with early uplift of continental crust with intraplate volcanism, followed by early stages of rifting with the deposition of the Karalundi Formation (and Noonyereena Member, which led to the formation of Besshi-type VMS deposits. With on-going mantle plume activity and early stages of continental separation, an oceanic plateau was formed and is now represented by mafic

  8. Rifts, orogens, cratons, and global tectonics: Introduction

    Directory of Open Access Journals (Sweden)

    S. V. Rasskazov

    2017-01-01

    Full Text Available A key role in developing the Earth theory is played by comparative studies of orogens, rifts, and platforms in the equatorial, middle and high latitudes of Asia and the adjacent Arctic regions. The modern shape of the planet’s triaxial asymmetrical cardioid ellipsoid results from its latest (Late Phanerozoic geodynamic evolution that began in Arctic and then commenced in Asia. At this stage, mechanisms of the lithosphere extension and compression, combined with extension, were launched in Arctic and Asia, respectively. The special issue of Geodynamics & Tectonophysics presents papers on this topic.

  9. Metamorphic complexes in accretionary orogens: Insights from the Beishan collage, southern Central Asian Orogenic Belt

    Science.gov (United States)

    Song, Dongfang; Xiao, Wenjiao; Windley, Brian F.; Han, Chunming; Yang, Lei

    2016-10-01

    The sources of ancient zircons and the tectonic attributions and origins of metamorphic complexes in Phanerozoic accretionary orogens have long been difficult issues. Situated between the Tianshan and Inner Mongolia orogens, the Beishan orogenic collage (BOC) plays a pivotal role in understanding the accretionary processes of the southern Central Asian Orogenic Belt (CAOB), particularly the extensive metamorphic and high-strained complexes on the southern margin. Despite their importance in understanding the basic architecture of the southern CAOB, little consensus has been reached on their ages and origins. Our new structural, LA-ICP-MS zircon U-Pb and Hf isotopic data from the Baidunzi, Shibandun, Qiaowan and Wutongjing metamorphic complexes resolve current controversial relations. The metamorphic complexes have varied lithologies and structures. Detrital zircons from five para-metamorphic rocks yield predominantly Phanerozoic ages with single major peaks at ca. 276 Ma, 286 Ma, 427 Ma, 428 Ma and 461 Ma. Two orthogneisses have weighted mean ages of 294 ± 2 Ma and 304 ± 2 Ma with no Precambrian inherited zircons. Most Phanerozoic zircons show positive εHf(t) values indicating significant crustal growth in the Ordovician, Silurian and Permian. The imbricated fold-thrust deformation style combined with diagnostic zircon U-Pb-Hf isotopic data demonstrate that the metamorphic rocks developed in a subduction-accretion setting on an arc or active continental margin. This setting and conclusion are supported by the nearby occurrence of Ordovician-Silurian adakites, Nb-rich basalts, Carboniferous-Permian ophiolitic mélanges, and trench-type turbidites. Current data do not support the presence of a widespread Precambrian basement in the evolution of the BOC; the accretionary processes may have continued to the early Permian in this part of the CAOB. These relationships have meaningful implications for the interpretation of the tectonic attributions and origins of other

  10. Differential behaviour of a Lesser Himalayan watershed in extreme ...

    Indian Academy of Sciences (India)

    Author Affiliations. Pankaj Chauhan1 Nilendu Singh1 Devi Datt Chauniyal2 Rajeev S Ahluwalia1 Mohit Singhal1. Wadia Institute of Himalayan Geology, Dehradun 248 001, India. School of Earth Science, HNB Garhwal University, Srinagar 246 174, India.

  11. Sporotrichosis in sub-himalayan India.

    Directory of Open Access Journals (Sweden)

    Santwana Verma

    Full Text Available Sporotrichosis is endemic in the Sub-Himalayan belt, which ranges from the northern to the north-eastern Indian subcontinent. Similar to many parts of the developing world, sporotrichosis is commonly recognized clinically in this region however consolidated epidemiological data is lacking. We report epidemiological, clinical and microbiological data from a hundred culture positive cases of sporotrichosis. Out of 305 clinically suspicious cases of sporotrichosis, a total of 100 isolates were identified as Sporothrix schenckii species complex (S. schenckii on culture. Out of the culture proven cases 71% of the cases presented with lymphocutaneous type of lesions while 28% had fixed localized type and 1% had disseminated sporotrichosis. Presentation with lesions on hands was most frequently seen in 32% with arm (23% and face (21% in that sequence. The male to female ratio was 1∶1.27. Age ranged from 1 ½ years to 88 years. Mean age was 43.25 years. Disease was predominantly seen in the fourth to sixth decade of life with 58% cases between 31 and 60 years of age. Since the first report from the region there has been a steady rise in the number of cases of sporotrichosis. Seasonal trends reveal that most of the patients visited for consultation in the beginning of the year between March and April. This is the first study, from the most endemic region of the Sub-Himalayan belt, to delve into epidemiological and clinical details of such a large number of culture proven cases over a period of more than eighteen years which would help in the understanding of the local disease pattern of sporotrichosis.

  12. Granite ascent and emplacement during contractional deformation in convergent orogens

    Science.gov (United States)

    Brown, Michael; Solar, Gary S.

    1998-09-01

    Based on a case study in the Central Maine Belt of west-central Maine, U.S.A., it is proposed that crustal-scale shear zone systems provide an effective focussing mechanism for transfer of granite melt through the crust in convergent orogens. During contractional deformation, flow of melt in crustal materials at depths below the brittle-plastic transition is coupled with plastic deformation of these materials. The flow is driven by pressure gradients generated by buoyancy forces and tectonic stresses. Within the oblique-reverse Central Maine Belt shear zone system, stromatic migmatite and concordant to weakly discordant irregular granite sheets occur in zones of higher strain, which suggests percolative flow of melt to form the migmatite leucosomes and viscous flow of melt channelized in sheet-like bodies, possibly along fractures. Cyclic fluctuations of melt pressure may cause instantaneous changes in the effective permeability of the flow network if self-propagating melt-filled tensile and/or dilatant shear fractures are produced due to melt-enhanced embrittlement. Inhomogeneous migmatite and schlieric granite occur in zones of lower strain, which suggests migration of partially-molten material through these zones en masse by granular flow, and channelized flow of melt carrying entrained residue. Founded on the Central Maine Belt case study, we develop a model of melt extraction and ascent using the driving forces, stress conditions and crustal rheologies in convergent, especially transpressive orogens. Ascent of melt becomes inhibited with decreasing depth as the solidus is approached. For intermediate a(H 2O) muscovite-dehydration melting, the water-saturated solidus occurs between 400 and 200 MPa, near the brittle-plastic transition during high- T-low- P metamorphism, where the balance of forces favors (sub-) horizontal fracture propagation. Emplacement of melt may be accommodated by ductile flow and/or stoping of wall rock, and inflation may be accommodated

  13. MESO-NEOPROTEROZOIC GRENVILLE-SVECONORWEGIAN INTRACONTINENTAL OROGEN: HISTORY, TECTONICS, GEODYNAMICS

    Directory of Open Access Journals (Sweden)

    M. V. Mints

    2017-01-01

    the high-pressure amphibolite facies near Allochthon Boundary Thrust showing an inverted metamorphic zoning. High-pressure granulite-facies metamorphism is characteristic of Sveconorwegian sector; and high-temperature eclogites are observed locally at the base of the allochthonous complexes and within the paraautochthonous complexes. A distinctive feature of GNSO is the abundant occurrence of specific intrusive magmatism. Massifs of anorthosite-mangerite-charnockite-granite (AMCG and anorthosite-rapakivi granite (ARG complexes formed 1.8–1.5 Ga ago frame the orogen as a wide arc. In the internal region of GSNO, these complexes were formed successively at 1.16–1.13, 1.09–1.05, 0.99–0.96, and 0.93–0.92 Ga. Later on, after the intrusion, the massifs unevenly underwent granulite-facies metamorphism. The high-temperature magmatism and metamorphism, numerous repeated thermal pulses and enormous crustal body that underwent high-temperature transformation point to a mantle plume as the most adequate source of thermal energy. The model of intracontinental development of GSNO comes into conflict with popular ideas, which assume origination of this orogen as a result of the collision and welding of the formerly distant continents (Laurentia, Baltica and Amazonia, which, as suggested, completed the assembly of Rodinia supercontinent. A conclusion is drawn that the concept of tectonic position and geodynamic evolution of GSNO, which is not a counterpart of the Tibet-Himalayan Orogen, should be revised.

  14. Late-orogenic mantle garnet pyroxenites evidence mantle refertilization during exhumation of orogenic belt

    Science.gov (United States)

    Chazot, G.; France, L.; Kornprobst, J.; Dallai, L.; Vannucci, R.

    2008-12-01

    The petrological and geochemical study of garnet bearing pyroxenites from four localities (FMC, Morocco, Jordan, Cameroon) demonstrates that these rocks are cumulates crystallised in the lithospheric mantle domain. Metamorphic reactions, exsolutions and trace elements WR analysis demonstrate that their crystallisation pressure ranges between 1 and 2GPa (30 to 60km). The elaboration of the PTt paths for the studied samples attests of important movements in the respective lithospheres. Replaced in the geodynamical contexts, the samples are interpreted to represent the crystallisation of melts formed during exhumation of orogenic domains. Radiogenic isotopes (Sr-Nd) show that in a very same region, the samples are isotopicaly heterogeneous but are similar to the respective regional lithosphere. Initial isotopic ratios lead to propose that the FMC samples have crystallised at the end of the Hercynian orogen and that the samples from the other localities (Morocco, Jordan and Cameroon) have crystallised at the end of the Pan-African orogen. After recalculation at the crystallisation time, the isotopic compositions are in good agreement with the respective regional lithosphere ones and so samples of this study could represent the product of the melting of these lithospheres. The analyses of oxygen stable isotopes allow to precise the model; they show that twelve of the samples come from the melting of a lherzolitic mantle and that the four others come from the melting of a heterogeneous mantle formed of lherzolites and eclogites. The presence of some hydrous minerals such as amphiboles and micas and the trace elements WR analyses show that some of the samples were affected by a late metasomatic event. Results of our study show that thermal relaxation following orogenic events lead to the crystallisation of pyroxenites in the lithosphere. The presence of lage amounts of mantle pyroxenites in old orogenic regions confers physical and chemical particularities to these

  15. Lateral thinking: 2-D interpretation of thermochronology in convergent orogenic settings

    Science.gov (United States)

    Batt, Geoffrey E.; Brandon, Mark T.

    2002-05-01

    Lateral motion of material relative to the regional thermal and kinematic frameworks is important in the interpretation of thermochronology in convergent orogens. Although cooling ages in denuded settings are commonly linked to exhumation, such data are not related to instantaneous behavior but rather to an integration of the exhumation rates experienced between the thermochronological 'closure' at depth and subsequent exposure at the surface. The short spatial wavelength variation of thermal structure and denudation rate typical of orogenic regions thus renders thermochronometers sensitive to lateral motion during exhumation. The significance of this lateral motion varies in proportion with closure temperature, which controls the depth at which isotopic closure occurs, and hence, the range of time and length scales over which such data integrate sample histories. Different chronometers thus vary in the fundamental aspects of the orogenic character to which they are sensitive. Isotopic systems with high closure temperature are more sensitive to exhumation paths and the variation in denudation and thermal structure across a region, while those of lower closure temperature constrain shorter-term behaviour and more local conditions. Discounting lateral motion through an orogenic region and interpreting cooling ages purely in terms of vertical exhumation can produce ambiguous results because variation in the cooling rate can result from either change in kinematics over time or the translation of samples through spatially varying conditions. Resolving this ambiguity requires explicit consideration of the physical and thermal framework experienced by samples during their exhumation. This can be best achieved through numerical simulations coupling kinematic deformation to thermal evolution. Such an approach allows the thermochronological implications of different kinematic scenarios to be tested, and thus provides an important means of assessing the contribution of

  16. Part I: Neoacadian to Alleghanian foreland basin development and provenance in the central appalachian orogen, pine mountain thrust sheet Part II: Structural configuration of a modified Mesozoic to Cenozoic forearc basin system, south-central Alaska

    Science.gov (United States)

    Robertson, Peter Benjamin

    . Four samples of Lower Mississippian to Middle Pennsylvanian sandstone were collected from the hanging wall (n = 3) and footwall (n = 1) of the Pine Mountain thrust sheet at Pound Gap to determine sediment provenance in this long-lived foreland basin system. Paleocurrent indicators considered in the context of the regional foreland basin system suggest transverse regional drainage during the development of Early and Late Mississippian delta complexes. Eustatic fall during the early stages of the Alleghanian orogeny to the east saw a shift in regional drainage with the development of a southwestward-flowing and axial braided river system in Early Pennsylvanian time followed by Middle Mississippian transgression of a fluvio-deltaic complex. Detrital zircon U-Pb age data from Lower Mississippian to Lower Pennsylvanian sandstone support regional interpretations of sediment sourcing from probably recycled foreland basin strata along the east Laurentian margin, whereas compositionally immature Middle Pennsylvanian sediment was sourced by a limited distribution of east Laurentia sources reflecting thrust belt migration into the adjacent foreland basin system during Alleghanian orogenesis. In addition, the stratigraphy of the foreland basin system in the central Appalachian basin is significantly different compared to the stratigraphic record that is typified for foreland basin systems and suggests that the Carboniferous Appalachian foreland basin system investigated in this study does not fit the typical foreland basin model that is used widely today for both ancient and modern systems. Possible factors that produce the observed discrepancies between the central Appalachian and typical foreland basin systems may include differences in the timing, type, and frequency of orogenic events leading to foreland basin development, related variations in the rheology of the underlying lithosphere, and whether forebulge migration is mechanically static or mobile. The Cordilleran margin

  17. Mantle refertilization and magmatism in old orogenic regions: The role of late-orogenic pyroxenites

    Science.gov (United States)

    France, Lydéric; Chazot, Gilles; Kornprobst, Jacques; Dallai, Luigi; Vannucci, Riccardo; Grégoire, Michel; Bertrand, Hervé; Boivin, Pierre

    2015-09-01

    Pyroxenites and garnet pyroxenites are mantle heterogeneities characterized by a lower solidus temperature than the enclosing peridotites; it follows that they are preferentially involved during magma genesis. Constraining their origin, composition, and the interactions they underwent during their subsequent evolution is therefore essential to discuss the sources of magmatism in a given area. Pyroxenites could represent either recycling of crustal rocks in mantle domains or mantle originated rocks (formed either by olivine consuming melt-rock reactions or by crystal fractionation). Petrological and geochemical (major and trace elements, Sr-Nd and O isotopes) features of xenoliths from various occurrences (French Massif-Central, Jordan, Morocco and Cameroon) show that these samples represent cumulates crystallized during melt percolation at mantle conditions. They formed in mantle domains at pressures of 1-2 GPa during post-collisional magmatism (possibly Hercynian for the French Massif-Central, and Panafrican for Morocco, Jordan and Cameroon). The thermal re-equilibration of lithospheric domains, typical of the late orogenic exhumation stages, is also recorded by the samples. Most of the samples display a metasomatic overprint that may be either inherited or likely linked to the recent volcanic activity that occurred in the investigated regions. The crystallization of pyroxenites during late orogenic events has implications for the subsequent evolution of the mantle domains. The presence of large amounts of mantle pyroxenites in old orogenic regions indeed imparts peculiar physical and chemical characteristics to these domains. Among others, the global solidus temperature of the whole lithospheric domain will be lowered; in turn, this implies that old orogenic regions are refertilized zones where magmatic activity would be enhanced.

  18. Understanding Himalayan extreme rainfall to inform disaster governance

    Science.gov (United States)

    Ek, M. B.; Kumar, A.

    2017-12-01

    The hydrological aspects of the Himalayan flooding events were investigated with the coupled atmospheric and Hydrological (WRF-LIS) modeling tool. The Convective storms occurring at the steep edge of broad high topography, such as the Rocky Mountains and Himalayas, are notorious for producing surprising and lethal flash floods. We investigated two recent Himalayan flood events (a) 2010 Ladakh flood: A flash flood and landslide in the Leh region of the Indus Valley in the Indian state of Jammu and Kashmir on 5-6 August 2010 resulted in hundreds of deaths and great property damage. (b) 2013 Uttrakhand flood: Over a three-day period in June 2013, approximately 500-1000 mm of rain fell over Uttarakhand and its river valleys as well as neighboring Nepal. The extensive precipitation and runoff led to devastating floods and landslides throughout the region and resulted in much destruction and loss of life (over 4,000 villages were affected, and the death toll exceeded 5,000). The Uttarakhand flood had characteristics in common with major 2013 floods in the Rocky Mountains in Colorado and Alberta. Our study examines the land-atmosphere interactions & cloud structure and dynamics of these flooding events in more detail, identifying the synoptic, mesoscale, convective, orographic, and land-surface components of the storm. We include satellite observations, ground-based radar imagery, and convection-permitting model simulations down to 1 km grid resolution to show the three-dimensional character of the precipitating cloud systems in more detail than previous studies. Our Land Information System (LIS) calculations suggest that soil moisture preconditioning by prior storms in the area in a vulnerable watershed is a hydrologic ingredient that should be taken into account along with the meteorological ingredients. In this regard, our results will be seen to reinforce the position taken by Doswell et al. (1996) that local forecasting of flood situations is ideally based on

  19. Sediment budget in a Himalayan Valley (Middle Kali Gandaki, Nepal)

    Science.gov (United States)

    Fort, M.; Cossart, E.

    2012-04-01

    Active mountains supply the largest sediment fluxes experienced on earth. At mountain range scale, sediment budgets are controlled by rock uplift and climate, hence by a wide range of erosion processes (detachment, transport and deposition), all operating within drainage basin units, with time and spatial patterns that indeed are quite complex at local scale. In the Himalayas, the sediment cascade is particularly efficient, as favoured by high, glaciated peaks, together with narrow valleys and steep hillslopes, in a monsoon-contrasted, climatic context. We focus on the Kali Gandaki valley, along the gorge section across Higher Himalaya (e.g. from Jomosom down to Tatopani). Along this reach, we identify sediment sources, sediment stores and sinks, and specifically consider hillslope interactions with valley floor at short and longer time scales, and their impact on sediment budgets and fluxes. We present a detailed sediment budget, constrained by available dates and/or relative chronology. Studied sites include rock-avalanches (Jomosom, Dhumpu), Pairothapla-Talbagar and Tatopani landslides, Ghatte khola debris fan, and terraces systems preserved at confluence sites along the lower slopes of the valley. On the basis of geomorphic surveys and mapping, and thanks to DEM facilities, we estimate the volume of each sedimentary unit, including lacustrine sediments trapped upstream of landslide and/or glacial dams. Debris volume eroded and/or deposited during the last decades is also calculated. Alternation of alluviation events and incision stages are then reconstructed, and their relation with sismo-tectonic and/or climatic triggering events suggested, according to the time scale considered. From our results it appears that if large landslides contribute significantly to the denudation history of active mountain range, more frequent, medium to small scales landslides are in fact of primary concern for Himalayan population. This conclusion suggests that in this very

  20. Tectonic controls of Holocene erosion in a glaciated orogen

    OpenAIRE

    Adams, Byron A.; Ehlers, Todd A.

    2018-01-01

    Recent work has highlighted a strong, worldwide, glacial impact of orogen erosion rates over the last 2 Ma. While it may be assumed that glaciers increased erosion rates when active, the degree to which past glaciations influence Holocene erosion rates through the adjustment of topography is not known. In this study, we investigate the influence of long-term tectonic and post-glacial topographic controls on erosion in a glaciated orogen, the Olympic Mountains, USA. We present 14 new 10Be and ...

  1. Structure of the Kaoko Belt, Namibia: progressive evolution of a classic transpressional orogen

    Science.gov (United States)

    Goscombe, Ben; Hand, Martin; Gray, David

    2003-07-01

    The Kaoko Belt portion of the Damara Orogen, Namibia, is the deeply eroded core of a sinistral transpressional orogen that has half-flower structure geometry centred on the major, 4-5-km-wide Purros Mylonite Zone. Formed between the Congo Craton in the east and Rio De La Plata Craton in Brazil, the Kaoko Belt represents the northern coastal arm of a triple junction within the Pan-African Orogenic System. Consisting of reworked Archaean, Palaeoproterozoic and Mesoproterozoic basement and a cover of Neoproterozoic Damara Sequence, the Kaoko Belt can be sub-divided structurally into three parallel NNW-trending zones. The Eastern Kaoko Zone comprises sub-greenschist facies shelf carbonates that have been uprightly folded. The Central Kaoko Zone contains a slope and deep basin facies succession that has experienced intense deformation, including pervasive reworking of basement into large-scale east-vergent nappes. The Western Kaoko Zone is predominantly deep basin facies of high metamorphic grade intruded by numerous granites. It has experienced intense wrench-style deformation with formation of upright isoclines and steep, crustal-scale shear zones. The Kaoko Belt evolved through three distinct phases of a protracted Pan-African Orogeny in the late Neoproterozoic to Cambrian. (1) An early Thermal Phase (M 1) was responsible for pervasive partial melting and granite emplacement in the Western Kaoko Zone from 656 Ma. (2) The Transpressional Phase produced the geometry of the belt by progressive sinistral shearing between 580 and 550 Ma. Deformation was continuously progressive through two stages and involved both temporal and spatial migration of deformation outwards towards the margin. The early strike-slip Wrench-Stage produced a high-strain L-S fabric by sub-horizontal transport. Deformation became progressively more transpressive, with high-angle convergence and flattening strains during the Convergent-Stage. In this stage, strike-slip movements evolved through

  2. Trading places: new economic geographies across Himalayan borderlands

    NARCIS (Netherlands)

    Harris, T.

    2013-01-01

    Major state-led infrastructural development projects in the Himalayan region have been underway for several years, such as the building of highways connecting Nepal and Tibet, the widening of roads throughout North Bengal, Sikkim, and Tibet, and the planning of extensions to the Beijing-Lhasa

  3. The hymenopterous pollinators of Himalayan foot hills of Pakistan ...

    African Journals Online (AJOL)

    Studies were undertaken to explore the diversity of hymenopterans pollinators from a diverse agroecosystems of Himalayan foot hills comprising the orchards of pome and stone fruits at different altitudes from 2200 to 3000 m from sea level. Field experiments were conducted on seven commercial fruit orchards at five ...

  4. Application of artificial neural networks in hydrological modeling: A case study of runoff simulation of a Himalayan glacier basin

    Science.gov (United States)

    Buch, A. M.; Narain, A.; Pandey, P. C.

    1994-01-01

    The simulation of runoff from a Himalayan Glacier basin using an Artificial Neural Network (ANN) is presented. The performance of the ANN model is found to be superior to the Energy Balance Model and the Multiple Regression model. The RMS Error is used as the figure of merit for judging the performance of the three models, and the RMS Error for the ANN model is the latest of the three models. The ANN is faster in learning and exhibits excellent system generalization characteristics.

  5. Transport of regional pollutants through a remote trans-Himalayan valley in Nepal

    Science.gov (United States)

    Dhungel, Shradda; Kathayat, Bhogendra; Mahata, Khadak; Panday, Arnico

    2018-01-01

    Anthropogenic emissions from the combustion of fossil fuels and biomass in Asia have increased in recent years. High concentrations of reactive trace gases and light-absorbing and light-scattering particles from these sources form persistent haze layers, also known as atmospheric brown clouds, over the Indo-Gangetic plains (IGP) from December through early June. Models and satellite imagery suggest that strong wind systems within deep Himalayan valleys are major pathways by which pollutants from the IGP are transported to the higher Himalaya. However, observational evidence of the transport of polluted air masses through Himalayan valleys has been lacking to date. To evaluate this pathway, we measured black carbon (BC), ozone (O3), and associated meteorological conditions within the Kali Gandaki Valley (KGV), Nepal, from January 2013 to July 2015. BC and O3 varied over both diurnal and seasonal cycles. Relative to nighttime, mean BC and O3 concentrations within the valley were higher during daytime when the up-valley flow (average velocity of 17 m s-1) dominated. BC and O3 concentrations also varied seasonally with minima during the monsoon season (July to September). Concentrations of both species subsequently increased post-monsoon and peaked during March to May. Average concentrations for O3 during the seasonally representative months of April, August, and November were 41.7, 24.5, and 29.4 ppbv, respectively, while the corresponding BC concentrations were 1.17, 0.24, and 1.01 µg m-3, respectively. Up-valley fluxes of BC were significantly greater than down-valley fluxes during all seasons. In addition, frequent episodes of BC concentrations 2-3 times higher than average persisted from several days to a week during non-monsoon months. Our observations of increases in BC concentration and fluxes in the valley, particularly during pre-monsoon, provide evidence that trans-Himalayan valleys are important conduits for transport of pollutants from the IGP to the

  6. Conflicts between traditional pastoralism and conservation of Himalayan ibex (Capra sibirica) in the Trans-Himalayan mountains

    NARCIS (Netherlands)

    Bagchi, S.; Mishra, C.; Bhatnagar, Y.V.

    2004-01-01

    There is recent evidence to suggest that domestic livestock deplete the density and diversity of wild herbivores in the cold deserts of the Trans-Himalaya by imposing resource limitations. To ascertain the degree and nature of threats faced by Himalayan ibex (Capra sibirica) from seven livestock

  7. Shallow Structure of the Main Himalayan Thrust from Relocated 2015 MW7.8 Gorkha, Nepal Aftershocks

    Science.gov (United States)

    Bai, L.; Liu, H.; Ritsema, J.; Mori, J. J.; Zhang, T.

    2015-12-01

    On 25 April 2015 the MW 7.8 Gorkha, Nepal earthquake ruptured a shallow section of the Main Himalayan Thrust (MHT) near the capital city of Kathmandu. A temporary broadband seismograph array we deployed near the China-Nepal border recorded the Gorkha earthquake and its aftershocks. Using teleseimic P waveform modeling and multi-scale double-difference earthquake relocation methods for the locally, regionally and teleseismically recorded events, we relocated 153 Gorkha earthquakes with MW>3.5. In addition, 43 earthquakes with MW>3.0 that occurred in the source region during three decades prior to the Ghorka earthquake were also relocated. The results of the study provide refined hypocenters with good depth constraints. From the aftershock data, we can see the shallowly dipping fault structure for the MHT, as well as other structures in the hanging wall of the fault zone. This is the first well-recorded earthquake sequence that has occurred on the shallowest portion of the MHT, providing new constraints on the structure of the MHT and its earthquake potential along the Himalaya orogen.

  8. Segmentation of the Himalayan megathrust around the Gorkha earthquake (25 April 2015) in Nepal

    Science.gov (United States)

    Mugnier, Jean-Louis; Jouanne, François; Bhattarai, Roshan; Cortes-Aranda, Joaquim; Gajurel, Ananta; Leturmy, Pascale; Robert, Xavier; Upreti, Bishal; Vassallo, Riccardo

    2017-06-01

    We put the 25 April 2015 earthquake of Nepal (Mw 7.9) into its structural geological context in order to specify the role of the segmentation of the Himalayan megathrust. The rupture is mainly located NW of Kathmandu, at a depth of 13-15 km on a flat portion of the Main Himalayan Thrust (MHT) that dips towards the N-NE by 7-10°. The northern bound of the main rupture corresponds to the transition towards a steeper crustal ramp. This ramp, which is partly coupled during the interseismic period, is only locally affected by the earthquake. The southern bound of the rupture was near the leading edge of the Lesser Himalaya antiformal duplex and near the frontal footwall ramp of the upper Nawakot duplex. The rupture has been affected by transversal structures: on the western side, the Judi lineament separates the main rupture zone from the nucleation area; on the eastern side, the Gaurishankar lineament separates the 25 April 2015 rupture from the 12 May 2015 (Mw 7.2) rupture. The origin of these lineaments is very complex: they are probably linked to pre-Himalayan faults that extend into the Indian shield beneath the MHT. These inherited faults induce transverse warping of the upper lithosphere beneath the MHT, control the location of lateral ramps of the thrust system and concentrate the hanging wall deformation at the lateral edge of the ruptures. The MHT is therefore segmented by stable barriers that define at least five patches in Central Nepal. These barriers influence the extent of the earthquake ruptures. For the last two centuries: the 1833 (Mw 7.6) earthquake was rather similar in extent to the 2015 event but its rupture propagated south-westwards from an epicentre located NE of Kathmandu; the patch south of Kathmandu was probably affected by at least three earthquakes of Mw ⩾ 7 that followed the 1833 event a few days later or 33 years (1866 event, Mw 7.2) later; the 1934 earthquake (Mw 8.4) had an epicentre ∼170 km east of Kathmandu, may have propagated

  9. Reconciling regional continuity with local variability in structure, uplift and exhumation of the Timor orogen

    NARCIS (Netherlands)

    Tate, Garrett W.; McQuarrie, Nadine; Tiranda, Herwin; van Hinsbergen, D.J.J.; Harris, Ron; Zachariasse, Willem Jan; Fellin, Maria Giuditta; Reiners, Peter W.; Willett, Sean D.

    Along-strike variations in orogenic development can be difficult to constrain. Resulting assumptions projecting similarity or variability along strike can lead to erroneous conclusions at the orogen scale. Young orogens provide opportunities to document limits of along-strike projection and test

  10. The importance of agricultural lands for Himalayan birds in winter.

    Science.gov (United States)

    Elsen, Paul R; Kalyanaraman, Ramnarayan; Ramesh, Krishnamurthy; Wilcove, David S

    2017-04-01

    The impacts of land-use change on biodiversity in the Himalayas are poorly known, notwithstanding widespread deforestation and agricultural intensification in this highly biodiverse region. Although intact primary forests harbor many Himalayan birds during breeding, a large number of bird species use agricultural lands during winter. We assessed how Himalayan bird species richness, abundance, and composition during winter are affected by forest loss stemming from agriculture and grazing. Bird surveys along 12 elevational transects within primary forest, low-intensity agriculture, mixed subsistence agriculture, and intensively grazed pastures in winter revealed that bird species richness and abundance were greatest in low-intensity and mixed agriculture, intermediate in grazed pastures, and lowest in primary forest at both local and landscape scales; over twice as many species and individuals were recorded in low-intensity agriculture than in primary forest. Bird communities in primary forests were distinct from those in all other land-use classes, but only 4 species were unique to primary forests. Low-, medium-, and high-intensity agriculture harbored 32 unique species. Of the species observed in primary forest, 80% had equal or greater abundance in low-intensity agricultural lands, underscoring the value of these lands in retaining diverse community assemblages at high densities in winter. Among disturbed landscapes, bird species richness and abundance declined as land-use intensity increased, especially in high-intensity pastures. Our results suggest that agricultural landscapes are important for most Himalayan bird species in winter. But agricultural intensification-especially increased grazing-will likely result in biodiversity losses. Given that forest reserves alone may inadequately conserve Himalayan birds in winter, comprehensive conservation strategies in the region must go beyond protecting intact primary forests and ensure that low-intensity agricultural

  11. [Echolocation calls of free-flying Himalayan swiftlets (Aerodramus brevirostris)].

    Science.gov (United States)

    Wang, Bin; Ma, Jian-Zhang; Chen, Yi; Tan, Liang-Jing; Liu, Qi; Shen, Qi-Qi; Liao, Qing-Yi; Zhang, Li-Biao

    2013-02-01

    Here, we present our findings of free-flying echolocation calls of Himalayan swiftlets (Aerodramus brevirostris), which were recorded in Shenjing Cave, Hupingshan National Reserve, Shimen County, Hunan Province in June 2012, using Avisoft-UltraSoundGate 116(e). We noted that after foraging at dusk, the Himalayan swiftlets flew fast into the cave without clicks, and then slowed down in dark area in the cave, but with sounds. The echolocation sounds of Himalayan swiftlets are broadband, double noise burst clicks, separated by a short pause. The inter-pulse intervals between double clicks (99.3±3.86 ms)were longer than those within double clicks (6.6±0.42 ms) (P0.05) and pulse duration 2.9±0.12 ms, 3.2±0.17 ms, (P>0.05) between the first and second, other factors-maximum frequency, minimum frequency, frequency bandwidth, and power-were significantly different between the clicks. The maximum frequency of the first pulse (20.1±1.10 kHz) was higher than that of second (15.4±0.98 kHz) (Pecholocation pulses including ultrasonic sound, with a maximum frequency reaching 33.2 kHz.

  12. The Capricorn Orogen Passive source Array (COPA) in Western Australia

    Science.gov (United States)

    Gessner, K.; Yuan, H.; Murdie, R.; Dentith, M. C.; Johnson, S.; Brett, J.

    2015-12-01

    COPA is the passive source component of a multi-method geophysical program aimed at assessing the mineral deposits potential of the Proterozoic Capricorn Orogen. Previous results from the active source surveys, receiver functions and magnetotelluric studies show reworked orogenic crust in the orogen that contrasts with more simple crust in the neighbouring Archean cratons, suggesting progressive and punctuated collisional processes during the final amalgamation of the Western Australian craton. Previous seismic studies are all based on line deployment or single station analyses; therefore it is essential to develop 3D seismic images to test whether these observations are representative for the whole orogen. With a careful design that takes advantage of previous passive source surveys, the current long-term and short-term deployments span an area of approximately 500 x 500 km. The 36-month total deployment can guarantee enough data recording for 3D structure imaging using body wave tomography, ambient noise surface wave tomography and P- and S-wave receiver function Common Conversion Point (CCP) stacking techniques. A successive instrument loan from the ANSIR national instrument pool, provided 34 broadband seismometers that have been deployed in the western half of the orogen since March 2014. We expect approximately 40-km lateral resolution near the surface for the techniques we propose, which due to low frequency nature of earthquake waves will degrade to about 100 km near the base of the cratonic lithosphere, which is expected at depths between 200 to 250 km. Preliminary results from the first half of the COPA deployment will be presented in the light of the hypotheses that 1) distinct crustal blocks can be detected continuously throughout the orogen (using ambient noise/body wave tomography); 2) distinct lithologies are present in the crust and upper mantle across the orogen (using receiver function CCP images); and 3) crustal and lithosphere deformation along

  13. Deformation of the Songshugou ophiolite in the Qinling orogen

    Science.gov (United States)

    Sun, Shengsi; Dong, Yunpeng

    2017-04-01

    The Qinling orogen, middle part of the China Central Orogenic Belt, is well documented that was constructed by multiple convergences and subsequent collisions between the North China and South China Blocks mainly based on geochemistry and geochronology of ophiolites, magmatic rocks as well as sedimentary reconstruction. However, this model is lack of constraints from deformation of subduction/collision. The Songshugou ophiolite outcropped to the north of the Shangdan suture zone represents fragments of oceanic crust and upper mantle. Previous works have revealed that the ophiolite was formed at an ocean ridge and then emplaced in the northern Qinling belt. Hence, deformation of the ophiolite would provide constraints for the rifting and subduction processes. The ophiolite consists chiefly of metamorphosed mafic and ultramafic rocks. The ultramafic rocks contain coarse dunite, dunitic mylonite and harzburgite, with minor diopsidite veins. The mafic rocks are mainly amphibolite, garnet amphibolite and amphibole schist, which are considered to be eclogite facies and retrograde metamorphosed oceanic crust. Amphibole grains in the mafic rocks exhibit a strong shape-preferred orientation parallel to the foliation, which is also parallel to the lithologic contacts between mafic and ultramafic rocks. Electron backscattered diffraction (EBSD) analyses show strong olivine crystallographic preferred orientations (CPO) in dunite including A-, B-, and C-types formed by (010)[100], (010)[001] and (100)[001] dislocation slip systems, respectively. A-type CPO suggests high temperature plastic deformation in the upper mantle. In comparison, B-type may be restricted to regions with significantly high water content and high differential stress, and C-type may also be formed in wet condition with lower differential stress. Additionally, the dunite evolved into amphibolite facies metamorphism with mineral assemblages of olivine + talc + anthophyllite. Assuming a pressure of 1.5 GPa

  14. The pre-orogenic detrital zircon record of the Variscan orogeny: Preliminary results

    Science.gov (United States)

    Stephan, Tobias; Kroner, Uwe

    2017-04-01

    To test plate-tectonic constellations in consideration of the long-term development of sedimentary transport paths, temporally and spatially highly resolved records of provenance analysis are mandatory. The interpretation of existing studies focus on small-scale areas within an orogen thereby neglecting the differing distribution of provenance data in the entire orogenic system. This study reviews a large data set of compiled geochronological data to document the development of pre-orogenic tectonic units on the example of the Variscan orogeny. Constrained by tectonic and geological models, the temporal distribution of U-Pb detrital zircon ages, used as a proxy for sedimentary provenance, shows that some minima and maxima of zircon abundance are nearly synchronous for thousands of kilometres along the orogeny. Age spectra of Precambrian to Lower Palaeozoic samples were constructed on the basis of 38729 U-Pb ages from 685 samples that were compiled from 102 publications. The age compilation combines thermal ionization mass spectrometry (TIMS), laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS), sensitive high-resolution ion microprobe (SHRIMP), and secondary ion mass spectrometry (SIMS) analyses. The data was re-processed using a common age calculation and concordance filter to ensure comparability. The concordance of each zircon grain was calculated from 206Pb/238U and 207Pb/235U ages to guarantee that only concordant grains, i.e., with 3) is used for the maximum age of deposition. In addition to the location of >600 samples, the precise depositional ages result in a spatially and temporally high resolution. To avoid the different levels of analytical precision of the compiled TIMS, LA-ICP-MS, SHRIMP, and SIMS data, detrital zircon ages are plotted as kernel density estimates. Spatial and temporal distribution of the kernel density estimates, as well as further statistical techniques (e.g. multidimensional scaling) are used to discriminate

  15. Geometry, kinematics and tectonic models of the Kazakhstan Orocline, Central Asian Orogenic Belt

    Science.gov (United States)

    Li, Pengfei; Sun, Min; Rosenbaum, Gideon; Yuan, Chao; Safonova, Inna; Cai, Keda; Jiang, Yingde; Zhang, Yunying

    2018-03-01

    The Central Asian Orogenic Belt (CAOB) is one of the largest accretionary orogens on Earth and is characterized by the occurrence of tight oroclines (Kazakhstan and Tuva-Mongolian oroclines). The origin of these large-scale orogenic curvatures is not quite understood, but is fundamentally important for understanding crustal growth and tectonic evolution of the CAOB. Here we provide an outline of available geological and paleomagnetic data around the Kazakhstan Orocline, with an aim of clarifying the geometry, kinematics and geodynamic origin of the orocline. The Kazakhstan Orocline is evident in a total magmatic image, and can be traced by the continuation of high magnetic anomalies associated with the Devonian Volcanic Belt and the Late Devonian to Carboniferous Balkhash-Yili arc. Paleomagnetic data show ∼112-126° clockwise rotation of the northern limb relative to the southern limb in the Late Devonian to Early Carboniferous, as well as ∼15-28° clockwise rotation of the northern limb and ∼39-40° anticlockwise rotation of the southern limb relative to the hinge of the orocline during the Late Carboniferous to Permian. We argue that the Kazakhstan Orocline experienced two-stage bending with the early stage of bending (Late Devonian to Early Carboniferous; ∼112-126°) driven by slab rollback, and the later stage (Late Carboniferous to Permian; 54-68°) possibly associated with the amalgamation of the Siberian, Tarim and Baltic cratons. This new tectonic model is compatible with the occurrence of rift basins, the spatial migration of magmatic arc, and the development of large-scale strike-slip fault systems during oroclinal bending.

  16. A case study of pedometer-recorded steps along the Himalayan ...

    African Journals Online (AJOL)

    A case study of pedometer-recorded steps along the Himalayan mountain range. ... African Journal for Physical Activity and Health Sciences ... The aim of this study was to provide data on the volume and intensity of steps in five healthy adults on an 11-day hike along the Himalayan mountain range and to highlight some ...

  17. Discriminating fluid source regions in orogenic gold deposits using B-isotopes

    Science.gov (United States)

    Lambert-Smith, James S.; Rocholl, Alexander; Treloar, Peter J.; Lawrence, David M.

    2016-12-01

    opposing population in the δ11B data for both tourmaline groups reflects continual tourmaline growth throughout mineralization, which records the process of fluid mixing. A peak in δ11B values at ∼8‰ largely controlled by tourmalines of syn- to post-ore timing represents a mixture of the two isotopically distinct fluids. This paper demonstrates that B-isotopes in tourmaline can be instrumental in interpreting complex and dynamic hydrothermal systems. The importance of B as an integral constituent of orogenic ore forming fluids and as a gangue phase in orogenic gold deposits makes B-isotope analysis a powerful tool for testing the level of source region variability in these fluids, and by extension, that of metal sources.

  18. Along-Strike Differences of the Main Himalayan Thrust and Deformation within the Indian Crust: Insights from Seismicity and Seismic Velocities in Bhutan and its Foreland

    Science.gov (United States)

    Diehl, T.; Singer, J.; Hetényi, G.; Kissling, E. H.; Clinton, J. F.

    2015-12-01

    The seismicity of Bhutan is characterized by the apparent lack of great earthquakes and a significantly lower activity compared to most other parts of the Himalayan arc. To better understand the underlying mechanisms of this anomalously low activity and to relate it with possible along-strike differences in the structure of the orogenic belt, a temporary network with up to 38 broadband seismometers was installed in Bhutan between January 2013 and November 2014. In this work we present a catalog of local and regional earthquakes detected and located with the GANSSER network complemented by regional stations in India, Bangladesh, and China. State-of-the-art data analysis and earthquake location procedures were applied to derive a high-precision earthquake catalog of Bhutan and surrounding regions. Focal mechanisms from regional moment tensor inversions and first-motion polarities complement the earthquake catalog. In the vicinity of the Shumar-Kuru Chu Spur in East Bhutan, seismicity forms a moderately dipping structure at about 12 km depth, which we associate with the Main Himalayan Thrust (MHT). North of 27.6°N the dip of the structure steepens, which can be interpreted as a ramp along the MHT. In West Bhutan seismicity occurs at depths of 20 to 40 km and receiver function images indicate that seismicity occurs in the underthrusting Indian crust rather than on the MHT. The highest seismic activity is clustered along the Goalpara Lineament, a dextral NE-SW striking shear zone in southwest Bhutan, which appears to connect to the western edge of the Shillong Plateau in the foreland. Focal depths indicate that this shear zone is located at depths of 20-30 km and therefore in the underthrusting Indian crust. Preliminary results of a 3D local earthquake tomography show substantial differences in the uppermost crust between east and west Bhutan. Consistent with our receiver function images, the results also indicate a thinning of the crustal root towards eastern Bhutan.

  19. Botany, ethnomedicines, phytochemistry and pharmacology of Himalayan paeony (Paeonia emodi Royle.).

    Science.gov (United States)

    Ahmad, Mushtaq; Malik, Khafsa; Tariq, Akash; Zhang, Guolin; Yaseen, Ghulam; Rashid, Neelam; Sultana, Shazia; Zafar, Muhammad; Ullah, Kifayat; Khan, Muhammad Pukhtoon Zada

    2018-04-04

    submission and most of the studies (90%) without validation of taxonomic names using recognized databases. In reported methods, 67% studies without characterization of extracts, 25% lack proper dose, 40% without duration and 31% reports lack information on proper controls. Similarly, only 18% studies reports active compound(s) responsible for pharmacological activities, 14% studies show minimal active concentration, only 2.5% studies report mechanism of action on target while none of the reports mentioned in silico approach. P. emodi is endemic to Himalayan region (Pakistan, China, India and Nepal) with diverse traditional therapeutic uses. Majority of reviewed studies showed confusion in its taxonomic validity, incomplete methodologies and ambiguous findings. Keeping in view the immense uses of P. emodi in various traditional medicinal systems, holistic pharmacological approaches in combination with reverse pharmacology, system biology, and "omics" technologies are recommended to improve the quality of research which leads to natural drug discovery development at global perspectives. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Food and nutrition security in the Hindu Kush Himalayan region.

    Science.gov (United States)

    Rasul, Golam; Hussain, Abid; Mahapatra, Bidhubhusan; Dangol, Narendra

    2018-01-01

    The status of food and nutrition security and its underlying factors in the Hindu-Kush Himalayan (HKH) region is investigated. In this region, one third to a half of children (security in the HKH region. To achieve sustainable food and nutrition security in the mountains, this study suggests a multi-sectoral integrated approach with consideration of nutritional aspects in all development processes dealing with economic, social, agricultural and public health issues. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  1. Transport of regional pollutants through a remote trans-Himalayan valley in Nepal

    Directory of Open Access Journals (Sweden)

    S. Dhungel

    2018-01-01

    Full Text Available Anthropogenic emissions from the combustion of fossil fuels and biomass in Asia have increased in recent years. High concentrations of reactive trace gases and light-absorbing and light-scattering particles from these sources form persistent haze layers, also known as atmospheric brown clouds, over the Indo–Gangetic plains (IGP from December through early June. Models and satellite imagery suggest that strong wind systems within deep Himalayan valleys are major pathways by which pollutants from the IGP are transported to the higher Himalaya. However, observational evidence of the transport of polluted air masses through Himalayan valleys has been lacking to date. To evaluate this pathway, we measured black carbon (BC, ozone (O3, and associated meteorological conditions within the Kali Gandaki Valley (KGV, Nepal, from January 2013 to July 2015. BC and O3 varied over both diurnal and seasonal cycles. Relative to nighttime, mean BC and O3 concentrations within the valley were higher during daytime when the up-valley flow (average velocity of 17 m s−1 dominated. BC and O3 concentrations also varied seasonally with minima during the monsoon season (July to September. Concentrations of both species subsequently increased post-monsoon and peaked during March to May. Average concentrations for O3 during the seasonally representative months of April, August, and November were 41.7, 24.5, and 29.4 ppbv, respectively, while the corresponding BC concentrations were 1.17, 0.24, and 1.01 µg m−3, respectively. Up-valley fluxes of BC were significantly greater than down-valley fluxes during all seasons. In addition, frequent episodes of BC concentrations 2–3 times higher than average persisted from several days to a week during non-monsoon months. Our observations of increases in BC concentration and fluxes in the valley, particularly during pre-monsoon, provide evidence that trans-Himalayan valleys are important conduits for transport of

  2. Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin

    International Nuclear Information System (INIS)

    Narula, Kapil K.; Gosain, A.K.

    2013-01-01

    The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11 600 km 2 with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO 3 ) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO 3 transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash–Sutcliffe and R 2 correlations greater than + 0.7). Nitrate loading obtained after nitrification, denitrification, and NO 3 removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO 3 concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the century. Water yield estimates

  3. Continental origin of the Gubaoquan eclogite and implications for evolution of the Beishan Orogen, Central Asian Orogenic Belt, NW China

    Science.gov (United States)

    Saktura, Wanchese M.; Buckman, Solomon; Nutman, Allen P.; Belousova, Elena A.; Yan, Zhen; Aitchison, Jonathan C.

    2017-12-01

    The Gubaoquan eclogite occurs in the Paleozoic Beishan Orogen of NW China. Previously it has been interpreted as a fragment of subducted oceanic crust that was emplaced as a mélange within continental rocks. Contrary to this, we demonstrate that the Gubaoquan eclogite protolith was a Neoproterozoic basic dyke/sill which intruded into Proterozoic continental rocks. The SHRIMP Usbnd Pb zircon dating of the metamorphic rims of the Gubaoquan eclogite yields an age 466 ± 27 Ma. Subdued heavy rare earth element abundances and lack of negative Eu anomalies of the metamorphic zircon domains confirm that this age represents eclogite facies metamorphism. The host augen orthogneiss has a Usbnd Pb zircon age of 920 ± 14 Ma, representing the timing of crystallization of the granitic protolith. A leucogranitic vein which intrudes the eclogite has a Usbnd Pb zircon age of 424 ± 8.6 Ma. This granitic vein marks the end of high-grade metamorphism in this area. The overcomplication of tectonic history of the Beishan Orogen is partially caused by inconsistent classifications and nomenclature of the same rock units and arbitrary subdivisions of Precambrian blocks as individual microcontinents. In an attempt to resolve this, we propose a simpler model that involves the partial subduction of the northern passive margin of the Dunhuang Block beneath the active continental margin developing on the Mazongshan-Hanshan Block to the north. Ocean closure and continental collision during the Late Ordovician resulted in continental thickening and eclogite facies metamorphism recorded by the mafic dykes/sills (now the Gubaoquan eclogite). In the light of the new data, the tectonothermal evolution of the Beishan Orogen is reviewed and integrated with the evolution of the Central Asian Orogenic Belt.

  4. Orogenic structural inheritance and rifted passive margin formation

    Science.gov (United States)

    Salazar Mora, Claudio A.; Huismans, Ritske S.

    2016-04-01

    Structural inheritance is related to mechanical weaknesses in the lithosphere due to previous tectonic events, e.g. rifting, subduction and collision. The North and South Atlantic rifted passive margins that formed during the breakup of Western Gondwana, are parallel to the older Caledonide and the Brasiliano-Pan-African orogenic belts. In the South Atlantic, 'old' mantle lithospheric fabric resulting from crystallographic preferred orientation of olivine is suggested to play a role during rifted margin formation (Tommasi and Vauchez, 2001). Magnetometric and gravimetric mapping of onshore structures in the Camamu and Almada basins suggest that extensional faults are controlled by two different directions of inherited older Brasiliano structures in the upper lithosphere (Ferreira et al., 2009). In the South Atlantic Campos Basin, 3D seismic data indicate that inherited basement structures provide a first order control on basin structure (Fetter, 2009). Here we investigate the role of structural inheritance on the formation of rifted passive margins with high-resolution 2D thermo-mechanical numerical experiments. The numerical domain is 1200 km long and 600 km deep and represents the lithosphere and the sublithospheric mantle. Model experiments were carried out by creating self-consistent orogenic inheritance where a first phase of orogen formation is followed by extension. We focus in particular on the role of varying amount of orogenic shortening, crustal rheology, contrasting styles of orogen formation on rifted margin style, and the time delay between orogeny and subsequent rifted passive formation. Model results are compared to contrasting structural styles of rifted passive margin formation as observed in the South Atlantic. Ferreira, T.S., Caixeta, J.M., Lima, F.D., 2009. Basement control in Camamu and Almada rift basins. Boletim de Geociências da Petrobrás 17, 69-88. Fetter, M., 2009. The role of basement tectonic reactivation on the structural evolution

  5. Plate kinematics in the Cantabrian domain of the Pyrenean orogen

    Directory of Open Access Journals (Sweden)

    S. Tavani

    2012-09-01

    Full Text Available The Cantabrian domain represents the western portion of the Pyrenean orogen, in the area where the Iberian continental lithosphere was subducted toward the north underneath the transitional to oceanic lithosphere of the Bay of Biscay. There, the about 100 km of orogenic convergence have been mostly accommodated in the northern portion of the orogen (i.e. the retro wedge developed in the Bay of Biscay abyssal plain, while only crustal-scale folding with limited internal deformation occurred in the Cantabrian southern wedge (pro-wedge. Integrated meso- and macrostructural analyses and a reappraisal of available information from the transitional area between the Pyrenean and Cantabrian domains are presented in this work, allowing to set geometric and kinematic constraints on the entire Meso-Cenozoic history of the northern portion of the Iberian Plate, including subduction initiation and evolution in the western portion of the Pyrenean orogen.

    The structural record of the Late Jurassic to Early Cretaceous deformation stage, which was associated with rifting and seafloor spreading in the Bay of Biscay, indicates a ridge perpendicular (NNE-SSW oriented extension, with no evidence of relevant strike-slip components during rifting. A Cenozoic NNW-SSE oriented shortening stage followed, related to the limited (about 100 km north-directed subduction of the Iberian continental lithosphere underneath the transitional to oceanic lithosphere of the Bay of Biscay. Subduction led to the formation of the poorly-developed Cantabrian pro-wedge, which is laterally juxtaposed to the well-developed Pyrenean pro-wedge to the east. During this convergence stage, the structural framework in the Cantabrian pro-wedge, and particularly along its transition with the Pyrenean wedge to the east, was severely complicated by the reactivation of Paleozoic and Mesozoic inherited structures.

    Data presented in this work fully support the development of the

  6. Simulation of a Himalayan cloudburst event

    Indian Academy of Sciences (India)

    Journal of Earth System Science. Current Issue : Vol. 127, Issue 1 · Current Issue Volume 127 | Issue 1. February 2018. Home · Volumes & Issues · Special Issues · Forthcoming Articles · Search · Editorial Board · Information for Authors · Subscription ...

  7. Satellite Observations of Desert Dust-induced Himalayan Snow Darkening

    Science.gov (United States)

    Gautam, Ritesh; Hsu, N. Christina; Lau, William K.-M.; Yasunari, Teppei J.

    2013-01-01

    The optically thick aerosol layer along the southern edge of the Himalaya has been subject of several recent investigations relating to its radiative impacts on the South Asian summer monsoon and regional climate forcing. Prior to the onset of summer monsoon, mineral dust from southwest Asian deserts is transported over the Himalayan foothills on an annual basis. Episodic dust plumes are also advected over the Himalaya, visible as dust-laden snow surface in satellite imagery, particularly in western Himalaya. We examined spectral surface reflectance retrieved from spaceborne MODIS observations that show characteristic reduction in the visible wavelengths (0.47 nm) over western Himalaya, associated with dust-induced solar absorption. Case studies as well as seasonal variations of reflectance indicate a significant gradient across the visible (0.47 nm) to near-infrared (0.86 nm) spectrum (VIS-NIR), during premonsoon period. Enhanced absorption at shorter visible wavelengths and the resulting VIS-NIR gradient is consistent with model calculations of snow reflectance with dust impurity. While the role of black carbon in snow cannot be ruled out, our satellite-based analysis suggests the observed spectral reflectance gradient dominated by dust-induced solar absorption during premonsoon season. From an observational viewpoint, this study underscores the importance of mineral dust deposition toward darkening of the western Himalayan snow cover, with potential implications to accelerated seasonal snowmelt and regional snow albedo feedbacks.

  8. Mating dominance amongst male Himalayan tahr: blonds do better.

    Science.gov (United States)

    Lovari, S; Pellizzi, B; Boesi, R; Fusani, L

    2009-05-01

    In ungulates, rank order is determined by differences in weight, body size, weapon size and age. In the Caprini tribe (Bovidae: Caprinae), adult male Himalayan tahr are unique to show different coat colours, but no sexual dimorphism in weapons. A highly significant correlation between hair colour and rank order was found during the rut: males with a lighter coloured ruff dominated over darker ruffed ones, in both aggressive interactions and access to oestrus females. We studied colour-based dominance in relation to weight, age and testosterone levels, which establish the social rank in most ungulates. No differences in weight and testosterone concentrations were found between adult male colour classes, but males with paler ruffs were significantly younger than darker adult males. The distribution of physical traumas from fights confirmed that younger, lighter-coloured males had a higher rank than older, darker males, a pattern which is unusual amongst ungulates. Coat colour seems to work as a signal of rank in male-male aggressive interactions and it changes according to age, whereas the relevant physiological determinants deserve further research. Intrasexual male competition has not changed weapon size or shape in the Himalayan tahr, but ruff colours are apparently used to signal rank and dominance. Colour patterns of adult males may then be homologous to ritualised weapons, apparently being a unique feature of male tahr amongst mammals.

  9. Trans-Himalayan water contributions to river discharge

    Science.gov (United States)

    Andermann, Christoff; Stieglitz, Thomas; Schuessler, Jan A.; Parajouli, Binod

    2017-04-01

    Hydrological processes in high mountains are not well understood. Groundwater is commonly considered to be of little importance in the mountain water balance, while direct runoff, snow and ice melt are thought to be the principal hydrological buffer. We present new insights into hydrological fluxes between major reservoirs in a trans-Himalayan catchment. The study area is the Kali Gandaki catchment, rising in the dry Tibetan interior, carving through the high Himalayas and draining the full width of the foothills to the Ganges foreland. The catchment has a well-defined monsoon climate, with pronounced annual wet and dry seasons and a clear separation of wind- and leeward regions. We have sampled the main river and its tributaries as well as several springs during the four hydrological seasons (winter, pre-monsoon, monsoon, post-monsoon). We have measured major element abundances as well as 222Rn in situ, as a tracer for groundwater contribution. These measurements are placed in a context of topographic analyses as well as continuous discharge and precipitation measurements. Furthermore, we have equipped two sites with continuous water samplers, sampling over > 4 monsoon seasons, allowing us to resolve the seasonal hydrological dynamic range on a very high temporal resolution. Chemical fluxes vary spatially over several orders of magnitude, showing a systematic downstream dilution trend for most major elements during all hydrological seasons. High initial concentrations derive from evaporite deposits in the uppermost part of the catchment, constituting a large scale, natural salt tracer experiment. The well-defined decline of solute concentrations along the main river, paired with constraints on the composition of lateral water inputs downstream allow the calculation of the spatial distribution of additional hydrological fluxes, by applying end member mixing modeling. Continuous river stage and bulk dissolved load (electrical conductivity) monitoring depict well

  10. Chemical Composition and Biological Activities of Trans-Himalayan Alga Spirogyra porticalis (Muell.) Cleve

    Science.gov (United States)

    Kumar, Jatinder; Dhar, Priyanka; Tayade, Amol B.; Gupta, Damodar; Chaurasia, Om P.; Upreti, Dalip K.; Toppo, Kiran; Arora, Rajesh; Suseela, M. R.; Srivastava, Ravi B.

    2015-01-01

    The freshwater alga Spirogyra porticalis (Muell.) Cleve, a filamentous charophyte, collected from the Indian trans-Himalayan cold desert, was identified on the basis of morpho-anatomical characters. Extracts of this alga were made using solvents of varying polarity viz. n-hexane, acetonitrile, methanol and water. The antioxidant capacities and phenolic profile of the extracts were estimated. The methanol extract showing highest antioxidant capacity and rich phenolic attributes was further investigated and phytochemical profiling was conducted by gas chromatography-mass spectrometry (GC/MS) hyphenated technique. The cytotoxic activity of methanol extract was evaluated on human hepatocellular carcinoma HepG2 and colon carcinoma RKO cell lines. The anti-hypoxic effect of methanol extract of the alga was tested on in vivo animal system to confirm its potential to ameliorate oxidative stress. The antioxidant assays viz. ferric reducing antioxidant power (FRAP), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging capacities, β-carotene-linoleic acid bleaching property and lipid peroxidation exhibited analogous results, wherein the algal extracts showed significantly high antioxidant potential. The extracts were also found to possess high content of total proanthocyanidin, flavonoid and polyphenol. GC/MS analysis revealed the presence of thirteen chemotypes in the methanol extract representing different phytochemical groups like fatty acid esters, sterols, unsaturated alcohols, alkynes etc. with substantial phyto-pharmaceutical importance. The methanol extract was observed to possess anticancer activity as revealed from studies on HepG2 and RKO cell lines. In the present study, S. porticalis methanol extract also provided protection from hypoxia-induced oxidative stress and accelerated the onset of adaptative changes in rats during exposure to hypobaric hypoxia. The

  11. Block-and-fault dynamics modelling of the Himalayan frontal arc: Implications for seismic cycle, slip deficit, and great earthquakes

    Science.gov (United States)

    Vorobieva, Inessa; Mandal, Prantik; Gorshkov, Alexander

    2017-10-01

    A numerical block-and-fault dynamics model (BAFD) of the Himalayan frontal arc, India is developed to understand the long-term patterns of strain accumulation and occurrences of great earthquakes in the Himalaya. The morphostructural scheme outlines twelve major crustal blocks, and external driving motions are prescribed using GPS data. The BAFD model reproduces essential features of the geodynamics and seismicity of the Himalayan frontal arc. The locations of the large synthetic earthquakes and their maximum magnitudes are consistent with the information available from the instrumental and historical earthquake catalogues. We model the evolution of the slip deficit and seismic cycles for different sections across the Himalaya frontal arc. The modelled seismic cycles are found to be varying from 700 to 2100 years and are in good agreement with the return periods estimates from the recent paleoseismological studies. We notice that the accumulation of the slip deficit depends not only on the rate of shortening, rheology and structure but also on the dynamics of the confining crustal blocks. Further, we observe that tectonic motions of the Shillong plateau and Assam basin microplates play a significant role in controlling the seismicity patterns of the Bhutan block, which resulted in the decreased seismic activity, and increased rate of aseismic displacement. Thus, we infer that the regional seismicity patterns are a consequence of dynamics of the entire regional fault-and-block system rather than dynamics of individual fault. Our BAFD modelling predicts the maximum earthquake hazard associated with future large/great earthquakes for the central Himalayan gap region, which lies between the 1905 Kangra and the 2015 Gorkha earthquake ruptures, but relatively less hazard in Kashmir and Assam.

  12. Natural Dams as Tipping Points in Himalayan Erosion (Invited)

    Science.gov (United States)

    Korup, O.

    2010-12-01

    Natural dams result from hillslope, glacial, volcanic, and other sediment inputs that temporarily overwhelm the transport capacity along a given river reach. Such blockages are tipping points in which fluvial erosion and sediment transport rapidly switch to aggradation and vice versa even in the most powerful of rivers, thus eventually modulating both rates and duration of river incision into bedrock. Conspicuous clusters of hundreds of large natural dams occur in several major watersheds draining the Himalayan syntaxes and the southern Himalayan front, including the Indus, Yarlung Tsangpo, Sutlej, Kali Gandaki, and Arun. The Indus features the largest concentration of giant landslide dams known worldwide, whereas the Yarlung Tsangpo seems largely devoid of comparable landslide dams. Glacial dams such as river-blocking moraines are limited to headwaters where topography intersects the regional snowline. By forming dams and protective alluvial fill, glaciers and landslides help retard headward fluvial bedrock incision into parts of the Tibetan Plateau interior, limiting its dissection in addition to effects of upstream aridity and localized rock uplift. A growing number of radiometric age constraints on widely exposed lake sediments and backwater terraces support the notion that large tracts of these rivers had been repeatedly ponded for as long as several tens of thousands of years during the Late Quaternary. High local topographic relief in buffers along these rivers characterizes conspicuous knickzones, and helps pinpoint first-order differences in the type and potential longevity of these natural dams. Patterns of low-temperature thermochronometric data corroborate that peaks in mean local relief, spatially coinciding with peaks in long-term exhumation rates, act as a regionally consistent downstream limit to the preservation potential of natural dams. If indeed glacier and landslide dams act as a negative feedback in response to fluvial dissection of parts of

  13. Geoethical Audit of Himalayan Stratigraphy: A Current Insight from India

    Science.gov (United States)

    Deep Ahluwalia, Arun

    2014-05-01

    Focus of this presentation is to illustrate how learned societies and an eminent academy fellow can unfortunately become a pressure group. It is a very unfair and unbecoming even perhaps more than HIMALAYAN HOAX perpetrated by V. J. Gupta two decades back for over 25 years where he fooled journals, funding agencies and about 120 co-authors. Unless corrected, our learned societies and academies may continue degenerate even more. If this can happen today in the biggest democracy of the world with rule of law and freedom of press, what may happen in other set ups across our planet. The ill conceived and highly misleading book HIMALAYAN FOSSIL FRAUD recently published from PSI, Lucknow University, gives some vital but also unfortunately partial, selective and falsified historical and scientific perspectives of the Himalayan Hoax. This book is a standing testimony of a geoethical failure of individuals and of a learned society who published it without checking facts. Lot of personal testimonies and experiences can be added by the presenter. Some INSA Fellows are today like a cooperative society for cover ups and dirty politicking. The nexus within INSA Fellows to mutually protect each other and gratify at public cost is transparent but ignored for fear and power of their huge clout. Mistakes are allowed in science but science ethics does not allow silence once a fraud is known. If one is such a celebrated VIP like Ashok Sahni and D. M. Banerjee highly rewarded and awarded by so many, it becomes mandatory to maintain highest ethical standards and appear to be doing so. Our eminent INSA Fellows and learned society PSI are making themselves look like a mafia. This is neither ethics nor science. It is pure reckless money making and petty politicking by big guns to save their own skin. Very unfortunate indeed for Lucknow University, Lucknow where PSI is based and the retired teachers manning it are staying put for a life time endlessly getting self elected. Ever lowering

  14. Modeling and Understanding the Mass Balance of Himalayan Glaciers

    Science.gov (United States)

    Rengaraju, S.; Achutarao, K. M.

    2017-12-01

    Changes in glaciers are among the most visible manifestations of a changing climate. Retreating glaciers have significant impacts on global sea-level rise and stream flow of rivers. Modeling the response of glaciers to climate change is important for many reasons including predicting changes in global sea level and water resources. The mass balance of a glacier provides a robust way of ascertaining whether there has been a net loss or gain of ice from the glacier. The mass balance reflects all of the meteorological forcing of the glacier - from the accumulation of snow and the combined losses from ablation and sublimation. The glaciers in the Himalayan region are considered sensitive to climate change and their fate under climate change is critical to the billions of humans that rely on rivers originating from these glaciers. Owing to complex terrain and harsh climate, Himalayan glaciers have historically been poorly monitored and this makes it harder to understand and predict their fate.In this study we model the observed mass balance of Himalayan glaciers using the methods of Radic and Hock (2011) and analyze the response to future changes in climate based on the model projections from the Coupled Model Intercomparison Project Phase-5 (CMIP5; Taylor et al., 2012). We make use of available observations of mass balance from various sources for 14 glaciers across the Himalayas. These glaciers are located across distinct climatic conditions - from the Karakoram and Hindu Kush in the West that are fed by winter precipitation caused by westerly disturbances to the Eastern Himalayas where the summer monsoon provides the bulk of the precipitation. For the historical observed period, we use the ECMWF Re-Analysis (ERA-40) for temperature and VASClimO (GPCC) data at 2.5°x2.5° resolution to calibrate the mass balance model. We evaluate the CMIP5 model simulations for their fidelity in capturing the distinct climatic conditions across the Himalayas in order to select

  15. The lithosphere of the Appalachian orogen and Atlantic passive margin

    Science.gov (United States)

    Fischer, K. M.; MacDougall, J. G.; Hawman, R. B.; Parker, E. H.; Wagner, L. S.

    2012-12-01

    The lithosphere of the Appalachian orogen and Atlantic passive margin has recorded repeated episodes of continental collision and break-up. Improved resolution of crust and mantle structure in this region holds promise for better understanding of orogenesis, rifting and passive margin development. At a broad scale, tomographic models manifest a decrease in lithospheric thickness from the central U.S. craton into the Appalachian orogen. Migration of Sp scattered waves indicates that a significant drop in shear-wave velocity typically occurs at depths of 80-120 km in the eastern U.S., and where these phases fall within the transition from high velocity lid to lower velocity mantle obtained from tomography, they are interpretable as the seismological lithosphere-asthenosphere boundary. Beneath the Appalachians and coastal plain, Sp-derived lithospheric thicknesses are larger than those found in the tectonically active western U.S. where values range from 40-90 km. The vertical shear velocity gradients required to produce the observed Sp phases are sharp (drops of 4-10% over Flexible Arrays. The goal of the Southeastern Suture of the Appalachian Margin Experiment (SESAME) is to better understand lithospheric structures produced by accretion and rifting processes, with a particular focus on the Laurentia-Gondwana suture proposed in southern Georgia, adjacent regions of Mesozoic extension and magmatism, and the architecture of southern Appalachian orogenic crust. SESAME comprises 85 broadband EarthScope Flexible Array stations deployed in two N-S lines that cross the proposed Laurentia-Gondwana suture and extend into Florida; a third line is oriented roughly normal to Appalachian crustal terranes from northern Georgia to eastern Tennessee. Stations were installed in three phases from 2010-2012, and will remain in the field until 2014. Preliminary data analyses reveal significant shear-wave splitting in SKS and SKKS phases beneath the western SESAME stations. Fast

  16. Into the Himalayan Exile: The Phylogeography of the Ground Beetle Ethira clade Supports the Tibetan Origin of Forest-Dwelling Himalayan Species Groups

    Science.gov (United States)

    Schmidt, Joachim; Opgenoorth, Lars; Höll, Steffen; Bastrop, Ralf

    2012-01-01

    The Himalayan mountain arc is one of the hotspots of biodiversity on earth, and species diversity is expected to be especially high among insects in this region. Little is known about the origin of the Himalayan insect fauna. With respect to the fauna of high altitude cloud forests, it has generally been accepted that Himalayan lineages are derived from ancestors that immigrated from Western Asia and from adjacent mountainous regions of East and Southeast Asia (immigration hypothesis). In this study, we sought to test a Tibetan Origin as an alternative hypothesis for groups with a poor dispersal ability through a phylogeographic analysis of the Ethira clade of the genus Pterostichus. We sequenced COI mtDNA and the 18S and 28S rDNA genes in 168 Pterostichini specimens, including 46 species and subspecies of the Ethira clade. In our analysis, we were able to show that the Ethira clade is monophyletic and, thus, represents a Himalayan endemic clade, supporting endemism of two of the basal lineages to the Central Himalaya and documenting large distributional gaps within the phylogeographic structure of the Ethira clade. Furthermore, the molecular data strongly indicate very limited dispersal abilities of species and subspecies of these primary wingless ground beetles. These results are consistent with the hypothesis of a Tibetan Origin, which explains the evolution, diversity and distribution of the Himalayan ground beetle Ethira clade much more parsimoniously than the original immigration hypothesis. PMID:23049805

  17. Invasive alien plant species dynamics in the Himalayan region under climate change.

    Science.gov (United States)

    Lamsal, Pramod; Kumar, Lalit; Aryal, Achyut; Atreya, Kishor

    2018-01-25

    Climate change will impact the dynamics of invasive alien plant species (IAPS). However, the ability of IAPS under changing climate to invade mountain ecosystems, particularly the Himalayan region, is less known. This study investigates the current and future habitat of five IAPS of the Himalayan region using MaxEnt and two representative concentration pathways (RCPs). Two invasive species, Ageratum conyzoides and Parthenium hysterophorus, will lose overall suitable area by 2070, while Ageratina adenophora, Chromolaena odorata and Lantana camara will gain suitable areas and all of them will retain most of the current habitat as stable. The southern Himalayan foothills will mostly conserve species ecological niches, while suitability of all the five species will decrease with increasing elevation. Such invasion dynamics in the Himalayan region could have impacts on numerous ecosystems and their biota, ecosystem services and human well-being. Trans-boundary response strategies suitable to the local context of the region could buffer some of the likely invasion impacts.

  18. Summer Temperature Trend Over the Past Two Millennia Using Air Content in Himalayan Ice

    National Research Council Canada - National Science Library

    Hou, S; Chappellaz, J; Jouzel, J; Chu, P. C; Masson-Delmotte, V; Qin, D; Raynaud, D; Mayewski, P. A; Lipenkov, V. Y; Kang, S

    2007-01-01

    Two Himalayan ice cores display a factor-two decreasing trend of air content over the past two millennia, in contrast to the relatively stable values in Greenland and Antarctica ice cores over the same period...

  19. Late-orogenic extension and strike-slip deformation in the Neogene of southeastern Spain

    NARCIS (Netherlands)

    Meijninger, B.M.L.

    2006-01-01

    The Betic Cordillera of southern Spain form the western end of the Alpine orogen, which during the Neogene was affected by large-scale late-orogenic extension. Extension, however, occurred within a setting of continuous slow convergence of the African and European plates. During the Neogene,

  20. Catastrophic valley fills record large Himalayan earthquakes, Pokhara, Nepal

    Science.gov (United States)

    Stolle, Amelie; Bernhardt, Anne; Schwanghart, Wolfgang; Hoelzmann, Philipp; Adhikari, Basanta R.; Fort, Monique; Korup, Oliver

    2017-12-01

    Uncertain timing and magnitudes of past mega-earthquakes continue to confound seismic risk appraisals in the Himalayas. Telltale traces of surface ruptures are rare, while fault trenches document several events at best, so that additional proxies of strong ground motion are needed to complement the paleoseismological record. We study Nepal's Pokhara basin, which has the largest and most extensively dated archive of earthquake-triggered valley fills in the Himalayas. These sediments form a 148-km2 fan that issues from the steep Seti Khola gorge in the Annapurna Massif, invading and plugging 15 tributary valleys with tens of meters of debris, and impounding several lakes. Nearly a dozen new radiocarbon ages corroborate at least three episodes of catastrophic sedimentation on the fan between ∼700 and ∼1700 AD, coinciding with great earthquakes in ∼1100, 1255, and 1344 AD, and emplacing roughly >5 km3 of debris that forms the Pokhara Formation. We offer a first systematic sedimentological study of this formation, revealing four lithofacies characterized by thick sequences of mid-fan fluvial conglomerates, debris-flow beds, and fan-marginal slackwater deposits. New geochemical provenance analyses reveal that these upstream dipping deposits of Higher Himalayan origin contain lenses of locally derived river clasts that mark time gaps between at least three major sediment pulses that buried different parts of the fan. The spatial pattern of 14C dates across the fan and the provenance data are key to distinguishing these individual sediment pulses, as these are not evident from their sedimentology alone. Our study demonstrates how geomorphic and sedimentary evidence of catastrophic valley infill can help to independently verify and augment paleoseismological fault-trench records of great Himalayan earthquakes, while offering unparalleled insights into their long-term geomorphic impacts on major drainage basins.

  1. Geomorphic legacy of medieval Himalayan earthquakes in the Pokhara Valley

    Science.gov (United States)

    Schwanghart, Wolfgang; Bernhardt, Anne; Stolle, Amelie; Hoelzmann, Philipp; Adhikari, Basanta R.; Andermann, Christoff; Tofelde, Stefanie; Merchel, Silke; Rugel, Georg; Fort, Monique; Korup, Oliver

    2016-04-01

    The Himalayas and their foreland belong to the world's most earthquake-prone regions. With millions of people at risk from severe ground shaking and associated damages, reliable data on the spatial and temporal occurrence of past major earthquakes is urgently needed to inform seismic risk analysis. Beyond the instrumental record such information has been largely based on historical accounts and trench studies. Written records provide evidence for damages and fatalities, yet are difficult to interpret when derived from the far-field. Trench studies, in turn, offer information on rupture histories, lengths and displacements along faults but involve high chronological uncertainties and fail to record earthquakes that do not rupture the surface. Thus, additional and independent information is required for developing reliable earthquake histories. Here, we present exceptionally well-dated evidence of catastrophic valley infill in the Pokhara Valley, Nepal. Bayesian calibration of radiocarbon dates from peat beds, plant macrofossils, and humic silts in fine-grained tributary sediments yields a robust age distribution that matches the timing of nearby M>8 earthquakes in ~1100, 1255, and 1344 AD. The upstream dip of tributary valley fills and X-ray fluorescence spectrometry of their provenance rule out local sediment sources. Instead, geomorphic and sedimentary evidence is consistent with catastrophic fluvial aggradation and debris flows that had plugged several tributaries with tens of meters of calcareous sediment from the Annapurna Massif >60 km away. The landscape-changing consequences of past large Himalayan earthquakes have so far been elusive. Catastrophic aggradation in the wake of two historically documented medieval earthquakes and one inferred from trench studies underscores that Himalayan valley fills should be considered as potential archives of past earthquakes. Such valley fills are pervasive in the Lesser Himalaya though high erosion rates reduce

  2. Geochemical evidence for Paleozoic crustal growth and tectonic conversion in the Northern Beishan Orogenic Belt, southern Central Asian Orogenic Belt

    Science.gov (United States)

    Yuan, Yu; Zong, Keqing; He, Zhenyu; Klemd, Reiner; Jiang, Hongying; Zhang, Wen; Liu, Yongsheng; Hu, Zhaochu; Zhang, Zeming

    2018-03-01

    The Beishan Orogenic Belt is located in the central southernmost part of the Central Asian Orogenic Belt (CAOB), which plays a key role in understanding the formation and evolution of the CAOB. Granitoids are the documents of crustal and tectonic evolution in orogenic belts. However, little is known regarding the petrogenesis and geodynamic setting of the widely distributed Paleozoic granitoids in the Northern Beishan Orogenic Belt (NBOB). The present study reveals significant differences concerning the petrogenesis and tectonic setting of early and late Paleozoic granitoids from the NBOB. The early Paleozoic granitoids from the 446-430 Ma Hongliuxia granite complex of the Mazongshan unit and the 466-428 Ma Shibanjing complex of the Hanshan unit show classic I-type granite affinities as revealed by the relative enrichment of LILEs and LREEs, pronounced depletions of Nb, Ta and Ti and the abundant presence of hornblende. Furthermore, they are characterized by strongly variable zircon εHf(t) values between - 16.7 and + 12.8 and evolved plagioclase Sr isotopic compositions of 0.7145-0.7253, indicating the involvement of both juvenile and ancient continental crust in the magma source. Thus, we propose that the early Paleozoic granitoids in the NBOB were generated in a subduction-related continental arc setting. In contrast, the late Paleozoic 330-281 Ma granitoids from the Shuangjingzi complex of the Hanshan unit exhibit positive zircon εHf(t) values between + 5.8 and + 13.2 and relatively depleted plagioclase Sr isotopic compositions of 0.7037-0.7072, indicating that they were mainly formed by remelting of juvenile crust. Thus, an intra-plate extensional setting is proposed to have occurred during formation of the late Paleozoic granitoids. Therefore, between the early and late Paleozoic, the magma sources of the NBOB granitoids converted from the reworking of both juvenile and ancient crusts during a subduction-induced compressional setting to the remelting of

  3. Timing and mechanism of the rise of the Shillong Plateau in the Himalayan foreland.

    OpenAIRE

    Govin, Gwladys; Najman, Yanina Manya Rachel; Copley, Alex; Millar, Ian; Van der Beek, Peter; Huyghe, Pascale; Grujic, Djordje; Davenport, Jesse

    2018-01-01

    The Shillong Plateau (northeastern India) constitutes the only significant topography in the Himalayan foreland. Knowledge of its surface uplift history is key to understanding topographic development and unraveling tectonic–climate–topographic coupling in the eastern Himalaya. We use the sedimentary record of the Himalayan foreland basin north of the Shillong Plateau to show that the paleo-Brahmaputra river was redirected north and west by the rising plateau at 5.2–4.9 Ma. We suggest that on...

  4. Ancient Himalayan wolf (Canis lupus chanco) lineage in Upper Mustang of the Annapurna Conservation Area, Nepal.

    Science.gov (United States)

    Chetri, Madhu; Jhala, Yadvendradev V; Jnawali, Shant R; Subedi, Naresh; Dhakal, Maheshwar; Yumnam, Bibek

    2016-01-01

    The taxonomic status of the wolf (Canis lupus) in Nepal's Trans-Himalaya is poorly understood. Recent genetic studies have revealed the existence of three lineages of wolves in the Indian sub-continent. Of these, the Himalayan wolf, Canis lupus chanco, has been reported to be the most ancient lineage historically distributed within the Nepal Himalaya. These wolves residing in the Trans-Himalayan region have been suggested to be smaller and very different from the European wolf. During October 2011, six fecal samples suspected to have originated from wolves were collected from Upper Mustang in the Annapurna Conservation Area of Nepal. DNA extraction and amplification of the mitochondrial (mt) control region (CR) locus yielded sequences from five out of six samples. One sample matched domestic dog sequences in GenBank, while the remaining four samples were aligned within the monophyletic and ancient Himalayan wolf clade. These four sequences which matched each other, were new and represented a novel Himalayan wolf haplotype. This result confirms that the endangered ancient Himalayan wolf is extant in Nepal. Detailed genomic study covering Nepal's entire Himalayan landscape is recommended in order to understand their distribution, taxonomy and, genetic relatedness with other wolves potentially sharing the same landscape.

  5. Tectonic processes during oblique collision: Insights from the St. Elias orogen, northern North American Cordillera

    Science.gov (United States)

    Pavlis, T.L.; Picornell, C.; Serpa, L.; Bruhn, R.L.; Plafker, G.

    2004-01-01

    Oblique convergence in the St. Elias orogen of southern Alaska and northwestern Canada has constructed the world's highest coastal mountain range and is the principal driver constructing all of the high topography in northern North America. The orogen originated when the Yakutat terrane was excised from the Cordilleran margin and was transported along margin-parallel strike-slip faults into the subduction-transform transition at the eastern end of the Aleutian trench. We examine the last 3 m.y. of this collision through an analysis of Euler poles for motion of the Yakutat microplate with respect to North America and the Pacific. This analysis indicates a Yakutat-Pacific pole near the present southern triple junction of the microplate and' predicts convergence to dextral-oblique convergence across the offshore Transition fault, onland structures adjacent to the Yakutat foreland, or both, with plate speeds increasing from 10 to 30 mm/yr from southeast to northwest. Reconstructions based on these poles show that NNW transport of the collided block into the NE trending subduction zone forced contraction of EW line elements as the collided block was driven into the subduction-transform transition. This suggests the collided block was constricted as it was driven into the transition. Constriction provides an explanation for observed vertical axis refolding of both earlier formed fold-thrust systems and the collisional suture at the top of the fold-thrust stack. We also suggest that this motion was partially accommodated by lateral extrusion of the western portion of the orogen toward the Aleutian trench. Important questions remain regarding which structures accommodated parts of this motion. The Transition fault may have accommodated much of the Yakutat-Pacific convergence on the basis of our analysis and previous interpretations of GPS-based geodetic data. Nonetheless, it is locally overlapped by up to 800 m of undeformed sediment, yet elsewhere shows evidence of young

  6. Long-Term Changes in Chemical Weathering in the Himalayan Region from Indus Fan Sediments

    Science.gov (United States)

    Carter, S.; Griffith, E. M.; Scher, H.; Dellapenna, T. M.; Clift, P. D.

    2017-12-01

    The Asian Monsoon reflects large-scale interactions between the atmosphere, land, and ocean systems. Increasing our understanding of this system, how and why it has evolved through time, is critically important in order to understand how it may evolve in the future. The radiogenic strontium isotopic signature (87Sr/86Sr) of the clay fraction in deep sea sediment cores within submarine fans has been used as a record of riverine 87Sr/86Sr composition to gain information about Himalayan weathering intensity. Strontium exists in clay minerals primarily in interlayer sites or adsorbed onto mineral surfaces. Interlayer cation exchange is thought to be completed within rivers during recrystallization or neoformation of clays. A record of chemical weathering intensity in the Himalayas is presented by analyzing the 87Sr/86Sr signature of the clay fraction in sediments from International Ocean Discovery Program (IODP) Expedition 355 Sites U1456 and U1457, located on the Indus Fan, eastern Arabian Sea. This record will be coupled with additional records of bulk grain size and K/Al ratios of clay as potentially additional indicators of weathering intensity. The Sr isotopes in the interstitial waters at each site have also been measured (Carter et al., in press) to verify that the Sr in the treated clay fraction is not being reset by diagenesis in the sedimentary column. Initial results verify that the 87Sr/86Sr values of the clay are less than those in the bulk sediment, as expected, but are not similar to pore fluid Sr. 87Sr/86Sr values of the clays show trends suggesting fluctuations in chemical weathering intensity through time. However, bulk grain size and K/Al ratios results conflict with the 87Sr/86Sr values. If the additional proxy records continue to show conflicting results for "weathering intensity", together they may reveal more information regarding the sedimentary system. Ultimately, the various records will either agree, providing strong evidence for changes in

  7. Thidiazuron: A potent cytokinin for efficient plant regeneration in Himalayan poplar (Populus ciliata Wall. using leaf explants

    Directory of Open Access Journals (Sweden)

    Gaurav Aggarwal

    2012-11-01

    Full Text Available Populus species are important resource for certain branches of industry and have special roles for scientific study on biological and agricultural systems. The present investigation was undertaken with an objective of enhancing the frequency of plant regeneration in Himalayan poplar (Populus ciliata Wall.. The effect of Thiadizuron (TDZ alone and in combination with adenine and α-Naphthalene acetic acid (NAA were studied on the regeneration potential of leaf explants. A high efficiency of shoot regeneration was observed in leaf (80.00% explants on MS basal medium supplemented with 0.024 mg/l TDZ and 79.7 mg/l adenine. Elongation and multiplication of shoots were obtained on Murashige and Skoog (MS basal medium, containing 0.5 mg/l 6. Benzyl aminopurine (BAP + 0.2mg/l Indole 3-acetic acid (IAA + 0.3 mg/l Gibberellic acid (GA3. High frequency root regeneration from in vitro developed shoots was observed on MS basal medium supplemented with 0.10 mg/l Indole 3-butyric acid(IBA. Maximum of the in vitro rooted plantlets were well accomplished to the mixture of sand: soil (1:1 and exhibited similar morphology with the field plants. A high efficiency plant regeneration protocol has been developedfrom leaf explants in Himalayan poplar (Populus ciliata Wall..

  8. Architecture and mineral deposit settings of the Altaid orogenic collage: a revised model

    Science.gov (United States)

    Yakubchuk, Alexander

    2004-09-01

    of the Paleo-Pacific Ocean. Several world-class Cu-(Mo)-porphyry, Cu-Pb-Zn VMS and intrusion-related Au mineral camps, which formed in the Altaids at this stage, coincided with the episodes of plate reorganization and oroclinal bending of magmatic arcs. Major Pb-Zn and Cu sedimentary rock-hosted deposits of Kazakhstan and Central Asia formed in backarc rifts, which developed on the earlier amalgamated fragments. Major orogenic gold deposits are intrusion-related deposits, often occurring within black shale-bearing sutured backarc basins with oceanic crust. After amalgamation of the western Altaids, this part of the collage and adjacent cratons were affected by the Siberian superplume, which ascended at the Permian-Triassic transition. This plume-related magmatism produced various deposits, such as famous Ni-Cu-PGE deposits of Norilsk in the northwest of the Siberian craton. In the early Mesozoic, the eastern Altaids were oroclinally bent together with the overlapping Transbaikal magmatic arc in response to the northward migration and anti-clockwise rotation of the North China craton. The following collision of the eastern portion of the Altaid collage with the Siberian craton formed the Mongol-Okhotsk suture zone, which still links the accretionary wedges of central Mongolia and Circum-Pacific belts. In the late Mesozoic, a system of continent-scale conjugate northwest-trending and northeast-trending strike-slip faults developed in response to the southward propagation of the Siberian craton with subsequent post-mineral offset of some metallogenic belts for as much as 70-400 km, possibly in response to spreading in the Canadian basin. India-Asia collision rejuvenated some of these faults and generated a system of impact rifts.

  9. Critical elements in Carlin, epithermal, and orogenic gold deposits

    Science.gov (United States)

    Goldfarb, Richard J.; Hofstra, Albert H.; Simmons, Stuart F.

    2016-01-01

    Carlin, epithermal, and orogenic gold deposits, today mined almost exclusively for their gold content, have similar suites of anomalous trace elements that reflect similar low-salinity ore fluids and thermal conditions of metal transport and deposition. Many of these trace elements are commonly referred to as critical or near-critical elements or metals and have been locally recovered, although typically in small amounts, by historic mining activities. These elements include As, Bi, Hg, In, Sb, Se, Te, Tl, and W. Most of these elements are now solely recovered as by-products from the milling of large-tonnage, base metal-rich ore deposits, such as porphyry and volcanogenic massive sulfide deposits.A combination of dominance of the world market by a single country for a single commodity and a growing demand for many of the critical to near-critical elements could lead to future recovery of such elements from select epithermal, orogenic, or Carlin-type gold deposits. Antimony continues to be recovered from some orogenic gold deposits and tellurium could potentially be a primary commodity from some such deposits. Tellurium and indium in sphalerite-rich ores have been recovered in the past and could be future commodities recovered from epithermal ores. Carlin-type gold deposits in Nevada are enriched in and may be a future source for As, Hg, Sb, and/or Tl. Some of the Devonian carbonaceous host rocks in the Carlin districts are sufficiently enriched in many trace elements, including Hg, Se, and V, such that they also could become resources. Thallium may be locally enriched to economic levels in Carlin-type deposits and it has been produced from Carlin-like deposits elsewhere in the world (e.g., Alsar, southern Macedonia; Lanmuchang, Guizhou province, China). Mercury continues to be recovered from shallow-level epithermal deposits, as well as a by-product of many Carlin-type deposits where refractory ore is roasted to oxidize carbon and pyrite, and mercury is then

  10. Himalayan River Terraces as A Landscape Response to Quaternary Summer Monsoon Variability

    Science.gov (United States)

    Jonell, T. N.; Clift, P. D.

    2013-12-01

    In order to interpret marine sedimentary archives as records of the erosional response to Asian monsoon variability, we must first recognize how transport processes affect the storage and release of sediment to the ocean. River terraces, such as found in the Greater Himalaya, provide a pivotal role in the source-to-sink story, because this is where sediment storage occurs and is likely modulated. We investigate the role that climate plays in controlling erosion and sediment flux to the Indus delta and fan by looking at the Indus River system, which is dominated by the strong forcing of the Asian monsoon, as well as winter Westerly winds. Paleoceanographic, speleothem, and lacustrine records indicate that summer monsoon intensity was strong from 29 to 37 ka, decreased after that time until ~16 ka, reached maximum intensity from 8 to 10 ka, and then weakened until ~3 ka. Some lacustrine records, however, indicate a more complex pattern of monsoon variability in the Greater Himalaya, which contrasts with monsoonal forcing in central India. This disagreement suggests that floodplains of major river systems may not experience the same climatic conditions as their mountain sources, resulting in contrasting landscape responses to climate change. High altitude river valleys, at least north ofthe Greater Himalaya, appear to be sensitive to monsoon strength because they lie on the periphery of the present rainfall maximum, in the Himalayan rain shadow. These steep river valleys may be affected by landslide damming during periods of increase moisture transport and strong monsoonal precipitation, where damming provides sediment storage through valley-filling and later sediment release through gradual incision or dam-bursting. The Zanskar River, a major tributary to the upper Indus River, provides a record of the erosional response of mountain river valleys to these extreme phases through river terracing. New OSL ages from alluvial terraces indicate reworking of sediment and

  11. Microphysical effects of Saharan dusts on an orogenic thunderstorm

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    T. Hashino

    2008-06-01

    Full Text Available This study investigates the microphysical sensitivity of an orogenic thunderstorm during Genoa 1992 flood event to the concentration and solubility of nucleating aerosols. Idealized 2-D simulations with a new microphysical scheme and a cloud resolving model showed the solubility of CCN can be as important as their concentration. High solubility cases of CCN led to less accumulation of precipitation on the ground and more fraction of the accumulation produced by heavy precipitation than lower solubility cases. The response of vertical motion to the solubility was different for cases with and without dust layer. The preliminary results show that the ice nucleation processes affected by solubility and dust layer may be detected by remote sensing technology.

  12. Black carbon and the Himalayan cryosphere: A review

    Science.gov (United States)

    Gertler, Charles G.; Puppala, Siva Praveen; Panday, Arnico; Stumm, Dorothea; Shea, Joseph

    2016-01-01

    The Himalayan cryosphere borders global hotspots for emissions of black carbon (BC), a carbonaceous aerosol with a short atmospheric lifespan and potentially significant impacts on glaciers and snow cover. BC in the atmosphere absorbs radiation efficiently, leading to localized positive climate forcing. BC may also be deposited onto snow and ice surfaces, thereby changing their albedo. This review presents up-to-date observational data of BC in the atmosphere and in snow and ice, as well as its effects on the cryosphere in the Hindu-Kush-Himalayan (HKH) region along the northern edge of South Asia. Significant spatial variation exists in the measured concentrations of BC in the atmosphere and cryosphere. A strong seasonal pattern exists, with highest concentrations in the pre-monsoon and lowest during the monsoon. Existing observations show bias towards certain areas, with a noticeable lack of measurements on the south side of the Himalaya. Significant uncertainty persists in the emissions estimates of BC in the HKH region, with a standard deviation of regional emissions from various emission inventories of 0.5150 × 10-9 kg m-2 s-1, or 47.1% of the mean (1.0931 × 10-9 kg m-2 s-1). This and other uncertainties, including poor model resolution, imprecision in deposition modeling, and incongruities among measurement types, propagate through simulations of BC concentration in atmosphere and cryosphere. Modeled atmospheric concentrations can differ from observations by as much as a factor of three with no systematic bias, and modeled concentrations in snow and ice can differ from observations by a factor of 60 in certain regions. In the Himalaya, estimates of albedo change due to BC range from about 2 to 10%, estimates of direct radiative forcing due to BC in the atmosphere from (-2)-7 W m-2, and surface forcing estimates from 0 to 28 W m-2, though every forcing estimate uses its own definition, with varying degrees of complexity and numbers of feedbacks. We find the

  13. Wilson cycle passive margins: Control of orogenic inheritance on continental breakup

    DEFF Research Database (Denmark)

    Petersen, Kenni D.; Schiffer, Christian

    2016-01-01

    such tectonic inheritance is generally appreciated, causative physical mechanisms that affect the localization and evolution of rifts and passive margins are not well understood. We use thermo-mechanical modeling to assess the role of orogenic structures during rifting and continental breakup. Such inherited...... thinning in the mantle lithosphere rather than in the crust, and continental breakup is therefore preceded by magmatism. This implies that whether passive margins become magma-poor or magma-rich, respectively, is a function of pre-rift orogenic properties. The models show that structures of orogenic...

  14. Petrogenesis of Triassic granitoids in the East Kunlun Orogenic Belt, northern Tibetan Plateau and their tectonic implications

    Science.gov (United States)

    Shao, Fengli; Niu, Yaoling; Liu, Yi; Chen, Shuo; Kong, Juanjuan; Duan, Meng

    2017-06-01

    The East Kunlun Orogenic Belt (EKOB), an important part of the Greater Tibetan Plateau, is an ideal region for understanding the tectonic evolution of the Anyemaqen Ocean. Here, we present zircon U-Pb ages, bulk-rock major and trace element analyses and Sr-Nd-Hf isotope compositions on representative samples of the syn-collisional Dulan batholith at the eastern end of the EKOB. The zircon U-Pb age data indicate that the bulk of the Dulan batholith was emplaced at 240-235 Ma. The granitoids have high- to medium-K and metaluminous characteristics. They are enriched in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) and depleted in some high field strength elements (HFSEs, e.g., Nb and Ta), while having a flat heavy REE (HREEs) pattern. The mafic magmatic enclaves (MMEs) share the same age, mineralogy and indistinguishable Sr-Nd-Hf isotopes with their granitoid hosts except for the higher HREE abundances. We show that the MMEs represent cumulate formed at earlier stages of the same magmatic system. The trace element data (e.g., Nb/Th, Ta/U) and inherited mantle isotopic characteristics of the Dulan batholith are also consistent with an origin via partial melting of the last fragments of underthrusting ocean crust. Simple mass balance calculations using the Sr-Nd-Hf isotopic data show that 85% Paleo-Tethys MORB and 15% mature crustal material (the Proterozoic gneiss of the study area) contribute to the source of the granitoids. The Dulan batholith shows compositional similarities to the bulk continental curst with inherited mantle isotopic signatures. The syn-collisional felsic magmatism must have contributed to the net continental crust growth in the EKOB. We infer that the Kunlun and Qinling orogens may actually be one single orogen offset later by the Wenquan fault system.

  15. Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Kapil K., E-mail: kkn2104@columbia.edu [Columbia Water Center (India Office), Columbia University, New Delhi 110 016 (India); Gosain, A.K. [Department of Civil Engineering, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi 110 016 (India)

    2013-12-01

    The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11 600 km{sup 2} with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO{sub 3}) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO{sub 3} transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash–Sutcliffe and R{sup 2} correlations greater than + 0.7). Nitrate loading obtained after nitrification, denitrification, and NO{sub 3} removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO{sub 3} concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the

  16. Aerosol-radiation-climate interactions over the Gangetic-Himalayan region

    Science.gov (United States)

    Gautam, Ritesh

    A growing body of evidence indicates that tropospheric aerosols, a major component of the global climate system, significantly influence the Earth's radiation budget and climate forcings. Their multi-faceted impacts on climate with considerable lack of in-depth knowledge of their properties and spatio-temporal distribution makes aerosols one of the least understood components of the Earth's climate. Over heavily polluted regions, the difficulty in quantifying aerosol effects is exacerbated. For example, the South Asian region of which about 1/7th of the world's population lives in the Indo-Gangetic Plains (IGP) is one of the major hotspots of rising pollution due to rapid urbanization/industrialization and growing energy demands. Bounded by the high-altitude Himalayas in the north, the regional climate is largely governed by the summer (southwest) and winter (northeast) monsoons. This dissertation is an attempt to gain reliable insight into the complex interactions between aerosols, radiation and climate of the Gangetic-Himalayan region with a special emphasis on the regional hydrological cycle through the extensive use of multi-sensor satellite data together with ground radiometric measurements. Plausible couplings in the two contrasting seasons (winter and pre-monsoon/summer) namely, between the widespread winter haze and fog; and the connection between pre-monsoon dust transport and summer monsoon rainfall variability were investigated. The spatial and temporal distribution of fog occurrences is found to be influenced by the heavy pollution over the eastern IGP through its microphysical and radiative interactions. During the pre-monsoon period, dust plumes (mixed with local pollution) in the Gangetic-Himalayan (GH) region occurs at elevated altitudes (>5 km) and is found to be significantly absorbing in nature causing enhanced heating in the middle troposphere. There is an increasing trend in the atmospheric loading of absorbing aerosols during the pre

  17. Modeling hydrology, groundwater recharge and non-point nitrate loadings in the Himalayan Upper Yamuna basin.

    Science.gov (United States)

    Narula, Kapil K; Gosain, A K

    2013-12-01

    The mountainous Himalayan watersheds are important hydrologic systems responsible for much of the water supply in the Indian sub-continent. These watersheds are increasingly facing anthropogenic and climate-related pressures that impact spatial and temporal distribution of water availability. This study evaluates temporal and spatial distribution of water availability including groundwater recharge and quality (non-point nitrate loadings) for a Himalayan watershed, namely, the Upper Yamuna watershed (part of the Ganga River basin). The watershed has an area of 11,600 km(2) with elevation ranging from 6300 to 600 m above mean sea level. Soil and Water Assessment Tool (SWAT), a physically-based, time-continuous model, has been used to simulate the land phase of the hydrological cycle, to obtain streamflows, groundwater recharge, and nitrate (NO3) load distributions in various components of runoff. The hydrological SWAT model is integrated with the MODular finite difference groundwater FLOW model (MODFLOW), and Modular 3-Dimensional Multi-Species Transport model (MT3DMS), to obtain groundwater flow and NO3 transport. Validation of various modules of this integrated model has been done for sub-basins of the Upper Yamuna watershed. Results on surface runoff and groundwater levels obtained as outputs from simulation show a good comparison with the observed streamflows and groundwater levels (Nash-Sutcliffe and R(2) correlations greater than +0.7). Nitrate loading obtained after nitrification, denitrification, and NO3 removal from unsaturated and shallow aquifer zones is combined with groundwater recharge. Results for nitrate modeling in groundwater aquifers are compared with observed NO3 concentration and are found to be in good agreement. The study further evaluates the sensitivity of water availability to climate change. Simulations have been made with the weather inputs of climate change scenarios of A2, B2, and A1B for end of the century. Water yield estimates under

  18. Himalayan origin and evolution of Myricaria (Tamaricaeae in the neogene.

    Directory of Open Access Journals (Sweden)

    Ming-Li Zhang

    Full Text Available BACKGROUND: Myricaria consists of about twelve-thirteen species and occurs in Eurasian North Temperate zone, most species in the Qinghai-Tibet Plateau (QTP and adjacent areas. METHODOLOGY/PRINCIPAL FINDINGS: Twelve species of Myricaria plus two other genera Tamarix and Reaumuria in Tamaricaceae, were sampled, and four markers, ITS, rps16, psbB-psbH, and trnL-trnF were sequenced. The relaxed Bayesian molecular clock BEAST method was used to perform phylogenetic analysis and molecular dating, and Diva, S-Diva, and maximum likelihood Lagrange were used to estimate the ancestral area. The results indicated that Myricaria could be divided into four phylogenetic clades, which correspond to four sections within the genus, of them two are newly described in this paper. The crown age of Myricaria was dated to early Miocene ca. 20 Ma, at the probable early uplifting time of the Himalayas. The Himalayas were also shown as the center of origin for Myricaria from the optimization of ancestral distribution. Migration and dispersal of Myricaria were indicated to have taken place along the Asian Mountains, including the Himalayas, Kunlun, Altun, Hendukosh, Tianshan, Altai, and Caucasus etc., westward to Europe, eastward to Central China, and northward to the Mongolian Plateau. CONCLUSIONS/SIGNIFICANCE: Myricaria spatiotemporal evolution presented here, especially the Himalayan origin at early Miocene ca. 20 Ma, and then migrated westward and eastward along the Asian mountains, offers a significant evolutionary case for QTP and Central Asian biogeography.

  19. Herbarium specimens show contrasting phenological responses to Himalayan climate.

    Science.gov (United States)

    Hart, Robbie; Salick, Jan; Ranjitkar, Sailesh; Xu, Jianchu

    2014-07-22

    Responses by flowering plants to climate change are complex and only beginning to be understood. Through analyses of 10,295 herbarium specimens of Himalayan Rhododendron collected by plant hunters and botanists since 1884, we were able to separate these responses into significant components. We found a lack of directional change in mean flowering time over the past 45 y of rapid warming. However, over the full 125 y of collections, mean flowering time shows a significant response to year-to-year changes in temperature, and this response varies with season of warming. Mean flowering advances with annual warming (2.27 d earlier per 1 °C warming), and also is delayed with fall warming (2.54 d later per 1 °C warming). Annual warming may advance flowering through positive effects on overwintering bud formation, whereas fall warming may delay flowering through an impact on chilling requirements. The lack of a directional response suggests that contrasting phenological responses to temperature changes may obscure temperature sensitivity in plants. By drawing on large collections from multiple herbaria, made over more than a century, we show how these data may inform studies even of remote localities, and we highlight the increasing value of these and other natural history collections in understanding long-term change.

  20. The Invisible Path of Karma in a Himalayan Purificatory Rite

    Directory of Open Access Journals (Sweden)

    Arik Moran

    2018-03-01

    Full Text Available Indic rites of purification aim to negate the law of karma by removing the residues of malignant past actions from their patrons. This principle is exemplified in the Kahika Mela, a rarely studied religious festival of the West Himalayan highlands (Himachal Pradesh, India, wherein a ritual specialist assumes karmic residues from large publics and then sacrificed to their presiding deity. British officials who had ‘discovered’ this purificatory rite at the turn of the twentieth century interpreted it as a variant of the universal ‘scapegoat’ rituals that were then being popularized by James Frazer and found it loosely connected to ancient Tantric practises. The However, observing a recent performance of the ritual significantly complicated this view. This paper proposes a novel reading of the Kahika Mela through the prism of karmic transference. Tracing the path of karmas from participants to ritual specialist and beyond, it delineates the logic behind the rite, revealing that the culminating act of human sacrifice is, in fact, secondary to the mysterious force that impels its acceptance.

  1. Orogenic gold: Common or evolving fluid and metal sources through time

    Science.gov (United States)

    Goldfarb, Richard J.; Groves, David I.

    2015-09-01

    generations, many which are not related to ore formation. Radiogenic isotopes, such as those of Pb, Sr, Nd, Sm, and Os, measured on hydrothermal minerals are even more difficult to interpret for defining metal source, particularly as the low-salinity ore fluids transport limited amounts of these elements and significant amounts of these may be locally added to the minerals during alteration reactions at the sites of gold deposition. Noble gas and halogen data are equally equivocal. Fluid exsolution from granitoids emplaced into the upper and middle crust, metamorphism of the crust, or fluids entering trans-crustal fault zones from below the crust all remain as permissive scenarios associated with orogenic gold formation, as the abundant geochemical data are equivocal. However, geological and geochronological data weigh heavily against a magmatic-hydrothermal model in the upper to middle crust. There is no universal temporal association between orogenic gold and magmatism, and where there is an overlap in age, there is no specific type of magmatism consistently associated with gold formation, nor element zonation around any specific pluton. A crustal metamorphic model for fluid and metal sources is very consistent with geological, geochronological, and geochemical data, although metamorphism on a regional scale that releases these components into major fault zones can be associated with many processes along active continental margins. These can include crustal thickening and radiogenic heating, slab rollback and heating during crustal extension, or subduction of a spreading ridge heating the base of an accretionary prism. In rare examples where Phanerozoic orogenic gold deposits are hosted in Precambrian high-grade metamorphic terranes, fluids and metals must, however, enter a transcrustal fault system from a sub-crustal source. This could either be a devolatilized, subducted, relatively flat, perhaps stalled slab and its overlying sediment, or the corner of the fertilized

  2. Climate change effects in the Western Himalayan ecosystems of India: evidence and strategies

    Directory of Open Access Journals (Sweden)

    Vindhya Prasad Tewari

    2017-08-01

    Full Text Available Background The fragile landscapes of the Himalayan region are highly susceptible to natural hazards, and there is ongoing concern about current and potential climate change impacts. This study provides background information on India’s Western Himalayas and reviews evidence of warming as well as variability in precipitation and extreme events. Methods Understanding and anticipating the impacts of climate change on Himalayan forest ecosystems and the services they provide to people are critical. Efforts to develop and implement effective policies and management strategies for climate change mitigation and adaptation requires particular new research initiatives. The various studies initiated and conducted in the region are compiled here. Results Several new initiatives taken by the Himalayan Forest Research Institute in Shimla are described. This includes new permanent observational field studies, some with mapped trees, in high altitude transitional zones for continuous monitoring of vegetation response. We have also presented new strategies for mitigating potential climate change effects in Himalayan forest ecosystems. Conclusions Assessment of the ecological and genetic diversity of the Himalayan conifers is required to evaluate potential responses to changing climatic conditions. Conservation strategies for the important temperate medicinal plants need to be developed. The impact of climate change on insects and pathogens in the Himalayas also need to be assessed. Coordinated efforts are necessary to develop effective strategies for adaptation and mitigation.

  3. EARLY PRECAMBRIAN CRUSTAL EVOLUTION OF THE BELOMORIAN AND TRANS-NORTH CHINA OROGENS AND SUPERCONTINENTS RECONSTRUCTION

    Directory of Open Access Journals (Sweden)

    A. I. Slabunov

    2017-01-01

    Full Text Available Comparative analysis of the crustal evolution of the Early Precambrian Belomorian and Trans-North China orogens (Fig. 1 has shown [Slabunov et al., 2015] that: Both belts were formed by the superposition of two Precambrian orogenies. The earth crust of the Belomorian belt was produced during the Mesoarchaean to Neoarchaean Belomorian collisional orogeny [Slabunov, 2008; Slabunov et al., 2006] and then was reworked during the Palaeoproterozoic Lapland-Kola collisional orogeny [Daly at al., 2006; Balagansky et al., 2014]. The earth crust of the Trans-North China orogen was formed during a Neoarchean accretionary orogeny and then was reworked during a Paleoproterozoic collisional orogeny [Zhao et al., 2012; Guo et al., 2012, 2005]. The Lapland granulite belt is the core of the Lapland-Kola Palaeoproterozoic collisional orogen in the Fennoscandian shield and the Khondolite belt occupies the same tectonic position in a Palaeoproterozoic collisional orogen in the North China craton.

  4. Landslide Hazard Assessment near Kedarnath Temple in Himalayan region considering cloudburst tragedy in 2013

    Science.gov (United States)

    Ansari, T. A.; Singh, T. N., Sr.

    2017-12-01

    The world famous Shri Kedarnath Temple in Uttarakhand state of India is located in the western extremity of the young and dynamically active Central Himalaya. As Indian plate is moving towards Eurasian plate which has steep slopes, highly variable altitudes and uncertain climatic conditions. Due to high seismic activity Himalayan rock mass is highly fractured, shattered and inherently weakness pose threat for landslide. On 16th and 17th June 2013, was witness an extreme climatic events of century in the history of the region, the high intensity rainfall, (> 400mm) caused number of landslide which have adverse economic and societal impacts, including the potential for heavy loss of human and widespread devastation of natural resources, infrastructures. The study region is at high altitude around 3583 meters, which is affected from impact of glacial melt due to climate change and future increase in rainfall subjected to high level uncertainty of landslides. Aerial and field survey has been done of the region and most vulnerable landslide locations of hill slope and road cut slope are studied for future prospect of safety. SLIDE 6.0, PHASE27 (numerical software) for slope stability, geomechanical profile of rock and kinematics analysis to know the type of failures. Rock quality tunneling index (Q), Geological strength (GSI), Slope mass Rating (SMR) and factor of safety were determined to know the slope instability. Our finding provides an important aspect for future safety as provide the information for landslide warning system and engineering countermeasures.

  5. Seismic vulnerability of the Himalayan half-dressed rubble stone masonry structures, experimental and analytical studies

    Directory of Open Access Journals (Sweden)

    N. Ahmad

    2012-11-01

    Full Text Available Half-Dressed rubble stone (DS masonry structures as found in the Himalayan region are investigated using experimental and analytical studies. The experimental study included a shake table test on a one-third scaled structural model, a representative of DS masonry structure employed for public critical facilities, e.g. school buildings, offices, health care units, etc. The aim of the experimental study was to understand the damage mechanism of the model, develop damage scale towards deformation-based assessment and retrieve the lateral force-deformation response of the model besides its elastic dynamic properties, i.e. fundamental vibration period and elastic damping. The analytical study included fragility analysis of building prototypes using a fully probabilistic nonlinear dynamic method. The prototypes are designed as SDOF systems assigned with lateral, force-deformation constitutive law (obtained experimentally. Uncertainties in the constitutive law, i.e. lateral stiffness, strength and deformation limits, are considered through random Monte Carlo simulation. Fifty prototype buildings are analyzed using a suite of ten natural accelerograms and an incremental dynamic analysis technique. Fragility and vulnerability functions are derived for the damageability assessment of structures, economic loss and casualty estimation during an earthquake given the ground shaking intensity, essential within the context of risk assessment of existing stock aiming towards risk mitigation and disaster risk reduction.

  6. Thermal modeling and parametric studies of a greenhouse fish pond in the Central Himalayan Region

    International Nuclear Information System (INIS)

    Sarkar, Bikash; Tiwari, G.N.

    2006-01-01

    This study describes the thermal modeling and its validation of greenhouse fish pond systems. Numerical computations have been performed for a typical day in the month of June, 2005, for the climatic condition of Champawat in the Central Himalayan Region. The energy balance equations have been written considering the effects of conduction, convection, radiation, evaporation and ventilation. The governing equations are numerically solved with Matlab 7.0 software to predict the water temperature. A parametric study has also been performed to find the effects of various parameters, namely the number of air changes per hour, the transmissivity (τ) and the isothermal mass and height of the greenhouse. It is observed that there is no significant effect in the parametric studies on water temperature due to the larger isothermal mass. The model has been validated with experimental data. On an average, the even span passive greenhouse fish pond can increase the inside temperature 4.14 deg. C higher than the temperature of an outdoor pond. Statistical analysis shows that the predicted and experimental values of water temperature exhibited fair agreement with a coefficient of correlation r = 0.90 and root mean square percent deviation e = 1.67%

  7. Snowmelt runoff prediction under changing climate in the Himalayan cryosphere: A case of Gilgit River Basin

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    Muhammad Adnan

    2017-09-01

    Full Text Available There are serious concerns of rise in temperatures over snowy and glacierized Himalayan region that may eventually affect future river flows of Indus river system. It is therefore necessary to predict snow and glacier melt runoff to manage future water resource of Upper Indus Basin (UIB. The snowmelt runoff model (SRM coupled with MODIS remote sensing data was employed in this study to predict daily discharges of Gilgit River in the Karakoram Range. The SRM was calibrated successfully and then simulation was made over four years i.e. 2007, 2008, 2009 and 2010 achieving coefficient of model efficiency of 0.96, 0.86, 0.9 and 0.94 respectively. The scenarios of precipitation and mean temperature developed from regional climate model PRECIS were used in SRM model to predict future flows of Gilgit River. The increase of 3 °C in mean annual temperature by the end of 21th century may result in increase of 35–40% in Gilgit River flows. The expected increase in the surface runoff from the snow and glacier melt demands better water conservation and management for irrigation and hydel-power generation in the Indus basin in future.

  8. Les premières années de The Himalayan Journal (1929-1940

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    Michel Raspaud

    2001-05-01

    Full Text Available IntroductionLa création de The Himalayan Club, sur le territoire de l’Empire des Indes à la fin de l’année 1927, s’accompagne presque aussitôt de la publication de The Himalayan Journal, en février 1929, soit mois de dix-huit mois après la création officielle de l’institution. L’objet du présent texte concerne donc la vie de The Himalayan Club lors de ses premières années d’existence, depuis la date de sa création jusqu’au début de la seconde guerre mondiale. Cependant, l’intérêt se focaliser...

  9. Case Report Associated with Aspergillosis and Hepatitis E Virus Coinfection in Himalayan Griffons

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    Heng Li

    2015-01-01

    Full Text Available This study involved a death which occurred in four Himalayan griffons housed in Beijing zoo, China. Based on pathogen identification and the pathological changes observed, we did characterize the fungi and Hepatitis E virus (HEV in four dead Himalayan griffons. Pathological changes were severe. Membranous-like material was observed on the surface of the internal organs. Spleen was necrotic. Focal lymphocyte infiltration in the liver and many sunflower-like fungi nodules were evident in the tissues, especially in the kidney. PCR was used to identify the pathogen. Based on the 18SrRNA genomic sequence of known fungi, the results confirmed that all four dead Himalayan griffons were infected with Aspergillus. At the same time the detection of HEV also showed positive results. To the best of our knowledge, this work appears to be the first report of concurrent presence of Aspergillosis and Hepatitis E virus in rare avian species.

  10. Enhancing Earth Observation Capacity in the Himalayan Region

    Science.gov (United States)

    Shrestha, B. R.

    2012-12-01

    Earth observations bear special significance in the Himalayan Region owing to the fact that routine data collections are often hampered by highly inaccessible terrain and harsh climatic conditions. The ongoing rapid environmental changes have further emphasized its relevance and use for informed decision-making. The International Center for Integrated Mountain Development (ICIMOD), with a regional mandate is promoting the use of earth observations in line with the GEOSS societal benefit areas. ICIMOD has a proven track record to utilize earth observations notably in the areas of understanding glaciers and snow dynamics, disaster risk preparedness and emergency response, carbon estimation for community forestry user groups, land cover change assessment, agriculture monitoring and food security analysis among others. This paper presents the challenges and lessons learned as a part of capacity building of ICIMOD to utilize earth observations with the primary objectives to empower its member countries and foster regional cooperation. As a part of capacity building, ICIMOD continues to make its efforts to augment as a regional resource center on earth observation and geospatial applications for sustainable mountain development. Capacity building possesses multitude of challenges in the region: the complex geo-political reality with differentiated capacities of member states, poorer institutional and technical infrastructure; addressing the needs for multiple user and target groups; integration with different thematic disciplines; and high resources intensity and sustainability. A capacity building framework was developed based on detailed needs assessment with a regional approach and strategy to enhance capability of ICIMOD and its network of national partners. A specialized one-week training course and curriculum have been designed for different thematic areas to impart knowledge and skills that include development practitioners, professionals, researchers and

  11. Recent Surveys of Sedimentary Records of Himalayan Uplift and Sea Level Changes in the Bay of Bengal

    Science.gov (United States)

    Spiess, V.; Schwenk, T.; Kudrass, H.; France-Lanord, C.

    2006-12-01

    The Ganges-Brahmaputra River System connects the Himalayan Mountain Range and Tibetan Plateau with the Bay of Bengal, providing sedimentary records of terrestrial climatic conditions and their changes under the strong influence of the monsoonal system to the Bengal sediment fan. The shelf of Bangladesh, the shelf canyon Swatch of no Ground, the continental slope and sedimentary fan receive large volumes of sediments, documenting on different time scales from annual near the shelf to millennial on the slope to million year time scales in the lower fan transport processes, weathering conditions, vegetation and precipitation changes. Research Cruise SO188 with R/V Sonne in June/July 2006 provided new insight into sediment transport processes in the Bengal Fan and deposits suitable to drilling targeting for high resolution studies of terrestrial processes and sea level changes. The survey collected high resolution multichannel seismic data to support an IODP drilling transect at 8°N and to collect further data to reconstruct the source-to-sink fate of sediment in the Himalayan-Bengal System. An extensive high-resolution 3D seismic survey targeted for fine- scale lithology and facies distribution and sediment structures in the vicinity of a meandering channel. Significant subsidence on the Bengal shelf, continuously providing accommodation space over the last few million years, is documented in a dense grid of seismic lines across the Bengal shelf and the Swatch of no Ground shelf canyon. Promising locations for IODP drilling had been investigated and will be integrated in an IODP proposal for shelf, slope and canyon drilling to study the Holocene and pre-Holocene history in up to 1500 m thick sequences.

  12. Phytochemical and antimicrobial activities of Himalayan Cordyceps sinensis (Berk.) Sacc.

    Science.gov (United States)

    Mamta; Mehrotra, Shubhi; Amitabh; Kirar, Vandana; Vats, Praveen; Nandi, Shoma Paul; Negi, P S; Misra, Kshipra

    2015-01-01

    This study evaluated the phytochemical and antimicrobial activities and also quantified bioactive nucleoside using high performance thin layer chromatography (HPTLC) of five extracts of Indian Himalayan Cordyceps sinensis prepared with different solvents employing accelerated solvent extraction (ASE) technique. The phytochemical potential of these extracts was quantified in terms of total phenolic and total flavonoid content while antioxidant activities were determined by 1,1-diphenyl-2-pycryl-hydrazyl (DPPH) and 2,2 -azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and ferric-reducing antioxidant power (FRAP) assays. Total reducing power (TRP) was determined by converting iron (III) into iron (II) reduction assay. CS(50%Alc) (15.1 ± 0.67mg/g of dry extract) and CS(100%Alc) (19.3 ± 0.33 mg/g of dry extract) showed highest phenolic and flavonoid content, respectively while CS(Aq) extract showed maximum antioxidant activity and the highest concentration of the three nucleosides (adenine 12.8 ± 0.49 mg/g, adenosine 0.36 ± 0.28 mg/g and uracil 0.14 ± 0.36 mg/g of dry extract) determined by HPTLC. The evaluation of extracts for antimicrobial activity against gram-negative and gram-positive bacterial strains showed CS(25%Alc), CS(75%Alc) and CS(100%Alc) extract to be more effective against E. coli, P. aerugenosa and B. subtilis giving 9, 7 and 6.5 mm of zone of inhibition (ZOI) in 93.75, 93.75 and 45 μg concentration, respectively, whereas CS(Aq) extract showed minimal inhibition against these.

  13. Himalayan porter's specialization: metabolic power, economy, efficiency and skill.

    Science.gov (United States)

    Minetti, Alberto E; Formenti, Federico; Ardigò, Luca P

    2006-11-07

    Carrying heavy loads in the Himalayan region is a real challenge. Porters face extreme ranges in terrain condition, path steepness, altitude hypoxia and climate for 6-8h a day, many months a year, since they were boys. It has been previously shown that, when carrying loads on level terrain, porters' metabolic economy is higher than in Caucasians but the reasons are still unknown. We monitored Nepalese porters both during 90 km trekking in Khumbu Valley and at two different altitudes (3490 and 5050 m above sea-level), where they were compared to Caucasian mountaineers during (22%) gradient walking. Both subject groups carried a load of up to 90% body mass. The remarkably higher performance of porters during uphill locomotion (+60% in speed, +39% mechanical power) is only partly explained by the lower cost of loaded walking (-20%), being also the result of a better cardio-circulatory adaptation to altitude, which generates a higher mass-specific metabolic power (+30%). Consequently, Nepalese porters show higher efficiency, both during uphill and downhill loaded walking. Their higher economy on steep paths cannot be ascribed to a better exchange between potential and kinetic energy, as in our experiments the body centre of mass travelled monotonically uphill (or downhill). A different oscillation pattern of the loaded head-trunk segment, together with the analysis of the different components of the mechanical work during load carrying, suggests that achieved motor skills in balancing the loaded body segment above the hip could play a role in determining the better economy of porters.

  14. Saussurea species in Indian Himalayan Region: diversity, distribution and indigenous uses

    OpenAIRE

    Jitendra Singh Butola; Sher S. Samant

    2010-01-01

    In spite of the high economic value of the Saussurea species in the Indian Himalayan Region (IHR), the potential of most of the species is yet to be investigated. Therefore, an attempt has been made to study the diversity, distribution, habitat preference, nativity, endemism, status and indigenous uses of Saussurea species in the IHR. A total of 62 species were recorded from the IHR; of these, 37 species were native to the Himalayan region, 8 were endemic and 21 were near endemic to the IHR. ...

  15. Increasing risk of glacial lake outburst floods as a consequence of climate change in the Himalayan region

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    Somana Riaz

    2014-03-01

    Full Text Available The greater Himalayan Mountains host the largest snow covered area outside the polar regions and serves as the source for some of the major fluvial systems of the world. The region acts as the lifeline for approximately 10% of the world’s population. The terrain is geologically active, highly susceptible to climate change processes and plays a significant role in global hydro-meteorological cycles and biodiversity. With the increasing impacts of climate change to the glaciers and ice caps during the past few decades, people living in the Himalayas have become vulnerable to a higher risk of floods, avalanches and glacial lake outburst floods(GLOFs. This study reviewed the work carried out by earlier researchers to understand the history and science of GLOFs and their potential risk to the communities in the Himalayanbelt, particularly in Pakistan.

  16. Titanite-bearing calc-silicate rocks constrain timing, duration and magnitude of metamorphic CO2 degassing in the Himalayan belt

    Science.gov (United States)

    Rapa, Giulia; Groppo, Chiara; Rolfo, Franco; Petrelli, Maurizio; Mosca, Pietro; Perugini, Diego

    2017-11-01

    The pressure, temperature, and timing (P-T-t) conditions at which CO2 was produced during the Himalayan prograde metamorphism have been constrained, focusing on the most abundant calc-silicate rock type in the Himalaya. A detailed petrological modeling of a clinopyroxene + scapolite + K-feldspar + plagioclase + quartz ± calcite calc-silicate rock allowed the identification and full characterization - for the first time - of different metamorphic reactions leading to the simultaneous growth of titanite and CO2 production. The results of thermometric determinations (Zr-in-Ttn thermometry) and U-Pb geochronological analyses suggest that, in the studied lithology, most titanite grains grew during two nearly consecutive episodes of titanite formation: a near-peak event at 730-740 °C, 10 kbar, 30-26 Ma, and a peak event at 740-765 °C, 10.5 kbar, 25-20 Ma. Both episodes of titanite growth are correlated with specific CO2-producing reactions and constrain the timing, duration and P-T conditions of the main CO2-producing events, as well as the amounts of CO2 produced (1.4-1.8 wt% of CO2). A first-order extrapolation of such CO2 amounts to the orogen scale provides metamorphic CO2 fluxes ranging between 1.4 and 19.4 Mt/yr; these values are of the same order of magnitude as the present-day CO2 fluxes degassed from spring waters located along the Main Central Thrust. We suggest that these metamorphic CO2 fluxes should be considered in any future attempts of estimating the global budget of non-volcanic carbon fluxes from the lithosphere.

  17. Continental Growth and Recycling in Convergent Orogens with Large Turbidite Fans on Oceanic Crust

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    Ben D. Goscombe

    2013-07-01

    Full Text Available Convergent plate margins where large turbidite fans with slivers of oceanic basement are accreted to continents represent important sites of continental crustal growth and recycling. Crust accreted in these settings is dominated by an upper layer of recycled crustal and arc detritus (turbidites underlain by a layer of tectonically imbricated upper oceanic crust and/or thinned continental crust. When oceanic crust is converted to lower continental crust it represents a juvenile addition to the continental growth budget. This two-tiered accreted crust is often the same thickness as average continental crustal and is isostatically balanced near sea level. The Paleozoic Lachlan Orogen of eastern Australia is the archetypical example of a tubidite-dominated accretionary orogeny. The Neoproterozoic-Cambrian Damaran Orogen of SW Africa is similar to the Lachlan Orogen except that it was incorporated into Gondwana via a continent-continent collision. The Mesozoic Rangitatan Orogen of New Zealand illustrates the transition of convergent margin from a Lachlan-type to more typical accretionary wedge type orogen. The spatial and temporal variations in deformation, metamorphism, and magmatism across these orogens illustrate how large volumes of turbidite and their relict oceanic basement eventually become stable continental crust. The timing of deformation and metamorphism recorded in these rocks reflects the crustal thickening phase, whereas post-tectonic magmatism constrains the timing of chemical maturation and cratonization. Cratonization of continental crust is fostered because turbidites represent fertile sources for felsic magmatism. Recognition of similar orogens in the Proterozoic and Archean is important for the evaluation of crustal growth models, particularly for those based on detrital zircon age patterns, because crustal growth by accretion of upper oceanic crust or mafic underplating does not readily result in the addition of voluminous zircon

  18. Anatexis witnessed post-collisional evolution of the Dabie orogen, China

    Science.gov (United States)

    Xu, Haijin; Zhang, Junfeng

    2017-09-01

    Crustal anatexis plays a significant role in the processes of orogenic evolution. We carried out a combined study of structure, U-Pb age and trace element on zircons from leucosome-based migmatites in the North Dabie zone to provide information on crustal anatexis during the evolution of the Dabie orogen. Protoliths of the migmatites are Middle Neoproterozoic (ca. 780-710 Ma) magmatic rocks that belong to the South China Block. They underwent a relatively low-T eclogite-facies metamorphism during the Middle to Late Triassic (235-225 Ma) continental subduction and collision. An over-thickened crustal root was formed and the Dabie orogen entered into the stage of post-collisional evolution after the Triassic. The earliest anatexis occurred at ca. 185 Ma; the anatexis in the Jurassic was weak and gentle due to episodic flow of metamorphic fluids with a prolonged interval. Nevertheless, it indicates that the crustal root started to become ductile and unstable at that time. Extensive epsodic anatexis occurred between ca. 160 Ma and 110 Ma. As the anatexis became stronger, more extensive and uninterrupted, the anatectic products changed gradually from low-degree migmatites to high-degree migmatites. The beginning of extensive anatexis at ∼160 Ma marks the beginning of orogenic activation. The duration of ca. 160-145 Ma corresponds to the orogenic activation when the collision-thickened crust still remained, whereas the period of ca. 145-110 Ma is in accordance with the orogenic collapse. The peak period of anatexis (ca. 145-125 Ma) was accompanied by plutonism, high-T granulite-facies metamorphism, extensional uplift and subsequent delamination of crustal root. After that, the anatexis trailed off until ca. 110 Ma. The long lasting multistage anatexis recorded in the migmatites has witnessed the evolution of the Dabie orogen in the postcollisional stage.

  19. The distribution, geochronology and geochemistry of early Paleozoic granitoid plutons in the North Altun orogenic belt, NW China: Implications for the petrogenesis and tectonic evolution

    Science.gov (United States)

    Meng, Ling-Tong; Chen, Bai-Lin; Zhao, Ni-Na; Wu, Yu; Zhang, Wen-Gao; He, Jiang-Tao; Wang, Bin; Han, Mei-Mei

    2017-01-01

    Abundant early Paleozoic granitoid plutons are widely distributed in the North Altun orogenic belt. These rocks provide clues to the tectonic evolution of the North Altun orogenic belt and adjacent areas. In this paper, we report an integrated study of petrological features, U-Pb zircon dating, in situ zircon Hf isotope and whole-rock geochemical compositions for the Abei, 4337 Highland and Kaladawan Plutons from north to south in the North Altun orogenic belt. The dating yielded magma crystallization ages of 514 Ma for the Abei Pluton, 494 Ma for the 4337 Highland Pluton and 480-460 Ma for the Kaladawan Pluton, suggesting that they are all products of oceanic slab subduction because of the age constraint. The Abei monzogranites derived from the recycle of Paleoproterozoic continental crust under low-pressure and high-temperature conditions are products of subduction initiation. The 4337 Highland granodiorites have some adakitic geochemical signatures and are sourced from partial melting of thickened mafic lower continental crust. The Kaladawan quartz diorites are produced by partial melting of mantle wedge according to the positive εHf(t) values, and the Kaladawan monzogranite-syenogranite are derived from partial melting of Neoproterozoic continental crust mixing the juvenile underplated mafic material from the depleted mantle. These results, together with existing data, provide significant information about the evolution history of oceanic crust subduction during the 520-460 Ma. The initiation of subduction occurred during 520-500 Ma with formation of Abei Pluton; subsequent transition from steep-angle to flat-slab subduction at ca.500 Ma due to the arrival of buoyant oceanic plateaus, which induces the formation of 4337 Highland Pluton. With ongoing subduction, the steep-angle subduction system is reestablished to cause the formation of 480-460 Ma Kaladawan Pluton. Meanwhile, it is this model that account for the temporal-spatial distribution of these early

  20. 40 Ma of hydrothermal W mineralization during the Variscan orogenic evolution of the French Massif Central revealed by U-Pb dating of wolframite

    Science.gov (United States)

    Harlaux, Matthieu; Romer, Rolf L.; Mercadier, Julien; Morlot, Christophe; Marignac, Christian; Cuney, Michel

    2018-01-01

    We present U-Pb thermal ionization mass spectrometer (TIMS) ages of wolframite from several granite-related hydrothermal W±Sn deposits in the French Massif Central (FMC) located in the internal zone of the Variscan belt. The studied wolframite samples are characterized by variable U and Pb contents (typically <10 ppm) and show significant variations in their radiogenic Pb isotopic compositions. The obtained U-Pb ages define three distinct geochronological groups related to three contrasting geodynamic settings: (i) Visean to Namurian mineralization (333-327 Ma) coeval with syn-orogenic compression and emplacement of large peraluminous leucogranites (ca. 335-325 Ma), (ii) Namurian to Westphalian mineralization (317-315 Ma) synchronous with the onset of late-orogenic extension and emplacement of syn-tectonic granites (ca. 315-310 Ma) and (iii) Stephanian to Permian mineralization (298-274 Ma) formed during post-orogenic extension contemporaneous with the Permian volcanism in the entire Variscan belt. The youngest ages (276-274 Ma) likely reflect the reopening of the U-Pb isotopic system after wolframite crystallization and may correspond to late hydrothermal alteration (e.g. ferberitization). Our results demonstrate that W(±Sn) mineralization in the FMC formed during at least three distinct hydrothermal events in different tectono-metamorphic settings over a time range of 40 Ma.

  1. Spatial gradients in freshwater fish diversity, abundance and current pattern in the Himalayan region of Upper Ganges Basin, India

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    AJEY KUMAR PATHAK

    2014-10-01

    Full Text Available Pathak AK, Sarkar UK, Singh SP. 2014. Spatial gradients in freshwater fish diversity, abundance and current pattern in the Himalayan region of Upper Ganges Basin, India. Biodiversitas 15: 186-194.The present study describes the analysis and mapping of the different measurements of freshwater fish biodiversity of the Upper Ganges basin in the Himalayan region using spatial interpolation methods of Geographical Information System. The diversity, richness and abundance of fishes for each sampling location were determined and Kriging interpolation was applied on each fisheries measurement to predict and produce semivariogram. The semivariogarms produced were cross validated and reclassified. The reclassified maps for richness, abundance and diversity of fishes, occurrence of cold water threatened fish and abundance of important genera like Tor, Schziothorax and species were produced. The result of the Kriging produced good results and overall error in the estimation process was found significant. The cross validation of semovariograms also provided a better result with the observed data sets. Moreover, weighted overlay analysis of the reclassified raster maps of richness and abundance of fishes produced the classified raster map at different evaluation scale (0-10 qualitatively describing the gradient of species richness and abundance compositely. Similarly, the classified raster map at same evaluation scale qualitatively describing the gradient of species abundance and diversity compositely was produced and published. Further, basin wise analysis between Alaknanda/Pindar and Ganga1 sub basins showed 0.745 disparities at 0.745 distances in 2 dimensional spaces. The richness, diversity and abundance of threatened fishes among the different sampling locations were not significant (p = 0.9.

  2. Sone megafan: A non-Himalayan megafan of craton origin on the southern margin of the middle Ganga Basin, India

    Science.gov (United States)

    Sahu, Sudarsan; Saha, Dipankar; Dayal, Shankar

    2015-12-01

    Researchers in the last few decades have focused on the fluvial megafans at the base of Himalayan foothills in the Ganga Basin. No major effort has so far been made to delineate any such large depositional environment at the base of the northern Indian peninsular craton at the distal parts of the basin. In this work, for the first time, we document a megafan, unusually created by the cratonic Sone River in the marginal plains south of the Ganga. The geomorphology of the megafan surface, distribution of palaeochannels, sedimentology, and areal extent of the megafan are described. The study also reconstructs the tectonic and palaeoclimatic conditions, which might have helped in sediment supply from the cratonic catchment areas of the Sone. We suggest tectonic control over the Sone River channel dynamics and development of the megafan. The oval- and fan-shaped, craton-derived sediment body covers an area of around 12,000 km2 in the marginal plains and about 9000 km2 in the central alluvium north of the Ganga River. The megafan is around 190 km long and 240 km wide. The mean slope of the megafan surface is 0.03°. An onlap of Himalayan sediments has occurred over the megafan at its toe parts caused by southward encroachment of the Ganga during the Holocene. The megafan sediments comprise brownish yellow fine to coarse sand and gravels with an admixture of carbonaceous nodules (kankars). The thickness of the megafan sediment, which directly overlies the Precambrian basement, varies from only a few meters in the south near the peninsular craton to 1000 m at the north in the central alluvial plain. The granular zones form prolific aquifer systems in an otherwise poor hydrogeological setting of the marginal plains.

  3. Nutritional profile of phytococktail from trans-Himalayan plants.

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    Priyanka Dhar

    Full Text Available We estimated the nutritive value, vitamin content, amino acid composition, fatty acid content, and mineral profile of a phytococktail comprising sea buckthorn (Hippophae rhamnoides, apricot (Prunus armeniaca, and roseroot (Rhodiola imbricata from trans-Himalaya. The free vitamin forms in the phytococktail were determined by rapid resolution liquid chromatography/tandem mass spectrometry (RRLC-MS/MS. Vitamin E and B-complex vitamins were detected as the principle vitamins. Reversed-phase high performance liquid chromatography (RP-HPLC with pre-column derivatization was used for identification and quantification of amino acids. Eight essential and eleven non-essential amino acids were quantified, and the content ranged between 76.33 and 9485.67 µg/g. Among the essential amino acids, L-methionine, L-phenylalanine, L-lysine, L-leucine, and L-histidine were found to be the dominant contributors. We also quantified the fatty acids in the phytococktail by using gas chromatography coupled with a flame ionization detector (GC-FID with fatty acid methyl esters (FAMEs derivatization. The analysis revealed the presence of 4 major fatty acids contributing to the total lipid content. Palmitic acid was found to be the rich source of saturated fatty acid (SFA and constituted ∼31% of the total lipid content. Among the unsaturated fatty acids (UFAs, palmitoleic acid (43.47%, oleic acid (20.89%, and linoleic acid (4.31% were prominent. The mineral profiling was carried out by inductively coupled plasma optical emission spectrometer (ICP-OES, and it was found to contain a number of important dietary mineral elements. The harsh climatic conditions, difficult terrain, and logistic constraints at high altitude regions of Indian trans-Himalayan cold desert lead to the scarcity of fresh fruits and vegetables. Therefore, the source of multiple vitamins, essential amino acids, fatty acids, and dietary minerals from the phytococktail would provide great health benefit

  4. Himalayan Vultures in Khodpe, far-west Nepal: is there any threat?

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    Manoj Kumar Joshi

    2015-11-01

    Full Text Available There is evidence that Himalayan Vulture Gyps himalayensis is susceptible to the veterinary drug diclofenac, which is responsible for the decline of other Gyps species across South Asia.  Unlike other Gyps species, there is little quantitative data to assess Himalayan Vultures population.  Based on observation, we analyzed the flock size and breeding success of the Himalayan Vultures on two cliffs of Khodpe in Baitadi District, far-west Nepal.  The mean flock size of Himalayan Vulture was 25.83±6.33.  Overall breeding success was 90.9% based on active nests.  We also conducted a questionnaire survey to assess the perceived threats in the view of local people to vultures and these threats include loss of food, veterinary drug, lack of proper nest sites, and lack of public awareness.  Additionally, 76% of the respondents felt that vultures were decreasing in the area, 94.7% were not aware of the toxicity of diclofenac to vultures, and very few (2% knew about the availability of meloxicam as a safe alternative drug.  The colony we studied is one of the few remaining known breeding populations, which provide baseline information from far-west Nepal, thus we recommend for conservation and continuous monitoring of this species to understand their population change and breeding biology. 

  5. Complexities and Controversies in Himalayan Research: A Call for Collaboration and Rigor for Better Data

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    Surendra P. Singh

    2015-11-01

    Full Text Available The Himalaya range encompasses enormous variation in elevation, precipitation, biodiversity, and patterns of human livelihoods. These mountains modify the regional climate in complex ways; the ecosystem services they provide influence the lives of almost 1 billion people in 8 countries. However, our understanding of these ecosystems remains rudimentary. The 2007 Intergovernmental Panel on Climate Change report that erroneously predicted a date for widespread glacier loss exposed how little was known of Himalayan glaciers. Recent research shows how variably glaciers respond to climate change in different Himalayan regions. Alarmist theories are not new. In the 1980s, the Theory of Himalayan Degradation warned of complete forest loss and devastation of downstream areas, an eventuality that never occurred. More recently, the debate on hydroelectric construction appears driven by passions rather than science. Poor data, hasty conclusions, and bad science plague Himalayan research. Rigorous sampling, involvement of civil society in data collection, and long-term collaborative research involving institutions from across the Himalaya are essential to improve knowledge of this region.

  6. Diversity and feeding strategies of soil microfauna along elevation gradients in Himalayan cold deserts

    Czech Academy of Sciences Publication Activity Database

    Devetter, Miloslav; Háněl, Ladislav; Řeháková, Klára; Doležal, J.

    2017-01-01

    Roč. 12, č. 11 (2017), č. článku e0187646. E-ISSN 1932-6203 R&D Projects: GA MŠk(CZ) LTC17019 Institutional support: RVO:60077344 Keywords : diversity * feeding strategies * soil microfauna * Himalayan cold deserts Subject RIV: EH - Ecology, Behaviour OBOR OECD: Ecology Impact factor: 2.806, year: 2016

  7. Engaging the state: ethnic patronage and cultural politics in the eastern Himalayan borderland

    DEFF Research Database (Denmark)

    Chettri, Mona

    2015-01-01

    In the eastern Himalayan borderland, state-led initiatives have led to the transformation of pre-existing patronage networks and placed ethnic identity at the core of regional politics. Based on ethnographic research in Sikkim, the paper illustrates the prolific rise of affirmative action politic...

  8. Retrieval of snow albedo and grain size using reflectance measurements in Himalayan basin

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    H. S. Negi

    2011-03-01

    Full Text Available In the present paper, spectral reflectance measurements of Himalayan seasonal snow were carried out and analysed to retrieve the snow albedo and effective grain size. The asymptotic radiative transfer (ART theory was applied to retrieve the plane and spherical albedo. The retrieved plane albedo was compared with the measured spectral albedo and a good agreement was observed with ±10% differences. Retrieved integrated albedo was found within ±6% difference with ground observed broadband albedo. The retrieved snow grain sizes using different models based on the ART theory were compared for various snow types and it was observed that the grain size model using two channel method (one in visible and another in NIR region can work well for the Himalayan seasonal snow and it was found consistent with temporal changes in grain size. This method can work very well for clean, dry snow as in the upper Himalaya, but sometimes, due to the low reflectances (<20% using wavelength 1.24 μm, the ART theory cannot be applied, which is common in lower and middle Himalayan old snow. This study is important for monitoring the Himalayan cryosphere using air-borne or space-borne sensors.

  9. Effects of experience and commercialisation on survival in Himalayan mountaineering: retrospective cohort study.

    Science.gov (United States)

    Westhoff, John L; Koepsell, Thomas D; Littell, Christopher T

    2012-06-13

    To determine whether previous Himalayan experience is associated with a decreased risk of climbing death, and whether mountaineers participating in commercial expeditions differ in their risk of death relative to those participating in traditional climbs. Retrospective cohort study. Expeditions in the Nepalese Himalayan peaks, from 1 January 1970 to the spring climbing season in 2010. 23,995 non-porters venturing above base camp on 39,038 climbs, 23,295 on 8000 m peaks. Death. After controlling for use of standard route, peak, age, season, sex, summit success, and year of expedition, increased Himalayan experience was not associated with a change in the odds of death (odds ratio 1.00, 95% confidence interval 0.96 to 1.05, P = 0.904). Participation in a commercial climb was associated with a 37% lower odds of death relative to a traditional venture, although not significantly (0.63, 0.37 to 1.09, P = 0.100). Choice of peak was clearly associated with altered odds of death (omnibus P<0.001); year of expedition was associated with a significant trend toward reduced odds of death (0.98, 0.96 to 0.99, P = 0.011). No net survival benefit is associated with increased Himalayan experience or participation in a traditional (versus commercial) venture. The incremental decrease in risk associated with calendar year suggests that cumulative, collective knowledge and general innovation are more important than individual experience in improving the odds of survival.

  10. Populations of Bactrocera oleae (Diptera: Tephritidae) and Its Parasitoids in Himalayan Asia

    Science.gov (United States)

    For a biological control program against olive fruit fly, Bactrocera oleae Rossi, olives were collected in the Himalayan foothills (China, Nepal, India, and Pakistan) to discover new natural enemies. Wild olives, Olea europaea ssp. cuspidata (Wall ex. G. Don), were sparsely distributed and fly-infes...

  11. Deformation mechanisms in the frontal Lesser Himalayan Duplex in Sikkim Himalaya, India

    Science.gov (United States)

    Matin, Abdul; Mazumdar, Sweety

    2009-08-01

    Understanding deformation mechanisms in Himalayan rocks is a challenging proposition due to the complex nature of the deformed rocks and their genesis. Crustal deformation in the Himalayan thrust belt typically occurs in elastico-frictional (EF) or quasi-plastic (QP) regimes at depths controlled mainly by regional strain-rate and geothermal gradient. However, material property, grain-size and their progressive changes during deformation are also important controlling factors. We present evidence of EF deformation from Gondwana rocks developed during the emplacement of one of the frontal horses (Jorthang horse) in the Lesser Himalayan Duplex (LHD) structure associated with Lesser Himalayan rocks in the footwall of the Ramgarh thrust in the Rangit window near Jorthang in the Sikkim Himalaya. The rocks in the horse exhibit systematic changes in microand meso-structures from an undeformed protolith to cataclasite suggesting that it was emplaced under elastico-frictional conditions. Meso- to micro-scale shear fractures are seen developed in Gondwana sandstone and slate while intercalated fine-grained shale-coal-carbonates are deformed by cataclastic flow suggesting that material property and grain-size have played an important role in the deformation of the Jorthang horse. In contrast, the hanging wall schists and quartzites of the Ramgarh thrust exhibit quasi-plastic deformation structures. This suggests that the Jorthang horse was emplaced under shallower crustal conditions than the antiformally folded Ramgarh thrust sheet even though the Ramgarh sheet presently overlies the Jorthang horse.

  12. Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements

    DEFF Research Database (Denmark)

    Singh, Ajit; Thomsen, Kristina Jørkov; Sinha, Rajiv

    2017-01-01

    . Here we analyse the sedimentary architecture, chronology and provenance of a major palaeochannel associated with many of these settlements. We show that the palaeochannel is a former course of the Sutlej River, the third largest of the present-day Himalayan rivers. Using optically stimulated...

  13. Time-scales of erosion and weathering processes in the Himalayan river system: Element and isotope approach using the U-series; Constantes de temps des processus d'erosion et d'alteration dans le systeme himalayen: approche geochimique elementaire et isotopique par les series de l'uranium

    Energy Technology Data Exchange (ETDEWEB)

    Granet, M

    2007-06-15

    The time-scales of erosion and weathering processes are key parameters which need to be determined to understand the response of the reliefs to external forcing like tectonics, climate and human activities. They were recovered by using U-series nuclides analyzed in sediments and suspended materials carried by the Himalayan rivers of the Ganges and Brahmaputra basins. In the Ganges basin, the time-scales of weathering determined from the study of coarse sediments carried by the Kali Gandaki range from several ky, where the uplift is located, to 350 ky. Such values indicate that the bed-rocks are in situ weathered for a long period before the weathering residual products get transported in the rivers as coarse sediments. At the outlet of the high range, these sediments are carried by the tributaries of the Ganges, the Gandak and Ghaghara, during a transfer period of about 100 ka. The study of the sediments at the outlet of the Brahmaputra tributaries allows to propose time-scales of weathering ranging from 110 to 270 ky. Such long periods confirm that during their transfer in the plains, the sediments are temporarily trapped at several places in the basins. In the Ganges and Brahmaputra rivers, the time-scales of sedimentary transfer are 575 and 160 ky, respectively. These values, which are of the same order as their response times, are much longer than the timescales of the Quaternary climate oscillations. It confirms the buffering action of the asiatic alluvial plains for the high-frequency sediment flux variations in response to external forcing in the chain. The study of suspended materials suggests that their chemical compositions result from the mixing of coarse river sediments with fine particles from various locations in the basin which are affected by vegetation recycling. By contrast to coarse sediments, the time-scales of transfer for the suspended materials are fast, e.g. a few ky, pointing the potential of U-series nuclides to assess particle transport

  14. Thermal evolution of the central Halls Creek Orogen, northern Australia

    International Nuclear Information System (INIS)

    Bodorkos, S.; Cawood, P.A.; Oliver, N.H.S.

    1999-01-01

    The Halls Creek Orogen in northern Australia records the Palaeoproterozoic collision of the Kimberley Craton with the North Australian Craton. Integrated structural, metamorphic and geochronological studies of the Tickalara Metamorphics show that this involved a protracted episode of high temperature, low-pressure metamorphism associated with intense and prolonged mafic and felsic intrusive activity in the interval ca 1850-1820 Ma. Tectonothermal development of the region commenced with an inferred mantle perturbation event, probably at ca 1880 Ma. This resulted in the generation of mafic magmas in the upper mantle or lower crust, while upper crustal extension preceded the rapid deposition of the Tickalara sedimentary protoliths. An older age limit for these rocks is provided by a psammopelitic gneiss from the Tickalara Metamorphics, which yield a 207 Pb/ 206 Pb SHRIMP age of 1867 ± 4 Ma for the youngest detrital zircon suite. Voluminous layered mafic intrusives were emplaced in the middle crust at ca 1860-1855 Ma. prior to the attainment of lower granulite facies peak metamorphic conditions in the middle crust. Locally preserved layer-parallel D 1 foliations that were developed during prograde metamorphism were pervasively overprinted by the dominant regional S 2 gneissosity coincident with peak metamorphism. Overgrowths on zircons record a metamorphic 207 Pb/ 206 Pb age of 1845 ± 4 Ma. The S 2 fabric is folded around tight folds and cut by ductile shear zones associated with D 3 (ca 1830 Ma), and all pre-existing structures are folded around large-scale, open F 4 folds (ca 1820 Ma). Construction of a temperature-time path for the mid-crustal section exposed in the central Halls Creek Orogen, based on detailed SHRIMP zircon data, key field relationships and petrological evidence, suggests the existence of one protracted thermal event (>400-500degC for 25-30 million years) encompassing two deformation phases. Protoliths to the Tickalara Metamorphics were

  15. Some aspects of the role of rift inheritance on Alpine-type orogens

    Science.gov (United States)

    Tugend, Julie; Manatschal, Gianreto; Mohn, Geoffroy; Chevrot, Sébastien

    2017-04-01

    Processes commonly recognized as fundamental for the formation of collisional orogens include oceanic subduction, arc-continent and continent-continent collision. As collisional belts result from the closure of oceanic basins and subsequent inversion of former rifted margins, their formation and evolution may also in theory be closely interlinked with the initial architecture of the former rifted margins. This assumption is indeed more likely to be applicable in the case of Alpine-type orogens, mainly controlled by mechanical processes and mostly devoid of arc-related magmatism. More and more studies from present-day magma-poor rifted margins illustrate the complex evolution of hyperextended domains (i.e. severely thinned continental crust (images across the Pyrenees (PYROPE) and the Alps (CIFALPS) reveal a surprisingly comparable present-day overall crustal and lithospheric structure. Based on the comparison between the two orogens we discuss: (1) the nature and depth of decoupling levels inherited from hyperextension; (2) the implications for restorations and interpretations of orogenic roots (former hyperextended domains vs. lower crust only); and (3) the nature and major role of buttresses in controlling the final stage of collisional processes. Eventually, we discuss the variability of the role of rift-inheritance in building Alpine-type orogens. The Pyrenees seem to represent one extreme, where rift-inheritance is important at different stages of collisional processes. In contrast, in the Alps the role of rift-inheritance is subtler, likely because of its more complex and polyphase compressional deformation history.

  16. An evaporite-bearing accretionary complex in the northern front of the Betic-Rif orogen

    Science.gov (United States)

    Pérez-Valera, Fernando; Sánchez-Gómez, Mario; Pérez-López, Alberto; Pérez-Valera, Luis Alfonso

    2017-06-01

    The Guadalquivir Accretionary Complex forms a largely oblique prism at the northern edge of the Betic-Rif orogen, where Miocene sediments plus allochthonous evaporite-bearing units were accreted during the displacement of the Alborán Domain toward the west. Traditional interpretations end the tectonic structuring of the Betic Cordillera at the present topographic front, beyond which gravitational and/or diapiric processes would predominate. However, this study shows pervasive tectonic deformation in the outer prism with coherent oblique shortening kinematics, which is achieved through an alternation of roughly N-S arcuate thrust systems connected by E-W transfer fault zones. These structures accord well with the geophysical models that propose westward rollback subduction. The main stage of tectonic activity occurred in the early-middle Miocene, but deformation lasted until the Quaternary with the same kinematics. Evaporite rocks played a leading role in the deformation as evidenced by the suite of ductile structures in gypsum distributed throughout the area. S- and L- gypsum tectonites, scaly clay fabrics, and brittle fabrics coexist and consistently indicate westward motion (top to 290°), with subordinate N-S contraction almost perpendicular to the transfer zones. This work reveals ductile tectonic fabrics in gypsum as a valuable tool to elucidate the structure and deformational history of complex tectonic mélanges involving evaporites above the décollement level of accretionary wedges.

  17. Hydrological and sedimentation implications of landscape changes in a Himalayan catchment due to bioenergy cropping

    Science.gov (United States)

    Remesan, Renji; Holman, Ian; Janes, Victoria

    2015-04-01

    There is a global effort to focus on the development of bioenergy and energy cropping, due to the generally increasing demand for crude oil, high oil price volatility and climate change mitigation challenges. Second generation energy cropping is expected to increase greatly in India as the Government of India has recently approved a national policy of 20 % biofuel blending by 2017; furthermore, the country's biomass based power generation potential is estimated as around ~24GW and large investments are expected in coming years to increase installed capacity. In this study, we have modelled the environmental influences (e.g.: hydrology and sediment) of scenarios of increased biodiesel cropping (Jatropha curcas) using the Soil and Water Assessment Tool (SWAT) in a northern Indian river basin. SWAT has been applied to the River Beas basin, using daily Tropical Rainfall Measuring Mission (TRMM) precipitation and NCEP Climate Forecast System Reanalysis (CFSR) meteorological data to simulate the river regime and crop yields. We have applied Sequential Uncertainty Fitting Ver. 2 (SUFI-2) to quantify the parameter uncertainty of the stream flow modelling. The model evaluation statistics for daily river flows at the Jwalamukhi and Pong gauges show good agreement with measured flows (Nash Sutcliffe efficiency of 0.70 and PBIAS of 7.54 %). The study has applied two land use change scenarios of (1) increased bioenergy cropping in marginal (grazing) lands in the lower and middle regions of catchment (2) increased bioenergy cropping in low yielding areas of row crops in the lower and middle regions of the catchment. The presentation will describe the improved understanding of the hydrological, erosion and sediment delivery and food production impacts arising from the introduction of a new cropping variety to a marginal area; and illustrate the potential prospects of bioenergy production in Himalayan valleys.

  18. Porphyry copper assessment of the Central Asian Orogenic Belt and eastern Tethysides: China, Mongolia, Russia, Pakistan, Kazakhstan, Tajikistan, and India: Chapter X in Global mineral resource assessment

    Science.gov (United States)

    Mihalasky, Mark J.; Ludington, Stephen; Hammarstrom, Jane M.; Alexeiev, Dmitriy V.; Frost, Thomas P.; Light, Thomas D.; Robinson, Gilpin R.; Briggs, Deborah A.; Wallis, John C.; Miller, Robert J.; Bookstrom, Arthur A.; Panteleyev, Andre; Chitalin, Andre; Seltmann, Reimar; Guangsheng, Yan; Changyun, Lian; Jingwen, Mao; Jinyi, Li; Keyan, Xiao; Ruizhao, Qiu; Jianbao, Shao; Gangyi, Shai; Yuliang, Du

    2015-01-01

    The U.S. Geological Survey collaborated with international colleagues to assess undiscovered resources in porphyry copper deposits in the Central Asian Orogenic Belt and eastern Tethysides. These areas host 20 known porphyry copper deposits, including the world class Oyu Tolgoi deposit in Mongolia that was discovered in the late 1990s. The study area covers major parts of the world’s largest orogenic systems. The Central Asian Orogenic Belt is a collage of amalgamated Precambrian through Mesozoic terranes that extends from the Ural Mountains in the west nearly to the Pacific Coast of Asia in the east and records the evolution and final closure of the Paleo-Asian Ocean in Permian time. The eastern Tethysides, the orogenic belt to the south of the Central Asian Orogenic Belt, records the evolution of another ancient ocean system, the Tethys Ocean. The evolution of these orogenic belts involved magmatism associated with a variety of geologic settings appropriate for formation of porphyry copper deposits, including subduction-related island arcs, continental arcs, and collisional and postconvergent settings. The original settings are difficult to trace because the arcs have been complexly deformed and dismembered by younger tectonic events. Twelve mineral resource assessment tracts were delineated to be permissive for the occurrence of porphyry copper deposits based on mapped and inferred subsurface distributions of igneous rocks of specific age ranges and compositions. These include (1) nine Paleozoic tracts in the Central Asian Orogenic Belt, which range in area from about 60,000 to 800,000 square kilometers (km2); (2) a complex area of about 400,000 km2 on the northern margin of the Tethysides, the Qinling-Dabie tract, which spans central China and areas to the west, encompassing Paleozoic through Triassic igneous rocks that formed in diverse settings; and (3) assemblages of late Paleozoic and Mesozoic rocks that define two other tracts in the Tethysides, the 100

  19. The threatening but unpredictable Sarcoptes scabiei: first deadly outbreak in the Himalayan lynx, Lynx lynx isabellinus, from Pakistan.

    Science.gov (United States)

    Hameed, Khalid; Angelone-Alasaad, Samer; Din, Jaffar Ud; Nawaz, Muhammad Ali; Rossi, Luca

    2016-07-19

    Although neglected, the mite Sarcoptes scabiei is an unpredictable emerging parasite, threatening human and animal health globally. In this paper we report the first fatal outbreak of sarcoptic mange in the endangered Himalayan lynx (Lynx lynx isabellinus) from Pakistan. A 10-year-old male Himalayan lynx was found in a miserable condition with severe crusted lesions in Chitral District, and immediately died. Post-mortem examination determined high S. scabiei density (1309 mites/cm(2) skin). It is most probably a genuine emergence, resulting from a new incidence due to the host-taxon derived or prey-to-predator cross-infestation hypotheses, and less probable to be apparent emergence resulting from increased infection in the Himalayan lynx population. This is an alarming situation for the conservation of this already threatened population, which demands surveillance for early detection and eventually rescue and treatment of the affected Himalayan lynx.

  20. Hissar-Alai and the Pamirs: Junction and Position in the System of Mobile Belts of Central Asia

    Science.gov (United States)

    Leonov, M. G.; Rybin, A. K.; Batalev, V. Yu.; Matyukov, V. E.; Shchelochkov, G. G.

    2018-01-01

    The position of the Pamirs and the Hissar-Alai mountainous system in the structure of Central Asia and features of their junction are considered. It is shown that their outer contours and tectonic infrastructure are significantly distinct in the planar pattern: latitudinally linear and arched for the Hissar-Alai and the Pamirs, respectively. These structures logically match those of the Central Asian and Alpine-Himalayan belts, respectively. The Pamir orogen is a relatively autonomous structural element of the crust, which is located discordantly relative to the country lithospheric blocks. Most of the Pamirs (at least, the Northern and Central) probably form a giant allochthon on the ancient basement of the Tarim and Afghan-Tajik blocks. The junction zone of these two "hard" crustal segments is reflected in the transverse Transpamir threshold, which is expressed in the relief, deep structure, and seismicity. The specific geological structure of the junction zone of the Pamirs and Hissar-Alai (systems of the Tarim, Alai, and Afghan-Tajik troughs) is shown. It suggested that this zone is a damper, which significantly neutralizes the dynamic influence of the Pamir and the southernmost elements of the Pamir-Punjab syntax on Hissar-Alai structures.

  1. Earthquake hazard assessment in the Zagros Orogenic Belt of Iran using a fuzzy rule-based model

    Science.gov (United States)

    Farahi Ghasre Aboonasr, Sedigheh; Zamani, Ahmad; Razavipour, Fatemeh; Boostani, Reza

    2017-08-01

    Producing accurate seismic hazard map and predicting hazardous areas is necessary for risk mitigation strategies. In this paper, a fuzzy logic inference system is utilized to estimate the earthquake potential and seismic zoning of Zagros Orogenic Belt. In addition to the interpretability, fuzzy predictors can capture both nonlinearity and chaotic behavior of data, where the number of data is limited. In this paper, earthquake pattern in the Zagros has been assessed for the intervals of 10 and 50 years using fuzzy rule-based model. The Molchan statistical procedure has been used to show that our forecasting model is reliable. The earthquake hazard maps for this area reveal some remarkable features that cannot be observed on the conventional maps. Regarding our achievements, some areas in the southern (Bandar Abbas), southwestern (Bandar Kangan) and western (Kermanshah) parts of Iran display high earthquake severity even though they are geographically far apart.

  2. The crustal structures from Wuyi-Yunkai orogen to Taiwan orogen: the onshore-offshore wide-angle seismic experiment of TAIGER and ATSEE projects

    Science.gov (United States)

    Kuochen, H.; Kuo, N. Y. W.; Wang, C. Y.; Jin, X.; Cai, H. T.; Lin, J. Y.; Wu, F. T.; Yen, H. Y.; Huang, B. S.; Liang, W. T.; Okaya, D. A.; Brown, L. D.

    2015-12-01

    The crustal structure is key information for understanding the tectonic framework and geological evolution in the southeastern China and its adjacent area. In this study, we integrated the data sets from the TAIGER and ATSEE projects to resolve onshore-offshore deep crustal seismic profiles from the Wuyi-Yunkai orogen to the Taiwan orogen in southeastern China. Totally, there are three seismic profiles resolved and the longest profile is 850 km. Unlike 2D and 3D first arrival travel-time tomography from previous studies, we used both refracted and reflected phases (Pg, Pn, PcP, and PmP) to model the crustal structures and the crustal reflectors. 40 shots, 2 earthquakes, and about 1,950 stations were used and 15,319 arrivals were picked among three transects. As a result, the complex crustal evolution since Paleozoic era are shown, which involved the closed Paleozoic rifted basin in central Fujian, the Cenozoic extension due to South China sea opening beneath the coastline of southern Fujian, and the on-going collision of the Taiwan orogen.

  3. Himalayan sedimentary pulses recorded by silicate detritus within a ferromanganese crust from the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.; Galy, A.; Sukumaran, N.P.; Parthiban, G.; Volvaiker, A.Y.

    of the sediment production by the erosion of an active orogenic range and its distribution over a vast area. Additionally, close superimposition of the Early Miocene detritus pulse in the SS663-Crust on the riverine Sr isotopic positive excursion suggests...

  4. Prevention of neonatal hypothermia in Himalayan villages. Role of the domiciliary caretaker.

    Science.gov (United States)

    Iyengar, S D; Bhakoo, O N

    1991-07-01

    Given severe winters at high altitudes, prevention of environmental neonatal hypothermia is of particular importance in Himalayan villages. This is a retrospective study of traditional concepts and practices for the prevention of neonatal hypothermia. 202 babies were studied from a population of 16,425 in three districts of a Himalayan state of North India. The community was found to believe that newborns, especially if underweight are vulnerable to cold induced disease for the first few months of life. A warm heated room for delivery and lying-in, early rooming in, oil massage and layers of warm clothing are traditional means for thermo-regulation as practiced by mothers, birth attendants and relatives. The ritual practice of bathing immediately after birth and then upto three times each day even in winter is not perceived by them to provoke hypothermia. For upto one month postpartum mothers are believed to be at risk for cold induced disease.

  5. Continental Collision Structures and Post-Orogenic Geological History of the Kangerlussuaq Area in the Southern Part of the Nagssugtoqidian Orogen, Central West Greenland

    Directory of Open Access Journals (Sweden)

    Jon Engström

    2014-12-01

    Full Text Available Deep-seated continental collision sutures, formed at a depth of more than 20 km, are exposed near Kangerlussuaq, close to the Greenland ice cap, on the southern margin of the Nagssugtoqidian orogen in Central West Greenland, thus offering a rare opportunity to study the tectonic deformation style of such an orogen. This paper adds new information on the tectonic history of the southern flank of the Nagssugtoqidian orogen. It focuses on (1 the results of a detailed structural investigation of lineament zones revealed from remote sensing of geophysical and topographic data and aerial photo interpretation, (2 detailed geological mapping at key locations and (3 a tectonic structural model describing the geological development of the area. The area has undergone several episodes of deformation, which have been compiled into an event succession that recognizes eight tectonic events overprinting each other: Two stages of folding (F1 and F2 have been identified along with one major episode of intrusion of the Kangâmiut mafic dyke swarm (2.05 Ga into the Archaean continent. These dyke intrusions are very important, since by examining the style of deformation for these intrusions it is possible to define the transition from the North Atlantic Craton in the south to the mobile belts in the Nagssugtoqidian orogen in the north. Five different types of pronounced lineaments and one less pronounced lineament post-dating the Kangâmiut dykes extending from ductile deformation shearing events to brittle deformation with extensive faulting. These lineaments cover both the collisional and post-collisional tectonic history of the area. The study focused on two types of lineaments: one semi-ductile type trending E–W with a dextral sense of shear and a second, a pronounced lineament outlining the Kangerlussuaq–Russell thrust fault. These two features are interpreted to be related to the Nagssugtoqidian orogeny, while the latter lineaments have a more brittle

  6. Post-collisional magmatism in the central East African Orogen: The Maevarano Suite of north Madagascar

    Science.gov (United States)

    Goodenough, K.M.; Thomas, Ronald J.; De Waele, B.; Key, R.M.; Schofield, D.I.; Bauer, W.; Tucker, R.D.; Rafahatelo, J.-M.; Rabarimanana, M.; Ralison, A.V.; Randriamananjara, T.

    2010-01-01

    Late tectonic, post-collisional granite suites are a feature of many parts of the Late Neoproterozoic to Cambrian East African Orogen (EAO), where they are generally attributed to late extensional collapse of the orogen, accompanied by high heat flow and asthenospheric uprise. The Maevarano Suite comprises voluminous plutons which were emplaced in some of the tectonostratigraphic terranes of northern Madagascar, in the central part of the EAO, following collision and assembly during a major orogeny at ca. 550 Ma. The suite comprises three main magmatic phases: a minor early phase of foliated gabbros, quartz diorites, and granodiorites; a main phase of large batholiths of porphyritic granitoids and charnockites; and a late phase of small-scale plutons and sheets of monzonite, syenite, leucogranite and microgranite. The main phase intrusions tend to be massive, but with variably foliated margins. New U-Pb SHRIMP zircon data show that the whole suite was emplaced between ca. 537 and 522 Ma. Geochemically, all the rocks of the suite are enriched in the LILE, especially K, and the LREE, but are relatively depleted in Nb, Ta and the HREE. These characteristics are typical of post-collisional granitoids in the EAO and many other orogenic belts. It is proposed that the Maevarano Suite magmas were derived by melting of sub-continental lithospheric mantle that had been enriched in the LILE during earlier subduction events. The melting occurred during lithospheric delamination, which was associated with extensional collapse of the East African Orogen. ?? 2009 Natural Environment Research Council.

  7. Magnetic fabric transposition in folded granite sills in Variscan orogenic wedge

    Czech Academy of Sciences Publication Activity Database

    Závada, Prokop; Calassou, T.; Schulmann, K.; Hrouda, F.; Štípská, P.; Hasalová, Pavlína; Míková, J.; Magna, T.; Mixa, P.

    2017-01-01

    Roč. 94, January (2017), s. 166-183 ISSN 0191-8141 R&D Projects: GA ČR GA14-15632S Institutional support: RVO:67985530 Keywords : orogenic sill * AMS fabric * folding Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 2.408, year: 2016

  8. Variability of orogenic magmatism during Mediterranean-style continental collisions : A numerical modelling approach

    NARCIS (Netherlands)

    Andrić, N.; Vogt, K.; Matenco, L.; Cvetković, V.; Cloetingh, S.; Gerya, T.

    The relationship between magma generation and the tectonic evolution of orogens during subduction and subsequent collision requires self-consistent numerical modelling approaches predicting volumes and compositions of the produced magmatic rocks. Here, we use a 2D magmatic-thermomechanical numerical

  9. Retrieval of snow albedo and grain size using reflectance measurements in Himalayan basin

    OpenAIRE

    H. S. Negi; A. Kokhanovsky

    2010-01-01

    In the present paper spectral reflectance measurements of Himalayan seasonal snow were carried out and analysed to retrieve the snow albedo and effective grain size. The asymptotic radiative transfer (ART) theory was applied to retrieve the plane and spherical albedo. The retrieved plane albedo was compared with the measured spectral albedo and a good agreement was observed with ±10% measured error accuracy. Retrieved integrated albedo was found within ±6% difference with ground observed broa...

  10. Lectotypification of names of Himalayan Brassicaceae taxa currently placed in the genus Cardamine

    Directory of Open Access Journals (Sweden)

    Karol Marhold

    2015-05-01

    Full Text Available Lectotypes of twenty-eight names of taxa currently recognized or synonymized in Cardamine are designated as part of the work on the account of the genus for the Pan-Himalayan Flora. Among them, the previous first-step lectotypification of the name C. calthifolia is finalized. In cases when specimen images are available online, stable identifiers for specimens, other permanent links, or links via JSTOR Global Plants are provided.

  11. Lectotypification of names of Himalayan Brassicaceae taxa currently placed in the genus Cardamine.

    Science.gov (United States)

    Marhold, Karol; Kempa, Matúš; Al-Shehbaz, Ihsan A

    2015-01-01

    Lectotypes of twenty-eight names of taxa currently recognized or synonymized in Cardamine are designated as part of the work on the account of the genus for the Pan-Himalayan Flora. Among them, the previous first-step lectotypification of the name Cardaminecalthifolia is finalized. In cases when specimen images are available online, stable identifiers for specimens, other permanent links, or links via JSTOR Global Plants are provided.

  12. Chemical characterization of meltwater from East Rathong glacier vis-a-vis Western Himalayan glaciers

    Digital Repository Service at National Institute of Oceanography (India)

    Sharma, B.M.; Tayal, S.; Chakraborty, P.; Bharat, G.K.

    also be significant regulator of ionic enrichment and variability of meltwater stream in comparison to western Himalaya streams. Chemical Characterization of Meltwater from East Rathong Glacier … 188 B.M. Sharma et al. Ta bl e 1 Ch em ic al c ha... and Gomukh. In: Proceeding of national symposium on Himalayan geology, Calcutta, Geological Society of India, vol 15. Miscellaneous Publication, pp 1–8 Brown GH, Sharp MJ, Tranter M (1996) Subglacial chemical erosion: seasonal variations in sol- ute...

  13. Effects of experience and commercialisation on survival in Himalayan mountaineering: retrospective cohort study

    Science.gov (United States)

    Koepsell, Thomas D; Littell, Christopher T

    2012-01-01

    Objectives To determine whether previous Himalayan experience is associated with a decreased risk of climbing death, and whether mountaineers participating in commercial expeditions differ in their risk of death relative to those participating in traditional climbs. Design Retrospective cohort study. Setting Expeditions in the Nepalese Himalayan peaks, from 1 January 1970 to the spring climbing season in 2010. Participants 23 995 non-porters venturing above base camp on 39 038 climbs, 23 295 on 8000 m peaks. Outcome Death. Results After controlling for use of standard route, peak, age, season, sex, summit success, and year of expedition, increased Himalayan experience was not associated with a change in the odds of death (odds ratio 1.00, 95% confidence interval 0.96 to 1.05, P=0.904). Participation in a commercial climb was associated with a 37% lower odds of death relative to a traditional venture, although not significantly (0.63, 0.37 to 1.09, P=0.100). Choice of peak was clearly associated with altered odds of death (omnibus P<0.001); year of expedition was associated with a significant trend toward reduced odds of death (0.98, 0.96 to 0.99, P=0.011). Conclusions No net survival benefit is associated with increased Himalayan experience or participation in a traditional (versus commercial) venture. The incremental decrease in risk associated with calendar year suggests that cumulative, collective knowledge and general innovation are more important than individual experience in improving the odds of survival. PMID:22695902

  14. Wave like signatures in aerosol optical depth and associated radiative impacts over the central Himalayan region

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, K. K.; Phanikumar, D. V.; Kumar, K.  Niranjan; Reddy, Kishore; Kotamarthi, V. R.; Newsom, Rob K.; Ouarda, Taha B. M. J.

    2015-10-01

    In this study, we present a case study on 16 October 2011 to show the first observational evidence of the influence of short period gravity waves in aerosol transport during daytime over the central Himalayan region. The Doppler lidar data has been utilized to address the daytime boundary layer evolution and related aerosol dynamics over the site. Mixing layer height is estimated by wavelet covariance transform method and found to be ~ 0.7 km, AGL. Aerosol optical depth observations during daytime revealed an asymmetry showing clear enhancement during afternoon hours as compared to forenoon. Interestingly, Fourier and wavelet analysis of vertical velocity and attenuated backscatter showed similar 50-90 min short period gravity wave signatures during afternoon hours. Moreover, our observations showed that gravity waves are dominant within the boundary layer implying that the daytime boundary layer dynamics is playing a vital role in transporting the aerosols from surface to the top of the boundary layer. Similar modulations are also evident in surface parameters like temperature, relative humidity and wind speed indicating these waves are associated with the dynamical aspects over Himalayan region. Finally, time evolution of range-23 height indicator snapshots during daytime showed strong upward velocities especially during afternoon hours implying that convective processes through short period gravity waves plays a significant role in transporting aerosols from the nearby valley region to boundary layer top over the site. These observations also establish the importance of wave induced daytime convective boundary layer dynamics in the lower Himalayan region.

  15. Probabilistic Seismic Hazard Assessment for Himalayan-Tibetan Region from Historical and Instrumental Earthquake Catalogs

    Science.gov (United States)

    Rahman, M. Moklesur; Bai, Ling; Khan, Nangyal Ghani; Li, Guohui

    2018-02-01

    The Himalayan-Tibetan region has a long history of devastating earthquakes with wide-spread casualties and socio-economic damages. Here, we conduct the probabilistic seismic hazard analysis by incorporating the incomplete historical earthquake records along with the instrumental earthquake catalogs for the Himalayan-Tibetan region. Historical earthquake records back to more than 1000 years ago and an updated, homogenized and declustered instrumental earthquake catalog since 1906 are utilized. The essential seismicity parameters, namely, the mean seismicity rate γ, the Gutenberg-Richter b value, and the maximum expected magnitude M max are estimated using the maximum likelihood algorithm assuming the incompleteness of the catalog. To compute the hazard value, three seismogenic source models (smoothed gridded, linear, and areal sources) and two sets of ground motion prediction equations are combined by means of a logic tree on accounting the epistemic uncertainties. The peak ground acceleration (PGA) and spectral acceleration (SA) at 0.2 and 1.0 s are predicted for 2 and 10% probabilities of exceedance over 50 years assuming bedrock condition. The resulting PGA and SA maps show a significant spatio-temporal variation in the hazard values. In general, hazard value is found to be much higher than the previous studies for regions, where great earthquakes have actually occurred. The use of the historical and instrumental earthquake catalogs in combination of multiple seismogenic source models provides better seismic hazard constraints for the Himalayan-Tibetan region.

  16. Reconnaissance Rb-Sr dates for the Himalayan Central Gneiss, Northwest India

    International Nuclear Information System (INIS)

    Powell, C. McA.; Crawford, A.R.; Armstrong, R.L.; Wynne-Edwards, H.R.; Prakash, R.

    1979-01-01

    Rb-Sr analysis of whole-rock samples and biotite and biotite - or muscovite - whole rock pairs suggests that the Himalayan Central Gneiss in the crystalline nappes of the Lesser Himalaya and the root zone in the High Himalaya was formed during Oligocene to mid-Miocene times by deformation and metamorphism of older rocks, including Precambrian. Four whole-rock samples from the Almora-Askot thrust sheets define an isochron of 1620 +- 90 Ma with a high initial 87 Sr/ 86 Sr ratio of 0.749 +- 0.007; other single whole-rock samples give dates in the range 268 to 1065 Ma, assuming an initial 87 Sr/ 86 Sr ratio of 0.704. These dates are considered to represent either depositional or early instructive/deformational events. Three biotite-whole rock pairs from the root zone of the Himalayan Central Gneiss in Lahaul give aqes of 16 to 19 Ma and two muscovite-whole rock pairs give similar mid-Cenozoic ages (12 and 26 Ma); two muscovite-whole rock pairs give Paleozoic ages, which suggests incomplete resetting of the muscovite by the Cenozoic metamorphism. The pattern of ages is similar to recent results from adjacent areas, and consistent with models of Himalayan tectonics involving formation of the Central Gneiss from older Indian crust during the mid-Cenozoic. (auth.)

  17. Multivariate statistical techniques for the evaluation of surface water quality of the Himalayan foothills streams, Pakistan

    Science.gov (United States)

    Malik, Riffat Naseem; Hashmi, Muhammad Zaffar

    2017-10-01

    Himalayan foothills streams, Pakistan play an important role in living water supply and irrigation of farmlands; thus, the water quality is closely related to public health. Multivariate techniques were applied to check spatial and seasonal trends, and metals contamination sources of the Himalayan foothills streams, Pakistan. Grab surface water samples were collected from different sites (5-15 cm water depth) in pre-washed polyethylene containers. Fast Sequential Atomic Absorption Spectrophotometer (Varian FSAA-240) was used to measure the metals concentration. Concentrations of Ni, Cu, and Mn were high in pre-monsoon season than the post-monsoon season. Cluster analysis identified impaired, moderately impaired and least impaired clusters based on water parameters. Discriminant function analysis indicated spatial variability in water was due to temperature, electrical conductivity, nitrates, iron and lead whereas seasonal variations were correlated with 16 physicochemical parameters. Factor analysis identified municipal and poultry waste, automobile activities, surface runoff, and soil weathering as major sources of contamination. Levels of Mn, Cr, Fe, Pb, Cd, Zn and alkalinity were above the WHO and USEPA standards for surface water. The results of present study will help to higher authorities for the management of the Himalayan foothills streams.

  18. SVM-based base-metal prospectivity modeling of the Aravalli Orogen, Northwestern India

    Science.gov (United States)

    Porwal, Alok; Yu, Le; Gessner, Klaus

    2010-05-01

    The Proterozoic Aravalli orogen in the state of Rajasthan, northwestern India, constitutes the most important metallogenic province for base-metal deposits in India and hosts the entire economically viable lead-zinc resource-base of the country. The orogen evolved through near-orderly Wilson cycles of repeated extensional and compressional tectonics resulting in sequential opening and closing of intracratonic rifts and amalgamation of crustal domains during a circa 1.0-Ga geological history from 2.2 Ga to 1.0 Ga. This study develops a conceptual tectonostratigraphic model of the orogen based on a synthesis of the available geological, geophysical and geochronological data followed by deep-seismic-reflectivity-constrained 2-D forward gravity modeling, and links it to the Proterozoic base-metal metallogeny in the orogen in order to identify key geological controls on the base-metal mineralization. These controls are translated into exploration criteria for base-metal deposits, validated using empirical spatial analysis, and used to derive input spatial variables for model-based base-metal prospectivity mapping of the orogen. A support vector machine (SVM) algorithm augmented by incorporating a feature selection procedure is used in a GIS environment to implement the prospectivity mapping. A comparison of the SVM-derived prospectivity map with the ones derived using other established models such as neural-networks, logistic regression, and Bayesian weights-of-evidence indicates that the SVM outperforms other models, which is attributed to the capability of the SVM to return robust classification based on small training datasets.

  19. Crustal melting beneath orogenic plateaus: Insights from 3-D thermo-mechanical modeling

    Science.gov (United States)

    Chen, L.; Song, X.; Gerya, T.; Xu, T.; Chen, Y.

    2017-12-01

    Mid-crustal melting is widely documented within orogenic plateaus. However, the mechanism for its generation and its role in the evolution of orogenic plateaus remain poorly understood. Here we use 3-D thermo-mechanical models to investigate the physical controls for mid-crustal melting beneath orogenic plateaus and its consequences in plateau evolution. The results demonstrate that: 1) lateral lithospheric strength contrast between two colliding continents facilitates an episodic growth of orogenic plateau and mid-crustal melting; 2) slower convergence favors larger amount of melt; and 3) radioactive heating during crustal thickening plays the primary role in generating mid-crustal melting. Shear heating also plays a positive role in mid-crustal melting, but its role is secondary to radioactive heating. During collisional orogeny, it is the combination of crustal self-heating (radioactive/shear heating) and the contrast in radiogenic element concentration between the upper and lower crust that makes the base of the thickened upper crust favorable for in situ crustal melting at the mid-crust. We also demonstrate that the occurrence of the mid-crustal melting layer postdates the establishment of a broad orogenic plateau, and causes mechanical decoupling between the overlying upper crust and underlying lower crust by dramatically reducing mid-crustal strength. At the later stage, the melt-weakened layer flows outward in a localized channel and manifest its potential role in the marginal dominance of mid-crustal partial melting. Our models provide a self-consistent explanation for the low S-wave velocity zones widespread in the Tibetan middle crust, which are most prominent in the periphery of Tibet.

  20. Post-orogenic exhumation history of a Variscan mid-crustal basement in Galicia (NW Spain)

    Science.gov (United States)

    Grobe, Rene; Alvarez-Marrón, Joaquina; Glasmacher, Ulrich A.; Stuart, Finlay; Castañeda-Zarauz, A.

    2010-05-01

    The present study aims to quantify the complex post-orogenic history of cooling, denudation, and long-term landscape evolution of a mid-crustal section of Variscan basement in Galicia (NW Spain). We use apatite fission-track and apatite (U-Th)/He thermochronological techniques combined with time-temperature (t-T) path modelling using the software code HeFTy©. The topography is characterized by an extensive, low relief area at ~500 m elevation in central Galicia, and a WNW-ESE ridge that reaches up to 1000 m to the North. The area experienced two major tectonic events since the end of the Variscan orogeny in the Late Palaeozoic: 1) continental break-up and Mesozoic rifting leading to the opening of the Atlantic Ocean and the Bay of Biscay, and 2) limited convergence between Iberia and Eurasia since Middle Eocene times. Apatite fission-track ages range from 68.1 ± 5.0 Ma to 174.5 ± 7.7 Ma and apatite (U-Th)/He ages range from 73.6 ± 5.4 to 147.1 ± 16.6 Ma. Age-elevation plots and t-T path modelling suggest a tectonothermal evolution with faster exhumation associated to faulting during Mesozoic rifting. In particular, two major fault systems trending WNW-ESE and NNE-SSW, the As Pontes and the Lugo faults respectively separate areas with the fastest exhumation around 115 Ma from areas with overall slow exhumation since 200-150 Ma. A landscape of subdued topography in central Galicia was acquired prior to Eocene convergence. The higher elevation areas along the northern ridge formed since Middle Eocene times due to fault reactivation and minor exhumation occurred along the fault escarpment.

  1. Paleoseismological evidence of surface faulting along the northeastern Himalayan front, India: Timing, size, and spatial extent of great earthquakes

    Science.gov (United States)

    Kumar, Senthil; Wesnousky, Steven G.; Jayangondaperumal, R.; Nakata, T.; Kumahara, Y.; Singh, Vimal

    2010-12-01

    The ˜2500 km long Himalayan arc has experienced three large to great earthquakes of Mw 7.8 to 8.4 during the past century, but none produced surface rupture. Paleoseismic studies have been conducted during the last decade to begin understanding the timing, size, rupture extent, return period, and mechanics of the faulting associated with the occurrence of large surface rupturing earthquakes along the ˜2500 km long Himalayan Frontal Thrust (HFT) system of India and Nepal. The previous studies have been limited to about nine sites along the western two-thirds of the HFT extending through northwest India and along the southern border of Nepal. We present here the results of paleoseismic investigations at three additional sites further to the northeast along the HFT within the Indian states of West Bengal and Assam. The three sites reside between the meizoseismal areas of the 1934 Bihar-Nepal and 1950 Assam earthquakes. The two westernmost of the sites, near the village of Chalsa and near the Nameri Tiger Preserve, show that offsets during the last surface rupture event were at minimum of about 14 m and 12 m, respectively. Limits on the ages of surface rupture at Chalsa (site A) and Nameri (site B), though broad, allow the possibility that the two sites record the same great historical rupture reported in Nepal around A.D. 1100. The correlation between the two sites is supported by the observation that the large displacements as recorded at Chalsa and Nameri would most likely be associated with rupture lengths of hundreds of kilometers or more and are on the same order as reported for a surface rupture earthquake reported in Nepal around A.D. 1100. Assuming the offsets observed at Chalsa and Nameri occurred synchronously with reported offsets in Nepal, the rupture length of the event would approach 700 to 800 km. The easternmost site is located within Harmutty Tea Estate (site C) at the edges of the 1950 Assam earthquake meizoseismal area. Here the most recent event

  2. Management of water resources and low flow estimation for the Himalayan basins of Nepal

    Science.gov (United States)

    Chalise, Suresh R.; Kansakar, Sunil R.; Rees, Gwyn; Croker, Karen; Zaidman, Maxine

    2003-11-01

    Reliable estimates of low flow are extremely important for the monsoonal mountainous areas of the Hindu Kush-Himalayan (HKH) region as people in this region are facing growing problems of water during dry periods in terms of both quality and quantity. Furthermore, increasing evidence of decrease in snow cover and retreat of glaciers due to global warming have been reported from various parts of the HKH, which has serious implications for low flow in the region. However, reliable methods for low flow are difficult to find and lack of hydrometeorological data have inhibited the development of such methods. This has posed serious problems for sustainable management of water resources systems in the region in view of the difficulties in low flow. This paper also discusses a method for low flow estimation in the mountainous regions of Nepal, which shares with other neighbouring areas the complexity in the nature of the terrain and climate, inadequate hydro-meteorological network and insufficient long-term reliable data on hydrometeorology. The method discussed is based on a method developed in the UK, for estimating the hydrological regime at ungauged sites. Regionalization of the flow has been developed applying multi-variate regression analysis of long-term hydro-meteorological data and catchment characteristics. A number of standardised flow duration type curves have been determined, and regression models of the flows and the topographical and geological characteristics of the catchments were established. The mean flow was estimated using the water balance principle where the long-term mean annual runoff is the difference between long-term average annual precipitation and long-term actual evapotranspiration. Regionalization has been carried out by developing grids of hydrological response. The grids allow the flow regime to be estimated at any point on any stream in the mountainous region of the country. This is the first regional method of this kind to be developed

  3. Himalayan Bioresource Rhodiola imbricata as a promising radioprotector for nuclear and radiological emergencies

    Directory of Open Access Journals (Sweden)

    Raman Chawla

    2010-01-01

    Full Text Available In recent years, a lot of interest has been generated world over in the area of radioprotection for first responders going to work in the hot zones at the incident site. A large number of molecular drugs have been screened for radioprotective efficacy, but with little success. The requirement of differential radioprotection necessitates a holistic approach, which can be realized using herbs in view of their multifaceted mode of action. Our earlier studies showed the radioprotective potential of Rhodiola imbricata, a Himalayan high-altitude plant. In this study, our focus has been to compare the pro-oxidant/antioxidant activities of three fractionated extracts of R. imbricata. The aqueous fraction exhibited significant (P < 0.05 pro-oxidant activity (up to 100 mg/ml under metal ion-induced stress ± flux [transition metal (Fe/Cu ± 0.25 kGy]. A decrease in the dielectric constant of the solvent system utilized for extraction, exhibited a significant (P < 0.05 negative correlation (−0.955 with mean protection potential of lipid against radiation flux. Such an effect was visualized as a significant shift from pro-oxidant to antioxidant activity in methanolic fraction (dielectric constant = 33, as compared to aqueous fraction (dielectric constant = 80. Aqueous fraction is predominantly pro-oxidant at maximal concentrations, indicating its anticancer potential. The presence of transition metals modulates such a biphasic activity differentially in various fractions, i.e., the conversion of Fe(III or Cu(II to Fe(II or Cu(I, respectively, due to the presence of certain bioactive constituents (electron donation at lower concentrations, favors pro-oxidant activity. On the other hand, certain other active constituents involved in metal ion chelation contributed to the overall antioxidant activity. The methanolic fraction exhibited significant antioxidant activity up to 250 mg/ml, which contributed to its radioprotective efficacy. The aquo

  4. Anti-oxidant and anti-microbial properties of some ethno-therapeutically important medicinal plants of Indian Himalayan Region.

    Science.gov (United States)

    Rawat, Sandeep; Jugran, Arun K; Bahukhandi, Amit; Bahuguna, Asutosh; Bhatt, Indra D; Rawal, Ranbeer S; Dhar, Uppeandra

    2016-12-01

    Therapeutic potential of medicinal plants as a source of noble natural anti-oxidants and anti-microbial agents has been well recognised all across the globe. In this study, phenolic compounds, in vitro anti-oxidant activity and anti-microbial properties have been investigated in five Himalayan medicinal plants, (e.g., Acorus calamus, Habenaria intermedia, Hedychium spicatum, Roscoea procera and Valeriana jatamansi) in different solvent systems. R. procera exhibited significantly (p anti-oxidant activity. Also, R. procera and H. spicatum were found rich in gallic acid; V. jatamansi in catechin, hydroxylbenzoic acid and caffeic acid and H. intermedia in hydroxyl benzoic acid. Solvent systems showed species specific response for extraction of total flavonoids and anti-oxidant activity. All the extracts were found effective against different bacterial and fungal strains in a dose dependent manner and maximum antimicrobial activity was found in R. procera as compared to other species. All the plant extracts showed greater activity against bacterial strains as compared to fungal strains. The results of this study suggest that extract of these species can be used as natural anti-oxidant to reduce free radical mediated disorders and as natural alternative for food preservation.

  5. Subduction and Slab Advance at Orogen Syntaxes: Predicting Exhumation Rates and Thermochronometric Ages with Numerical Modeling

    Science.gov (United States)

    Nettesheim, Matthias; Ehlers, Todd A.; Whipp, David M.

    2017-04-01

    The change in plate boundary orientation and subducting plate geometry along orogen syntaxes may have major control on the subduction and exhumation dynamics at these locations. Previous work documents that the curvature of subducting plates in 3D at orogen syntaxes forces a buckling and flexural stiffening of the downgoing plate. The geometry of this stiffened plate region, also called indenter, can be observed in various subduction zones around the world (e.g. St. Elias Range, Alaska; Cascadia, USA; Andean syntaxis, South America). The development of a subducting, flexurally stiffened indenter beneath orogen syntaxes influences deformation in the overriding plate and can lead to accelerated and focused rock uplift above its apex. Moreover, the style of deformation in the overriding plate is influenced by the amount of trench or slab advance, which is the amount of overall shortening not accommodated by underthrusting. While many subduction zones exhibit little to no slab advance, the Nazca-South America subduction and especially the early stages of the India-Eurasia collision provide end-member examples. Here, we use a transient, lithospheric-scale, thermomechanical 3D model of an orogen syntaxis to investigate the effects of subducting a flexurally stiffened plate geometry and slab advance on upper plate deformation. A visco-plastic upper-plate rheology is used, along with a buckled, rigid subducting plate. The free surface of the thermomechanical model is coupled to a landscape evolution model that accounts for erosion by fluvial and hillslope processes. The cooling histories of exhumed rocks are used to predict the evolution of low-temperature thermochronometer ages on the surface. With a constant overall shortening for all simulations, the magnitude of slab advance is varied stepwise from no advance, with all shortening accommodated by underthrusting, to full slab advance, i.e. no motion on the megathrust. We show that in models where most shortening is

  6. Evidence of Himalayan erosional event at approx. 0.5 Ma from a sediment core from the equatorial Indian Ocean in the vicinityof ODP Leg 116 sites

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.; Gupta, S.M.; Mislankar, P.G.; Rao, B.R.; Parthiban, G.; Roelandts, I.; Patil, S.K.

    ; discrimination plots of Ca/Ti versus K/Ti and K sub(2)O/Al sub(2) O sub(3) and La/Yb ratios suggest a highly metamorphosed source such as higher Himalayan crystalline (HHC) series indicating two events of increased physical weathering and erosion in the Himalayan...

  7. Comparative ecophysiology of seed germination in two pairs of closely related pines of mediterranean and himalayan origins

    International Nuclear Information System (INIS)

    Saeed, M.; Raza, A.M.; Mushtaq, M.; Luqman, M.

    2016-01-01

    In this study we have examined the comparative ecophysiology of seed germination in two pairs of related pines of Mediterranean and Himalayan origins. One pair comprises Pinus canariensis and Pinus roxburghii, and the second Pinus peuce and Pinus wallichiana. Each pair has close taxonomic and morphological affinities. We have observed considerable differences among these pines about their germination behaviour. Seed germination of Pinus canariensis was feasible within a range of 15-20 degree C both under light and darkness, while the optimum germination of Pinus roxburghii was achievable at 25 degree C under white light. Germination rate of Pinus roxburghii was significantly enhanced under white light. A brief red light pulse resulted in promoting germination in Pinus roxburghii; however, the enhancing effect of red light was reversed by a brief far-red pulse; which indicated the mediation of phytochrome system in seed germination. Pinus peuce seeds were deeply dormant and required an extended period of stratification in order to come out of dormancy. Pinus wallichiana seeds were less dormant as compared to Pinus peuce, 30 d stratification or incubation under white light resulted in overcoming the dormancy. (author)

  8. Impact of the springtime Himalayan-Tibetan Plateau on the onset on the Indian summer monsoon in coupled forecasts

    Science.gov (United States)

    Orsolini, Yvan; Senan, Retish; Weisheimer, Antje; Vitart, Frederic; Balsamo, Gianpaolo; Doblas-Reyes, Francisco; Stockdale, Timothy; Dutra, Emanuel

    2016-04-01

    The springtime snowpack over the Himalayan-Tibetan Plateau (HTP) region has long been suggested to be an influential factor on the onset of the Indian summer monsoon. In the frame of the SPECS project, we have assessed the impact of realistic snow initialization in springtime over HTP on the onset of the Indian summer monsoon. We examine a suite of coupled ocean-atmosphere 4-month ensemble reforecasts made at the European Centre for Medium-Range Weather Forecasts (ECMWF), using the Seasonal Forecasting System 4. The reforecasts were initialized on 1 April every year for the period 1981-2010. In these seasonal reforecasts, the snow is initialized "realistically" with ERA-Interim/Land Reanalysis. In addition, we carried out an additional set of forecasts, identical in all aspects except that initial conditions for snow-related land surface variables over the HTP region are randomized. We show that high snow depth over HTP influences the meridional tropospheric temperature gradient reversal that marks the monsoon onset. Composite difference based on a normalized HTP snow index reveal that, in high snow years, (i) the onset is delayed by about 8 days, and (ii) negative precipitation anomalies and warm surface conditions prevail over India. We show that about half of this delay can be attributed to the realistic initialization of snow over the HTP region. We further demonstrate that high April snow depths over HTP are not uniquely influenced by either the El Nino-Southern Oscillation, the Indian Ocean Dipole or the North Atlantic Oscillation.

  9. Assessment of precipitation variability and uncertainty of stream flow in the Hindu Kush Himalayan and Karakoram River basins of Pakistan

    Science.gov (United States)

    Faiz, Muhammad Abrar; Liu, Dong; Fu, Qiang; Wrzesiński, Dariusz; Muneer, Shehakk; Khan, Muhammad Imran; Li, Tianxiao; Cui, Song

    2017-09-01

    The agricultural production system and hydropower production of Pakistan is largely dependent on melting water from the Hindu Kush Himalayan and the Karakoram River basins. Regardless of such significant prominence, a complete evaluation of the prevailing state of hydro-climatic variables is missing. In this context, we examine the precipitation variability and uncertainty of river flows based on diversity indexes and Shannon information entropy theory. The results indicate that the Shannon diversity index presents a clear depiction of precipitation variability on all metrological stations as compared to the Simpson diversity index. The maximum precipitation variability was found at Chilas station as compared to Hunza, Bunji and Gilgit stations. The results also show that the diversity indexes are highly, negatively correlated with standard deviation, and the amount of precipitation is less than 50 mm (dry months). At the decadal scale, the Hunza and Astore stations show higher precipitation evenness as compared to the Skardu, Bunji and Gilgit stations. The uncertainty analysis shows higher entropy value E D = 90% for Indus River gauged at Mangla station. The higher entropy means the greater the chaos of the variables and the lower their certainty. The analysis exhibited that the rivers with high stream flow variability also show low entropy of its distribution and therefore higher stream flow concentration in the annual cycle.

  10. Key role of Upper Mantle rocks in Alpine type orogens: some speculations derived from extensional settings for subduction zone processes and mountain roots

    Science.gov (United States)

    Müntener, Othmar

    2016-04-01

    Orogenic architecture and mountain roots are intrinsically related. Understanding mountain roots largely depends on geophysical methods and exhumed high pressure and high temperature rocks that might record snapshots of the temporal evolution at elevated pressure, temperatures and/or fluid pulses. If such high pressure rocks represent ophiolitic material they are commonly interpreted as exhumed remnants of some sort of 'mid-ocean ridge' processes. Mantle peridotites and their serpentinized counterparts thus play a key role in understanding orogenic architecture as they are often considered to track suture zones or ancient plate boundaries. The recognition that some mantle peridotites and their serpentinized counterparts are derived from ocean-continent transition zones (OCT's) or non-steady state (ultra-)slow plate separation systems question a series of 'common beliefs' that have been applied to understand Alpine-type collisional orogens in the framework of the ophiolite concept. Among these are: (i) the commonly held assumption of a simple genetic link between mantle melting and mafic (MORB-type) magmatism, (ii) the commonly held assumption that mélange zones represent deep subduction zone processes at the plate interface, (iii) that pre-collisional continental crust and oceanic crust can easily be reconstructed to their original thickness and used for reconstructions of the size of small subducted oceanic basins as geophysical data from rifted margins increasingly indicate that continental crust is thinned to much less than the average 30-35 kilometers over a large area that might be called the 'zone of hyperextension', and (iv) the lack of a continuous sheet of mafic oceanic crust and the extremely short time interval of formation results in a lack of 'eclogitization potential' during convergence and hence a lack of potential for subsequent slab pull and, perhaps, a lack of potential for 'slab-breakoff'. Here we provide a synopsis of mantle rocks from the

  11. Extreme variation of sulfur isotopic compositions in pyrite from the Qiuling sediment-hosted gold deposit, West Qinling orogen, central China: an in situ SIMS study with implications for the source of sulfur

    Science.gov (United States)

    Chen, Lei; Li, Xian-hua; Li, Jian-wei; Hofstra, Albert H.; Liu, Yu; Koenig, Alan E.

    2015-08-01

    high δ34S values. The variations in Au content and sulfur isotopic compositions across a single ore-stage pyrite grain may reflect displacement of indigenous groundwater with low δ34S values by auriferous metamorphic fluids with high δ34S values. The very low-grade metamorphism of the host rocks and the metamorphic derivation of sulfur for the ore pyrite indicate that the Qiuling sediment-hosted gold deposit is an epizonal manifestation of an orogenic gold system in the West Qinling orogen.

  12. Extreme variation of sulfur isotopic compositions in pyrite from the Qiuling sediment-hosted gold deposit, West Qinling orogen, central China: An in situ SIMS study with implications for the source of sulfur

    Science.gov (United States)

    Chen, Lei; Li, Xian-hua; Li, Jian-wei; Hofstra, Albert H.; Liu, Yu; Koenig, Alan E.

    2015-01-01

    rocks with very high δ34S values. The variations in Au content and sulfur isotopic compositions across a single ore-stage py- rite grain may reflect displacement of indigenous groundwater with low δ34S values by auriferous metamorphic fluids with high δ34S values. The very low-grade metamorphism of the host rocks and the metamorphic derivation of sulfur for the ore pyrite indicate that the Qiuling sediment-hosted gold deposit is an epizonal manifestation of an orogenic gold system in the West Qinling orogen.

  13. Tectonic evolution of the Black Sea orogene belt and the history of opening of the Black Sea basin

    Energy Technology Data Exchange (ETDEWEB)

    Uesuemezsoy, S. (Istanbul Univ. (Turkey))

    1988-08-01

    The Black Sea basin is surrounded by successive orogenic belts of Hercynian, Cimmerian, and Alpine ages. The Rhodope, Thracian, western Pontian, and Transcaucasian (RTPT) blocks of Precambrian age were involved by the circum-Black Sea orogene belts. The Hercynian orogene was documented in the Balkanide, Great Caucasian, Kriastide, southern Pontian, and Transcaucasian belts. The Cimmerian orogene extended north and south of the Black Sea. The southern Cimmerian orogene was represented by the circum-Rhodope and East Thracian-Strandja-Kuere belts. The northern Cimmerian orogene belt extended along the Dobruca-Crimean and southern slope belts. Following the demise of the Black Sea Cimmerian basin, the northernmost oceanic branch extending from Nish-Trajan through the present Black Sea to the intra-Transcaucasian basin, was opened within the Hercynian and Cimmerian consolidated terrain in the Late Jurassic. The other oceanic branch, extending from Izmir-Ankara through circum Kirsehir to various basins, was opened within the Paleotethyan collision belt, considered to be eastern extension of the Pindus basin. The Nish-Trajan sector of the northernmost basin was closed in the middle Cretaceous, and the Moesian platform re-fused to the Getic-Serbo-Macedonian-Rhodope belt. The easternmost extension of the intra-Transcaucasian basin disappeared in the Late Cretaceous. Consequently, the northernmost oceanic branch was reduced to the present Black Sea basin.

  14. Seismic anisotropies of the Songshugou peridotites (Qinling orogen, central China) and their seismic implications

    Science.gov (United States)

    Cao, Yi; Jung, Haemyeong; Song, Shuguang

    2018-01-01

    Though extensively studied, the roles of olivine crystal preferred orientations (CPOs or fabrics) in affecting the seismic anisotropies in the Earth's upper mantle are rather complicated and still not fully known. In this study, we attempted to address this issue by analyzing the seismic anisotropies [e.g., P-wave anisotropy (AVp), S-wave polarization anisotropy (AVs), radial anisotropy (ξ), and Rayleigh wave anisotropy (G)] of the Songshugou peridotites (dunite dominated) in the Qinling orogen in central China, based on our previously reported olivine CPOs. The seismic anisotropy patterns of olivine aggregates in our studied samples are well consistent with the prediction for their olivine CPO types; and the magnitude of seismic anisotropies shows a striking positive correlation with equilibrium pressure and temperature (P-T) conditions. Significant reductions of seismic anisotropies (AVp, max. AVs, and G) are observed in porphyroclastic dunite compared to coarse- and fine-grained dunites, as the results of olivine CPO transition (from A-/D-type in coarse-grained dunite, through AG-type-like in porphyroclastic dunite, to B-type-like in fine-grained dunite) and strength variation (weakening: A-/D-type → AG-type-like; strengthening: AG-type-like → B-type-like) during dynamic recrystallization. The transition of olivine CPOs from A-/D-type to B-/AG-type-like in the forearc mantle may weaken the seismic anisotropies and deviate the fast velocity direction and the fast S-wave polarization direction from trench-perpendicular to trench-oblique direction with the cooling and aging of forearc mantle. Depending on the size and distribution of the peridotite body such as the Songshugou peridotites, B- and AG-type-like olivine CPOs can be an additional (despite minor) local contributor to the orogen-parallel fast velocity direction and fast shear-wave polarization direction in the orogenic crust such as in the Songshugou area in Qinling orogen.

  15. Nature and provenance of the Beishan Complex, southernmost Central Asian Orogenic Belt

    Science.gov (United States)

    Zheng, Rongguo; Li, Jinyi; Xiao, Wenjiao; Zhang, Jin

    2018-03-01

    The ages and origins of metasedimentary rocks, which were previously mapped as Precambrian, are critical in rebuilding the orogenic process and better understanding the Phanerozoic continental growth in the Central Asian Orogenic Belt (CAOB). The Beishan Complex was widely distributed in the southern Beishan Orogenic Collage, southernmost CAOB, and their ages and tectonic affinities are still in controversy. The Beishan Complex was previously proposed as fragments drifted from the Tarim Craton, Neoproterozoic Block or Phanerozoic accretionary complex. In this study, we employ detrital zircon age spectra to constrain ages and provenances of metasedimentary sequences of the Beishan Complex in the Chuanshanxun area. The metasedimentary rocks here are dominated by zircons with Paleoproterozoic-Mesoproterozoic age ( 1160-2070 Ma), and yield two peak ages at 1454 and 1760 Ma. One sample yielded a middle Permian peak age (269 Ma), which suggests that the metasedimentary sequences were deposited in the late Paleozoic. The granitoid and dioritic dykes, intruding into the metasedimentary sequences, exhibit zircon U-Pb ages of 268 and 261 Ma, respectively, which constrain the minimum deposit age of the metasedimentary sequences. Zircon U-Pb ages of amphibolite (274 and 216 Ma) indicate that they might be affected by multi-stage metamorphic events. The Beishan Complex was not a fragment drifted from the Tarim Block or Dunhuang Block, and none of cratons or blocks surrounding Beishan Orogenic Collage was the sole material source of the Beishan Complex due to obviously different age spectra. Instead, 1.4 Ga marginal accretionary zones of the Columbia supercontinent might have existed in the southern CAOB, and may provide the main source materials for the sedimentary sequences in the Beishan Complex.

  16. Recent advances about of the orogenic modern belt (1000-500 M.A.) in Uruguay

    International Nuclear Information System (INIS)

    Bossi, J.

    1989-01-01

    Progress in lithologic, structural, tectonic and geo tectonic data about a 1000-500 m.y.orogenic belt developed at the East of Uruguay, arrived in the 80, are here described. Conclusions are mainly based on the 1/100.000 scale geologic map of a 6000 sq. km comprised between Sierra Ballena, Sierra de Animas, Pan de Azucar and Mariscala. These new data clearly states the lithological distribution and contribute to guide strategic prospect ion.

  17. The susceptibility of large river basins to orogenic and climatic drivers

    Science.gov (United States)

    Haedke, Hanna; Wittmann, Hella; von Blanckenburg, Friedhelm

    2017-04-01

    Large rivers are known to buffer pulses in sediment production driven by changes in climate as sediment is transported through lowlands. Our new dataset of in situ cosmogenic nuclide concentration and chemical composition of 62 sandy bedload samples from the world largest rivers integrates over 25% of Earth's terrestrial surface, distributed over a variety of climatic zones across all continents, and represents the millennial-scale denudation rate of the sediment's source area. We can show that these denudation rates do not respond to climatic forcing, but faithfully record orogenic forcing, when analyzed with respective variables representing orogeny (strain rate, relief, bouguer anomaly, free-air anomaly), and climate (runoff, temperature, precipitation) and basin properties (floodplain response time, drainage area). In contrast to this orogenic forcing of denudation rates, elemental bedload chemistry from the fine-grained portion of the same samples correlates with climate-related variables (precipitation, runoff) and floodplain response times. It is also well-known from previous compilations of river-gauged sediment loads that the short-term basin-integrated sediment export is also climatically controlled. The chemical composition of detrital sediment shows a climate control that can originate in the rivers source area, but this signal is likely overprinted during transfer through the lowlands because we also find correlation with floodplain response times. At the same time, cosmogenic nuclides robustly preserve the orogenic forcing of the source area denudation signal through of the floodplain buffer. Conversely, previous global compilations of cosmogenic nuclides in small river basins show the preservation of climate drivers in their analysis, but these are buffered in large lowland rivers. Hence, we can confirm the assumption that cosmogenic nuclides in large rivers are poorly susceptible to climate changes, but are at the same time highly suited to detect

  18. Deformation Partitioning: The Missing Link Between Outcrop-Scale Observations And Orogen-Scale Processes

    Science.gov (United States)

    Attia, S.; Paterson, S. R.; Jiang, D.; Miller, R. B.

    2017-12-01

    Structural studies of orogenic deformation fields are mostly based on small-scale structures ubiquitous in field exposures, hand samples, and under microscopes. Relating deformation histories derived from such structures to changing lithospheric-scale deformation and boundary conditions is not trivial due to vast scale separation (10-6 107 m) between characteristic lengths of small-scale structures and lithospheric plates. Rheological heterogeneity over the range of orogenic scales will lead to deformation partitioning throughout intervening scales of structural development. Spectacular examples of structures documenting deformation partitioning are widespread within hot (i.e., magma-rich) orogens such as the well-studied central Sierra Nevada and Cascades core of western North America: (1) deformation partitioned into localized, narrow, triclinic shear zones separated by broad domains of distributed pure shear at micro- to 10 km scales; (2) deformation partitioned between plutons and surrounding metamorphic host rocks as shown by pluton-wide magmatic fabrics consistently oriented differently than coeval host rock fabrics; (3) partitioning recorded by different fabric intensities, styles, and orientations established from meter-scale grid mapping to 100 km scale domainal analyses; and (4) variations in the causes of strain and kinematics within fold-dominated domains. These complex, partitioned histories require synthesized mapping, geochronology, and structural data at all scales to evaluate partitioning and in the absence of correct scaling can lead to incorrect interpretations of histories. Forward modeling capable of addressing deformation partitioning in materials containing multiple scales of rheologically heterogeneous elements of varying characteristic lengths provides the ability to upscale the large synthesized datasets described above to plate-scale tectonic processes and boundary conditions. By comparing modeling predictions from the recently developed

  19. Why inputs matter: Selection of climatic variables for species distribution modelling in the Himalayan region

    Science.gov (United States)

    Bobrowski, Maria; Schickhoff, Udo

    2017-04-01

    Betula utilis is a major constituent of alpine treeline ecotones in the western and central Himalayan region. The objective of this study is to provide first time analysis of the potential distribution of Betula utilis in the subalpine and alpine belts of the Himalayan region using species distribution modelling. Using Generalized Linear Models (GLM) we aim at examining climatic factors controlling the species distribution under current climate conditions. Furthermore we evaluate the prediction ability of climate data derived from different statistical methods. GLMs were created using least correlated bioclimatic variables derived from two different climate models: 1) interpolated climate data (i.e. Worldclim, Hijmans et al., 2005) and 2) quasi-mechanistical statistical downscaling (i.e. Chelsa; Karger et al., 2016). Model accuracy was evaluated by the ability to predict the potential species distribution range. We found that models based on variables of Chelsa climate data had higher predictive power, whereas models using Worldclim climate data consistently overpredicted the potential suitable habitat for Betula utilis. Although climatic variables of Worldclim are widely used in modelling species distribution, our results suggest to treat them with caution when remote regions like the Himalayan mountains are in focus. Unmindful usage of climatic variables for species distribution models potentially cause misleading projections and may lead to wrong implications and recommendations for nature conservation. References: Hijmans, R.J., Cameron, S.E., Parra, J.L., Jones, P.G. & Jarvis, A. (2005) Very high resolution interpolated climate surfaces for global land areas. International Journal of Climatology, 25, 1965-1978. Karger, D.N., Conrad, O., Böhner, J., Kawohl, T., Kreft, H., Soria-Auza, R.W., Zimmermann, N., Linder, H.P. & Kessler, M. (2016) Climatologies at high resolution for the earth land surface areas. arXiv:1607.00217 [physics].

  20. Antibacterial and Antifungal Potential of Himalayan Medicinal Plants for Treating Wound Infections

    International Nuclear Information System (INIS)

    Habiba, U.; Ahmad, M.; Shinwari, S.; Sultana, S.; Zafar, M.; Shinwari, Z. K.

    2016-01-01

    Many bacterial and fungal strains are involved in wound infectious diseases as most of these strains become resistant to the most commonly used synthetic drugs in Himalayan region. Plant based natural products seem to be an alternative to this problem. The aim of this investigation was to evaluate the In vitro antibacterial and antifungal activities of 30 medicinal plants used in folk recipes by Himalayan people to treat wound infections against multi-drug resistant pathogens. In total of six medically important Myco-bacterial strains Streptococcus pyogenes, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Candida albicans and Aspergillus niger were tested against methanolic plant extracts at 5 mg/ml concentration using agar disc well diffusion method to determined Minimum inhibitory concentrations (MICs). The plant extracts showed varied levels of MICs against test microorganisms. The strongest antibacterial activity was reported in methanolic extract of Cynadon dactylon (L.) Pers. against Klebsiella pneumoniae with 20.67±1.36 mm MICs, while Candida albicans was considered to be the most resistant pathogen with MICs 9.6±0.57 mm. The findings were compared with results obtained using standard antibiotics, aminooxanilic, ciprofloxacin, cefotaxime, fluconazole and itraconazole at conc. 5mg/ ml. The results provide an evidence of folk medicinal uses of plants among the Himalayan communities to treat wounds. Further research needs to be carried out to identify the active molecules and evaluate the in vivo antibacterial and antifungal activities as well as toxicity level with clinical trials to use full potential of these plants for drug discovery development to control wounds globally. (author)

  1. Schumann resonance frequency variations observed in magnetotelluric data recorded from Garhwal Himalayan region India

    Directory of Open Access Journals (Sweden)

    R. Chand

    2009-09-01

    Full Text Available Schumann resonance (SR frequency variation has been studied using Magnetotelluric (MT data recorded in one of the world's toughest and generally inaccessible Himalayan terrain for the first time in the author's knowledge. The magnetotelluric data, in the form of orthogonal time varying electric and magnetic field components (Ex, Ey, Bx and By, recorded during 10 March–23 May 2006, in the Himalayan region, India, at elevations between 1228–2747 m above mean sea level (amsl, were used to study the SR frequency variation. Electromagnetic field components, in the form of time series, were recorded at 64 Hz sampling frequency at a site located away from the cultural noise. Spectral analysis of time series data, at a frequency resolution of 0.03 Hz, has been performed using Fast Fourier Transform (FFT algorithm. Spectral stabilization in three Schumann resonance modes is achieved by averaging the power spectral magnitude of 32 data segments, each with 2048 sample data. Amplitude variation in the Schumann resonance frequency associated with day-night, sunrise and terminator effect was observed. Average diurnal variation in the first three Schumann resonance frequencies associated with magnetic field components is presented. The maximum frequency variation of about 0.3, 0.4 and 0.7 Hz was observed in the first, second and third mode, respectively. The frequency variations observed in electric and magnetic field components also show phase shift and varying attenuation. The SR frequency variation has been used to define the ionospheric electron density variation in the Himalayan region, India.

  2. Schumann resonance frequency variations observed in magnetotelluric data recorded from Garhwal Himalayan region India

    Directory of Open Access Journals (Sweden)

    R. Chand

    2009-09-01

    Full Text Available Schumann resonance (SR frequency variation has been studied using Magnetotelluric (MT data recorded in one of the world's toughest and generally inaccessible Himalayan terrain for the first time in the author's knowledge. The magnetotelluric data, in the form of orthogonal time varying electric and magnetic field components (Ex, Ey, Bx and By, recorded during 10 March–23 May 2006, in the Himalayan region, India, at elevations between 1228–2747 m above mean sea level (amsl, were used to study the SR frequency variation. Electromagnetic field components, in the form of time series, were recorded at 64 Hz sampling frequency at a site located away from the cultural noise. Spectral analysis of time series data, at a frequency resolution of 0.03 Hz, has been performed using Fast Fourier Transform (FFT algorithm. Spectral stabilization in three Schumann resonance modes is achieved by averaging the power spectral magnitude of 32 data segments, each with 2048 sample data. Amplitude variation in the Schumann resonance frequency associated with day-night, sunrise and terminator effect was observed. Average diurnal variation in the first three Schumann resonance frequencies associated with magnetic field components is presented. The maximum frequency variation of about 0.3, 0.4 and 0.7 Hz was observed in the first, second and third mode, respectively. The frequency variations observed in electric and magnetic field components also show phase shift and varying attenuation. The SR frequency variation has been used to define the ionospheric electron density variation in the Himalayan region, India.

  3. Quantitative insights into the role of gravitational collapse in major orogenic belts

    Directory of Open Access Journals (Sweden)

    E. Mantovani

    2006-06-01

    Full Text Available Abstract Previous works have proposed gravitational collapse as the driving mechanism of extensional deformation of thickened continental crust. In this work we investigate the physical plausibility of this interpretation for the most important orogenic belts of the world by computing the spreading force induced by lateral variations of crustal thickness and the possible resisting forces. Two collapse mechanisms, one involving the upper crust only and the other the whole crust, have been considered. Particular attention has been devoted to constrain the uncertainty affecting such computations, mostly due to the large variability of the thermal and mechanical properties of rocks. The results obtained show that gravitational collapse is not a plausible mechanism in the four Mediterranean orogens here considered (Northern Apennines, Calabrian Arc, Hellenic Arc and Carpathians. For the other orogenic zones we have taken into account (Western U.S. Cordillera, Central Andes, Himalayas and Central Alps, the large uncertainty that affects the estimate of spreading and resisting forces does not allow to firmly assess the feasibility of gravitational collapse.

  4. Wave like signatures in aerosol optical depth and associated radiative impacts over the central Himalayan region

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, K. K.; Phanikumar, D. V.; Kumar, K.  Niranjan; Reddy, Kishore; Kotamarthi, V. R.; Newsom, Rob K.; Ouarda, Taha B. M. J.

    2015-10-01

    Doppler Lidar and Multi-Filter Rotating Shadowband Radiometer (MFRSR) observations are utilized to show wave like signatures in aerosol optical depth (AOD) during daytime boundary layer evolution over the Himalayan region. Fourier analysis depicted 60–80 min periods dominant during afternoon hours, implying that observed modulations could be plausible reason for the AOD forenoon–afternoon asymmetry which was previously reported. Inclusion of wave amplitude in diurnal variation of aerosol radiative forcing estimates showed ~40% additional warming in the atmosphere relative to mean AOD. The present observations emphasize the importance of wave induced variations in AOD and radiation budget over the site.

  5. Sediment pathways and emergence of Himalayan source material in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Ismaiel, M.; Srinivas, K.; Gopala Rao, D.; Mishra, J.; Saha, D.

    Basin and ECMI), following the structural architecture of the BoB. The velocities obtained from the present dataset (wide–angle seismic reflections and drill wells A and B) and from pub- lished refraction data31 were largely followed to calculate... with strong supportive evidences – onlap un- conformity, buried channels, fan architecture and apex location – for discharge of sediments through the Ganges–Brahmaputra delta to the BoB. Around this time in the Himalayan foreland basin, a major Oligocene...

  6. New taxonomic and faunistic data on the Himalayan Lesteva Latreille, 1797 (Coleoptera: Staphylinidae: Omaliinae).

    Science.gov (United States)

    Shavrin, Alexey V

    2016-12-05

    New taxonomic and faunistc data for seven species of the genus Lesteva Latreille, 1797 of the Himalayas are presented. Two species are redescribed: L. (s.str.) kargilensis Cameron, 1934 and L. (s.str.) steeli Lohse, 1982. The aedeagus of L. (s.str.) steeli is illustrated. One synonym is proposed: L. (s.str.) brevipennis Cameron, 1941 = L. pakistana Coiffait, 1984 syn. n. A lectotype and paralectotypes for L. (s.str.) torrentum Cameron, 1924 are designated. A key to species known from the Himalayan Region is provided.

  7. Estimates of late Cenozoic climate change relevant to Earth surface processes in tectonically active orogens

    Directory of Open Access Journals (Sweden)

    S. G. Mutz

    2018-04-01

    Full Text Available The denudation history of active orogens is often interpreted in the context of modern climate gradients. Here we address the validity of this approach and ask what are the spatial and temporal variations in palaeoclimate for a latitudinally diverse range of active orogens? We do this using high-resolution (T159, ca. 80  ×  80 km at the Equator palaeoclimate simulations from the ECHAM5 global atmospheric general circulation model and a statistical cluster analysis of climate over different orogens (Andes, Himalayas, SE Alaska, Pacific NW USA. Time periods and boundary conditions considered include the Pliocene (PLIO,  ∼  3 Ma, the Last Glacial Maximum (LGM,  ∼  21 ka, mid-Holocene (MH,  ∼  6 ka, and pre-industrial (PI, reference year 1850. The regional simulated climates of each orogen are described by means of cluster analyses based on the variability in precipitation, 2 m air temperature, the intra-annual amplitude of these values, and monsoonal wind speeds where appropriate. Results indicate the largest differences in the PI climate existed for the LGM and PLIO climates in the form of widespread cooling and reduced precipitation in the LGM and warming and enhanced precipitation during the PLIO. The LGM climate shows the largest deviation in annual precipitation from the PI climate and shows enhanced precipitation in the temperate Andes and coastal regions for both SE Alaska and the US Pacific Northwest. Furthermore, LGM precipitation is reduced in the western Himalayas and enhanced in the eastern Himalayas, resulting in a shift of the wettest regional climates eastward along the orogen. The cluster-analysis results also suggest more climatic variability across latitudes east of the Andes in the PLIO climate than in other time slice experiments conducted here. Taken together, these results highlight significant changes in late Cenozoic regional climatology over the last  ∼  3 Myr. Comparison

  8. Estimates of late Cenozoic climate change relevant to Earth surface processes in tectonically active orogens

    Science.gov (United States)

    Mutz, Sebastian G.; Ehlers, Todd A.; Werner, Martin; Lohmann, Gerrit; Stepanek, Christian; Li, Jingmin

    2018-04-01

    The denudation history of active orogens is often interpreted in the context of modern climate gradients. Here we address the validity of this approach and ask what are the spatial and temporal variations in palaeoclimate for a latitudinally diverse range of active orogens? We do this using high-resolution (T159, ca. 80 × 80 km at the Equator) palaeoclimate simulations from the ECHAM5 global atmospheric general circulation model and a statistical cluster analysis of climate over different orogens (Andes, Himalayas, SE Alaska, Pacific NW USA). Time periods and boundary conditions considered include the Pliocene (PLIO, ˜ 3 Ma), the Last Glacial Maximum (LGM, ˜ 21 ka), mid-Holocene (MH, ˜ 6 ka), and pre-industrial (PI, reference year 1850). The regional simulated climates of each orogen are described by means of cluster analyses based on the variability in precipitation, 2 m air temperature, the intra-annual amplitude of these values, and monsoonal wind speeds where appropriate. Results indicate the largest differences in the PI climate existed for the LGM and PLIO climates in the form of widespread cooling and reduced precipitation in the LGM and warming and enhanced precipitation during the PLIO. The LGM climate shows the largest deviation in annual precipitation from the PI climate and shows enhanced precipitation in the temperate Andes and coastal regions for both SE Alaska and the US Pacific Northwest. Furthermore, LGM precipitation is reduced in the western Himalayas and enhanced in the eastern Himalayas, resulting in a shift of the wettest regional climates eastward along the orogen. The cluster-analysis results also suggest more climatic variability across latitudes east of the Andes in the PLIO climate than in other time slice experiments conducted here. Taken together, these results highlight significant changes in late Cenozoic regional climatology over the last ˜ 3 Myr. Comparison of simulated climate with proxy-based reconstructions for the MH and

  9. Modelling catchment hydrological responses in a Himalayan Lake ...

    Indian Academy of Sciences (India)

    Multi-sensor and multi-temporal satellite data for 1992 and 2005 was used for determining the spatio-temporal dynamics of the lake catchment. Geographic Information System (GIS) based simulation model namely Generalized Watershed Loading Function (GWLF) was used to model the hydrological processes under the ...

  10. Modelling catchment hydrological responses in a Himalayan Lake ...

    Indian Academy of Sciences (India)

    cesses in Dal lake catchment of Kashmir Himalayas by integrating remote sensing, simulation modelling ... have significantly altered the land system, impairing, inter-alia, sustained biotic communities and water quality of the lake. The primary objective of this paper was ..... zone is modelled as linear ground water reservoir.

  11. The Kharapeh orogenic gold deposit: Geological, structural, and geochemical controls on epizonal ore formation in West Azerbaijan Province, Northwestern Iran

    Science.gov (United States)

    Niroomand, Shojaeddin; Goldfarb, Richard J.; Moore, Farib; Mohajjel, Mohammad; Marsh, Erin E.

    2011-01-01

    part of a diachronous gold event during the middle to late Tertiary throughout the SSZ and during the final stages of the Zagros orogeny. The proximity of Kharapeh to the main tectonic suture of the orogen, well-developed regional fold systems with superimposed complex fracture geometries, and recognition of nearby volcanogenic massive sulfide systems that suggest a region characterized by sulfur- and metal-rich crustal rocks, collectively indicate an area of the SSZ with high favorability for undiscovered gold resources.

  12. Eastern Turkish high plateau as a small Turkic-type orogen: Implications for post-collisional crust-forming processes in Turkic-type orogens

    Science.gov (United States)

    Şengör, A. M. Celâl; Özeren, Mehmet Sinan; Keskin, Mehmet; Sakınç, Mehmet; Özbakır, Ali Değer; Kayan, İlhan

    Post-collisional magmatism may be generated by extensive crustal melting in Tibet-type collisional environments or by falling out of slabs from under giant subduction-accretion complexes in Turkic-type collisional orogens giving rise to decompression melting of the asthenospheric mantle replacing the removed oceanic lithosphere. In Turkic-type post-collisional magmatism, the magmatic products are dominantly alkalic to peralkalic and greatly resemble those of extensional regions giving rise to much confusion especially in interpreting old collisional orogenic belts. Such magmatic regions are also host to a variety of economically valuable ore deposits, including gold. One place in the world where today active, Turkic-type post-collisional magmatism is present is the eastern Anatolian high plateau, produced after the terminal Arabia/Eurasia collision in the late Miocene. The plateau is mostly underlain by the late Cretaceous to Oligocene East Anatolian Accretionary Complex, which formed south of the Rhodope-Pontide magmatic arc. This subduction-accretion complex has been further shortening since the collision, but it has also since been domed and became almost entirely covered by at least 15,000 km 3 of volcanic rocks. The volcanic rocks are calc-alkalic in the north, transitional in the middle, and alkalic in the south of the plateau. Where the crust is thinnest today (less than 38 km), the volcanics are derived almost entirely from an enriched mantle. The ages of the volcanics also become younger from north to south, from about 11 Ma to possibly 17th century AD. We interpret the origin of the magmatic rocks as the result of decompression melting of the asthenospheric mantle sucked towards the exposed base of the East Anatolian Accretionary Complex as the oceanic lithosphere beneath it fell out. The lower density of the hot asthospheric material was the cause of the doming. We believe that similar processes dominated the post-collisional tectonics of such vast

  13. European Bulletin of Himalayan Research (EBHR) Number 14, 1998

    OpenAIRE

    South Asia Institute, Heidelberg University, Germany; (CNRS) Centre National de la Recherche Scientifique, France; (SOAS) School of Oriental and African Studies, UK

    1998-01-01

    Graham Clarke : An Appreciation by Ben Campbell; Innovations in Traditional Crafts by Nager and Hunza; In the 20th Century by Jurgen Wasim Frembgen; Work and Nutrition in High Asia by Hiltrud Herbers; The Restoration of Baltit fort by Stefano Bianca; Seasonal Migration in Western Nepal by Satya Shrestha; On Francis Buchanan Hamilton's Account of the Kingdom of Nepal by Marie Lecomte-Tilouine; Credit Systems and Urban Development in Nepal by Michael Muhlich; Ladakh Studies, 8th Colloquium, Moe...

  14. Bionic Design for Mars Sampling Scoop Inspired by Himalayan Marmot Claw

    Directory of Open Access Journals (Sweden)

    Long Xue

    2016-01-01

    Full Text Available Cave animals are often adapted to digging and life underground, with claw toes similar in structure and function to a sampling scoop. In this paper, the clawed toes of the Himalayan marmot were selected as a biological prototype for bionic research. Based on geometric parameter optimization of the clawed toes, a bionic sampling scoop for use on Mars was designed. Using a 3D laser scanner, the point cloud data of the second front claw toe was acquired. Parametric equations and contour curves for the claw were then built with cubic polynomial fitting. We obtained 18 characteristic curve equations for the internal and external contours of the claw. A bionic sampling scoop was designed according to the structural parameters of Curiosity’s sampling shovel and the contours of the Himalayan marmot’s claw. Verifying test results showed that when the penetration angle was 45° and the sampling speed was 0.33 r/min, the bionic sampling scoops’ resistance torque was 49.6% less than that of the prototype sampling scoop. When the penetration angle was 60° and the sampling speed was 0.22 r/min, the resistance torque of the bionic sampling scoop was 28.8% lower than that of the prototype sampling scoop.

  15. Antioxidant and antiproliferative activities of phenolics isolated from fruits of Himalayan yellow raspberry (Rubus ellipticus).

    Science.gov (United States)

    Saini, Ritu; Dangwal, Koushalya; Singh, Himani; Garg, Veena

    2014-11-01

    Yellow Himalayan raspberry, a wild edible fruit, was analyzed for phenolic contents, and antioxidant, antibacterial and antiproliferative activities. Phenolics were extracted using 80 % aqueous solvents containing methanol, acidic methanol, acetone and acidic acetone. Our analysis revealed that the acidic acetone extracts recovered the highest level of total phenolics (899 mg GAE/100 g FW) and flavonoids (433.5 mg CE/100 g FW). Free radical scavenging activities (DPPH, ABTS, superoxide and linoleate hydroperoxide radicals) and ferric reducing activity were highest in the acetone and acidic acetone extracts. No metal chelating or antibacterial activity was detected in any of the extracts. Acetone and methanol extracts showed potent antiproliferative activity against human cervical cancer cells (C33A) with an EC50 of inhibition at 5.04 and 4. 9 mg/ml fruit concentration respectively, while showing no cytotoxicity to normal PBMCs cells. Therefore, the present study concluded that the yellow Himalayan raspberry is a potent source of phytochemicals having super antioxidant and potent antiproliferative activities.

  16. Partial altitudinal migration of a Himalayan Forest pheasant.

    Science.gov (United States)

    Norbu, Nawang; Wikelski, Martin C; Wilcove, David S; Partecke, Jesko; Ugyen; Tenzin, Ugyen; Sherub; Tempa, Tshering

    2013-01-01

    Altitudinal migration systems are poorly understood. Recent advances in animal telemetry which enables tracking of migrants across their annual cycles will help illustrate unknown migration patterns and test existing hypotheses. Using telemetry, we show the existence of a complex partial altitudinal migration system in the Himalayas and discuss our findings to help better understand partial and altitudinal migration. We used GPS/accelerometer tags to monitor the migration of Satyr tragopan (Tragopan satyra) in the Bhutan Himalayas. We tagged 38 birds from 2009 - 2011 and found that tragopans are partially migratory. Fall migration lasted from the 3(rd) week of September till the 3(rd) week of November with migrants traveling distances ranging from 1.25 km to 13.5 km over 1 to 32 days. Snowfall did not influence the onset of migration. Return migration started by the 1(st) week of March and lasted until the 1(st) week of April. Individuals returned within 4 to 10 days and displayed site fidelity. One bird switched from being a migrant to a non-migrant. Tragopans displayed three main migration patterns: 1) crossing multiple mountains; 2) descending/ascending longitudinally; 3) moving higher up in winter and lower down in summer. More females migrated than males; but, within males, body size was not a factor for predicting migrants. Our observations of migrants traversing over multiple mountain ridges and even of others climbing to higher elevations is novel. We support the need for existing hypotheses to consider how best to explain inter- as well as intra-sexual differences. Most importantly, having shown that the patterns of an altitudinal migration system are complex and not a simple up and down slope movement, we hope our findings will influence the way altitudinal migrations are perceived and thereby contribute to a better understanding of how species may respond to climate change.

  17. Partial altitudinal migration of a Himalayan Forest pheasant.

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    Nawang Norbu

    Full Text Available BACKGROUND: Altitudinal migration systems are poorly understood. Recent advances in animal telemetry which enables tracking of migrants across their annual cycles will help illustrate unknown migration patterns and test existing hypotheses. Using telemetry, we show the existence of a complex partial altitudinal migration system in the Himalayas and discuss our findings to help better understand partial and altitudinal migration. METHODOLOGY/PRINCIPAL FINDINGS: We used GPS/accelerometer tags to monitor the migration of Satyr tragopan (Tragopan satyra in the Bhutan Himalayas. We tagged 38 birds from 2009 - 2011 and found that tragopans are partially migratory. Fall migration lasted from the 3(rd week of September till the 3(rd week of November with migrants traveling distances ranging from 1.25 km to 13.5 km over 1 to 32 days. Snowfall did not influence the onset of migration. Return migration started by the 1(st week of March and lasted until the 1(st week of April. Individuals returned within 4 to 10 days and displayed site fidelity. One bird switched from being a migrant to a non-migrant. Tragopans displayed three main migration patterns: 1 crossing multiple mountains; 2 descending/ascending longitudinally; 3 moving higher up in winter and lower down in summer. More females migrated than males; but, within males, body size was not a factor for predicting migrants. CONCLUSIONS/SIGNIFICANCE: Our observations of migrants traversing over multiple mountain ridges and even of others climbing to higher elevations is novel. We support the need for existing hypotheses to consider how best to explain inter- as well as intra-sexual differences. Most importantly, having shown that the patterns of an altitudinal migration system are complex and not a simple up and down slope movement, we hope our findings will influence the way altitudinal migrations are perceived and thereby contribute to a better understanding of how species may respond to climate change.

  18. Boundary layer effects above a Himalayan valley near Mount Everest

    Science.gov (United States)

    Sun, Fanglin; Ma, Yaoming; Li, Maoshan; Ma, Weiqiang; Tian, Hui; Metzger, Stefan

    2007-04-01

    Periodical Wind Profiler and Radio Acoustic Sounding System observations have been commenced at the Himalayas' northern slope nearby Mount Everest in September 2005. Primarily data sets obtained 25 km remote from the glacier edge are utilized for a preliminary discussion of planetary boundary layer circulation resembling high alpine mountainous regions. Substantial findings include the detection of two wind shears and the phenomenon of glacier wind at a distance of 25 km from the glaciers. The latter lead to a reversed compensatory flow in a vertical scale of up to 2000 m above ground level, pointing at supra regional impact.

  19. Effective Reversible Immobilization of Captive Himalayan Black Bears (Selenarctos thibetanus laniger) with Medetomidine-Tiletamine-Zolazepam and Atipamezole.

    Science.gov (United States)

    Arun, Attur Shanmugam; Krishna, Sanath; Antony, Linto; Pillai, Harikrishnan Chandran; Venkataramanappa, Manjunatha; Suresh, Sujay

    2016-04-28

    We used a combination of medetomidine and tiletamine-zolazepam to immobilize five Himalayan black bears (Selenarctos thibetanus laniger) in Bannerghatta Biological Park, Bangalore, India. Medetomidine and tiletamine-zolazepam were administered at 0.01 mg/kg and 0.5 mg/kg, respectively. We describe procedures and observations recorded during the immobilization.

  20. An analysis of snow cover changes in the Himalayan region using MODIS snow products and in-situ temperature data

    NARCIS (Netherlands)

    Maskey, S.; Uhlenbrook, S.; Ojha, S.

    2011-01-01

    Amidst growing concerns over the melting of the Himalayas’ snow and glaciers, we strive to answer some of the questions related to snow cover changes in the Himalayan region covering Nepal and its vicinity using Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover products from 2000 to

  1. Supraglacial Ponds Regulate Runoff From Himalayan Debris-Covered Glaciers

    Science.gov (United States)

    Irvine-Fynn, Tristram D. L.; Porter, Philip R.; Rowan, Ann V.; Quincey, Duncan J.; Gibson, Morgan J.; Bridge, Jonathan W.; Watson, C. Scott; Hubbard, Alun; Glasser, Neil F.

    2017-12-01

    Meltwater and runoff from glaciers in High Mountain Asia is a vital freshwater resource for one-fifth of the Earth's population. Between 13% and 36% of the region's glacierized areas exhibit surface debris cover and associated supraglacial ponds whose hydrological buffering roles remain unconstrained. We present a high-resolution meltwater hydrograph from the extensively debris-covered Khumbu Glacier, Nepal, spanning a 7 month period in 2014. Supraglacial ponds and accompanying debris cover modulate proglacial discharge by acting as transient and evolving reservoirs. Diurnally, the supraglacial pond system may store >23% of observed mean daily discharge, with mean recession constants ranging from 31 to 108 h. Given projections of increased debris cover and supraglacial pond extent across High Mountain Asia, we conclude that runoff regimes may become progressively buffered by the presence of supraglacial reservoirs. Incorporation of these processes is critical to improve predictions of the region's freshwater resource availability and cascading environmental effects downstream.

  2. Assessment of Land-Use/Land-Cover Change and Forest Fragmentation in the Garhwal Himalayan Region of India

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    Amit Kumar Batar

    2017-04-01

    Full Text Available The Garhwal Himalaya has experienced extensive deforestation and forest fragmentation, but data and documentation detailing this transformation of the Himalaya are limited. The aim of this study is to analyse the observed changes in land cover and forest fragmentation that occurred between 1976 and 2014 in the Garhwal Himalayan region in India. Three images from Landsat 2 Multispectral Scanner System (MSS, Landsat 5 Thematic Mapper (TM, and Landsat 8 Operational Land Imager (OLI were used to extract the land cover maps. A cross-tabulation detection method in the geographic information system (GIS module was used to detect land cover changes during the 1st period (1976–1998 and 2nd period (1998–2014. The landscape fragmentation tool LFT v2.0 was used to construct a forest fragmentation map and analyse the forest fragmentation pattern and change during the 1st period (1976–1998 and 2nd period (1998–2014. The overall annual rate of change in the forest cover was observed to be 0.22% and 0.27% in the 1st period (1976–1998 and 2nd period (1998–2014, respectively. The forest fragmentation analysis shows that a large core forest has decreased throughout the study period. The total area of forest patches also increased from 1976 to 2014, which are completely degraded forests. The results indicate that anthropogenic activities are the main causes of the loss of forest cover and forest fragmentation, but that natural factors also contributed. An increase in the area of scrub and barren land also contributed to the accumulation of wasteland or non-forest land in this region. Determining the trend and the rate of land cover conversion is necessary for development planners to establish a rational land use policy.

  3. Adverse impacts of pasture abandonment in Himalayan protected areas: Testing the efficiency of a Natural Resource Management Plan (NRMP)

    International Nuclear Information System (INIS)

    Nautiyal, Sunil; Kaechele, Harald

    2007-01-01

    The high elevational areas in the Himalayas of India are dominated by forests and alpine pastures. There are many protected areas in the region, including Nanda Devi Biosphere Reserve (NDBR) and Valley of Flowers (VOF) where natural resource management plan (NRMP) has been implemented for the conservation of biodiversity. This has affected the traditional animal husbandry system, as well as the vegetation dynamics of alpine pastures. An integrated approach to studying the impact of NRMP in the region has been applied by us. First, a survey was conducted regarding livestock management, data pertaining the livestock husbandry, the role of animal husbandry in economics of rural household, and socioeconomics. Second, field based study on phytosociology of some important alpine herbs was done to enumerate the density and species richness in different land mark of the region. Thereafter, satellite data and Geographic Information System (GIS) were used to develop a land cover map of the area and to note changes in the landscape over time after implementation of NRMP. From an economic point of view the implementation of such plan is a setback to the rural economy. However, the ecological perspective of such models is a threat to the diversity of alpine pastures. The invasion of bushes/thorny bushes/shrubs and weeds with their luxuriant growth is changing the vegetation index and dynamics. Consequently, the diversity of herbs in alpine pastures of the Himalayan Mountains is in jeopardy. Overall, the situation is leading to landscape change in the region. This study is helpful for generating useful outcomes and strategies considering the question or debate 'is grazing good or bad for pasture ecosystems in the Himalayas?'

  4. Chronological constraints on tectonic evolution of the Chinese Tianshan Orogen through detrital zircons from modern and paleo-river sands

    Science.gov (United States)

    Ren, Rong; Guan, Shuwei; Han, Baofu

    2017-04-01

    The Chinese Tianshan Orogen marked the prolonged, complicated interactions between the southwestern Paleo-Asian Ocean and surrounding blocks. Massive new and previous detrital zircon U-Pb chronological data from modern and paleo-river sands (more than 7000 ages from 102 samples) were compiled to constrain its tectonic evolution. The Chinese Tianshan Orogen is characterized by predominant Paleozoic and minor Mesozoic and Precambrian detrital zircon ages that show multimodal characteristic. The oldest Phanerozoic zircon population (peak at 475 Ma) results from subduction and closure of the Early Paleozoic Terskey Ocean. But the absence of this peak in Chinese North and southern South Tianshan suggests that the subductions of the North and South Tianshan oceans may not initiate until Late Ordovician, with subsequent 460-390 Ma and 360-320 Ma arc magmatism. Similar to magmatic suite in classic collisional orogens, the youngest massive 320-270 Ma magmatism is supposed to be post-collisional. The North and South Tianshan oceans therefore probably had their closure to form the Chinese Tianshan Orogen during Late Carboniferous. The weak Mesozoic intra-plate magmatism further argues against a Late Permian-Triassic Tianshan Orogen for the lack of extensive syn- and post-collisional magmatism. Moreover, the diverse Precambrian detrital zircon age patterns indicate that the surrounding blocks have distinct tectonic evolution and short-term amalgamation during the Neoproterozoic.

  5. Snow sublimation on a high-altitude Himalayan glacier

    Science.gov (United States)

    Stigter, E.; Litt, M.; Steiner, J. F.; Bonekamp, P. N. J.; Bierkens, M. F.; Shea, J.; Immerzeel, W. W.

    2017-12-01

    Snow sublimation is a loss of water from a snowpack to the atmosphere due to direct phase transition of snow to water vapour. Conditions at high elevations in the Himalaya favour sublimation, i.e. low atmospheric pressure, high wind speed, dry air and high incoming solar radiation. Snow sublimation is a potential important component of the high-altitude water and glacier mass balance, but measurements are non-existent in the Himalaya and models generally ignore this process. Hence, we measured surface latent heat fluxes with an eddy covariance system on Yala Glacier (5350 m a.s.l) in the Nepalese Himalaya to quantify the role snow sublimation plays in the water budget. A one-month data set from October to November 2016 reveals that cumulative sublimation is substantial relative to the dry season precipitation (31 mm for a 32-day period). Sublimation parameterizations of different complexity were subsequently tested against our field measurements to quantify sublimation patterns in space and over longer periods based on nominal meteorological measurements. Results show that a multiple linear regression on wind speed and humidity performed best and this is used to simulate snow sublimation spatially distributed on Yala Glacier for the winter season 2016-2017. Averaged over an entire winter and over the entire glacier surface, sublimation plays a crucial role in the high altitude water balance and in the mass balance of glaciers. Future research should focus on quantifying the role of sublimation at the catchment scale, the development of larger scale parametrizations and efficient measurement strategies to validate the results.

  6. Testing the effect of the Himalayan mountains as a physical barrier to gene flow in Hippophae tibetana Schlect. (Elaeagnaceae.

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    La Qiong

    Full Text Available Hippophae tibetana is a small, dioecious wind-pollinated shrub endemic to the Tibetan-Qinghai Plateau. It is one of the shrubs that occur at very high elevations (5250 m a.s.l.. The Himalayan mountains provides a significant geographical barrier to the Qinghai-Tibetan Plateau, dividing the Himalayan area into two regions with Nepal to the south and Tibet to the north. There is no information on how the Himalayan mountains influence gene flow and population differentiation of alpine plants. In this study, we analyzed eight nuclear microsatellite markers and cpDNA trnT-trnF regions to test the role of the Himalayan mountains as a barrier to gene flow between populations of H. tibetana. We also examined the fine-scale genetic structure within a population of H. tibetana on the north slope of Mount (Mt. Everest. For microsatellite analyses, a total of 241 individuals were sampled from seven populations in our study area (4 from Nepal, 3 from Tibet, including 121 individuals that were spatially mapped within a 100 m × 100 m plot. To test for seed flow, the cpDNA trnT-trnF regions of 100 individuals from 6 populations (4 from Nepal, 2 from Tibet were also sequenced. Significant genetic differentiation was detected between the two regions by both microsatellite and cpDNA data analyses. These two datasets agree about southern and northern population differentiation, indicating that the Himalayan mountains represent a barrier to H. tibetana limiting gene flow between these two areas. At a fine scale, spatial autocorrelation analysis suggests significant genetic structure within a distance of less than 45 m, which may be attributed mainly to vegetative reproduction and habitat fragmentation, as well as limited gene flow.

  7. Greisen deposits associated to carboniferous post-orogenic granites with mineralization potential, Sierra de Fiambala, Catamarca, Argentina

    International Nuclear Information System (INIS)

    Fogliata, A. S.; Rubinstein, N. R.; Avila, J. C.; Baez, M.

    2008-01-01

    The Fiambala range is located in the central south part of the province of Catamarca, Western Sierras Pampeanas, Argentina. It is largely conformed by Precambrian metamorphic rocks, a Cambrian granitic intrusive, Ordovician basic and ultra basic rocks and epi zonal Carboniferous granites (Los Ratones, El Salto and Ayacucho Granites). The Carboniferous granites are sub alkaline, weakly peraluminous, high silica (except for the porphyritic facies of Los Ratones granite) and moderately enriched in K. Contents of trace elements and REE indicate that El S alto and Ayacucho granites and the granular facies of Los Ratones granite have characteristics of evolved and differentiated granite associated with hydrothermal systems. The variations of trace elements, particularly Sn, W, U, Rb, Ba, Zr and Sr suggest that they correspond to granites with mineralization potential. Genetically linked to these granites there are Sn, W, U and minor base metals greisen deposits. The hydrothermal process that yield to these deposits involved two main alteration stages, beginning with alkali metasomatism follow by greissenization. According to the isotopic ages the hydrothermal processes postdate about 1 Ma the magmatic activity. The analyses of the granites and the associated greisen deposits confirm that the post orogenic carboniferous magmatism is the major metallogenetic control of the ore deposits from the studied area. This metallogenetic control could be a useful tool in prospecting similar deposits in the rest of the Western Sierras Pampeanas. (Author)

  8. Late Cenozoic Climate Change and its Implications on the Denudation of Orogen Syntaxes

    Science.gov (United States)

    Mutz, Sebastian; Ehlers, Todd

    2017-04-01

    The denudation history of active orogens is often interpreted in the context of modern climate gradients. Despite the influence of climatic conditions on erosion rates, information about paleoclimate evolution is often not available and thus not considered when denudation histories are interpreted. In this study, we analyze output from paleoclimate simulations conducted with ECHAM5-wiso at T159 (ca. 80x80km) resolution. Specifically, we analyze simulations of pre-industrial (PI, pre-1850), Mid-Holocene (MH, ca. 6ka), Last Glacial Maximum (LGM, ca. 21ka) and Pliocene (PLIO, ca. 3ka) climates and focus on a selection of orogen syntaxes as study regions (e.g. Himalaya, SE Alaska, Cascadia, and Central Andes). For the selected region, we carry out a cluster analysis using a hybrid of hierarchical and k-means clustering procedures using mean annual temperature (MAT), temperature amplitude, mean annual precipitation (MAP), precipitation amplitude and u-wind and v-wind in different months to provide a general overview of paleoclimates in the study regions. Additionally, we quantify differences between paleoclimates by applying two-group linear discrimination analyses to the simulation output for a similar selection of variables. Results indicate the largest differences to the PI climate are observed for the LGM and PLIO climates in the form of widespread cooling and reduced precipitation in the LGM and warming and enhanced precipitation during the PLIO. These global trends can be observed for most locations in the investigated areas, but the strength varies regionally and the trends in precipitation are less uniform than trends in temperatures. The LGM climate shows the largest deviation in annual precipitation from the PI climate, and shows enhanced precipitation in the temperate Andes, and coastal regions for both SE Alaska and the US Pacific Northwest Pacific. Furthermore, LGM precipitation is reduced in the western Himalayas and enhanced in the eastern Himalayas

  9. Lithologically controlled strength variation and the Himalayan megathrust geometry: an analogue modeling approach

    Science.gov (United States)

    Ghosh, Subhajit; Das, Animesh; Bose, Santanu; Mandal, Nibir

    2017-04-01

    A moment magnitude (Mw) 7.8 earthquake associated with a Mw 7.3 aftershock hit the Gorkha region near Kathmandu, Nepal on April 25, 2015. The rupture propagated eastward for about 140 km and caused thousands of deaths. The focal mechanism of the Gorkha earthquake shows thrust sense over the mid-crustal steeply dipping ramp on the basal décollement known as the Main Himalayan Thrust (MHT). The MHT is the largest and fastest slipping continental megathrust over which the southward tapering Himalayan thrust wedge similar to the accretionary wedges is moving. The MHT ramps up to the surface beneath the Siwalik group of rocks as the Main Frontal Thrust (MFT). Below the MFT the basal décollement is flat until it reaches the mid-crustal ramp ( 20°) below the Himalayan klippen and then again it becomes flat. This geometry of the décollement is consistent with the balanced cross sections, microseismic data, magnetotelluric images, INDEPTH seismic reflection profile, present day stress distribution and fits well with the prominent topographic break (physiographic transition) in the Lesser Himalaya. Lithologically stratified sedimentary sequences in the upper crust are mechanically heterogeneous. It has been long known that the mechanical properties of the stratigraphic succession influence the resultant structural architecture of the fold and thrust belts. The rheologically weak stratigraphic horizon generally contains the basal décollement due to its relatively low frictional strength. Hence, any vertical or lateral change in frictional property may control the effective strength and the positions of the décollement in space. In the present study, we used non-cohesive sand and mica dust layers as analogue materials for simulating the strong and weak layers respectively in the sandbox apparatus. Experimental results with relatively high basal friction (μ=0.46) show that such a weak horizon at a shallow depth perturbs the sequential thrust progression, and forces a

  10. Status, ecology, and conservation of the Himalayan griffon Gyps himalayensis (Aves, Accipitridae) in the Tibetan plateau.

    Science.gov (United States)

    Lu, Xin; Ke, Dianhua; Zeng, Xianhai; Gong, Guohong; Ci, Ren

    2009-05-01

    The dramatic population crashes of 3 species of Gyps vulture have raised concerns about the status of their lesser-known congeners. Among these is the Himalayan griffon, G. himalayensis, an iconic vulture of the Tibetan plateau. The continued existence of this scavenger has not only ecological but also cultural implications because of their unique role in the centuries-old sky burial tradition that is followed by nearly 5 million Tibetan people. A lack of baseline information of the Himalayan griffon limits our ability to take conservation measures. The presented data, which were collected during 1996 and 2004 to 2007, indicate that this species is still widespread throughout the plateau and has not experienced a major population decline, likely as a result of protection by Tibetan Buddhism and limited disturbances from human activities largely due to the remoteness of the plateau. Both site and road counts showed that open meadow habitats had the highest griffon abundance, followed by alpine shrub and forest habitats. Estimates based on road transect counts showed that 229,339 Himalayan griffons (+/- 40,447) occupy the 2.5 million km2 Tibetan plateau. In contrast, the maximum carrying capacity of the plateau, on the basis of the total biomass of potential food resources, is 507,996 griffons, with meadow habitats accounting for about 76% of the total population. Griffons depend largely on livestock carcasses for food and forage in groups averaging 5.5 (range 1-100) individuals. Domestic yaks provide about 64% of the griffons' diet, while wild ungulates and human corpses provide 1% and 2%, respectively. Compared with its lowland congeners, this, the only high-elevation Gyps species, had both low population density and small group size, a likely response to the harsh environmental conditions. Although griffon abundance appears relatively stable in their fairly pristine environment, precautionary measures, including investigation of threats, monitoring of population

  11. Vertical profile of aerosols in the Himalayan region using an ultralight aircraft platform

    Science.gov (United States)

    Singh, A.; Mahata, K.; Rupakheti, M.; Lawrence, M. G.; Junkermann, W.

    2017-12-01

    Indo-gangetic plain (IGP) and Himalayan foothills have large spatial and temporal heterogeneity in aerosols characteristics. Regional meteorology around 850-500 mb plays an important role in the transformation and transportation of aerosols from west Asia to IGP, into Himalayan foothill, as well to high-altitude region of the Himalayas. In order to quantify the vertical and horizontal variation of aerosol properties in the Himalayan , an airborne campaign was carried out in the Pokhara Valley/Nepal (83°50'-84°10' E, 25°7'-28°15' N, 815 masl ) in two phases: test flights during May 2016 and an intensive airborne sampling flight in December-January 2017. This paper provides an overview of airborne measurement campaign from the first phase of measurements in May 2016. A two-seater microlight aircraft (IKARUS C 42) was used as the aerial platform. This was deemed the feasible option in Nepal for an aerial campaign; technical specification of the aircraft include an approximately 6 hrs of flying time, short-take off run, > 100 kgs of payload, suitable for spiral upward and downward profiling. The instrument package consist of GRIMM 1.108 for particle size distribution from 0.3 to 20 um at 6 seconds time resolution, and TSI CPC 3375 for total ultrafine particle (UFP) concentration at 1 s. The package also includes a Magee Scientific Aethalometer (AE42) for aerosol absorption at seven different wavelengths. Meteorological parameters include temperature and dew point at a sampling rate of 1 Hz or higher. The paper provides a snapshot of observed vertical profile (from 800 to 4500masl) of aerosols size, number and black carbon over one of populated mountain valley in Nepal during the pre-monsoon season. During the airborne measurement, local fires- mostly agriculture burn were observed, however no large scale forest fire was captured. Sharp morning and afternoon gradients were observed in the vertical profile for aerosol number and size, mostly dominated by 2000 masl

  12. The depositional setting of the Late Quaternary sedimentary fill in southern Bannu basin, Northwest Himalayan fold and thrust belt, Pakistan

    KAUST Repository

    Farid, Asam M.

    2014-07-10

    Geostatistical variogram and inversion techniques combined with modern visualization tools have made it possible to re-model one-dimensional electrical resistivity data into two-dimensional (2D) models of the near subsurface. The resultant models are capable of extending the original interpretation of the data to depict alluvium layers as individual lithological units within the 2D space. By tuning the variogram parameters used in this approach, it is then possible to visualize individual lithofacies and geomorphological features for these lithologic units. The study re-examines an electrical resistivity dataset collected as part of a groundwater study in an area of the Bannu basin in Pakistan. Additional lithological logs from boreholes throughout the area have been combined with the existing resistivity data for calibration. Tectonic activity during the Himalayan orogeny uplifted and generated significant faulting in the rocks resulting in the formation of a depression which subsequently has been filled with clay-silt and dirty sand facies typical of lacustrine and flood plain environments. Streams arising from adjacent mountains have reworked these facies which have been eroded and replaced by gravel-sand facies along channels. It is concluded that the sediments have been deposited as prograding fan shaped bodies, flood plain, and lacustrine deposits. Clay-silt facies mark the locations of paleo depressions or lake environments, which have changed position over time due to local tectonic activity and sedimentation. The Lakki plain alluvial system has thus formed as a result of local tectonic activity with fluvial erosion and deposition characterized by coarse sediments with high electrical resistivities near the mountain ranges and fine sediments with medium to low electrical resistivities towards the basin center. © 2014 Springer International Publishing Switzerland.

  13. Spatial and temporal characterization of progressive deformation during orogenic growth: Example from the Fuegian Andes, southern Argentina

    Science.gov (United States)

    Torres Carbonell, Pablo J.; Cao, Sebastián J.; Dimieri, Luis V.

    2017-06-01

    Superposed structural fabrics in the easternmost Fuegian Andes reveal two distinct, non-coaxial deformation phases across the transition from the orogenic core to the thrust-fold belt. Each phase is characterized by different metamorphic conditions and consistently different orientations, which allow the structural correlation between the orogenic core and the internal thrust-fold belt. The first deformation phase was coeval with regional metamorphism reaching upper greenschist facies, and featured simple shear deformation of the basement (Paleozoic and Jurassic) and cover (Cretaceous) in the top of the underthrusting South American plate. The second phase developed during collision of the orogenic wedge with the Río Chico Arch, a promontory in the underthrusting plate; this phase was characterized by thrust sheet emplacement and formation of a crustal duplex, with rock uplift and consequent low to very-low grade metamorphism. Buttressing against the Río Chico Arch is responsible for the change in shortening orientation that distinguishes both phases.

  14. Strain partitioning at orogenic contacts during rotation, strike–slip and oblique convergence: Paleogene–Early Miocene evolution of the contact between the South Carpathians and Moesia

    NARCIS (Netherlands)

    Krézsek, Cs.; Lăpădat, A.; Matenco, L.C.; Arnberger, K.; Barbu, V.; Olaru, R.

    2013-01-01

    Oblique convergence accompanied by large-scale strike–slip deformation taking place between orogenic units is an inherent feature of highly bended mountain chains. Strain partitioning during subduction and collision takes place between differently oriented orogenic segments and creates contrasting

  15. Bio-prospecting Bacterial Diversity of Hot Springs in Northern Himalayan Region of India for Laccases.

    Science.gov (United States)

    Gupta, Vijaya; Gupta, Naveen; Capalash, Neena; Sharma, Prince

    2017-09-01

    Bacterial diversity of hot springs of northern Himalayan region of India was studied and explored for laccases, the multicopper enzymes applicable in a large number of industries due to their ability to utilize a wide range of substrates. 220 operational taxonomic units (OTUs) out of 5551 sequence reads for bacterial diversity and 3 OTUs out of 19 sequence reads for Laccase like multicopper oxidases (LMCOs) diversity were generated. Bacteroidetes (74.28%) was the most abundant phylum including genus Paludibacter (66.96%), followed by phylum Proteobacteria (24.53%) including genera Chitinilyticum (7.55%) and Cellvibrio (6.14%). In case of laccase diversity, three LMCO sequences showed affiliation with proteobacteria and one with two domain laccase from uncultivable bacteroidetes. LMCO sequences belonged to H and N families.

  16. MINING THE PROTEIN REPERTOIRE OF A HIMALAYAN SHRUB, HIPPOPHAE RHAMNOIDES FOR ANTIFREEZE PROTEINS

    Directory of Open Access Journals (Sweden)

    Bhavana Sharma

    2016-09-01

    Full Text Available Seabuckthorn (Hippophae rhamnoides, a cold desert shrub, can survive freezing temperature conditions and is considered as frost and drought tolerant. Earlier, antifreeze activity was reported in seabuckthorn seedlings grown under laboratory conditions. No reports are available on the cold hardiness of this huge bioresource available naturally in the Himalayan region. Detection of antifreeze activity in leaves and berries (splat assay and nanoliter osmometer confirmed the presence of putative antifreeze proteins (AFPs which may help in the survival of this plant under freezing conditions. Flower shaped ice crystals were observed in both leaves and berries while hexagonal ice crystals in seedlings indicated comparatively higher antifreeze activity in the wild parts. Splat assay results confirmed highest IRI activity in leaf (a 2.75 fold decrease in mean grain size of ice crystal after annealing followed by berry (with 1.75 fold decrease and least in the seedlings (with 1.5 fold decrease. Gel filtration chromatography resolved leaf fractions exhibited antifreeze activity in 34, 36 and 41 kDa while in berry fractions a 41 kDa polypeptide showed antifreeze activity. This is the first report showing presence of AFPs in (H. rhamnoides leaf and berry. Shotgun proteomic analysis using Q-Exactive Orbitrap High Resolution Mass Spectrometer and functional annotation of leaf and berry proteins revealed their association with primary, secondary metabolism, defence/stress, redox regulation, signalling and structural remodelling majority of which are affected during cold stress. Further purification of these AFPs could open gates for commercial utilization of this plant growing abundantly in Himalayan regions of India.

  17. Origin of unusual HREE-Mo-rich carbonatites in the Qinling orogen, China.

    Science.gov (United States)

    Song, Wenlei; Xu, Cheng; Smith, Martin P; Kynicky, Jindrich; Huang, Kangjun; Wei, Chunwan; Zhou, Li; Shu, Qihai

    2016-11-18

    Carbonatites, usually occurring within intra-continental rift-related settings, have strong light rare earth element (LREE) enrichment; they rarely contain economic heavy REE (HREE). Here, we report the identification of Late Triassic HREE-Mo-rich carbonatites in the northernmost Qinling orogen. The rocks contain abundant primary HREE minerals and molybdenite. Calcite-hosted fluid inclusions, inferred to represent a magmatic-derived aqueous fluid phase, contain significant concentrations of Mo (~17 ppm), reinforcing the inference that these carbonatitic magmas had high Mo concentrations. By contrast, Late Triassic carbonatites in southernmost Qinling have economic LREE concentrations, but are depleted in HREE and Mo. Both of these carbonatite types have low δ 26 Mg values (-1.89 to -1.07‰), similar to sedimentary carbonates, suggesting a recycled sediment contribution for REE enrichment in their mantle sources. We propose that the carbonatites in the Qinling orogen were formed, at least in part, by the melting of a subducted carbonate-bearing slab, and that 10 Ma younger carbonatite magmas in the northernmost Qinling metasomatized the thickened eclogitic lower crust to produce high levels of HREE and Mo.

  18. Magnetotelluric Imaging of the Lithosphere Across the Variscan Orogen (Iberian Autochthonous Domain, NW Iberia)

    Science.gov (United States)

    Alves Ribeiro, J.; Monteiro-Santos, F. A.; Pereira, M. F.; Díez Fernández, R.; Dias da Silva, Í.; Nascimento, C.; Silva, J. B.

    2017-12-01

    A new magnetotelluric (MT) survey comprising 17 MT soundings throughout a 30 km long N30°W transect in the Iberian autochthons domain of NW Iberia (Central Iberian Zone) is presented. The 2-D inversion model shows the resistivity structure of the continental crust up to 10 km depth, heretofore unavailable for this region of the Variscan Orogen. The MT model reveals a wavy structure separating a conductive upper layer underlain by a resistive layer, thus picturing the two main tectonic blocks of a large-scale D2 extensional shear zone (i.e., Pinhel shear zone). The upper layer represents a lower grade metamorphic domain that includes graphite-rich rocks. The lower layer consists of high-grade metamorphic rocks that experienced partial melting and are associated with granites (more resistive) emplaced during crustal thinning. The wavy structure is the result of superimposed crustal shortening responsible for the development of large-scale D3 folds (e.g., Marofa synform), later deflected and refolded by a D4 strike-slip shear zone (i.e., Juzbado-Penalva do Castelo shear zone). The later contribution to the final structure of the crust is marked by the intrusion of postkinematic granitic rocks and the propagation of steeply dipping brittle fault zones. Our study demonstrates that MT imaging is a powerful tool to understand complex crustal structures of ancient orogens in order to design future prospecting surveys for mineral deposits of economic interest.

  19. Cenozoic landforms and post-orogenic landscape evolution of the Balkanide orogen: Evidence for alternatives to the tectonic denudation narrative in southern Bulgaria

    Science.gov (United States)

    Gunnell, Y.; Calvet, M.; Meyer, B.; Pinna-Jamme, R.; Bour, I.; Gautheron, C.; Carter, A.; Dimitrov, D.

    2017-01-01

    Continental denudation is the mass transfer of rock from source areas to sedimentary depocentres, and is typically the result of Earth surface processes. However, a process known as tectonic denudation is also understood to expose deep-seated rocks in short periods of geological time by displacing large masses of continental crust along shallow-angle faults, and without requiring major contributions from surface erosion. Some parts of the world, such as the Basin and Range in the USA or the Aegean province in Europe, have been showcased for their Cenozoic tectonic denudation features, commonly described as metamorphic core-complexes or as supradetachment faults. Based on 22 new apatite fission-track (AFT) and 21 helium (AHe) cooling ages among rock samples collected widely from plateau summits and their adjacent valley floors, and elaborating on inconsistencies between the regional stratigraphic, topographic and denudational records, this study frames a revised perspective on the prevailing tectonic denudation narrative for southern Bulgaria. We conclude that conspicuous landforms in this region, such as erosion surfaces on basement-cored mountain ranges, are not primarily the result of Paleogene to Neogene core-complex formation. They result instead from "ordinary" erosion-driven, subaerial denudation. Rock cooling, each time suggesting at least 2 km of crustal denudation, has exposed shallow Paleogene granitic plutons and documents a 3-stage wave of erosional denudation which progressed from north to south during the Middle Eocene, Oligocene, Early to Middle Miocene, and Late Miocene. Denudation initially prevailed during the Paleogene under a syn-orogenic compressional regime involving piggyback extensional basins (Phase 1), but subsequently migrated southward in response to post-orogenic upper-plate extension driven by trench rollback of the Hellenic subduction slab (Phase 2). Rare insight given by the denudation pattern indicates that trench rollback

  20. Tectono-thermal evolution of the Atlas system - SW Morocco

    Science.gov (United States)

    Ruiz, G.; Negro, F.; Babault, J.; Foeken, J.; Stuart, F.; Kober, F.; Ivy-Ochs, S.

    2009-04-01

    In Morocco, the High and Middle Atlas of Morocco are intra-continental fold-thrust belts situated in the southern foreland of the Rif orogen. The High Atlas and its eastern continuation in Algeria and Tunisia is an ENE-WSW to E-W trending belt about 2000kms long and 100kms wide. It is a key natural laboratory because it 1) is the southern and westernmost expression of Alpine-Himalayan orogeny, and 2) encompasses Pre-Cambrian to recent evolution of the region. Phases of shortening and exhumation of this orogen remain however ill constrained and the few available quantitative, data do not allow the present-day high topography (over 4000m) to be explained. In order to put constrains on the recent orogenic growth of the Atlas system, we investigated the temperature-time history of rocks combining extensive low-temperature thermochronological analysis (Fission tracks and (U-Th)/He on zircon and apatite), and sub-recent denudation rates using cosmogenic Neon and Beryllium analysis. The target area is a NE-SW oriented transect between Marrakech and Igherm crossing the different structural segments of the western Atlas away from present-day fault systems. Results are much contrasted from one domain to the other: Pre-Cambrian bedrocks from the Anti-Atlas domain yield old Fission-Track ages on zircon (380-300 Ma), apatite (180-120 Ma) but also U-Th/He (150-110 Ma) still on apatite that are discussed in another contribution. U-Th/He ages on apatite are many from the High-Atlas (#>20) and much younger ranging between ~35 and 5 Ma. We performed a detailed vertical profile in the axial zone of the High-Atlas. Age-elevation relationship suggests that exhumation increased towards 1.0 km/my by the Late Miocene (~13-12 Ma). Further, continental series of Cretaceous age from the adjacent Sub-Atlas domains indicate total resetting to temperatures greater than 80°C suggesting that a post Cretaceous sedimentary pile of at least 3 kilometres in thickness is missing. The timing of the

  1. Transpressional folding and associated cross-fold jointing controlling the geometry of post-orogenic vein-type W-Sn mineralization: examples from Minas da Panasqueira, Portugal

    Science.gov (United States)

    Jacques, Dominique; Vieira, Romeu; Muchez, Philippe; Sintubin, Manuel

    2018-02-01

    The world-class W-Sn Panasqueira deposit consists of an extensive, subhorizontal vein swarm, peripheral to a late-orogenic greisen cupola. The vein swarm consists of hundreds of co-planar quartz veins that are overlapping and connected laterally over large distances. Various segmentation structures, a local zigzag geometry, and the occurrence of straight propagation paths indicate that they exploited a regional joint system. A detailed orientation analysis of the systematic joints reveals a geometrical relationship with the subvertical F2 fold generation, reflecting late-Variscan transpression. The joints are consistently orthogonal to the steeply plunging S0-S2 intersection lineation, both on the regional and the outcrop scale, and are thus defined as cross-fold or ac-joints. The joint system developed during the waning stages of the Variscan orogeny, when already uplifted to an upper-crustal level. Veining reactivated these cross-fold joints under the conditions of hydraulic overpressures and low differential stress. The consistent subperpendicular orientation of the veins relative to the non-cylindrical F2 hinge lines, also when having an inclined attitude, demonstrates that veining did not occur during far-field horizontal compression. Vein orientation is determined by local stress states variable on a meter-scale but with the minimum principal stress consistently subparallel to fold hinge lines. The conspicuous subhorizontal attitude of the Panasqueira vein swarm is thus dictated by the geometry of late-orogenic folds, which developed synchronous with oroclinal buckling of the Ibero-Armorican arc.

  2. From hyper-extended rifts to orogens: the example of the Mauléon rift basin in the Western Pyrenees (SW France)

    Science.gov (United States)

    Masini, E.; Manatschal, G.; Tugend, J.

    2011-12-01

    An integral part of plate tectonic theory is that the fate of rifted margins is to be accreted into mountain belts. Thus, rift-related inheritance is an essential parameter controlling the evolution and architecture of collisional orogens. Although this link is well accepted, rift inheritance is often ignored. The Pyrenees, located along the Iberian and European plate boundary, can be considered as one of the best places to study the reactivation of former rift structures. In this orogen the Late Cretaceous and Tertiary convergence overprints a Late Jurassic to Lower Cretaceous complex intracontinental rift system related to the opening of the North Atlantic. During the rifting, several strongly subsiding basins developed in the axis of the Pyrenees showing evidence of extreme crustal extension and even locale mantle exhumation to the seafloor. Although the exact age and kinematics of rifting is still debated, these structures have an important impact in the subsequent orogenic overprint. In our presentation we discuss the example of the Mauléon basin, which escaped from the most pervasive deformations because of its specific location at the interface between the western termination of the chain and the Bay of Biscay oceanic realm. Detailed mapping combined with seismic reflection, gravity data and industry wells enabled to determine the 3D rift architecture of the Mauléon basin. Two major diachronous detachment systems can be mapped and followed through space. The Southern Mauléon Detachment (SMD) develops first, starts to thin the crust and floors the Southern Mauléon sub-Basin (SMB). The second, the Northern Mauléon Detachment (SMD) is younger and controls the final crustal thinning and mantle exhumation to the north. Both constitute the whole Mauléon basin. Like at the scale of the overall Pyrenees, the reactivation of the Mauléon Basin increases progressively from west to east, which enables to document the progressive reactivation of an aborted hyper

  3. Devonian post-orogenic extension-related volcano-sedimentary rocks in the northern margin of the Tibetan Plateau, NW China: Implications for the Paleozoic tectonic transition in the North Qaidam Orogen

    Science.gov (United States)

    Qin, Yu; Feng, Qiao; Chen, Gang; Chen, Yan; Zou, Kaizhen; Liu, Qian; Jiao, Qianqian; Zhou, Dingwu; Pan, Lihui; Gao, Jindong

    2018-05-01

    The Maoniushan Formation in the northern part of the North Qaidam Orogen (NQO), NW China, contains key information on a Paleozoic change in tectonic setting of the NQO from compression to extension. Here, new zircon U-Pb, petrological, and sedimentological data for the lower molasse sequence of the Maoniushan Formation are used to constrain the timing of this tectonic transition. Detrital zircons yield U-Pb ages of 3.3-0.4 Ga with major populations at 0.53-0.4, 1.0-0.56, 2.5-1.0, and 3.3-2.5 Ga. The maximum depositional age of the Maoniushan Formation is well constrained by a youngest detrital zircon age of ∼409 Ma. Comparing these dates with geochronological data for the region indicates that Proterozoic-Paleozoic zircons were derived mainly from the NQO as well as the Oulongbuluk and Qaidam blocks, whereas Archean zircons were probably derived from the Oulongbuluk Block and the Tarim Craton. The ∼924, ∼463, and ∼439 Ma tectonothermal events recorded in this region indicate that the NQO was involved in the early Neoproterozoic assembly of Rodinia and early Paleozoic microcontinental convergence. A regional angular unconformity between Devonian and pre-Devonian strata within the NQO suggests a period of strong mountain building between the Oulongbuluk and Qaidam blocks during the Silurian, whereas an Early Devonian post-orogenic molasse, evidence of extensional collapse, and Middle to Late Devonian bimodal volcanic rocks and Carboniferous marine carbonate rocks clearly reflect long-lived tectonic extension. Based on these results and the regional geology, we suggest that the Devonian volcano-sedimentary rocks within the NQO were formed in a post-orogenic extensional setting similar to that of the East Kunlun Orogen, indicating that a major tectonic transition from compression to extension in these two orogens probably commenced in the Early Devonian.

  4. The Australasian frog family Ceratobatrachidae in China, Myanmar and Thailand: discovery of a new Himalayan forest frog clade

    OpenAIRE

    YAN, Fang; JIANG, Ke; WANG, Kai; JIN, Jie-Qiong; SUWANNAPOOM, Chatmongkon; LI, Cheng; Jens, V. VINDUM; Rafe, M. BROWN; CHE, Jing

    2016-01-01

    In an effort to study the systematic affinities and specieslevel phylogenetic relationships of the enigmatic anurans variably assigned to the genera Ingerana or Limnonectes (family Dicroglossidae), we collected new molecular sequence data for five species including four Himalayan taxa, Limnonectes xizangensis, Lim. medogensis, Lim. alpine, Ingerana borealis and one southeast Asian species, I. tasanae, and analyzed these together with data from previous studies involving other ostensibly relat...

  5. Constraining the timing of exhumation of the Eastern Himalayan syntaxis, from a study of the palaeo-Brahmaputra deposits, Siwalik Group, Arunachal Pradesh, India

    Science.gov (United States)

    Govin, Gwladys; Najman, Yani; van der Beek, Peter; Millar, Ian; Bernet, Matthias; Dupont-Nivet, Guillaume; Wijbrans, Jan; Gemignani, Lorenzo; Vögeli, Natalie; Huyghe, Pascale

    2015-04-01

    The evolution of Himalayan syntaxes is debated: they have been subjected to anomalously young (debated. Bedrock studies have been interpreted to imply rapid exhumation since either 3-4 Ma 2 or 8-10 Ma 3. However, the earlier history of the sampled region is removed by erosion and should be preserved in the sedimentary record. Bracciali et al 4 focused on distal detrital deposits and suggested a much more recent onset, during the Quaternary. A number of models have been proposed to explain the syntaxial evolution, supporting different controlling influences, from lithospheric channel flow, to tectonic-surface process interactions. Ductile extrusion of weak lower crust from beneath Tibet by "channel flow" 5 is a process that has been proposed to account for the outward growth of the plateau to the east 6, exhumation of the Higher Himalaya in the Miocene when coupled with high erosion rates, and could be responsible for rapid exhumation of the syntaxis 7. Ehlers and Bendick 8 propose that initiation of rapid and localised exhumation at subduction arc terminations may result from the 3D geometry imposed by subducting curved shells at such locations. Clark and Bilham 9 evoke a change in regional stress along the India-Asia-Burma plate boundary, perhaps due to the introduction of denser (oceanic and transitional crust) material into the eastern part of the boundary late in the orogen's history. Zeitler et al 10 consider that exhumation of the syntaxis is driven by surface processes. In order to understand how and why the syntaxis formed, this project aims to better constrain the onset of exhumation of the Namche Barwa using the proximal detrital record of material eroded from the syntaxis by the paleo-Brahmaputra. We analyse the sedimentary record to have access to earlier erosion products than preserved in the bedrock itself, in a proximal location. The Remi River section, in the Siwalik Group, is located directly downstream of the syntaxis and therefore is the most

  6. Tectonothermal evolution of the Triassic flysch in the Bayan Har Orogen, Tibetan plateau

    Science.gov (United States)

    Wang, Hejing; Rahn, Meinert; Zhou, Jian

    2018-01-01

    The Bayan Har Orogen comprises a major part of the "Qingzang-Dianxi fold region" in western China. It preserves important information of the tectono-thermal evolution covering the time span from the closure of the Paleo-Tethys Ocean up to the formation of the Himalayas. Low temperature metamorphic indicators, such as mineral assemblages, illite "crystallinity" (IC), chlorite "crystallinity" (CC), illite polytype, b-cell dimension of K-white micas, geothermometry of selected minerals were analyzed. The values of Kübler index (KI) of the Triassic flysch in the Bayan Har Orogen range from 0.23-1.63°Δ2θ while Árkai index (ÁI) in a range of 0.21-0.60°Δ2θ. Iso-thermal zones mapped with KI describe a pair of anchizones and an anchiregion within the Bayan Har Orogen: the "Giant Yushu Anchizone" in the southwest (extending > 750 km long and 100 km wide), the "Zaling-Eling-Lakes Anchizone" in the center (about 150 km long and 40 km wide) and the "Xing-Tong-Zhe Anchiregion" in the northeast (covering an area of roughly 60,000 km2). They are separated by diagenetic zones. Peak metamorphic conditions are estimated around 280-330 °C and a low to intermediate (N. New Hampshire) pressure type. A slight change with increasing then decreasing pressure was observed from SW to NE. The relationship between anchimetamorphic pattern of Triassic flysch and large-scale folds and faults indicates syn- to post structural metamorphism. Compression at the end of the Triassic, induced by the interaction of the Tarim, North China and Indian blocks caused the closure of the Paleo-Tethys Ocean and led to the folding of the Triassic flysch within the Paleo-Tethys Ocean basin. Anchimetamorphism may have been caused by crustal thickening of > 10 km due to an accretionary wedge setting and a temperature increase in those rocks due to burial. Such a regional metamorphic pattern would provide important information for reconstruction of palaeotectonic-palaeogeograph and the evolutionary history

  7. Partial melting of amphibolites in the Eastern Segment of the Sveconorwegian orogen, southern Sweden.

    Science.gov (United States)

    Brophy, E.; Hansen, E. C.; Möller, C.; Huffman, M.

    2017-12-01

    Mafic migmatites with amphibolitic melanosome and tonalitic leucosome are a common feature in continental collision orogenic zones. However, the anatexis of mafic rocks has received much less attention than anatexis in felsic, intermediate or pelitic compositions. We examined mafic migmatites along a traverse within the Eastern Segment of the 1.14-0.9 Ga Sveconorwegian orogen, between Forsheda and Fegen southern Sweden. This traverse occurs in the center of a >150 km metamorphic transition from sub-greenschist facies in the east to high-pressure granulite and eclogite facies in the west (Möller and Andersson, unpublished metamorphic map). The Eastern Segment is a parautochthonous belt made up of rocks of the Fennoscandian shield that were deformed and metamorphosed during the Sveconorwegian orogeny. Within the traverse amphibolite bodies occur within migmatitic felsic to intermediate orthogneisses. The first appearance of tonalitic leucosome in amphibolite was observed towards the eastern edge of the traverse and continued to occur sporadically westward ranging in abundance (by outcrop area) from 0 to 25 %. The mineral assemblage in amphibolite is hbl + plag ( An30) + qtz + bt ± grt ± ilm ± ttn ± py ± SO2-rich scp. No examples of peritectic pyroxene associated with leucosome were found. The lack of peritectic pyroxene suggests that a water-rich phase was present at the onset of anatexis. The highly variable amount of leucosome further suggests that the amount of melt generated was determined by the amount of water available. Together these suggest that partial was driven by the local influx of a water-rich fluid. In the higher grade portions further west migmatitic amphibolite with tonalitic leucosome occurs in two varieties: one with peritectic pyroxene and relatively small amounts of leucosome, interpreted as forming by water-undersaturated dehydration melting, and another without peritectic pyroxene and with larger amounts of leucosome which is interpreted

  8. Origin of allanite in gneiss and granite in the Dabie orogenic belt, Central East China

    Science.gov (United States)

    Guo, Haihao; Xiao, Yilin; Xu, Lijuan; Sun, He; Huang, Jian; Hou, Zhenhui

    2017-03-01

    Allanite is a common accessory mineral phase, representing an important carrier of rare earth elements, Th, U, Sr and other trace elements in most continental rocks. As Th and U can be incorporated into the allanite lattice, the mineral is a good geochronological tool for constraining geological events. Moreover, the trace element features δEu, Th/U ratio and common lead content of allanite are indicators of the forming conditions. Allanite and coexisting epidote-group minerals are abundant in ultrahigh-pressure (UHP) metamorphic rocks from the Dabie-Sulu orogen in central East China. However, if these minerals formed in the Neoproterozoic as magmatic phases, or in the Triassic as metamorphic phases is a matter of long-standing controversy. We report major and trace element analyses of whole rocks, allanite and coexisting epidote-group minerals, together with U-Th-Pb isotopic compositions of allanite in UHP gneiss from the Dabie-Sulu orogen, and allanite in the adjacent Jingshan granite. The granite is emplaced along the southeastern margin of the North China Craton and considered a product of partial melting of the subducted Dabie-Sulu gneiss. Trace elements (low Th/U and La/Sm, high δEu and high Sr) and high common lead concentrations indicate a metamorphic origin of allanite-epidote in the UHP gneiss. On the other hand, coarse-grained allanite from the Jingshan granite shows a corrosion core and a magmatic rim with common 208Pb up to 70% in the core and less than 30% in the rim. The allanite cores are of peritectic and the rims of magmatic origin with ages of ∼160 Ma, consistent with the granite crystallization age. In combination with previous studies, we conclude that the allanite of the Jingshan granite has form from the subducted and remolten Dabie-Sulu gneiss. Allanite records Triassic UHP metamorphic ages as well as Jurassic peritectic-magmatic ages as a part of the evolution of the Dabie-Sulu orogen.

  9. Build-up of the Himalayan avifauna through immigration: a biogeographical analysis of the Phylloscopus and Seicercus warblers.

    Science.gov (United States)

    Johansson, Ulf S; Alström, Per; Olsson, Urban; Ericson, Per G P; Sundberg, Per; Price, Trevor D

    2007-02-01

    The Himalayan mountain range is one of the most species-rich areas in the world, harboring about 8% of the world's bird species. In this study, we compare the relative importance of immigration versus in situ speciation to the build-up of the Himalayan avifauna, by evaluating the biogeographic history of the Phylloscopus/Seicercus warblers, a speciose clade that is well represented in Himalayan forests. We use a comprehensive, multigene phylogeny in conjunction with dispersal-vicariance analysis to discern patterns of speciation and dispersal within this clade. The results indicate that virtually no speciation has occurred within the Himalayas. Instead, several speciation events are attributed to dispersal into the Himalayas followed by vicariance between the Himalayas and China/Southeast Asia. Most, perhaps all, of these events appear to be pre-Pleistocene. The apparent lack of speciation within the Himalayas stands in contrast to the mountain-driven Pleistocene speciation suggested for the Andes and the East African mountains.

  10. Zircon (U-Th)/He Thermochronometric Constraints on Himalayan Thrust Belt Exhumation, Bedrock Weathering, and Cenozoic Seawater Chemistry

    Science.gov (United States)

    Colleps, Cody L.; McKenzie, N. Ryan; Stockli, Daniel F.; Hughes, Nigel C.; Singh, Birendra P.; Webb, A. Alexander G.; Myrow, Paul M.; Planavsky, Noah J.; Horton, Brian K.

    2018-01-01

    Shifts in global seawater 187Os/188Os and 87Sr/86Sr are often utilized as proxies to track global weathering processes responsible for CO2 fluctuations in Earth history, particularly climatic cooling during the Cenozoic. It has been proposed, however, that these isotopic records instead reflect the weathering of chemically distinctive Himalayan lithologies exposed at the surface. We present new zircon (U-Th)/He thermochronometric and detrital zircon U-Pb geochronologic evidence from the Himalaya of northwest India to explore these contrasting interpretations concerning the driving mechanisms responsible for these seawater records. Our data demonstrate in-sequence southward thrust propagation with rapid exhumation of Lesser Himalayan strata enriched in labile 187Os and relatively less in radiogenic 87Sr at ˜16 Ma, which directly corresponds with coeval shifts in seawater 187Os/188Os and 87Sr/86Sr. Results presented here provide substantial evidence that the onset of exhumation of 187Os-enriched Lesser Himalayan strata could have significantly impacted the marine 187Os/188Os record at 16 Ma. These results support the hypothesis that regional weathering of isotopically unique source rocks can drive seawater records independently from shifts in global-scale weathering rates, hindering the utility of these records as reliable proxies to track global weathering processes and climate in deep geologic time.

  11. Lateral structure variations and transient swarm revealed by seismicity along the Main Himalayan Thrust north of Kathmandu

    Science.gov (United States)

    Hoste-Colomer, R.; Bollinger, L.; Lyon-Caen, H.; Burtin, A.; Adhikari, L. B.

    2017-09-01

    The midcrustal seismicity along the Main Himalayan Thrust in Nepal presents lateral variations along the rupture of the 2015 Gorkha earthquake. In order to resolve these variations, we relocate the seismicity north of Kathmandu, during a period well covered by the Nepal National Seismological Network, using a double-difference algorithm. The 550 relocated events highlight a complex pattern of clustered seismicity within the unstable-stable transition zone. Part of the seismicity is densely clustered on a southward dipping plane which ruptured on January 31st 1997 (ML = 5.8), activating a backthrust with a geometry consistent with the centroid moment tensor of this event calculated in this study. At its eastern end, the midcrustal cluster is offset by 20 km to the south suggesting the presence of a tear fault. The analysis of the time sequence allows constraining a scenario involving stress transfer between these local midcrustal structures, beginning more than one month before the 1997 main shock. The temporal evolution of the seismicity is strikingly similar for two other transient seismic swarm episodes which developed hundreds of kilometers apart along the Main Himalayan Thrust at the same time. The local stress field appears responsible for the higher sensitivity of these regions to subtle strain transients developing along the Main Himalayan Thrust.

  12. Age and kinematics of ductile deformation in the Cerro Durazno area, NW Argentina: Significance for orogenic processes operating at the western margin of Gondwana during Ordovician - Silurian times

    Science.gov (United States)

    Wegmann, Maja I.; Riller, Ulrich; Hongn, Fernando D.; Glodny, Johannes; Oncken, Onno

    2008-07-01

    The Cerro Durazno Pluton belongs to a suite of Paleozoic granitoid intrusions in NW-Argentina, that are central for understanding the tectonic setting of the western margin of Gondwana in Ordovician and Silurian times. The pluton and its host rocks were tectonically overprinted by metamorphic mineral shape fabrics formed under middle greenschist-facies metamorphic conditions and associated with the nearby Agua Rosada Shear Zone. Kinematic analysis of the shear zone based on the geometric relationship between individual segments of the shear plane and principal axes of mineral fabric ellipsoids indicates reverse-sense of shear with a minor component of left-lateral displacement. This is compatible with the kinematics of other ductile deformation zones in this area, collectively forming a network, which accomplished orogen-parallel extension in addition to vertical thickening. Using the Rb-Sr isotopic system, an undeformed pegmatite dike of the Cerro Durazno Pluton was dated at 455.8 ± 3.6 Ma and mineral fabrics of the Agua Rosada Shear Zone formed at middle greenschist-facies metamorphism gave deformation ages of 437.0 ± 3.8 Ma and ⩽428.4 ± 4.5 Ma. Thus, tectonic overprint at low metamorphic grade occurred about 20-30 Ma after terminal magmatism in the Cerro Durazno area. Our data from the Cerro Durazno area and regional considerations suggest that the western margin of Gondwana was characterized by orogen-parallel extension in addition to crustal thickening as well as episodes of magmatism and ductile deformation that varied greatly in time and space.

  13. Carboniferous rifted arcs leading to an archipelago of multiple arcs in the Beishan-Tianshan orogenic collages (NW China)

    Science.gov (United States)

    Tian, Zhonghua; Xiao, Wenjiao; Windley, Brian F.; Zhang, Ji'en; Zhang, Zhiyong; Song, Dongfang

    2017-10-01

    The Beishan and East Tianshan Orogenic Collages in the southernmost Central Asian Orogenic Belt (CAOB) record the final stages of evolution of the Paleo-Asian Ocean. These collages and their constituent arcs have an important significance for resolving current controversies regarding their tectonic setting and age, consequent accretionary history of the southern CAOB, and the closure time of the Paleo-Asian Ocean. In this paper, we present our work on the southern Mazongshan arc and the northern Hongyanjing Basin in the Beishan Orogenic Collage (BOC), and our comparison with the Bogda arc and associated basins in the East Tianshan Orogenic Collage. Field relationships indicate that the Pochengshan fault defines the boundary between the arc and basin in the BOC. Volcanic rocks including basalts and rhyolites in the Mazongshan arc have bimodal calc-alkaline characteristics, an enrichment in large ion lithophile elements such as Rb, Ba, and Pb and depletion in high field-strength elements (e.g., Nb and Ta), which were probably developed in a subduction-related tectonic setting. We suggest that these bimodal calc-alkaline volcanic rocks formed in rifted arcs instead of post-orogenic rifts with mantle plume inputs. By making detailed geochemical comparisons between the Mazongshan arc and the Bogda arc to the west, we further propose that they are similar and both formed in arc rifts, and helped generate a Carboniferous archipelago of multiple arcs in the southern Paleo-Asian Ocean. These data and ideas enable us to postulate a new model for the tectonic evolution of the southern CAOB.

  14. Deep origin and hot melting of an Archaean orogenic peridotite massif in Norway.

    Science.gov (United States)

    Spengler, Dirk; van Roermund, Herman L M; Drury, Martyn R; Ottolini, Luisa; Mason, Paul R D; Davies, Gareth R

    2006-04-13

    The buoyancy and strength of sub-continental lithospheric mantle is thought to protect the oldest continental crust (cratons) from destruction by plate tectonic processes. The exact origin of the lithosphere below cratons is controversial, but seems clearly to be a residue remaining after the extraction of large amounts of melt. Models to explain highly melt-depleted but garnet-bearing rock compositions require multi-stage processes with garnet and clinopyroxene possibly of secondary origin. Here we report on orogenic peridotites (fragments of cratonic mantle incorporated into the crust during continent-continent plate collision) from Otrøy, western Norway. We show that the peridotites underwent extensive melting during upwelling from depths of 350 kilometres or more, forming a garnet-bearing cratonic root in a single melting event. These peridotites appear to be the residue after Archaean aluminium depleted komatiite magmatism.

  15. 40Ar-39Ar method for age estimation: principles, technique and application in orogenic regions

    International Nuclear Information System (INIS)

    Dalmejer, R.

    1984-01-01

    A variety of the K-Ar method for age estimation by 40 Ar/ 39 Ar recently developed is described. This method doesn't require direct analysis of potassium, its content is calculated as a function of 39 Ar, which is formed from 39 K under neutron activation. Errors resulted from interactions between potassium and calcium nuclei with neutrons are considered. The attention is paid to the technique of gradual heating, used in 40 Ar- 39 Ar method, and of obtaining age spectrum. Aplicabilities of isochronous diagram is discussed for the case of presence of excessive argon in a sample. Examples of 40 Ar- 39 Ar method application for dating events in orogenic regions are presented

  16. EARLY STAGE OF THE CENTRAL ASIAN OROGENIC BELT BUILDING: EVIDENCES FROM THE SOUTHERN SIBERIAN CRATON

    Directory of Open Access Journals (Sweden)

    D. P. Gladkochub

    2017-01-01

    Full Text Available The origin of the Central-Asian Orogenic Belt (CAOB, especially of its northern segment nearby the southern margin of the Siberian craton (SC is directly related to development and closure of the Paleo-Asian Ocean (PAO. Signatures of early stages of the PAO evolution are recorded in the Late Precambrian sedimentary successions of the Sayan-Baikal-Patom Belt (SBPB on the southern edge of SC. These successions are spread over 2000 km and can be traced along this edge from north-west (Sayan area to south-east (Baikal area and further to north-east (Patom area. Here we present the synthesis of all available and reliable LA-ICP-MS U-Pb geochronological studies of detrital zircons from these sedimentary successions.

  17. Strain histories from the eastern Central Range of Taiwan: A record of advection through a collisional orogen

    Science.gov (United States)

    Mondro, Claire A.; Fisher, Donald; Yeh, En-Chao

    2017-05-01

    In the eastern Central Range of Taiwan there is a regional variation in the orientation of maximum finite stretch across the slate belt, with down-dip maximum stretch found in the western Central Range and along-strike maximum stretch in the eastern Central Range. Incremental strain histories from syntectonic fibers in pyrite pressure shadows indicate a progressive change in extension direction from down dip to along strike during deformation, there is a corresponding temporal variation in stretching direction shown in samples from the eastern edge of the Central Range, a pattern that mimics the regional west-to-east spatial variation. These observed temporal and spatial strain distributions are used to evaluate the kinematics associated with slaty cleavage development during advection through the Taiwan orogenic system. The subduction zone beneath the island of Taiwan is influenced by two types of obliquity that have the potential to generate the observed along-strike stretching. First, the plate motion vector of the Philippine Sea plate relative to the Eurasian plate is slightly oblique to the regional strike of the mountain range, which could result in partitioning of strike slip shearing into the interior of the collision. Second, the north-south Luzon volcanic arc on the Philippine Sea Plate is obliquely oriented relative to the northeast-southwest edge of the Eurasian continental margin, which could result in lateral extrusion of the ductile core of the range. Incremental strain histories in cleavage-parallel samples represent a time-for-space equivalence where the stretching direction is fixed relative to the position within the mountain belt architecture (e.g., the topographic divide), and temporal variations in the eastern central Range reflect lateral advection through the strain field in response to accretionary and erosional fluxes. Incremental strain histories in cleavage perpendicular samples show both clockwise and counter-clockwise rotation of

  18. High-resolution multicomponent seismic imaging for VMS deposits within the Paleoproterozoic Flin Flon Belt, Trans-Hudson Orogen, Canada

    Science.gov (United States)

    Malinowski, M.; White, D.

    2008-12-01

    The Flin Flon-Glennie complex (Trans-Hudson Orogen) hosts the largest Paleoproterozoic volcanogenic massive sulphide (VMS) district in the world. The main deposits of the Flin Flon camp have mineral compositions of predominantly pyrite, pyrrhotite, sphalerite, and chalcopyrite. All of these minerals are characterised by high acoustic impedances relative to typical host rocks, thus making them excellent candidates for seismic exploration. In a concerted effort to support exploration for new ore deposits in the vicinity of Flin Flon and surrounding region, a program of seismic investigations has been implemented as part of the Targetted Geoscience Initiative-3 (TGI-3) Saskatchewan-Manitoba project. This project is a joint Federal-Provincial effort led by the Geological Survey of Canada with active participation by Hudson Bay Mining and Smelting Ltd. Rock property measurements, downhole geophysical logging and vertical seismic profiles acquired in advance of the main seismic survey demonstrated the expected reflectivity of the mining camp geology. The principle seismic survey was conducted during May-September, 2007 and comprised a total of 75 km of high- resolution 2D seismic profiles and a 3D survey covering approximately 10 km2. Seismic imaging in the Flin Flon area poses significant challenges due to the complex crystalline geology, the location of the imaging targets beneath an active town and operational mine site, and the highly variable terrain. Data were recoreded using IO System IV digital vector (3-component) accelerometers, spaced at 5 m intervals (for 2D survey) with recording times of 4 s. Seismic sources spaced at 20 m intervals included Vibroseis and dynamite sources on land, and an airgun for lake areas. The results of processing the vertical-component data for P-wave reflections reveal subhorizontal reflectivity associated mainly with the Missi metasedimentary complex and steeply dipping reflectivity associated with the polydeformed volcanic rocks

  19. U-Th-Ra variations in Himalayan river sediments (Gandak river, India): Weathering fractionation and/or grain-size sorting?

    Science.gov (United States)

    Bosia, Clio; Chabaux, François; Pelt, Eric; France-Lanord, Christian; Morin, Guillaume; Lavé, Jérôme; Stille, Peter

    2016-11-01

    Understanding the origin of U-Th-Ra variations in the Ganga river sediments is a prerequisite for correctly using U-series nuclides to constrain the sediment transport times in Himalayan rivers. For this purpose, U, Th, and Ra concentrations, along with 238U-234U-230Th-226Ra radioactive disequilibria, were analyzed in bank, bedload and suspended sediments from the Gandak river, one of the main tributaries of the Ganga river. The data confirm that U and Th budgets of the Himalayan sediments are significantly influenced by minor resistant minerals, such as zircon, garnet and Ti-bearing minerals, the dissolution of which required the use of a high-pressure acid digestion process. Most importantly, the results indicate that the variations in (238U/232Th) and (230Th/232Th) activity ratios and 238U-234U-230Th-226Ra disequilibria in sediments along the river alluvial plain mainly reflect modifications in the mineralogical and grain-size compositions rather than the degree of weathering during transport. The (238U/232Th) and (230Th/232Th) activity ratios in the bank and bed sediments are related to variations in the minor primary minerals strongly enriched in U and Th (i.e., zircon, REE-bearing minerals and Ti-bearing minerals), whereas the activity ratios in the suspended load are related to variations in the proportions of clay, Fe-oxyhydroxides and the silt-sand fraction, which contains U- and Th-bearing minor minerals. The data also indicate that 238U-234U-230Th-226Ra disequilibria are strongly influenced by secondary mineral phases: the 230Th budget is likely mainly controlled by Fe-oxyhydroxides, and the 226Ra budget is likely mainly controlled by clay minerals. Therefore, the variations in the 238U-234U-230Th-232Th system in the sediments of the Gandak river cannot simply be interpreted as the result of fractionation due to chemical transformation of the bulk sediment during its transport within the alluvial plain and/or the result of radioactive decay. Consequently

  20. The Pan-African Damara Orogen of South West Africa/Namibia

    International Nuclear Information System (INIS)

    Miller, R.McG.

    1983-01-01

    The structural grain of the Damara orogen points to a reversal of spreading and to north-westward subduction of the African cratons below a South American craton and of the Kalahari Craton below the Congo Craton. D 1 recumbent folding was followed by intrusion of 650 m.y.-old granitic rocks, uplift and erosion and deposition of a northern molasse. D 2 deformation in the coastal arm marked the continental collision phase in this region. The final, large-scale deformational event in this region caused westward-vergent back folding which was followed by intrusion of 570 m.y.-old post-tectonic granites. In the Central Zone, widespread intrusion of 550 m.y.-old, syntectonic granites and extrusion of their volcanic equivalents in a 150 km-wide, high-temperature-low-pressure zone along the leading edge of the Congo Craton was accompanied by uplift, erosion and the deposition of K-rich greywackes as a fore-arc sequence above the earlier, spreading-phase deposits in the closing Southern Zone ocean. Sedimentological aspects of the Damara along the southern margin of the orogen suggest that the lower Nama Group, which contains a unique Ediacara fauna and was derived from easterly sources, was deposited between about 650 and 550 m.y. ago during deformation north of the Southern Zone ocean. During the final major deformation event in the Central Zone (D 3 doming), the fore-arc deposits and the underlying passive-margin sediments to the south were deformed. The Damaran granitic rocks are Hercynotype; granites make up 96 per cent of the more than 200 plutons. Average compositions have a slightly less calc-alkaline character than typical compressional margin granitic suites. Early granites have I-type chemistries and appear to have been derived from deep crustal sources, whereas most of the young granites have intermediate to S-type compositions and were generated at various crustal levels

  1. Crustal structure of the Dabie orogenic belt (eastern China) inferred from gravity and magnetic data

    Science.gov (United States)

    Yang, Yu-shan; Li, Yuan-yuan

    2018-01-01

    In order to better characterize the crustal structure of the Dabie orogen and its tectonic history, we present a crustal structure along a 500 km long profile across the Dabie orogenic belt using various data processing and interpretation of the gravity and magnetic data. Source depth estimations from the spectral analysis by continuous wavelet transform (CWT) provide better constraints for constructing the initial density model. The calculated gravity effects from the initial model show great discrepancy with the observed data, especially at the center of the profile. More practical factors are then incorporated into the gravity modeling. First, we add a high density body right beneath the high pressure metamorphic (HPM) and ultrahigh pressure metamorphic (UHPM) belt considering the exposed HPM and UHPM rocks in the mid of our profile. Then, the anomalous bodies A, B, and C inferred from the CWT-based spectral analysis results are fixed in the model geometry. In the final crustal density structure, two anomalous bodies B and C with high density and low magnetization could possibly be attributed to metasomatised mantle materials by SiO2-rich melt derived from the foundering subducted mafic lower crust. Under the extensional environment in the early Cretaceous, the upwelling metasomatised mantle was partially melted to produce the parental magma of the post-collisional mafic-ultramafic intrusive rocks. As for the low density body A with strong magnetization located in the lower crust right beneath the HP and UHP metamorphic belt, it is more likely to be composed of serpentinized mantle peridotite (SMP). This serpentinized mantle peridotite body (SMPB) represents the emplacement of mantle-derived peridotites in the crust, accompanying the exhumation of the UHP metamorphic rocks.

  2. Isolating active orogenic wedge deformation in the southern Subandes of Bolivia

    Science.gov (United States)

    Weiss, Jonathan R.; Brooks, Benjamin A.; Foster, James H.; Bevis, Michael; Echalar, Arturo; Caccamise, Dana; Heck, Jacob; Kendrick, Eric; Ahlgren, Kevin; Raleigh, David; Smalley, Robert; Vergani, Gustavo

    2016-08-01

    A new GPS-derived surface velocity field for the central Andean backarc permits an assessment of orogenic wedge deformation across the southern Subandes of Bolivia, where recent studies suggest that great earthquakes (>Mw 8) are possible. We find that the backarc is not isolated from the main plate boundary seismic cycle. Rather, signals from subduction zone earthquakes contaminate the velocity field at distances greater than 800 km from the Chile trench. Two new wedge-crossing velocity profiles, corrected for seasonal and earthquake affects, reveal distinct regions that reflect (1) locking of the main plate boundary across the high Andes, (2) the location of and loading rate at the back of orogenic wedge, and (3) an east flank velocity gradient indicative of décollement locking beneath the Subandes. Modeling of the Subandean portions of the profiles indicates along-strike variations in the décollement locked width (WL) and wedge loading rate; the northern wedge décollement has a WL of ~100 km while accumulating slip at a rate of ~14 mm/yr, whereas the southern wedge has a WL of ~61 km and a slip rate of ~7 mm/yr. When compared to Quaternary estimates of geologic shortening and evidence for Holocene internal wedge deformation, the new GPS-derived wedge loading rates may indicate that the southern wedge is experiencing a phase of thickening via reactivation of preexisting internal structures. In contrast, we suspect that the northern wedge is undergoing an accretion or widening phase primarily via slip on relatively young thrust-front faults.

  3. Physical properties of rocks from the Trans-Hudson orogen, Canada

    Science.gov (United States)

    Fowler, C. R.; Stead, D.; Pandit, B. I.; Janser, B. W.; Nisbet, E. G.

    2004-12-01

    A physical properties database of rock types from the Trans Hudson orogen is presented. Measurements have been made on 320 samples representing metamorphosed Archaean and juvenile Proterozoic orogenic rocks. Water saturated densities were generally between 2600 and 3100 kg m-3. In most cases the porosity was less than 1 percent. Except for a few samples, magnetic susceptibility ranged from 20 to 4000 x 10 exp-6 SI units. P-wave velocities and S-wave velocities were made under maximum uniaxial stress and triaxial stresses equivalent to depths of ca 4 km. P-wave and S-wave velocities measured were in the range 5-7 km s-1 and 3-4 km s-1 respectively. The velocity data show a wide variation in impedance between neighbouring domains and within domains: seismic reflection coefficients greater than 0.1 would appear to be routinely possible. Thermal conductivity measurements made using a `divided-bar' apparatus, yielded values between 1 and 5 W m-1 K-1. Electrical resistivity measurements were made at room temperature from 5 Hz to 10 kHz after samples were oven dried and after saturation in solutions with salinity up to 1.0 M. The porosity - resistivity data is in reasonable overall agreement with Archie's Law for all rock types. A minimum value for the resistivity of those samples not containing significant sulphide minerals or graphite, was 50 ohm-m. For sulphide and graphite-bearing samples, resistivity was as low as 1 ohm-m. The resistivity data are consistent with the hypothesis that North American Central Plains(NACP) conductivity anomaly is due to the presence in the crust of graphite- and/or sulphide-rich bodies or saline pore fluids.

  4. Various Particulate Matter Effects on Glacial Melting Rates in the Himalayan Mountain Range

    Science.gov (United States)

    Barwegen, S.

    2017-12-01

    Due to increased human activity and the impact of global warming in the Himalayas, glaciers are melting at alarming rates. It is hypothesized that by the year 2100, about 5,500 glaciers located in the Hindu-Kush will melt by up to 70%-90%. This will be severely detrimental to farmers as well as lessen the potential to harness hydropower, which requires the glaciers to be fully present (Vidal 2015). The melting of these glaciers is accelerating, in part, due to the deposition of particulate matter onto the snow, which lowers the albedo and causes the glaciers to absorb more heat. The Himalayan glaciers, specifically, are melting due to intense human movement over the snow, movement of particulate matter from storms, the increase in temperatures due to global warming, and soot deposited from forest fires (Dimmick 2014). This whole mountain range needs to retain glaciers in order to support the population of people living there by providing water. This project investigated the effect of both different types and amounts of particulate matter (PM) on ice melting rates. It was a model simulating the impact of PM of varying sizes and sources on glacial melting rates in the Himalayan glaciers. The impact of eight different types of PM (charcoal, pumice, sand/organic soil mixture, peat moss/soil, gravel/soil, soot, and soil), at two different masses (0.1g and 0.3g) on the melting rate of ice was assessed. Ice cubes were covered in PM and placed 5 cm away from a 50W incandescent bulb, with mass measured at regular intervals as they melted. Mass loss was recorded at 3, 6, 9, and 15 minutes and each sample type was repeated in triplicate. Over the course of the experiment, the ice cubes with 0.1 gram of PM were observed to be melting at a slower rate. Of the ice cubes with .3 g of PM on top, the ice covered in the sand and organic soil mixture had the lowest mass loss (3.4 g over 15 minutes), while the gravel and potting soil (4.9 g over 15 minutes) resulted in the highest (4

  5. Temporal and spatial changes in Western Himalayan firn line altitudes from 1998 to 2009

    Science.gov (United States)

    Guo, Zhongming; Wang, Ninglian; Kehrwald, Natalie M.; Mao, Ruijuan; Wu, Hongbo; Wu, Yuwei; Jiang, Xi

    2014-07-01

    Understanding changes in glacier mass balance is important because it is indicative of changes in climate and the hydrologic cycle. The latter also has particular influence on people living near glaciers and/or glacier-fed rivers. The Western Himalayas remain one of the regions where recent changes in glacier mass balance are not well-known. The temporal and spatial changes in firn line altitudes are an indicator of equilibrium line altitudes and thus reflect changes in glacier mass balance. Here, we use Himalayan Landsat TM/ETM + data in July and August (the late summer melt season) to quantify changes in firn line altitudes from 1998 to 2009. We produced reflectance maps through radiometric calibration and atmospheric correction and use topographic correction to remove or reduce terrain or shadow effects. The real ‘surface albedo’ is obtained by narrowband-to-broadband (NTB) albedo conversion from the combined solar radiation. The firn line altitude was then extracted by combining the ‘surface albedo’ with pre-registered digital elevation model. The individual firn line altitude varies by region. The Western Himalayas display the largest range of firn line variability, where the firn line altitudes vary from 4840 m a.s.l. to 5770 m a.s.l. The individual glacier mean firn line altitude from 1998 to 2009 rose from 5072 ± 77 m a.s.l. to 5640 ± 74 m a.s.l. in the Western Himalayas. The mean firn line altitude increased from 1998 to 2009. The lowest mean recorded firn line altitude recorded was 5237 ± 166 m a.s.l. in 1998, whereas the highest was 5397 ± 135 m a.s.l. in 2000. We also observed a difference between the changes in fine line altitudes of northern and southern slopes of the western Himalayans, as the northern slope glaciers display a greater increase in firn line altitudes than the southern slope glaciers. In the southern slope, changes in firn line altitudes correlate with NCDC-NOAA temperature and precipitation data. This sustained increase of

  6. Enhanced pre-monsoon warming over the Himalayan-Gangetic region from 1979 to 2007

    Science.gov (United States)

    Gautam, R.; Hsu, N. C.; Lau, K.-M.; Tsay, S.-C.; Kafatos, M.

    2009-04-01

    Fundamental to the onset of the Indian Summer Monsoon is the land-sea thermal gradient from the Indian Ocean to the Himalayas-Tibetan Plateau (HTP). The timing of the onset is strongly controlled by the meridional tropospheric temperature gradient due to the rapid pre-monsoon heating of the HTP compared to the relatively cooler Indian Ocean. Analysis of tropospheric temperatures from the longest available record of microwave satellite measurements reveals widespread warming over the Himalayan-Gangetic region and consequent strengthening of the land-sea thermal gradient. This trend is most pronounced in the pre-monsoon season, resulting in a warming of 2.7°C in the 29-year record (1979-2007), when this region is strongly influenced by dust aerosols at elevated altitudes. The enhanced tropospheric warming is accompanied by increased atmospheric loading of absorbing aerosols, particularly vertically extended dust aerosols, raising the possibility that aerosol solar heating has amplified the seasonal warming and in turn strengthened the land-sea gradient.

  7. Essential Oil Composition of Valeriana Jatamansi Jones from Himalayan Regions of India

    Science.gov (United States)

    Raina, Archana P.; Negi, K. S.

    2015-01-01

    Valeriana jatamansi Jones germplasm collected from sub-temperate Himalayan region of Uttarakhand and North-East state of Meghalaya, India was evaluated under identical conditions at National Bureau of Plant Genetic Resources, Bhowali, India, to study germplasm diversity based on essential oil composition. Twenty one compounds were identified in V. jatamansi root oil by GC and GC-MS. The major compounds identified were patchouli alcohol (0.4-63.7%), maaliol (2.9-53.8%), seychellene (4.1-27.4%), calarene/ß-gurjunene (3.0-20.8%), α-santalene (0.6-12.0%). Other compounds present were bornyl acetate (0.6-1.5%), α-guaiene (0.7-2.3%), α-bulnesene/δ-guaiene (0.7-6.3%), 7-epi-α-selinene (0.4-1.4%), kessane (2.1-3.3%), spathulenol (0.7-3.4%), viridiflorol (0.9-7.1%), α-patchoulene (0.8-6.6%), ß-patchoulene (0.4-0.8%). Two superior chemotypes identified in V. jatamansi oil from Uttarakhand were: patchouli alcohol rich (IC573221, 63.7%) and maaliol rich (IC573222, 53.8%; IC589096, 51.7%), while accession from north-east was patchouli alcohol rich chemotype (IC574522, 57.2%). These superior chemotypes with higher amounts of patchouli alcohol and maaliol could be used for promoting cultivation as well as for meeting need of pharmaceutical industries. PMID:26009656

  8. An overview of studies of observed climate change in the Hindu Kush Himalayan (HKH region

    Directory of Open Access Journals (Sweden)

    Qing-Long You

    2017-09-01

    Full Text Available The Hindu Kush Himalayan (HKH hereafter region is characterized by mountainous environments and a variety of regional climatic conditions. High-altitude regions in the HKH have the recent warming amplifications, especially during the global warming hiatus period. The rapid warming cause solid state water (snow, ice, glacier, and permafrost to shrink, leading to increase in meltwater and there have been found more frequent incidences of flash floods, landslides, livestock diseases, and other disasters in the HKH region. Increasing awareness of climate change over the HKH region is reached a consensus. Meanwhile, the HKH region is often referred to as the water towers of Asia as many high-altitude regions store its water in the form of snow and/or glacier, feeding ten major large rivers in Asia. Therefore, the impacts of climate change on water availability in these river basins have huge influences on the livelihood of large number of population, especially in downstream regions. However, the scarcity of basic hydro-meteorological observations particularly in high-altitude regions of HKH limits rigorous analysis of climate change. Most studies used reanalysis data and/or model-reconstructed products to explore the spatial and temporal characteristics of hydro-meteorological processes, especially for extreme events. In this study, we review recent climate change in the HKH region, and the scientific challenges and research recommendations are suggested for this high-altitude area.

  9. Ethnomedicinal botany of the Apatani in the Eastern Himalayan region of India

    Directory of Open Access Journals (Sweden)

    Kala Chandra Prakash

    2005-11-01

    Full Text Available Abstract This paper investigates the wealth of medicinal plants used by the Apatani tribe of Arunachal Pradesh. Apatani have traditionally settled in seven villages in the Ziro valley of Lower Subansiri district of Arunachal Pradesh in the Eastern Himalayan region of India. The present study has resulted in the documentation of 158 medicinal plant species used by the Apatani group of villages. These medicinal plant species were distributed across 73 families and 124 genera. Asteraceae was the most dominant family (19 species, 11 genera of medicinal plants, followed by Zingiberaceae, Solanaceae, Lamiaceae and Araceae. For curing ailments, the use of aboveground plant parts was higher (80% than the belowground plant parts in the Apatani group of villages. Of the aboveground plant parts, leaf was used in the majority of cases (56 species, followed by fruit. Different belowground plant forms such as root, tuber, rhizome, bulb and pseudo-bulb were used by Apatani as a medicine. About 52 types of ailments were cured by using these 158 medicinal plant species. The results of this study are further discussed in the changing socio-economic contexts.

  10. Understanding Dynamics of Himalayan Glaciers: Scope and Challenges of Remote Sensing

    Science.gov (United States)

    Bajracharya, S. R.; Maharjan, S. B.; Shrestha, F.

    2014-11-01

    remote-sensing based consistent semi-automated glacier mapping methodology with minimum manual intervention has been developed at ICIMOD. Using this methodology the glaciers of Hindu Kush Himalayan region were mapped in 2011 and continuously used for glacier mapping and monitoring in the region. These data were freely available to download from ICIMOD portal and GLIMS database. These comprehensive glacier information are the only data which is being used for research and development projects for countries like Bhutan, Nepal and Pakistan. Recently decadal glacier change from 1980 to 2010 of Nepal and Bhutan were published to understand the glacier change in the Himalaya. The decadal change assessment will be continued in other basins of HKH region to understand the glacier change. Due to rugged terrain, remote access, and logistic hindrance field verification is a challenging task and can be limited only in selected glaciers. Geodetic mass balance study in the selected glaciers like in Yala of Langtang basin and Rikha Samba of Hidden valley are on progress complement to field validation. High resolution images, lack of hydro-meteorological stations near to the glacier and limited competent manpower are another hindrance in the study of glacier change of the HKH region.

  11. HIMALA: Climate Impacts on Glaciers, Snow, and Hydrology in the Himalayan Region

    Science.gov (United States)

    Brown, Molly Elizabeth; Ouyang, Hua; Habib, Shahid; Shrestha, Basanta; Shrestha, Mandira; Panday, Prajjwal; Tzortziou, Maria; Policelli, Frederick; Artan, Guleid; Giriraj, Amarnath; hide

    2010-01-01

    Glaciers are the largest reservoir of freshwater on Earth, supporting one third of the world s population. The Himalaya possess one of the largest resources of snow and ice, which act as a freshwater reservoir for more than 1.3 billion people. This article describes a new project called HIMALA, which focuses on utilizing satellite-based products for better understanding of hydrological processes of the river basins of the region. With support from the US Agency for International Development (USAID), the International Centre for Integrated Mountain Development (ICIMOD), together with its partners and member countries, has been working on the application of satellite-based rainfall estimates for flood prediction. The US National Aeronautics and Space Administration (NASA) partners are working with ICIMOD to incorporate snowmelt and glacier melt into a widely used hydrological model. Thus, through improved modeling of the contribution of snow and ice meltwater to river flow in the region, the HIMALA project will improve the ability of ICIMOD and its partners to understand the impact of weather and climate on floods, droughts, and other water- and climate-induced natural hazards in the Himalayan region in Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, and Pakistan.

  12. Characterization of Microsatellite Loci in the Himalayan Lichen Fungus Lobaria pindarensis (Lobariaceae

    Directory of Open Access Journals (Sweden)

    Shiva Devkota

    2014-04-01

    Full Text Available Premise of the study: Microsatellite loci were developed for the rare, Himalayan, endemic haploid lichen fungus, Lobaria pindarensis, to study its population subdivision and the species' response to forest disturbance and fragmentation. Methods and Results: We developed 18 polymorphic microsatellite markers using 454 pyrosequencing data and assessed them in 109 individuals. The number of alleles per locus ranged from three to 11 with an average of 6.9. Nei's unbiased gene diversity, averaged over loci, ranged from 0.514 to 0.685 in the three populations studied. The cross-amplification success with related species (L. chinensis, L. gyrophorica, L. isidiophora, L. orientalis, L. pulmonaria, L. spathulata, and Lobaria sp. was generally high and decreased with decreasing relationship to L. pindarensis. Conclusions: The new markers will allow the study of genetic diversity and differentiation within L. pindarensis across its distribution. Moreover, they will enable us to study the effects of forest management on the genetic population structure of this tree-colonizing lichen and to carry out population genetic studies of related species in East Asia.

  13. Detection of flea-borne Rickettsia species in the Western Himalayan region of India

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    R Chahota

    2015-01-01

    Full Text Available Human infections by various rickettsial species are frequently reported globally. We investigated a flea-borne rickettsial outbreak infecting 300 people in Western Himalayan region of India. Arthropod vectors (ticks and fleas and animal and human blood samples from affected households were analysed by gltA and ompB genes based polymerase chain reaction (PCR. Rat flea (Ceratophyllus fasciatus samples were found harbouring a Rickettsia sp. Phylogenetic analysis based on gltA gene using PHYLIP revealed that the detected Rickettsia sp. has 100% identity with SE313 and RF2125 strains of Rickettsia sp. of flea origin from Egypt and Thai-Myanmar border, respectively and cf1 and 5 strains from fleas and lice from the USA. But, the nucleotide sequence of genetically variable gene ompB of R14 strain was found closely related to cf9 strain, reported from Ctenocephalides felis fleas. These results highlight the public health importance of such newly discovered or less recognised Rickettsia species/strains, harboured by arthropod vectors like fleas.

  14. Natural resources assessment and their utilization: analyses from a Himalayan state.

    Science.gov (United States)

    Uniyal, Sanjay Kr; Singh, Rakesh D

    2012-08-01

    The present paper quantifies and reviews the natural resource use in the Himalayan state of Himachal Pradesh (HP). Twenty-five percent of the geographical area of HP is under forests and harbour ca. 3,400 plant species. The available bioresources not only support the livelihood of nearly 6 million people but also fulfill the forage requirement of 5.2 million livestock. Thus, dependence on bioresources is manifold. Based on field surveys to different localities of HP and analyses of published information, two types of resource use patterns have been identified. One, the direct use of forest resources which is represented by extraction of timber, fuelwood and fodder; and the second represents indirect resource use from the forest that is represented by activities related to agriculture, tourism and industry. Amongst the direct resource use, annual timber requirement of the local people works out to be 310,063 m(3). On the other hand, annual fuelwood and fodder requirement of local people is to the tune of 3,646,348.8 and 10,294,116.5 tons, respectively. Extraction of fodder therefore appears to be one of the main reasons for forest degradation in HP as opposed to timber and fuelwood extraction. However, compared to direct resource use, indirect resource use and pressures have far more pronounced effect on the forests. Of the indirect pressures, shifts in agriculture patterns and increased tourism seem to be the most prominent.

  15. Acceptability of micronutrient fortified school meals by schoolchildren in rural Himalayan villages of India.

    Science.gov (United States)

    Osei, A K; Houser, R F; Bulusu, S; Hamer, D H

    2008-09-01

    This cross-sectional randomized controlled study assessed the social acceptability of micronutrient fortified cooked lunch meals by schoolchildren in rural Himalayan villages of India, in a program where the cooking and the micronutrient fortification were done at school. Subjects were randomly assigned to treatment (91) and control (90) groups. The treatment group consumed a weighed amount of cooked lunch meals fortified with locally produced multi-micronutrient premix and the control group consumed a weighed amount of the same meals but without added micronutrient premix. After having eaten, subjects were asked to rate, on a 3-point Likert scale using "smiley" faces, the pleasantness of smell, taste, and overall satisfaction with the food. The mean age of study children was 7.96 +/- 1.64 y and 48.6% were males. The average amounts of food consumed by the treatment and control groups were 345 +/- 114 and 360 +/- 102.4 g, respectively. Addition of the multi-micronutrient premix to school meals did not significantly affect the mean amount of food consumed by the schoolchildren (P > 0.05; independent sample t-test). No significant differences were seen between treatment and control groups in terms of ratings for taste, smell, and the general acceptance of the micronutrient fortified or the unfortified school meals. In conclusion, the addition of a multiple micronutrient premix to school meals was well liked by schoolchildren and did not adversely affect their food consumption.

  16. Himalayan uplift shaped biomes in Miocene temperate Asia: evidence from leguminous Caragana.

    Science.gov (United States)

    Zhang, Ming-Li; Xiang, Xiao-Guo; Xue, Juan-Juan; Sanderson, Stewart C; Fritsch, Peter W

    2016-11-09

    Caragana, with distinctive variation in leaf and rachis characters, exhibits three centers of geographic distribution, i.e., Central Asia, the Qinghai-Tibetan Plateau (QTP), and East Asia, corresponding to distinct biomes. Because Caragana species are often ecologically dominant components of the vegetation in these regions, it is regarded as a key taxon for the study of floristic evolution in the dry regions of temperate Asia. Based on an expanded data set of taxa and gene regions from those previously generated, we employed molecular clock and biogeographical analyses to infer the evolutionary history of Caragana and link it to floristic patterns, paleovegetation, and paleoclimate. Results indicate that Caragana is of arid origin from the Junggar steppe. Diversification of crown group Caragana, dated to the early Miocene ca. 18 Ma and onwards, can be linked to the Himalayan Motion stage of QTP uplift. Diversification of the major clades in the genus corresponding to taxonomic sections and morphological variation is inferred to have been driven by the uplift, as well as Asian interior aridification and East Asian monsoon formation, in the middle to late Miocene ca. 12~6 Ma. These findings demonstrate a synchronous evolution among floristics, vegetation and climate change in arid Central Asia, cold arid alpine QTP, and mesophytic East Asia.

  17. From 'third pole' to north pole: a Himalayan origin for the arctic fox.

    Science.gov (United States)

    Wang, Xiaoming; Tseng, Zhijie Jack; Li, Qiang; Takeuchi, Gary T; Xie, Guangpu

    2014-07-22

    The 'third pole' of the world is a fitting metaphor for the Himalayan-Tibetan Plateau, in allusion to its vast frozen terrain, rivalling the Arctic and Antarctic, at high altitude but low latitude. Living Tibetan and arctic mammals share adaptations to freezing temperatures such as long and thick winter fur in arctic muskox and Tibetan yak, and for carnivorans, a more predatory niche. Here, we report, to our knowledge, the first evolutionary link between an Early Pliocene (3.60-5.08 Myr ago) fox, Vulpes qiuzhudingi new species, from the Himalaya (Zanda Basin) and Kunlun Mountain (Kunlun Pass Basin) and the modern arctic fox Vulpes lagopus in the polar region. A highly hypercarnivorous dentition of the new fox bears a striking resemblance to that of V. lagopus and substantially predates the previous oldest records of the arctic fox by 3-4 Myr. The low latitude, high-altitude Tibetan Plateau is separated from the nearest modern arctic fox geographical range by at least 2000 km. The apparent connection between an ancestral high-elevation species and its modern polar descendant is consistent with our 'Out-of-Tibet' hypothesis postulating that high-altitude Tibet was a training ground for cold-environment adaptations well before the start of the Ice Age. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  18. Tiger density in a tropical lowland forest in the Eastern Himalayan Mountains.

    Science.gov (United States)

    Singh, Randeep; Chauhan, Devendra Singh; Mishra, Sudhanshu; Krausman, Paul R; Goyal, Surendra Prakash

    2014-01-01

    Tropical evergreen forests in northeast India are a biological hot spot for conservation of flora and fauna. Little is known, however, about tiger abundance, which is a flagship species for tropical evergreen forests. Our objective was to document the capture rate and population density of tigers based on spatial explicit capture-recapture (SECR) approaches using camera trap data in an intensive study area (ISA) of 158 km(2) in Pakke Tiger Reserve (PTR) during March to May 2006. The Reserve lies in the foothills of the Eastern Himalayan Mountains, northeast India. We monitored 38 camera traps in ISA for 70 days and documented 10 photo-captures of tigers (5 left and 5 right flanks) with an average trap success rate of 1.3 captures/100 trap days. The overall capture probability was 0.05. The tiger density estimated using a SECR model was 0.97 ± 0.23 individuals/100 km(2). This is the first systematic sampling study in tropical semi evergreen forests of India, and information on capture rate and population density of tigers provides baseline data from which to determining changes in the future to assist conservation.

  19. Soil-gas radon/helium surveys in some neotectonic areas of NW Himalayan foothills, India

    Directory of Open Access Journals (Sweden)

    S. Mahajan

    2010-06-01

    Full Text Available The present research is aimed at accessing the relationship between variation in the soil gases radon (222Rn and helium (4He and recently developed fissures and other neotectonic features in Nurpur and Nadha areas of the NW Himalayas, India. Two soil-gas surveys were conducted on/near known faults to reconfirm their position using soil gas technique and to check their present activity. During these surveys, soil-gas samples were collected along traverses crossing the observed structures. The data analysis reveals that the concentrations of radon and helium along the Dehar lineament and the longitudinal profile (Profile D are very high compared to any other thrust/lineament of the Nurpur area. The Nadha area shows high values of radon and helium concentrations along/near the Himalayan Frontal Fault (HFF as compared to the adjoining areas. This indicates the presence of some buried fault/fault zone running parallel to the HFF, not exposed to the surface and not delineated by satellite data but is geochemically active and might be tectonically active too. Hence, soil helium and radon gas patterns have been combined with morphological and geological observations to supply useful constraints for deformation of tectonic environments.

  20. Numerical modeling of a remote Himalayan glacier constrained by satellite data

    Science.gov (United States)

    Scherler, Dirk; Farinotti, Daniel; Anderson, Robert S.; Strecker, Manfred R.

    2010-05-01

    Himalayan glaciers are amongst the least studied and understood glaciers on Earth, yet their future behavior and water budget is crucial for densely-populated areas in south, central, and eastern Asia. Here, we use remotely-sensed glacier-surface velocities from a glacier in the upper Tons valley of western Uttaranchal in the Indian Himalaya, to evaluate the results from a numerical glacier model. We estimate present-day ice thickness distribution from surface topography with an approach based on mass conservation and principles of ice-flow dynamics. The numerical glacier model is based on the shallow ice approximation, and requires a mass-balance profile and glacier-bedrock topography as input. Optical-satellite imagery is used for mapping glacier extents and deriving glacier-surface velocities from cross correlation of multi-temporal ASTER and SPOT images. Modeling results, employing a mass balance profile from nearby monitored glaciers with a better data base, indicate good agreement between observed and modeled glacier extents and surface velocities. Discrepancies between model and observation in the lower part of the glacier are likely related to (1) poorly constrained effects of debris cover, and (2) the present disequilibrium and down-wasting of the glacier. Our technique will be useful for comparative analyses of glacial behavior worldwide as most data for our study has been obtained from analysis of remote-sensing data, virtually available for any region on Earth.

  1. The Paleozoic metamorphic history of the Central Orogenic Belt of China from 40Ar/39Ar geochronology of eclogite garnet fluid inclusions

    NARCIS (Netherlands)

    Qiu, H.N.; Wijbrans, J.R.

    2008-01-01

    The pressure-temperature-time evolution of the UHP eclogites of Dabie-Sulu, in the eastern sector of the Central Orogenic Belt of China shows a complex pattern of predominantly Triassic, and to a lesser extent Early Paleozoic ages.

  2. Rapid Urban Growth in the Kathmandu Valley, Nepal: Monitoring Land Use Land Cover Dynamics of a Himalayan City with Landsat Imageries

    Directory of Open Access Journals (Sweden)

    Asif Ishtiaque

    2017-10-01

    Full Text Available The Kathmandu Valley of Nepal epitomizes the growing urbanization trend spreading across the Himalayan foothills. This metropolitan valley has experienced a significant transformation of its landscapes in the last four decades resulting in substantial land use and land cover (LULC change; however, no major systematic analysis of the urbanization trend and LULC has been conducted on this valley since 2000. When considering the importance of using LULC change as a window to study the broader changes in socio-ecological systems of this valley, our study first detected LULC change trajectories of this valley using four Landsat images of the year 1989, 1999, 2009, and 2016, and then analyzed the detected change in the light of a set of proximate causes and factors driving those changes. A pixel-based hybrid classification (unsupervised followed by supervised approach was employed to classify these images into five LULC categories and analyze the LULC trajectories detected from them. Our results show that urban area expanded up to 412% in last three decades and the most of this expansion occurred with the conversions of 31% agricultural land. The majority of the urban expansion happened during 1989–2009, and it is still growing along the major roads in a concentric pattern, significantly altering the cityscape of the valley. The centrality feature of Kathmandu valley and the massive surge in rural-to-urban migration are identified as the primary proximate causes of the fast expansion of built-up areas and rapid conversions of agricultural areas.

  3. Study of the Genetic Diversity of the Ornamental Fish Badis badis (Hamilton-Buchanan, 1822 in the Terai Region of Sub-Himalayan West Bengal, India

    Directory of Open Access Journals (Sweden)

    Tanmay Mukhopadhyay

    2014-01-01

    Full Text Available Dwarf chameleon fish or Badis badis, a lesser known ornamental freshwater fish, has recently been included in the Indian threatened category of fish list. There are insufficient studies with regard to the assessment of genetic background of this ichthyofauna, especially in the western sub-Himalayan region of West Bengal, India, popularly known as the Terai. The present study is the first attempt to investigate the present status of the genetic background of this species in the Mahananda and Balason rivers, major streams of this region. Twenty-one selective RAPD primers generated 53 and 60 polymorphic fragments in the Mahananda and Balason populations, respectively. The proportion of polymorphic loci, Nei’s genetic diversity (H, and Shannon’s index (H′ were 0.4416, 0.1654±0.2023, and 0.2450±0.2907, respectively, in Mahananda river population and were 0.5041, 0.1983±0.2126, and 0.2901±0.3037, respectively, in Balason river population. Inbreeding coefficient and degree of gene differentiation were also calculated. The H and H′ were found to be 0.1601±0.1944 and 0.2363±0.2782, respectively, in overall Mahananda-Balason river system. Our study revealed considerable lack of genetic variation among the individuals of Badis badis. The genetic data obtained from the present study lend support to the view that there is a scope of stock improvement for this ichthyofauna.

  4. Magma-assisted strain localization in an orogen-parallel transcurrent shear zone of southern Brazil

    Science.gov (United States)

    Tommasi, AndréA.; Vauchez, Alain; Femandes, Luis A. D.; Porcher, Carla C.

    1994-04-01

    In a lithospheric-scale, orogen-parallel transcurrent shear zone of the Pan-African Dom Feliciano belt of southern Brazil, two successive generations of magmas, an early calc-alkaline and a late peraluminous, have been emplaced during deformation. Microstructures show that these granitoids experienced a progressive deformation from magmatic to solid state under decreasing temperature conditions. Magmatic deformation is indicated by the coexistence of aligned K-feldspar, plagioclase, micas, and/or tourmaline with undeformed quartz. Submagmatic deformation is characterized by strain features, such as fractures, lattice bending, or replacement reactions affecting only the early crystallized phases. High-temperature solid-state deformation is characterized by extensive grain boundary migration in quartz, myrmekitic K-feldspar replacement, and dynamic recrystallization of both K-feldspar and plagioclase. Decreasing temperature during solid-state deformation is inferred from changes in quartz crystallographic fabrics, decrease in grain size of recrystallized feldspars, and lower Ti amount in recrystallized biotites. Final low-temperature deformation is characterized by feldspar replacement by micas. The geochemical evolution of the synkinematic magmatism, from calc-alkaline metaluminous granodiorites with intermediate 87Sr/86Sr initial ratio to peraluminous granites with very high 87Sr/86Sr initial ratio, suggests an early lower crustal source or a mixed mantle/crustal source, followed by a middle to upper crustal source for the melts. Shearing in lithospheric faults may induce partial melting in the lower crust by shear heating in the upper mantle, but, whatever the process initiating partial melting, lithospheric transcurrent shear zones may collect melt at different depths. Because they enhance the vertical permeability of the crust, these zones may then act as heat conductors (by advection), promoting an upward propagation of partial melting in the crust

  5. Microtectonic and geochemical characterization of thrusting in a foreland basin: Example of the South-Pyrenean orogenic wedge (Spain)

    Science.gov (United States)

    Lacroix, B.; Buatier, M.; Labaume, P.; Travé, A.; Dubois, M.; Charpentier, D.; Ventalon, S.; Convert-Gaubier, D.

    2011-09-01

    In orogenic systems, thrust faults play a major role in stacking different tectonic units and may act as conduits for the expulsion of large amounts of fluid of different origins (metamorphic, diagenetic, meteoric). This study focuses on the Monte Perdido thrust unit emplaced in the Paleogene Jaca thrust-sheet-top basin, in the SW-central Pyrenees. We aim to decipher the mechanisms and P-T conditions of deformation in fault zones and characterize the related fluid involvement, through combined microstructural, geochemical and microthermometry analyses. Two thrust faults cutting platform limestones, marls and siliciclastic turbidites of the lower part of the basin-fill (Paleocene-lower Eocene) have been studied. The fault zones are characterized by metre-thick shear zones with highly deformed, foliated clay-rich sediments. Foliation is underlined by preferentially oriented phyllosilicates. Several generations of shear and extension calcite, quartz and chlorite-bearing veins attest to fluid-rock interactions during a multi-stage deformation. Microstructural observations and stable isotope analyses on calcite from veins and host sediments suggest that deformation was aseismic and dominated by diffusive mass transfer from pressure solution sites along cleavage and stylolites to the precipitation sites in veins, with mineralizing fluids in equilibrium with the host sediments. Our results suggest an essentially closed hydrologic system, and imply the absence of significant fluid flow along the studied fault zones. Microthermometric study on fluid inclusions present in calcite and quartz veins, and calcite-quartz oxygen isotopic fractionation determined for the first generation shear veins, allow a geothermal gradient of 34 °C/km to be estimated. Analytical results demonstrate an evolution of the fault zones in three stages. The first stage was related to the emplacement of the Monte Perdido thrust unit during the middle Eocene at a temperature of ˜208 °C and a burial

  6. Conceptual model development for landscape management in the mountains of the Indian Himalayan region: an approach for sustainable socio-ecological development

    Directory of Open Access Journals (Sweden)

    Sunil Nautiyal

    2010-09-01

    Full Text Available This study aims at presenting a conceptual model for landscape management in the Himalayan region of India, using quantitative/mathematical approach. Keeping in view the requirement, (based on fifteen years empirical field work in the Himalayan region and as well as literature survey the MODAM (Multiple Objectives Decision Support Tools for Landscape Management model along with linear programming approach was adopted with a view to presenting additional methodological perspectives on interdisciplinary landscape research. The work has stemmed out from the original research contribution, which tries to integrate interdisciplinary research planning with landscape management related research in the Himalayan region. This biodiversity hotspot has relatively high complexity in terms of sustainable socioeconomic development vis a vis conservation and management of the resources. The concepts and insights presented in this article will provide the basis for a discussion, on decisionmaking issues among multidisciplinary experts with regard to sustainable socioecological development within complex environments.

  7. Uranium cycle and tectono-metamorphic evolution of the Lufilian Pan-African orogenic belt (Zambia)

    International Nuclear Information System (INIS)

    Eglinger, Aurelien

    2013-01-01

    Uranium is an incompatible and lithophile element, and thus more concentrated in silicate melt produced by the partial melting of the mantle related to continental crust formation. Uranium can be used as a geochemical tracer to discuss the generation and the evolution of continental crust. This thesis, focused on the Pan-African Lufilian belt in Zambia, combines structural geology, metamorphic petrology and thermos-barometry, fluid inclusions, geochemistry and geochronology in order to characterize the uranium cycle for this crustal segment. Silici-clastic and evaporitic sediments have been deposited within an intra-continental rift during the dislocation of the Rodinia super-continent during the early Neo-proterozoic. U-Pb ages on detrital zircon grains in these units indicate a dominant Paleo-proterozoic provenance. The same zircon grains show sub-chondritic εHf (between 0 and -15) and yield Hf model ages between ∼2.9 and 2.5 Ga. These data suggest that the continental crust was generated before the end of the Archean (< 2.5 Ga) associated with uranium extraction from the mantle. This old crust has been reworked by deformation and metamorphism during the Proterozoic. Uranium has been re-mobilized and reconcentrated during several orogenic cycles until the Pan-African orogeny. During this Pan-African cycle, U-Pb and REY (REE and Yttrium) signatures of uranium oxides indicate a first mineralizing event at ca. 650 Ma during the continental rifting. This event is related to late diagenesis hydrothermal processes at the basement/cover interface with the circulation of basinal brines linked to evaporites of the Roan. The second stage, dated at 530 Ma, is connected to metamorphic highly saline fluid circulations, synchronous to the metamorphic peak of the Lufilian orogeny (P=9±3 kbar; T=610±30 deg. C). These fluids are derived from the Roan evaporite dissolution. Some late uranium re-mobilizations are described during exhumation of metamorphic rocks and their

  8. Complete moment tensor retrieval for weak events: application to orogenic and volcanic areas

    Science.gov (United States)

    Campus, P.; Suhadolc, P.; Panza, G. F.; Sileny, J.

    1996-08-01

    Aiming to study the mechanism and time history of weak local events we invert the dominant part of high-frequency seismograms (S and surface waves) by using two methods which implement moment tensor description of the focus. The point-source approximation is applied since we assume that the size of the focus with respect to the minimum wavelength of the analyzed signals is relatively small. Various constraints of the moment tensor are applied to cover local events of different origin - both the tectonic earthquakes and seismic events induced by volcanic activity. In the former case the double-couple constraint is applied, in the latter one a full moment tensor is decomposed into a volumetric part (V), representing volume changes, a compensated linear vector-dipole part (CLVD), describing opening of a fluid-filled lenticular crack, and a double couple part (DC), representing a shear slip. In the full moment tensor inversion the hypocentral depth and structural model may vary within pre-defined intervals. In the orogenic area of Friuli, Northern Italy, both the method looking for a DC only and the procedure implying the complete moment tensor arrive produce a DC mechanism, the orientation of which is consistent with the polarity readings. In the volcanic area of Phlegrean Fields, Southern Italy, the possible existence of fluid motion, which can be associated to volume changes and crack openings has to be taken into account, therefore, we used only the full moment tensor description to analyze several events in the magnitude range from 1.3 to 3. The obtained source durations vary from a few tenths of a second to about two seconds, suggesting that even small events may be characterized by relatively complex rupture history, although some of the retrieved complexities may be an artifact due to lateral inhomogeneities and other unmodelled structural effects. The percentage of the V component was found to be as large as 30% here, while it was negligible in the orogenic

  9. Prolonged high relief in the northern Cordilleran orogenic front during middle and late Eocene extension based on stable isotope paleoaltimetry

    Science.gov (United States)

    Fan, Majie; Constenius, Kurt N.; Dettman, David L.

    2017-01-01

    The paleoelevation and size of the North America Cordilleran orogen during the late Cretaceous-Paleogene contractional and subsequent extensional tectonics remain enigmatic. We present new estimates of paleorelief of the northern Cordilleran orogenic front during the middle and late Eocene using oxygen isotope compositions of unaltered molluscan fossils and paleosol carbonates in the Kishenehn basin. Bounded by several mountains ranges to the east, the Kishenehn basin was a half graben developed during middle Eocene to early Miocene collapse of the Cordilleran orogen. These mollusk taxa include three sympatric groups with affinities to wet tropical, semi-arid subtropical, and temperate environments. Our reconstructed surface water δ18O values vary between -19.8‰ and -6.3‰ (VSMOW) during the middle and late Eocene. The large differences in paleoenvironments and surface water δ18O values suggest that the catchment of the Kishenehn basin was at variable elevation. The estimated paleorelief between the basin and the surrounding mountains, based on both Rayleigh condensation model and predictions of Eocene precipitation isotope values using an isotope-enabled global climate model, is ∼4 km, and the basin floor was <1.5 km high. This high topography and high relief paleogeography suggest that the Cordilleran orogenic front reached an elevation of at least 4 km, and the crust thickness may have reached more than 55 km before Eocene gravitational collapse. We attribute the maintenance of high Eocene topography to the combination of an inherited thick crust, thermal uplift caused by mantle upwelling, and isostatic uplift caused by removing lower lithosphere or oceanic slab.

  10. Role of Neogene Exhumation and Sedimentation on Critical-Wedge Kinematics in the Zagros Orogenic Belt, Northeastern Iraq, Kurdistan

    Science.gov (United States)

    Koshnaw, R. I.; Horton, B. K.; Stockli, D. F.; Barber, D. E.; Tamar-Agha, M. Y.; Kendall, J. J.

    2014-12-01

    The Zagros orogenic belt and foreland basin formed during the Cenozoic Arabia-Eurasia collision, but the precise histories of shortening and sediment accumulation remain ambiguous, especially at the NW extent of the fold-thrust belt in Iraqi Kurdistan. This region is characterized by well-preserved successions of Cenozoic clastic foreland-basin fill and deformed Paleozoic-Mesozoic hinterland bedrock. The study area provides an excellent opportunity to investigate the linkage between orogenic wedge behavior and surface processes of erosion and deposition. The aim of this research is to test whether the Zagros orogenic wedge advanced steadily under critical to supercritical wedge conditions involving in-sequence thrusting with minimal erosion or propagated intermittently under subcritical condition involving out-of-sequence deformation with intense erosion. These endmember modes of mountain building can be assessed by integrating geo/thermochronologic and basin analyses techniques, including apatite (U-Th)/He thermochronology, detrital zircon U-Pb geochronology, stratigraphic synthesis, and seismic interpretations. Preliminary apatite (U-Th)/He data indicate activation of the Main Zagros Fault (MZF) at ~10 Ma with frontal thrusts initiating at ~8 Ma. However, thermochronometric results from the intervening Mountain Front Flexure (MFF), located between the MZF and the frontal thrusts, suggest rapid exhumation at ~6 Ma. These results suggest that the MFF, represented by the thrust-cored Qaradagh anticline, represents a major episode of out-of-sequence deformation. Detrital zircon U-Pb analyses from the Neogene foreland-basin deposits show continuous sediment derivation from sources to the NNE in Iraq and western Iran, suggesting that out-of-sequence thrusting did not significantly alter sedimentary provenance. Rather, intense hinterland erosion and recycling of older foreland-basin fill dominated sediment delivery to the basin. The irregular distribution of

  11. Large along-strike variations in the onset of Subandean exhumation: Implications for Central Andean orogenic growth

    Science.gov (United States)

    Lease, Richard O.; Ehlers, T.A.; Enkelmann, E.

    2016-01-01

    Plate tectonics drives mountain building in general, but the space-time pattern and style of deformation is influenced by how climate, geodynamics, and basement structure modify the orogenic wedge. Growth of the Subandean thrust belt, which lies at the boundary between the arid, high-elevation Central Andean Plateau and its humid, low-elevation eastern foreland, figures prominently into debates of orogenic wedge evolution. We integrate new apatite and zircon (U-Th)/He thermochronometer data with previously published apatite fission-track data from samples collected along four Subandean structural cross-sections in Bolivia between 15° and 20°S. We interpret cooling ages vs. structural depth to indicate the onset of Subandean exhumation and signify the forward propagation of deformation. We find that Subandean growth is diachronous south (11 ± 3 Ma) vs. north (6 ± 2 Ma) of the Bolivian orocline and that Subandean exhumation magnitudes vary by more than a factor of two. Similar north-south contrasts are present in foreland deposition, hinterland erosion, and paleoclimate; these observations both corroborate diachronous orogenic growth and illuminate potential propagation mechanisms. Of particular interest is an abrupt shift to cooler, more arid conditions in the Altiplano hinterland that is diachronous in southern Bolivia (16-13 Ma) vs. northern Bolivia (10-7 Ma) and precedes the timing of Subandean propagation in each region. Others have interpreted the paleoclimate shift to reflect either rapid surface uplift due to lithosphere removal or an abrupt change in climate dynamics once orographic threshold elevations were exceeded. These mechanisms are not mutually exclusive and both would drive forward propagation of the orogenic wedge by augmenting the hinterland backstop, either through surface uplift or spatially variable erosion. In summary, we suggest that diachronous Subandean exhumation was driven by piecemeal hinterland uplift, orography, and the outward

  12. A Major Out of Sequence Fault in Central Range and Its Implication to Mountain Building Process of Taiwan Orogenic Belt

    Science.gov (United States)

    Lee, Y. H.

    2015-12-01

    A Major Out of Sequence Fault in Central Range and Its Implication to Mountain Building Process of Taiwan Orogenic Belt Yuan-Hsi Lee1, Wei Lo2, Wei-Hau Wang1, Tim-Byrne 3, Ruey-Juen Rau 41. Department of Earth and Environmental Sciences, National Chung Cheng University, Taiwan, R.O.C. 2. Department of Materials and Mineral Resources Engineering, Taipei, National Taipei University of Technology, Taiwan, R.O.C. 3. Center for Integrative Geosciences, University of Connecticut, Storrs, CT, USA 4. Department of Earth Science, National Chen-Kung University, Taiwan, R.O.C. Taiwan mountain belt results from collision between Eurasia continental crust and Philippine Sea plate that result in exposing the metamorphic complex with high exhumation rate in eastern Central Range of Taiwan orogenic belt. In this study we combine with field survey, zircon fission track (ZFT), metamorphic grade, and tomography data to identify there exists a major out of sequence fault (MOSF) in eastern Central Range of Taiwan orogenic belt. This MOSF extends from north to south of eastern central Range with several segments and the total length is more than 250 km. The ZFT shows total annealing age of ca.1-3 Ma on the hanging wall and partial annealing ages on the foot wall. The seismicity data indicates the MOSF is still active from central to southern central Range. We consider that the MOSF is related with crustal channel flow in depth. To the western side of crustal flow it shows thrusting mechanism associated with MOSF and the normal faults (or normal shearing zone) develop in eastern side of the crustal channel flow. This crustal channel flow is also related with exposing the metamorphic complex in Central Range that is important mechanism for the mountain building process of Taiwan orogenic belt.

  13. Late Miocene Thermal Evolution of the Eastern Himalayan Syntaxis as Constrained by Biotite 40Ar/39Ar Thermochronology

    Science.gov (United States)

    Gong, J.; Ji, J.; Zhou, J.; Tu, J.; Sun, D.; Han, B.; Zhong, D.

    2014-12-01

    We conducted biotite 40Ar/39Ar thermochronological research in the eastern Himalayan syntaxis and the surrounding Gangdese belt that wraps around the syntaxis, aiming to explore the overall cooling pattern and thermal evolution in this hard-to-access region. The compilation of our new dataset and published ages in the region presents a new temporal-spatial pattern: (1) Separated by the boundary faults of the eastern Himalayan syntaxis, a temporal gap at 13-7 Ma exists in the cooling history of the study area, with ages younger than 7 Ma clustering within the syntaxis, while ages older than 13 Ma distributing in the Gangdese belt. The gap could be a manifestation of the reactivated rapid cooling of the syntaxis since 7 Ma on the background of slow cooling all over the region, which temporally constrains the initial propagation of the eastern Himalayan syntaxis. (2) Ages in the syntaxis and the surrounding region show an annulus shape that younging toward Namche Barwa-Gyala Peri peak that is the core of the syntaxis, from 7-4 Ma and 4-2 Ma in the vicinities to 2-1 Ma in the core, which presents a spatially progressive acceleration in the cooling and exhumation towards the core. This observation indicates that the syntaxis experiences an inward acceleration along a vertical stalk rather than large-scale lateral propagation since late Miocene. The new findings argue that cooling revealed by biotite 40Ar/39Ar method was driven by tectonic contraction. We propose a model for the development of the Namche Barwa syntaxis that dominated by impulsive accelerating and subordinated by progressive accelerating driving by gravitational isostasy.

  14. Automatically detecting Himalayan Glacial Lake Outburst Floods in LANDSAT time series

    Science.gov (United States)

    Veh, Georg; Korup, Oliver; Roessner, Sigrid; Walz, Ariane

    2017-04-01

    More than 5,000 meltwater lakes currently exist in the Himalayas, and some of them have grown rapidly in past decades due to glacial retreat. This trend might raise the risk of Glacial Lake Outburst Floods (GLOFs), which have caused catastrophic damage and several hundred fatalities in historic time. Yet the growing number and size of Himalayan glacial lakes have no detectable counterpart in increasing GLOF frequency. Only 35 events are documented in detail since the 1950s, mostly in the Himalayas of Eastern Nepal and Bhutan. Observations are sparse in the far eastern and totally missing in the northwestern parts of the mountain belt. The GLOF record is prone to a censoring bias, such that mainly larger floods or flood impacts have been registered. Thus, establishing a more complete record and learning from past GLOFs is essential for hazard assessment and regional planning. To detect previously unreported GLOFs in the Himalayas, we developed an automated processing chain for generating GLOF related surface-cover time series from LANDSAT data. We downloaded more than 5,000 available LANDSAT TM, ETM+ and OLI images from 1987 to present. We trained a supervised machine-learning classifier with >4,000 randomly selected image pixels and topographic variables derived from digital topographic data (SRTM and ALOS DEMs), defining water, sediment, shadow, clouds, and ice as the five main classes. We hypothesize that GLOFs significantly decrease glacial lake area while increasing the amount of sediment cover in the channel network downstream simultaneously. Thus we excluded shadows, clouds, and lake ice from the analysis. We derived surface cover maps from the fitted model for each satellite image and compiled a pixelwise time-series stack. Customized rule sets were applied to systematically remove misclassifications and to check for a sediment fan in the flow path downstream of the former lake pixels. We verified our mapping approach on thirteen GLOFs documented in the

  15. Rhizospheric Bacterial Community of Endemic Rhododendron arboreum Sm. Ssp. delavayi along Eastern Himalayan Slope in Tawang

    Directory of Open Access Journals (Sweden)

    Rajal Debnath

    2016-09-01

    Full Text Available Information on rhizosphere micobiome of endemic plants from high mountain ecosystems against those of cultivated plantations is inadequate. Comparative bacterial profiles of endemic medicinal plant R. arboreum Sm. subsp. delavayi rhizosphere pertaining to four altitudinal zonation Pankang-Thang (PTSO, Nagula, Y-junction and Bum La (Indo-China border (in triplicates each along cold adapted Eastern slope of Himalayan Tawang region, India is described here. Significant differences in DGGE profile between below ground bulk vs rhizospheric community profile associated with the plant was identified. Tagged 16S amplicon sequencing from PTSO (3912m to Bum La (4509 m, revealed that soil pH, total nitrogen (TN, organic matter (OM significantly influenced the underlying bacterial community structure at different altitudes. The relative abundance of Acidobacteria was inversely related to pH, as opposed to TN which was positively correlated to Acidobacteria and Proteobacteria abundance. TN was also the significant predictor for less abundant taxonomic groups Chloroflexi, Gemmatimonadetes and Nitrospirae. Bum La soil harbored less bacterial diversity compared to other sites at lower altitudes. The most abundant phyla at 3% genetic difference were Acidobacteria, Actinobacteria and Proteobacteria amongst others. Analysis of similarity indicated greater similarity within lower altitudinal than higher altitudinal group (ANOSIM, R = 0.287, p = 0.02. Constraining the ordination with the edaphic factor explained 83.13% of variation. Unique phylotypes of Bradyrhizobium and uncultured Rhizobiales were found in significant proportions at the four regions. With over 1% relative abundance Actinobacteria (42.6%, Acidobacteria (24.02%, Proteobacteria (16.00%, AD3 (9.23%, WPS-2 (5.1% and Chloroflexi (1.48% dominated the core microbiome.

  16. Metamorphic evolution of the Lesser Himalayan Crystalline Sequence, Siyom Valley, NE Himalaya, India

    Science.gov (United States)

    Nandini, P.; Thakur, S. S.

    2011-03-01

    The paper reports classical Barrovian inverted metamorphism in the Lesser Himalayan Crystalline Sequence, Siyom Valley, NE Himalaya. The sequence is thrust-bounded and constitutes a part of the western limb of the Siang antiform. Six metamorphic zones are delineated with increasing grade from biotite zone through garnet-, staurolite-, kyanite-, sillimanite- to sillimanite-K-feldspar zone with increasing structural level. Granulite-facies pelitic assemblages, marked by the occurrence of garnet + cordierite occur in the sillimanite-K-feldspar zone. Three phases of folding, F 1, F 2 and F 3 and two generations of planar structures, S 1 and S 2 are recognised. Peak metamorphic mineral growths are dominantly syn-F 2. Metamorphic isograds and boundary thrusts of the sequence are co-folded around the Siang antiform by F 3 deformation. Garnet shows prograde growth zoning in lower grade rocks and retrograde diffusion zoning in higher grade rocks. Pelites of the sillimanite-K-feldspar zone show textural evidence of decompression such as corona of cordierite around kyanite. Breakdown reactions of muscovite and biotite in this zone are attributed to decompression. Geothermobarometric calculations show gradual increase of temperature from garnet zone to sillimanite-K-feldspar zone, whereas pressure increases sharply from garnet zone to staurolite zone and remains nearly constant thereafter. Peak metamorphism reached temperature of >750 °C and pressure of ˜10 kbar in the sillimanite-K-feldspar zone. P-T estimates, decompression reactions and pseudosection topologies suggest a clockwise path with steep decompression for the evolution of the sillimanite-K-feldspar zone in the Siyom Valley.

  17. Estimating stream discharge from a Himalayan Glacier using coupled satellite sensor data

    Science.gov (United States)

    Child, S. F.; Stearns, L. A.; van der Veen, C. J.; Haritashya, U. K.; Tarpanelli, A.

    2015-12-01

    The 4th IPCC report highlighted our limited understanding of Himalayan glacier behavior and contribution to the region's hydrology. Seasonal snow and glacier melt in the Himalayas are important sources of water, but estimates greatly differ about the actual contribution of melted glacier ice to stream discharge. A more comprehensive understanding of the contribution of glaciers to stream discharge is needed because streams being fed by glaciers affect the livelihoods of a large part of the world's population. Most of the streams in the Himalayas are unmonitored because in situ measurements are logistically difficult and costly. This necessitates the use of remote sensing platforms to obtain estimates of river discharge for validating hydrological models. In this study, we estimate stream discharge using cost-effective methods via repeat satellite imagery from Landsat-8 and SENTINEL-1A sensors. The methodology is based on previous studies, which show that ratio values from optical satellite bands correlate well with measured stream discharge. While similar, our methodology relies on significantly higher resolution imagery (30 m) and utilizes bands that are in the blue and near-infrared spectrum as opposed to previous studies using 250 m resolution imagery and spectral bands only in the near-infrared. Higher resolution imagery is necessary for streams where the source is a glacier's terminus because the width of the stream is often only 10s of meters. We validate our methodology using two rivers in the state of Kansas, where stream gauges are plentiful. We then apply our method to the Bhagirathi River, in the North-Central Himalayas, which is fed by the Gangotri Glacier and has a well monitored stream gauge. The analysis will later be used to couple river discharge and glacier flow and mass balance through an integrated hydrologic model in the Bhagirathi Basin.

  18. Physico-chemical, structural, pasting and thermal properties of starches of fourteen Himalayan rice cultivars.

    Science.gov (United States)

    Gani, Adil; Ashwar, Bilal Ahmad; Akhter, Gazalla; Shah, Asima; Wani, Idrees Ahmed; Masoodi, Farooq Ahmad

    2017-02-01

    Starch of fourteen rice cultivars grown in Himalayan region were evaluated for physico-chemical, structural, pasting and thermal properties. The rice cultivars selected showed a wide variation in apparent amylose content (AAC), ranging between 10.76%-26.87%, highest in CH-1039 and lowest in SKAU-292 starch. There were ten low, three intermediate and one high AAC rice. Resistant starch content varied significantly among the rice cultivars, ranging from 6.00% to 19.60%. Generally, high ACC starches presented high contents of resistant starch. Water absorption capacity (80.10-130.32%), swelling (5.73-9.61g/g) and solubility (0.037-0.090g/g) indices varied significantly among the rice cultivars. The rice starch granule morphology showed polyhedral or irregular shapes and granular sizes in the range of 1.8-6.7μm in different rice starches. Pasting profile of starch varied significantly among the rice cultivars, probably due to variations in their AAC. Thermal properties of the starches ranged considerably among different rice cultivars: onset temperature of gelatinization, T o (58.25-72.49°C), peak temperature of gelatinization, T p (69.93-93.26°C), conclusion temperature of gelatinization, T c (97.28±8.28-112.16°C) and gelatinization enthalpy ΔH G (14.29-29.63J/g). The ATR-FTIR spectroscopy of rice starches identified most of the α-1→4 glucosidic linkages within the absorption bands of 1149-1023cm -1 . Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Culturable bacteria in Himalayan glacial ice in response to atmospheric circulation

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    S. Zhang

    2007-01-01

    Full Text Available Only recently has specific attention been given to culturable bacteria in Tibetan glaciers, but their relation to atmospheric circulation is less understood yet. Here we present the results of culturable bacteria preserved in an ice core drilled from the East Rongbuk (ER glacier, Himalayas. The average concentrations of culturable bacteria are 5.0, 0.8, 0.1 and 0.7 CFU mL−1 for the glacier ice deposited during the premonsoon, monsoon, postmonsoon and winter seasons, respectively. The high concentration of culturable bacteria in ER glacier deposited during the premonsoon season is attributed to the transportation of continental dust stirred up by the frequent dust storms during spring. This is also confirmed by the spatial distribution of culturable bacteria in Tibetan glaciers. Continental dust originated from the Northwest China accounts for the high abundance of culturable bacteria in the northern Tibetan Plateau, while monsoon moisture exerts great influence on culturable bacteria with low abundance in the southern plateau. The numbers of representatives with different ARDRA patterns from RFLP analysis are 10, 15, 1 and 2 for the glacial ice deposited during the premonsoon, monsoon, postmonsoon and winter seasons, respectively, suggesting that culturable bacteria deposited in ER glacier during monsoon season are more diverse than that deposited during the other seasons, possibly due to their derivation from both marine air masses and local or regional continental sources, while culturable bacteria deposited during the other seasons are from only one possible origin that is transported by westerlies. Our results show the first report of seasonal variations of abundance and species diversity of culturable bacteria recovered from glacial ice in the Himalayas, and we suggest that microorganisms in Himalayan ice might provide a potential new proxy for the reconstruction of atmospheric circulation.

  20. Earthquake swarms near eastern Himalayan Syntaxis along Jiali Fault in Tibet: A seismotectonic appraisal

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    Basab Mukhopadhyay

    2015-09-01

    Full Text Available The seismotectonic characteristics of ten repeated earthquake swarm sequence within a seismic cluster along Jiali Fault in eastern Himalayan Syntaxis (EHS have been analysed. The swarms are spatially disposed in and around Yigong Lake (a natural lake formed by blocking of Yigong River by landslide and are characterized by low magnitude, crustal events with low to moderate b values. Ms : mb discriminant functions though indicate anomalous nature of the earthquakes within swarm but are considered as natural events that occurred under condition of high apparent stress and stress gradients. Composite fault plane solutions of selected swarms indicate strike–slip sense of shear on fault planes; solution parameters show low plunging compression and tensional axes along NW–SE and NE–SW respectively with causative fault plane oriented ENE–WSW, dipping steeply towards south or north. The fault plane is in excellent agreement with the disposition and tectonic movement registered by right lateral Jiali Fault. The process of pore pressure perturbation and resultant ‘r–t plot’ with modelled diffusivity (D = 0.12 m2/s relates the diffusion of pore pressure to seismic sequence in a fractured poro-elastic fluid saturated medium at average crustal depth of 15–20 km. The low diffusivity depicts a highly fractured interconnected medium that is generated due to high stress activity near the eastern syntaxial bent of Himalaya. It is proposed that hydro fracturing with respect to periodic pore pressure variations is responsible for generation of swarms in the region. The fluid pressure generated due to shearing and infiltrations of surface water within dilated seismogenic fault (Jiali Fault are causative factors.

  1. Pleistocene-Recent Drainage Evolution in the Western Himalayan Foreland Basin

    Science.gov (United States)

    Clift, P. D.; Giosan, L.; Macklin, M.; Carter, A.; Tabrez, A. R.

    2011-12-01

    The rivers of the upper Indus flood plains support large populations in an area where rainfall is relatively weak. Nonetheless, the region has been one in which early civilizations flourished and then dispersed, most notably the Indus Valley or Harappan Culture. We investigated potential links between human settlement and drainage evolution by drilling abandoned and filled river channels on the northern edge of the Thar Desert to see how they have evolved. Pb isotope data from single K-feldspar grains from Holocene and Pleistocene sands showed that the channels were sourced from Himalayan rivers before and at 6-8 ka, but that after that time the proportion of high isotopic ratio grains rose, indicating increased contribution from the Thar Desert dunes prior to ~4.5 ka when flow in the Ghaggar-Hakra ceased entirely. U-Pb dating of single zircon sand grains confirms this general pattern. Grain ages <300 Ma are typical of the Thar Desert and become more common around 6-8 ka as the river flux decreased and desert began to encroach. Zircons ages at ~1900 Ma can be linked to a westward flow of the Yamuna River into the Indus but this flow may have finished as early as 49 ka, so that this capture does not affect the Harappan Culture. After this time the Sutlej and Beas River flowed through the region until they were both captured away to the north prior to 6-8 ka. The Harappan centers on the north of the Thar Desert likely dispersed because of unpredictable water supply as the monsoon weakened and because the flow of major rivers had ceased well before 4 ka.

  2. Assessment of Antioxidant Properties in Fruits of Myrica esculenta: A Popular Wild Edible Species in Indian Himalayan Region

    OpenAIRE

    Rawat, Sandeep; Jugran, Arun; Giri, Lalit; Bhatt, Indra D.; Rawal, Ranbeer S.

    2011-01-01

    Crude extract of Myrica esculenta fruits, a wild edible species of Indian Himalayan Region, was evaluated for phenolic compounds and antioxidant properties. Results revealed significant variation in total phenolic and flavonoid contents across populations. Among populations, total phenolic content varied between 1.78 and 2.51 mg gallic acid equivalent/g fresh weight (fw) of fruits and total flavonoids ranged between 1.31 and 1.59 mg quercetin equivalent/g fw. Antioxidant activity determined b...

  3. K/Ar hornblende ages from the higher Himalaya: implications for India-Asia collision and Himalayan metamorphosis

    International Nuclear Information System (INIS)

    Sorkhabi, R.B.; Stump, A.K.; Jain, A.K.; Manickavasagam, R.M.; Nishimura Susumu

    1993-01-01

    Two amphibolite samples from the Higher Himalayan Crystalline (HHC) belt from the Suru Valley, Zanskar, have yielded Eocene K/Ar hornblende cooling ages between 40 and 45 Ma, thus indicating much older peak metamorphic conditions in northern parts of the Indian Plate. These ages are in conformity with almost identical ages from metamorphic complexes across the Nanga Parbat syntaxis in Pakistan and reveal a 65 to 70-Ma collision phase of the Indian indentor in the NW-Himalaya. (author). 21 refs., 2 figs

  4. Sighting of Tibetan Wolf Canis lupus chanko in the Greater Himalayan range of Nanda Devi Biosphere Reserve, Uttarakhand, India: a new record

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    T. Bhattacharya

    2010-11-01

    Full Text Available In India, the Tibetan Wolf Canis lupus chanko is distributed in the Trans-Himalaya region. We report the sighting of Tibetan Wolf from the Bedini-Ali area that falls in the Greater Himalayan range and is located in the transition zone of Nanda Devi Biosphere Reserve in Uttarakhand, India. We hypothesise that the Tibetan wolf inhabiting the Trans-Himalayan areas of Nanda Devi Biosphere Reserve would have moved south-west around the alpine regions of Nanda Devi National Park towards Bedini-Ali, following migratory livestock herds that graze in these areas during summer.

  5. Cambrian ophiolite complexes in the Beishan area, China, southern margin of the Central Asian Orogenic Belt

    Science.gov (United States)

    Shi, Yuruo; Zhang, Wei; Kröner, Alfred; Li, Linlin; Jian, Ping

    2018-03-01

    We present zircon ages and geochemical data for Cambrian ophiolite complexes exposed in the Beishan area at the southern margin of the Central Asian Orogenic Belt (CAOB). The complexes consist of the Xichangjing-Xiaohuangshan and Hongliuhe-Yushishan ophiolites, which both exhibit complete ophiolite stratigraphy: chert, basalt, sheeted dikes, gabbro, mafic and ultramafic cumulates and serpentinized mantle peridotites. Zircon grains of gabbro samples yielded 206Pb/238U ages of 516 ± 8, 521 ± 4, 528 ± 3 and 535 ± 6 Ma that reflect the timing of gabbro emplacement. The geochemical data of the basaltic rocks show enrichment in large-ion lithophile elements and depletion in the high field strength elements relative to normal mid-oceanic ridge basalt (NMORB) in response to aqueous fluids or melts expelled from the subducting slab. The gabbro samples have higher whole-rock initial 87Sr/86Sr ratios and lower positive εNd(t) values than NMORB. These geochemical signatures resulted from processes or conditions that are unique to subduction zones, and the ophiolites are therefore likely to have formed within a supra-subduction zone (SSZ) environment. We suggest that the Cambrian ophiolite complexes in the Beishan area formed within a SSZ setting, reflecting an early Paleozoic subduction of components of the Paleo-Central Asian Ocean and recording an early Paleozoic southward subduction event in the southern CAOB along the northern margin of the Tarim and North China Cratons.

  6. Polyphase Neoproterozoic orogenesis within the east Africa- Antarctica orogenic belt in central and northern Madagascar

    Science.gov (United States)

    Key, R.M.; Pitfield, P.E.J.; Thomas, Ronald J.; Goodenough, K.M.; Waele, D.; Schofield, D.I.; Bauer, W.; Horstwood, M.S.A.; Styles, M.T.; Conrad, J.; Encarnacion, J.; Lidke, D.J.; O'connor, E. A.; Potter, C.; Smith, R.A.; Walsh, G.J.; Ralison, A.V.; Randriamananjara, T.; Rafahatelo, J.-M.; Rabarimanana, M.

    2011-01-01

    Our recent geological survey of the basement of central and northern Madagascar allowed us to re-evaluate the evolution of this part of the East Africa-Antarctica Orogen (EAAO). Five crustal domains are recognized, characterized by distinctive lithologies and histories of sedimentation, magmatism, deformation and metamorphism, and separated by tectonic and/or unconformable contacts. Four consist largely of Archaean metamorphic rocks (Antongil, Masora and Antananarivo Cratons, Tsaratanana Complex). The fifth (Bemarivo Belt) comprises Proterozoic meta-igneous rocks. The older rocks were intruded by plutonic suites at c. 1000 Ma, 820-760 Ma, 630-595 Ma and 560-520 Ma. The evolution of the four Archaean domains and their boundaries remains contentious, with two end-member interpretations evaluated: (1) all five crustal domains are separate tectonic elements, juxtaposed along Neoproterozoic sutures and (2) the four Archaean domains are segments of an older Archaean craton, which was sutured against the Bemarivo Belt in the Neoproterozoic. Rodinia fragmented during the early Neoproterozoic with intracratonic rifts that sometimes developed into oceanic basins. Subsequent Mid- Neoproterozoic collision of smaller cratonic blocks was followed by renewed extension and magmatism. The global 'Terminal Pan-African' event (560-490 Ma) finally stitched together the Mid-Neoproterozoic cratons to form Gondwana. ?? The Geological Society of London 2011.

  7. Three-dimensional thermoluminescence spectra of different origin quartz from Altay Orogenic belt, Xinjiang, China

    International Nuclear Information System (INIS)

    Tan Kaixuan; Liu Zehua; Zeng Sheng; Liu Yan; Xie Yanshi; Rieser, Uwe

    2009-01-01

    Three-dimensional thermoluminescence spectra are measured for different types of geological origin quartz from the Altay orogenic belt, northern Xinjiang, China. The results show striking differences which appear to be characteristic of their geological origin. Granitic quartz is dominated by emission bands at 420-430 nm, 550-560 nm, at a temperature of 170 deg. C. Pegmatite quartz is characterized by an intense 480 nm emission band at 170 deg. C. Volcanic quartz has exclusive UV (340-360 nm) and violet (410-430 nm) emission bands. Hydrothermal quartz exhibits very different TL spectral characteristics because of different hydrothermal activity and mineralization. Only one TL peaks at 485 nm/170 deg. C was observed in sedimentary quartz. An intense 730 nm emission band observed at 170 deg. C considered generally to be characteristics of feldspar was observed in quartz from granite and hydrothermal Au-bearing quartz. This TL peak is probably related to the centre of [FeO 4 ] 0 on an Si site. All samples show an intense 990-1000 nm emission band at 330 deg. C. Identical types of quartz formed in different regions or different geological and tectonic settings can also exhibit striking differences in TL spectra.

  8. Uraniferous alaskitic granites with special reference to the Damara Orogenic Belt

    International Nuclear Information System (INIS)

    Toens, P.D.; Corner, B.

    1980-10-01

    The control and patterns of uranium mineralisation in the alaskitic granites of the Damara Orogenic Belt are discussed. The polyphase Damara metamorphism produced high-grade metamorphic assemblages, migmatites and syn-, late-, and post-tectonic anatectic granites through reactivation of the basement and overlying Damara rocks. During anatexis the incompatible elements, particularly the uranium derived from these formations, were incorporated into the melts which then rose, in an attempt to attain gravitational equilibrium, by varying distances depending on the depth of origin of the melts, on their water content and on the availability of tensional environments. Fractional crystallisation during ascent and increased water content concentrated the uranium into residual melts which finally crystallised as alaskitic pegmatitic granite. Structural episodes played an important part in the emplacement of the uraniferous granites and the presence of marble bands was an important factor in not only providing a structural trap for the alaskitic melts and associated uranium-rich volatiles, but also by leading to the boiling of the magma and the subsequent deposition of uranium. The present-day level of erosion is considered to be an important factor contributing to the preservation of many of the uraniferous granite bodies. In addition it is suggested that secondary enrichment occurring above the water-table in the prevailing desert environment is an important criterion in enriching the tenor of mineralisation to ore grades. The exploration techniques necessary for the location of uraniferous granite bodies are briefly outlined [af

  9. Partial melting of deeply subducted eclogite from the Sulu orogen in China.

    Science.gov (United States)

    Wang, Lu; Kusky, Timothy M; Polat, Ali; Wang, Songjie; Jiang, Xingfu; Zong, Keqing; Wang, Junpeng; Deng, Hao; Fu, Jianmin

    2014-12-17

    We report partial melting of an ultrahigh pressure eclogite in the Mesozoic Sulu orogen, China. Eclogitic migmatite shows successive stages of initial intragranular and grain boundary melt droplets, which grow into a three-dimensional interconnected intergranular network, then segregate and accumulate in pressure shadow areas and then merge to form melt channels and dikes that transport magma to higher in the lithosphere. Here we show, using zircon U-Pb dating and petrological analyses, that partial melting occurred at 228-219 Myr ago, shortly after peak metamorphism at 230 Myr ago. The melts and residues are complimentarily enriched and depleted in light rare earth element (LREE) compared with the original rock. Partial melting of deeply subducted eclogite is an important process in determining the rheological structure and mechanical behaviour of subducted lithosphere and its rapid exhumation, controlling the flow of deep lithospheric material, and for generation of melts from the upper mantle, potentially contributing to arc magmatism and growth of continental crust.

  10. Organic molecular paleohypsometry: A new approach to reconstructing the paleoelevation history of an orogen

    Science.gov (United States)

    Hren, M. T.; Ouimet, W. B.

    2017-12-01

    Paleoelevation data is critical to understanding the links and feedbacks between rock-uplift and erosion yet few approaches have proved successful in quantifying changes in paleoelevation rapidly eroding, tropical landscapes. In addition, quantitative methods of reconstructing paleoelevation from marine sedimentary archives are lacking. Here we present a new approach to quantifying changes in paleoelevation that is based on the geochemical signature of organic matter exported via the main river networks of an orogen. This new approach builds on fundamentals of stable isotope paleoaltimetry and is akin to the theory behind cosmogenic isotope records of catchment-integrated erosion. Specifically, we utilize predictable patterns of precipitation and organic molecular biomarker stable isotopes to relate the hypsometry of organic matter in a catchment to the geochemical signal in exported organic carbon. We present data from two sites (the cold temperate White Mountains of New Hampshire, USA and the tropical, rapidly eroding landscape of Taiwan) to demonstrate this relationship between exported carbon geochemistry and catchment hypsometry and the validity of this approach.

  11. Controlling factors of spatial and temporal preservation of the geochronological signal in sediments during an orogenic cycle

    Science.gov (United States)

    Rat, Juliette; Mouthereau, Frédéric; Bernet, Matthias; Brichau, Stéphanie; Balvay, Mélanie; Garzanti, Eduardo; Ando, Sergio

    2017-04-01

    Detrital content of sediments preserved in basins provide constraints on the nature of source rocks, dynamics of sediment transport, and potentially on tectonics and climate changes. U-Pb dating method on detrital zircon is ideally suited for provenance studies due to the ability of U-Pb age data to resist several orogenic cycles. However, with the aim to track sediment source evolution over a single orogenic cycle and determine characteristic time and parameters controlling the geochronological signal preservation throughout the cycle from rifting, mountain building to post-collision evolution, low-temperature thermochronology combined with sediment petrography are more appropriate than the U-Pb dating approach taken alone. To better understanding processes at play in the long-term geochronological signal preservation we focus on the sediment record associated with the Iberia plate tectonic evolution, which is part of the OROGEN research project, co-financed by BRGM, TOTAL & CNRS. The Iberian plate recorded a period of extension in the Late Jurassic, followed during the Early Cretaceous (Aptian-Albian) by a major thinning event documented by thick syn-rift sediments in intraplate basins and plate-scale heating/cooling of the Iberia crust, as argued by published fission track ages. Paleogeographic reconstructions that are based on stratigraphic and lithofacies analyses in northern Iberia (Iberian Range, Pyrenees and Basque-Cantabrians Range), describe a large domain of continental/fluvial and shallow-marine siliciclastic deposition. The related detrital content was then recycled during the subsequent Pyrenean orogenic phase in the Ebro foreland basin, and eventually transfer to the Mediterranean realm during post-orogenic re-excavation of the Ebro basin. In this study, we complete the published time-temperature paths in the mesozoic syn-rift basins by providing new thermo-chronological analyses of well-dated syn-collision and post-collision stratigraphic sections

  12. Calcite twinning strain variations across the Proterozoic Grenville orogen and Keweenaw-Kapuskasing inverted foreland, USA and Canada

    Directory of Open Access Journals (Sweden)

    John P. Craddock

    2017-11-01

    Full Text Available We report the calcite twinning strain results of a traverse across the Grenville orogen from Parry Sound, Ontario (NW to Ft. Ann, New York (SE, including the younger, adjacent Ordovician Taconic allochthon. Fifty four carbonates (marbles, calcite veins, Ordovician limestone were collected resulting in 68 strain analyses on mechanically twinned calcite (n = 2337 grains across the Central Gneiss Belt (CGB; 3 samples, the Central Metasedimentary Belt (CMB; 27 samples, the Central Granulite Terrane (CGT; Adirondack's; 13 samples and the Ottawan Orogenic Lid (OOL; 11 samples. Twinning strains in the greenschist-grade OOL marbles preserve N–S shortening and U-Pb titanite ages (∼1150 Ma; n = 4 document these marbles formed during the Shawinigan (1190–1140 Ma part of the Grenville orogen. From northwest to southeast, the Ottawan (1095–1020 Ma twinning strain is dominantly a layer-parallel shortening fabric oriented N–S (Parry Sound, then becomes parallel to the Grenville thrust direction (NW–SE across the CMB to the Adirondack Highlands where the sub-horizontal shortening strain becomes margin-parallel (SW–NE. Within the regional sample suite there are two areas studied in detail, the Bancroft shear zone (n = 11 and a roadcut on the southeast side of the Adirondack Mountains (Ft. Ann, NY; n = 8. Marbles from the Bancroft shear zone contain calcite grains with 2 sets of twin lamellae (e1 and e2. The better-developed e1 sets (n = 406 record a horizontal fabric oriented NW–SE whereas the younger e2 lamellae (n = 146 preserve a margin-parallel (SW–NE horizontal fabric. Both the e1 and e2 strains record an overprint vertical shortening strain (NEV, perhaps related to extensional orogenic collapse. We also report an Ottawan orogen-aged granoblastic mylonite (1093 Ma, U-Pb zircon; 1102 Ma Ar-Ar biotite in the Keweenaw thrust hanging wall 500 km inboard of the Grenville front and interpret the relations of Grenville

  13. Generation of post-collisional normal calc-alkaline and adakitic granites in the Tongbai orogen, central China

    Science.gov (United States)

    Zhang, Wen-Xiang; Zhu, Liu-Qin; Wang, Hao; Wu, Yuan-Bao

    2018-01-01

    Post-collisional granites are generally generated by partial melting of continental crust during orogenic extension. The occurrence of normal calc-alkaline granites following adakitic granites in a collisional orogen is frequently supposed as a sign of tectonic regime transition from compression to extension, which has been debated yet. In this paper, we present a comprehensive study of zircon U-Pb ages, Hf-O isotopes, as well as whole-rock major and trace elements and Sr-Nd isotopes, for Tongbai and Jigongshan post-collisional granitic plutons in the Tongbai orogen. Zircon U-Pb dating yields intrusion ages of ca. 140 and 135 Ma for the Tongbai and Jigongshan plutons, respectively, suggesting they are post-collisional granites. These granites are high-K calc-alkaline series, metaluminous to weakly peraluminous with A/CNK ratios of 0.85-1.08. The Tongbai gneissic granites are normal calc-alkaline granite, having variable SiO2 (61.93-76.74 wt%) and Sr/Y (2.9-38.9) and (La/Yb)N (1.7-30.1) ratios with variably negative Eu anomalies (0.41-0.92). They have relatively high initial Sr isotope ratios of 0.707571 to 0.710317, and low εNd(t) (- 15.74 to - 11.09) and εHf(t) (- 17.6 to - 16.9) values. Their Nd and Hf model ages range from 2.2 to 1.8 Ga and 2.3 to 2.2 Ga. On the contrary, the Jigongshan granites show higher SiO2 (66.56-72.11 wt%) and Sr/Y (30.1-182.0) and (La/Yb)N (27.4-91.4) ratios with insignificant Eu anomalies (0.73-1.00), belonging to adakitic granite. They have Isr = 0.707843-0.708366, εNd(t) = - 19.83 to - 17.59, and εHf(t) = - 26.0 to - 23.5. Their Nd and Hf model ages vary from ca. 2.5 to 2.4 Ga and ca. 2.8 to 2.6 Ga. The Tongbai and Jigongshan granites are characterized by mantle-like zircon δ18O values (5.17-5.46‰). These geochemical features suggest that the Tongbai and Jigongshan granites were derived from partial melting of Paleoproterozoic and Archean continental crust, respectively. Fractional crystallization affected the geochemical

  14. A revised oxygen barometry in sulfide-saturated magmas and application to the Permian magmatic Ni-Cu deposits in the southern Central Asian Orogenic Belt

    Science.gov (United States)

    Mao, Ya-Jing; Qin, Ke-Zhang; Barnes, Stephen J.; Ferraina, Clément; Iacono-Marziano, Giada; Verrall, Michael; Tang, Dongmei; Xue, Shengchao

    2017-11-01

    Oxygen fugacity is a key parameter in controlling the petrogenesis of mafic-ultramafic rocks and their associated sulfide mineralization, especially in convergent settings. This study uses new and previously published experimental data on olivine-sulfide pairs to reparameterize an expression for oxygen barometry using the distribution coefficient K D FeNi for Fe-Ni exchange between olivine and sulfide. We derive a new expression, ΔQFM = (9.775 + 0.416 • C Ni - K D FeNi)/4.308, where ΔQFM denotes divergence from the fayalite-magnetite-quartz buffer. The revised oxygen barometry has been applied to the Permian magmatic Ni-Cu deposits in the Central Asian Orogenic Belt, NW China. The Ni-Cu deposits in the East Tianshan—North Tianshan, Central Tianshan, and Beishan—are considered as a single mineral system, whereas the spatially separated deposits in the East Junggar are considered as a separate system. The deposit of the East Tianshan group exhibits a large range of oxygen fugacity (QFM - 2 to QFM + 1) and Ni tenor (metal concentration in pure sulfide, 5 to 16 wt%). The Poyi and Huangshannan deposits contain high-Ni tenor sulfides, varying from 12 to 16 wt%. The relatively high Fo values (> 85 mol%) and Ni contents (> 2000 ppm) in olivine of these deposits indicate that the high-Ni tenor sulfides were segregated from less differentiated high-Ni magmas that also had relatively high oxygen fugacity ( QFM + 1). The remaining Ni-Cu deposits in the East Tianshan—the Huangshandong, Huangshanxi, Hulu, Tulaergen, Tudun, and Xiangshanzhong deposits—have intermediate Ni tenors (5-8 wt%). These sulfides correspond to intermediate Fo values (80-84 mol%) and Ni contents (700-1400 ppm) in the coexisting olivine, illustrating that they were segregated from magmas with lower Ni contents thought to be the result of a large amount (15-20%) of olivine fractionation at depth. These magmas are more reduced (- 2 fugacity and Ni tenor in the Permian Ni-Cu deposits in the Central

  15. Use of Satellite and In Situ Reflectance Data for Lake Water Color Characterization in the Everest Himalayan Region

    Directory of Open Access Journals (Sweden)

    Erica Matta

    2017-02-01

    Full Text Available This study applied remote sensing techniques to the study of water color in Himalayan glacial lakes as a proxy of suspended solid load. In situ measurements gathered in 5 lakes in October 2014 during satellite data acquisition enabled the characterization of water reflectance and clarity and supported image processing. Field data analysis led to a distinction between 3 water colors and a consequent lake water color classification on a regional scale from Landsat-8 data previously corrected for atmospheric and adjacency effects. Several morphometric parameters (lake size and shape, distance between lake and glacier were also computed for the lakes thus classified. The results showed spatial and temporal variations in lake water color, suggestive of relationships between glacier shrinkage and the presence of brighter and more turbid water. A finer-scale analysis of the spatial variability of water reflectance on Chola Lake (based on GeoEye-1 data captured on 18 October 2014 showed the contribution of water component absorption from the inflow. Overall, the findings support further research to monitor Himalayan lakes using both Landsat-8 and Sentinel-2 (with its improved resolutions.

  16. Widespread albedo decreasing and induced melting of Himalayan snow and ice in the early 21st century.

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    Jing Ming

    Full Text Available The widely distributed glaciers in the greater Himalayan region have generally experienced rapid shrinkage since the 1850s. As invaluable sources of water and because of their scarcity, these glaciers are extremely important. Beginning in the twenty-first century, new methods have been applied to measure the mass budget of these glaciers. Investigations have shown that the albedo is an important parameter that affects the melting of Himalayan glaciers.The surface albedo based on the Moderate Resolution Imaging Spectroradiometer (MODIS data over the Hindu Kush, Karakoram and Himalaya (HKH glaciers is surveyed in this study for the period 2000-2011. The general albedo trend shows that the glaciers have been darkening since 2000. The most rapid decrease in the surface albedo has occurred in the glacial area above 6000 m, which implies that melting will likely extend to snow accumulation areas. The mass-loss equivalent (MLE of the HKH glacial area caused by surface shortwave radiation absorption is estimated to be 10.4 Gt yr-1, which may contribute to 1.2% of the global sea level rise on annual average (2003-2009.This work probably presents a first scene depicting the albedo variations over the whole HKH glacial area during the period 2000-2011. Most rapidly decreasing in albedo has been detected in the highest area, which deserves to be especially concerned.

  17. Widespread albedo decreasing and induced melting of Himalayan snow and ice in the early 21st century.

    Science.gov (United States)

    Ming, Jing; Wang, Yaqiang; Du, Zhencai; Zhang, Tong; Guo, Wanqin; Xiao, Cunde; Xu, Xiaobin; Ding, Minghu; Zhang, Dongqi; Yang, Wen

    2015-01-01

    The widely distributed glaciers in the greater Himalayan region have generally experienced rapid shrinkage since the 1850s. As invaluable sources of water and because of their scarcity, these glaciers are extremely important. Beginning in the twenty-first century, new methods have been applied to measure the mass budget of these glaciers. Investigations have shown that the albedo is an important parameter that affects the melting of Himalayan glaciers. The surface albedo based on the Moderate Resolution Imaging Spectroradiometer (MODIS) data over the Hindu Kush, Karakoram and Himalaya (HKH) glaciers is surveyed in this study for the period 2000-2011. The general albedo trend shows that the glaciers have been darkening since 2000. The most rapid decrease in the surface albedo has occurred in the glacial area above 6000 m, which implies that melting will likely extend to snow accumulation areas. The mass-loss equivalent (MLE) of the HKH glacial area caused by surface shortwave radiation absorption is estimated to be 10.4 Gt yr-1, which may contribute to 1.2% of the global sea level rise on annual average (2003-2009). This work probably presents a first scene depicting the albedo variations over the whole HKH glacial area during the period 2000-2011. Most rapidly decreasing in albedo has been detected in the highest area, which deserves to be especially concerned.

  18. The Rio Pardo salient, northern Araçuaí orogen: an example of a complex basin-controlled fold-thrust belt curve

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    Eliza Peixoto

    Full Text Available ABSTRACT: The Rio Pardo salient, the large antitaxial curve described by the Araçuaí fold-and-thrust belt along the southeastern edge of the São Francisco craton, is one of the most prominent and one of the least studied features of the Brasiliano Araçuaí-West Congo orogenic system (AWCO. In addition to the Archean/Paleoproterozoic basement, the salient is comprised of metasedimentary rocks mainly from the Neoproterozoic Macaúbas Group and the Salinas Formation. Its western limb occupies a portion of the Espinhaço ridge, where the NS-trending structures of the Araçuaí belt progressively curve NE and E, thereby defining the hinge zone along the Serra Geral on the Minas-Bahia boundary. The eastern limb is NW-trending and marked by a major shear zone. In models postulated to generate the AWCO through the closure of the Neoproterozoic Macaúbas basin, this large curve plays a critical kinematic role. Yet, in spite of this, its development is still not fully understood. How did this curve originate? Which factors controlled its generation? Our field study performed in the northern Araçuaí orogen characterized the kinematic picture of the salient, and led to a model that addresses these questions. The results we obtained indicate that the Rio Pardo salient developed in response to four deformation phases. The contractional D1 and D2 phases are coaxial and responsible for a craton-directed tectonic transport along the salient’s outer arc, which is coupled with an overall southward motion of the inner arc, thereby giving rise to a rather complex kinematic picture. Furthermore, structures of the D1/D2 phases define a zigzag pattern with alternating NE- and NW-trending segments along the salient’s leading edge. Along the NE-trending segments, the metasedimentary rocks are thrust northwestwards on top of the craton basement, while along the NW-trending segments, the supracrustal rocks are displaced along dextral to reverse

  19. Orogenic potassic mafic magmatism, a product of alkaline-peraluminous mixing ? Variscan 'calc-alkaline' rocks from the Central Iberian and Ossa Morena Zones, Central Spain.

    Science.gov (United States)

    Scarrow, Jane H.; Cambeses, Aitor; Bea, Fernando; Montero, Pilar; Molina, José F.; Moreno, Juan Antonio

    2013-04-01

    Orogenic magmatic rocks provide information about mantle and crust melt-generation and -interaction processes. In this context, minor potassic mafic stocks which are formed of enriched mantle and crustal components and are common as late-orogenic intrusions in granitic plutons give insight into the timing of new crust formation and crustal recycling. Potassic mafic stocks are prevalent, albeit low volume, constituents of granite batholiths all through the European Variscan (350-280 Ma). In the Central Iberia Zone, Spanish Central System, crustal-melt, S-type, granitoid plutons are intruded by minor concomitant ultramafic-intermediate appinitic-vaugneritic stocks. Notwithstanding their whole-rock calc-alkaline composition, the stocks apparently did not have a subduction-related origin. Recent studies have attributed their genesis to mixing of alkaline mantle and peraluminous crustal melts. Their primary alkaline character, as indicated by amphibole and biotite mineral chemistry data, points, rather, towards an extension-related genesis. In the Ossa Morena Zone, south of the Central Iberian Zone, the igneous rocks also have a whole-rock calc-alkaline composition which has been considered to be the result of northward subduction of the South Portuguese Zone. Nevertheless, identification of a 'sill' of significant volume of mafic magma in the middle crust, the ´IBERSEIS reflective body', in a seismic profile across the Ossa Morena and South Portuguese Zones has cast doubt upon the calc-alkaline magmatism-subduction model; leading, instead, to the magmatism being attributed to intra-orogenic extension related to a mantle plume active from 340 Ma to 330 Ma. The aim here, then, is to reinvestigate the petrogenesis and age of the calc-alkaline rocks of the Ossa Morena Zone to determine their tectonomagmatic context be it subduction-, plume- or extension-related, and establish what they may reveal about mantle-crust interactions. Focussing, initially, on the Valencia del

  20. Thermochronometry Across the Austroalpine-Pennine Boundary, Central Alps, Switzerland: Orogen-Perpendicular Normal Fault Slip on a Major "Overthrust" and Its Implications for Orogenesis

    Science.gov (United States)

    Price, Jason B.; Wernicke, Brian P.; Cosca, Michael A.; Farley, Kenneth A.

    2018-03-01

    Fifty-one new and 309 published thermochronometric ages (nine systems with closure temperatures ranging from 450 to 70°C) from the Graubünden region of the Central Alps demonstrate that a pronounced thermal mismatch between the Austroalpine allochthon (Alpine "orogenic lid") and the Pennine zone persisted until at least 29 Ma and, allowably, until circa 18 Ma. The observed mismatch supports previous suggestions that the famous "overthrust" between the Austroalpine allochthon and the Pennine zone, historically regarded as primarily an Eocene top-north thrust fault, is in fact primarily an Oligocene-Miocene normal fault that has a minimum of 60 km of displacement with top-south or top-southeast sense of shear. Two hallmarks of Alpine geology, deposition of the foredeep Molasse and emplacement of the Helvetic nappes, appear to be coeval, peripheral manifestations of crustal thickening via the interposition of the Pennine zone as a northward intruding wedge between the Austroalpine "lid" and the European cratonic margin, with the Helvetic system (European margin) acting as the "floor" of the wedge. We presume the Penninic wedge is driven by the buoyant rise of subducted crust no longer able to remain attached to the descending slab. If so, emplacement of the Pennine wedge could have occurred mainly after Adria was juxtaposed against cratonic Europe.

  1. Thermochronometry across the Austroalpine-Pennine boundary, Central Alps, Switzerland: Orogen-perpendicular normal fault slip on a major ‘overthrust’ and its implications for orogenesis

    Science.gov (United States)

    Price, Jason B.; Wernicke, Brian P.; Cosca, Michael A.; Farley, Kenneth A.

    2018-01-01

    Fifty‐one new and 309 published thermochronometric ages (nine systems with closure temperatures ranging from ~450 to 70°C) from the Graubünden region of the Central Alps demonstrate that a pronounced thermal mismatch between the Austroalpine allochthon (Alpine “orogenic lid”) and the Pennine zone persisted until at least 29 Ma and, allowably, until circa 18 Ma. The observed mismatch supports previous suggestions that the famous “overthrust” between the Austroalpine allochthon and the Pennine zone, historically regarded as primarily an Eocene top‐north thrust fault, is in fact primarily an Oligocene‐Miocene normal fault that has a minimum of 60 km of displacement with top‐south or top‐southeast sense of shear. Two hallmarks of Alpine geology, deposition of the foredeep Molasse and emplacement of the Helvetic nappes, appear to be coeval, peripheral manifestations of crustal thickening via the interposition of the Pennine zone as a northward intruding wedge between the Austroalpine “lid” and the European cratonic margin, with the Helvetic system (European margin) acting as the “floor” of the wedge. We presume the Penninic wedge is driven by the buoyant rise of subducted crust no longer able to remain attached to the descending slab. If so, emplacement of the Pennine wedge could have occurred mainly after Adria was juxtaposed against cratonic Europe.

  2. Mineral potential tracts for orogenic, Carlin-like, and epithermal gold deposits in the Islamic Republic of Mauritania, (phase V, deliverable 69): Chapter H in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

    Science.gov (United States)

    Goldfarb, Richard J.; Marsh, Erin; Anderson, Eric D.; Horton, John D.; Finn, Carol A.; Beaudoin, Georges

    2015-01-01

    The gold resources of Mauritania presently include two important deposits and a series of poorly studied prospects. The Tasiast belt of deposits, which came into production in 2007, is located in the southwestern corner of the Rgueïbat Shield and defines a world-class Paleoproterozoic(?) orogenic gold ore system. The producing Guelb Moghrein deposit occurs along a shear zone in Middle Archean rocks at the bend in the Northern Mauritanides and is most commonly stated to be an iron oxide-copper-gold (IOCG) type of deposit, although it also has some important characteristics of orogenic gold and skarn deposits. Both major deposits are surrounded by numerous prospects that show similar mineralization styles. The Guelb Moghrein deposit, and IOCG deposit types in general are discussed in greater detail in a companion report by Fernette (2015). In addition, many small gold prospects, which are probably orogenic gold occurrences and are suggested to be early Paleozoic in age, occur along the length of Southern Mauritanides. Existing data indicate the gold deposits and prospects in Mauritania have a sulfide assemblage most commonly dominated by pyrrhotite and chalcopyrite, and have ore-related fluids with apparently high salinities.

  3. Palaeozoic arc magmatism in the Central Asian Orogenic Belt of Kazakhstan: SHRIMP zircon ages and whole-rock Nd isotopic systematics

    Science.gov (United States)

    Kröner, A.; Hegner, E.; Lehmann, B.; Heinhorst, J.; Wingate, M. T. D.; Liu, D. Y.; Ermelov, P.

    2008-03-01

    Early Palaeozoic tonalite to granodiorite intrusions in northern Kazakhstan are associated with lode gold mineralization and have SHRIMP zircon ages of 457.3 ± 6.6 Ma (Aksu), 452.9 ± 5.6 Ma and 447.4 ± 5.4 Ma (both Zholymbet). The Stepnyak intrusion contains large xenoliths with an age of 480.6 ± 5.0 Ma. One early Palaeozoic zircon from a porphyritic diorite at Stepnyak has a core with a near-concordant 207Pb/ 206Pb age of 3888 ± 1.5 Ma, whereas other xenocrystic grains are between 983 and 2698 Ma old. The early Archaean age is probably inherited from unexposed basement of the Kokchetav Massif and represents the oldest crustal material so far known from the Asian continent. It appears that the Aksu, Zholimbet and Stepnyak granitoids were emplaced in the late Ordovician in an Andean- or Japan-type continental arc environment on the margin of the Kokchetav Massif. Late Palaeozoic granitoids in central Kazakhstan have Devonian zircon ages of 407.1 ± 3.9, 381.1 ± 3.1 and 369.2 ± 4.9 Ma, whereas the youngest sample from the Topar Massif has a late Carboniferous emplacement age of 314.1 ± 5.1 Ma. Initial ɛNd values range from +5 to -1 corresponding to Nd-model ages of 1.1-0.6 Ga. The isotopic data are similar to those of other Phanerozoic granitoids of the Central Asian Orogenic Belt and corroborate melting of predominantly juvenile crustal protoliths. Our data also confirm that Devonian and Carboniferous arc magmatism in central Kazakhstan assimilated older and already accreted island arc systems, yet is derived from primitive sources, probably in a subduction setting. The range of ɛNd values with corresponding Nd mean crustal residence ages in the range of 0.6-1.1 Ga for most samples indicates variable recycling of late Proterozoic largely juvenile continental crust in the formation of the Palaeozoic magmatic arcs of central Kazakhstan. The orogenic evolution terminated with Permian anorogenic, rift-related alkaline granite magmatism ( ɛNd = +2 to +8) which

  4. Time-space focused intrusion of genetically unrelated arc magmas in the early Paleozoic Ross-Delamerian Orogen (Morozumi Range, Antarctica)

    Science.gov (United States)

    Rocchi, S.; Di Vincenzo, G.; Dini, A.; Petrelli, M.; Vezzoni, S.

    2015-09-01

    The growth of continental crust in accretionary orogenic belts takes place through repeated cycles of subduction-accretion of rock units from continental and oceanic magmatic arcs, supra-subduction zone backarcs and forearcs loaded with continent-derived materials. An ancient example relevant to magmatic arc accretion models is represented by the remnants of the Cambrian-Ordovician Ross Orogen in the Morozumi Range, Victoria Land (Antarctica). There, late Neoproterozoic phyllites host an intrusive complex which preserves a remarkably uncommon record of genetically unrelated magma pulses emplaced under a variable stress regime in a short time span: (1) a dominant K-feldspar-phyric granite, (2) fine-grained dioritic stocks and dykes, (3) a peraluminous granite; and (4) a tonalitic-granodioritic dyke swarm. Laserprobe U-Pb zircon dates cluster at late Cambrian times for all these units, yet they carry differential cargoes of relict cores. Unique geochemical-isotopic signatures for both the less evolved magmas (diorite and dyke tonalite) and the most acidic ones (granite and peraluminous granite) indicate that each one of them originated from distinct sources at depth. Additionally, field relationships and chemical evolutionary trends testify for a variety of shallow level open-system processes, such as magma mingling/mixing between diorite and main granite magmas, as well as progressive incorporation of the host schists by the dyke tonalite magma. In summary, crustal growth in the Morozumi intrusive complex was contributed by fresh mantle magma issuing from the metasomatised mantle wedge, while the production of other melts did recycle different crustal portions/layers: the main granite derived from Grenville-age granulitic lower crust; the peraluminous granite from late Proterozoic upper crust, and the tonalite magmas derived from subduction erosion-enriched subarc mantle and evolved by ingestion of local metasedimentary rocks. Overall, the Morozumi intrusive complex

  5. Himalayan Lake- and River-Impacting Landslides and Ice Avalanches: Some So Deadly, Some No Problem

    Science.gov (United States)

    Kargel, J. S.; Karki, A.; Haritashya, U. K.; Shugar, D. H.; Harrison, S.

    2017-12-01

    the same area. Factors for landslide triggering of glacial lake outburst floods (GLOFs) include some of the same factors, but the mass/energy input rate into the lake, the lake's shape and length, and moraine dam properties are also important in GLOF triggering. Himalayan examples will illustrate some hazard factors.

  6. Blood Pressure and Altitude: An Observational Cohort Study of Hypertensive and Nonhypertensive Himalayan Trekkers in Nepal.

    Science.gov (United States)

    Keyes, Linda E; Sallade, Thomas Douglas; Duke, Charles; Starling, Jennifer; Sheets, Alison; Pant, Sushil; Young, David S; Twillman, David; Regmi, Nirajan; Phelan, Benoit; Paudel, Purshotam; McElwee, Matthew; Mather, Luke; Cole, Devlin; McConnell, Theodore; Basnyat, Buddha

    2017-09-01

    Keyes, Linda E., Thomas Douglas Sallade, Charles Duke, Jennifer Starling, Alison Sheets, Sushil Pant, David S. Young, David Twillman, Nirajan Regmi, Benoit Phelan, Purshotam Paudel, Matthew McElwee, Luke Mather, Devlin Cole, Theodore McConnell, and Buddha Basnyat. Blood pressure and altitude: an observational cohort study of hypertensive and nonhypertensive Himalayan trekkers in Nepal. High Alt Med Biol. 18:267-277, 2017. To determine how blood pressure (BP) changes with altitude in normotensive versus hypertensive trekkers. Secondary aims were to evaluate the prevalence of severe hypertension (BP ≥180/100 mmHg) and efficacy of different antihypertensive agents at high altitude. This was an observational cohort study of resting and 24-hour ambulatory BP in normotensive and hypertensive trekkers at 2860, 3400, and 4300 m in Nepal. We enrolled 672 trekkers age 18 years and older, 60 with a prior diagnosis of hypertension. Mean systolic and diastolic BP did not change between altitudes in normotensive or hypertensive trekkers, but was higher in those with hypertension. However, there was large interindividual variability. At 3400 m, the majority (60%, n = 284) of normotensive participants had a BP within 10 mmHg of their BP at 2860 m, while 21% (n = 102) increased and 19% (n = 91) decreased. The pattern was similar between 3400 and 4300 m (64% [n = 202] no change, 21% [n = 65] increased, 15% [n = 46] decreased). BP decreased in a greater proportion of hypertensive trekkers versus normotensives (36% [n = 15] vs. 21% at 3400 m, p = 0.01 and 30% [n = 7] vs. 15% at 4300 m, p = 0.05). Severe hypertension occurred in both groups, but was asymptomatic. In a small subset of participants, 24-hour ambulatory BP monitoring showed that nocturnal BP decreased in normotensive (n = 4) and increased in hypertensive trekkers (n = 4). Most travelers, including those with well-controlled hypertension, can be reassured

  7. Radical scavenging, prolyl endopeptidase inhibitory, and antimicrobial potential of a cultured Himalayan lichen Cetrelia olivetorum.

    Science.gov (United States)

    Savale, Swapnil Anil; Pol, Chaitrali Satish; Khare, Roshni; Verma, Neeraj; Gaikwad, Subhash; Mandal, Bapi; Behera, Bhaskar C

    2016-01-01

    antioxidant, PEPI, and antimicrobial potential. The present study indicates therapeutic potential of Himalayan lichen C. olivetorum against neurodegenerative diseases owing to its radical scavenging, PEPI, and antimicrobial activities. Further, the result encourages its commercial exploitation through mass culture for production of its bioactive components and their use in pharmaceutical and nutraceutical industries.

  8. Response of streamflow to projected climate change scenarios in an eastern Himalayan catchment of India

    Science.gov (United States)

    Senzeba, K. T.; Rajkumari, S.; Bhadra, A.; Bandyopadhyay, A.

    2016-04-01

    Snowmelt run-off model (SRM) based on degree-day approach has been employed to evaluate the change in snow-cover depletion and corresponding streamflow under different projected climatic scenarios for an eastern Himalayan catchment in India. Nuranang catchment located at Tawang district of Arunachal Pradesh with an area of 52 km2 is selected for the present study with an elevation range of 3143-4946 m above mean sea level. Satellite images from October to June of the selected hydrological year 2006-2007 were procured from National Remote Sensing Centre, Hyderabad. Snow cover mapping is done using NDSI method. Based on long term meteorological data, temperature and precipitation data of selected hydrological year are normalized to represent present climatic condition. The projected temperature and precipitation data are downloaded from NCAR's GIS data portal for different emission scenarios (SRES), viz., A1B, A2, B1; and IPCC commitment (non-SRES) scenario for different future years (2020, 2030, 2040 and 2050). Projected temperature and precipitation data are obtained at desired location by spatially interpolating the gridded data and then by statistical downscaling using linear regression. Snow depletion curves for all projected scenarios are generated for the study area and compared with conventional depletion curve for present climatic condition. Changes in cumulative snowmelt depth for different future years are highest under A1B and lowest under IPCC commitment, whereas A2 and B1 values are in-between A1B and IPCC commitment. Percentage increase in streamflow for different future years follows almost the same trend as change in precipitation from present climate under all projected climatic scenarios. Hence, it was concluded that for small catchments having seasonal snow cover, the total streamflow under projected climatic scenarios in future years will be primarily governed by the change in precipitation and not by change in snowmelt depth. Advancing of

  9. Crustal evolution in the East African Orogen: a neodymium isotopic perspective

    Science.gov (United States)

    Stern, Robert J.

    2002-05-01

    The East African Orogen (EAO) is one of Earth's great collision zones, where East and West Gondwana collided to form the supercontinent `Greater Gondwana' or `Pannotia' at the end of Neoproterozoic time. There is now sufficient Nd isotopic data for basement rocks of the EAO to yield a useful summary. A total of 449 samples were gleaned from the literature, recalculated to a common value for the La Jolla Nd standard, and entered in Excel spreadsheets. This data set was filtered to exclude samples with 147Sm/ 144Nd> 0.165, considered to yield unreliable model ages, leaving 413 suitable data. The crust of the Arabian-Nubian Shield, including Egypt east of the Nile, Sudan east of the Keraf suture, Sinai, Israel, Jordan, most of Arabia, Eritrea, and northern Ethiopia yields overwhelmingly Neoproterozoic model ages. Crust to the east, in the Afif terrane of Arabia, Yemen, Somalia, and Eastern Ethiopia yields much older model ages, averaging 2.1 Ga, demonstrating an abundance of reworked ancient crust. This provides an isotopic link with Madagascar (mean age of 2.4 Ga), which in pre-Jurassic reconstructions lies on the southern extension of this older, remobilized tract. Crust in the far southern extreme of the EAO in Tanzania also yields ancient model ages, averaging 2.3 Ga. The central EAO, in southern Ethiopia and Kenya, yields intermediate ages (mean 1.1-1.2 Ga), interpreted to indicate extensive mixing between Neoproterozoic mantle-derived melts and ancient crust. The Nd isotope data indicate that the northern EAO is composed of juvenile Neoproterozoic crust sandwiched between reworked older crust, whereas the EAO farther south is progressively dominated by ancient crust reworked during Neoproterozoic time. The distribution of juvenile and reworked ancient crust suggests that the most intense collision between East and West Gondwana occurred in the southern part of the EAO.

  10. On thrusting, regional unconformities and exhumation of high-grade greenstones in Neoarchean orogens. The case of the Waroonga Shear Zone, Yilgarn Craton

    Science.gov (United States)

    Zibra, I.; Korhonen, F. J.; Peternell, M.; Weinberg, R. F.; Romano, S. S.; Braga, R.; De Paoli, M. C.; Roberts, M.

    2017-08-01

    During the Neoarchean, the dominant tectonic style progressively changed from an episodic-overturn/stagnant-lid regime to modern-style plate tectonics. The Neoarchean strengthening of continental lithosphere changed the style of deformation of orogenic belts. The case study presented here provides insights into how such transition in tectonic style occurred, a matter that is generally controversial. We present structural and metamorphic data from the c. 2660 Ma Waroonga Shear Zone (WSZ) in the Neoarchean Yilgarn orogen (Western Australia). The WSZ contains a syntectonic pluton and older, high-grade greenstones. The tectonic fabric in the pluton developed during melt-present thrusting, followed by syn-cooling wrench-dominated transpression. Mafic greenstones preserve three metamorphic assemblages. The M1 assemblage (Grt-Cpx-Qtz) records peak P-T conditions of 12 ± 1 kbar and 800 ± 50 °C, followed by isothermal decompression to 9 kbar (M2). These anhydrous assemblages might predate the WSZ. Greenstones then underwent decompression at c. 2660 Ma (3-4 kbar; 600-650 °C), defined by the amphibole-rich M3 assemblage, synkinematic with the tectonic fabric in the WSZ. We show that shearing along the WSZ exhumed these greenstones by at least 10 km, inducing major uplift and erosion. Archean accretionary orogens developed on weak lithosphere, where deformation suppressed crustal thickening, orogenic relief and synorogenic exhumation of orogenic roots. However, our study indicates a genetic link between (i) strain localization along contractional structures, inducing large-scale uplift; (ii) exhumation of high-grade greenstones; (iii) development of inverse metamorphic gradients; (iv) establishment of a regional unconformity, with clastic sediments fed by the uplifted terrane; (v) incorporation of portions of the newly-formed orogenic basins into the footwall of the WSZ. These features imply that the Yilgarn orogenic lithosphere at c. 2660 Ma was stiff enough to allow

  11. From the plutonic root to the volcanic roof of a continental magmatic arc: a review of the Neoproterozoic Araçuaí orogen, southeastern Brazil

    Science.gov (United States)

    Gonçalves, Leonardo; Alkmim, Fernando F.; Pedrosa-Soares, Antônio; Gonçalves, Cristiane C.; Vieira, Valter

    2018-01-01

    The Araçuaí-West Congo orogen (AWCO) is one of the various components of the Brasiliano/Pan-African orogenic network generated during the amalgamation of West Gondwana. In the reconstructions of Gondwana, the AWCO, encompassing the Araçuaí orogen of South America and the West Congo belt of Southwestern Africa, appears as a tongue-shaped orogenic zone embraced by the São Francisco-Congo craton. Differing from the vast majority of the known orogens owing to its singular confined setting, the AWCO contains a large amount of orogenic igneous rocks emplaced in all stages of its tectonic evolution. We present new and revised information about the oldest Ediacaran granitic assemblage, the G1 Supersuite, which together with the Rio Doce Group defines the Rio Doce magmatic arc, and then we propose a new tectonic setting for the arc. Field relationships and mineralogical compositions of the G1 Supersuite allow us to characterize three lithofacies associations, Opx-bearing rocks, enclave-rich Tonalite-Granodiorite and enclave-poor Granite-Tonalite, suggesting different crustal levels are exposed in the central part of the Araçuaí orogen. The region is interpreted to represent a tilted crustal section, with deep arc roots now exposed along its western border. Chemically, these plutonic associations consist mostly of magnesian, metaluminous to slightly peraluminous, calc-alkaline to alkali-calcic and medium- to high-K acidic rocks. The dacitic and rhyolitic rocks of the Rio Doce Group are mainly magnesian, peraluminous, calcic to calc-alkaline, and medium- to high-K acidic rocks. Zircon U-Pb data constrain the crystallization of the granitoids between ca. 625 and 574 Ma, while the age of the metamorphosed volcanic rocks is around ca. 585 Ma. Thus, within errors, these rock associations likely belong to the same magmatic event and might represent the subduction-related, pre-collisional, evolution of the Araçuaí orogen. In addition, whole-rock Sm-Nd isotopic compositions

  12. Differential decay of the East-African Antarctic Orogen : an integrated examination of Northeastern Mozambique

    Science.gov (United States)

    Ueda, K.; Jacobs, J.; Emmel, B.; Thomas, R. J.; Matola, R.

    2009-04-01

    In Northeastern Mozambique, the late Proterozoic - early Paleozoic East African-Antarctic Orogen can be subdivided into two major blocks that exhibit some relevant differences. The line of divide is represented by the Lurio Belt, a kinematically poorly constrained shear zone that also marks the conceptual northern limit of frequent late-tectonic granitoid intrusions. Moreover, far-travelled granulite-facies nappes cover a much larger area north of this belt (Viola et. al, 2008), giving rise to the assumption of different exhumation and present exposure levels. U/Pb data from previous surveys (e.g., Norconsult consortium, 2007) show coeval high-grade metamorphism in the whole region between c. 610 - 550 Ma, while the block south of the Lurio Belt also shows continuing metamorphism until c. 490 Ma that can be related to extension. Geothermobarometry for samples from within the Lurio Belt (Engvik et. al, 2007) indicates rapid exhumation after high-pressure granulite facies metamorphism and is consistant with the assumption of long tectonic activity. A possible model for the outlined pattern is the delamination of the orogenic root only in the southern part, followed by rapid mechanical thinning as well as by isostatic accommodation along the Lurio Belt. A valuable marker was identified in the metasedimentary Mecuburi group that overlies the southern basement. U/Pb analysis of detrital zircons have yielded a maximum deposition age of c. 600 Ma, while metamorphism is recorded until c. 505 Ma. Investigations of the relationship between metasediments and older basement show that the basal contact is a fairly preserved depositional contact, allowing to suppose a conjoint post-depositional evolution. It is notable that the timing of deposition shortly follows the onset of the main, widespread high-grade metamorphism. Relatively high but variable degrees of migmatisation in the Mecuburi Group require a phase of burial from surface to deep levels after 600 Ma, followed by

  13. A Tale of Amalgamation of Three Permo-Triassic Collage Systems in Central Asia: Oroclines, Sutures, and Terminal Accretion

    Science.gov (United States)

    Xiao, Wenjiao; Windley, Brian F.; Sun, Shu; Li, Jiliang; Huang, Baochun; Han, Chunming; Yuan, Chao; Sun, Min; Chen, Hanlin

    2015-05-01

    The Central Asian Orogenic Belt records the accretion and convergence of three collage systems that were finally rotated into two major oroclines. The Mongolia collage system was a long, N-S-oriented composite ribbon that was rotated to its current orientation when the Mongol-Okhotsk orocline was formed. The components of the Kazakhstan collage system were welded together into a long, single composite arc that was bent to form the Kazakhstan orocline. The cratons of Tarim and North China were united and sutured by the Beishan orogen, which terminated with formation of the Solonker suture in northern China. All components of the three collage systems were generated by the Neoproterozoic and were amalgamated in the Permo-Triassic. The Central Asian Orogenic Belt evolved by multiple convergence and accretion of many orogenic components during multiple phases of amalgamation, followed by two phases of orocline rotation.

  14. Orogen-parallel Variation in Flexure of the Arabian Plate Beneath the Zagros Mountains

    Science.gov (United States)

    Pirouz, M.; Avouac, J. P.; Simpson, G.; Hassanzadeh, J.; Herman, F.; Sternai, P.

    2014-12-01

    The Zagros Mountains are the part of the Alpine-Himalayan chain that forms the northern margin of the Arabian plate and comprises a Neogene-Recent sedimentary basin that is forming in response to ongoing Arabia-Eurasia collision. Flexure of the Arabian lithosphere beneath the Zagros forms one of largest and most active basins in the world at which a backstripped deflection of a competent layer just below the foreland deposits represents its total amount of tectonic subsidence. As such, the Asmari Fm. can be used to analyze flexural bending and subsequently the amount of loading and elastic thickness of the Arabian lithosphere since the continent-continent collision started. In this study, flexure of the Arabian lithosphere is investigated using more than 100 boreholes and 60 interpreted seismic lines which show that the flexure is shallower (~ 1 km) and wider in the east and deeper (~6 km) and narrower towards the west (Figure 1). The shallow and wide eastern foredeep has little accommodation space due to small tectonic loads and the thick lithosphere in this region. In addition, viscous strength in the eastern sector leads to a wide deformation belt with low topography and low surface slopes. These factors, combined with arid climatic conditions, produce low sediment supply to the foreland basin so that it remains under-filled even though the foreland basin is shallow. In contrast, the western part of the Zagros region shows much larger accommodation space due to the combination of large loads and a relatively thin elastic plate. In the western sector, frictional basal strength and steeper topography along with more humid climatic conditions leading to a large supply of sediment to the foreland which is completely filled even though the foreland basin is deep. Our results also show that the Zagros foreland basin migrated towards south through the Neogene; however, the way of propagation is not fully understood yet. The eastern depocenter of the Zagros foreland

  15. Two-stage formation model of the Junggar basin basement: Constraints to the growth style of Central Asian Orogenic Belt

    Science.gov (United States)

    He, Dengfa

    2016-04-01

    Junggar Basin is located in the central part of the Central Asian Orogenic Belt (CAOB). Its basement nature is a highly controversial scientific topic, involving the basic style and processes of crustal growth. Some researchers considered the basement of the Junggar Basin as a Precambrian continental crust, which is not consistent with the petrological compositions of the adjacent orogenic belts and the crust isotopic compositions revealed by the volcanic rocks in the basin. Others, on the contrary, proposed an oceanic crust basement model that does not match with the crustal thickness and geophysical characteristics of the Junggar area. Additionally, there are several viewponits, such as the duplex basement with the underlying Precambrian crystalline rocks and the overlying pre-Carboniferous folded basement, and the collaged basement by the Precambrian micro-continent block in the central part and the Hercynian accretionary folded belts circling it. Anyway, it is necessary to explain the property of basement rock, its strong inhomogeneous compositions as well as the geophysical features. In this paper, based on the borehole data from more than 300 industry wells drilled into the Carboniferous System, together with the high-resolution gravity and magnetic data (in a scale of 1:50,000), we made a detailed analysis of the basement structure, formation timing and processes and its later evolution on a basis of core geochemical and isotopic analysis. Firstly, we defined the Mahu Pre-Cambrian micro-continental block in the juvenile crust of Junggar Basin according to the Hf isotopic analysis of the Carboniferous volcanic rocks. Secondly, the results of the tectonic setting and basin analysis suggest that the Junggar area incorporates three approximately E-W trending island arc belts (from north to south: Yemaquan- Wulungu-Chingiz, Jiangjunmiao-Luliang-Darbut and Zhongguai-Mosuowan- Baijiahai-Qitai island arcs respectively) and intervened three approximately E-W trending

  16. The Wyoming gold deposits: volcanic-hosted lode-type gold mineralisation in the eastern Lachlan Orogen, Australia

    Science.gov (United States)

    Chalmers, D. Ian; Ransted, Terry W.; Kairaitis, Rimas A.; Meates, David G.

    2007-06-01

    The eastern Lachlan Orogen in southeastern Australia is noted for its major porphyry-epithermal-skarn copper-gold deposits of late Ordovician age. Whilst many small quartz vein-hosted or orogenic lode-type gold deposits are known in the region, the discovery of the Wyoming gold deposits has demonstrated the potential for significant lode-type mineralisation hosted within the same Ordovician volcanic stratigraphy. Outcrop in the Wyoming area is limited, with the Ordovician sequence largely obscured by clay-rich cover of probable Quaternary to Cretaceous age with depths up to 50 m. Regional aeromagnetic data define a north-south trending linear belt interpreted to represent the Ordovician andesitic volcanic rock sequence within probable Ordo-Silurian pelitic metasedimentary rocks. Drilling through the cover sequence in 2001 to follow up the trend of historically reported mineralisation discovered extensive alteration and gold mineralisation within an andesitic feldspar porphyry intrusion and adjacent volcaniclastic sandstones and siltstones. Subsequent detailed resource definition drilling has identified a substantial mineralised body associated with sericite-carbonate-albite-quartz-(±chlorite ± pyrite ± arsenopyrite) alteration. The Wyoming deposits appear to have formed as the result of a rheological contrast between the porphyry host and the surrounding volcaniclastic rocks, with the porphyry showing brittle fracture and the metasedimentary rocks ductile deformation. The mineralisation at Wyoming bears many petrological and structural similarities to orogenic lode-style gold deposits. Although the timing of alteration and mineralisation in the Wyoming deposits remain problematic, a relationship with possible early to middle Devonian deformation is considered likely.

  17. Geochemistry, 40Ar/39Ar geochronology, and geodynamic implications of Early Cretaceous basalts from the western Qinling orogenic belt, China

    Science.gov (United States)

    Zhang, Feifei; Wang, Yuejun; Cawood, Peter A.; Dong, Yunpeng

    2018-01-01

    The Qinling-Dabie orogenic belt was formed by the collision of the North and South China Cratons during the Early Mesozoic and subsequently developed into an intracontinental tectonic process during late Mesozoic. Field investigations identified the presence of late Mesozoic basalts in the Duofutun and Hongqiang areas in the western Qinling orogenic belt. The petrogenesis of these basalts provides an important constraint on the late Mesozoic geodynamics of the orogen. The representative basaltic samples yield the 40Ar/39Ar plateau age of about 112 Ma. These samples belong to the alkaline series and have SiO2 ranging from 44.98 wt.% to 48.19 wt.%, Na2O + K2O from 3.44 wt% to 5.44 wt%, and MgO from 7.25 wt.% to 12.19 wt.%. They demonstrate the right-sloping chondrite-normalized REE patterns with negligible Eu anomalies (1.00-1.10) and PM-normalized patterns enriched in light rare earth element, large ion lithophile element and high field strength element, similar to those of OIB rocks. These samples additionally show an OIB-like Sr-Nd isotopic signature with εNd(t) values ranging from +6.13 to +10.15 and initial 87Sr/86Sr ratios from 0.7028 to 0.7039, respectively. These samples are geochemically subdivided into two groups. Group 1 is characterized by low Al2O3 and high TiO2 and P2O5 contents, as well as high La/Yb ratios (>20), being the product of the high-pressure garnet fractionation from the OIB-derived magma. Group 2 shows higher Al2O3 but lower P2O5 contents and La/Yb ratios (<20) than Group 1, originating from asthenospheric mantle with input of delaminated lithospheric component. In combination with available data, it is proposed for the petrogenetic model of the Early Cretaceous thickened lithospheric delamination in response to the asthenospheric upwelling along the western Qinling orogenic belt.

  18. 10Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis

    Directory of Open Access Journals (Sweden)

    M. Lupker

    2017-08-01

    Full Text Available The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range and flows from the Tibetan Plateau through the eastern Himalayan syntaxis downstream to the Indo-Gangetic floodplain and the Bay of Bengal. As such, it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. The measured 10Be denudation rates span around 2 orders of magnitude across individual catchments (ranging from 0.03 to > 4 mm yr−1 and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates, however, occurs  ∼  150 km downstream of the Namche Barwa–Gyala Peri massif (NBGPm, an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse-grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high-concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage, and quartz content of the upstream Tibetan Plateau part of the catchment, which tends to lead to an overestimation of downstream denudation rates. While no direct 10Be denudation measurements were made in the syntaxis, the dilution of the upstream 10Be signal, measured in Tsangpo

  19. Variations in particulate matter over Indo-Gangetic Plains and Indo-Himalayan Range during four field campaigns in winter monsoon and summer monsoon: Role of pollution pathways

    Science.gov (United States)

    Sen, A.; Abdelmaksoud, A. S.; Nazeer Ahammed, Y.; Alghamdi, Mansour ِA.; Banerjee, Tirthankar; Bhat, Mudasir Ahmad; Chatterjee, A.; Choudhuri, Anil K.; Das, Trupti; Dhir, Amit; Dhyani, Pitamber Prasad; Gadi, Ranu; Ghosh, Sanjay; Kumar, Kireet; Khan, A. H.; Khoder, M.; Maharaj Kumari, K.; Kuniyal, Jagdish Chandra; Kumar, Manish; Lakhani, Anita; Mahapatra, Parth Sarathi; Naja, Manish; Pal, Dharam; Pal, S.; Rafiq, Mahammad; Romshoo, Shakil Ahmad; Rashid, Irfan; Saikia, Prasenjit; Shenoy, D. M.; Sridhar, Vijay; Verma, Nidhi; Vyas, B. M.; Saxena, Mohit; Sharma, A.; Sharma, S. K.; Mandal, T. K.

    2017-04-01

    Both in-situ and space-borne observations reveal an extremely high loading of particulates over the Indo-Gangetic Plains (IGP), all year around. With a burgeoning population and combustion sources (fossil fuels (FFs) and biofuels (BFs)) in close proximity to each other, the IGP is widely regarded as a hotspot for anthropogenic aerosol emission in South Asia. The deteriorating air quality over this region, particularly during winters, is a cause of major concern, since the pollutants undergo long range transport from their source regions to the Indo-Himalayan Range (IHR), Bay of Bengal (BoB) and other remote areas, polluting their pristine atmospheric conditions. Seasonal reversal in winds over the Indian mainland leads to an outflow of continental pollutants into the BoB during winters and a net advection of desert dust aerosols into the IGP from southwest Asia (SW-Asia), northwest India (NW-India) and northern Africa (N-Africa) during summers. Through the course of this study, four observational campaigns were conducted for sampling the ambient PM2.5 and PM10 during winter and summer seasons of 2014-2015, at multiple locations (18 sites) in the IGP, IHR, and semi-arid/arid sites towards their south and west, in order to accurately determine the inter-seasonal and inter-annual changes in the aerosol loading at the sites. We have also utilized data from Moderate Resolution Imaging Spectroradiometer (MODIS) on-board Earth Observing System (EOS) Terra satellite for estimating the columnar Aerosol Optical Depth at 550 nm (AOD550) and data from EOS Terra and Aqua satellites for discovering openly burning fires in the vicinity of sampling sites. Determination of the major source regions and key transport pathways during both seasons have also been attempted, using back-trajectory cluster analyses, as well as receptor models such as PSCF and CWT.

  20. Extension of the Mid- to Lower Crust with Orogenic Inheritance: Examples from the Death Valley Region (Western US), and the Mauleon Basin (Southwestern France).

    Science.gov (United States)

    Lima, R. D.; Hayman, N. W.; Kelly, E. D.; Lavier, L. L.

    2015-12-01

    Continental margins exhibit a range of widths and symmetries defined by the strain patterns that arise during extension and rifting. An important pattern in this respect is the early localization of extension into necking zones. The rheology of the lower crust plays a large role in this localization, and can be affected by inherited orogenic structures, fabrics, and mineral assemblages. Here, we further evaluate the role of orogenic fabrics in continental extension using microstructural observations and thermodynamic modeling of geological sections exposed in the Funeral and Black Mountains of the Death Valley region, California, and from the Mauleon Basin, France. The Death Valley region sits within the Basin-and-Range region of broadly distributed Cenozoic extension, over a relatively flat and deep moho. In contrast, in the Mauleon basin, Cretaceous extension accommodated mantle exhumation, and was strongly localized in older Hercynian orogenic crust. In both areas, mid- to lower crustal rocks are characterized by inherited migmatitic fabrics overprinted by zones of localized, extensional fabrics. Mineral assemblages that formed over a P-T cooling path define the fabrics in each field area. The high-temperature fabrics record decompression-melting due to late- to post-orogenic collapse. Yet, the two field areas show contrasting retrograde assemblages, which are hypothesized to have resulted from changes in the local effective bulk composition produced by differences in melt segregation. At subsequent extensional stages, mid- to lower crustal deformation resulted in the transposition of the inherited post-orogenic fabrics, documented with quartz fabric analysis (including EBSD). The two contrasting regions show how the rheology of inherited orogenic lower crust responds to differences in melt-segregation and metamorphic histories, potentially controlling margin structural evolution.

  1. Geochemical modeling of orogenic gold deposit using PCANN hybrid method in the Alut, Kurdistan province, Iran

    Science.gov (United States)

    Mohammadzadeh, Mohammadjafar; Nasseri, Aynur

    2018-03-01

    In this paper stream sediments based geochemical exploration program with the aim of delineating potentially promising areas by a comprehensive stepwise optimization approach from univariate statistics, PCA, ANN, and fusion method PCANN were under taken for an orogenic gold deposit located in the Alut, Kurdistan province, NW of Iran. At first the data were preprocessed and then PCA were applied to determine the maximum variability directions of elements in the area. Subsequently the artificial neural network (ANN) was used for quick estimation of elemental concentration, as well as discriminating anomalous populations and intelligent determination of internal structure among the data. However, both the methods revealed constraints for modeling. To overcome the deficiency and shortcoming of each individual method a new methodology is presented by integration of both "PCA & ANN" referred as PCANN method. For integrating purpose, the detected PCs pertinent to ore mineralization selected and intruded to neural network structure, as a result different MLPs with various algorithms and structures were produced. The resulting PCANN maps suggest that the gold mineralization and its pathfinder elements (Au, Mo, W, Bi, Sb, Cu, Pb, Ag & As) are associated with metamorphic host rocks intruded by granite bodies in the Alut area. In addition, more concealed and distinct Au anomalies with higher intensity were detected, confirming the privileges of the method in evaluating susceptibility of the area in delineating new hidden potential zones. The proposed method demonstrates simpler network architecture, easy computational implementation, faster training speed, as well as no need to consider any primary assumption about the behavior of data and their probability distribution type, with more satisfactory predicting performance for generating gold potential map of the area. Comparing the results of three methods (PCA, ANN and PCANN), representing the higher efficiency and more

  2. Detrital zircon geochronology of pre- and syncollisional strata, Acadian orogen, Maine Appalachians

    Science.gov (United States)

    Bradley, Dwight C.; O'Sullivan, Paul B.

    2017-01-01

    northwest. Next, southeasterly parts of this succession were deformed in the Acadian orogeny, shedding detritus towards the northwest into what remained of the basin. Finally, by Pragian time, all strata in the Central Maine Basin had been deformed and detritus from this new source accumulated as the Tarratine Formation in a new incarnation of the foreland basin. Silurian-Devonian strata from the Central Maine Basin have similar detrital zircon age distributions to coeval rocks from the Arctic Alaska and Farewell terranes of Alaska and the Northwestern terrane of Svalbard. We suggest that these strata were derived from different segments of the 6500-km-long Appalachian-Caledonide orogen.

  3. Multiple sulfur isotopes monitor fluid evolution of an Archean orogenic gold deposit

    Science.gov (United States)

    LaFlamme, Crystal; Sugiono, Dennis; Thébaud, Nicolas; Caruso, Stefano; Fiorentini, Marco; Selvaraja, Vikraman; Jeon, Heejin; Voute, François; Martin, Laure

    2018-02-01

    The evolution of a gold-bearing hydrothermal fluid from its source to the locus of gold deposition is complex as it experiences rapid changes in thermochemical conditions during ascent through the crust. Although it is well established that orogenic gold deposits are generated during time periods of abundant crustal growth and/or reworking, the source of fluid and the thermochemical processes that control gold precipitation remain poorly understood. In situ analyses of multiple sulfur isotopes offer a new window into the relationship between source reservoirs of Au-bearing fluids and the thermochemical processes that occur along their pathway to the final site of mineralisation. Whereas δ34S is able to track changes in the evolution of the thermodynamic conditions of ore-forming fluids, Δ33S is virtually indelible and can uniquely fingerprint an Archean sedimentary reservoir that has undergone mass independent fractionation of sulfur (MIF-S). We combine these two tracers (δ34S and Δ33S) to characterise a gold-bearing laminated quartz breccia ore zone and its sulfide-bearing alteration halo in the (+6 Moz Au) structurally-controlled Archean Waroonga deposit located in the Eastern Goldfields Superterrane of the Yilgarn Craton, Western Australia. Over 250 analyses of gold-associated sulfides yield a δ34S shift from what is interpreted as an early pre-mineralisation phase, with chalcopyrite-pyrrhotite (δ34S = +0.7‰ to +2.9‰) and arsenopyrite cores (δ34S = ∼-0.5‰), to a syn-mineralisation stage, reflected in Au-bearing arsenopyrite rims (δ34S = -7.6‰ to +1.5‰). This shift coincides with an unchanging Δ33S value (Δ33S = +0.3‰), both temporally throughout the Au-hosting hydrothermal sulfide paragenesis and spatially across the Au ore zone. These results indicate that sulfur is at least partially recycled from MIF-S-bearing Archean sediments. Further, the invariant nature of the observed MIF-S signature demonstrates that sulfur is derived from a

  4. Tectonic evolution of a part of the Tethyside orogenic collage: The Kargi Massif, northern Turkey

    Science.gov (United States)

    Tüysüz, Okan

    1990-02-01

    The central part of the Rhodope-Pontide fragment, one of the major tectonic units in Turkey, provides critical data for evaluating the Cimmeride and Alpide evolution of the Mediterranean Tethysides. Tectonic events that affected the central part of the Rhodope-Pontide fragment since the end of the Paleozoic, generated east-west trending belts with the event of every episode redeforming and partly obliterating the structures of previous episodes. This evolution may be conveniently described in terms of three major episodes: (1) Two different realms of pre-Dogger oceanic rocks are present in the area. The northern realm coincided with main branch of Paleo-Tethys that was being actively destroyed by south dipping subduction. The southern realm, the Karakaya ocean, a back arc basin related to this subduction, began opening by rifting of a retroarc carbonate platform during the Permo-Triassic. To the west a continental domain with sparse magmatism seperated the two oceanic areas. Toward the east the two oceans become united by the wedging out of the continental domain. These two pre-Dogger oceans closed during the Lias, and their remnants were emplaced between the southern margin of Laurasia and the fragments of the Cimmerian continent. (2) The second episode partly overlapped the first with rifting south of the Cimmerian continent fragment during the Lias. This rifting was followed by a transgression which covered the ruins of the Cimmeride orogenic belt by the Malm. This rifting concurrently led to the development of the northern branch of the Neo-Tethys and a south facing Atlantic-type continental margin. A southerly thickening sedimentary prism developed on this margin during the Lias to early Cretaceous interval. (3) The floor of the northern branch of Neo-Tethys began to be consumed along the north dipping subduction zone beneath the previosly constructed continental margin. This convergent margin generated a magmatic arc to the north and to the south a subduction

  5. Himalayan/Karakoram Disaster After Disaster: The Pain Will Not Be Ending Anytime Soon

    Science.gov (United States)

    Kargel, J. S.; Leonard, G. J.

    2013-12-01

    Are recent natural disasters in the Himalaya/Karakoram partly human-caused? Will disasters diminish or increase in frequency? Natural disasters in this region are nothing new. Earthquakes, floods, landslides, avalanches, and debris flows have occurred in the Himalaya/Karakoram since the mountains first grew from the sea. Simply put, the Himalaya/Karakoram, being South Asia's 'water tower' and an active plate tectonic collision zone, must shed water and debris to the lowlands and the sea. When this activity occurs swiftly and with high intensity at or near human settlements, the results are often deadly. Remote sensing analysis of recent disasters coupled with demography, news accounts, and field studies indicate that there is a component of human responsibility. Two overarching human elements include (1) settlement and infrastructure encroachment into hazardous mountain areas and (2) aggravation of climate change. Both are substantially responsible--separately or together--for most of the recent tragedies. These conclusions provide the answer to when the disasters will end: not soon. Unfortunately, disasters will almost surely increase. Whether natural disasters have increased in frequency over the region's long historical record may be debated and must be researched. This expected link is a challenge to assess due to the stochastic nature of disasters and their triggering events (e.g., earthquakes and extreme weather events). While Himalayan tectonism, rock mechanics, glaciation, and climate are fundamental causes of the disasters, so are human land uses. Encroaching development into ever-hazardous zones is a paramount cause of much human tragedy. Climate change is harder to pin down specifically as a cause of some of these disasters, because some disasters are linked to rare extreme weather events and mass movements, which may be statistically but not individually attributable in part to climate change. Nevertheless, evidence supports a major role of climate

  6. Between China and Nepal: Trans-Himalayan Trade and the Second Life of Development in Upper Humla

    Directory of Open Access Journals (Sweden)

    Martin Saxer

    2013-09-01

    Full Text Available Upper Humla, an area in northwestern Nepal bordering the Tibet Autonomous Region, has lost much of its prosperity over the past five decades. The region’s recent history has been shaped by modernization efforts and development initiatives on both sides. However, the author argues that, contrary to the common conception that Communist reform in Tibet dismantled the traditional economic foundation of trade-based Himalayan livelihoods, different forces were at work in the case of upper Humla. Three benevolent development initiatives in public health, wildlife conservation, and community forestry triggered the decline. The “second lives” of successful development, rather than the side effects of modernist planning, are responsible for upper Humla’s current predicament.

  7. Molecular phylogenetic analysis of fleshy pored mushrooms: Neoboletus luridiformis and Hortiboletus rubellus from western Himalayan range of Pakistan

    International Nuclear Information System (INIS)

    Sarwar, S.; Khalid, N.; Dentinger, B.M.

    2016-01-01

    Fleshy pored mushrooms is the name given to boletes due to their porous hymenium and fleshy nature. These are ectomycorrhizal basidiomycetes found in all continents except Antarctica. These mushrooms are important economically due to their edibility and medicinal value. This research work highlights the diversity of boletes in Pakistan and their correct identification by using molecular phylogenetic techniques. Western Himalayan range (WHR) of Pakistan is considered as diversity rich area. During present investigation regarding diversity of boletes in these areas, two bolete taxa viz. Hortiboletus rubellus and Neoboletus luridiformis were found under conifers. These mushrooms were collected and analyzed morphologically as well as phylogenetically by using Internal Transcribed Spacer (ITS) region of nrDNA sequences, and compared with their allies. All description and comparison with related taxa is provided in detail. These boletes are first time analyzed using molecular method from Pakistan. (author)

  8. Transforming the Lives of Mountain Women Through the Himalayan Nettle Value Chain: A Case Study From Darchula, Far West Nepal

    Directory of Open Access Journals (Sweden)

    Lipy Adhikari

    2018-02-01

    Full Text Available Naugad is a remote rural municipality in the mountains of far west Nepal with poor accessibility and limited economic opportunities, especially for women and marginalized communities. Promotion of the natural resource-based value chain for allo (the Himalayan nettle, Girardinia diversifolia was identified as an innovative livelihood strategy by the local community. Value chain development started in 2014. The project was designed to focus on women and include participation by the private sector. This paper analyzes the impact of the project, especially on women's lives, using primary and secondary data. A community-owned enterprise was established with private-sector support from the South Asian Association of Regional Cooperation's Business Association of Home Based Workers (SABAH Nepal. The enterprise now has 82 members (69 of them women, with 150 households benefiting directly and indirectly. SABAH Nepal provided training in sustainable harvesting and processing techniques and promotes the products in high-end international markets. A buyback guarantee scheme provides security to local artisans. The quality and range of allo products have increased markedly, as has the share in benefits for local people. Skills training and visits to trade fairs have helped women build their capacity and take a leading role in the value chain process. The community-owned enterprise members have earned up to NPR 4000 per month from sewing, more than the local rate for day labor and sufficient to cover general household expenses. More than 25 women entrepreneurs have started microbusinesses related to allo. Allo has become an important economic asset, transforming the lives of mountain women in this village area. The approach has potential for scaling up across the subtropical to temperate areas of the Himalayan region in Bhutan, China, India, Myanmar, and Nepal.

  9. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Abdul Matin. Articles written in Journal of Earth System Science. Volume 118 Issue 4 August 2009 pp 379-390. Deformation mechanisms in the frontal Lesser Himalayan Duplex in Sikkim Himalaya, India · Abdul Matin Sweety Mazumdar · More Details Abstract Fulltext PDF.

  10. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Mahavir Singh. Articles written in Journal of Earth System Science. Volume 120 Issue 2 April 2011 pp 281-290. Atmospheric ultrafine aerosol number concentration and its correlation with vehicular flow at two sites in the western Himalayan region: Kullu-Manali, India.

  11. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Raghavendra Ashrit. Articles written in Journal of Earth System Science. Volume 115 Issue 3 June 2006 pp 299-313. Simulation of a Himalayan cloudburst event · Someshwar Das Raghavendra Ashrit M W Moncrieff · More Details Abstract Fulltext PDF. Intense rainfall often ...

  12. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Anirban Mukhopadhyay. Articles written in Journal of Earth System Science. Volume 123 Issue 6 August 2014 pp 1349-1360. Forest cover change prediction using hybrid methodology of geoinformatics and Markov chain model: A case study on sub-Himalayan town ...

  13. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. M Israil. Articles written in Journal of Earth System Science. Volume 117 Issue 3 June 2008 pp 189-200. Magnetotelluric investigations for imaging electrical structure of Garhwal Himalayan corridor, Uttarakhand, India · M Israil D K Tyagi P K Gupta Sri Niwas · More Details ...

  14. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science. Harinder K Thakur. Articles written in Journal of Earth System Science. Volume 118 Issue 1 February 2009 pp 41-48. Aerosol optical depths at Mohal-Kullu in the northwestern Indian Himalayan high altitude station during ICARB · Jagdish C Kuniyal Alpana Thakur Harinder ...

  15. The New Consort Gold Mine, Barberton greenstone belt, South Africa: orogenic gold mineralization in a condensed metamorphic profile

    Science.gov (United States)

    Otto, A.; Dziggel, A.; Kisters, A. F. M.; Meyer, F. M.

    2007-10-01

    The New Consort Gold Mine in the Palaeo- to Mesoarchaean Barberton greenstone belt, South Africa is one of the oldest recognized orogenic gold deposits on Earth. The gold mineralization is hosted by discrete mylonitic units that occur at, or close to, the contact between the mafic and ultramafic volcanic rocks of the c. 3,280 Ma Onverwacht Group and the mainly metasedimentary rocks of the overlying c. 3,260-3,230 Ma Fig Tree Group. This contact, locally referred to as the Consort Bar, formed during ductile D1 imbrication of the metavolcanosedimentary sequence and predates the main stage of the gold mineralization. The imbricate stack is situated in the immediate hanging wall of the basal granitoid-greenstone contact along the northern margin of the greenstone belt. It is characterized by a condensed metamorphic profile in which the metamorphic grade increases from upper greenschist facies conditions (510-530°C, 4 kbar) in rocks of the Fig Tree Group to upper amphibolite facies grades (600-700°C, 6-8 kbar) in the basal Onverwacht Group. Detailed structural and petrological investigations indicate that the Consort Bar represents a major structural break, which is largely responsible for the telescoping of metamorphic isograds within the structural sequence. Two stages of mineralization can be distinguished. Loellingite, pyrrhotite, and a calc-silicate alteration assemblage characterize an early high-T mineralization event, which is restricted to upper amphibolite facies rocks of the Onverwacht Group. This early mineralization may correlate with the local D1 deformation. The second and main stage of gold mineralization was associated with renewed ductile shearing during D2. The D2 deformation resulted in the reactivation of earlier structures, and the formation of a NNW trending, steeply dipping shear zone system, the Shires Shear Zone, which separates two regional SE plunging D1 synclines. The mineralized shear zones are intruded by abundant syn-kinematic pegmatite

  16. Sedimentary records on the subduction-accretion history of the Russian Altai, northwestern Central Asian Orogenic Belt

    Science.gov (United States)

    Chen, Ming; Sun, Min

    2017-04-01

    The Russian Altai, comprising the northern segment of the Altai-Mongolian terrane (AM) in the south, the Gorny Altai terrane (GA) in the north and the intervening Charysh-Terekta-Ulagan-Sayan suture zone, is a key area of the northwestern Central Asian Orogenic Belt (CAOB). A combined geochemical and detrital zircon study was conducted on the (meta-)sedimentary sequences from the Russian Altai to reveal the tectono-magmatic history of these two terranes and their amalgamation history, which in turn place constraints on the accretionary orogenesis and crustal growth in the CAOB. The Cambrian-Ordovician meta-sedimentary rocks from the northern AM are dominated by immature sediments possibly sourced from intermediate-felsic igneous rocks. Geochemical data show that the sediments were likely deposited in a continental arc-related setting. Zircons separated from these rocks are mainly 566-475 Ma and 1015-600 Ma old, comparable to the magmatic records of the Tuva-Mongolian terrane and surrounding island arcs in the western Mongolia. The similar source nature, provenance and depositional setting of these rocks to the counterparts from the Chinese Altai (i.e., the southern AM) imply that the whole AM possibly represents a coherent accretionary prism of the western Mongolia in the early Paleozoic rather than a Precambrian continental block with passive marginal deposition as previously thought. In contrast, the Cambrian to Silurian (meta-)sedimentary rocks from the GA are characterized by a unitary zircon population with ages of 640-470 Ma, which were potentially sourced from the Kuznetsk-Altai intra-oceanic island arc in the east of this terrane. The low abundance of 640-540 Ma zircons (5%) may attest that this arc was under a primitive stage in the late Neoproterozoic, when mafic igneous rocks dominated. However, the voluminous 530-470 Ma zircons (95%) suggest that this arc possibly evolved toward a mature one in the Cambrian to early Ordovician with increasing amount of

  17. A Comparative Study of the Electrical Structure of Circum Tibetan Plateau Orogenic Belts and its Tectonic Implications

    Science.gov (United States)

    Jin, Sheng; Zhang, Letian; Wei, Wenbo; Ye, Gaofeng; Jing, Jianen; Dong, Hao; Xie, Chengliang; Yin, Yaotian

    2017-04-01

    The Tibetan Plateau, as known as "roof of the world", was created through the on-going continent-continent collision between the Indian and Eurasian plates since 55 Ma. As the process continues, the plateau is growing both vertically and horizontally. The horizontal expansion of the plateau is blocked by the Yangtze block in the east, the Tarim block in the north, and the Ordos block in the northeast, and consequently lead to the formation of the circum Tibetan plateau orogenic belts. To better understand the mechanism behind this process, we conducted a comparative study by collecting 7 magnetotelluric (MT) profiles over the margins of the Tibetan plateau, namely, the INDEPTH 100, 700 and 800 lines in the southern Tibet, the INDEPTH 4000 and 5000 lines across the Altyn Tagh fault on the northern margin of the plateau, as well as other two profiles across the Haiyuan fault and the Longmenshan fault on the northeastern and eastern margins of the plateau deployed under the framework of project SinoProbe. The electrical features of the stable blocks surrounding the Tibetan plateau are generally resistive, while crustal conductive layers are found to be wide spread within the plateau. The southern margin of the Tibetan plateau is characterized by large scale underthrust of the Indian lithosphere beneath the plateau. This intense converging process created the thrust fault system distributed along the southern margin of the Tibetan plateau over 1000 km. Crustal conductive layers discovered in southern Tibet are generally associated with the southward crustal flow that originated from the lower crust within the plateau and exhumed along the thrust belts in the Himalayas. On the eastern margin of the Tibetan plateau, the electrical structures suggest that the Yangtze block wedged into the Tibetan lithosphere and caused decoupling between the crust and upper mantel. Large scale conductors discovered beneath the Songpan-Ganze block reflect that the eastward crustal flow was

  18. 21st century Himalayan hydropower: Growing exposure to glacial lake outburst floods?

    Science.gov (United States)

    Schwanghart, Wolfgang; Worni, Raphael; Huggel, Christian; Stoffel, Markus; Korup, Oliver

    2014-05-01

    Primary energy demand in China and India has increased fivefold since 1980. To avoid power shortages and blackouts, the hydropower infrastructure in the Hindu Kush-Himalaya region is seeing massive development, a strategy supported by the policy of the World Bank and in harmony with the framework of the Kyoto Protocol. The targeted investments in clean energy from water resources, however, may trigger far-reaching impacts to downstream communities given that hydropower projects are planned and constructed in close vicinity to glaciated areas. We hypothesize that the location of these new schemes may be subject to higher exposure to a broad portfolio of natural hazards that proliferate in the steep, dissected, and tectonically active topography of the Himalayas. Here we focus on the hazard from glacial lake outburst floods (GLOF), and offer an unprecedented regional analysis for the Hindu Kush-Himalaya orogen. We compiled a database of nearly 4,000 proglacial lakes that we mapped from satellite imagery; and focus on those as potential GLOF sources that are situated above several dozen planned and existing hydropower plants. We implemented a scenario-based flood-wave propagation model of hypothetic GLOFs, and compared thus simulated peak discharges with those of the local design floods at the power plants. Multiple model runs confirm earlier notions that GLOF discharge may exceed meteorological, i.e. monsoon-fed, flood peaks by at least an order of magnitude throughout the Hindu Kush-Himalaya. We further show that the current trend in hydropower development near glaciated areas may lead to a >15% increase of projects that may be impacted by future GLOFs. At the same time, the majority of the projects are to be sited where outburst flood modelling produces its maximum uncertainty, highlighting the problem of locating minimum risk sites for hydropower. Exposure to GLOFs is not uniformly distributed in the Himalayas, and is particularly high in rivers draining the Mt

  19. Melting Himalayan glaciers contaminated by legacy atmospheric depositions are important sources of PCBs and high-molecular-weight PAHs for the Ganges floodplain during dry periods.

    Science.gov (United States)

    Sharma, Brij Mohan; Nizzetto, Luca; Bharat, Girija K; Tayal, Shresth; Melymuk, Lisa; Sáňka, Ondřej; Přibylová, Petra; Audy, Ondřej; Larssen, Thorjørn

    2015-11-01

    Melting glaciers are natural redistributors of legacy airborne pollutants, affecting exposure of pristine proglacial environments. Our data shows that melting Himalayan glaciers can be major contributors of polychlorinated biphenyls (PCBs) and high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) for surface water in the Gangetic Plain during the dry season. Glacial emissions can exceed in some cases inputs from diffuse sources within the catchment. We analyzed air, deposition and river water in several sections along the Ganges River and its major headwaters. The predominant glacial origin of these contaminants in the Himalayan reach was demonstrated using air-water fugacity ratios and mass balance analysis. The proportion of meltwater emissions compared to pollutant discharge at downstream sections in the central part of the Gangetic Plain was between 2 and 200%. By remobilizing legacy pollutants from melting glaciers, climate change can enhance exposure levels over large and already heavily impacted regions of Northern India. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Geological and geochemical implications of the genesis of the Qolqoleh orogenic gold mineralisation, Kurdistan Province (Iran)

    Science.gov (United States)

    Taghipour, Batoul; Ahmadnejad, Farhad

    2015-03-01

    The Qolqoleh gold deposit is located in the northwestern part of the Sanandaj-Sirjan Zone (SSZ), within the NE-SW trending Qolqoleh shear zone. Oligocene granitoids, Cretaceous meta-limestones, schists and metavolcanics are the main lithological units. Chondrite-normalised REE patterns of the ore-hosting metavolcanics indicate REE enrichment relative to hanging wall (chlorite-sericite schist) and footwall (meta-limestone) rocks. The pattern also reflects an enrichment in LREE relative to HREE. It seems that the LREE enrichment is related to the circulation of SO42- and CO2-bearing fluids and regional metamorphism in the Qolqoleh shear zone. Both positive and negative Eu anomalies are observed in shear-zone metavolcanics. These anomalies are related to the degree of plagioclase alteration during gold mineralisation and hydrothermal alteration. In progressing from a metavolcanic protomylonite to an ultramylonite, significant changes occurred in the major/trace element and REE concentration. Utilising an Al-Fe-Ti isocon for the ore-hosting metavolcanics shows that Sc, Y, K, U, P, and M-HREE (except Eu) are relatively unchanged; S, As, Ag, Au, Ca, LOI, Rb and LREE are enriched, and Sr, Ba, Eu, Cr, Co and Ni decrease with an increasing degree of deformation. Based on geochemical features and comparison with other well-known shear zones in the world, the study area is best classified as an Isovolume-Gain (IVG) type shear zone and orogenic type gold mineralisation. Based on the number of phases observed at room temperature and their microthermometric behaviour, three fluid inclusion types have been recognised in quartz-sulphide and quartz-calcite veins: Type I monophase aqueous inclusions, Type II two-phase liquid-vapour (L-V) inclusions which are subdivided into two groups based on the homogenisation temperature (Th): a) L-V inclusions with Th from 205 to 255°C and melting temperature of last ice (Tm) from -3 to -9°C. b) L-V inclusions with higher Th from 335 to 385

  1. Miocene magmatism and tectonics within the Peri-Alboran orogen (western Mediterranean)

    Science.gov (United States)

    El Azzouzi, M.; Bellon, H.; Coutelle, A.; Réhault, J.-P.

    2014-07-01

    The aim of this paper concerns Miocene igneous activity in the Alboran Sea and Peri-Alboran area (northern Morocco, western Algeria and Betic Cordilleras in Spain), considering its age and its location with regard to major tectonics structures. We have compiled previous K-Ar isotopic ages of lavas and plutonic boulders and intrusives with an error of ±1σ and completed this set by a new K-Ar isotopic age for andesitic tuffites from Alboran Island. Geochemistry of most of these samples has been considered after previous analyses completed with new data for Spain magmatism. These two sets of data allow us to place the magmatic activity within the regional stratigraphy and tectonics and their chronological framework of the three major tectonic phases of the Maghrebian orogen, at 17 Ma (Burdigalian), 15 Ma (Langhian) and 9 Ma (Tortonian). Petro-geochemical characteristics are compared through time and geographical locations. A major goal of this coupled approach is to help the elaboration of possible geodynamical processes. As an application, we present the case study of the Dellys, Djinet and Thenia region (east of Algiers) where the successive magmatic events between 19.4 ± 1 and 11.6 ± 0.5 Ma are closely related to the local tectonics and sedimentation. The Peri-Alboran igneous activity is placed in a multidisciplinary framework. Timing of activity is defined according to the ages of the neighbouring sedimentary units and the K-Ar ages of igneous rocks. In Spain, the Cabo de Gata-Carboneras magmatic province displays late Oligocene and early Miocene leucogranitic dikes, dated from 24.8 ± 1.3 to 18.1 ± 1.2 Ma; three following andesitic to rhyolitic events took place around 15.1 ± 0.8 to 14.0 ± 0.7 Ma, 11.8 ± 0.6 to 9.4 ± 0.4 Ma, 8.8 ± 0.4 to 7.9 ± 0.4 Ma; this last event displays also granitic rocks. Lamproitic magmas dated between 8.4 ± 0.4 and 6.76 ± 0.04 Ma were emplaced after the Tortonian phase. In Morocco, after the complex building of the Ras Tarf

  2. Multiple fluid sources/pathways and severe thermal gradients during formation of the Jílové orogenic gold deposit, Bohemian Massif, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Zachariáš, J.; Žák, Karel; Pudilová, M.; Snee, L. W.

    2013-01-01

    Roč. 54, October (2013), s. 81-109 ISSN 0169-1368 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 Keywords : Orogenic gold deposits * Carbon isotopes * Oxygen isotopes * Bismuth * Age * Bohemian Massif Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.383, year: 2013

  3. Climate instability and tipping points in the Late Devonian: Detection of the Hangenberg Event in an open oceanic island arc in the Central Asian Orogenic Belt

    Czech Academy of Sciences Publication Activity Database

    Carmichael, A.; Waters, J. A.; Batchelor, C. J.; Coleman, D. M.; Suttner, T. J.; Kido, E.; Moore, L. M.; Chadimová, Leona

    2016-01-01

    Roč. 32, 1 April (2016), s. 213-231 ISSN 1342-937X Institutional support: RVO:67985831 Keywords : Central Asian Orogenic Belt * chemostratigraphy * Devonian-Carboniferous * Hangenberg Event * West Junggar Subject RIV: DB - Geology ; Mineralogy Impact factor: 6.959, year: 2016

  4. Nature and timing of the final collision of Central Asian Orogenic Belt: insights from basic intrusion in the Xilin Gol Complex, Inner Mongolia, China

    NARCIS (Netherlands)

    Li, Y.; Zhou, H.; Brouwer, F.M.; Xiao, W.; Wijbrans, J.R.; Zhao, J.; Zhong, Z.; Liu, H.

    2014-01-01

    The Solonker suture zone of the Central Asian Orogenic Belt (CAOB) records the final closure of the Paleo-Asian Ocean. The nature and timing of final collision along the Solonker suture has long been controversial, partly because of an incomplete record of isotopic ages and differing interpretations

  5. Palaeozoic polymetamorphism in the North Qinling orogenic belt, Central China: Insights from petrology and in situ titanite and zircon U-Pb geochronology

    NARCIS (Netherlands)

    Li, Y.; Zhou, H.; Li, Q.L.; Xiang, H.; Zhong, Z.Q.; Brouwer, F.M.

    2014-01-01

    The Qinling orogenic belt experienced multiple phases of orogenesis during the Palaeozoic. Unraveling the timing and P- T conditions of these events is the key to understanding the convergence processes between the South China and the North China Blocks. The Songshugou Complex, located in the

  6. Bicarbonate-rich fluid inclusions and hydrogen diffusion in quartz from the Libčice orogenic gold deposit, Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Hrstka, Tomáš; Dubessy, J.; Zachariáš, J.

    2011-01-01

    Roč. 281, 3-4 (2011), s. 317-332 ISSN 0009-2541 Institutional research plan: CEZ:AV0Z30130516 Keywords : bicarbonate * fluid inclusions * hydrogen diffusion * orogenic gold deposits * raman spectroscopy Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.518, year: 2011

  7. Two Explanations of Curvature in Variscan Orogen of Moravia: Terrane Segmentation With Clockwise Rotation Vs. Strong Effect of the Moravian Shear Zone

    Czech Academy of Sciences Publication Activity Database

    Hladil, Jindřich; Melichar, R.

    1999-01-01

    Roč. 99, č. 1 (1999), s. 106-107 ISSN 0946-8978. [Old Crust - New Problems: Geodynamics and Utilization Includes the final international colloquium of the DFG priority programme Orogenic Processes Quantification and Modeling in the Variscan Belt. 22.02.1999-26.02.1999, Freiberg/ Saxony ] Subject RIV: DB - Geology ; Mineralogy

  8. Study of the Genetic Diversity of the Ornamental Fish Badis badis (Hamilton-Buchanan, 1822) in the Terai Region of Sub-Himalayan West Bengal, India

    OpenAIRE

    Tanmay Mukhopadhyay; Soumen Bhattacharjee

    2014-01-01

    Dwarf chameleon fish or Badis badis, a lesser known ornamental freshwater fish, has recently been included in the Indian threatened category of fish list. There are insufficient studies with regard to the assessment of genetic background of this ichthyofauna, especially in the western sub-Himalayan region of West Bengal, India, popularly known as the Terai. The present study is the first attempt to investigate the present status of the genetic background of this species in the Mahananda and ...

  9. Reactivation of inherited structures during the opening of the South Atlantic: a low-temperature thermochronology study on the Araçuaí orogenic belt (east Brazilian margin)

    Science.gov (United States)

    Van Ranst, Gerben; De Grave, Johan; Pedrosa-Soares, Antonio Carlos; Tack, Luc; Baudet, Daniel; Novo, Tiago

    2017-04-01

    A subject that has historically been regarded with increasing interest in geology are the supercontinent-cycles. This still poses questions about tectonic evolution on a regional scale, more precisely on the role of reactivation of older, pre-existing structures (inheritance), in which the same faults or weak zones are reactivated rather than the emergence of new systems. A region that is ideally suited for this research is the Araçuaí-West Congo Orogenic belt (AWCO), which is situated partly in eastern Brazil (Gonçalves et al., 2014) and partly in western Africa (D.R. Congo, Congo Brazza, Gabon and Angola; Frimmel et al., 2006; Tack et al., 2001). This orogenic belt was formed during the Cambrian as a result of a series of extension and compression events, of which the final phase is known as the Braziliano-Pan-African orogenesis (e.g. Pedrosa-Soares & Alkmim, 2011). During the break-up of Gondwana and the opening of the South Atlantic, the AWCO became separated. The main part is situated in east Brazil, known as the Araçuaí orogeny, while on the west African margin, the West Congo Belt is a witness to this event. In order to gain a better understanding, the tectonic movements should be placed in an absolute timeframe. Multi-method low-temperature thermochronology lends itself as an ideal tool for this purpose. In this study samples from N-S and E-W profiles in east Brazil (Caparáo-Vitória-Gov. Valadares) have been acquired. These samples are investigated using the apatite fission track (AFT) and apatite (U-Th-Sm)/He (AHe) methods. In a later phase the samples which were taken on profiles in the D.R. Congo (Lower Congo) will be analysed by the same methods. Preliminary results for the Brazilian margin indicate cooling ages ranging between 55 Ma and c. 80 Ma.

  10. Observations of Upward Propagating Gravity Waves in the Vertical Transport of Aerosols during Daytime Boundary Layer Evolution over Central Himalayan Region

    Science.gov (United States)

    Shukla, K. K.; Phani Kumar, D. V.; Kondapalli, N. K.; Kotamarthi, V. R.; Newsom, R. K.

    2014-12-01

    In this study, we present a case study on 16 October 2011 to show the first observational evidence of the influence of short period gravity waves in aerosol transport during daytime over the central Himalayan region. The Doppler lidar data has been utilized to address the daytime boundary layer evolution and related aerosol dynamics over the site. Mixing layer height is estimated by wavelet covariance transform method and found to be ~ 0.7 km, AGL. Aerosol optical depth observations during daytime revealed an asymmetry showing clear enhancement during afternoon hours as compared to forenoon. Interestingly, Fourier and wavelet analysis of vertical velocity and attenuated backscatter showed similar 50-90 min short period gravity wave signatures during afternoon hours. Moreover, our observations showed that gravity waves are dominant within the boundary layer implying that the daytime boundary layer dynamics is playing a vital role in transporting the aerosols from surface to the top of the boundary layer. Similar modulations are also evident in surface parameters like temperature, relative humidity and wind speed indicating these waves are associated with the dynamical aspects over Himalayan region. Finally, time evolution of range-height indicator snapshots during daytime showed strong upward velocities especially during afternoon hours implying that convective processes through short period gravity waves plays a significant role in transporting aerosols from the nearby valley region to boundary layer top over the site. These observations also establish the importance of wave induced daytime convective boundary layer dynamics in the lower Himalayan region.

  11. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Articles written in Journal of Earth System Science. Volume 125 Issue 7 October 2016 pp 1463-1472. Geospatial approach ... Volume 126 Issue 3 April 2017 pp 43. Simulating climate change impact on soil erosion using RUSLE model − A case study in a watershed of mid-Himalayan landscape · Surya Gupta Suresh Kumar.

  12. Three Proterozoic orogenic cycles in the Livingstone Mountains, Tanzania: Evidence from petrology and ion microprobe dating of zircon and monazite

    Science.gov (United States)

    Nitsche, Christoph; Schenk, Volker; Schmitt, Axel; Kazimoto, Emmanuel

    2017-04-01

    The Livingstone Mountains at Lake Nyasa in southern Tanzania are situated in an area where three orogenic belts seem to be overlapping: the Ubendian-Usagaran belts, the Irumide Belt and the East African Orogen, whose formations are linked to the assembly of the Proterozoic supercontinents of Columbia, Rodinia and Gondwana. Granulite-facies migmatitic metapelites and two orthogneisses were studied petrologically and by ion microprobe dating of monazite and zircon to decipher their tectono-metamorphic history and to find out if and to which degree the rocks of the Livingstone Mountains were affected by the different orogenies. Zircon dating of orthogneiss yielded a magmatic age of ca. 2.2 Ga. Texturally controlled ion microprobe U-Pb dating of monazite inclusions in garnet of a Grt-Sil-Bt migmatite in combination with discordant zircon data point to sillimanite-garnet grade metamorphism at 1857±27 Ma during the Ubendian-Usagaran orogeny. Oscillatory zoned concordant zircon of another orthogneiss was dated at 997±8.6 Ma, whereas the age of monazite inclusions in garnet and matrix of a garnet-sillimanite-gneiss revealed an associated high-grade metamorphism at 1067±20 Ma during the Irumide orogeny. Low Th/U overgrowths on orthogneiss zircon and concordant matrix monazite in metapelite are dated at 653±9.1 Ma, which is in agreement with the known ages of Pan-African events in the East African Orogen and in the Ubendian Belt (655-550 Ma) (Möller et al., 2000; Boniface et al, 2012). Garnet is homogeneous in Fe and Mg, but cores are mantled by Ca-rich garnet which shows rim-ward depletion in Ca. Thermobarometry using compositions of garnet rims and matrix minerals yielded 770-820 °C and 7-8 kbar, which we interpret to represent conditions during the Neoproterozoic metamorphic event. The high-grossular mantle might reflect earlier conditions of kyanite-grade metamorphism tentatively correlated with high-pressure metamorphism during the Mesoproterozoic Irumide orogeny

  13. Constraining a Precambrian Wilson Cycle lifespan: An example from the ca. 1.8 Ga Nagssugtoqidian Orogen, Southeastern Greenland

    Science.gov (United States)

    Nicoli, Gautier; Thomassot, Emilie; Schannor, Mathias; Vezinet, Adrien; Jovovic, Ivan

    2018-01-01

    In the Phanerozoic, plate tectonic processes involve the fragmentation of the continental mass, extension and spreading of oceanic domains, subduction of the oceanic lithosphere and lateral shortening that culminate with continental collision (i.e. Wilson cycle). Unlike modern orogenic settings and despite the collection of evidence in the geological record, we lack information to identify such a sequence of events in the Precambrian. This is why it is particularly difficult to track plate tectonics back to 2.0 Ga and beyond. In this study, we aim to show that a multidisciplinary approach on a selected set of samples from a given orogeny can be used to place constraints on crustal evolution within a P-T-t-d-X space. We combine field geology, petrological observations, thermodynamic modelling (Theriak-Domino) and radiogenic (U-Pb, Lu-Hf) and stable isotopes (δ18O) to quantify the duration of the different steps of a Wilson cycle. For the purpose of this study, we focus on the Proterozoic Nagssugtoqidian Orogenic Belt (NOB), in the Tasiilaq area, South-East Greenland. Our study reveals that the Nagssugtoqidian Orogen was the result of a complete three stages juvenile crust production (Xjuv) - recycling/reworking sequence: (I) During the 2.60-2.95 Ga period, the Neoarchean Skjoldungen Orogen remobilised basement lithologies formed at TDM 2.91 Ga with progressive increase of the discharge of reworked material (Xjuv from 75% to 50%; δ18O: 4-8.5‰). (II) After a period of crustal stabilization (2.35-2.60 Ga), discrete juvenile material inputs (δ18O: 5-6‰) at TDM 2.35 Ga argue for the formation of an oceanic lithosphere and seafloor spreading over a period of 0.2 Ga (Xjuv from ca. 2.05 Ga with the accretion of volcanic/magmatic arcs (i.e. Ammassalik Intrusive Complex) and by subduction of small oceanic domains (M1: 520 ± 60 °C at 6.6 ± 1.4 kbar). (III) Continental collision between the North Atlantic Craton and the Rae Craton occurred at 1.84-1.89 Ga. Crustal

  14. Inferred Early Permian Arc Rifting in Bogda Mountain, Southernmost of the Central Asia Orogenic Belt: Evidence from a Peperite Bearing Volcano-Sedimentary Succession

    Science.gov (United States)

    Memtimin, M.; Guo, Z.

    2017-12-01

    Late Paleozoic tectonic history, especially Carboniferous-Permian periods, of the Central Asia Orogenic Belt (CAOB) is considered to be the turning point for the termination of terrane amalgamation and closure of the Paleoasian Ocean. However, the debate about the paleoenvironment and tectonic setting of the region during the period is still not resolved. In this study, we report a set of volcano-sedimentary sequence in the Bogda Mountain of the southernmost of CAOB, which is associated with contemporaneous subaqueous emplacement of and interaction between mafic lava and carbonate sediments. The succession contains four distinct facies including closely packed pillow basalts, pillow basalts with interstitial materials, hyaloclastites and peperites. We discuss their formation and emplacement mechanism, interaction between hot magma-water/unconsolidated sediments and thermal metamorphism during the interaction. Textural features of the sequence, especially hyaloclastites and peperites, provide clear evidence for in situ autofragmentation of lava flows, synvolcanic sedimentation of carbonates, fuel coolant interaction when hot magma bulldozed into wet unconsolidated sediments, and represent autochthonous origin of the succession. Lateral transition of the lithofacies indicate a progressively deepening subaqueous environment, resembling a stepwise evolution from early stage of volcanic intrusion with lower lava flux in shallower water level to increasingly subsiding basin with more lava flux in greater depth. Previous studies determined that the mafic magma was intruded around the Carboniferous-Permian boundary ( 300Ma), and geochemical studies showed the magma was originated from dry depleted mantle with little crustal contamination. Nevertheless, the succession was thought to be fault related allochthones formation which was transferred in as part of a Carboniferous intraplate arc. Combining our findings with the previous study results, we propose a new model to

  15. The Sanfengshan copper deposit and early Carboniferous volcanogenic massive sulfide mineralization in the Beishan orogenic belt, Northwestern China

    Science.gov (United States)

    Wang, Jialin; Gu, Xuexiang; Zhang, Yongmei; Zhou, Chao; He, Ge; Liu, Ruiping

    2018-03-01

    The Sanfengshan copper deposit, located in the Beishan orogenic belt, Northwestern China, is hosted in the lower member of the Hongliuyuan Formation, an early Carboniferous metavolcanic-sedimentary sequence. Mineralization occurs as stratiform, stratiform-like and lenticular orebodies, and comprises of laminated, brecciated, banded, massive, and disseminated ores. The mineralogy is dominated by pyrite, chalcopyrite and sphalerite. Fe-Mn chert is widely distributed and generally occurs as massive, laminated, bands or lenses, which are consistent with the orebody. Alteration at Sanfengshan displays a clear concentric zoning pattern and the footwall alteration is more intense and somewhat thicker than the hanging-wall alteration. Systematic geochemical investigation on the volcanic rocks in this area shows that the basalts of the Hongliuyuan Formation (HLY) are predominantly tholeiites with nearly flat rare earth element (REE) pattern, insignificant negative anomalies of high field strength elements (HFSEs), and low Ti/V and Th/Nb ratios. They were most likely derived from partial melting of depleted asthenospheric mantle and formed in a fore-arc setting during initiation of the southward subduction of the Paleo-Asian Ocean. The basalts of the Maotoushan Formation (MTS) display a calc-alkaline nature and are enriched in large ion lithophile elements (LILEs) and depleted in HFSEs, suggesting an active continental margin setting. Sulfur isotope (δ34S) values of the sulfide and sulfate minerals vary between 0‰ and 5.4‰, which are consistent with sulfur derivation from leaching of the host volcanic rocks, although a direct magmatic contribution cannot be ruled out. The Re-Os isotope data of pyrite yield an isochron age of 353 ± 35 Ma, consistent with the age of the host HLY basalts. Thus, a syngenetic (volcanogenic massive sulfide) model is proposed and it is concluded that the Sanfengshan copper deposit is a typical Cyprus-type VMS deposit that formed in an early

  16. Metamorphic Rock-Hosted Orogenic Gold Deposit Type as a Source of Langkowala Placer Gold, Bombana, Southeast Sulawesi

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    Arifudin Idrus

    2014-06-01

    Full Text Available DOI: 10.17014/ijog.v6i1.114In 2008, placer gold was discovered in Langkowala area (Bombana Regency, Southeast Sulawesi, Indonesia, and more than 60,000 traditional gold miners in the early 2009 have been operating by digging vertical pits and panning active stream sediments. The grade of placer gold ranges from 50 to 140 g/t. Local geological framework indicates that the placer gold is not related to volcanic rock-related hydrothermal gold deposit, e.g. epithermal, skarn or porphyry. This paper describes a preliminary study on possible primary deposit type as a source of the Langkowala (Bombana secondary placer gold. A field study indicates that the Langkowala (Bombana placer/paleoplacer gold is possibly related to gold-bearing quartz veins/veinlets hosted by metamorphic rocks particularly mica schist and metasediments in the area. These quartz veins/veinlets are currently recognized in metamorphic rocks at Wumbubangka Mountains, a northern flank of Rumbia Mountain Range. Sheared, segmented quartz veins/veinlets are of 2 cm to 2 m in width and contain gold in a grade varying between 2 and 61 g/t. At least, there are two generations of the quartz veins. The first generation of quartz vein is parallel to foliation of mica schist and metasediments with general orientation of N 300oE/60o; the second quartz vein generation crosscut the first quartz vein and the foliation of the wallrock. The first quartz veins are mostly sheared/deformed, brecciated, and occasionally sigmoidal, whereas the second quartz veins are relatively massive. The similar quartz veins/veinlets types are also probably present in Mendoke Mountain Range, in the northern side of Langkowala area. This primary gold deposit is called as ‘orogenic gold type’. The orogenic gold deposit could be a new target of gold exploration in Indonesia in the future.

  17. SPECIFIC VELOCITY STRUCTURE OF THE UPPER MANTLE IN THE TRANSBAIKALIA SEGMENT OF THE MONGOLIA-OKHOTSK OROGENIC BELT

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    V. M. Soloviev

    2017-01-01

    Full Text Available The paper presents the results of deep seismic studies on Geophysical Reference Profile 1-SB (Sredneargunsk – Ust-Karenga – Taksimo – Vitim in East Transbaikalia,Russia. The1200 kmlong profile crosses the major tectonic structures of the Central Asian fold belt: the Argun median massif, the Selenga-Stanovoy and Transbaikalia folded regions, and the Baikal rift zone. Its northwestern fragment extends into the Angara-Lena monocline of the Siberian platform. The southeastern (Transbaikalia and northwestern (Baikal-Patom fragments of the profile are based on the spot (differential seismic sounding technique using explosions and 40-tonne vibrators. The south­eastern (Transbaikalia fragment shows small crustal thickness values (~40 km, an almost horizontal position of the Moho, and high velocities of longitudinal waves (~8.4 km/sec beneath the Moho. The analysis of parallelism graphs and the dynamic expression of the wave refracted from the Moho suggests a less than 5–10 km thick layer of high velocities and low gradients below Moho. The database on theterritoryofTransbaikaliaincludes ~200 wave arrival times from large earthquakes, which were refracted at the Moho at distances of ~200–1400 km. As part of the tomographic interpretation, using additional DSS data on the Moho, theterritoryofTransbaikaliahas been mapped to show the patterns of the threshold velocity values at the Moho. The seismic data was used to contour an area with high velocity values in the mantle in the central part of the Mongolia-Okhotsk orogenic belt and the neighboring fold structures of Transbaikalia. According to the analysis of the seismic and geologic data on the study area, the mantle layer with high velocity values in the Mongolian-Okhotsk orogenic belt may be represented by the eclogitic rock plates.

  18. Petrogenesis and tectonic implications of Upper Triassic appinite dykes in the East Kunlun orogenic belt, northern Tibetan Plateau

    Science.gov (United States)

    Liu, Bin; Ma, Chang-Qian; Huang, Jian; Wang, Lian-Xun; Zhao, Shao-Qing; Yan, Rong; Sun, Yang; Xiong, Fu-Hao

    2017-07-01

    This paper presents geochronological, mineralogical, geochemical, and Sr-Nd isotopic data for recently identified Upper Triassic appinite dyke swarms in the East Kunlun orogenic belt (EKOB), northern Tibetan Plateau. Zircon U-Pb isotopic analyses using SHRIMP and LA-ICP-MS techniques yield 206Pb/238U ages of 226.1 ± 1.9 Ma and 226.4 ± 3.5 Ma, which can be interpreted as the crystallization ages of the appinite dykes. All the samples are characterized by high Al2O3 contents, enrichments in light rare earth elements (LREEs) and large ion lithophile elements (LILEs) and strong depletions in Nb, Ta, Ti and P. These characteristics are comparable to those of subduction-related calc-alkaline high-Al basalts. Delayed plagioclase nucleation caused by relatively high-pressure conditions and high H2O contents is the most likely interpretation of the high Al contents. The geochemical and isotopic variations suggest that the appinite dykes were derived from partial melting of a mixed mantle source consisting of enriched lithospheric mantle and MORB-type asthenospheric mantle and had experienced some degree of crustal contamination during migration through continental crust. The appinite dykes are associated with previously documented, contemporaneous high-Ba-Sr and/or high-Sr/Y granites (225-223 Ma) derived from thickened mafic lower crust. These rocks provide important constraints on the compositional variations in the orogenic lithospheric mantle during the Late Triassic and provide evidence of a post-collisional environment associated with lithospheric delamination or slab break-off.

  19. Geochemical Characteristics of Granitoids in southwest Tianshan: Four Stages for Geodynamic Evolution of the Southwest Tianshan Orogenic Belt

    Science.gov (United States)

    Zhu, Y.

    2016-12-01

    Paleozoic intrusive rocks widely exposed in the west Tianshan orogenic belt provides key to understand the geodynamic evolution of the central Asian orogenic belt. A synthesis involving the data for Chinese Yili-central Tianshan and southwest Tianshan and comparison of Kyrgyz Tianshan with a broader dataset including zircon U-Pb ages, zircon Hf isotopic composition, major and trace elements for Paleozoic intrusions are presented to classify the Paleozoic intrusive rocks in four categories which corresponding to subduction of the Terskey Ocean, initial subduction stage of South Tianshan Ocean (STO), major subduction stage of the STO, and collisional to post-collisional stages. The subduction of the Terskey Oceanic crust finally caused the closure of the Terskey Ocean and the opening of the South Tianshan back-arc basin. The development of the Southwest Tianshan back-arc basin formed the STO, which subducted under the Yili-central Tianshan during early Silurian to early Carboniferous, and consequently formed huge arc magmatic rocks. Both the Silurian and early Carboniferous intrusions showing arc geochemical characteristics were derived from partial melting of juvenile arc-derived rocks with involvement of old continental crust. The STO finally closed by the end of early Carboniferous. Afterwards, geodynamic setting changed from convergence to extensional during late Carboniferous to early Permian periods. There is a significant geodynamic change from convergence to extension during late Carboniferous to early Permian, which may be resulted from breakoff of the subducted slab (Fig. 1). Such processes caused upwelling of asthenosphere and triggered partial melting of continental crust, as evidenced by emplacement of voluminous granitic rocks. References: An F, et al, 2013. Journal of Asian Earth Sciences, 78: 100-113; Zhu YF, 2011. Ore Geology Reviews, 40: 108-121; Zhu YF, et al, 2009. Geological Society, London, 166: 1085-1099; Zhu YF et al, 2016. Journal of Earth

  20. Large-scale Desert Dust Deposition on the Himalayan Snow Cover: A Climatological Perspective from Satellite Observations

    Science.gov (United States)

    Gautam, R.; Hsu, N. C.; Lau, W. K.

    2013-12-01

    The Himalaya-Tibetan Plateau (HTP) has a profound influence on the Asian climate. The HTP are also among the largest snow/ice-covered regions on the Earth and provide major freshwater resource to the downstream densely-populated regions of Asia. Recent studies indicate climate warming over the HTP amplified by atmospheric heating and deposition of absorbing aerosols (e.g. dust and soot) over the HTP snowpack and glaciers. Recently, greater attention has focused on the effects of soot deposition on accelerated snowmelt and glacier retreat in the HTP, associated with increasing anthropogenic emissions in Asia. On the other hand, the role of transported dust affecting snow albedo/melt is not well understood over the HTP, in spite of the large annual cycle of mineral dust loading, particularly over the northern parts of south Asia during pre-monsoon season. This study addresses the large-scale effects of dust deposition on snow albedo in the elevated HTP from a satellite observational perspective. Dust aerosol transport, from southwest Asian arid regions, is observed in satellite imagery as darkening of the Himalayan snowpack. Additionally, multi-year spaceborne lidar observations, from CALIPSO, also show dust advected to elevated altitudes (~5km) over the Himalayan foothills, and episodically reaching the top of the western Himalaya. Spectral surface reflectance analysis of dust-laden snow cover (from MODIS) indicates enhanced absorption in the shorter visible wavelengths, yielding a significant gradient in the visible-nearIR reflectance spectrum. While soot in snow is difficult to distinguish from remote sensing, our spectral reflectance analysis of dust detection in the snowpack is consistent with theoretical simulations of snow darkening due to dust impurity. We find that the western HTP, in general, is influenced by enhanced dust deposition due to its proximity to major dust sources (and prevailing dust transport pathways), compared to the eastern HTP. Coinciding

  1. Seasonal changes in surface albedo of Himalayan glaciers from MODIS data and links with the annual mass balance

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    F. Brun

    2015-02-01

    Full Text Available Few glaciological field data are available on glaciers in the Hindu Kush–Karakoram–Himalayan (HKH region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India and Mera Glacier (Everest region, Nepal, and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG and glacier-wide annual mass balance (Ba measured with the glaciological method (R2 = 0.75. At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and Ba suggests that AMAAG can be used as a proxy for the maximum snow line altitude or equilibrium line altitude (ELA on winter-accumulation-type glaciers in the Himalayas. However, for the summer-accumulation-type Mera Glacier, our approach relied on the hypothesis that ELA information is preserved during the monsoon. At Mera Glacier, cloud obscuration and snow accumulation limits the detection of albedo during the monsoon, but snow redistribution and sublimation in the post-monsoon period allows for the calculation of AMAAG. Reconstructed Ba at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degree-day method. Reconstructed Ba at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and Ba is constrained over a shorter time period for Mera Glacier (6 years than for Chhota Shigri Glacier (11 years. Thus the mass balance reconstruction

  2. Antioxidant Capacities, Phenolic Profile and Cytotoxic Effects of Saxicolous Lichens from Trans-Himalayan Cold Desert of Ladakh

    Science.gov (United States)

    Kumar, Jatinder; Dhar, Priyanka; Tayade, Amol B.; Gupta, Damodar; Chaurasia, Om P.; Upreti, Dalip K.; Arora, Rajesh; Srivastava, Ravi B.

    2014-01-01

    Fourteen saxicolous lichens from trans-Himalayan Ladakh region were identified by morpho-anatomical and chemical characteristics. The n-hexane, methanol and water extracts of the lichens were evaluated for their antioxidant capacities. The lichen extracts showing high antioxidant capacities and rich phenolic content were further investigated to determine their cytotoxic activity on human HepG2 and RKO carcinoma cell lines. The ferric reducing antioxidant power (FRAP), 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide (NO) radical scavenging capacities and β-carotene-linoleic acid bleaching property exhibited analogous results where the lichen extracts showed high antioxidant action. The lichen extracts were also found to possess good amount of total proanthocyanidin, flavonoid and polyphenol. The methanolic extract of Lobothallia alphoplaca exhibited highest FRAP value. Methanolic extract of Xanthoparmelia stenophylla showed the highest ABTS radical scavenging capacity. The n-hexane extract of Rhizoplaca chrysoleuca exhibited highest DPPH radical scavenging capacity. Highest antioxidant capacity in terms of β-carotene linoleic acid bleaching property was observed in the water extract of Xanthoria elegans. Similarly, Melanelia disjuncta water extract showed highest NO scavenging capacity. Among n-hexane, methanol and water extracts of all lichens, the methanolic extract of Xanthoparmelia mexicana showed highest total proanthocyanidin, flavonoid and polyphenol content. From cytotoxic assay, it was observed that the methanolic extracts of L. alphoplaca and M. disjuncta were exhibiting high cytotoxic effects against cancer cell growth. Similarly, the water extract of Dermatocarpon vellereum, Umbilicaria vellea, X. elegans and M. disjuncta and the methanolic extract of M. disjuncta and X. stenophylla were found to possess high antioxidant capacities and were non-toxic and may be used

  3. The strong motion amplitudes from Himalayan earthquakes and a pilot study for the deterministic first order microzonation of Delhi City

    International Nuclear Information System (INIS)

    Parvez, Imtiyaz A.; Panza, G.F.; Gusev, A.A.; Vaccari, F.

    2001-09-01

    The interdependence among the strong-motion amplitude, earthquake magnitude and hypocentral distance has been established (Parvez et al. 2001) for the Himalayan region using the dataset of six earthquakes, two from Western and four from Eastern Himalayas (M w =5.2-7.2) recorded by strong-motion networks in the Himalayas. The level of the peak strong motion amplitudes in the Eastern Himalayas is three fold larger than that in the Western Himalayas, in terms of both peak acceleration and peak velocities. In the present study, we include the strong motion data of Chamoli earthquake (M w =6.5) of 1999 from the western sub-region to see whether this event supports the regional effects and we find that the new result fits well with our earlier prediction in the Western Himalayas. The minimum estimates of peak acceleration for the epicentral zone of M w =7.5-8.5 events is A peak =0.25-0.4 g for the Western Himalayas and as large as A peak =1.0-1.6 g for the Eastern Himalayas. Similarly, the expected minimum epicentral values of V peak for M w =8 are 35 cm/s for Western and 112 cm/s for Eastern Himalayas. The presence of unusually high levels of epicentral amplitudes for the eastern subregion also agrees well with the macroseismic evidence (Parvez et al. 2001). Therefore, these results represent systematic regional effects, and may be considered as a basis for future regionalized seismic hazard assessment in the Himalayan region. Many metropolitan and big cities of India are situated in the severe hazard zone just south of the Himalayas. A detailed microzonation study of these sprawling urban centres is therefore urgently required for gaining a better understanding of ground motion and site effects in these cities. An example of the study of site effects and microzonation of a part of metropolitan Delhi is presented based on a detailed modelling along a NS cross sections from the Inter State Bus Terminal (ISBT) to Sewanagar. Full synthetic strong motion waveforms have been

  4. New Ar/Ar single grain mineral ages from Korean orogenic belts with implications for the Triassic cooling and exhumation history

    Science.gov (United States)

    de Jong, Koenraad; Ruffet, Gilles; Han, Seokyoung

    2013-04-01

    The Korean peninsula is located in the eastern margin of the Eurasian continent where major late Palaeozoic to early Mesozoic continental collision zones, like the Central Asian Orogenic Belt and the Qinling-Dabie-Sulu Belt, merge with circum-Pacific subduction-accretion systems. Deciphering the tectonic evolution of Korea is thus crucial for the understanding of the amalgamation of East Asia. Classically, research in Korea has focused on the search for (ultra)high-pressure metamorphic rocks and their isotopic dating, most recently applying SHRIMP on Th- and U-bearing accessory minerals, in order to substantiate links with the Qinling-Dabie-Sulu Belt across the Yellow Sea in China. Instead of trying to date peak pressure conditions we focused on 40Ar/39Ar laser-probe step-heating dating of single grains of the fabric-forming minerals muscovite, biotite and amphibole, formed during retrograde recrystallisation and exhumation. This is a big advantage as their growth can be straightforwardly correlated to major phases of the tectono-metamorphic evolution of rocks. This approach helps to meet the major geochronological challenge of obtaining age estimates for the timing of specific tectono-metamorphic events in the Korean orogenic belts. The Korean peninsula comprises a number of Palaeoproterozoic high-grade gneiss terranes; only one of which has been affected by Permo-Triassic metamorphism: the Gyeonggi Massif. We concentrated on the uppermost Gyeonggi Massif and the overlying Imjingang Belt, to the North, and the ill-defined Hongseong zone to the West, both constituted by younger metamorphic rocks. Both belts contain rare lenses of mafic rocks with relics of high-pressure metamorphism. Hornblende from a corona-textured amphibolite from the lowermost part of the Imjingang Belt yielded a U-shaped age spectrum, the base of which is formed by four concordant steps with a weighted mean age of 242.8 ± 2.4 Ma (15% 39Ar release). Muscovites from strongly retrogressed and

  5. Secondary Inorganic Aerosols over an Urban Location in North-Western Himalayan Region: Seasonal Variation in Composition and Formation Process(es)

    Science.gov (United States)

    Kaushal, D.; Tandon, A.

    2017-12-01

    Oxidative photo-chemical transformation of precursor gases, mainly of anthropogenic origin, produces secondary aerosols. Secondary inorganic aerosols constitute a significant fraction of total aerosol load over urban locations especially high altitude in wet-temperate climatic set-up. Towns situated in North-Western Himalayan region (NWHR) with sizable population and attractive tourist destinations have been facing ever increasing problem of gaseous and particulate air pollution from exponential increase in vehicular traffic and other anthropogenic emissions. The present study has been planned to investigate the seasonal variations in atmospheric processes responsible for the formation of Secondary Inorganic Aerosols (SIA) and to estimate contribution of SIA to PM­10 load over an Urban location, Dharamshala, in Dhauladhar region of NWHR. Twenty four hourly PM10 aerosol samples were collected, on quartz micro fibre filters in Dharamshala (1350 amsl) on weekly basis for complete one year time-period (February 2015 - January 2016). These samples were analyzed for Water Soluble Inorganic Ions (WSII) using Ion-Chromatographic System. On annual basis, SO42- ions contributed maximum (52%) followed by NO3- (13%) and NH4+ (12%) to WSII. Based upon Principal Component Analysis (PCA), dominant sources contributing to PM10 associated WSII were identified as: Fossil-Fuel and Bio-mass burning, Vehicular (mainly diesel) emissions and gaseous emissions from the microbial degradation of dead bio-mass. Throughout the year, significantly high proportion of SO42- and considerable thermodynamic stability of (NH4)2SO2 at ambient temperatures, made it the major contributor to SIA over NH4NO3 and NH4Cl. On seasonal basis, maximum contribution of SIA to PM10 was observed in monsoon followed by the winter season. Low ambient temperature in winter season favoured formation of NH4NO3 with significant contribution to SIA. It could be concluded that observed variability in the composition and

  6. Assessment of Antioxidant Properties in Fruits of Myrica esculenta: A Popular Wild Edible Species in Indian Himalayan Region

    Directory of Open Access Journals (Sweden)

    Sandeep Rawat

    2011-01-01

    Full Text Available Crude extract of Myrica esculenta fruits, a wild edible species of Indian Himalayan Region, was evaluated for phenolic compounds and antioxidant properties. Results revealed significant variation in total phenolic and flavonoid contents across populations. Among populations, total phenolic content varied between 1.78 and 2.51 mg gallic acid equivalent/g fresh weight (fw of fruits and total flavonoids ranged between 1.31 and 1.59 mg quercetin equivalent/g fw. Antioxidant activity determined by 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid radical scavenging, 1,1-diphenyl-2-picrylhydrazyl radical scavenging and ferric reducing antioxidant power (FRAP exhibited considerable antioxidant potential and showed significant positive correlation with total phenolic and total flavonoids content. High performance liquid chromatography analysis revealed significant variation (P <  .01 in phenolic compounds (i.e., gallic acid, catechin, hydroxybenzioc acid and ρ-coumaric acid across populations. This study provides evidences to establish that consumption of M. esculenta fruits while providing relished taste would also help in reduction of free radicals. Therefore, this wild edible species deserves promotion in the region through horticulture and forestry interventions.

  7. Capturing forest dependency in the central Himalayan region: Variations between Oak (Quercus spp.) and Pine (Pinus spp.) dominated forest landscapes.

    Science.gov (United States)

    Chakraborty, Anusheema; Joshi, Pawan Kumar; Sachdeva, Kamna

    2017-10-05

    Our study explores the nexus between forests and local communities through participatory assessments and household surveys in the central Himalayan region. Forest dependency was compared among villages surrounded by oak-dominated forests (n = 8) and pine-dominated forests (n = 9). Both quantitative and qualitative analyses indicate variations in the degree of dependency based on proximity to nearest forest type. Households near oak-dominated forests were more dependent on forests (83.8%) compared to households near pine-dominated forests (69.1%). Forest dependency is mainly subsistence-oriented for meeting basic household requirements. Livestock population, cultivated land per household, and non-usage of alternative fuels are the major explanatory drivers of forest dependency. Our findings can help decision and policy makers to establish nested governance mechanisms encouraging prioritized site-specific conservation options among forest-adjacent households. Additionally, income diversification with respect to alternate livelihood sources, institutional reforms, and infrastructure facilities can reduce forest dependency, thereby, allowing sustainable forest management.

  8. Landslide hazard assessment along a mountain highway in the Indian Himalayan Region (IHR) using remote sensing and computational models

    Science.gov (United States)

    Krishna, Akhouri P.; Kumar, Santosh

    2013-10-01

    Landslide hazard assessments using computational models, such as artificial neural network (ANN) and frequency ratio (FR), were carried out covering one of the important mountain highways in the Central Himalaya of Indian Himalayan Region (IHR). Landslide influencing factors were either calculated or extracted from spatial databases including recent remote sensing data of LANDSAT TM, CARTOSAT digital elevation model (DEM) and Tropical Rainfall Measuring Mission (TRMM) satellite for rainfall data. ANN was implemented using the multi-layered feed forward architecture with different input, output and hidden layers. This model based on back propagation algorithm derived weights for all possible parameters of landslides and causative factors considered. The training sites for landslide prone and non-prone areas were identified and verified through details gathered from remote sensing and other sources. Frequency Ratio (FR) models are based on observed relationships between the distribution of landslides and each landslide related factor. FR model implementation proved useful for assessing the spatial relationships between landslide locations and factors contributing to its occurrence. Above computational models generated respective susceptibility maps of landslide hazard for the study area. This further allowed the simulation of landslide hazard maps on a medium scale using GIS platform and remote sensing data. Upon validation and accuracy checks, it was observed that both models produced good results with FR having some edge over ANN based mapping. Such statistical and functional models led to better understanding of relationships between the landslides and preparatory factors as well as ensuring lesser levels of subjectivity compared to qualitative approaches.

  9. Genetic relatedness among indigenous rice varieties in the Eastern Himalayan region based on nucleotide sequences of the Waxy gene.

    Science.gov (United States)

    Choudhury, Baharul I; Khan, Mohammed L; Dayanandan, Selvadurai

    2014-12-29

    Indigenous rice varieties in the Eastern Himalayan region of Northeast India are traditionally classified into sali, boro and jum ecotypes based on geographical locality and the season of cultivation. In this study, we used DNA sequence data from the Waxy (Wx) gene to infer the genetic relatedness among indigenous rice varieties in Northeast India and to assess the genetic distinctiveness of ecotypes. The results of all three analyses (Bayesian, Maximum Parsimony and Neighbor Joining) were congruent and revealed two genetically distinct clusters of rice varieties in the region. The large group comprised several varieties of sali and boro ecotypes, and all agronomically improved varieties. The small group consisted of only traditionally cultivated indigenous rice varieties, which included one boro, few sali and all jum varieties. The fixation index analysis revealed a very low level of differentiation between sali and boro (F(ST) = 0.005), moderate differentiation between sali and jum (F(ST) = 0.108) and high differentiation between jum and boro (F(ST) = 0.230) ecotypes. The genetic relatedness analyses revealed that sali, boro and jum ecotypes are genetically heterogeneous, and the current classification based on cultivation type is not congruent with the genetic background of rice varieties. Indigenous rice varieties chosen from genetically distinct clusters could be used in breeding programs to improve genetic gain through heterosis, while maintaining high genetic diversity.

  10. Rupture process of the Mw7.9 2015 Gorkha earthquake (Nepal): insights into Himalayan megathrust segmentation

    Science.gov (United States)

    Grandin, Raphaël; Vallée, Martin; Satriano, Claudio; Lacassin, Robin; Klinger, Yann; Simoes, Martine; Bollinger, Laurent

    2016-04-01

    We investigate the rupture process of the 25 April 2015 Gorkha earthquake (Mw7.9) using a kinematic joint inversion of teleseismic waves, strong-motion data, high-rate GPS, static GPS and SAR data. The rupture is found to be simple in terms of coseismic slip and even more in terms of rupture velocity, as both inversion results and a complementing back projection analysis show that the main slip patch broke unilaterally at a steady velocity of 3.1-3.3km/s. This feature likely contributes to the moderate peak ground acceleration (0.2g) observed in Kathmandu. The ~15km deep rupture occurs along the base of the coupled portion of the Main Himalayan Thrust, and does not break the area ranging from Kathmandu to the front. The limitation in length and width of the rupture cannot be identified in the pre-earthquake interseismic coupling distribution, and is therefore discussed in light of the structural architecture of the megathrust.

  11. Rupture process of the Mw = 7.9 2015 Gorkha earthquake (Nepal): Insights into Himalayan megathrust segmentation

    Science.gov (United States)

    Grandin, Raphaël.; Vallée, Martin; Satriano, Claudio; Lacassin, Robin; Klinger, Yann; Simoes, Martine; Bollinger, Laurent

    2015-10-01

    We investigate the rupture process of the 25 April 2015 Gorkha earthquake (Mw = 7.9) using a kinematic joint inversion of teleseismic waves, strong motion data, high-rate GPS, static GPS, and synthetic aperture radar (SAR) data. The rupture is found to be simple in terms of coseismic slip and even more in terms of rupture velocity, as both inversion results and a complementing back projection analysis show that the main slip patch broke unilaterally at a steady velocity of 3.1-3.3 km/s. This feature likely contributes to the moderate peak ground acceleration (0.2 g) observed in Kathmandu. The ~15 km deep rupture occurs along the base of the coupled portion of the Main Himalayan Thrust and does not break the area ranging from Kathmandu to the front. The limitation in length and width of the rupture cannot be identified in the preearthquake interseismic coupling distribution and is therefore discussed in light of the structural architecture of the megathrust.

  12. Digitizing information for wider reach through 'him-Padap-Sanklan', an e-inventory of Himalayan flora

    Directory of Open Access Journals (Sweden)

    Amit Kumar

    2014-09-01

    Full Text Available 'him-Padap-Sankalan' is a digital directory of floral resources of Himachal Pradesh H.P., a biologically rich state of the Himalayan Biodiversity hotspot. It provides information on nomenclature, taxonomic classification, local name(s, trade name(s and uses of 3348 plant species along with maps showing their distribution in H.P. The information housed in 'Him-Padap-Sankalan' has been compiled from published sources, primarily the Flora of Himachal Pradesh: Analysis. The Graphic User Interface of the 'him-Padap-Sankalan' has been prepared using ASP.Net having MS-Access database in the back end. The 'scientific names', 'trade names', 'local names', 'synonyms', 'genus' and 'species' are the various search modules of 'him-Padap-Sankalan', which can be accessed using an internet browser connected through local area network. Analysis of information reveals that of the 201 families, Poaceae, Asteraceae, Papilionaceae, Scrophularariaceae, Rosaceae, Cyperaceae, Lamiaceae, Ranunculaceae, Brassicaceae and Apiaceae are the ten dominat families in the state. 24 families and 18 genera are common to all the 12 districts of H.P. The maximum number of families, genera and species are in Shimla district and the least in Bilaspur district of H.P.

  13. Drying, burning and emission characteristics of beehive charcoal briquettes: an alternative household fuel of Eastern Himalayan Region.

    Science.gov (United States)

    Mandal, S; Kumar, Arvind; Singh, R K; Kundu, K

    2014-05-01

    Beehive charcoal briquettes were produced from powdered charcoal in which soil was added as binder. It was found to be an eco-friendly, clean and economic alternative source of household fuel for the people of Eastern Himalayan Region. Experiments were conducted to determine natural drying behaviour, normalised burn rate, temperature profile and emission of CO, CO2, UBHC (unburnt hydrocarbons) and NO(x) of beehive briquettes prepared from 60:40; 50:50 and 40:60 ratios of charcoal and soil. It was observed that under natural drying conditions (temperature, humidity) briquettes took 433 hr to reach equilibrium moisture content of 5.56-10.29%. Page's model was found suitable to describe the drying characteristics of all three combinations. Normalised burn rate varied between 0.377-0.706% of initial mass min⁻¹. Total burning time of briquette ranged between 133-143 min. The peak temperature attained by briquettes ranged from 437 °C to 572 °C. All the briquette combinations were found suitable for cooking and space heating. Emission of CO, CO2, UBHC, NO and NO2 ranged between 68.4-107.2, 922-1359, 20.9-50.8, 0.19-0.29 and 0.34-0.64 g kg⁻¹, respectively which were less than firewood.

  14. Himalayan ibex (Capra ibex sibirica habitat suitability and range resource dynamics in the Central Karakorum National Park, Pakistan

    Directory of Open Access Journals (Sweden)

    Garee Khan

    2016-07-01

    Full Text Available The study investigates Himalayan ibex (Capra ibex sibirica and their range resource condition within the preferred habitat in the Central Karakoram National Park, Pakistan. We apply ecological niche factor analysis (ENFA using 110 ibex sighting data and 6 key biophysical variables describing the habitat conditions and produce habitat suitability and maps with GIS and statistical tool (BioMapper. The modeling results of specialization factor shows some limitation for ibex over the use of slope, elevation, vegetation types and ruggedness. The habitat area selection for the ibex is adjusted to the ibex friendly habitat available conditions. The model results predicted suitable habitat for ibex in certain places, where field observation was never recorded. The range resource dynamics depict a large area that comes under the alpine meadows has the highest seasonal productivity, assessed by remote sensing based fortnightly vegetation condition data of the last 11 years. These meadows are showing browning trend over the years, attributable to grazing practices or climate conditions. At lower elevation, there are limited areas with suitable dry steppes, which may cause stress on ibex, especially during winter.

  15. The Australasian frog family Ceratobatrachidae in China, Myanmar and Thailand: discovery of a new Himalayan forest frog clade.

    Science.gov (United States)

    Yan, Fang; Jiang, Ke; Wang, Kai; Jin, Jie-Qiong; Suwannapoom, Chatmongkon; Li, Cheng; Vindum, Jens V; Brown, Rafe M; Che, Jing

    2016-01-18

    In an effort to study the systematic affinities and specieslevel phylogenetic relationships of the enigmatic anurans variably assigned to the genera Ingerana or Limnonectes (family Dicroglossidae), we collected new molecular sequence data for five species including four Himalayan taxa, Limnonectes xizangensis, Lim. medogensis, Lim. alpina, [corrected] Ingerana borealis and one southeast Asian species, I. tasanae, and analyzed these together with data from previous studies involving other ostensibly related taxa. Our surprising results demonstrate unequivocally that Lim. xizangensis, Lim. medogensis and Lim. alpina [corrected] form a strongly supported clade, the sister-group of the family Australasian forest frog family Ceratobatrachidae. This discovery requires an expansion of the definition of Ceratobatrachidae and represents the first record of this family in China. These three species are distinguished from the species of Ingerana and Limnonectes by the: (1) absence of interdigital webbing of the foot, (2) absence of terminal discs on fingers and toes, (3) absence of circumarginal grooves on the fingers and toes, and (4) absence of tarsal folds. Given their phylogenetic and morphological distinctiveness, we assign them to the oldest available generic name for this clade, Liurana Dubois 1987, and transfer Liurana from Dicroglossidae to the family Ceratobatrachidae. In contrast, Ingerana tasanae was found to be clustered with strong support with the recently described genus Alcalus (Ceratobatrachidae), a small clade of otherwise Sundaic species; this constitutes a new record of the family Ceratobatrachidae for Myanmar and Thailand. Finally, Ingerana borealis clustered with the "true" Ingerana (family Dicroglossidae), for which the type species is I. tenasserimensis.

  16. The Australasian frog family Ceratobatrachidae in China, Myanmar and Thailand: discovery of a new Himalayan forest frog clade

    Science.gov (United States)

    YAN, Fang; JIANG, Ke; WANG, Kai; JIN, Jie-Qiong; SUWANNAPOOM, Chatmongkon; LI, Cheng; Jens, V. VINDUM; Rafe, M. BROWN; CHE, Jing

    2016-01-01

    In an effort to study the systematic affinities and specieslevel phylogenetic relationships of the enigmatic anurans variably assigned to the genera Ingerana or Limnonectes (family Dicroglossidae), we collected new molecular sequence data for five species including four Himalayan taxa, Limnonectes xizangensis, Lim. medogensis, Lim. alpine, Ingerana borealis and one southeast Asian species, I. tasanae, and analyzed these together with data from previous studies involving other ostensibly related taxa. Our surprising results demonstrate unequivocally that Lim. xizangensis, Lim. medogensis and Lim. alpine form a strongly supported clade, the sister-group of the family Australasian forest frog family Ceratobatrachidae. This discovery requires an expansion of the definition of Ceratobatrachidae and represents the first record of this family in China. These three species are distinguished from the species of Ingerana and Limnonectes by the: (1) absence of interdigital webbing of the foot, (2) absence of terminal discs on fingers and toes, (3) absence of circumarginal grooves on the fingers and toes, and (4) absence of tarsal folds. Given their phylogenetic and morphological distinctiveness, we assign them to the oldest available generic name for this clade, Liurana Dubois 1987, and transfer Liurana from Dicroglossidae to the family Ceratobatrachidae. In contrast, Ingerana tasanae was found to be clustered with strong support with the recently described genus Alcalus (Ceratobatrachidae), a small clade of otherwise Sundaic species; this constitutes a new record of the family Ceratobatrachidae for Myanmar and Thailand. Finally, Ingerana borealis clustered with the "true" Ingerana (family Dicroglossidae), for which the type species is I. tenasserimensis. PMID:26828029

  17. THE CONSERVATION AND POTENTIAL HABITAT OF THE HIMALAYAN MUSK DEER, MOSCHUS CHRYSOGASTER, IN THE PROTECTED AREAS OF NEPAL

    Directory of Open Access Journals (Sweden)

    Achyut ARYAL

    2011-06-01

    Full Text Available The Himalayan musk deer (Moschus chrysogaster is a cervid distributed from the eastern to the western Himalayas of Nepal. The species is listed as endangered in appendix I of IUCN Red data, and protected in Nepal under the National Parks and Wildlife Conservation Act of 1973. Musk deer occupy the middle to the higher mountain regions, which cover 12 protected areas of Nepal (6 national parks, 5 conservation areas, 1 hunting reserve. However, of the 30177.19 km2 potential habitat, only 19.26% (5815.08 km2 is inside the protected areas and the remaining 80.73% falls outside the protected areas. Consequently, poaching, habitat destruction, livestock grazing and forest fire in the musk deer habitat are important challenges for the conservation of musk deer in the country. A thorough status survey in and outside the protected areas should be carried out and a species-focused conservation action plan should be prepared and implemented properly. A program for increasing awareness and enhancing livelihood of the local populations be launched in the poor and poaching risk zones of Nepal.

  18. Crustal structure of a Proterozoic craton boundary: east Albany-Fraser Orogen, Western Australia, imaged with passive seismic and gravity anomaly data

    Science.gov (United States)

    Sippl, Christian; Brisbout, Lucy; Spaggiari, Catherine; Gessner, Klaus; Tkalcic, Hrvoje; Kennett, Brian; Murdie, Ruth

    2017-04-01

    We use passive seismic and gravity data to characterize the crustal structure and the crust-mantle boundary of the east Albany-Fraser Orogen in Western Australia, a Proterozoic orogen that reworked the southern and southeastern margin of the Archean Yilgarn Craton. The crustal thickness pattern retrieved from receiver functions shows a belt of substantially thickened crust - about 10 km thicker than the surrounding regions - that follows the trend of the orogen, but narrows to the southwest. Common conversion point profiles show a clear transition from a wide, symmetric Moho trough in the northeast to a one-sided, north-western Moho dip in the southwest, where the Moho appears to underthrust the craton towards its interior. The change from a Moho trough to an underthrust Moho appears to coincide with the inferred trace of the Ida Fault, a major terrane boundary within the Yilgarn Craton. Bulk crustal vp/vs ratios are mostly in the felsic to intermediate range, with clearly elevated values (≥1.8) at stations in the Fraser Zone granulite facies, dominantly mafic metamorphic rocks. Forward modelling of gravity anomaly data using the retrieved Moho geometry as a geometric constraint shows that a conspicuous, elongated gravity low on the northwestern side of the eastern Albany-Fraser Orogen is almost certainly caused by thickened Archean crust. To obtain a model that resembles the regional gravity pattern the following assumptions are necessary: high-density rocks occur in the upper crustal portion of the Fraser Zone, at depth inside the Moho trough and in parts of the eastern Nornalup Zone east of the Moho trough. Although our gravity models do not constrain at which crustal level these high-density rocks occur, active deep seismic surveys suggest that large extents of the east Albany-Fraser Orogen's lower crust include a Mesoproterozoic magmatic underplate known as the Gunnadorrah Seismic Province. The simplest interpretation of the imaged crustal structure is that

  19. Records of Mesoproterozoic taphrogenic events in the eastern basement of the Araçuaí Orogen, southeast Brazil

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    Tobias Maia Rabelo Fonte-Boa

    Full Text Available ABSTRACT: The history of palaeocontinents alternates long fragmentation to drift periods with relatively short agglutination intervals. One of the products of a Rhyacian-Orosirian orogeny was a palaeocontinent that brought together the basement of the Araçuaí-West Congo orogen (AWCO with regions now located in the São Francisco and Congo cratons. From ca. 2 Ga to ca. 0.7 Ga, this large region of the São Francisco-Congo palaeocontinent was spared of orogenic events, but underwent at least five taphrogenic events recorded by anorogenic magmatism and/or sedimentation. The taphrogenic events are well documented in the AWCO proximal portions and neighboring cratonic regions, but lack evidence in the AWCO high-grade core. Our studies on amphibolites intercalated in the Rhyacian Pocrane complex, basement of the Rio Doce magmatic arc, allowed to the recognition of two Mesoproterozoic taphrogenic episodes. The oldest one, a Calymmian episode, is recorded by amphibolites with a zircon magmatic crystallization age at 1529 ± 37 Ma (U-Pb SHRIMP, and lithochemical signature of basaltic magmatism related to continental intraplate settings. Another set of amphibolite bodies records the youngest taphrogenic episode, a Stenian event, with a zircon magmatic crystallization age at 1096 ± 20 Ma (U-Pb SHRIMP, and lithochemical signature similar to mature magmatism of continental rift setting. The Calymmian episode (ca. 1.5 Ga correlates to the Espinhaço II basin stage and mafic dikes of the northern Espinhaço, Chapada Diamantina and Curaçá domains, while the Stenian episode (ca. 1.1 Ga correlates to the Espinhaço III basin stage. We also present U-Pb data for 87 detrital zircon grains from a quartzite lens intercalated in the Pocrane complex, the Córrego Ubá quartzite. Its age spectrum shows main peaks at 1176 ± 21 Ma (35%, 1371 ± 30 Ma (18%, 1536 ± 22 Ma (19%, 1803 ± 36 Ma (17% and 1977 ± 38 Ma (12%, suggesting a Stenian (ca. 1176 Ma maximum

  20. Comparative tectonic and dynamic analysis of cratons, orogens, basins, and metallogeny: A special volume to honor the career of Brian F. Windley

    Science.gov (United States)

    Kusky, Tim; Xiao, Wenjiao

    2015-11-01

    Cratons, orogens, and basins of the world each show a distinctive pattern of evolution and metallogeny, and relationships to supercontinent cycles. Some aspects of these histories have remained similar through time, yet others have changed with Earth's changing biota, heat production and flow, and atmospheric composition and temperature. To understand the similarities and differences between these cratons, orogens, and basins through time, we need systematic comparative tectonic analyses between these different elements from similar and widely different ages. One of the pioneers in comparative tectonic analysis is Brian F. Windley, whose research has spanned all of these topics, and more, for more than five decades. This special issue is a tribute to his career.

  1. Geothermal structure of the eastern Black Sea basin and the eastern Pontides orogenic belt: Implications for subduction polarity of Tethys oceanic lithosphere

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    Nafiz Maden

    2013-07-01

    Full Text Available The numerical results of thermal modeling studies indicate that the lithosphere is cold and strong beneath the Black Sea basin. The thermal lithospheric thickness increases southward from the eastern Pontides orogenic belt (49.4 km to Black Sea basin (152.2 km. The Moho temperature increases from 367 °C in the trench to 978 °C in the arc region. The heat flow values for the Moho surface change between 16.4 mW m−2 in the Black Sea basin and 56.9 mW m−2 in the eastern Pontides orogenic belt. Along the southern Black Sea coast, the trench region has a relatively low geothermal potential with respect to the arc and back-arc region. The numerical studies support the existence of southward subduction beneath the Pontides during the late Mesozoic–Cenozoic.

  2. Evidences for an orogenic-induced global cooling at the Frasnian-Famennian boundary (ca 376 Ma BP)

    Science.gov (United States)

    Averbuch, O.; Tribovillard, N.; Devleeschouwer, X.; Riquier, L.

    2003-04-01

    Late Devonian time (Famennian, 376--362 Ma BP) is a period of both intense orogenic activity and drastic climatic variations with the onset of a major glaciation event upon parts of the Gondwanian Southern America and Africa situated in high southern latitudes. This global cooling event is coeval with a significant fall in the atmospheric CO_2 content as suggested both by stomatal data and modelling. In the stratigraphic record, the Frasnian-Famennian transition is characterized by a great loss of biotic diversity and pronounced environmental changes with the demise of reefal carbonate platforms and the deposition of extensive organic-rich levels (Kellwasser levels) in Late Frasnian times followed by a rapid global scale sea-level fall and an increase in detrital input in the basal Famennian. We propose to relate the Famennian global cooling and the associated environnmental changes to the development of major mountain cordilleras extending on one hand from the Urals to South America (including the Central Asian, the European, the Northern African, the Appalachian belts) and on the other hand from the western American Antler to the Arctic Ellesmerian belt. Extensive high pressure metamorphic rocks dated between ca 380 and 360 Ma BP, pervasive deformations distributed along the belt (Eo-Variscan phase) and synorogenic molassic rocks trapped within the flexural foreland basins indicate a major collisional event in Late Frasnian-Famennian times inducing an important crustal thickening and associated high continental relief. The major drop in the atmospheric CO2 content would be driven by the conjunction of two orogenic-induced mechanisms : (1) the intensification of silicate weathering on the continental areas as attested by a major rise in the 87Sr/86Sr composition of sea water at the Frasnian-Famennian boundary ; the coeval development of vascular plants on emerged lands is also probably an important factor in enhanced chemical weathering of continental soils (2

  3. Origins of two types of serpentinites from the Qinling orogenic belt, central China and associated fluid/melt-rock interactions

    Science.gov (United States)

    Wu, Kai; Ding, Xing; Ling, Ming-Xing; Sun, Wei-dong; Zhang, Li-Peng; Hu, Yong-Bin; Huang, Rui-Fang

    2018-03-01

    Serpentinites are important volatile and fluid mobile element repositories in oceanic lithosphere and subduction zones, and thus provide significant constraints on global geochemical cycles and tectonic evolution at convergent margins. In this contribution, two types of serpentinites from the Mianlue suture zone in the Qinling orogenic belt, central China, are identified on the basis of detailed mineralogical and geochemical study. Serpentinites from the Jianchaling region (Group 1) are composed of lizardite/chrysotile + magnesite + magnetite. Most of these serpentinites (Group 1a), consist of pseudomorphic orthopyroxene and olivine, and are characterized by low Al2O3/SiO2, high MgO/SiO2 and Ir-type PGEs to Pt ratios, suggesting a residual mantle origin. Meanwhile, the U-shape REE pattern and positive Eu, Sr and Ba anomalies of these serpentinites indicate that serpentinization fluids have interacted with gabbroic cumulates at moderately high temperatures or associate with the chlorinity and redox conditions of the fluid. Considering the limited mobility of U in the hydrating fluids for the Group 1a serpentinites, hydrating fluids for these serpentinites are most likely derived from the dehydrated slab, and have been in equilibrium with subducting sediments. There are also some serpentinites with low-grade metamorphic recrystallization from the Jianchaling region (Group 1b), represented by recrystallized serpentine minerals (antigorite). The trace element compositions of these Group 1b serpentinites suggest that partial dehydration of serpentinites associated with the transformation from lizardite to antigorite in subduction zone is also likely to affect the geochemistry of serpentinites. Serpentinites from the Liangyazi region (Group 2) are composed of antigorite + dolomite + spinel + magnetite. The high Cr number (0.65-0.80) and low Ti concentrations of spinels in Group 2 serpentinites indicate a refractory mantle wedge origin. Fertile major element compositions

  4. Aeromagnetic study of the Hengshan-Wutai-Fuping region: Unraveling a crustal profile of the Paleoproterozoic Trans-North China Orogen

    Science.gov (United States)

    Zhang, Jian; Zhao, Guochun; Shen, Wenlue; Li, Sanzhong; Sun, Min

    2015-11-01

    An integrated crustal profile of the intervening Trans-North China Orogen (TNCO) is one of the key issues to understanding the tectonic evolution of the North China Craton. However, the existing geological studies focus only on the surface-mapping based petrological, geochemical and structural analysis, but lack subsurface geophysical evidence and thus make the crustal profile interpretations ambiguous. In contrast, the current geophysical data covers a very large-scale lithospheric mantle and fails to image the detailed structural pattern of the orogenic crust. To achieve this goal, we present high-resolution aeromagnetic data for the Hengshan-Wutai-Fuping region, the largest exposure of the central TNCO. The reduced-to-pole magnetic anomaly map firstly verifies the regional tectonic subdivision that the high-grade metamorphic terranes (i.e. Hengshan and Fuping Complexes) are consistent with high-magnetic responses and long-wavelength anomalies, intervened by a low-grade terrane (Wutai Complex) characterized by low-magnetic responses and short-wavelength anomalies. 3D Euler deconvolution reveals that the tendencies of the clustered solutions show large consistence with the major structural pattern of the region which is characterized by a fan-shaped doubly-vergent orogenic wedge. Upward continuation further shows that the northwest part of the orogen yields a thicker crust and is most likely located closer to the paleosubduction zone. The new aeromagnetic data, combined with structural, petrological and metamorphic data indicate that an eastward-dipping subduction zone was most possibly active before the collision of the Western and Eastern Blocks, leading to the formation of the TNCO and the final amalgamation of the North China Craton.

  5. The Heart of China revisited: II Early Paleozoic (ultra)high-pressure and (ultra)high-temperature metamorphic Qinling orogenic collage

    Science.gov (United States)

    Bader, Thomas; Franz, Leander; Ratschbacher, Lothar; de Capitani, Christian; Webb, A. Alexander G.; Yang, Zhao; Pfänder, Jörg A.; Hofmann, Mandy; Linnemann, Ulf

    2013-07-01

    Orogens with multiple (ultra)high-pressure ((U)HP) and (ultra)high-temperature ((U)HT) metamorphic events provide a complex but telling record of oceanic and continental interaction. The Early Paleozoic history of the "Heart of China," the Qinling orogenic collage, offers snapshots of at least three (U)HP and two (U)HT metamorphic events. The preservation of remnants of both oceanic and continental domains together with a ≥110 Myr record of magmatism allows the reconstruction of the processes that resulted in this disparate metamorphism. Herein, we first illuminate the pressure-temperature-time (P-T-t) evolution of the Early Paleozoic (U)HP and (U)HT events by refining the petrographic descriptions and P-T estimates, assess published, and employ new U/Th-Pb zircon, monazite, and titanite, and 40Ar-39Ar phengite geochronology to date the magmatic and metamorphic events. Then we explore how the metamorphic and magmatic events are related tectonically and how they elucidate the affinities among the various complexes in the Qinling orogenic collage. We argue that a Meso-Neoproterozoic crustal fragment—the Qinling complex—localized subduction-accretion events that involved subduction, oceanic-arc formation, and back-arc spreading along its northern margin, and mtantle-wedge exhumation and spreading-ridge subduction along its southern margin.

  6. A study of Guptkashi, Uttarakhand earthquake of 6 February 2017 (M w 5.3) in the Himalayan arc and implications for ground motion estimation

    Science.gov (United States)

    Srinagesh, Davuluri; Singh, Shri Krishna; Suresh, Gaddale; Srinivas, Dakuri; Pérez-Campos, Xyoli; Suresh, Gudapati

    2018-02-01

    The 2017 Guptkashi earthquake occurred in a segment of the Himalayan arc with high potential for a strong earthquake in the near future. In this context, a careful analysis of the earthquake is important as it may shed light on source and ground motion characteristics during future earthquakes. Using the earthquake recording on a single broadband strong-motion seismograph installed at the epicenter, we estimate the earthquake's location (30.546° N, 79.063° E), depth (H = 19 km), the seismic moment (M 0 = 1.12×1017 Nm, M w 5.3), the focal mechanism (φ = 280°, δ = 14°, λ = 84°), the source radius (a = 1.3 km), and the static stress drop (Δσ s 22 MPa). The event occurred just above the Main Himalayan Thrust. S-wave spectra of the earthquake at hard sites in the arc are well approximated (assuming ω -2 source model) by attenuation parameters Q(f) = 500f 0.9, κ = 0.04 s, and f max = infinite, and a stress drop of Δσ = 70 MPa. Observed and computed peak ground motions, using stochastic method along with parameters inferred from spectral analysis, agree well with each other. These attenuation parameters are also reasonable for the observed spectra and/or peak ground motion parameters in the arc at distances ≤ 200 km during five other earthquakes in the region (4.6 ≤ M w ≤ 6.9). The estimated stress drop of the six events ranges from 20 to 120 MPa. Our analysis suggests that attenuation parameters given above may be used for ground motion estimation at hard sites in the Himalayan arc via the stochastic method.

  7. The treatment of jaundice with medicinal plants in indigenous communities of the Sub-Himalayan region of Uttarakhand, India.

    Science.gov (United States)

    Sharma, Jyotsana; Gairola, Sumeet; Gaur, R D; Painuli, R M

    2012-08-30

    Inspite of tremendous advances made in allopathic medical practices, herbs still play an important role in the management of various liver diseases. A large number of plants and formulations have been claimed to have hepatoprotective activity. Jaundice is a symptom, indicative of the malfunctioning of the liver. This paper provides ethnomedicinal information on the plants used to treat jaundice by three important indigenous communities, i.e., nomadic Gujjars, Tharu and Bhoxa of Sub-Himalayan region, Uttarakhand, India. To record herbal preparations used by the studied indigenous communities in treatment of jaundice and discuss hepatoprotective properties of the recorded plants. The traditional knowledge of the studied indigenous communities on herbal preparations used for treating jaundice was collected through structured questionnaire and personal interviews. The interviews were conducted with 91 traditional healers (29 Bhoxa, 35 Tharu and 27 nomadic Gujjars) in Sub-Himalayan region of Uttarakhand, India. More than 250 research papers reporting ethnomedicinal information on the hepatoprotective plants used by various communities from different parts of India were extensively reviewed. A total of 40 medicinal plants belonging to 31 families and 38 genera were recorded to be used by the studied communities in 45 formulations as a remedy of jaundice. Bhoxa, nomadic Gujjars and Tharu communities used 15, 23 and 9 plants, respectively. To our knowledge eight plants reported in the present survey viz., Amaranthus spinosus L., Cissampelos pareira L., Ehretia laevis Roxb., Holarrhena pubescens Wall., Ocimum americanum L., Physalis divaricata D. Don, Solanum incanum L. and Trichosanthes cucumerina L. have not been reported earlier as remedy of jaundice in India. Literature review revealed that a total of 214 (belonging to 181 genus and 78 families), 19 (belonging to 18 genus and 12 families) and 14 (belonging to 14 genus and 11 families) plant species are used as internal

  8. Low fidelity of CORDEX and their driving experiments indicates future climatic uncertainty over Himalayan watersheds of Indus basin

    Science.gov (United States)

    Hasson, Shabeh ul; Böhner, Jürgen; Chishtie, Farrukh

    2018-03-01

    Assessment of future water availability from the Himalayan watersheds of Indus Basin (Jhelum, Kabul and upper Indus basin—UIB) is a growing concern for safeguarding the sustainable socioeconomic wellbeing downstream. This requires, before all, robust climate change information from the present-day state-of-the-art climate models. However, the robustness of climate change projections highly depends upon the fidelity of climate modeling experiments. Hence, this study assesses the fidelity of seven dynamically refined (0.44° ) experiments, performed under the framework of the coordinated regional climate downscaling experiment for South Asia (CX-SA), and additionally, their six coarse-resolution driving datasets participating in the coupled model intercomparison project phase 5 (CMIP5). We assess fidelity in terms of reproducibility of the observed climatology of temperature and precipitation, and the seasonality of the latter for the historical period (1971-2005). Based on the model fidelity results, we further assess the robustness or uncertainty of the far future climate (2061-2095), as projected under the extreme-end warming scenario of the representative concentration pathway (RCP) 8.5. Our results show that the CX-SA and their driving CMIP5 experiments consistently feature low fidelity in terms of the chosen skill metrics, suggesting substantial cold (6-10 ° C) and wet (up to 80%) biases and underestimation of observed precipitation seasonality. Surprisingly, the CX-SA are unable to outperform their driving datasets. Further, the biases of CX-SA and of their driving CMIP5 datasets are higher in magnitude than their projected changes under RCP8.5—and hence under less extreme RCPs—by the end of 21st century, indicating uncertain future climates for the Indus Basin watersheds. Higher inter-dataset disagreements of both CMIP5 and CX-SA for their simulated historical precipitation and for its projected changes reinforce uncertain future wet/dry conditions

  9. On the formation and evolution of the Pannonian basin: constraints derived from the orogenic collapse recorded at the junction between Carpathians and Dinarides

    Science.gov (United States)

    Matenco, L. C.; Radivojevic, D.

    2012-04-01

    Formation and evolution of back-arc basins is related to the evolution of subduction zones, resulting geometries being dependent on the interplay between the velocity of retreating slabs and boundary conditions that often limit rapid subduction systems. Classical models of evolution in the Alps-Carpathians-Dinaridic domain assume that the formation of the Pannonian back-arc basin is related to the rapid roll-back of an European slab and the invasion of Tisza-Dacia and ALCAPA upper plate blocks into the so-called Carpathians embayment starting at ~20Ma. The general mechanism assumes a gradual evolution, an initial mechanical phase of extensional detachments being recognized near the transition between the Alps and the Pannonian basin was subsequently followed by upper crustal normal faulting and a thermal phase during the Middle-late Miocene times that affected the central part of the Pannonian basin. A key area of the entire system often neglected by kinematic studies is the connection between South Carpathians and Dinarides. Here, regional seismic lines traversing the entire Serbian part of the Pannonian basin were calibrated with well data in order to derive an evolutionary model. The deformation is dominantly expressed by the formation of extensional (half-)grabens that are the brittle expression of large-scale extensional detachments. In contrast with previous interpretation restricting the syn-rift phase to the Middle Miocene, the geometry of normal faults and the associated syn-kinematic sedimentation allows the definition of a continuous Early to Late Miocene extensional evolution that was followed by the formation of isolated uplifted areas during the subsequent Pliocene - Quaternary inversion. The orientation of these (half-)grabens changes gradually from W-E to NW-SE and then to N-S, suggesting that the present-day strike of faults is the effect of a clockwise rotational mechanism of South Carpathians and Apuseni Mountains in respect to Dinarides. The S

  10. Performance of CMIP3 and CMIP5 GCMs to simulate observed rainfall characteristics over the Western Himalayan region

    Science.gov (United States)

    Meher, J. K.; Das, L.

    2017-12-01

    The Western Himalayan Region (WHR) was subject to a significant negative trend in the annual and monsoon rainfall during 1902-2005. Annual and seasonal rainfall change over WHR of India was estimated using 22 rain gauge station rainfall data from the India Meteorological Department. The performance of 13 global climate models (GCMs) from the coupled model intercomparison project phase 3 (CMIP3) and 42 GCMs from CMIP5 was evaluated through multiple analysis: the evaluation of the mean annual cycle, annual cycles of interannual variability, spatial patterns, trends and signal-to-noise ratio. In general, CMIP5 GCMs were more skillful in terms of simulating the annual cycle of interannual variability compared to CMIP3 GCMs. The CMIP3 GCMs failed to reproduce the observed trend whereas 50% of the CMIP5 GCMs reproduced the statistical distribution of short-term (30-years) trend-estimates than for the longer term (99-years). GCMs from both CMIP3 and CMIP5 were able to simulate the spatial distribution of observed rainfall in pre-monsoon and winter months. Based on performance, each model of CMIP3 and CMIP5 was given an overall rank, which puts the high resolution version of the MIROC3.2 model (MIROC3.2 hires) and MIROC5 at the top in CMIP3 and CMIP5 respectively. Robustness of the ranking was judged through a sensitivity analysis, which indicated that ranks were independent during the process of adding or removing any individual method. It also revealed that trend analysis was not a robust method of judging performances of the model as compared to other methods.

  11. Soil carbon stocks along an altitudinal gradient in different land-use categories in Lesser Himalayan foothills of Kashmir

    Science.gov (United States)

    Shaheen, H.; Saeed, Y.; Abbasi, M. K.; Khaliq, A.

    2017-04-01

    The carbon sequestration potential of soils plays an important role in mitigating the effect of climate change, because soils serve as sinks for atmospheric carbon. The present study was conducted to estimate the carbon stocks and their variation with altitudinal gradient in the Lesser Himalayan foothills of Kashmir. The carbon stocks were estimated in different land use categories, namely: closed canopy forests, open forests, disturbed forests, and agricultural lands within the altitudinal range from 900 to 2500 m. The soil carbon content was determined by the Walkley-Black titration method. The average soil carbon stock was found to be 2.59 kg m-2. The average soil carbon stocks in closed canopy forests, open forests, and disturbed forests were 3.39, 2.06, and 2.86 kg m-2, respectively. The average soil carbon stock in the agricultural soils was 2.03 kg m-2. The carbon stocks showed a significant decreasing trend with the altitudinal gradient with maximum values of 4.13 kg m-2 at 900-1200 m a.s.l. and minimum value of 1.55 kg m-2 at 2100-2400 m a.s.l. The agricultural soil showed the least carbon content values indicating negative impacts of soil plowing, overgrazing, and soil degradation. Lower carbon values at higher altitudes attest to the immature character of forest stands, as well as to degradation due to immense fuel wood extraction, timber extraction, and harsh climatic conditions. The study indicates that immediate attention is required for the conservation of rapidly declining carbon stocks in agricultural soils, as well as in the soils of higher altitudes.

  12. Haemato-biochemical and endocrine profiling of north western Himalayan Gaddi sheep during various physiological/reproductive phases

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    A. Sharma

    2015-08-01

    Full Text Available The study was aimed to provide baseline data regarding haemato-biochemical and endocrine profiling of Gaddi sheep found in north western Himalayan region of Himachal Pradesh, India. Each random sample was collected from 45 Gaddi sheep reared in government sheep breeding farm Tal, Hamirpur, India, during various reproductive phases viz. anestrus, breeding season and post partum period. Haematology revealed significantly higher (P<0.05 RBC as well as haematocrit values in pregnant animals (n=23 during breeding season than during other reproductive phases. The number of platelets were significantly lower (P<0.05 and MCH, MCHC values were statistically higher (P<0.05 during postpartum period than during other reproductive phases. Blood biochemistry revealed significantly higher (P<0.05 concentrations of plasma cholesterol (83.98±3.68 mg/dl, plasma calcium (71.06±1.52 mg/l, magnesium (18.21±0.53 mg/l, potassium (5.10±0.13 mEq/l and significantly lower (P<0.05 concentrations of plasma total protein (5.75±0.31 gm/dl, globulin (3.04±0.29 gm/dl and sodium (138.83±1.83 mEq/l during postpartum period in comparison to other reproductive phases. Endocrine profile revealed significantly higher (P<0.05 serum estrogen (60.97±1.24 pg/ml and T4 (6.0±0.27 μg/ml concentrations during postpartum phase. Similarly, significantly higher (P<0.05 serum progesterone (5.16±0.76 ng/ml as well as TSH (0.70±0.14 μg/ml concentration were recorded during pregnancy. From the study it can be concluded that physiological status significantly affects the blood metabolic and endocrine profile in Gaddi sheep.

  13. Malnutrition as a cause of mental retardation: A population-based study from Sub-Himalayan India

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    Sunil Kumar Raina

    2016-01-01

    Full Text Available Background: Mental retardation is one of the most common disabilities of childhood. The research on childhood malnutrition and its relationship with cognitive functioning suggests that malnutrition alone does not cause mental retardation. Objective: To identify the relation between malnutrition and cognition among children from a Sub-Himalayan state in North India. Materials and Methods: A two-phase cross-sectional study was conducted in the rural, urban, and slum area of district Kangra. A 30-cluster sampling technique was used to screen a population of children 1–10 years of age from five randomly selected panchayats (village government units of district Kangra. The screening was based on a modified version of the ten questions screen, adapted to the local population. In the first phase, a door-to-door survey was done to identify suspects of mental retardation. In the second phase, the children found positive in the first phase were called for clinical examination to confirm mental retardation. Anthropometric assessment of all study children was done by measuring weight and height. The nutritional assessment was done by categorizing them according to Waterlow classification for malnutrition. Results: Out of the total 5300 children, 1.7% were diagnosed as mentally retarded. No positive association was reported with different types of malnutrition and mental retardation. A weakly positive association existed between nutritional status and mental retardation (correlation coefficient-0.04. Children who were both wasted and stunted had the highest risk (odds ratio, 95% confidence interval - 5.57, 2.29–10.36 of mental retardation as compared to normal. Conclusion: Malnutrition may be one of the causes but certainly not the only cause of mental retardation. Other causes may be contributing more significantly toward it.

  14. Dissolved organic matter and inorganic ions in a central Himalayan glacier--insights into chemical composition and atmospheric sources.

    Science.gov (United States)

    Xu, Jianzhong; Zhang, Qi; Li, Xiangying; Ge, Xinlei; Xiao, Cunde; Ren, Jiawen; Qin, Dahe

    2013-06-18

    Melting of Himalayan glaciers can be accelerated by the deposition of airborne black carbon and mineral dust as it leads to significant reductions of the surface albedo of snow and ice. Whereas South Asia has been shown a primary source region to these particles, detailed sources of these aerosol pollutants remain poorly understood. In this study, the chemical compositions of snow pit samples collected from Jima Yangzong glacier in the central Himalayas were analyzed to obtain information of atmospheric aerosols deposited from summer 2009 to spring 2010. Especially, an Aerodyne high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was used for the first time to chemically characterize the dissolved organic and inorganic matter (DOM and DIM) in snow samples. The concentrations of these species varied seasonally, with high levels observed during the winter-spring period and low levels during the summer monsoon period. On average, the dissolved substances was dominated by organics (58%) with important contributions from inorganic species, NO3(-) (12.5%), Ca(2+) (9.1%), NH4(+) (8.7%), and SO(4)(2-) (8.1%). DOM was found more oxidized with an average (± 1σ) atomic oxygen-to-carbon ratio (nO/nC) of 0.64 (± 0.14) and organic mass-to-carbon ratio (OM/OC) of 2.01 (± 0.19) during the winter-spring periods compared to the summer season (nO/nC = 0.31 ± 0.09 and OM/OC = 1.58 ± 0.12). In addition, biomass burning particles were found significantly enhanced in snow during the winter-spring periods, consistent with HYSPLIT back trajectory analysis of air mass history, which indicates prevailing atmospheric transport from northwest India and Nepal.

  15. Diversity, molecular phylogeny, and bioactive potential of fungal endophytes associated with the Himalayan blue pine (Pinus wallichiana).

    Science.gov (United States)

    Qadri, Masroor; Rajput, Roopali; Abdin, Malik Z; Vishwakarma, Ram A; Riyaz-Ul-Hassan, Syed

    2014-05-01

    In this study, we investigated the diversity of fungal endophytes associated with Pinus wallichiana from the Western Himalayas, with emphasis on comparison of endophytic communities harbored by the stem and needle tissues of the host and their antimicrobial potential. A total number of 130 isolates, comprising of 38 different genera, were recovered from 210 fragments of the plant. Among the isolated fungi, only a single isolate, Tritirachium oryzae, belonged to the Phylum Basidiomycota whereas the rest belonged to Ascomycota. Dothideomycetes was the dominant class with the highest isolation frequency of 49.2 %. The most frequent colonizers of the host were Alternaria spp., Pestalotiopsis spp., Preussia spp., and Sclerostagonospora spp. The diversity and species richness were higher in needle tissues than in the stems. Antimicrobial activities were displayed by extracts from a total number of 22 endophytes against one or more pathogens. Endophytes designated as P1N13 (Coniothyrium carteri), P2N8 (Thielavia subthermophila), P4S6b (Truncatella betulae), P7N10 (Cochliobolus australiensis), and P8S4 (Tritirachium oryzae) were highly active against Candida albicans. Broad spectrum antimicrobial activities were obtained with the extracts of P8-S4 (Tritirachium oryzae) and P5-N26 (Coniochaeta gigantospora) that were potentially active against the Gram-positive and Gram-negative bacteria as well as the fungal pathogen, Candida albicans. The most prominent antagonistic activity against fungal pathogens was shown by P8-S4 (Tritirachium oryzae), P5-N31a (Truncatella spadicea), and P5-N20 (Fusarium larvarum). Our findings indicate that Pinus wallichiana harbors a rich endophytic fungal community with potential antimicrobial activities. Further studies are needed to understand the ecology and evolutionary context of the associations between the Himalayan pine and its endophytes.

  16. Genetic diversity of pinus roxburghii sarg. Collected from different himalayan regions of India assessed by random amplified polymorphic DNA analysis.

    Science.gov (United States)

    Sinha, Dwaipayan; Singh, Jyotsna; Tandon, P K; Kakkar, Poonam

    2013-09-01

    Present study was aimed at molecular genetic fingerprint profile of 15 genotypes of three populations of Pinus roxburghii Sarg. from Himalayan regions of India using random amplified polymorphic DNA (RAPD) based markers. Needles of Pinus roxburghii Sarg. were collected from Dharamshala, Himachal Pradesh (HP), Nainital, Uttarakhand (UK) and Darjeeling, West Bengal (WB) regions of India. The samples were subjected to DNA extraction and RAPD analysis using oligonucleotide purification cartridge (OPC) primers. Out of 15 primers tested, nine primers gave scorable bands. Altogether 48 bands were obtained, out of which 43 were found to be polymorphic. Number of amplified fragments with RAPD primers ranged from four to eight with the size of amplicon ranging from 500 to 7,000bp. Investigation of natural diversity at intraspecies level was performed with 15 genotypes. Forty-eight amplification products were scored by RAPD and showed 89.58% polymorphism with a mean intrapopulation genetic diversity (Hpop) of 0.2754. A significant inter- and intrapopulation diversity was observed, with the percentage of polymorphic loci (Pp) ranging from 50.09 to 70.83%, Shannon's information index (I) from 0.3262 to 0.4689 and Nei's gene diversity (h) from 0.2032 to 0.3335 with mean Nei's gene diversity 0.377 and the overall estimate of gene flow being (Nm) 1.3555. Unweighted pair-group method with arithmetic average (UPGMA) analysis based Dendrogram showed single cluster. The variation amongst the samples of the three ecological regions can be attributed to varied climatic conditions and may help in conservation/future cultivation of these species.

  17. Characterizing anthropogenic impacts on two mid-altitude Himalayan lakes in the Western Himalaya: A look at shifts in water chemistry and phytoplankton communities

    Science.gov (United States)

    Marcus, T. S.; Tiwari, S.; Bhatt, J. P.; Pandit, M. K.; Varner, R. K.

    2017-12-01

    The Himalayan region is globally regarded for its natural mountain ecosystems but increased agricultural expansion and urbanization have resulted in greater nutrient loading in Himalayan water bodies causing widespread fish kills and shrinking lakes. Despite concerns for environmental degradation, lack of empirical investigations and quantitative data are major constraints in understanding these events. To determine the impact of human development on Himalayan lakes, we investigated Rewalsar, a spring-fed lake and Kareri a glacial-fed lake in the state of Himachal Pradesh. Rewalsar is surrounded by a rapidly growing town and agricultural fields while Kareri Lake is situated in a relatively remote area. Measurements were made in the spring periods of 2013 and 2016. Water samples were collected 1m below the lake surface and analyzed for major ions, nitrates, phosphates, DO, pH, temperature, turbidity, and TDS. Alagal samples were collected from each lake and species counted and identified using standard taxonomic literature. Statistical analysis was performed using PC-ORD. Results showed a significant change in water chemistry and phytoplankton communities with Rewalsar Lake showing an increase in pollutant tolerant algae over the sample period. Principle component analysis showed that the 2016 data from Kareri Lake had phytoplankton communities and chemical data resembling the urban lake of Rewalsar. Kareri Lake had the highest DO (10 mg/ml) while Rewalsar showed the lowest DO at 3 mg/ml in 2016, a decrease from 8 mg/ml in 2013. With a total oxygen demand (TOD) of 6.5 mg/ml in Rewalsar, the decreasing DO value is likely the cause of the increasing annual fish kills as reported by local governments. TDS measurements were highest in Rewalsar Lake compared to the TDS levels of Kareri, indicating a higher amount of surface runoff from the surrounding area in Rewalsar. Nitrate and phosphate levels also increased over this time period. Our multi-year investigation also

  18. Seasonal characteristic features of local circulation at a Himalayan valley near Mount Everest

    Science.gov (United States)

    Zhang, Lang; Ma, Yaoming

    2016-04-01

    For obtaining seasonal variation information of local circulation features and deeper understanding of wind system mechanism of the Rongbuk valley on the northern slope of Himalayas near by Mount Everest, Global Position System (GPS) radiosonde system was launched on June, 4-11, August, 20-26 and November, 22-28 in year 2014, which are considered to be the pre-monsoon, monsoon and non-monsoon periods respectively. Additionally, the wind profiler (WP) and radio acoustic sounding system (RASS) measurements were operated to observe the vertical structures of local wind system from May to August, 2014. Meanwhile, the surface wind data obtained from three different sites located at 4276m,5190m and 5830m above sea level in the Rongbuk valley are used to discuss the possible different glacier wind effect in different parts of Rongbuk Valley. Substantial findings include the existence of weak nighttime upslope flows during monsoon caused by the air temperature difference in the valley and the downward momentum transport from westerlies to surface wind during winter. During pre-monsoon, there are two circulations dominate the entire valley, e.g. mountain-valley wind system and glacier wind system, before about 16:00 Beijing Standard Time (BST).

  19. Post-20 Ma Motion of the Adriatic Plate: New Constraints From Surrounding Orogens and Implications for Crust-Mantle Decoupling

    Science.gov (United States)

    Le Breton, Eline; Handy, Mark R.; Molli, Giancarlo; Ustaszewski, Kamil

    2017-12-01

    A new kinematic reconstruction that incorporates estimates of post-20 Ma shortening and extension in the Apennines, Alps, Dinarides, and Sicily Channel Rift Zone (SCRZ) reveals that the Adriatic microplate (Adria) rotated counterclockwise as it subducted beneath the European Plate to the west and to the east, while indenting the Alps to the north. Minimum and maximum amounts of rotation are derived by using, respectively, estimates of crustal extension along the SCRZ (minimum of 30 km) combined with crustal shortening in the Eastern Alps (minimum of 115 km) and a maximum amount (140 km) of convergence between Adria and Moesia across the southern Dinarides and Carpatho-Balkan orogens. When combined with Neogene convergence in the Western Alps, the best fit of available structural data constrains Adria to have moved 113 km to the NW (azimuth 325°) while rotating 5 ± 3° counterclockwise relative to Europe since 20 Ma. Amounts of plate convergence predicted by our new model exceed Neogene shortening estimates of several tens of kilometers in both the Apennines and Dinarides. We attribute this difference to crust-mantle decoupling (delamination) during rollback in the Apennines and to distributed deformation related to the northward motion of the Dacia Unit between the southern Dinarides and Europe (Moesia). Neogene motion of Adria resulted from a combination of Africa pushing from the south, the Adriatic-Hellenides slab pulling to the northeast, and crustal wedging in the Western Alps, which acted as a pivot and stopped farther northwestward motion of Adria relative to Europe.

  20. Mesoproterozoic juvenile crust in microcontinents of the Central Asian Orogenic Belt: evidence from oxygen and hafnium isotopes in zircon.

    Science.gov (United States)

    He, Zhen-Yu; Klemd, Reiner; Yan, Li-Li; Lu, Tian-Yu; Zhang, Ze-Ming

    2018-03-22

    We report in situ O and Hf isotope data of zircon grains from coeval Mesoproterozoic (ca. 1.4 Ga) igneous metamafic (amphibolite) and granitic rocks of the Chinese Central Tianshan microcontinent (CTM) in the southern Central Asian Orogenic Belt (CAOB). Zircon grains from amphibolite have mantle-like δ 18 O VSMOW values of 4.7-5.6‰ and juvenile Hf isotopic compositions (ε Hf (t) = 8.4-15.3; T DMC  = 1.57-1.22 Ga), whereas those from granitic rocks have δ 18 O VSMOW values of 5.6-7.0‰ and evolved Hf isotopic compositions (ε Hf (t) = -1.0-8.2; T DMC  = 2.09-1.62 Ga). Zircon O-Hf isotopic compositions of the metamafic and granitic rocks provide evidence for Mesoproterozoic (ca. 1.4 Ga) crustal growth and a substantial Palaeoproterozoic supracrustal component in the CTM. These findings and previous studies, reporting ca. 1.4 Ga magmatic rocks from other microcontinents of the CAOB, suggest that a large belt of Mesoproterozoic (ca. 1.4 Ga) juvenile continental crust formed in a continental terrane, fragments of which now occur over a distance of more than a thousand kilometres in the southern CAOB.

  1. Distribution, microfabric, and geochemical characteristics of siliceous rocks in central orogenic belt, China: implications for a hydrothermal sedimentation model.

    Science.gov (United States)

    Li, Hongzhong; Zhai, Mingguo; Zhang, Lianchang; Gao, Le; Yang, Zhijun; Zhou, Yongzhang; He, Junguo; Liang, Jin; Zhou, Liuyu; Voudouris, Panagiotis Ch

    2014-01-01

    Marine siliceous rocks are widely distributed in the central orogenic belt (COB) of China and have a close connection to the geological evolution and metallogenesis. They display periodic distributions from Mesoproterozoic to Jurassic with positive peaks in the Mesoproterozoic, Cambrian--Ordovician, and Carboniferous--Permian and their deposition is enhanced by the tensional geological settings. The compressional regimes during the Jinning, Caledonian, Hercynian, Indosinian, and Yanshanian orogenies resulted in sudden descent in their distribution. The siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic quartz, syn-depositional metal sulphides, and scattered carbonate minerals. Their SiO2 content (71.08-95.30%), Ba (42.45-503.0 ppm), and ΣREE (3.28-19.75 ppm) suggest a hydrothermal sedimentation origin. As evidenced by the Al/(Al + Fe + Mn), Sc/Th, (La/Yb) N, and (La/Ce) N ratios and δCe values, the studied siliceous rocks were deposited in a marginal sea basin of a limited ocean. We suggest that the Bafangshan-Erlihe area experienced high- and low-temperature stages of hydrothermal activities. The hydrothermal sediments of the former stage include metal sulphides and silica, while the latter was mainly composed of silica. Despite the hydrothermal sedimentation of the siliceous rocks, minor terrigenous input, magmatism, and biological activity partly contributed to geochemical features deviating from the typical hydrothermal characteristics.

  2. Distribution, Microfabric, and Geochemical Characteristics of Siliceous Rocks in Central Orogenic Belt, China: Implications for a Hydrothermal Sedimentation Model

    Directory of Open Access Journals (Sweden)

    Hongzhong Li

    2014-01-01

    Full Text Available Marine siliceous rocks are widely distributed in the central orogenic belt (COB of China and have a close connection to the geological evolution and metallogenesis. They display periodic distributions from Mesoproterozoic to Jurassic with positive peaks in the Mesoproterozoic, Cambrian—Ordovician, and Carboniferous—Permian and their deposition is enhanced by the tensional geological settings. The compressional regimes during the Jinning, Caledonian, Hercynian, Indosinian, and Yanshanian orogenies resulted in sudden descent in their distribution. The siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic quartz, syn-depositional metal sulphides, and scattered carbonate minerals. Their SiO2 content (71.08–95.30%, Ba (42.45–503.0 ppm, and ΣREE (3.28–19.75 ppm suggest a hydrothermal sedimentation origin. As evidenced by the Al/(Al + Fe + Mn, Sc/Th, (La/YbN, and (La/CeN ratios and δCe values, the studied siliceous rocks were deposited in a marginal sea basin of a limited ocean. We suggest that the Bafangshan-Erlihe area experienced high- and low-temperature stages of hydrothermal activities. The hydrothermal sediments of the former stage include metal sulphides and silica, while the latter was mainly composed of silica. Despite the hydrothermal sedimentation of the siliceous rocks, minor terrigenous input, magmatism, and biological activity partly contributed to geochemical features deviating from the typical hydrothermal characteristics.

  3. Detrital zircon provenance analysis in the Zagros Orogen, SW Iran: implications for the amalgamation history of the Neo-Tethys

    Science.gov (United States)

    Zhang, Zhiyong; Xiao, Wenjiao; Majidifard, Mahmoud Reza; Zhu, Rixiang; Wan, Bo; Ao, Songjian; Chen, Ling; Rezaeian, Mahnaz; Esmaeili, Rasoul

    2017-06-01

    The Zagros Orogen developed as a result of Arabia-Eurasia collision. New in situ detrital zircon U-Pb and Hf isotopic analyses from a Cenozoic sedimentary sequence in SW Iran are used to unravel the amalgamation history of Neo-Tethys. Data indicate that: (1) Paleocene and Eocene strata (58 and 45 Ma, respectively) were sourced from obducted ophiolite and Triassic volcanics, (2) Lower Miocene ( 18 Ma) strata indicate mixed provenance from obducted ophiolite and Iranian magmatic rocks, (3) Mid to Upper Miocene sediments ( 14 to 11.2 Ma) were mainly sourced from Sanandaj-Sirjan zone granitoids to the north, and (4) Lower Pliocene ( 5 Ma) sediments mainly show Arabian age characteristics, with a minor Eurasian affinity component. Two hypotheses are outlined to highlight the key events: Hypothesis A, previously published by several workers, suggests that the sequence studied lay on the Arabia passive margin and that initial collision occurred prior to 18 Ma; Hypothesis B, modified from the Makran model, which is here preferred, suggests that Paleogene to Upper Miocene sediments were sourced from the northern Neo-Tethyan accretionary complex or Eurasia, and carry no input from Arabia, whereas the Lower Pliocene sample shows a mixed provenance from both Arabia and Eurasia, suggesting that collision occurred between 11.2 and 5 Ma.

  4. Melting of subducted continental crust: Geochemical evidence from Mesozoic granitoids in the Dabie-Sulu orogenic belt, east-central China

    Science.gov (United States)

    Zhao, Zi-Fu; Liu, Zhi-Bin; Chen, Qi

    2017-09-01

    Syn-collisional and postcollisional granitoids are common in collisional orogens, and they were primarily produced by partial melting of subducted continental crust. This is exemplified by Mesozoic granitoids from the Dabie-Sulu orogenic belt in east-central China. These granitoids were emplaced in small volumes in the Late Triassic (200-206 Ma) and the Late Jurassic (146-167 Ma) but massively in the Early Cretaceous (111-143 Ma). Nevertheless, all of them exhibit arc-like trace element distribution patterns and are enriched in Sr-Nd-Hf isotope compositions, indicating their origination from the ancient continental crust. They commonly contain relict zircons with Neoproterozoic and Triassic U-Pb ages, respectively, consistent with the protolith and metamorphic ages for ultrahigh-pressure (UHP) metaigneous rocks in the Dabie-Sulu orogenic belt. Some granitoids show low zircon δ18O values, and SIMS in-situ O isotope analysis reveals that the relict zircons with Neoproterozoic and Triassic U-Pb ages also commonly exhibit low δ18O values. Neoproterozoic U-Pb ages and low δ18O values are the two diagnostic features that distinguish the subducted South China Block from the obducted North China Block. Thus, the magma source of these Mesozoic granitoids has a genetic link to the subducted continental crust of the South China Block. On the other hand, these granitoids contain relict zircons with Paleoproterozoic and Archean U-Pb ages, which are present in both the South and North China Blocks. Taken together, the Mesozoic granitoids in the Dabie-Sulu orogenic belt and its hanging wall have their magma sources that are predominated by the continental crust of the South China Block with minor contributions from the continental crust of the North China Block. The Triassic continental collision between the South and North China Blocks brought the continental crust into the thickened orogen, where they underwent the three episodes of partial melting in the Late Triassic, Late

  5. Exploration of the diversity and associated health benefits of traditional pickles from the Himalayan and adjacent hilly regions of Indian subcontinent.

    Science.gov (United States)

    Chakraborty, Rakhi; Roy, Swarnendu

    2018-05-01

    The Himalayas have provided shelter to the various communities for thousands of years and have remained the cradle for the origin of diverse cultures and traditions. The Himalayan belt is rich in biodiversity and have ushered mankind with numerous gifts for survival and existence. The art of pickling is believed to have developed independently among the different communities of this region. In this region, the main meal is supplemented with pickles or achar that not only adds flavour, but also enhances the value of the meal and often comes with inherent health benefits. The prime objective of this article was to enlist the diverse pickles that are being prepared and consumed by the different tribes and communities, and at the same time analyse the science behind pickle preparation and health benefits and concerns associated with pickles. We have enlisted about hundred monotypic pickles, that are prepared from single fruit or vegetable; but sometimes fungi such as Agaricus and ferns like Diplazium and Pteridium have also been used. Also, fish and meat pickles are common mostly in the Eastern Himalayan region. Traditional pickles constitute the medicinal values of the ingredients and other beneficial properties conferred by the associated microorganisms.

  6. Accessing the capability of TRMM 3B42 V7 to simulate streamflow during extreme rain events: Case study for a Himalayan River Basin

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    Kumar, Brijesh; Lakshmi, Venkat

    2018-03-01

    The paper examines the quality of Tropical Rainfall Monitoring Mission (TRMM) 3B42 V7 precipitation product to simulate the streamflow using Soil Water Assessment Tool (SWAT) model for various rainfall intensities over the Himalayan region. The SWAT model has been set up for Gandak River Basin with 41 sub-basins and 420 HRUs. Five stream gauge locations are used to simulate the streamflow for a time span of 10 years (2000-2010). Daily streamflow for the simulation period is collected from Central Water Commission (CWC), India and Department of Hydrology and Meteorology (DHM), Nepal. The simulation results are found good in terms of Nash-Sutcliffe efficiency (NSE) {>}0.65, coefficient of determination (R2) {>}0.67 and Percentage Bias (PBIAS){}124.4 mm/d). The PBIAS and RSR show that TRMM simulated streamflow is suitable for moderate to heavy rainfall intensities. However, it does not perform well for light- and extremely-heavy rainfall intensities. The finding of the present work is useful for the problems related to water resources management, irrigation planning and hazard analysis over the Himalayan regions.

  7. Assessment of the performance of CORDEX-SA experiments in simulating seasonal mean temperature over the Himalayan region for the present climate: Part I

    Science.gov (United States)

    Nengker, T.; Choudhary, A.; Dimri, A. P.

    2018-04-01

    The ability of an ensemble of five regional climate models (hereafter RCMs) under Coordinated Regional Climate Downscaling Experiments-South Asia (hereafter, CORDEX-SA) in simulating the key features of present day near surface mean air temperature (Tmean) climatology (1970-2005) over the Himalayan region is studied. The purpose of this paper is to understand the consistency in the performance of models across the ensemble, space and seasons. For this a number of statistical measures like trend, correlation, variance, probability distribution function etc. are applied to evaluate the performance of models against observation and simultaneously the underlying uncertainties between them for four different seasons. The most evident finding from the study is the presence of a large cold bias (-6 to -8 °C) which is systematically seen across all the models and across space and time over the Himalayan region. However, these RCMs with its fine resolution perform extremely well in capturing the spatial distribution of the temperature features as indicated by a consistently high spatial correlation (greater than 0.9) with the observation in all seasons. In spite of underestimation in simulated temperature and general intensification of cold bias with increasing elevation the models show a greater rate of warming than the observation throughout entire altitudinal stretch of study region. During winter, the simulated rate of warming gets even higher at high altitudes. Moreover, a seasonal response of model performance and its spatial variability to elevation is found.

  8. The Western Carpathians fold and thrust belt and its relationships with the inner zone of the orogen: constraints from sequentially restored, balanced cross-sections integrated with low-temperature thermochronometry

    Science.gov (United States)

    Mazzoli, Stefano; Castelluccio, Ada; Andreucci, Benedetta; Jankowski, Leszek; Ketcham, Richard A.; Szaniawski, Rafal; Zattin, Massimiliano

    2017-04-01

    The Western Carpathians are the northernmost, W-E-trending branch of a more than 1500 km long, curved orogen. Traditionally, the Western Carpathians have been divided into two distinct parts, namely the Inner Carpathians (including basement nappes) and the Outer Carpathians fold and thrust belt. These two major domains are separated by the so-called 'Pieniny Klippen Belt', a narrow zone of intensely deformed and sheared Mesozoic to Palaeogene rocks. In this contribution, a new interpretation for the tectonic evolution of the Western Carpathians is provided based on: (i) the analysis of the stratigraphy of the Mesozoic-Tertiary successions across the different orogenic domains; (ii) the construction of a series of balanced and restored cross-sections, validated by 2D forward modeling; and (iii) the integration of a large thermochronometric dataset (apatite fission tracks and apatite and zircon (U-Th-(Sm))/He ages). The latter work included thermo-kinematic modeling using FetKin, a finite element solver that takes as input a series of balanced cross-sections. The software solves the heat flow equations in 2D together with the predicted thermochronometric ages, which can be compared with the measured data. Moreover, the spatial distribution of burial depths, cooling ages and the rate of exhumation were correlated with heat flow, topographic relief, crustal and lithospheric thickness. This process allowed us to obtain the cooling history along each section and test the response of low-temperature thermochronometers to the changes in the thrust belt geometry produced by fault activity and topography evolution. Our sequentially restored, balanced cross-sections, showing a mix of thin-skinned thrusting and thick-skinned tectonic inversion involving the reactivation of pre-existing basement normal faults, effectively unravel the tectonic evolution of the thrust belt-foreland basin system. Our analysis provides a robust correlation of the stratigraphy from the Outer to the

  9. Assessment of the performance of CORDEX-South Asia experiments for monsoonal precipitation over the Himalayan region during present climate: part I

    Science.gov (United States)

    Ghimire, S.; Choudhary, A.; Dimri, A. P.

    2018-04-01

    Analysis of regional climate simulations to evaluate the ability of 11 Coordinated Regional Climate Downscaling Experiment in South Asia experiments (CORDEX-South Asia) along with their ensemble to produce precipitation from June to September (JJAS) over the Himalayan region have been carried out. These suite of 11 combinations come from 6 regional climate models (RCMs) driven with 10 initial and boundary conditions from different global climate models and are collectively referred here as 11 CORDEX South Asia experiments. All the RCMs use a similar domain and are having similar spatial resolution of 0.44° ( 50 km). The set of experiments are considered to study precipitation sensitivity associated with the Indian summer monsoon (ISM) over the study region. This effort is made as ISM plays a vital role in summertime precipitation over the Himalayan region which acts as driver for the sustenance of habitat, population, crop, glacier, hydrology etc. In addition, so far the summer monsoon precipitation climatology over the Himalayan region has not been studied with the help of CORDEX data. Thus this study is initiated to evaluate the ability of the experiments and their ensemble in reproducing the characteristics of summer monsoon precipitation over Himalayan region, for the present climate (1970-2005). The precipitation climatology, annual precipitation cycles and interannual variabilities from each simulation have been assessed against the gridded observational dataset: Asian Precipitation-Highly Resolved Observational Data Integration Towards the Evaluation of Water Resources for the given time period. Further, after the selection of the better performing experiment the frequency distribution of precipitation was also studied. In this study, an approach has also been made to study the degree of agreement among individual experiments as a way to quantify the uncertainty among them. The experiments though show a wide variation among themselves and individually over

  10. Paleozoic magmatism and porphyry Cu-mineralization in an evolving tectonic setting in the North Qilian Orogenic Belt, NW China

    Science.gov (United States)

    Qiu, Kun-Feng; Deng, Jun; Taylor, Ryan D.; Song, Kai-Rui; Song, Yao-Hui; Li, Quan-Zhong; Goldfarb, Richard J.

    2016-01-01

    The NWW-striking North Qilian Orogenic Belt records the Paleozoic accretion–collision processes in NW China, and hosts Paleozoic Cu–Pb–Zn mineralization that was temporally and spatially related to the closure of the Paleo Qilian-Qinling Ocean. The Wangdian Cu deposit is located in the eastern part of the North Qilian Orogenic Belt, NW China. Copper mineralization is spatially associated with an altered early Paleozoic porphyritic granodiorite, which intruded tonalites and volcaniclastic rocks. Alteration zones surrounding the mineralization progress outward from a potassic to a feldspar-destructive phyllic assemblage. Mineralization consists mainly of quartz-sulfide stockworks and disseminated sulfides, with ore minerals