Sample records for bottom lithospheric study

  1. A Top to Bottom Lithospheric Study of Africa and Arabia

    Pasyanos, M


    We study the lithospheric structure of Africa, Arabia and adjacent oceanic regions with fundamental-mode surface waves over a wide period range. Including short period group velocities allows us to examine shallower features than previous studies of the whole continent. In the process, we have developed a crustal thickness map of Africa. Main features include crustal thickness increases under the West African, Congo, and Kalahari cratons. We find crustal thinning under Mesozoic and Cenozoic rifts, including the Benue Trough, Red Sea, and East, Central, and West African rift systems. Crustal shear wave velocities are generally faster in oceanic regions and cratons, and slower in more recent crust and in active and formerly active orogenic regions. Deeper structure, related to the thickness of cratons and modern rifting, is generally consistent with previous work. Under cratons we find thick lithosphere and fast upper mantle velocities, while under rifts we find thinned lithosphere and slower upper mantle velocities. There are no consistent effects in areas classified as hotspots, indicating that there seem to be numerous origins for these features. Finally, it appears that the African Superswell has had a significantly different impact in the north and the south, indicating specifics of the feature (temperature, time of influence, etc.) to be dissimilar between the two regions. Factoring in other information, it is likely that the southern portion has been active in the past, but that shallow activity is currently limited to the northern portion of the superswell.

  2. Bottom to top lithosphere structure and evolution of western Eger Rift (Central Europe)

    Babuška, Vladislav; Fiala, Jiří; Plomerová, Jaroslava


    Roč. 99, č. 4 (2010), s. 891-907. ISSN 1437-3254 R&D Projects: GA ČR GA205/07/1088; GA AV ČR IAA300120709 Institutional research plan: CEZ:AV0Z30120515; CEZ:AV0Z30130516 Keywords : western Bohemian Massif * Eger (Ohře) Rift * lithosphere structure and development * mantle seismic anisotropy Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 1.980, year: 2010

  3. Pipeline bottoming cycle study. Final report


    The technical and economic feasibility of applying bottoming cycles to the prime movers that drive the compressors of natural gas pipelines was studied. These bottoming cycles convert some of the waste heat from the exhaust gas of the prime movers into shaft power and conserve gas. Three typical compressor station sites were selected, each on a different pipeline. Although the prime movers were different, they were similar enough in exhaust gas flow rate and temperature that a single bottoming cycle system could be designed, with some modifications, for all three sites. Preliminary design included selection of the bottoming cycle working fluid, optimization of the cycle, and design of the components, such as turbine, vapor generator and condensers. Installation drawings were made and hardware and installation costs were estimated. The results of the economic assessment of retrofitting bottoming cycle systems on the three selected sites indicated that profitability was strongly dependent upon the site-specific installation costs, how the energy was used and the yearly utilization of the apparatus. The study indicated that the bottoming cycles are a competitive investment alternative for certain applications for the pipeline industry. Bottoming cycles are technically feasible. It was concluded that proper design and operating practices would reduce the environmental and safety hazards to acceptable levels. The amount of gas that could be saved through the year 2000 by the adoption of bottoming cycles for two different supply projections was estimated as from 0.296 trillion ft/sup 3/ for a low supply projection to 0.734 trillion ft/sup 3/ for a high supply projection. The potential market for bottoming cycle equipment for the two supply projections varied from 170 to 500 units of varying size. Finally, a demonstration program plan was developed.

  4. Electromagnetic induction studies. [of earth lithosphere and asthenosphere

    Hermance, J. F.


    Recent developments in electromagnetic induction studies of the lithosphere and the asthenosphere are reviewed. Attention is given to geoelectrical studies of active tectonic areas in terms of the major zones of crustal extension, the basin and range province along western regions of North America, and the Rio Grande rift. Studies have also been performed of tectonic activity around Iceland, the Salton Trough and Cerro Prieto, and the subduction zones of the Cascade Mountains volcanic belt, where magnetotelluric and geomagnetic variation studies have been done. Geomagnetic variations experiments have been reported in the Central Appalachians, and submarine electromagnetic studies along the Juan de Fuca ridge. Controlled source electromagnetic and dc resistivity investigations have been carried out in Nevada, Hawaii, and in the Adirondacks Mountains. Laboratory examinations on the conductivity of representative materials over a broad range of temperature, pressure, and chemistry are described.

  5. A lithospheric 3D temperature study from the South Atlantic

    Hirsch, K. K.; Scheck-Wenderoth, M.; Maystrenko, Y.; Sippel, J.


    The East African continental margin is a passive volcanic margin that experienced a long post-rifting history after break up in Early Cretaceous times. The break up resulted in the formation of a number of basins along the margin. The by far largest depocentre in the South Atlantic, the Orange Basin, was the location of previously performed studies. These studies of the Orange Basin have been performed to investigate the crustal structure and the temperature evolution of the basin. In this way, they gave way to new insights and to a number of questions. With 3D gravity modelling we found the crust to include high density bodies. Furthermore, a rifting model was developed which explained both the geometry and the thermal constraints of the basin. Now, this study has been extended spatially to cover a larger area and into depth to include the deep lithosphere. The main goal is to combine information on the geometry and properties of the sedimentary part of the system with data on the geometry and physical properties of the deep crust. It was also aimed to integrate both the continental and the oceanic parts of the margin into a consistent 3D structural model on a lithospheric scale. A 3D temperature model was evaluated for the passive continental margin of the South Atlantic including the lithospheric structure of the margin. We evaluate a case study for different scenarios to estimate the influence of sediments and crustal structures on the thermal field. The calculated conductive field is constrained by temperature measurements and 3D gravity modelling. At the Norwegian continental margin it has been found that a differentiation of the physical properties of the lower crust and the mantle is needed between the oceanic and continental domains to explain the observations. We aim to compare the younger setting of the Norwegian continental margin with the old passive margin in the South Atlantic. In particular, the South Atlantic is interesting since the southern half

  6. Experimental study of lithosphere-troposphere-ionosphere coupling

    Korepanov, Valery; Fedorov, Oleh; Lizunov, Georgy

    The ionosphere is the closest to the Earth area of near-Earth space and because of this the powerful natural and man-made processes, such as hurricanes, earthquakes, tsunami, big explosions and starts of heavy rockets to name a few, have to create corresponding disturbances there. Numerous experimental observations evidence the existence of such "terragenic" variations of ionospheric parameters, created by the sources below the ionosphere, in the troposphere and even in the lithosphere. Probably the most important question here is whether it is possible to detect enough reliably the ionospheric disturbances, related to the earthquake preparation state, at the background of the much stronger influences "from above" - of solar and galactic sources. So, the seismo-ionospheric coupling is one of the hottest topics of modern scientific research. The importance to shed more light to this process is connected with the study of possible earthquakes precursors in the ionosphere, monitoring of which could be a further step to the scientifically substantiated solution of the problem of earthquakes warning. The processing results of the data collected at Ukrainian Antarctic Station "Academician Vernadsky" are discussed. Basing on these data the theoretical study was performed and the energy transmission mechanism in the lithosphere-atmosphere-ionosphere system is analyzed. The atmospheric gravity waves are proposed as the most probable energy carriers for troposphere-ionosphere coupling. Basing on this study, as well as on the experience of preparation of several dedicated satellite mission (e. g., WARNING, INTERBALL-PROGNOZ) a new idea of spatial experiment IONOSAT is proposed to study in details the mechanism of seismo-ionospheric coupling and its realization peculiarities are discussed. This study was supported by NSAU contract No 1-02/03.

  7. Hydrocarbons in the Bay of Bengal and Central Indian Basin bottom sediments: Indicators of geochemical processes in the lithosphere

    Chernova, T.G.; Paropkari, A.L.; Pikovskii, Yu.I.; Alekseeva, T.A.

    liquid phase. Three zones were visualized by use of . ultraviolet light: 1 the zone represented by paraffin–naphthene hydrocarbons absence of lumi- . . nescence , 2 the zone consisting of aromatic hydro- .. carbons presence of luminescence , and 3... in a 25 m Apiezon L capil- lary column with temperature programming from 1258 to 3008Cat38C min y1 and hydrogen as a carrier gas. PAH were studied using Shpol’skii low-tempera- ture luminescence spectroscopy method. The n- hexane PAH solutions...

  8. Lithospheric processes

    Baldridge, W. [and others


    The authors used geophysical, geochemical, and numerical modeling to study selected problems related to Earth's lithosphere. We interpreted seismic waves to better characterize the thickness and properties of the crust and lithosphere. In the southwestern US and Tien Shari, crust of high elevation is dynamically supported above buoyant mantle. In California, mineral fabric in the mantle correlate with regional strain history. Although plumes of buoyant mantle may explain surface deformation and magmatism, our geochemical work does not support this mechanism for Iberia. Generation and ascent of magmas remains puzzling. Our work in Hawaii constrains the residence of magma beneath Hualalai to be a few hundred to about 1000 years. In the crust, heat drives fluid and mass transport. Numerical modeling yielded robust and accurate predictions of these processes. This work is important fundamental science, and applies to mitigation of volcanic and earthquake hazards, Test Ban Treaties, nuclear waste storage, environmental remediation, and hydrothermal energy.

  9. Lithospheric processes

    The authors used geophysical, geochemical, and numerical modeling to study selected problems related to Earth's lithosphere. We interpreted seismic waves to better characterize the thickness and properties of the crust and lithosphere. In the southwestern US and Tien Shari, crust of high elevation is dynamically supported above buoyant mantle. In California, mineral fabric in the mantle correlate with regional strain history. Although plumes of buoyant mantle may explain surface deformation and magmatism, our geochemical work does not support this mechanism for Iberia. Generation and ascent of magmas remains puzzling. Our work in Hawaii constrains the residence of magma beneath Hualalai to be a few hundred to about 1000 years. In the crust, heat drives fluid and mass transport. Numerical modeling yielded robust and accurate predictions of these processes. This work is important fundamental science, and applies to mitigation of volcanic and earthquake hazards, Test Ban Treaties, nuclear waste storage, environmental remediation, and hydrothermal energy

  10. Robust high resolution models of the continental lithosphere: Methodology and application to Asia (Utrecht Studies in Earth Sciences 036)

    Stolk, W.


    Asia is a key natural laboratory for the study of active intra-continental deformation in far-field response to the ongoing collision ofIndiaandEurasia. The resulting tectonic processes strongly depend on the thermo-mechanical structure of the lithosphere. This lithosphere can be separated into crus

  11. Understanding the lithosphere in complex tectonic scenarios by integrating geophysical data: The Pyrenees case study

    Campanyà, Joan; Fullea, Javier; Ledo, Juanjo; Queralt, Pilar; Marcuello, Alex; Liesa, Montserrat; Muñoz, Josep Anton


    Tectonic processes dominate the development of the outermost layer of the Earth over a timescale of millions of years. The locations where these processes take place provide a great opportunity for Earth scientists to study and understand the dynamics and properties of the lithosphere. The Pyrenees are a particular case of continental collision formed as a result of the collision between the Iberian and European plates, which caused the subduction of the Iberian lower crust below the European crust. Large amounts of geophysical data have been acquired in the area providing spectacular images of lithospheric subduction beneath the Western and Central Pyrenees, confirming the occurrence of this generally well-understood process. The Eastern Pyrenees, however, are a most puzzling part of the orogen and the geodynamical evolution of this area cannot be understood without the influence of the Neogene Mediterranean rifting, following the continental collision. The complexity of this area and the controversy of the geophysical results set in debate concepts well recognized in the other parts of the Pyrenees such as the subduction of the Iberian lower crust and the depth of the lithosphere-asthenosphere boundary. The aims of this study are to characterise major tectonic and geophysical variations along the Pyrenean mountain range at a lithospheric-scale and constrain the causes of the observed lateral variations. A preliminary model of the lithospheric configuration and dynamics, based on magnetotelluric geophysical results, has been developed and constrained using independent and available geophysical, geological and geochemical data. Computational petrology methods, using Litmod, were used for integrated modelling of all data.

  12. Nodule bottom backscattering study using multibeam echosounder

    Chakraborty, B.; Raju, Y.S.N.; Nair, R.R.

    A study is carried out to observe the angular dependence of backscattering strength at nodule area where grab sample and photographic data is available. Theoretical study along with the experimentally observed data shows that the backscattering...

  13. Introduction of sub-lithospheric component into melted lithospheric base by propagating crack: Case study of migrated Quaternary volcanoes in Wudalianchi, China

    Chuvashova, Irina; Sun, Yi-min


    From a long-lasted discussion on origin of mantle magmatism (i.e. Foulger, 2010), it follows that magmatic sources might belong to: (1) a plume, starting from the lower thermal boundary layer of the mantle, (2) a counterflow from the lower mantle after an avalanche of slab material from the transition layer, (3) a melting anomaly of a domain that extends above the transition layer at depths of 200-410 km, (4) a melting anomaly of a domain that occurs beneath the lithosphere at depths of 50-200 km, (5) a melting anomaly of the lithospheric base, activated due to its extension, and (6) a melting anomaly of the crust-mantle boundary originated through delamination of an orogenic root in compressional conditions. In this study, we present geological and geochemical evidence on the Quaternary volcanism related to the shallow melting anomaly at the lithospheric base. Eruptions of potassic liquids at the northern terminus of the Songliao basin, subsided from the Middle Jurassic to Paleogene, are limited to the Wudalianchi zone that is exhibited by the 230-km long north-south chain of late Cenozoic volcanic fields: Erkeshan - Wudalianchi - Keluo - Xiaogulihe. Contemporaneous eruptions of potassic-sodic melts are distributed at the western and eastern flanks of this zone, in the Nuominhe and Wuyiling volcanic fields, respectively. The melting anomaly is marked by local decreasing S-wave velocities at a depth of 100 km (Rasskazov et al., 2014). Lithospheric control of the potassic volcanism is emphasized by decreasing thickness of the crust up to 33.5 km (Wang, Chen, 2005). In the Wudalianchi field, volcanism commenced at ca. 2.3 Ma and episodically rejuvenated until AD1720-1721 (Guide book ..., 2010). From comparative geochemical study of volcanic rocks from the Wudalianchi zone and Nuominhe volcanic field, the volcanism was examined to be provided by melting of the heterogeneous lithospheric base, material of which was mixed with a common sub-lithospheric component. Due to

  14. An Integrated Geophysical study of the Lithospheric Structure Beneath Libya

    Brown, W. A.; Doser, D. I.; Keller, R. G.


    The tectonic evolution of Libya has yielded a complex crustal structure, which is composed of a series of basins and uplifts. A considerable amount of oil exploration has been undertaken in the area and numerous studies have been published on the shallow (feathering approached. The resulting mosaicked figures were then overlain with the previously mapped faults analyzed to identify the more recent faults.

  15. A Lithospheric Study of Eastern Asia Using Surface Wave Dispersion

    Pasyanos, M. E.; Walter, W. R.; Flanagan, M. P.


    We have continued our study of surface-wave group-velocity dispersion across Eastern Asia in the vicinity of the Korean Peninsula, Yellow Sea, and Sea of Japan. We primarily use seismic data from permanent stations in South Korea, China, Japan, Taiwan and Russia. We also use data from several IRIS PASSCAL deployments in China and North Korea. We measure group-velocity using multiple narrow-band filters on deconvolved displacement data. We use a conjugate gradient method to perform a high-resolution group-velocity tomography over the region. Our current results include Rayleigh wave inversions for periods from 10 to 100 seconds. There is an excellent correspondence between the group velocities and tectonic structure, including large sedimentary features and crustal thickness variations. At long periods (> 50 sec), we find that the inversion has features associated with the subduction of the Pacific and Philippine Plates under the Eurasian continent, including the effects of the subducting slab and magmatic arc. We use the group-velocity results to model the shear-velocity structure of the crust and upper mantle across the region. We employ a grid-search technique to fit the Rayleigh wave group-velocities over the whole period range. This does a very good job at retrieving features in the crust and uppermost mantle. Deeper features in the mantle, however, are harder to model directly using this method. To resolve these features, we will be forwarding modeling the structure by constructing several models of the subduction zone. We will then be testing the various models by comparing the group velocities predicted by the models to the observed group velocities along cross-sections. Preliminary results indicate that the magmatic arc has the largest affect on the long period surface waves, with the subducting slab being a much subtler feature.

  16. The continental lithosphere

    Artemieva, Irina


    The goal of the present study is to extract non-thermal signal from seismic tomography models in order to distinguish compositional variations in the continental lithosphere and to examine if geochemical and petrologic constraints on global-scale compositional variations in the mantle are...... consistent with modern geophysical data. In the lithospheric mantle of the continents, seismic velocity variations of a non-thermal origin (calculated from global Vs seismic tomography data [Grand S.P., 2002. Mantle shear-wave tomography and the fate of subducted slabs. Philosophical Transactions of the...... and evolution of Precambrian lithosphere: A global study. Journal of Geophysical Research 106, 16387–16414.] show strong correlation with tectono-thermal ages and with regional variations in lithospheric thickness constrained by surface heat flow data and seismic velocities. In agreement with xenolith...

  17. An isostatic study of the Karoo basin and underlying lithosphere in 3-D

    Scheiber-Enslin, Stephanie E.; Ebbing, Jörg; Webb, Susan J.


    A 3-D density model of the crust and upper mantle beneath the Karoo basin is presented here. The model is constrained using potential field, borehole and seismic data. Uplift of the basin by the end of the Cretaceous has resulted in an unusually high plateau (>1000 m) covering a large portion of South Africa. Isostatic studies show the topography is largely compensated by changes in Moho depths (˜35 km on-craton and >45 km off-craton) and changes in lithospheric mantle densities between the Kaapvaal Craton and surrounding regions (˜50 kg m-3 increase from on- to off-craton). This density contrast is determined by inverted satellite gravity and gravity gradient data. The highest topography along the edge of the plateau (>1200 m) and a strong Bouguer gravity low over Lesotho, however, can only be explained by a buoyant asthenosphere with a density decrease of around 40 kg m-3.

  18. Birth of the Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL)

    James, D. E.; Sacks, I. S.


    As recently as 1984 institutions doing portable seismology depended upon their own complement of instruments, almost all designed and built in-house, and all of limited recording capability and flexibility. No data standards existed. Around 1980 the National Research Council (NRC) of the National Academy of Sciences (NAS), with National Science Foundation (NSF) support, empanelled a committee to study a major new initiative in Seismic Studies of the Continental Lithosphere (SSCL). The SSCL report in 1983 recommended that substantial numbers (1000 or more) of new generation digital seismographs be acquired for 3-D high resolution imaging of the continental lithosphere. Recommendations of the SSCL committee dovetailed with other NRC/NAS and NSF reports that highlighted imaging of the continental lithosphere as an area of highest priority. For the first time in the history of portable seismology the question asked was "What do seismologists need to do the job right?" A grassroots effort was undertaken to define instrumentation and data standards for a powerful new set of modern seismic research tools to serve the national seismological community. In the spring and fall of 1983 NSF and IASPEI sponsored workshops were convened to develop specifications for the design of a new generation of portable instrumentation. PASSCAL was the outgrowth of these seminal studies and workshops. The first step toward the formal formation of PASSCAL began with an ad-hoc organizing committee, comprised largely of the members of the NAS lithospheric seismology panel, convened by the authors at Carnegie Institution in Washington in November 1983. From that meeting emerged plans and promises of NSF support for an open organizational meeting to be held in January 1984, in Madison, Wisconsin. By the end of the two-day Madison meeting PASSCAL and an official consortium of seismological institutions for portable seismology were realities. Shortly after, PASSCAL merged with the complementary

  19. Lateral heterogeneity and vertical stratification of cratonic lithospheric keels: a case study of the Siberian craton

    Artemieva, Irina; Cherepanova, Yulia; Herceg, Matija;


    regional xenolith P-T arrays,lithosphere density heterogeneity as constrained by free-board and satellite gravity data, and the non-thermalpart of upper mantle seismic velocity heterogeneity based on joint analysis of thermal and seismic tomography data.Density structure of the cratonic lithosphere...... strongly depleted lithospheric mantle of the Archean nuclei, particularly below the Anabar shield.Since we cannot identify the depth distribution of density anomalies, we complement the approach by seismicdata. An analysis of temperature-corrected seismic velocity structure indicates strong vertical and...

  20. Lithosphere structure of the NE Bohemian Massif (Sudetes) — A teleseismic receiver function study

    Geissler, W.H.; Kämpf, H.; Skácelová, Z.; Plomerová, Jaroslava; Babuška, Vladislav; Kind, R.

    564-565, Sep 5 (2012), s. 12-37. ISSN 0040-1951 R&D Projects: GA ČR GA205/07/1088; GA ČR GAP210/12/2381; GA MŠk LM2010008 Institutional research plan: CEZ:AV0Z30120515 Keywords : lithospheric structure * Moho discontinuity * lithosphere- asthenosphere boundary * Permo-Carboniferous volcanism * Central Europe Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.684, year: 2012

  1. Impact of bottom trawling on sediment characteristics - A study along inshore waters off Veraval coast, India

    Bhagirathan, U.; Meenakumari, B.; Jayalakshmy, K.V.; Panda, S.K.; Madhu, V.R.; Vaghela, D.T.

    The present communication is a study on the impact of bottom trawling on the sediment characteristics along Veraval coast, which is the largest trawler port of India. Experimental bottom trawling was conducted from MFV Sagarkripa at five transects...

  2. Experimental Study on the Measurement of Water Bottom Vibration Induced by Underwater Drilling Blasting

    Gu Wenbin; Chen Jianghai; Wang Zhenxiong; Wang Zhihua; Liu Jianqing; Lu Ming


    Due to the lack of proper instrumentations and the difficulties in underwater measurements, the studies about water bottom vibration induced by underwater drilling blasting are seldom reported. In order to investigate the propagation and attenuation laws of blasting induced water bottom vibration, a water bottom vibration monitor was developed with consideration of the difficulties in underwater measurements. By means of this equipment, the actual water bottom vibration induced by underwater ...

  3. A seismic tomography study of lithospheric structure under the Norwegian Caledonides

    Hejrani, Babak; Jacobsen, B. H.; Balling, N.;


    towards the north along the Caledonian Mountains or not? For this purpose we present new results of relative P-wave tomography for the northern SCANLIPS (SCANdinavia Lithosphere ProfileS) profile across the northern part of the Caledonides combined with data from permanent seismological stations in this...... area. These results are compared the upper mantle structure obtained by Medhus (2010) and Hejrani et al. (2011) for Caledonian and shield units to the south in southern Norway and Sweden, where the lithospheric transition follows the eastern margin of the Oslo Graben. Crooked line seismic tomography...

  4. Lithospheric mantle evolution monitored by overlapping large igneous provinces: Case study in southern Africa

    Jourdan, F.; Bertrand, H.; Féraud, G.; Le Gall, B.; Watkeys, M. K.


    Most of the studies on the large igneous provinces (LIPs) focus on Phanerozoic times, and in particular, those related to the disruption of Pangea (e.g. CAMP, Karoo, Parana-Etendeka) while Precambrian LIPs (e.g. Ventersdorpf, Fortescue) remain less studied. Although the investigation of Precambrian LIPs is difficult because they are relatively poorly preserved, assessment of their geochemical characteristics in parallel with younger overlapping LIP is fundamental for monitoring the evolution of the mantle composition through time. Recent 40Ar/ 39Ar dating of the Okavango giant dyke swarm (and related sills) in southern Africa showed that ~ 90% of the dykes were emplaced at 179 ± 1 Ma and belong to the Karoo large igneous province whereas ~ 10% of dykes yielded Proterozoic ages (~ 1-1.1 Ga). Here, we provide new major, trace and rare earth elements analyses of the low-Ti Proterozoic Okavango dyke swarm (PODS) that suggest, combined with age data, a cognate origin with the 1.1 Ga Umkondo large igneous province (UIP), southern Africa. The geochemical characteristics of the PODS and UIP basalts are comparable to those of overlapping low-Ti Karoo basalts, and suggest that both LIPs were derived from similar enriched mantle sources. A mantle plume origin for these LIPs is not easily reconciled with the geochemical dataset and the coincidence of two compositionally similar mantle plumes acting 900 Myr apart is unlikely. Instead, we propose that the Umkondo and Karoo large igneous provinces monitored the slight evolution of a shallow enriched lithospheric mantle from Proterozoic to Jurassic.

  5. Numerical Study on the Influence of Different Waving Bottom Form on the Fluid Surface Wave

    Yongxin Zhu


    Full Text Available In the present study, the effect of waving bottom on the surface wave is studied. Basing on the fundamental equations of potential flow theory and boundary conditions, using the multiple scales perturbation method to derive the first-order and the second-order approximate equation which the fluid surface waves satisfied in the presence of waving bottom. Under the second-order approximation, the fluid surface waveform in first-order approximate equation is numerically simulated with MATLAB in the presence of different waving bottom form. The results show that: the fluid surface waveform is composed of a harmonic wave which has the same frequency with waving bottom and a pair of KdV solitary waves that spread to both the right and the left side when the waving bottom wave is a harmonic wave; and when the waving bottom is a solitary wave packet, it consists of a solitary wave which is closely related to the specific form of waving bottom and a couple of KdV solitary waves. With the development of time, three waves in fluid surface do not affect each other and they propagate independently. Thus it can be seen the waving bottom is effective for maintaining surface wave energy balance income and expenditure in the spreading process.

  6. Tracing ancient events in the lithospheric mantle: A case study from ophiolitic chromitites of SW Turkey

    Akbulut, Mehmet; González-Jiménez, José María; Griffin, William L.; Belousova, Elena; O'Reilly, Suzanne Y.; McGowan, Nicole; Pearson, Norman J.


    New major-, minor- and trace-element data on high-Cr chromites from several ophiolitic podiform chromitites from Lycian and Antalya peridotites in southwestern Turkey reveal a polygenetic origin from a range of arc-type melts within forearc and back-arc settings. These forearc and the back-arc related high-Cr chromitites are interpreted to reflect the tectonic juxtaposition of different lithospheric mantle segments during the obduction. The diversity of the γOs(t=0) values (-8.28 to +13.92) in the Antalya and Lycian chromitite PGMs and their good correlations with the sub- to supra-chondritic 187Os/188Os ratios (0.1175-0.1459) suggests a heterogeneous mantle source that incorporated up to 40% recycled crust, probably due to subduction processes of the orogenic events. The few model ages calculated define two significant peaks in TRD model ages at 1.5 and 0.25 Ga, suggesting that the chromitites are younger than 0.25 Ga and include relics of an at least Mesoproterozoic or older (>1.0 Ga) mantle protolith. Eight of the nine zircon grains separated from the chromitites, are interpreted as detrital and/or resorbed xenocrystic relics, whilst a significantly less reworked/resorbed one is considered to be of metasomatic origin. In-situ U-Pb dating of the xenocrystic zircon grains yielded a spread of ages within ca 0.6-2.1 Ga, suggesting recycling of crustal rocks younger than 0.6 Ga (Late Neoproterozoic). The notable coincidence between the lower age limit of the older zircons (ca 1.6 Ga) and the oldest Os model age peak (ca 1.5 Ga) from the PGM may suggest a Mesoproterozoic rifting stage. These findings imply a Paleoproterozoic sub-continental lithospheric mantle (SCLM) protolith for the SW Anatolian mantle which was later converted into an oceanic lithospheric mantle domain possibly following a rifting and continental break-up initiated during Mesoproterozoic (ca 1.5-1.0 Ga). The single metasomatic zircon of ca 0.09 Ga age coinciding with the initiation of the

  7. Anisotropic tomography of the European lithospheric structure from surface wave studies

    Nita, Blanka; Maurya, Satish; Montagner, Jean-Paul


    We present continental-scale seismic isotropic and anisotropic imaging of shear wave upper-mantle structure of tectonically diversified terranes creating the European continent. Taking into account the 36-200 s period range of surface waves enables us to model the deep subcontinental structure at different vertical scale-lengths down to 300 km. After very strict quality selection criteria, we have obtained phase wave speeds at different periods for fundamental Rayleigh and Love modes from about 9000 three-component seismograms. Dispersion measurements are performed by using Fourier-domain waveform inversion technique named "roller-coaster-type" algorithm. We used the reference model with a varying average crustal structure for each source-station path. That procedure led to significant improvement of the quality and number of phase wave speed dispersion measurements compared to the common approach of using a reference model with one average crustal structure. Surface wave dispersion data are inverted at depth for retrieving isotropy and anisotropy parameters. The fast axis directions related to azimuthal anisotropy at different depths constitute a rich database for geodynamical interpretations. Shear wave anomalies of the horizontal dimension larger than 200 km are imaged in our models. They correlate with tectonic provinces of varying age-provenance. Different anisotropy patterns are observed along the most distinctive feature on our maps-the bordering zone between the Palaeozoic and Precambrian Europe. We discuss the depth changes of the lithosphere-asthenosphere boundary along the profiles crossing the chosen tectonic units of different origin and age: Fennoscandia, East European Craton, Anatolia, Mediterranean subduction zones. Within the flat and stable cratonic lithosphere, we find traces of the midlithospheric discontinuity.

  8. Study of top and bottom contact resistance in one organic field-effect transistor

    Liu Ge; Liu Ming; Wang Hong; Shang Li-Wei; Ji Zhuo-Yu; Liu Xing-Hua; Liu Jiang


    This paper reports that the organic field-effect transistors with hybrid contact geometry were fabricated,in whic hthe top electrodes and the bottom electrodes were combined in parallel resistances within one transistor.With the facility of the novel structure,the difference of contact resistance between the top contact geometry and the bottom contact geometry was studied.The hybrid contact devices showed similar characteristics with the top contact configuration devices,which provide helpful evidence on the lower contact resistance of the top contact configuration device.The origin of the different contact resistance between the top contact device and the bottom contact device was discussed.

  9. A Study on the Environmental Standard of Sediment on the Bottom of the Water

    Lee, Chang Hee; Yoo, Hye Jin [Korea Environment Institute, Seoul (Korea)


    Sediment on the bottom of the water has been considered one of the water pollutants in the environmental management of Korea so treated as a management on pollutants, as you can see the examples in the dragging operation in the polluted sea area. To healthily maintain and conserve the water ecosystem including bottom living things in the water, sediment on the bottom of the water should be recognized as the independent medium, which should maintain the certain quality like the water, the atmosphere, and soil, rather than the source of water pollution. Such recognition means that the management of sediment on the bottom of the water should change the fragmentary goal, centered the post management focusing on the water management, to the ecosystematic goal including the bottom living things. In a point of the view, this study has a great significance to suggest not only the final goal for the management of sediment on the bottom of the water but also the necessity of developing the environmental standard of the sediment on the bottom of the water, which is a standard of the management or judgment in the actual managing the sediment on the bottom of the water - an estimation on the pollution of sediment, a removal of the polluted sediment, a purification of sediment, and an abandonment of the dragged sediment -, and the development measures. Considering the situation that even the basic scheme related to the management of sediment is not prepared in the Government level, the concept of the environmental standard of sediment, the foreign example of the environmental standard of sediment, the current state of the domestic sediment pollution, and the development scheme of the environmental standard in this study must be the important foundation to establish the management system of sediment in the Government level. 121 refs., 10 figs., 45 tabs.

  10. Petrological and seismic studies of the lithosphere in the earthquake swarm region Vogtland/NW Bohemia, central Europe

    Geissler, W. H.; Kämpf, H.; Seifert, W.; Dulski, P.


    New petrological and geochemical data of upper mantle and lower crustal xenoliths from a Quaternary tephra deposit in Mýtina, Czech Republic, are discussed in the frame of previous geophysical results (receiver functions, reflection seismology) of the western Eger/Ohře Rift area. The Vogtland/NW Bohemia region is well known for intraplate earthquake swarms, which are usually associated with volcanic activity. As previously reported, 3He/ 4He data of CO 2 emissions in mofettes and mineral-water springs point at ongoing magmatic processes in this area. Using teleseismic P receiver functions, an approximately 40-km-wide Moho updoming (from 31 to 27 km) and indications for a seismic discontinuity at 50 to 60 km depth were observed beneath the active CO 2-degassing field. The studied xenolith suite probes a lithospheric profile within the structural and gas geochemical anomaly field of the western Eger Rift. With regard to texture, composition, p- T estimates and origin, five xenolith groups can be discriminated. Upper crustal xenoliths (quartzites, phyllites, mica schists) resemble crystalline country rocks at surface. One noritic xenolith (6 kbar, 800 °C) could represent a sample of the lower crust. Clinopyroxenites and hornblendites probably represent cumulates of the nephelinitic magma or fragments of magmatic veins. Porous wehrlites and one hornblende peridotite xenolith reflect a metasomatied upper mantle. Megacrysts of Ti-rich amphibole, olivine, clinopyroxene, and phlogopite could be fragments of pegmatitic veins or high-pressure phenocrysts. Most of the ultramafic nodules (xenoliths and megacrysts) formed at pressures between 6 and 11 kbar (22 to 38 km depth), at temperatures well above regional geotherms of the Bohemian Massif calculated from surface heat flow studies. Orthopyroxene-bearing spinel-lherzolite xenoliths were not observed. Our petrographical, geochemical, and thermobarometric results indicate a lithospheric mantle strongly altered by magmatic

  11. Can compaction, caused by melt extraction and intrusion, generate tectonically effective stresses in the lithosphere?

    Wallner, Herbert; Schmeling, Harro


    Aim of our study is to deepen understanding the role of melt processes while the lithospheric evolution by means of numerical modeling. In the sense of plate tectonics, on the one hand, stresses are transferred by stiff lithospheric plates, on the other, lithosphere is deformed, broken, or modified in various ways. Melting often plays an important role but is not easy to model numerically due to all the interactions of physics, phase changes, non-linearities, time scales, petrology, heterogeneities and chemical reactions. Here we restrict on a thermo-mechanical model of visco-plastic two phase flow with partial melting. Viscosity is temperature-, stress- and depth-dependent. Freezing and melting are determined by a simplified linear binary solid solution model. The fast melt transport through and into the lithosphere, acting on a short time scale, is replaced by melt extraction and intrusion in a given emplacement level. Numerical approximation is done in 2D with Finite Differences with markers in an Eulerian formulation. A scenario of continental rifting serves for a model of lithosphere above asthenosphere under extensional conditions. An anomaly of increased temperature at the bottom produces a low fraction of melt initially in the asthenosphere. Above a porosity limit melt is extracted and leads to compaction at its origin which induces under-pressure attracting ambient melt and contracting the depleted matrix. In a higher, colder lithospheric level the emplaced melt extends the matrix, immediately freezes; an increase of enrichment and heating takes place. The dilatation of the rock matrix generates relative high compaction pressures if it's viscosity is high as in the uppermost mantle lithosphere. Local and temporary varying stresses provide deviatoric components which sometimes may be the origin of tectonic activity in nature. Divergence terms of the full compaction formulation, responsible for viscous stress, are tested and reviewed. Quality and stability

  12. Numerical study of different bottom boundary conditions on water flow in lysimeters

    Groh, Jannis; Vanderborght, Jan; Pütz, Thomas; Vereecken, Harry


    The separation of the bottom of the lysimeter from its surroundings in the field introduces an artificial boundary that may impact the water balance of lysimeters. The use of tension controlled lysimeter (TCL) prevents an artificial boundary at the end of the lysimeter. Water flow across the lysimeter bottom can be controlled by the adjustment of matric potentials at the lower end of the lysimeter to measured field conditions in the close vicinity of the facility. However lysimeters are often transferred from the place where the soil monoliths were sampled to another location for practical reasons or to study the effect of climate change (e.g. SOILCan). The water flux across the bottom boundary of translocated TCL can be affected if climatic conditions, soil properties and the hydrogeological setting in the field differ from the place where the lysimeter was taken from. To assess the potential impact of different bottom boundary conditions on the water balance of translocated TCL a numerical study in virtual soils was conducted. We present a comparison of different approaches using water balance simulations. Results shows that water balance components of translocated TCL are sensitive towards the soil hydraulic parameters and hydrogeological setting in the field. The change in field conditions can impact the water flux dynamic across the lysimeter bottom, change the evaporation and the plant water uptake and release. A shift in the climate regime (translocation) will modify the depth and dynamics of the water table and impact the water balance of lysimeters.

  13. How To Design A Triple Bottom Line Organization: A Start-Up Case Study

    Bernhard Schroeder


    Full Text Available In today’s business environment, where success for a start-up company is measured by early revenue and profit, it can be quite challenging to design a triple bottom line organization (people/planet/profit from the very beginning. We present a case study of a U.S.-based start-up firm and discuss its early challenges, developmental processes, and current success as a triple bottom line firm. The company’s founder and CEO, with no initial product, distribution, or revenue strategy, sought to develop a company that could provide the marketplace with a valuable product while also staying true to a corporate vision of positively affecting less fortunate people. Our analysis of the case suggests that the founder’s vision, passion, transparent communication, and leveraging of partners’ resources were key elements in building the firm. We draw implications of our case study for the designers of future triple bottom line organizations.

  14. The fate of the Indian lithosphere beneath western Tibet: Upper mantle elastic wave speed structure from a joint teleseismic and regional body wave tomographic study

    Razi, Ayda S.; Roecker, Steven W.; Levin, Vadim


    We investigate the fate of the Indian lithosphere following its descent beneath western Tibet by means of tomographic imaging based on arrival times of body waves from regional and teleseismic sources recorded by a portable network deployed in the region from 2007 to 2011. We use a non-linear iterative algorithm that simultaneously models absolute, regional, and relative teleseismic arrival times to obtain a 3-D velocity structure in a spherical segment that extends from 26°N to 37°N, from 76°E to 89°E, and from the surface to 430 km depth. We find that variations in P and S wave speeds in the upper mantle are similar, and identify a number of prominent fast anomalies beneath western Tibet and the adjacent Himalayas. We associate these fast anomalies with the mantle lithosphere of India that is likely colder and hence faster than the ambient mantle. Resolution tests confirm the ability of our dataset to resolve their shapes in the upper 300 km, and the lack of significant downward smearing of these features. We interpret the presence of faster material below 300 km as being consistent with former Indian lithosphere having reached these depths. There are two main fast anomalies in our model. One resembles a ∼100 km wide sub-vertical column located directly beneath the India-Asia plate boundary. The other anomaly is thinner, and has the shape of a dipping slab that spans the north-south width of the Lhasa block. It dips towards the NE, starting near the Indus-Yarlung suture and ending north of the Bangong-Nujiang Suture at depths in excess of 300 km. Another finding of our study is the absence of major fast anomalies west of ∼80°E, which our resolution tests show to be significant. Our results do not support the notion of a continuous body of formerly Indian lithosphere being presently underthrust northward, and extending all the way to the northern boundary of the plateau. Rather, shapes of fast anomalies in western Tibet suggest colder material beneath the

  15. Single and Tertiary System Dye Removal from Aqueous Solution Using Bottom Ash: Kinetic and Isotherm Studies

    R. Gandhimathi


    Full Text Available This paper investigates the ability of Bottom ash to adsorb three cationic dyes from aqueous solution in single and tertiary systems. Crystal Violet (CV, Methylene Blue (MB and Malachite Green (MG were used as cationic dye models. The surface characteristics of Bottom ash were investigated using Fourier Transform Infrared (FTIR. Pseudo second order model was fitted better than Pseudo First order model for all system of MG, MB and CV. From the isotherm study, the adsorption capacity increased in the order of MB< MGBottom ash decreases in tertiary system as compared to single system. Langmuir and Freundlich isotherm models were fitted for all system of dyes. Freundlich isotherm model found to be the best fit for all systems.

  16. The life cycle of bottom-up ideas : case studies of the companies where the simulation game method was applied

    Forssén, Minna


    The main aim of this thesis is to study the life cycle of the incremental "bottom-up" ideas, which concern process and organizational matters. According to earlier studies, bottom-up ideas are not always successfully used and managed and as well there exists need for more study on organizational and process innovations. It is therefore useful to study this phenomenon more and gain more information about how organizations manage the development and implementation of these bottom-up ideas. ...

  17. Electromagnetic imaging of lithosphere permeable zones

    Litvinova, Tamara; Petrova Petrova, Alevtina; Petrishchev Petrishchev, Maxim


    By way of strong minima of magnetic anomalies studies we are investigated the features of the lithosphere structure by magnetic and gravity data. Exploration methods included the application of existing and open source near-surface aeromagnetic (WDMAM) with satellite data both at 100 km and 400 km in altitude (CHAMP) and gravity satellite data (GRACE). Aeromagnetic data have been used for the 2D geomagnetic model for a depth range from 3 to 50 km plotting. Gravity data has allowed to study the 2D density model for a depth range from 5 to 200 km plotting. At the heart of the geomagnetic and density model plotting lies the technique of the spectral-spatial representation of a geomagnetic field converted in a deep geomagnetic model. The technique of the spectral-spatial analysis (SPAN) is used to differentiate the weakly magnetic heterogeneities within the basement. In this paper we have studied the structure of the lithosphere in the area of deep magnetic minima in the vicinity of the eastern part of the Fennoscandian Shield, Central Europe and the northern part of South America. We have found powerful (more than 10 km) permeable feeble magnetic zones in the middle crust (20-30 km in depth) that are detected as feebly magnetic layer using the geomagnetic data. The magnetic minimum at 100 and 400 km in altitude corresponds to this feeble magnetic layer. It stands out as the low density layer at depth 20-35 km and, after the break, at depth 60-100 km. Ground-based magnetotelluric survey has allowed to allocate the high-conductivity layer at depth 15-30 and 60-110 km. It suggests that the detected layers can be rheological weak. The same is for the regions of Central Europe and South America. The powerful feebly magnetic layers have been detected in the middle and bottom crust (30-50 km for the Central Europe and 30-40 km for South America). The low density layers have been found for 20-35 km and 50-80 km in depth. The ground based measurement has confirmed the presence

  18. Cobalt and precious metals in sulphides of peridotite xenoliths and inferences concerning their distribution according to geodynamic environment: A case study from the Scottish lithospheric mantle

    Hughes, Hannah S. R.; McDonald, Iain; Faithfull, John W.; Upton, Brian G. J.; Loocke, Matthew


    Abundances of precious metals and cobalt in the lithospheric mantle are typically obtained by bulk geochemical analyses of mantle xenoliths. These elements are strongly chalcophile and the mineralogy, texture and trace element composition of sulphide phases in such samples must be considered. In this study we assess the mineralogy, textures and trace element compositions of sulphides in spinel lherzolites from four Scottish lithospheric terranes, which provide an ideal testing ground to examine the variability of sulphides and their precious metal endowments according to terrane age and geodynamic environment. Specifically we test differences in sulphide composition from Archaean-Palaeoproterozoic cratonic sub-continental lithospheric mantle (SCLM) in northern terranes vs. Palaeozoic lithospheric mantle in southern terranes, as divided by the Great Glen Fault (GGF). Cobalt is consistently elevated in sulphides from Palaeozoic terranes (south of the GGF) with Co concentrations > 2.9 wt.% and Co/Ni ratios > 0.048 (chondrite). In contrast, sulphides from Archaean cratonic terranes (north of the GGF) have low abundances of Co (< 3600 ppm) and low Co/Ni ratios (< 0.030). The causes for Co enrichment remain unclear, but we highlight that globally significant Co mineralisation is associated with ophiolites (e.g., Bou Azzer, Morocco and Outokumpu, Finland) or in oceanic peridotite-floored settings at slow-spreading ridges. Thus we suggest an oceanic affinity for the Co enrichment in the southern terranes of Scotland, likely directly related to the subduction of Co-enriched oceanic crust during the Caledonian Orogeny. Further, we identify a distinction between Pt/Pd ratio across the GGF, such that sulphides in the cratonic SCLM have Pt/Pd ≥ chondrite whilst Palaeozoic sulphides have Pt/Pd < chondrite. We observe that Pt-rich sulphides with discrete Pt-minerals (e.g., PtS) are associated with carbonate and phosphates in two xenolith suites north of the GGF. This three

  19. Lithospheric thermal-rheological structures of the continental margin in the northern South China Sea


    Thermal structures of three deep seismic profiles in the continental margin in the northern South China Sea are calculated, their "thermal" lithospheric thicknesses are evaluated based on the basalt dry solidus, and their rheological structures are evaluated with linear frictional failure criterion and power-law creep equation. "Thermal" lithosphere is about 90 km in thickness in shelf area, and thins toward the slope, lowers to 60-65 km in the lower slope, ocean crust and Xisha Trough. In the mid-west of the studied area, the lithospheric rheological structure in shelf area and Xisha Islands is of four layers: brittle, ductile, brittle and ductile. Because of uprising of heat mantle and thinning of crust and lithosphere in Xisha Trough, the bottom of the upper brittle layer is only buried at 16 km. In the eastern area, the bottom of the upper brittle layer in the north is buried at 20 km or so, while in lower slope and ocean crust, the rheological structure is of two layers of brittle and ductile, and crust and uppermost mantle form one whole brittle layer whose bottom is buried at 30-32 km. Analyses show that the characteristics of rheological structure accord with the seismic result observed. The character of rheological stratification implies that before the extension of the continent margin, there likely was a ductile layer in mid-lower crust. The influence of the existence of ductile layer to the evolution of the continent margin and the different extensions of ductile layer and brittle layer should not be overlooked. Its thickness, depth and extent in influencing continent margin's extension and evolution should be well evaluated in building a dynamic model for the area.

  20. On the Radon mechanism of the Lithosphere-Atmosphere coupling. Tlamacas mountain case study, volcano Popocatepetl area, Mexico

    Kotsarenko, A.; Grimalsky, V.; Yutsis, V. V.; Koshevaya, S.; Bravo Osuna, A.


    Results on Radon monitoring in 3 different sites in volcano Popocatepetl and referent site revealed Radon depletion anticipating 9 cases of moderate eruptive activity among 23 total events. The most pronounced reaction was observed in Tlamacas observational site. The averaged Radon concentration in Paso de Cortes and Tlamacas 2 sites is significantly lower in comparison with that at Tlamacas; the Radon variation in the mentioned sites has many specific features meanwhile in the Tlamacas site Radon behavior emphasizes a more individual character. The combined study by means of Radon survey, Gamma ray, Uranium, Thorium and Potassium spectrometry revealed an anomalously increased diffusion Radon emanation localized in the area of Tlamacas. Complementary geophysical studies by methods of gravimetric and magnetic prospection make credible postulation about volcanic origin of Tlamacas mountain. Observed zonal geological structures in the Tlamacas mountain and surrounding area may stimulate intensive Radon emanation from the volcanic depth. A new conception is proposed regarding a Lithosphere-Atmosphere coupling in the case of Tlamacas being similar in nature with a shortened electrical circuit Earth—thunderstorm clouds (high-altitude mountains) so that an enhanced ionization caused by intensive Radon release may explain in a novel way the noise-like geomagnetic emission observed before destructive earthquakes and volcanic eruptions. Numerical simulation gives values of geomagnetic perturbations 10-3 - 10-1 nT under "normal" conditions which can easily transform into the range 1 - 10 nT in the case of higher electric field E > 1 kV/m which is typical for mountains.

  1. Lithospheric layering in the North American craton.

    Yuan, Huaiyu; Romanowicz, Barbara


    How cratons-extremely stable continental areas of the Earth's crust-formed and remained largely unchanged for more than 2,500 million years is much debated. Recent studies of seismic-wave receiver function data have detected a structural boundary under continental cratons at depths too shallow to be consistent with the lithosphere-asthenosphere boundary, as inferred from seismic tomography and other geophysical studies. Here we show that changes in the direction of azimuthal anisotropy with depth reveal the presence of two distinct lithospheric layers throughout the stable part of the North American continent. The top layer is thick ( approximately 150 km) under the Archaean core and tapers out on the surrounding Palaeozoic borders. Its thickness variations follow those of a highly depleted layer inferred from thermo-barometric analysis of xenoliths. The lithosphere-asthenosphere boundary is relatively flat (ranging from 180 to 240 km in depth), in agreement with the presence of a thermal conductive root that subsequently formed around the depleted chemical layer. Our findings tie together seismological, geochemical and geodynamical studies of the cratonic lithosphere in North America. They also suggest that the horizon detected in receiver function studies probably corresponds to the sharp mid-lithospheric boundary rather than to the more gradual lithosphere-asthenosphere boundary. PMID:20740006

  2. A Study on Inviscid Flow with a Free Surface over an Undulating Bottom

    Srikumar Panda


    In this paper, the problem involving inviscid flow with a free surface over an undulating bottom is studied within the framework of linear theory. Applying perturbation analysis in conjunction with the Fourier transform technique, the boundary value problem arising from the flow problem is solved analytically. Behaviour of both interface and free-surface profiles, which are unknown at the outset, are analyzed. It is found that each profile (interface and free-surface) possesses a ...

  3. Technical and economic study of Stirling and Rankine cycle bottoming systems for heavy truck diesel engines

    Kubo, I.


    Bottoming cycle concepts for heavy duty transport engine applications were studied. In particular, the following tasks were performed: (1) conceptual design and cost data development for Stirling systems; (2) life-cycle cost evaluation of three bottoming systems - organic Rankine, steam Rankine, and Stirling cycles; and (3) assessment of future directions in waste heat utilization research. Variables considered for the second task were initial capital investments, fuel savings, depreciation tax benefits, salvage values, and service/maintenance costs. The study shows that none of the three bottoming systems studied are even marginally attractive. Manufacturing costs have to be reduced by at least 65%. As a new approach, an integrated Rankine/Diesel system was proposed. It utilizes one of the diesel cylinders as an expander and capitalizes on the in-cylinder heat energy. The concept eliminates the need for the power transmission device and a sophisticated control system, and reduces the size of the exhaust evaporator. Results of an economic evaluation indicate that the system has the potential to become an attractive package for end users.

  4. Subduction-driven recycling of continental margin lithosphere.

    Levander, A; Bezada, M J; Niu, F; Humphreys, E D; Palomeras, I; Thurner, S M; Masy, J; Schmitz, M; Gallart, J; Carbonell, R; Miller, M S


    Whereas subduction recycling of oceanic lithosphere is one of the central themes of plate tectonics, the recycling of continental lithosphere appears to be far more complicated and less well understood. Delamination and convective downwelling are two widely recognized processes invoked to explain the removal of lithospheric mantle under or adjacent to orogenic belts. Here we relate oceanic plate subduction to removal of adjacent continental lithosphere in certain plate tectonic settings. We have developed teleseismic body wave images from dense broadband seismic experiments that show higher than expected volumes of anomalously fast mantle associated with the subducted Atlantic slab under northeastern South America and the Alboran slab beneath the Gibraltar arc region; the anomalies are under, and are aligned with, the continental margins at depths greater than 200 kilometres. Rayleigh wave analysis finds that the lithospheric mantle under the continental margins is significantly thinner than expected, and that thin lithosphere extends from the orogens adjacent to the subduction zones inland to the edges of nearby cratonic cores. Taking these data together, here we describe a process that can lead to the loss of continental lithosphere adjacent to a subduction zone. Subducting oceanic plates can viscously entrain and remove the bottom of the continental thermal boundary layer lithosphere from adjacent continental margins. This drives surface tectonics and pre-conditions the margins for further deformation by creating topography along the lithosphere-asthenosphere boundary. This can lead to development of secondary downwellings under the continental interior, probably under both South America and the Gibraltar arc, and to delamination of the entire lithospheric mantle, as around the Gibraltar arc. This process reconciles numerous, sometimes mutually exclusive, geodynamic models proposed to explain the complex oceanic-continental tectonics of these subduction zones

  5. Seismic and gravity study of the lithospheric structure of the Southern Oklahoma Aulacogen and surrounding region

    Tave, M.; Gurrola, H.; Mickus, K. L.; Thomas, W. A.


    The Southern Oklahoma Aulacogen (SOA) is easily recognizable in gravity and magnetic maps as perhaps the second largest gravity anomaly in North America (second to the Mid-continental rift). The SOA lies in the Granite Rhyolite province of Oklahoma. It is characterized by large magnitude basement faults that were active during Cambrian rifting and were reactivated as thrust faults during the late Paleozoic (313-285 Ma) during the Ouachita Orogeny. The SOA was originally considered to be a failed rift of a triple junction associated with Cambrian-aged opening of the Iapetan Ocean. This model is supported by the three-armed pattern of gravity highs at the junction of the SOA with Ouachita orogen, the age of the bimodal series of gabbroic and rhyolitic rock (that are clearly mantle derived), and the interpretation of a thick sequence of clastic metasedimentary rock as rift-fill. These metasedimentary rock, however, have been found to be much older than the SOA faulting and volcanism. More recent investigations favor models that describe the SOA as a system of leaky transform faults that are roughly parallel to the Alabama-Oklahoma transform fault, which partially frames part of the Iapetan margin of Southern Laurentia. This study will try to use seismic and gravity modeling to resolve the nature of the SOA and to determine the depth (into the mantle) to which features related to the formation of the SOA are preserved. The EarthScope transportable array (TA) has completed data acquisition in Oklahoma and Texas. We have made receiver functions (RF) from the TA along the SOA and found that the there is an abrupt change in crustal structure across the SOA. RF analysis shows that a mid-crustal boundary occurs at about 15 km south of the SOA that dips toward the SOA. North of the SOA, this midcrustal boundary appears to be 5 km shallower and flat. The Moho appears to be 45 km deep to the south of the SOA but appears to be at a depth of about 38 km to the north. Additional

  6. Bottom production

    In the context of the LHC experiments, the physics of bottom flavoured hadrons enters in different contexts. It can be used for QCD tests, it affects the possibilities of B decays studies, and it is an important source of background for several processes of interest. The physics of b production at hadron colliders has a rather long story, dating back to its first observation in the UA1 experiment. Subsequently, b production has been studied at the Tevatron. Besides the transverse momentum spectrum of a single b, it has also become possible, in recent time, to study correlations in the production characteristics of the b and the b. At the LHC new opportunities will be offered by the high statistics and the high energy reach. One expects to be able to study the transverse momentum spectrum at higher transverse momenta, and also to exploit the large statistics to perform more accurate studies of correlations

  7. Bottom production

    Baines, J.; Baranov, S.P.; Bartalini, P.; Bay, A.; Bouhova, E.; Cacciari, M.; Caner, A.; Coadou, Y.; Corti, G.; Damet, J.; Dell-Orso, R.; De Mello Neto, J.R.T.; Domenech, J.L.; Drollinger, V.; Eerola, P.; Ellis, N.; Epp, B.; Frixione, S.; Gadomski, S.; Gavrilenko, I.; Gennai, S.; George, S.; Ghete, V.M.; Guy, L.; Hasegawa, Y.; Iengo, P.; Jacholkowska, A.; Jones, R.; Kharchilava, A.; Kneringer, E.; Koppenburg, P.; Korsmo, H.; Kramer, M.; Labanca, N.; Lehto, M.; Maltoni, F.; Mangano, M.L.; Mele, S.; Nairz, A.M.; Nakada, T.; Nikitin, N.; Nisati, A.; Norrbin, E.; Palla, F.; Rizatdinova, F.; Robins, S.; Rousseau, D.; Sanchis-Lozano, M.A.; Shapiro, M.; Sherwood, P.; Smirnova, L.; Smizanska, M.; Starodumov, A.; Stepanov, N.; Vogt, R.


    In the context of the LHC experiments, the physics of bottom flavoured hadrons enters in different contexts. It can be used for QCD tests, it affects the possibilities of B decays studies, and it is an important source of background for several processes of interest. The physics of b production at hadron colliders has a rather long story, dating back to its first observation in the UA1 experiment. Subsequently, b production has been studied at the Tevatron. Besides the transverse momentum spectrum of a single b, it has also become possible, in recent time, to study correlations in the production characteristics of the b and the b. At the LHC new opportunities will be offered by the high statistics and the high energy reach. One expects to be able to study the transverse momentum spectrum at higher transverse momenta, and also to exploit the large statistics to perform more accurate studies of correlations.

  8. Bottom-up or top-down in dream neuroscience? A top-down critique of two bottom-up studies.

    Foulkes, David; Domhoff, G William


    Recent neuroscientific studies of dreaming, specifically those in relation to waking sensory-motor impairments, but also more generally, betray a faulty understanding of the sort of process that dreaming is. They adhere to the belief that dreaming is a bottom-up phenomenon, whose form and content is dictated by sensory-motor brain stem activity, rather than a top-down process initiated and controlled by higher-level cognitive systems. But empirical data strongly support the latter alternative, and refute the conceptualization and interpretation of recent studies of dreaming in sensory-motor impairment in particular and of recent dream neuroscience in general. PMID:24905546

  9. SuperB: An opportunity to study baryons with beauty and bottom super-nuclei

    Feliciello, A., E-mail: [Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Via P. Giuria 1, I-10125 Torino (Italy)


    SuperB is an INFN flagship project for a new high-luminosity heavy-flavor factory. Along with its companion detector, it is dedicated to the search for CP violation effects in the B meson sector with the aim of looking for direct and indirect signals of new physics, beyond the Standard Model. However it could offer as well the opportunity for a systematic, high-statistics study of b baryon properties and for a search for bottom super-nuclei, that is bound nuclear systems with an explicit content of beauty.

  10. Progress Report: Integrated Ecological Studies at Lisbon Bottom Unit, Big Muddy Fish and Wildlife Refuge, Fiscal Year 1999

    US Fish and Wildlife Service, Department of the Interior — The U.S. Geological Survey has been carrying out integrated ecological studies at the Lisbon Bottom Unit of the Big Muddy Fish and Wildlife Refuge since 1996. This...



    Interaction between current and underwater bottom topography modulates roughness of the sea surface, which in turn yields variation of the radar scattering echo. By using the mechanism, this paper presents a simulation model for Synthetic Aperture Radar (SAR) imaging of underwater bottom topography. The numerical simulations experiments were made using the Princeton Ocean Model (POM) and analytical expression theory of SAR Image in Mischief sea area. It is concluded that the SAR image is better visual when water depth of underwater bottom topography is shallow or gradient of underwater bottom topography is high.

  12. Application of model studies for quality control of bottom pressure based GLOSS sea level gauge at Takoradi Harbour (Ghana, West Africa)

    Joseph, A.; Mehra, P.; Desai, R.G.P.; Dotse, J.; Odammetey, J.T.; Nkebi, E.K.; VijayKumar, K.; Prabhudesai, S.

    Quality-control of bottom pressure based sea level gauge has been effected using a statistically derived simple linear model constructed from a set of bottom pressures and concurrent tide-staff measurements. The study reveals that the crucial factor...

  13. Using dichotic listening to study bottom-up and top-down processing in children and adults.

    Andersson, Martin; Llera, John Eric; Rimol, Lars M; Hugdahl, Kenneth


    The study examined top-down attention modulation of bottom-up processing in children and adults under conditions of varying bottom-up stimulus demands. Voiced and unvoiced consonant-vowel syllables were used in a dichotic-listening situation to manipulate the strength of the bottom-up stimulus-driven right ear advantage when subjects were instructed to focus attention on, and report, either the left or right ear stimulus. We predicted that children would differ from adults in their ability to use attention to modulate a lateralized ear advantage, and particularly when there was a conflict between the direction of the bottom-up ear advantage and the direction of the top-down attention instruction. Thirty children and 30 adults were presented with dichotic presentations of consonant-vowel syllables. The results showed that the voicing manipulation affected the strength of the ear advantage, and that the children performed significantly below the adults when the voicing parameter caused a strong conflict between bottom-up and top down processing. Thus, children seem to lack the cognitive flexibility necessary to modulate a stimulus-driven bottom-up ear advantage, particularly in situations where right ear advantage (REA) is enhanced by the acoustic properties of the stimuli and attentional demands require a left ear shift. It is suggested that varying the stimulus demands in a dichotic-listening situation may be a novel way to study cognitive development. PMID:18608228

  14. The lithospheric mantle below southern West Greenland

    Sand, Karina Krarup; Waight, Tod Earle; Pearson, D. Graham; Nielsen, Troels F.D.; Makovicky, Emil; Hutchison, Mark T.

    Geothermobarometry of primarily garnet lherzolitic xenoliths from several localities in southern West Greenland is applied to address the diamond potential, pressure and temperature distribution and the stratigraphy of the subcontinental lithospheric mantle ~600 Ma ago. The samples are from...... been conducted. No variation in P-T gradients between the three distinct crustal areas has been discerned. We find that the lithospheric mantle beneath this region extended to a depth of 215 km at the time of eruption, with a geotherm similar to those defined by peridotites from the Slave craton and...... the Kirkland Lake locality within the Superior craton. In supporting previous studies we find that the continental lithospheric mantle is layered and increases in fertility with depth. Twenty-five of 32 investigated samples are estimated to be derived from the diamond stability field that extends into...

  15. Numerical study of swirling flow in a cylinder with rotating top and bottom

    Shen, Wen Zhong; Sørensen, Jens Nørkær; Michelsen, Jess


    A numerical investigation of oscillatory instability is presented for axisymmetric swirling flow in a closed cylinder with rotating top and bottom. The critical Reynolds number and frequency of the oscillations are evaluated as function of the ratio of angular velocities of the bottom and the top...

  16. A Study on Inviscid Flow with a Free Surface over an Undulating Bottom

    Srikumar Panda


    Full Text Available In this paper, the problem involving inviscid flow with a free surface over an undulating bottom is studied within the framework of linear theory. Applying perturbation analysis in conjunction with the Fourier transform technique, the boundary value problem arising from the flow problem is solved analytically. Behaviour of both interface and free-surface profiles, which are unknown at the outset, are analyzed. It is found that each profile (interface and free-surface possesses a wave free region at the far upstream, followed by a modulated downstream wave. It also observed, for the first time, that the amplitude of the downstream wave is varying. Further, the effects of various system parameters are analyzed and demonstrated in graphical forms.

  17. QCD sum rule study of a charged bottom-strange scalar meson

    Zanetti, C. M.; Nielsen, M.; Khemchandani, K. P.


    Using the QCD sum rule approach, we investigate the possible four-quark structure for the new observed Bs0π± narrow structure (D0). We use a diquak-antidiquark scalar current and work to the order of ms in full QCD, without relying on 1 /mQ expansion. Our study indicates that although it is possible to obtain a stable mass in agreement with the state found by the D0 collaboration, more constraint analysis (simultaneous requirement of the OPE convergence and the dominance of the pole on the phenomenological side) leads to a higher mass. We also predict the masses of the bottom scalar tetraquark resonances with zero and two strange quarks.

  18. Socio-economic impacts of nuclear generating stations: Peach Bottom case study

    This report documents a case study of the socio-economic impacts of the construction and operation of the Peach Bottom nuclear power station. It is part of a major post-licensing study of the socio-economic impacts at twelve nuclear power stations. The case study covers the period beginning with the announcement of plans to construct the reactor and ending in the period 1980 to 1981. The case study deals with changes in the economy, population, settlement patterns and housing, local government and public services, social structure, and public response in the study area during the construction/operation of the reactor. A regional modeling approach is used to trace the impact of the construction/operation on the local economy, labor market, and housing market. Emphasis in the study is on the attribution of socio-economic impacts to the reactor or other causal factors. As part of the study of local public response to the construction/operation of the reactor, the effects of the Three Mile Island accident are examined


    XUE Yang; XU Wei-lin; LUO Shu-jing; CHEN Hua-yong; LI Nai-wen; XU Ling-jun


    Dam break can cause a significant disaster in the downstream,especially,in a valley with cascade reservoirs,which would aggravate the disaster extent.The experimental studies of the dam-break flow of cascade reservoirs are few and far between at the present.Most of related studies concern the failure of a single dam..This article presents an experimental study of the characteristics of an instantly filled dam-break flow of cascade reservoirs in a rectangular glass flume with a steep bottom slope.A new method was used to simulate the sudden collapse of the dam.A series of sensors for automatic water-levels were deployed to record the rapid water depth fluctuation.The experimental results show that,the ratio of the initial water depth of the downstream reservoir to that of the upstream reservoir would greatly affect the flood peak water depth in the downstream reservoir area and in the stream channel behind the downstream dam,while the influence of the dam spacing is insignificant.In addition,the comparison between the single reservoir and the cascade reservoirs shows some difference in the dam-break flow pattern and the stage hydrograph at the corresponding gauging points.

  20. Bottom Factors Applied to the Zoning Study of the Risk Levels of Landslides in the Three Gorges Reservoir Area

    QIAO Jianping; ZHU Axing; WU Caiyan; TIAN Hongling


    Without taking inducing factors into consideration, this paper adopts a quantitative analysis of the bottom factors in the Three Gorges Reservoir area, studies the relationship between the bottom factors and the development of landslides, and then zones the area according to risk levels. The bottom factors adopted in this paper include lithological characters(U1), gradient(U2), slope form(U3), difference of height(U4), and slope orientation(U5). In 4 650 km2 of the studied area, the areas of the very high, high, medium and low hazard degree area respectively were 57.94 km2, 2 305.15 km2, 1 241.6 km2, 1 045.31 km2. The methodological steps are ① inversion statistic analysis, ② the analysis of contribution ratio and weighing, ③ getting results via fuzzy evaluation of risk levels.

  1. Perennial plate tectonics with lasting mantle lithosphere scars

    Heron, P.; Pysklywec, R. N.; Stephenson, R.


    Although the conventional theory of plate tectonics can explain non-rigid behaviour at plate boundaries, it cannot adequately explain the processes involved in deformation and seismicity within plate interiors. Here, we consider that the pre-existing deformation or "scarring" within the mantle lithosphere may have a very long lived presence that could incorporate deformation of the plate interior and plate boundary. Mantle lithosphere scars from continent-continent collisions could generate virtual plate boundaries that remain over long timescales, producing "perennial" plate tectonics. Local geophysical studies can map the crustal environment well, and global whole mantle tomography models are rapidly improving, yet high-resolution images of the mantle lithosphere are often not available in regions where scarring may be present. Where mantle lithosphere heterogeneities have been observed (usually interpreted simply as subduction scars), the same attention has not been afforded to them as, for example, re-activation of faults within the Earth's crust. In idealized numerical simulations, we compare how relic scarring at varying depths in the lithosphere affects patterns of deformation. High-resolution thermal-mechanical numerical experiments explore continental lithospheric deformation featuring a weakened crust and mantle lithosphere scars. Our models show that deep lithospheric scars can control the tectonic evolution of a region over shallow geological features, indicating the importance of mantle lithosphere heterogeneities. The Altyn Tagh Fault (ATF) in central China is an example of an ancient continental collision zone that undergoes periodic deformation during times of regional compression. We suggest that the ATF may be a locale where a long-lasting mantle lithosphere scar can control the subsequent crustal evolution and deformation, with ancient plate boundaries having a "perennial" plate tectonic presence.

  2. Stability of Continental Lithosphere based on Analogue Experiments with Microwave Induced Internal Heating

    Fourel, Loic; Limare, Angela; Surducan, Emanoil; Surducan, Vasile; Neamtu, Camelia; Vilella, Kenny; Farnetani, Cinzia; Kaminski, Edouard; Jaupart, Claude


    Continental lithosphere is usually depicted as the upper conductive layer of the Earth. Its formation is achieved through melt depletion that generates a residue that is less dense and more viscous than the underlying convecting mantle. As it is cooled from above, continental lithosphere can develop its own convective currents and may become unstable depending on its thickness and density contrast with the mantle. But chemical differentiation due to mantle magmatism also enriches continental lithosphere in heat producing elements. According to present estimates, the Earth's mantle may have lost as much as half of its radioactive elements in favour of continental crust and this stratified redistribution of heat sources has two main effects. First, mantle convection vigor decreases and becomes increasingly sensitive to heat supply from the core. Second, localized heat production at the top surface increases the continental insulating effects and competes against lithospheric instabilities. In the present study, we focus on the later and we determine which amount of internal heating is required to keep the lithosphere stable for a given rate of cooling from the top. The physics underlying instability triggering corresponds to the problem of a two differentially heated layered system cooled from above, where the top layer is less dense and more viscous than the bottom one, representative of the lithosphere-mantle system. Few studies have been devoted to the intrinsic characteristics of this layered type of convection. Here, we present a state of the art laboratory setup to generate internal heating in controlled conditions based on microwave (MW) absorption. The volumetric heat source can be localized in space and its intensity can be varied in time. Our tank prototype has horizontal dimensions of 30 cm x 30 cm and 5 cm height. A uniform and constant temperature is maintained at the upper boundary by an aluminium heat exchanger and adiabatic conditions are imposed at

  3. Experimental studies of anomalous radon activity in the Tlamacas Mountain, Popocatepetl Volcano area, México: new tools to study lithosphere-atmosphere coupling for forecasting volcanic and seismic events

    Jose Antonio Lopez Cruz Abeyro; G. Urquiza Beltrán; Hector Roman Peréz Enríquez; Svetlana Koshevaya; Ana Gabriela Bravo Osuna; Vsevolod Yutsis; Vladimir Grimalsky; Anatoliy Kotsarenko; Carlos Valdés Gonzales


    This study presents and discusses the results of soil radon monitoring at three different volcano sites and one reference site, from December 2007 to January 2009. This relates to the activity of the Popocatepetl Volcano and a radon survey and gamma-ray spectrometry in the area between Paso de Cortes and Tlamacas Mountain, and in the adjacent regions. The results are applied to the aspects of atmosphere electricity and lithosphere-atmosphere coupling in relation to the forecasting of...

  4. Bottom-up study of flaw tolerance properties of protein networks

    Qin, Zhao; Buehler, Markus


    We study the material properties of an intermediate filament proten network by computational modeling using a bottom-up approach. We start with an atomic model of each filament's and obtain the mechanical behavior of them. We then use these parameters in setting up a mesoscale model of the network material at scales of micrometers. Using this multi-scale method, we report a detailed analysis of the associated deformation and failure mechanisms of this hierarchical material. Our modeling reveals that a structure transition that occurs at the proteins' secondary structure level is crucial for the networks' flaw tolerance property, which implies that the material retains its mechanical function despite the existence of large defects. We also examine the effect of crosslink strength on the failure properties. We discover that relatively weaker crosslinks lead to a more flaw tolerant network that is 23% stronger. This unexpected behavior is caused by that the crosslink strength functions as a switch to alter the failure mechanism. Weak crosslinks are able to efficiently diffuse the stress around the crack tip, making the crack more difficult to propagate. We compare our results to that of elastic and softening materials and find that the effect of crosslink strength is much smaller in those systems. These findings imply that the mechanical properties of both the filaments and interfaces among filaments are critical for bioinspired material designs, challenging the conventional paradigm in engineering design.

  5. Isotope studies of the Caspian Sea: Climatic record from bottom sediments (preliminary results)

    Two cores (7.8 m and 9.3 m long) of bottom sediments from the southern and middle Caspian Sea were studied. Variation of the stable isotopes of oxygen and carbon in the carbonates, radiocarbon dating, lithological structure and distribution of the main salt ions Cl-, Na+, and K+ along the core length wave were used to develop a general picture of the relationship between water level fluctuation and climatic change in the sea basin within the last 70 ka. It was found that during the glacial ages the sea level dropped as far as the Apsheron sill, and the southern and middle parts of the sea were separated. At the time of interglacial episodes, when the southern and northern glaciers melted, the water level rose and both sea basins merged. It was determined that about 40 ka BP, during the Khvalinean transgression after the Ostashkov episode of the Valday (Wurm) glaciation, the Caspian Sea discharged to the Black Sea through the Kuma-Manych Valley (25 m a.s.l.). (author)

  6. The Lithosphere in Italy: Structure and Seismicity

    We propose a structural model for the lithosphere-asthenosphere system for the Italic region by means of the S-wave velocity (VS) distribution with depth. To obtain the velocity structure the following methods are used in the sequence: frequency-time analysis (FTAN); 2D tomography (plotted on a grid 1o x 1o); non-linear inversion; smoothing optimization method. The 3D VS structure (and its uncertainties) of the study region is assembled as a juxtaposition of the selected representative cellular models. The distribution of seismicity and heat flow is used as an independent constraint for the definition of the crustal and lithospheric thickness. The moment tensor inversion of recent damaging earthquakes which occurred in the Italic region is performed through a powerful non-linear technique and it is related to the different rheologic-mechanic properties of the crust and uppermost mantle. The obtained picture of the lithosphere-asthenosphere system for the Italic region confirms a mantle extremely vertically stratified and laterally strongly heterogeneous. The lateral variability in the mantle is interpreted in terms of subduction zones, slab dehydration, inherited mantle chemical anisotropies, asthenospheric upwellings, and so on. The western Alps and the Dinarides have slabs with low dip, whereas the Apennines show a steeper subduction. No evidence for any type of mantle plume is observed. The asymmetric expansion of the Tyrrhenian Sea, which may be interpreted as related to a relative eastward mantle flow with respect to the overlying lithosphere, is confirmed. (author)

  7. A Phenomenological Study of Bottom Quark Fragmentation in Top Quark Decay

    Gennaro CorcellaEnrico Fermi Ctr., Rome & SNS, Pisa & INFN, Pisa; Federico Mescia(Barcelona U.)


    Top-quark physics is one of the main fields of investigation at the Tevatron accelerator and, ultimately, at the LHC. We perform a phenomenological analysis of ttbar events at hadron colliders, with a focus on observables relying on bottom-quark fragmentation in top-quark decay. In particular, we investigate the B-lepton invariant-mass distribution in the dilepton channel and give an estimate of the contribution of bottom fragmentation to the Monte Carlo uncertainty on the top-quark mass reco...

  8. A phenomenological study of bottom-quark fragmentation in top-quark decay

    Corcella, Gennaro [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Rome (Italy); Scuola Normale Superiore, Pisa (Italy); INFN, Sezione di Pisa, Pisa (Italy); Mescia, Federico [Universitat de Barcelona, Departamento d' Estructura i Constituents de la Materia (ECM) and Institut de Ciencies del Cosmos (ICC), Barcelona (Spain)


    Top-quark physics is one of the main fields of investigation at the Tevatron accelerator and, ultimately, at the LHC. We perform a phenomenological analysis of t anti t events at hadron colliders, with a focus on observables relying on bottom-quark fragmentation in top-quark decay. In particular, we investigate the B-lepton invariant-mass distribution in the dilepton channel and give an estimate of the contribution of bottom fragmentation to the Monte Carlo uncertainty on the top-quark mass reconstruction. (orig.)

  9. Study of major factors to affect photoresist profile on developable bottom anti-reflective coating process

    Roh, Hyo Jung; Ju, Dong Kyu; Kim, Hyun Jin; Kim, Jaehyun


    As critical dimensions continue to shrink in lithography, new materials will be needed to meet the new demands imposed by this shrinkage. Recently, there are needs for novel materials with various substrates and immersing process, including double patterning process, a high resolution implant process, and so on. Among such materials, Developable Bottom Anti-reflective Coating material (DBARC) is a good candidate for high resolution implant application as well as double patterning. DBARC should have reflectivity control function as an ordinary BARC, as well as an appropriate solubility in TMAH-based conventional developer after exposure and bake process. The most distinguished advantage of DBARC is to skip BARC etch process that is required in normal BARC process. In spite of this advantage, the photoresist profile on DBARC could be influenced by components and process conditions of DBARC. Several groups have tried to solve this issue to implement DBARC to new process. We have studied material-related factors affecting photoresist profiles, such as a polymer, photo-acid generators (PAGs), and additives. And we explored the effect of process condition for photoresist and DBARC. In case of polymer, we studied the effect of dissolution rate in developer and crosslinking functionality. For PAGs and additives, the effect of acid diffusivity and cross-linking degree according to their bulkiness were examined. We also evaluated coated film stability in a photoresist solvent after BARC bake process and compared lithographic performance of various DBARC formulations. In addition, the effect of photoresist profile with bake condition of photoresist and DBARC were investigated. In this paper, we will demonstrate the most influential factors of DBARC to photoresist profile and suggest the optimum formulation and process condition for DBARC application.

  10. A comparative study on water column and bottom feeding habit of tank reared brook trout

    Feed consumption growth rate and feed conversion were compared for brook trout (Salvelinus fontinalis) feeding in the water column or at the tank bottom. The trial that lasted 120 days was conducted in four 300 L fibreglass tanks with two replicates of fish (mean weight of 45.9 g) in each feeding treatment. Fish fed in the water column exhibited a mean (SD) specific growth rate(SGR) of 0.93 and reached a final mean weight of 138.9 (28.9) g whereas bottom fed fish had a mean SGR of 0.91 and 135.7 (39.2) g body weight. Overall feed conversion ratios (FCR) and condition factors (CF) were assessed as 1.73, 1.22 for the water column and 1.71, 1.25 bottom fed fish. None of these variables showed statistically significant difference between the treatments. thus, it seems that brook trout may feed both in water column and at bottom in tank culture conditions and this habit could be utilised for reducing feed waste in intensive commercial trout culture

  11. Segmentation and Positioning in the Brazilian Kids Market: A Case Study on the Bottom of the Pyramid

    Andres Rodriguez Veloso


    Full Text Available This article approaches the kids market, focusing on the Bottom of the Pyramid. A case study is developed within the toy industry. Because few studies have been developed on this subject (kids marketing, the option of this study is to focus on basic marketing strategies, market segmentation and positioning. Results exemplify how can a company structure its marketing strategy in order to have a clear focus on a given segment of the kids market.

  12. Hybrid Combined Cycles with Biomass and Waste Fired Bottoming Cycle - a Literature Study

    Petrov, Miroslav P.


    incinerators is probably the option with the greatest efficiency improvement potential, within the reasonable cost and scale limits. Furthermore, a State-of-Art report is included in the study as a separate chapter. Descriptions of existing hybrid combined cycle installations with biofuel-fired bottoming cycle in Sweden and its surrounding countries are compiled in it. The presentation shows that hybrid combined cycles are a standard technology in many respects. These specific configurations have been chosen as the most rewarding ones out of various alternatives and have proved their advantages in commercial operation. The major research project following this literature study will focus on investigation of possible efficiency improvement of biomass energy utilization by application of hybrid configurations with natural gas fired gas turbine and internal combustion engines as topping cyclesof curve fitting procedures)

  13. Mechanisms and geologic significance of the mid-lithosphere discontinuity in the continents

    Karato, Shun-Ichiro; Olugboji, Tolulope; Park, Jeffrey


    The stable continents have a puzzling structure. Recent seismological studies have revealed a marked drop in seismic velocity at middle-lithosphere depths, but a generally small velocity drop at the lithosphere-asthenosphere boundary. The mid-lithosphere discontinuity has previously been attributed to changes in composition and/or crystal alignment (anisotropy) caused by metasomatic alteration, as well as to partial melting and/or accretion of intruded materials that occurred after the formation of the continents. We show that these models cannot easily explain the global presence of a large seismic velocity drop in the middle lithosphere and a small velocity change at the lithosphere-asthenosphere boundary. These models are also difficult to reconcile with long-term continental stability and, in particular, observations of nearly depth-invariant ages of rocks in the continental lithosphere that do not support the notion of late alteration events. Instead, we propose an elastically accommodated grain-boundary sliding model that predicts a substantial velocity drop at the mid-lithosphere discontinuity and a weak seismic signal at the lithosphere-asthenosphere boundary, as observed, without invoking late-stage modifications to the lithosphere. In this model, the mid-lithosphere discontinuity is a general feature of the stable continents, the precise depth of which depends primarily on temperature and water content. Consequently, the depth of the mid-lithosphere discontinuity may provide clues to the evolution of continents.

  14. Comparative study of the fluid dynamics of bottom spray fluid bed coaters

    Chan, L. W.; Tang, Elaine S. K.; Heng, Paul W. S.


    Fluid dynamics of pellets processed in bottom spray traditional Wurster coating and swirl accelerated air (precision) coating were compared with the intent to understand and facilitate improvements in the coating processes. Fluid dynamics was described by pellet mass flow rate (MFR) obtained using a pellet collection system and images captured using high speed photography. Pellet flow within the partition column was found to be denser and slower in Wurster coating than in precision coating, s...

  15. A computational study of liposome logic: towards cellular computing from the bottom up

    Smaldon, James; Romero-Campero, Francisco J.; Fernández Trillo, Francisco; Gheorghe, Marian; Alexander, Cameron; Krasnogor, Natalio


    In this paper we propose a new bottom-up approach to cellular computing, in which computational chemical processes are encapsulated within liposomes. This “liposome logic” approach (also called vesicle computing) makes use of supra-molecular chemistry constructs, e.g. protocells, chells, etc. as minimal cellular platforms to which logical functionality can be added. Modeling and simulations feature prominently in “top-down” synthetic biology, particularly in the specification, design and impl...

  16. Air demand estimation in bottom outlets with the particle finite element method - Susqueda Dam case study

    Salazar, Fernando; San-Mauro, Javier; Celigueta, Miguel Ángel; Oñate, Eugenio


    Dam bottom outlets play a vital role in dam operation and safety, as they allow controlling the water surface elevation below the spillway level. For partial openings, water flows under the gate lip at high velocity and drags the air downstream of the gate, which may cause damages due to cavitation and vibration. The convenience of installing air vents in dam bottom outlets is well known by practitioners. The design of this element depends basically on the maximum air flow through the air vent, which in turn is a function of the specific geometry and the boundary conditions. The intrinsic features of this phenomenon makes it hard to analyse either on site or in full scaled experimental facilities. As a consequence, empirical formulas are frequently employed, which offer a conservative estimate of the maximum air flow. In this work, the particle finite element method was used to model the air-water interaction in Susqueda Dam bottom outlet, with different gate openings. Specific enhancements of the formulation were developed to consider air-water interaction. The results were analysed as compared to the conventional design criteria and to information gathered on site during the gate operation tests. This analysis suggests that numerical modelling with the PFEM can be helpful for the design of this kind of hydraulic works.


    Richard Amfo-Otua; Sarah Graham Kyerewaa; Emmanuel Adu Ofori; Adams Sadick


    Treatment of healthcare waste either by incinerating or open burning in a pit produces bottom ashes which contains heavy metals and other chemicals which are toxic, persistent and accumulate in the food chain resulting in adverse health effects in human and the environment. The study investigated the level of heavy metals in the ashes of thermally treated medical waste from four health care facilities in Ghana. Two batch of the ash samples were collected from two hospital incinerators and the...

  18. The Influence of Triple Bottom Line on Strategic Positioning: An Exploratory Case Study on Differentiation through Image

    Hanan Alhaddi


    Using grounded theory as a methodological approach, the influence of triple bottom line (TBL) was explored as an emerging, yet substantially important phenomenon on strategic positioning through image differentiation. This study makes a contribution to the sustainability scholarship (TBL as a subset of sustainability) and the marketing scholarship by introducing and exploring the dynamics among TBL, strategic positioning, differentiation, and image. This is done by presenting The Influence of...

  19. Studies of evolved stars. V. Nucleosynthesis in hot-bottom convective envelopes

    Convective envelopes fitted to the cores of luminous double shell models have been found to develop high base temperatures, (40-80) times106degreeK, during the period between shell flashes. We show that these ''hot-bottom'' envelopes are the result of the increasing influence of radiation pressure on the radiative and adiabatic temperature gradients. Lower limits on the luminosity (M)/sub bol/approx. =-5.4) and total mass (approx.1.5M/sub mass/) required for the phenomenon are derived; these values depend sensitively on the treatment of the radiative atmosphere and the ionization zones. Light-element nucleosynthesis in hot-bottom envelopes is examined using a convective diffusion model. Large surface 7Li enhancements are produced by the 7Be transport mechanism if the base temperature T/subb/ exceeds 30times106degreeK. Sufficient time before carbon ignition exists for CN processing if T/subb/approximately-greater-than50times106degreeK, while full CNO processing and hydrogen depletion may occur if T/subb/approximately-greater-than75times106degreeK. Comparison with observations indicates that nucleosynthesis in hot-bottom envelopes is not the primary cause of the abundance anomalies observed in peculiar red giants, except possibly for the large 13C/12C ratios and lithium enhancements found in some stars. In particular, mixing of tripe-α carbon and s-process elements initiated by the helium shell flashes seems to be required in order to satisfy constraints imposed by the observed line and band strengths and luminosities

  20. A computational study of liposome logic: towards cellular computing from the bottom up.

    Smaldon, James; Romero-Campero, Francisco J; Fernández Trillo, Francisco; Gheorghe, Marian; Alexander, Cameron; Krasnogor, Natalio


    In this paper we propose a new bottom-up approach to cellular computing, in which computational chemical processes are encapsulated within liposomes. This "liposome logic" approach (also called vesicle computing) makes use of supra-molecular chemistry constructs, e.g. protocells, chells, etc. as minimal cellular platforms to which logical functionality can be added. Modeling and simulations feature prominently in "top-down" synthetic biology, particularly in the specification, design and implementation of logic circuits through bacterial genome reengineering. The second contribution in this paper is the demonstration of a novel set of tools for the specification, modelling and analysis of "bottom-up" liposome logic. In particular, simulation and modelling techniques are used to analyse some example liposome logic designs, ranging from relatively simple NOT gates and NAND gates to SR-Latches, D Flip-Flops all the way to 3 bit ripple counters. The approach we propose consists of specifying, by means of P systems, gene regulatory network-like systems operating inside proto-membranes. This P systems specification can be automatically translated and executed through a multiscaled pipeline composed of dissipative particle dynamics (DPD) simulator and Gillespie's stochastic simulation algorithm (SSA). Finally, model selection and analysis can be performed through a model checking phase. This is the first paper we are aware of that brings to bear formal specifications, DPD, SSA and model checking to the problem of modeling target computational functionality in protocells. Potential chemical routes for the laboratory implementation of these simulations are also discussed thus for the first time suggesting a potentially realistic physiochemical implementation for membrane computing from the bottom-up. PMID:21886681

  1. The electrical Lithosphere of the Alboran Domain

    Garcia, X. A.; Evans, R. L.; Elsenbeck, J.; Jegen, M. D.; Matsuno, T.


    On the Western edge of the Mediterranean, the slow convergence of the Iberian and African plates is marked by very intricate tectonic activity, marked by a combination of small-scale subduction and sub-lithospheric downwelling. Delamination or convective instability has also been proposed to have occurred beneath this domain during the past 25 My. And different geodynamic models have been proposed to explain the lithospheric structure of the arc-shaped belt (Betic and Rif orogenies) and the opening of the Alboran Basin. As part of several international projects carried out in this area, magnetotelluric (MT) methods have been used to explore the crust and upper mantle. The measurements of mantle electrical conductivity are a well known complement to measurements of seismic velocity. Conductivity is sensitive to temperature, composition and hydration of the mantle, and therefore MT is widely used to provide constraints on mantle processes. We present results of electromagnetic studies in the Western Mediterranean, focusing specially in the recently work on the Alboran sea as part of a marine MT survey. Land MT studies have already imaged an area of low resistivity coincident with an area of low velocities without earthquake hypocenters, interpreted as asthenospheric material intruded by the lateral lithospheric tearing and breaking-off of the east-directed subducting Ligurian slab under the Alboran Domain. The model suggests that the most likely scenario for the opening of the Alboran Basin is related to the westward rollback of the Ligurian subducting slab. The marine data show complex MT response functions with strong distortion due to seafloor topography and coast effect, suggesting a fairly resistive lithosphere beneath the seafloor.

  2. Observation and study of bottom-meson decays to a charm meson, a proton-antiproton pair, and pions

    Hong, Tae Min [Univ. of California, Santa Barbara, CA (United States)


    Bottom-meson decays with baryons show two unusual features—the branching fractions are enhanced for multibody decays and the baryon-antibaryon subsystem recoils against the other decay products—and their reasons are not yet well understood. Moreover, measurements using explicit reconstruction techniques constitute only about 1% out of about 8% of such decays. This Dissertation reports the study of ten bottom-meson decays (labeled 0– 9) to a proton-antiproton pair, a charm meson, and a system of up to two pions, using the BABAR Experiment’s 455×106 BB pairs produced with the PEP-II asymmetric-energy e+e- collider at the Stanford Linear Accelerator Center.

  3. The impact of fish predation on shallow soft bottoms in brackish waters (SW Finland); an experimental study

    Mattila, J.; Bonsdorff, E.

    The impact of fish predation on shallow soft bottoms was studied by field and laboratory experiments. The field manipulations (caging experiments) were carried out in 2 shallow (1.5 m) bays in the northern Baltic Sea. An a priori hypothesis that fish do not structure macrozoobenthic communities in shallow soft-bottom areas was tested. Short-term aquarium experiments clearly showed that perch ( Perca fluviatilis L.), roach ( Rutilus rutilus L.) and ruffe ( Acerina cernua (L.)) are all effective predators on benthic macroinvertebrates ( Corophium volutator) Pallas and Nereis diversicolor O.F. Müller) under laboratory conditions. Thus fish can be considered a potential structuring force on benthic communities in shallow soft-bottom areas. Caging experiments of one to two month's duration (partial and total exclosure of fish and enclosure with perch) induced only minor changes in the benthic community. These results support the a priori hypothesis. One of our main conclusions is, however, that fish predation and other biotic interactions (competition, disturbance, etc.) together with abiotic factors play some role in the structuring processes. Multilevel testing is needed in studies on biotic interactions in the marine environment. Results from a specific environment should not automatically be applied to other kinds of habitats.

  4. Bottom-up approach for decentralised energy planning: Case study of Tumkur district in India

    Decentralized Energy Planning (DEP) is one of the options to meet the rural and small-scale energy needs in a reliable, affordable and environmentally sustainable way. The main aspect of the energy planning at decentralized level would be to prepare an area-based DEP to meet energy needs and development of alternate energy sources at least-cost to the economy and environment. Present work uses goal-programming method in order to analyze the DEP through bottom-up approach. This approach includes planning from the lowest scale of Tumkur district in India. The scale of analysis included village level-Ungra, panchayat level (local council)-Yedavani, block level-Kunigal and district level-Tumkur. The approach adopted was bottom-up (village to district) to allow a detailed description of energy services and the resulting demand for energy forms and supply technologies. Different scenarios are considered at four decentralized scales for the year 2005 and are developed and analyzed for the year 2020. Decentralized bioenergy system for producing biogas and electricity, using local biomass resources, are shown to promote development compared to other renewables. This is because, apart from meeting energy needs, multiple goals could be achieved such as self-reliance, local employment, and land reclamation apart from CO2 emissions reduction.

  5. Lithospheric rheology and Moho upheaval control the generation mechanism of the intraplate earthquakes in the North China Basin

    Liu, Chang; Zhu, Bojing; Shi, Yaolin


    Many devastating intraplate earthquakes, such as the 1966 Xingtai earthquake (Ms 7.2) and the 1976 Tangshan earthquake (Ms 7.8), occurred in the North China Basin (NCB). This study aims to investigate the generation mechanism of the large intraplate earthquakes in the NCB and the spatial distribution of earthquake activity through numerical experiments. In order to simulate the interseismic stress accumulation process in the NCB, we set up several 3D finite element models based on different lithospheric rheological structure and apply boundary conditions of horizontal compression. We find that stress concentration with high rate in the regions where Moho upheaves is responsible for the large earthquakes in the NCB. During the interseismic period large stress rate is located nearly around the bottom of the brittle upper crust, where stress accumulates fast to reach fault strength and active the main shocks. Aftershocks in the seismogenic layers could be triggered by the main shocks. Two factors are critical to the crustal stress accumulation process. (1) The first is Moho upheaval in the seismic zones. (2) The second is viscosity contrast among the crustal layers. Our results support the lithospheric rheological structure in the NCB as following: the brittle upper crust, brittle-ductile transition in the middle crust, the ductile lower crust, and the ductile lithospheric upper mantle.

  6. Study of Charm and Bottom Particle Production Using a Holographic Bubble Chamber


    The experimental arrangement consists mainly of a small, rapid cycling, heavy liquid bubble chamber, HOBC, equipped for holography and a muon detector. The high spatial resolution which can be obtained in a small holographic bubble chamber (5-10 @mm) allows a good efficiency for the detection of shortlived particles like charm and bottom particles. With the one muon trigger the proportion of these particles is greatly enhanced. For the first phase of the experiment the emphasis is on the determination of charm cross-sections. The aim is to determine the production cross-sections at 100, 200 and 300 GeV/c for different incident particles, and consequently determine the energy dependence of the charm cross-sections.

  7. A Study on Bottom Friction Coefficient in the Bohai, Yellow, and East China Sea

    Daosheng Wang


    Full Text Available The adjoint tidal model based on the theory of inverse problem has been applied to investigate the effect of bottom friction coefficient (BFC on the tidal simulation. Using different schemes of BFC containing the constant, different constant in different subdomain, depth-dependent form, and spatial distribution obtained from data assimilation, the M2 constituent in the Bohai, Yellow, and East China Sea (BYECS is simulated by assimilating TOPEX/Poseidon altimeter data, respectively. The simulated result with spatially varying BFC obtained from data assimilation is better than others. Results and analysis of BFC in BYECS indicate that spatially varying BFC obtained from data assimilation is the best fitted one; meanwhile it could improve the accuracy in the simulation of M2 constituent. Through the analysis of the best fitted one, new empirical formulas of BFC in BYECS are developed with which the commendable simulated results of M2 constituent in BYECS are obtained.

  8. Preface to "Insights into the Earth's Deep Lithosphere"

    Pasyanos, M E


    Dear Readers: I am pleased to present a special issue of Tectonophysics entitled 'Insights into the Earth's Deep Lithosphere.' This compilation sought to capture the flavor of the increasing number of studies that are emerging to investigate the complex lithospheric structure of the earth. This issue evolved out of a Fall 2007 AGU special session entitled 'Understanding the Earth's Deep Lithosphere' that I organized with Irina Artemieva from the University of Copenhagen. For that session, we solicited talks that discussed the increasing number of methods that have surfaced to study various aspects of the earth's deep lithosphere. These methods include seismic, gravity, thermal, geochemical, and various combinations of these methods. The quality of the presentations (2 oral sessions with 16 talks and 23 associated poster presentations) was such that we felt that the emerging topic deserved a dedicated forum to address these questions in greater detail. The availability of new data sets has also improved the number and quality of lithospheric studies. With many new studies and methodologies, a better understanding of both continental and oceanic lithospheres is starting to emerge. Questions remain about the thickness and evolution of the lithosphere, the presence of lithospheric keels, the density and anisotropy of lithospheric roots, mechanisms of lithospheric thinning, and differences between mechanical, thermal and chemical boundary layers. While we did not get contributions on the full gamut of methods and regions, a lot of ground was covered in this issue's manuscripts. Like any collection of papers on the deep lithosphere, the topics are quite varied in methodology, geographic location, and what aspect of the lithosphere being studied. Still, the results highlight the rewarding aspects of earth structure, history, and evolution that can be gleaned. A brief synopsis of the papers contained in this issue is given.

  9. Thermal-rheological structure of the lithosphere beneath Jiyang Depression: Its implications for geodynamics

    LIU Shaowen; WANG Liangshu; GONG Yuling; LI Cheng; LI Hua; HAN Yongbing


    Jiyang Depression, located in the southeast Bohai Bay Basin, has the geomorphologic framework of multiple uplifts intervening with sags. Combined the abundant geo-temperature data and thermo-physical parameters of rock samples derived from oil and gas exploration during the past years, with geothermal approaches, here we investigate the lithospheric thermal regime of this depression. Consequently, based on the obtained thermal structure of the lithosphere, along with rheological modeling, the lithospheric rheological profiles of Jiyang Depression are then determined. Our results show that the temperature at the bottom of sedimentary cover within depression varies from 129℃ to 298℃, accompanied with the basement heat flow ranging between 54.3 and 60.5 mW/m2; and 406℃-436℃ for temperature at the bottom of the upper crust, along with heat flow varying from 47.7 to 52.6 mW/m2; while the temperature at the bottom of the middle crust is between 537℃ and 572℃, as well as heat flow ranging from 41.3 to 56.3 mW/m2. The temperature at Moho ranges from 669℃ to 721℃, the heat flow derived from mantle is between 38.1 and 43.1 mW/m2, and calculated thickness of the thermal lithosphere beneath depression varies from 71 to 90 km. Lithospheric thermal regime is a close correlation with such factors as crustal thickness and surface heat flow, etc. Usually, the larger the surface heat flow, the larger the deep temperature and heat flow within lithosphere, and the thinner the thermal lithospheric thickness. This high thermal regime of the lithosphere in Jiyang Depression is thought to be related to Cenozoic back-arc spreading during the western Pacific plate subduction into Eurasian continent. Lithospheric rheological modeling shows that the lithosphere in Jiyang Depression is characterized by its distinct rheological stratification as follows: The upper and most part of the middle crust are of brittle, while the lower crust and the lower part of middle crust are all

  10. The changing role of the lithosphere in models of glacial isostasy: a historical review

    Wolf, Detlef


    During the last 125 years, the role of the lithosphere in models of glacial-isostatic adjustment experienced several changes. Following the postulation of glacial isostasy by Jamieson in 1865, the lithosphere was generally regarded as comparable in importance for the adjustment process to the fluid substratum. This changed with the initiation of quantitative modelling by Van Bemmelen and Berlage and by Haskell in 1935, whereupon effects due to the lithosphere were commonly neglected in interpretations of postglacial uplift for 30 years. After the development of a layered viscous earth model with an elastic surface layer by McConnell in 1965, the lithosphere was eventually reintroduced into models of glacial isostasy. Subsequent studies largely confirmed the original ideas regarding the importance of the lithosphere for the adjustment process, although the effects are pronounced only for short-wavelength deformations. Using this response characteristic of the lithosphere, estimates of its thickness have recently become available for several tectonic provinces.

  11. Optical and electronic properties study of bottom-up graphene nanoribbons for photovoltaic applications

    Villegas, Cesar E. P.; Rocha, Alexandre


    Graphene nanoribbons (GNRs), turn out to be serious contender for several optolectronic applications due to their physical properties. Recently, bottom-up methods, using the assembly of appropriate precursor molecules were shown to be an exciting pathway towards making precise nanoribbons. In particular, it has been demonstrated that so-called cove-shaped GNRs absorb light in the visible part of the spectrum, suggesting they could be used for photovoltaic applications. In solar cells, the key ingredient is the presence excitons and their subsequent diffusion along a donor material. This is influenced by the character of the different excitations taking place, as well as, the exciton binding energy. Thus, In this work we use many-body corrected density functional theory to simulate the optical properties of these nanoribbons. We elucidate the most important transitions occurring in these systems, and identify types of excitatiions that have not been previously observed in conventional nanoribbons. We also find that the exciton binding energies for all the structures we considered are in the eV range, which enhances the diffusion lengths for the particle-hole pairs. Finally, we estimate the potencial of these systems as solar cells by calculating the short-circuit current. The Authors thank FAPESP for financial support.

  12. Bottom-up modelling of continuous renovation and energy balance of existing building stock: case study Kočevje

    Šijanec Zavrl, Marjana; Stegnar, Gašper; Rakušček, Andraž; Gjerkeš, Henrik


    A dynamic bottom-up model of the building stock is developed and implemented in a case study of Kočevje urban region. In the model, national register of real estate is cross-linked to data from other registers, e.g. the energy performance certificates (EPC) and the subsidized energy renovation measures. Regular updates of the data in registers enable continual improvement of the model. Therenovation potential is determined with respect to the age of building components after the last renovati...

  13. Projecting Different Identities: A Longitudinal Study of the 'Whipsaw' Effects of Changing Leadership Discourse About the Triple Bottom Line

    Moingeon, Bertrand; Bayle-Cordier , Julie


    This paper focuses on changes in leadership’s discourse about the "triple bottom line" in Ben & Jerry’s ice cream from its founding days through to its acquisition by and integration into Unilever. For this study, the authors analyzed CEO claims about "who we are" from their letters in annual reports (what they label projected identity). A sample of employees (both long-service and relative newcomers) were interviewed about their perceptions of B&J’s over the thirty years covered. Findings re...

  14. Lithospheric evolution of the Northern Arabian Shield: Chemical and isotopic evidence from basalts, xenoliths and granites

    Stein, M.


    The evolution of the upper-mantle and the lower-crust (the conteinental lithosphere), is the area of Israel and Sinai was studied, using the chemical composition and the Nd-Sr isotopic systematics from mantle and crustal nodules, their host basalts, and granites. The magmatism and the metasomatism making the lithosphere are related to uprise of mantle diapirs in the uppermost mantle of the area. These diapirs heated the base of the lithosphere, eroded, and replaced it with new hot material. It caused a domal uplift of the lithosphere (and the crust). The doming resulted in tensional stresses that in turn might develop transport channels for the basalt.

  15. Complexity of the Fennoscandian lithosphere

    Vinnik, Lev; Kozlovskaya, Elena; Oreshin, Sergey; Kosarev, Grigoriy; Silvennoinen, Hanna; Vaganova, Natalia; Kiselev, Sergey


    -explosion profile crossing this part of Fennoscandia. At the stations of the POLENET/LAPNET array the P-wave velocities are generally close to the IASPEI91 velocities down to a depth of about 200 km. The S-wave velocities are close to the IASPEI91 velocities in the depth interval from the Moho to 100 km and higher than the IASPEI91 velocities in a depth range from 100 to 200 km. The most complex lithosphere structure is obtained for stations where the anomalously thick (more than 60-km) crust is known from earlier controlled-source seismology experiments. For some stations the S-wave and P-wave crust-mantle boundaries are located at different depths (around 45 km and 75-80 km, respectively). In summary, the structure of the Fennoscandian lithosphere appears to be very complex and deserving further multi-disciplinary studies.

  16. Experimental studies of anomalous radon activity in the Tlamacas Mountain, Popocatepetl Volcano area, México: new tools to study lithosphere-atmosphere coupling for forecasting volcanic and seismic events

    Jose Antonio Lopez Cruz Abeyro


    Full Text Available

    This study presents and discusses the results of soil radon monitoring at three different volcano sites and one reference site, from December 2007 to January 2009. This relates to the activity of the Popocatepetl Volcano and a radon survey and gamma-ray spectrometry in the area between Paso de Cortes and Tlamacas Mountain, and in the adjacent regions. The results are applied to the aspects of atmosphere electricity and lithosphere-atmosphere coupling in relation to the forecasting of volcano and earthquake activity. The monitoring of radon release reveals a decrease in radon concentration (down to total suppression with approaching moderate volcanic eruptions. The behavior of the radon activity at the Tlamacas site is more apparent, compared to other observational sites. The average level of radon release observed at the Tlamacas site is much higher, with some characteristic variations. Both the radon survey and gamma-ray spectrometry indicate intensive diffusion radon emission localized in the area of Tlamacas Mountain. The average radon concentration in the area of Tlamacas is about 10-20-fold greater than the background volcano values. The new concept of lithosphere-atmosphere coupling is presented: intensive radon release in high elevated areas shortens and modifies the Earth-to-thunderclouds electric circuit, which provokes microdischarges into the air close to the ground, attracting lightning discharges. This concept attempts to explain in a new way the noise-like geomagnetic emissions registered before major earthquakes, and it promotes interest for the study of thunderstorm activity in seismo-active zones, as a promising instrument for earthquake forecasting.

  17. Studying interaction of technogenic radionuclides with particles of bottom land soils by the method of chemical fractionation

    During study of technogenic radionuclide interaction with particles of bottom land soils compounds of several types was separated by the method of chemical fractionation: a) 60Co radiocolloids and Eu isotopes with elements being contained in composition of polymeric films as sesquioxides and hydroxides (Fe, Al); b) organometallic complexes of 60Co, 137Cs and Eu isotopes with humus substances of soil as ligands. Substitution H2O2 oxidizer for chromic mixture in used fractionation scheme permits to increase radionuclide separation out of soil into solution by several fold: from 6.5 up to 46% for 60Co, from 1.4 up to 36% for 137Cs and from 5.2-8.5 up to 23-32% for Eu isotopes

  18. Effects of bottom topography on dynamics of river discharges in tidal regions: case study of twin plumes in Taiwan Strait

    K. A. Korotenko


    Full Text Available The Princeton Ocean Model is used to investigate the intratidal variability of currents and turbulent mixing and their impact on the characteristics and evolution of the plumes of two neighboring rivers, the Zhuoshui River and the Wu River, at the central eastern coast of Taiwan Strait. The two estuaries are located close to each other and their conditions are similar in many respects, and yet the two plumes exhibit significantly different behavior. We explain this through differences of the bottom topography in the areas adjacent to the two river mouths. The Zhuoshui River runs into a shallow area that is permanently exposed to strong tidal mixing, while the Wu River mouth is located in a deeper, stratified area outside the region of intense mixing. This destruction of the plume by tidal mixing is confirmed by the results of numerical modeling with POM. The spatial and temporal variability of turbulent kinetic energy and its production rate in the study region, as well as the horizontal diffusivity, are analyzed with the emphasis given to the dependence of the turbulence parameters on the bottom topography on the one hand and their influence on the river plumes on the other. Further, we use a Lagrangian particle tracking model in combination with POM to investigate the effect of the tidal wetting-and-drying (WAD of land taking place near the Zhuoshui estuary, and demonstrate that WAD leads to significant reduction of the plume extent and surface salinity deficit near the river mouth. We use observational data from a short field campaign in the study area to tune and validate the model experiments.

  19. From bottom-up to top-down : an fMRI study of language development

    Parks, Erin Nicole


    A growing number of functional MRI studies have examined age-related changes in language organization. However, existing studies have predominantly examined differences between children and adults using cross-sectional designs and have been limited to a single language component studied at a single point in time. Thus the mechanisms by which cognitive changes occur over time are still uncertain. A better understanding of developmental changes in the brain organization for language might broad...

  20. Magmatic expressions of continental lithosphere removal

    Wang, Huilin; Currie, Claire A.


    Gravitational lithosphere removal in continental interior has been inferred from various observations, including anomalous surface deflections and magmatism. We use numerical models and a simplified theoretical analysis to investigate how lithosphere removal can be recognized in the magmatic record. One style of removal is a Rayleigh-Taylor-type instability, where removal occurs through dripping. The associated magmatism depends on the lithosphere thermal structure. Four types of magmatism ar...


    Richard Amfo-Otua


    Full Text Available Treatment of healthcare waste either by incinerating or open burning in a pit produces bottom ashes which contains heavy metals and other chemicals which are toxic, persistent and accumulate in the food chain resulting in adverse health effects in human and the environment. The study investigated the level of heavy metals in the ashes of thermally treated medical waste from four health care facilities in Ghana. Two batch of the ash samples were collected from two hospital incinerators and the other two from medical waste burnt in an open-pit. The samples were collected on different days but within the same month, stored and transported to Water Research Institute laboratory for heavy metals analysis. The concentrations of Pb, Cd, Cr and Hg were assessed using Atomic Absorption Spectrophotometry (AAS. The results proved that the concentrations of heavy metals were higher for the waste treated in the incinerator than those burnt in the open pit. The average concentration of the metals in the ashes were in the following decreasing order Pb>Cr>Hg>Cd. The mean concentration of Pb from the incinerated bottom ash was 147.5mg/kg and Cd was 2.5mg/kg whilst the open pit was (69.67mg/kg and (1.34mg/kg respectively. All the metals investigated exceeded the Dutch and Danish limit values for maximum permissible levels of heavy metals in good soil quality and therefore classified as harmful and toxic and therefore proper attention should be given to the ash disposal at the landfill sites.

  2. Socioeconomic impacts of nuclear generating stations: Peach Bottom case study. Technical report 1 Oct 78-4 Jan 82

    The report documents a case study of the socioeconomic impacts of the construction and operation of the Peach Bottom nuclear power station. It is part of a major post-licensing study of the socioeconomic impacts at twelve nuclear power stations. The case study covers the period beginning with the announcement of plans to construct the reactor and ending in the period, 1980-81. The case study deals with changes in the economy, population, settlement patterns and housing, local government and public services, social structure, and public response in the study area during the construction/operation of the reactor. A regional modeling approach is used to trace the impact of construction/operation on the local economy, labor market, and housing market. Emphasis in the study is on the attribution of socioeconomic impacts to the reactor or other causal factors. As part of the study of local public response to the construction/operation of the reactor, the effects of the Three Mile Island accident are examined

  3. Influence of bottom topography on dynamics of river plumes in semi-enclosed domains: Case study in Taiwan Strait

    Zavialov, Peter; Korotenko, Konstantin; Osadchiev, Alexander; Kao, Ruei-Chi; Ding, Chung-Feng


    This paper summarizes the results of a Russian-Taiwan research project focused on the role of continental discharges into the Taiwan Strait, an important channel in the western Pacific Ocean transporting water between the South China Sea and the East China Sea. Another critically important hydrographic feature in the area is the discharge of freshwater from multiple rivers of the western coast of Taiwan. With its long-term average discharge rate of 210 m3/s, the Zhuoshui River is the biggest of the rivers bringing a large amount of pollutants and nutrients into the Strait. The northern extremity of Zhuoshui River's plume often merges with that of the Wu River (also known as Dudu River) whose average discharge rate is about 120 m3/s. Oceanic waters in the area experience significant anthropogenic pressures, traceable to the distance of a few km offshore and tens of km along the shore. This is manifested, in particular, in strongly elevated concentrations of copper, iron, and other trace metals. The corresponding quantitative estimates are obtained. The newly obtained in situ data from a field campaign were also used to implement 2 numerical models aimed at simulating the pathways of the continental waters in the study region. One of them, based on the Princeton Ocean Model, was coupled with a regional barotropic tidal model for the Taiwan Strait. The other one, a fully Lagrangian model STRiPE is based on applying a complete set of momentum equations to individual "particles" of river water released into the ocean. Both models demonstrated reasonable good agreement with the in situ data and each other. The bathymetry, tides and winds significantly affect the dynamics of the Wu and Zhuoshui river plumes, acting together in a complex interactive manner. The Zhuoshui River plume stretches in a narrow alongshore belt both to the south and north from the river mouth while the larger, round-shaped Wu River's plume elongates mostly north of its mouth. The difference is

  4. Peace Corps Volunteers and the Boundaries of Bottom-Up Development: Mongolia, a Case Study

    Schuckman, Hugh Erik


    From President Kennedy's first announcement of a non-military US volunteer corps in 1961, the Peace Corps has been one of the preeminent government grassroots volunteer development agency. This study explores the history of the ambiguities inherent in this contention, pressure primarily stemming from the organization's role as both a…

  5. A superconducting radiofrequency e+e- linear collider for bottom quark and nuclear physics studies

    The design of an accelerator complex based on recirculated linacs is presented. It could be used as a b-antib hadron factory and simultaneously it could provide nearly continuous beams for Nuclear Physics studies. The expected performances of this accelerator are given. The main components and the associated developments are mentioned. The characteristics of the associated detector requested to perform an original b-antib physics program are also listed. Finally, possible extensions offered by the accelerator complex are presented

  6. Integrated experimental platforms to study blast injuries: a bottom-up approach

    Bo, C.; Williams, A.; Rankin, S.; Proud, W. G.; Brown, K. A.


    We are developing experimental models of blast injury using data from live biological samples. An integrated research strategy is followed to study material and biological properties of cells, tissues and organs, that are subjected to dynamic and static pressures, relevant to those of battlefield blast. We have developed a confined Split Hopkinson Pressure Bar (SHPB) system, which allows cells, either in suspension or as a monolayer, to be subjected to compression waves with pressures on the order of a few MPa and durations of hundreds of microseconds. The chamber design enables recovery of biological samples for cellular and molecular analysis. The SHPB platform, coupled with Quasi-Static experiments, is used to determine stress-strain curves of soft biological tissues under compression at low, medium and high strain rates. Tissue samples are examined, using histological techniques, to study macro- and microscopic changes induced by compression waves. In addition, a shock tube enables application of single or multiple air blasts with pressures on the order of kPa and a few milliseconds duration; this platform was used for initial studies on mesenchymal stem cells responses to blast pressures.

  7. Depth to crustal magnetic bottom. Examples using aeromagnetic data across north Queensland, Australia

    Complete text of publication follows. A detailed study to estimate magnetic bottom depths under north Queensland has been made using the continent-wide high-resolution airborne total magnetic intensity (TMI) data of Australia (a source dataset for the World Digital Magnetic Anomaly Map, WDMAM). Magnetisation of the lithosphere is generally assumed not significant below the Moho crust/mantle boundary due to compositional changes. However, in regions of high temperatures in the lower crust, this bottom-depth of magnetisation may be significantly above the Moho depths due to temperatures in excess of the Curie-point isotherm of the dominant magnetic mineralogy. This study uses modelling of the azimuthally averaged log of the power spectrum of TMI data to determine bottom depths. Two methods are considered and compared: slope-fitting and automated fitting of full spectral data. Several issues in successfully using these methods have been addressed, such as magnetisation type, size of data window, location of spectral peak, sensitivities of the spectral parameters and the choice of optimisation algorithm. The TMI data have an initial grid resolution of 80 m, with an appropriate IGRF removed. These data are reduced to the pole, upward continued 1 km, sub-sampled to a 1 km grid spacing and a first order polynominal trend removed prior to the spectral analysis. Calculated magnetic bottom depths are compared both with published data on the depth to Moho and with other model interpretations of the area including heat flow modelling.

  8. Numerical study of natural melt convection in cylindrical cavity with hot walls and cold bottom sink

    Ahmanache Abdennacer


    Full Text Available Numerical study of natural convection heat transfer and fluid flow in cylindrical cavity with hot walls and cold sink is conducted. Calculations are performed in terms of the cavity aspect ratio, the heat exchanger length and the thermo physical properties expressed via the Prandtl number and the Rayleigh number. Results are presented in the form of isotherms, streamlines, average Nusselt number and average bulk temperature for a range of Rayleigh number up to 106. It is observed that Rayleigh number and heat exchanger length influences fluid flow and heat transfer, whereas the cavity aspect ratio has no significant effects.

  9. Thin elastic shells with variable thickness for lithospheric flexure of one-plate planets

    Beuthe, Mikael


    Planetary topography can either be modeled as a load supported by the lithosphere, or as a dynamical effect due to lithospheric flexure caused by mantle convection. In both cases the response of the lithosphere to external forces can be calculated with the theory of thin elastic plates or shells. On one-plate planets the spherical geometry of the lithospheric shell plays an important role in the flexure mechanism. So far the equations governing the deformations and stresses of a spherical shell have only been derived under the assumption of a shell of constant thickness. However local studies of gravity and topography data suggest large variations in the thickness of the lithosphere. In this article we obtain the scalar flexure equations governing the deformations of a thin spherical shell with variable thickness or variable Young's modulus. The resulting equations can be solved in succession, except for a system of two simultaneous equations, the solutions of which are the transverse deflection and an associ...

  10. Is the Asian lithosphere underthrusting beneath northeastern Tibetan Plateau? Insights from seismic receiver functions

    Shen, Xuzhang; Yuan, Xiaohui; Liu, Mian


    Whether or not the Asian lithosphere has underthrusted beneath the Tibetan Plateau is important for understanding the mechanisms of the plateau's growth. Using data from the permanent seismic stations in northeastern Tibetan Plateau, we studied seismic structures of the lithosphere and upper mantle across the plateau's northeastern margin using P and S receiver functions. The migrated P- and S-receiver function images reveal a thick crust and a diffuse lithosphere-asthenosphere boundary (LAB) beneath the Tibetan Plateau, contrasting sharply with the relatively thin crust and clear, sharp LAB under the bounding Asian blocks. The well-defined LAB under the Asian blocks tilts toward but does not extend significantly under the Tibetan Plateau; this is inconsistent with the model of Asian mantle lithosphere underthrusting beneath the Tibet Plateau. Instead, our results indicate limited, passive deformation of the bounding Asian lithosphere as it encounters the growing Tibetan Plateau.


    A. Ghomri


    Full Text Available This study aims to study the hydraulic jump controlled by threshold, moving in a channel profile 'U' bottomed rough for a single roughness E=5,63mm. Functional relations in dimensionless terms, linking the different characteristics of the projection, showing the effect of roughness of the bottom of the channel are obtained. The hydraulic jump is the primary means used by hydraulic structures to dissipate energy. This hydraulic jump is formed at the sharp transition from a supercritical flow a stream flow.


    A. Ghomri


    Full Text Available This study aims to study the hydraulic jump controlled by threshold, moving in a channel profile 'U' bottomed rough for a single roughness E=5,63mm. Functional relations in dimensionless terms, linking the different characteristics of the projection, showing the effect of roughness of the bottom of the channel are obtained. The hydraulic jump is the primary means used by hydraulic structures to dissipate energy. This hydraulic jump is formed at the sharp transition from a supercritical flow a stream flow.

  13. Depth to Curie temperature or bottom of the magnetic sources in the volcanic zone of la Réunion hot spot

    Gailler, Lydie-Sarah; Lénat, Jean-François; Blakely, Richard J.


    We present an innovative study to generalize Curie Point Depth (CPD) determinations at the scale of oceanic volcanic islands, an approach which has previously focused largely on continental areas. In order to determine the validity of this technique in oceanic environments, we first tested the approach on sets of sea-floor-spreading anomalies. Assuming that magnetic anomalies are concentrated within the oceanic crust and uppermost mantle, the Curie depth should deepen as oceanic lithosphere increases in age and thickness away from spreading centers. The calculated depths to the magnetic bottom are in agreement with this general pattern. On the basis of this test, we then applied the method to La Réunion Island and surrounding oceanic lithosphere. The calculated extent of magnetic sources lies at depths between 10 and 30 km and exhibits a complex topography, presumably caused by a combination of various magmatic and tectonic lithospheric structures. These calculations indicate that magnetic sources extend well below the crust-mantle interface at this location. To the first order, the bottom of the magnetic surface shallows beneath Réunion and Mauritius Islands due to the thermal effect of the hot spot, and deepens away from La Réunion edifice. On the scale of the Mascarene Basin, several discontinuities in the CPD correlate well with major fracture zones.

  14. Ppercase(melcor) sensitivity studies for a low-pressure, short-term station blackout at the Peach Bottom plant

    This paper summarizes the results of analyses performed to assess the effect of a variety of design parameters and operational procedures on a station blackout severe accident at the Peach Bottom Atomic Power Station. The severe-accident ppercase(melcor) code, version 1.8.1 was used in these analyses. The following sensitivity studies were completed: effect of the automatic depressurization system actuation timing on the accident progression; effect of fuel and cladding porosities on vessel failure and containment failure times; effect of several parameters on the amount of in-vessel steel ejected into the cavity after vessel failure; effect of different parameters on vessel penetration failure time; vessel failure timing; and lower plenum shroud and core shroud temperatures. These sensitivity studies provided valuable insights into the ppercase(melcor) code behavior and into the progression of this severe accident. The most significant results are: (a) the optimum steam cooling of the core is accomplished when the automatic depressurization system is actuated when the core water level is at one-third of the active core height, delaying vessel failure by minutes and containment failure by hours, (b) vessel failure is significantly delayed (by 2 h) when lower-plenum debris quenching is included in the model, and (c) the core shroud melts during this transient. ((orig.))

  15. Search for the supersymmetric partner of bottom quark at DO at Tevatron. Studies on missing transverse energy

    Supersymmetry, the extension of the Standard Model of particle physics, is searched for, by trying to observe the supersymmetric partner of the bottom quark (b-bar). This search is performed by using events with a final state comprising 2 coplanar b-quark jets and missing transverse energy and coming from a sample of 992 pb-1 of data collected by the D0 detector at the Tevatron, the Fermilab pp-bar collider. The absence of an excess of events in comparison to Standard Model expectations leads to exclude sb masses up to 201 GeV and neutralino masses up to 94 GeV. The missing transverse energy has been studied carefully under 2 points of view, because of its fundamental role in this search. First, at the level of the trigger system which allows the online selection candidate events, and then during the process Z → νν + jets that is an important background noise and in which the transverse momentum of Z turns into missing energy because of the no-detection of the neutrinos. (author)

  16. Search for supersymmetric partner of bottom quark at d0 at Tevatron. Studies on missing transverse energy

    Calvet, Samuel Pierre; /Marseille, CPPM


    Supersymmetry, extension of the Standard Model of Particle Physics (SM), is searched for by trying to observe the supersymmetric partner of bottom quark ({tilde b}). This search is performed using events with a final state comprising two acoplanar b-quark jets and missing transverse energy (MET) and coming from a sample of 992 pb{sup -1} of data collected by the D0 detector at the Tevatron, the Fermilab p{bar p} collider. The absence of an excess of events in comparison to MS expectations leads to exclude sb masses up to 201 GeV, neutralino masses up to 94 GeV. The MET has been studied under two points of view, because of its fundamental role in this search. First, at the level of the trigger system which allows the online selection candidate events, and then, within the framework of the ALPGEN generator, the simulation of the Z boson transverse momentum which appears as MET when the Z boson decays into neutrino.

  17. EDS coal liquefaction process development, Phase V. Engineering design study of an EDS Illinois bottoms fired hybrid boiler



    This interim report documents work carried out by Combustion Engineering, Inc. under a contract to Exxon Research and Engineering Company and was prepared by Combustion Engineering, Inc. This report is the second of two reports by Combustion Engineering, Inc. on the predevelopment phase of the Hybrid Boiler program and covers the results of an engineering design study of a Hybrid Boiler firing the vacuum distillation residue (vacuum bottoms) derived from processing Illinois No. 6 coal in the EDS Coal Liquefaction Process. The function of the Hybrid Boiler is to heat the coal slurry feed for an EDS coal liquefaction plant by a process coil in the convection section and to generate high pressure steam in the radiant section. The Hybrid Boiler design developed in this phase of the program is based on the results of a laboratory characterization program (reported in EDS Interim Report FE-2893-112), on Combustion Engineering, Inc.'s extensive experience as a designer and supplier of steam generating equipment, and on Exxon Research and Engineering Co.'s experience with the design and operation of process heaters.

  18. Seismic Structure of Shallow Lithosphere at Locations of Distinctive Seafloor Spreading /

    Henig, Ashlee Shae


    Multichannel Seismic (MCS) Refraction and Reflection analyses are used to determine the structure of the upper 1-2 km of lithosphere at two distinct seafloor spreading regions at 1) the Atlantis Massif Oceanic Core Complex (OCC) at 30°N on the Mid-Atlantic Ridge (MAR), and 2) the southward propagating tip and pseudofault regions of the Central Lau Spreading Center (CLSC) in the Lau Backarc Basin. The Synthetic Ocean Bottom Experiment (SOBE) downward continuation technique is employed to incre...

  19. Lithospheric Architecture, Heterogenities, Instabilities, Melting - insight form numerical modelling

    Gorczyk, Weronika; Hobbs, Bruce; Ord, Alison; Gessner, Klaus; Gerya, Taras V.


    The seismological structure of the Earth's lithosphere is identified to be strongly heterogeneous in terms of thermal and rheological structures. Lithospheric discontinuities (sharp changes in the thermal and/or compositional structure) are thought to be long lived and are mostly correlated with major tectonic boundaries that commonly have been reactivated and which subsequently are the foci of magma intrusion and major mineralization. Resent studies have shown that mantle metasomatism is also controlled by such boundaries. This paper explores the control that lithospheric heterogeneity exerts on the thermal and chemical evolution during deformation subsequent to the development of the heterogeneity. We explore the behaviour of the rheological heterogeneous lithosphere in a compressional regime. The occurrence of such variations may be caused for instance by amalgamation of micro-continents such as is thought to be characteristic of the Yilgarn, Western Australia or South Africa. Theses micro-continents, due to diverse histories may be characterised by various thermal and rheological structures. The models are simplistic but illustrate the basic principles. The code used in this study is based on a conservative finite-difference, multi-grid, marker in cell method. Devolatilisation reactions and melting can affect the physical properties of rocks and are incorporated in a self-consistent manner. We use a petrological-thermomechanical modelling approach with all rock properties including mechanical properties calculated in the Lagrangian scheme for rock markers at every time step based on Gibbs free energy minimization as a function of the local pressure, temperature and rock composition. The results illustrate that initial structural complexity is necessary for and has a dramatic effect on fault and development, the growth of deep basins, core complex formation, melting and devolatilisation within the lithosphere. The horizontal and vertical variation in plastic

  20. The lithosphere-asthenosphere Italy and surroundings

    Panza, G F; Chimera, G; Pontevivo, A; Raykova, R


    The velocity-depth distribution of the lithosphere-asthenosphere in the Italian region and surroundings is imaged, with a lateral resolution of about 100 km, by surface wave velocity tomography and non-linear inversion. Maps of the Moho depth, of the thickness of the lithosphere and of the shear-wave velocities, down to depths of 200 km and more, are constructed. A mantle wedge, identified in the uppermost mantle along the Apennines and the Calabrian Arc, underlies the principal recent volcanoes, and partial melting can be relevant in this part of the uppermost mantle. In Calabria a lithospheric doubling is seen, in connection with the subduction of the Ionian lithosphere. The asthenosphere is shallow in the Southern Tyrrhenian Sea. High velocity bodies, cutting the asthenosphere, outline the Adria-lonian subduction in the Tyrrhenian Sea and the deep-reaching lithospheric root in the Western Alps. Less deep lithospheric roots are seen in the Central Apennines. The lithosphere-asthenosphere properties delineat...

  1. The lithosphere-asthenosphere: Italy and surroundings

    The velocity-depth distribution of the lithosphere-asthenosphere in the Italian region and surroundings is imaged, with a lateral resolution of about 100 km, by surface wave velocity tomography and non-linear inversion. Maps of the Moho depth, of the thickness of the lithosphere and of the shear-wave velocities, down to depths of 200 km and more, are constructed. A mantle wedge, identified in the uppermost mantle along the Apennines and the Calabrian Arc, underlies the principal recent volcanoes, and partial melting can be relevant in this part of the uppermost mantle. In Calabria a lithospheric doubling is seen, in connection with the subduction of the Ionian lithosphere. The asthenosphere is shallow in the Southern Tyrrhenian Sea. High velocity bodies, cutting the asthenosphere, outline the Adria-lonian subduction in the Tyrrhenian Sea and the deep-reaching lithospheric root in the Western Alps. Less deep lithospheric roots are seen in the Central Apennines. The lithosphere-asthenosphere properties delineate a differentiation between the northern and the southern sectors of the Adriatic Sea, likely attesting the fragmentation of Adria. (author)

  2. Global distribution of the lithosphere-asthenosphere boundary: a new look

    V. M. Hamza


    Full Text Available New global maps of the depth to the boundary between the lithosphere and the asthenosphere are presented. The maps are based on updated global databases for heat flow and crustal structure. For continental regions the estimates of lithospheric thickness are based on determinations of subcrustal heat flow, after corrections for contributions of radiogenic heat in crustal layers. For oceanic regions the estimates of lithospheric thickness are based on the newly proposed finite half-space (FHS model. Unlike the half-space cooling (HSC and the Plate models the FHS model takes into account effects of buffered solidification at the lower boundary of the lithosphere and assumes that vertical domain for downward growth of boundary layer have an asymptotic limit. Results of numerical simulations reveal that theoretical values derived from FHS model provide vastly improved fits to observational data for heat flow and bathymetry than can be achieved with HSC and Plate models. Also, the data fits are valid for the entire age range of the oceanic lithosphere. Hence estimates of depths to lithosphere – asthenosphere boundary (LAB based on FHS model, are believed to provide more reliable estimates than those reported in previous thermal models. The global maps of depths to LAB derived in the present work reveal several features in regional variations of lithosphere thicknesses that have not been identified in earlier studies. For example, regions of ocean floor with ages less than 55 Ma are characterized by relatively rapid thickening of the lithosphere. Also there is better resolution in mapping the transition from oceanic to continental lithosphere, as most of the latter ones are characterized by lithospheric thickness greater than 150 km. As expected the plate spreading centers in oceanic regions as well as areas of recent magmatic activity in continental regions are characterized by relatively thin lithosphere, with LAB depths of less than 50 km. On the

  3. Global distribution of the lithosphere-asthenosphere boundary: a new look

    V. M. Hamza


    Full Text Available New global maps of the depth to the boundary between the lithosphere and the asthenosphere are presented. The maps are based on updated global databases for heat flow and crustal structure. For continental regions the estimates of lithospheric thickness are based on determinations of subcrustal heat flow, after corrections for contributions of radiogenic heat in crustal layers. For oceanic regions the estimates of lithospheric thickness are based on the newly proposed finite half-space (FHS model. Unlike the half-space cooling (HSC and the plate models the FHS model takes into account effects of buffered solidification at the lower boundary of the lithosphere and assumes that the vertical domain for downward growth of the boundary layer have an asymptotic limit. Results of numerical simulations reveal that theoretical values derived from the FHS model provide vastly improved fits to observational data for heat flow and bathymetry than can be achieved with HSC and plate models. Also, the data fits are valid for the entire age range of the oceanic lithosphere. Hence estimates of depths to lithosphere- asthenosphere boundary (LAB based on the FHS model are believed to provide more reliable estimates than those reported in previous thermal models.

    The global maps of depths to LAB derived in the present work reveal several features in regional variations of lithosphere thicknesses that have not been identified in earlier studies. For example, regions of ocean floor with ages less than 55 Ma are characterized by relatively rapid thickening of the lithosphere. Also there is better resolution in mapping the transition from oceanic to continental lithosphere, as most of the latter ones are characterized by lithospheric thickness greater than 150 km. As expected the plate spreading centers in oceanic regions as well as areas of recent magmatic activity in continental regions are characterized by relatively thin lithosphere, with LAB depths of

  4. Deformation of island-arc lithosphere due to steady plate subduction

    Fukahata, Yukitoshi; Matsu'ura, Mitsuhiro


    Steady plate subduction elastically brings about permanent lithospheric deformation in island arcs, though this effect has been neglected in most studies based on elastic dislocation theory. We investigate the characteristics of the permanent lithospheric deformation using a kinematic model, in which steady slip motion is given along a plate interface in the elastic lithosphere overlying the viscoelastic asthenosphere under gravity. As a rule of thumb, long-term lithospheric deformation can be understood as a bending of an elastic plate floating on non-viscous fluid, because the asthenosphere behaves like water on the long term. The steady slip below the lithosphere-asthenosphere boundary does not contribute to long-term lithospheric deformation. Hence, the key parameters that control the lithospheric deformation are only the thickness of the lithosphere and the geometry of the plate interface. Slip on a plate interface generally causes substantial vertical displacement, and gravity always tries to retrieve the original gravitational equilibrium. For a curved plate interface gravity causes convex upward bending of the island-arc lithosphere, while for a planar plate interface gravity causes convex downward bending. Larger curvature and thicker lithosphere generally results in larger deformation. When the curvature changes along the plate interface, internal deformation is also involved intrinsically, which modifies the deformation field due to gravity. Because the plate interface generally has some curvature, at least near the trench, convex upward bending of the island-arc lithosphere, which involves uplift of island-arc and subsidence around the trench, is always realized. On the other hand, the deformation field of the island-arc lithosphere sensitively depends on lithospheric thickness and plate interface geometry. These characteristics obtained by the numerical simulation are consistent with observed topography and free-air gravity anomalies in subduction

  5. A preliminary study on the occurrence of Dermatophyles and other keratinophilic fungi in bottom sediments of rivers and lakes

    Krzysztof Ulfig


    Sam pies of bottom sediments from the Rivers Nacyna, Ruda and from an eutrophic reservoir holding cooling waters were examined for dermatophytes and correlated fungi. The species isolated were: Trichophyton terrestre complex, T. ajelloi (and its perfect form Anhroderma uncinatum). pathogenic strains of T. mentagrophytes and Microsporum cookei; also isolated were five species of the genus Chrysosporium.

  6. A preliminary study on the occurrence of Dermatophyles and other keratinophilic fungi in bottom sediments of rivers and lakes

    Krzysztof Ulfig


    Full Text Available Sam pies of bottom sediments from the Rivers Nacyna, Ruda and from an eutrophic reservoir holding cooling waters were examined for dermatophytes and correlated fungi. The species isolated were: Trichophyton terrestre complex, T. ajelloi (and its perfect form Anhroderma uncinatum. pathogenic strains of T. mentagrophytes and Microsporum cookei; also isolated were five species of the genus Chrysosporium.

  7. The Roles of Feature-Specific Task Set and Bottom-Up Salience in Attentional Capture: An ERP Study

    Eimer, Martin; Kiss, Monika; Press, Clare; Sauter, Disa


    We investigated the roles of top-down task set and bottom-up stimulus salience for feature-specific attentional capture. Spatially nonpredictive cues preceded search arrays that included a color-defined target. For target-color singleton cues, behavioral spatial cueing effects were accompanied by cue-induced N2pc components, indicative of…

  8. Bottom-up engineering of biological systems through standard bricks: a modularity study on basic parts and devices.

    Lorenzo Pasotti

    Full Text Available BACKGROUND: Modularity is a crucial issue in the engineering world, as it enables engineers to achieve predictable outcomes when different components are interconnected. Synthetic Biology aims to apply key concepts of engineering to design and construct new biological systems that exhibit a predictable behaviour. Even if physical and measurement standards have been recently proposed to facilitate the assembly and characterization of biological components, real modularity is still a major research issue. The success of the bottom-up approach strictly depends on the clear definition of the limits in which biological functions can be predictable. RESULTS: The modularity of transcription-based biological components has been investigated in several conditions. First, the activity of a set of promoters was quantified in Escherichia coli via different measurement systems (i.e., different plasmids, reporter genes, ribosome binding sites relative to an in vivo reference promoter. Second, promoter activity variation was measured when two independent gene expression cassettes were assembled in the same system. Third, the interchangeability of input modules (a set of constitutive promoters and two regulated promoters connected to a fixed output device (a logic inverter expressing GFP was evaluated. The three input modules provide tunable transcriptional signals that drive the output device. If modularity persists, identical transcriptional signals trigger identical GFP outputs. To verify this, all the input devices were individually characterized and then the input-output characteristic of the logic inverter was derived in the different configurations. CONCLUSIONS: Promoters activities (referred to a standard promoter can vary when they are measured via different reporter devices (up to 22%, when they are used within a two-expression-cassette system (up to 35% and when they drive another device in a functionally interconnected circuit (up to 44%. This paper

  9. Independent effects of bottom-up temporal expectancy and top-down spatial attention. An audiovisual study using rhythmic cueing.

    Alexander eJones


    Full Text Available Selective attention to a spatial location has shown enhance perception and facilitate behaviour for events at attended locations. However, selection relies not only on where but also when an event occurs. Recently, interest has turned to how intrinsic neural oscillations in the brain entrain to rhythms in our environment, and, stimuli appearing in or out of synch with a rhythm have shown to modulate perception and performance. Temporal expectations created by rhythms and spatial attention are two processes which have independently shown to affect stimulus processing but it remains largely unknown how, and if, they interact. In four separate tasks, this study investigated the effects of voluntary spatial attention and bottom-up temporal expectations created by rhythms in both unimodal and crossmodal conditions. In each task the participant used an informative cue, either colour or pitch, to direct their covert spatial attention to the left or right, and respond as quickly as possible to a target. The lateralized target (visual or auditory was then presented at the attended or unattended side. Importantly, although not task relevant, the cue was a rhythm of either flashes or beeps. The target was presented in or out of sync (early or late with the rhythmic cue. The results showed participants were faster responding to spatially attended compared to unattended targets in all tasks. Moreover, there was an effect of rhythmic cueing upon response times in both unimodal and crossmodal conditions. Responses were faster to targets presented in sync with the rhythm compared to when they appeared too early in both crossmodal tasks. That is, rhythmic stimuli in one modality influenced the temporal expectancy in the other modality, suggesting temporal expectancies created by rhythms are crossmodal. Interestingly, there was no interaction between top-down spatial attention and rhythmic cueing in any task suggesting these two processes largely influenced

  10. Satellite-derived geoid for the estimation of lithospheric cooling and basal heat flux anomalies over the northern Indian Ocean lithosphere

    S Rajesh; T J Majumdar


    The northern Indian Ocean consists of older Bay of Bengal (BOB) oceanic lithosphere with numerous intra-plate loads; whereas, contrasting elements like active Mid-Ocean ridge divergence and slow spreading ridges are present in the relatively younger (<60 Ma) Arabian Sea oceanic lithosphere. The mechanism of lithospheric cooling of young age oceanic lithosphere from the moderately active and slow spreading Carlsberg Ridge is analysed by considering the hypothesis of near lithospheric convective action or whole upper mantle convection. We addressed these issues by studying the marine geoid at different spatial wavelengths and retrieved and compared their lithospheric cooling signatures, plate spreading and distribution of mass and heat anomalies along with seismicity, bathymetry, gravity and isochron age data. Results show that progressive cooling of young-aged oceanic lithosphere from the Mid-Ocean Carlsberg Ridge is because of conductive cooling and those signals are retrieved in the shorter wavelength band (111 < < 1900 km) of constrained residual geoid with mass anomaly sources near to sublithospheric. This shows steadiness in the geoid anomaly decay rate (∼–0.1 m/Ma), consistency in the growth of thermal boundary layer and progressive fall of basal temperature and heat flux (900–300 K and 100–18 mW m−2) with increase of lithospheric age. The above observations are attributed to the fact that the advective–convective action beneath the Mid-Ocean Carlsberg Ridge is driven by the basal temperature gradient between the lithosphere and the near lithospheric low viscose thin layer. But, for the case of old-aged oceanic lithosphere in the BOB, the residual geoid anomaly cooling signals are not prominently seen in the same band as that of the Arabian Sea because of the Ninetyeast Ridge magmatism. However, its cooling anomaly signatures are retrieved at relatively higher band (1335 ≤ ≤ 3081 km) having erratic geoid decay rates (–0.3 to 0.2 m/Ma) owing

  11. The evolution of the earth's lithosphere

    The key and the well established basis for our present understanding of the evolution of the earth's lithosphere is the continous creation of new oceanic lithosphere in the mid oceanic ridge system. Paleomagnetic evidence and the concept of global plate tectonics permit a quantitative reconstruction of the kinematic history of the lithosphere for the past 200 m.y. This leads to continent configurations very similar to those proposed by A. Wegener. Plate tectonic processes can be traced back until Precambrian times. Before that, due to the generally higher temperature of the earth, the evolution was apparently governed by different processes. Thermal convection and gavitational instabilities are considered as driving forces for the lithosphere. (orig.)

  12. Imaging Canary Island hotspot material beneath the lithosphere of Morocco and southern Spain

    Miller, Meghan S.; O'Driscoll, Leland J.; Butcher, Amber J.; Thomas, Christine


    The westernmost Mediterranean has developed into its present day tectonic configuration as a result of complex interactions between late stage subduction of the Neo-Tethys Ocean, continental collision of Africa and Eurasia, and the Canary Island mantle plume. This study utilizes S receiver functions (SRFs) from over 360 broadband seismic stations to seismically image the lithosphere and uppermost mantle from southern Spain through Morocco and the Canary Islands. The lithospheric thickness ranges from ∼65 km beneath the Atlas Mountains and the active volcanic islands to over ∼210 km beneath the cratonic lithosphere in southern Morocco. The common conversion point (CCP) volume of the SRFs indicates that thinned lithosphere extends from beneath the Canary Islands offshore southwestern Morocco, to beneath the continental lithosphere of the Atlas Mountains, and then thickens abruptly at the West African craton. Beneath thin lithosphere between the Canary hot spot and southern Spain, including below the Atlas Mountains and the Alboran Sea, there are distinct pockets of low velocity material, as inferred from high amplitude positive, sub-lithospheric conversions in the SRFs. These regions of low seismic velocity at the base of the lithosphere extend beneath the areas of Pliocene-Quaternary magmatism, which has been linked to a Canary hotspot source via geochemical signatures. However, we find that this volume of low velocity material is discontinuous along strike and occurs only in areas of recent volcanism and where asthenospheric mantle flow is identified with shear wave splitting analyses. We propose that the low velocity structure beneath the lithosphere is material flowing sub-horizontally northeastwards beneath Morocco from the tilted Canary Island plume, and the small, localized volcanoes are the result of small-scale upwellings from this material.

  13. The structure of the Ionian lithosphere

    Carr, M. H.; Clow, G. D.


    Exploratory work on the structure of the Ionian lithosphere is reported. The approach is to examine temperature profiles within the lithosphere that result from different distributions of sulfur and silicates and different conductive heat fluxes, then compare such profiles with observations in the expectation that only a limited set of the profiles are possible. In this preliminary work some rather simplistic assumptions were taken and the report should be viewed more as a demonstration of a method rather than a presentation of results.

  14. Comparative study of ageing, heat treatment and accelerated carbonation for stabilization of municipal solid waste incineration bottom ash in view of reducing regulated heavy metal/metalloid leaching

    Santos, Rafael; Mertens, Gilles; Salman, Muhammad; Cizer, Özlem; Gerven, Tom Van


    This study compared the performance of four different approaches for stabilization of regulated heavy metal and metalloid leaching from municipal solid waste incineration bottom ash (MSWI-BA): (i) short term (three months) heap ageing, (ii) heat treatment, (iii) accelerated moist carbonation, and (iv) accelerated pressurized slurry carbonation. Two distinct types of MSWI-BA were tested in this study: one originating from a moving-grate furnace incineration operation treating exclusively house...

  15. A temporal and spatial study of invertebrate communities associated with hard-bottom habitats in the South Atlantic Bight

    Wenner, E. L.; Hinde, P.; Knott, D. M; Van Dolah, R. F.


    Species composition, biomass, density, and diversity of benthic invertebrates from six bard-bottom areas were evaluated. Seasonal collections using a dredge, trawl, and suction and grab samplers yielded 432, 525, and 845 taxa, respectively. Based on collections wltb the different gear types, species composition of invertebrates was found to change bathymetrically. Inner- and mlddle-shelf sites were more similar to each other in terms of invertebrate species composition than they were to outer...

  16. Matching Lithosphere velocity changes to the GOCE gravity signal

    Braitenberg, Carla


    Authors: Carla Braitenberg, Patrizia Mariani, Alberto Pastorutti Department of Mathematics and Geosciences, University of Trieste Via Weiss 1, 34100 Trieste Seismic tomography models result in 3D velocity models of lithosphere and sublithospheric mantle, which are due to mineralogic compositional changes and variations in the thermal gradient. The assignment of density is non-univocal and can lead to inverted density changes with respect to velocity changes, depending on composition and temperature. Velocity changes due to temperature result in a proportional density change, whereas changes due to compositional changes and age of the lithosphere can lead to density changes of inverted sign. The relation between velocity and density implies changes in the lithosphere rigidity. We analyze the GOCE gradient fields and the velocity models jointly, making simulations on thermal and compositional density changes, using the velocity models as constraint on lithosphere geometry. The correlations are enhanced by applying geodynamic plate reconstructions to the GOCE gravity field and the tomography models which places today's observed fields at the Gondwana pre-breakup position. We find that the lithosphere geometry is a controlling factor on the overlying geologic elements, defining the regions where rifting and collision alternate and repeat through time. The study is carried out globally, with focus on the conjugate margins of the African and South American continents. The background for the study can be found in the following publications where the techniques which have been used are described: Braitenberg, C., Mariani, P. and De Min, A. (2013). The European Alps and nearby orogenic belts sensed by GOCE, Boll. Bollettino di Geofisica Teorica ed Applicata, 54(4), 321-334. doi:10.4430/bgta0105---- Braitenberg, C. and Mariani, P. (2015). Geological implications from complete Gondwana GOCE-products reconstructions and link to lithospheric roots. Proceedings of 5th

  17. Experimental Study of Transient Thermal Convection Following a Catastrophic Lithospheric Overturn: Applications to the Tectonic Style, Thermal Evolution and Topography of Venus

    Robin, C. M.; Thayalan, V.; Jellinek, A. M.


    The coexistence of dynamically supported highlands and coronae is difficult to reconcile with models of Venusian mantle convection. Coronae are well explained by transient discrete mantle upwellings (thermals), which are characteristic of weak cooling due to the stagnant lid style of convection expected in one-plate planets. In contrast, topographic highlands such as Atla, Beta and Themis Regio are better explained by persistent axisymmetric plumes more typical of the Earth's mantle, which is cooled strongly by subduction and plate tectonics (i.e. mobile lid convection). From the observed crater distribution, it is also inferred that the surface of Venus has a mean age of ~700 Ma. One explanation for this young surface age is that it is a result of a recent and catastrophic resurfacing event. We test a hypothesis that the occurrence of highlands and coronae are a consequence of the style of transient mantle convection driven by sudden overturn of the lithosphere. A series of stagnant lid and mobile lid convection control experiments at thermal equilibrium under conditions appropriate for Venus' mantle are first performed. The mobile lid regime is achieved using a conveyor belt at the cold boundary. Next, we investigate the thermal and temporal characteristics of transitions from steady-state stagnant lid to mobile lid, and from mobile lid to stagnant lid regimes. Using a combination of time-lapse video, shadowgraphs and analyses of time-series of temperature and heat flux data, we identify the qualitative changes in convective regime, the quantitative changes in the heat transfer characteristics of the flows, and the characteristic time scales over which transitions occur. Three regimes are observed: (i) steady-state stagnant lid mode characterized by time-dependent hot (rising) and cold (sinking) thermals; (ii) steady-state mobile-lid mode characterized by active stirring and long-lived plumes; and (iii) a transient mixed mode characterized by the coexistence of

  18. Bottom sediments of Ypacarai Lake

    Bottom sediments of Ypacarai Lake was investigated with XRF and Mossbauer techniques. The lake of about 120 Km2, is a shallow one, medium deep of about 1.8m. In addition to its use for recreation, its basin has a wide area of influence and of economical significance. Bottom sediments play an important role in the overall distribution of trace elements in the aquatic system and act as a sink for metals. Bottom samples were taken from 5 different sampling stations, selected according to the morphology and population sites in the shore. The concentration of toxic metals was found to be low and no negative ecological impact should be expected. The main metallic ion component is iron (1.69%). Mossbauer studies showed this element appears as Fe+3 and no Fe+2 was detected. It is here suggested that Fe+3 acts as the limiting element which controls eutrophication process

  19. Water in the Cratonic Mantle Lithosphere

    Peslier, A. H.


    The fact that Archean and Proterozoic cratons are underlain by the thickest (>200 km) lithosphere on Earth has always puzzled scientists because the dynamic convection of the surrounding asthenosphere would be expected to delaminate and erode these mantle lithospheric "keels" over time. Although density and temperature of the cratonic lithosphere certainly play a role in its strength and longevity, the role of water has only been recently addressed with data on actual mantle samples. Water in mantle lithologies (primarily peridotites and pyroxenites) is mainly stored in nominally anhydrous minerals (olivine, pyroxene, garnet) where it is incorporated as hydrogen bonded to structural oxygen in lattice defects. The property of hydrolytic weakening of olivine [4] has generated the hypothesis that olivine, the main mineral of the upper mantle, may be dehydrated in cratonic mantle lithospheres, contributing to its strength. This presentation will review the distribution of water concentrations in four cratonic lithospheres. The distribution of water contents in olivine from peridotite xenoliths found in kimberlites is different in each craton (Figure 1). The range of water contents of olivine, pyroxene and garnet at each xenolith location appears linked to local metasomatic events, some of which occurred later then the Archean and Proterozoic when these peridotites initially formed via melting. Although the low olivine water contents ( 6 GPa at the base of the Kaapvaal cratonic lithosphere may contribute to its strength, and prevent its delamination, the wide range of those from Siberian xenoliths is not compatible with providing a high enough viscosity contrast with the asthenophere. The water content in olivine inclusions from Siberian diamonds, on the other hand, have systematically low water contents (water contents. The olivine inclusions, however, may have been protected from metasomatism by their host diamond and record the overall low olivine water content of

  20. Diagnostic study, design and implementation of an integrated model of care in France: a bottom-up process with continuous leadership

    de Stampa, Matthieu; Vedel, Isabelle; Mauriat, Claire; Bagaragaza, Emmanuel; Routelous, Christelle; Bergman, Howard; Lapointe, Liette; Cassou, Bernard; Ankri, Joel; Henrard, Jean-Claude


    Background: Sustaining integrated care is difficult, in large part because of problems encountered securing the participation of health care and social service professionals and, in particular, general practitioners (GPs). Purpose: To present an innovative bottom-up and pragmatic strategy used to implement a new integrated care model in France for community-dwelling elderly people with complex needs.Results: In the first step, a diagnostic study was conducted with face-to-face interviews to g...

  1. Ecology of phasmids (phasmatodea) in a moist neotropical forest: a study on life history, host-range and bottom-up versus top-down regulation

    Berger, Jürgen


    Herbivory is discussed as a key agent in maintaining dynamics and stability of tropical forested ecosystems. Accordingly increasing attention has been paid to the factors that structure tropical herbivore communities. The aim of this study was (1) to describe diversity, density, distribution and host range of the phasmid community (Phasmatodea) of a moist neotropical forest in Panamá, and (2) to experimentally assess bottom-up and top-down factors that may regulate populations of the phasmid ...

  2. Hyperextension of continental lithospheric mantle to oceanic-like lithosphere: the record of late gabbros in the Ronda subcontinental lithospheric mantle section (Betic Cordillera, S-Spain)

    Hidas, Karoly; Garrido, Carlos; Targuisti, Kamal; Padron-Navarta, Jose Alberto; Tommasi, Andrea; Marchesi, Claudio; Konc, Zoltan; Varas-Reus, Maria Isabel; Acosta Vigil, Antonio


    Rupturing continents is a primary player in plate tectonic cycle thus longevity, stability, evolution and breakup of subcontinental lithosphere belongs for a long time to a class of basic geological problems among processes that shape the view of our Earth. An emerging body of evidences - based on mainly geophysical and structural studies - demonstrates that the western Mediterranean and its back-arc basins, such as the Alborán Domain, are hyperextended to an oceanic-like lithosphere. Formation of gabbroic melts in the late ductile history of the Ronda Peridotite (S-Spain) - the largest (ca. 300 km2) outcrop of subcontinental lithospheric mantle massifs on Earth - also attests for the extreme thinning of the continental lithosphere that started in early Miocene times. In the Ronda Peridotite, discordant gabbroic veins and their host plagioclase lherzolite, as well as gabbroic patches in dunite were collected in the youngest plagioclase tectonite domains of the Ojén and Ronda massifs, respectively. In Ojén, gabbro occurs as 1-3 centimeter wide discordant veins and dikes that crosscut the plagioclase tectonite foliation at high angle (60°). Within the veins cm-scale igneous plagioclase and clinopyroxene grains show a shape preferred orientation and grow oriented, subparallel to the trace of high temperature host peridotite foliation and oblique to the trend of the vein. In contrast to Ojén, mafic melts in the Ronda massif crystallized along subcentimeter wide anastomozing veins and they often form segregated interstitial melt accumulations in the host dunite composed of plagioclase, clinopyroxene and amphibole. Despite the differences in petrography and major element composition, the identical shape of calculated REE patterns of liquid in equilibrium with clinopyroxenes indicates that the percolating melt in Ronda and Ojén shares a common source. However, unlike gabbros from the oceanic lithosphere that shows clinopyroxene in equilibrium with LREE-depleted MORB

  3. Offshore Southern California lithospheric velocity structure from noise cross-correlation functions

    Bowden, D. C.; Kohler, M. D.; Tsai, V. C.; Weeraratne, D. S.


    A new shear wave velocity model offshore Southern California is presented that images plate boundary deformation including both thickening and thinning of the crustal and mantle lithosphere at the westernmost edge of the North American continent. The Asthenospheric and Lithospheric Broadband Architecture from the California Offshore Region Experiment (ALBACORE) ocean bottom seismometer array, together with 65 stations of the onshore Southern California Seismic Network, is used to measure ambient noise correlation functions and Rayleigh wave dispersion curves which are inverted for 3-D shear wave velocities. The resulting velocity model defines the transition from continental lithosphere to oceanic, illuminating the complex history and deformation in the region. A transition to the present-day strike-slip regime between the Pacific and North American Plates resulted in broad deformation and capture of the now >200 km wide continental shelf. Our velocity model suggests the persistence of the uppermost mantle volcanic processes associated with East Pacific Rise spreading adjacent to the Patton Escarpment, which marks the former subduction of Farallon Plate underneath North America. The most prominent of these seismic structures is a low-velocity anomaly underlying the San Juan Seamount, suggesting ponding of magma at the base of the crust, resulting in thickening and ongoing adjustment of the lithosphere due to the localized loading. The velocity model also provides a robust framework for future earthquake location determinations and ground-shaking simulations for risk estimates.



    The pressure gradient of the lithosphere is a key to explaining various geological processes, and varies also in time and space similar to the geothermal gradient. In this paper a correlation formula of geothermal gradients and pressure gradients was built with the thermocomprestion coefficients. Based on this formula, the article has studied the relation between the pressure gradients and the geothermal gradients in the lithosphere, and the results indicate that the pressure gradient in the lithosphere is nonlinear, and its minimum value is the lithostatic gradient, and that the pressure gradient of the lithosphere will increase obviously with the contribution of both geothermal and gravity, and could be twice times more than the lithostatic gradient.

  5. Peridotite-melt interaction: A key point for the destruction of cratonic lithospheric mantle

    ZHANG HongFu


    This paper presents an overview of recent studies dealing with different ages of mantle peridotitic xenoliths and xenocrysts from the North China Craton, with aim to provide new ideas for further study on the destruction of the North China Craton. Re-Os isotopic studies suggest that the lithospheric mantle of the North China Craton is of Archean age prior to its thinning. The key reason why such a low density and highly refractory Archean lithospheric mantle would be thinned is changes in composition, thermal regime, and physical properties of the lithospheric mantle due to interaction of peridotites with melts of different origins. Inward subducUon of circum craton plates and collision with the North China Craton provided not only the driving force for the destruction of the craton, but also continuous melts derived from partial melting of subducted continental or oceanic crustal materials that resulted in the compositional change of the lithospheric mantle. Regional thermal anomaly at ca. 120 Ma led to the melting of highly modified iithospheric mantle. At the same time or subsequently lithospheric extension and asthenospheric upwelling further reinforced the melting and thinning of the lithospheric mantle. Therefore, the destruction and thinning of the North China Craton is a combined result of peridotite-melt interaction (addition of volatile), enhanced regional thermal anomaly (temperature increase) and lithospheric extension (decompression). Such a complex geological process finally produced a "mixed" lithospheric mantle of highly chemical heterogeneity during the Mesozoic and Cenozoic. It also resulted in significant difference in the composition of mantle peridotitic xenoliths between different regions and times.

  6. Thick plate flexure. [for lithospheric models of Mars and earth

    Comer, R. P.


    Analytical expressions are derived for the displacements and stresses due to loading of a floating, uniform, elastic plate of arbitrary thickness by a plane or axisymmetric harmonic load. The solution is exact except for assumptions of small strains and linear boundary conditions, and gravitation within the plate is neglected. For typical earth parameters its predictions are comparable to those of the usual thin plate theory frequently assumed in studies of lithospheric flexure, gravity and regional isostasy. Even for a very thick lithosphere, which may exist in some regions of Mars, the thin plate theory is a better approximation to the thick plate solution than the elastic half-space limit, except for short-wavelength loads.

  7. A bottom-up approach for optimization of friction stir processing parameters; a study on aluminium 2024-T3 alloy

    Highlights: • An experimental bottom-up approach has been developed for optimizing the process parameters for friction stir processing. • Optimum parameter processed samples were tested and characterized in detail. • Ultimate tensile strength of 1.3 times the base metal strength was obtained. • Residual stresses on the processed surface were only 10% of the yield strength of base metal. • Microstructure observations revealed fine equi-axed grains with precipitate particles at the grain boundaries. - Abstract: Friction stir processing (FSP) is emerging as one of the most competent severe plastic deformation (SPD) method for producing bulk ultra-fine grained materials with improved properties. Optimizing the process parameters for a defect free process is one of the challenging aspects of FSP to mark its commercial use. For the commercial aluminium alloy 2024-T3 plate of 6 mm thickness, a bottom-up approach has been attempted to optimize major independent parameters of the process such as plunge depth, tool rotation speed and traverse speed. Tensile properties of the optimum friction stir processed sample were correlated with the microstructural characterization done using Scanning Electron Microscope (SEM) and Electron Back-Scattered Diffraction (EBSD). Optimum parameters from the bottom-up approach have led to a defect free FSP having a maximum strength of 93% the base material strength. Micro tensile testing of the samples taken from the center of processed zone has shown an increased strength of 1.3 times the base material. Measured maximum longitudinal residual stress on the processed surface was only 30 MPa which was attributed to the solid state nature of FSP. Microstructural observation reveals significant grain refinement with less variation in the grain size across the thickness and a large amount of grain boundary precipitation compared to the base metal. The proposed experimental bottom-up approach can be applied as an effective method for

  8. Culture from the Bottom Up

    Atkinson, Dwight; Sohn, Jija


    The culture concept has been severely criticized for its top-down nature in TESOL, leading arguably to its falling out of favor in the field. But what of the fact that people do "live culturally" (Ingold, 1994)? This article describes a case study of culture from the bottom up--culture as understood and enacted by its individual users.…

  9. The hydrothermal power of oceanic lithosphere

    C. J. Grose


    Full Text Available We have estimated the power of ventilated hydrothermal heat transport, and its spatial distribution, using a set of recently developed plate models which highlight the effects of hydrothermal circulation and thermal insulation by oceanic crust. Testing lithospheric cooling models with these two effects, we estimate that global advective heat transport is about 6.6 TW, significantly lower than previous estimates, and that the fraction of that extracted by vigorous circulation on the ridge axes (<1 Ma is about 50% of the total, significantly higher than previous estimates. This low hydrothermal power estimate originates from the thermally insulating properties of oceanic crust in relation to the mantle. Since the crust is relatively insulating, the effective properties of the lithosphere are "crust dominated" near ridge axes (yielding lower heat flow, and gradually approach mantle values over time. Thus, cooling models with crustal insulation predict low heat flow over young seafloor, implying that the difference of modeled and measured heat flow is due to the heat transport properties of the lithosphere, in addition to ventilated hydrothermal circulation as generally accepted. These estimates may bear on important problems in the physics and chemistry of the Earth because the magnitude of hydrothermal power affects chemical exchanges between the oceans and the lithosphere, thereby affecting both thermal and chemical budgets in the oceanic crust and lithosphere, the subduction factory, and convective mantle.

  10. M(o)ssbauer spectroscopic studies the characterization of three China coal and the corresponding fly-ashes and bottom ashes

    YAO Duo-xi; ZHI Xia-chen


    Three fresh China coals (lignitie, bituminite and anthracite) from different geological origin and the corresponding fly and bottom ashes were studied by room temperature(RT) M(o)ssbauer spectroscopy(MS). The iron-bearing minerals were characterized to was found in bituminite and anthracite coal.The M(o)ssbauer spectra of the fly and bottom ashes as a result of pulverised coal combustion(PCC) in Xiaolongtan,Shuicheng and Luohuang Power Plants are comprised of superimposed sextets and doulets of oxides includes maghemite(γ-Fe2O3), magnitite(Fe3O4), haematite(α-Fe2O3), magnesioferite (MgFe2O4), Fe3+/Fe2+-mullite, Fe3+-glass silicate andmetallic iron. The studies also show that iron-bearing minerals in coals are largely dependant on geological regions and coal rank, the composition of the corresponding fly and bottom ashes will not only depend on the type and mineralogy of the feed coal but also on the local nature of combustion.

  11. Bottom dwelling animals: Benthos

    Ingole, B.S.

    . At the bottom/sediment dwelling animal communities are collectively termed as 'BENTHOS'. This extremely valuable component of the marine environment consumes the sediment organic matter from the overlying water column and effectively converts into benthic...

  12. Winter Bottom Trawl Survey

    National Oceanic and Atmospheric Administration, Department of Commerce — The standardized NEFSC Winter Bottom Trawl Survey was initiated in 1992 and covered offshore areas from the Mid-Atlantic to Georges Bank. Inshore strata were...

  13. Spring Bottom Trawl Survey

    National Oceanic and Atmospheric Administration, Department of Commerce — The standardized NEFSC Spring Bottom Trawl Survey was initiated in 1968 and covered an area from Cape Hatteras, NC, to Nova Scotia, Canada, at depths >27m....

  14. Summer Bottom Trawl Survey

    National Oceanic and Atmospheric Administration, Department of Commerce — Sampling the coastal waters of the Gulf of Maine using the Northeast Fishery Science Center standardized bottom trawl has been problematic due to large areas of...

  15. Seismic evidence for the layered mantle lithosphere: a comparsion between Zagros and South Africa

    Sodoudi, Forough; Kind, Rainer


    Recent S receiver function studies present evidence for the existence of the layered mantle lithosphere beneath ancient cratons. However, the nature of these layers is still unclear. They can be attributed to the presence of accumulated melts, remnants of subduction interfaces, changes in anisotropic properties or fluids. Further characterization of these layers is needed to provide more insights into the assembly and evolution of cratons. Here we compare the mantle lithosphere of the ancient Kalahari craton with the relatively young mantle lithosphere of Zagros, which is assumed as the location of the future craton. We applied the S receiver function method to map the internal layering of the lithosphere and to image its lower limit. For this aim, we used teleseismic events recorded at 97 seismic stations within the Kalahari craton and those recorded at 61 permanent seismic stations in Iran. Our results reveal a thick and stratified mantle lithosphere beneath the Kalahari craton containing three significant negative velocity contrasts at 85, 150-200, and 260-280 km depth. Moreover, they imply that frozen-in anisotropy as well as notable compositional variations can lead to sharp Mid-Lithospheric Discontinuities (MLD) that can be clearly observed in the SRF data. We show that a 50 km thick anisotropic layer just below the Moho boundary with 3% S wave anisotropy may be responsible for producing a MLD at 85 km depth. The horizontal anisotropy in the upper lithosphere may be attributed to processes during the formation of the Kalahari Craton. Furthermore, significant correlation between the depths of an apparent boundary separating the depleted and metasomatised lithosphere, as inferred from chemical tomography, and those of our second layer led us to characterize it as a compositional boundary, most likely due to the modification of the cratonic mantle lithosphere by magma infiltration. The largest velocity contrast (3.6-4.7%) is observed at a boundary located at

  16. Preferential mantle lithospheric extension under the South China margin

    Continental rifting in the South China Sea culminated in seafloor spreading at ∼ 30Ma (Late Oligocene). The basin and associated margins form a classic example of break-up in a relatively juvenile arc crust environment. In this study, we documented the timing, distribution and amount of extension in the crust and mantle lithosphere on the South China Margin during this process. Applying a one-dimensional backstripping modeling technique to drilling data from the Pearl River Mouth Basin (PRMB) and Beibu Gulf Basin, we calculated subsidence rates of the wells and examined the timing and amount of extension. Our results show that extension of the crust exceeded that in the mantle lithosphere under the South China Shelf, but that the two varied in phase, suggesting depth-dependent extension rather than a lithospheric-scale detachment. Estimates of total crustal extension derived in this way are similar to those measured by seismic refraction, indicating that isostatic compensation is close to being local. Extension in the Beibu Gulf appears to be more uniform with depth, a difference that we attribute to the different style of strain accommodation during continental break-up compared to intra-continental rifting. Extension in PRMB and South China slope continues for ∼ 5m.y. after the onset of seafloor spreading due to the weakness of the continental lithosphere. The timing of major extension is broadly mid-late Eocene to late Oligocene (∼ 45-25Ma), but is impossible to correlate in detail with poorly dated strike-slip deformation in the Red River Fault Zone. (author)

  17. Lithospheric and Upper-Mantle Structure of the Red Sea and Arabian Peninsula

    Hansen, S. E.; Schwartz, S. Y.; Rodgers, A. J.; Gaherty, J. B.; Al-Amri, A. M.


    Using broadband seismic data recorded by various networks, a variety of techniques have been employed to investigate the lithospheric and upper-mantle structure of the Red Sea and Arabian Peninsula. This presentation will summarize our findings and conclusions about the tectonic evolution and current state of the Arabian Plate. S-wave receiver functions provide constraints on the lithospheric thickness and reveal very thin lithosphere (40-80 km) along the Red Sea coast, which thickens rapidly toward the interior of the Arabian Shield (100-120 km). A step of 20-40 km in lithospheric thickness is also observed at the Shield-Platform boundary. Mantle anisotropy has been analyzed using shear-wave splitting of teleseismic SKS waveforms. The consistent north-south oriented fast directions are not adequately explained by end-member models of fossilized anisotropy and present-day plate motion and have instead been explained by a combination of plate- and density-driven flow in the asthenosphere. Further constraints on the upper mantle velocity and anisotropy have been obtained by jointly inverting the receiver function constraints with frequency dependent surface wave phase delays. The results demonstrate that the thin lithospheric lid is underlain by a pronounced low-velocity zone and that anisotropy is required in both the lithosphere and asthenosphere. Attenuation and thermal estimates are also being explored and preliminary results will be presented. The combined results of these studies support a two-stage rifting history for the Red Sea, where extension and erosion by asthenospheric flow are responsible for variations in the lithospheric thickness. These lithospheric variations guide asthenospheric flow beneath western Arabia and the Red Sea, leading to a large-scale thermal anomaly that is associated with Cenozoic uplift and volcanism. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National

  18. Structural regularities in the lithosphere of continents and plate tectonics

    Pavlenkova, N. I.


    Two fundamental, but competing earth science concepts have been under discussion in Russia. The first one, that of endogenous regimes, is based on the assumption that permanent vertical relationships or long-term interactions between the crust and upper mantle control crustal evolution. Significant horizontal movements of the lithosphere, as required by the second concept, that of global plate tectonics, would destroy these crust-mantle interactions. Certain regular features of the crust and upper mantle support the endogenous regime concept and are difficult to explain in terms of conventional plate tectonics. In particular, the close correlation between near-surface features and deep (> 400 km) mantle inhomogeneities suggests that many geological structures are deeply rooted in the mantle. Moreover, geophysical studies have failed to reveal a well-defined and continuous asthenosphere at relatively shallow depths (˜ 100 km) that would allow lithospheric plates to be transported over large distances, and the rheology of the lithosphere itself is found to be sufficiently inhomogeneous as to cast doubt on the principle of thin rigid plates. In contrast, palaeomagnetic and other data require that horizontal movements of many near-surface geological structures must have taken place. To explain this apparent contradiction, it is suggested here that the crust and its connected deep root are capable of gliding along one of the deep mantle phase transition zones with respect to the inner Earth.

  19. A Comparative Study of Fouling and Bottom Ash from Woody Biomass Combustion in a Fixed-Bed Small-Scale Boiler and Evaluation of the Analytical Techniques Used

    Lara Febrero


    Full Text Available In this work, fouling and bottom ash were collected from a low-power boiler after wood pellet combustion and studied using several analytical techniques to characterize and compare samples from different areas and determine the suitability of the analysis techniques employed. TGA results indicated that the fouling contained a high amount of organic matter (70%. The XRF and SEM-EDS measurements revealed that Ca and K are the main inorganic elements and exhibit clear tendency in the content of Cl that is negligible in the bottom ash and increased as it penetrated into the innermost layers of the fouling. Calcite, magnesia and silica appeared as the major crystalline phases in all the samples. However, the bottom ash was primarily comprised of calcium silicates. The KCl behaved identically to the Cl, preferably appeared in the adhered fouling samples. This salt, which has a low melting point, condenses upon contact with the low temperature tube and played a crucial role in the early stages of fouling formation. XRD was the most useful technique applied, which provided a semi-quantitative determination of the crystalline phases. FTIR was proven to be inadequate for this type of sample. The XRF and SEM-EDS, techniques yield similar results despite being entirely different.

  20. Lithospheric stress patterns: A global view

    Zoback, Mary Lou; Burke, Kevin

    The present-day lithospheric stress state is the result of a variety of forces that act on and within the tectonic plates forming the Iithosphere. Knowledge of this stress state provides important constraints on forces acting at a variety of scales and, hence, helps to solve scientific problems of interest to a wide spectrum of scientists and engineers.Six years of effort by scientists from all over the world (listed at end of article) brought together under the International Lithosphere Program (ILP) of the joint International Union of Geodesy and Geophysics/International Union of Geological Sciences (IUGG/IUGS) Interunion Commission on the Lithosphere culminated in the July 1992 publication of the World Stress Map and nineteen accompanying research papers in a special issue of the Journal of Geophysical Research-Solid Earth (volume 87, number B8). Figure 1 shows a reduced version of the published 1:40,000,000 color map.

  1. Seismic evidence for sharp lithosphere-asthenosphere boundaries of oceanic plates.

    Kawakatsu, Hitoshi; Kumar, Prakash; Takei, Yasuko; Shinohara, Masanao; Kanazawa, Toshihiko; Araki, Eiichiro; Suyehiro, Kiyoshi


    The mobility of the lithosphere over a weaker asthenosphere constitutes the essential element of plate tectonics, and thus the understanding of the processes at the lithosphere-asthenosphere boundary (LAB) is fundamental to understand how our planet works. It is especially so for oceanic plates because their relatively simple creation and evolution should enable easy elucidation of the LAB. Data from borehole broadband ocean bottom seismometers show that the LAB beneath the Pacific and Philippine Sea plates is sharp and age-dependent. The observed large shear wave velocity reduction at the LAB requires a partially molten asthenosphere consisting of horizontal melt-rich layers embedded in meltless mantle, which accounts for the large viscosity contrast at the LAB that facilitates horizontal plate motions. PMID:19390042

  2. Lithospheric thinning beneath rifted regions of Southern California.

    Lekic, Vedran; French, Scott W; Fischer, Karen M


    The stretching and break-up of tectonic plates by rifting control the evolution of continents and oceans, but the processes by which lithosphere deforms and accommodates strain during rifting remain enigmatic. Using scattering of teleseismic shear waves beneath rifted zones and adjacent areas in Southern California, we resolve the lithosphere-asthenosphere boundary and lithospheric thickness variations to directly constrain this deformation. Substantial and laterally abrupt lithospheric thinning beneath rifted regions suggests efficient strain localization. In the Salton Trough, either the mantle lithosphere has experienced more thinning than the crust, or large volumes of new lithosphere have been created. Lack of a systematic offset between surface and deep lithospheric deformation rules out simple shear along throughgoing unidirectional shallow-dipping shear zones, but is consistent with symmetric extension of the lithosphere. PMID:21979933

  3. Synopsis SFB 108 - stress and stress release in the lithosphere1

    Fuchs, K.


    'Stress and Stress Release in the Lithosphere' has been studied within a Collaborative Research Centre at Karlsruhe University (SFB 108) as special contribution from Germany to the International Lithosphere Program (ILP). This synopsis is an outline of the research results obtained by the SFB 108 as presented in this special volume of Tectonophysics. It starts with a summary of ideas on stress and stress release in the lithosphere which guided the SFB 108 at its beginning in 1981. It is followed by a review of strategy in cooperative research on rift systems, world stress map and the scales of structure of the continental lithosphere from crust to mantle. The main observations are then summarized and connections are made between key results from the various disciplines to obtain new views in lithospheric tectonics. Finally we address open questions and perspectives for future research. The research addressed various styles of continental rifting from the Afro-Arabian rift system to the Central European rift system with the Rhinegraben and the grabens in the French Massif Central as outstanding features. A number of critical parameters such as thickness, heat flow, rheology, composition, strength of the crust and of the lithospheric mantle and the influence of active mantle plumes were identified and classified. Together they strongly influence the style of rifting. Petrophysical modelling of integrated information on seismic velocities, composition and temperature from xenolith analysis, density, gravity and topography provided essential constraints on plume-lithosphere interaction in the French Massif Central and also in the Kenya rift. The Rhinegraben and its Variscan environment offered the opportunity to study different concepts of upper and lower crust, including the occurrence of deep crustal earthquakes and the role of an Alpine detachment. A special concern of the SFB 108 was the distribution of dimensions of heterogeneities in the lithosphere and its

  4. Charmed Bottom Baryon Spectroscopy

    Brown, Zachary S; Detmold, William; Meinel, Stefan; Orginos, Kostas


    The spectrum of doubly and triply heavy baryons remains experimentally unexplored to a large extent. Although the detection of such heavy particle states may lie beyond the reach of exper- iments for some time, it is interesting compute this spectrum from QCD and compare results between lattice calculations and continuum theoretical models. Several lattice calculations ex- ist for both doubly and triply charmed as well as doubly and triply bottom baryons. Here, we present preliminary results from the first lattice calculation of doubly and triply heavy baryons including both charm and bottom quarks. We use domain wall fermions for 2+1 flavors (up down and strange) of sea and valence quarks, a relativistic heavy quark action for the charm quarks, and non-relativistic QCD for the heavier bottom quarks. We present preliminary results for the ground state spectrum.

  5. Cathodic protection for the bottoms of above ground storage tanks

    Mohr, John P. [Tyco Adhesives, Norwood, MA (United States)


    Impressed Current Cathodic Protection has been used for many years to protect the external bottoms of above ground storage tanks. The use of a vertical deep ground bed often treated several bare steel tank bottoms by broadcasting current over a wide area. Environmental concerns and, in some countries, government regulations, have introduced the use of dielectric secondary containment liners. The dielectric liner does not allow the protective cathodic protection current to pass and causes corrosion to continue on the newly placed tank bottom. In existing tank bottoms where inadequate protection has been provided, leaks can develop. In one method of remediation, an old bottom is covered with sand and a double bottom is welded above the leaking bottom. The new bottom is welded very close to the old bottom, thus shielding the traditional cathodic protection from protecting the new bottom. These double bottoms often employ the use of dielectric liner as well. Both the liner and the double bottom often minimize the distance from the external tank bottom. The minimized space between the liner, or double bottom, and the bottom to be protected places a challenge in providing current distribution in cathodic protection systems. This study examines the practical concerns for application of impressed current cathodic protection and the types of anode materials used in these specific applications. One unique approach for an economical treatment using a conductive polymer cathodic protection method is presented. (author)

  6. Assessment study of the coupled code RELAP5/PARCS against the Peach Bottom BWR turbine trip test

    The modeling of complex transients in nuclear power plants (NPP) remains a challenging topic for best estimate three-dimensional coupled code computational tools. This technique is, nowadays, extensively used for simulating transients that involve core spatial asymmetric phenomena and strong feedback effects between core neutronics and reactor loop thermal-hydraulics. In this framework, the Peach Bottom BWR turbine trip experiment 2 is considered. The test involves a rapid positive reactivity addition into the core generated by a water hammer load. To perform a numerical simulation of such phenomenon a reference case was calculated using the coupled code RELAP5/PARCS. An overall data comparison shows good agreement between calculated and measured pressure wave trend in the core region. However, the predicted power response during the excursion phase did not match correctly the experimental tendency. For this purpose, a series of sensitivity analyses have been carried out to identify the most probable reasons of such discrepancy. It was found out that the uncertainties related to the cross-sections modeling and to the thermal-hydraulic closure relationships are the main source of the incorrect power feedback response during the transient

  7. Case studies of the application of enhanced steel alloys for bottom hole assembly components for sour service conditions

    Chan, Alvaro [Nov Grant Prideco, Navasota (United States); Moura, Carlos [ASPEN Assesoria Tecnica e Comercial, Cascavel, PR (Brazil); Johnson, Charles; Landriault, Alain [Weatherford Canda Partnership, Calgary, AB (Canada)


    The new more modern drilling programs require the drill string to travel across sour formations in order to reach the hydrocarbon reservoirs. Traditional materials have been employed in the manufacture of HWDP components along with basic heat treatment processes. Standard HWDP tools have started to show their operational as well as environmental limitations when subjected to sour service applications. The advanced, more complex drilling programs require for the HWDP tools to be put in service under different configurations. Either at the bottom of the drill string near the drill bit for vertical well configurations or on top of the drill string for weight application on horizontal or extended reach applications. An operator in northwestern Canada has replaced standard HWDP with enhanced sour service HWDP in order to complete the programmed wells. These enhanced tools offer higher tensile and torque capabilities and improved toughness than standard HWDP tools and in addition, provide protection against sour service conditions. The use of second-generation double shoulder connections (2nd-Gen. DSC) has also provided added torque and tensile capacities to these versatile HWDP tools. For over a year more than a dozen wells have been drilled employing these enhanced BHA tools and have helped the operator reach its targets through sour service formations and produce wells in a safe and cost effective manner. (author)

  8. Study of the Top-quark Pair Production in Association with a Bottom-quark Pair from Fast Simulations at the LHC

    Jo, Young Kwon; Choi, Su Yong; Kim, Tae Jeong; Roh, Youn Jung


    A large number of top quarks will be produced at the Large Hadron Collider (LHC) for Run II period. This will allow us to measure the rare processes from the top sector in great details. We present the study of the top-quark pair production in association with a bottom-quark pair (ttbb) from fast simulations for the Compact Muon Solenoid (CMS) experiment. The differential distributions of ttbb are compared with the top-quark pair production with two additional jets (ttjj) and with the product...

  9. Magnetic mineralogy of the Mercurian lithosphere

    Strauss, Becky; Feinberg, Joshua; Johnson, Catherine


    Mercury and Earth are the only inner solar system planets with present-day core-dynamo magnetic fields, in contrast to the past fields of Mars and the Moon and the absence of evidence for a past or present field at Venus. Recently, the MESSENGER mission also measured magnetic fields from lithospheric magnetization on Mercury for the first time. These fields are consistent with remanent magnetization held by rocks exposed to an ancient, internally generated planetary magnetic field. However, the conditions for magnetization in the lithosphere of Mercury are unique among terrestrial planets, and the mechanisms for the acquisition (induced versus remanent) and alteration of magnetization are still unknown. We investigate the physical and chemical environment of Mercury's crust, past and present, to establish the conditions in which magnetization may have been acquired and subsequently modified. Three factors are particularly crucial to the determination of crustal composition and iron mineralogy: the temperature profile of the lithosphere and its evolution over time, redox conditions in the planet's crust and mantle, and the iron content of the lithosphere. We explore potential mechanisms for remanence acquisition and alteration on Mercury, whose surface environment is distinct from that of other inner solar system planets in that it is both very hot and highly reducing. The long-term thermal history of Mercury's crust plays an important role in the longevity of any crustal magnetization, which may be subject to remagnetization through thermal, viscous, and shock mechanisms. This thermal and compositional framework isused to constrain plausible candidate magnetic mineralogies, which can then be analyzed in terms of their capacity to acquire and retain magnetic remanence that is detectable from satellite orbit. We propose a suite of minerals and materials that could be carriers of remanence in the lithosphere of Mercury, including iron alloys, silicides, and sulfides.

  10. The oscillations of ship lock bottom

    N.Yu. Kuzmin


    Full Text Available The article deals with the dynamic characteristics of the ship lock. The accurate design relations intended to study the natural and forced vibrations of the bottom of the ship lock are provided. The degree of filling of the lock, as well as the added mass of water is considered. The various coupling conditions of the bottom and walls of buildings are taken into account. A concrete example of the calculation is given.An exact, in the framework of the adopted design scheme, solution of the problem of the own and forced vibrations of the bottom of the ship lock is found. The frequency of the first five tones of vibrations and the associated mass of liquid according to thickness of the structure and coupling conditions of the bottom and sides of the lock are analyzed. A significant effect of liquids on low-frequency part of the spectrum and the dynamic response of the bottom is determined.

  11. Laser bottom hole assembly

    Underwood, Lance D; Norton, Ryan J; McKay, Ryan P; Mesnard, David R; Fraze, Jason D; Zediker, Mark S; Faircloth, Brian O


    There is provided for laser bottom hole assembly for providing a high power laser beam having greater than 5 kW of power for a laser mechanical drilling process to advance a borehole. This assembly utilizes a reverse Moineau motor type power section and provides a self-regulating system that addresses fluid flows relating to motive force, cooling and removal of cuttings.

  12. A Numerical Study of Natural Convection in a Square Enclosure with Non-Uniformly Heated Bottom Wall and Square Shape Heated Block

    M. Jahirul Haque Munshi


    Full Text Available The present work is aimed to study has been carried out of natural convection in a square enclosure with non-uniformly heated bottom wall and square shape heated block with different Prandtl numbers of 0.71, 1.0 and 1.5 has been investigated numerically. The horizontal bottom wall of the square cavity was nonuniformly heated and inner square shape heated block kept at Th while the side walls of the cavity were maintained at a cold temperature Tc with Th>Tc and upper wall is adiabatic. Finite element method was employed to solve the dimensionless governing equations of continuity, momentum and energy of the problem. Using the developed code, a parametric study was performed, and the effects of the Rayleigh number and the different Prandtl number on the fluid flow and heat transfer inside the square enclosure were investigated. The obtained results showed that temperature distribution and flow pattern inside the square enclosure depended on both strength of the magnetic field and Rayleigh number. For all cases two counter rotating eddies were formed inside the square enclosure. The magnetic field is decreased with the intensity of natural convection and flow velocity. Also it was found that for higher Rayleigh numbers a relatively stronger field was needed to decrease the heat transfer through natural convection.

  13. Study of the top-quark-pair production in association with a bottom-quark pair from fast simulations for the CMS experiment

    Jo, Young Kwon; Kim, Tae Jeong; Roh, Youn Jung


    The large number of top quarks will be produced at the Large Hadron Collider for Run II period. This will allow us to measure the rare processes from the top sector in great details. We present the study of the top-quark-pair production in association with a bottom-quark pair (ttbb) from fast simulations for the CMS experiment. Differential distributions of ttbb are compared with the top-quark-pair production with two additional jets (ttjj) and also the production in association with the Higgs (ttH) where the Higgs decays to a bottom-quark pair. The significances of ttbb process in the dileptonic and semileptonic decay mode are calculated with the data corresponding to an integrated luminosity of 10 fb-1 which is foreseen to be collected in the early Run II period. This study will be an important input in searching for the new physics beyond the standard model as well as in searching for ttH process where the Yukawa coupling with the top quark can be directly measured.

  14. Study of the top-quark pair production in association with a bottom-quark pair from fast simulations at the LHC

    Jo, Young Kwon; Choi, Su Yong; Roh, Youn Jung; Kim, Tae Jeong


    A large number of top quarks will be produced at the Large Hadron Collider (LHC) during the Run II period. This will allow us to measure the rare processes from the top sector in great details. We present a study of top-quark pair production in association with a bottom-quark pair (tbar tbbar b) from fast simulations for the Compact Muon Solenoid (CMS) experiment. The differential distributions of tbar tbbar b are compared with the top-quark pair production with two additional jets (tbar tjj) and with the production in association with the Higgs (tbar tH), where the Higgs decays to a bottom-quark pair. The significances of the tbar tbbar b process in the dileptonic and the semileptonic decay modes are calculated with the data corresponding to an integrated luminosity of 10 fb-1, which is foreseen to be collected in the early Run II period. This study will provide an important input in searching for new physics beyond the standard model, as well as in searching for the tbar tH process where the Yukawa coupling with the top quark can be directly measured.

  15. Lithospheric scale model of Merida Andes, Venezuela (GIAME Project)

    Schmitz, M.; Orihuela, N. D.; Klarica, S.; Gil, E.; Levander, A.; Audemard, F. A.; Mazuera, F.; Avila, J.


    Merida Andes (MA) is one of the most important orogenic belt in Venezuela and represents the northern culmination of South America Andes. During the last 60 years, several models have been proposed to explain the shallow and deep structure, using different geological, geophysical, seismological, geochemical and petrologic concepts; nevertheless, most of them have applied local observation windows, and do not represent the major structure of MA. Therefore, a multidisciplinary research group, coordinated by FUNVISIS, in close cooperation with UCV, ULA and PDVSA, is proposed in order to get the outlined goals in the project entitled GIAME ("Geociencia Integral de los Andes de MErida") was established, which aims to generate a lithospheric scale model and the development of a temporal dynamic model for the MA. As a base for lithospheric investigations of the Merida Andes, we are proposing three wide angle seismic profiles across the orogen on three representative sites, in order to determine the inner structure and its relation with the orogen's gravimetric root. To the date, there are no seismic studies at lithospheric scale which cross MA. The wide angle seismic will be complemented with the re-processing and re-interpretation of existing reflection seismic data, which will allow to establish a relationship between MA and its associated flexural basins (Maracaibo and Barinas-Apure basins). Depending on the results of the VENCORP Project (VENezuelan COntinental Reflection Profiling), which might show some reliable results about crustal features and Moho reflectors along three long seismic profiles at Caribbean Moutain system, a reflection seismic profile across the central portion of MA is proposed. Additional tasks, consisting in MA quaternary deformation studies, using research methods like neotectonics and paleoseismology, georadar, numerical modeling, cinematic GPS, SAR interferometry, thermocronology, detailed studies on regional geology, flexural modeling

  16. Lithospheric flexure beneath the Freyja Montes Foredeep, Venus: Constraints on lithospheric thermal gradient and heat flow

    Analysis of Venera 15 and 16 radar images and topographic data from the Freyja Montes region on Venus suggest that this mountain belt formed as a result of a sequence of underthrusts of the lithosphere of the North Polar Plains beneath the highlands of Ishtar Terra. The Freyja Montes deformation zone consists, south to north, of a linear orogenic belt, an adjacent plateau, a steep scarp separating the plateau from the North Polar Plains, a linear depression at the base of the scarp, and an outer rise. The topographic profile of the depression and outer rise are remarkably similar to that of a foreland deep and rise formed by the flexure of the underthrusting plate beneath a terrestrial mountain range. The authors test the lithospheric flexure hypothesis and they estimate the effective thickness Te of the elastic lithosphere of the underthrusting portion of the North Polar Plains by fitting individual topographic profiles to deflection curves for a broken elastic plate. The theoretical curves fit the observed topographic profiles to within measurement error for values of flexural rigidity D in the range (0.8-3) x 1022 N m, equivalent to Te in the range 11-18 km. Under the assumption that the base of the mechanical lithosphere is limited by the creep strength of olivine, the mean lithospheric thermal gradient is 14-23 K/km. That the inferred thermal gradient is similar to the value expected for the global mean gradient on the basis of scaling from Earth provides support for the hypothesis that simple conduction dominates lithospheric heat transport on Venus relative to lithospheric recycling and volcanism

  17. Bottom-strange mesons in hyperonic matter

    Pathak, Divakar; Mishra, Amruta


    The in-medium behavior of bottom-strange pseudoscalar mesons in hot, isospin asymmetric and dense hadronic environment is studied using a chiral effective model. The same was recently generalized to the heavy quark sector and employed to study the behavior of open-charm and open-bottom mesons. The heavy quark (anti-quark) is treated as frozen and all medium modifications of these bottom-strange mesons are due to their strange anti-quark (quark) content. We observe a pronounced dependence of t...

  18. The lithosphere-asthenosphere system in the Calabrian Arc and surrounding seas

    Through the non-linear inversion of Surface-Wave Tomography data, using as a priori constraints seismic data from literature, it has been possible to define a fairly detailed structural model of the lithosphere-asthenosphere system (thickness, S-wave and P-wave velocities of the crust and of the upper mantle layers) in the Calabrian Arc region (Southern Tyrrhenian Sea, Calabria and the Northern-Western part of the Ionian Sea). The main features identified by our study are: (1) a very shallow (less then 10 km deep) crust-mantle transition in the Southern Tyrrhenian Sea and very low S-wave velocities just below a very thin lid in correspondence of the submarine volcanic bodies in the study area; (2) a shallow and very low S-wave velocity layer in the mantle in the areas of Aeolian islands, of Vesuvius, Ischia and Phlegraean Fields, representing their shallow-mantle magma source; (3) a thickened continental crust and lithospheric doubling in Calabria; (4) a crust about 25 km thick and a mantle velocity profile versus depth consistent with the presence of a continental rifled, now thermally relaxed, lithosphere in the investigated part of the Ionian Sea; (5) the subduction of the Ionian lithosphere towards NW below the Tyrrhenian Basin; (6) the subduction of the Adriatic lithosphere underneath the Vesuvius and Phlegraean Fields. (author)

  19. Experimental study on secondary depressurization action for PWR vessel bottom small break LOCA with HPI failure and gas inflow (ROSA-V/LSTF test SB-PV-03)

    A small break loss-of-coolant accident (SBLOCA) experiment was conducted at the Large Scale Test Facility (LSTF) of ROSA-V program to study effects of accident management (AM) measures on core cooling, which is important in case of high pressure injection (HPI) system failure during an SBLOCA at a pressurized water reactor (PWR). The LSTF is a full-height and 1/48 volume-scaled facility simulating 4-loop Westinghouse-type PWR (3423 MWt). The experiment, SB-PV-03, simulated a PWR vessel bottom SBLOCA with a rupture of ten instrument-tubes which is equivalent to 0.2% cold leg break. Total HPI failure, non-condensable gas inflow from accumulator injection system (AIS) and operator AM actions on steam generator (SG) secondary depressurization at a rate of -55 K/h and auxiliary feedwater (AFW) supply for 30 minutes were assumed as experiment conditions. It is clarified that the AM actions are effective on primary system depressurization until the end of AIS injection at 1.6 MPa, but thereafter become less effective due to inflow of the non-condensable gas, resulting in delay of low pressure injection (LPI) actuation and whole core heatup under continuous water discharge through the bottom break. The report describes these thermohydraulic phenomena related with transient primary coolant mass and AM actions in addition to estimation of non-condensable gas behavior which affected primary-to-secondary heat transfer. (author)

  20. The lithosphere-asthenosphere boundary observed with USArray receiver functions

    P. Kumar


    Full Text Available The dense deployment of seismic stations so far in the western half of the United States within the USArray project provides the opportunity to study in greater detail the structure of the lithosphere-asthenosphere system. We use the S receiver function technique for this purpose which has higher resolution than surface wave tomography, is sensitive to seismic discontinuities and has no problems with multiples like P receiver functions. Only two major discontinuities are observed in the entire area down to about 300 km depth. These are the crust-mantle boundary (Moho and a negative boundary which we correlate with the lithosphere-asthenosphere boundary (LAB since a low velocity zone is the classical definition of the seismic observation of the asthenosphere by Gutenberg (1926. Our S receiver function LAB is at a depth of 70–80 km in large parts of westernmost North America. East of the Rocky Mountains its depth is generally between 90 and 110 km. Regions with LAB depths down to about 140 km occur in a stretch from northern Texas over the Colorado Plateau to the Columbia Basalts. These observations agree well with tomography results in the westernmost USA and at the east coast. However, in the central cratonic part of the USA the tomography LAB is near 200 km depth. At this depth no discontinuity is seen in the S receiver functions. The negative signal near 100 km depth in the central part of the USA is interpreted by Yuan and Romanowicz (2010 or Lekic and Romanowicz (2011 as a recently discovered mid lithospheric discontinuity (MLD. A solution for the discrepancy between receiver function imaging and surface wave tomography is not yet obvious and requires more high resolution studies at other cratons before a general solution may be found. Our results agree well with petrophysical models of increased water content in the asthenosphere, which predict a sharp and shallow LAB also in continents (Mierdel et al., 2007.

  1. The lithosphere-asthenosphere boundary observed with USArray receiver functions

    P. Kumar


    Full Text Available The dense deployment of seismic stations so far in the western half of the United States within the USArray project provides the opportunity to study in greater detail the structure of the lithosphere-asthenosphere system. We use the S receiver function technique for this purpose, which has higher resolution than surface wave tomography, is sensitive to seismic discontinuities, and is free from multiples, unlike P receiver functions. Only two major discontinuities are observed in the entire area down to about 300 km depth. These are the crust-mantle boundary (Moho and a negative boundary, which we correlate with the lithosphere-asthenosphere boundary (LAB, since a low velocity zone is the classical definition of the seismic observation of the asthenosphere by Gutenberg (1926. Our S receiver function LAB is at a depth of 70–80 km in large parts of westernmost North America. East of the Rocky Mountains, its depth is generally between 90 and 110 km. Regions with LAB depths down to about 140 km occur in a stretch from northern Texas, over the Colorado Plateau to the Columbia basalts. These observations agree well with tomography results in the westernmost USA and on the east coast. However, in the central cratonic part of the USA, the tomography LAB is near 200 km depth. At this depth no discontinuity is seen in the S receiver functions. The negative signal near 100 km depth in the central part of the USA is interpreted by Yuan and Romanowicz (2010 and Lekic and Romanowicz (2011 as a recently discovered mid-lithospheric discontinuity (MLD. A solution for the discrepancy between receiver function imaging and surface wave tomography is not yet obvious and requires more high resolution studies at other cratons before a general solution may be found. Our results agree well with petrophysical models of increased water content in the asthenosphere, which predict a sharp and shallow LAB also in continents (Mierdel et al., 2007.

  2. Flexure and rheology of Pacific oceanic lithosphere

    Hunter, Johnny; Watts, Tony


    The idea of a rigid lithosphere that supports loads through flexural isostasy was first postulated in the late 19th century. Since then, there has been much effort to investigate the spatial and temporal variation of the lithosphere's flexural rigidity, and to understand how these variations are linked to its rheology. We have used flexural modelling to first re-assess the variation in the rigidity of oceanic lithosphere with its age at the time of loading, and then to constrain mantle rheology by testing the predictions of laboratory-derived flow laws. A broken elastic plate model was used to model trench-normal, ensemble-averaged profiles of satellite-derived gravity at the trench-outer rise system of circum-Pacific subduction zones, where an inverse procedure was used to find the best-fit Te and loading conditions. The results show a first-order increase in Te with plate age, which is best fit by the depth to the 400 ± 35°C plate-cooling isotherm. Fits to the observed gravity are significantly improved by an elastic plate that weakens landward of the outer rise, which suggests that bending-induced plate weakening is a ubiquitous feature of circum-Pacific subduction zones. Two methods were used to constrain mantle rheology. In the first, the Te derived by modelling flexural observations was compared to the Te predicted by laboratory-derived yield strength envelopes. In the second, flexural observations were modelled using elastic-plastic plates with laboratory-derived, depth-dependent yield strength. The results show that flow laws for low-temperature plasticity of dry olivine provide a good fit to the observations at circum-Pacific subduction zones, but are much too strong to fit observations of flexure in the Hawaiian Islands region. We suggest that this discrepancy can be explained by differences in the timescale of loading combined with moderate thermal rejuvenation of the Hawaiian lithosphere.

  3. The prediction of oceanic lithospheric magnetic anomalies from magnetisation estimates, using vector spherical harmonics

    Masterton, S.; Gubbins, D.; Ivers, D.; Müller, D.; Winch, D.


    High resolution lithospheric magnetic field anomaly maps derived from satellite data now offer immense opportunities to interpret crustal magnetic properties such as susceptibility, depth to Curie isotherm, magnetisation type and intensity. We present a method in which a vector spherical harmonic formulation allows the natural separation of 3 types of lithospheric magnetisation: one responsible for the observed potential field external to the crust, one responsible for the field inside the Earth that is not observed, and a toroidal magnetisation associated with a radial electric current responsible for a non-potential field. The latter two constitute the annihilator in the inverse problem for magnetisation using magnetic field data. Starting from a model of vertically integrated lithospheric magnetisation based on geology, we compute all 3 types of magnetisation and discuss implications of the 2 annihilators for inversion studies. We adopt a forward-modelling approach in which lithospheric magnetisation is estimated independently of satellite data, with particular emphasis on the oceans. Induced and remanent contributions are determined separately. Remanent magnetisation is derived from a combination of magnetic crustal thickness, a remanence intensity-age profile superimposed onto a geomagnetic polarity timescale and a digital age grid of the ocean floor, and magnetisation directions derived from the implementation of updated plate reconstruction models. Induced magnetisation is derived from a combination of magnetic crustal thickness and standard magnetic susceptibilities associated with major geological units. We present comparisons between magnetic anomalies predicted from magnetisation estimates and lithospheric magnetic field models.

  4. Three-dimensional density distributions in the Asian lithosphere

    Zhang, G.; Li, C.; Wang, X.; Wang, Z.; Fang, J.; Sino-probe-cugb


    We have inversed the residual Bouguer gravity anomalies to study the three-dimensional density distributions of the Asian lithosphere (60°~150°E and 15°~60°N). Firstly, we have collected the free-air gravity anomalies (30'×30') and topography data of GTOP030 with 5'×5' grid spacing, and then calculated the Bougouer gravity anomalies by terrain correction and Bougouer correction. We have also collected the depth data of the Moho discontinuity (30'×30') and the discontinuity of sedimentary layer. By using the Oldenburg-Parker formula (Parker, 1972) and the forward modeling method, we calculated the theoretical gravity anomalies which mainly are caused by the Moho discontinuity and the sedimentary layer discontinuity. In our study, the average depths of Moho discontinuity and sedimentary layer discontinuity are 33 km and 4 km, and the density differences are 0.42 g/cm3 and 0.2 g/cm3, respectively. In addition, we have simulated the gravity anomalies of the spherical harmonics with the 2-6 order for the lower mantle by using the formula of Bowin (1983) which represented the relation between the depth of field source and the order of the geopotential spherical harmonics. Using all data mentioned above, we have calculated the residual Bougouer gravity anomalies, which may be caused by anomalous density bodies in the lithosphere. Secondly, we used the calculated residual Bougouer gravity anomalies to inverse the three-dimensional density differences in the Asian lithosphere by using the Algebra Reconstruction Techniques (ART). During the inversion, the densities converted from the P-wave velocity data (with grid spacing of 2°×2°) according to the Birch Law are considered as the initial density model. The grid spacing is set as 2°×2° in the horizontal direction, and it is 25 km, 55 km and 100 km in the vertical direction, respectively. Comparing the density anomalies at the three depths, we can conclude that (1) the density in the lithosphere beneath Asian

  5. Lithospheric Thickness Modeled from Long Period Surface Wave Dispersion

    Pasyanos, M E


    The behavior of surface waves at long periods is indicative of subcrustal velocity structure. Using recently published dispersion models, we invert surface wave group velocities for lithospheric structure, including lithospheric thickness, over much of the Eastern Hemisphere, encompassing Eurasia, Africa, and the Indian Ocean. Thicker lithosphere under Precambrian shields and platforms are clearly observed, not only under the large cratons (West Africa, Congo, Baltic, Russia, Siberia, India), but also under smaller blocks like the Tarim Basin and Yangtze craton. In contrast, it is found that remobilized Precambrian structures like the Saharan Shield and Sino-Korean Paraplatform do not have well-established lithospheric keels. The thinnest lithospheric thickness is found under oceanic and continental rifts, as well as along convergence zones. We compare our results to thermal models of continental lithosphere, lithospheric cooling models of oceanic lithosphere, lithosphere-asthenosphere boundary (LAB) estimates from S-wave receiver functions, and velocity variations of global tomography models. In addition to comparing results for the broad region, we examine in detail the regions of Central Africa, Siberia, and Tibet. While there are clear differences in the various estimates, overall the results are generally consistent. Inconsistencies between the estimates may be due to a variety of reasons including lateral and depth resolution differences and the comparison of what may be different lithospheric features.

  6. Thermal erosion of cratonic lithosphere as a potential trigger for mass-extinction

    Pilet, Sebastien; Guex, Jean; Muntener, Othmar; Bartolini, Annachiara; Spangenberg, Jorge; Schoene, Blair; Schaltegger, Urs


    studies of the composition of the Kaapvaal craton have shown that sulfide minerals are enclosed in the basal part of the cratonic lithosphere. The formation of these sulfide minerals are linked to multiple refertilization/metasomatic events, which affected the base of the subcontinental lithospheric mantle from the Archean to the Proterozoic. We suggest that the transitions from an initial cool period to greenhouse conditions recorded by T-J and Pl-To sedimentary sections result of changing gas species emitted during the progressive thermal erosion of cratonic lithosphere by plume activity or thermal internal heating of the lithosphere. Our petrological model for LIP magmatism argues that initial gas emission was dominated by sulfur liberated from sulfide-bearing cratonic lithosphere causing global cooling and eustatic regression, which was followed by warming/transgression associated with the progressive increase of CO2 in the atmosphere associated to LIPs emission and metamorphic reactions in sedimentary basins. We suggest that the nature of the underlying lithosphere during large LIP eruption potentially exerts an important control on the consequences at the Earth's surface. This model offers an explanation for why LIPs erupted through oceanic lithosphere are not associated with climatic and biotic crises comparable to LIPs emitted through cratonic lithosphere.

  7. Insights for the melt migration, the volcanic activity and the ultrafast lithosphere delamination related to the Yellowstone plume (Western USA)

    Rigo, A.; Adam, C.; Grégoire, M.; Gerbault, M.; Meyer, R.; Rabinowicz, M.; Fontaine, F.; Bonvalot, S.


    The Yellowstone-East Snake River Plain hotspot track has been intensely studied since several decades and is widely considered to result from the interaction of a mantle plume with the North American plate. An integrated conclusive geodynamic interpretation of this extensive data set is however presently still lacking, and our knowledge of the dynamical processes beneath Yellowstone is patchy. It has been argued that the Yellowstone plume has delaminated the lower part of the thick Wyoming cratonic lithosphere. We derive an original dynamic model to quantify delamination processes related to mantle plume-lithosphere interactions. We show that fast (˜300 ka) lithospheric delamination is consistent with the observed timing of formation of successive volcanic centres along the Yellowstone hotspot track and requires (i) a tensile stress regime within the whole lithosphere exceeding its failure threshold, (ii) a purely plastic rheology in the lithosphere when stresses reach this yield limit, (iii) a dense lower part of the 200 km thick Wyoming lithosphere and (iv) a decoupling melt horizon inside the median part of the lithosphere. We demonstrate that all these conditions are verified and that ˜150 km large and ˜100 km thick lithospheric blocks delaminate within 300 ka when the Yellowstone plume ponded below the 200 km thick Wyoming cratonic lithosphere. Furthermore, we take advantage of the available extensive regional geophysical and geological observation data sets to design a numerical 3-D upper-mantle convective model. We propose a map of the ascending convective sheets contouring the Yellowstone plume. The model further evidences the development of a counter-flow within the lower part of the lithosphere centred just above the Yellowstone mantle plume axis. This counter-flow controls the local lithospheric stress field, and as a result the trajectories of feeder dykes linking the partial melting source within the core of the mantle plume with the crust by

  8. On searching applicants for mechanism of solar-lithosphere relations

    Kairatkyzy, Dina; Andreyev, Alexey; Zhumabayeva, Saltanat; Seraliyev, Alibek


    It is actively discussed at present a question on possible influence of solar activity (high-speed solar wind streams bearing the "frozen" magnetic field lines of the Sun) on the stress status of the lithosphere and, consequently, on the Earth's seismic activity (e.g. Zhang, 1998, Acta Seismologica Sinica; Khachikyan et al., EGU2016-2754-1; IUGG2015-3132). There are at least two ideas on possible applicants for physical mechanism of solar-lithosphere relations: (i) - the muons of cosmic rays, which can penetrate the Earth's crust to a depth of at least the first ten kilometers and in tense seismic environment generate nuclear-electromagnetic cascade which energy can be a trigger of earthquake (Tsarev and Chechin, 1988, Preprint № 179, Physical Institute after Lebedev, Moscow); (ii) - the geomagnetic storms (Sobolev et al., 1998, Physics of the Earth #7) when the high-frequency oscillations of the geomagnetic field during the main phase of the storm generate significant induction currents which electric energy entering into the crust can be converted into mechanical energy increasing the stress status of the lithosphere (Sobolev and Demin, Mechano-electric phenomena into the Earth. M . Nauka. 1980). Besides this, among the possible cosmogenic factors changing the stress state of the lithosphere, could be the variation of the angular velocity of rotation of the Earth (e.g. Bostrom, 2000. Tectonic consequence of the Earth's Rotation), if it depends on solar activity variations. More of 50 years ago, Munk and Donald (The Rotation of the Earth, Cambrige University Press, 1960) suggested that the interaction between solar wind and geomagnetic field would probably influence the short period variation of angular velocity of the Earth. In this work, we check up this suggestion on the base of very precise data on the length of day (LOD) from 1986 to the present, which are presented by the International Earth Rotation and Reference Systems Service (IERS). Using the methods

  9. Deep Continental Crustal Earthquakes and Lithospheric Structure: A Global Synthesis

    Devlin, S.; Isacks, B. L.


    The distribution of earthquake depths within the continental crust defines the seismogenic thickness (TS), over which at least some part of crustal deformation is accommodated by rapid release of stored elastic strains. Intraplate continental seismicity is often thought to be restricted to the upper crust where TS is within the range of 15 to 20 km. This appears consistent with a lithospheric strength profile involving a weak, ductile lower crust located beneath a stronger, brittle upper crust. With the assumption of a strong uppermost mantle lid, this is often referred to the Jelly Sandwich model of lithosphere rheology. Studies in many places, however, document lower crustal earthquakes beneath continents in apparent disagreement with the model. We explore this and related issues through a survey of where and in what tectonic settings deep intraplate earthquakes are well documented in the continental crust. TS reaches Moho depth in many intraplate regions \\--- Sierra Nevada, Colorado Plateau, East African and Baikal Rift Systems, North Island New Zealand, Tien Shan, and the Andean and Alpine forelands. A review of possible deformation mechanisms which could control continental earthquake depth and facilitate seismicity beneath the brittle-ductile transition suggests that the influence of fluids is the only mechanism capable of encouraging earthquake occurrence throughout the continental crust at any tectonic setting. Surface derived fluids can induce pore fluid pressure changes to depths of 25 km and melt-reactions can induce earthquakes at depths throughout continental crust. On a global scale, fluid-enhanced embrittlement is not limited by depth or tectonic environment. We find that deep crustal earthquakes occur where the lithosphere is in a transitional state between primarily stable (e.g., shields) and highly deformed (e.g., U.S. Basin and Range or Southern California). Observations of relative intensity of tectonic deformation and regional percent strain

  10. Processes of lithosphere evolution: New evidence on the structure of the continental crust and uppermost mantle

    Artemieva, I.M.; Mooney, W.D.; Perchuc, E.; Thybo, H.


    We discuss the structure of the continental lithosphere, its physical properties, and the mechanisms that formed and modified it since the early Archean. The structure of the upper mantle and the crust is derived primarily from global and regional seismic tomography studies of Eurasia and from global and regional data on seismic anisotropy. These data as documented in the papers of this special issue of Tectonophysics are used to illustrate the role of different tectonic processes in the lithospheric evolution since Archean to present. These include, but are not limited to, cratonization, terrane accretion and collision, continental rifting (both passive and active), subduction, and lithospheric basal erosion due to a relative motion of cratonic keels and the convective mantle. ?? 2002 Elsevier Science B.V. All rights reserved.

  11. Crustal response to lithosphere evolution

    Artemieva, Irina; Thybo, Hans; Cherepanova, Yulia;


    assessed results from various seismic studies, including reflection and refraction profiles and receiver function studies. The region includes a nearly continuous age record for crustal evolution over ca. 3.6-3.8 billion years. We present an analysis of the crustal structure heterogeneity in relation......We present a new model for the structure of the crust in an area which stretches from the North Atlantic region in the west to the Verkhoyansk Ridge in the east and encompasses Greenland, Iceland, most of Europe, West Siberian basin, and the Siberian cratons. The model is based on critically...... to geological and tectono-thermal ages of the crust, and the tectonic setting. The results indicate that the Precambrian crust is as heterogeneous as Phanerozoic, and we do not observe any evidence for thickening from the Archean to Proterozoic crust. If anything, our analysis rather suggests the opposite trend...

  12. Foundering lithosphere imaged beneath the southern Sierra Nevada, California, USA.

    Boyd, Oliver S; Jones, Craig H; Sheehan, Anne F


    Seismic tomography reveals garnet-rich crust and mantle lithosphere descending into the upper mantle beneath the southeastern Sierra Nevada. The descending lithosphere consists of two layers: an iron-rich eclogite above a magnesium-rich garnet peridotite. These results place descending eclogite above and east of high P wave speed material previously imaged beneath the southern Great Valley, suggesting a previously unsuspected coherence in the lithospheric removal process. PMID:15286370

  13. Intraplate Harrat Volcanism and Neogene Evolution of the Lithosphere-Asthenosphere Boundary beneath Western Saudi Arabia

    Kent, A. J.; Duncan, R. A.; Graham, D. W.; Al-Amri, A. M.; Alshalntoni, S. A.


    Continental extension is a fundamental plate tectonic process, and extensional environments are associated with significant production of basaltic magmas. Although tholeiitic magmatism produced by mantle decompression is common, dispersed, less voluminous and compositionally variable basaltic and related magmas also occur in association with continental extension. One of the most voluminous, best-preserved and least studied examples of the latter is the volcanic harrats of western Saudi Arabia. Uplift, crustal erosion and harrat volcanism occurred from ~15 Ma to recent over a considerable region of western Arabia. Volcanism trends north from the Red Sea along the Makkah-Madinah-Nafud (MMN) line as a number of discrete harrats, and geophysical evidence suggests this region is underlain by hot upwelling asthenosphere. Larger harrats occur along the central axis of the MMN line, with smaller fields on the periphery. We present initial results of an ongoing study of harrat volcanism, including more than 50 new 40Ar-39Ar ages together with geochemical and isotopic data. Magma storage and fractionation appears to have occurred at a range of crustal levels, including deep storage and transport sufficiently rapid to preserve a range of lithospheric and crustal xenoliths. Melting commenced within the garnet peridotite field, however modeling of REE element abundances suggest that considerable differences exist in the thickness of the overlying lithospheric lid. Thinner lithosphere (line, whereas harrats peripheral to the MMN line have thicker lithosphere (>60-80 km) and magmas result from lower degree melts. The observed variability can be explained by a process of progressively thinning lithosphere along the main axis of the MMN line, as a result of regional lithospheric extension and mantle decompression melting, coupled with northward asthenospheric flow from the Red Sea and/or Afar hot spot.

  14. Simultaneous estimation of lithospheric uplift rates and absolute sea level change in southwest Scandinavia from inversion of sea level data

    Nielsen, Lars; Hansen, Jens Morten; Hede, Mikkel Ulfeldt;


    Relative sea level curves contain coupled information about absolute sea level change and vertical lithospheric movement. Such curves may be constructed based on, for example tide gauge data for the most recent times and different types of geological data for ancient times. Correct account for...... vertical lithospheric movement is essential for estimation of reliable values of absolute sea level change from relative sea level data and vise versa. For modern times, estimates of vertical lithospheric movement may be constrained by data (e.g. GPS-based measurements), which are independent from the...... relative sea level data. Similar independent data do not exist for ancient times. The purpose of this study is to test two simple inversion approaches for simultaneous estimation of lithospheric uplift rates and absolute sea level change rates for ancient times in areas where a dense coverage of relative...

  15. Elastic expansion of the lithosphere caused by groundwater depletion

    Several centimeters of man-induced elastic expansion of the lithosphere is inferred to have been caused by the depletion and removal from the area of large masses of groundwater in parts of Arizona, California, and Texas. The water was removed principally by evapotranspiration by crops of groundwater pumped from aquifers. Arguments for elastic expansion are based on both theoretical estimates and comparison with the elastic deformations observed at Lake Mead and Lake Kariba, where comparable masses of water were loaded on the earth's surface. In one area, south central Arizona, 6 cm of crustal uplift observed from 198 to 1967 may be related to the removal of 4 4.35 x 1013 kg of groundwater. First, if the observed uplift is assumed to be due to man-induced unloading, a Young's modulus of the lithosphere of approximately 0.68 Mbar is implied, which is comparable to values reported elsewhere. Second, the uplift compares favorably with the depression caused by the formation of Lake Mead, 430 km northwest of the study area, when allowance is made for the different magnitudes, sense, and areas of surface loading

  16. Microplate transfer by lithospheric coupling forces at the plate boundary

    Plattner, C.; Malservisi, R.; Govers, R.; Iaffaldano, G.


    The Baja California (BAJA) microplate was ruptured from the North American (NAM) plate ~ 12 Ma ago and since then translated with the Pacific (PAC) plate. The microplates' transport mechanism has been explained by partial coupling with the PAC plate. According to this theory, the young oceanic lithosphere from the Farallon-Pacific spreading center approaching North America was too buoyant to be subducted. Therefore a zone of increased lithospheric coupling developed between the partially subducted Farallon slabs and the overlying NAM margin. In consequence both, the subduction and the seafloor spreading slowed down and ceased. With the development of this coupling region west of BAJA the main PAC-NAM plate boundary jumped inland east of BAJA, first delocalized in the Protogulf extensional province, and later localized along the Gulf of California. We use a numerical modeling technique to test the dynamic conditions of BAJA transport as seen from present-day and from geologic plate motion studies. Using the kinematic data we test the necessary coupling forces for BAJA transport, as well as, geometrical constraints along the PAC-BAJA coupling zone. Evaluating the transport conditions at different stages of the plate boundary evolution, we want to learn about necessary pre-conditions for the BAJA transfer.

  17. Lithospheric models of the North American continent

    Tesauro, Magdala; Kaban, Mikhail; Mooney, Walter; Cloetingh, Sierd


    We constructed NACr14, a 3D model of the North American (NA) crust, based on the most recent seismic data from the USGS database. In comparison with the global crustal model CRUST 1.0, NACr14 is more heterogeneous, showing a larger spatial variability of the thickness and average velocities of the crustal layers. Velocities of the lower crust vary in a larger range than those of the other layers, while the thickness of all the three layers is on average between 11 and 13 km. The largest velocities of the crystalline crust (>6.6 km/s) reflect the presence of a 7.x layer (>7.0 km/s) in the lowermost part of the crust. Using NACr2014, a regional (NA07) and a global (SL201sv) tomography model, and gravity data, we apply an iterative technique, which jointly interprets seismic tomography and gravity data, to estimate temperature and compositional variations in the NA upper mantle. The results obtained demonstrate that temperature of the cratonic mantle is up to 150°C higher than when using a uniform compositional model. The differences between the two tomography models influence the results more strongly than possible changes of the depth distribution of compositional variations. Strong negative compositional density anomalies, corresponding to Mg # >92, characterize the upper mantle of the northwestern part of the Superior craton and the central part of the Slave and Churchill craton. The Proterozoic upper mantle of the western and more deformed part of the NA cratons, appears weakly depleted (Mg# ~91) when NA07 is used, in agreement with the results based on the interpretation of xenolith data. When we use SL2013sv, the same areas are locally characterized by high density bodies, which might be interpreted as the effect due to fragments of subducted slabs, as those close to the suture of the Appalachians and Grenville province. We used the two thermal models to estimate the integrated strength and the effective elastic thickness (Te) of the lithosphere. In the

  18. Sub-lithospheric small scale convection - a process for continental collision magmatism

    Kaislaniemi, Lars; van Hunen, Jeroen; Allen, Mark; Neill, Iain


    We have studied the role of sub-lithospheric small scale convection in the generation of collision zone magmatism, using combined geodynamic-petrological models. We compare the results with the collisional magmatism of the Turkish-Iranian plateau, where a number of randomly (in both space and time) distributed volcanic centres on has been produced by the active Arabia-Eurasia collision since initial plate collision at ~27-35 Ma. These volcanic rocks have a highly variable geochemical signature, but commonly point to a lithospheric mantle or asthenospheric source. Major and trace element characteristics span the range from OIB-like, to calc-alkali, shoshonitic and even ultrapotassic. We suggest these spatially, temporally and chemically diverse patterns of volcanism are caused by sub-lithospheric small scale convection (SSC), manifested as small (50 to 300 km) convection cells at the lithosphere-asthenosphere boundary and dripping of the lithospheric mantle into the asthenosphere. SSC is activated by the increased amount of water in the lithospheric and asthenospheric mantle and its rheological weakening effect. The increase in water content is caused by the subduction prior to the collision and/or continental subduction during collision. The mantle convection code CitCom, together with a parameterized melting model, is used to model the SSC process. We relate the water content to the mantle solidus and viscosity, and the amount of depletion to the viscosity and buoyancy of the mantle material. We measure the amount of magmatism taking place by assuming direct and instantaneous percolation of mantle melts to the surface. We mimic the dislocation creep mechanism with a diffusion creep mechanism using low activation energy--either one is needed for the SSC to take place under realistic conditions. Results show that SSC is able to produce small degrees (0-2 %) of melting of the mantle through dripping lithosphere, decompression melting, erosion of the overlying

  19. Family agriculture for bottom-up rural development: a case study of the indigenous Mayan population in the Mexican Peninsula

    Krishnamurthy, Laksmi Reddiar; Krishnamurthy, Sumithra


    Since pre-colonial times the indigenous communities of Mayan origin in the state of Quintana Roo, Mexico, widely practice home gardens on a sustainable basis as the principal form of family agriculture. This study analyzes the structural complexity, functional diversity and management strategy of these indigenous home gardens in order to attempt to propose recommendations for improved family farming. The Mayan home gardens are structured into three or more vertical layers of multiple plant sp...

  20. Biogenic reefs affect multiple components of intertidal soft-bottom benthic assemblages: The Lanice conchilega case study

    De Smet, B; D'Hondt, A.-S.; Verhelst, P.; Fournier, J.; Godet, L.; Desroy, N.; Rabaut, M.; Vincx, M.; Vanaverbeke, J.


    Biogenic reefs composed of the tube-building polychaete Lanice conchilega are important from a conservation point of view because they noticeably increase the biodiversity in otherwise species poor environments. However, up to now, little or no attention has been paid to the intertidal epi- and hyperbenthic communities associated with the reefs. Therefore, this is the first study which focuses on the effect of L. conchilega reefs on the entire bentho-pelagic community at two different locatio...

  1. Cratonic lithospheric mantle: Is anything subducted?

    William L. Griffin; Suzanne Y. O'ReiUy


    @@ If the subcontinental lithospheric mantle (SCLM) formed through the repeated underthrusting of oceanic slabs, peridotitic SCLM should resemble oceanic peridotites, and mafic rocks (eclogites, s.l.) should be distributed throughout the SCLM. However, cratonic peridotites (both exposed massifs and xenoliths) differ markedly from oceanic and ophiolitic peridotites in their Fe-Cr-Al relationships and abundances of trace elements (Li and B) diagnostic of subduction. "Typical"cratonic peridotites have experienced extensive metaso matism; modelling of their refractory protoliths indicates high-degree melting at high P, perhaps a uniquely Archean process.

  2. On studying protein phosphorylation patterns using bottom-up LC-MS/MS: the case of human alpha-casein

    Kjeldsen, Frank; Savitski, Mikhail M; Nielsen, Michael L;


    occupancy rates of phosphosites in proteins may differ by orders of magnitude, and thus the occupancy rate must be reported for each occupied phosphosite. To highlight potential pitfalls in quantifying the occupancy rates, alpha(s1)-casein from human milk was selected as a model molecule representing...... moderately phosphorylated proteins. For this purpose, human milk from one Caucasian woman in the eighth month of lactation was used. The phosphorylation level of caseins is believed to have major implications for the formation of micelles that are involved in delivering valuable calcium phosphate and other...... minerals to the new-born. Human alpha(s1)-casein has been reported to be much less phosphorylated than ruminant caseins, which may indicate a different function of caseins in humans. Revealing the phosphorylation pattern in human casein can thus shed light on its function. The current study found that the...

  3. Thermal-rheological structure of lithosphere beneath the northern flank of Tarim Basin, western China:Implications for geodynamics

    LIU; Shaowen; WANG; Liangshu; LI; Cheng; LI; Hua; HAN; Yong


    Based on the data of geo-temperature and thermophysical parameters of rocks in the Kuqa Depression and the Tabei Uplift, northern flank of the Tarim Basin, in terms of the analytical solution of 1-D heat transfer equation, the thermal structure of the lithosphere under this region is determined. Our results show that the average surface heat flow of the northern flank of the Tarim Basin is 45 mW/m2, and the mantle heat flow is between 20 and 23 mW/m2; the temperature at crust-mantle boundary (Moho) ranges from 514℃ to 603℃ and the thermal lithosphere where the heat conduction dominates is 138-182 km thick. Furthermore, in combination with the P wave velocity structure resulting from the deep seismic sounding profile across this region and rheological modeling, we have studied the local composition of the lithosphere and its rheological profile, as well as the strength distribution. We find that the rheological stratification of the lithosphere in this region is apparent. The lowermost of the lower crust is ductile; however,the uppermost of the mantle and the upper and middle parts of the crust are both brittle layers,which is typically the so-called sandwich-like structure. Lithospheric strength is also characterized by the lateral variation, and the uplift region is stronger than the depression region. The lithospheric strength of the northem flank of the Tarim Basin decreases gradually from south to north; the Kuqa Depression has the lowest strength and the south of the Tabei Uplift is strongest.The total lithospheric strength of this region is 4.77× 1012-5.03 × 1013 N/m under extension, and 6.5 × 1012-9.4× 1013 N/m under compression. The lithospheric brittle-ductile transition depth is between 20 km and 33 km. In conclusion, the lithosphere of the northern flank of the Tarim Basin is relatively cold with higher strength, so it behaves rigidly and deforms as a whole, which is also supported by the seismic activity in this region. This rigidity of the

  4. Biogenic reefs affect multiple components of intertidal soft-bottom benthic assemblages: the Lanice conchilega case study

    De Smet, Bart; D'Hondt, An-Sofie; Verhelst, Pieterjan; Fournier, Jérôme; Godet, Laurent; Desroy, Nicolas; Rabaut, Marijn; Vincx, Magda; Vanaverbeke, Jan


    Biogenic reefs composed of the tube-building polychaete Lanice conchilega are important from a conservation point of view because they noticeably increase the biodiversity in otherwise species poor environments. However, up to now, little or no attention has been paid to the intertidal epi- and hyperbenthic communities associated with the reefs. Therefore, this is the first study which focuses on the effect of L. conchilega reefs on the entire bentho-pelagic community at two different locations. Environmental variables were measured and macro-, epi- and hyperbenthic communities were sampled within a L. conchilega reef and a control area at two locations in France: the bay of the Mont Saint-Michel (BMSM) and Boulogne-sur-Mer (Boulogne). The effect of the reef presence on the benthic community was studied with a 3-factor (Reef, Location and Period) Permanova. In addition, the relationship between the benthic community and the environmental variables was investigated using Distance-based linear models (DistLM). Most collected organisms were sampled in the reef area (macrobenthos: 91%, epibenthos: 81% and hyperbenthos: 78.5%) indicating that, independent of the location, the L. conchilega reefs positively affect all three associated benthic communities. However, the extent of the effect seems to be most pronounced for the macrobenthos and less distinct in case of the hyperbenthos. The macro-, and epibenthos are mainly structured by biotic variables (L. conchilega density and macrobenthic food availability respectively), while the hyperbenthos is rather structured by environmental variables. In general, L. conchilega reefs do not only affect abundances and diversity but they substantially steer the structure of the intertidal benthic sandy beach ecosystem.

  5. Plate Tectonics Initiation on Earth-Like Planets: Insights From Numerical and Theoretical Analysis of Convection-Induced Lithospheric Failure

    Wong, Teresa

    Plate tectonics is central to many aspects of the geology and evolution of terrestrial planets, yet it is only observed on the Earth while all other known planets are covered with a stagnant lithosphere. Plate motions on the Earth are mostly driven by the pull of subducting slabs, therefore understanding the initiation of subduction is crucial to understanding plate tectonics initiation. On a one-plate planet which lacks the forces due to plate motions, some other mechanisms will have to cause the first episode of subduction to mobilize the surface. Sublithospheric convection has been proposed as a possible mechanism that induce stresses in the lithosphere. The question is whether these stresses can initiate subduction. We develop scaling laws for the criterion of lithospheric failure from single-cell steady-state convection, which has more controlled flow and thus easier to analyze. We show that these scaling laws are applicable to time-dependent convection. We also investigate the time-dependent behavior of convection to understand the factors controlling the timing of lithospheric failure. We find that the variation in timing not only systematically depends on the physical parameters of the convecting mantle; for convective systems with the same set of parameters, small variations in initial conditions result in different structures of the lithosphere. This changes the stresses in the lithosphere and gives rise to different times of lithospheric failure. This study suggests that it is important to address the question of when plate tectonics can initiate on a planet, in addition to finding favorable conditions for lithospheric failure. We extrapolate the scaling laws to planetary conditions to assess the feasibility of plate tectonics for terrestrial planets, and estimate whether plate tectonics can happen in reasonable planetary lifetimes.

  6. Heat flux and topography constraints on thermochemical structure below North China Craton regions and implications for evolution of cratonic lithosphere

    Wang, Yongming; Huang, Jinshui; Zhong, Shijie; Chen, Jiaming


    The eastern North China Craton (NCC) has undergone extensive reactivation during the Mesozoic and Cenozoic, while the western NCC has remained stable throughout its geological history. Geophysical and geochemical observations, including heat flux, surface topography, crustal and lithospheric thicknesses, and volcanism, show significant contrast between the eastern and western NCC. These observations provide constraints on thermochemical structure and reactivation process of the eastern NCC, thus helping understand the dynamic evolution of cratonic lithosphere. In this study, we determined the residual topography for the NCC region by removing crustal contribution to the topography. We found that the residual topography of the eastern NCC region is generally 0.3-0.9 km higher than the western NCC. We computed a large number of two-dimension thermochemical convection models for gravitational instability of cratonic lithosphere and quantified surface heat flux and topography contrasts between stable and destabilized parts of cratonic lithosphere. These models consider different chemical buoyancy (i.e., buoyancy number B) and viscosity for the cratonic lithosphere. Our models suggest that to explain the difference in heat flux (25-30 mW/m2) and residual topography (0.3-0.9 km) between the eastern and western NCC regions, the buoyancy number B is required to be ~0.3-0.4. This range of B implies that as much as 50% of the original cratonic lithospheric material remains in the present-day eastern NCC lithosphere and its underlying shallow mantle and that the new lithosphere in the eastern NCC may be a mixture of the relics of old craton materials and the normal mantle.

  7. The crust and lithosphere thicknesses of Greenland revisited: what do recent gravity data tell us?

    Steffen, Rebekka; Lund, Björn


    Crustal and lithospheric thicknesses are nowadays extensively studied and several datasets exist for most parts of the Earth; however, for some regions only a few estimations are available. For high resolution models of glacial isostatic adjustment (GIA), the thickness of the crust and lithosphere beneath the glaciated regions are very important as they affect the calculation of past and future sea level changes. Greenland, with its decreasing ice sheet and rapidly retreating outlet glaciers, is one such region where the GIA estimation is important but where the ice sheet itself prevents extensive studies of the crustal and lithospheric thicknesses. Most of the thickness estimates have so far been obtained from seismological studies, which depend on the density of the station networks. We will present newly obtained crustal and lithospheric thickness maps, which are estimated from gravity data using the Parker-Oldenburg inversion algorithm. The gravity dataset will be presented together with all the necessary corrections which have to be applied before the inversion procedure. The obtained thickness maps will be compared to former results of seismological and gravimetric studies and differences will be discussed, also from a geodynamic point of view.

  8. Tidal signals in ocean-bottom magnetic measurements of the Northwestern Pacific: observation versus prediction

    Schnepf, N. R.; Manoj, C.; Kuvshinov, A.; Toh, H.; Maus, S.


    Motional induction in the ocean by tides has long been observed by both land and satellite measurements of magnetic fields. While these signals are weak (˜10 nT) when compared to the main magnetic field, their persistent nature makes them important for consideration during geomagnetic field modelling. Previous studies have reported several discrepancies between observations and numerical predictions of the tidal magnetic signals and those studies were inconclusive of the source of the error. We address this issue by (1) analysing magnetometer data from ocean-bottom stations, where the low-noise and high-signal environment is most suitable for detecting the weak tidal magnetic signals, (2) by numerically predicting the magnetic field with a spatial resolution that is 16 times higher than the previous studies and (3) by using four different models of upper-mantle conductivity. We use vector magnetic data from six ocean-bottom electromagnetic (OBEM) stations located in the Northwestern Pacific Ocean. The OBEM tidal amplitudes were derived using an iteratively re-weighted least-squares (IRLS) method and by limiting the analysis of lunar semidiurnal (M2), lunar elliptic semidinurnal (N2) and diurnal (O1) tidal modes to the night-time. Using a 3-D electromagnetic induction solver and the TPX07.2 tidal model, we predict the tidal magnetic signal. We use earth models with non-uniform oceans and four 1-D mantle sections underneath taken from Kuvshinov and Olsen, Shimizu et al. and Baba et al. to compare the effect of upper-mantle conductivity. We find that in general, the predictions and observations match within 10-70 per cent across all the stations for each of the tidal modes. The median normalized percent difference (NPD) between observed and predicted amplitudes for the tidal modes M2, N2 and O1 were 15 per cent, 47 per cent and 98 per cent, respectively, for all the stations and models. At the majority of stations, and for each of the tidal modes, the higher

  9. Numerical Analysis and Simulation Experiment of Lithospheric Thermal Structures in the South China Sea and the Western Pacific

    Lin Ge; Peng Meili; Zhao Chongbin; Zhang Lu; Zhang Desheng; Liu Shilin


    The asthenosphere upwelled on a large scale in the western Pacific and South China Sea during the Cenozoic,which formed strong upward throughflow and caused the thermal structure to be changed obviously.The mathematical analysis has demonstrated that the upward throughflow velocity may have varied from 3×1011 to 6×1012 m/s.From the relationship between the lithospheric thickness and the conductive heat flux,the Hthospherie heat flux in the western Pacific should be above 30 mW/m2,which is consistent with the observed data.The huge low-speed zone within the upper mantle of the marginal sea in the western Pacific reflects that the upper mantle melts partially,flows regionally in the regional stress field,forms the upward heat flux at its bottom,and causes the change of the lithospheric thermal structure in the region.The numerical simulation result of the expansion and evolution in the South China Sea has demonstrated that in the early expansion,the upward throughflow velocity was relatively fast,and the effect that it had on the thickness of the lithosphere was relatively great,resulting in the mid-ocean basin expanding rapidly.After the formation of the ocean basin in the South China Sea,the upward throughflow velocity decreased,but the conductive heat flux was relatively high,which is close to the actual situation.Therefore,from the heat transfer point of view,this article discusses how the upward heat flux affects the lithospheric thermal structure in the western Pacific and South China Sea.The conclusions show that the upward heat throughflow at the bottom of the llthospheric mantle resulted in the tectonic deformation at the shallow crust.The intensive uplifts and rifts at the crust led to the continent cracks and the expansion in the South China Sea.


    Lidia V. Solov’eva; Tatiana V. Kalashnikova; Sergei I. Kostrovitsky; Alexei V. Ivanov; Stanislav S. Matsuk; Ludmila F. Suvorova


    The area of studies covers the north-eastern part of the Siberian craton (the Birekte terrain), Russia. The influence of metasomatic and magmatic processes on the mantle lithosphere is studied based on results of analyses of phlogopite- and phlogopite-amphibole-containing deep-seated xenoliths from kimberlites of the Kuoika field. In the kimberlitic pipes, deep-seated xenoliths with mantle phlogopite- and phlogopite-amphibole mineralization are developed in two genetically different rock seri...

  11. Lithosphere mapping beneath the North American plate

    Griffin, W. L.; O'Reilly, Suzanne Y.; Doyle, B. J.; Pearson, N. J.; Coopersmith, H.; Kivi, K.; Malkovets, V.; Pokhilenko, N.


    Major- and trace-element analyses of garnets from heavy-mineral concentrates have been used to derive the compositional and thermal structure of the subcontinental lithospheric mantle (SCLM) beneath 16 areas within the core of the ancient Laurentian continent and 11 areas in the craton margin and fringing mobile belts. Results are presented as stratigraphic sections showing variations in the relative proportions of different rock types and metasomatic styles, and the mean Fo content of olivine, with depth. Detailed comparisons with data from mantle xenoliths demonstrate the reliability of the sections. In the Slave Province, the SCLM in most areas shows a two-layer structure with a boundary at 140-160 km depth. The upper layer shows pronounced lateral variations, whereas the lower layer, after accounting for different degrees of melt-related metasomatism, shows marked uniformity. The lower layer is interpreted as a subcreted plume head, added at ca. 3.2 Ga; this boundary between the layers rises to <100 km depth toward the northern and southern edges of the craton. Strongly layered SCLM suggests that plume subcretion may also have played a role in the construction of the lithosphere beneath Michigan and Saskatchewan. Outside the Slave Province, most North American Archon SCLM sections are less depleted than similar sections in southern Africa and Siberia; this may reflect extensive metasomatic modification. In E. Canada, the degree of modification increases toward the craton margin, and the SCLM beneath the Kapuskasing Structural Zone is typical of that beneath Proterozoic to Phanerozoic mobile belts. SCLM sections from several Proterozoic areas around the margin of the Laurentian continental core (W. Greenland, Colorado-Wyoming district, Arkansas) show discontinuities and gaps that are interpreted as the effects of lithosphere stacking during collisional orogeny. Some areas affected by Proterozoic orogenesis (Wyoming Craton, Alberta, W. Greenland) appear to retain

  12. An experimental study on effective depressurization actions for PWR vessel bottom small break LOCA with HPI failure and gas inflow (ROSA-V test SB-PV-04)

    A small break loss-of-coolant accident (SBLOCA) experiment was conducted at the Large Scale Test Facility (LSTF) of ROSA-V program to study effects of accident management (AM) measures on core cooling, which are important in case of total failure of high pressure injection (HPI) system during an SBLOCA at a pressurized water reactor (PWR). The LSTF is a full-height and 1/48 volume-scaled facility simulating a 4-loop Westing-house-type PWR (3423 MWt). The experiment, SB-PV-04, simulated a PWR vessel bottom SBLOCA with a rupture of ten instrument-tubes which is equivalent to 0.2% cold leg break. It is clarified that AM actions with steam generator (SG) rapid depressurization by fully opening relief valves and auxiliary feedwater supply are effective to avoid core uncovery by actuating the low pressure injection (LPI) system though the primary depressurization is degraded by non-condensable gas inflow to the primary loops from the accumulator injection system. The effective core cooling was established by the rapid depressurization which contributed to preserve larger primary coolant mass than in the previous experiment (SB-PV-03) which was conducted with smaller primary cooling rate of -55 K/h as AM actions. (author)

  13. Comparative study of predatory responses in blue mussels ( Mytilus edulis L.) produced in suspended long line cultures or collected from natural bottom mussel beds

    Christensen, Helle Torp; Dolmer, Per; Petersen, Jens Kjerulf; Tørring, Ditte


    Blue mussels ( Mytilus edulis L.) are a valuable resource for commercial shellfish production and may also have uses as a tool in habitat improvement, because mussel beds can increase habitat diversity and complexity. A prerequisite for both commercial mussel production and habitat improvement is the availability of seed mussels collected with minimum impact on the benthic ecosystem. To examine whether mussels collected in suspended cultures can be used for bottom culture production and as tool in habitat improvement, the differences in predatory defence responses between suspended and bottom mussels exposed to the predatory shore crab ( Carcinus maenas L.) were tested in laboratory experiments and in the field. Predatory defence responses (byssal attachment and aggregation) and morphological traits were tested in laboratory, while growth and mortality were examined in field experiments. Suspended mussels had an active response in relation to the predator by developing a significantly firmer attachment to the substrate and a closer aggregated structure. Bottom mussels had a passive strategy by having a thicker shell and larger relative size of the adductor muscle. In a field experiment mussels originated from suspended cultures had a higher length increment and lower mortality when compared to bottom mussels. It is concluded that suspended mussels potentially are an alternative resource to bottom culture and can be used in habitat improvement of mussel beds, but that the use of suspended mussels has to be tested further in large-scale field experiments.

  14. Improving the modelling of the lithospheric field at all scales for the benefit of geophysical interpretations

    Complete text of publication follows. During the last years, the geographical coverage of magnetic fields improved thanks to the release of old and new data acquired from the Earth's surface to the satellite altitudes. Concerted international efforts to compile and publish these data in a digital format, like the World Digital Magnetic Anomaly Map (WDMAM) project, represented a key motivation for also improving our methods for interpreting and modelling marine, airborne and satellite data. Thus, these unprecedented high spatial resolution data also challenged our ability 1) to extract accurately the contribution of the lithospheric field from the total measurements, 2) to represent the data with potential field modelling technique capable of merging locally all kinds of data, 3) and to interpret these models in terms of sources distribution and depth, heat flow, etc... I will first briefly review recent advances made towards improving the marine and aeromagnetic compilations at the worldwide scale. Then, I will focus on the other end of the lithospheric magnetic field spectrum and discuss the consistency of various recent satellite-based lithospheric field models. This will allow me to illustrate the ambiguities and compatibility issues that remain to be addressed before we can successfully merge near surface and satellite data. Then, I will report on different studies carried out to interpret lithospheric magnetic field models in terms of tectonic, and discuss some original methods employed to estimate local and average properties of the Earth's magnetic crust.

  15. Petrography and Geochemistry of Peridotite Xenoliths from Hannuoba and Significance for Lithospheric Mantle Evolution


    The compositions of the whole rocks and trace elements of minerals in peridotites can reflect the characteristics of the lithospheric mantle. The nature and evolution of the Cenozoic lithospheric mantle beneath Hannuoba (汉诺坝), located on the north edge of the intra-North China orogenic belt,are discussed based on the in-situ LAM-ICPMS detected trace element compositions of clinopyroxenes in the Hannuoba peridotitic xenoliths combined with detailed petrography and geochemistry studies. The Hannuoba lithospheric mantle was formed by different partial meltings of the primitive mantle. Most of the samples reflect the partial melting degree of lower than 5% with a few samples of 15%-20%.Major element compositions of the whole rocks and geochemical compositions of clinopyroxenes reveal the coexistence of both fertile and depleted mantle underneath the Hannuoba region during the Cenozoic.This was probably caused by the asthenospheric mantle replacing the aged craton mantle through erosion,intermingling and modification. Our conclusion is further supported by the existence of both carbonatitic magmatic material and silicate melt/fluid metasomatism as magnified by the trace elements of the clinopyroxenes from the Hannuoba lithospheric mantle.

  16. Coupling between different layers of the lithosphere under horizontal drag underneath

    宁杰远; 臧绍先; 王曙光; 魏荣强; 梁国平


    Based on a layered rheological model of the lithosphere, the velocity and stress distributions in the lithosphere under horizontal drag underneath were calculated using viscoelastic finite element method of plain strain with finite deformation. In the simulation, different conditions of drag and blocking were assumed to study their influences on the stress distribution and the coupling between different layers. Blocking depth has little influence on the stress level in the whole area and the coupling between different layers, but influences the stress state in the area around the blocking. The area covered by the high stress anomaly becomes larger when the blocking depth becomes deeper, but the magnitude of the value of the maximum shear stress decreases. The greater the viscosity differences between different layers of the lithosphere, the greater the possibility of decoupling between them. Under the drag of normal mantle convection (the convection velocity is about 20 cm·a?1), a lithosphere with a rheological structure similar to that of North China could not have decoupling between different layers, while could have stress distribution with magnitude of several MPa to tens of MPa and could have anomalous areas with stress accumulation if the geological structure is complicated.

  17. Melt-rich channel observed at the lithosphere-asthenosphere boundary.

    Naif, S; Key, K; Constable, S; Evans, R L


    The lithosphere-asthenosphere boundary (LAB) separates rigid oceanic plates from the underlying warm ductile asthenosphere. Although a viscosity decrease beneath this boundary is essential for plate tectonics, a consensus on its origin remains elusive. Seismic studies identify a prominent velocity discontinuity at depths thought to coincide with the LAB but disagree on its cause, generally invoking either partial melting or a mantle dehydration boundary as explanations. Here we use sea-floor magnetotelluric data to image the electrical conductivity of the LAB beneath the edge of the Cocos plate at the Middle America trench offshore of Nicaragua. Underneath the resistive oceanic lithosphere, the magnetotelluric data reveal a high-conductivity layer confined to depths of 45 to 70 kilometres. Because partial melts are stable at these depths in a warm damp mantle, we interpret the conductor to be a partially molten layer capped by an impermeable frozen lid that is the base of the lithosphere. A conductivity anisotropy parallel to plate motion indicates that this melt has been sheared into flow-aligned tube-like structures. We infer that the LAB beneath young plates consists of a thin, partially molten, channel of low viscosity that acts to decouple the overlying brittle lithosphere from the deeper convecting mantle. Because this boundary layer has the potential to behave as a lubricant to plate motion, its proximity to the trench may have implications for subduction dynamics. PMID:23518564

  18. The Vaendoera test road, Sweden: A case study of long-term properties of roads constructed with MSWI bottom ash; Projekt Vaendoera: En studie av laangtidsegenskaper hos vaegar anlagda med bottenaska fraan avfallsfoerbraenning

    Bendz, David; Arm, Maria; Westberg, Gunnar; Sjoestrand, Karin; Lyth, Martin; Wik, Ola [Swedish Geotechnical Inst., Linkoeping (Sweden); Flyhammar, Peter [Lund Inst. of Technology (Sweden). Dept. of Water Resources Engineering


    The accumulated effects of leaching and aging in a subbase layer of bottom ash were investigated in this study. The paved test road were constructed in 1987 in Linkoeping, Sweden, and has been used until the start of this study. The objective of this study was to investigate: (i) the accumulated effects of leaching and aging (ii) the accumulated effects of load and aging on the geotechnical properties (iii) the prerequisites for separate excavation of the bottom ash for possible reuse. The study started in September 2003 and included tests with falling weight deflectometer, triax testing on undisturbed core samples of bottom ash, sampling for chemical analysis. Three trenches were excavated in the test road, samples of the subbase layer and the subgrade were taken in the shaft walls and brought to the laboratory for leaching tests (EN 12457-2) and extraction, respectively. The extraction procedure was used to estimate extractable and chemically available fractions. It was found that the steady increase of stiffness which had been detected by falling weight deflectometer during the first years after construction had ceased. The undisturbed samples showed stiffness comparable with recently produced bottom ash from the same incineration plant, but lower stiffness if compared with the reference material of crushed rock. The permanent deformation was significantly larger for the samples compared with the crushed rock and recent (1999-2001) bottom ash from other incineration plants. The spatial distribution patterns of leachable easily soluble constituents reveal the existence of horizontal gradients, directed from the center of the road towards the shoulders of the road. This implies that horizontal transport by diffusion is the rate limiting leaching process for all easily soluble constituents underneath the pavement in a road. The bottom ash that was used in the sub-base layer was fresh at the time of the construction of the test road with a pH of about 11. Measured p

  19. Lithospheric structure of Venus from gravity and topography

    Jiménez-Díaz, Alberto; Ruiz, Javier; Kirby, Jon F.; Romeo, Ignacio; Tejero, Rosa; Capote, Ramón


    There are many fundamental and unanswered questions on the structure and evolution of the venusian lithosphere, which are key issues for understanding Venus in the context of the origin and evolution of the terrestrial planets. Here we investigate the lithospheric structure of Venus by calculating its crustal and effective elastic thicknesses (Tc and Te, respectively) from an analysis of gravity and topography, in order to improve our knowledge of the large scale and long-term mechanical behaviour of its lithosphere. We find that the venusian crust is usually 20-25 km thick with thicker crust under the highlands. Our effective elastic thickness values range between 14 km (corresponding to the minimum resolvable Te value) and 94 km, but are dominated by low to moderate values. Te variations deduced from our model could represent regional variations in the cooling history of the lithosphere and/or mantle processes with limited surface manifestation. The crustal plateaus are near-isostatically compensated, consistent with a thin elastic lithosphere, showing a thickened crust beneath them, whereas the lowlands exhibit higher Te values, maybe indicating a cooler lithosphere than that when the venusian highlands were emplaced. The large volcanic rises show a complex signature, with a broad range of Te and internal load fraction (F) values. Finally, our results also reveal a significant contribution of the upper mantle to the strength of the lithosphere in many regions.

  20. Understanding lithospheric stresses: systematic analysis of controlling mechanisms with applications to the African Plate

    Medvedev, Sergei


    Many mechanisms control the state of stress within Earth plates. First-order well-known mechanisms include stresses induced by lateral variations of lithospheric density structure, sublithospheric tractions, ridge push, and subduction pull. In this study, we attempt to quantify the influence of these mechanisms to understand the origin of stresses in the lithosphere, choosing the African plate (TAP) as an example. A finite-element based suite, Proshell, was developed to combine several data sets, to estimate the gravitational potential energy (GPE) of the lithosphere, and to calculate stresses acting on the real (non-planar) geometry of TAP. We introduce several quantitative parameters to measure the degree of fit between the model and observations. Our modelling strategy involves nine series of numerical experiments. We start with the simplest possible model and then, step by step, build it up to be a more physically realistic model, all the while discussing the influence of each additional component. The starting (oversimplified) model series (1) is based on the CRUST2 data set for the crust, and a half-space-cooling approximation of the lithospheric mantle. We then describe models (series 2-5) that account for lithospheric mantle density heterogeneities to build a more reliable GPE model. The consecutive series involve basal traction from the convective mantle (series A, C), and the rheological heterogeneity of the TAP via variations in its effective elastic thickness (series B, C). The model quality reflects the increase in complexity between series with an improving match toobserved stress regimes and directions. The most complex model (series D) also accounts for the bending stresses in the elastic lithosphere and achieves a remarkably good fit to observations. All of our experiments were based on the iteration of controlling parameters in order to achieve the best fit between modelled and observed stresses, always considering physically feasible values. This

  1. Intraplate orogenesis within accreted and scarred lithosphere: Example of the Eurekan Orogeny, Ellesmere Island

    Heron, Philip J.; Pysklywec, Russell N.; Stephenson, Randell


    The Eurekan Orogeny, which created much of the high topography of Ellesmere Island and adjacent Greenland, exhibits a crustal architecture linked to intraplate orogenesis in the Cenozoic. It is generally considered that the rotation of Greenland in the Eocene (related to sedimentary basin formation in Baffin Bay) produced compressional intraplate tectonics. Deformation in the region is notably localized to the Central Ellesmere Domain and the Northern Ellesmere Domain. However, an important tectonic feature of Ellesmere Island is the Hazen Stable Block, which shows horizontal Paleogene Eureka Sound group strata overlying Palaeozoic-age steeply dipping beds. The intense deformation in the Hazen Stable Block is related to continental orogenesis in the Late Silurian-Devonian. Therefore, the Hazen Stable Block is thought to have undergone only minor Eurekan-age (55-35 Ma) deformation, while surrounding (highly deformed) units may have re-activated faults from Paleocene continental amalgamation. Here, high-resolution thermal-mechanical numerical experiments are implemented to explore lithospheric deformation (related to continental shortening) for a range of tectonic scenarios, namely, the presence of inherent deformational "scars" and rheologically strengthened crust/mantle lithosphere (both due to ancient continental accretion). This study marks the first geodynamic excursion to this high Arctic region, and we present some of the first interpretations of the development of Eurekan-age lithospheric evolution. Our results show that a rheologically strong Hazen Stable Block crust produces tectonics similar to the Eurekan Orogeny. Furthermore, lithospheric scars can generate more localized deformation and topography than rheological changes to the lithosphere and may offer a new interpretation on enigmatic intraplate tectonics.

  2. Anisotropic zonation in the lithosphere of Central North America: Influence of a strong cratonic lithosphere on the Mid-Continent Rift

    Ola, O.; Frederiksen, A. W.; Bollmann, T.; van der Lee, S.; Darbyshire, F.; Wolin, E.; Revenaugh, J.; Stein, C.; Stein, S.; Wysession, M.


    We present shear-wave splitting analyses of SKS and SKKS waves recorded at sixteen Superior Province Rifting Earthscope Experiment (SPREE) seismic stations on the north shore of Lake Superior, as well as fifteen selected Earthscope Transportable Array instruments south of the lake. These instruments bracket the Mid-Continent Rift (MCR) and sample the Superior, Penokean, Yavapai and Mazatzal tectonic provinces. The data set can be explained by a single layer of anisotropic fabric, which we interpret to be dominated by a lithospheric contribution. The fast S polarization directions are consistently ENE-WSW, but the split time varies greatly across the study area, showing strong anisotropy (up to 1.48 s) in the western Superior, moderate anisotropy in the eastern Superior, and moderate to low anisotropy in the terranes south of Lake Superior. We locate two localized zones of very low split time (< 0.6 s) adjacent to the MCR: one in the Nipigon Embayment, an MCR-related magmatic feature immediately north of Lake Superior, and the other adjacent to the eastern end of the lake, at the southern end of the Kapuskasing Structural Zone (KSZ). Both low-splitting zones are adjacent to sharp bends in the MCR axis. We interpret these two zones, along with a low-velocity linear feature imaged by a previous tomographic study beneath Minnesota and the Dakotas, as failed lithospheric branches of the MCR. Given that all three of these branches failed to propagate into the Superior Province lithosphere, we propose that the sharp bend of the MCR through Lake Superior is a consequence of the high mechanical strength of the Superior lithosphere ca. 1.1 Ga.



    Bottom flow energy dissipation is one of the common energydissipation methods for flood-releasing structures with high water head. Measures of this energy dissipation depend mainly on the turbulent action of hydraulic jump.In this paper, the physical process and the calculating methods of the atomization caused by bottom flow energy dissipation were studied, the computation models of atomization quantity for the self-aerated flow in overflow and hydraulic jump regions are presented, and the main results are of theoretical and practical significance for the hydraulic and electric engineering.

  4. Effective elastic thickness of the continental lithosphere in China from heat flow: Implications for the lithospheric rheology and active tectonics

    Liu, S.; Wang, L.


    The effective elastic thickness (Te) of continental lithosphere is one important parameter that describes the response of the lithosphere to long-term loads. However, the estimation of Te is still controversial and various forward and inverse methods have been proposed since the last 20 years. Besides the general application of gravity-topography based inverse method, thermal aspect and related technique is more emphasized, since the mechanical behavior of lithosphere is obviously influenced by temperature. Here we present the effective elastic thickness of the continental lithosphere in China from heat flow data by the method proposed by Burov et al, J. Geophys. Res., 1995, 100(B3):3905-3927. Our results show that Te varies much in different areas of China due to diverse and complicated geological evolution and associated change in thermal regime. Te is much larger than the crustal thickness in the regions where the heat flow is really low (usually less than 50mW/m2) and the lithosphere is relatively thick, indicating much more contribution from the upper mantle to the whole strength of lithosphere. Under this condition, the rheology of the mantle with olivine dominates the deformation manner and processes of the lithosphere and the typical cases in China are those blocks (Tarim, Junggar, Ordos and Sichuan) in central-western China. For instance, the Te of the Tarim basin is 66

  5. Effects of bottom-up and top-down intervention principles in emergent literacy in children at risk of developmental dyslexia: a longitudinal study.

    Helland, Turid; Tjus, Tomas; Hovden, Marit; Ofte, Sonja; Heimann, Mikael


    This longitudinal study focused on the effects of two different principles of intervention in children at risk of developing dyslexia from 5 to 8 years old. The children were selected on the basis of a background questionnaire given to parents and preschool teachers, with cognitive and functional magnetic resonance imaging results substantiating group differences in neuropsychological processes associated with phonology, orthography, and phoneme-grapheme correspondence (i.e., alphabetic principle). The two principles of intervention were bottom-up (BU), "from sound to meaning", and top-down (TD), "from meaning to sound." Thus, four subgroups were established: risk/BU, risk/TD, control/BU, and control/TD. Computer-based training took place for 2 months every spring, and cognitive assessments were performed each fall of the project period. Measures of preliteracy skills for reading and spelling were phonological awareness, working memory, verbal learning, and letter knowledge. Literacy skills were assessed by word reading and spelling. At project end the control group scored significantly above age norm, whereas the risk group scored within the norm. In the at-risk group, training based on the BU principle had the strongest effects on phonological awareness and working memory scores, whereas training based on the TD principle had the strongest effects on verbal learning, letter knowledge, and literacy scores. It was concluded that appropriate, specific, data-based intervention starting in preschool can mitigate literacy impairment and that interventions should contain BU training for preliteracy skills and TD training for literacy training. PMID:21383104

  6. Subduction initiation, recycling of Alboran lower crust, and intracrustal emplacement of subcontinental lithospheric mantle in the Westernmost Mediterranean

    Varas-Reus, María Isabel; Garrido, Carlos J.; Bosch, Delphine; Marchesi, Claudio; Hidas, Károly; Booth-Rea, Guillermo; Acosta-Vigil, Antonio


    Unraveling the tectonic settings and processes involved in the annihilation of subcontinental mantle lithosphere is of paramount importance for our understanding of the endurance of continents through Earth history. Unlike ophiolites -- their oceanic mantle lithosphere counterparts -- the mechanisms of emplacement of the subcontinental mantle lithosphere in orogens is still poorly known. The emplacement of subcontinental lithospheric mantle peridotites is often attributed to extension in rifted passive margins or continental backarc basins, accretionary processes in subduction zones, or some combination of these processes. One of the most prominent features of the westernmost Mediterranean Alpine orogenic arcs is the presence of the largest outcrops worldwide of diamond facies, subcontinental mantle peridotite massifs; unveiling the mechanisms of emplacement of these massifs may provide important clues on processes involved in the destruction of continents. The western Mediterranean underwent a complex Alpine evolution of subduction initiation, slab fragmentation, and rollback within a context of slow convergence of Africa and Europe In the westernmost Mediterranean, the alpine orogeny ends in the Gibraltar tight arc, which is bounded by the Betic, Rif and Tell belts that surround the Alboran and Algero-Balearic basins. The internal units of these belts are mostly constituted of an allochthonous lithospheric domain that collided and overthrusted Mesozoic and Tertiary sedimentary rocks of the Mesozoic-Paleogene, South Iberian and Maghrebian rifted continental paleomargins. Subcontinental lithospheric peridotite massifs are intercalated between polymetamorphic internal units of the Betic (Ronda, Ojen and Carratraca massifs), Rif (Beni Bousera), and Tell belts. In the Betic chain, the internal zones of the allochthonous Alboran domain include, from bottom to top, polymetamorphic rock of the Alpujarride and Malaguide complexes. The Ronda peridotite massif -- the


    I. S. Chuvashova


    Full Text Available A comparative study of major elements, trace elements, and isotopes in high- and moderate-Mg volcanic sequences of 16–14 and 14–13 Ma, respectively, has been performed in the Bereya volcanic center. In the former (small volume sequence, contaminated by crustal material basalts and trachybasalts of K–Na series were followed by uncontaminated basanites and basalts of transitional (K–Na–K compositions and afterwards by picrobasalts and ba­salts of K series. From pressure estimates using equation [Scarrow, Cox, 1995], high-Mg magma originated at the deep range of 115–150 km. In the latter (high-volume sequence, basalts and basaltic andesites of transitional (Na–K–Na compositions and basalts of Na series were overlain by basalts and trachybasalts of K–Na series. First, there was a strong melting of its shallow garnet-free part with coeval weak melting of more deep garnet-bearing portion, then only a deep garnet-bearing portion of the lithospheric mantle melted. It is suggested that the sequential formation of high- and moderate-Mg melts reflected the mid-Miocene thermal impact of the lithosphere by hot material from the Transbaikalian low-velocity domain, which had the potential temperature Tp as high as 1510 °С. This thermal impact triggered the rifting in the lithosphere of the Baikal Rift System.

  8. Determination of the Earth's lithospheric magnetic field with satellite data

    Kotsiaros, Stavros; Olsen, Nils; Finlay, Christopher


    Satellites such as Magsat, Ørsted, CHAMP and Swarm provide the most effective means of determining on a global scale the Earth's lithospheric magnetic field. In particular, the Swarm three-satellite constellation mission aims at capturing the smallest-scale features of the lithospheric field that have ever been captured from space. To achieve that, explicit advantage of the constellation aspect of Swarm has to be taken by using gradient estimates. We derive lithospheric field models using more than one year of magnetic gradient data, which are approximated by first differences of field vector data between the two lower Swarm satellites and along each satellite orbit, respectively. We find that gradient data are less sensitive to large-scale external field fluctuations. Moreover, gradient data appear to be a very efficient way of increasing the resolution of lithospheric field models and thus providing an initial validation of the gradient concept underlying the Swarm mission.

  9. Measurement of bottom-reflected sound in bottom-limited propagation environment

    Hahn, Jooyoung; Park, Joungsoo


    To study the bottom reflection of underwater acoustic sound in a bottom-limited propagation environment, an experiment was conducted using four transmitting sounds in the form of a continuous wave from 1 to 6 kHz. The site of the experiment was a continental shelf region off the east coast of Korea where the bottom was composed of sandy mud. The mean water depth was 1100 m in the experiment area. Oceanographic data and acoustic data were collected simultaneously during the experiment. It was found that the sound pressure level decreased by 90 dB to 3.4 km and there is little frequency dependence because a strong direct path contributes more than a bottom-reflected path in sound pressure level. At a range between 6 and 7 km, there is a strong bottom-reflected ray path and frequency dependence exists because the bottom reflection loss varies with frequency at a given grazing angle. Sound pressure levels increase as the range increases between 6 and 7 km by 5.4, 1.9, 1.7, and 1.5 dB at frequencies of 1000, 2490, 3990, and 5490 Hz, respectively.

  10. Development and validation of HPLC-ICP-MS method for the determination inorganic Cr, As and Sb speciation forms and its application for Pławniowice reservoir (Poland) water and bottom sediments variability study.

    Jabłońska-Czapla, Magdalena; Szopa, Sebastian; Grygoyć, Katarzyna; Łyko, Aleksandra; Michalski, Rajmund


    The optimization of methodology for determination and extraction of inorganic ionic As(III)/As(V), Cr(III)/Cr(VI) and Sb(III)/Sb(V) forms in water and easily-leached fractions of bottom sediments by HPLC-ICP-MS were studied. In paper total concentration of As, Cr, Sb, pH and redox potential were determined. Ions were successfully separated on Dionex IonPac AS7: As(III), As(V), Sb(III), Sb(V) and Dionex IonPac AG7: Cr(III), Cr(VI) with LOD 0.18 μg/L, 0.22 μg/L, 0.009 μg/L, 0.012 μg/L 0.11 μg/L, 0.17 μg/L, respectively. Water and bottom sediments samples were collected monthly from Pławniowice Reservoir, in three-point transects between March and December 2012. In the bottom water predominated As(III) and Cr(III) forms and the highest content of Cr(III) was in the water flowing into the Pławniowice Reservoir. Concentration of Cr(VI) increased in the bottom water in the spring and summer (April-July), while decreasing of the Cr(III) content was associated with the release of Cr(VI) from sediment into the water. Studies have shown that antimony accumulates in reservoir sediments and its reduced form was predominated except May and October-November period when high concentrations of Sb(V) was present. In contrast As(V) was the predominant arsenic form in bottom sediments. PMID:24468399

  11. Lithospheric structure models applied for locating the Romanian seismic events

    Oancea, V.; Popescu, E.; M. Rizescu; Enescu, D.


    The paper presents our attempts made for improving the locations obtained for local seismic events, using refined lithospheric structure models. The location program (based on Geiger method) supposes a known model. The program is run for some seismic sequences which occurred in different regions, on the Romanian territory, using for each of the sequences three velocity models: 1) 7 layers of constant velocity of seismic waves, as an average structure of the lithosphere for the whole territory...

  12. Global lithospheric magnetic field modelling by successive regional anaysis

    E. Thébault;  


    Present lithospheric field models, like the MF4 and CM4, are produced by least squares estimation using spherical harmonic basis functions with global support. Accounting for the different properties of magnetic data at low and high latitudes, a method that can take regional differences into account is proposed. Using four years of CHAMP satellite data, a detailed lithospheric magnetic field snapshot is obtained at 400 km altitude over the entire sphere by stitching together a dense coverage ...

  13. Project WILAS – West Iberia Lithosphere and Astenosphere Structure

    Dias, Nuno; Carrilho, Fernando; Haberland, C.; J. Fonseca; Custódio, S.; Caldeira, Bento; Villaseñor, A.


    The lithosphere of Iberia has been formed through a number of processes of continental collision and extension: in Lower Paleozoic, the collision of three tectonics blocks produced the Variscan Orogeny, the main event of formation of the lithosphere. The subsequent Mesozoic rifting and breakup of the Pangea had a profound effect on the continental crust of Iberia. Since the Miocene, the southern interaction between Africa and Iberia is characterized by a diffuse convergent margin ...

  14. Decommissioning Peach Bottom Unit 1

    Decommissioning activities are described for Peach Bottom Unit No. 1, a 40 mw(e) HTGR demonstration plant owned and operated by the Philadelphia Electric Company. Radiological aspects of decommission are discussed. The application of advance planning and effective health physics techniques used during the Peach Bottom decommission program demonstrated the feasibility of decommissioning a nuclear facility economically at low personnel exposure levels and with a negligible environmental impact

  15. Density heterogeneity of the cratonic lithosphere

    Cherepanova, Yulia; Artemieva, Irina


    Using free-board modeling, we examine a vertically-averaged mantle density beneath the Archean-Proterozoic Siberian craton in the layer from the Moho down to base of the chemical boundary layer (CBL). Two models are tested: in Model 1 the base of the CBL coincides with the LAB, whereas in Model 2...... the base of the CBL is at a 180 km depth. The uncertainty of density model is <0.02 t/m3 or <0.6% with respect to primitive mantle. The results, calculated at in situ and at room temperature (SPT) conditions, indicate a heterogeneous density structure of the Siberian lithospheric mantle with a strong...... correlation between mantle density variations and the tectonic setting. Three types of cratonic mantle are recognized from mantle density anomalies. 'Pristine' cratonic regions not sampled by kimberlites have the strongest depletion with density deficit of 1.8-3.0% (and SPT density of 3.29-3.33 t/m3 as...

  16. The role of mechanical heterogeneities during continental breakup: a 3D lithospheric-scale modelling approach

    Duclaux, Guillaume; Huismans, Ritske S.; May, Dave


    How and why do continents break? More than two decades of analogue and 2D plane-strain numerical experiments have shown that despite the origin of the forces driving extension, the geometry of continental rifts falls into three categories - or modes: narrow rift, wide rift, or core complex. The mode of extension itself is strongly influenced by the rheology (and rheological behaviour) of the modelled layered system. In every model, an initial thermal or mechanical heterogeneity, such as a weak seed or a notch, is imposed to help localise the deformation and avoid uniform stretching of the lithosphere by pure shear. While it is widely accepted that structural inheritance is a key parameter for controlling rift localisation - as implied by the Wilson Cycle - modelling the effect of lithospheric heterogeneities on the long-term tectonic evolution of an extending plate in full 3D remains challenging. Recent progress in finite-element methods applied to computational tectonics along with the improved accessibility to high performance computers, now enable to switch from plane strain thermo-mechanical experiments to full 3D high-resolution experiments. Here we investigate the role of mechanical heterogeneities on rift opening, linkage and propagation during extension of a layered lithospheric systems with pTatin3d, a geodynamics modeling package utilising the material-point-method for tracking material composition, combined with a multigrid finite-element method to solve heterogeneous, incompressible visco-plastic Stokes problems. The initial model setup consists in a box of 1200 km horizontally by 250 km deep. It includes a 35 km layer of continental crust, underlaid by 85 km of sub-continental lithospheric mantle, and an asthenospheric mantle. Crust and mantle have visco-plastic rheologies with a pressure dependent yielding, which includes strain weakening, and a temperature, stress, strain-rate-dependent viscosity based on wet quartzite rheology for the crust, and wet

  17. Comparative study of ageing, heat treatment and accelerated carbonation for stabilization of municipal solid waste incineration bottom ash in view of reducing regulated heavy metal/metalloid leaching.

    Santos, Rafael M; Mertens, Gilles; Salman, Muhammad; Cizer, Özlem; Van Gerven, Tom


    This study compared the performance of four different approaches for stabilization of regulated heavy metal and metalloid leaching from municipal solid waste incineration bottom ash (MSWI-BA): (i) short term (three months) heap ageing, (ii) heat treatment, (iii) accelerated moist carbonation, and (iv) accelerated pressurized slurry carbonation. Two distinct types of MSWI-BA were tested in this study: one originating from a moving-grate furnace incineration operation treating exclusively household refuse (sample B), and another originating from a fluid-bed furnace incineration operation that treats a mixture of household and light industrial wastes (sample F). The most abundant elements in the ashes were Si (20-27 wt.%) and Ca (16-19 wt.%), followed by significant quantities of Fe, Al, Na, S, K, Mg, Ti, and Cl. The main crystalline substances present in the fresh ashes were Quartz, Calcite, Apatite, Anhydrite and Gehlenite, while the amorphous fraction ranged from 56 to 73 wt.%. The leaching values of all samples were compared to the Flemish (NEN 7343) and the Walloon (DIN 38414) regulations from Belgium. Batch leaching of the fresh ashes at natural pH showed that seven elements exceeded at least one regulatory limit (Ba, Cr, Cu, Mo, Pb, Se and Zn), and that both ashes had excess basicity (pH > 12). Accelerated carbonation achieved significant reduction in ash basicity (9.3-9.9); lower than ageing (10.5-12.2) and heat treatment (11.1-12.1). For sample B, there was little distinction between the leaching results of ageing and accelerated carbonation with respect to regulatory limits; however carbonation achieved comparatively lower leaching levels. Heat treatment was especially detrimental to the leaching of Cr. For sample F, ageing was ineffective and heat treatment had marginally better results, while accelerated carbonation delivered the most effective performance, with slurry carbonation meeting all DIN limits. Slurry carbonation was deemed the most

  18. Comparative study of predatory responses in blue mussels (Mytilus edulis L.) produced in suspended long line cultures or collected from natural bottom mussel beds

    Christensen, Helle Torp; Dolmer, Per; Petersen, Jens Kjerulf; Tørring, Ditte Bruunshøj


    Blue mussels (Mytilus edulis L.) are a valuable resource for commercial shellfish production and may also have uses as a tool in habitat improvement, because mussel beds can increase habitat diversity and complexity. A prerequisite for both commercial mussel production and habitat improvement is...... the availability of seed mussels collected with minimum impact on the benthic ecosystem. To examine whether mussels collected in suspended cultures can be used for bottom culture production and as tool in habitat improvement, the differences in predatory defence responses between suspended and bottom...... mussels exposed to the predatory shore crab (Carcinus maenas L.) were tested in laboratory experiments and in the field. Predatory defence responses (byssal attachment and aggregation) and morphological traits were tested in laboratory, while growth and mortality were examined in field experiments...

  19. Stagnant-lid Convection with Lateral Variations in Lithospheric Thickness: Application to Mars

    Sramek, O.; Zhong, S.


    The hemispheric dichotomy and Tharsis volcanic province are dominant planetary scale features on Mars. The formation mechanism of the dichotomy remains unclear and arguments have been made for both exogenic (i.e., giant impact) and endogenic (i.e., related to internal dynamics) origin. A recently proposed model by Zhong (2009) aims to link the formation of the dichotomy and the subsequent emplacement of the Tharsis region. This model requires a large-scale (spherical harmonic degree 1) flow in the mantle and involves a differential rotation of Martian lithosphere with respect to the sublithospheric mantle. It has been shown previously that a long-wavelength pattern of mantle flow naturally arises in convection models when realistic viscosity profiles are used. The lithosphere-mantle differential motion is excited by lateral variations in lithospheric thickness, assumed to represent the melt residue left after dichotomy formation by an endogenic process that involves melting. This motion could explain the inferred past migration of the Tharsis volcanic center from the current southern hemisphere to the dichotomy boundary. We present a suite of 3-D spherical-shell models to investigate the effect of various parameters on crucial ingredients of this model. First we look at the effect of varying asthenospheric channel thickness on the wavelength of convection for uniform lithospheric thickness, thus extending results of previous studies. We find a trade-off between the channel thickness and viscosity reduction in the channel, where a thinner asthenosphere requires a larger decrease in viscosity in order to generate degree-1 flow pattern. We then incorporate into our models a rigid lithospheric keel of hemispheric extent and observe the following. i) The position of the keel controls the orientation of the thermal structure, such that in the early stages of evolution the thermal upwelling is focused below the center of the keel. ii) Differential movement between the

  20. Comparison study of some finite volume and finite element methods for the shallow water equations with bottom topography and friction terms

    Lukácová-Medvid'ová, Maria; Teschke, Ulf


    We present a comparison of two discretization methods for the shallow water equations, namely the finite volume method and the finite element scheme. A reliable model for practical interests includes terms modelling the bottom topography as well as the friction effects. The resulting equations belong to the class of systems of hyperbolic partial differential equations of first order with zero order source terms, the so-called balance laws. In order to approximate correctly steady equilibrium ...

  1. Density heterogeneity of lithospheric mantle of Siberia in light of flat surface relief and high amplitudes of Moho and LAB topographies

    Cherepanova, Y.; Artemieva, I. M.


    Most of the Siberian craton and the West Siberian basin lack surface relief while the amplitudes of topography variations at the Moho and at top of the basement are ca. 20 km and 15 km, correspondingly. Seismic (surface wave tomography and interpretations of ultra-deep Soviet PNE reflection/refraction profiles) and thermal models indicate significant (at least 100 km but possibly as much as 200 km) variations in the lithosphere thickness across the entire region, whereas xenoliths studies from kimberlite-sampled areas confirm the presence of ca. 50 km deep regional LAB undulations. Few published analyses of the regional lithosphere flexure indicate a small thickness of the elastic lithosphere (less than 30 km), atypical of other cratons, and thus do not favor strong flexural support of lithosphere density heterogeneities. Assuming local isostatic equilibrium, we examine the relative contributions of the crust and the lithospheric mantle to maintain surface topography. Parameters controlling lithosphere buoyancy include thicknesses and densities of the crust and the lithospheric mantle, and lithosphere temperatures. We take advantage of our new crustal model, based on a quality-controlled compilation of all seismic models published in international and Russian literature, theses and reports since 1970s. For the lithosphere thickness and temperatures (which are interrelated parameters) we examine two end-member models as constrained by different seismic and thermal models. Assuming no effect of the dynamic topography (which is a valid approximation for most of the region, probably except for its southern margins), we examine compositional density variations in the lithospheric mantle. We also examine the effect of dynamic topography for kimberlite regions, where we adopt xenolith-based data on densities of the lithospheric mantle. The results are compared to seismic data on Pn velocities which show strong anomalies throughout the region (from 7.8 to 8.8 km/s) and to

  2. Creation and Deformation of Hydrous Lithosphere at the Southern Mariana Margin

    Martinez, F.; Kelley, K. A.; Stern, R. J.


    Mantle lithosphere formed at mid-ocean seafloor spreading centers is thought to be essentially anhydrous because water is strongly partitioned into melt and removed from the mantle during crustal formation. Since water weakens olivine this dehydration process is also thought to strengthen oceanic mantle lithosphere above solidus depths, perhaps helping to focus deformation and melt delivery to the narrow plate boundary zones observed at mid-ocean ridges. In contrast, convergent margins are sites of high water flux from subducting slabs and thereby provide an opportunity to study the creation and deformation of lithosphere in a hydrous environment. The southern Mariana margin presents a rare case in which the upper plate is undergoing active extension parallel to the trench and directly above the subducting slab. The extension has rifted preexisting Paleogene lithosphere resulting in the present-day creation of new lithosphere in this hydrous environment. Here we present preliminary results from R/V Thomas G. Thompson cruise TN273 in December 2011-January 2012 utilizing the Hawaii Mapping Research Group's IMI-30, a 30 kHz deep-towed side-scan sonar, and ship-based Simrad EM302 multibeam bathymetry. The sidescan sonar imagery and multibeam bathymetry map the tectonic and volcanic structure of a 32 x 80 km area referred to as the southeast Mariana forearc rifts (SEMFR), which extend from near the backarc spreading center toward the trench. The sonar imagery shows a complex volcanic and tectonic structure with no single spreading or rifting axis. Volcanism appears to be widely dispersed and separated by faulted areas. Bathymetry data show several rifts spanning this area but no single rift appears to be focusing tectonic activity as earthquake seismicity is broadly distributed across this region. The data depict a broad volcano-tectonic zone of complex deformation and distributed volcanism unlike the narrow plate boundary zones of mid-ocean ridges. This distributed

  3. Lithospheric Signature of Paleorifts in Cratonal Europe and North America

    Keller, G. R.; Stephenson, R. A.; Mickus, K. L.


    Southwestern North America and Central Europe share many aspects of their Neoproterozoic and Phanerozoic tectonic evolution. In particular, the break-up of late Precambrian supercontinent created the continental blocks called Laurentia and Baltica. Passive margins developed during and after the rifting that formed these continents, and these margins were deformed by Paleozoic orogenies (Appalachian-Ouachita; Caledonian-Variscan respectively). Our group has studied the Ouachita orogeny that affected southern Laurentia for many years and has recently had the opportunity to study Central Europe by participating in several large seismic experiments. The results of the POLONAISE' 97 experiment delineated the rifted margin of Baltica, and we interpret it to be quite similar to crustal models we have developed for the Ouachita margin. For example, the Holy Cross Mountains in southern Poland exposed a crustal block that is similar to the Devil's River uplift in west Texas. The Polish basin contains a thick pre-Permian section similar to that observed along the Ouachita orogenic belt that is overlain by a Permian and younger sequence that is analogous to the Gulf Coast sequence. Both the Variscan orogeny in Central Europe and the Ouachita orogeny appear to be the result of soft collisions that have left the pre-orogenic rifted margins largely intact. In terms of continental tectonics, rifts that do not succeed in breaking a continent apart are sometimes referred to as having "failed". These failed rifts usually are the sites of post-rift sedimentation that contain important records of continental evolution and prolific petroleum resources. During the past 15 years, a number of studies have shown that the modification of the lithosphere (most evidence is actually for the crust) in failed rifts takes on many forms, is highly variable, and is often very substantial. Although semantic arguments are seldom productive, these results call into question any perception that these

  4. Greenhouse Gas Emission Accounting. Preliminary study as input to a joint Int. IPCC Expert Meeting / CKO-CCB Workshop on Comparison of Top-down versus Bottom-up Emission Estimates.

    Amstel, van, R.; Kroeze, C.; Janssen, L.J.H.M.; Olivier, J. G. J.; Wal, van der, M.F.


    Bottom-up data for carbon dioxide, methane and nitrous oxide from the official national inventories (National Communications) were compared with data from EDGAR (Emission Database for Global Atmospheric Research) and top-down emission estimates, based on the results of dispersion and climate models using measured concentrations of greenhouse gases in the atmosphere. The aims of this preliminary study were to investigate the possibilities of comparing different types of emission inventories, t...

  5. Global model for the lithospheric strength and effective elastic thickness

    Tesauro, Magdala; Kaban, Mikhail K.; Cloetingh, Sierd A. P. L.


    Global distribution of the strength and effective elastic thickness (Te) of the lithosphere are estimated using physical parameters from recent crustal and lithospheric models. For the Te estimation we apply a new approach, which provides a possibility to take into account variations of Young modulus (E) within the lithosphere. In view of the large uncertainties affecting strength estimates, we evaluate global strength and Te distributions for possible end-member 'hard' (HRM) and a 'soft' (SRM) rheology models of the continental crust. Temperature within the lithosphere has been estimated using a recent tomography model of Ritsema et al. (2011), which has much higher horizontal resolution than previous global models. Most of the strength is localized in the crust for the HRM and in the mantle for the SRM. These results contribute to the long debates on applicability of the "crème brulée" or "jelly-sandwich" model for the lithosphere structure. Changing from the SRM to HRM turns most of the continental areas from the totally decoupled mode to the fully coupled mode of the lithospheric layers. However, in the areas characterized by a high thermal regime and thick crust, the layers remain decoupled even for the HRM. At the same time, for the inner part of the cratons the lithospheric layers are coupled in both models. Therefore, rheological variations lead to large changes in the integrated strength and Te distribution in the regions characterized by intermediate thermal conditions. In these areas temperature uncertainties have a greater effect, since this parameter principally determines rheological behavior. Comparison of the Te estimates for both models with those determined from the flexural loading and spectral analysis shows that the 'hard' rheology is likely applicable for cratonic areas, whereas the 'soft' rheology is more representative for young orogens.

  6. Internal structure of oceanic lithosphere: A perspective from tectonic windows

    Karson, Jeffrey A.

    Major faulted escarpments on the seafloor provide "tectonic windows" into oceanic crust and upper mantle. Direct observations in these settings reveal that the spatial arrangement, internal structure, and contacts between major rock units are significantly more complex than commonly anticipated on the basis of seismic studies and ophiolite analogs. From this perspective, a stratiform, ophiolite-like sequence of rock units, including basaltic volcanic rocks, sheeted diabase dike complex, isotropic and layered gabbroic and ultramafic rocks over upper mantle peridotites—all separated by generally horizontal contacts, may be much less common in the oceanic lithosphere than generally thought. Conversely, documented examples of large outcrop areas (tens of kilometers across) that lack the ophiolite-like sequence or that contain structures that do not conform to the ophiolite model call into question the basic assumptions made in the reconstruction and interpretation of ophiolite complexes. Historically, the stratiform ophiolite architecture has been the basis for inferences of the interaction between tectonism and magmatism at mid-ocean ridge spreading centers. A growing number of constraints on geological relations along seafloor escarpments hint at much broader range of interactions between tectonic deformation and magmatic construction. Along slow-spreading ridges, the magma budget (volume of magma per unit plate separation) is highly variable, giving rise to a wide range of morphologic and geologic features along wide rift valleys. The diversity of crustal architectures and internal structures seen in tectonic windows is correspondingly large. Although it is possible that a relatively simple, layered ophiolite-like crust develops in regions of relatively high magma budget (Reykjanes Ridge, Azores region, etc.), more complex structures that differ from those of stratiform ophiolites are present where lower magma budgets prevail. Significant deviations from a simple

  7. Electric lithosphere-astenosphere boundary in the north-west Fennoscandia as revealed from magnetotelluric data (MaSca project)

    Cherevatova, M.; Smirnov, M.


    Magnetotelluric images of the electric lithosphere-astenosphere boundary (LAB) below the north-western Fennoscandian Shield show that thickest lithosphere is in the Proterozoic Domain, not in Archaean. The Magnetotelluric (MT) method is well suited to map the depth to the LAB. The electric lithosphere is defined as the resistive outer shell overlying a highly conducting zone (astenosphere) in the upper mantle. A few extensive field campaigns have been undertaken in the Summers of 2011 to 2014 within the framework of the project "Magnetotellurics in the Scandes". The MaSca survey crosses two important boundaries: (i) the transition zone from the stable Precambrian cratonic interior to passive continental margin beneath the Caledonian orogen and the Scandinavian Mountains in western Fennoscandia; (ii) the boundary between the Archaean and Proterozoic crust and upper mantle. In this study we present the electrical resistivity models obtained from 279 MT sites (70 long-period stations among them) acquired from 2011 to 2013. We also used other sources of data available in the study area: the IMAGE observatory data, the BEAR array and two small arrays of Finnish Geological Survey (GTK). We present the results of 2D lithospheric-scale inversions obtained along four selected profiles: three profiles are NW-SE directed, thought to be perpendicular to estimated regional strike and one profile crosses the Archaean-Proterozoic boundary, thus NE-SW directed. The final interpretation models revealed thickest lithosphere is in the Palaeoproterozoic Svecofennian province and reaches depth of 300 km. The Archaean lithosphere is thinner, with depth of 200 km to 250 km.

  8. Major zircon megacryst suites of the Indo-Pacific lithospheric margin (ZIP) and their petrogenetic and regional implications

    Sutherland, Lin; Graham, Ian; Yaxley, Gregory; Armstrong, Richard; Giuliani, Gaston; Hoskin, Paul; Nechaev, Victor; Woodhead, Jon


    Zircon megacrysts (± gem corundum) appear in basalt fields of Indo-Pacific origin over a 12,000 km zone (ZIP) along West Pacific continental margins. Age-dating, trace element, oxygen and hafnium isotope studies on representative zircons (East Australia-Asia) indicate diverse magmatic sources. The U-Pb (249 to 1 Ma) and zircon fission track (ZFT) ages (65 to 1 Ma) suggest thermal annealing during later basalt transport, with migrating lithosphere. In contrast, East Asian-Russian ZIP sites reflect later basaltic magmatism (migrating lithosphere and slab subduction.

  9. Structure, seismicity, and instrumentation of stable North American lithosphere

    Wolin, Emily Lynne Gregonis

    The work in this thesis covers a number of different fields in seismology. These can be divided into three parts. In the first, I discuss earthquakes that occur along the North American passive margin. In the second, I investigate the noise characteristics of Superior Rifting Earthscope Experiment (SPREE) seismic stations. In the third, I evaluate the predictions of pre-existing tomographic models, expand raypath coverage in eastern North America by fitting waveforms, and produce an updated tomographic model focusing on the structure of stable North American lithosphere. First, I explore the rare, but moderate-to-large earthquakes that occur along the passive margin of North America, such as the August 2011 Mineral, Virginia earthquake. I discuss the tectonic setting, possible causes, and challenges of studying such earthquakes and propose directions for their future study. Examining the seismicity of the regions surrounding the 1929 Grand Banks and 1933 Baffin Bay earthquakes, I conclude that the aftershocks of these events continue today due to low strain rates along the margin. Second, I characterize the long-period noise characteristics of SPREE stations. At periods greater than 20 seconds, horizontal noise levels at SPREE stations vary seasonally and diurnally. I find that SPREE stations in sandy soil have the most consistent noise levels. Stations in fine-grained soil become extremely noisy during summer days, but very quiet when the surrounding soil freezes solid in winter. Finally, I evaluate previous generations of tomographic models and develop my own. I calculate synthetic seismograms for three tomographic models and compare them to new observed seismograms from earthquakes in stable North America. I find that adding data to a tomographic model does not necessarily improve predictions of regional S and Rayleigh waveforms. With this in mind, I apply the method of partitioned waveform inversion to derive constraints on S-velocity structure. I add these

  10. Geomorphological record of transformations of upland river valley bottoms at variable rate of gully erosion (case study: Wieprz River valley in Roztocze)

    Kociuba, Waldemar


    In the upland geosystems of the moderate climate zone, any change in the conditions of functioning of a catchment causes a response of the system involving variable dynamics of fluvial processes (Gregory, Walling 1973; Schumm 1977, 1981; Kostrzewski, Szpikowski 2003; Świeca, Kociuba 2007). In the conditions of low anthropopressure, the direction and intensity of the processes modelling the valley bottom are determined by environmental factors, i.e. the geology and lithology of sediments, and land relief, and climate-driven factors, i.e. precipitation and groundwater supply determining water and sediment discharge rate (Froehlich 1982; Kostrzewski et al. 1994; Krzemień 1999; Dearing, Jones 2003, Meybeck et al. 2003; Kociuba et al. 2003; Świeca, Kociuba 2007; Rodzik et al. 2008). In the conditions of strong anthropopressure, the processes of transformation of the valley bottom can be largely accelerated due to disturbances in the stability of the catchment’s environmental conditions. Their geomorphological ef fects are manifested in changes in the channel shape (in the plan and cross profile), and in the modelling of the zone outside the channel, as a result of both flood and delluvial sediment deposition, particularly in the mouth zones of dry valleys and erosional dissections (Bork 1989; Rodzik et al. 2008; Brown 2009). Transformations of valley landforms resulting from changes in natural conditions and anthropopressure on the valley system can be traced based on the example of the meridional part of the Roztocze section of the Wieprz River valley (Fig. 1) - a typical medium-sized upland river of the moderate climate zone (Rodzik et al. 2008). The modern relief of the alluvial plain of the Roztocze fragment of the Wieprz River valley results from complex morphogenetic processes (Kociuba, Brzezińska-Wójcik 2002; Kociuba, Superson 2004). The primary morphostructural features developed with the contribution of tectonic movements in the Neogene and Early