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Sample records for basin southern peru

  1. Andes hantavirus variant in rodents, southern Amazon Basin, Peru.

    Science.gov (United States)

    Razuri, Hugo; Tokarz, Rafal; Ghersi, Bruno M; Salmon-Mulanovich, Gabriela; Guezala, M Claudia; Albujar, Christian; Mendoza, A Patricia; Tinoco, Yeny O; Cruz, Christopher; Silva, Maria; Vasquez, Alicia; Pacheco, Víctor; Ströher, Ute; Guerrero, Lisa Wiggleton; Cannon, Deborah; Nichol, Stuart T; Hirschberg, David L; Lipkin, W Ian; Bausch, Daniel G; Montgomery, Joel M

    2014-02-01

    We investigated hantaviruses in rodents in the southern Amazon Basin of Peru and identified an Andes virus variant from Neacomys spinosus mice. This finding extends the known range of this virus in South America and the range of recognized hantaviruses in Peru. Further studies of the epizoology of hantaviruses in this region are warranted.

  2. Cenozoic forearc basin sediments in Southern Peru (15-18°S): Stratigraphic and heavy mineral constraints for Eocene to Miocene evolution of the Central Andes

    Science.gov (United States)

    Decou, A.; von Eynatten, H.; Mamani, M.; Sempere, T.; Wörner, G.

    2011-05-01

    A large sedimentary forearc basin developed in Cenozoic times between the present-day Coastal Cordillera and the Western Cordillera of the Central Andes, called Moquegua basin in southern Peru. The basin is filled by Moquegua Group deposits (~ 50 to 4 Ma) comprising mostly siliciclastic mudstones, sandstones and conglomerates as well as volcanic intercalations. Several facies changes both, along orogenic strike and through time, are described and have led to subdivision into four sedimentary units (Moquegua A, B, C and D). In this paper we present a refined stratigraphic scheme of the Moquegua Group combined with the first provenance analysis of the Moquegua basin based on (i) semi-quantitative analysis of heavy mineral abundance, (ii) electron microprobe (EMP) and laser ablation (LA) ICP-MS analyses of single detrital amphibole and Fe-Ti oxide grains, and (iii) comparative analysis of the different potential source rocks to clearly identify the most likely sources. Results allow us to reconstruct sediment provenance and to relate changes of the erosion-sedimentation system in the Moquegua basin to the evolution of the Andean orogen. At ~ 50 to ~ 40 Ma the Moquegua basin was close to sea level and fed by low energy rivers transporting mainly metamorphic basement and Jurassic-Cretaceous sedimentary detritus from local and distal sources. The latter might be as far as the present Eastern Cordillera. From ~ 35 Ma on the distal sediment sources were cut off by the uplift of the Altiplano and Eastern Cordillera leading to higher energy fluvial systems and increasing importance of local sources, especially the relevant volcanic arcs. From 25 Ma on volcanic arc rocks became the predominant sources for Moquegua Group sediments. The 10 Ma time lag observed between the onset of uplift-induced facies and provenance changes (at ~ 35 Ma) and the onset of intense magmatic activity (at ~ 25 Ma) suggests that magmatic addition was not the main driver for crustal thickening and

  3. Fibrous gypsum veins as diffuse features and within fault zones: the case study of the Pisco Basin (Ica desert, southern Peru)

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    Rustichelli, Andrea; Di Celma, Claudio; Tondi, Emanuele; Baud, Patrick; Vinciguerra, Sergio

    2016-04-01

    New knowledge on patterns of fibrous gypsum veins, their genetic mechanisms, deformation style and weathering are provided by a field- and laboratory-based study carried out on the Neogene to Quaternary Pisco Basin sedimentary strata (porous sandstones, siltstones and diatomites) exposed in the Ica desert, southern Peru. Gypsum veins vary considerably in dimensions, attitudes and timing and can develop in layered and moderately fractured rocks also in the absence of evaporitic layers. Veins occur both as diffuse features, confined to certain stratigraphic levels, and localised within fault zones. Arrays formed by layer-bounded, mutually orthogonal sets of steeply-dipping gypsum veins are reported for the first time. Vein length, height and spacing depend on the thickness of the bed packages in which they are confined. Within fault zones, veins are partly a product of faulting but also inherited layer-bounded features along which faults are superimposed. Due to the different petrophysical properties with respect to the parent rocks and their susceptibility to textural and mineralogical modifications, water dissolution and rupture, gypsum veins may have a significant role in geofluid management. Depending on their patterns and grade of physical and chemical alteration, veins may influence geofluid circulation and storage, acting as barriers to flow and possibly also as conduits.

  4. Staphylococcus aureus causing tropical pyomyositis, Amazon Basin, Peru.

    NARCIS (Netherlands)

    Garcia, C.; Hallin, M.; Deplano, A.; Denis, O.; Sihuincha, M.; Groot, R. de; Gotuzzo, E.; Jacobs, J.

    2013-01-01

    We studied 12 Staphylococcus aureus isolates causing tropical pyomyositis in the Amazon Basin of Peru. All isolates were methicillin-susceptible; 11 carried Panton-Valentine leukocidin-encoding genes, and 5 belonged to multilocus sequence type 25 and possessed an extensive set of enterotoxins. Our f

  5. Crustal Seismicity and Recent Faults in Southern Peru

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    David, C.; Comte, D.; Tavera, H.; Audin, L.; Herail, G.

    2004-12-01

    Most seismological studies in southern Peru have been focused on the downgoing slab seismicity in order to constrain the Wadati-Benioff zone. This study deals with the intra-continental seismicity of the southern Peru forearc (17,3° S - 18,5° S) in a post-seismic context (Arequipa thrust earthquake, Mw=8.4, 23 June, 2001). It is difficult to identify historical crustal earthquake from available catalogues, however some crustal events teleseismically recorded can be found since 1976; they exhibit normal focal mechanism solutions in the southern Peru volcanic arc and inverse focal mechanism solutions in the Central Depression. Following a notable increase of shallow crustal seismicity located close to the Western Cordillera after the 23 June 2001, a temporary seismic network was deployed between January and March 2003 in order to study the Wadati-Benioff zone and monitoring the crustal seismicity in southern Peru. From the about 1700 events locally recorded by the local network, 300 crustal earthquakes were identified in the Peruvian forearc between Tacna and Moquegua. This crustal seismicity is distributed along a lineament located at depths between 0 and 60 km, dipping at about 45° from the Western Cordillera towards the coast, almost perpendicular to the subducting slab; this behaviour was previously observed in northern Chile and in southern Peru, north of the study zone (16° S). In the Central Depression, seismic activity is not superficial occurring between 25-60 km depth and it is mostly characterized by inverse focal mechanism solutions. Superficial faults situated in the Central Depression and in the Coastal Cordillera can not be associated with the seismic activity observed in this area. However, in the Pre-Cordillera, crustal seismicity occurs at depths between 0-15 km and can be correlated with shallow fault systems recognized by satellite images and on the field. For examples, the Incapuquio fault system which was a transpressive system in Cretaceous

  6. Tectonic subsidence analyses of miogeoclinal strata from mesozoic marginal basin of Peru

    Energy Technology Data Exchange (ETDEWEB)

    Devlin, W.J.

    1988-01-01

    The Western Peruvian trough is composed of an eastern miogeoclinical facies of carbonate and clastic strata, and a western eugeoclinal facies consisting of a succession of volcanic and sedimentary rocks. In norther and central Peru, the miogeocline is located between a tectonic hinge adjacent to platformal facies of the Maranon geanticline on the east, and an outer marginal high bounded by the Cordillera Blanca fault and Tapacocha axis on the west. Miogeoclinal and platformal strata in southern Peru occur in a broad belt between Arequipa and Lago Titicaca. A marginal basin setting has been proposed for the Western Peruvian trough and the several kilometers of subsidence in the basin has been attributed to back-arc extension and crustal thinning. As a test of this model, quantitative tectonic subsidence curves were constructed from representative sections within miogeoclinar strata from four localities. Preliminary results indicate that the calculated curves have the same overall form as the age-depth curve for ocean floor, suggesting that subsidence was controlled by cooling and thermal contraction of heated lithosphere. The slopes of the curves are less than those for subsidence of oceanic lithosphere. However, they are in agreement with geologic evidence that the miogeocline accumulated on continental crust. Significant variations in the timing of onset, duration, and magnitude of subsidence are observed between sections from northern and southern Peru.

  7. Additions of angiosperms to the Flora of Peru from the Andean-Amazonian forests of southern Peru

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    Isau Huamantupa

    2014-10-01

    Full Text Available We present 25 new records of angiosperms for the Peruvian flora, as a result of different botanical explorations conducted in southern Peru, mainly in the areas of the departments of Cusco, Apurimac and Madre de Dios.

  8. The formation of early settled villages and the emergence of leadership: A test of three theoretical models in the Rio Ilave, Lake Titicaca Basin, southern Peru

    Science.gov (United States)

    Craig, Nathan Mcdonald

    Despite obvious necessities for understanding later developments in the region, Preceramic cultures in the Titicaca Basin are poorly understood due to lacking empirical data. This dissertation focuses on examination of two processes occurring in the Rio Ilave drainage during the Late 5000--3100 B.C.E. (6000--4400 B.P.) and Terminal 3100--1500 B.C.E. Archaic (4400--3200 B.P.): the formation of settled villages and the emergence of leadership. These processes are tested against theoretical predictions derived from: population resource imbalance, human behavioral ecology, and agency theories. Resource imbalance theory predicts appearance of density dependent adaptive problems prior to major cultural transformations. Human behavioral ecology predicts increased dietary diversity and incorporation of greater processing costs occuring coincidentally with reduced residential mobility. Symbolic mate value advertising is a predicted leadership strategy. Agency theory predicts internal sources of social tension, potentially independent of external forces, as primary causes of cultural change. Feast hosting and the formation political economy are expected to be central to both social processes investigated from this perspective. Local paleoclimatic proxies suggest aridity from ca 4000--2000 B.C.E. Reanalysis of pedestrian survey data indicate population growth during the Late Archaic. Excavation and ground penetrating radar survey at Pirco and Jiskairumoko demonstrate reduced residential mobility and increased evidence for social differentiation appearing during the Late Archaic's (before 3000 B.C.E.) end. New cultural patterns include: pithouses, more groundstone, internal storage, costly non-local artifacts, domesticated plants and animals, costly grave goods, and use of ochre in symbolic contexts. No clear cut evidence for inter-community promotional feasting was identified but some finds suggest intra-community alliance feasts. By the end of the Terminal Archaic ca. 1500 B

  9. Avifauna of the Pongos Basin, Amazonas Department, Peru

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    Brooks, D.M.; O'Neill, J.P.; Foster, M.S.; Mark, T.; Dauphine, N.; Franke, I.J.

    2009-01-01

    We provide an inventory of the avifauna of the Pongos Basin, northern Amazonas Department, Peru based on museum specimens collected during expeditions spanning >60 years within the 20th century. Four hundred and thirty-eight species representing 52 families are reported. Differences between lowland and higher elevation avifaunas were apparent. Species accounts with overviews of specimen data are provided for four species representing distributional records, two threatened species, and 26 species of Nearctic and Austral migrants, of which six are considered probable migrants.

  10. Islay And The Economy Of Southern Peru In 19th Century

    OpenAIRE

    2015-01-01

    This article notes the specificity of the regional economic history of Southern Peru, which in 1780-1840 experienced an important economic growth while the rest of the Viceroyalty of Peru was in crisis. This important fact is not well known because of the lack of research on regional economy. It presents data on the dynamics of international markets and its relation with the southern economy. Finally, the article argues some problems related to the general development of the Peruvian economy.

  11. Chemical and isotopic evolution of the coastal batholith of southern Peru

    Science.gov (United States)

    Boily, M.; Brooks, C.; Ludden, J. N.; James, D. E.

    1989-09-01

    of each superunit must be ultimately derived from an isotopically depleted mantle wedge above the subduction zone. The gabbro-diorite-granodiorite-monzogranite association is formed via fractional crystallization and crustal assimilation (i.e., AFC) during ascent in the Andean crust. If the exposed Precambrian crust represents a good compositional average of the upper crustal material assimilated, then the isotopic and some of the trace element variations observed in the three groups can be related to various amounts of crustal assimilation (i.e., small for group 1, but substantial for group 3), although surprisingly little assimilation is required when considering all southern Peruvian intrusives. More complex models advocate different parental mafic magmas formed by various mixtures of lower crustal and mantle derived melts, both having heterogenous but depleted Nd and Sr isotopic compositions. The parental magmas would then ascend, differentiate, and assimilate upper crustal materials of different compositions (i.e., a crust similar to the exposed Precambrian basement for groups 2 and 3 and a less enriched crust, not exposed in the area, for group 1). If the first model is correct, then the relatively small degree of crustal assimilation experienced during the formation of the Coastal Batholith of southern Peru is consistent with the hypothesis that the thick Andean crust was thinned during the prevailing extensional tectonic regime that led to the formation of a marginal basin in central Peru during the late Mesozoic. This allowed the basic magmas to encounter the base of the Precambrian section at shallower depth and spend less time ascending and differentiating in this enriched crust, effectively limiting the amount of assimilation.

  12. High Andean butterflies from southern Peru, I. Dry puna Satyrinae, with the description of two new taxa and three new records from Peru (Lepidoptera: Nymphalidae

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    José Alfredo Cerdeña

    2014-12-01

    Full Text Available This is the first part of a series of contributions to the knowledge of the high Andean butterfly fauna in southern Peru. In this work the butterfly species of the subfamily Satyrinae present in the dry puna of Peru are reviewed. A new species, Pampasatyrus gorkyi sp. nov. and a new subspecies Argyrophorus lamna cuzcoensis ssp. nov. are described from the department Cusco, Peru. Three species are recorded for the first time for Peru, Argyrophorus gustavi Staudinger, Faunula euripides (Weymer and Faunula eleates (Weymer previously reported from Chile and Bolivia. Ecological and biogeographical data are provided.

  13. A new species of Andean semiaquatic lizard of the genus Potamites (Sauria, Gymnophtalmidae from southern Peru

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    Germán Chávez

    2012-01-01

    Full Text Available We describe a new lizard species of the genus Potamites from the montane forests of the Cordillera de Vilcabamba (Cusco region and Apurimac River valley (Ayacucho region, between 1500 and 2000 meters of elevation, in southern Peru. The new species is distinguishable from all other species of the genus mainly byhighly keeled scattered scales on dorsum and females lacking femoral pores.

  14. Mummies and dental health in the ancient Ilo valley, southern Peru

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    Simon Hillson

    2003-10-01

    Full Text Available In the very arid climate of southern Peru, archaeological remains, including many human burials, are extremely well preserved. Study of the teeth of mummified people from different cultural groups and time periods is beginning to provide evidence of diet and disease among the ancient inhabitants of the Ilo valley between the foot-hills of the Andes and the desert coast.

  15. Origin of lead in andean calc-alkaline lavas, southern peru.

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    Tilton, G R; Barreiro, B A

    1980-12-12

    Lead isotope data from Quaternary andesitic lavas of the Arequipa and Barroso groups of southern Peru and from regional Precambrian granulitic gneisses reveal a lead component in the lavas from the gneisses. The lava leads can be accounted for by two-component mixtures of lead from mantle and lower crustal sources, although the mixing process need not have occurred in the lower crust.

  16. Multiple glacial culminations from the Lateglacial to the late Holocene in central and southern Peru (Invited)

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    Licciardi, J. M.; Schaefer, J. M.; Rodbell, D. T.; Stansell, N.; Schweinsberg, A.; Finkel, R. C.; Zimmerman, S. R.

    2013-12-01

    Fluctuations in small tropical mountain glaciers serve as sensitive indicators of variations in past and present-day climate. Most of the world's modern tropical glaciers reside in the Peruvian Andes, where a growing number of well-dated glacial records have recently been developed. As additional records are documented, regional patterns of late Pleistocene to Holocene glacial activity have begun to emerge. Here we present a compilation of new and previously obtained 10Be surface exposure ages from boulders on well-preserved moraine successions in two glaciated Andean ranges: the Cordillera Vilcabamba of southern Peru (13°20'S, 72°32'W) and the Huaguruncho massif (10°32'S, 75°56'W), located in central Peru ~450 km northwest of the Vilcabamba. A high-resolution composite chronology that merges >100 10Be measurements on moraine sequences in five glaciated drainages of the Cordillera Vilcabamba reveals the occurrence of at least five discrete glacial culminations from the Lateglacial to the late Holocene. At the Huaguruncho massif, >20 10Be exposure ages obtained from moraine sequences in a south-facing cirque indicate at least three major glacial stages spanning the Lateglacial to the Little Ice Age. The moraine ages at Huaguruncho are broadly correlative with the Vilcabamba moraine chronologies, with some dated moraine belts exhibiting geomorphic expressions that closely resemble those of their coeval counterparts in the Vilcabamba. A recurring finding in both field areas is a mismatch between basal radiocarbon ages from bog and lake sediments and 10Be exposure ages on outboard moraines, which enclose the depositional basins. These age discrepancies suggest that cosmogenic 10Be production rates scaled to high altitudes in the tropics are substantially lower than previous estimates. While we anticipate that future refinements to scaled isotope production rates may significantly affect correlation of 10Be exposure ages in the high Andes with ages derived from

  17. Shadows of the colonial past – diverging plant use in Northern Peru and Southern Ecuador

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    Bussmann Rainer W

    2009-02-01

    Full Text Available Abstract This paper examines the traditional use of medicinal plants in Northern Peru and Southern Ecuador, with special focus on the Departments of Piura, Lambayeque, La Libertad, Cajamarca, and San Martin, and in Loja province, with special focus on the development since the early colonial period. Northern Peru represents the locus of the old Central Andean "Health Axis." The roots of traditional healing practices in this region go as far back as the Cupisnique culture early in the first millennium BC. Northern Peru and Southern Ecuador share the same cultural context and flora but show striking differences in plant use and traditional knowledge. Two hundred fifteen plant species used for medicinal purposes in Ecuador and 510 plant species used for medicinal purposes in Peru were collected, identified,. and their vernacular names, traditional uses, and applications recorded. This number of species indicates that the healers, market vendors, and members of the public interviewed in Peru still have a very high knowledge of plants in their surroundings, which can be seen as a reflection of the knowledge of the population in general. In Ecuador much of the original plant knowledge has already been lost. In Peru, 433 (85% were Dicotyledons, 46 (9% Monocotyledons, 21 (4% Pteridophytes, and 5 (1% Gymnosperms. Three species of Giartina (Algae and one species of the Lichen genus Siphula were used. The families best represented were Asteraceae with 69 species, Fabaceae (35, Lamiaceae (25, and Solanaceae (21. Euphorbiaceae had 12 species, and Poaceae and Apiaceae each accounted for 11 species. In Ecuador the families best represented were Asteraceae (32 species, Euphorbiaceae, Lamiaceae, and Solanaceae (11 species each, and Apiaceae, Fabaceae, Lycopodiaceae (9 species each. One hundred eighty-two (85% of the species used were Dicotyledons, 20 Monocotyledons (9.3%, 12 ferns (5.5%, and one unidentified lichen was used. Most of the plants used (83% were

  18. Shadows of the colonial past--diverging plant use in Northern Peru and Southern Ecuador.

    Science.gov (United States)

    Bussmann, Rainer W; Sharon, Douglas

    2009-02-02

    This paper examines the traditional use of medicinal plants in Northern Peru and Southern Ecuador, with special focus on the Departments of Piura, Lambayeque, La Libertad, Cajamarca, and San Martin, and in Loja province, with special focus on the development since the early colonial period. Northern Peru represents the locus of the old Central Andean "Health Axis." The roots of traditional healing practices in this region go as far back as the Cupisnique culture early in the first millennium BC. Northern Peru and Southern Ecuador share the same cultural context and flora but show striking differences in plant use and traditional knowledge. Two hundred fifteen plant species used for medicinal purposes in Ecuador and 510 plant species used for medicinal purposes in Peru were collected, identified,. and their vernacular names, traditional uses, and applications recorded. This number of species indicates that the healers, market vendors, and members of the public interviewed in Peru still have a very high knowledge of plants in their surroundings, which can be seen as a reflection of the knowledge of the population in general. In Ecuador much of the original plant knowledge has already been lost. In Peru, 433 (85%) were Dicotyledons, 46 (9%) Monocotyledons, 21 (4%) Pteridophytes, and 5 (1%) Gymnosperms. Three species of Giartina (Algae) and one species of the Lichen genus Siphula were used. The families best represented were Asteraceae with 69 species, Fabaceae (35), Lamiaceae (25), and Solanaceae (21). Euphorbiaceae had 12 species, and Poaceae and Apiaceae each accounted for 11 species. In Ecuador the families best represented were Asteraceae (32 species), Euphorbiaceae, Lamiaceae, and Solanaceae (11 species each), and Apiaceae, Fabaceae, Lycopodiaceae (9 species each). One hundred eighty-two (85%) of the species used were Dicotyledons, 20 Monocotyledons (9.3%), 12 ferns (5.5%), and one unidentified lichen was used. Most of the plants used (83%) were native to Peru

  19. Mammal diversity in the middle basin of the river Tambopata, Puno, Peru

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    Víctor Pacheco

    2011-08-01

    Full Text Available This study documents the mammalian diversity in the Tambopata River middle basin, one of the most important information gaps in Peru. Five sites were evaluated in Puno (San Fermín 850 m, Curva Alegre 950 m, Challohuma 1200 m, Yanahuaya 1600 m, and Yanacocha 1985 m. The trapping effort was 7072 trap-nights and 201 mistnet-nights. 76 species were recorded in the study area, including 16 species under some conservation’s category. Bats and rodents were the most diverse orders (67.5%. The diversity indices of Shannon-Wiener and Simpson for small mammals show a moderate and mild negative correlation with elevation, respectively. Meanwhile the altitude is negatively correlated with the relative abundance (RA of bats, and positively with the RA of non-volant mammals. The marsupials Marmosa (Micoureus demerarae, Marmosops bishopi and Marmosops impavidus; the rodent Neacomys musseri, and bats Platyrrhinus albericoi, P. masu, P. nigellus, Eumops auripendulus and Cormura brevirostris are first records for the department of Puno. Akodon baliolus and Oxymycterus juliacae are considered valid species. The species Sturnira lilium and Akodon baliolus were those with the highest RA. Our records, added to published and unpublished data, indicate that the Río Tambopata watershed is habitat of 141 species of mammals. Finally, we recommend the extension of the southern part of the buffer zone of the PNBS to include the montane forests of Yanacocha, to protect the unique middleelevation fauna of the Río Tambopata watershed.

  20. Climate change underlies global demographic, genetic, and cultural transitions in pre-Columbian southern Peru.

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    Fehren-Schmitz, Lars; Haak, Wolfgang; Mächtle, Bertil; Masch, Florian; Llamas, Bastien; Cagigao, Elsa Tomasto; Sossna, Volker; Schittek, Karsten; Isla Cuadrado, Johny; Eitel, Bernhard; Reindel, Markus

    2014-07-01

    Several archaeological studies in the Central Andes have pointed at the temporal coincidence of climatic fluctuations (both long- and short-term) and episodes of cultural transition and changes of socioeconomic structures throughout the pre-Columbian period. Although most scholars explain the connection between environmental and cultural changes by the impact of climatic alterations on the capacities of the ecosystems inhabited by pre-Columbian cultures, direct evidence for assumed demographic consequences is missing so far. In this study, we address directly the impact of climatic changes on the spatial population dynamics of the Central Andes. We use a large dataset of pre-Columbian mitochondrial DNA sequences from the northern Rio Grande de Nasca drainage (RGND) in southern Peru, dating from ∼840 BC to 1450 AD. Alternative demographic scenarios are tested using Bayesian serial coalescent simulations in an approximate Bayesian computational framework. Our results indicate migrations from the lower coastal valleys of southern Peru into the Andean highlands coincident with increasing climate variability at the end of the Nasca culture at ∼640 AD. We also find support for a back-migration from the highlands to the coast coincident with droughts in the southeastern Andean highlands and improvement of climatic conditions on the coast after the decline of the Wari and Tiwanaku empires (∼1200 AD), leading to a genetic homogenization in the RGND and probably southern Peru as a whole.

  1. Late Paleozoic to Jurassic chronostratigraphy of coastal southern Peru: Temporal evolution of sedimentation along an active margin

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    Boekhout, F.; Sempere, T.; Spikings, R.; Schaltegger, U.

    2013-11-01

    We present an integrated geochronological and sedimentological study that significantly revises the basin and magmatic history associated with lithospheric thinning in southern coastal Peru (15-18°S) since the onset of subduction at ˜530 Ma. Until now, estimating the age of the sedimentary and volcanic rocks has heavily relied on paleontologic determinations. Our new geochronological data, combined with numerous field observations, provide the first robust constraints on their chronostratigraphy, which is discussed in the light of biostratigraphical attributions. A detailed review of the existing local units simplifies the current stratigraphic nomenclature and clarifies its absolute chronology using zircon U-Pb ages. We observe that the Late Paleozoic to Jurassic stratigraphy of coastal southern Peru consists of two first-order units, namely (1) the Yamayo Group, a sedimentary succession of variable (0-2 km) thickness, with apparently no nearby volcanic lateral equivalent, and (2) the overlying Yura Group, consisting of a lower, 1-6 km-thick volcanic and volcaniclastic unit, the Chocolate Formation, and an upper, 1-2 km-thick sedimentary succession that are in markedly diachronous contact across the coeval arc and back-arc. We date the local base of the Chocolate Formation, and thus of the Yura Group, to 216 Ma, and show that the underlying Yamayo Group spans a >110 Myr-long time interval, from at least the Late Visean to the Late Triassic, and is apparently devoid of significant internal discontinuities. The age of the top of the Chocolate Formation, i.e. of the volcanic arc pile, varies from ˜194 Ma to less than ˜135 Ma across the study area. We suggest that this simplified and updated stratigraphic framework can be reliably used as a reference for future studies.

  2. Analysis of the 23 June 2001 Southern Peru Earthquake Using Locally Recorded Seismic Data

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    Tavera, H.; Comte, D.; Boroschek, R.; Dorbath, L.; Portugal, D.; Haessler, H.; Montes, H.; Bernal, I.; Antayhua, Y.; Salas, H.; Inza, A.; Rodriguez, S.; Glass, B.; Correa, E.; Balmaceda, I.; Meneses, C.

    2001-12-01

    The 23 June 2001, Mw=8.4 southern Peru earthquake ruptured the northern and central part of the previous large earthquake occurred on 13 August 1868, Mw ~9. A detailed analysis of the aftershock sequence was possible due to the deployment of a temporary seismic network along the coast in the Arequipa and Moquegua districts, complementing the Peruvian permanent stations. The deployed temporary network included 10 short period three component stations from the U. of Chile-IRD-France and 7 broad-band seismic stations from the Instituto Geofísico del Perú. This network operated during the first weeks after the mainshock and recorded the major aftershocks like the larger one occurred on 7 July 2001, Mw=7.5, this event defines the southern limit of the rupture area of the 2001 Peruvian earthquake. The majority of the aftershocks shows a thrusting fault focal mechanisms according with the average convergence direction of the subducting Nazca plate, however, normal faulting events are also present in the aftershock sequence like the 5 July 2001, Mw=6.6 one. The depth distribution of the events permitted a detailed definition of the Wadati-Benioff zone in the region. The segment between Ilo and Tacna did not participated in the rupture process of the 2001 southern Peru earthquake. Seismicity located near the political Peruvian-Chilean boundary was reliable determined using the data recorded by the northern Chile permanent network. Analysis of the mainshock and aftershock acelerograms recorded in Arica, northern Chile are also included. The occurrence of the 1995 Antofagasta (Mw=8.0) and the 2001 southern Peru earthquakes suggests that the probability of having a major earthquake in the northern Chile region increased, considering that the previous large earthquake in this region happened in 1877 (Mw ~9), and since that time no earthquake with magnitude Mw>8 had occurred inside of the 1877 estimated rupture area (between Arica and Antofagasta).

  3. Stress in the contorted Nazca Plate beneath southern Peru from local earthquakes

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    Schneider, John F.; Sacks, I. Selwyn

    1987-12-01

    We study earthquake focal mechanisms in a region of highly contorted subducting lithosphere to identify dominant sources of stress in the subduction process. We observe a stress pattern in the contorted Nazca plate beneath southern Peru from an analysis of hypocentral trend and focal mechanisms of intermediate-depth earthquakes. Expanding on previous studies, we examine the hypocentral trend using 1673 of 2178 well-located local events from the nine-station Arequipa network. The dip of the plate beneath southern Peru averages 25°-30° from 25- to 100-km depth. Below this depth there is an 80- to 100-km-wide contortion between a zone of increasing dip (convex) to the southeast and a flat lying (concave) zone to the northwest. Using more than 6000 P wave first motions of events deeper than 50 km, we derive stress orientations from a moving average of composite focal mechanisms across a 200 by 350 km region including the contortion. The in-plate distribution of tension (T) and compression (P) axes reveals a coherent stress pattern. The trend is most clear beneath south-central Peru (NW section) and below 100- km depth in southernmost Peru (SE section). Both T and P axes tend to be dominantly in plate, especially below 100-km depth. T axes orient toward the contortion in a fan-shaped trend, which suggests that the deepest part of the seismic zone, within the convex SE section, is sinking and pulling the more buoyant NW section. We conclude that from 50- to 200-km depth, slab-pull forces are dominant in the observed stress. Our results suggest that a significant amount of plate extension occurs in this region of intermediate-depth subduction.

  4. Isolation of viruses from mosquitoes (Diptera: Culicidae) collected in the Amazon Basin region of Peru.

    Science.gov (United States)

    Turell, M J; O'Guinn, M L; Jones, J W; Sardelis, M R; Dohm, D J; Watts, D M; Fernandez, R; Travassos da Rosa, A; Guzman, H; Tesh, R; Rossi, C A; Ludwig, V; Mangiafico, J A; Kondig, J; Wasieloski, L P; Pecor, J; Zyzak, M; Schoeler, G; Mores, C N; Calampa, C; Lee, J S; Klein, T A

    2005-09-01

    As part of a comprehensive study on the ecology of arthropod-borne viruses in the Amazon Basin region of Peru, we assayed 539,694 mosquitoes captured in Loreto Department, Peru, for arboviruses. Mosquitoes were captured either by dry ice-baited miniature light traps or with aspirators while mosquitoes were landing on human collectors, identified to species, and later tested on Vero cells for virus. In total, 164 virus isolations were made and included members of the Alphavirus (eastern equine encephalomyelitis, Trocara, Una, Venezuelan equine encephalomyelitis, and western equine encephalomyelitis viruses), Flavivirus (Ilheus and St. Louis encephalitis), and Orthobunyavirus (Caraparu, Itaqui, Mirim, Murutucu, and Wyeomyia viruses) genera. In addition, several viruses distinct from the above-mentioned genera were identified to the serogroup level. Eastern equine encephalomyelitis virus was associated primarily with Culex pedroi Sirivanakarn & Belkin, whereas Venezuelan equine encephalomyelitis virus was associated primarily with Culex gnomatos Sallum, Huchings & Ferreira. Most isolations of Ilheus virus were made from Psorophora ferox (Von Humboldt). Although species of the Culex subgenus Melanoconion accounted for only 45% of the mosquitoes collected, 85% of the virus isolations were made from this subgenus. Knowledge of the viruses that are being transmitted in the Amazon Basin region of Peru will enable the development of more effective diagnostic assays, more efficient and rapid diagnoses of clinical illnesses caused by these pathogens, risk analysis for military/civilian operations, and development of potential disease control measures.

  5. Large slope instabilities in Northern Chile and Southern Peru

    Science.gov (United States)

    Crosta, Giovanni B.; Hermanns, Reginald L.; Valbuzzi, Elena; Frattini, Paolo; Valagussa, Andrea

    2014-05-01

    Deep canyon incision into Tertiary paleosurfaces and large slope instabilities along the canyon flanks characterize the landscape of western slope of the Andes of northern Chile and South Peru. This area belongs to the Coastal Escarpment and Precordillera and is formed by coarse-grained clastic and volcanoclastic formations. The area is characterized by intense seismicity and long-term hyperaridity (Atacama Desert). Landslides along the canyon flanks affect volumes generally up to 1 km3 and locally evolved in large rock avalanches. We prepared a landslide inventory covering an area of about 30,000 km2, extending from Iquique (Chile) to the South and Tacna (Peru) to the North. A total of 606 landslides have been mapped in the area by use of satellite images and direct field surveys, prevalently including large phenomena. The landslides range from 1 10-3 km2 to 464 km2 (Lluta landslide). The total landslide area, inclusive of the landslide scarp and of the deposit, amounts to about 2,130 km2 (about 7% of the area). The mega landslides can be classified as large block slides that can evolve in large rock avalanches (e.g. Minimini landslide). Their initiation seems to be strongly associated to the presence of secondary faults and large fractures transversal to the slope. These landslides show evidence suggesting a re-incision by the main canyon network. This seems particularly true for the Lluta collapse where the main 'landslide' mass is masked or deleted by the successive erosion. Other landslides have been mapped along the Coastal Escarpment and some of the major tectonic escarpments with an E-W trend. We examined area-frequency distributions of landslides by developing logarithmically binned, non-cumulative size frequency distributions that report frequency density as a function of landslide planar area A. The size frequency distribution presents a strong undersampling for smaller landslides, due to the extremely old age of the inventory. For landslides larger than

  6. Floristic diversity of the upper river basin Tambo-Ichuña (Moquegua, Peru

    Directory of Open Access Journals (Sweden)

    Daniel B. Montesinos-Tubée

    2011-06-01

    Full Text Available A study of the floristic diversity of vascular plants is presented from the basin of the Tambo-Ichuña River, the high Andean Puna plateau and wetlands of Ichuña, Ubinas and Yunga Districts (3400 - 4700 m altitude, General Sanchez Cerro Province, Department of Moquegua, Peru. Vascular flora is composed of 70 families, 238 genera and 404 species. The Magnoliopsida represent 78% of the species, Liliopsida 16%, Gymnosperms 0.5% and Pteridophytes 6%. Among lifeforms, the Hemicryptophytes are the most numerous. Three vegetation formations have been identified, the humid scrubland being the most diverse in species richness. Between endemic species, 42 taxa are exclusive to Peru. A total number of 272 new additions of vascular species to the flora of the department of Moquegua are presented.

  7. Alboran Basin, southern Spain - Part I: Geomorphology

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, A. [Secretaria General de Pesca Maritima, Corazon de Maria, 8, 28002 Madrid (Spain); Ballesteros, M.; Rivera, J.; Acosta, J. [Instituto Espanol de Oceanografia, Corazon de Maria, 8, 28002 Madrid (Spain); Montoya, I. [Universidad Juan Carlos I, Campus de Mostoles, Madrid (Spain); Uchupi, E. [Woods Hole Oceanographic Institution, Woods Hole, MA 02543 (United States)

    2008-01-15

    Bathymetric, 3D relief and shaded relief maps created from multibeam echo-sounding data image the morphology of the Alboran Basin, a structural low along the east-west-trending Eurasian-African plates boundary. Topographic features in the basin are the consequence of volcanism associated with Miocene rifting, rift and post-rift sedimentation, and recent faulting resulting from the convergence of the African-Eurasian plates. Pleistiocene glacially induced regressions/transgressions when the sea level dropped to about 150 m below its present level gas seeps and bottom currents. Recent faulting and the Pleistocene transgressions/regressions led to mass-wasting, formation of turbidity currents and canyon erosion on the basin's slopes. Recent fault traces at the base of the northern basin slope have also served as passageways for thermogenic methane, the oxidation of which by bacteria led to the formation of carbonate mounds along the fault intercepts on the sea floor. Expulsion of thermogenic or biogenic gas has led to the formation of pockmarks; erosion by bottom currents has resulted in the formation of moats around seamounts and erosion of the seafloor of the Alboran Ridge and kept the southern edge of the 36 10'N high sediment free. (author)

  8. Normal Faulting at the Western Margin of the Altiplano Plateau, Southern Peru

    Science.gov (United States)

    Schildgen, T. F.; Hodges, K. V.; Whipple, K. X.; Perignon, M.; Smith, T. M.

    2004-12-01

    Although the western margin of the Altiplano Plateau is commonly used to illustrate the marked differences in the evolution of a mountain range with strong latitudinal and longitudinal precipitation gradients, the nature of tectonism in this semi-arid region is poorly understood and much debated. The western margin of the Altiplano in southern Peru and northern Chile marks an abrupt transition from the forearc region of the Andes to the high topography of the Cordillera Occidental. This transition has been interpreted by most workers as a monocline, with modifications due to thrust faulting, normal faulting, and gravity slides. Based on recent fieldwork and satellite image analysis, we suggest that, at least in the semi-arid climate of southern Peru, this transition has been the locus of significant high-angle normal faulting related to the block uplift of the Cordillera Occidental. We have focused our initial work in the vicinity of 15\\deg S latitude, 71\\deg W longitude, where the range front crosses Colca Canyon, a major antecedent drainage northwest of Arequipa. In that area, Oligocene to Miocene sediments of the Moquegua Formation, which were eroded from uplifted terrain to the northeast, presently dip to the northeast at angles between 2 and 10º. Field observations of a normal fault contact between the Moquegua sedimentary rocks and Jurassic basement rocks, as well as 15-m resolution 3-D images generated from ASTER satellite imagery, show that the Moquegua units are down-dropped to the west across a steeply SW-dipping normal fault of regional significance. Morphology of the range front throughout southern Peru suggests that normal faulting along the range front has characterized the recent tectonic history of the region. We present geochronological data to constrain the timing of movement both directly from the fault zone as well as indirectly from canyon incision that likely responded to fault movement.

  9. Geodetic, teleseismic, and strong motion constraints on slip from recent southern Peru subduction zone earthquakes

    OpenAIRE

    Pritchard, M. E.; Norabuena, E. O.; Jillings, C.; Boroschek, R.; Comte, D.; Simons, M.; T. H. Dixon; Rosen, P. A.

    2007-01-01

    We use seismic and geodetic data both jointly and separately to constrain coseismic slip from the 12 November 1996 M_w 7.7 and 23 June 2001 M_w 8.5 southern Peru subduction zone earthquakes, as well as two large aftershocks following the 2001 earthquake on 26 June and 7 July 2001. We use all available data in our inversions: GPS, interferometric synthetic aperture radar (InSAR) from the ERS-1, ERS-2, JERS, and RADARSAT-1 satellites, and seismic data from teleseismic and strong motion stations...

  10. Variability in New Shortening Estimates from Southern Peru (12-14S); Implications for Mass Balance of the Andean Plateau.

    Science.gov (United States)

    Gotberg, N.; McQuarrie, N.

    2008-12-01

    One of the fundamental questions of interest with regards to the Andean Plateau is the mass balance of material needed to create and sustain a 3-4 km high plateau. Is crustal shortening sufficient to support an isostatically compensated crust of 60-70km? We present new estimates of shortening across the northern margin of the Andean Plateau. The cross section extent, from the eastern edge of the volcanic arc to foreland basin, is approximately one half of the physiographic width of the Andean Plateau in Peru. Cross sectional shortening estimates in southern Peru (12-14°S) provide a best estimate of 123 km or 40% shortening with an absolute minimum estimate of 86 km or 30% and absolute maximum estimate of 275 km or 60%. We determined the maximum and minimum shortening estimates using the cross sectional area and possible variations in assumptions made about the amount of erosion, detachment dip, involvement of basement thrusts and displacement along faults. The best estimate of shortening is well short of the required 240-300km of shortening needed in order to account for a 60-70km thick crust under the entire plateau. This suggests that for an isostatically equilibrated crust either 1) there is a significant amount of shortening (~150km) in the western half of the plateau which, is hidden by the volcanic arc or 2) crustal material is being added to the Peruvian section of the Andean Plateau either through lower crustal flow or a process of magmatic underplating followed by differentiation and delamination.

  11. Mammal diversity in the middle basin of the river Tambopata, Puno, Peru

    OpenAIRE

    Víctor Pacheco; Gisella Márquez; Edith Salas; Oscar Centty

    2011-01-01

    This study documents the mammalian diversity in the Tambopata River middle basin, one of the most important information gaps in Peru. Five sites were evaluated in Puno (San Fermín 850 m, Curva Alegre 950 m, Challohuma 1200 m, Yanahuaya 1600 m, and Yanacocha 1985 m). The trapping effort was 7072 trap-nights and 201 mistnet-nights. 76 species were recorded in the study area, including 16 species under some conservation’s category. Bats and rodents were the most diverse orders (67.5%). The diver...

  12. Exploration Breakthrough in Southern Margin of Junggar Basin

    Institute of Scientific and Technical Information of China (English)

    Kang Zhulin; Zheng Jiandong

    1997-01-01

    @@ The Hutubi structure, located in the southern margin of Junggar Basin, is 60 km norrthwest of Urumqi and 20 km northwest of Changji (Fig. l). The Hu-2 well drilled in the Hutubi structure has gained high-yield gas flow,significant exploration breakthrough in the southern margin of Junggar Basin since the 1950s.

  13. Molecular taxonomy of Anopheles (Nyssorhynchus) benarrochi (Diptera: Culicidae) and malaria epidemiology in southern Amazonian Peru.

    Science.gov (United States)

    Conn, Jan E; Moreno, Marta; Saavedra, Marlon; Bickersmith, Sara A; Knoll, Elisabeth; Fernandez, Roberto; Vera, Hubert; Burrus, Roxanne G; Lescano, Andres G; Sanchez, Juan Francisco; Rivera, Esteban; Vinetz, Joseph M

    2013-02-01

    Anopheline specimens were collected in 2011 by human landing catch, Shannon and CDC traps from the malaria endemic localities of Santa Rosa and San Pedro in Madre de Dios Department, Peru. Most specimens were either Anopheles (Nyssorhynchus) benarrochi B or An. (Nys.) rangeli, confirmed by polymerase chain reaction-restriction fragment length polymorphism-internal transcribed spacer 2 (PCR-RFLP-ITS2) and, for selected individuals, ITS2 sequences. A few specimens from Lupuna, Loreto Department, northern Amazonian Peru, were also identified as An. benarrochi B. A statistical parsimony network using ITS2 sequences confirmed that all Peruvian An. benarrochi B analyzed were identical to those in GenBank from Putumayo, southern Colombia. Sequences of the mtDNA COI BOLD region of specimens from all three Peruvian localities were connected using a statistical parsimony network, although there were multiple mutation steps between northern and southern Peruvian sequences. A Bayesian inference of concatenated Peruvian sequences of ITS2 + COI detected a single clade with very high support for all An. benarrochi B except one individual from Lupuna that was excluded. No samples were positive for Plasmodium by CytB-PCR.

  14. Tectonic and climatic controls on the Chuquibamba landslide (western Andes, southern Peru)

    Science.gov (United States)

    Margirier, A.; Audin, L.; Carcaillet, J.; Schwartz, S.; Benavente, C.

    2015-06-01

    The contribution of landslides to the Quaternary evolution of relief is poorly documented in arid contexts. In southern Peru and northern Chile, several massive landslides disrupt the arid western Andean front. The Chuquibamba landslide, located in southern Peru, belongs to this set of large landslides. In this area, the Incapuquio fault system captures the intermittent drainage network and localizes rotational landslides. Seismic activity is significant in this region with recurrent Mw 9 subduction earthquakes; however, none of the latest seismic events have triggered a major landslide. New terrestrial cosmogenic dating of the Chuquibamba landslide provides evidence that the last major gravitational mobilization of these rotational landslide deposits occurred at ~ 102 ka, during the Ouki wet climatic event identified on the Altiplano between 120 and 98 ka. Our results suggest that wet events in the arid and fractured context of the Andean forearc induced these giant debris flows. Finally, our study highlights the role of tectonics and climate on (i) the localization of large Andean landslides in the Western Cordillera and on (ii) the long-term mass transfer to the trench along the arid Andean front.

  15. Genetic diversity of vaccine candidate antigens in Plasmodium falciparum isolates from the Amazon basin of Peru

    Directory of Open Access Journals (Sweden)

    Lucas Carmen M

    2008-05-01

    Full Text Available Abstract Background Several of the intended Plasmodium falciparum vaccine candidate antigens are highly polymorphic and could render a vaccine ineffective if their antigenic sites were not represented in the vaccine. In this study, characterization of genetic variability was performed in major B and T-cell epitopes within vaccine candidate antigens in isolates of P. falciparum from Peru. Methods DNA sequencing analysis was completed on 139 isolates of P. falciparum collected from endemic areas of the Amazon basin in Loreto, Peru from years 1998 to 2006. Genetic diversity was determined in immunological important regions in circumsporozoite protein (CSP, merozoite surface protein-1 (MSP-1, apical membrane antigen-1 (AMA-1, liver stage antigen-1 (LSA-1 and thrombospondin-related anonymous protein (TRAP. Alleles identified by DNA sequencing were aligned with the vaccine strain 3D7 and DNA polymorphism analysis and FST study-year pairwise comparisons were done using the DnaSP software. Multilocus analysis (MLA was performed and average of expected heterozygosity was calculated for each loci and haplotype over time. Results Three different alleles for CSP, seven for MSP-1 Block 2, one for MSP-1 Block 17, three for AMA-1 and for LSA-1 each and one for TRAP were identified. There were 24 different haplotypes in 125 infections with complete locus typing for each gene. Conclusion Characterization of the genetic diversity in Plasmodium isolates from the Amazon Region of Peru showed that P. falciparum T and B cell epitopes in these antigens have polymorphisms more similar to India than to Africa. These findings are helpful in the formulation of a vaccine considering restricted repertoire populations.

  16. Chromium isotope composition of reducing and anoxic sediments from the Peru Margin and Cariaco Basin

    Science.gov (United States)

    Gueguen, B.; Planavsky, N.; Wang, X.; Algeo, T. J.; Peterson, L. C.; Reinhard, C. T.

    2014-12-01

    Chromium isotope systematics in marine sediments are now being used as a new redox proxy of the modern and ancient Earth's surface. Chromium is primarily delivered to the oceans by riverine inputs through weathering of Cr(III)-rich minerals present in the continental crust and oxidation of insoluble Cr(III) to soluble Cr(VI) species. Since oxidation-reduction reactions fractionate Cr isotopes whereby oxidized Cr(VI) species are preferentially enriched in heavy Cr isotopes, the Cr isotope composition of marine sediments may be useful tracers of redox conditions at the Earth's surface through geological time. Chromium is quantitatively removed in organic-rich sediments where reducing conditions prevail and promote reduction of Cr(VI) to Cr(III), and thus, these sediments should capture the ambient seawater Cr isotope composition. However, the isotopic composition of modern organic-rich sediments is poorly documented so far, and this step is essential for further modeling the global oceanic Cr isotope mass balance and assessing the effects of sedimentation and post-depositional processes on the marine Cr isotopes archive. In this study, we have characterized modern marine organic-rich sediments for their Cr isotope composition (δ53/52Cr) from two different settings, the Peru margin upwelling zone and the anoxic Cariaco Basin (Venezuela). Chromium isotopes were measured on a MC-ICP-MS (Nu Plasma) using a double-spike correction method. The authigenic fraction of shallow samples from the Peru margin sedimentary sequence with a high Total Organic Carbon (TOC) content (>10 wt%) yield an average δ53/52Crauthigenic value of +0.67 ±0.05 ‰ (2sd). However, although this value is close to the seawater value (Atlantic Ocean) and to Cariaco basin sediments (~ +0.6 ‰), reducing sediments from the Peru margin are on average isotopically slightly heavier, especially in samples having a low authigenic fraction and a low TOC content (δ53/52Crauthigenic values up to +1.30

  17. Olivine in the Southern Isidis Basin

    Science.gov (United States)

    2007-01-01

    The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) took this observation of the transition region between Libya Montes and the Isidis Basin on Mars at 17:16 UTC (12:16 p.m. EST) on January 2, 2007, near 3.6 degrees north latitude, 84.1 degrees east longitude. The image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 18 meters (60 feet) across. The image is about 11 kilometers (7 miles) wide at its narrowest point. The Isidis Basin resulted from of a gigantic impact on the surface of Mars early in the planet's history. The southern rim, where this target is located, is a region of complex geology and part of the planetary dichotomy boundary that separates the older southern highlands from the lower, younger northern plains. The image on the left was constructed from three visible wavelengths (RGB: 0.71, 0.60, 0.53 microns) and is a close approximation of how the surface would appear to the human eye. The image on the right was constructed from three infrared wavelengths (RGB: 2.49, 1.52, 1.08 microns) chosen to highlight variations in the mineralogy of the area. Of interest is that features in this image not only differ in color, but also in texture and morphology. The gray areas absorb similarly at all wavelengths used in this image, but display absorptions at other wavelengths related to the iron- and magesium-rich mineral pyroxene. The reddest areas absorb strongly at the wavelengths used for green and blue, which is attributable to another iron- and magesium-rich mineral, olivine. The brownish areas show subdued mineral absorptions and could represent some type of mixture between the other two materials. The presence of the mineral olivine is particularly interesting because olivine easily weathers to other minerals; thus, its presence indicates either the lack of weathering in this region or relatively recent exposure. CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and

  18. Imaging Lithospheric-scale Structure Beneath Northern Altiplano in Southern Peru and Northern Bolivia

    Science.gov (United States)

    Kumar, A.; Wagner, L. S.; Beck, S. L.; Zandt, G.; Long, M. D.

    2014-12-01

    The northern Altiplano plateau of southern Peru and northern Bolivia is one of the highest topographic features on the Earth, flanked by Western and Eastern Cordillera along its margin. It has strongly influenced the local and far field lithospheric deformation since the early Miocene (Masek et al., 1994). Previous studies have emphasized the importance of both the crust and upper mantle in the evolution of Altiplano plateau (McQuarrie et al., 2005). Early tomographic and receiver function studies, south of 16° S, show significant variations in the crust and upper mantle properties in both perpendicular and along strike direction of the Altiplano plateau (Dorbath et. al., 1993; Myers et al., 1998; Beck and Zandt, 2002). In order to investigate the nature of subsurface lithospheric structure below the northern Altiplano, between 15-18° S, we have determined three-dimensional seismic tomography models for Vp and Vs using P and S-wave travel time data from two recently deployed local seismic networks of CAUGHT and PULSE. We also used data from 8 stations from the PERUSE network (PERU Subduction Experiment). Our preliminary tomographic models show a complex variation in the upper mantle velocity structure with depth, northwest and southeast of lake Titicaca. We see the following trend, at ~85 km depth, northwest of lake Titicaca: low Vp and Vs beneath the Western Cordillera, high Vs beneath the Altiplano and low Vp and Vs beneath the Eastern Cordillera. This low velocity anomaly, beneath Eastern Cordillera, seems to coincide with Kimsachata, a Holocene volcano in southern Peru. At depth greater than ~85 km: we find high velocity anomaly beneath the Western Cordillera and low Vs beneath the Altiplano. This high velocity anomaly, beneath Western Cordillera, coincides with the well-located Wadati-Benioff zone seismicity and perhaps represents the subducting Nazca slab. On the southeast of lake Titicaca, in northern Bolivia, we see a consistently high velocity anomaly

  19. Determination of Nazca slab geometry and state of stress beneath the southern Peru and northern Bolivia

    Science.gov (United States)

    Kumar, A.; Wagner, L. S.; Beck, S. L.; Young, B. E.; Zandt, G.; Long, M. D.; Tavera, H.; Minaya, E.

    2013-12-01

    Subduction of the Nazca plate in the north central Andes beneath southern Peru and northern Bolivia is of prime importance because of the role it plays in the evolution of topographic features since the late Eocene (~40 Ma). Previous studies based on slab event locations constrained only with teleseismic data defined a broad area of flat slab subduction in central and southern Peru, which transitions to a normally dipping slab beneath the northernmost Altiplano Plateau. We present earthquake locations and focal mechanisms using data from two temporary arrays: the network of 50 broadband seismic stations that were part of the NSF-Continental Dynamics-funded project 'CAUGHT' (Central Andean Uplift and the Geodynamics of High Topography) and the 40 station NSF- Geophysics funded 'PULSE' array (PerU Lithosphere and Slab Experiment). Our earthquake locations provide new information about the geometry of subducting Nazca slab between 13°S to 18°S. A significant clustering of intermediate depth earthquakes at ~15.5°S and 18°S suggests strong and localized release of tectonic stress in the slab perhaps due to bending and unbending. There are not enough intra-slab events at depth greater than 100 km to constrain the flat slab width north of 14°S. Our analyses indicate that the flat slab is at least 10 to 12 km shallower than the previous estimates (e.g. Cahill and Isacks, 1992; Ramos, 2009). Focal mechanisms and stress axis orientation of slab events at ~15.5°S indicate down-dip extension, where the dip changes from subhorizontal to steeply dipping slab. The continuity in the trend of stress suggests that the slab is deformed but not torn where it transitions from flat to steeply dipping. Data from local slab events will eventually be incorporated into a local tomographic body wave inversion to better constrain the velocity structure of the mantle lithosphere and asthenosphere below the Altiplano. This in turn will provide the valuable information on the process

  20. Paleozoic evolution of active margin basins in the southern Central Andes (northwestern Argentina and northern Chile)

    Science.gov (United States)

    Bahlburg, H.; Breitkreuz, C.

    originated as an extensional structure at the continental margin of Gondwana. Independent lines of evidence imply that basin evolution was not connected to subduction. Thus, the basin could not have been in a fore-arc position as previously postulated. Above the folded Devonian-Early Carboniferous strata, a continental volcanic arc developed from the Late Carboniferous to the Middle Triassic. It represents the link between the Choiyoi Province in central Chile and Argentina, and the Mitu Group rift in southern Peru. The volcanic arc succession is characterized by the prevalence of silicic lavas and tuffs and volcaniclastic sedimentary rocks. During the latest Carboniferous, a thick ostracod-bearing lacustrine unit formed in an extended lake in the area of the Depresión Preandina. This lake basin originated in an intra-arc tensional setting. During the Early Permian, marine limestones were deposited on a marine platform west and east of the volcanic arc, connected to the depositional area of the Copacabana Formation in southern Peru.

  1. Pollution by heavy metals in the Moche River Basin, 1980 - 2010, La Libertad - Peru

    Directory of Open Access Journals (Sweden)

    Félix Huaranga Moreno

    2012-09-01

    Full Text Available The pollution of the continental waters is a problem at a world scale, mainly due to the impact of the mining tailings. Using top technologies as neutralization plants of acid waters, many companies are mitigating the impact of this functioning; so taking as a reference the changes in the concentration of heavy metals present in water, soils and cultivations of the high, middle and low basin of the Moche river, samplings of water were obtained at eight stations of the Moche river (Trujillo, Peru, and in four sectors of its margins for soils and cultivations. The most representative heavy metals in water were found in the high basin during the year 1980: iron (557.500 ppm, lead (100.375 ppm, cadmium (4.550 ppm, copper (6.900 ppm, zinc (262.900 ppm and arsenic (9.000 ppm; whereas in the soils the higher concentrations were found on the right margin of median basin in the year 1980: iron (83.400 mg/kg; lead (0.820 mg/kg; cadmium (0.012 mg/kg; copper (1.240 mg/kg; zinc (0.380 mg/kg and arsenic (0.016 mg/kg; in relation to the metal accumulation in the cultivations, iron (0.6525 mg/kg was predominant, being the yucca (Manihot esculentus the most contaminated cultivation. It is concluded that, most contamination level of water analysis was present in the high basin during 1980, whereas the right side of the median basin highest levels of contamination in the samples of soils; relating to the cultives, the yucca (Manihot esculentus was the species most contaminated.

  2. The historical (218 ± 14 aBP) explosive eruption of Tutupaca volcano (Southern Peru)

    Science.gov (United States)

    Samaniego, Pablo; Valderrama, Patricio; Mariño, Jersy; van Wyk de Vries, Benjamín; Roche, Olivier; Manrique, Nélida; Chédeville, Corentin; Liorzou, Céline; Fidel, Lionel; Malnati, Judicaëlle

    2015-06-01

    The little known Tutupaca volcano (17° 01' S, 70° 21' W), located at the southern end of the Peruvian arc, is a dacitic dome complex that experienced a large explosive eruption during historical times. Based on historic chronicles and our radiometric data, this eruption occurred 218 ± 14 aBP, probably between 1787 and 1802 AD. This eruption was characterised by a large sector collapse that triggered a small debris avalanche (<1 km3) and an associated pyroclastic eruption whose bulk volume was 6.5-7.5 × 107 m3. Both units were emplaced synchronously and spread onto the plain situated to the northeast of Tutupaca volcano. The spatial and temporal relationship between the debris avalanche and the pyroclastic density current deposits, coupled with the petrological similarity between the juvenile fragments in the debris avalanche, the pyroclastic density current deposits and the pre-avalanche domes, indicates that juvenile magma was involved in the sector collapse. Large amounts of hydrothermally altered material are also found in the avalanche deposit. Thus, the ascent of a dacitic magma, coupled with the fact that the Tutupaca dome complex was constructed on top of an older, altered volcanic sequence, probably induced the destabilisation of the hydrothermally active edifice, producing the debris avalanche and its related pyroclastic density currents. This eruption probably represents the youngest debris avalanche in the Andes and was accompanied by one of the larger explosive events to have occurred in Southern Peru during historical times.

  3. 3D Body Wave Velocity Tomography in Southern Peru: Seismotectonic Implications

    Science.gov (United States)

    Gallego, A.; Perez, J.; David, C.; Comte, D.; Charrier, R.; Dorbath, L.

    2004-12-01

    The studied region corresponds to the southern segment of the 1868 rupture area, that did not break with the last Mw=8.4 Arequipa earthquake in southern Peru. A temporary network of 19 short period, continuous recording seismic stations was deployed (16.5° -18.5° S; 69.5° -72° W) between December 2002-March 2003 in this region. The 1093 select events were used for a joint hypocentral and velocity structure inversion. The first obtained 1D velocity model was used as the initial model for the 3D inversion, consisting in 231 blocks distributed along layers separated by 10 km for depths lower than 80 km, and by 20 km for depths between 80 and 160 km. North of the Arica Bend, between the Coast and Andean Range the high Vp velocity and Vp/Vs ratio observed at depths lower than 10 km could represent the Precambrian basement uplifted by the Incapuquio sinistral fault system, which develops a positive flower structure typical for transpressional zones, that raised the basement. This behavior is in good agreement with the uplift of the Cambrian metamorphic complex, in the Precordillera south of the Arica Bend (northern Chile), by the west-vergent thrust system. Beneath the anomalous high velocities (between 20 and 30 km depth), a low velocity zone (Vpearthquake post-seismic period.

  4. Seismicity and structure of Nazca Plate subduction zone in southern Peru

    Science.gov (United States)

    Lim, H.; Kim, Y.; Clayton, R. W.

    2015-12-01

    We image the Nazca plate subduction zone system by detecting and (re)locating intra-slab earthquakes in southern Peru. Dense seismic arrays (PeruSE, 2013) were deployed along four lines to target geophysical characterization of the subduction system in the transition zone between flat and normal dipping segments of the Nazca plate (2-15°S). The arc volcanism is absent near the flat slab segment, and currently, the correlation between the location of the active volcanic front and corresponding slab depth is neither clear nor consistent between previously published models from seismicity. We detect 620 local earthquakes from August 2008 to February 2013 by manually picking 6559 and 4145 arrival times for P- and S-phases, respectively. We observe that the S-phase data is helpful to reduce the trade-off between origin time and depth of deeper earthquakes (>100 km). Earthquake locations are relocated to constrain the Nazca slab-mantle interface in the slab-dip transition zone using 7322 measurements of differential times of nearby earthquake pairs by waveform cross-correlation. We also employ the double-difference tomography (Zhang and Thurber, 2003) to further improve earthquake source locations and the spatial resolution of the velocity structure simultaneously. The relocated hypocenters clearly delineate the dipping Wadati-Benioff zone in the slab-dip transition zone between the shallow- (25°) to-flat dipping slab segment in the north and the normal (40°) dipping segment in the south. The intermediate-depth seismicity in the flat slab region stops at a depth of ~100 km and a horizontal distance of ~400 km from the trench. We find a significant slab-dip difference (up to 10°) between our relocated seismicity and previously published slab models along the profile region sampling the normal-dip slab at depth (>100 km).

  5. Bajocian ammonoids from Pumani River area (Ayacucho, Peru): Palaeobiogeographical and palaeoenvironmental implications for the Arequipa Basin

    Science.gov (United States)

    Fernandez-Lopez, Sixto; Carlotto, Victor; Giraldo, Edwin; Chacaltana, Cesar

    2014-01-01

    Deposits of the Socosani Formation in the Pucayacu and Pumani sections (Ayacucho Department, Peru), along several kilometres, have yielded Upper Bajocian ammonoid fossil-assemblages characterized by the occurrence of juvenile individuals belonging to endemic or pandemic genera, such as Megasphaeroceras and Spiroceras respectively. In addition, certain Bajocian genera relatively common in the Mediterranean-Caucasian Subrealm, but very scarce in the Eastern Pacific Subrealm, such as the strigoceratid Cadomoceras and the phylloceratid Adabofoloceras, occur in this area. According to the taphonomic, palaeoecological and palaeobiogeographical evidence from the Pumani River area, the maximum deepening, relative sea-level rise and oceanic accessibility of a Bajocian-Bathonian, second-order, transgressive/regressive facies cycle in the marine Arequipa Basin were reached during the Late Bajocian Niortense Biochron. However, synsedimentary regional tectonics in the Pumani River area disturbed this general deepening/shallowing cycle of the Arequipa Basin, particularly during the Late Bajocian post-Niortense time-interval of the Garantiana and Parkinsoni biochrons.

  6. Chrysobrycon yoliae, a new species of stevardiin (Characiformes: Characidae from the Ucayali basin, Peru

    Directory of Open Access Journals (Sweden)

    James Anyelo Vanegas-Ríos

    Full Text Available Chrysobrycon yoliae, new species, is described from a drainage flowing into the río Yucamia basin, río Ucayali basin, Peru. Chrysobrycon yoliaeis readily distinguished from its congeners by the anterior tip of pelvic bone situated anterior to the fifth rib (vs. situated posterior to the fifth rib, the presence of 20-26 dentary teeth (vs. 11-19, and the possession of a terminal lateral-line tube between caudal-fin rays 10 and 11 (vs. the absence of this tube, except in C. eliasi. The new species differs from C. eliasiand C. myersiby the presence of teeth on third pharyngobranchial (vs. the absence of teeth on this bone and also differs from C. eliasiby the dorsal-fin origin situated at vertical through anal-fin rays 5 to 7 (vs. located at vertical through anal-fin rays 8 to 10, the posterior extent of the ventral process of quadrate reaching the vertical through posterior margin of symplectic (vs. not reaching the vertical through posterior margin of symplectic, the dorsal-fin to adipose-fin length 26.8-28.8% SL (vs. 23.9-26.8% SL, and the body depth at dorsal-fin origin 34.4-42.2% SL (vs. 24.1-34.5% SL. A key for the identification of Chrysobryconspecies is provided.

  7. Geomorphic Effects, Chronologies, and Archaeological Significance of El Nino Floods in Southern Peru

    Science.gov (United States)

    Magilligan, F. J.; Manners, R.; Goldstein, P.

    2003-12-01

    The catastrophic effects of large floods have been well documented, on both contemporary and paleo-timecales, especially for the conterminous U.S. Less is known, however, about extreme events in hyper-arid sub-tropical climates where synoptic scale meteorological causes, such as El Nino-Southern Oscillation events, are the driving atmospheric mechanism. This research documents the geomorphic effects of extreme floods in the Moquegua River valley of southern Peru, in the core of the Atacama Desert. Using a combination of geomorphic mapping, hydrolologic modeling, aerial photography, ASTER satellite imagery, and GIS, we document the geomorphic signature of large contemporary floods within the mid-valley section (1500 masl) of the Rio Moquegua. Stratigraphic evidence and paleostage indicators of paleofloods, such as slackwater deposits and preserved high level flood gravels, are used to evidence late Holocene paleoflood magnitude-frequency relationships. On contemporary timescales, channel belt expansion by lateral erosion during large floods, such as the recent '97 and '98 floods, correspond to as much as 30-40 hectares of floodplain loss along the 20 km study reach. Sixty years of repeat aerial photography indicates that channel belt expansion and floodplain erosion commonly occurs along the Rio Moquegua. The frequent resetting of floodplain alluvium conditioned by these large floods is supported by radiocarbon dating of floodplain exposures. These dates indicate that most of the contemporary floodplain alluvium is younger that 560 14C yrs BP. The highest terrace remnants date to 3250 14C yrs BP and record a series of overbank flood gravels. Evidence for the regionally extensive Miraflores ENSO flood, ca. 1300 AD, exists in tributary and along mainstem sections. This flood has been documented along the coasts of Northern Chile to northern Peru, and has been evoked to explain significant social collapse. Our field evidence indicates that it catastrophically affected

  8. Effects of change in slab geometry on the mantle flow and slab fabric in Southern Peru

    Science.gov (United States)

    Knezevic Antonijevic, Sanja; Wagner, Lara S.; Beck, Susan L.; Long, Maureen D.; Zandt, George; Tavera, Hernando

    2016-10-01

    The effects of complex slab geometries on the surrounding mantle flow field are still poorly understood. Here we combine shear wave velocity structure with Rayleigh wave phase anisotropy to examine these effects in southern Peru, where the slab changes its geometry from steep to flat. To the south, where the slab subducts steeply, we find trench-parallel anisotropy beneath the active volcanic arc that we attribute to the mantle wedge and/or upper portions of the subducting plate. Farther north, beneath the easternmost corner of the flat slab, we observe a pronounced low-velocity anomaly. This anomaly is caused either by the presence of volatiles and/or flux melting that could result from southward directed, volatile-rich subslab mantle flow or by increased temperature and/or decompression melting due to small-scale vertical flow. We also find evidence for mantle flow through the tear north of the subducting Nazca Ridge. Finally, we observe anisotropy patterns associated with the fast velocity anomalies that reveal along strike variations in the slab's internal deformation. The change in slab geometry from steep to flat contorts the subducting plate south of the Nazca Ridge causing an alteration of the slab petrofabric. In contrast, the torn slab to the north still preserves the primary (fossilized) petrofabric first established shortly after plate formation.

  9. Geodetic, teleseismic, and strong motion constraints on slip from recent southern Peru subduction zone earthquakes

    Science.gov (United States)

    Pritchard, M. E.; Norabuena, E. O.; Ji, C.; Boroschek, R.; Comte, D.; Simons, M.; Dixon, T. H.; Rosen, P. A.

    2007-03-01

    We use seismic and geodetic data both jointly and separately to constrain coseismic slip from the 12 November 1996 Mw 7.7 and 23 June 2001 Mw 8.5 southern Peru subduction zone earthquakes, as well as two large aftershocks following the 2001 earthquake on 26 June and 7 July 2001. We use all available data in our inversions: GPS, interferometric synthetic aperture radar (InSAR) from the ERS-1, ERS-2, JERS, and RADARSAT-1 satellites, and seismic data from teleseismic and strong motion stations. Our two-dimensional slip models derived from only teleseismic body waves from South American subduction zone earthquakes with Mw > 7.5 do not reliably predict available geodetic data. In particular, we find significant differences in the distribution of slip for the 2001 earthquake from models that use only seismic (teleseismic and two strong motion stations) or geodetic (InSAR and GPS) data. The differences might be related to postseismic deformation or, more likely, the different sensitivities of the teleseismic and geodetic data to coseismic rupture properties. The earthquakes studied here follow the pattern of earthquake directivity along the coast of western South America, north of 5°S, earthquakes rupture to the north; south of about 12°S, directivity is southerly; and in between, earthquakes are bilateral. The predicted deformation at the Arequipa GPS station from the seismic-only slip model for the 7 July 2001 aftershock is not consistent with significant preseismic motion.

  10. Integrating short-term and long-term forecasting with reservoir optimisation; Mantaro Basin, Peru.

    Science.gov (United States)

    Jensen, R. A.; Lasarte, A.; Butts, M. B.

    2009-04-01

    Operational water management often requires a trade-off between short-term and long-term water demands, where short-term demands are driven for example by hydropower generation and flood protection requirements and the long-term demands by water and irrigation supply, sustainable reservoir management and the seasonal impacts of snow melt or climate. This paper presents an operational decision support system designed to forecast and optimise reservoir operations in both the short-term and long-term. The system has been established for the 20,000 km2 Mantaro river basin located in the high Andes with altitudes ranging from 3500 to nearly 6000 m.a.s.l.. The two main power stations at Tablachaca have a combined capacity of more than 1000 MW that supplies 30% of Peru's electrical energy. In addition, the basin's water resources supply extensive agricultural areas, an urban population and mining activities and sustain important ecological habitats. In this paper, the methodologies used for the integrating short-term and long-term forecasting are presented together with their application to the optimal operation of reservoirs. A key element in the system is the MIKE BASIN modelling tool. The system uses several modelling capabilities of MIKE BASIN: rainfall-runoff, reservoir operation, hydropower production, and river flow routing. The system also takes advantage of long-term forecasts (based on statistical information) and short-term forecasts (based on telemetry data). The continually updated runoff and flow forecasts enter the optimization, which applies the Model Predictive Control principle for MIKE BASIN as the core simulation model. For each optimization, a non-linear program algorithm is used to find the best release strategy. On the basis of the forecasted inflows and the real time data the system suggests to the user from which reservoirs to release water for alleviation of possible forecasted deficits. In addition to the Tablachaca scheme the model accounts for

  11. Taxonomy and new collections of wild potato species in Central and Southern Peru in 1999

    NARCIS (Netherlands)

    Salas, A.R.; Spooner, D.M.; Huamán, Z.; Torres Maita, R.V.; Hoekstra, R.; Schüler, K.; Hijmans, R.J.

    2001-01-01

    Peru contains about half of the described wild potato taxa, and many of these are not yet preserved in genebanks. This paper reports results of the second of a series of five planned collecting expeditions to Peru. Collections were made in the central Peruvian departments of Ancash, Huancavelica, La

  12. The eruptive chronology of the Ampato-Sabancaya volcanic complex (Southern Peru)

    Science.gov (United States)

    Samaniego, Pablo; Rivera, Marco; Mariño, Jersy; Guillou, Hervé; Liorzou, Céline; Zerathe, Swann; Delgado, Rosmery; Valderrama, Patricio; Scao, Vincent

    2016-09-01

    We have reconstructed the eruptive chronology of the Ampato-Sabancaya volcanic complex (Southern Peru) on the basis of extensive fieldwork, and a large dataset of geochronological (40K-40Ar, 14C and 3He) and geochemical (major and trace element) data. This volcanic complex is composed of two successive edifices that have experienced discontinuous volcanic activity from Middle Pleistocene to Holocene times. The Ampato compound volcano consists of a basal edifice constructed over at least two cone-building stages dated at 450-400 ka and 230-200 ka. After a period of quiescence, the Ampato Upper edifice was constructed firstly during an effusive stage (80-70 ka), and then by the formation of three successive peaks: the Northern, Southern (40-20 ka) and Central cones (20-10 ka). The Southern peak, which is the biggest, experienced large explosive phases, resulting in deposits such as the Corinta plinian fallout. During the Holocene, eruptive activity migrated to the NE and constructed the mostly effusive Sabancaya edifice. This cone comprised many andesitic and dacitic blocky lava flows and a young terminal cone, mostly composed of pyroclastic material. Most samples from the Ampato-Sabancaya define a broad high-K magmatic trend composed of andesites and dacites with a mineral assemblage of plagioclase, amphibole, biotite, ortho- and clino-pyroxene, and Fe-Ti oxides. A secondary trend also exists, corresponding to rare dacitic explosive eruptions (i.e. Corinta fallout and flow deposits). Both magmatic trends are derived by fractional crystallisation involving an amphibole-rich cumulate with variable amounts of upper crustal assimilation. A marked change in the overall eruptive rate has been identified between Ampato (~ 0.1 km3/ka) and Sabancaya (0.6-1.7 km3/ka). This abrupt change demonstrates that eruptive rates have not been homogeneous throughout the volcano's history. Based on tephrochronologic studies, the Late Holocene Sabancaya activity is characterised by strong

  13. The Progreso Basin Province of Northwestern Peru and Southwestern Ecuador: Neogene and Cretaceous-Paleogene Total Petroleum Systems

    Science.gov (United States)

    Higley, Debra K.

    2004-01-01

    The Progreso Basin province (6083) in northwestern Peru and southwestern Ecuador consists of the Paleogene Santa Elena block and Peru Bank, and the Neogene Tumbes-Progreso subbasin. The Santa Elena block and Peru Bank are part of the Cretaceous-Paleogene Total Petroleum System (TPS)(608302), which contains the Cretaceous-Paleogene Santa Elena Block Assessment Unit (60830201). The Tumbes- Progreso subbasin includes the Neogene TPS (608301) and associated Neogene Pull-Apart Basin Assessment Unit (60830101). The complex tectonic history of the Progreso Basin province influenced depositional and erosional patterns across the region, and also the location, timing, and types of seals, traps, possible source and reservoir rocks, and hydrocarbon generation and migration. Marine shales that are interbedded with and overlie reservoir intervals are the probable hydrocarbon source rocks. Timing of hydrocarbon generation and migration was probably Miocene and younger, following creation of the Tumbes-Progreso subbasin by movement along the Dolores-Guayaquil megashear. More than 220 million barrels of oil (MMBO) and 255 billion cubic feet of gas (BCFG) have been produced from the Progreso Basin province. The means of estimated recoverable oil, gas, and natural gas liquids (NGL) resources from undiscovered fields in the province are 237 MMBO, 695 BCFG, and 32 MMB NGL, respectively. The means of estimated recoverable oil, gas, and NGL resources from undiscovered onshore fields are 45 MMBO, 113 BCFG, and 5 MMBNGL, and from undiscovered offshore fields are 192 BBO, 582 BCFG, and 27 MMBNGL. These are USGS grown undiscovered resources that were determined by using a minimum field size of 1 million barrels of oil equivalent.

  14. The Southern Region of Peru Earthquake of June 23rd, 2001

    Science.gov (United States)

    Tavera, Hernando; Fernández, Efraín; Bernal, Isabel; Antayhua, Yanet; Agüero, Consuelo; Rodríguez, Henry Salas Simeón; Vilcapoma, Luis; Zamudio, Yolanda; Portugal, David; Inza, Adolfo; Carpio, Julia; Ccallo, Freddy; Valdivia, Igor

    2006-04-01

    The western border of South America is one of the most important seismogenic regions in the world. In this region the most damaging earthquake ever recorded occurred. In June 23rd, 2001, another very strong earthquake (Mw = 8.1-8.2) occurred and produced death and damages in the whole southern region of Peru. This earthquake was originated by a friction process between Nazca and South American plates and affected an area of about 300 km × 120 km defined by the distribution of more than 220 aftershocks recorded by a local seismic network that operated 20 days. The epicenter of the main shock was localized in the northwestern extremity of the aftershock area, which suggests that the rupture propagated towards the SE direction. The modeling of P-wave for teleseismic distances permitted to define a focal mechanism of reverse type with NW-SE oriented nodal planes and a possible fault plane moving beneath almost horizontally in NE direction. The source time function (STF) suggests a complex process of rupture during 85 sec with 2 successive sources. The second one of greater size, and located approximately 100-120 km toward the SE direction was estimated to have a rupture velocity of about 2 km/sec on a 28°-dipping plane to the SE (N135°). A second event happened 45 sec after the first one with an epicenter 130km farther to the SE and a complex STF. This event and the second source of the main shock caused a Tsunami with waves from 7 to 8 meters that propagated almost orthogonally to the coast line, by affecting mainly the Camaná area. Three of all the aftershocks presented magnitudes greater or equal to Mw = 6.6, two of them occurred in front of the cities of Ilo and Mollendo (June 26th and July 7th) with focal mechanisms similar to the main seismic event. The aftershock of July 5th shows a normal mechanism at a depth of 75 km, and is therefore most likely located within the subducting Nazca plate and not in the coupling. The aftershocks of June 26th (Mw = 6.6) and

  15. A Geochemical Comparison of the Northern Peninsular Ranges Batholith in Southern California and the Coastal Batholith in Southern Peru

    Science.gov (United States)

    Clausen, B. L.; Martínez Ardila, A. M.; Morton, D. M.

    2010-12-01

    An extensive geochemical data set from the northern Peninsular Ranges Batholith (PRB) in southern California is compared and contrasted with the Arequipa segment of the Peruvian Coastal Batholith, including new granitoid samples recently collected near Ica (14°S, 76°W). The data include major and trace elements and Sr isotope ratios. This is part of an on-going study of subduction-related magmatism to refine a petrogenetic model of crust formation at plate boundaries, with a particular interest in the role of magma mixing. Research in the northern PRB suggests that continental crust is formed in several cycles: (1) mantle melting to give mafic volcanics and gabbroic intrusives, (2) basalt/gabbro melting to give felsic granitoids uncontaminated by continental crust and having low initial 87Sr/86Sr (Sri) values less than 0.704, and (3) crustal melting to give high Sri values greater than 0.704. Geochemical evidence was used to determine the extent of mixing between mafic and felsic magma that produced rocks of intermediate SiO2 composition. These differentiation cycles formed a west to east chronologic sequence and yielded granitoids of gabbro, tonalite, and granodiorite composition. Using principal component analysis on the northern PRB granitoids, the four factors affecting geochemical composition were categorized as differentiation, crustal contamination, depth of magma source, and conditions that yield a range from calcic to more alkaline granitoids. A similar major and trace element analysis is being done for a classic result of subduction in the Peruvian Coastal Batholith. The Peruvian samples recently collected include granitoids of the upper Cretaceous Coastal Batholith, as well as the associated volcanics of Cretaceous and Jurassic age. The Coastal Batholith samples include a range of granitoids from the early gabbros and from the four batholithic super-units (from west to east: Linga, Pampahuasi, Tiabaya, and Incahuasi) containing a combination of diorite

  16. Comparison of co-seismic and post-seismic slip of large earthquakes in southern Peru and northern Chile

    Science.gov (United States)

    Pritchard, M. E.; Ji, C.; Simons, M.; Klotz, J.

    2003-12-01

    We use InSAR, GPS, and seismic data to constrain the location of co-seismic and post-seismic slip on the subduction interface in southern Peru and northern Chile. We focus on the July 30, 1995, {M}w~8.1 and the January 30, 1998, {M}w~7.1 northern Chile earthquakes as well as the November 12, 1996, {M}w~7.7 and June 23, 2001, {M}w~8.4 southern Peru earthquakes. For all four earthquakes, we invert body-wave seismic waveforms and geodetic data (InSAR for all earthquakes and GPS where available) both jointly and separately for co-seismic slip. In northern Chile, we constrain the temporal and spatial evolution of post-seismic after-slip using about 30 interferograms spanning 1995-2000 and GPS data from the German SAGA array (spanning 1995-1997, including vertical displacements). In southern Peru, we use InSAR data, and GPS data from the Arequipa station to constrain post-seismic after-slip. Comparison of these events provides insight into the rupture process of large subduction zone earthquakes and the mechanisms of post-seismic after-slip. The plate tectonic setting for all the earthquakes is similar (convergence rate, plate age, etc.), but the amount of post-seismic after-slip is different. There is significant slip after the 2001 earthquake (equivalent to approximately 20% of the co-seismic moment), but compared to other recent subduction zone earthquakes, there is little slip following the other three events. The different amounts of post-seismic slip are not obviously related to differences in the dynamic ruptures of each event, but might be related to along-strike variations in material properties (like sediment thickness).

  17. A new species of Acanthoscurria (Araneae: Theraphosidae: Theraphosinae without stridulatory organ, from southern Peru

    Directory of Open Access Journals (Sweden)

    Nelson Ferretti

    2016-08-01

    Full Text Available Acanthoscurria sacsayhuaman sp. nov. (Araneae: Theraphosidae is described based on a male from Cusco, Peru. The new species is characterized by the absence of stridulatory bristles on retrolateral face of palpal trochanter. Moreover, it can be distinguished by morphology of the male palpal bulb and tibial apophysis of the first pair of legs. The genus is recorded for the first time for Peru.

  18. Largest explosive eruption in historical times in the Andes at Huaynaputina volcano, a.d. 1600, southern Peru

    Science.gov (United States)

    Thouret, Jean-Claude; Davila, Jasmine; Eissen, Jean-Philippe

    1999-05-01

    The largest explosive eruption (volcanic explosivity index of 6) in historical times in the Andes took place in a.d. 1600 at Huaynaputina volcano in southern Peru. According to chronicles, the eruption began on February 19 with a Plinian phase and lasted until March 6. Repeated tephra falls, pyroclastic flows, and surges devastated an area 70 × 40 km2 west of the vent and affected all of southern Peru, and earthquakes shook the city of Arequipa 75 km away. Eight deposits, totaling 10.2 13.1 km3 in bulk volume, are attributed to this eruption: (1) a widespread, ˜8.1 km3 pumice-fall deposit; (2) channeled ignimbrites (1.6 2 km3) with (3) ground-surge and ash-cloud-surge deposits; (4) widespread co-ignimbrite ash layers; (5) base-surge deposits; (6) unconfined ash-flow deposits; (7) crystal-rich deposits; and (8) late ash-fall and surge deposits. Disruption of a hydrothermal system and hydromagmatic interactions are thought to have fueled the large-volume explosive eruption. Although the event triggered no caldera collapse, ring fractures that cut the vent area point to the onset of a funnel-type caldera collapse.

  19. Large mass movements related to deglaciation effects in southern Peru (Cusco)

    Science.gov (United States)

    Giráldez, Claudia; Choquevilca, Walter; Fernández, Felipe; Frey, Holger; García, Javier; Haeberli, Wilfried; Huggel, Christian; Ludena, Sebastián; Rohrer, Mario; Suarez, Wilson

    2013-04-01

    The Andes of Peru are among the regions most severely affected by glacier and high-mountain hazards over the past 100 years. Large-scale disasters with thousands of people killed are on record, including ice/rock avalanches, debris flows, and glacier lake outburst floods (GLOF's). Effects of climate change such as glacier retreat and formation of glacier lakes have been one of the drivers of hazards in the past. Now, there is an increasing concern about the destabilizing effect that recent and further warming has a on perennially frozen bedrock and on steep glaciers in the steep flanks of high-mountain peaks, with potentially severe consequences to ice/rock avalanches, which may impact existing and new lakes, producing far-reaching outburst floods. Risks are also changing due to the socio-economic development in the Andean region and need to be considered using integrative approaches. Most research so far has concentrated on the Cordillera Blanca region where the most devastating disasters occurred during the 20th century. Very little is known about glacier and high-mountain hazards in the southern Peruvian Cordilleras of Cusco although some of the largest debris flows worldwide affected this region in recent years. In fact, very little is known about the nature, origin and exact dimensions of mass movements in this area, and long-term climatic records are neither available. Here we analyze these recent events in the Santa Teresa region based on field work, satellite images, available meteorological data, and numerical modeling of mass movements. These studies are part of a larger effort towards an integrative risk management. Most of the mass movements that caused disasters have their origin in glaciated catchments draining towards Santa Teresa with catchment sizes between about 100 and 300 km2, and glacier areas of 6 to 16 km2 per catchment. It is known that the enormous 1998 debris flow (ca. 25 million m3) that destroyed the Machu Picchu hydropower plant

  20. Trigger Analysis and Modelling of Very Large Debris Flows in Santa Teresa, Cusco, Southern Peru

    Science.gov (United States)

    Buis, Daniel; Huggel, Christian; Frey, Holger; Giráldez, Claudia; Rohrer, Mario; Christen, Marc; Portocarrero, César

    2014-05-01

    The Peruvian Andes have repeatedly been affected by large mass movements such as landslides, avalanches and debris flows. In 1998, two very large debris flows in the region of Machu Picchu (Sacsara and Ahobamba), southern Peru, destroyed the town of Santa Teresa, an important hydropower scheme and further infrastructure. The debris flows on the order of 5 to 25 million m3 volume rank among the largest recently observed events of this type worldwide. Despite their extreme dimensions, these events have not been studied in detail. An important limitation for more insight studies is the remote location of the mass flows and the very sparse information and data available for the study region. Neither triggering processes nor mass flow process characteristics have been understood to date. This study tries to fill some of these gaps in understanding that are critical to improved assessment of hazards and eventual risk reduction measures. For the trigger analysis we used data and information from field work, a limited number of ground based meteorological data, and complementary satellite derived data. Results indicate that in the case of the Sacsara event, heavy rainfall likely was a main trigger. For Ahobamba, antecedent rainfall as well as snow and ice melt leading to saturation of glacial sediments must have played an important role. Simulations with a dynamic debris flow model (RAMMS) allowed us to constrain a number of flow parameters such as flow height and velocity, runout distance and flow and deposition volumes. Strong surging flow behavior was detected, resulting in very large runout distance (exceeding 20 km); which rather depends on the largest single surge volume, not the total event volume. Based on the identification of potential mass flow sources we modeled a number of scenarios. The assessment of related hazards, including a preliminary hazard map, showed that several communities in catchments draining towards Santa Teresa are endangered by mass movements

  1. Neotectonic of subsiding basins : case of studies from Marañon and Beni basins, Peru and Bolivia

    OpenAIRE

    Dumont, Jean-Francois

    1994-01-01

    Climatic conditions make the fluvial processes very sensitive in the extended flood plain of subandean basins, giving typical morphostructures. Because of high subsidence rate, these basins are case for the understanding of neotectonics in subsiding basins. Recent anciente fluvial traces are used in combination with sub surface structures, neotectonic and seismotectonic data to study the neotectonic evolution of the Peruvian and Bolivian active foreland basins. These basins, the Marañon Basin...

  2. Killing the snake of poverty : local perceptions of poverty and well-being and people’s capabilities to improve their lives in the Southern Andes of Peru

    NARCIS (Netherlands)

    Miyashita, A.

    2009-01-01

    Despite the generalised image of comuneros of the Southern Andes of Peru as living in poverty, a closer examination of the daily lives of the campesinos provides a more dynamic perspective. Some households claim that their lives are improving, others that their lives are the same, while many report

  3. Efficacy of sulfadoxine-pyrimethamine and mefloquine for the treatment of uncomplicated Plasmodium falciparum malaria in the Amazon basin of Peru

    Directory of Open Access Journals (Sweden)

    Magill Alan J.

    2004-01-01

    Full Text Available In vivo antimalarial drug efficacy studies of uncomplicated Plasmodium falciparum malaria at an isolated site in the Amazon basin of Peru bordering Brazil and Colombia showed >50% RII/RIII resistance to sulfadoxine-pyrimethamine but no evidence of resistance to mefloquine.

  4. Internal vein texture and vein evolution of the epithermal Shila-Paula district, southern Peru

    Science.gov (United States)

    Chauvet, Alain; Bailly, Laurent; André, Anne-Sylvie; Monié, Patrick; Cassard, Daniel; Tajada, Fernando Llosa; Vargas, Juan Rosas; Tuduri, Johann

    2006-07-01

    The epithermal Shila-Paula Au-Ag district is characterized by numerous veins hosted in Tertiary volcanic rocks of the Western Cordillera (southern Peru). Field studies of the ore bodies reveal a systematic association of a main E-W vein with secondary N55-60°W veins—two directions that are also reflected by the orientation of fluid-inclusion planes in quartz crystals of the host rock. In areas where this pattern is not recognized, such as the Apacheta sector, vein emplacement seems to have been guided by regional N40°E and N40°W fractures. Two main vein-filling stages are identified. stage 1 is a quartz-adularia-pyrite-galena-sphalerite-chalcopyrite-electrum-Mn silicate-carbonate assemblage that fills the main E-W veins. stage 2, which contains most of the precious-metal mineralization, is divided into pre-bonanza and bonanza substages. The pre-bonanza substage consists of a quartz-adularia-carbonate assemblage that is observed within the secondary N45-60°W veins, in veinlets that cut the stage 1 assemblage, and in final open-space fillings. The two latter structures are finally filled by the bonanza substage characterized by a Fe-poor sphalerite-chalcopyrite-pyrite-galena-tennantite-tetrahedrite-polybasite-pearceite-electrum assemblage. The ore in the main veins is systematically brecciated, whereas the ore in the secondary veins and geodes is characteristic of open-space crystallization. Microthermometric measurements on sphalerite from both stages and on quartz and calcite from stage 2 indicate a salinity range of 0 to 15.5 wt% NaCl equivalent and homogenization temperatures bracketed between 200 and 330°C. Secondary CO2-, N2- and H2S-bearing fluid inclusions are also identified. The age of vein emplacement, based on 40Ar/39Ar ages obtained on adularia of different veins, is estimated at around 11 Ma, with some overlap between adularia of stage 1 (11.4±0.4 Ma) and of stage 2 (10.8±0.3 Ma). A three-phase tectonic model has been constructed to explain the

  5. Genetic analysis of South American eastern equine encephalomyelitis viruses isolated from mosquitoes collected in the Amazon Basin region of Peru.

    Science.gov (United States)

    Kondig, John P; Turell, Michael J; Lee, John S; O'Guinn, Monica L; Wasieloski, Leonard P

    2007-03-01

    Identifying viral isolates from field-collected mosquitoes can be difficult and time-consuming, particularly in regions of the world where numerous closely related viruses are co-circulating (e.g., the Amazon Basin region of Peru). The use of molecular techniques may provide rapid and efficient methods for identifying these viruses in the laboratory. Therefore, we determined the complete nucleotide sequence of two South American eastern equine encephalomyelitis viruses (EEEVs): one member from the Peru-Brazil (Lineage II) clade and one member from the Argentina-Panama (Lineage III) clade. In addition, we determined the nucleotide sequence for the nonstructural P3 protein (nsP3) and envelope 2 (E2) protein genes of 36 additional isolates of EEEV from mosquitoes captured in Peru between 1996 and 2001. The 38 isolates were evenly distributed between lineages II and III virus groupings. However, analysis of the nsP3 gene for lineage III strongly suggested that the 19 isolates from this lineage could be divided into two sub-clades, designated as lineages III and IIIA. Compared with North American EEEV (lineage I, GA97 strain), we found that the length of the nsP3 gene was shorter in the strains isolated from South America. A total of 60 nucleotides was deleted in lineage II, 69 in lineage III, and 72 in lineage IIIA. On the basis of the sequences we determined for South American EEEVs and those for other viruses detected in the same area, we developed a series of primers for characterizing these viruses.

  6. Seismic Structure in Southern Peru: Evidence for a Smooth Contortion Between Flat and Normal Subduction of the Nazca Plate

    Science.gov (United States)

    Dougherty, S. L.; Clayton, R. W.

    2014-12-01

    Rapid changes in slab geometry are typically associated with fragmentation of the subducted plate; however, continuous curvature of the slab is also possible. The transition from flat to normal subduction in southern Peru is one such geometrical change, where previous studies have suggested both tearing and continuity of the slab. The morphology of the subducted Nazca plate along this transition is further explored here using intraslab earthquakes recorded by temporary regional seismic arrays. Observations of a gradual increase in slab dip coupled with a lack of any gaps or vertical offsets in the intraslab seismicity suggest a smooth contortion of the slab. Concentrations of focal mechanisms at orientations which are indicative of slab bending are also observed along the change in slab geometry. The presence of a thin ultra-slow velocity layer (USL) atop the horizontal Nazca slab is identified and located. The lateral extent of this USL is coincident with the margin of the projected linear continuation of the subducting Nazca Ridge, implying a causal relationship. Waveform modeling of the 2D structure in southern Peru using a finite-difference algorithm provides constraints on the velocity and geometry of the slab's seismic structure and confirms the absence of any tears in the slab. The seismic and structural evidence suggests smooth contortion of the Nazca plate along the transition from flat to normal subduction. The slab is estimated to have experienced 10% strain in the along-strike direction across this transition, compared to 15% strain across flat-to-normal transitions in central Mexico where the Cocos slab is likely torn.

  7. Lead isotopic evidence for evolutionary changes in magma-crust interaction, Central Andes, southern Peru

    Energy Technology Data Exchange (ETDEWEB)

    Barreiro, B.A. (California Univ., Santa Barbara (USA). Dept. of Geological Sciences); Clark, A.H. (Queen' s Univ., Kingston, Ontario (Canada). Dept. of Geological Sciences)

    1984-07-01

    Lead isotopic measurements were made on Andean igneous rocks of Jurassic to Recent age in Moquegua and Tacna Departments, southernmost Peru, to clarify the petrogenesis of the rocks and, in particular, to investigate the effect of crustal thickness on rock composition. This location in the Cordillera Occidental is ideal for such a study because the ca. 2 Ga Precambrian basement rocks (Arequipa massif) have a distinct Pb isotopic signature which is an excellent tracer of crustal interaction, and because geomorphological research has shown that the continental crust was here thickened drastically in the later Tertiary.

  8. Centuries of marine radiocarbon reservoir age variation within archaeological Mesodesma Donacium shells from Southern Peru

    Science.gov (United States)

    Jones, K.B.; Hodgins, G.W.L.; Etayo-Cadavid, M. F.; Andrus, C.F.T.; Sandweiss, D.H.

    2010-01-01

    Mollusk shells provide brief (Peru. The ranges in marine 14C ages (and thus R) from the 2 shells are 530 and 170 14C yr; R from individual aragonite samples spans 130 ?? 60 to 730 ?? 170 14C yr. This intrashell 14C variability suggests that 14C dating of small (time-slice much less than 1 yr) marine samples from a variable-R (i.e. variable-upwelling) environment may introduce centuries of chronometric uncertainty. ?? 2010 by the Arizona Board of Regents on behalf of the University of Arizona.

  9. GEODYNAMICS OF NAZCA RIDGE’S OBLIQUE SUBDUCTION AND MIGRATION - IMPLICATIONS FOR TSUNAMI GENERATION ALONG CENTRAL AND SOUTHERN PERU: Earthquake and Tsunami of 23 June 2001

    Directory of Open Access Journals (Sweden)

    George Pararas-Carayannis

    2012-01-01

    Full Text Available Peru is in a region of considerable geologic and seismic complexity. Thrust faulting along the boundary where the Nazca plate subducts beneath the South American continent has created three distinct seismic zones. The angle of subduction of the Nazca oceanic plate beneath the South American plate is not uniform along the entire segment of the Peru-Chile Trench. Furthermore, subduction is affected by buoyancy forces of the bounding oceanic ridges and fractures - such as the Mendana Fracture Zone (MFZ to the North and the Nazca Ridge to the South. This narrow zone is characterized by shallow earthquakes that can generate destructive tsunamis of varied intensities. The present study examines the significance of Nazca Ridge’s oblique subduction and migration to the seismicity of Central/Southern Peru and to tsunami generation. The large tsunamigenic earthquake of 23 June 2001 is presented as a case study. This event generated a destructive, local tsunami that struck Peru’s southern coasts with waves ranging from 3 to 4.6 meters (10-15 feet and inland inundation that ranged from 1 to 3 km. In order to understand the near and far-field tsunamigenic efficiency of events along Central/Southern Peru and the significance of Nazca Ridge’s oblique subduction, the present study examines further the geologic structure of the region and this quake’s moment tensor analysis, energy release, fault rupture and the spatial distribution of aftershocks. Tsunami source mechanism characteristics for this event are presented, as inferred from seismic intensities, energy releases, fault plane solutions and the use of empirical relationships. The study concludes that the segment of subduction and faulting paralleling the Peru-Chile Trench from about 150 to 180 South, as well as the obliquity of convergent tectonic plate collision in this region, may be the reason for shorter rupture lengths of major earthquakes and the generation of only local destructive tsunamis.

  10. Along-strike variations in post-seismic deformation in northern Chile and southern Peru

    Science.gov (United States)

    Pritchard, M. E.; Simons, M.

    2004-12-01

    We use InSAR and GPS data to constrain the spatio-temporal evolution of post-seismic after-slip following three large subduction zone earthquakes in South America. Post-seismic deformation following the 1995 {M}w~8.1 Antofagasta, Chile earthquake is barely above the InSAR detection limit, but by combining GPS observations with 36 interferograms we model the post-seismic deformation between the years 1995-2000. If the deformation is after-slip on the fault interface, the equivalent moment magnitude is 10-20% of the co-seismic moment, with the maximum deformation occurring 100 km from the maximum co-seismic slip. There is a pulse of deformation between large aftershocks in 1996 and 1998 that appears distinct from the general decay of after-slip with time. The low magnitude of post-seismic deformation is anomalous compared to other recent subduction zone earthquakes, including the nearby 2001 {M}w~8.4 Arequipa, Peru earthquake. After-slip following the 2001 earthquake between 2001-2004 equals about 20-40% of the co-seismic moment. There is no definitive post-seismic deformation following the 1996 {M}w~7.7 Nazca, Peru earthquake between 1997-1999, although there is no data spanning the first 51 days after the earthquake. Variations in the depth of rupture during these three earthquakes cannot solely explain the variations in after-slip. We suggest that variations in sediment subducted in each location may control the magnitude of after-slip. The larger thickness of sediments in the region of the 2001 earthquake might also explain why observed after-slip is located in the same area as the co-seismic slip, instead of down-dip, as in other subduction zones.

  11. Upper plate deformation and seismic barrier in front of Nazca subduction zone: The Chololo Fault System and active tectonics along the Coastal Cordillera, southern Peru

    Science.gov (United States)

    Audin, Laurence; Lacan, Pierre; Tavera, Hernando; Bondoux, Francis

    2008-11-01

    The South America plate boundary is one of the most active subduction zone. The recent Mw = 8.4 Arequipa 2001 earthquake ruptured the subduction plane toward the south over 400 km and stopped abruptly on the Ilo Peninsula. In this exact region, the subduction seismic crisis induced the reactivation of continental fault systems in the coastal area. We studied the main reactivated fault system that trends perpendicular to the trench by detailed mapping of fault related-geomorphic features. Also, at a longer time scale, a recurrent Quaternary transtensive tectonic activity of the CFS is expressed by offset river gullies and alluvial fans. The presence of such extensional fault systems trending orthogonal to the trench along the Coastal Cordillera in southern Peru is interpreted to reflect a strong coupling between the two plates. In this particular case, stress transfer to the upper plate, at least along the coastal fringe, appears to have induced crustal seismic events that were initiated mainly during and after the 2001 earthquake. The seafloor roughness of the subducting plate is usually thought to be a cause of segmentation along subduction zones. However, after comparing and discussing the role of inherited structures within the upper plate to the subduction zone segmentation in southern Peru, we suggest that the continental structure itself may exert some feedback control on the segmentation of the subduction zone and thus participate to define the rupture pattern of major subduction earthquakes along the southern Peru continental margin.

  12. Assessing hydrological changes in a regulated river system over the last 90 years in Rimac Basin (Peru)

    Science.gov (United States)

    Vega-Jácome, Fiorella; Lavado-Casimiro, Waldo Sven; Felipe-Obando, Oscar Gustavo

    2017-03-01

    Hydrological changes were assessed considering possible changes in precipitation and regulation or hydraulic diversion projects developed in the basin since 1960s in terms of improving water supply of the Rimac River, which is the main source of fresh water of Peru's capital. To achieve this objective, a trend analysis of precipitation and flow series was assessed using the Mann-Kendall test. Subsequently, the Eco-flow and Indicators of Hydrologic Alteration (IHA) methods were applied for the characterization and quantification of the hydrological change in the basin, considering for the analysis, a natural period (1920-1960) and an altered period (1961-2012). Under this focus, daily hydrologic information of the "Chosica R-2" station (from 1920 to 2013) and monthly rainfall information related to 14 stations (from 1964 to 2013) were collected. The results show variations in the flow seasonality of the altered period in relation to the natural period and a significant trend to increase (decrease) minimum flows (maximum flows) during the analyzed period. The Eco-flow assessment shows a predominance of Eco-deficit from December to May (rainy season), strongly related to negative anomalies of precipitation. In addition, a predominance of Eco-surplus was found from June to November (dry season) with a behavior opposite to precipitation, attributed to the regulations and diversion in the basin during that period. In terms of magnitude, the IHA assessment identified an increase of 51% in the average flows during the dry season and a reduction of 10% in the average flows during the rainy season (except December and May). Furthermore, the minimum flows increased by 35% with shorter duration and frequency, and maximum flows decreased by 29% with more frequency but less duration. Although there are benefits of regulation and diversion for developing anthropic activities, the fact that hydrologic alterations may result in significant modifications in the Rimac River ecosystem

  13. Prevalence and risk factors associated to Eimeria spp. infection in unweaned alpacas (Vicugna pacos) from Southern Peru.

    Science.gov (United States)

    Díaz, Pablo; Panadero, Rosario; López, Rosalía; Cordero, Aida; Pérez-Creo, Ana; López, Ceferino M; Fernández, Gonzalo; Díez-Baños, Pablo; Morrondo, Patrocinio

    2016-01-01

    A total of 350 faecal samples from unweaned alpacas over 3 months of age were collected from 23 herds in order to determine the prevalence of Eimeria spp. in Southern Peru and to identify the risk factors associated to Eimeria infection in young alpacas. Samples were examined by a flotation technique and the identification of risk factors was assessed by a logistic regression analysis. Sixty four percent of the examined animals shed Eimeria oocysts; herd prevalence was 96%, with an intra-herd prevalence of 60% (range 5.9-100%). Five different Eimeria species were identified, being E. lamae (91%), E. alpacae (87%) and E. punoensis (78%) the most prevalent; E. macusaniensis (35%) and E. ivitaensis (13%) were less common. Mixed-species infections were more frequent (78%) than single infections (22%). E. lamae was the most common monospecific infection and E. lamae/E. alpacae the most frequent association. The geographical area has a significant effect on Eimeria infection rates (74.9% wet Puna vs 37.4% dry Puna) as well as the breeding system (65.1% traditional vs 63.8% modern). In contrast, the sex of the animals (64.6% males vs 64.0% females) showed no influence on the prevalence of infection by Eimeria. The high prevalence found at both individual and herd level and the common presence of highly pathogenic Eimeria species may lead to important economic losses for alpaca breeders and could require the implementation of suitable control measures.

  14. El Niño floods and culture change: A late Holocene flood history for the Rio Moquegua, southern Peru

    Science.gov (United States)

    Magilligan, Francis J.; Goldstein, Paul S.

    2001-05-01

    The 1997 1998 El Niño generated large floods throughout southern Peru, especially in inland locations along Rio Moquegua. Using remote sensing, hydraulic modeling, field surveying, and stratigraphic analyses, we estimate the magnitude and frequency of this flood and determine a late Holocene flood history for main- stem and tributary sections. Modeling indicates a peak discharge of 450 m3/s for the 1998 flood, with an estimated recurrence interval between 50 and 100 yr. Flood deposits for two large events, dated to A.D. 690 and A.D. 1300, respectively, exist in a small tributary system. Tiwanaku site abandonment (ca. A.D. 1000) predates the younger flood, indicating that stratigraphically recognizable El Niño driven floods were not a causal mechanism for abandonment. Although possessing three flood units, main-stem alluvium is considerably younger (<320 14C yr B.P.) than tributary alluvium, evidencing the major channel widening and lateral reworking of the main stem.

  15. 3D Geologic Model of the Southern Great Basin

    Science.gov (United States)

    Wagoner, J. L.; Myers, S. C.

    2006-12-01

    We have constructed a regional 3D geologic model of the southern Great Basin, in support of a seismic wave propagation investigation of the 1993 Nonproliferation Experiment (NPE) at the Nevada Test Site (NTS). The model is centered on the NPE and spans longitude -119.5° to -112.6°, latitude 34.5° to 39.8°, and a depth from the surface to 150 km below sea level. Hence, the model includes the southern half of Nevada, as well as parts of eastern California, western Utah, and a portion of northwestern Arizona. The upper crust is constrained by geologic and geophysical studies, and the lower crust and upper mantle are constrained by geophysical studies. The upper crustal geologic units are Quaternary basin fill, Tertiary deposits, pre-Tertiary deposits, intrusive rocks, and calderas. The lower crust and upper mantle are parameterized with 8 layers, including the Moho. Detailed geologic data, including surface maps, borehole data, and geophysical surveys, were used to define the geology at the NTS. Digital geologic outcrop data were available for both Nevada and Arizona, whereas we scanned and hand digitized geologic maps for California and Utah. Published gravity data (2km spacing) were used to determine the thickness of the Cenozoic deposits and constrain the depth of the basins. The free surface is based on a 10m lateral resolution DEM at the NTS and a 90m resolution DEM elsewhere. The gross geophysical structure of the crust and upper mantle is taken from regional surface-wave studies. Variations in crustal thickness are based on receiver function analysis and a compilation of reflection/refraction studies. We used the Earthvision (Dynamic Graphics, Inc.) software to integrate the geologic and geophysical information into a model of x,y,z,p nodes, where p is an integer index representing the geologic unit. For regional seismic simulations we convert this realistic geologic model into elastic parameters. Upper crustal units are treated as seismically homogeneous

  16. Fungal and Prokaryotic Activities in the Marine Subsurface Biosphere at Peru Margin and Canterbury Basin Inferred from RNA-Based Analyses and Microscopy.

    Science.gov (United States)

    Pachiadaki, Maria G; Rédou, Vanessa; Beaudoin, David J; Burgaud, Gaëtan; Edgcomb, Virginia P

    2016-01-01

    The deep sedimentary biosphere, extending 100s of meters below the seafloor harbors unexpected diversity of Bacteria, Archaea, and microbial eukaryotes. Far less is known about microbial eukaryotes in subsurface habitats, albeit several studies have indicated that fungi dominate microbial eukaryotic communities and fungal molecular signatures (of both yeasts and filamentous forms) have been detected in samples as deep as 1740 mbsf. Here, we compare and contrast fungal ribosomal RNA gene signatures and whole community metatranscriptomes present in sediment core samples from 6 and 95 mbsf from Peru Margin site 1229A and from samples from 12 and 345 mbsf from Canterbury Basin site U1352. The metatranscriptome analyses reveal higher relative expression of amino acid and peptide transporters in the less nutrient rich Canterbury Basin sediments compared to the nutrient rich Peru Margin, and higher expression of motility genes in the Peru Margin samples. Higher expression of genes associated with metals transporters and antibiotic resistance and production was detected in Canterbury Basin sediments. A poly-A focused metatranscriptome produced for the Canterbury Basin sample from 345 mbsf provides further evidence for active fungal communities in the subsurface in the form of fungal-associated transcripts for metabolic and cellular processes, cell and membrane functions, and catalytic activities. Fungal communities at comparable depths at the two geographically separated locations appear dominated by distinct taxa. Differences in taxonomic composition and expression of genes associated with particular metabolic activities may be a function of sediment organic content as well as oceanic province. Microscopic analysis of Canterbury Basin sediment samples from 4 and 403 mbsf produced visualizations of septate fungal filaments, branching fungi, conidiogenesis, and spores. These images provide another important line of evidence supporting the occurrence and activity of fungi in

  17. Evolution and hazard analysis of high-mountain lakes in the Cordillera Vilcabamba (Southern Peru) from 1991 to 2014

    Science.gov (United States)

    Guardamino, Lucía; Drenkhan, Fabian

    2015-04-01

    In recent decades, glaciers in high-mountain regions have experienced unprecedented glacier retreat since the Little Ice Age (LIA). This development triggers the formation and growth of glacier lakes, which in combination with changes in glacier parameters might produce more frequent conditions for the occurrence of disasters, such as Glacier Lake Outburst Floods (GLOF). Facing such a scenario, the analysis of changing lake characteristics and identification of new glacier lakes are imperative in order to identify and reduce potential hazards and mitigate or prevent future disasters for adjacent human settlements. In this study, we present a multi-temporal analysis with Landsat TM 5 and OLI 8 images between 1991 and 2014 in the Cordillera Vilcabamba region (Southern Peru), a remote area with difficult access and climate and glaciological in-situ data scarcity. A semi-automatic model was developed using the band ratios Normalized Difference Snow Index (NDSI) and Normalized Difference Water Index (NDWI) in order to identify glacier and lake area changes. Results corroborate a strong glacier area reduction of about 51% from 1991 (200.3 km²) to 2014 (98.4 km²). At the same time, the number of lakes (total lake surface) has increased at an accelerated rate, from 0.77% (0.48%) in 1991 to 2.31% (2.49%) in 2014. In a multiple criteria analysis to identify potential hazards, 90 out of a total of 329 lakes in 2014 have been selected for further monitoring. Additionally, 29 population centers have been identified as highly exposed to lake related hazards from which 25 indicate a distance less than 1 km to an upstream lake and four are situated in a channel of potential debris flow. In these areas human risks are particularly high in view of a low HDI below Peru's average and hence pronounced vulnerability. We suggest more future research on measurements and monitoring of glacier and lake characteristics in these remote high-mountain regions, which include comprehensive risk

  18. Dynamic implications of ridges on a debris avalanche deposit at Tutupaca volcano (southern Peru)

    Science.gov (United States)

    Valderrama, Patricio; Roche, Olivier; Samaniego, Pablo; van Wyk de Vries, Benjamin; Bernard, Karine; Mariño, Jersy

    2016-02-01

    Catastrophic volcanic landslides can involve different parts of a volcano that can be incorporated into any resulting debris avalanche. The different material properties may influence the mechanical behaviour and, hence, the emplacement mechanisms of the different avalanche units. We present data from a coupled hydrothermal- and magmatic-related volcanic landslide at Tutupaca volcano (Peru). Around ad 1802, the hydrothermal system under Tutupaca's growing dacite dome failed, creating a debris avalanche that triggered a large explosive eruption. A typical debris avalanche hummocky unit is found, formed out of rock from the dome foot and the underlying hydrothermally altered lavas. It is covered by a more widespread and remarkable deposit that contains remnants of the hot dome core and the inner hydrothermal material. This deposit has ridges 20-500-m long, 10-30-m wide and 1-5-m high, regularly spaced and that fan slightly outward. Cross sections exposed within the ridges reveal coarser cores and finer troughs, suggesting grain size segregation during emplacement. Ridge morphology and granulometry are consistent with fingering known to occur in granular flows. The ridges are also associated with large blocks that have evidence of differential movement compared with the rest of the flowing mass. The presence of both ridged and hummocky deposits in the same event shows that, as different lithologies combine and collapse sequentially, materials with different mechanical properties can coexist in one landslide, leading to contrasting emplacement dynamics. The different structures thus highlight the complexity of such hazardous volcanic events and show the difficulty we face with modelling them.

  19. Geophysical surveys on permafrost in Coropuna and Chachani volcanoes (southern Peru)

    Science.gov (United States)

    Ubeda, Jose; Yoshikawa, Kenji; Pari, Walter; Palacios, David; Macias, Pablo; Apaza, Fredy; Ccallata, Beto; Miranda, Rafael; Concha, Ronald; Vasquez, Pool; Cruz, Rolando

    2015-04-01

    A network of air and ground temperature sensors installed 2004-2014 has enabled the discovery of permafrost on the Coropuna (6377 m) and Chachani (6057 m) volcanoes. However, on the Misti (5820 m) volcano there is no permafrost, which can be attributed to geothermal heat. Misti and Chachani are very close to each other, near the city of Arequipa (S. Peru). Coropuna is 150 km to the west. Various volcanic eruptions have taken place on Misti and Coropuna in the last 10 ka (Úbeda et al, 2012). The volcanic activity on the Chachani seems to be much older, although it has not been researched to date. Coropuna is covered by a glacial system of ~40 km2 (23-11-2013) and the moraines surrounding the volcanic complex indicate a surface of >500 km2 >10 ka ago (Úbeda et al, 2011). On Chachani the evidence also suggests a great extent in the past although in this case there are no glaciers conserved at the present day. On Misti there are currently no glaciers either, nor is there any evidence conserved of their earlier presence, and this has also been related to geothermal heat. As well as other study areas, the CRYOPERU sensor network includes 4 stations in the sector Coropuna-NE; 3 stations in Coropuna-SE; 3 stations in Chachani-SE and 3 stations in Misti-NW. The stations are at different altitudes, in an interval of 4300-6000 m. Each station has a thermometer to measure the air temperature (at a height of 0.50 m) and three thermometers to measure the ground temperature (at depths of 0.15, 0.30 and 1.00 m). The sensors are synchronized in GPS time and record the temperature every 30 minutes. Úbeda, J. et al (2012). Glacial and volcanic evolution on Nevado Coropuna (Tropical Andes) based on cosmogenic 36Cl surface exposure dating. EGU2012-3683-2. Úbeda, J. (2011). El impacto del cambio climático en los glaciares del complejo volcánico Nevado Coropuna (Cordillera Occidental de los Andes Centrales). PhD Thesis. Universidad Complutense de Madrid. 594 pp. http

  20. Lead isotopic evidence for evolutionary changes in magma-crust interaction, Central Andes, southern Peru

    Science.gov (United States)

    Barreiro, Barbara A.; Clark, Alan H.

    1984-07-01

    Lead isotopic measurements were made on Andean igneous rocks of Jurassic to Recent age in Moquegua and Tacna Departments, southernmost Peru, to clarify the petrogenesis of the rocks and, in particular, to investigate the effect of crustal thickness on rock composition. This location in the Cordillera Occidental is ideal for such a study because the ca. 2 Ga Precambrian basement rocks (Arequipa massif) have a distinct Pb isotopic signature which is an excellent tracer of crustal interaction, and because geomorphological research has shown that the continental crust was here thickened drastically in the later Tertiary. Seven samples of quartz diorites and granodiorites from the Ilo and Toquepala intrusive complexes, and seven samples of Toquepala Group subaerial volcanics were analyzed for Pb isotopic compositions. The plutonic rocks range in age from Jurassic to Eocene; the volcanic rocks are all Late Cretaceous to Eocene. With one exception, the Pb isotopic ratios are in the ranges 206Pb/ 204Pb= 18.52-18.75, 207Pb/ 204Pb= 15.58-15.65, and 208Pb/ 204Pb= 38.53-38.74. The data reflect very little or no interaction with old continental material of the Arequipa massif type. Lead from four Miocene Huaylillas Formation ash-flow tuffs, two Pliocene Capillune Formation andesites and five Quaternary Barroso Group andesites has lower 206Pb/ 204Pb than that in the pre-Miocene rocks, but relatively high 207Pb/ 204Pb and 208Pb/ 204Pb ( 206Pb/ 204Pb= 18.16-18.30, 207Pb/ 204Pb= 15.55-15.63, 208Pb/ 204Pb= 38.45-38.90). Tilton and Barreiro [9] have shown that contamination by Arequipa massif granulites can explain the isotopic composition of the Barosso Group lavas, and the new data demonstrate that this effect is evident, to varying degrees, in all the analysed Neogene volcanic rocks. The initial incorporation of such basement material into the magma coincided with the Early Miocene uplift of this segment of the Cordillera Occidental [32], and thus with the creation of a thick

  1. Volcanic and glacial evolution of Chachani-Nocarane complex (Southern Peru) deduced from the geomorphologic map.

    Science.gov (United States)

    Alcalá, J.; Zamorano, J. J.; Palacios, D.

    2012-04-01

    The Chachani-Nocarane (16°11'S; 71°31'W; 6.057 m asl) is a large volcanic complex located in the western Central-Andean Cordillera, South of Peru. The date of the last eruption is not known and there are no registers of recent volcanic activity. The complex is shaped by glacial forms belonging to different phases, and periglacial forms (several generations of rock glaciers) which alternate with volcanic forms. The aim of this research is to establish the glacio-volcanic evolution of the volcanic complex Chachani-Nocarane. In order to do so, a detailed 1:20.000 scale geomorphological map was elaborated by integrating the following techniques: interpretation of the 1:35.000 scale aerial photographs (Instituto Geográfico Nacional de Perú, 1956) and the analysis of satellite images (Mrsid; NASA, 2000). Finally, the cartography was corrected though field work campaigns. Through the geomorphologic analysis of the landforms and their relative position, we have identified twelve phases, seven volcanic and five glacial phases. The most ancient volcanic phase is locate to the north area of the study area and correspond with Nocarane and Chingana volcanoes, alignment NW-SE. Above those ensemble the rest of the large delimited geomorphological units overlap. The most recent is located to the SW and consists of a complex series of domes, lava cones and voluminous lavas. Within the glacial phases, the most ancient one is related to the Last Glacial Maximum during the Pleistocene. Over this period, glaciers formed moraines from 3150 to 3600 m asl. The most recent glacier pulsation corresponds to the Little Ice Age (LIA). The moraines related to that event are the closest to the summits, located between 5.100 and 5.300 m asl, and they represent the last trace of glacial activity on the volcanic complex. Currently, this tropical mountain does not have glaciers. The only solid-state water reserves are found in the form of permafrost, as shown by various generations of rock

  2. Dta points used in assessment of coal in the southern Piceance basin study area (psptg)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This is a shapefile and point coverage of 627 data points used in the assessment of coal in the southern Piceance Basin study area. Information in this file includes...

  3. The 2013 Earthquake Series in the Southern Vienna Basin: location

    Science.gov (United States)

    Apoloner, M.-T.; Bokelmann, G.; Bianchi, I.; Brückl, E.; Hausmann, H.; Mertl, S.; Meurers, R.

    2014-08-01

    Eastern Austria is a region of low to moderate seismicity, and hence the seismological network coverage is relatively sparse. Nevertheless accurate earthquake location is very important, as the area is one of the most densely populated and most developed areas in Austria. In 2013 a series of earthquakes with magnitudes up to 4.2 was recorded in the Southern Vienna Basin. With portable broadband, semi-permanent, and permanent installed seismic sensors from different institutions it was possible to record the main- and aftershocks with an unusual multitude of close-by seismic stations. In this study we combine records from all available stations up to 240 km distance in one dataset. First, we stabilize the location with three stations deployed in the epicentral area. The higher network density moves the location of smaller magnitude events closer to the main shocks, with respect to preliminary locations achieved by permanent and semi-permanent networks. Then we locate with NonLinLoc using consistent picks, a 3-D velocity model and apply station corrections. This second approach results in stable epicenters, for limited and even changing station availability. This dataset can then be inspected more closely for the presence of regional phases, which then can be used for more accurate localizations and especially depth estimation. Further research will address directivity effects and the asymmetry in earthquake intensity observed throughout the area, using double differences and cross-correlations.

  4. Crude oil geochemistry of the southern Songliao Basin

    Energy Technology Data Exchange (ETDEWEB)

    Li Taiming; Rullkoetter, J.; Radke, M.; Schaefer, R.G.; Welte, D.H.

    1987-08-01

    Twenty-three crude oils from the southern Songliao Basin, Heilongjiang Province (People's Republic of China), were characterized by various organic geochemical techniques to have a very uniform bulk and molecular composition in terms of source characteristics (type I kerogen) but to vary significantly in thermal maturity. Two middle Cretaceous source rocks, i.e. the Members 1 of the Qingshankou (Qn/sub 1/) and Nenjiang (Nen/sub 1/) Formations, were considered to be the most likely origin of the oils investigated, but a Jurassic source cannot be fully excluded for the Nang'An oils. Molecular maturation indicators including carbon preference indices, sterane isomerisation, conversion of mono- into triaromatic steroid hydrocarbons, relative concentration of diasteranes and the 18..cap alpha..(H)-22,29,30-trisnorneohopane/17..cap alpha..(H)-22,29,30-trisnorhopane ratio showed that there is a positive correlation between thermal maturity of the oils and the age of their reservoirs. This was interpreted as an indication of limited cross-stratigraphic migration and further evidence for the generation in the Qn/sub 1/ and Nen/sub 1/ source rocks.

  5. Seismological investigations in the Gioia Tauro Basin (southern Calabria, Italy

    Directory of Open Access Journals (Sweden)

    S. Gresta

    2008-06-01

    Full Text Available This study provides new seismological information to characterize the seismically active area of the Gioia Tauro basin (southern Calabria, Italy. Seismic activity recorded by a temporary network from 1985 to 1994 was analyzed for focal mechanisms, stress tensor inversion, P-wave seismic attenuation and earthquake source parameters estimation. Fault plane solutions of selected events showed a variety of different mechanisms, even if a prevalence of normal dip-slip solutions with prevalent rupture orientations occurring along ca. NE-SW directions was observed. Stress tensor inversion analysis disclosed a region governed mainly by a NW-SE extensional stress regime with a nearly vertical ?1. These results are consistent with the structure movements affecting the studied area and with geodetic data. Furthermore, evaluation of P-waves seismic attenuation and earthquake source parameters of a subset of events highlighted a strong heterogeneity of the crust and the presence of fault segments and/or weakened zones where great stress accumulation or long-rupture propagation are hindered.

  6. Shortening Record in the Central Andean Plateau of Southern Peru: Basement Inversion, Thin-skinned Thrusting, and Geomorphic Response

    Science.gov (United States)

    Perez, N.; Horton, B. K.; McQuarrie, N.; Stübner, K.; Ehlers, T. A.

    2015-12-01

    Variations in the inherited structural architecture along western South America influence the timing, magnitude, and style of Andean deformation and topographic evolution. New results from mapping, balanced cross-section construction, apatite and zircon (U-Th)/He thermochronology, and geomorphology spanning the Altiplano, Eastern Cordillera and Subandean zone of southern Peru define the role of Triassic rift inversion on Cenozoic deformation style, thrust belt kinematics, exhumation timing, and spatial variation of canyon incision. A minimum of 130 km (38%) shortening along a 200 km transect accommodated by thin- and thick-skinned structures involved selective reactivation of Triassic normal faults that fed slip to shallower detachments of thin-skinned fold-thrust systems. Map relationships define unique structural domains defined by inherited normal faults. In the Eastern Cordillera, new zircon (U-Th)/He results from a Triassic pluton reveal Oligocene-Miocene (~26-18 Ma) cooling, consistent with previously reported exhumation from ~40 km along strike to the NW. However, rapid ~15 Ma cooling revealed by new apatite (U-Th)/He data is ~11 Myr older than equivalent rocks in a similar structural setting ~40 km to the NW. This suggests a potential middle Miocene shift from synchronous to diachronous exhumation along strike. Modern fluvial profiles constructed along the Eastern Cordillera show a reduction in knickpoint elevations from SE to NW, suggesting more youthful uplift toward the NW, comparable to the spatial trend in apatite (U-Th)/He ages. The deformation front reached the Subandean zone by ~15 Ma, after the majority of reported deformation in the Eastern Cordillera and Altiplano. These variations in exhumation over such distances are consistent with multiple potential scenarios: a northward propagating wave of uplift, spatial variations in climatically driven incision, interactions with mantle dynamics, or complex structural geometries.

  7. Kinship and seasonal migration among the Aymara of southern Peru: human adaptation to energy scarcity

    Energy Technology Data Exchange (ETDEWEB)

    Collins, J.L.

    1981-01-01

    The people of the southern Peruvian highlands have adapted to a condition of energy scarcity through seasonal migration to lowland areas. In the disrict of Sarata (a fictitious name for a real district on the northeastern shore of Lake Titicaca) people spend three to seven months of every year growing coffee in the Tambopata Valley of the eastern Andes. This migratory pattern, which is hundreds of years old, provides the context for an investigation of human adaptive processes. This study presents models of the flow of energy through high-altitude households and shows that energy is a limiting factor for the population. There are two periods when energy subsidies from lowland regions become crucial to the continued survival of highland households. These are the periods of peak growth and reproduction experienced by households early in their developmental cycles, and times of sharply lowered productivity caused by environmental crises such as drought or killing frosts. Seasonal migration provides the subsidies that households rely on during these periods.

  8. End Late Paleozoic tectonic stress field in the southern edge of Junggar Basin

    Directory of Open Access Journals (Sweden)

    Wei Ju

    2012-09-01

    Full Text Available This paper presents the end Late Paleozoic tectonic stress field in the southern edge of Junggar Basin by interpreting stress-response structures (dykes, folds, faults with slickenside and conjugate joints. The direction of the maximum principal stress axes is interpreted to be NW–SE (about 325°, and the accommodated motion among plates is assigned as the driving force of this tectonic stress field. The average value of the stress index R′ is about 2.09, which indicates a variation from strike-slip to compressive tectonic stress regime in the study area during the end Late Paleozoic period. The reconstruction of the tectonic field in the southern edge of Junggar Basin provides insights into the tectonic deformation processes around the southern Junggar Basin and contributes to the further understanding of basin evolution and tectonic settings during the culmination of the Paleozoic.

  9. Geomorphologic map and derived geomorphological evolution model of the Ampato volcanic complex (Southern Peru).

    Science.gov (United States)

    Alcalá, J.; Zamorano, J. J.; Palacios, D.

    2012-04-01

    In this work we present the evolution of the Ampato volcanic complex (15°24´-15° 51´S, 73°W; 6.288 m asl) from a geomorphological perspective based on the analysis of landforms, both volcanic and derived from cold processes such as moraines and rock glaciers. In order to do so, a detailed 1:20.000 scale geomorphological map was elaborated by integrating the following techniques: the interpretation of the 1:35.000 scale aerial photographs (Instituto Geográfico Nacional de Perú, 1956) and the analysis of satellite images (Mrsid; NASA, 2000). The cartography was corrected through field work campaigns. A geomorphological cross-section traversing the map from North to South was elaborated in order facilitate the interpretation of the landforms. From the thorough analysis of the landforms represented in the geomorphological map and their relative position we have identified six main volcanic phases, mainly constructive but also, to a lesser extent, destructive (related with a Sant. Helens eruption), interspersed by five large glacial phases. From the three andesitic stratovolcanoes that form the complex (HualcaHualca, Sabancaya and Ampato) we suggest that the oldest of them is HualcaHualca representing the first step of the process over which the other units were placed. The most recent phase corresponds to the main cone of Sabancaya and its sets of domes and large lavas flows. Also we have detected a number of well-preserved vents on the Southern slope of volcano HualcaHualca close to the 1955 glacier tongues. Their presence is an evidence of recent volcanic activity in a volcano considered extinct. The glacial activity has been very active during the Quaternary on the Ampato Complex. The most ancient glacial phase is linked to the Last Glacial Maximum of the Pleistocene. During this event, the paleoglaciers descended down to 3650 m asl and builted moraines of 25- 30 m height. The most recent advance is related to the global event known as Little Ice Age (LIA

  10. Petroleum geological atlas of the southern permian basin area -Overview SPB-atlas project-organisation and results

    NARCIS (Netherlands)

    Doornenbal, J.C.; Abbink, O.A.; Pagnier, H.J.M.; Wees, J.D. van

    2009-01-01

    The Southern Permian Basin (also referred to as Central European Basin) is Europe s largest sedimentary basin. It is a typical intracontinental basin that evolved from latest Carboniferous to recent times and extends from eastern England to the Belarussian-Polish border and from Denmark to South Ger

  11. Pre-Columbian population dynamics in coastal southern Peru: A diachronic investigation of mtDNA patterns in the Palpa region by ancient DNA analysis.

    Science.gov (United States)

    Fehren-Schmitz, Lars; Reindel, Markus; Cagigao, Elsa Tomasto; Hummel, Susanne; Herrmann, Bernd

    2010-02-01

    Alternative models have been proposed to explain the formation and decline of the south Peruvian Nasca culture, ranging from migration or invasion to autochthonous development and ecological crisis. To reveal to what extent population dynamic processes accounted for cultural development in the Nasca mainland, or were influenced by them, we analyzed ancient mitochondrial DNA of 218 individuals, originating from chronologically successive archaeological sites in the Palpa region, the Paracas Peninsula, and the Andean highlands in southern Peru. The sampling strategy allowed a diachronic analysis in a time frame from approximately 800 BC to 800 AD. Mitochondrial coding region polymorphisms were successfully analyzed and replicated for 130 individuals and control region sequences (np 16021-16408) for 104 individuals to determine Native American mitochondrial DNA haplogroups and haplotypes. The results were compared with ancient and contemporary Peruvian populations to reveal genetic relations of the archaeological samples. Frequency data and statistics show clear proximity of the Nasca populations to the populations of the preceding Paracas culture from Palpa and the Peninsula, and suggest, along with archaeological data, that the Nasca culture developed autochthonously in the Rio Grande drainage. Furthermore, the influence of changes in socioeconomic complexity in the Palpa area on the genetic diversity of the local population could be observed. In all, a strong genetic affinity between pre-Columbian coastal populations from southern Peru could be determined, together with a significant differentiation from ancient highland and all present-day Peruvian reference populations, best shown in the differential distribution of mitochondrial haplogroups.

  12. Paleomagnetism, magnetic fabric, and 40Ar/39Ar dating of Pliocene and Quaternary ignimbrites in the Arequipa area, southern Peru

    Science.gov (United States)

    Paquereau-Lebti, Perrine; Fornari, Michel; Roperch, Pierrick; Thouret, Jean-Claude; Macedo, Orlando

    2008-07-01

    40Ar/39Ar ages and paleomagnetic correlations using characteristic remanent magnetizations (ChRM) show that two main ignimbrite sheets were deposited at 4.86 ± 0.07 Ma (La Joya Ignimbrite: LJI) and at 1.63 ± 0.07 Ma (Arequipa Airport Ignimbrite: AAI) in the Arequipa area, southern Peru. The AAI is a 20-100 m-thick ignimbrite that fills in the Arequipa depression to the west of the city of Arequipa. The AAI is made up of two cooling units: an underlying white unit and an overlying weakly consolidated pink unit. Radiometric data provide the same age for the two units. As both units record exactly the same well-defined paleomagnetic direction (16 sites in the white unit of AAI: Dec = 173.7; Inc = 31.2; α95 = 0.7; k = 2749; and 10 sites in the pink unit of AAI; Dec = 173.6; Inc = 30.3; α95 = 1.2; k = 1634), showing no evidence of secular variation, the time gap between emplacement of the two units is unlikely to exceed a few years. The >50 m thick well-consolidated white underlying unit of the Arequipa airport ignimbrite provides a very specific magnetic zonation with low magnetic susceptibilities, high coercivities and unblocking temperatures of NRM above 580°C indicating a Ti-poor titanohematite signature. The Anisotropy of Magnetic Susceptibility (AMS) is strongly enhanced in this layer with anisotropy values up to 1.25. The fabric delineated by AMS was not recognized neither in the field nor in thin sections, because most of the AAI consists in a massive and isotrope deposit with no visible textural fabric. Pumices deformation due to welding is only observed at the base of the thickest sections. AMS within the AAI ignimbrite show a very well defined pattern of apparent imbrications correlated to the paleotopography, with planes of foliation and lineation dipping often at more than 20° toward the expected vent, buried beneath the Nevado Chachani volcanic complex. In contrast with the relatively small extent of the thick AAI, the La Joya ignimbrite covers large

  13. The evolution of the magmatic arc of Southern Peru (200-60 Ma), Arequipa area: insight from geochemical modeling

    Science.gov (United States)

    Demouy, S.; Benoit, M.; De Saint Blanquat, M.; Brunet, P.

    2012-12-01

    Cordilleran-type batholiths are built by prolonged arc activity along continental margins and may provide detailed magmatic records of the subduction system evolution. The magmas produced in subduction context involve both mantellic and crustal end members and are subject to various petrological processes. The MASH zones (Hildreth and Moorbath, 1988), at the basis of the continental crust, are the best places for the genesis of such hybrid magmas. The various geochemical signatures observed in the plutonic rocks, may also be attributed to source heterogeneities or generated by subsequent petrological processes. This study has focused in the Arequipa section of the Coastal Batholith of Southern Peru (200-60 Ma), in an area extending over 80x40 km. Major and trace elements as well as Sr and Nd isotopic analyses were performed in a set of 100 samples ranging from gabbro to granite. The obtained data highlight the wide heterogeneity of the geochemical signatures that is not related to the classification of the rocks. In first step, Rb/Sr systematic was used to isolate a set of samples plotting along a Paleocene isochron and defining a cogenetic suite. This suite appears to have evolved by simple fractional crystallization. By using reverse modeling, the parameters controlling the fractional crystallization process were defined, as partition coefficients, initial concentrations and amount of fractional crystallization. The other magmatic suites display a wide range of isotopic and geochemical signatures. To explain this heterogeneity, a model involving competition between fractional crystallization and magma mixing into MASH zones was proposed. A large range of hybrid magma types is potentially generated during the maturation of the system, but this range tends to disappear as fractionation and mixing occurs. Finally the model predicts the genesis of a homogeneous reservoir created at depth, from which magmas may evolve only by fractional crystallization. Therefore

  14. Observations regarding the movement of barchan sand dunes in the Nazca to Tanaca area of southern Peru

    Science.gov (United States)

    Parker Gay, S.

    1999-03-01

    Significant studies of sand dunes and sand movement made in coastal southern Peru in 1959-1961 [Gay, S.P., 1962. Origen, distribución y movimiento de las arenas eólicas en el área de Yauca a Palpa. Boletin de la Sociedad Geologica del Perú 37, 37-58] have never been published in the English language and consequently have never been referred to in the standard literature. These studies contain valuable information, not developed by later workers in this field, that may be of broad general interest. For example, using airphotos of barchan dunes and plotting the rates of movement vs. dune widths, the author quantified the deduction of Bagnold [Bagnold, R.A., 1941. The Physics of Blown Sand and Desert Dunes. Methuen, London.] that the speed of barchan movement is inversely proportional to barchan size (as characterized by height or width). This led to the conclusion that all barchans in a given dune field, regardless of size, sweep out approximately equal areas in equal times. Another conclusion was that collisions between smaller, overtaking dunes and larger dunes in front of them do not result in destruction or absorption of the smaller dunes if the collision is a `sideswipe'. The dunes simply merge into a compound dune for a time, and the smaller dune then moves on intact, i.e., passes, the larger dune, whilst retaining its approximate original size and shape. Another result of the 1959-1961 studies was a map that documents the Pacific coast beaches as the source of the sand ( Fig. 1), which is then blown inland through extensive dune fields of barchans and other dune forms in great clockwise-sweeping paths, to its final resting place in huge sand masses, sometimes called `sand seas' [Lancaster, N., 1995. Geomorphology of Desert Dunes. Routledge, London], at higher elevations 20 to 60 km from the coast. A minor, but nevertheless interesting, discovery was a small heavy mineral dune located directly in the lee of a large barchan, evidently formed by the winnowing

  15. Structural Control of the Ubinas-Huaynaputina-Ticsani System: A Large, Young Silicic Magmatic System in Southern Peru

    Science.gov (United States)

    Lavallee, Y.; de Silva, S. L.; Salas, G.; Byrnes, J.

    2003-12-01

    The location of magma reservoirs and volcanic centers are commonly controlled by tectonic structures (e.g., Hutton, 1989; Gibbons and Moreno, 2002). In the Central Volcanic Zone, southern Peru, volcanism is mainly associated with the major NNW-SSE sinistral strike slip fault systems underlying the main volcanic arc. However, a group of related silicic volcanoes was recently discovered which crop out beyond the arc; the Ubinas-Huaynaputina-Ticsani system (UHTS). Characterizing its dimension and tectonic influences are crucial in order to evaluate corresponding volcanic hazards. Potentially active fault systems as well as major tectonic features in and around the UHTS were mapped and the structural framework was elucidated. The UHTS is located within a north to south extensional domain housing three fault systems: (1) the arc related NNW-SSE fault system, intersected by (2) a unique N-S en echelon strike slip fault system, and (3) a minor W-E fault system. Identification of confined Cretaceous volcanics known as the Matalaque formation indicated the presence of a narrow graben that developed on the western side of the N-S fault system. Interestingly all volcanic centers are positioned at the intersection of the NNW-SSE faults with the N-S faults. Seismic records revealed the concentration of seismicity around depths ranging between 20 and 33 km. The position of the UHTS is dictated by the intersection of the NNW-SSE and N-S major en echelon strike slip fault systems. We propose the role of the NNW-SSE fault as a deep pathway for magma ascent whereas the N-S strike-slip motion allowed the release of stress and deviation of magma, which scattered and ponded between adjacent NNW-SSE faults at ~30 km depths. Based on the vent distribution, we estimated the size of the silicic magma reservoir as approximately 40 x 60 km; this is a reasonable estimate since the withdrawal of a volume larger than 10 km3 was not significant enough to produce an equivalent caldera collapse

  16. Environmental evolution of the Rio Grande drainage basin and Nasca region (Peru) in 2003-2007 using ENVISAT ASAR and ASTER time series

    Science.gov (United States)

    Cigna, Francesca; Tapete, Deodato; Lasaponara, Rosa; Masini, Nicola

    2013-04-01

    Recent palaeo-environmental studies and remote sensing investigations demonstrated that the Rio Grande drainage basin in Southern Peru is a still evolving landscape, and impacts due to its changes have implications for the preservation of both the natural and cultural features of the Nasca region, well-known for the evidences of the ancient Paracas and Nasca Civilizations, who flourished from the 4th century BC to the 6th century AD. To image the modifications occurred in the last decade, we exploited the entire 4year-long stack of ENVISAT ASAR C-band archive imagery available over the region, which was provided by the European Space Agency (ESA) via the Cat-1 project 11073. The latter supports the activities of the Italian mission of heritage Conservation and Archaeogeophysics (ITACA), which directly involve researchers from the Institute for Archaeological and Monumental Heritage (IBAM) and the Institute of Methodologies for Environmental Analysis (IMAA), National Research Council (CNR) of Italy. With the aim of reconstructing the temporal evolution of the Rio Grande drainage basin and its effects and implications for the heritage of the region, we processed 8 ASAR Image Mode IS2 scenes acquired in descending mode between 04/02/2003 and 15/11/2005 and 5 images in ascending mode between 24/07/2005 and 11/11/2007, and focused on SAR backscattering information, amplitude change detection methods and extraction of ASAR-derived time series of the backscattering coefficient over target areas of interest. The ASAR 2003-2007 analysis was coupled and integrated with NDVI-based soil moisture and vegetation change assessment performed by using ASTER multi-spectral data acquired during the same time frame of the ASAR stacks, on 30/05/2003, 01/06/2004 and 10/06/2007. The research was performed both at the regional scale over the entire Rio Grande drainage basin, with particular focus on its tributaries Rio Ingenio, Rio Nazca and Rio Taruga, and at the local scale over the

  17. Glacial recession in the Tropical Andes from the Little Ice Age: the case of Ampato Volcanic Complex (Southern Peru

    Science.gov (United States)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.

    2010-03-01

    Data published over the last decade reveal substantial glacial recession in the tropical Andes since the Little Ice Age (LIA), (Ramirez, et al., 2001; Rabatel, et al., 2005; Rabatel, et al., 2008; Vuille, et al., 2008; Hastenrath, 2009; Jomelli, et al., 2009), and a growing rate of recession since the 1980’s caused by global warming (Ramirez, et al., 2001; Vuille, et al., 2008). Today there is great interest in the evolution of these ice masses due to heightened awareness of climate change and of the strategic importance that glaciers have as a hydrologic resource for communities in arid climate zones in the tropical Andes (Mark, 2008; Vuille et al., 2008). Cordillera Blanca forms part of the Andes Mountains of northern Peru, and is a chosen site for many studies on glacier evolution. Vuille et al. 2008 determined that a considerable area of ice mass was lost at Huascarán-Chopicalqui glacier (18% from 1920-1970) and Astesonraju glacier (20% from 1962-2003). Studies at Coropuna volcano, which has the most extensive glacier field in the western range of southern Peru, also report a strong melting trend that began with only minimal recession from 1955-1986 (4%), but increased to 14% from 1986-2007 (Úbeda et al., 2009). Only a few of the Andes glaciers are consistently monitored, and the most comprehensive data are for Chacaltaya and Zongo glaciers (16º S) in Bolivia. Since the maximum LIA, Chacaltaya has lost 89% of its surface area, particularly in recent years. By 1983, the totaled loss was five times the shrinkage for the period 1940-1963 (Ramirez, et al., 2001). Zongo glacier maintained equilibrium from 1956-1975, but later experienced a period dominated by continuous recession (Soruco, et al., 2009). This study expands current knowledge of glacier evolution since the LIA in the Central Volcanic Zone (CVZ; 14º - 27º S) (Stern, 2004) of the Andes. The study site was chosen in an area that had never been used for preliminary research of this type, concretely

  18. Plate interactions control middle late Miocene, proto-Gulf and Basin and Range extension in the southern Basin and Range

    Science.gov (United States)

    Henry, Christopher D.; Aranda-Gomez, J. Jorge

    2000-03-01

    Middle-late Miocene (proto-Gulf; ˜12-6 Ma) extension around the Gulf of California (Gulf Extensional Province) is commonly interpreted as resulting from partitioning of oblique Pacific-North American plate motion into strike-slip displacement along the margin and east-northeast extension perpendicular to the margin within the North American plate. We propose that this mechanism also applies to kinematically similar, predominantly east-northeast extension that occurred at the same time throughout the southern Basin and Range province, from southern Arizona and New Mexico to the Trans-Mexican Volcanic Belt. New field and 40Ar/ 39Ar data in Sinaloa and Durango confirm that this episode of extension occurred on the mainland side of the Gulf and in the Basin and Range east of the Sierra Madre Occidental, which is generally considered the eastern margin of the Gulf Extensional Province. Published data indicate the middle-late Miocene episode also occurred across the northern and southern ends of the Sierra Madre where the Gulf Extensional Province connects with the Basin and Range: (1) from central Sonora into southern Arizona and New Mexico, and (2) from Nayarit into central Mexico north of the Trans-Mexican Volcanic Belt. This episode appears to have affected an area that continues to the eastern edge of the Basin and Range province in Texas and San Luis Potosi. Recognition that this episode of extension affected the entire southern Basin and Range resolves the discrepancy between the amount of extension calculated based on plate reconstructions and that based on field data within the Gulf Extensional Province alone. Published plate reconstructions require 160 to 110 km of east-northeast extension between ˜12 and 6 Ma. If taken up solely within the Gulf Extensional Province, this would have generated 66 to 78% extension, which is much greater than observed. Spread across the entire southern Basin and Range it requires only ˜20% total extension, which is more

  19. Origin of Meter-Size Granite Basins in the Southern Sierra Nevada, California

    Science.gov (United States)

    Moore, James G.; Gorden, Mary A.; Robinson, Joel E.; Moring, Barry C.

    2008-01-01

    Meter-size granite basins are found in a 180-km belt extending south from the South Fork of the Kings River to Lake Isabella on the west slope of the southern Sierra Nevada, California. Their origin has long been debated. A total of 1,033 basins have been inventoried at 221 sites. The basins occur on bedrock granitic outcrops at a median elevation of 1,950 m. Median basin diameter among 30 of the basin sites varies from 89 to 170 cm, median depth is 12 to 63 cm. Eighty percent of the basin sites also contain smaller bedrock mortars (~1-2 liters in capacity) of the type used by Native Americans (American Indians) to grind acorns. Features that suggest a manmade origin for the basins are: restricted size, shape, and elevation range; common association with Indian middens and grinding mortars; a south- and west-facing aspect; presence of differing shapes in distinct localities; and location in a food-rich belt with pleasant summer weather. Volcanic ash (erupted A.D. 1240+-60) in the bottom of several of the basins indicates that they were used shortly before ~760 years ago but not thereafter. Experiments suggest that campfires built on the granite will weaken the bedrock and expedite excavation of the basins. The primary use of the basins was apparently in preparing food, including acorns and pine nuts. The basins are among the largest and most permanent artifacts remaining from the California Indian civilization.

  20. A new structural model of the Pachitea Basin, Peru: Interaction of thick-skinned tectonics and salt detached thrusting

    Science.gov (United States)

    Witte, J.; Rebaza, J.; Westlund, D.; Stratton, M.; Alegria, C.

    2015-11-01

    We present four new structural transects, a new seismo-stratigraphic correlation, a refined structural model and new shortening rates for the Pachitea Basin (=PB), Peru. Our results are based on the integration and detailed interpretation of newly acquired industry seismic (2D, 2005 vintage), existing well data, existing and proprietary surface geology data and newly acquired aero magnetic data (2007 vintage). Our assessment confirms the presence of at least four distinct structural styles in the area, thick-skinned structures, thin-skinned detachment thrusting, salt-tectonics and localized strike-slip tectonics. Based on seismo-stratigraphic correlations we conclude that the oldest rocks carried to outcrop by the San Matias (=SM) thrust are of Jurassic age. We interpret the thin-skinned master detachment to be located in varying positions, directly below or above, autochtonous salt pillows. Timing assessment of the SM thrust sheet reveals that it has been active from at least ˜5 Ma to post-2 Ma, supporting regionally published timing data for this latitude. Positive topographic surface expressions indicate ongoing contraction along the mountain front of the Peruvian Eastern Cordillera (=EC). Across the PB we calculate between 2.6% and 5.5% for thick-skinned shortening and at least 25.5% for the thin-skinned shortening. For the SM thrust sheet we calculate a slip-rate of ˜1-1.6 mm/yr, which is in line with published slip rates on individual thrusts from around the world. Observations along the SM thrust system indicate that thin- and thick-skinned systems interact mechanically, and that they have been active intermittently. We conclude that the location of salt pillows as well as pre-existing or growing basement-involved structures helped trigger the SM thrust. Different types of salt bodies are present in the PB, autochtonous pillows, slightly thrusted pillows and allochtonous diapirs. Our results provide new insight into the structural interplay, particularly

  1. Modeling anomalous surface - wave propagation across the Southern Caspian basin

    Energy Technology Data Exchange (ETDEWEB)

    Priestly, K.F.; Patton, H.J.; Schultz, C.A.

    1998-01-09

    The crust of the south Caspian basin consists of 15-25 km of low velocity, highly attenuating sediment overlying high velocity crystalline crust. The Moho depth beneath the basin is about 30 km as compared to about 50 km in the surrounding region. Preliminary modeling of the phase velocity curves shows that this thick sediments of the south Caspian basin are also under-lain by a 30-35 km thick crystalline crust and not by typical oceanic crust. This analysis also suggest that if the effect of the over-pressuring of the sediments is to reduce Poissons` ratio, the over-pressured sediments observed to approximately 5 km do not persist to great depths. It has been shown since 1960`s that the south Caspian basin blocks the regional phase Lg. Intermediate frequency (0.02-0.04 Hz) fundamental mode Raleigh waves propagating across the basin are also severely attenuated, but the low frequency surface waves are largely unaffected. This attenuation is observed along the both east-to-west and west-to-east great circle paths across the basin, and therefore it cannot be related to a seismograph site effect. We have modeled the response of surface waves in an idealized rendition of the south Caspian basin model using a hybrid normal mode / 2-D finite difference approach. To gain insight into the features of the basin which cause the anomalous surface wave propagation, we have varied parameters of the basin model and computed synthetic record sections to compare with the observed seismograms. We varied the amount of mantel up-warp, the shape of the boundaries, the thickness and shear wave Q of the sediments and mantle, and the depth of the water layer. Of these parameters, the intermediate frequency surface waves are most severely affected by the sediments thickness and shear wave attenuation. fundamental mode Raleigh wave phase velocities measure for paths crossing the basin are extremely low.

  2. Factors influencing the productivity of irrigated crops in Southern Peru, in relation to prediction by simulation models

    NARCIS (Netherlands)

    Versteeg, M.N.

    1985-01-01

    The objective of the study was to determine the growth potential of alfalfa, potato, Rhodes grass and maize in the irrigated desert of S. Peru, as at that production level the highest utilization efficiency of irrigation water is usually obtained. Important growth- influencing factors were identifie

  3. USING SRTM TO QUANTIFY SIZE PARAMETERS AND SPATIAL DISTRIBUTION OF ENDORHEIC BASINS IN SOUTHERN SOUTH AMERICA

    Directory of Open Access Journals (Sweden)

    Ralf Hesse

    2008-08-01

    Full Text Available The SRTM data set is the highest resolution DEM with global or continental coverage. It is therefore theDEM of choice for continental-scale geomorphological mapping and quantitative analysis. In this study,SRTM data are used for the identification and characterisation of endorheic basins in southern SouthAmerica (south of 19°S. The results show the feasibility of continental-scale quantitative geomorphologybased on SRTM data and provide insights into the distribution of closed basins. The largest endorheicbasin is located in the Puna region and consists of several interconnected sub-basins. This basin accountsfor 38.6 % (7877 km3 of the total volume of the endorheic basins identified in this study. Analyses of thegeographic distribution show a narrow longitudinal distribution between 64.5 and 71.5° W and a multimodallatitudinal distribution which is characterised by two groups of basins at 22.5–27.5°S and 37.5–50.0° Sand an almost complete absence of basins between 27.5 and 37.5° S. Problems and sources ofmisinterpretation arising from data quality and resolution are discussed. Further research, targeting in particularthe genesis and potential for paleoenvironmental reconstruction of closed basins in southern Argentina, iscalled for.

  4. MAPEO FOTOGRAMÉTRICO EN ARQUEOLOGÍA: EXPERIENCIAS DESDE EL PROYECTO RAMIS, CUENCA NORTE DEL TITICACA, PERÚ (Photogrammetric Mapping in Archaeology: Experiences from the Ramis Project, Northern Titicaca Basin, Peru

    Directory of Open Access Journals (Sweden)

    Luis A. Flores

    2015-10-01

    Full Text Available El registro arqueológico en tiempo real, desde el propio campo, se ha vuelto una práctica casi común para muchos arqueólogos. Aunque reemplazar el papel por la pantalla táctil aún sigue trayendo dudas y controversias. En este breve reporte queremos compartir una experiencia de registro usando un mapeo digital fotogramétrico en un sistema SIG, que fue practicado en la cuenca del Titicaca, una región altiplánica al sur del Perú, donde demostramos que este método de recolección de datos puede traer no solo rapidez sino también precisión en las mediciones. ENGLISH: The recording of archaeology in real-time, from the field itself, has become common practice for many archaeologists. Still, replacing paper with touch screens continues to raise doubts and cause controversies within the discipline. In this brief report, we want to share an experience recording in the field using digital photogrammetric mapping in GIS. This project was carried out in the Lake Titicaca Basin, a highland region in southern Peru, where we demonstrated that this method of recording data can not only bring faster, but more accurate measurements than older methods.

  5. Modification of Thickened Orogenic Crust by a Subducting Ridge: Disruption of the Andean Lower Crust of Southern Peru by the Subducting Aseismic Nazca Ridge

    Science.gov (United States)

    Bishop, B.; Beck, S. L.; Zandt, G.; Wagner, L. S.; Long, M. D.; Tavera, H.

    2015-12-01

    The subduction of oceanic plateaus or aseismic ridges represent significant perturbations to the long term development of subduction systems and associated orogenies, the consequences of which are variable and determined by the physical characteristics of both the overriding and subducting plates. Flat subduction of the ~18 km oceanic crust of the aseismic Nazca Ridge under the 50 km to 65 km continental crust of the Peruvian Andes provides an opportunity to investigate these consequences. Through analysis of 2233 teleseismic P-wave receiver functions from 55 broadband seismometers deployed in southern Peru for the PULSE, CAUGHT and PeruSE seismic experiments we have identified the South American continental Moho and subducted Nazca oceanic Moho to a higher degree of detail than previously possible in the region.We find that the continental Moho beneath the Western and Eastern Cordilleras of the Peruvian Andes is at a depth >60 km to the north and south of the subducted Nazca Ridge but at 500 km from the trench.

  6. Late Triassic uplift of southern Norway revealed by detrital zircons in the Norwegian-Danish Basin

    Science.gov (United States)

    Olivarius, Mette; Nielsen, Lars H.; Weibel, Rikke; Kristensen, Lars; Thomsen, Tonny B.

    2016-04-01

    Zircon U/Pb geochronometry is used to identify the sediment source areas of the Upper Triassic to Lower Jurassic shallow marine to paralic Gassum Formation in the Norwegian-Danish Basin. The analyses of zircon grains from geographically and stratigraphically widely distributed cores take advantage of the detailed sequence stratigraphic framework existing for the succession. The zircon ages indicate that the sediment in the lower part of the Gassum Formation in the northern and central parts of the basin was supplied solely from the Telemarkia Terrane in the southern part of southern Norway. However, age signatures from other basement terranes were added during periods of transgression presumably as a result of longshore reworking. The sediment in the eastern part of the basin has a different provenance signature that reflects supply from various sources of which some or all seemingly include older sediments. The basinwide fluvial incision that occurred during a relative sea-level fall in the Rhaetian is interpreted to be related to uplift of southern Norway since a pronounced content of zircon grains with U/Pb ages of 1.65 Ga were introduced in the Norwegian-Danish Basin at the time. This age is dominant in the upper part of the Gassum Formation and is present in all studied younger sediments in the Norwegian-Danish Basin, whereas it is missing in older sediments in the basin. Rocks with corresponding ages are presently exposed in the Jotun Nappe Complex and the Western Gneiss Complex in the central and northern parts of southern Norway. Thus, major faulting activity must have occurred in southern Norway during the Late Triassic that made such rocks available for erosion with permanent southeastwards drainage.

  7. Characteristics of seismostratigraphy and analysis of structural- lithofacies in the southern Yellow Sea Cenozoic basin

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper, the upper structural layer of the southern Yellow Sea Basin (SYSB) is further divided into three layers based on the latest obtained high-resolution single-channel seismic profiles. Combined with the borehole data, the characteristics and evolvement of structure and environment since middle-late Tertiary are discussed. The study shows that the acoustic-base indicated by shallow seismic profiles represents the basic shape of the SYSB in late Oligocene-early Miocene. Based on the comprehensive analysis of some typical profiles crossing the basin about seismostratigraphy, gravity and magnetics, the basin edge fault and some basin inner structure are identified. Furthermore, the acoustic-base is classified into four types of basal lithofacies: Eogene basin basement, Paleozoic basement, Mesozoic basement and magma intrusion basement.

  8. New insights into the mechanism of postseismic stress relaxation exemplified by the 23 June 2001 Mw = 8.4 earthquake in southern Peru

    Science.gov (United States)

    Hergert, Tobias; Heidbach, Oliver

    2006-01-01

    The 2001 Mw = 8.4 southern Peru subduction earthquake marked the beginning of a transient postseismic surface motion in direction of the coseismic displacement at the permanent GPS station Arequipa. In general this motion is assigned to afterslip. Our hypothesis is that the observed transient signal can be explained by stress relaxation processes in the overriding plate. We use a 2D finite element model incorporating non-linear viscoelastic Maxwell rheology. Our model results indicate that coseismically induced stresses are relieved by viscoelastic stress relaxation in the lower crust. The trenchward directed creep motion is transferred to the upper crust due to elastic coupling leading there to an instantaneous relief of elastic stresses. In contrast to the existing conceptual models for stress relaxation, which incorporate shear stresses, we conclude that tensional elastic stresses throughout the crust and upper mantle are the main driving forces for the transient GPS signal.

  9. Magma sources and mixing for the Coastal Batholith in southern Peru: insights from new elemental and isotopic data and from comparison with California batholithic rocks

    Science.gov (United States)

    Clausen, B. L.; Martinez, A. M.; Gonzalez, L. U.; Poma, O.; Paterson, S. R.; Ianno, A.

    2013-12-01

    depth, and least alkalinity] is the low-Sri (>To interpret the new Peru data: The range of SiO2 indicates extent of magma differentiation versus mixing with only low SiO2 in Pampahuasi, high SiO2 in Tiabaya, and a range of SiO2 in the other two super-units. The size of the range aids in determining whether the emplacement was during compression or extension. The crustal contamination increases from west to east, with relative proportions of mantle and lower crustal source dependant on local thickness of the crust; the Coastal Batholith in the Ica area is intermediate between having a primary mantle component as in central Peru where the crust is thin and having a significant crustal component in southern Peru where the crust is thick. The magma source depth ranges from shallow in the west to intermediate in the east with Tiabaya from the deepest source. The calc-alkalinity shows a slight trend of increasing alkalinity toward the east. The alumina content shows these rocks as metaluminous with a slightly higher content in the east than west, suggesting an increased crustal component. The TiO2/Fe2O3 ratios suggest a slight increase in the ilmenite to magnetite composition from west to east.

  10. A see-saw of pre-Columbian boom regions in southern Peru, determined by large-scale circulation changes

    Science.gov (United States)

    Mächtle, B.; Schittek, K.; Forbriger, M.; Schäbitz, F.; Eitel, B.

    2012-04-01

    Environmental changes and cultural transitions during several periods of Peruvian history show a strong coincidence between humid and dry climatic oscillations and the rise and decline of cultures. It is noteworthy, that alternating periods of geo-ecological fragility and stability occurred in time and space between the coastal Nasca region (14.5° S) and the high Andean northern Titicaca basin, just a few hundred kilometers to the east. Based on a multi-proxy palynological and sedimentological approach to reconstruct palaeoenvironmental changes, we found that the Nasca region received a maximum of precipitation during the archaeological boom times of the Early Horizon and the Early Intermediate Period (800 BC - 650 AD, Paracas and Nasca cultures) as well as during the late intermediate period (1150-1450 AD), whereas, in contrast, the Titicaca region further to the south-east experienced drought and cultural depression during that times. During the Middle Horizon (650 - 1150 AD), the Tiwanaku agronomy and culture boomed in the Titicaca region and expanded to the west, contemporaneous with a raised lake level and more humid conditions. In the Nasca region, runoff for irrigation purposes was reduced and less reliable due to drought. Considering a coincidence between environmental and cultural changes, we state that success and decline of civilizations were controlled by hydrological oscillations, triggering fertility as well as a critical loss of natural resources. In response to spatial changing resources, cultural foci were shifted. Therefore, the success of pre-Columbian civilizations was closely coupled to areas of geo-ecological favorability, which were directly controlled by distinct regional impacts of large-scale circulation mechanisms, including El Niño - Southern Oscillation (ENSO). Changes in the position of the intertropical convergence zone (ITCZ) and the Bolivian anticyclone determined meridional shifts in moisture transport across the Andes, which

  11. Permafrost and Periglacial Activity Distribution and Geothermal Anomalies in the Chachani and El Misti Volcanoes (Southern Peru)

    Science.gov (United States)

    Palacios, D.; Andrés, N.; Úbeda, J.; Alcalá, J.

    2009-04-01

    /year, records only one cycle/year. At the crater, there are 80 yearly cycles at 30 cm and none at 100 cm. The conclusion from the results obtained from the thermometers leads to the following hypothesis: the permafrost distribution on the mountains surrounding Arequipa city starts at an altitude of 5450 m for climatic reasons, but the area of maximum periglacial activity is located in a belt between the altitudes of 4900 and 5400 m, although always at very limited depths, and is non-existent at more than 80 cm. These climatic values are cancelled out on El Misti by substantial geothermal heat which does not only act at a few localized spots, as has been described for other volcanoes (Palacios et al., 2007): it affects the whole volcano, although naturally to a greater extent at the summit, where the crater is located. Even the air temperature is affected, but it is the ground temperature which is basically and drastically changed, eliminating any possibility of glacial accumulation or permafrost, and reducing the depth of periglacial activity to only the first few centimeters of the ground. This activity is more significant at altitudes much greater than expected from the climatic conditions. References.- Dornbusch, U., 2001. Modern and Last Local Glacial Maximum snowlines in the Central Andes of Peru, Bolivia, and Northern Chile. Quaternary Science Reviews 18, 63-84. Paquereau, P.; Thouret, J-C.; Worner, G.; & Fornari, M., 2006. Neogene and Quaternary ignimbrites in the area of Arequipa, southern Peru: stratigraphical and petrological correlations. J Volc Geotherm Res, 154: 251-275. Palacios, D.; Zamorano, J.J.; & Andrés, N., 2007. Permafrost distribution in tropical stratovolcanoes: Popocatépetl and Iztaccíhuatl volcanoes (Mexico). Geophysical Research Abstracts 9: 05615. Thouret, J-C.; Finizola, A.; Fornary, M.; Suni, J. & Frechen. M., 2001. Geology of El Misti volcano near the city of Arequipa, Peru. Geological Society of America Bulletin, 113(12): 593-610.

  12. The late Quaternary tephrostratigraphical record of the San Gregorio Magno basin (southern Italy)

    Science.gov (United States)

    Munno, R.; Petrosino, P.

    2007-03-01

    Twenty-one primary pyroclastic layers were found embedded in the lacustrine sediments of the San Gregorio Magno basin (Southern Apennines). These sand-sized layers were characterised by a noticeable juvenile fragments content and by a sharp basal contact with the underlying clay and silt sediments. The tephra layers have been correlated with terrestrial counterparts from well-known eruptive events of the Campanian volcanic area, or with reference layers from deep sea sediment cores and from the Monticchio maar sequence. The investigation of the San Gregorio Magno tephra layers made it possible to deduce that lacustrine sedimentation at San Gregorio Magno basin began before 170k yr BP and lasted at least until the emplacement of the Neapolitan Yellow Tuff, which occurred about 15k yr BP. The tephrochronology allowed determination of the varying sedimentation rate that occurred in the basin. Correlation of the lacustrine record with marine sequences has allowed development of a late Quaternary tephrostratotype for southern Italy. Copyright

  13. Chrysobrycon eliasi, new species of stevardiine fish (Characiformes: Characidae from the río Madre de Dios and upper río Manuripe basins, Peru

    Directory of Open Access Journals (Sweden)

    James Anyelo Vanegas-Ríos

    Full Text Available Chrysobrycon eliasi is described from several drainages of río Madre de Dios and upper río Manuripe basins, río Madeira basin, Peru. The new species is distinguished from its congeners by the maxillary teeth, which are tricuspidate, bicuspidate and conical, and the terminal lateral-line tube developed between caudal-fin rays 10-11. Other characters that help to recognize C. eliasi are the possession of maxilla with 6-15 (usually 11 teeth occupying more than 70% of the length of the maxilla in adults, predorsal scales 18-22, dorsal-fin to hypural complex length 36.32-41.17% of standard length (SL, gill-gland length in males 3.57-5.05% SL, maxillary length 33.76-38.75% of head length, and branched anal-fin rays 24-30. The discovery of C. eliasi allows us to extend the geographic distribution of the genus to the southeast, into the río Madeira basin.

  14. Focal mechanisms in the southern Dead Sea basin and related structural elements based on seismological data

    Science.gov (United States)

    Hofstetter, A.; Dorbath, C.; Dorbath, L.

    2014-12-01

    A dense temporary local seismological network was operated from 10/2006 to 3/2008 in the southern Dead Sea basin also outside the basin within the framework of the DESIRE (DEad Sea Integrated REsearch) project, providing many recordings of local earthquakes. We used the recordings of DESIRE and also the recordings of the permanent networks of Israel Seismic Network, Israel, and Jordan Seismic Observatory, Jordan. We determined high quality focal plane solutions of 490 events, using at least 6 stations (normally >10 stations) with a good station distribution around the epicenters. In the southern Dead Sea basin and adjacent regions there are several clusters of earthquakes. Most of the activity occurred along the eastern bordering fault of the basin, in the Lisan Peninsula and just south and north of it. Along the eastern and western bordering faults we observe mainly strike slip mechanism, probably supporting the left lateral motion along the Dead Sea fault. The nodal planes of many of focal mechanisms inside the basin are parallel to the transverse faults crossing the basin, i.e., Bokek and Ein-Gedi faults, and also parallel to faults that border the Lisan Peninsula on the north-western and south-western sides.

  15. Basement structure of the Granada basin, Betic Cordilleras, southern Spain

    Science.gov (United States)

    Morales, J.; Vidal, F.; De Miguel, F.; Alguacil, G.; Posadas, A. M.; Ibañez, J. M.; Guzmán, A.; Guirao, J. M.

    1990-06-01

    The analysis and interpretation of geophysical data (gravity and seismic reflection) has facilitated the definition of the Granada basin structure. The reflector showing the contact between the Betic-Subbetic basement and the Neogene-Quaternary sedimentary filling has been identified. Mapping of the basement in two and three dimensions is presented. The presence of four important depocenters (Genil, Chimeneas, Cubillas and Granada) has been determined. These troughs are limited by ridge areas through important sets of fractures. In some cases the accumulation of Neogene-Quaternary sediments reaches a thickness exceeding 3 km as in the Genii and Cubillas depocenters. The mapping of the most important fractures affecting the basement has been achieved, defining four systems that have influenced and conditioned the genesis and late evolution of the Granada basin. The directions of the most important groups of fractures are: NE-SW, N70W to E-W, N45W and N10-30E.

  16. Imaging the transition from flat to normal subduction: variations in the structure of the Nazca slab and upper mantle under southern Peru and northwestern Bolivia

    Science.gov (United States)

    Scire, Alissa; Zandt, George; Beck, Susan; Long, Maureen; Wagner, Lara; Minaya, Estela; Tavera, Hernando

    2016-01-01

    Two arrays of broad-band seismic stations were deployed in the north central Andes between 8° and 21°S, the CAUGHT array over the normally subducting slab in northwestern Bolivia and southern Peru, and the PULSE array over the southern part of the Peruvian flat slab where the Nazca Ridge is subducting under South America. We apply finite frequency teleseismic P- and S-wave tomography to data from these arrays to investigate the subducting Nazca plate and the surrounding mantle in this region where the subduction angle changes from flat north of 14°S to normally dipping in the south. We present new constraints on the location and geometry of the Nazca slab under southern Peru and northwestern Bolivia from 95 to 660 km depth. Our tomographic images show that the Peruvian flat slab extends further inland than previously proposed along the projection of the Nazca Ridge. Once the slab re-steepens inboard of the flat slab region, the Nazca slab dips very steeply (˜70°) from about 150 km depth to 410 km depth. Below this the slab thickens and deforms in the mantle transition zone. We tentatively propose a ridge-parallel slab tear along the north edge of the Nazca Ridge between 130 and 350 km depth based on the offset between the slab anomaly north of the ridge and the location of the re-steepened Nazca slab inboard of the flat slab region, although additional work is needed to confirm the existence of this feature. The subslab mantle directly below the inboard projection of the Nazca Ridge is characterized by a prominent low-velocity anomaly. South of the Peruvian flat slab, fast anomalies are imaged in an area confined to the Eastern Cordillera and bounded to the east by well-resolved low-velocity anomalies. These low-velocity anomalies at depths greater than 100 km suggest that thick mantle lithosphere associated with underthrusting of cratonic crust from the east is not present. In northwestern Bolivia a vertically elongated fast anomaly under the Subandean Zone

  17. Linkages Between Cretaceous Forearc and Retroarc Basin Development in Southern Tibet

    Science.gov (United States)

    Orme, D. A.; Laskowski, A. K.

    2015-12-01

    Integrated provenance and subsidence analysis of forearc and retroarc foreland basin strata were used to reconstruct the evolution of the southern margin of Eurasia during the Early to Late Cretaceous. The Cretaceous-Eocene Xigaze forearc basin, preserved along ~600 km of the southern Lhasa terrane, formed between the Gangdese magmatic arc and accretionary complex as subduction of Neo-Tethyan oceanic lithosphere accommodated the northward motion and subsequent collision of the Indian plate. Petrographic similarities between Xigaze forearc basin strata and Cretaceous-Eocene sedimentary rocks of the northern Lhasa terrane, interpreted as a retroarc foreland basin, were previously interpreted to record N-S trending river systems connecting the retro- and forearc regions during Cretaceous time. New sandstone petrographic and U-Pb detrital zircon provenance analysis of Xigaze forearc basin strata support this hypothesis. Qualitative and statistical provenance analysis using cumulative distribution functions and Kolmogorov-Smirnov (K-S) tests show that the forearc basin was derived from either the same source region as or recycled from the foreland basin. Quartz-rich sandstones with abundant carbonate sedimentary lithic grains and rounded, cobble limestone clasts suggests a more distal source than the proximal Gangdese arc. Therefore, we interpret that the northern Lhasa terrane was a significant source of Xigaze forearc detritus and track spatial and temporal variability in the connection between the retro- and forearc basin systems during the Late Cretaceous. A tectonic subsidence curve for the Xigaze forearc basin shows a steep and "kinked" shape similar to other ancient and active forearc basins. Initial subsidence was likely driven by thermal relaxation of the forearc ophiolite after emplacement while additional periods of rapid subsidence likely result from periods of high flux magmatism in the Gangdese arc and changes in plate convergence rate. Comparison of the

  18. Reconstruction of Equilibrium Line Altitudes of Nevado Coropuna Glaciers (Southern Peru) from the Late Pleistocene to the present

    Science.gov (United States)

    Úbeda, J.; Palacios, D.; Vázquez, L.

    2009-04-01

    The Nevado Coropuna (15°31'S-72°39'W) is a volcanic complex located 200 km NE of the city of Arequipa, in the Southern Peruvian Andes. The summit area in the complex is covered with a glacier system formed by dozens of branches descending in all directions totaling many km2 in surface area. The study of the volcanic complex and its glaciers is of great interest because it is the main water reserve for tens of thousands of people, because of the risk scenario created by the presence of ice masses on a volcano with relatively recent activity, and because it constitutes an excellent geoindicator of the effects of climate change on ice masses in the western mountain chain of the Central Andes. This research aims to analyze glacier evolution using as geoindicators variations in glacier surface and equilibrium line altitudes (ELAs), defining deglaciation rates based on those variations and preparing forecasts with them on when the ice masses might disappear if the same rates were to occur in the future. In addition, a first estimation is attempted of the chronologies of the last phase of volcanic activity and the last phase of maximum glacier advance that can be attributed to the Late Glacial or Last Glacial Maximum periods. To achieve these aims, digital topography with 50m contour interval, two orthophotos of the central section of the Coropuna complex (15-6-1955 and 21-10-1986), an ASTER satellite image (12-11-2007) and geomorphological mapping of the volcanic complex created in a previous phase of the research (Ubeda, 2007) were integrated into a Geographical Information System (GIS). The GIS was used to determine the global extent of the glacier system, and in more detail, that of two groups (NE and SE) in 1955, 1986 and 2007. Using the geomorphological cartography as a basis, the extent of the glaciers during their last advance in the Little Ice Age (LIA) and their last maximum advance were calculated. Next, surface areas for all phases were calculated using

  19. Reservoir-forming age and its exploration significance to stratigraphic reservoirs in southern Songliao Basin

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Despite many studies concerning the forming age, evolution characteristics and the age of petroleum charging in the Fuxin upheaval of southern Songliao Basin, no consensus has been reached so far. This paper presents the first K-Ar dating of autogenetic illite from stratigraphic petroleum reservoirs in the Fuyu oil layer of the Fuxin upheaval belt. Isotopic test and age calculation were carried out based on the separation and purification of illite mineral, X-diffraction analysis and the detection of scanning electron microscopy. The evolution characteristics of structure, sedimentation, reservoir-forming about the Fuxin upheaval belt were interpreted in terms of the synthetical analysis of "six-type geological history" evolution in southern Songliao Basin. The geologic background of petroleum evolution and reservoir formation are similar in the entire central depression region of southern Songliao Basin. The Changling sag and the Fuxin upheaval belt brought about obvious upheaval-sag separation after the hydrocarbon-generation peak of K2qn1 and the main reservoir-forming period of the Fuyu oil layer, namely reservoir-forming happened before the Fuxin upheaval belt extensively raised. The reservoirs have three characteristics: the hydrocarbon source rock above the reservoir, the oil source in the locality, and the vertical migration. The geological cognition is corrected, that is, oil source came from the Changling sag and migrated from the side direction. The bulk process of petroleum charging in the stratigraphic hydrocarbon reservoirs in the Fuxin upheaval belt of southern Songliao Basin is determined according to the isotopic age of autogenetic illite in combination with the method of fluid inclusions. The cognition is helpful to exactly evaluate the resource potential and exploration direction in the Fuxin upheaval belt, Changling sag and their peripheral areas. The present results indicate that the combination of the two methods (the K-Ar dating of

  20. Geometric Reconstruction of Bedrock and Overlying Recent Deposits In An Intra-mountain Basin: The Clusone Basin (southern Alps, Italy)

    Science.gov (United States)

    Caielli, G.; Berra, F.

    Regione Lombardia (Direzione Generale Territorio e Urbanistica) and the National Research Council (CNR-IDPA Milano) acquired seismic reflection profiles in the Clu- sone basin (Middle Val Seriana, Southern Alps). In the study area, the bedrock is rep- resented by late Triassic carbonate units (Formazione di Castro, Dolomia Principale and coeval basinal facies, bordered northward by an important alpine fault) covered by a large amount of recent deposits that covers an area of more than 10 km2, with a maximum thickness of more than two hundreds meters, as documented by available well data. The aim of the seismic prospecting was to identify the sediments layering and the rock basement depth. The acquisition parameters were as follows: group in- terval 10 m; shot interval 5 m; geophone frequency 14 Hz; sample rate 1 ms; record length 2 s, energy source hydrapulse. The cable, with 120 channels, remained dur- ing all the experiment allowing reflection/refraction events acquisition. The data were processed by a standard procedure using PROMAX and SUNT5 processing codes. The statics were calculated starting from the refracted first arrivals using a two layer inversion based on least square optimisation. Standard seismic reflection processing was applied to obtain reflection images and it was integrated with seismic refraction data inversion. Seismic profiles allow to reconstruct both the main reflectors in the recent deposits and the geometry of the bedrock. The first results document a complex history in the drainage patterns of the Clusone basin, allowing to identify, in an intra- mountain basin, drainage directions that in some cases are different from the ones that can be observed today. The integration of well data and seismic profiles in this study of an intra-mountain basin allows on one side the identification of the bedrock geome- tries and, on the other, gives constrains for the reconstruction of the geomorphologic evolution of a sector of a mountain chain.

  1. Seismometer deployment campaign and observations on the tectonics of the Southern Vienna basin fault system.

    Science.gov (United States)

    Le Bras, Ronan; Bianchi, Irene; Piana Agostinetti, Nicola; Bokelmann, Götz

    2014-05-01

    Two moderate size earthquakes (both M=4.2) shook the Vienna basin in September-October 2013. Immediately following the second earthquake on October 2, the Institute of Meteorology and Geophysics in Vienna (IMGW) deployed a three station local network located within a few kilometers of the fault zone with the aim to monitor the aftershocks and better understand the tectonics of the Vienna basin. We present the results of this data collection exercise and show some interesting observations at station SOP, located in Sopron, Hungary. The station is located close to the nodal plane for earthquakes on the Southern Vienna Basin fault system fault and data for the largest aftershocks in October 1-2 show a pattern indicating a progression of the rupture from the South-West to the North-East which can best be explained by rupture along the direction of the main fault.

  2. Geothermal field and thermotectonic evolution in Southern South Yellow Sea Basin

    Institute of Scientific and Technical Information of China (English)

    YANG Shuchun; HU Shengbiao; CAI Dongsheng; FENG Xiaojie; GAO Le; LU Jingmei

    2003-01-01

    Based on the available borehole temperature data and measurements of thermal conductivities on 10 core samples in the Southern South Yellow Sea Basin, 8 heat flow values are obtained. The results show that the mean values of temperature gradient and heat flow are 28.6℃/km and 69 mW/m2, respectively. The thermal history reconstruction from the inversion of vitrinite reflectance data, using the temperature-gradient method, indicates that the highest paleo-heat flow occurred at the end of the Mesozoic, and then the basin began to cool to present day. Tectonic subsidence analysis shows that the basin experienced at least four episodes of quick subsidence since the late Paleozoic and that the tectonic evolution was quite strong and complex.

  3. The Mississippian Pedroches Basin: A failed attempt to propagate a Palaeotethys Arm across Southern Iberia?

    Science.gov (United States)

    Armendáriz, Maider; Quesada, Cecilio; Rosales, Idoia

    2013-04-01

    The Pedroches basin, straddling the boundary between the Ossa Morena (OMZ) and the Central Iberian (CIZ) zones of the Iberian Massif, forms one of the largest exposures of Mississippian rocks in the Iberian Peninsula. With the only exception of transitional facies near the northern and southern margins, the basin fill mostly consists of volcanic and sedimentary rocks deposited in relatively shallow continental shelf environments, in which storm activity was the main process of sediment supply and dispersal. Significantly, the Pedroches basin is split into several compartments (structural units), among which three syn-sedimentary, sigmoidal shape igneous belts, produced the most severe facies, structural and palaeogeographic changes. Owing to its timing of formation during the period of Variscan convergence, its location within an area undergoing active Variscan deformation, and the fact that the basin fill was itself affected by the Variscan orogeny, the Pedroches basin was considered a typical example of a syn-orogenic, peripheral foreland basin. Recent stratigraphical, sedimentological and isotope geology work has allowed a reinterpretation of the basin fill, in which two different sequences may be distinguished, with distinct tectono-stratigraphic significance. Above a basal conglomerate, the several hectometres thick lower part of the basin fill succession shows the highest variability among the various structural units in terms of lithology, facies and thickness. Most volcanic rocks are located within this lower part, within and in between the igneous belts, suggesting the important role of lithosphere-through, extension-related faulting in the origin of the basin. Significant across-strike thickness changes attest for syn-sedimentary horst and graben formation at this stage. On the contrary, the upper part of the basin fill is very similar in all units and corresponds to flyschoid greywacke-mudstone alternations (Culm facies). The change between the lower and

  4. Geology, Water, and Wind in the Lower Helmand Basin, Southern Afghanistan

    Science.gov (United States)

    Whitney, John W.

    2006-01-01

    This report presents an overview of the geology, hydrology, and climate of the lower Helmand Basin, a large, closed, arid basin in southern Afghanistan. The basin is drained by the Helmand River, the only perennial desert stream between the Indus and Tigris-Euphrates Rivers. The Helmand River is the lifeblood of southern Afghanistan and has supported desert civilizations in the Sistan depression for over 6,000 years. The Helmand Basin is a structurally closed basin that began to form during the middle Tertiary as a consequence of the collision of several Gondwanaland fragments. Aeromagnetic studies indicate the basin is 3-5 kilometers deep over basement rocks. Continued subsidence along basin-bounding faults in Iran and Pakistan throughout the Neogene has formed the Sistan depression in the southwest corner of the basin. Lacustrine, eolian, and fluvial deposits are commonly exposed in the basin and were intruded by latest Miocene-middle Quaternary volcanoes, which indicates that depositional environments in the lower Helmand Basin have not substantially changed for nearly 10 million years. Lakes expanded in the Sistan depression during the Quaternary; however, the size and extent of these pluvial lakes are unknown. Climate conditions in the lower Helmand Basin likely mirrored climate changes in the Rajasthan Desert to the east and in Middle Eastern deserts to the west: greater aridity during global episodes of colder temperatures and increased available moisture during episodes of warmer temperatures. Eolian processes are unusually dominant in shaping the landscape in the basin. A strong wind blows for 120 days each summer, scouring dry lakebeds and creating dune fields from annual flood deposits. Nearly one-third of the basin is mantled with active or stabilized dunes. Blowing winds combined with summer temperatures over 50? Celsius and voluminous insect populations hatched from the deltaic wetlands create an environment referred to as the 'most odious place on

  5. A new species of Trachytherus (Notoungulata: Mesotheriidae) from the late Oligocene (Deseadan) of Southern Peru and the middle latitude diversification of early diverging mesotheriids.

    Science.gov (United States)

    Shockey, Bruce J; Billet, Guillaume; Salas-Gismondi, Rodolfo

    2016-05-18

    Herein we describe a new species of early diverging mesotheriid notoungulate from the late Oligocene of Moquegua, Peru. This taxon, Trachytherus ramirezi sp. nov., is distinctive in terms of a few characteristics that appear plesiomorphic as compared to those of other described mesotheriids, even other species referred to Trachytherus. Such plesiomorphic traits include the absence of an upper diastema and a lack of heart-shaped incisive foramina, traits that are generally present in other mesotheriids. Our phylogenetic analysis of described early divergent mesotheriids indicates that T. ramirezi was the earliest to diverge. This analysis also confirms the paraphyletic nature of the "genus" Trachytherus.          Geographically, T. ramirezi clusters among T. alloxus, T. subandinus, and T. spegazzinianus, all of which are known from a discrete region in the middle latitudes of western South America that we refer to as the Bolivian Orocline Region (BOR). Our palaeobiogeographic reconstruction using maximum parsimony identifies the BOR as a possible ancestral area for the Mesotheriidae and as an important region for their diversification. For the more exclusive Mesotheriinae, the BOR was reconstructed as the ancestral area, an area from which some mesotheriines would have later dispersed to southern South America. Uncertainty concerning the ancestral area, for the Mesotheriidae-which could be BOR or southern South America area (or both)-is possibly due to the ignorance of the phylogenetic affinities for the undescribed mesotheriid remains reported from Tinguirirican localities. The present description of T. ramirezi therefore adds to the high taxonomic diversity of early mesotheriid species in the relatively small area of the BOR and emphasizes the likely role played by this topographically dynamic area on mesotheriid evolution during a significant time in the history of the clade.

  6. Evidences for a Paleocene marine incursion in southern Amazonia (Madre de Dios Sub-Andean Zone, Peru)

    NARCIS (Netherlands)

    Louterbach, M.; Roddaz, M.; Bailleul, J.; Antoine, P.O.; Adnet, S.; Kim, J.H.; van Soelen, E.E.; Parra, F.; Gérard, J.; Calderon, Y.; Gagnaison, C.; Sinninghe Damsté, J.S.; Baby, P.

    2014-01-01

    This article presents new biostratigraphic dating, facies analysis, organic geochemical data and Nd–Sr isotopic provenance from five outcrops of southern Amazonia (MD-85, MD-177 MD-184, MD-255 and MD-256) to document for the first time the presence of a shallow marine ingression in the Paleocene of

  7. Submarine landslides in the Southern Adriatic basin: good candidates for potential paleoseismic analysis.

    Science.gov (United States)

    Dalla Valle, Giacomo; Trincardi, Fabio; Foglini, Federica; Campiani, Elisabetta; Pellegrini, Claudio

    2016-04-01

    The Plio-Pleistocene sedimentary succession of the western continental margin that surround the Southern Adriatic basin mainly consists of contourite depositional systems. The architectural stacking pattern of the contourites-linked bodies is sometimes interrupted by the presence of large-scale mass-transport complexes (MTCs). MTCs are spatially diffused along the margin and are characterized by high variability in size, morphology and geometries. In the northern sector of the margin MTCs derive from the remobilisation of upper-slope contourite drifts, whereas in the southern sector of the margin sedimentary instability involves shelf-margin, progradational deposits. The most prominent MTC of the northern sector of the margin is the Gondola Slide (GS) a large, deep-seated MTC composed of at least three distinct MTDs involving up to 40km3 of sediments. The events that have generated these MTDs have been enclosed within a robust chronological framework using sedimentary shallow piston-cores collected along the continental slope. The reconstruction of the age of these MTDs indicates that failures have repeatedly occurred along the margin during at least the last 55,000 years. Therefore, the GS case indicates that sediment instability processes can span a large portion of a sea-level cycle, pointing to triggering mechanisms that are independent from variations in the relative sea level position. The repeated GS failure events are therefore interpreted to be mainly triggered by earthquake shocks. The Southern Adriatic basin represents a seismically active area and earthquakes are generally cluster along long-lived shear zones. One of these zones, the Gondola Zone, which run across the shelf and the slope, close to the GS-MTC, has been site of paleoseismology analysis, indicating recent (younger than 5.5 kyr) tectonic deformation through E-W strike-slip faulting . Basin-scale MTDs characterize also the southern sector of the continental margin. MTDs are present both

  8. Basin Evolution of the Cretaceous-Early Eocene Xigaze Forearc, Southern Tibet

    Science.gov (United States)

    Orme, D. A.; Carrapa, B.; Kapp, P. A.; Gehrels, G. E.; Reiners, P. W.

    2013-12-01

    An understanding of the processes which control the evolution of forearc basins is important for deciphering the tectonic development of a convergent margin prior to continent-continent suturing. This study presents sedimentologic, modal petrographic and geo-thermochronologic data from the Xigaze forearc basin, preserved along ~ 600 km of the Indus-Yarlung Suture Zone in southern Tibet. From late Cretaceous to early Cenozoic time, subduction of Neo-Tethyan oceanic crust beneath the southern margin of Asia accommodated the northward motion of the Indian craton and formed the Xigaze forearc basin. Following collision with India in the early Cenozoic, the basin transitioned from predominantly marine to non-marine sedimentation and was subsequently uplifted to a mean elevation of 5000 m. Thus, the sedimentary record in the Xigaze forearc preserves information regarding the tectonic evolution of the Indo-Asia continental margin prior to and following collision. We present new measured sections and geo-thermochronologic data from Early Cretaceous to Early Eocene clastic and carbonate sedimentary rocks, preserved in two previously unexplored regions of the forearc, (1) at its western most extent, northwest of Saga, and (2) north of Lhatse. In turn, we compare our results with previously published data in order to synthesize our current understanding of forearc evolution. Strata preserved in the Lhaste region record an initial shallow marine phase of forearc sedimentation (Aptian), but quickly transition to deep marine slope and distal fan turbidite facies (Albian-Campanian). In contrast, facies preserved in the Saga region record a younger shoaling upward marine sequence (Maastrichtian-Ypresian), with the uppermost ~ 400 m consisting of fluvial channel sandstones and red-green paleosols. Facies and depositional environments in the Saga region are highly variable along strike, with turbidites, shelf limestones, estuarine siliciclastics and thick paleosols sequences all

  9. The role of Argopecten purpuratus shells structuring the soft bottom community in shallow waters of southern Peru

    Science.gov (United States)

    Lomovasky, Betina J.; Gamero, Patricia A.; Romero, Leonardo; Firstater, Fausto N.; Gamarra Salazar, Alex; Hidalgo, Fernando; Tarazona, Juan; Iribarne, Oscar O.

    2015-12-01

    Accumulation of Argopecten purpuratus shells often occurs after El Niño events in shallow waters of Independencia Bay (14°17‧S-76°10‧W; Pisco, Peru). Here we experimentally investigate the effects of their shell accumulation on macrobenthos assemblages in soft bottom, shallow areas of the bay. A field experiment (from May 2006 to May 2007), including four treatments with different coverage levels of empty shells of A. purpuratus, were randomly arranged in: (1) areas devoid of shells ("Empty" treatment: experimental control), (2) 50% of the plot area covered with shells haphazardly distributed over the bottom ("medium" treatment), (3) 100% of the plot area covered with shells, forming a 10 cm valve layer ("full" treatment) and (4) "natural control". We found a total of 124 taxa throughout the experiment. Polychaetes, crustaceans and mollusks were the most abundant groups in "natural controls", dominated by the gastropod Nassarius gayi and the polychaetes Prionospio peruana, Platynereis bicanaliculata and Mediomastus branchiferus. The abundance of individuals (N) and the species richness (S) were higher in the "medium" treatment, but only in one month under positive sea bottom thermal anomalies. Similarity analysis (Bray-Curtis) showed that "natural control", "empty" and "full" treatments were more similar among them than the "medium" treatment. Multidimensional analysis showed no clear species association among treatments and a higher grouping among the samplings of Jun-06, Aug-06 and Nov-06. Our results also showed that the commercial crab Romaleon polyodon and the polyplacophora Tonicia elegans were positively affected by shell accumulations ("medium" treatment), while the limpet Fissurella crassa was negatively affected. Our study shows that directly by changing habitat structure or indirectly by changing sediment characteristics, the addition of scallop shells to the soft bottom can modify the macrobenthic assemblage; however, the seasonal oceanographic

  10. Seismic Structural Setting of Western Farallon Basin, Southern Gulf of California, Mexico.

    Science.gov (United States)

    Pinero-Lajas, D.; Gonzalez-Fernandez, A.; Lopez-Martinez, M.; Lonsdale, P.

    2007-05-01

    Data from a number of high resolution 2D multichannel seismic (MCS) lines were used to investigate the structure and stratigraphy of the western Farallon basin in the southern Gulf of California. A Generator-Injector air gun provided a clean seismic source shooting each 12 s at a velocity of 6 kts. Each signal was recorded during 6- 8 s, at a sampling interval of 1 ms, by a 600 m long digital streamer with 48 channels and a spacing of 12.5 m. The MCS system was installed aboard CICESE's (Centro de Investigacion Cientifica y de Educacion Superior de Ensenada) 28 m research vessel Francisco de Ulloa. MCS data were conventionally processed, to obtain post- stack time-migrated seismic sections. The MCS seismic sections show a very detailed image of the sub-bottom structure up to 2-3 s two-way travel time (aprox. 2 km). We present detailed images of faulting based on the high resolution and quality of these data. Our results show distributed faulting with many active and inactive faults. Our study also constrains the depth to basement near the southern Baja California eastern coast. The acoustic basement appears as a continuous feature in the western part of the study area and can be correlated with some granite outcrops located in the southern Gulf of California islands. To the East, near the center of the Farallon basin, the acoustic basement changes, it is more discontinuous, and the seismic sections show a number of diffracted waves.

  11. Clustering and interpretation of local earthquake tomography models in the southern Dead Sea basin

    Science.gov (United States)

    Bauer, Klaus; Braeuer, Benjamin

    2016-04-01

    The Dead Sea transform (DST) marks the boundary between the Arabian and the African plates. Ongoing left-lateral relative plate motion and strike-slip deformation started in the Early Miocene (20 MA) and produced a total shift of 107 km until presence. The Dead Sea basin (DSB) located in the central part of the DST is one of the largest pull-apart basins in the world. It was formed from step-over of different fault strands at a major segment boundary of the transform fault system. The basin development was accompanied by deposition of clastics and evaporites and subsequent salt diapirism. Ongoing deformation within the basin and activity of the boundary faults are indicated by increased seismicity. The internal architecture of the DSB and the crustal structure around the DST were subject of several large scientific projects carried out since 2000. Here we report on a local earthquake tomography study from the southern DSB. In 2006-2008, a dense seismic network consisting of 65 stations was operated for 18 months in the southern part of the DSB and surrounding regions. Altogether 530 well-constrained seismic events with 13,970 P- and 12,760 S-wave arrival times were used for a travel time inversion for Vp, Vp/Vs velocity structure and seismicity distribution. The work flow included 1D inversion, 2.5D and 3D tomography, and resolution analysis. We demonstrate a possible strategy how several tomographic models such as Vp, Vs and Vp/Vs can be integrated for a combined lithological interpretation. We analyzed the tomographic models derived by 2.5D inversion using neural network clustering techniques. The method allows us to identify major lithologies by their petrophysical signatures. Remapping the clusters into the subsurface reveals the distribution of basin sediments, prebasin sedimentary rocks, and crystalline basement. The DSB shows an asymmetric structure with thickness variation from 5 km in the west to 13 km in the east. Most importantly, a well-defined body

  12. 3D Fault Geometry and Basin Evolution in the Northern Continental Borderland Offshore Southern California

    Science.gov (United States)

    Schindler, C. S.; Nicholson, C.; Sorlien, C.

    2007-12-01

    Grids of recently released high-quality industry multichannel seismic (MCS) reflection data, combined with bathymetry and offshore well data are used to map digital 3D fault surfaces and stratigraphic reference horizons in the northern Continental Borderland offshore of southern California. This area experienced large-scale oblique crustal extension and translation associated with the initiation and development of the Pacific-North American plate boundary. The 3D surfaces of structure and stratigraphy can thus be used to better understand and evaluate regional patterns of uplift, subsidence, fault interaction and other aspects of plate boundary deformation. Our mapping in Santa Cruz basin and on Santa Rosa and Santa Cruz-Catalina Ridge reveals an unusual pattern of faulting, folding and basin subsidence. This subsidence is significant (up to 3-4 km since early-Miocene time) and is responsible for the development of several major Borderland basins. Vertical motions can be estimated from an early-Miocene unconformity that likely represents a paleo-horizontal, near-paleo-sea-level erosional surface. As such, it can be used to reconstruct Borderland forearc geometry prior to rifting, subsidence and subsequent basin inversion. Major findings to date include: (a) a better characterization of the complex 3D geometry and pinch-out of the eastern edge of the northern forearc Nicolas terrane and its implications for Borderland basin development, plate reconstructions, and vertical motions associated with oblique rifting; (b) recognition that the East Santa Cruz Basin fault, previously thought to be a predominantly high-angle, large- displacement right-slip fault representing the eastern edge of the Nicolas terrane, is in fact a series of reactivated right-stepping, NE-dipping reverse-separation faults; (c) discovery that NW-striking faults associated with Santa Cruz-Catalina Ridge bend west into a horse-tail structure to interact with and contribute to the southern frontal

  13. Hydrological drought forecasting and skill assessment for the Limpopo river basin, Southern Africa

    Directory of Open Access Journals (Sweden)

    P. Trambauer

    2014-08-01

    Full Text Available Ensemble hydrological predictions are normally obtained by forcing hydrological models with ensembles of atmospheric forecasts produced by Numerical weather prediction models. To be of practical value to water users, such forecasts should not only be sufficiently skilful, they should also provide information that is relevant to the decisions end users make. The semi-arid Limpopo basin in Southern Africa has experienced severe droughts in the past, resulting in crop failures, high economic losses and the need for humanitarian aid. In this paper we address the seasonal prediction of hydrological drought for the Limpopo river basin by testing three proposed forecasting systems (FS that can provide operational guidance to dam operators and water managers within the basin at the seasonal time scale. All three FS include a distributed hydrological model of the basin, and are forced with either (i a global atmospheric model forecast (ECMWF seasonal forecast system – S4, (ii the commonly applied Ensemble Streamflow Prediction approach (ESP using resampled historical data, or (iii a conditional ESP approach (ESPcond, which is conditional on the ENSO signal. We determine the skill of the three systems in predicting drought indices and streamflow. We also assess the skill of the model in predicting indicators that are meaningful to the local end users in the basin. FS_S4 shows moderate skill for all lead times (3, 4, and 5 months and aggregation periods. FS_ESP also performs better than climatology for the shorter lead times, but with a lower skill than FS_S4. FS_ESPcond shows skill in between the other two FS, though its skill is shown to be more robust. The skills of FS_ESP and FS_ESPcond reduce rapidly with increasing lead time. Both FS_S4 and FS_ESPcond show good potential for seasonal hydrological drought forecasting in the Limpopo river basin, which is encouraging in the context of providing better operational guidance to water users.

  14. Aliphatic hydrocarbons in sediment cores from the southern basin of Lake Michigan

    Energy Technology Data Exchange (ETDEWEB)

    Doskey, P.V. [Argonne National Lab., IL (United States). Environmental Research Division; Andren, A.W. [Univ. of Wisconsin, Madison, WI (United States). Water Chemistry Program

    1991-10-01

    Aliphatic hydrocarbons in sediments of the southern basin of Lake Michigan have planktonic, terrigenous, and petroleum residue origins. Surficial sediments collected near the eastern shore in 60-80 m of water contained more petroleum residue and planktonic hydrocarbons and exhibited less terrigenous character than sediments collected from the deepest location in the basin. Petroleum residue inputs have increased since 1900 as evidenced by a change in the flux of an unresolved complex mixture (UCM) of hydrocarbons from 6 ng/cm{sup 2}{center_dot}yr to a flux of approximately 100 ng/cm{sup 2}{center_dot}yr in 1980. Sediment profiles of the UCM exhibited subsurface concentration maxima that may be due to reduced inputs of combustion products or feeding by oligochaetes. Profiles of n-C{sub l7} and pristane indicated that planktonic n-alkanes undergo degradation in the aerobic, mixed zone of the sediments.

  15. Multi-Layer Superposed Coalbed Methane System in Southern Qinshui Basin, Shanxi Province, China

    Institute of Scientific and Technical Information of China (English)

    Zheng Zhang; Yong Qin; Xuehai Fu; Zhaobiao Yang; Chen Guo

    2015-01-01

    Multi-coalbed developed in Carboniferous–Permian coal-bearing strata of southern Qinshui Basin, and different coal-bearing segments have different coalbed methane (CBM) reservoiring characteristics. Analysis of previous studies suggests that the essence of an unattached CBM system is to possess a unified fluid pressure system, which includes four key elements, namely, gas-bearing coal-rock mass, formation fluid, independent hydrodynamic system and capping layer condition. Based on the exploration and exploitation data of CBM, it is discovered that the gas content of coal seams in southern Qinshui Basin presents a change rule of non-monotonic function with the seam dipping, and a turning point of the change appears nearby coal seam No. 9, and coal seams of the upper and the lower belong to different CBM systems respectively; well test reservoir pressure shows that the gradient of coal seam No. 15 of the Taiyuan Formation is significantly higher than that of coal seam No. 3 of the Shanxi Formation; the equivalent reservoir pressure gradient of coal seam No. 15 “jumps” obviously compared with the reservoir pressure gradient of coal seam No. 3 in the same vertical well, that is, the relation between reservoir pressure and burial depth takes on a characteristic of nonlinearity; mean-while, the vertical hydraulic connection among the aquifers of Shanxi Formation and Taiyuan Forma-tion is weak, constituting several relatively independent fluid pressure systems. The characteristics dis-cussed above reveal that the main coal seams of southern Qinshui Basin respectively belong to relatively independent CBM systems, the formation of which are jointly controlled by sedimentary, hydrogeolog-ical and structural conditions.

  16. TRANSGRESSIVE SEQUENCES ON FORELAND MARGINS: A CASE STUDY OF THE NEOGENE CENTRAL GUADALQUIVIR BASIN, SOUTHERN SPAIN

    Directory of Open Access Journals (Sweden)

    J. GABRIEL PENDÓN

    2004-07-01

    Full Text Available The Guadalquivir foreland basin, located between the Iberian basement northward and the Betic orogen to the South, represents the western sector of the earlier foredeep basin of the Betic Cordillera. Along the northern foreland margin, the sedimentary fill of this basin includes a Tortonian Basal Transgressive Complex (BTC, composed of five internal sequences bounded by transgressive surfaces. Two main parts are distinguished within each sequence: the lower transgressive lag deposits, and the upper stillstand/prograding sediments. Three facies associations were distinguished within this stratigraphic succession along the central sector of this basin margin: unfossiliferous conglomerates and coarse-grained sands (A, fossiliferous conglomerates and coarse-grained sands (B, and yellow medium-coarse-grained fossiliferous sands (C. A fourth facies association (D: blue silty marlstones and shales overlies the BTC. Deposits of alluvial sediments (facies association A and shallow-marine/foreshore sediments (facies association C, were recurrently interrupted by transgressive pulses (facies associations B and C. Every pulse is recorded by an erosional, cemented sandy-conglomerate bar with bivalves (Ostreidae, Isognomon, balanids, gastropods and other marine bioclasts; or their transgressive equivalents. The lateral facies changes in each individual sequence of the BTC are related to: (1 the influence on the northern foreland margin of the tectonic activity of the southern orogenic margin; (2 the palaeorelief formed by irregularities of the substrate which controls the sediment dispersal; and (3 the evolution stages of the sedimentary systems. 

  17. Tephrochronological study in the quaternary Val d'Agri intermontane basin (Southern Apennines, Italy)

    Science.gov (United States)

    Zembo, Irene; Vignola, Pietro; Andò, Sergio; Bersezio, Riccardo; Vezzoli, Luigina

    2011-01-01

    In the south-eastern depocentre of the Val d'Agri basin (Southern Apennines), a volcanic ash layer crops out interbedded within poorly structured alluvial fan deposits of Late Pleistocene age. Textural, depositional and pedological features of this weathered layer suggest a primary deposition from a pyroclastic fall-out of volcanic ash. Chemical analyses of feldspars show an alkali trachytic composition and accessory minerals association allow to correlate this tephra layer with the regionally dispersed Y-7 marine tephra layer (Tufo Verde Epomeo eruption, Ischia volcano), dated at 56 ± 4 ka. The Val d'Agri tephra here described for the first time was deposited during MIS Stage 3. Its recovery and characterization permit to contribute to regional correlation of the Mediterranean climatic and volcanic events from marine to continental successions and to describe landscape evolution of the Southern Apennines during glacial-interglacial cycles.

  18. CLIMATE CHANGE IN NORTHERN AFRICA: TOWARDS A RETURN OF RAINFALL ON THE SOUTHERN MEDITERRANEAN BASIN

    Directory of Open Access Journals (Sweden)

    NOUACEUR ZEINEDDINE

    2014-03-01

    Full Text Available To determine to what extent climate change affects the rainfall recorded on the southern Mediterranean basin, a trend analysis is proposed. This study is based on the chronological graphic method of processing information (MGCTI of type "Matrice Bertin". Results show an extreme variability of the precipitations and a severe drought, especially for Morocco, observed since 1970s. Finally, a gradual return to humid conditions is observed from the beginning of the 2000s in Algeria and Tunisia and since 2008 in Morocco. This new trend is also confirmed by recent results provided by agricultural data of 2011/2012 and 2012/2013.

  19. Contribution to the diversity and conservation knowledge of mammals in the basin of the Apurimac river, Peru

    Directory of Open Access Journals (Sweden)

    Víctor Pacheco

    2013-04-01

    Full Text Available The present work documents the diversity of mammals in the headwaters of the Apurímac river, one of the most important information gaps in Peru, based on an evaluation of fi ve sampling areas in the departments of Apurímac (Cconoc, Velavelayoc, Ayacucho (Yanamonte, Ccentabamba and Cuzco (Catarata. Capture’s effort was 1280 trap-nights and 41 mistnet-nights. Sixty species were recorded in the study area and included 15 threatened species and four species endemic to Perú. As expected, bats and rodents were the most diverse orders (66,7 %. The species diversity in the sites sampled declines signifi cantly with elevation from the lowest elevation sites (Ccentabamba and Catarata to the highest (Velavelayoc. The marsupial Monodelphis peruviana and the Dwarf Brocket deer Mazama chunyi are fifi rst records for the department of Ayacucho. The bats Artibeus planirostris and Myotis keaysi, and the river otter Lontra longicaudis are fifi rst records for the department of Apurímac. For bats, the relative abundance showed a signifi cant negative correlation with elevation, but was not signifi cant for small terrestrial mammals. The species of Sturnira, Akodon and Thomasomys had the highest values of relative abundance. The diversity indices (Shannon-Wiener and Simpson also showed also a signifi cant negative correlation with elevation. The Apurímac river headwater is estimated to have at least 97 mammals species. We recommend creating conservation areas in Huanipaca, Yanamonte and Catarata, and enlarging the area of the Santuario Histórico Machu Picchu to include the archaeological site of Choquequirao.

  20. Spatial and temporal evolution of Liassic to Paleocene arc activity in southern Peru unraveled by zircon U-Pb and Hf in-situ data on plutonic rocks

    Science.gov (United States)

    Demouy, Sophie; Paquette, Jean-Louis; de Saint Blanquat, Michel; Benoit, Mathieu; Belousova, Elena A.; O'Reilly, Suzanne Y.; García, Fredy; Tejada, Luis C.; Gallegos, Ricardo; Sempere, Thierry

    2012-12-01

    Cordilleran-type batholiths are built by prolonged arc activity along active continental margins and provide detailed magmatic records of the subduction system evolution. They complement the stratigraphic record from the associated forearcs and backarcs. We performed in-situ U-Pb geochronology and Hf isotope measurements on zircon grains from a large set of plutonic rocks from the Coastal Batholith in southern Peru. This batholith emplaced into the Precambrian basement and the Mesozoic sedimentary cover. We identify two major periods of voluminous arc activity, during the Jurassic (200-175 Ma) and the Late Cretaceous-Paleocene (90-60 Ma). Jurassic arc magmatism mainly resulted in the emplacement of a dominantly mafic suite with ɛHf values ranging from - 9.5 to + 0.1. Published ages south of the Arequipa area suggest that the arc migrated southwestward out of the study area during the Middle Jurassic. After a magmatic gap of 85 Ma, arc activity abruptly resumed 90 Ma ago in Arequipa. Intrusive bodies emplaced into both basement and older Jurassic intrusions and strata. This activity culminated between 70 and 60 Ma with the emplacement of very large volumes of dominantly quartz-dioritic magmas. This last episode may be considered as a flare-up event, characterized by intense magmatic transfers into the crust and rapid relief creation. The Late Cretaceous-Paleocene initial ɛHf are shifted toward positive values (up to + 3.3 and + 2.6) compared to the Jurassic ones, indicating either a larger input of juvenile magmas, a lesser interaction with the ancient crust, or an increase of re-melting of young mantle-derived mafic lower crust. These magmatic fluxes with juvenile component are coeval with the onset of the crustal thickening at 90 Ma and represent a significant contribution to the formation of the continental crust in this area.

  1. Traveling Weather Disturbances in Mars' Southern Extratropics: Sway of the Great Impact Basins

    Science.gov (United States)

    Hollingsworth, Jeffery L.

    2016-04-01

    ' transient barotropic/baroclinic eddies are significantly influenced by the great impact basins of this hemisphere (e.g., Argyre and Hellas). In addition, the occurrence of a southern storm zone in late winter and early spring is keyed particularly to the western hemisphere via orographic influences arising from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate fundamental differences amongst such simulations and these are described.

  2. Stratigraphic correlations of the Vaca Muerta formation in the southern Neuquén basin, Argentina

    Science.gov (United States)

    Nesma, Krim; Patrice, Imbert; Cedric, Bonnel; Charles, Aubourg

    2013-04-01

    The petroleum Neuquén basin, south west Argentina, contains a continuous late Triassic to Cenozoic succession including continental and marine sediments, deposited under a variety of tectonic regimes. The Vaca Muerta formation is one of the major source rocks of the Neuquén basin and was deposited during the Andic cycle. This formation consists of organic-rich dark brown to black shales and mudstones deposited during a major transgression, in euxinic conditions on a shelf and slope during the Tithonian. Over most of the basin, the Vaca Muerta formation overlies the continental deposits of the Tordillo formation. The contact between the two formations is isochronous throughout the basin and marks the Tithonian transgression (Leanza, 1981). After this transgression, prograding bodies were deposited and the Vaca Muerta corresponds to the distal part of this latest. It includes stages from Middle Tithonian in the south to Valanginian in the north (Leanza & Hugo, 1977). The Vaca Muerta formation is well exposed in the southern part of the Neuquén basin, from the Picun Leufu Anticline to the north of the town of Las Lajas. It corresponds in these two areas to a succession of dark to brown shales and carbonate beds. In details, we can divide it into two parts: the Lower Vaca Muerta and the Upper Vaca Muerta. Above, the Picun Leufu formation overlies the Vaca Muerta formation and consists of carbonaceous and siliciclastics prograditional bodies. This unit is absent in the "North Zapala Zone" and its lateral equivalent is less carbonaceous. In this poster; we propose eight detailed sedimentological logs, which are correlated along 120 km north-south trend (from the Picun Leufu Anticline to the south west to the Agrio thrust Belt (ATB) to the north). This correlation will be used to assess the vertical and lateral variability of the Vaca Muerta deposits and to define the palaeogeographic evolution of that region. This allowed us to identify two major prograding sequences

  3. A numerical method for determining the state of stress using focal mechanisms of earthquake populations: application to Tibetan teleseisms and microseismicity of Southern Peru

    Science.gov (United States)

    Carey-Gailhardis, Evelyne; Louis Mercier, Jacques

    1987-03-01

    give a good evaluation of the regional (mean) state of stress. Focal mechanisms of the small events are also modelled by a mean stress deviator, but this differs significantly from the regional state of stress in southern Peru deduced from Quaternary faulting. This may be due to imprecise location of the small events. However, some movements are strongly different from those predicted by the computed mean stress deviator. This suggests that small fault kinematics surely depend on the regional state of stress but that local effects may control the small deformations.

  4. Reservoir Potential of Silurian Carbonate Mud Mounds in the Southern Sichuan Basin, Central China

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wenzhi; YANG Xiaoping; Steve KERSHAW; ZHANG Baomin

    2006-01-01

    Lower Silurian mud mounds of the Shinuilan Formation, located in the southern Sichuan Basin, China, have developed in open shelf settings in deeper water than shallow-water reef-bearing limestones that occur in the region. An integration of the outcrop, drill data and seismic profiles show that contemporaneous faults have controlled the boundary and distribution of the sedimentary facies of Lower Silurian rocks in the southern Sichuan Basin. Mounds appear to have developed in the topographic lows formed by synsedimentary faulting, on the shelf of the Yangtze Platform. Average mound thickness is 20 m, maximum 35 m. Mounds are composed mainly of micrite, possibly microbially bound, and are overlain by shales. Mound tops are preferentially dolomitized, with the Mg2+ source probably from the clay content of the mound-top carbonate. Microfacies analysis and reconstruction of the diagenetic history reveal that the mound tops have higher porosity, and are gas targets; in contrast, mound cores and limbs show pores filled by three generations of calcite cement, and therefore have a low gas potential.

  5. Laramide structure of the central Sangre de Cristo Mountains and adjacent Raton Basin, southern Colorado

    Science.gov (United States)

    Lindsey, D.A.

    1998-01-01

    erosion of a highland is the appearance of abundant feldspar in the Late Cretaceous Vermejo Formation. Above the Vermejo, unconformities overlain by conglomerate indicate continued thrusting and erosion of highlands from late Cretaceous (Raton) through Eocene (Cuchara) time. Eocene alluvial-fan conglomerates in the Cuchara Formation may represent erosion of the Culebra thrust block. Deposition in the Raton Basin probably shifted north from New Mexico to southern Colorado from Paleocene to Eocene time as movement on individual thrusts depressed adjacent segments of the basin.

  6. Hydrological drought forecasting and skill assessment for the Limpopo River basin, southern Africa

    Science.gov (United States)

    Trambauer, P.; Werner, M.; Winsemius, H. C.; Maskey, S.; Dutra, E.; Uhlenbrook, S.

    2015-04-01

    Ensemble hydrological predictions are normally obtained by forcing hydrological models with ensembles of atmospheric forecasts produced by numerical weather prediction models. To be of practical value to water users, such forecasts should not only be sufficiently skilful, they should also provide information that is relevant to the decisions end users make. The semi-arid Limpopo Basin in southern Africa has experienced severe droughts in the past, resulting in crop failure, economic losses and the need for humanitarian aid. In this paper we address the seasonal prediction of hydrological drought in the Limpopo River basin by testing three proposed forecasting systems (FS) that can provide operational guidance to reservoir operators and water managers at the seasonal timescale. All three FS include a distributed hydrological model of the basin, which is forced with either (i) a global atmospheric model forecast (ECMWF seasonal forecast system - S4), (ii) the commonly applied ensemble streamflow prediction approach (ESP) using resampled historical data, or (iii) a conditional ESP approach (ESPcond) that is conditional on the ENSO (El Niño-Southern Oscillation) signal. We determine the skill of the three systems in predicting streamflow and commonly used drought indices. We also assess the skill in predicting indicators that are meaningful to local end users in the basin. FS_S4 shows moderate skill for all lead times (3, 4, and 5 months) and aggregation periods. FS_ESP also performs better than climatology for the shorter lead times, but with lower skill than FS_S4. FS_ESPcond shows intermediate skill compared to the other two FS, though its skill is shown to be more robust. The skill of FS_ESP and FS_ESPcond is found to decrease rapidly with increasing lead time when compared to FS_S4. The results show that both FS_S4 and FS_ESPcond have good potential for seasonal hydrological drought forecasting in the Limpopo River basin, which is encouraging in the context of

  7. Soil erosion vulnerability in the verde river basin, southern minas gerais

    Directory of Open Access Journals (Sweden)

    Vinícius Augusto de Oliveira

    2014-06-01

    Full Text Available Soil erosion is one of the most significant environmental degradation processes. Mapping and assessment of soil erosion vulnerability is an important tool for planning and management of the natural resources. The objective of the present study was to apply the Revised Universal Soil Loss Equation (RUSLE using GIS tools to the Verde River Basin (VRB, southern Minas Gerais, in order to assess soil erosion vulnerability. A annual rainfall erosivity map was derived from the geographical model adjusted for Southeastern Brazil, calculating an annual value for each pixel. The maps of soil erodibility (K, topographic factor (LS, and use and management of soils (C were developed from soils and their uses map and the digital elevation model (DEM developed for the basin. In a GIS environment, the layers of the factors were combined to create the soil erosion vulnerability map according to RUSLE. The results showed that, in general, the soils of the VRB present a very high vulnerability to water erosion, with 58.68% of soil losses classified as "High" and "Extremely High" classes. In the headwater region of VRB, the predominant classes were "Very High" and "Extremely High" where there is predominance of Cambisols associated with extensive pastures. Furthermore, the integration of RUSLE/GIS showed an efficient tool for spatial characterization of soil erosion vulnerability in this important basin of the Minas Gerais state.

  8. Crustal structure and tectonics from the Los Angeles basin to the Mojave Desert, southern California

    Science.gov (United States)

    Fuis, G. S.; Ryberg, T.; Godfrey, N. J.; Okaya, D. A.; Murphy, J. M.

    2001-01-01

    A seismic refraction and low-fold reflection survey, known as the Los Angeles Region Seismic Experiment (LARSE), was conducted along a transect (line 1) extending from Seal Beach, California, to the Mojave Desert, crossing the Los Angeles and San Gabriel Valley basins and San Gabriel Mountains. The chief result of this survey is an interpreted cross section that addresses a number of questions regarding the crustal structure and tectonics of southern California that have been debated for decades and have important implications for earthquake hazard assessment. The results (or constraints) are as follows. (1) The maximum depth of the Los Angeles basin along line 1 is 8 9 km. (2) The deep structure of the Sierra Madre fault zone in the northern San Gabriel Valley is as follows. The Duarte branch of the Sierra Madre fault zone forms a buried, 2.5-km-high, moderately north dipping buttress between the sedimentary and volcanic rocks of the San Gabriel Valley and the igneous and metamorphic rocks of the San Gabriel Mountains. (For deeper structure, see following.) (3) There are active crustal décollements in southern California. At middle-crustal depths, the Sierra Madre fault zone appears to sole into a master décollement that terminates northward at the San Andreas fault and projects southward beneath the San Gabriel Valley to the Puente Hills blind thrust fault. (4) The dip and depth extent of the San Andreas fault along line 1 dips steeply (˜83°) northward and extends to at least the Moho. (5) The subsurface lateral extent of the Pelona Schist in southern California is as follows. Along line 1, the Pelona Schist underlies much, if not all of the San Gabriel Mountains south of the San Andreas fault to middle-crustal depths. North of the San Andreas fault, it is apparently not present along the transect.

  9. Emerged quaternary marine terraces in southern Peru: Sea level changes and continental margin tectonics over the subducting Nazca Ridge

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, J.T.J.

    1988-01-01

    Because of the arid climate, mollusk shells in the marine cover strata are exceptionally well preserved and provide datable samples for a terrace and sea level chronology. Amino acid racemization was the most extensively used dating method, with three other numerical dating methods, electron spin resonance (ESR), Uranium-series, and radiocarbon ages used to calibrate the amino acid ages. D-alloisoleucine/L-isoleucine (A/I) ratios of >200 mollusks shells belong to six statistically and geomorphically defined aminozones. Aminozone IIa correlates with the last Interglacial (deep-sea oxygen isotope Stage 5e) based on 12 ESR ages and the similarity of the IIa ratios to those determined from calibrated last Interglacial sites on the Pacific Coast, U.S. Calibrated amino acid ages for the other aminozones are; I = >45,000 yr B.P. and {le} 87,000; IIb = 211,000 yr B.P.; III = 297,000 yr B.P.; IV = 496,000 yr B.P.; and V {ge} 945,000 yr B.P. The calibrated ages agree with ESR, Uranium series, and radioactive ages. The pattern of terrace deformation can be approximated by a simple geometric model in which the subconducting Nazca Ridge migrates obliquely southeastward as a rigid trapezoid beneath the forearc. The model correctly predicts a pattern of marine terrace deformation with the highest elevations located above the southern flank of the Nazca Ridge and subsidence above the northern flank. The topography, pattern of marine terrace deformation, and Quaternary rates of uplift of the Paracas Block are determined by oblique subduction of the aseismic Nazca Ridge.

  10. Organic geochemistry and petroleum geology, tectonics and basin analysis of southern Tarim and northern Qaidam basins, northwest China

    Science.gov (United States)

    Hanson, Andrew Dean

    Organic geochemistry of oils from the Tarim basin, NW China, distinguish at least seven genetic groups of oils. The largest group are derived from Middle-Upper Ordovician anoxic slope-facies marls coincident with the margins of structural uplifts. Other groups include non-marine derived oils in the Luntai uplift, from southwest Tarim, in the Kuqa depression, and west of the Bachu uplift. A seep sample from west of Kashi clusters with Luntai oils. These results suggest that numerous source-rock horizons occur, but they are really restricted. Organic geochemistry of oils from northern Qaidam defines a family of hypersaline, anoxic lacustrine derived oils. Cenozoic outcrop samples from northern Qaidam are too organic lean to be of source quality, but dark laminated upper Oligocene mudstones from the Shi 28 well are of fair to good quality. Biomarkers provide a good correlation between the oils and the core samples. Organic matter is from algae and bacteria and lacks terrestrial material. Hydrocarbons are contained in upper Oligocene, Miocene, and Pliocene reservoirs. Eight oils are from NW Qaidam, but one sample comes from NE Qaidam, an area previously believed to only produce oils derived from Jurassic source rocks. Thus an unidentified Cenozoic source rock occurs in NE Qaidam. Thermal modeling indicates generation occurred in northwestern Qaidam within the last 3 million years, agreeing with observed low maturity biomarker parameters. Cenozoic stratigraphy in northern Qaidam and southern Tarim basins record the tectonic history of the surrounding structural/topographic elements. Paleocurrents record flow away from adjacent ranges from the Miocene to the present. Provenance data tie sediments to adjacent structural elements. Petrography indicates increasingly immature sandstones in Miocene and younger sediments relative to pre-Miocene samples. Apatite fission-track results from southeastern Tarim yield a cooling age of 17 +/- 1 Ma indicative of unroofing since at

  11. Petroleum geology and exploration potential of Ucayali Basin, Peru%秘鲁Ucayali盆地油气地质特征及勘探潜力分析

    Institute of Scientific and Technical Information of China (English)

    王青; 王建君; 汪平; 朱志强; 赵旭

    2012-01-01

    The Ucayali Basin is one of the sub-Andean foreland basins with several types of pays. There are two sets of main source rocks including the Pucara Formation (T-J) and the Ene Formation ( P). Multiple sets of reservoirs generated, such as the Chonta, Vivian, Cushabatay, Agua Caliente and Raya Formations of Cretaceous and the Ene Formation of Permian. And the seal factors for the reservoirs are excellent. There are two types of thrust deformations in the Ucayali Basin. Basement-involved structures mainly occur in the north, while thin-skinned thrusting structures exist in the south. Traps of the discovered fields in the basin are mainly anticlines related to thrust faults. In the Northern Ucayali sub-Basin, hydrocarbons from the Pucara Formation move through unconformities and faults towards Cretaceous formations, and re-accumulate after the Quechua tectonic movement. However, in the Southern Ucayali sub-Basin, natural gas generate from the over mature shales of the Ene Formation, and migrate into the Permian and Cretaceous reservoirs. Four types of exploration leads exist in the basin; traps in thrustfold-foredeep belt, Carbonate reservoir in the Pucara Formation, gas prospects of Permian in the northern basin, and Cretaceous stratigraphic traps in the east of the basin.%秘鲁Ucayali盆地是位于安第斯山山前的前陆盆地之一,盆地内发育多套储盖组合.盆地内主力烃源岩包括上三叠统一下侏罗统Pucara组和二叠系Ene组的泥岩;发育多套储层,包括白垩系Chonta,Vivian,Cushabatay,AguaCaliente和Raya组储层,以及下二叠统的Ene组砂岩层等;盖层条件良好.北部主要发育基底相关的逆冲断层,而在盆地的南部发育薄皮式的逆冲断层,盆地内已发现的油气田的圈闭类型主要是与逆冲断层相关的断背斜圈闭.北Ucayali次盆Pucara组生成的油气运移至该组地层的剥蚀面,充注至白垩系,但遭到后期造山运动的破坏,通过再次运移聚集成藏.

  12. Chronological dating and tectonic implications of late Cenozoic volcanic rocks and lacustrine sequence in Oiyug Basin of southern Tibet

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Reconstruction of uplift history of the Tibetan Plateau is crucial for understanding its environmental impacts. The Oiyug Basin in southern Tibet contains multiple periods of sedimentary sequences and volcanic rocks that span much of the Cenozoic and has great potential for further studying this issue. However, these strata were poorly dated. This paper presents a chronological study of the 145 m thick and horizontally-distributed lacustrine sequence using paleomagnetic method as well as a K-Ar dating of the underlying volcanic rocks. Based on these dating results, a chronostratigraphic framework and the basin-developmental history have been established for the past 15 Ma, during which three tectonic stages are identified. The period of 15-8.1 Ma is characterized by intense volcanic activities involving at least three major eruptions. Subsequently, the basin came into a tectonically quiescent period and a lacustrine sedimentary sequence was developed. Around 2.5 Ma, an N-S fault occurred across the southern margin of the basin, leading to the disappearance of the lake environment and the development of the Oiyug River. The Gyirong basin on northern slope of the Himalayas shows a similar basin developmental history and thus there is a good agreement in tectonic activities between the Himalayan and Gangdise orogenic belts. Therefore, the tectonic evolution stages experienced by the Oiyug Basin during the past 15 Ma could have a regional significance for southern Tibet. The chronological data obtained from this study may provide some constraints for further studies with regard to the tectonic processes and environmental changes in southern Tibetan Plateau.

  13. Detailed history of atmospheric trace elements from the Quelccaya ice core (Southern Peru) during the last 1200 years

    Science.gov (United States)

    Uglietti, C.; Gabrielli, P.; Thompson, L. G.

    2013-12-01

    The recent increase in trace element concentrations, for example Cr, Cu, Zn, Ag, Pb, Bi, and U, in polar snow and ice has provided compelling evidence of a hemispheric change in atmospheric composition since the nineteenth century. This change has been concomitant with the expansion of the Industrial Revolution and points towards an anthropogenic source of trace elements in the atmosphere. There are very few low latitude trace element ice core records and these are believed to be sensitive to perturbations of regional significance. To date, these records have not been used to document a preindustrial anthropogenic impact on atmospheric composition at low latitudes. Ice cores retrieved from the tropical Andes are particularly interesting because they have the potential to reveal detailed information about the evolution and environmental consequences of mineral exploitation related to the Pre Inca Civilizations, the Inca Empire (1438-1533 AD) and the subsequent Spanish invasion and dominance (1532-1833 AD). The chemical record preserved in the ice of the Quelccaya ice cap (southern Peruvian Andes) offers the exceptional opportunity to geochemically constrain the composition of the tropical atmosphere at high resolution over the last ~1200 years. Quantification of twenty trace elements (Ag, Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Rb, Sb, Sn, Ti, Tl, U, V, and Zn) was performed by ICP-SFMS over 105 m of the Quelccaya North Dome core (5600 m asl, 128.57 m) by analyzing 2450 samples. This provides the first atmospheric trace element record in South America spanning continuously and at high resolution for the time period between 1990 and 790 AD. Ag, As, Bi, Cd, Cr, Co, Cu, Mn, Mo, Sb, Sn, Pb and Zn show increases in concentration and crustal enrichment factor starting at different times between 1450 and 1550 AD, in concomitance with the expansions of the Inca Empire and, subsequently, the Spanish Empire well before the inception of the Industrial Revolution. This

  14. Along-Strike Variations in Focal Mechanisms of Central Andean Crustal Earthquakes: Northern Peru through the Argentina Sierras Pampeanas

    Science.gov (United States)

    Devlin, S.; Isacks, B. L.

    2003-12-01

    120 shallow focal mechanisms in the crust above the subducted Nazca plate were assembled from the Harvard CMT catalog and published studies covering over 40 years of seismicity. The study area included the Andes crust above three major segments of the subducted plate, the Peruvian and Argentinean flat-slab segments and the intervening segment where the subducted Nazca plate dips more steeply. The most seismically active regions continue to be the thick-skinned foreland thrust belts in the eastern Andes of Peru and the Sierras Pampeanas. The earthquakes there are clearly associated with youthful tectonic structures with strong topographic signatures as revealed by the new 90 m SRTM digital elevation models. The mechanisms are dominantly of the thrust type but include a minority of strike-slip orientations. However the P axes remain consistent. The thin-skinned thrust belts east of the central Andean Plateau show significant activity only near Santa Cruz, Bolivia and northern Argentina; most of the Sub-Andean thrust belt of Bolivia and southern Peru remains aseismic. The central Andean plateau itself also remains aseismic except for the region of southern Peru and two earthquakes in the Puna. The crustal seismicity in southern Peru is largely concentrated on the western side of the plateau. The focal mechanisms show a strong grouping of T axes in a horizontal, north-south orientation. Both normal and strike-slip mechanisms occur in this region, with no obvious correlation with elevation or surface structures. Remarkably, with the exception of one normal fault type mechanism near the Cusco basin, the earthquakes occur in regions of the western parts of the Altiplano that do not exhibit topographic evidence of substantial crustal deformation. These results are consistent with a model in which the Altiplano of southern Peru, with a trend most oblique to the overall direction of convergence, manifests a left-lateral shearing component across the orogen.

  15. Norian-Rhaetian sedimentary evolution of the Slovenian Basin (eastern Southern Alps)

    Science.gov (United States)

    Gale, L.; Šmuc, A.; Kolar-Jurkovšek, T.; Skaberne, D.; Celarc, B.; Čar, J.; Rožič, B.

    2012-04-01

    The Slovenian Basin represents a Mesozoic deep water sedimentary environment, during the Triassic situated on the southern passive continental margin of the Neotethys (Meliata) Ocean (cf. Schmid et al., 2008). The Norian-Rhaetian sedimentary evolution of the Slovenian Basin is reconstructed on the basis of five sections located in different parts of the Tolmin Nappe (Eastern Southern Alps, western Slovenia). The correlation of sections is based on conodont data and facies analysis. The Norian-Rhaetian interval is in the basin represented by the "Bača dolomite" (bedded dolostone with chert) and the Slatnik Formation (hemipelagic and allodapic limestones), while the bordering reef-rimmed carbonate platforms in inner areas record peritidal deposition (Main Dolomite, Dachstein Limestone). The transition from claystone and marly limestone dominated "Amphiclina beds" to the bedded "Bača dolomite" took place at the Carnian-Norian boundary. The change in facies can be attributed to the eustatic rise of sea-level and the subsequent retreat of terrigenous input. Intensive basin-wide slumping took place during the Early Norian and marks a short period of tectonic activity. Slump breccias are followed by bedded dolostones. An increase in terrigenous input in pyrite-enriched thin-bedded dolostones indicates a relative sea-level fall (cf. Haas, 2002) at the Early-Middle Norian boundary. The Middle-Late Norian sedimentation is dominated by bedded dolostones. The microfacies analysis of scarce non-dolomitized horizons indicates hemipelagic deposition and sedimentation from distal turbidites, with material derived from adjacent platform. An interval of slump breccias suggests that another tectonic pulse took place during the Middle Norian. The Late Norian in the northern part of the Tolmin Nappe already belongs to the Slatnik Formation, which spans the rest of the Triassic, while in other parts of the Basin the "Bača dolomite" continues up to the Triassic-Jurassic boundary. The

  16. Tracing the lateral movement of sediments through a shrubland environment using fallout radionuclides, Jornada Basin, Southern New Mexico

    Science.gov (United States)

    Semi-arid grassland and savanna communities in many parts of the world have been displaced by woody shrubs. In the Jornada Basin of southern New Mexico, the displacement of perennial grasslands is well documented beginning in 1858. As shrubs invade semi-arid perennial grasslands, the length, number,...

  17. Hydrological modeling of the semi-arid Andarax river basin in southern Spain

    DEFF Research Database (Denmark)

    Andersen, Flemming Hauge; Jensen, Karsten Høgh; Sandholt, Inge

      The 2,265 km2 Andarax river basin located in Southern Spain is one of the most arid regions in Europe with a mean annual precipitation of 250-350 mm, which mainly falls (70%) in autumn and winter. The terrain changes from sea level at the coast to more than 2,500 m in the Sierra Nevada Mountains....... Most of the precipitation falling in the mountainous areas, where the unit Triassic schists dominates, is converted into overland flow, which runs directly to the rivers. In areas with limestone most of the precipitation infiltrates and is subsequently routed through fractures before discharging...... availability in the delta region. Due to the high evapotranspiration in semi-arid or arid regions groundwater recharge can be as low as 1 % of the precipitation. Thus it is essential to accurately predict the seasonal and regional distribution of actual evapotranspiration (ET) within the river catchment...

  18. Human environment and climate during the Middle Pleistocene in southern Italy (Boiano basin, Molise)

    Science.gov (United States)

    Orain, R.; Lebreton, V.; Russo Ermolli, E.; Sémah, A.-M.; Nomade, S.; Shao, Q.; Bahain, J.-J.; Peretto, C.

    2012-04-01

    Palaeobotanical investigations undertaken on early prehistoric sites of Western Europe, as Pont-de-Lavaud (France, ca 1.2 - 1 Ma) and Ca' Belvedere di Monte Poggiolo (Italy, ca 1.2 - 0.8 Ma), indicate that hominins have settled in different types of environments. During the "Mid-Pleistocene Transition (MPT)", at about 1 to 0.6 Ma, the transition from 41-ka to 100-ka dominant climatic oscillations occurring within a long-term cooling trend is associated with an aridity crisis and strongly modified the structure of environments. Since the MPT, the specific climate and environment evolution of the southern Italy provided propitious conditions for a long-term human occupation even during glacial times and the density of prehistoric sites could probably be explained by the amount of sustainable environments. The human strategy of occupation of a territory probably was motivated by availabilities of resources for subsistence in the local ecosystems. Sites such as La Pineta (ca 600 ka), Notarchirico (ca 600 ka), San Nicola di Monteroduni (ca 400 ka) or Ceprano (ca 350 ka) testify to the preferential occupation of the valleys of the central and southern Apennines during this period. In this area, the Boiano basin (Molise, Italy) recorded a lacustrine and fluvio-palustrine sedimentation, with basal deposits older than 440 ka deduced from tephrochronology. Pollen analyse of the Boiano sequence aims to describe the evolution of vegetation and climates between OIS 13 and 9, at regional and micro-regional scales. The characteristics of the Boiano basin are enlightened within the progressive reduction of the deciduous forest diversity along the Middle Pleistocene. The main palaeoecological information consists of an important persistence of edaphic humidity during the glacial phases. The peculiar conditions recorded in the region could have constituted a refuge for arboreal flora during the Middle Pleistocene and provided subsistence resources to the animal and human communities.

  19. Late Paleozoic sedimentation and tectonics of rift and limited ocean basin at southern margin of the Qinling

    Institute of Scientific and Technical Information of China (English)

    孟庆任; 张国伟; 于在平; 梅志超

    1996-01-01

    The rifting and occurrence of limited oceanic basin at southern margin of Qinling separated south Qinling from Yangtze Block in late Paleozoic. Detailed sedimentary studies were carried out at two localities at southern flank of this rift-limited oceanic basin zone. and depositional architectures were then established accordingly. The results show that tectono-sedimentary stories are differing in different positions but clearly demonstrate spatial development of the rift. It is obvious that the rift in west part of Mianlue underwent two developmentary phases, early rapid subsidence and late slow subsidence, and there occurred breakup unconformity between the seccessions of the two subsidence phases. Combined with the data of structural, geochemical and chronological studies on the ophiolitic complex within the Mianlue zone. it is demonstrated that the rifting-drifting transition occurred, leading to the development of limited oceanic basin during the late Paleazoic. Spatial and temporal evolution of the

  20. Strengthening Adaptation to Extreme Climate Events in Southwestern Amazonia: an Example from the Trinational Acre River Basin in the Madre de Dios/Peru - Acre/Brazil - Pando/Bolivia (MAP) Region.

    Science.gov (United States)

    Brown, I. F.

    2015-12-01

    Southwestern Amazonia, where Bolivia, Brazil and Peru meet, faces numerous challenges to the sustainable utilization of land and water resources as the region experiences rapid population and economic growth, expanding agriculture, transportation and energy sectors, along with frequent flooding and droughts. It is also predicted to be one of the most susceptible areas for climate change in the coming decade. The Acre River Basin, one of the few trinational basins in Amazonia, lies at the center of the Madre de Dios Region (Peru), Acre State (Brazil) and Pando Department (Bolivia) or MAP Region. It covers approximately 7,500 km2 and its inhabitants range from indigenous groups avoiding contact with industrial society to more than 60,000 dwellers of a binational urban center. The basin incorporates most the challenges facing the region and this paper discusses steps underway to address the basin's vulnerability to climate-related threats. A trinational group of professionals used GIS databases and local knowledge to classify these threats and possible societal responses. To prioritize threats and to propose responses, this group adapted a method proposed by the Queensland Climate Change Centre of Excellence of Australia to develop climate risk matrices for assessing impacts, adaptation, risk and vulnerability. The three priority climate variables were prolonged and more frequent droughts, more intense flooding, and more days with temperatures > 35oC. The final matrix proposed two areas of concentration - 1) Reduce the vulnerability of communities to hydro-meteorological extreme events and 2) Protect and restore ecosystems that maintain critical water-related resources with actions in public policy, capacity-building, and immediate activities. These results are being incorporated into the Amazon Project of the Global Environment Fund of the United Nations Environment Program, administered by the Amazon Cooperation Treaty Organization (ACTO).

  1. In-situ stresses in the Southern Perth Basin at the GSWA Harvey-1 well site

    Science.gov (United States)

    Rasouli, Vamegh 14Pervukhina, Marina 2Müller, Tobias M. 2Pevzner, Roman

    2013-11-01

    Knowledge of orientations and magnitudes of present-day stresses is important for different applications including fault reactivation, borehole stability and CO2 injection studies. As part of the West Hub Carbon Capture and Storage project, the GSWA Harvey-1 well was drilled in early 2012. It is located ~115km south of Perth and is used to assess the suitability for CO2 underground storage. The aim of this study is to estimate the mechanical properties and state of stress fields in the Southern Perth Basin. The analysis is based on the newly acquired log and VSP data and results of a rock mechanical model including vertical profiles of elastic and strength properties as well as identified breakout zones. The results indicate that the stress regime in the region is dominantly strike-slip. It changes to a reverse faulting system at shallow depths of below ~900m. Stress field orientation is obtained from borehole breakout analysis. The average azimuth of the maximum horizontal stress is 106° and the standard deviation is 10°. This direction of the maximum horizontal stress is broadly consistent with the east-west direction earlier reported for the Perth Basin.

  2. Magnitude-frequency distribution of submarine landslides in the Gioia Basin (southern Tyrrhenian Sea)

    Science.gov (United States)

    Casas, D.; Chiocci, F.; Casalbore, D.; Ercilla, G.; de Urbina, J. Ortiz

    2016-12-01

    Regional inventories and magnitude-frequency relationships provide critical information about landslides and represent a first step in landslide hazard assessment. Despite this, the availability of accurate inventories in the marine environment remains poor because of the commonly low accessibility of high-resolution data at regional scales. Evaluating high-resolution bathymetric data spanning the time interval 2007-2011 for the Gioa Basin of the southern Tyrrhenian Sea yielded a landslide inventory of 428 events affecting an area of >85 km2 and mobilizing approximately 1.4 km3 of sediment. This is the first time that this area is studied in such detail, justifying comparison with other areas both onland and offshore. Statistical analyses revealed that the cumulative distribution of the dataset is characterized by two right-skewed probability distributions with a heavy tail. Moreover, evidence of a rollover for smaller landslide volumes is consistent with similar trends reported in other settings worldwide. This may reflect an observational limitation and the site-specific geologic factors that influence landslide occurrence. The robust validation of both power-law and log-normal probability distributions enables the quantification of a range of probabilities for new extreme events far from the background landslide sizes defined in the area. This is a useful tool at regional scales, especially in geologically active areas where submarine landslides can occur frequently, such as the Gioia Basin.

  3. Gully Erosion Monitoring on Shakhen Drainage Basin, Southern Khorasan Province, Iran

    Science.gov (United States)

    Rezaei Moghaddam, M. H.; Saghafi, M.

    In many parts of Iran gullies can be found, but few studies have reported their genesis and characteristics. This study investigates gullies under semi arid climate in the small case-study area of Southern Khorasan Province, in Iran. The objectives are to determine the spatial distribution of gullies in the study area, to measure their morphological and topographical characteristics and to reconstruct the factors that led to their development. Large deep gullies are some of the most important sediment sources in the semi-arid environment of the Shaken Basin. So, this study regards gully development in SHAKHEN drainage basin, north of BIRJAND city, taking into account environmental and social characteristics, which affect gully occurrence and its evolution. Gully erosion clearly is a threshold phenomenon. This geomorphic process occurs only when a threshold in terms of flow hydraulics, rainfall, topography, pedology and land use has been exceeded. In this study with using simple methodology the gully erosion, initiation and development concerning with main factors are monitored. Furthermore, also the role of new tectonics activity in the study area on gully development was considered. Hence, different information resources are being undertaken such as: maps, aerial photos, satellite image and field observations to determine variables in order to understand where and why gullies occurred and developed.

  4. Magnitude-frequency distribution of submarine landslides in the Gioia Basin (southern Tyrrhenian Sea)

    Science.gov (United States)

    Casas, D.; Chiocci, F.; Casalbore, D.; Ercilla, G.; de Urbina, J. Ortiz

    2016-07-01

    Regional inventories and magnitude-frequency relationships provide critical information about landslides and represent a first step in landslide hazard assessment. Despite this, the availability of accurate inventories in the marine environment remains poor because of the commonly low accessibility of high-resolution data at regional scales. Evaluating high-resolution bathymetric data spanning the time interval 2007-2011 for the Gioa Basin of the southern Tyrrhenian Sea yielded a landslide inventory of 428 events affecting an area of >85 km2 and mobilizing approximately 1.4 km3 of sediment. This is the first time that this area is studied in such detail, justifying comparison with other areas both onland and offshore. Statistical analyses revealed that the cumulative distribution of the dataset is characterized by two right-skewed probability distributions with a heavy tail. Moreover, evidence of a rollover for smaller landslide volumes is consistent with similar trends reported in other settings worldwide. This may reflect an observational limitation and the site-specific geologic factors that influence landslide occurrence. The robust validation of both power-law and log-normal probability distributions enables the quantification of a range of probabilities for new extreme events far from the background landslide sizes defined in the area. This is a useful tool at regional scales, especially in geologically active areas where submarine landslides can occur frequently, such as the Gioia Basin.

  5. Modeling of soil erosion and sediment transport in the East River Basin in southern China.

    Science.gov (United States)

    Wu, Yiping; Chen, Ji

    2012-12-15

    Soil erosion is a major global environmental problem that has caused many issues involving land degradation, sedimentation of waterways, ecological degradation, and nonpoint source pollution. Therefore, it is significant to understand the processes of soil erosion and sediment transport along rivers, and this can help identify the erosion prone areas and find potential measures to alleviate the environmental effects. In this study, we investigated soil erosion and identified the most seriously eroded areas in the East River Basin in southern China using a physically-based model, Soil and Water Assessment Tool (SWAT). We also introduced a classical sediment transport method (Zhang) into SWAT and compared it with the built-in Bagnold method in simulating sediment transport process along the river. The derived spatial soil erosion map and land use based erosion levels can explicitly illustrate the identification and prioritization of the critical soil erosion areas in this basin. Our results also indicate that erosion is quite sensitive to soil properties and slope. Comparison of Bagnold and Zhang methods shows that the latter can give an overall better performance especially in tracking the peak and low sediment concentrations along the river. We also found that the East River is mainly characterized by sediment deposition in most of the segments and at most times of a year. Overall, the results presented in this paper can provide decision support for watershed managers about where the best management practices (conservation measures) can be implemented effectively and at low cost. The methods we used in this study can also be of interest in sediment modeling for other basins worldwide.

  6. Biostratigraphy of a Paleocene–Eocene Foreland Basin boundary in southern Tibet

    Directory of Open Access Journals (Sweden)

    Xiaoqiao Wan

    2010-10-01

    Full Text Available This study of the Paleocene–Eocene boundary within a foreland basin of southern Tibet, which was dominated by a carbonate ramp depositional environment, documents more complex environmental conditions than can be derived from studies of the deep oceanic environment. Extinction rates for larger foraminiferal species in the Zongpu-1 Section apply to up to 46% of the larger foraminiferal taxa. The extinction rate in southern Tibet is similar to rates elsewhere in the world, but it shows that the Paleocene fauna disappeared stepwise through the Late Paleocene, with Eocene taxa appearing abruptly above the boundary. A foraminifera turnover was identified between Members 3 and 4 of the Zongpu Formation—from the Miscellanea–Daviesina assemblage to an Orbitolites–Alveolina assemblage. The Paleocene and Eocene boundary is between the SBZ 4 and SBZ 5, where it is marked by the extinction of Miscellanea miscella and the first appearance of Alveolina ellipsodalis and a large number of Orbitolites. Chemostratigraphically, the δ13C values from both the Zongpu-1 and Zongpu-2 Sections show three negative excursions in the transitional strata, one in Late Paleocene, one at the boundary, and one in the early Eocene. The second negative excursion of δ13C, which is located at the P–E boundary, coincides with larger foraminifera overturn. These faunal changes and the observed δ13C negative excursions provide new evidence on environmental changes across the Paleocene–Eocene boundary in Tibet.

  7. Biostratigraphy of a Paleocene-Eocene Foreland Basin boundary in southern Tibet

    Institute of Scientific and Technical Information of China (English)

    Xiaoqiao Wan; Xi Wang; Luba F.Jansa

    2010-01-01

    This study of the Paleocene-Eocene boundary within a foreland basin of southern Tibet,which was dominated by a carbonate ramp depositional environment, documents more complex environmental conditions than can be derived from studies of the deep oceanic environment. Extinction rates for larger foraminiferal species in the Zongpu-1 Section apply to up to 46% of the larger foraminiferal taxa.The extinction rate in southern Tibet is similar to rates elsewhere in the world, but it shows that the Paleocene fauna disappeared stepwise through the Late Paleocene, with Eocene taxa appearing abruptly above the boundary. A foraminifera turnover was identified between Members 3 and 4 of the Zongpu Formation-from the Miscellanea-Daviesina assemblage to an Orbitolites-Alveolina assemblage. The Paleocene and Eocene boundary is between the SBZ 4 and SBZ 5, where it is marked by the extinction of Miscellanea miscella and the first appearance of Alveolina ellipsodalis and a large number of Orbitolites.Chemostratigraphically, the δ13C values from both the Zongpu-1 and Zongpu-2 Sections show three negative excursions in the transitional strata, one in Late Paleocene, one at the boundary, and one in the early Eocene. The second negative excursion of δ13C, which is located at the P-E boundary, coincides with larger foraminifera overturn. These faunal changes and the observed δ13C negative excursions provide new evidence on environmental changes across the Paleocene-Eocene boundary in Tibet.

  8. Mercury Levels in Human Hair and Farmed Fish near Artisanal and Small-Scale Gold Mining Communities in the Madre de Dios River Basin, Peru

    Science.gov (United States)

    Langeland, Aubrey L.; Hardin, Rebecca D.; Neitzel, Richard L.

    2017-01-01

    Artisanal and small-scale gold mining (ASGM) has been an important source of income for communities in the Madre de Dios River Basin in Peru for hundreds of years. However, in recent decades, the scale of ASGM activities in the region has increased dramatically, and exposures to a variety of occupational and environmental hazards related to ASGM, including mercury, are becoming more widespread. The aims of our study were to: (1) examine patterns in the total hair mercury level of human participants in several communities in the region and compare these results to the 2.2 µg/g total hair mercury level equivalent to the World Health Organization (WHO) Expert Committee of Food Additives (JECFA)’s Provisional Tolerable Weekly Intake (PTWI); and (2), to measure the mercury levels of paco (Piaractus brachypomus) fish raised in local aquaculture ponds, in order to compare these levels to the EPA Fish Tissue Residue Criterion of 0.3 µg Hg/g fish (wet weight). We collected hair samples from 80 participants in four communities (one control and three where ASGM activities occurred) in the region, and collected 111 samples from fish raised in 24 local aquaculture farms. We then analyzed the samples for total mercury. Total mercury levels in hair were statistically significantly higher in the mining communities than in the control community, and increased with increasing geodesic distance from the Madre de Dios headwaters, did not differ by sex, and frequently exceeded the reference level. Regression analyses indicated that higher hair mercury levels were associated with residence in ASGM communities. The analysis of paco fish samples found no samples that exceeded the EPA tissue residue criterion. Collectively, these results align with other recent studies showing that ASGM activities are associated with elevated human mercury exposure. The fish farmed through the relatively new process of aquaculture in ASGM areas appeared to have little potential to contribute to human

  9. [Hyphessobrycon taphorni and H. eschwartzae (Teleostei: Characidae) two new species of fish in the basin of Madre de Dios river, Peru].

    Science.gov (United States)

    Garcia-Alzate, Carlos A; Romin-Valencia, César; Ortega, Hernán

    2013-06-01

    Hyphessobrycon with 129 valid species, is a genus of fish that has a great diversity of species in the Neotropical ichthyofauna, reaches its greatest diversity in the Amazon basin with about 70% of these species, is highly desired by hobbyists because of their beauty and color, and are still meeting new species. We analyzed specimens from the Departamento de Ictiología, Museo de Historia Natural de la Universidad Mayor de San Marcos, Lima, Perú (MUSM); and measurements of the specimens were taken point to point with digital calipers. Observations of bone and cartilage structures were made on cleared and stained (C&S) samples. The morphometric relationships between species using 21 variables were explored using a principal component analysis (PCA). Here we describe two new species, Hyphessobrycon taphorni and H. eschwartzae from the Madre de Dios River drainage, Peru. Hyphessobrycon taphorni sp. n. can be distinguished by the number of dorsal-fin rays (iii, 8), by the number of: pored lateral-line scales (4-5), teeth in the outer premaxillary row (1-2), teeth in the inner premaxillary row (7-8), by: the caudal-peduncle length (11.4-16.4% SL), number of lateral scales (28-29, except from H. loretoensis which has 29-30) and absence of a humeral spot (vs. present), it differs from H. loretoensis by the number of: scales between the lateral line and the anal fin origin (4 vs. 3) and maxillary teeth (2 vs. 3-4), and it differs from H. agulha by the number of branched pectoral-fin rays (11-12 vs. 9-10). Hyphessobrycon eschwartzae sp. n. is distinguished by the number of: simple anal-fin rays (iv), teeth on the dentary (13-15), teeth in the inner premaxillary row (6), teeth in the outer premaxillary row (3, except from H. heterorhabdus and H. loretoensis which have 3-4); it differs from H. loretoensis by the number of: pored lateral-line scales (7 vs. 9-10), scales between the lateral line and the dorsal-fin origin (5 vs. 3-4); it differs from H. agulha in the number of

  10. Determining Deep Basin Structure of the Hueco and southern Mesilla Bolsons, West Texas, Southern New Mexico and Northern Chihuahua Using Nonseismic Geophysical Techniques

    Science.gov (United States)

    Doser, D. I.; Avila, V.; Budhathoki, P.; Marrufo, S.; Montana, C. J.; Kaip, G.; Moncada, M.; Dena Ornelas, O.

    2012-12-01

    The Hueco and southern Mesilla bolsons are the primary groundwater source for much of the El Paso/Ciudad Juarez metropolitan region of over 1 million residents. The bolsons lie at the point where the strike of the southern Rio Grande rift changes from north-south to northwest-southeast, likely due to its interaction with pre-existing Mesozoic and Paleozoic structures. Tectonic activity continues with recent (< 750,000 years) movement along basin bounding and low level (M<4) seismicity. Over the past 4 years we have been using a conjunction of microgravity, magnetic, water well logs and electrical resistivity studies to image the complex structure of these basins within a heavily urbanized environment. These studies suggest the presence of several northwest-southeast striking cross faults within the southern Mesilla Bolson as well as an extensive subsurface andesite body related to the Cristo Rey laccolith. Intrabasin faults in the Hueco Bolson appear to cut the basin into at least 3 smaller subbasins and to control the boundary between fresh and saline water within the aquifer system beneath El Paso. We are also able to trace the East Franklins Mountain fault (last movement < 15,000 ya) at least 15 km south of the U.S.-Mexico border.

  11. Basins Formed by Interaction of Left- and Right-Lateral Faults in the Eastern Transverse Ranges, Southern California

    Science.gov (United States)

    Langenheim, V. E.; Powell, R. E.; Biehler, S.

    2006-12-01

    In a sinistral domain along the dextral San Andreas transform boundary, CW rotation of the Eastern Transverse Ranges is accompanied by left-lateral displacement on the E-striking, through-going Pinto Mountain (PMF), Blue Cut (BCF), Chiriaco (CF), and Salton Creek Fault (SCF) zones. Best-fit offsets matching bedrock geologic features are 14-20 km, 3-7 km, 11-14 km, and 8-14 km, respectively, on the principal faults and 1-3 km on each of lesser faults that do not transect the entire domain. A discrepancy exists between these magnitudes and those predicted by paleomagnetically determined rotations of basalt distributed along the faults. A key approach to resolving this discrepancy is documenting the evolving infrastructure of basins along the fault and internal deformation in the crustal blocks between faults. Here we bring potential-field geophysical data to bear on basin structure. We use gravity data to map mostly concealed left-stepping strands of the northern three through-going fault zones and to reveal several strike-slip basins formed in left steps. Two strike-slip basins are revealed along the PMF. The western basin (Joshua Tree basin) extends E from the town of Yucca Valley for ~20 km long and is 3 km wide and ~1 km deep. We name the N-bounding fault the Yucca Valley strand and the southern strand, the Joshua Tree strand. Although surface expression of the PMF does not extend E of the Mesquite Lake Fault, a prominent gravity gradient suggests that the fault (named the Dale Lake strand) continues E and forms the south margin of a prominent basin beneath Dale Lake Valley. The Dale Lake basin is ~16 km long, ~6 km wide and >2 km deep. Along the BCF, strike-slip basins in Pleasant Valley and western Pinto Basin are ~6 km long, ~3 km wide, and ~1 km deep. In western Pinto Basin, the strand of the BCF based on a topograhic slope break does not coincide with the basin margin as defined by gravity and magnetic data. A large, deep (>2 km) triangular basin occupies

  12. Basin-and Mountain-Building Dynamic Model of "Ramping-Detachment-Compression" in the West Kunlun-Southern Tarim Basin Margin

    Institute of Scientific and Technical Information of China (English)

    CUI Junwen; LI Pengwu; GUO Xianpu; DING Xiaozhong; TANG Zhemin

    2008-01-01

    -present compression-rapid uplift and strong subsidence, when the basin- and mountain-forming processes were simultaneously controlled by north-vergent thrust propagation and compression. The authors summarize the processes as the "ramping-detachment-compression basin- and mountain-forming dynamic model". The basin-range tectonics was initiated in the Late Jurassic, the Miocene-Piiocene were a major transition period for the basin- and mountain-forming mechanism and the terminal early Pleistocene tectonic movement in the main laid a foundation for the basin-and-mountain tectonic framework in the West Kunlun-southern Tarim basin margin.

  13. A thick lens of fresh groundwater in the southern Lihue Basin, Kauai, Hawaii, USA

    Science.gov (United States)

    Izuka, Scot; Gingerich, Stephen

    2002-11-01

    A thick lens of fresh groundwater exists in a large region of low permeability in the southern Lihue Basin, Kauai, Hawaii, USA. The conventional conceptual model for groundwater occurrence in Hawaii and other shield-volcano islands does not account for such a thick freshwater lens. In the conventional conceptual model, the lava-flow accumulations of which most shield volcanoes are built form large regions of relatively high permeability and thin freshwater lenses. In the southern Lihue Basin, basin-filling lavas and sediments form a large region of low regional hydraulic conductivity, which, in the moist climate of the basin, is saturated nearly to the land surface and water tables are hundreds of meters above sea level within a few kilometers from the coast. Such high water levels in shield-volcano islands were previously thought to exist only under perched or dike-impounded conditions, but in the southern Lihue Basin, high water levels exist in an apparently dike-free, fully saturated aquifer. A new conceptual model of groundwater occurrence in shield-volcano islands is needed to explain conditions in the southern Lihue Basin. Résumé. Dans le sud du bassin de Lihue (Kauai, Hawaii, USA), il existe une épaisse lentille d'eau souterraine douce dans une vaste région à faible perméabilité. Le modèle conceptuel conventionnel pour la présence d'eau souterraine à Hawaii et dans les autres îles de volcans en bouclier ne rend pas compte d'une lentille d'eau douce si épaisse. Dans ce modèle conceptuel, les accumulations de lave dont sont formés la plupart des volcans en bouclier couvrent de vastes régions à relativement forte perméabilité, avec des lentilles d'eau douce peu épaisses. Dans le sud du bassin de Lihue, les laves remplissant le bassin et les sédiments constituent une région étendue à faible conductivité hydraulique régionale, qui, sous le climat humide du bassin, est saturée presque jusqu'à sa surface; les surfaces pi

  14. Jurassic sedimentary evolution of southern Junggar Basin:Implication for palaeoclimate changes in northern Xinjiang Uygur Autonomous Region, China

    Institute of Scientific and Technical Information of China (English)

    Shun-Li Li; Xing-He Yu; Cheng-Peng Tan; Ronald Steel

    2014-01-01

    Junggar Basin, located in northern Xinjiang, presents continuous and multi-kilometer-thick strata of the Jurassic deposits. The Jurassic was entirely terrestrial lfuvial and lacustrine deltaic sedimentation. Eight outcrop sections across the Jurassic strata were meas-ured at a resolution of meters in southern Junggar Basin. Controlling factors of sedimentary evolution and palaeoclimate changes in Junggar Basin during the Jurassic were discussed based on lithology, fossils and tectonic setting. In the Early to Middle Jurassic, the warm and wide Tethys Sea generated a strong monsoonal circulation over the central Asian continent, and provided adequate moisture for Junggar Basin. Coal-bearing strata of the Badaowan, Sangonghe, and Xishanyao Formations were developed under warm and humid palaeocli-mate in Junggar Basin. In the late Middle Jurassic, Junggar Basin was in a semi-humid and semi-arid environment due to global warming event. Stratigraphy in the upper part of the Mid-dle Jurassic with less plant fossils became multicolor or reddish from dark color sediments. During the Late Jurassic, collision of Lhasa and Qiangtang Block obstructed monsoon from the Tethys Sea. A major change in climate from semi-humid and semi-arid to arid conditions took place, and reddish strata of the Upper Jurassic were developed across Junggar Basin.

  15. Jurassic sedimentary evolution of southern Junggar Basin:Implication for palaeoclimate changes in northern Xinjiang Uygur Autonomous Region,China

    Institute of Scientific and Technical Information of China (English)

    Shun-Li; Li; Xing-He; Yu; Cheng-Peng; Tan; Ronald; Steel

    2014-01-01

    Junggar Basin,located in northern Xinjiang,presents continuous and multikilometer-thick strata of the Jurassic deposits.The Jurassic was entirely terrestrial fluvial and lacustrine deltaic sedimentation.Eight outcrop sections across the Jurassic strata were measured at a resolution of meters in southern Junggar Basin.Controlling factors of sedimentary evolution and palaeoclimate changes in Junggar Basin during the Jurassic were discussed based on lithology,fossils and tectonic setting.In the Early to Middle Jurassic,the warm and wide Tethys Sea generated a strong monsoonal circulation over the central Asian continent,and provided adequate moisture for Junggar Basin.Coal-bearing strata of the Badaowan,Sangonghe,and Xishanyao Formations were developed under warm and humid palaeoclimate in Junggar Basin.In the late Middle Jurassic,Junggar Basin was in a semi-humid and semi-arid environment due to global warming event.Stratigraphy in the upper part of the Middle Jurassic with less plant fossils became multicolor or reddish from dark color sediments.During the Late Jurassic,collision of Lhasa and Qiangtang Block obstructed monsoon from the Tethys Sea.A major change in climate from semi-humid and semi-arid to arid conditions took place,and reddish strata of the Upper Jurassic were developed across Junggar Basin.

  16. Gravity analysis of the Precambrian basement topography associated with the northern boundary of Ghadames Basin (southern Tunisia)

    Science.gov (United States)

    Dhaoui, Mohamed; Gabtni, Hakim; Jallouli, Chokri; Jleilia, Ali; Mickus, Kevin Lee; Turki, Mohamed Moncef

    2014-12-01

    Gravity data were analyzed to determine the structural development of the northern boundary of the Ghadames Basin in southern Tunisia. The Ghadames Basin which also occurs in eastern Algeria and northwestern Libya is one of the most prolific hydrocarbon producers in North Africa with several of the largest oil fields occurring along its northern boundary. The Ghadames Basin was formed during a series of tectonic events ranging from the Early Paleozoic to the Early Cenozoic. These tectonic events produced a basin in southern Tunisia that has a complex basement configuration which is not completely known. A residual gravity anomaly map constructed using polynomial trend surfaces, and vertical and horizontal gravity derivative maps indicate that the northern boundary contains a series of maxima and minima anomalies that trend in two prominent directions: northeast-southwest and east-west. The horizontal and vertical derivative gravity anomaly maps indicate that the width of the basement structures range between 10 and 20 km in width. Three-dimensional (3D) Euler deconvolution and 3D forward modeling constrained by well data, one seismic reflection profile and remote sensing data confirm the width of the basement structures and indicates that the depth of basin varies between 1.5 and 5 km, with deeper sections in general more numerous in the southern sections of the boundary. The gravity analysis constrained by the seismic reflection profile and well data implies that the basement topography may have been formed during the Pan African and/or late Mesozoic rifting. However, additional seismic reflection and well data are needed to confirm this conclusion. The discovery of the numerous basement structures suggests that there may exist additional hydrocarbon traps within the northern boundary of the Ghadames Basin.

  17. Intraplate deformation of the Al Qarqaf Arch and the southern sector of the Ghadames Basin (SW Libya)

    Science.gov (United States)

    Carruba, Stefano; Perotti, Cesare; Rinaldi, Marco; Bresciani, Ilenia; Bertozzi, Giuseppe

    2014-09-01

    The structural evolution of the Al Qarqaf Arch (Libya) and the southern sector of the Ghadames Basin were reconstructed by the integration of remote sensing analysis, 2D seismic lines, well log data and geological maps. The Al Qarqaf Arch (Libya) is a wide, gentle warping of pre-Cambrian and Palaeozoic rocks that forms the southern boundary of the Ghadames Basin, a large Palaeozoic intracratonic basin of the Saharan Platform. Surface and subsurface analyses revealed the presence of different phases of intracratonic deformations, related to the Al Qarqaf Arch uplift and Ghadames Basin development. Extensional tectonic phases prevailed in the study area up until the Devonian, while compressional folding and structural inversion affected the region during Late Carboniferous and Mesozoic, indicating that compressional horizontal stresses affected the plate interior, giving rise to intraplate tectonics. Three major unconformities (Intra-Silurian, Silurian-Devonian transition and Upper Carboniferous unconformities) outline these tectonic events related to the upwarping of the arch and the downwarping of the basin.

  18. Identifying needs for streamflow forecasting in the Incomati basin, Southern Africa

    Science.gov (United States)

    Sunday, Robert; Werner, Micha; Masih, Ilyas; van der Zaag, Pieter

    2013-04-01

    Despite being widely recognised as an efficient tool in the operational management of water resources, rainfall and streamflow forecasts are currently not utilised in water management practice in the Incomati Basin in Southern Africa. Although, there have been initiatives for forecasting streamflow in the Sabie and Crocodile sub-basins, the outputs of these have found little use because of scepticism on the accuracy and reliability of the information, or the relevance of the information provided to the needs of the water managers. The process of improving these forecasts is underway, but as yet the actual needs of the forecasts are unclear and scope of the ongoing initiatives remains very limited. In this study questionnaires and focused group interviews were used to establish the need, potential use, benefit and required accuracy of rainfall and streamflow forecasts in the Incomati Basin. Thirty five interviews were conducted with professionals engaged in water sector and detailed discussions were held with water institutions, including the Inkomati Catchment Management Agency (ICMA), Komati Basin Water Authority (KOBWA), South African Weather Service (SAWS), water managers, dam operators, water experts, farmers and other water users in the Basin. Survey results show that about 97% of the respondents receive weather forecasts. In contrast to expectations, only 5% have access to the streamflow forecast. In the weather forecast, the most important variables were considered to be rainfall and temperature at daily and weekly time scales. Moreover, forecasts of global climatic indices such as El Niño or La Niña were neither received nor demanded. There was limited demand and/or awareness of flood and drought forecasts including the information on their linkages with global climatic indices. While the majority of respondents indicate the need and indeed use the weather forecast, the provision, communication and interpretation were in general found to be with too

  19. Low flows and reservoir management for the Durance River basin (Southern France) in the 2050s

    Science.gov (United States)

    Sauquet, Eric

    2015-04-01

    The Durance River is one of the major rivers located in the Southern part of France. Water resources are under high pressure due to significant water abstractions for human uses within and out of the natural boundaries of the river basin through an extended open channel network. Water demands are related to irrigation, hydropower, drinking water, industries and more recently water management has included water needs for recreational uses as well as for preserving ecological services. Water is crucial for all these activities and for the socio-economic development of South Eastern France. Both socio-economic development and population evolution will probably modify needs for water supply, irrigation, energy consumption, tourism, industry, etc. In addition the Durance river basin will have to face climate change and its impact on water availability that may question the sustainability of the current rules for water allocation. The research project R²D²-2050 "Risk, water Resources and sustainable Development within the Durance river basin in 2050" aims at assessing future water availability and risks of water shortage in the 2050s by taking into account changes in both climate and water management. R²D²-2050 is partially funded by the French Ministry in charge of Ecology and the Rhône-Méditerranée Water Agency. This multidisciplinary project (2010-2014) involves Irstea, Electricité de France (EDF), the University Pierre et Marie Curie (Paris), LTHE (CNRS), the Société du Canal de Provence (SCP) and the research and consultancy company ACTeon. A set of models have been developed to simulate climate at regional scale (given by 330 projections obtained by applying three downscaling methods), water resources (provided by seven rainfall-runoff models forced by a subset of 330 climate projections), water demand for agriculture and drinking water, for different sub basins of the Durance River basin upstream of Mallemort under present day and under future conditions

  20. Thermal and Evolved Gas Analysis (TEGA) of hyperarid soils doped with microorganisms from the Atacama Desert in southern Peru (Pampas de la Joya): Implications for the Phoenix Mission

    Science.gov (United States)

    Valdivia-Silva, Julio E.; Navarro-Gonzalez, Rafael; McKay, Chris

    TEGA is one of several instruments on board of the Phoenix Lander that will perform differential scanning calorimetry and evolved gas analysis of soil samples and ice, collected from the surface and subsurface at a northern landing site on Mars. TEGA is a combination of a high-temperature furnace and a mass spectrometer that will be use to analyze samples delivered to instrument via a robotic arm. The samples will be heated at a programmed ramp rate up to 1000° C and the power required for heating will be carefully and continuously monitored (scanning calorimetry). The evolved gases generated during the process will be analyzed with the evolved-gas analyzer (a magnetic sector mass spectrometer) in order to determine the composition of gases released as a function of temperature. Our laboratory has developed a sample characterization method using a pyrolizer integrated to a quadrupole mass spectrometer to support the interpretations of TEGA data. Here we examine the thermal and evolved gas properties of six types of hyperarid soils from the Pampas de La Joya southern Peru, a possible analog to Mars, which has been previously enriched with microorganisms (Salmonella thypimurium, Micrococcus luteus, and Candida albicans) to investigate the effect of soil matrix over TEGA response. Between 20 to 40 mg of soil pre-treated to 500° C for 24 hours to remove traces of organics, was mixed with or without 5mg biomass lyophilized (dry weight). Additionally 20 mg of each one microorganism were analyzed. The samples were placed in the pyrolizer that reached 1200° C at 1 hour. The volatiles released were transferred to the MS using helium as a carrier gas. The quadrupole MS was ran in scan mode from 40-350m/z. As expected, there were significant differences in the evolved gas behaviors for microorganism samples with or without a soil matrix under similar heating conditions. In addition, samples belonging to the most arid environments had significant differences compared with

  1. Thermally evolved gas analysis (TEGA) of hyperarid soils doped with microorganisms from the Atacama Desert in southern Peru: Implications for the Phoenix mission

    Science.gov (United States)

    Valdivia-Silva, Julio E.; Navarro-González, Rafael; McKay, Christopher

    2009-07-01

    TEGA, one of several instruments on board of the Phoenix Lander, performed differential scanning calorimetry and evolved gas analysis of soil samples and ice, collected from the surface and subsurface at a northern landing site on Mars. TEGA is a combination of a high temperature furnace and a mass spectrometer (MS) that was used to analyze samples delivered to the instrument via a robotic arm. The samples were heated at a programmed ramp rate up to 1000 °C. The power required for heating can be carefully and continuously monitored (scanning calorimetry). The evolved gases generated during the process can be analyzed with the evolved gas analyzer (a magnetic sector mass spectrometer) in order to determine the composition of gases released as a function of temperature. Our laboratory has developed a sample characterization method using a pyrolyzer integrated to a quadrupole mass spectrometer to support the interpretations of TEGA data. Here we examine the evolved gas properties of six types of hyperarid soils from the Pampas de La Joya in southern Peru (a possible analog to Mars), to which we have added with microorganisms ( Salmonella typhimurium, Micrococcus luteus, and Candida albicans) in order to investigate the effect of the soil matrix on the TEGA response. Between 20 and 40 mg of soil, with or without ˜5 mg of lyophilized microorganism biomass (dry weight), were placed in the pyrolyzer and heated from room temperature to 1200 °C in 1 h at a heating rate of 20 °C/min. The volatiles released were transferred to a MS using helium as a carrier gas. The quadrupole MS was ran in scan mode from 10 to 200 m/z. In addition, ˜20 mg of each microorganism without a soil matrix were analyzed. As expected, there were significant differences in the gases released from microorganism samples with or without a soil matrix, under similar heating conditions. Furthermore, samples from the most arid environments had significant differences compared with less arid soils

  2. Description of Lutzomyia (Trichophoromyia) nautaensis n. sp. (Diptera: Psychodidae) from the Peruvian Amazon Basin.

    Science.gov (United States)

    Fernandez, Roberto; Lopez, Victor; Cardenas, Roldan; Requena, Edwin

    2015-07-01

    A new species of sand fly, which we describe as Lutzomyia (Trichophoromyia) nautaensis n. sp., was collected in the northern Peruvian Amazon Basin. In this region of Peru, cutaneous leishmaniasis is transmitted primarily by anthropophilic sand flies; however, zoophilic sand flies of the subgenus Trichophoromyia may also be incriminated in disease transmission. Detection of Leishmania spp. in Lutzomyia auraensis Mangabeira captured in the southern Peruvian Amazon indicates the potential of this and other zoophilic sand flies for human disease transmission, particularly in areas undergoing urban development. Herein, we describe Lutzomyia (Trichophoromyia) nautaensis n. sp., and report new records of sand flies in Peru.

  3. Nutrient maximums related to low oxygen concentrations in the southern Canada Basin

    Institute of Scientific and Technical Information of China (English)

    JIN Ming-ming; SHI Jiuxin; LU Yong; CHEN Jianfang; GAO Guoping; WU Jingfeng; ZHANG Haisheng

    2005-01-01

    The phenomenon of nutrient maximums at 70~200 m occurred only in the region of the Canada Basin among the world oceans. The prevailing hypothesis was that the direct injection of the low-temperature high-nutrient brines from the Chukchi Sea shelf (<50 m) in winter provided the nutrient maximums. However, we found that there are five problems in the direct injection process. Formerly Jin et al. considered that the formation of nutrient maximums can be a process of locally long-term regeneration. Here we propose a regeneration-mixture process. Data of temperature, salinity, oxygen and nutrients were collected at three stations in the southern Canada Basin during the summer 1999 cruise. We identified the cores of the surface, near-surface, potential temperature maximum waters and Arctic Bottom Water by the diagrams and vertical profiles of salinity, potential temperature, oxygen and nutrients. The historical 129Ⅰ data indicated that the surface and near-surface waters were Pacific-origin, but the waters below the potential temperature maximum core depth was Atlantic-origin. Along with the correlation of nutrient maximums and very low oxygen contents in the near-surface water, we hypothesize that, the putative organic matter was decomposed to inorganic nutrients; and the Pacific water was mixed with the Atlantic water in the transition zone. The idea of the regeneration-mixture process agrees with the historical observations of no apparent seasonal changes, the smooth nutrient profiles, the lowest saturation of CaCO3 above 400 m, low rate of CFC-11 ventilation and 3H-3He ages of 8~18 a around the nutrient maximum depths.

  4. Provenance and paleogeography of the Devonian Durazno Group, southern Parana Basin in Uruguay

    Science.gov (United States)

    Uriz, N. J.; Cingolani, C. A.; Basei, M. A. S.; Blanco, G.; Abre, P.; Portillo, N. S.; Siccardi, A.

    2016-03-01

    A succession of Devonian cover rocks occurs in outcrop and in the subsurface of central-northern Uruguay where they were deposited in an intracratonic basin. This Durazno Group comprises three distinct stratigraphic units, namely the Cerrezuelo, Cordobés and La Paloma formations. The Durazno Group does not exceed 300 m of average thickness and preserves a transgressive-regressive cycle within a shallow-marine siliciclastic shelf platform, and is characterized by an assemblage of invertebrate fossils of Malvinokaffric affinity especially within the Lower Devonian Cordobés shales. The sedimentary provenance of the Durazno Group was determined using petrography, geochemistry, and morphological studies of detrital zircons as well as their U-Pb ages. Sandstone petrography of Cerrezuelo and La Paloma sequences shows that they have a dominantly quartz-feldspathic composition with a minor contribution of other minerals. Whole-rock geochemical data indicate that alteration was strong in each of the three formations studied; chondritic-normalized REE patterns essentially parallel to PAAS, the presence of a negative Eu-anomaly, and Th/Sc and La/Hf ratios point to an average source composition similar to UCC or slightly more felsic. Within the Cerrezuelo Formation, recycling of older volcano-metasedimentary sources is interpreted from Zr/Sc ratios and high Hf, Zr, and REE concentrations. U-Pb detrital zircon age populations of the Cerrezuelo and La Paloma formations indicate that the principal source terranes are of Neoproterozoic age, but include also minor populations derived from Mesoproterozoic and Archean-Paleoproterozoic rocks. A provenance from the Cuchilla Dionisio-Dom Feliciano, Nico Pérez and Piedra Alta terranes of Uruguay and southern Brazil is likely. This study establishes an intracratonic extensional tectonic setting during Durazno time. Considering provenance age sources, regional paleocurrent distributions and the established orogenic history recorded in SW

  5. Water Quality and Soil Natural Salinity in the Southern Imera Basin (Sicily, Italy

    Directory of Open Access Journals (Sweden)

    Roberta Selvaggi

    2010-10-01

    Full Text Available The Southern Imera river crosses one of the most arid part of Sicily. The geochemical composition of the river water is due to the solubilization processes of gypsum rocks, which accounts for the particularly low quality of resources in the areas in which the presence of evaporitics deposits is highest. The geochemical composition and hydraulic parameters of river was monitored with the aim of reaching a better understanding of the relationships between litology and water quality. The Imera river is a potential local hydric resource, but seasonal variability of salinity does not allow farmers to use its water. A geochemical monitoring of the Imera river water has been carried out in selected localities integrating a GIS analysis of the river hydrography basin and of the distribution of the evaporitic formation. During 2003 and 2005 we performed four monitoring surveys of water chemicophysical parameters (temperature, pH and electrical conductivity and of the main ionic concentrations (Ca2+, Mg2+, K+, Na+, Cl-, SO4 2- . We also installed a multiparameter probe next to the hydrometrical station of Drasi, about 15 km from the river mouth. Such multiparameter probe was used to determine, continuously and simultaneously, temperature, electrical conductivity, pH, dissolved oxygen, redox potenzial, water level. The geochemical composition of the water allowed to confirm the results of Roda (1971 and Favara (2000, who pointed out that the main cause of degrade of the Southern Imera river are the salt-rich waters of some tributaries flowing over gypsum rocks and halite deposits. We have been able to identify which specific areas are the main contributors to the degradation of the Imera river.

  6. Urbanization dramatically altered the water balances of a paddy field dominated basin in Southern China

    Directory of Open Access Journals (Sweden)

    L. Hao

    2015-02-01

    Full Text Available Rice paddy fields provide important ecosystem services (e.g., food production, water retention, carbon sequestration to a large population globally. However, these benefits are declining as a result of rapid environmental and socioeconomic transformations characterized by population growth, urbanization, and climate change in many Asian countries. This case study examined the responses of streamflow and watershed water balances to the decline of rice paddy fields due to urbanization in the Qinhuai River Basin in southern China where massive industrialization has occurred in the region during the past three decades. We found that streamflow increased by 58% and evapotranspiration (ET decreased by 23% during 1986–2013 as a result of an increase in urban areas of three folds and reduction of rice paddy field by 27%. Both highflows and lowflows increased significantly by about 28% from 2002 to 2013. The increases in streamflow were consistent with the decreases in ET and leaf area index monitored by independent remote sensing MODIS data. The reduction in ET and increase in streamflow was attributed to the large cropland conversion that overwhelmed the effects of regional climate warming and climate variability. Converting traditional rice paddy fields to urban use dramatically altered land surface conditions from a water-dominated to a human-dominated landscape, and thus was considered as one of the extreme types of contemporary hydrologic disturbances. The ongoing large-scale urbanization in the rice paddy-dominated regions in the humid southern China, and East Asia, will likely elevate stormflow volume, aggravate flood risks, and intensify urban heat island effects. Understanding the linkage between land use change and changes in hydrological processes is essential for better management of urbanizing watersheds.

  7. Natural gas qualities in the Southern Permian basin; Die Erdgasqualitaeten im suedlichen Permbecken

    Energy Technology Data Exchange (ETDEWEB)

    Gerling, P.; Kockel, F. [BGR, Hannover (Germany); Lokhorst, A.; Geluk, M.C. [TNO, Haarlem (Netherlands); Nicholson, R.A. [British Geological Survey, Nottingham (United Kingdom); Laier, T. [Danmarks og Groenlands Geologiske Undersoegelse, Kopenhagen (Denmark); Pokorski, J. [Panstwowy Instytut Geologiczny, Warsaw (Poland)

    1998-12-31

    There is a substantial amount of molecular and isotopic gas data in the literature but mostly in the archives of companies and geological services. As the geological services of most European countries traditionally contain (confidential and non-confidential) data on geology and resources these institutions from Great Britain, the Netherlands, Denmark, Poland and Germany decided to compile molecular and isotopic natural gas data from the area of the Southern European Permian basin. The partially EU-subsidised project was carried out between 1994 and 1997 (LOKHORST ed. 1998) The atlas is based on existing data and also on newly determined molecular and isotopic gas parameters. Ring analyses of national and international standard gases ensure the quality and comparability of the data thus obtained. The aim of the ``stocktaking`` of natural gas was to describe the gas qualities from the Southern North Sea in the West to the Eastern borders of Poland, to characterise them genetically and to relate the to the geological environment. (orig.) [Deutsch] Ein substantieller Anteil von molekularen und isotopischen Gasdaten existiert, teilweise in der Literatur, vor allem aber in den Archiven der Firmen und der geologischen Dienste. Da die geologischen Dienste der meisten europaeischen Laender traditionell (oeffentliche und vertrauliche) Daten ueber die Geologie und Rohstoffe vorhalten, haben sich diese Institutionen aus Grossbritanien, den Niederlanden, Daenemark, Polen und Deutschlands entschlossen, molekulare und isotopische Erdgasdaten aus dem Bereich des suedlichen europaeischen Permbeckens zu kompilieren. Das partiell von der EU gefoerderte Projekt wurde in den Jahren 1994 bis 1997 durchgefuehrt (LOKHORST ed. 1998). Ausser auf bereits vorhandenen Daten beruht der Atlas auf etwa 200 Neu-Bestimmungen molekularer und isotopischer Gasparameter. Ringanalysen nationaler und internationeler Standardgase gewaehrleisteten die Qualitaet und die Vergleichbarkeit der gewonnenen

  8. Interannual variability of the summer precipitation and streamflow in coastal river basins in Southern Oaxaca, Mexico

    Science.gov (United States)

    Perez, N.; Kretzschmar, T.; Cavazos, T.; Munoz-Arriola, F.

    2013-05-01

    Interannual variability of summer rainfall and streamflow in coastal river basins in Southern Oaxaca, Mexico (Río Verde, Río Tehuantepec, and the Southern Coast) were compared and the relationship with El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) were evaluated. A regionalization based on an oblique-rotated component analysis (PCA) was applied to 47 climatological stations, in the period from 1960 to 1990, and four precipitation regions were defined. Seventeen streamflow stations were clustered according to the four regions derived from the PCA. A correlation between annual precipitation and annual streamflow in each region was carried out; in the four regions, streamflow variability was significantly correlated (95% level) with annual rainfall, with higher values in the wettest regions. Therefore, regional streamflow during the study period is modulated by interannual rainfall. A significant negative correlation at the 95 % level was only found with the Oceanic El Niño Index (ONI) in rainfall Region 3, nearest to the Gulf of Tehuantepec. Wet years, mainly were associated with SST anomalies (≥ -0.6°C) similar to weak La Niña and Neutral cool conditions, while dry years were associated with positive SST anomalies similar to Neutral warm conditions (≤ 0.5°C). This rainfall-streamflow relationship with ENSO means, that for example for years with La Niña conditions, the streamflow is expected to show the highest levels, which directly implicates the regional water resource management. In each derived PCA region, the top 95 percentile (P95) of daily precipitation events were also evaluated and divides as those derived from tropical cyclones (TC) of the Eastern Tropical Pacific (EPAC), and non-tropical cyclone (NTC) rainfall events. The largest contribution of extreme P95 precipitation derived from TCs to the annual precipitation was observed in Region 3. A significant upward trend in the contribution of TC

  9. Diamondoid Hydrocarbons as Maturity Indicators for Condensates from Southern Indus Basin, Pakistan

    Directory of Open Access Journals (Sweden)

    Shagufta Nasir

    2013-01-01

    Full Text Available Diamondoid hydrocarbons have been examined in condensates reservoired in the Southern Indus Basin using GC-MS. Bulk properties reveal that samples are waxy and low sulfur with the exception of Pakhro and Gopang which are nonwaxy. TIC show bimodal distribution of n-alkanes along with high abundance of C20+ n-alkanes indicating substantial contribution of terrigeneous OM in these samples. CPI close to one is consistent with mature nature of oils. The samples show two ranges of Pr/Ph ratios. Those within the range of 2.2–2.7 reflect marine depositional settings for OM while others with Pr/Ph >3 may have originated from terrestrial OM deposited under marine oxic conditions. The cross plot of Pr/n-C17 versus Ph/n-C18 indicate type III kerogen as main source of OM deposited under marine to marine oxic conditions. The values of diamondoid based maturity parameters, like methyladamantane index 54.1–75.8% and methyldiamantane index 34.9–56.3% indicate high level of thermal maturity corresponding to vitrinite reflectance 1.1–1.6%. No biodegradation is observed in any of these samples as shown by methyladamantanes/adamantane 3.99–5.52 and methyldiamantanes/diamantane 2.16–2.99 and supported by high values of API gravity (45.13°–60.02° and absence of UCM.

  10. Structural framework and Mesozoic Cenozoic evolution of Ponta Grossa Arch, Paraná Basin, southern Brazil

    Science.gov (United States)

    Strugale, Michael; Rostirolla, Sidnei Pires; Mancini, Fernando; Portela Filho, Carlos Vieira; Ferreira, Francisco José Fonseca; de Freitas, Rafael Corrêa

    2007-09-01

    The integration of structural analyses of outcrops, aerial photographs, satellite images, aeromagnetometric data, and digital terrain models can establish the structural framework and paleostress trends related to the evolution of Ponta Grossa Arch, one of the most important structures of the Paraná Basin in southern Brazil. In the study area, the central-northern region of Paraná State, Brazil, the arch crosses outcropping areas of the Pirambóia, Botucatu, and Serra Geral Formations (São Bento Group, Mesozoic). The Pirambóia and Botucatu Formations are composed of quartz sandstones and subordinated siltstones. The Serra Geral Formation comprises tholeiitic basalt lava flows and associated intrusive rocks. Descriptive and kinematic structural analyses reveal the imprint of two brittle deformation phases: D1, controlled by the activation of an extensional system of regional faults that represent a progressive deformation that generated discontinuous brittle structures and dike swarm emplacement along a NW-SE trend, and D2, which was controlled by a strike-slip (transtensional) deformation system, probably of Late Cretaceous-Tertiary age, responsible for important fault reactivation along dykes and deformation bands in sandstones.

  11. Features of Late Cenozoic Deepwater Sedimentation in Southern Qiongdongnan Basin,Northwestern South China Sea

    Institute of Scientific and Technical Information of China (English)

    Yuan Shengqiang; Yao Genshun; Lü Fuliang; Hu Bing; He Xiaosu; Wang Bin; Li Li

    2009-01-01

    Based on high resolution 2D and 3D seismic data acquired in recent years,using sequence stratigraphy analysis and geophysical methods,we discuss the features of Late Cenozoic deepwater sedimentation in the southern Qiongdongnan (琼东南) basin.The study area entered a bathyal slope environment in the Miocene.The channel developed in the Sanya (三亚) Formation was controlled by a fault break,and its shingled seismic characteristics represent multiple erosion and fill,which may indicate that turbidite current developed in the slope environment.The polygon faults found in mudstone of the Meishan (梅山) Formation represent the deepwater hungry sedimentary environment.The large-scale channels developed on the top of HuangUu (黄流) Formation could be the result of a big sea level drop and an increase of sediment supply.The fantastic turbidite channel developed in Late Quaternary in the slope environment has "fan-like" body and long frontal tiny avuision channel The analysis of these features suggests that the sediment supply of the study area in the post-rifting period was dominant from the Vietnam uplift in the southwest.These deepwater sedimentary features could be potential reservoirs or migration pathways for deepwater petroleum systems.

  12. Geochemical processes controlling the groundwater quality in lower Palar river basin, southern India

    Indian Academy of Sciences (India)

    M Senthilkumar; L Elango

    2013-04-01

    Hydrogeochemical study of groundwater was carried out in a part of the lower Palar river basin, southern India to determine the geochemical processes controlling the groundwater quality. Thirty-nine groundwater samples were collected from the study area and analysed for pH, Eh, EC, Ca, Mg, Na, K, HCO3, CO3, Cl and SO4. The analysed parameters of the groundwater in the study area were found to be well within the safe range in general with respect to the Bureau of Indian Standards for drinking water except for few locations. The results of these analyses were used to identify the geochemical processes that are taking place in this region. Cation exchange and silicate weathering are the important processes controlling the major ion distribution of the study area. Mass balance reaction model NETPATH was used to assess the ion exchange processes. High concentration of Ca in groundwater of the study area is due to the release of Ca by aquifer material and adsorption of Na due to ion exchange processes. Groundwater of the study area is suitable for drinking and irrigation purposes except for few locations.

  13. Historical evolution of slope instability in the Calore River Basin, Southern Italy

    Science.gov (United States)

    Diodato, Nazzareno; Soriano, Marcella; Bellocchi, Gianni; Fiorillo, Francesco; Cevasco, Andrea; Revellino, Paola; Guadagno, Francesco Maria

    2017-04-01

    There is interest in knowing historical spatio-temporal patterns of landslide activity. However, this is challenging to reconstruct because it is difficult to obtain detailed records for past landslide activity. Here, we deal with hydro-geomorphological signatures, such as storms, downpours, floods, snowmelt and mass movement, to detect annual slope instability events (ASIEs) over historical times. In order to obtain ASIEs for each year, a monthly Instability Density Index (IDI) was used and then monthly values were summed up to obtain a yearly value. Classes of monthly IDI varying between 0 (no instability) and 4 (highest instability) were determined from historical documents. We present an application for the Calore River Basin, Southern Italy, using data from a 313-year long series (1701-2013 CE). After 1880 CE the information becomes more valuable with directly observed landslide frequency. By this cataloguing, 129 ASIEs were obtained. Their evolution shows slight instability during the 18th century. Uneven and greater slope instability occurred instead across the 19th century, when an important phase of deforestation coincided with intensification of agricultural activities. Slope instability events continued during the 20th century but their causes are mainly related to anthropisation and the effects of recent climate change. It was determined that stormy autumns until the 19th century and successive winter-times with enhanced snowmelt, may have driven the reactivation of widespread instability events. We also found that mountainous and hilly terrains have an acute sensitivity to climate change.

  14. Platform sedimentation and collapse in a carbonate-dominated margin of a foreland basin (Jaca basin, Eocene, southern Pyrenees)

    Science.gov (United States)

    Barnolas, Antonio; Teixell, Antonio

    1994-12-01

    The Eocene Jaca basin is a foreland basin with well-exposed carbonate platforms in the distal margin. This margin underwent alternating periods of stable platform growth and platform drowning. Periods of drowning were accompanied by large-scale collapses with generation of shelf-edge truncations and resedimentation of carbonate megabreccias into a terrigenous turbiditic trough. These features caused a stepped retreat of the platforms and are related to episodic variations of tectonic loading in the hinterland and correlative flexural bending of the distal basin.

  15. A review of the stratigraphy and sedimentary environments of the Karoo-aged basins of Southern Africa

    Science.gov (United States)

    Smith, R. M. H.; Eriksson, P. G.; Botha, W. J.

    1993-02-01

    The Karoo Basin of South Africa was one of several contemporaneous intracratonic basins in southwestern Gondwana that became active in the Permo-Carboniferous (280 Ma) and continued to accumulate sediments until the earliest Jurassic, 100 million years later. At their maximum areal extent, during the early Permian, these basins covered some 4.5 million km 2. The present outcrop area of Karoo rocks in southern Africa is about 300 000 km 2 with a maximum thickness of some 8000 m. The economic importance of these sediments lies in the vast reserves of coal within the Ecca Group rocks of northern and eastern Transvaal and Natal, South Africa. Large reserves of sandstone-hosted uranium and molybdenum have been proven within the Beaufort Group rocks of the southern Karoo trough, although they are not mineable in the present market conditions. Palaeoenvironmental analysis of the major stratigraphic units of the Karoo succession in South Africa demonstrates the changes in depositional style caused by regional and localized tectonism within the basin. These depocentres were influenced by a progressive aridification of climate which was primarily caused by the northward drift of southwestern Gondwana out of a polar climate and accentuated by the meteoric drying effect of the surrounding land masses. Changing palaeoenvironments clearly influenced the rate and direction of vertebrate evolution in southern Gondwana as evidenced by the numerous reptile fossils, including dinosaurs, which are found in the Karoo strata of South Africa, Lesotho, Namibia and Zimbabwe. During the Late Carboniferous the southern part of Gondwana migrated over the South Pole resulting in a major ice sheet over the early Karoo basin and surrounding highlands. Glacial sedimentation in upland valleys and on the lowland shelf resulted in the Dwyka Formation at the base of the Karoo Sequence. After glaciation, an extensive shallow sea covered the gently subsiding shelf, fed by large volumes of meltwater

  16. Slab roll-back and trench retreat as controlling factor for basin subsidence in southern Central America

    Science.gov (United States)

    Brandes, Christian; Winsemann, Jutta

    2015-04-01

    Slab roll-back and trench retreat are important factors for basin subsidence, magma generation and volcanism in arc-trench systems. Based on the sedimentary and tectonic record of the southern Central American island-arc we conclude that repeated phases of slab roll-back and trench retreats occurred the arc-trench system since the Late Cretaceous. These trench retreats were most probably related to the subduction of oceanic plateaus and seamounts and effected both the fore-arc and back-arc evolution. We used numerical basin modelling techniques to analyse the burial history of fore-arc and back-arc basins in Central America and combined the results with field data of the sedimentological evolution of the basin-fills. From the basin models, geohistory curves were extracted for the fore-arc and back-arc basins to derive the subsidence evolution. The Sandino Fore-arc Basin is characterized by low subsidence during the first 40 Myr. Since the Late Cretaceous the basin has a linear moderate subsidence with a phase of accelerated subsidence in the Oligocene. In the North and South Limón Back-arc Basin, subsidence started at approximately the same time as in the Sandino Fore-arc Basin. The North and South Limón Basins show a linear subsidence trend in the Paleocene and Eocene. Evidence for trench retreats is given by pulses of uplift in the outer-arc area, followed by subsidence in both the fore-arc and back-arc basins. The first slab roll-back probably occurred during the Early Paleocene. This is indicated by the collapse of carbonate platforms, and the re-deposition of large carbonate blocks into deep-water turbidites. A new pulse of uplift or decreased subsidence, respectively during the Late Eocene is attributed to subduction of rough crust. A subsequent slab detachment and the establishment of a new subduction zone further westward was described by Walther et al. (2000). Strong uplift affected the entire fore-arc area, which led to the deposition of very coarse

  17. Early to Middle Ordovician back-arc basin in the southern Appalachian Blue Ridge: characteristics, extent, and tectonic significance

    Science.gov (United States)

    Tull, James; Holm-Denoma, Christopher S.; Barineau, Clinton I.

    2014-01-01

    Fault-dismembered segments of a distinctive, extensive, highly allochthonous, and tectonically significant Ordovician (ca. 480–460 Ma) basin, which contains suites of bimodal metavolcanic rocks, associated base metal deposits, and thick immature deep-water (turbiditic) metasediments, occur in parts of the southern Appalachian Talladega belt, eastern Blue Ridge, and Inner Piedmont of Alabama, Georgia, and North and South Carolina. The basin's predominantly metasedimentary strata display geochemical and isotopic evidence of a mixed provenance, including an adjacent active volcanic arc and a provenance of mica (clay)-rich sedimentary and felsic plutonic rocks consistent with Laurentian (Grenvillian) upper-crustal continental rocks and their passive-margin cover sequences. Geochemical characteristics of the subordinate intercalated bimodal metavolcanic rocks indicate formation in a suprasubduction environment, most likely a back-arc basin, whereas characteristics of metasedimentary units suggest deposition above Neoproterozoic rift and outer-margin lower Paleozoic slope and rise sediments within a marginal basin along Ordovician Laurentia's Iapetus margin. This tectonic setting indicates that southernmost Appalachian Ordovician orogenesis (Taconic orogeny) began as an extensional accretionary orogen along the outer margin of Laurentia, rather than in an exotic (non-Laurentian) arc collisional setting. B-type subduction polarity requires that the associated arc-trench system formed southeast of the palinspastic position of the back-arc basin. This scenario can explain several unique features of the southern Appalachian Taconic orogen, including: the palinspastic geographic ordering of key tectonic elements (i.e., back-arc, arc, etc.), and a lack of (1) an obducted arc sensu stricto on the Laurentian margin, (2) widespread Ordovician regional metamorphism, and (3) Taconic klippen to supply detritus to the Taconic foreland basin.

  18. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Santiago Fire, Orange County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Santiago Fire in Orange County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  19. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Witch Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Witch Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  20. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Canyon Fire, Los Angeles County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Canyon Fire in Los Angeles County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  1. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Ammo Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Ammo Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  2. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Buckweed Fire, Los Angeles County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Buckweed Fire in Los Angeles County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  3. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Harris Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Harris Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  4. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Poomacha Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Poomacha Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  5. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Rice Fire, San Diego County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Rice Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  6. AN UPPER VISÉAN (ASBIAN-BRIGANTIAN AND SERPUKHOVIAN CORAL SUCCESSION AT DJEBEL OUARKZIZ (NORTHERN TINDOUF BASIN, SOUTHERN MOROCCO

    Directory of Open Access Journals (Sweden)

    SERGIO RODRÍGUEZ

    2013-03-01

    Full Text Available The Djebel Ouarkziz Formation, located in the northern part of the Tindouf Basin, in western Algeria and southern Morocco, is composed mainly of shales with interbedded limestones, dolostones and sandstones. The limestone beds are relatively thin, but are laterally persistent, and can be followed along strike for tens of kilometres. We have identified 19 limestone beds in three main sections; one logged along the road from Assa to Zag, a second in the Tinguiz-Remz Valley, 15 km to the east, and a third section 10 km west of the Assa-Zag road section. Rugose coral assemblages are recorded in most limestone beds, but the stratigraphically higher beds become more diverse However, many rugose genera and species are persistent throughout much of the succession. The oldest coral assemblages are Asbian in age and the youngest coral assemblages indicate a Serpukhovian age, as confirmed by foraminiferal biostratigraphy. The first appearance of rugose corals shows a different pattern than that in northern Moroccan basins; some common genera that first appear in the Asbian and lower Brigantian in northern Morocco and Europe, appear much later, in the upper Brigantian or Serpukhovian in the Djebel Ouarkziz. The genus Kizilia, which is rare in the Upper Viséan in northern Moroccan basins, is, however, abundant in the Tindouf Basin. Interestingly, the occurrence of the genus Lonsdaleia in the Serpukhovian from Djebel Ouarkziz poses a palaeogeographic problem because of its absence in northern Moroccan basins (except as transported elements in Serpukhovian conglomerates. Similarly, Actinocyathus in the Serpukhovian in the Tindouf Basin is not present north of the Anti-Atlas Mountains. A possible coral migration route to the Tindouf Basin may be from the northeast via the Béchar Basin in Algeria, similar to that already inferred for foraminifers and calcareous algae. 

  7. Geologic Controls of Hydrocarbon Occurrence in the Southern Appalachian Basin in Eastern Tennessee, Southwestern Virginia, Eastern Kentucky, and Southern West Virginia

    Energy Technology Data Exchange (ETDEWEB)

    Robert D. Hatcher

    2004-05-31

    This report summarizes the second-year accomplishments of a three-year program to investigate the geologic controls of hydrocarbon occurrence in the southern Appalachian basin in eastern Tennessee, southwestern Virginia, eastern Kentucky, and southern West Virginia. The project: (1) employs the petroleum system approach to understand the geologic controls of hydrocarbons; (2) attempts to characterize the T-P parameters driving petroleum evolution; (3) attempts to obtain more quantitative definitions of reservoir architecture and identify new traps; (4) is working with USGS and industry partners to develop new play concepts and geophysical log standards for subsurface correlation; and (5) is geochemically characterizing the hydrocarbons (cooperatively with USGS). Second-year results include: All current milestones have been met and other components of the project have been functioning in parallel toward satisfaction of year-3 milestones. We also have been effecting the ultimate goal of the project in the dissemination of information through presentations at professional meetings, convening a major workshop in August 2003, and the publication of results. Our work in geophysical log correlation in the Middle Ordovician units is bearing fruit in recognition that the criteria developed locally in Tennessee and southern Kentucky have much greater extensibility than anticipated earlier. We have identified a major 60 mi-long structure in the western part of the Valley and Ridge thrust belt that is generating considerable exploration interest. If this structure is productive, it will be one of the largest structures in the Appalachians. We are completing a more quantitative structural reconstruction of the Valley and Ridge than has been made before. This should yield major dividends in future exploration in the southern Appalachian basin. Our work in mapping, retrodeformation, and modeling of the Sevier basin is a major component of the understanding of the Ordovician

  8. Hydrologic assessment of three drainage basins in the Pinelands of southern New Jersey, 2004-06

    Science.gov (United States)

    Walker, Richard L.; Nicholson, Robert S.; Storck, Donald A.

    2011-01-01

    The New Jersey Pinelands is an ecologically diverse area in the southern New Jersey Coastal Plain, most of which overlies the Kirkwood-Cohansey aquifer system. The demand for groundwater from this aquifer system is increasing as local development increases. Because any increase in groundwater withdrawals has the potential to affect streamflows and wetland water levels, and ultimately threaten the ecological health and diversity of the Pinelands ecosystem, the U.S. Geological Survey, in cooperation with the New Jersey Pinelands Commission, began a multi-phase hydrologic investigation in 2004 to characterize the hydrologic system supporting the aquatic and wetland communities of the New Jersey Pinelands area (Pinelands). The current investigation of the hydrology of three representative drainage basins in the Pinelands (Albertson Brook, McDonalds Branch, and Morses Mill Stream basins) included a compilation of existing data; collection of water-level and streamflow data; mapping of the water-table altitude and depth to the water table; and analyses of water-level and streamflow variability, subsurface gradients and flow patterns, and water budgets. During 2004-06, a hydrologic database of existing and new data from wells and stream sites was compiled. Methods of data collection and analysis were defined, and data networks consisting of 471 wells and 106 surface-water sites were established. Hydrographs from 26 water-level-monitoring wells and four streamflow-gaging stations were analyzed to show the response of water levels and streamflow to precipitation and recharge with respect to the locations of these wells and streams within each basin. Water-level hydrographs show varying hydraulic gradients and flow potentials, and indicate that responses to recharge events vary with well depth and proximity to recharge and discharge areas. Results of the investigation provide a detailed characterization of hydrologic conditions, processes, and relations among the components

  9. Radiometric age determination of tonsteins and stratigraphic constraints for the Lower Permian coal succession in southern Parana Basin, Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Guerra-Sommer, Margot; Cazzulo-Klepzig, Miriam; Hartmann, Leo Afraneo; Formoso, Milton Luis Laquintinie [Instituto de Geociencias, Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves, 9500, 91501-970 Porto Alegre, Rio Grande do Sul (Brazil); Santos, Joao Orestes Schneider [Centre for Global Targeting, University of Western Australia, Crawley, Perth 6009, WA (Australia); Ketzer, Joao Marcelo [Instituto de Meio Ambiente, Pontificia Universidade Catolica, Avenida Ipiranga, Porto Alegre, Rio Grande do Sul (Brazil)

    2008-03-03

    Ion microprobe (SHRIMP II) dating of zircons from tonsteins interbedded with coal seams from the Candiota and Faxinal coalfields (Early Permian, Rio Bonito Formation, Parana Basin, Brazil) is presented. The mean ages obtained (290.6 {+-} 1.5 Ma) are more precise than previously published intervals. Calibrations of chronostratigraphic data with radiometric ages show that the main coal succession from the southern Basin is constrained to the Middle Sakmarian. The {+-} 2 Ma time interval of deposition supports the hypothesis that the coal-generating process was quite rapid in terms of geological time. In a general context, Faxinal and Candiota coals are assigned, into the Protohaploxypinus goraiensis Subzone, besides some paleocological differences evidenced by palynological studies. This bio-interval does not correspond to a consistent palynostratigraphic tool and more accurate biostratigraphic zonation for the Carboniferous-Permian interval must be delineated. The new results have far-reaching significance for correlations of the Basin with sequences of the Argentinian Paganzo Basin (302 {+-} 6 Ma and 288 {+-} 7 Ma) and also with the Karoo Basin, with the lowermost Ecca Group (288 {+-} 3 Ma and 289.6 {+-} 3.8 Ma). This new evidence supports the presence of an active and widespread Lower Permian explosive volcanic event in western Gondwana, which is interpreted as the same volcanism which produced the Choiyoi Group in western Argentina. According to this correlation the ash-fall source is located about 1400 km to the southwest of their area of deposition. (author)

  10. Description of Lutzomyia (Trichophoromyia) nautaensis n. sp. (Diptera: Psychodidae) from the Peruvian Amazon Basin

    OpenAIRE

    Fernandez, Roberto; Lopez,Victor; Cardenas, Roldan; Requena, Edwin

    2015-01-01

    A new species of sand fly, which we describe as Lutzomyia (Trichophoromyia) nautaensis n. sp., was collected in the northern Peruvian Amazon Basin. In this region of Peru, cutaneous leishmaniasis is transmitted primarily by anthropophilic sand flies; however, zoophilic sand flies of the subgenus Trichophoromyia may also be incriminated in disease transmission. Detection of Leishmania spp. in Lutzomyia auraensis Mangabeira captured in the southern Peruvian Amazon indicates the potential of thi...

  11. The location and nature of the Telemzan High Ghadames basin boundary in southern Tunisia based on gravity and magnetic anomalies

    Science.gov (United States)

    Gabtni, H.; Jallouli, C.; Mickus, K. L.; Zouari, H.; Turki, M. M.

    2006-03-01

    Gravity and magnetic data were analyzed to add constraints on the location and nature of the Telemzan-Ghadames boundary (TGB) and structure of the Ghadames basin in southern Tunisia. TGB is the boundary between the thick sedimentary cover of the intracratonic Ghadames basin to the south and the thin sedimentary cover of the Saharan platform to the north. The upward continuation of the Bouguer gravity anomalies showed that the TGB is a regional geophysical feature that may have controlled the amount of sediment being deposited both north and south of the boundary and the tectonic environment in the region since Paleozoic time. To emphasize the shorter wavelength gravity and magnetic anomalies, a series of gray scale images of the directional horizontal gradients were constructed that determined a series of previously unknown east-west-trending gravity and magnetic anomalies south of 31.6°N that correspond to lineaments seen on a Landsat 7 image and the location of the TGB. Also, an edge-enhancement analysis illustrated the same linear gravity anomalies and showed the subbasins and uplifts within the Ghadames basin had source depths of between 0.5 and 3.4 km. A north-south trending gravity model showed that the TGB is a relatively gradual feature (possibly basement stepped down by relatively low-displacement faulting) controlling the subsidence of the main Ghadames basin and confirms the edge-enhancement analysis that subbasin S3 and uplift U1 are the main structural features within the Ghadames basin. The knowledge of basement architecture of the Ghadames basin is important for future petroleum exploration within this intracratonic basin.

  12. Basin geodynamics and sequence stratigraphy of Upper Triassic to Lower Jurassic deposits of Southern Tunisia

    Science.gov (United States)

    Carpentier, Cédric; Hadouth, Suhail; Bouaziz, Samir; Lathuilière, Bernard; Rubino, Jean-Loup

    2016-05-01

    Aims of this paper are to propose a geodynamic and sequential framework for the late Triassic and early Jurassic of and south Tunisia and to evidence the impact of local tectonics on the stratigraphic architecture. Facies of the Upper Triassic to Lower Jurassic of Southern Tunisia have been interpreted in terms of depositional environments. A sequential framework and correlation schemes are proposed for outcrops and subsurface transects. Nineteen middle frequency sequences inserted in three and a half low frequency transgression/regression cycles were evidenced. Despite some datation uncertainties and the unknown durations of Lower Jurassic cycles, middle frequency sequences appear to be controlled by eustasy. In contrast the tectonics acted as an important control on low frequency cycles. The Carnian flooding was certainly favored by the last stages of a rifting episode which started during the Permian. The regression accompanied by the formation of stacked angular unconformities and the deposition of lowstand deposits during the late Carnian and Norian occured during the uplift and tilting of the northern basin margins. The transpressional activity of the Jeffara fault system generated the uplift of the Tebaga of Medenine high from the late Carnian and led to the Rhaetian regional angular Sidi Stout Unconformity. Facies analysis and well-log correlations permitted to evidence that Rhaetian to Lower Jurassic Messaoudi dolomites correspond to brecciated dolomites present on the Sidi Stout unconformity in the North Dahar area. The Early-cimmerian compressional event is a possible origin for the global uplift of the northern African margin and Western Europe during the late Carnian and the Norian. During the Rhaetian and the early Jurassic a new episode of normal faulting occured during the third low frequency flooding. This tectonosedimentary evolution ranges within the general geodynamic framework of the north Gondwana margin controlled by the opening of both

  13. Coontail fluorite rhythmites of southern Illinois: evidence for episodic basin dewatering

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, C.A.; Kelly, W.C.; Wilkinson, B.H.

    1985-01-01

    Stratiform coontail ore of the Cave-in-Rock fluorite district, southern Illinois, display conspicuous, rhythmic banded textures similar to those reported in many MVT deposits throughout the world (e.g., east Tennessee, USA; Silesian-Cracow Region, Poland; and northern Baffin Island, Canada). Banding is expressed by the rhythmic alteration of two types of layers: detrital layers of fluorite mottled with particulate gangue dolomite and quartz, and layers of clear, crystalline fluorspar. Both are now composed principally of fluorite but differ in color, fabric and outline. In the past, this rhythmic banding has generally been attributed to fine-scale replacement of a primary host rock stratification or to cyclic replacement of host carbonates by a fluid of oscillating chemistry. Detailed megascopic and microscopic studies of these ores and their carbonate host real that ore bands were not derived by fine-scale in situ limestone replacement. Detrital bands contain hydraulically transported, sorted and graded, allochthonous debris derived by dissolution and disaggregation of host limestone and overlying shale. The banded fabric thus represents a cyclic interplay of chemical and hydraulic processes active during hydrothermal ore mineralization. Coontail ore bodies evidently formed in a hydrothermal spelean system, whose laterally sinuous trace reflects localization of hydrothermal activity where feeder faults intersected relatively impermeable roof-rock shales. The banded nature of these ores testifies to the ability of Mississippi Valley-type hydrothermal solutions to both create and fill their own open spaces. Moreover, the rhythmic nature of coontail ores suggests a prolonged and pulsating mineralization best explained by episodic dewatering of the Illinois Basin.

  14. Late quaternary sea bottom conditions in the southern Panama basin, Eastern Equatorial Pacific

    Science.gov (United States)

    Patarroyo, German D.; Martínez, José I.

    2015-11-01

    A paleoceanographic reconstruction of the southern Panama Basin for the last 23.000 years, based on the benthic foraminiferal analysis from the deep sea core ME0005A-24JC (0.01°N, 86.28°W, water depth 2941) is presented. Cluster and SHEBI (SHE Analysis for Biozone Identification) analyses performed on the benthic foraminiferal assemblages, evidence a faunal turnover in the early Holocene at 14 ky BP. Between 23 and 14 ky BP, Fursenkoina rotundata, Hoeglundina elegans, Globobulimina affinis, Globobulimina pacifica, Cibicidoides wuellerstorfi and Uvigerina hispidocostata were common. Conversely, from 14 ky to the present, the assemblage is represented by Chilostomella oolina, Laticarinina pauperata, and Uvigerina proboscidea. This faunal turnover suggests significant fluctuations in oxygen content at the sea floor and the organic matter (OM) influx, which could reflect: (1) fluctuations in the surface productivity related to the equatorial divergence and, (2) OM advection caused by the dynamic of the deep sea currents. Paleoproductivity estimates and benthic foraminiferal rates depict a general trend towards lower values since the Last Glacial Maximum (LGM) with a conspicuous change at 14 ky BP. Therefore, the paleoceanographic reconstructions of the ME0005A-24JC core suggest a transition from La Niña-like conditions during the LGM to El Niño-like conditions in the recent, as previously proposed for the Eastern Equatorial Pacific. Estimates of the paleo-intensity of deep sea currents based on the relative percentage abundance of the epifaunal foraminifera Cibicidoides wuellerstorfi suggest stronger deep sea currents on the Carnegie Ridge before 14 ky BP.

  15. Uncovering the diversity in the Amazophrynella minuta complex: integrative taxonomy reveals a new species of Amazophrynella (Anura, Bufonidae) from southern Peru.

    Science.gov (United States)

    Rojas, Rommel R; Chaparro, Juan C; Carvalho, Vinícius Tadeu De; Ávila, Robson W; Farias, Izeni Pires; Hrbek, Tomas; Gordo, Marcelo

    2016-01-01

    A new species of the genus Amazophrynella (Anura, Bufonidae) is described from the departments of Madre de Dios, Cusco and Junin in Peru. An integrative taxonomy approach is used. A morphological diagnosis, morphometrics comparisons, description of the advertisement call, and the phylogenetic relationships of the new species are provided. Amazophrynella javierbustamantei sp. n. differs from other species of Amazophrynella by: intermediate body-size (snout-vent length 14.9 mm in males, n = 26 and 19.6 mm in females, n = 20), tuberculate skin texture of body, greatest hand length of the Amazophrynella spp. (3.6 mm in males, n = 26 and 4.6 mm in females, n = 20), venter coloration yellowish, tiny rounded black points covering the venter, and thirteen molecular autapomorphies in the 16S RNA gene. Its distribution varies from 215 to 708 m a.s.l. This discovery highlights the importance of the remnant forest in preserving the biodiversity in Peru, and increase in seven the species formally described in the genus Amazophrynella.

  16. Prevalence and risk factors for encephalomyocarditis virus infection in Peru.

    Science.gov (United States)

    Czechowicz, Josephine; Huaman, Jose Luis; Forshey, Brett M; Morrison, Amy C; Castillo, Roger; Huaman, Alfredo; Caceda, Roxana; Eza, Dominique; Rocha, Claudio; Blair, Patrick J; Olson, James G; Kochel, Tadeusz J

    2011-04-01

    Although encephalomyocarditis virus (EMCV) infection has been commonly documented among domestic animals, less is known about EMCV transmission among humans. Recently, we described the isolation of EMCV from two febrile patients in Peru. To further investigate EMCV transmission in Peru, we screened febrile patients reporting to health clinics in Peru for serological evidence of recent EMCV infection. We also conducted a serological survey for EMCV-neutralizing antibodies in the city of Iquitos, located in the Amazon basin department of Loreto, Peru. Additionally, we screened serum from rodents collected from 10 departments in Peru for evidence of EMCV exposure. EMCV infection was found to be only rarely associated with acute febrile disease in Peru, accounting for 17% in cities in the tropical rainforest of northeastern Peru (Iquitos and Yurimaguas). On the basis of the serological survey conducted in Iquitos, risk factors for past infection include increased age, socioeconomic indicators such as residence construction materials and neighborhood, and swine ownership. Evidence from the rodent survey indicates that EMCV exposure is common among Murinae subfamily rodents in Peru (9.4% EMCV IgG positive), but less common among Sigmodontinae rodents (1.0% positive). Further studies are necessary to more precisely delineate the mode of EMCV transmission to humans, other potential disease manifestations, and the economic impact of EMCV transmission among swine in Peru.

  17. What do Great Subduction Earthquakes tell us About Continental Deformation of the Upper Plate in the Central Andes Forearc? Insights From Seismotectonics, Continental Deformation and Coulomb Modelisation Along Southern Peru Margin

    Science.gov (United States)

    Audin, L.; Perfettini, H.; Tavera, H.

    2007-05-01

    Subduction of the Nazca plate beneath the Peruvian margin has produced numerous megathrust earthquakes during the last century and still constitutes mature seismic gaps in some places such as in between Ilo (Peru) and Arica (Chile). The rupture zones of the 1604, 1784 and 1868 southern Peru events were partially reactivated by the Arequipa 2001 (Mw = 8.5) seismic event, whose rupture zone was about 350km-long and stopped its propagation towards the south on Ilo Peninsula. Just after the occurrence of 2001 event, some reactivation of continental fault systems are identified and monitored thanks to the Peruvian seismic network and describe continental deformation processes occurring perpendicularly to the trench or parallel to the trench, traducing the continental plate response to major subduction earthquakes and some partitioning of the deformation. The Chololo and associated ( perpendicular to the trench) fault systems define some 80-km-long margin crustal blocks and the major one coincides with the 2001 earthquake southern limit of the rupture zone as it propagated to the south. These blocks are made from Late Jurassic and Cretaceous plutonic rocks from the Coastal Batholith; these are outcropping in some places and are evidenced by the aeromagnetic mapping elsewhere around the area. Northward along the subduction zone, another boundary between two rupture zones of major subduction earthquake was reactivated recently, perpendicularly to the trench, by the seismic crisis of October 2006, M=6.4, near Lima, right at the southern end of the rupture zone of the 1974 event (Mw=8.1).Those boundaries corresponding to discontinuities (lithospheric fault systems) in the upper plate, trending nearly perpendicular to the trench, act as earthquake barriers during rupture of large seismic events. Additionally occurred on 20 of November 2006 another seismic event (Mw=5.6 Neic, Ml=5.3) in Tacna region, showing a reverse focal mechanism compatible with the trend of the Sama

  18. Drought management plans and water availability in agriculture: A risk assessment model for a Southern European basin

    Directory of Open Access Journals (Sweden)

    Carlos Dionisio Pérez-Blanco

    2014-08-01

    Full Text Available The Drought Management Plans (DMPs are regulatory instruments that establish priorities among the different water uses and define more stringent constraints to access to publicly provided water during droughts, especially for non-priority uses such as agriculture. These plans have recently become widespread across EU southern basins. However, in some of these basins the plans were approved without an assessment of the potential impacts that they may have on the economic activities exposed to water restrictions. This paper develops a stochastic methodology to estimate the expected water availability in agriculture that results from the decision rules of the recently approved DMPs. The methodology is applied to the particular case of the Guadalquivir River Basin in southern Spain. Results show that if DMPs are successfully enforced, available water will satisfy in average 62.2% of current demand, and this figure may drop to 50.2% by the end of the century as a result of climate change. This is much below the minimum threshold of 90% that has been guaranteed to irrigators so far.

  19. Influence of El Niño-Southern Oscillation (ENSO) on the behavior of floods in the Itajaí River basin in Southern Brazil

    Science.gov (United States)

    Tiago Silva, Artur; Portela, Maria Manuela; Naghettini, Mauro; Fernandes, Wilson

    2016-04-01

    The Itajaí River basin is located in the Southeastern South America (SESA) region, where the influence of El Niño-Southern Oscillation (ENSO) on hydrometeorological extremes has been reported. The lower reaches of the river are prone to calamitous floods as the basin is frequently subjected to extreme rainfall events. The history of devastating floods motivated the construction of detention dams in the upper reaches of the river during the 1970s-1990s. This work presents a study on the nonstationarity of floods in the Itajaí River, using a peaks-over-threshold (POT) approach applied to flood data from 3 gauging stations located in the Basin. Exploratory data analysis methods and nonstationary Poisson-Generalized Pareto models are used to study the joint influence of ENSO and upstream flood control dams on the flood regime of the river. Bayesian model estimation techniques are used with prior belief about the Generalized Pareto shape parameter elicited from regional information. The analysis revealed that occurrence rate and over-threshold peak magnitudes exhibit statistically significant and complex relationships with ENSO. Results also show evidence that, while upstream flood detention dams play a perceptible, though small, role in reducing flood hazard, the influence of the climate covariate on the flood regime is dominant. Furthermore, increased ENSO activity in recent decades, possibly related to a reported climate regime shift in the mid-1970s, has increased flood hazard and led to the occurrence of very large annual floods.

  20. Description of Apistogramma paulmuelleri sp n., a new geophagine cichlid species (Teleostei : Perciformes) from the Amazon river basin in Loreto, Peru

    OpenAIRE

    2013-01-01

    A new species of Apistogramma is described from Peru, based on a total of 28 specimens collected in a small forest stream in the catchment of a nameless tributary of the Rio Amazonas about 80 kilometres south of Iquitos, Departamento Loreto (approximately 73 degrees 34' W / 04 degrees 24' S). At first sight Apistogramma paulmuelleri sp. n. resembles A. regani, but is differentiated from the latter and all other Apistogramma species by the combination of a large band-like spot on the caudal-fi...

  1. Geologic appraisal of the petroleum potential of offshore southern California; the borderland compared to onshore coastal basins

    Science.gov (United States)

    Taylor, James Carlton

    1976-01-01

    Offshore southern California is part of a much larger Pacific continental margin, and the two areas have a similar geologic history at least as far back as middle Tertiary time. Assessment of the petroleum potential of the offshore Southern California borderland is accomplished by examining the adjacent highly explored productive coastal basins in the tectonically unstable area west of the San Andreas fault. Known oil and gas accumulations in this region can be characterized as follows: 88 percent comes from the Los Angeles and Ventura basins; 87 percent has been found in late Miocene and younger strata and only 0.2 percent has been found in Eocene strata; 80 percent has been found in thick deposits of deep-water turbidite reservoirs; and 5 percent has been found in fractured Miocene siliceous shale reservoirs. The percentage of siliceous shale reservoirs will increase as a result of recent discoveries in this rock type in the Santa Barbara Channel. Of the 212 known fields only 5 are giants (greater than 500 million barrels), and these fields account for 52 percent of all past production from the region. Most fields are faulted anticlines, and the largest fields have the highest oil recoveries per acre. Geologic knowledge of the offshore is limited by the availability of data. Data have been obtained from geophysical surveys, analyses of bedrock samples from the sea floor, and extrapolations of data from the mainland and offshore islands. Several factors have a negative effect on the assessment of the petroleum potential of the southern California borderland. They are: 1. The Neogene section is relatively thin, and the Paleogene section is thin and has a limited distribution. 2. Over large areas, Miocene sediments apparently rest directly on basement. 3. Along much of the Santa Rosa-Cortes Ridge, sediments are uplifted and truncated, exposing Paleogene rocks. 4. Organic content in Paleogene sediments is believed too low to generate large amounts of petroleum. 5

  2. The Common Agricultural Policy as a driver of water quality changes: the case of the Guadalquivir River Basin (southern Spain

    Directory of Open Access Journals (Sweden)

    Gloria Salmoral

    2015-09-01

    Full Text Available Several studies have analysed the effects of European environmental policies on water quality, but no detailed retrospective analysis of the impacts of the Common Agricultural Policy (CAP reforms on observed water quality parameters has been carried out. This study evaluates the impact of the CAP and other drivers on the concentrations of nitrates and suspended solids in the Guadalquivir River Basin (southern Spain over the 1999-2009 period. The most important drivers that are degrading both water quality indicators are exports from upland areas and agricultural intensification. Water quality conditions have improved in regions where there has been abandonment and/or deintensification. The decoupling process has reduced the concentration of nitrates and suspended solids in a number of subbasins. Although agricultural production and water efficiency in the basin have improved, high erosion rates have not yet been addressed. 

  3. Thermal History of Rocks in the Shiwandashan Basin, Southern China: Evidence from Apatite Fission-Track Analysis

    Institute of Scientific and Technical Information of China (English)

    Wang Xinwei; Wang Xinwen; Ma Yongsheng

    2005-01-01

    Based on interpretations of the apatite fission-track analysis data for 10 outcrop samples and forward modeling of confined fission-track length distributions, the thermal history of rocks in the Shiwandashan basin and its adjacent area, southern China, has been qualitatively and semi-quantitatively studied. The results reflect several features of the thermal history. Firstly, all the samples have experienced temperatures higher than 60-70 ℃. Secondly, the time that the basement strata (T1b) on the northwestern side of the Shiwandashan basin were uplifted and exhumed to the unannealed upper crust (with a paleogeotemperature of below 60-70 ℃) is much earlier than the basement rocks (γ15) on the southeastern side of the basin. Thirdly, the thermal history of samples from the basin can be divided into six stages, I.e., the fast burial and heating stage (220-145 Ma), the transient cooling stage (145-135 Ma), the burial and heating stage (135-70 Ma), the rapid cooling stage (70-50 Ma), the relatively stable stage (50-20 Ma) and another rapid cooling stage (20 Ma to present).

  4. Efficacy of three different regimens of primaquine for the prevention of relapses of Plasmodium vivax malaria in the Amazon Basin of Peru.

    Science.gov (United States)

    Durand, Salomón; Cabezas, Cesar; Lescano, Andres G; Galvez, Mariela; Gutierrez, Sonia; Arrospide, Nancy; Alvarez, Carlos; Santolalla, Meddly L; Bacon, David J; Graf, Paul C F

    2014-07-01

    We evaluated the efficacy of three primaquine (PQ) regimes to prevent relapses with Plasmodium vivax through an open-label randomized trial in Loreto, Peru. Vivax monoinfections were treated with chloroquine for 3 days and PQ in three different regimes: 0.5 mg/kg per day for 5 days (150 mg total), 0.5 mg/kg per day for 7 days (210 mg total), or 0.25 mg/kg per day for 14 days (210 mg total). Biweekly fever assessments and bimonthly thick smears were taken for 210 days. Recurrences after 35 days were considered relapses. One hundred eighty cases were enrolled in each group; 90% of cases completed follow-up. There were no group-related differences in age, sex, or parasitemia. Relapse rates were similar in the 7- and 14-day regimes (16/156 = 10.3% and 22/162 = 13.6%, P = 0.361) and higher in the 5-day group (48/169 = 28.4%, P < 0.001 and P = 0.001, respectively). The 7-day PQ regimen used in Peru is as efficacious as the recommended 14-day regimen and superior to 5 treatment days.

  5. Geologic Controls of Hydrocarbon Occurrence in the Appalachian Basin in Eastern Tennessee, Southwestern Virginia, Eastern Kentucky, and Southern West Virginia

    Energy Technology Data Exchange (ETDEWEB)

    Hatcher, Robert D

    2005-11-30

    This report summarizes the accomplishments of a three-year program to investigate the geologic controls of hydrocarbon occurrence in the southern Appalachian basin in eastern Tennessee, southwestern Virginia, eastern Kentucky, and southern West Virginia. The project: (1) employed the petroleum system approach to understand the geologic controls of hydrocarbons; (2) attempted to characterize the P-T parameters driving petroleum evolution; (3) attempted to obtain more quantitative definitions of reservoir architecture and identify new traps; (4) is worked with USGS and industry partners to develop new play concepts and geophysical log standards for subsurface correlation; and (5) geochemically characterized the hydrocarbons (cooperatively with USGS). Third-year results include: All project milestones have been met and addressed. We also have disseminated this research and related information through presentations at professional meetings, convening a major workshop in August 2003, and the publication of results. Our work in geophysical log correlation in the Middle Ordovician units is bearing fruit in recognition that the criteria developed locally in Tennessee and southern Kentucky are more extendible than anticipated earlier. We have identified a major 60 mi-long structure in the western part of the Valley and Ridge thrust belt that has been successfully tested by a local independent and is now producing commercial amounts of hydrocarbons. If this structure is productive along strike, it will be one of the largest producing structures in the Appalachians. We are completing a more quantitative structural reconstruction of the Valley and Ridge and Cumberland Plateau than has been made before. This should yield major dividends in future exploration in the southern Appalachian basin. Our work in mapping, retrodeformation, and modeling of the Sevier basin is a major component of the understanding of the Ordovician petroleum system in this region. Prior to our

  6. Preliminary seismicity and focal mechanisms for the southern Great Basin of Nevada and California: January 1992 through September 1992

    Energy Technology Data Exchange (ETDEWEB)

    Harmsen, S.C.

    1994-06-01

    The telemetered southern Great Basin seismic network (SGBSN) is operated for the Department of Energy`s Yucca Mountain Project (YMP). The US Geological Survey, Branch of Earthquake and Landslide Hazards, maintained this network until September 30, 1992, at which time all operational and analysis responsibilities were transferred to the University of Nevada at Reno Seismological Laboratory (UNRSL). This report contains preliminary earthquake and chemical explosion hypocenter listings and preliminary earthquake focal mechanism solutions for USGS/SGBSN data for the period January 1, 1992 through September 30, 1992, 15:00 UTC.

  7. Endemic Venezuelan equine encephalitis in northern Peru.

    Science.gov (United States)

    Aguilar, Patricia V; Greene, Ivorlyne P; Coffey, Lark L; Medina, Gladys; Moncayo, Abelardo C; Anishchenko, Michael; Ludwig, George V; Turell, Michael J; O'Guinn, Monica L; Lee, John; Tesh, Robert B; Watts, Douglas M; Russell, Kevin L; Hice, Christine; Yanoviak, Stephen; Morrison, Amy C; Klein, Terry A; Dohm, David J; Guzman, Hilda; Travassos da Rosa, Amelia P A; Guevara, Carolina; Kochel, Tadeusz; Olson, James; Cabezas, Cesar; Weaver, Scott C

    2004-05-01

    Since Venezuelan equine encephalitis virus (VEEV) was isolated in Peru in 1942, >70 isolates have been obtained from mosquitoes, humans, and sylvatic mammals primarily in the Amazon region. To investigate genetic relationships among the Peru VEEV isolates and between the Peru isolates and other VEEV strains, a fragment of the PE2 gene was amplified and analyzed by single-stranded conformation polymorphism. Representatives of seven genotypes underwent sequencing and phylogenetic analysis. The results identified four VEE complex lineages that cocirculate in the Amazon region: subtypes ID (Panama and Colombia/Venezuela genotypes), IIIC, and a new, proposed subtype IIID, which was isolated from a febrile human, mosquitoes, and spiny rats. Both ID lineages and the IIID subtype are associated with febrile human illness. Most of the subtype ID isolates belonged to the Panama genotype, but the Colombia/Venezuela genotype, which is phylogenetically related to epizootic strains, also continues to circulate in the Amazon basin.

  8. IRETHERM: Geophysical modeling of the southern margin of the Dublin Basin

    Science.gov (United States)

    Vozar, J.; Jones, A. G.; Llovet, J. C.; Pasquali, R.

    2014-12-01

    Multi-dimensional magnetotelluric (MT) modelling of data collected in the Newcastle area are presented in the frame of the IRETHERM project. The Newcastle area, situated on the southern margin of the Dublin Basin, exhibits elevated geothermal gradient (>30 °C/km) in the exploratory boreholes drilled by GT Energy. The MT soundings were carried out in the highly urbanized Dublin suburb and are heavily noise-contaminated and distorted due to EM noise from nearby industry and the DC tram system. Processing the "quietest" 4-hour night time subsets of data using several robust codes and the ELICIT method we obtained reliable and interpretable MT impedance and geomagnetic transfer functions at most sites. Tensor decomposition was applied at each site to ascertain if the data are suitable for 2D modelling and to determine the appropriate geoelectric strike direction. The final 2-D models underwent examination using a new stability technique, and the final two 2-D profiles with reliability estimations, expressed through conductance and resistivity, were derived. 3-D models of all MT data in the Newcastle area have also been determined. The 3-D models exhibit higher conductive structures in comparison to the 2-D models, with similarly resistive background rocks. The shallow conductive structures, to the depth of 1 km, have north-south elongation correlated with surface traces of faults, which are perpendicular to the regional Blackrock to Newcastle Fault (BNF). Deeper structures become more oriented to regional geoelectric strike similar to 2-D regional strike. The 2-D and 3-D modeling reveal that the BNF is imaged as a conductive zone to depths of 4 km and is likely highly fractured. Generally, the area south of the BNF is more resistive and compact with a horizontal conductive layer at approximately 1 km depth and with a very thin surficial sedimentary layer. In contrast, the structures north of the BNF are more heterogeneous, with deeper conductive layers (2-3 km depth

  9. Extreme precipitation and extreme streamflow in the Dongjiang River Basin in southern China

    Directory of Open Access Journals (Sweden)

    W. Wang

    2007-07-01

    Full Text Available Extreme hydro-meteorological events have become the focus of more and more studies in the last decade. Due to the complexity of the spatial pattern of changes in precipitation processes, it is still hard to establish a clear view of how precipitation has changed and how it will change in the future. In the present study, changes in extreme precipitation and streamflow processes in the Dongjiang River Basin in southern China are investigated. It was shown that little change is observed in annual extreme precipitation in terms of various indices, but some significant changes are found in the precipitation processes on a monthly basis. The result indicates that when detecting climate changes, besides annual indices, seasonal variations in extreme events should be considered as well. Despite of little change in annual extreme precipitation series, significant changes are detected in several annual extreme flood flow and low-flow series, mainly at the stations along the main channel of Dongjiang River, which are affected significantly by the operation of several major reservoirs. The result highlights the importance of evaluating the impacts of human activities in assessing the changes of extreme streamflows. In addition, three non-parametric methods that are not-commonly used by hydro-meteorology community, i.e., Kolmogorov–Smirnov test, Levene's test and quantile test, are introduced and assessed by Monte Carlo simulation in the present study to test for changes in the distribution, variance and the shift of tails of different groups of dataset. Monte Carlo simulation result shows that, while all three methods work well for detecting changes in two groups of data with large data size (e.g., over 200 points in each group and big difference in distribution parameters (e.g., over 100% increase of scale parameter in Gamma distribution, none of them are powerful enough for small data sets (e.g., less than 100 points and small distribution

  10. Cenomanian-Turonian facies succession in the Guerrero-Morelos Basin, Southern Mexico

    Science.gov (United States)

    Aguilera-Franco, Noemí; Hernández Romano, Ulises

    2004-09-01

    The Cenomanian-Turonian succession of southern Mexico is characterized by an abrupt change from shallow marine to pelagic facies. The drowning of the platform coincides with the widely documented Cenomanian-Turonian Oceanic Anoxic Event (CTOAE). A proper understanding of the drowning event and the effects of the OAE requires, as an essential first step, the construction of a detailed stratigraphic framework. This has been achieved and utilizes sedimentological data as well as a combination of benthic and planktonic biostratigraphic schemes. Deposition of the Cenomanian-Turonian sedimentary rocks of the Guerrero-Morelos basin was controlled by tectonic and oceanographic factors resulting in depositional environments ranging from a semi-restricted shelf, ramp, pelagic and prodelta deposits. Facies analysis indicates that shallow marine limestones of the Morelos Formation (lower-upper Cenomanian) were deposited in intertidal-shallow supratidal and subtidal environments in a semi-restricted shelf. Peloidal-bioclastic packstone-wackestones with minor grainstones are the predominant texture of these rocks. Abundant large benthic foraminifers, calcareous algae (dasycladacean) and mollusks (gastropods and rudists) characterize the fossil assemblage. The Cuautla Formation (uppermost Cenomanian-Turonian) represents sedimentation on a low-energy, wave-dominated, carbonate ramp. The inner ramp accumulated bioclastic banks and shoals composed of peloidal-benthic foraminifer-grainstone, calcareous red and green algae, rudists and minor solitary corals. The middle ramp is represented by nodular packstones with a diverse assemblage of echinoderms, green and red algae, bryozoan, rudists, solitary corals, roveacrinids, calcisphaerulids, and non-keeled planktonic foraminifers. The outer ramp is dominated by argillaceous wackestone-packstone characterized by calcisphaerulids, roveacrinids, and non-keeled planktonic foraminifers. An increase in terrigenous-clastic material towards the

  11. Tectonomagmatic relationship between the Sierra Madre Occidental ignimbrite flare-up and the southern Basin and Range province

    Science.gov (United States)

    Aguirre-Diaz, G. J.; Labarthe-Hernandez, G.

    2004-12-01

    The Sierra Madre Occidental (SMO) is a Mid-Tertiary, large-volume, ignimbrite province at least 1,200 km long and 200-500 km wide, extending continuously from the U.S.-Mexico border (31\\deg N) to its intersection with the Mexican Volcanic Belt (21\\deg N). Considering the average thickness of 1,000 m for the ignimbrite plateau, based on several measured sections along the province, and the average wide of the province of 300 km, a conservative estimate of the physical volume of the SMO ignimbrites is about 360,000 km3. The southern part of the Basin and Range province is in Mexico. This extensional province overlaps in space and time with the SMO ignimbrite flare-up and formed NW- to NE-trending normal faults that bound many large grabens, which are particularly long and deep in the southern SMO. Basin and Range faulting occurred between at least 32 Ma and 12 Ma with both limits probably extending until the Eocene and the Quaternary. Ignimbrite activity can be as old as 51 Ma and as young as 17-16 Ma, but most of the ignimbrite volume was erupted in the 38-23 Ma period. Thus, the ignimbrite flare-up can be defined as a period of intense explosive volcanic activity that produced enormous volumes of silicic ignimbrite sheets, which took place mainly between 38 and 23 Ma in Mexico. The ignimbrite flare-up coincided in time with peaks in Basin and Range faulting, and the ignimbrite activity apparently migrated from the east-northeast to the west-southwest, i.e., from central Chihuahua (38-27 Ma) to Durango-Tayoltita-Nazas (32-29 Ma) to Zacatecas-Tepic (24-23 Ma), finishing by 16 Ma at Jalisco-Nayarit, as deduced from the compilation of geologic works done in the SMO. It is unknown yet whether there was a west-southward migration of Basin and Range faulting and if the ignimbrite flare-up occurred episodically as peaks (38-27 Ma, 32-29 Ma, and 24-23 Ma) or was continuous. Nevertheless, by the time that the ignimbrite flare-up started, the Basin and Range extension was

  12. Peru : Opportunities for All, Peru Poverty Assessment

    OpenAIRE

    World Bank

    2005-01-01

    Peru faces high levels of poverty and inequality. In 2004, over half of Peru's population was poor and about 20 percent were extremely poor. Following improvements during the 1990s, poverty increased in the wake of the 1998 economic crisis, while extreme poverty remained stable. Notwithstanding the economic recovery since 2001, with a strong positive impact in reducing extreme poverty, progress on poverty rates however, has been limited to rural areas. A main focus of this report is to explai...

  13. Extension of geographic distribution of Chrysobrycon hesperus and C. myersi (Characiformes, Characidae, Stevardiinae for several drainages flowing into the Amazon River Basin in Peru and Colombia Extensión de la distribución geográfica de Chrysobrycon hesperus y C. myersi (Characiformes, Characidae, Stevardiinae para varios drenajes fluyendo hacia la cuenca del Amazonas en Perú y Colombia

    Directory of Open Access Journals (Sweden)

    James Anyelo Vanegas-Ríos

    2013-03-01

    Full Text Available The geographic distribution of Chrysobrycon hesperus (Böhlke and C. myersi Weitzman and Menezes is extended to new localities from the upper Amazon Basin in Peru and Colombia. Chrysobrycon hesperus is recorded for the first time for the Putumayo River Basin in Colombia.Se amplía la distribución geográfica de Chrysobrycon hesperus (Böhlke y C. myersi Weitzman y Menezes para nuevas localidades de la cuenca alta del Amazonas en Perú y Colombia. Chrysobrycon hesperus se registra por primera vez para la cuenca del río Putumayo en Colombia.

  14. Basin Evolution and Exhumation of the Xigaze Forearc, Southern Tibet: Insight from Sedimentology, Stratigraphy, and Geo-Thermochronology

    Science.gov (United States)

    Orme, D. A.; Carrapa, B.; Abbey, A. L.; Kapp, P. A.; Ding, L.

    2012-12-01

    Forearc basins are important data archives for understanding continental dynamics because they preserve the tectono-erosional record of continental margins before collision. This study focuses on the Cretaceous-Eocene Xigaze forearc basin in southern Tibet, which is exposed along ~600 km of the Indus-Yarlung Suture Zone between the Indian craton to the south and the Asian Lhasa terrane to the north. From late Cretaceous to early Cenozoic time, subduction of Neo-Tethyan oceanic crust beneath the southern margin of Asia accommodated the northward motion of the Indian craton and formed the Xigaze forearc basin. Following collision with India in the early Cenozoic, the basin transitioned from predominantly marine to non-marine sedimentation and was subsequently uplifted to a mean elevation of 5000 m. How this transition occurred remains unresolved. This study's overall objective is to decipher forearc-basin and Indo-Asia continental-margin development from field sedimentology and stratigraphy, and detrital geo-thermochronology. We present new stratigraphic sections, totaling 8 km thick, from a previously unexplored ~60 km segment of the Xigaze forearc, ~50 km north-northwest of Saga. These sections are quite different from those known farther east. Sedimentary facies of mid-Cretaceous to early Eocene deposits indicate a shoaling-upward trend consistent with other ancient forearc basins (e.g., Great Valley forearc, California). Middle to late Cretaceous deposits indicate a variety of facies and depositional environments along strike in the study area. Facies include distal marine turbidites, shelf limestones, estuarine siliciclastics, and brown paleosols. In contrast, Eocene depositional environments are transitional from nearshore marine to pericontinental. Facies consist of dirty limestones, packstones, and wackestones, interbedded with terrigenous conglomerates and red-green paleosols. Eocene fauna include abundant foraminifera such as Nummulites-Discocyclina and

  15. Geologic Controls of Hydrocarbon Occurrence in the Southern Appalachian Basin in Eastern Tennessee, Southwestern Virginia, Eastern Kentucky, and Southern West Virginia

    Energy Technology Data Exchange (ETDEWEB)

    Robert D. Hatcher

    2003-05-31

    This report summarizes the first-year accomplishments of a three-year program to investigate the geologic controls of hydrocarbon occurrence in the southern Appalachian basin in eastern Tennessee, southwestern Virginia, eastern Kentucky, and southern West Virginia. The project: (1) employs the petroleum system approach to understand the geologic controls of hydrocarbons; (2) attempts to characterize the T-P parameters driving petroleum evolution; (3) attempts to obtain more quantitative definitions of reservoir architecture and identify new traps; (4) is working with USGS and industry partners to develop new play concepts and geophysical log standards for subsurface correlation; and (5) is geochemically characterizing the hydrocarbons (cooperatively with USGS). First-year results include: (1) meeting specific milestones (determination of thrust movement vectors, fracture analysis, and communicating results at professional meetings and through publication). All milestones were met. Movement vectors for Valley and Ridge thrusts were confirmed to be west-directed and derived from pushing by the Blue Ridge thrust sheet, and fan about the Tennessee salient. Fracture systems developed during Paleozoic, Mesozoic, and Cenozoic to Holocene compressional and extensional tectonic events, and are more intense near faults. Presentations of first-year results were made at the Tennessee Oil and Gas Association meeting (invited) in June, 2003, at a workshop in August 2003 on geophysical logs in Ordovician rocks, and at the Eastern Section AAPG meeting in September 2003. Papers on thrust tectonics and a major prospect discovered during the first year are in press in an AAPG Memoir and published in the July 28, 2003, issue of the Oil and Gas Journal. (2) collaboration with industry and USGS partners. Several Middle Ordovician black shale samples were sent to USGS for organic carbon analysis. Mississippian and Middle Ordovician rock samples were collected by John Repetski (USGS) and

  16. Discriminant analysis for characterization of hydrochemistry of two mountain river basins of contrasting climates in the southern Western Ghats, India.

    Science.gov (United States)

    Thomas, Jobin; Joseph, Sabu; Thrivikramji, K P

    2015-06-01

    Discriminant analysis (DA) was performed on river hydrochemistry data for three seasons (i.e., monsoon (MON), post-monsoon (POM), and pre-monsoon (PRM)) to examine the spatio-temporal hydrochemical variability of two mountain river basins (Muthirapuzha River Basin (MRB) and Pambar River Basin (PRB)) of the southern Western Ghats, India. Although the river basins drain tropical mountainous terrain, climate and degree of anthropogenic disturbances show significant differences (i.e., humid, more disturbed MRB vs semiarid, less disturbed PRB). In MRB, TDS, Na(+), pH, Mg(2+), and K(+) are the attributes responsible for significant hydrochemical variations between the seasons, while Cl(-), TH, and Na(+) are the predictors in PRB. The temporal discriminant models imply the importance of rainfall pattern, relative contribution of groundwater toward stream discharge and farming activities in hydrochemistry between the seasons. Inclusion of hydrochemical attributes (in the temporal discriminant functions) that can be derived from both natural and anthropogenic sources suggests that ionic enrichment strongly depends on the seasons, and is mainly due to the variability in the intensity of anthropogenic activities as well as fluctuations in river discharge. In spatial discriminant models, Cl(-) is the only variable responsible for hydrochemical variations between the basins (during MON), whereas Si discriminates during POM and PRM, implying the role of atmospheric supply, anthropogenic modifications as well as intensity of weathering. In the spatial discrimination models, misclassification of hydrochemistry data between MRB and PRB can be attributed to the overlapping effect of humid climate of MRB extending toward the upstream of (semiarid) PRB. This study underscores the versatility of DA in deciphering the significance of climatic controls on hydrochemical composition of tropical mountain rivers.

  17. Paleocene deep-water sediments and radiolarian faunas:Implications for evolution of Yarlung-Zangbo foreland basin, southern Tibet

    Institute of Scientific and Technical Information of China (English)

    丁林

    2003-01-01

    This is the first report on the Paleocene deep-water sequences and radiolarian faunas, which are distributed along the southern side of the Yarlung-Zangbo suture zone. The Zheba group is coined to indicate these Paleocene sequences which are subsequently divided into two lithostratigraphic units based on the lithology observed in the field. The lower unit characterized by the rhythmic cherts and siliceous shales is named the Sangdanlin formation, and the upper one composed mainly of flysches is termed the Zheya formation. The radiolarian faunas from the Zheba group are assigned to the RP1-RP6 zones of the Paleocene age. The Early Paleocene ra-diolarian assemblages have the potential to be established into the low latitude radiolarian zones and to fill in the gap between the Late Cretaceous and the Late Paleocene radiolarian zonations. The radiolarian dating provides a valuable tool for the regional correlation and reconstruction of the sedimentary environment of the Neo-Tethyan Ocean. The preliminary work shows that the Paleo-cene sequences accumulated in a foreland basin resulted from the southern Asian margin loading onto the northern Indian passive continental margin. The Yarlung-Zangbo foreland basin se-quences deposited on the Indian passive continental margin also resulted in many good source- reservoir-covering assemblages for oil and gas resources.

  18. A contribution of hydrogenotrophic methanogenesis to the biogenic coal bed methane reserves of Southern Qinshui Basin, China.

    Science.gov (United States)

    Guo, Hongguang; Yu, Zhisheng; Thompson, Ian P; Zhang, Hongxun

    2014-11-01

    The activity of methanogens and related bacteria which inhabit the coal beds is essential for stimulating new biogenic coal bed methane (CBM) production from the coal matrix. In this study, the microbial community structure and methanogenesis were investigated in Southern Qinshui Basin in China, and the composition and stable isotopic ratios of CBM were also determined. Although geochemical analysis suggested a mainly thermogenic origin for CBM, the microbial community structure and activities strongly implied the presence of methanogens in situ. 454 pyrosequencing analysis combined with methyl coenzyme-M reductase (mcrA) gene clone library analysis revealed that the archaeal communities in the water samples from both coal seams were similar, with the dominance of hydrogenotrophic methanogen Methanobacterium. The activity and potential of these populations to produce methane were confirmed by the observation of methane production in enrichments supplemented with H2 + CO2 and formate, and the only archaea successfully propagated in the tested water samples was from the genus Methanobacterium. 454 pyrosequencing analysis also recovered the diverse bacterial communities in the water samples, which have the potential to play a role in the coal biodegradation fueling methanogens. These results suggest that the biogenic CBM was generated by coal degradation via the hydrogenotrophic methanogens and related bacteria, which also contribute to the huge CBM reserves in Southern Qinshui Basin, China.

  19. The Mean Residence Time (MRT) of exfiltrating groundwater in the Southern Vienna Basin (Fischa-Dagnitz spring area)

    Science.gov (United States)

    Wyhlidal, Stefan; Rank, Dieter; Schuster, Katharina; Jung, Martin

    2013-04-01

    The "Mitterndorfer Senke" in the youngest zone of subsidence in the Southern Vienna Basin contains an important groundwater body used by regional water-supply facilities. The depression is filled with Pleistocene gravels and sands and is about 40 km long, up to 8 km wide and 50 to 150 m deep. Up to 13 m3/s of river water infiltrate in the alluvial cones in the most southern part of the "Mitterndorfer Senke" by the crossing rivers. The contribution of local precipitation to groundwater recharge is very low due to high evaporation in this area (up to 500 mm/a) compared with to an mean annual precipitation amount about of 500 mm/a in the southern Vienna basin. This sedimentary filling in the "Senke" acts very much like a pipeline, transmitting water readily from the main recharge area south-west of Wiener Neustadt to locations of surface discharge in the northern part of the basin. For many years a plume of chlorinated hydrocarbons has been moving from the industrial plants in the most southern part of the depression towards the Danube. In this context the determination of the groundwater flow velocity in the depression became important. The Fischa-Dagnitz spring is situated in a distance of some 20 km from the infiltration section and discharges about 350 l/s. A long-term environmental isotope monitoring record from 1964 - 2012 exists for this spring. The result of the evaluation of ³H time series using the dispersion model leads to a mean residence time between 13.5-16.5 years for the base flow of the Fischa-Dagnitz spring. This corresponds to previous studies, however, the present results are based on a more complete data set and therefore they are more significant. There is also evidence of occasional short-term influences of storm waters in the Fischa-Dagnitz spring. Normally these effects may be neglected. The difference between the δ18O values of precipitation of Gloggnitz (altitude 512 m) and the Fischa-Dagnitz spring leads to the conclusion, that the

  20. Influenza-Like Illness Sentinel Surveillance in Peru

    Science.gov (United States)

    2009-07-01

    Nacional de San Agustı́n, Arequipa , Peru, 6 Universidad Nacional de Ucayali, Pucallpa, Peru, 7 Dirección Regional de Salud de Puno, Ministerio de Salud...country. The sites included in this study were from 1) the southern highlands, including Arequipa , Cusco, Puno and Juliaca, all located over 2,500 meters...noted if the patient spent at least one night in the hospital or health center. Study participants from Sullana, Arequipa , Puno, Pucallpa and Iquitos

  1. Chemical characteristics of Central Indian Basin waters during the southern summer

    Digital Repository Service at National Institute of Oceanography (India)

    DeSousa, S.N.; Sardessai, S.; RameshBabu, V.; Murty, V.S.N.; Gupta, G.V.M.

    Chemical properties of the water column were examined at the Indian Deep-sea Environment Experiment (INDEX) site in the Central Indian Basin (CIB), as a part of baseline studies prior to the benthic disturbance experiment for the environmental...

  2. Middle-late Holocene climate variability in La Paz Basin, southern Gulf of California

    Science.gov (United States)

    Gómez-Lizárraga, L. E.; Perez-Cruz, L. L.; Fucugauchi, J. U.

    2013-12-01

    Sediments from DIPAL III-K47 core collected at 830 m depth in the western slope within the oxygen minimum zone of La Paz Basin, southern Gulf of California provide a detailed record of paleoceanography and paleoclimatology for the tropical Pacific on centennial time scales for the past 7300 years. The sedimentary sequence is compose of hemipelagic sediments and is laminated throughout its entire length (145 cm). According to the preliminary age model based on radiocarbon AMS dates, core covers the period from ca 7300 to 1000 cal yr BP. The estimated sedimentation rates are between 0.20 and 0.29 mm/yr. Radiolarian assemblages, geochemical (major and trace elements Al, Ba, Ca, K, Si Ti, Zr and Zr/Al and Ba/Al ratios) and magnetic susceptibility are used as proxies of variations of oceanic circulation patterns, paleoproductivity, aeolian activity and precipitation. Eighty-two intervals were sampled for radiolarians and the core was sampled at 1-cm intervals to produce records of major and trace elements. Factor Analysis of the radiolarian abundances counted in sediments samples identified three assemblages. The first one (Arachnocorallium calvata, Lithomelissa setosa, Lithomelissa thoracites and Peridium longispinum) suggests winter-spring like conditions (cold and dry), Gulf of California Water persistence and a relative increase in productivity that might become from the east-to-west upwelling gradient. The second radiolarian assemblage (Tetrapyle octacantha group and Phorticium pylonium group) was interpreted as stratification of the column water and the incursion of warm, oligotrophic Tropical Surface Water that remind summer-fall like conditions. The third assemblage (Clathrocircus stapedius, Phorticium pylonium group, Lithomelissa pentacantha, Phormacantha hystrix, Phormospyris stabilis scaphipes, Lithomelissa thoracites, Pseudocubus obeliscus, Druppatractus irregularis and Druppatractus variabilis), suggests a mix water column that favors the organic carbon

  3. IRETHERM: Multidimensional geophysical modeling of the southern margin of the Dublin Basin

    Science.gov (United States)

    Vozar, Jan; Jones, Alan G.; Rath, Volker; Campanya, Joan; Pasquali, Riccardo

    2015-04-01

    Multi-dimensional magnetotelluric (MT) modelling of data from the Newcastle area west of Dublin, acquired as part of the geothermal potential of Ireland (IRETHERM) project, is presented. The Newcastle area, situated on the southern margin of the Carboniferous Dublin Basin, exhibits elevated geothermal gradient (>30 ° C/km) in the exploratory boreholes drilled by GT Energy. The MT soundings were carried out in the highly urbanized Dublin suburb and are heavily noise-contaminated and distorted due to EM noise from nearby industry and the DC tram system (LUAS). We obtained reliable and interpretable MT impedance and geomagnetic transfer functions at most sites by processing the 'quietest' 4-hour night time subsets of data using several robust codes and the ELICIT method. Tensor decomposition was applied at each site to ascertain if the data are suitable for 2-D modelling and to determine the appropriate geoelectric strike direction. The obtained 2-D models underwent examination using a new stability technique, and the final two 2-D profiles with reliability estimations, expressed through conductance and resistivity, were derived. 3-D models, including all usable MT data in the Newcastle area, have also been determined with and without resistivity constrains for shallow structures from resistivity measurements in one of the boreholes (borehole NGE1). The 3-D models exhibit structures with higher conductivity in comparison to the 2-D models, with similarly resistive background rocks. The shallow conductive structures, to a depth of 1 km, have north-south elongations correlated with the surface traces of faults that are perpendicular to the regional Blackrock to Newcastle Fault (BNF). Deeper structures become more oriented to a regional geoelectric strike similar to 2-D regional strike. To obtain superior characterization of the thermal transport properties of the investigated area, we used porosity and resistivity data from borehole NGE1 to estimate relation between

  4. Field detection of eastern equine encephalitis virus in the Amazon Basin region of Peru using reverse transcription-polymerase chain reaction adapted for field identification of arthropod-borne pathogens.

    Science.gov (United States)

    O'Guinn, Monica L; Lee, John S; Kondig, John P; Fernandez, Roberto; Carbajal, Faustino

    2004-02-01

    In support of efforts to develop rapid diagnostic assays for use in the field, reverse transcription-polymerase chain reaction (RT-PCR) assays were developed to detect arboviruses circulating in the Amazon Basin region of Peru. Previous knowledge of arthropod/pathogen relationships allowed a focused evaluation to be conducted in November 2000 that assessed the feasibility and reliability of a mobile, rapid, field-expedient RT-PCR diagnostic system aimed at detecting eastern equine encephalitis virus (EEEV) in Culex (Melanoconion) pedroi mosquitoes. Modifications were made to a commercially available mobile molecular laboratory kit and assay procedures were tailored for use under harsh environmental conditions with field-collected and field-processed mosquitoes. From CO2 baited mosquito light traps, 3,227 Cx. (Mel.) pedroi mosquitoes were collected and sorted into 117 pools. The pools were processed and assayed in the field by RT-PCR and five of those pools were found positive for EEEV. Laboratory sequence analysis confirmed the presence of two distinct subtypes of EEEV.

  5. Peru, People and Plants.

    Science.gov (United States)

    Thompson, Dennis

    Designed for horticulture, horticulture therapy, and botany students at Edmonds Community College (Washington), this 6-hour module explores the pre-Columbian use of plant materials in Peru and its relationships to cultural practices in modern Peru. The first sections provide basic information about the module, such as its objectives, the concepts…

  6. A new species of Andean frog of the genus Bryophryne from southern Peru Anura: Craugastoridae) and its phylogenetic position, with notes on the diversity of the genus.

    Science.gov (United States)

    Chaparro, Juan C; Padial, José M; Gutiérrez, Roberto C; De La Riva, Ignacio

    2015-07-30

    We describe a new species of terrestrial frog of the genus Bryophryne (Anura: Craugastoridae) from the wet puna and elfin forests of the Amazonian versant of the Andes. The new species seems to be restricted to high altitude environments at elevations between 3506-3651 m in the area now protected by Megantoni National Sanctuary and Manu National Park (Distrito de Echarate, Provincia La Convención, Departamento Cusco, Peru). The new species is characterized by lacking vomerine processes of vomers, by having tympanic annulus and tympanic membrane not evident through the skin, smooth dorsal skin with scattered warts, conspicuous dorsolateral, middorsal, and occipital folds, warty flanks, areolate skin on ventral surfaces of the body, and by lacking finger and toe fringes and basal web on feet. In life, specimens have bright and highly variable dorsal coloration that ranges from olive-green to red with variable combinations of red or orange marks (red or orange in the green form and olive-green in the red form). Molecular phylogenetic analyses of mitochondrial and nuclear DNA place the new species within the genus Bryophryne and as sister group of B. cophites. Bryophryne bustamantei, also sequenced for this study, is found as the sister group of the clade formed by B. cophites and the new species. Bryophryne is found as sister group of Psychrophrynella in maximum likelihood analyses and as the sister group of a large clade of holoadenines in parsimony analyses. The genus Bryophryne now contains nine species, all of them distributed along the Cordillera Oriental of the Peruvian Andes, southeast of the Apurimac River valley.

  7. A preliminary investigation of the structure of southern Yucca Flat, Massachusetts Mountain, and CP basin, Nevada Test Site, Nevada, based on geophysical modeling.

    Energy Technology Data Exchange (ETDEWEB)

    Geoffrey A. Phelps; Leigh Justet; Barry C. Moring, and Carter W. Roberts

    2006-03-17

    New gravity and magnetic data collected in the vicinity of Massachusetts Mountain and CP basin (Nevada Test Site, NV) provides a more complex view of the structural relationships present in the vicinity of CP basin than previous geologic models, helps define the position and extent of structures in southern Yucca Flat and CP basin, and better constrains the configuration of the basement structure separating CP basin and Frenchman Flat. The density and gravity modeling indicates that CP basin is a shallow, oval-shaped basin which trends north-northeast and contains ~800 m of basin-filling rocks and sediment at its deepest point in the northeast. CP basin is separated from the deeper Frenchman Flat basin by a subsurface ridge that may represent a Tertiary erosion surface at the top of the Paleozoic strata. The magnetic modeling indicates that the Cane Spring fault appears to merge with faults in northwest Massachusetts Mountain, rather than cut through to Yucca Flat basin and that the basin is downed-dropped relative to Massachusetts Mountain. The magnetic modeling indicates volcanic units within Yucca Flat basin are down-dropped on the west and supports the interpretations of Phelps and KcKee (1999). The magnetic data indicate that the only faults that appear to be through-going from Yucca Flat into either Frenchman Flat or CP basin are the faults that bound the CP hogback. In general, the north-trending faults present along the length of Yucca Flat bend, merge, and disappear before reaching CP hogback and Massachusetts Mountain or French Peak.

  8. Main Structural Styles and Deformation Mechanisms in the Northern Sichuan Basin, Southern China

    Institute of Scientific and Technical Information of China (English)

    TANG Liangjie; GUO Tonglou; JIN Wenzheng; YU Yixin; LI Rufeng

    2008-01-01

    The Triassic Jialingjiang Formation and Leikoupo Formation are characterized by thick salt layers. Three tectono-stratigraphic sequences can be identified according to detachment layers of Lower-Middle Triassic salt beds in the northern Sichuan Basin, i.e. the sub-salt sequence composed of Sinian to the Lower Triassic Feixianguan Formation, the salt sequence of the Lower Triassic Jialingjiang Formation and Mid-Triassic Leikoupou Formation, and the supra-salt sequence composed of continental clastics of the Upper-Triassic Xujiahe Formation, Jurassic and Cretaceous. A series of specific structural styles, such as intensively deformed belt of basement-involved imbricated thrust belt, basement-involved and salt-detached superimposed deformed belt, buried salt-related detached belt, duplex, piling triangle zone and pop-up, developed in the northern Sichuan Basin. The relatively thin salt beds, associated with the structural deformation of the northern Sichuan Basin, might act as a large decollement layer. The deformation mechanisms in the northern Sichuan Basin included regional compression and shortening, plastic flow and detachment, tectonic upwelling and erosion, gravitational sliding and spreading. The source rocks in the northern Sichuan Basin are strata underlying the salt layer, such as the Cambrian, Silurian and Permian. The structural deformation related to the Triassic salt controlled the styles of traps for hydrocarbon. The formation and development of hydrocarbon traps in the northern Sichuan Basin might have a bearing upon the Lower-Middle Triassic salt sequences which were favorable to the hydrocarbon accumulation and preservation. The salt layers in the Lower-Middle Triassic formed the main cap rocks and are favorable for the accumulation and preservation of hydrocarbon.

  9. Palaeotopography-governed sediment distribution—a new predictive model for the Permian Upper Rotliegend in the Dutch sector of the Southern Permian Basin

    NARCIS (Netherlands)

    Mijnlieff, H.F.; Geluk, M.

    2011-01-01

    The Southern Permian Basin (SPB) formed a large, elongated saucer-shaped inland depression extending from the UK to Poland and from Belgium to Denmark. During the Middle to early Late Permian the SPB was filled progressively by playa sediments from its centre in northwestern Germany before it was fl

  10. Late Pleistocene evolution of the Rhine-Meuse system in the southern North Sea basin: imprints of climate change, sea-level oscillation and glacio-isostacy

    NARCIS (Netherlands)

    Busschers, F.S.; Kasse, C.; Balen, R.T. van; Berghe, J. van den; Cohen, K.M.; Weerts, H.J.T.; Wallinga, J.; Johns, C.; Cleveringa, P.; Bunnik, F.P.M.

    2007-01-01

    High-resolution continuous core material, geophysical measurements, and hundreds of archived core descriptions enabled to identify 13 Late Pleistocene Rhine-Meuse sedimentary units in the infill of the southern part of the North Sea basin (the Netherlands, northwestern Europe). This sediment record

  11. Late Pleistocene evolution of the Rhine in the southern North-Sea Basin: imprints of climate change, sea-level oscillations and glacio-isostacy

    NARCIS (Netherlands)

    Busschers, F.S.; Kasse, C.; van Balen, R.T.; Vandenberghe, J.; Cohen, K.M.; Weerts, H.J.T.; Wallinga, J.

    2007-01-01

    High-resolution continuous core material, geophysical measurements, and hundreds of archived core descriptions enabled to identify 13 Late Pleistocene Rhine-Meuse sedimentary units in the infill of the southern part of the North Sea basin (the Netherlands, northwestern Europe). This sediment record

  12. Fluvial evolution of the Rhine during the last interglacial-glacial cycle in the southern North Sea basin: A review and look forward

    NARCIS (Netherlands)

    Peeters, J.; Busschers, F.S.; Stouthamer, E.

    2015-01-01

    This paper presents the current state of knowledge on the evolution and depositional history of the River Rhine in the southern part of the North Sea basin during the upper Middle and Late Pleistocene, and its response to climate change, sea-level oscillation and glacio-isostasy. The study focuses o

  13. Field relationships and petrographic evidence of magma mingling and mixing processes in the Arequipa Segment of the Coastal Batholith in Southern Peru

    Science.gov (United States)

    Martinez, A. M.; Clausen, B. L.; Gonzalez, L. U.; Poma, O.

    2013-12-01

    The Cretaceous plutonic rocks of the Arequipa segment in the Coastal Batholith of Peru provide an interesting natural laboratory to study evidence for magma mingling and mixing at outcrop or map scale (mainly mingling) and at thin-section or crystal scale (mingling and mixing) through the integration of fieldwork and petrographic analysis. These plutonic rocks display an important record of field and petrographic evidence for mingling and mixing processes involving the interaction of felsic and mafic magmas taking place within active magma chambers in continental arc settings. The research area in the Arequipa segment near Ica is approximately 60 km wide area and is divided into four super-units younging from west to east: Linga, Pampahausi, Tiabaya, and Incahuasi. The plutonic rocks are made up of several intrusions of diorites, quartz diorites, tonalites, quartz monzodiorites, quartz monzonites, granodiorites, and granites. The transects chosen to develop a detailed and systematic sampling of the early gabbros and the four super-units were selected on the degree of accessibility and outcrop exposure. These six transects are along the river canyons: Rio Pisco, Seco, Ica, Curis, Tingo, and Grande. From field evidence, the best areas for identifying of mingling textures correspond to Rio Pisco, Ica, Tingo, and Grande. Mingling features that preserve a record of magma interaction styles observed at the outcrop level in these transects are: abundant alkali feldspar megacrysts, dikes, interfingering, flow bands, enclaves, mafic sheets, and stoping. The largest number of mingling features from fieldwork are found in the Pampahuasi, Tiabaya, and Incahuasi super-units. From petrographic analysis, a variety of important microtextures indicating magma mixing and mingling processes were also identified such as: calcic zones in plagioclase, contact melting, sieve texture, truncating zoning, poikilitic quartz and feldspar, ocellar texture, porphyritic texture, and acicular

  14. Tomographic imaging of the effects of Peruvian flat slab subduction on the Nazca slab and surrounding mantle under central and southern Peru

    Science.gov (United States)

    Scire, A. C.; Zandt, G.; Beck, S. L.; Bishop, B.; Biryol, C. B.; Wagner, L. S.; Long, M. D.; Minaya, E.; Tavera, H.

    2014-12-01

    The modern central Peruvian Andes are dominated by a laterally extensive region of flat slab subduction. The Peruvian flat slab extends for ~1500 km along the strike of the Andes, correlating with the subduction of the Nazca Ridge in the south and the theorized Inca Plateau in the north. We have used data from the CAUGHT and PULSE experiments for finite frequency teleseismic P- and S-wave tomography to image the Nazca slab in the upper mantle below 95 km depth under central Peru between 10°S and 18°S as well as the surrounding mantle. Since the slab inboard of the subducting Nazca Ridge is mostly aseismic, our results provide important constraints on the geometry of the subducting Nazca slab in this region. Our images of the Nazca slab suggest that steepening of the slab inboard of the subducting Nazca Ridge locally occurs ~100 km further inland than was indicated in previous studies. The region where we have imaged the steepening of the Nazca slab inboard of the Nazca Ridge correlates with the location of the Fitzcarrald Arch, a long wavelength upper plate topographic feature which has been suggested to be a consequence of ridge subduction. When the slab steepens inboard of the flat slab region, it does so at a very steep (~70°) angle. The transition from the Peruvian flat slab to the more normally dipping slab south of 16°S below Bolivia is characterized by an abrupt bending of the slab anomaly in the mantle in response to the shift from flat to normal subduction. The slab anomaly appears to be intact south of the Nazca Ridge with no evidence for tearing of the slab in response to the abrupt change in slab dip. A potential tear in the slab is inferred from an observed offset in the slab anomaly north of the Nazca Ridge extending subparallel to the ridge axis between 130 and 300 km depth. A high amplitude (-5-6%) slow S-wave velocity anomaly is observed below the projection of the Nazca Ridge. This anomaly appears to be laterally confined to the mantle

  15. Modelling pH, alkalinity and runoff in a lakeless forested basin in southern Finland

    Energy Technology Data Exchange (ETDEWEB)

    Lepistoe, A.; Jaervi, T.; Seuna, P.

    1987-01-01

    The Swedish PULSE model, with the HBV model as the hydrological part, has been used for simulation of the pH and alkalinity of runoff. In Sweden the model has been applied with good results to forested basins that have lakes. In the present study the model was applied to a forested basin without lakes, in order to test its suitability in this case. The model was calibrated to a small (0.69 km{sup 2}) basin using a 12-year time period (1972-83;R{sup 2}=0.80 for runoff). Verification was carried out with data of the intensively monitored years 1984-85 (R{sup 2}=0.84 for runoff, R{sup 2}=0.71 for pH). The results show that the PULSE model can also be applied satisfactorily to basins without lakes. The simulation provides reference values fo use in destinguishing long term changes in the runoff water quality from natural short-term variations. 5 figures, 10 references. (author).

  16. Lithostratigraphy, depositional history and sea level changes of the Cauvery Basin, southern India

    Directory of Open Access Journals (Sweden)

    Muthuvairvasamy Ramkumar

    2003-01-01

    Full Text Available The sedimentary sequence exposed in the erstwhile Tiruchirapalli district hosts a more or less complete geological record of the Upper Cretaceous-Tertiary period. Systematic field mapping, collation of data on the micro-meso scale lithology, sedimentary structures, petrography, faunal assemblage and facies relationships of these rocks, in the light of modern stratigraphic concepts, helped to enumerate the lithostratigraphic setup and depositional history of the basin. Spatial and temporal variations of the lithologies and revised stratigraphic units are presented in this paper. Many high frequency sea level cycles (presumably fourth or higher order which stack up to form third order sea level cycles (six in number, which in turn form part of second order cycles (two in number, including seven eustatic sea level peaks, have been recorded in this basin. Trend analysis of sea level curves indicates a gradual increase of the sea level from Barremian to Coniacian and a gradual decrease from Coniacian to Danian. Such lasting sea level trends had their influence on the sedimentation pattern and facies association. It is inferred that depositional bathymetry was maintained at a shallow-moderate level, primarily influenced by a lack of major subsidence during the depositional history of this basin. The study also revealed a prevalent simple basin filling process and dominant control by sea level changes, rather than tectonic movements over the depositional regime.

  17. Coricladus quiteriensis gen. et sp. nov., a new conifer in Southern-Brazil Gondwana (Lower Permian, Paraná Basin

    Directory of Open Access Journals (Sweden)

    Jasper André

    2005-01-01

    Full Text Available A new taxon of conifers (Coricladus quiteriensis is described based on megafloristic remains from the roofshale level at the Quitéria Outcrop (Rio Bonito Formation - Lower Permian - Southern Paraná Basin - Rio Grande do Sul - Brazil. This megafloristic community is included in the Botrychiopsis Zone - Botrychiopsis valida Sub-Zone (Kungurian/Roadian. The assemblage, preserved as impressions, do not present remains of epidermic characters, and is composed mainly of isolated vegetative branches with spirally disposed acicular leaves, presenting a conspicuous central vein and also isolated fertile branches with sparse and irregular leaves and terminal cones. Leafless principal branches, organically connected with sterile and fertile branches, are rare. Reproductive feminine scales, disposed in a plane, are organized in lax terminal cones on branches, composed by 4 (four distal ovuliferous scales, and 8 (eight elliptical-elongated anatropous seeds. Paleoecological data pointed out to a mesophylous to higrophylous habitat in swampy environments.

  18. Petrogenesis of Mesoproterozoic lamproite dykes from the Garledinne (Banganapalle) cluster, south-western Cuddapah Basin, southern India

    Science.gov (United States)

    Rao, N. V. Chalapathi; Atiullah; Kumar, Alok; Sahoo, Samarendra; Nanda, Purnendu; Chahong, Ngazimpi; Lehmann, B.; Rao, K. V. S.

    2016-04-01

    We report mineral chemistry and whole-rock major and trace-element geochemistry for a recent find of Mesoproterozoic (~1.4 Ga) lamproites from the Garledinne (Banganapalle) cluster, south-western part of the Paleo-Mesoproterozoic Cuddapah Basin, southern India. The Garledinne lamproites occur as WNW-ESE-trending dykes that have undergone varying degree of pervasive silicification and carbonate alteration. Nevertheless, their overall texture and relict mineralogy remain intact and provide important insights into the nature of their magmas. The lamproite dykes have porphyritic to weakly porphyritic textures comprising pseudomorphed olivine macrocrysts and microphenocrysts, titanian phlogopite microphenocrysts, spinel having a compositional range from chromite to rarely magnesiochromite, Sr-rich apatite and niobian rutile. The Garledinne and other Cuddapah Basin lamproites (Chelima and Zangamarajupalle) collectively lack sanidine, clinopyroxene, potassic richterite, and titanite and are thus mineralogically distinct from the nearby Mesoproterozoic lamproites (Krishna and Ramadugu) in the Eastern Dharwar Craton, southern India. The strong correlation between various major and trace elements coupled with high abundances of incompatible and compatible trace elements imply that alteration and crustal contamination have had a limited effect on the whole-rock geochemistry (apart from K2O and CaO) of the Garledinne lamproites and that olivine fractionation played an important role in their evolution. The Garledinne lamproites represent small-degree partial melts derived from a refractory (previously melt extracted) peridotitic mantle source that was subsequently metasomatised (enriched) by carbonate-rich fluids/melts within the garnet stability field. The involvement of multiple reservoirs (sub-continental lithospheric mantle and asthenosphere) has been inferred in their genesis. The emplacement of the Garledinne lamproites is linked to extensional events, across the various

  19. New constraints on the geometry and evolution of the Southern San Andreas Fault and Salton Pull-apart basin

    Science.gov (United States)

    Sahakian, V. J.; Holmes, J. J.; Kell, A. M.; Harding, A. J.; Driscoll, N. W.; Kent, G.

    2013-12-01

    In the recent geologic past, the Salton pull-apart basin, northern Imperial Fault (IF) and Southern San Andreas Fault (SSAF) have been part of an evolving tectonic regime, subject to strain partitioning. This part of the North American/Pacific plate boundary has the potential for generating a large earthquake. Several lines of active-source seismic reflection and refraction data in the Salton Sea were analyzed to better understand the fault interactions and evolution in this region by investigating the SSAF geometry, stratigraphy, and velocity structure. These data, collected in conjunction with the Salton Seismic Imaging Project (SSIP) include two fault-perpendicular lines: one adjacent to the southern terminus of the SSAF (Line 7), and one just south of the terminus (Line 8). We present results from Multi Channel Seismic (MCS) data along Line 7, and refraction data along Lines 7 and 8. Velocity models along these lines were constructed from the refraction data. Included in the Line 7 model is an interface representing a strong reflector observed in the MCS data, which helps to constrain the raypaths and velocities in the model. Line 7 MCS data image stratigraphic layers thickening to and dipping down to the east towards the SSAF, indicative of a westward-dipping, oblique strike-slip fault. The refraction data along this line are consistent with a westward dipping SSAF and a down the west normal component. We present velocity models for Line 7 and 8, as well as resolution tests supporting the fault's geometry. The results from these two lines and a fault parallel line suggest that the SSAF is dipping to the west and is in transtension. We propose that the SSAF has migrated northward through time, partitioning its strain onto the IF. As the IF migrates northwards it forms the Salton pull-apart basin.

  20. CENOZOIC BASIN-CONTROLLING FAULTS AND THEIR BEARING ON BASIN GROUPS FORMAION IN THE SOUTHERN SOUTH CHINA SEA%南海南部新生代控盆断裂特征及盆地群成因

    Institute of Scientific and Technical Information of China (English)

    熊莉娟; 马云; 王霄飞; 李三忠; 索艳慧; 刘鑫; 余珊; 程世秀; 薛友辰; 安慧婷; 戴黎明

    2012-01-01

    There are many small and medium-sized Cenozoic sedimentary basins in the southern South China Sea, such as the Nanweixi Basin, the Beikang Basin, the Liyue Basin, the Zengmu Basin, the Nansha Trough, the Brunei-Sabah Basin, the Northwest Palawan Basin and other basins from north to south. In general, NE-trending faults control the formation of the half grabens with faulting in the north and overlapping in the south. However, single grabens are mainly developed in the northern continental slope, while two-layered basins developed in the south of the region, of which the lower layer is the graben and the upper layer the imbricated nappes. According to the nature of main controlling faults and the transition of the basins at different evolutionary stages, these basins can be divided into three groups: the rift basin group (the Nanweixi, Beikang and Liyue basins), the rift-pull-apart-foreland superimposed basin group (the Zengmu basin) and the rift-foreland basin group (the Nansha Trough, Brunei-Sabah, the Northwest Palawan basins). The formation of these basin groups is closely related to major marginal faults of the basins and secondary faults in the sub-basins. Based on the nature of the faults, the basin-controlling fault belts can be subdivided into three types: tensile, shear and compressional, including the extensional fault belt in the northern edge of the Nansha Trough, the strike-slip fault belts at the west edge of the Wanan Basin and the Lupar and the Tingjia-Lee Jun Fault belts, and the thrust fault belt in the southern edge of the Nansha Trough. Tectonic events which happened in southern South China Sea, such as the South China Sea Movement in Oligocene and the Nansha Movement in the Middle Miocene, affected the basins to various degrees. As the result, there was the inversion from a rift basin/pull-apart basin to a marine foreland basin, as well as the inversion of fault belts from normal faults to reverse faults or strike-slip faults. The kinetic

  1. Decline of General Intelligence in Children Exposed to Manganese from Mining Contamination in Puyango River Basin, Southern Ecuador.

    Science.gov (United States)

    Betancourt, Óscar; Tapia, Marlene; Méndez, Ignacio

    2015-09-01

    Based on ecosystem approaches to health (Ecohealth), this study sought to identify neurobehavioral disorders in children exposed to several levels of toxic metal pollution from gold mining in the Puyango River Basin, Southern Ecuador. Ninety-three children born or living in the study area participated in the study. A neurobehavioral test battery consisting of 12 tests assessing various functions of the nervous system was applied as well as a questionnaire regarding events of exposure of children's mothers to contaminants during perinatal period. Hair samples were taken from children to determine manganese concentrations. Descriptive and inferential statistics were applied in order to examine possible relationships between exposure events, hair manganese, and neurobehavioral disorders. Having controlled co-variables such as age and educational level, it was found that children with elevated levels of hair manganese (over 2 μg/g) had poor performance in the test of general intelligence (Raven's Progressive Color Matrices Scale PCM). The Ecohealth approach helped to identify that children in the lower Puyango Basin with very elevated levels of manganese in the river water (970 µg/L) are the ones who have the highest levels of hair manganese and the worst performance in the intelligence test.

  2. Intrusion versus inversion—a 3D density model of the southern rim of the Northwest German Basin

    Science.gov (United States)

    Bilgili, Filiz; Götze, Hans-Jürgen; Pašteka, Roman; Schmidt, Sabine; Hackney, Ron

    2009-04-01

    An unsolved problem of regional importance for both the evolution and structure of the Northwest German Basin is the existence or non-existence of the so-called Bramsche Massif. Explaining the nature of this massif and the cause of a related strong, positive Bouguer anomaly (Bramsche Anomaly) is critical. In the study described here, we tested an existing “intrusion model” against a newer “inversion model” in the southern Northwest German Basin. In the intrusion model, the strongly-positive Bouguer anomaly represents the gravity effect of an intrusion at depths between 6 and 10 km. More recent interpretations invoke tectonic inversion rather than intrusion to explain increased burial and the low level of hydrocarbon maturity found in boreholes. We tested these different interpretations by constructing 3D forward density models to 15 km depth. The intrusion model was updated and adjusted to incorporate recent data and we also modelled pre-Zechstein structures using different scenarios. The final model has a very good fit between measured and modelled gravity fields. Based on currently available seismic and structural models, as well as borehole density measurements, we show that the positive Bouguer anomaly cannot be modeled without a high-density, intrusive-like body at depth. However, further in-sight into the crustal structures of the Bramsche region requires more detailed investigations.

  3. Diversity and biogeography of bacterial assemblages in surface sediments across the San Pedro Basin, Southern California Borderlands.

    Science.gov (United States)

    Hewson, Ian; Jacobson Meyers, Myrna E; Fuhrman, Jed A

    2007-04-01

    Sediment bacteria play important roles in the biogeochemistry of ocean sediments; however, factors influencing assemblage composition have not been extensively studied. We examined extractable sediment bacterial abundance, the composition of bacterial assemblages using a high-throughput molecular fingerprinting approach, and several sediment biogeochemical parameters (organic matter content and alkaline phosphatase activity), along a 35 km transect from Point Fermin, Southern California, to Santa Catalina Island, across the approximately 900-m-deep San Pedro Basin. Automated rRNA intergenic spacer analysis (ARISA) demonstrated that in two spatially isolated shallow (approximately < 60 m, on opposite sides of the channel) sediment environments, assemblages were more similar to each other than to deeper communities. Distinct communities existed in deeper and shallower sediments, and stations within the deep basin over 2 km apart contained remarkably similar assemblage fingerprints. The relative contribution to total amplified DNA fluorescence of operational taxonomic units (OTUs) was significantly correlated to that of other OTUs in few comparisons (2.7% of total), i.e. few bacterial types were found together or apart consistently. The relative proportions within assemblages of only a few OTU were significantly correlated to measured physicochemical parameters (organic matter content and wet/dry weight ratio of sediments) or enzyme (alkaline phosphatase) activities. A low percentage of shared OTU between shallow and deep sediments, and the presence of similar, but spatially isolated assemblages suggests that bacterial OTU may be widely dispersed over scales of a few kilometres, but that environmental conditions select for particular assemblages.

  4. Earthquake engineering in Peru

    Science.gov (United States)

    Vargas, N.J

    1983-01-01

    During the last decade, earthquake engineering research in Peru has been carried out at the Catholic University of Peru and at the Universidad Nacional de Ingeniera (UNI). The Geophysical Institute (IGP) under the auspices of the Organization of American States (OAS) has initiated in Peru other efforts in regional seismic hazard assessment programs with direct impact to the earthquake engineering program. Further details on these programs have been reported by L. Ocola in the Earthquake Information Bulletin, January-February 1982, vol. 14, no. 1, pp. 33-38. 

  5. Arsenic concentrations in soils and sediments of the southern Pampean Plain, within Claromecó River Basin (Argentina)

    Science.gov (United States)

    Sosa, N. N.; Datta, S.; Zarate, M.

    2015-12-01

    The Pampean plain is an extensive flatland covering ~1000000 km2 of central and northern Argentina. The region, dominated by Neogene and quaternary volcanoclastic loess and loess-like deposits, shows one of the highest groundwater As concentrations of the world which cause serious problems to human health. The oxidising and high pH conditions of the Pampean groundwater leads to the dissolution of volcanic glass and Fe oxy-hydroxides and the release of As to water. Variation of As content related to lithogenic factors is evident from our study in Claromecó River Basin (Southern Pampean plain): the Mio-Pliocene fluvial facies (MPFF) show low As content (2.6mg/kg) compared to the Late Pleistocene fluvial facies (11.6mg/kg; LPFF). Furthermore, the pedogenic calcrete and the paleosols developed in fluvial facies present significantly different As content: 3.9 mg/Kg in MPFF pedogenic calcrete and 16.5 mg/Kg in LPFF paleosols. Modern soils show the highest As content, especially in the illuvial horizons (23.3 mg/Kg) controlled by grain size and clay mineralogy constituents. Preliminary results demonstrate a sedimentological control embarking differences in As concentrations. These differences are probably attributed to a major hydraulic gradient during the MPFF, which is reflected in grain size and in fluvial structures, which probably was followed by washed out sediments. A geomorphological control was observed through an increase of As concentrations from the interfluves (MPFF) to the valleys (LPFF) as well as from the upper to the lower basin zone within the LPFF. Pedogenic calcrete and paleosols developed in MPFF and LPFF respectively reflect the different geomorphological conditions showing high As content in LPFF paleosols (attributed to Fe oxy-hydroxides). This study relates mineralogy and sedimentological environment to groundwater, surface water from wetlands to understand the hydrochemical processes in controlling As within the Claromecó basin.

  6. Holocene vegetation and climate history of the northern Bighorn Basin, southern Montana

    Science.gov (United States)

    Lyford, M.E.; Betancourt, J.L.; Jackson, S.T.

    2002-01-01

    Records of Holocene vegetation and climate change at low elevations (climate change from 55 14C-dated woodrat middens at two low-elevation sites (1275 to 1590 m, currently vegetated by Juniperus osteosperma woodlands, in the northern Bighorn Basin. Macrofossil and pollen analyses show that the early Holocene was cooler than today, with warming and drying in the middle Holocene. During the Holocene, boreal (Juniperus communis, J. horizontalis) and montane species (J. scopulorum) were replaced by a Great Basin species (J. osteosperma). J. osteosperma colonized the east side of the Pryor Mountains 4700 14C yr B.P. Downward movement of lower treeline indicates wetter conditions between 4400 and 2700 14C yr B.P. Increased aridity after 2700 14C yr B.P. initiated expansion of J. osteosperma from the east to west side of the Pryor Mountains. ?? 2002 University of Washington.

  7. Risk assessment of desertification using GIS in parts of Mond Basin, Southern Iran

    Energy Technology Data Exchange (ETDEWEB)

    Masoudi, M.; Asrari, E.

    2009-07-01

    The present paper attempts to evolve a new model by considering various indicators of different types of land degradation desertification, namely water erosion, soil salinity, vegetation degradation, and lowering of ground water table. the Mond river basin, located centrally to this zone, has been selected as a test area to assess the risk and kind of desertification. For this purpose two sub basins of the Payab and Quareh Aghaj have been chosen for detailed study. The thresholds for the severity classes of indicators have been established and then the hazards map for each indicator of types of desertification has been prepared in a GIS. The risk maps of water erosion, soil salinization, lowering of water table, vegetation degradation have been produced for each of the two sub basins. It was possible to distinguish the areas under actual risk from areas under potential risk of desertification types. Also areas under potential risk are classified to subclasses with different probability level to show a statistical picture of risk in future. (Author) 3 refs.

  8. Integrating facies and structural analyses with subsidence history in a Jurassic-Cretaceous intraplatform basin: Outcome for paleogeography of the Panormide Southern Tethyan margin (NW Sicily, Italy)

    Science.gov (United States)

    Basilone, Luca; Sulli, Attilio; Gasparo Morticelli, Maurizio

    2016-06-01

    We illustrate the tectono-sedimentary evolution of a Jurassic-Cretaceous intraplatform basin in a fold and thrust belt present setting (Cala Rossa basin). Detailed stratigraphy and facies analysis of Upper Triassic-Eocene successions outcropping in the Palermo Mts (NW Sicily), integrated with structural analysis, restoration and basin analysis, led to recognize and describe into the intraplatform basin the proximal and distal depositional areas respect to the bordered carbonate platform sectors. Carbonate platform was characterized by a rimmed reef growing with progradational trends towards the basin, as suggested by the several reworked shallow-water materials interlayered into the deep-water succession. More, the occurrence of thick resedimented breccia levels into the deep-water succession suggests the time and the characters of synsedimentary tectonics occurred during the Late Jurassic. The study sections, involved in the building processes of the Sicilian fold and thrust belt, were restored in order to obtain the original width of the Cala Rossa basin, useful to reconstruct the original geometries and opening mechanisms of the basin. Basin analysis allowed reconstructing the subsidence history of three sectors with different paleobathymetry, evidencing the role exerted by tectonics in the evolution of the narrow Cala Rossa basin. In our interpretation, a transtensional dextral Lower Jurassic fault system, WNW-ESE (present-day) oriented, has activated a wedge shaped pull-apart basin. In the frame of the geodynamic evolution of the Southern Tethyan rifted continental margin, the Cala Rossa basin could have been affected by Jurassic transtensional faults related to the lateral westward motion of Africa relative to Europe.

  9. Geogenic arsenic and other trace elements in the shallow hydrogeologic system of Southern Poopó Basin, Bolivian Altiplano.

    Science.gov (United States)

    Ormachea Muñoz, Mauricio; Wern, Hannes; Johnsson, Fredrick; Bhattacharya, Prosun; Sracek, Ondra; Thunvik, Roger; Quintanilla, Jorge; Bundschuh, Jochen

    2013-11-15

    Environmental settings in the southern area of Lake Poopó in the Bolivian highlands, the Altiplano, have generated elevated amounts of arsenic (As) in the water. The area is characterised by a semiarid climate, slow hydrological flow and geologic formations of predominantly volcanic origin. The present study aimed at mapping the extent of the water contamination in the area and to investigate the geogenic sources and processes involved in the release of As to the groundwater. Ground- and surface-water samples were collected from 24 different sites, including drinking water wells and rivers, in the southern Poopó basin in two different field campaigns during the dry and rainy seasons. The results revealed variable levels of As in shallow drinking water wells and average concentration exceeding the WHO guidelines value. Arsenic concentrations range from below 5.2 μg/L (the detection level) to 207 μg/L and averages 72 μg/L. Additionally, high boron (B) concentrations (average 1902 μg/L), and high salinity are further serious concerns for deteriorating the groundwater quality and rendering it unsuitable for drinking. Groundwater is predominantly of the Na-Cl-HCO3 type or the Ca-Na-HCO3 type with neutral or slightly alkaline pH and oxidising character. While farmers are seriously concerned about the water scarcity, and on a few occasions about salinity, there are no concerns about As and B present at levels exceeding the WHO guidelines, and causing negative long term effects on human health. Sediment samples from two soil profiles and a river bed along with fourteen rock samples were also collected and analysed. Sequential extractions of the sediments together with the calculation of the mineral saturation indices indicate that iron oxides and hydroxides are the important secondary minerals phases which are important adsorbents for As. High pH values, and the competition of As with HCO3 and dissolved silica for the adsorption sites probably seems to be an

  10. Geogenic arsenic and other trace elements in the shallow hydrogeologic system of Southern Poopó Basin, Bolivian Altiplano

    Energy Technology Data Exchange (ETDEWEB)

    Ormachea Muñoz, Mauricio, E-mail: ormachea@kth.se [KTH – International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm (Sweden); Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, 303, La Paz (Bolivia, Plurinational State of); Wern, Hannes; Johnsson, Fredrick; Bhattacharya, Prosun [KTH – International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm (Sweden); Sracek, Ondra [Department of Geology, Faculty of Science, Palacký University, 17. listopadu 12, 771 46 Olomouc (Czech Republic); Thunvik, Roger [KTH – International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm (Sweden); Quintanilla, Jorge [Laboratorio de Hidroquímica, Instituto de Investigaciones Químicas, Universidad Mayor de San Andrés, 303, La Paz (Bolivia, Plurinational State of); Bundschuh, Jochen [KTH – International Groundwater Arsenic Research Group, Division of Land and Water Resources Engineering, Department of Sustainable Development, Environmental Sciences and Engineering, Royal Institute of Technology (KTH), Teknikringen 76, SE-100 44 Stockholm (Sweden); Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba, Queensland 4350 (Australia)

    2013-11-15

    Highlights: • Groundwater used as drinking water has elevated concentrations of arsenic and boron. • Sediments are potential sources of arsenic and boron in shallow groundwater. • Fe-oxides and hydroxides are important absorbents of arsenic. • Multiple geochemical processes drive mobilisation of arsenic in groundwater. -- Abstract: Environmental settings in the southern area of Lake Poopó in the Bolivian highlands, the Altiplano, have generated elevated amounts of arsenic (As) in the water. The area is characterised by a semiarid climate, slow hydrological flow and geologic formations of predominantly volcanic origin. The present study aimed at mapping the extent of the water contamination in the area and to investigate the geogenic sources and processes involved in the release of As to the groundwater. Ground- and surface-water samples were collected from 24 different sites, including drinking water wells and rivers, in the southern Poopó basin in two different field campaigns during the dry and rainy seasons. The results revealed variable levels of As in shallow drinking water wells and average concentration exceeding the WHO guidelines value. Arsenic concentrations range from below 5.2 μg/L (the detection level) to 207 μg/L and averages 72 μg/L. Additionally, high boron (B) concentrations (average 1902 μg/L), and high salinity are further serious concerns for deteriorating the groundwater quality and rendering it unsuitable for drinking. Groundwater is predominantly of the Na–Cl–HCO{sub 3} type or the Ca–Na–HCO{sub 3} type with neutral or slightly alkaline pH and oxidising character. While farmers are seriously concerned about the water scarcity, and on a few occasions about salinity, there are no concerns about As and B present at levels exceeding the WHO guidelines, and causing negative long term effects on human health. Sediment samples from two soil profiles and a river bed along with fourteen rock samples were also collected and

  11. The Fischa-Dagnitz spring, Southern Vienna Basin: a multi tracer time series study re-assessing earlier conceptual assumptions.

    Science.gov (United States)

    Suckow, Axel; Gerber, Christoph; Kralik, Martin; Sültenfuss, Jürgen; Purtschert, Roland

    2013-04-01

    The gravel aquifer of the Southern Vienna Basin is a very important backup drinking water resource for the city of Vienna. A discharge location, the Fischa-Dagnitz spring in the Southern Vienna Basin, Austria, was re-investigated in 2011, five years after the gas exchange tracer test published in (Stolp et al., 2010), and sampled for stable isotopes 18O/2H, tritium, 3He, SF6 and 85Kr (Gerber et al., 2012). Additionally, new tritium time series data (Davis et al., 1967), previously not considered in Stolp et al. (2010), were included. These show a higher and earlier tritium peak of >300 TU in 1965 in the discharge of the Fischa-Dagnitz spring as compared to 221 TU in 1972 considered in Stolp et al. (2010). The new 3He, SF6 and 85Kr gas tracer data from 2011 confirm the earlier finding for 3He of Stolp et al. (2010) and indicate a more recent equilibration with the atmosphere than the water bound tracers 18O, 2H and tritium. A new modelling attempt using the Lumpy code (Suckow, 2012) confirmed the discrepancy between the tritium data and the gaseous tracers 3He, SF6 and 85Kr. No steady-state combination of local recharge (represented by an exponential model) and Schwarza river infiltration flowing through the gravel aquifer (represented by a parallel dispersion model) can equally well explain both the tritium time series and the gas tracer results. A revised conceptual model proposes that a pinching of the aquifer at unconformities in the gravel body or a fault zone known in the gravel body forces groundwater along the flow path closer to the surface and exposes it to the atmosphere. This would tend to reset the "dating" clock for the gaseous tracers 3He, SF6 and 85Kr, which can equilibrate quickly with the atmosphere, but not for tritium, which marks the transport behaviour of the water itself. These findings are of importance also for other multi-tracer assessments of groundwater movement in phreatic aquifer systems. References: Davis, G.H., Payne, B.R., Dincer, T

  12. EnviSAT ASAR Monitoring Of The Natural And Archaeological Landscape Of Nasca, Peru

    Science.gov (United States)

    Cigna, Francesca; Tapete, Deodato; Lasaponara, Rosa; Masini, Nicola

    2013-12-01

    We exploit the 4year-long archive of ENVISAT ASAR IS2 C-band imagery available through ESA Cat-1 project id.11073 over Nasca (Southern Peru), to reconstruct the temporal evolution of the Rio Grande drainage basin and its impacts on the natural and cultural heritage preserved within this region, well- known for the evidences of the ancient Paracas and Nasca Civilizations who flourished between the 4th century BC and the 6th century AD. Inferences about the recent changes of the cultural landscapes and the main landforms in 2003-2007 were retrieved based on SAR backscattering (σ0) time series. Ancient aqueduct systems (the so-called puquios) and the famous geoglyphs ('Nasca Lines') were detected, even at a medium-resolution scale provided by ENVISAT images.

  13. Introduction to selected references on fossil fuels of the central and southern Appalachian basin: Chapter H.1 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    Science.gov (United States)

    Ruppert, Leslie F.; Lentz, Erika E.; Tewalt, Susan J.; Román Colón, Yomayra A.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    The Appalachian basin contains abundant coal and petroleum resources that have been studied and extracted for at least 150 years. In this volume, U.S. Geological Survey (USGS) scientists describe the geologic framework and geochemical character of the fossil-fuel resources of the central and southern Appalachian basin. Separate subchapters (some previously published) contain geologic cross sections; seismic profiles; burial history models; assessments of Carboniferous coalbed methane and Devonian shale gas; distribution information for oil, gas, and coal fields; data on the geochemistry of natural gas and oil; and the fossil-fuel production history of the basin. Although each chapter and subchapter includes references cited, many historical or other important references on Appalachian basin and global fossil-fuel science were omitted because they were not directly applicable to the chapters.

  14. 1970 Huaraz, Peru Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 1970, an earthquake-induced rock and snow avalanche on Mt. Huascaran, Peru, buried the towns of Yungay and Ranrahirca. The magnitude 7.8 earthquake killed 66,794...

  15. Two new records of Fabiana stephanii Hunz. & Barboza (Solanaceae from Arequipa and Ayacucho (Peru

    Directory of Open Access Journals (Sweden)

    Eliana Linares Perea

    2016-08-01

    Full Text Available In this work, two new records of Fabiana stephanii Hunz. & Barboza for the flora of Southern Peru are reported, including taxonomical, biogeographical and phytosociological data on this species.

  16. Paleoceanographic Changes in the Lagonegro Basin (Southern Italy) during the Late Triassic Linked to Oceanic Rifting in the Western Tethyan Region

    Science.gov (United States)

    Casacci, M.; Algeo, T. J.; Bertinelli, A.; Rigo, M.

    2015-12-01

    The Lagonegro Basin was part of the southwestern branch of the western Tethys, an actively spreading young ocean during the Late Triassic (Ciarapica and Passeri, 2002, 2005). The sedimentary environment was a deepening-upward basin, bordered to the north by the Apenninic and Apulian carbonate platforms. Paleoseismic activity is evidenced by frequent debris flows on the basin margins (Passeri et al., 2005). The Lagonegro succession is characterized by Permian to Miocene formations deposited in shallow to deep basinal environments. The Upper Triassic is comprised of deep-marine sediments belonging to the Calcari con Selce ("Cherty Limestone") Formation of late Ladinian to late Norian-early Rhaetian age and the Scisti Silicei ("Siliceous Shale") Formation of late Norian-early Rhaetian to Late Jurassic age. The "Transitional Interval" between these two formations is gradational over a 20- to 40-m interval (Miconnet, 1983). The Transitional Interval was investigated in three sections (Pignola-Abriola, Monte Volturino, and Madonna del Sirino) in the Southern Apennines (southern Italy), representing a proximal-to-distal transect across the Lagonegro Basin. The transition from mainly calcareous to mainly siliceous sedimentation may have been influenced by rapid, post-rift subsidence of the Lagonegro Basin. It also coincided with a shift to warmer or more humid conditions around the Norian/Rhaetian boundary, as reflected in a pronounced increase in the chemical index of alteration (CIA), a weathering proxy (Young and Nesbitt, 1998). Redox proxies indicate mainly oxic conditions in the deep basin, although organic-rich shale beds are present at multiple levels in the otherwise organic-poor succession. The abruptness of the transitions between organic-poor and -rich sediment layers suggests major changes in paleoceanographic conditions, possibly related to switches from lagoonal circulation (linked to a net negative water balance) to estuarine circulation (linked to a net

  17. Imaging 2D structures by the CSAMT method: application to the Pantano di S. Gregorio Magno faulted basin (Southern Italy)

    Science.gov (United States)

    Troiano, Antonio; Di Giuseppe, Maria Giulia; Petrillo, Zaccaria; Patella, Domenico

    2009-06-01

    A controlled source audiofrequency magnetotelluric (CSAMT) survey has been undertaken in the Pantano di San Gregorio Magno faulted basin, an earthquake prone area of Southern Apennines in Italy. A dataset from 11 soundings, distributed along a nearly N-S 780 m long profile, was acquired in the basin's easternmost area, where the fewest data are available as to the faulting shallow features. A preliminary skew analysis allowed a prevailing 2D nature of the dataset to be ascertained. Then, using a single-site multi-frequency approach, Dantzig's simplex algorithm was introduced for the first time to estimate the CSAMT decomposition parameters. The simplex algorithm, freely available online, proved to be fast and efficient. By this approach, the TM and TE mode field diagrams were obtained and a N35°W ± 10° 2D strike mean direction was estimated along the profile, in substantial agreement with the fault traces within the basin. A 2D inversion of the apparent resistivity and phase curves at seven almost noise-free sites distributed along the central portion of the profile was finally elaborated, reinforced by a sensitivity analysis, which allowed the best resolved portion of the model to be imaged from the first few meters of depth down to a mean depth of 300 m b.g.l. From the inverted section, the following features have been outlined: (i) a cover layer with resistivity in the range 3-30 Ω m ascribed to the Quaternary lacustrine clayey deposits filling the basin, down to an average depth of about 35 m b.g.l., underlain by a structure with resistivity over 50 Ω m up to about 600 Ω m, ascribed to the Mesozoic carbonate bedrock; (ii) a system of two normal faults within the carbonate basement, extending down to the maximum best resolved depth of the order of 300 m b.g.l.; (iii) two wedge-shaped domains separating the opposite blocks of the faults with resistivity ranging between 30 Ω m and 50 Ω m and horizontal extent of the order of some tens of metres, likely

  18. Crustal shear velocity structure in the Southern Lau Basin constrained by seafloor compliance

    Science.gov (United States)

    Zha, Yang; Webb, Spahr C.

    2016-05-01

    Seafloor morphology and crustal structure vary significantly in the Lau back-arc basin, which contains regions of island arc formation, rifting, and seafloor spreading. We analyze seafloor compliance: deformation under long period ocean wave forcing, at 30 ocean bottom seismometers to constrain crustal shear wave velocity structure along and across the Eastern Lau Spreading Center (ELSC). Velocity models obtained through Monte Carlo inversion of compliance data show systematic variation of crustal structure in the basin. Sediment thicknesses range from zero thickness at the ridge axis to 1400 m near the volcanic arc. Sediment thickness increases faster to the east than to the west of the ELSC, suggesting a more abundant source of sediment near the active arc volcanoes. Along the ELSC, upper crustal velocities increase from the south to the north where the ridge has migrated farther away from the volcanic arc front. Along the axial ELSC, compliance analysis did not detect a crustal low-velocity body, indicating less melt in the ELSC crustal accretion zone compared to the fast spreading East Pacific Rise. Average upper crust shear velocities for the older ELSC crust produced when the ridge was near the volcanic arc are 0.5-0.8 km/s slower than crust produced at the present-day northern ELSC, consistent with a more porous extrusive layer. Crust in the western Lau Basin, which although thought to have been produced through extension and rifting of old arc crust, is found to have upper crustal velocities similar to older oceanic crust produced at the ELSC.

  19. Deformation mechanisms deduced from AMS data in the Jaca-Pamplona basin (southern Pyrenees)

    Science.gov (United States)

    Larrasoan˜a, J. C.; Pueyo-Morer, E. L.; Millán-Garrido, H.; Parés, J. M.; Del Valle, J.

    The first AMS data obtained in the Eocene marls and turbidites of the Jaca-Pamplona basin, and their interpretation in the local structural framework are presented. AMS data have proved to be excellent geometric indicators of microstructural features, as well as markers of the relative strain of rocks. The performed AMS analysis allowed to infer the strain of rocks, which is not possible by means of the classical structural methods, in areas where strata do not display any strain markers. Besides, the AMS data have been the sensitive enough to allow a preliminary estimation of the deformation mechanisms that ruled the structural configuration of the study area.

  20. Late triassic flora of the Partizanskaya River basin (Southern Primor'e)

    Science.gov (United States)

    Volynets, E. B.; Shorokhova, S. A.; Ge, Sun

    2008-02-01

    Flora from the lower Norian deposits of the Upper Triassic, which are exposed in the Partizanskaya River basin, has been studied in detail. A new Imalinovo floral assemblage is distinguished. As is established, its taxonomic composition is represented by abundant cycadophytes and conifers occurring in association with insignificant ferns and czekanowskialeans, rare horsetails, pteridosperms, and ginkgoaleans. The studied floral assemblage is compared with several floras of East Asia: the Mongugai flora of Primor'e, the Tianqiaoling flora of northeastern China, the Yamanoi and Nariwa floras of Japan.

  1. Groundwater quality in the shallow aquifers of the Tulare, Kaweah, and Tule Groundwater Basins and adjacent highlands areas, Southern San Joaquin Valley, California

    Science.gov (United States)

    Fram, Miranda S.

    2017-01-18

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. The shallow aquifers of the Tulare, Kaweah, and Tule groundwater basins and adjacent highlands areas of the southern San Joaquin Valley constitute one of the study units being evaluated.

  2. Tephrochronology of a 70 ka-long marine record in the Marsili Basin (southern Tyrrhenian Sea)

    Science.gov (United States)

    Tamburrino, S.; Insinga, D. D.; Pelosi, N.; Kissel, C.; Laj, C.; Capotondi, L.; Sprovieri, M.

    2016-11-01

    A sequence of tephra layers is studied in a 13.9 m-long deep-sea core (MD01-2474G) from the southern Tyrrhenian Sea. The chronology of the succession is provided by a high-resolution age-depth model based on isotope stratigraphy and AMS radiocarbon dating, which place the succession of events in a time interval spanning the last 70 ka. Based on a precise chronological framework and proximal-distal correlations, the Y-1, Y-6 and Y-7 main marker tephras were identified. Compositional data on fresh micro-pumice or glass shards of selected tephras were correlated with the coeval volcanic activity of Aeolian Arc (Vulcano and Salina), Mt. Etna, Phlegrean Fields Pantelleria and Ischia. The tephra sequence contains a number of deposits documenting recurrent activity on Vulcano Island at ca. 6.9 ka BP (MD3), ca. 16.7 ka BP (MD11), ca. 23.2 ka BP (MD14), ca. 29.6 ka BP (MD15), ca. 36.9 ka BP (MD22) and ca. 42.5 ka BP (MD27). The results presented in this study improve the southern Tyrrhenian Sea tephrostratigraphic framework and provide new insights into chemistry and dispersal area of Aeolian Arc pyroclastic deposits in this sector of the Central Mediterranean.

  3. Differentiating Tectonic and Anthropogenic Earthquakes in the Greater Los Angeles Basin, Southern California

    Science.gov (United States)

    Hauksson, E.; Goebel, T.; Cochran, E. S.; Ampuero, J. P.

    2014-12-01

    The 2014 flurry of moderate earthquakes in the Los Angeles region raised the concern if some of this or past seismicity was of anthropogenic origin as opposed to being caused by ongoing transpressional tectonics. The Mw5.1 La Habra sequence is located near several major oil fields but the Mw4.4 Encino sequence was located away from oil fields, within the Santa Monica Mountains. The last century of seismicity in the Los Angeles area consists of numerous small and large earthquakes. Most of these earthquakes occur beneath the basin sediments and are associated with transpressional tectonics, related to the big bend in the San Andreas fault, but some could be associated with large oil fields. In particular, both the 1933 Mw6.4 Long Beach and the 1987 Mw5.9 Whittier Narrows earthquakes were spatially associated with two major oil fields, the Huntington Beach and Montebello fields. Numerous large oil fields have been in production for more than 125 years. The geographical locations of the oil fields follow major tectonic trends such as the Newport-Inglewood fault, the Whittier fault, and the thrust belt located at the north edge of the Los Angeles basin. More than 60 fields have oil wells and some of these have both disposal and fracking wells. Before fluid injection became common, Kovach (1974) documented six damaging events induced by fluid extraction from 1947 to 1961 in the Wilmington oil field. Since 1981 the waveform-relocated earthquake catalog for the Los Angeles basin is complete on the average above M2.0. We compare the spatial distribution of these events and the proximity of nearby active oil fields. We will also analyze the seismicity in the context of available monthly fluid extraction and injection volumes and search for temporal correlations. The La Habra sequence apparently correlates with temporal changes in extraction and injection volumes in the Santa Fe Springs oil field but not with activities in other oil fields within closer spatial proximity.

  4. Using 10Be cosmogenic surface exposure dating to determine the evolution of the Purgatorio active fault in the Andean forearc, southern Peru

    Science.gov (United States)

    Carlos, Benavente; Swann, Zerathe; Laurence, Audin; Fabrizio, Delgado; Marianne, Saillard; Sarah, Hall R.; Aster Team

    2015-04-01

    Active transpressive deformation has been occurring along the Andean hyperarid forearc for the last 3 Myrs but many of these faults are still not described even if able to produce large damaging earthquakes. Active faulting along the northern part of the Arica Bend can be recognized due to the presence of well-preserved and sharp fault scarps indicating recent surface slip. During the Mio-Pliocene, deposition within the forearc continental basins resulted in the formation of vast fan deposits and conglomerates of the Moquegua Formation, which can be considered as bedrock in this exposure study (~45-4 Ma; Tosdal et al., 1984; Sebrier et al., 1988a; Roperch et al., 2006). The typical vertical Purgatorio fault scarps offset both the Moquegua bedrock and several younger geomorphic features associated with Moquegua formation outcroping vertically along the fault scarp. These samples are well-suited to the application of in situ produced cosmogenic radionuclides for surface exposure dating, as the hyperarid region has extremely low erosion rates. We sampled the scarp away from any significant drainage so as to avoid possibly disturbed areas. The sampling did involve extracting quarzite conglomeratic material along the bedrock scarp and on the upper surrounding crests. The aim has been to measure Berylium-20 TCN (Terrestrial in situ Cosmogenic Nuclides) concentrations to determine exposure age as a function of height on the scarp. This has been successfully employed on one scarp in Italy based on Chlorine-36 TCN (Palumbo et al., 2004). However, slow faults behaviour remains unclear and more contributions are needed. Quaternary activity of the Purgatorio fault system was evidenced by Hall et al. (2008). They highlighted a vertical offset of about ~100 m for a pediment surface intercepted by the fault, and dated at ~280 ka. Considering that the pediment surface is horizontal, this would gave a maximum of ~0.3 mm/yr of vertical deformation since 280 ka. Our new data provide

  5. Aminostratigraphy of Middle and Late Pleistocene deposits in The Netherlands and the southern part of the North Sea Basin

    Science.gov (United States)

    Meijer, T.; Cleveringa, P.

    2009-09-01

    A review of all available amino acid racemization D (alloisoleucine)/L (isoleucine) data from the whole shell of four molluscan species from Late and late Middle Pleistocene deposits of the Netherlands is presented. The data allow the distinction of 5 aminostratigraphical units, NAZ (Netherlands Amino Zone) A-E, each representing a temperate stage. The zones are correlated with marine isotope stages 1, 5e, 7, 9, and 11 respectively. Apart from NAZ-D (MIS 9), in all aminozones the marine transgression reached the present-day onshore area of the Netherlands. The transgression during NAZ-C (Oostermeer Interglacial: MIS 7) seems to be at least as widespread as its counterpart during NAZ-B (Eemian: MIS 5e) in the southern bight of the North Sea Basin. The stratigraphic position of the Oostermeer Interglacial is just below deposits of the Drente phase of the Saalian and because of this position the interglacial marine deposits have formerly erroneously considered to be of Holsteinian age. Neede, the 'classic' Dutch Holsteinian site, is dated in NAZ-E (MIS 11), like Noordbergum. Although the validity of these zones has been checked with independent data, some overlap between succeeding zones may occur. The relation between amino acid data from elsewhere in the North Sea Basin and the Netherlands amino zonation is discussed. The deposits at the Holsteinian stratotype Hummelsbüttel in North West Germany are dated in NAZ-D. This interglacial correlates with MIS 9. The Belvédère Interglacial, which is of importance for its archaeology, is in NAZ-D (MIS 9) and therefore of Holsteinian age as well. The lacustroglacial 'pottery clays' in the Noordbergum area are deposits from two glacial stages, which can be correlated with MIS 8 and 10 (the Elsterian). The pottery clay that is considered equivalent to the German 'Lauenburger Ton' correlates with MIS 10.

  6. Log evaluation of a coalbed methane (CBM) reservoir: a case study in the southern Qinshui basin, China

    Science.gov (United States)

    Jie, Hou; Changchun, Zou; Zhaohui, Huang; Liang, Xiao; Yuqing, Yang; Guohua, Zhang; Wenwen, Wang

    2014-02-01

    Proximate analysis components, gas content, porosity and permeability are the most important parameters for CBM reservoir evaluation. Based on the analysis of the conventional well log response of the no. 3 and no. 15 CBM seams in the southern Qinshui basin of China, regression analysis is used to establish the prediction models of the components of proximate analysis. The Langmuir rank equation is used to calculate the gas content. Variable matrix density is used to evaluate the total porosity. Based on the dual lateral log interaction method, a fracture porosity estimation model is established and the coal fracture permeability is predicted by using the Faivre-Sibbit method in the two CBM seams. Comparisons between the estimated and measured data of proximate analysis components, gas content, porosity and permeability indicate that the established models are credible. The absolute errors between the estimated moisture (Mad), ash (Aad), volatile (Vdaf), fixed carbon (FCad) and the measured results of coal in two coal seams are less than 0.41%, 9.47%, 3.61% and 9.41%, respectively. The absolute errors between the estimated and measured gas content are less than 4.05 cm3 g-1. The absolute errors of estimated total porosity and the analysed results of coal are less than 0.84%. Field samples show that Mad, Aad and Vdaf are less than 1.00%, 10.00%-25.00% and 10.00-15.00%, respectively, in the no. 3 and no. 15 CBM seams in the southern Qinshui basin. The FCad is close to 70.00%. The gas content ranges from 7.00 cm3 g-1 to 20.00 cm3 g-1 in the no. 3 coal seam and from 10.00 cm3 g-1 to 30.00 cm3 g-1 in the no. 15 coal seam. The total porosity is close to 5.50% and the fracture porosity is generally less than 2.50%. Fracture permeability is mainly distributed from 0.001 to 10 mD. The results indicate that the conventional well logs are effective in CBM reservoir evaluation.

  7. Seismic Data Interpretation: A Case Study of Southern Sindh Monocline, Lower Indus Basin, Pakistan

    Directory of Open Access Journals (Sweden)

    Shabeer Ahmed Abbasi

    2015-04-01

    Full Text Available The Sindh monocline in Lower Indus Basin is an important oil and gas producing area of Pakistan where a large number of oil, gas and condensate fields have been discovered from structural traps. This research involves the interpretation of stratigraphic and structural styles of Sindh Monocline using 2D (Two-Dimensional seismic reflection and well log. Four reflectors of different formations have been marked and were named as Reflector-1 as of Khadro Formation, Reflector-2 as Upper Goru Member, Reflector-3 as Lower Goru Formation and Reflector-4 as Chiltan Limestone. The average depth of Khadro Formation was marked at 449.0m, Upper Goru Member at 968m, Lower Goru Formation at 1938m and Chiltan Limestone at 2943m. Faults were marked on seismic sections which collectively form horsts and grabens which is the evidence of extensional tectonic in the area. Seismic interpretation was carried out through window based Kingdom Software

  8. The Aquatic And Marshy Flora Of The Lotru River Basin (Southern Carpathians, Romania

    Directory of Open Access Journals (Sweden)

    Drăgulescu Constantin

    2014-10-01

    Full Text Available The present paper continues the series of floristic inventories of the main Romanian rivers in the Carpathian Mountains (from which have been published those of Mureş, Sadu, Olt, Someş, Criş, Târnave, Tisa. In this work the author lists 204 plant taxa (hydrophilic, meso-hygrophilic and hygrophilic identified by the author or by other botanists in the Lotru Valley basin. Noted for each species were life form, floral element, ecological preferences for humidity (U, temperature (T, soil reaction (R, corology and coenology. Bibliographical sources are coded with numbers (see the references at the end of the paper. The sign “!” indicates that the author has seen the plant in that locality.

  9. Sod-podzolic soils with a complex organic profile of the southern Vyatka River basin

    Science.gov (United States)

    Prokashev, A. M.; Soboleva, E. S.; Chepurnov, R. R.; Matushkin, A. S.; Ohorzin, N. D.; Borodaty, I. L.; Zhuikova, I. A.; Alalykina, I. Y.; Russkikh, G. A.; Pupysheva, S. A.; Mokrushin, S. L.; Vartan, I. A.

    2016-08-01

    The article is devoted to the morphology and substantive properties of the sod- podzolic soils with a complex organic profile having the second humus horizons and found on the southern right bank of the lower Vyatka River. The research results of the mineral and organic phases are the evidence of the relict origin of the second humus horizon as well as the evidence of profile polygenicity of the given soils. They went through two fundamentally different pedogenesis stages during the postglacial period: 1) the developmental accumulative evolution stage in the first half of the Holocene and 2) the accumulative-eluvial stage of erasing evolution including the elements of inheriting evolution in the second half of the Holocene. Keywords: granulometric composition, fractional and group composition, humus age, genesis, soil evolution

  10. The 2001 - Present Triggered Seismicity Sequence in the Raton Basin of Southern Colorado/Northern New Mexico

    Science.gov (United States)

    Rubinstein, J. L.; Ellsworth, W. L.; McGarr, A.

    2012-12-01

    The occurrence of an earthquake of magnitude (M) 5.3 near Trinidad, CO, on 23 August 2011 renewed interest in the possibility that an earthquake sequence in this region that began in August 2001 is the result of industrial activities. Our investigation of this seismicity, in the Raton Basin of northern New Mexico and southern Colorado, led us to conclude that the majority, if not all of the earthquakes since August 2001 have been triggered by the deep injection of wastewater related to the production of natural gas from the coal-bed methane field here. The evidence that this earthquake sequence was triggered by wastewater injection is threefold. First, there was a marked increase in seismicity shortly after major fluid injection began in the Raton Basin. From 1970 through July of 2001, there were five earthquakes of magnitude 3 and larger located in the Raton Basin. In the subsequent 10 years from August of 2001 through the end of 2011, there were 95 earthquakes of magnitude 3 and larger. The statistical likelihood of this rate increase occurring naturally was determined to be 0.01%. Second, the vast majority of the seismicity is located close (within 5km) to active disposal wells in this region. Additionally, this seismicity is primarily shallow, ranging in depth between 2 and 8 km, with the shallowest seismicity occurring within 500 m depth of the injection intervals. Finally, these wells have injected exceptionally high volumes of wastewater. The 23 August 2011 M5.3 earthquake, located adjacent to two high-volume disposal wells, is the largest earthquake to date for which there is compelling evidence of triggering by fluid injection activities; indeed, these two nearly-co-located wells injected about 4.9 million cubic meters of wastewater during the period leading up to the M5.3 earthquake, more than 7 times as much as the disposal well at the Rocky Mountain Arsenal that caused damaging earthquakes in the Denver, CO, region in the 1960s. Much of the seismicity

  11. Simulation of Regional Ground-Water Flow in the Suwannee River Basin, Northern Florida and Southern Georgia

    Science.gov (United States)

    Planert, Michael

    2007-01-01

    The Suwannee River Basin covers a total of nearly 9,950 square miles in north-central Florida and southern Georgia. In Florida, the Suwannee River Basin accounts for 4,250 square miles of north-central Florida. Evaluating the impacts of increased development in the Suwannee River Basin requires a quantitative understanding of the boundary conditions, hydrogeologic framework and hydraulic properties of the Floridan aquifer system, and the dynamics of water exchanges between the Suwannee River and its tributaries and the Floridan aquifer system. Major rivers within the Suwannee River Basin are the Suwannee, Santa Fe, Alapaha, and Withlacoochee. Four rivers west of the Suwannee River are the Aucilla, the Econfina, the Fenholloway, and the Steinhatchee; all drain to the Gulf of Mexico. Perhaps the most notable aspect of the surface-water hydrology of the study area is that large areas east of the Suwannee River are devoid of channelized, surface drainage; consequently, most of the drainage occurs through the subsurface. The ground-water flow system underlying the study area plays a critical role in the overall hydrology of this region of Florida because of the dominance of subsurface drain-age, and because ground-water flow sustains the flow of the rivers and springs. Three principal hydrogeologic units are present in the study area: the surficial aquifer system, the intermediate aquifer system, and the Floridan aquifer system. The surficial aquifer system principally consists of unconsoli-dated to poorly indurated siliciclastic deposits. The intermediate aquifer system, which contains the intermediate confining unit, lies below the surficial aquifer system (where present), and generally consists of fine-grained, uncon-solidated deposits of quartz sand, silt, and clay with interbedded limestone of Miocene age. Regionally, the intermediate aquifer system and intermediate con-fining unit act as a confining unit that restricts the exchange of water between the over

  12. Andean shrublands of Moquegua, South Peru: Prepuna plant communities

    NARCIS (Netherlands)

    Montesinos, D.B.; Cleef, A.M.; Sykora, K.V.

    2012-01-01

    A syntaxonomic overview of shrubland vegetation in the southern Andean regions of Peru is presented. For each plant community, information is given on physiognomy, floristic diversity, ecology and geographical distribution. The shrub vegetation on the slopes of the upper Tambo river valley includes

  13. The Rise and Development of Sendero Luminoso in Peru

    Science.gov (United States)

    1992-03-27

    at the University of San Cristobal de Huamanga in Ayacucho in the southern sierra. He was described as "a theorist of the highest level" and a...Larmer. "Peru: Into the Cross-fire." Newsweek, 19 August 1991, pp. 29-30. Bourque, Susan C. and Kay B. Warren. "Democracy Without Peace: The Cultural

  14. Arenaria acaulis (Caryophyllaceae), a new species from South Peru

    NARCIS (Netherlands)

    Montesinos, D.B.; Kool, A.

    2015-01-01

    Abstract
    During studies on the flora of Moquegua (Southern Peru), some interesting Arenaria populations (subgen. Dicranilla, Caryophyllaceae)
    were found. The morphology of the plants does not resemble any other neotropical Arenaria species. The most
    similar species known so far is Arenar

  15. Peru v. Yale: A Battle Rages over Machu Picchu

    Science.gov (United States)

    Glenn, David

    2009-01-01

    In early 1916, the legendary Yale University archaeologist Hiram Bingham III completed his third and final expedition in southern Peru. He shipped home 74 boxes of artifacts from Machu Picchu, a spectacular site in the Andes that is believed to have been the last major settlement of the Inca empire. Those boxes were supposed to be on temporary…

  16. Serological evidence for Saint Louis encephalitis virus in free-ranging New World monkeys and horses within the upper Paraná River basin region, Southern Brazil

    OpenAIRE

    2014-01-01

    Introduction Saint Louis encephalitis virus (SLEV) primarily occurs in the Americas and produces disease predominantly in humans. This study investigated the serological presence of SLEV in nonhuman primates and horses from southern Brazil. Methods From June 2004 to December 2005, sera from 133 monkeys (Alouatta caraya, n=43; Sapajus nigritus, n=64; Sapajus cay, n=26) trap-captured at the Paraná River basin region and 23 blood samples from farm horses were obtained and used for the ser...

  17. A 38,000-year record of floods and debris flows in the Ilo region of southern Peru and its relation to El Niño events and great earthquakes

    Science.gov (United States)

    Keefer, David K.; Moseley, Michael E.; DeFrance, Susan D.

    2003-01-01

    Previous work throughout the Ilo region of south coastal Peru has documented the existence of flood and debris-flow deposits produced by two El Niño events evidently much more severe than any in recent history. These two events have been dated to ca. AD 1300–1400 and AD 1607–08. The Late Pleistocene to Holocene record of older sedimentary deposits in this region is dominated by flood and debris-flow deposits of similar scale. These older deposits have been described and dated from three coastal, alluvial-fan sites. These deposits, which are as old as 38 200 years, are dominated by massive debris-flow deposits, several tens of cm thick, typically composed of cobble- and boulder-sized clasts in a matrix of silty sand, with characteristics indicating generation by heavy rainfall in an arid environment. Twenty-two radiocarbon dates and a single infrared-stimulated luminescence date show that particularly severe El Niño events occurred throughout the Late Pleistocene and two of three divisions of the Holocene with significantly different frequencies. The period of greatest activity was during the Early Holocene when at least six such events took place during a period of ca. 3600 years, beginning near the end of the Younger Dryas ca. 12 000 years ago. One of these events produced a debris flow that may have caused abandonment of the Paleo-Indian site at Quebrada Tacahuay, one of the oldest on the Andean coast. No severe events took place during the Middle Holocene between ca. 8400 and 5300 years ago, when a wide variety of other paleoclimate proxy records indicate that the El Niño–Southern Oscillation regime was particularly weak. Since ca. 5300 years ago, four of these severe events have taken place. The Late Pleistocene sequence is constrained by only two dates, which indicate that at least ten severe events took place between ca. 38 200 and 12 900 years ago. Mechanisms probably responsible for generating these large-scale deposits include: (1)

  18. The Hydromedusae and its distribution in Chukchi Sea and adjacent southern edge waters of Canada Basin, Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    张金标; 林茂

    2001-01-01

    The present paper is based on materials collected in Chukchi Sea and adjacent southern edge waters of Canada Basin, Arctic Ocean during the period from July to August 1999 on the icebreaker, the R/V “Xuelong”, by the Chinese First Arctic Scientific Expedition. Totally, 8 species of pelagic Hydromedusae were identified, of which 4 species belonged to Anthomedusae, 2 species to Leptomedusae, 1 species to Trachymedusae and 1 species to Narcomedusae, the Neoturris breviconis is recorded for the first time in Chukchi Sea. Their principal morphological characteristics are described and illustrated. The 8 species of Hydromedusae occurring in the Chukchi Sea were all cold water species, of which 6 species belong to neritic species and 2 species to ocean species. According to the geographic distribution of species, they may be divided into three groups: Arctic species, Arctic-boreal species and Boreal-temperate species. From the view-point of zoogeography, species from these waters belong to the Arctic fauna.The abundance of Hydromedusae in Chukchi Sea was generally low, with a mean value of 108 ind.*10-2*m-3. Rathkea octopunctata and Aglantha digitale were dominant species. From the view-point of vertical distribution Aglantha digitale is inhabiting in the depth of 0 300 m and with the maximum in the depth of 50 m to 100 m.

  19. Hunter-gatherer adaptations and environmental change in the southern Great Basin: The evidence from Pahute and Rainier mesas

    Energy Technology Data Exchange (ETDEWEB)

    Pippin, L.C.

    1998-06-01

    This paper reviews the evidence for fluctuations in past environments in the southern Great Basin and examines how these changes may have affected the strategies followed by past hunter and gatherers in their utilization of the resources available on a highland in this region. The evidence used to reconstruct past environments for the region include botanical remains from packrat middens, pollen spectra from lake and spring deposits, faunal remains recovered from archaeological and geologic contexts, tree-ring indices from trees located in sensitive (tree-line) environments, and eolian, alluvial and fluvial sediments deposited in a variety of contexts. Interpretations of past hunter and gatherer adaptive strategies are based on a sample of 1,311 archaeological sites recorded during preconstruction surveys on Pahute and Rainier mesas in advance of the US Department of Energy`s nuclear weapons testing program. Projectile point chronologies and available tree-ring, radiocarbon, thermoluminescence and obsidian hydration dates were used to assign these archaeological sites to specific periods of use.

  20. Object-based locust habitat mapping using high-resolution multispectral satellite data in the southern Aral Sea basin

    Science.gov (United States)

    Navratil, Peter; Wilps, Hans

    2013-01-01

    Three different object-based image classification techniques are applied to high-resolution satellite data for the mapping of the habitats of Asian migratory locust (Locusta migratoria migratoria) in the southern Aral Sea basin, Uzbekistan. A set of panchromatic and multispectral Système Pour l'Observation de la Terre-5 satellite images was spectrally enhanced by normalized difference vegetation index and tasseled cap transformation and segmented into image objects, which were then classified by three different classification approaches: a rule-based hierarchical fuzzy threshold (HFT) classification method was compared to a supervised nearest neighbor classifier and classification tree analysis by the quick, unbiased, efficient statistical trees algorithm. Special emphasis was laid on the discrimination of locust feeding and breeding habitats due to the significance of this discrimination for practical locust control. Field data on vegetation and land cover, collected at the time of satellite image acquisition, was used to evaluate classification accuracy. The results show that a robust HFT classifier outperformed the two automated procedures by 13% overall accuracy. The classification method allowed a reliable discrimination of locust feeding and breeding habitats, which is of significant importance for the application of the resulting data for an economically and environmentally sound control of locust pests because exact spatial knowledge on the habitat types allows a more effective surveying and use of pesticides.

  1. River-Basin Politics and the Rise of Ecological and Transnational Democracy in Southeast Asia and Southern Africa

    Directory of Open Access Journals (Sweden)

    Chris Sneddon

    2008-06-01

    Full Text Available In recent years, debates over 'deliberative', 'transnational' and 'ecological' democracy have proliferated, largely among scholars engaged in discussions of modernisation, globalisation and political identity. Within this broad context, scholars and practitioners of environmental governance have advanced the argument that a democratic society will produce a more environmentally conscious society. We want to make a volte-face of this argument and ask: to what extent does engagement with environmental politics and, specifically, water politics, contribute to processes of democratisation? After reviewing some of the contributions to debates over 'ecological' and 'transnational' democracy, we explore this question within the context of conflicts over river-basin development in Southeast Asia and southern Africa. We argue that there are multiple pathways to democratisation and that, in some cases, the environment as a political issue does constitute a significant element of democratisation. But notions of 'ecological' and 'transnational' democracy must embody how both 'environment' and 'the transnational', as mobilised by specific social movements in specific historical and geographical circumstances, are politically constructed.

  2. An organic geochemical correlation study of some Drmno depresssion crude oils (southern part of the Pannonian Basin, Yugoslavia

    Directory of Open Access Journals (Sweden)

    D. VITOROVIC

    2001-05-01

    Full Text Available The results of an investigation of crude oils originating from the Sirakovo and Bradarac-Maljurevac localities (southern part of the Pannonian Basin are reported in this paper. The aim was to estimate the organic geochemical similarity of the crude oils from the Drmno (Kostolac depression oil fields. The nine selected samples originated from reservoir rocks of various depths. Reliable source and organic geochemical maturation parameters served as the basis for the correlation studies. The similar origin of the investigated Drmno depression crude oils was corroborated, characterized by a significant participation of terrestrial precursor biomass. They were shown to be of relatively low maturity and to have been formed during the earlier stages of the diagenet- ic-catagenetic sequence of processes leading to the formation of crude oils, most probably in source rocks ofTertiary age, corresponding to vitrinite reflectances between Ro = 0.70 % and Ro = 0.80 %. The crude oils from Bradarac-Maljurevac seemed to be somewhat less homogeneous with respect to organic geochemical parameters compared to Sirakovo crude oils.

  3. Southern North Sea Basin in Europe: Biodiversity of the Marine Fürstenau Formation Including Early White and Megatooth Sharks

    Directory of Open Access Journals (Sweden)

    C. G. Diedrich

    2012-01-01

    Full Text Available The Fürstenau Formation (Lutetian, Paleogene, Eocene is based on type sections near Fürstenau in Germany (central Europe and is built of 22 meter thick marine glauconitic and strongly bioturbated sands, clays, and a vertebrate-rich conglomerate bed. The conglomerate layer from the Early Lutetian transgression reworked Lower Cretaceous, and Paleogene marine sediments. It is dominated by pebbles from the locally mountains which must have been transported by an ancient river in a delta fan. Marine reworked Lower Cretaceous and Paleogen pebbles/fossils, were derived from the underlying deposits of northern Germany (= southern pre North Sea basin. The benthic macrofauna is cold upwelling water influenced and non-tropical, and medium divers. The vertebrate fish fauna is extremely rich in shark teeth, with about 5,000 teeth per cubic meter of gravel. The most dominant forms are teeth from sand shark ancestors Striatolamia macrota, followed by white shark ancestors Carcharodon auriculatus. Even teeth from the magatooth shark ancestor Carcharocles sokolovi are present in a moderately diverse and condensed Paleogene fish fauna that also includes rays, chimaeras, and more then 80 different bony fish. Fragmentary turtle remains are present, and few terrestrial vertebrates and even marine mammals with phocids, sirenians and possibly whales.

  4. Structural features and petroleum geology of the fold-thrust belt in the southern Tarim basin, China

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xinyuan; LUO Jinhai; WANG Qinghua

    2004-01-01

    The west Kunlun fold-thrust belt (WKFTB) and the Altun fold-thrust belt (AFTB) are respectively located in the southern margin of the Tarim basin, NW China. The analyses of typical structures and regional dynamics of the fold-thrust belts reveal their different structural and petroleum features and mechanisms. WKFTB differs from AFTB by abundant fault-related folds and triangles zones, and was formed by northward extrusion of the west Kunlun orogen. AFTB was affected synchronously by northward extrusion of the Altun orogen and the sinistral strike-slipping of the Altun Fault, so it is characterized by the minor scale and the monotonous structural styles. The Aqike anticline and the Aqike fault, of which the strikes are orthogonal to the strike of the fold-thrust belts, are regarded as the adjustive structures between both of the fold-thrust belts. The oil-gas pools of WKFTB develop mainly in the faulted-related anticline traps, but the oil-gas pools of AFTB develop mainly in the low fault-block and anticlines traps related with the paleo-uplifts. There are different exploration countermeasures for both of the fold-thrust belts.

  5. Geochemical evolution of groundwater in southern Bengal Basin: The example of Rajarhat and adjoining areas, West Bengal, India

    Indian Academy of Sciences (India)

    Paulami Sahu; P K Sikdar; Surajit Chakraborty

    2016-02-01

    Detailed geochemical analysis of groundwater beneath 1223 km2 area in southern Bengal Basin along with statistical analysis on the chemical data was attempted, to develop a better understanding of the geochemical processes that control the groundwater evolution in the deltaic aquifer of the region. Groundwater is categorized into three types: `excellent', `good' and `poor' and seven hydrochemical facies are assigned to three broad types: `fresh', `mixed' and `brackish' waters. The `fresh' water type dominated with sodium indicates active flushing of the aquifer, whereas chloride-rich `brackish' groundwater represents freshening of modified connate water. The `mixed' type groundwater has possibly evolved due to hydraulic mixing of `fresh' and `brackish' waters. Enrichment of major ions in groundwater is due to weathering of feldspathic and ferro-magnesian minerals by percolating water. The groundwater of Rajarhat New Town (RNT) and adjacent areas in the north and southeast is contaminated with arsenic. Current-pumping may induce more arsenic to flow into the aquifers of RNT and Kolkata cities. Future large-scale pumping of groundwater beneath RNT can modify the hydrological system, which may transport arsenic and low quality water from adjacent aquifers to presently unpolluted aquifer.

  6. Modelling the impact of a subsurface barrier on groundwater flow in the lower Palar River basin, southern India

    Science.gov (United States)

    Senthilkumar, M.; Elango, L.

    2011-06-01

    Groundwater modelling is widely used as a management tool to understand the behaviour of aquifer systems under different hydrological stresses, whether induced naturally or by humans. The objective of this study was to assess the effect of a subsurface barrier on groundwater flow in the Palar River basin, Tamil Nadu, southern India. Groundwater is supplied to a nearby nuclear power plant and groundwater also supplies irrigation, industrial and domestic needs. In order to meet the increasing demand for groundwater for the nuclear power station, a subsurface barrier/dam was proposed across Palar River to increase the groundwater heads and to minimise the subsurface discharge of groundwater into the sea. The groundwater model used in this study predicted that groundwater levels would increase by about 0.1-0.3 m extending out a distance of about 1.5-2 km from the upstream side of the barrier, while on the downstream side, the groundwater head would lower by about 0.1-0.2 m. The model also predicted that with the subsurface barrier in place the additional groundwater requirement of approximately 13,600 m3/day (3 million gallons (UK)/day) can be met with minimum decline in regional groundwater head.

  7. Seismicity in the Raton Basin of Southern Colorado and Northern New Mexico, USA, as Recorded by a Local Array

    Science.gov (United States)

    Macartney, H.

    2013-12-01

    Microseismic events (Raton Basin of southern Colorado and northern New Mexico, USA, over a period of 18 months following the occurrence of a 5.3 magnitude event near Trinidad CO in August, 2011. Micro-seismicity was observed in the region, concentrated in six clusters at depths of 6-12 km below the surface, deep in the basement, and 4-10 km below zones used for fluid disposal from an overlying coalbed methane natural gas field. Clusters are separated from disposal zones by large aseismic intervals. The clusters are mixed in character; both planar and elongate amorphous swarms, some continually active and some as short-lived bursts, with larger initial events tending to occur deeper and smaller after-shocks propagating upward and away from the nucleating events. Magnitudes range between 0 and 3, with the vast majority being less than 1.5M. Most of the clusters have no disposal wells above and no seismic activity was correlated with changes in fluid disposal. No seismicity was detected from hydraulic fracturing operations.

  8. Fault zone characteristics and basin complexity in the southern Salton Trough, California

    Science.gov (United States)

    Persaud, Patricia; Ma, Yiran; Stock, Joann M.; Hole, John A.; Fuis, Gary S.; Han, Liang

    2016-01-01

    Ongoing oblique slip at the Pacific–North America plate boundary in the Salton Trough produced the Imperial Valley (California, USA), a seismically active area with deformation distributed across a complex network of exposed and buried faults. To better understand the shallow crustal structure in this region and the connectivity of faults and seismicity lineaments, we used data primarily from the Salton Seismic Imaging Project to construct a three-dimensional P-wave velocity model down to 8 km depth and a velocity profile to 15 km depth, both at 1 km grid spacing. A VP = 5.65–5.85 km/s layer of possibly metamorphosed sediments within, and crystalline basement outside, the valley is locally as thick as 5 km, but is thickest and deepest in fault zones and near seismicity lineaments, suggesting a causative relationship between the low velocities and faulting. Both seismicity lineaments and surface faults control the structural architecture of the western part of the larger wedge-shaped basin, where two deep subbasins are located. We estimate basement depths, and show that high velocities at shallow depths and possible basement highs characterize the geothermal areas.

  9. Endocrine disruptors in water filters used in the Rio dos Sinos Basin region, Southern Brazil.

    Science.gov (United States)

    Furtado, C M; von Mühlen, C

    2015-05-01

    The activated carbon filter is used in residences as another step in the treatment of drinking water, based on a physical-chemical process to absorb pollutants that are not removed in conventional treatment. Endocrine disruptors (EDCs) are exogenous substances or mixtures of substances that acts on the endocrine system similarly to the endogenously produced hormones, triggering malfunctions and harmful changes to human and animal health. The objective of the present work was to study EDCs through semi-quantitative analysis of residential water filters collected in the region of Rio dos Sinos basin, focusing on two specific classes: hormones and phenols. The solid phase extraction principle was used for the extraction of compounds and gas chromatography coupled with mass spectrometry for the separation and characterization of EDCs. Four samples of residential filters collected from public water distribution and artesian wells, from the cities of Novo Hamburgo and São Leopoldo were analysed. Using the developed methodology, it was possible to detect and comparatively quantify selected EDCs in all studied samples, which indicates the presence of these contaminants in drinking water from different sources.

  10. Drought and vegetation analysis in Tarsus River Basin (Southern Turkey using GIS and Remote Sensing data

    Directory of Open Access Journals (Sweden)

    Celalettin Duran

    2015-12-01

    Full Text Available In this study, the effects of topographic variables on drought and vegetation in dry season have been examined. Distributions of dry conditions in Tarsus River Basin were derived using the NDVI, NDMI indexes and LST (Land Surface Temperature from landsat8 image bands. There is large difference in elevation in the study area. Local climatic conditions are formed under the influence of altitude and morphological structure. Narrow and deep valleys in the topography create more moderate temperature/moisture conditions and are the main distribution area of tall forest vegetation. High radiation in the highest plateau system and, extreme temperature/moisture values led short-lived herbaceous vegetation to spread. Due to high insolation/temperature and restricted marine affect, establishment of scrub vegetation can be observed both in mid-elevation and south-sloping plateau of the study area. Anthropogenic agricultural fields form the land surface with the potential of high temperature/evapotranspiration rate in harvesting periods. Broadleaf plant species spread in areas close to the base of the valley stream. Plantation forest has been created in areas of near-shore sand dunes and very small delta (marsh. Variability in topography also increases the width of the combination of factors that shape the vegetation. This also enables the number of taxa to increase and unusual taxa to co-exist.

  11. Species composition and phytosociology of xerophytic plant communitiesSouth Peru after extreme rainfall in South Peru

    NARCIS (Netherlands)

    Montesinos-Tubée, D.B.; Sýkora, K.V.; Quipuscoa-Silvestre, V.; Cleef, A.M.

    2015-01-01

    We present a phytosociological overview of the arid and semi-arid montane vegetation of the province of Arequipa in southern Peru. The xerophytic vegetation was studied after extreme rainfall had promoted exceptionally lush vegetation and a high aboveground floristic diversity. We used TWINSPAN for

  12. Environmental monitoring in the Mar Grande basin (Ionian Sea, Southern Italy).

    Science.gov (United States)

    De Serio, Francesca; Mossa, Michele

    2016-07-01

    Hydrodynamic and water quality data has been recorded since February 2014 by a meteo-oceanographic station installed in the inner part of the Gulf of Taranto, in the northeastern part of the Ionian Sea (Southern Italy). This monitoring action, managed by the research unit of the Technical University of Bari, DICATECh Department, could play a pivotal role in a vulnerable and sensitive area, affected by massive chemical and biological pollutant discharges due to the presence of heavy industry and intense maritime traffic. Monthly trends of winds, waves, currents, and biochemical parameters, such as dissolved oxygen, chlorophyll, and turbidity, are analyzed and discussed. The analysis exhibits that the wave regime is slightly controlled by wind forcing; rather, topography strongly affects the wave propagation direction. Surface currents appear wind induced in the measuring station, while near the bottom a quasi-steady current directed towards southwest is formed. The selected water quality indicators show monthly trends consistent with the typical seasonal convective fluxes and mixing.

  13. Prevalence of malformed frogs in Kaoping and Tungkang river basins of southern Taiwan.

    Science.gov (United States)

    Huang, Da-Ji; Chiu, Yuh-Wen; Chen, Chien-Min; Huang, Kai-Hsiang; Wang, Shu-Yin

    2010-05-01

    In this study we found many amphibians with bizarre appearances, known as malformations in Pingtung County southern Taiwan. For this investigation we collected frogs inhabiting the Kaoping and Tungkang river watersheds between February 2006 and June 2007. Among the total number of 10,909 normal frogs (i.e., anurans) collected during the investigation period, the Indian rice frogs (Rana limnocharis) account for the greatest number next is the Chinese bullfrog (Rana rugulosa). Of all the 244 captured malformed frogs, the Indian rice frog account for the greatest proportion. These malformed frogs have their main distribution in upstream areas of these two rivers. Our result indicates that the appearance rate of malformed frogs is 1.8% in the upstream reaches of the Kaoping River and 2.6%, and 0.8%, respectively in the upstream and midstream reaches of the Tungkang river. The most-commonly-found malformation is the lack of palms, followed by the lack of appendages, exostosis, and a malformed appendicular. It is, therefore, reasonable to speculate that the causes for the malformation may be related to the increased organic pollutants and agricultural chemicals used in the upstream reaches of these two rivers.

  14. Flash flood occurrences since the 17th century in steep drainage basins in southern Italy.

    Science.gov (United States)

    Petrucci, Olga; Pasqua, A Aurora; Polemio, Maurizio

    2012-11-01

    The historical floods that have occurred since the seventeenth century were collected for a study area in southern Italy. Damages caused by floods, rainfall and the main anthropogenic modifications are discussed all together. The aim was to assess whether the frequency of floods is changing and, if so, whether these changes can be attributed to either rainfall and/or anthropogenic modifications. In 4 % of cases, mainly occurred in past centuries, floods damaged people. Hydraulic works, roads and private buildings were the more frequently damaged elements (25, 18 and 14 % of the cases, respectively). The annual variability of rainfall was discussed using an annual index. Short duration-high intensity rainfalls were characterized considering time series of annual maxima of 1, 3, 6, 12, and 24 h and daily rainfall. The rainfall shows a decreasing trend, in terms of both the annual maximum of short duration and the annual amount. The population has been progressively increasing since the sixteenth century, except during the years following the catastrophic 1908 earthquake. The rate of population growth has been very high since the second half of the twentieth century; the urbanized areas greatly increased, especially following the second half of the twentieth century. At the same time, the trend of damaging floods has been increasing, especially since the seventies. The analysis indicates that, despite a rainfall trend favourable towards a reduction in flood occurrence, floods damage has not decreased. This seems to be mainly the effect of mismanagement of land use modifications.

  15. Delayed tree mortality in the Atchafalaya Basin of Southern Louisiana following Hurricane Andrew

    Science.gov (United States)

    Keeland, B.D.; Gorham, L.E.

    2009-01-01

    Hurricanes can damage trees in forested wetlands, and the potential for mortality related to these storms exists due to the effects of tree damage over time. In August 1992, Hurricane Andrew passed through the forested wetlands of southern Louisiana with winds in excess of 225 kph. Although more than 78 of the basal area was destroyed in some areas, most trees greater than 2.5 cm dbh were alive and resprouting prolifically the following year (98.8). Survival of most tree species was similarly high two years after the hurricane, but mortality rates of some species increased dramatically. For example, Populus heterophylla (swamp cottonwood) mortality increased from 7.8 to 59.2 (n 76) and Salix interior (sandbar willow) mortality increased from 4.5 to 57.1 (n 21). Stem sprouts on many up-rooted hardwood trees of other species were still alive in 1998, 6 years after the hurricane. Due to the understory tree species composition, regeneration, and high levels of resprouting, there was little change in species composition or perhaps a slight shift toward more shade and flood tolerant species six years following the hurricane event. Triadica sebifera (Chinese tallow) was found on some of the sites heavily disturbed by Hurricane Andrew, and may proliferate at the expense of native tree species. ?? 2009 The Society of Wetland Scientists.

  16. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Ranch Fire, Ventura and Los Angeles Counties, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Ranch Fire in Ventura and Los Angeles Counties, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  17. Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Slide and Grass Valley Fires, San Bernardino County, Southern California

    Science.gov (United States)

    Cannon, Susan H.; Gartner, Joseph E.; Michael, John A.; Bauer, Mark A.; Stitt, Susan C.; Knifong, Donna L.; McNamara, Bernard J.; Roque, Yvonne M.

    2007-01-01

    INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Slide and Grass Valley Fires in San Bernardino County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 3.50 inches (88.90 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

  18. Simulation-optimization aids in resolving water conflict: Temecula Basin, Southern California

    Science.gov (United States)

    Hanson, Randall T.; Faunt, Claudia C.; Schmid, Wolfgang; Lear, Jonathan

    2014-01-01

    The productive agricultural areas of Pajaro Valley, California have exclusively relied on ground water from coastal aquifers in central Monterey Bay. As part of the Basin Management Plan (BMP), the Pajaro Valley Water Management Agency (PVWMA) is developing additional local supplies to replace coastal pumpage, which is causing seawater intrusion. The BMP includes an aquifer storage and recovery (ASR) system, which captures and stores local winter runoff, and supplies it to growers later in the growing season in lieu of ground-water pumpage. A Coastal Distribution System (CDS) distributes water from the ASR and other supplemental sources. A detailed model of the Pajaro Valley is being used to simulate the coupled supply and demand components of irrigated agriculture from 1963 to 2006. Recent upgrades to the Farm Process in MODFLOW (MF2K-FMP) allow simulating the effects of ASR deliveries and reduced pumping for farms in subregions connected to the CDS. The BMP includes a hierarchy of monthly supply alternatives, including a recovery well field around the ASR system, a supplemental wellfield, and onsite farm supply wells. The hierarchy of delivery requirements is used by MF2K-FMP to estimate the effects of these deliveries on coastal ground-water pumpage and recovery of water levels. This integrated approach can be used to assess the effectiveness of the BMP under variable climatic conditions, and to test the impacts of more complete subscription by coastal farmers to the CDS deliveries. The model will help managers assess the effects of new BMP components to further reduce pumpage and seawater intrusion.

  19. Late Givetian ammonoids from Hassi Nebech (Tafilalt Basin, Anti-Atlas, southern Morocco

    Directory of Open Access Journals (Sweden)

    J. Bockwinkel

    2013-02-01

    Full Text Available The Hassi Nebech area of the SE Tafilalt (Tafilalt Basin, Anti-Atlas, Morocco yielded the richest and most diverse late Givetian ammonoid fauna on a global scale. Above the distinctive regional "Lower Marker Bed" (Synpharciceras clavilobum Zone, abundant loosely collected limonitic specimens derive from hypoxic shales of the Taouzites taouzensis to Petteroceras errans zones. The ontogenetic morphometry and intraspecific variability of a total of 30 species representing five families, the Acanthoclymeniidae, Taouzitidae, Pharciceratidae, Petteroceratidae, and Tornoceratidae, are documented. New taxa are: Pseudoprobeloceras praecox n. sp., Scaturites minutus n. gen. n. sp., Darkaoceras velox n. sp., Pharciceras decoratum n. sp., Ph. fornix n. sp., Ph. subconstans n. sp., Ph. involutum n. sp., Lunupharciceras incisum n. sp., Transpharciceras procedens n. gen. n. sp., Stenopharciceras progressum n. sp., Pluripharciceras n. gen. (type species: Synpharciceras plurilobatum Petter, 1959, Plu. orbis n. sp., Synpharciceras frequens n. sp., Lobotornoceras bensaidi n. sp., Nebechoceras eccentricum n. gen. n. sp., and Phoenixites lenticulus n. sp. The documentation of conch and particularly suture ontogeny and intraspecific variability necessitates a revised diagnosis for ten taxa. Manticoceras pontiformis Termier & Termier, 1950, Probeloceras costulatum Petter, 1959, and Pseudoprobeloceras nebechense Bensaïd, 1974 are regarded as subjective junior synonyms of Ps. pernai (Wedekind, 1918. Sandbergeroceras acutum Termier & Termier, 1950 is a subjective synonym of Taouzites taouzensis (Termier & Termier, 1950. Pharciceras applanatum Bensaïd, 1974 is transferred to Extropharciceras. Other forms (Ph. aff. tridens, Ph. cf. subconstans n. sp., Extropharciceras n. sp. 2, Ex. cf. arenicum, Ex. cf. applanatum, Synpharciceras sp., Plu. cf. plurilobatum are described in open nomenclature. doi:10.1002/mmng.201300001

  20. Geology and potential hydrocarbon play system of Lower Karoo Group in the Maamba Coalfield Basin, southern Zambia

    Science.gov (United States)

    Phiri, Cryton; Wang, Pujun; Nyambe, Imasiku Anayawa

    2016-06-01

    This study attempts to augment geology and potential hydrocarbon play system database not only in the Maamba Coalfield basin of southern Zambia but in other similar continental non-marine Karoo rift basins in the region as well. Geological analyses were conducted through extensive outcrops and exposures and subsurface boreholes. Six (6) major lithofacies (diamictites, conglomerates, sandstones, siltstones, coal and mudstones) represents Lower Karoo Group sequence. Four (4) mudstone core samples were prepared for thin section petrography. In addition, six (6) samples of sandstones obtained from outcrops, exposures and cores were impregnated with blue epoxy before thin sectioning in order to facilitate easy recognition of porosity. Quantification of framework grain composition and porosity was achieved by point counting a total of 300 points per thin section. The identification of diagenetic constituents and pore types was made possible by the use of scanning electron microscopy (SEM). Rock-Eval pyrolysis analyses utilised 35 core samples of mudstones and coal. According to results of the analyses, three (3) deposition settings which include; alluvial, fluvial-lacustrine and lacustrine setting are envisaged. . Fluvial-lacustrine deposits are host to mudstones and coal source rocks and sandstone reservoir rocks. Mudstones and coal source rocks gave the total organic carbon (TOC) that is well above the recommended thresholds of 0.5 wt % and 2.5 wt % of gas and oil generation respectively. The hydrogen index (HI) values are mostly below 200 mg HC/g TOC, indicating fair quantities of type III kerogen. The thermal maturity readings measured by temperature Tmax range from 440 to 485 °C in agreement with calculated vitrinite reflectance (Rocalc) range of 0.76-1.57% indicating mature to post mature stages. This maturation is attributed to the burial temperatures and near-surface heat flows by faults. Production Index (PI) values are less than 0.1 suggesting some hydrocarbon

  1. Cenozoic magnetostratigraphy and magnetic properties of the southern Issyk-Kul basin, Kyrgyzstan

    Science.gov (United States)

    Wack, Michael R.; Gilder, Stuart A.; Macaulay, Euan A.; Sobel, Edward R.; Charreau, Julien; Mikolaichuk, Alexander

    2014-08-01

    We present paleomagnetic data from the northern flank of the Tianshan range, southeast of Lake Issyk-Kul (Kyrgyzstan). 613 cores were collected in two parallel sections with a total thickness of 960 m (Chon Kyzylsuu, CK) and 990 m (Jeti Oguz, JO), as well as 48 cores at six sites in a nearby anticline. Rock magnetic analyses identify both magnetite and hematite in the fluvial-lacustrine sediments. The concentration of both minerals, the magnetite:hematite ratio, and the average magnetite grain size increase upward in both sections. Anisotropy of anhysteretic remanent magnetization defines a tectonic fabric with sub-horizontal maximum axes that parallel the strike direction together with intermediate and minimum axes that streak out about a great circle orthogonal to the maximum axes suggestive of a tectonic fabric emplaced during folding. Stepwise thermal demagnetization isolates interpretable magnetization components in 284 samples that define 26 polarity chrons in CK and 19 in JO. A positive fold test, dual polarities and systematic changes in rock-magnetic parameters with depth suggest that the high temperature magnetization component was acquired coevally with deposition. An age model based on a visual magnetostratigraphic correlation of both sections with the geomagnetic polarity time scale defines absolute ages from 26.0 to 13.3 Ma, with a fairly constant sedimentation rate of 9-10 cm/ka. A correlation based on a numerical algorithm arrives at a slightly different conclusion, with deposition ages from 25.2 to 11.0 Ma and sedimentation rates from 5 to 8 cm/ka. In comparison with sedimentation rates found at other magnetostratigraphic sections in the Tianshan realm, we infer that the sedimentary record in this part of the Issyk-Kul Basin precedes the more rapid phase of uplift of the Kyrgyz Tianshan. The onset of deposition and concomitant erosion of the adjacent Terskey Range is in good agreement with independent assessments of the exhumation history of this

  2. Spectral analysis of hydrological time series of a river basin in southern Spain

    Science.gov (United States)

    Luque-Espinar, Juan Antonio; Pulido-Velazquez, David; Pardo-Igúzquiza, Eulogio; Fernández-Chacón, Francisca; Jiménez-Sánchez, Jorge; Chica-Olmo, Mario

    2016-04-01

    Spectral analysis has been applied with the aim to determine the presence and statistical significance of climate cycles in data series from different rainfall, piezometric and gauging stations located in upper Genil River Basin. This river starts in Sierra Nevada Range at 3,480 m a.s.l. and is one of the most important rivers of this region. The study area has more than 2.500 km2, with large topographic differences. For this previous study, we have used more than 30 rain data series, 4 piezometric data series and 3 data series from gauging stations. Considering a monthly temporal unit, the studied period range from 1951 to 2015 but most of the data series have some lacks. Spectral analysis is a methodology widely used to discover cyclic components in time series. The time series is assumed to be a linear combination of sinusoidal functions of known periods but of unknown amplitude and phase. The amplitude is related with the variance of the time series, explained by the oscillation at each frequency (Blackman and Tukey, 1958, Bras and Rodríguez-Iturbe, 1985, Chatfield, 1991, Jenkins and Watts, 1968, among others). The signal component represents the structured part of the time series, made up of a small number of embedded periodicities. Then, we take into account the known result for the one-sided confidence band of the power spectrum estimator. For this study, we established confidence levels of <90%, 90%, 95%, and 99%. Different climate signals have been identified: ENSO, QBO, NAO, Sun Spot cycles, as well as others related to sun activity, but the most powerful signals correspond to the annual cycle, followed by the 6 month and NAO cycles. Nevertheless, significant differences between rain data series and piezometric/flow data series have been pointed out. In piezometric data series and flow data series, ENSO and NAO signals could be stronger than others with high frequencies. The climatic peaks in lower frequencies in rain data are smaller and the confidence

  3. Evaluating the efficiency of sediment metal pollution indices in interpreting the pollution of Haraz River sediments, southern Caspian Sea basin.

    Science.gov (United States)

    Nasrabadi, Touraj; Bidhendi, Gholamreza Nabi; Karbassi, Abdolreza; Mehrdadi, Nasser

    2010-12-01

    The Haraz River is one of the most significant rivers in the southern Caspian Sea basin. Towards the estuary, the river receives discharges of industrial, agricultural, and urban wastes. In the present investigation, bulk concentrations of Cu, Zn, As, Cd, Pb, Fe, Ni, Cr, Co, and Sr in Haraz River (Iran) bed sediments were measured from several sample locations. In addition, association of studied metals with various sedimentary phases was assessed to determine the proportions of metals in different forms. The intensity of sediment contamination was evaluated using an enrichment factor (EF), geo-accumulation index (I(geo)), and a newly developed pollution index (I(poll)). Both EF and I(geo) formulae compare present concentrations of metals to their background levels in crust and shale, respectively. In a specific area with its own geological background like Haraz River water basin where naturally high concentrations of metals may be found, such a comparison may lead to biased conclusions regarding levels of anthropogenic contamination. Accordingly, chemical partitioning results are substituted for the mean crust and shale levels in the new index (I(poll)). The Pearson correlation coefficient between the anthropogenic portion of metallic pollution in Haraz river-bed sediments with I(poll) showed much more value in comparison with those of geochemical accumulation index and enrichment factor. The order of metals introduced by anthropogenic activities are as follows: Sr > Pb > Co > Cd > Zn > Cu > Ni > As > Cr > Fe. The results showed relatively higher concentrations of Cd, As, Sr, and Pb in comparison with those of shale. However, based on the chemical partitioning of metals, it is found that Sr, Pb, Co, and Cd are the most mobile metals. In spite of the high As concentrations in sediments, it is not likely that this element is a major hazard for the aquatic environment since it is found mainly in the residual fraction. Also, Fe, Cr, and Ni are present in the greatest

  4. Religious Regimes in Peru

    NARCIS (Netherlands)

    Spier, Fred

    1994-01-01

    This inquiry deals with religion and politics in Peru from the beginning of agrarisation, c. 8000 B.C. up until AD 1991. Of central importance for the analysis are state formation and development, the relations between church and state, the internal and external relations within and among the variou

  5. Assessing sedimentation rates at Usumacinta and Grijalva river basin (Southern Mexico) using OSL and suspended sediment load analysis: A study from the Maya Classic Period

    Science.gov (United States)

    Munoz-Salinas, E.; Castillo, M.; Sanderson, D.; Kinnaird, T.; Cruz-Zaragoza, E.

    2013-12-01

    Studying sedimentation rates on floodplains is key to understanding environmental changes occurred through time in river basins. The Usumacinta and Grijalva rivers flow most of their travel through the southern part of Mexico, forming a large river basin, crossing the states of Chiapas and Tabasco. The Usumacinta-Grijalva River Basin is within the 10 major rivers of North America, having a basin area of ~112 550 km2. We use the OSL technique for dating two sediment profiles and for obtaining luminescence signals in several sediment profiles located in the streambanks of the main trunk of the Usumacinta and Grijalva rivers. We also use mean annual values of suspended sediment load spanning ~50 years to calculate the sedimentation rates. Our OSL dating results start from the 4th Century, when the Maya Civilization was at its peak during the Classic Period. Sedimentation rates show a notable increase at the end of the 19th Century. The increase of the sedimentation rates seems to be related to changes in land uses in the Sierra Madre de Chiapas and Altos de Chiapas, based on deforestation and land clearing for developing new agrarian and pastoral activities. We conclude that the major environmental change in the basin of the Usumacinta and Grijalva Rivers since the Maya Classic Period was generated since the last Century as a result of an intense anthropogenic disturbance of mountain rain forest in Chiapas.

  6. Evolution of the late Quaternary San Gregorio Magno tectono-karstic basin (southern Italy) inferred from geomorphological, tephrostratigraphical and palaeoecological analyses: tectonic implications

    Science.gov (United States)

    Aiello, G.; Ascione, A.; Barra, D.; Munno, R.; Petrosino, P.; Russo Ermolli, E.; Villani, F.

    2007-03-01

    The Pantano di San Gregorio Magno is a 4.7 km2 large tectono-karstic basin located in the axial belt of the Southern Apennines, an area affected by intense seismicity. The basin was formed in the Middle Pleistocene and is presently undissected. It is filled by lacustrine sediments (clays, silts and pyroclastic sands) passing laterally into alluvial fan deposits. Geomorphological investigations were integrated with tephrostratigraphical, palynological and palaeoecological analyses of a 61 m thick core (not reaching the bedrock). The multiproxy analysis of the S. Gregorio Magno record shows that, over the last 200k yr, the basin hosted a freshwater lake with an oscillating level. Age constraints provided by the tephrostratigraphic record allowed estimation of the sedimentation rate, which varied strongly through time. Evolution of the basin resulted from the complex combination of tectonic subsidence, karst processes and changing amounts of sedimentary inputs. The latter was influenced by allogenic contributions related both to primary and reworked volcanoclastic inputs and was climate-driven. The overall evidence, which indicates that in the long-term the accumulation rate substantially counterbalanced the accommodation space created by faulting, suggests that the basin evolution was also modulated by changing subsidence rates. Copyright

  7. Understanding the Physiography, Bioclimate and Mapping of the Vegetation of the Chalakkudy River Basin, Anamalai part of Southern Western Ghats, India

    Directory of Open Access Journals (Sweden)

    Amitha Bachan Kandarumadathil Hyder

    2014-09-01

    Full Text Available Vegetation of an area is determined by the overall interaction of the climatic, edaphic, and biotic factors. It is important to define the bioclimate of a region to understand the Vegetation dynamics of a region especially of the Tropical Monsoonal continents with complex physiography. It is a pioneering effort to understand bioclimate and primary   vegetation of a river basin from the southern Western Ghats region. Twenty years of rainfall data were analysed and geophysical features of the Chalakkudy River basin were analysed using GIS facility. The results provide more accurate data of the length, area and other physiographic features for the Chalakkudy River basin indicating need of updating of data of other river basins of Kerala. The bioclimatic data analyzed from 20 years of rainfall and vegetation maps indicate presence of dry-moist-forest zones to ever wet-rainforest regimes in the basin. The vegetation data shows 80% catchements of the river under forest category of which primary forests dominates with 519 Km2 (36% followed by forest plantations 179.6 Km2 (12%, secondary forests 197.4 Km2 (17%, tea, coffee and other plantations constitute 198.3 Km2 (13%, degraded non forest vegetation 86.9 Km2 (6% and reservoir, streams and rivers 46.5 Km2 (3%.  Of the 361 Km2 primary wet-evergreen (Rainforests forests 294 Km2 is dense forest and 67 Km2 is degraded forests.

  8. A Study of the Connection Among Basin-Fill Aquifers, Carbonate-Rock Aquifers, and Surface-Water Resources in Southern Snake Valley, Nevada

    Science.gov (United States)

    ,

    2008-01-01

    The Secretary of the Interior through the Southern Nevada Public Lands Management Act approved funding for research to improve understanding of hydrologic systems that sustain numerous water-dependent ecosystems on Federal lands in Snake Valley, Nevada. Some of the streams and spring-discharge areas in and adjacent to Great Basin National Park have been identified as susceptible to ground-water withdrawals (Elliott and others, 2006) and research has shown a high potential for ground-water flow from southern Spring Valley into southern Snake Valley through carbonate rocks that outcrop along a low topographic divide known as the Limestone Hills (Welch and others, 2007). Comprehensive geologic, hydrologic, and chemical information will be collected and analyzed to assess the hydraulic connection between basin-fill aquifers and surface-water resources, water-dependent ecological features, and the regional carbonate-rock aquifer, the known source of many high-discharge springs. Understanding these connections is important because proposed projects to pump and export ground water from Spring and Snake Valleys in Nevada may result in unintended capture of water currently supplying springs, streams, wetlands, limestone caves, and other biologically sensitive areas (fig. 1). The methods that will be used in this study may be transferable to other areas in the Great Basin. The National Park Service, Bureau of Land Management, U.S. Fish and Wildlife Service, and U.S. Forest Service submitted the proposal for funding this research to facilitate science-based land management. Scientists from the U.S. Geological Survey (USGS) Water Resources and Geologic Disciplines, and the University of Nevada, Reno, will accomplish four research elements through comprehensive data collection and analysis that are concentrated in two distinct areas on the eastern and southern flanks of the Snake Range (fig. 2). The projected time line for this research is from July 2008 through September 2011.

  9. Contribution of the airborne geophysical survey to the study of the regolith : A case study in southern Paris Basin.

    Science.gov (United States)

    Prognon, Francois; Lacquement, Fréderic; Deparis, Jacques; Martelet, Guillaume; Perrin, José

    2010-05-01

    Studies of soil and subsoil, also called regolith, are at the crossroads of scientific new challenging questions as well as new environmental needs. Historically, geological maps were focussed on solid geology. Present societal needs increasingly require knowledge of regolith properties: superficial studies combining geology, geochemistry and geophysics become essential to better understand the natural processes which govern the repartition and evolution of subsoil formations. Such progress is critical to better orient the use and management of natural and groundwater resources. Among other techniques, airborne geophysics is appropriate to provide information on near surface, because of i) its high spatial coverage ii) the rapidity of acquisition and iii) the variety of available sensors (magnetic, spectral radiometry, electromagnetic …). We illustrate the results of an airborne geophysical survey carried out in France, in "Région Centre" administrative region in the southern part of the Paris Basin. Spectral radiometry data were collected throughout "Région Centre" with a line spacing of 1 km. This method provides maps of potassium (K), uranium (U) and thorium (Th) which are the only naturally occurring elements with direct or indirect radioisotopes that produce gamma rays of sufficient intensity to be measured at airborne survey heights. Gamma-rays emitted from the Earth surface are related to the primary mineralogy and geochemistry of the bedrock and/or the nature of secondary weathering including regolith materials. Obtained images are confronted with former geological investigations (1:50 000e geological maps). Geophysical data and geological maps are generally consistent on most of the covered area since the first-rate information delivered by the spectrometry derives from the geochemistry of the solid geology. Second-rate gamma-ray responses come from superimposed allochtonous deposits as well as in situ geochemical modifications. For instance

  10. Differences in nitrous oxide distribution patterns between the Bering Sea basin and Indian Sector of the Southern Ocean

    Institute of Scientific and Technical Information of China (English)

    CHEN Liqi; ZHANG Jiexia; ZHAN Liyang; LI Yuhong; SUN Heng

    2014-01-01

    Nitrous oxide (N2O) distribution patterns in the Bering Sea basin (BSB) and Indian Sector of the Southern Ocean (ISSO) were described and compared. In both sites, the waters were divided into four layers:surface layer, subsurface layer, N2O maximum layer, and deep water. Simulations were made to find out the most important factors that regulate the N2O distribution patterns in different layers of both sites. The results showed that in the surface water, N2O was more understaturated in the ISSO than the BSB. This phenom-enon in the surface water of ISSO may result from ice melt water intrusion and northeastward transport of the Antarctic surface water. Results of the rough estimation of air-sea fluxes during the expedition were (-0.34±0.07)-(-0.64±0.13) μmol/(m2·d) and (-1.47±0.42)-(-1.77±0.51) μmol/(m2·d) for the BSB and the ISSO, respectively. Strongly stratified surface layer and temperature minimum layer restricted exchange across the thermocline. The N2O maximum existed in higher concentration and deeper in the BSB than the ISSO, but their contribution to the upper layer by eddy diffusions was negligible. In deep waters, a concen-tration difference of 5 nmol/L N2O between these two sites was found, which suggested that N2O produc-tion occurred during thermohaline circulation. N2O may be a useful tracer to study important large-scale hydrographic processes.

  11. Paleoclimatic implications of fossil shoreline deposits in the southern basin and range province during the Pleistocene-Holocene transition

    Science.gov (United States)

    Kowler, A. L.

    2010-12-01

    Paleolake shoreline deposits throughout the southern Basin and Range (SBAR) signify past intervals of steady-state climatic conditions occuring during the late Pleistocene slightly before, as well as after the Last Glacial Maximum (LGM; ~23-19 Ka). Unfortunately, a lack of knowledge about the age of fossil shoreline deposits—due to C-14 related uncertainties and incomplete dating of shorelines—has resulted in a large gap in our knowledge about past climatic and surface hydrologic conditions in the SBAR. Several studies collectively reveal multiple lake level oscillations during the LGM and last part of the Pleistocene, with reasonably well dated shoreline deposits existing for only four paleolakes: one in central New Mexico (Estancia), two in southwestern New Mexico (Playas and Cloverdale), and one in southeastern Arizona (Cochise). In summary, there is evidence for a pre-LGM high-stand at Cochise (>26 Ka), LGM high-stands at Estancia and Cloverdale (>20-16 Ka), deglacial age high-stands at Playas and Cochise (16-13 Ka), and latest Pleistocene-early Holocene still stands of as yet undetermined elevation at Playas and Estancia (13-9K). Further, the absence of high-stands from 11-10 Ka suggests that the Younger Dryas climatic reversal—which is detected in the stable O isotopic composition of speleothems from Cave-of-the-Bells in southeastern Arizona—was marked there by a decrease in mean annual air temperature without a significant increase in precipitation. Alternatively, if a return to glacial precipitation levels did occur, then it was for an interval so short that sedimentological evidence was not preserved. This presentation will cover the afore mentioned chronologies, along with discussion about associated atmospheric circulation patterns in the SBAR and across western North America.

  12. Abandoned mine drainage in the Swatara Creek Basin, southern anthracite coalfield, Pennsylvania, USA: 2. performance of treatment systems

    Science.gov (United States)

    Cravotta, Charles A.

    2010-01-01

    A variety of passive and semi-passive treatment systems were constructed by state and local agencies to neutralize acidic mine drainage (AMD) and reduce the transport of dissolved metals in the upper Swatara Creek Basin in the Southern Anthracite Coalfield in eastern Pennsylvania. To evaluate the effectiveness of selected treatment systems installed during 1995–2001, the US Geological Survey collected water-quality data at upstream and downstream locations relative to each system eight or more times annually for a minimum of 3 years at each site during 1996–2007. Performance was normalized among treatment types by dividing the acid load removed by the size of the treatment system. For the limestone sand, open limestone channel, oxic limestone drain, anoxic limestone drain (ALD), and limestone diversion well treatment systems, the size was indicated by the total mass of limestone; for the aerobic wetland systems, the size was indicated by the total surface area of ponds and wetlands. Additionally, the approximate cost per tonne of acid treated over an assumed service life of 20 years was computed. On the basis of these performance metrics, the limestone sand, ALD, oxic limestone drain, and limestone diversion wells had similar ranges of acid-removal efficiency and cost efficiency. However, the open limestone channel had lower removal efficiency and higher cost per ton of acid treated. The wetlands effectively attenuated metals transport but were relatively expensive considering metrics that evaluated acid removal and cost efficiency. Although the water-quality data indicated that all treatments reduced the acidity load from AMD, the ALD was most effective at producing near-neutral pH and attenuating acidity and dissolved metals. The diversion wells were effective at removing acidity and increasing pH of downstream water and exhibited unique potential to treat moderate to high flows associated with storm flow conditions.

  13. When the waves of European Neolithization met: first paleogenetic evidence from early farmers in the southern Paris Basin.

    Directory of Open Access Journals (Sweden)

    Maïté Rivollat

    Full Text Available An intense debate concerning the nature and mode of Neolithic transition in Europe has long received much attention. Recent publications of paleogenetic analyses focusing on ancient European farmers from Central Europe or the Iberian Peninsula have greatly contributed to this debate, providing arguments in favor of major migrations accompanying European Neolithization and highlighting noticeable genetic differentiation between farmers associated with two archaeologically defined migration routes: the Danube valley and the Mediterranean Sea. The aim of the present study was to fill a gap with the first paleogenetic data of Neolithic settlers from a region (France where the two great currents came into both direct and indirect contact with each other. To this end, we analyzed the Gurgy 'Les Noisats' group, an Early/Middle Neolithic necropolis in the southern part of the Paris Basin. Interestingly, the archaeological record from this region highlighted a clear cultural influence from the Danubian cultural sphere but also notes exchanges with the Mediterranean cultural area. To unravel the processes implied in these cultural exchanges, we analyzed 102 individuals and obtained the largest Neolithic mitochondrial gene pool so far (39 HVS-I mitochondrial sequences and haplogroups for 55 individuals from a single archaeological site from the Early/Middle Neolithic period. Pairwise FST values, haplogroup frequencies and shared informative haplotypes were calculated and compared with ancient and modern European and Near Eastern populations. These descriptive analyses provided patterns resulting from different evolutionary scenarios; however, the archaeological data available for the region suggest that the Gurgy group was formed through equivalent genetic contributions of farmer descendants from the Danubian and Mediterranean Neolithization waves. However, these results, that would constitute the most ancient genetic evidence of admixture between farmers

  14. Multiple Suppression and Imaging of Marine Seismic Data from The Shallow Water Area in Southern East China Sea Shelf Basin

    Science.gov (United States)

    Shi, J.; Luan, X.; Yang, C.

    2015-12-01

    Neither surface-related multiple elimination(SRME) nor predictive de-convolution method is effective to suppress the multiple of marine seismic data from the shallow water area. The former method needs the accurate reflection of seafloor, which is mixed with the direct wave in the near offset range. The other one could probably lose the primary wave when applied to the shallow water seismic data. We introduced the new method: deterministic water-layer de-multiple method (DWD) which is capable for the poor extrapolate result of near-offset traces. Firstly, the data shifts as downward continuation in tau-p domain with a water-layer period and the multiple model will be obtained. Then, the original seismic subtracts adaptively with the multiple model. Finally, we would get the de-multiple data after inverse tau-p transform. Marine seismic real data is from southern part of East China Sea Shelf Basin. This area has become the potential target for marine hydrocarbon exploration, it is located in the junction of the Eurasian plate pacific plate and Indian plate. Because the average water depth is less than 100 meters, seismic data contains abundant of multiple, especially the surface-related multiple. As a result it is difficult to distinguish the strata structure clearly. We used DWD approach to remove the water-layer multiple, cut off the seafloor reflection events and then suppressed the residual surface-related multiple by the traditional SRME. At last , the radon transform was applied to eliminate the multiple with long period . With these steps, we suppressed the multiple of marine seismic data from this area effectively. After multiple is removed , we acquired more accurate velocity to build the velocity model of migration. With the pre-stack migration technique, reflections from each geological period are shown clearly in the seismic section. This work was supported by the National Science Foundation of China(grant no. 41476053).

  15. A structurally controlled fan-delta complex at the southern margin of the peninsular range forearc basin complex (Baja California)

    Energy Technology Data Exchange (ETDEWEB)

    Morris, W.R.; Busby-Spera, C. (Univ. of California, Santa Barbara (USA))

    1990-05-01

    A confined trunk fan delta and its structurally controlled tributary fan deltas are extremely well exposed along the southern margin of the Rosario embayment. This fan-delta complex consists of nonmarine to deep marine deposits almost continuously exposed for over 20 km in the down-paleoslope direction. Facies and stratal patterns in the fan-delta complex were controlled by local faulting, climatic variation, and eustasy, resulting in relative sea level fluctuations. Basin bathymetry and drainage patterns were controlled by a series of half-grabens that formed along north-south-trending faults that lay along the northern margin of an east-west-trending depression. Breccias were initially shed into the north-south-trending half-grabens; axial drainage systems were later established within the grabens, making up the tributary fan deltas. These tributary fan deltas fed a voluminous trunk fan delta confined to the east-west-trending depression. The trunk and tributary fan delta deposits show two major progradational to retrogradational cycles that record relative sea level fluctuations. Progradation in the shallow-marine environment is represented by conglomerate channels cut into ripple-laminated or bioturbated siltstone and HCS sandstones, overlain by conglomerate mouth bar deposits interstratified with nearshore sandstone deposits. Retrogradation in the shallow marine environment is recorded by either a vertical clastic facies transition or a clastic-carbonate facies transition. The clastic facies transition consists of nearshore sandstone deposits overlain by offshore bioturbated siltstones. The clastic-carbonate facies transition consists of the development of red algal patch reefs and rhodoliths on top of fan-delta conglomeratic lobes, mudstone and sandstone bank channel margins, or paleobasement highs. The clastic-carbonate facies transition reflects low sediment supply controlled by climatic conditions.

  16. Diagenesis and reservoir quality of the Lower Cretaceous Quantou Formation tight sandstones in the southern Songliao Basin, China

    Science.gov (United States)

    Xi, Kelai; Cao, Yingchang; Jahren, Jens; Zhu, Rukai; Bjørlykke, Knut; Haile, Beyene Girma; Zheng, Lijing; Hellevang, Helge

    2015-12-01

    The Lower Cretaceous Quantou Formation in the southern Songliao Basin is the typical tight oil sandstone in China. For effective exploration, appraisal and production from such a tight oil sandstone, the diagenesis and reservoir quality must be thoroughly studied first. The tight oil sandstone has been examined by a variety of methods, including core and thin section observation, XRD, SEM, CL, fluorescence, electron probing analysis, fluid inclusion and isotope testing and quantitative determination of reservoir properties. The sandstones are mostly lithic arkoses and feldspathic litharenites with fine to medium grain size and moderate to good sorting. The sandstones are dominated by feldspar, quartz, and volcanic rock fragments showing various stages of disintegration. The reservoir properties are quite poor, with low porosity (average 8.54%) and permeability (average 0.493 mD), small pore-throat radius (average 0.206 μm) and high displacement pressure (mostly higher than 1 MPa). The tight sandstone reservoirs have undergone significant diagenetic alterations such as compaction, feldspar dissolution, quartz cementation, carbonate cementation (mainly ferrocalcite and ankerite) and clay mineral alteration. As to the onset time, the oil emplacement was prior to the carbonate cementation but posterior to the quartz cementation and feldspar dissolution. The smectite to illite reaction and pressure solution at stylolites provide a most important silica sources for quartz cementation. Carbonate cements increase towards interbedded mudstones. Mechanical compaction has played a more important role than cementation in destroying the reservoir quality of the K1q4 sandstone reservoirs. Mixed-layer illite/smectite and illite reduced the porosity and permeability significantly, while chlorite preserved the porosity and permeability since it tends to be oil wet so that later carbonate cementation can be inhibited to some extent. It is likely that the oil emplacement occurred

  17. When the waves of European Neolithization met: first paleogenetic evidence from early farmers in the southern Paris Basin.

    Science.gov (United States)

    Rivollat, Maïté; Mendisco, Fanny; Pemonge, Marie-Hélène; Safi, Audrey; Saint-Marc, Didier; Brémond, Antoine; Couture-Veschambre, Christine; Rottier, Stéphane; Deguilloux, Marie-France

    2015-01-01

    An intense debate concerning the nature and mode of Neolithic transition in Europe has long received much attention. Recent publications of paleogenetic analyses focusing on ancient European farmers from Central Europe or the Iberian Peninsula have greatly contributed to this debate, providing arguments in favor of major migrations accompanying European Neolithization and highlighting noticeable genetic differentiation between farmers associated with two archaeologically defined migration routes: the Danube valley and the Mediterranean Sea. The aim of the present study was to fill a gap with the first paleogenetic data of Neolithic settlers from a region (France) where the two great currents came into both direct and indirect contact with each other. To this end, we analyzed the Gurgy 'Les Noisats' group, an Early/Middle Neolithic necropolis in the southern part of the Paris Basin. Interestingly, the archaeological record from this region highlighted a clear cultural influence from the Danubian cultural sphere but also notes exchanges with the Mediterranean cultural area. To unravel the processes implied in these cultural exchanges, we analyzed 102 individuals and obtained the largest Neolithic mitochondrial gene pool so far (39 HVS-I mitochondrial sequences and haplogroups for 55 individuals) from a single archaeological site from the Early/Middle Neolithic period. Pairwise FST values, haplogroup frequencies and shared informative haplotypes were calculated and compared with ancient and modern European and Near Eastern populations. These descriptive analyses provided patterns resulting from different evolutionary scenarios; however, the archaeological data available for the region suggest that the Gurgy group was formed through equivalent genetic contributions of farmer descendants from the Danubian and Mediterranean Neolithization waves. However, these results, that would constitute the most ancient genetic evidence of admixture between farmers from both Central

  18. Fossil Cenozoic crassatelline bivalves from Peru: New species and generic insights

    Directory of Open Access Journals (Sweden)

    Thomas J. DeVries

    2016-08-01

    Full Text Available Discoveries of new fossil Cenozoic crassatellines in Peru provide a new phylogenetic perspective on “large” Neogene genera, in which four lineages are considered to have arisen independently from different Paleogene Crassatella ancestors. Latest Oligocene and early Miocene species of the new genus Tilicrassatella gen. nov.―T. ponderosa, T. torrens sp. nov., and T. sanmartini sp. nov. from the East Pisco Basin―probably evolved from the late Eocene species, Crassatella rafaeli sp. nov., which itself differed in significant respects from slightly older species of the East Pisco Basin, C. neorhynchus and C. pedroi sp. nov. The paciphilic genus, Hybolophus, is raised to full generic status. Added to its ranks are the East Pisco Miocene species H. maleficae sp. nov., H. terrestris sp. nov., and the oldest species of the genus, the late Eocene or Oligocene H. disenum sp. nov. from the Talara Basin of northern Peru. Kalolophus gen. nov., encompassing circum-Caribbean fossil species, the extant species, K. speciosus, and the trans-isthmus species, K. antillarum, appears to have evolved from the early Oligocene Floridian species, Crassatella portelli sp. nov. The genus Marvacrassatella is a western Atlantic Miocene lineage most likely descended from Kalolophus. The genus Eucrassatella is restricted to Australian and New Zealand taxa. The Eocene New Zealand species, Spissatella media, is transferred to Eucrassatella and deemed a candidate for the most recent common ancestor of younger Eucrassatella and all Spissatella species. In the southern Pacific Ocean, the circum-Caribbean region, and tropical western America, crassatelline lineages developed one or more of the following characters: large resilifers, smooth ventral margins, and an extended left anterior cardinal tooth. Some of these late Paleogene convergent character changes might have countered increased shear forces exerted on the crassatelline valves while burrowing into finer-grained and

  19. Large vertical motions and basin evolution in the Outer Continental Borderland off Southern California associated with plate boundary development and continental rifting

    Science.gov (United States)

    Nicholson, C.; Sorlien, C. C.; Schindler, C. S.; De Hoogh, G.

    2011-12-01

    The Continental Borderland offshore southern California occupies a strategic position along the continental margin. It was the locus of ~75% of Pacific-North America displacement history, it helped accommodate the large-scale (>90°) tectonic rotation of the Western Transverse Ranges province, and is still accommodating potentially 20% of PAC-NAM plate motion today. As such, it represents an ideal natural laboratory to investigate plate boundary evolution and basin development associated with transform initiation, oblique continental rifting, transrotation and transpression. We have been using newly released grids of high-quality industry multichannel seismic (MCS) reflection data, combined with multibeam bathymetry and offshore well data to map and construct digital 3D fault surfaces and stratigraphic reference horizons over large parts of the Outer Continental Borderland. These 3D surfaces of structure and stratigraphy can be used to better understand and evaluate regional patterns of uplift, subsidence, fault interaction and other aspects of plate boundary deformation. In the northern Outer Borderland, mapping in Santa Cruz basin, and across both Santa Rosa and Santa Cruz-Catalina ridges reveals a pattern of interacting high-and low-angle faults, fault reactivation, basin subsidence, folding, and basin inversion. Subsidence since early-Miocene time is significant (up to 4 km) and is much larger than predicted by simple thermal cooling models of continental rifting. This requires additional tectonic components to drive this regional subsidence and subsequent basin inversion. Farther south, a more en echelon pattern of ridges and basins suggests a distributed component of right-lateral shear also contributed to much of the modern Borderland seafloor topography, including major Borderland basins. Vertical motions of uplift and subsidence can be estimated from a prominent early-Miocene unconformity that likely represents a regional, paleo-horizontal, near

  20. New seismo-stratigraphic data of the Volturno Basin (northern Campania, Tyrrhenian margin, southern Italy: implications for tectono-stratigraphy of the Campania and Latium sedimentary basins

    Directory of Open Access Journals (Sweden)

    Ennio Marsella

    2011-07-01

    Full Text Available A geological section of the Volturno Basin (northern Campania, continental margin, Italy has been constructed based on new multi-channel seismic data, to show the stratigraphic relationships between the filling in the Quaternary basin and the Meso-Cenozoic acoustic basement. The new seismic sections presented here outline the underlying structures of the basin and their relationships to the filling in the Quaternary basin. Deep exploration wells in Campania and Latium on the Tyrrhenian margin have gathered litho-stratigraphic and commercial multi-channel seismic data that can be used for better integration of the geological data for the area under study. The trending of the seismic units is controlled by the Massico Structural High, which forms the boundary of the Volturno Basin towards the north-west. This produces a geometry that is characteristic of a fan complex, with NE-SW trending. This qualitative calibration of the seismic sequences that fill the sedimentary basin was carried out through the litho-stratigraphic data of the «Castelvolturno 2» well, which highlights the pyroclastic layers and conglomeratic strata of the lagoon and delta environments as they evolve upwards towards marine sediments. Seismo-stratigraphic analysis shows the complex depositional geometries of the filling in the Volturno Basin, which overlie the Meso-Cenozoic carbonatic basement and the related flysch deposits. Coupled with regional geological evidence, the data interpretation here suggests that the Volturno Basin represents a half-graben structure that is characterized by down-thrown blocks along normal faults.

  1. Interbasin flow in the Great Basin with special reference to the southern Funeral Mountains and the source of Furnace Creek springs, Death Valley, California, U.S.

    Science.gov (United States)

    Belcher, W.R.; Bedinger, M.S.; Back, J.T.; Sweetkind, D.S.

    2009-01-01

    Interbasin flow in the Great Basin has been established by scientific studies during the past century. While not occurring uniformly between all basins, its occurrence is common and is a function of the hydraulic gradient between basins and hydraulic conductivity of the intervening rocks. The Furnace Creek springs in Death Valley, California are an example of large volume springs that are widely accepted as being the discharge points of regional interbasin flow. The flow path has been interpreted historically to be through consolidated Paleozoic carbonate rocks in the southern Funeral Mountains. This work reviews the preponderance of evidence supporting the concept of interbasin flow in the Death Valley region and the Great Basin and addresses the conceptual model of pluvial and recent recharge [Nelson, S.T., Anderson, K., Mayo, A.L., 2004. Testing the interbasin flow hypothesis at Death Valley, California. EOS 85, 349; Anderson, K., Nelson, S., Mayo, A., Tingey, D., 2006. Interbasin flow revisited: the contribution of local recharge to high-discharge springs, Death Valley, California. Journal of Hydrology 323, 276-302] as the source of the Furnace Creek springs. We find that there is insufficient modern recharge and insufficient storage potential and permeability within the basin-fill units in the Furnace Creek basin for these to serve as a local aquifer. Further, the lack of high sulfate content in the spring waters argues against significant flow through basin-fill sediments and instead suggests flow through underlying consolidated carbonate rocks. The maximum temperature of the spring discharge appears to require deep circulation through consolidated rocks; the Tertiary basin fill is of insufficient thickness to generate such temperatures as a result of local fluid circulation. Finally, the stable isotope data and chemical mass balance modeling actually support the interbasin flow conceptual model rather than the alternative presented in Nelson et al. [Nelson

  2. Preliminary study on Late Triassic to Early Jurassic strata and floral variation in Hechuan region of Chongqing,southern Sichuan Basin

    Institute of Scientific and Technical Information of China (English)

    Ning TIAN; Yongdong WANG; Xiaoju YANG; Qing NI; Zikun JIANG

    2008-01-01

    The end-Triassic mass extinction event is extensively known, however, the terrestrial response of this event is still poorly understood. Here we briefly report our preliminary results on the variation of floral diversity through the Triassic/Jurassic boundary deposits in the Tanba section of Hechuan region, Chongqing, southern China. It is recognized that the floral biodiversity of the Hechuan region shows a distinct change through the Triassic and Jurassic transition; and the floral diversity loss reaches up to 92 5% at species level. Meanwhile, in northeastern region of the Sichuan Basin, the floral diversity declines by about 50% across the T/J boundary at species level with a remarkable turnover of genera and species. The potential reasons and mechanisms that cause the floral diversity differentiation of the T/J boundary in the Sichuan Basin are briefly discussed in this note.

  3. Stratigraphy and paleogeographic significance of a Late Pennsylvanian to Early Permian channeled slope sequence in the Darwin Basin, southern Darwin Hills, east-central California

    Science.gov (United States)

    Stevens, Calvin H.; Stone, Paul; Magginetti, Robert T.; Ritter, Scott M.

    2015-01-01

    The complex stratigraphy of late Paleozoic rocks in the southern Darwin Hills consists of regionally extensive Mississippian and Early to Middle Pennsylvanian rocks overlain by latest Pennsylvanian to Early Permian rocks, herein called the Darwin Hills sequence. Deposition of this latter sequence marked the beginning of the Darwin Basin. In Mississippian time, a carbonate platform prograded westward over slightly older slope deposits. In the Late Mississippian this platform was exposed to erosion and siliciclastic sediments were deposited. In Early to Middle Pennsylvanian time the area subsided, forming a west-facing ramp that was subjected to deformation and erosion in Middle or early Late Pennsylvanian time. Later this area was tilted westward and deep-water sediments were deposited on this slope. In latest Pennsylvanian to earliest Permian time, a major channel was cut through the older Pennsylvanian rocks and into the Upper Mississippian strata. This channel was gradually filled with increasingly finer grained, deep-water sediment as the area evolved into a basin floor by Early Permian (Sakmarian) time. Expansion of the Darwin Basin in Artinskian time led to a second phase of deposition represented by strata of the regionally extensive Darwin Canyon Formation. The geology in this small area thus documents tectonic events occurring during the early development of the Darwin Basin.

  4. Interplay between regional uplift and glacio-eustasy in the Crotone Basin (Calabria, southern Italy) since 0.45 Ma: A review

    Science.gov (United States)

    Zecchin, Massimo; Caffau, Mauro; Ceramicola, Silvia

    2016-08-01

    During the last 0.45 Ma, the Crotone Basin, a forearc basin located on the Ionian side of Calabria, southern Italy, experienced a phase of uplift that persists today. The transition from subsidence to uplift occurred close to the Marine Isotope Stage (MIS) 11 (ca. 0.4 Ma). The subsequent progressive emergence of the area was punctuated by several marine transgressions linked to high-frequency, high-magnitude glacio-eustatic changes, which are recorded as coastal terraces. These high-frequency sequences show a variable stacking pattern due to the interplay between glacio-eustasy, uplift and local physiography. In particular, a progressive SE-ward migration of the shoreline is documented in the study area since MIS 11. This trend was enhanced during the MIS 5.5 to MIS 2 time interval, due to the combined effect of uplift and lowering glacio-eustatic sea level until the Last Glacial Maximum. Moreover, the regional uplift also led to a physiographic change from relatively low-gradient to high-gradient settings between MIS 7.1 and MIS 5.5. A comparison between the late Quaternary geological record of the Crotone Basin and that of other basins is crucial to improve the present knowledge on past sea levels related to MISs. This ultimately will help to better understand the Holocene sea-level history and the human contribution to sea-level change, in order to predict future scenarios.

  5. Giant Otters in Peru

    Directory of Open Access Journals (Sweden)

    Schenk C.

    1992-02-01

    Full Text Available We are in the second year of fieldwork surveying for Giant Otters in the southeastern rainforest of Peru, in three areas with differing levels of legal protection. While there is some illegal hunting still happening outside the protected areas, the main threat to the otters is badly-conducted tourism. Well-organised tourism can be a promising argument for establishing protected areas like national parks.

  6. Fairy chimneys in Peru

    CERN Document Server

    Sparavigna, Amelia Carolina

    2011-01-01

    Erosion creates beautiful landscapes. A large part of them is known just by the local population. Google Maps can help in locating the places, study them and start any project for preservation. An interesting example is given by a landscape of fairy chimneys in Peru, near San Pedro de Larcay. It is remarkable the fact that some of them have been adapted as dwelling places.

  7. Integrative geomorphological mapping approach for reconstructing meso-scale alluvial fan palaeoenvironments at Alborz southern foothill, Damghan basin, Iran

    Science.gov (United States)

    Büdel, Christian; Majid Padashi, Seyed; Baumhauer, Roland

    2013-04-01

    Alluvial fans and aprons are common depositional features in general Iranian geomorphology. The countries major cities as well as settlements and surrounding area have often been developed and been built up on this Quaternary sediment covers. Hence they periodically face the effects of varying fluvial and slope-fluvial activity occurring as part of this geosystem. The Geological Survey of Iran therefore supports considerable efforts in Quaternary studies yielding to a selection of detailed mapped Quaternary landscapes. The studied geomorphologic structures which are settled up around an endorheic basin in Semnan Province represent a typical type of landform configuration in the area. A 12-km-transect was laid across this basin and range formation. It is oriented in north-south direction from the southern saltpan, called "Kavir-e-Haj Aligholi"/"Chah-e-Jam" ("Damghan Kavir"), across a vast sandy braided river plain, which is entering from the north east direction of the city of Shahroud. At its northern rim it covers alluvial sediment bodies, which are mainly constituted by broad alluvial aprons, fed by watersheds in Alborz Mountains and having their genetic origins in Mio-/Pliocene times. During this study a fully analytical mapping system was used for developing a geodatabase capable of integrating geomorphological analyses. Therefore the system must provide proper differentiation of form, material and process elements as well as geometric separation. Hence the German GMK25 system was set up and slightly modified to fit to the specific project demands. Due to its structure it offers most sophisticated standards and scale independent hierarchies, which fit very well to the software-determinated possibilities of advanced geodatabase applications. One of the main aspects of mapping Quaternary sediments and structures is to acquire a proper description and systematic correlation and categorization of the belonging mapping-objects. Therefore the team from GSI and

  8. Structure and function of fish communities in the southern Lake Michigan basin with emphasis on restoration of native fish communities

    Science.gov (United States)

    Simon, Thomas P.; Stewart, Paul M.

    1999-01-01

    The southern Lake Michigan basin in northwest Indiana possesses a variety of aquatic habitats including riverine, palustrine, and lacustrine systems. The watershed draining this area is a remnant of glacial Lake Chicago and supports fish communities that are typically low in species richness. Composition of the presettlement Lake Michigan fish community near the Indiana Dunes has been difficult to reconstruct. Existing data indicate that the number of native species in the Lake Michigan watershed, including nearshore Lake Michigan, has declined by 22% since the onset of European settlement. Few remnants of natural fish communities exist, and those occur principally in the ponds of Miller Woods, the Grand Calumet Lagoons, and the Little Calumet River. These communities have maintained a relatively diverse assemblage of fishes despite large-scale anthropogenic disturbances in the area, including channelization, massive river redirection, fragmentation, habitat alteration, exotic species invasions, and the introduction of toxic chemicals. Data that we collected from 1985 to 1996 suggested that the Grand Calumet River has the highest proportion of exotic fish species of any inland wetland in northwest Indiana. Along the Lake Michigan shoreline, another group of exotics (e.g., round goby, alewife, and sea lamprey) have affected the structure of native fish communities, thereby altering lake ecosystem function. Stocking programs contribute to the impairment of native communities. Nonindigenous species have restructured the function of Lake Michigan tributaries, causing disruptions in trophic dynamics, guild structure, and species diversity. Several fish communities have been reduced or eliminated by the alteration and destruction of spawning and nursery areas. Degradation of habitats has caused an increase in numbers and populations of species able to tolerate and flourish when confronted with hydrologic alteration. Fish communities found on public lands in northwest

  9. Peru Mercury Inventory 2006

    Science.gov (United States)

    Brooks, William E.; Sandoval, Esteban; Yepez, Miguel A.; Howard, Howell

    2007-01-01

    In 2004, a specific need for data on mercury use in South America was indicated by the United Nations Environmental Programme-Chemicals (UNEP-Chemicals) at a workshop on regional mercury pollution that took place in Buenos Aires, Argentina. Mercury has long been mined and used in South America for artisanal gold mining and imported for chlor-alkali production, dental amalgam, and other uses. The U.S. Geological Survey (USGS) provides information on domestic and international mercury production, trade, prices, sources, and recycling in its annual Minerals Yearbook mercury chapter. Therefore, in response to UNEP-Chemicals, the USGS, in collaboration with the Economic Section of the U.S. Embassy, Lima, has herein compiled data on Peru's exports, imports, and byproduct production of mercury. Peru was selected for this inventory because it has a 2000-year history of mercury production and use, and continues today as an important source of mercury for the global market, as a byproduct from its gold mines. Peru is a regional distributor of imported mercury and user of mercury for artisanal gold mining and chlor-alkali production. Peruvian customs data showed that 22 metric tons (t) of byproduct mercury was exported to the United States in 2006. Transshipped mercury was exported to Brazil (1 t), Colombia (1 t), and Guyana (1 t). Mercury was imported from the United States (54 t), Spain (19 t), and Kyrgyzstan (8 t) in 2006 and was used for artisanal gold mining, chlor-alkali production, dental amalgam, or transshipment to other countries in the region. Site visits and interviews provided information on the use and disposition of mercury for artisanal gold mining and other uses. Peru also imports mercury-containing batteries, electronics and computers, fluorescent lamps, and thermometers. In 2006, Peru imported approximately 1,900 t of a wide variety of fluorescent lamps; however, the mercury contained in these lamps, a minimum of approximately 76 kilograms (kg), and in

  10. Using apatite fission track thermochronology to document the deformation sequence in an exhumed foreland basin: an example from the southern Pyrenees.

    Science.gov (United States)

    Meresse, F.; Labaume, P.; Jolivet, M.; Teixell, A.

    2009-04-01

    Université Montpellier 2, INSU-CNRS, Laboratoire Géosciences Montpellier, cc060, 34095 Montpellier Cedex 5, France florian.meresse@gm.univ-montp2.fr The study of foreland basins provides important constraints on the evolution of orogenic wedges. In particular, the study of tectonics-sedimentation relationships is essential to date the tectonic activity. However, processes linked to wedge growth are not always completely recorded by the tecto-sedimentary markers, and thermochronological study of the basin-fill can provide further insights. In this work, we have combined apatite fission track analysis (apatite FTA) with structural analysis to precise the timing of the deformation sequence and to characterise the coupling between thrust activity, burial and denudation in the south-Pyrenean foreland basin, a proximal foredeep of the Pyrenees that has been incorporated in the Pyrenean thrust wedge. We have focused the study on a NNE-SSW cross-section of the south-vergent thrust system from the southern flank of the Axial Zone to the South-Pyrenean Frontal Thrust (SPFT), in the west-central part of the belt. This section provides a complete transverse of the South-Pyrenean Zone, here corresponding to the Ainsa and Jaca basins. Apatite FTA provides important new constraints on the south-Pyrenean foreland basin evolution: (i) Data show the southward decrease of the fission track reset level, from a total reset (indicating heating at Tmax>110°C) in the Paleozoic of the Axial Zone, to a partial reset (110°C>Tmax>60°C) in the lower-middle Eocene Hecho Group turbidites in the northern part of the Jaca basin, and to the absence of reset (TmaxJaca basin. This indicates a decreasing amount of denudation going southwards, from more than 4.5 km in the north to less than 2.5 km in the south if we assume an average geothermal gradient around 25°/km. The structural setting of the Jaca basin attests that the burial of sediments was mainly due to sedimentary accumulation. (ii

  11. New species and host plants of Anastrepha (Diptera: Tephritidae) primarily from Peru and Bolivia.

    Science.gov (United States)

    Norrbom, Allen L; Rodriguez, Erick J; Steck, Gary J; Sutton, Bruce A; Nolazco, Norma

    2015-11-16

    Twenty-eight new species of Anastrepha are described and illustrated: A. acca (Bolivia, Peru), A. adami (Peru), A. amplidentata (Bolivia, Peru), A. annonae (Peru), A. breviapex (Peru), A. caballeroi (Peru), A. camba (Bolivia, Peru), A. cicra (Bolivia, Peru), A. disjuncta (Peru), A. durantae (Peru), A. echaratiensis (Peru), A. eminens (Peru), A. ericki (Peru), A. gonzalezi (Bolivia, Peru), A. guevarai (Peru), A. gusi (Peru), A. kimi (Colombia, Peru), A. korytkowskii (Bolivia, Peru), A. latilanceola (Bolivia, Peru), A. melanoptera (Peru), A. mollyae (Bolivia, Peru), A. perezi (Peru), A. psidivora (Peru), A. robynae (Peru), A. rondoniensis (Brazil, Peru), A. tunariensis (Bolivia, Peru), A. villosa (Bolivia), and A. zacharyi (Peru). The following host plant records are reported: A. amplidentata from Spondias mombin L. (Anacardiaceae); A. caballeroi from Quararibea malacocalyx A. Robyns & S. Nilsson (Malvaceae); A. annonae from Annona mucosa Jacq. and Annona sp. (Annonaceae); A. durantae from Duranta peruviana Moldenke (Verbenaceae); and A. psidivora from Psidium guajava L. (Myrtaceae).

  12. Layer-block tectonics of Cenozoic basements and formation of intra-plate basins in Nansha micro-plate,southern South China Sea

    Institute of Scientific and Technical Information of China (English)

    LIU Hailing; XIE Guofa; LIN Qiujin; ZHENG Hongbo; LIU Yingchun

    2009-01-01

    Layer-block tectonics (LBT) concept, with the core of pluralistic geodynamic outlook and multi-layer-sliding tectonic outlook, is one of new keys to study 3-dimensional solid and its 4-dimensional evolution history of global tectonic system controlled by global geodynamics system. The LBT concept is applied to study the lithospheric tectonics of the southern South China Sea (SCS). Based on the analysis of about 30 000 km of geophysical and geological data, some layer-blocks in the Nansha micro-plate can be divided as Nansha ultra-crustal layer-block, Zengmu crustal layer-block, Nanwei (Rifleman bank)-Andu (Ardasier bank) and Liyue (Reed bank)-North Palawan crustal layer-blocks, Andu-Bisheng and Liyue-Banyue basemental layer-blocks. The basic characteristics of the basemental layer-blocks have been dicussed, and three intra-plate basin groups are identified. The intra-plate basins within Nansha micro-plate can be divided into three basin groups of Nanwei-Andu, Feixin-Nanhua, and Liyue-North Palawan based on the different geodynamics. In the light of pluralistic geodynamic concept, the upheaving force induced by the mid-crust plastic layer is proposed as the main dynamical force which causes the formation of the intra-plate basins within the Nansha micro-plate. Finally, models of a face-to-face dip-slip-detachment of basemental layer-block and a unilateral dip-slip-detachment of basemental layer-block are put forward for the forming mechanisms of the Nanwei-Andu and Liyue-North Palawan intra-plate basin groups, respectively.

  13. Late Cretaceous-Cenozoic Evolution of the Central Andean Foreland Basin System in the Eastern Cordillera to Subandean Zone, Southern Bolivia

    Science.gov (United States)

    Calle, A.; Horton, B. K.; Anderson, R. B.; Long, S. P.

    2015-12-01

    Evaluation of foreland basin deposystems and provenance across southern Bolivia reveals punctuated growth of the central Andean orogenic wedge. New and published sedimentology, provenance data, stratigraphy, subcrop mapping, and apatite (U-Th)/He thermochronometry along two transects (19.5, 21°S) from the easternmost Eastern Cordillera (EC) to the western Subandean Zone (SAZ) shed light on Late Cretaceous-Miocene thrust belt and foreland basin dynamics. Sediment dispersal patterns are constrained by paleocurrents, detrital zircon U-Pb geochronology, sandstone petrography, and conglomerate clast compositions. Spatial and temporal changes in the Andean thrust belt are recorded in asymmetric foreland basin thicknesses, facies distributions, and provenance within the EC (Incapampa and Camargo synclines) and SAZ (El Rosal and Entre Rios synclines). The >4 km uppermost Cretaceous-lower Miocene EC succession and ~2.5 km upper Oligocene-Miocene SAZ clastic successions record a shift from fluvial backbulge to pedogenic forebulge deposition. Braided, meandering, and lacustrine foredeep deposition records the most-rapid subsidence, with a later shift to progradational braided and alluvial fan deposition in the wedge-top zone. Growth strata preserved in EC and SAZ wedge-top deposits suggest unsteady eastward advance of the deformation front. Distal foreland deposits show west-directed paleocurrents with >1 Ga detrital zircon populations. Emerging Andean sources are indicated by east-directed paleocurrents, 36-25 Ma), Interandean Zone (IAZ, ~22-7 Ma) and SAZ (<6 Ma) can be linked to eastward passage of a flexural forebulge, recorded as a 50-200 m thick condensed zone in EC and SAZ basin fill. Integrated assessment of basin architecture, provenance, and exhumation highlights the potential influence of pre-Cenozoic IAZ heterogeneities on orogenic wedge growth.

  14. How to solve the technical problems in CBM development: A case study of a CBM gas reservoir in the southern Qinshui Basin

    Directory of Open Access Journals (Sweden)

    Qingzhong Zhu

    2015-03-01

    Full Text Available The low average single-well production, resulting in low economic benefit, has become the main bottleneck of CBM development in China. In view of this issue, through case study of a CBM gas reservoir in the southern Qinshui Basin, we summarized the present status of CBM technology and development there and also pointed out some major problems in CBM development: (1 the engineering technology for the CBM development needs to adapt to the particular geological characteristics; (2 a large number of inefficient zones still exist in mature blocks in the southern Qinshui Basin; (3 single-well production can not be effectively enhanced only by increasing the fracturing scale; (4 the production of multi-lateral wells is higher, but the fulfillment rate of production capacity overall is still low; and (5 on-site management lacks scientific evidence. On this basis, we present the following suggestions for subsequent coalbed gas development: (1 the production construction mode should be changed, and the fulfillment rate of production capacity construction should be improved; (2 CBM geological research should be improved and well types and locations should be designed reasonably and scientifically; (3 main technologies should be built in a dialectical thinking mode; (4 horizontal well design should be optimized to improve the applicability of relevant technologies; (5 fracturing mode should be changed to improve single-well production; and (6 the drainage technology should be changed to improve economic efficiency.

  15. Genetic divergence in populations of Lutzomyia ayacuchensis, a vector of Andean-type cutaneous leishmaniasis, in Ecuador and Peru.

    Science.gov (United States)

    Kato, Hirotomo; Cáceres, Abraham G; Gomez, Eduardo A; Mimori, Tatsuyuki; Uezato, Hiroshi; Hashiguchi, Yoshihisa

    2015-01-01

    Haplotype and gene network analyses were performed on mitochondrial cytochrome oxidase I and cytochrome b gene sequences of Lutzomyia (Lu.) ayacuchensis populations from Andean areas of Ecuador and southern Peru where the sand fly species transmit Leishmania (Leishmania) mexicana and Leishmania (Viannia) peruviana, respectively, and populations from the northern Peruvian Andes, for which transmission of Leishmania by Lu. ayacuchensis has not been reported. The haplotype analyses showed higher intrapopulation genetic divergence in northern Peruvian Andes populations and less divergence in the southern Peru and Ecuador populations, suggesting that a population bottleneck occurred in the latter populations, but not in former ones. Importantly, both haplotype and phylogenetic analyses showed that populations from Ecuador consisted of clearly distinct clusters from southern Peru, and the two populations were separated from those of northern Peru.

  16. New insight on the water management in Ica Valley-Peru

    Science.gov (United States)

    Guttman, Joseph; Berger, Diego

    2014-05-01

    The Andes divide Peru into three natural drainage basins: Pacific basin, Atlantic basin and Lake Titicaca basin. According to the National Water Authority (ANA), the Pacific basin is the driest basin. The bulk of water that feed the local aquifers in the coastal Pacific region is coming from rivers that flow west from the Andes. One of them is the Ica River- source of the Ica Aquifer and the Pampas de Villacuri Aquifer. The Ica River flows in a graben that was created by a series of faults. The graben is filled with sand and gravel with interbeded and lenses of clay. The aquifer thickness varies between 25 meters to more than 200 meters. The Ica Valley has an extension of 7700 km2 and belongs to the Province of Ica, the second larger economic center in Peru. The Valley is located in the hyperarid region of the Southern Coastal area of Peru with a few millimeters of precipitation per year. The direct recharge is almost zero. The recharge into the Ica Valley aquifer is comes indirectly by infiltration of storm water through the riverbed generates in the Andes, through irrigation canals and by irrigation return flow. In this hyperarid region, local aquifers like the Ica Valley are extremely valuable resources to local populations and are the key sources of groundwater for agriculture and population needs. Therefore, these aquifers play a crucial role in providing people with water and intense attention should be given to manage the water sector properly and to keep the aquifer sustainable for future generations. The total pumping (from rough estimations) is much greater than the direct and indirect recharge. The deficit in the water balance is reflected in large water level decline, out of operation of shallow wells and the ascending of saline water from deeper layers. The change from flood irrigation that contributes about 35-40% of the water to the aquifer, to drip irrigation dramatically reduces the amount of water that infiltrates into the sub-surface from the

  17. The Messinian early Pliocene stratigraphic record in the southern Bajo Segura Basin (Betic Cordillera, Spain): Implications for the Mediterranean salinity crisis

    Science.gov (United States)

    Soria, Jesús M.; Caracuel, Jesús E.; Corbí, Hugo; Dinarès-Turell, Jaume; Lancis, Carlos; Tent-Manclús, José E.; Viseras, César; Yébenes, Alfonso

    2008-01-01

    The analysis of the Messinian and Pliocene stratigraphy of the southern Bajo Segura Basin (Betic Cordillera, Spain) has revealed three highstand sedimentary phases (Messinian I, Messinian II, and Pliocene) bounded by two lowstand erosional surfaces (intra-Messinian and end-Messinian unconformities). The Messinian I highstand phase is characterized by the progradation of coastal and shallow marine sandstones (La Virgen Fm) over slope and pelagic-basin marls (Torremendo Fm). After this first phase, a fall in sea level brought about the intra-Messinian unconformity, a subaerial erosional surface with local accumulations of karstic breccias and caliche-like carbonate crusts. The Messinian II highstand phase is represented by sandy beaches and muddy lagoons (Garruchal Fm) correlative with shallow marine evaporites (San Miguel Fm); this second phase records the intra-Messinian reflooding of the basin, which characterizes the salinity crisis in the marginal basins of the Mediterranean. A new sea-level fall resulted in the end-Messinian unconformity, of which the most significant feature is the presence of a broad palaeovalley, c. 200 m deep, which, along its course, completely eroded the deposits of the Messinian II phase and part of the deposits of the Messinian I phase. The Pliocene highstand phase begins with coastal and shallow marine conglomerates and sandstones (La Pedrera Fm) which fill the deep part of the above-mentioned palaeovalley. These bottom deposits evolved gradually upwards towards pelagic marls (Hurchillo Fm), over which shallow marine and coastal sandstones prograded (Rojales Fm). This third phase records the flooding of the basin at the beginning of the Pliocene, when the salinity crisis ended in the marginal basins of the Mediterranean. The combination of calcareous nannoplankton biostratigraphy and magnetostratigraphy has confirmed that both the end of the sedimentation of the Messinian I phase, as well as the two lowstand erosional surfaces (intra

  18. Optica Precolombina Del Peru

    CERN Document Server

    Lunazzi, J J

    2007-01-01

    Archaeological American mirrors are common findings and the images obtained with them are often described by archaeologists as possessing high quality. However, photographs attesting this fact are rare, if any. To the best of my knowledge, only two papers show that quality concerning the Olmeca culture, and only one of them mentions the pre-Inca cultures case. Certainly more images are needed to increase awareness of the importance of the existence of sophisticated imaging elements, particularly when evaluating the cultural degree of the pre-Columbian civilizations. In this paper we show images made in two museums in Lima, Peru, by means of mirrors and the lens action on a necklace element.

  19. The Arequipa (Peru) earthquake of June 23, 2001

    Science.gov (United States)

    Tavera, H.; Buforn, E.; Bernal, I.; Antayhua, Y.; Vilacapoma, L.

    The Arequipa earthquake of 23 June 2001 hasbeen the largest earthquake (Mw = 8.3)occurredin the last century in southern Peru with amaximum intensity of VIII (MM scale). Focalmechanisms of main shock and three largeraftershocks have been studied, showingthrusting solutions for main shock and twoaftershocks and normal motion for the eventof July, 5. The rupture area has beenobtained from distribution of aftershocks.The occurrence of the Arequipa earthquakeis related with the convergence processbetween the Nazca and South Americaplates.

  20. Selected examples of needs for long term pilot areas in Mediterranean catchments: a mountain traditional agricultural system and a large and regulated hydrographic basin in Southern Spain

    Science.gov (United States)

    José Polo, María; Herrero, Javier; Millares, Agustín; José Pérez-Palazón, María; Pimentel, Rafael; Aguilar, Cristina; Jurado, Alicia; Contreras, Eva; Gómez-Beas, Raquel; Carpintero, Miriam; Gulliver, Zacarías

    2015-04-01

    Integrated River Basin Management (IRBM) aims at planning water, land and other natural resources for an equitable and sustainable management, also capable of preserving or restoring freshwater ecosystems. Long term series of significant variables at different scales and a sound knowledge of the river basin processes are needed to establish the current state and past&future evolution of the hydrological system, soil use and vegetation distribution, and their social impacts and feedbacks. This is particularly crucial if future scenario analyses are to be performed to assess decision-making processes and adaptive plans. This work highlights the need for an adequate design and development of process-oriented monitoring systems at the basin scale in a decision-making framework. First, the hydrologic monitoring network of the Guadalfeo River Basin, in the southern face of Sierra Nevada Range (Spain), is shown, in a pilot catchment of 1300 km2 in which snow processes in Mediterranean conditions have been studied over the last ten years with a holistic approach. The network development and the main features of the dataset are described together with their use for different scientific and environmental applications; their benefits for assessing social and economic impact in the rural environment are shown from a study case in which the sustainability of ancient channels fed by snowmelt, in use since the XIIIth century for traditional irrigated crops in the mountainous area, was assessed in a future scenarios analyses. Secondly, the standard flow and water quality monitoring networks in the Guadalquivir River Basin, a large (57400 km2) and highly regulated agricultural catchment in southern Spain, are shown, and their strengths and weaknessess for an IRBM framework are analysed. Sediments and selected pollutants are used to trace soil erosion and agricultural/urban exports throughout the catchment, and the final loads to the river estuary in the Atlantic Ocean are assessed

  1. Detrital Zircon Provenance Record of Pre-Andean to Modern Tectonics in the Northern Andes: Examples from Peru, Ecuador, and Colombia

    Science.gov (United States)

    George, S. W. M.; Jackson, L. J.; Horton, B. K.

    2015-12-01

    Detrital zircon U-Pb age distributions from modern rivers and Mesozoic-Cenozoic basin fill in the northern Andes provide insights into pre-Andean, Andean, and active uplift and exhumation of distinctive sediment source regions. Diagnostic age signatures enable straightforward discrimination of competing sediment sources within the Andean magmatic arc (Western Cordillera-Central Cordillera), retroarc fold-thrust belt (Eastern Cordillera-Subandean Zone), and Amazonian craton (composed of several basement provinces). More complex, however, are the mid/late Cenozoic provenance records generated by recycling of basin fill originally deposited during early/mid Mesozoic extension, late Mesozoic thermal subsidence, and early Cenozoic shortening. Although subject to time-transgressive trends, regionally significant provenance patterns in Peru, Ecuador, and Colombia reveal: (1) Triassic-Jurassic growth of extensional subbasins fed by local block uplifts (with commonly unimodal 300­-150 Ma age peaks); (2) Cretaceous deposition in an extensive postrift setting fed by principally cratonic sources (with common 1800-900 Ma ages); and (3) Cenozoic growth of a broad flexural basin fed initially fed by magmatic-arc rocks (100-0 Ma), then later dominance by thrust-belt sedimentary rocks with progressively greater degrees of basin recycling (yielding diverse and variable age populations from the aforementioned source regions). U-Pb results from modern rivers and smaller subbasins prove useful in evaluating source-to-sink relationships, downstream mixing relationships, hinterland-foreland basin connectivity, paleodrainage integration, and tectonic/paleotopographic reconstructions. Most but not all of the elevated intermontane basins in the modern hinterland of the northern Andes contain provenance records consistent with genesis in a broader foreland basin developed at low elevation. Downstream variations within modern axial rivers and Cenozoic axial basins inform predictive models of

  2. MESOZOIC TECTONIC EVOLUTION AND PROTOTYPE BASIN CHARACTERS IN THE SOUTHERN EAST CHINA SEA SHELF BASIN%东海陆架盆地南部中生代构造演化与原型盆地性质

    Institute of Scientific and Technical Information of China (English)

    杨长清; 杨传胜; 李刚; 廖晶; 龚建明

    2012-01-01

    东海陆架盆地南部夹持于欧亚板块、太平洋板块与印度板块之间,是发育在前中生代基础之上的中、新生代叠合盆地.其构造演化爱古太平洋板块俯冲及特提斯一喜马拉雅构造域的联合影响,经历了印支末期基隆运动、燕山期渔山和雁荡运动的叠加改造.结合浙闽隆起带中生代火成岩事件、盆地构造变形、沉积学的一些证据,通过海陆对比研究,认为东海陆架盆地南部早—中三叠世可能为面向古太平洋的被动大陆边缘盆地;晚三叠世—侏罗纪古太平洋板块已对中国大陆有较强的俯冲作用,东海陆架盆地及南部原型盆地为活动大陆边缘弧前盆地;白垩纪受控于滨海断裂表现为活动大陆边缘走滑拉分盆地;古新世—始新世火山岛弧向东移动,东海陆架变为弧后裂谷盆地.%The Southern East China Sea Shelf Basin is a Mesozoic-Cenozoic superimposed basin developed on the pre-Mesozoic basement at the junction of the Eurasian, Pacific and Indian plates. It has experienced the superimposed deformations of the Jilong, Yushan and Yandang movements and the tectonic evolution is obviously influenced by both the subduction of the Paleo-Pacific plate and the Thethys-Himalayas Tectonic Domain. Studies of Mesozoic igneous events, basin tectonic deformation, sedimentology and comparative study between land and sea have been carried out in this region. Results suggest that the Southern East China Sea Shelf Basin might be a passive continental margin basin facing the Paleo-Pacific in Early-Middle Triassic: a fore-arc basin along the active ocean margin while the Paleo-Pacific Plate intensely subducted under the East Asia continent in Late-Triassic and Jurassic: a strike-slip pull apart basin controlled by the offshore Fault in the Cretaceous and a backarc rift basin in Palaeocene-Eocene when volcanic arc migrated eastwards.

  3. The flux and recovery of bioactive substances in the surface sediments of deep basins off southern California

    Energy Technology Data Exchange (ETDEWEB)

    Jahnke, R.A.

    1990-06-11

    Sediment microbial community biomass and activity in Santa Monica Basin, a nearshore basin in the California Continental Borderland, were examined in October 1985, 1986 and 1987, May 1986, April 1987 and January 1990. Millimeter-scale ATP profiles and incubation of intact cores with {sup 3}H-adenine indicated a high-biomass interface microbial population in the low-oxygen central basin, which was absent in samples from the basin slope sediments. A majority of microbial activity and organic matter mineralization occurred in the top cm of sediment. Comparison of measured ATP and total organic carbon profiles suggest that the C:ATP ratio (wt:wt) ranges between 47:1 and 77:1 in central basin interfacial populations, substantially lower than reported for other aquatic environments. Carbon production estimated from DNA synthesis measurements via {sup 3}H-adenine incorporation was compared with TCO{sub 2} fluxes measured by in situ benthic chamber experiments. Within the uncertainty of the C:ATP ratio, an overall microbial carbon assimilation efficiency of 75--90% was indicated. The low C:ATP ratios and high carbon assimilation efficiencies significantly affect estimates of microbial growth and respiration and are substantially different than those often assumed in the literature. These results suggest that without independent knowledge of these ratios, the uncertainty in tracer-derived microbial growth and respiration rates may be larger than previously reported. 66 refs., 8 figs., 3 tabs.

  4. Astrology in seventeenth-century Peru.

    Science.gov (United States)

    Brosseder, Claudia

    2010-06-01

    This article discusses three aspects of the history of astrology in seventeenth-century Peru that are of larger interest for the history of science in Latin America: Creole concerns about indigenous idolatry, the impact of the Inquisition on natural philosophy, and communication between scholars within the Spanish colonies and the transatlantic world. Drawing mainly on the scholars Antonio de la Calancha, Juan de Figueroa, and Ruiz de Lozano, along with several Jesuits, the article analyzes how natural and medical astrology took shape in Peru and how they fostered astronomical investigations of the southern skies. While natural and medical astrology, showing New and Old World influences, oscillated between orthodoxy and heterodoxy, and between scholasticism and new science, judicial astrology remained undeveloped. Toward the end of the seventeenth century the discourse about astrology took an unexpected turn, reflecting a newly invigorated moral and Christian reading of the heavens that was in part a response to a deep-rooted dissatisfaction with the failure of the extirpation of idolatry campaigns. Inscribing divine and cardinal virtues, the Virgin Mary, Christian saints, and Greco-Roman allegories into the heavens was considered a way to finally solve the problem of idolatry and to convey Creole greatness.

  5. Simulated effects of proposed ground-water pumping in 17 basins of east-central and southern Nevada

    Science.gov (United States)

    Schaefer, D.H.; Harrill, J.R.

    1995-01-01

    The Las Vegas Valley Water District filed 146 applications in 1989 to pump about 180,800 acre- ft/yr in 17 basins for use in Las Vegas Valley. A previously constructed, two-layer computer model of the carbonate-rock province area was configured to simulate transient conditions and used to develop first approximations of the possible effects of these withdrawals. Simulations were made using the phased pumping schedule proposed by the water district. Ground-water-level declines of several hundred feet could ultimately develop in the basins scheduled to supply most of the pumped ground water. Simulated declines in the carbonate-rock aquifer were somewhat larger than simulated declines in the overlying basin-fill deposits. Decreases in simulated regional spring flow were shown in several cells including those representing the Muddy River Springs, Hiko-Crystal-Ash spring area, and the Ash Meadows spring area. Model simulations show flow decreases of about 11 percent, 14 percent, and 2 percent, respectively, at these springs after almost 100 years of pumping. Simulated evapotranspiration also decreased in many basins, with the largest decreases occurring in the basins where ground-water withdrawals were greatest. These basins include Railroad, Spring, and Snake Valleys. The largest decrease in simulated evapotranspiration occurred in Railroad Valley, 64 percent after almost 100 years of pumpage. Model-sensitivity tests indicate that long-term results were relatively insensitive to variations in values used for aquifer storage. The adequacy of the model to simulate the effects of this proposed pumping will remain untested until actual pumping stresses have been in place long enough to cause measurable effects within the system.

  6. COMPETITIVENESS TEXTILE CLUSTER PERU MEXICO

    OpenAIRE

    Gutiérrez Huby, Ana María; Facultad de Ciencias Contables, Universidad Nacional Mayor de San Marcos; Amador Murguía, María Eugenia; Universidad de Guadalajara

    2014-01-01

    This article is a summary of the research study entitled "A comparative study in Peru- Mexico textile cluster in determining competitive strategies" that was developed in 2010 by the author in collaboration with a team of researchers at the University of Guadalajara. This article basically presents the results in comparative terms of the competitive situation of the textile cluster, Peru and Mexico, "Gamarra" and "Zapotlanejo" respectively representing the textile industry in their countries,...

  7. Identification and simulation of space–time variability of past hydrological drought events in the Limpopo River basin, southern Africa

    NARCIS (Netherlands)

    Trambauer, P.; Maskey, S.; Werner, M.; Pappenberger, F.; Van Beek, L.P.H.; Uhlenbrook, S.

    2014-01-01

    Droughts are widespread natural hazards and in many regions their frequency seems to be increasing. A finer-resolution version (0.05° × 0.05°) of the continental-scale hydrological model PCRaster Global Water Balance (PCR-GLOBWB) was set up for the Limpopo River basin, one of the most water-stressed

  8. THE SEQUENCE OF PALEOENVIRONMENTAL CHANGES SINCE ABOUT 4KA B. P., RECORDED BY NIYA SECTION IN SOUTHERN MARGIN OF TARIM BASIN

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Through synthetic researches of multi-index geological records of Niya section, which are of high resolu tion in southern margin of Tarim Basin, this paper has reconstructed the sequences of paleoclimate in this region during historical times (since about 4000a B. P. ). During the last 4000 years, the area has experienced alternations of rela tive cold-moisture and relative warm-dry periods. Three evident cold-moisture periods and three warm-dry periods are identi fing. The study shows that the human activities have an intimate relation with the evolution of paleoclimate in the south ern Xinjiang. Paleoclimate has played very important role in influencing human being′s agricultural activities.

  9. ALLOSTRATIGRAPHY AND SEISMIC STRATIGRAPHY OF THE MIOCENE SEDIMENTS OF THE SPICCHIAIOLA - POMARANCE AREA, SOUTHERN SIDE OF THE VOLTERRA BASIN (TUSCANY, ITALY

    Directory of Open Access Journals (Sweden)

    ALESSANDRO BOSSIO LUCA MARIA FORESI

    1997-11-01

    Full Text Available The objective of this work is to analyze the Miocene depositional units of the southern side of the Volterra Basin (Tuscany, Italy utilizing outcrop and seismic data and to establish the major events that led to their formation. Four depositional units have been recognized: Unit 1 is characterized by marine sediments of late Serravallian-early Tortonian age; Unit 2 is characterized by fluvio-lacustrine and brackish deposits of late Tortonian-early Messinian age; Unit 3 is characterized by marine deposits of early Messinian age; Unit 4 is characterized by the lacustrine deposits ("Lago-mare" facies of late Messinian age. The deposition of these four units is associated with an extensional tectonic regime that has been active in Tuscany since the late Tortonian. This regime generated half graben type structures in which deposition occurred. The recognized unconformities between the units are mainly related to uplift as a consequence of the extensional tectonic regime.    

  10. Quatro especies nuevas de nematodos del sur del Perú y redescripción de Hedruris Orestiae Moniez, 1889 Four new species of nematodes from southern Peru, with a redescription of Hedruris orestiae Moniez, 1889

    Directory of Open Access Journals (Sweden)

    Nicanor Ibâñez H.

    1976-01-01

    Full Text Available En el estudio helmintológico de anfibios del género Telmatobius Wiegmann, 1834, y del pez Orestias luteus Valenciennes, 1839, de las zonas de Arequipa, Puno y del Lago Titicaca, se han encontrado nematodes de los géneros Hedruris Nitzsch, 1821 y Falcaustra Lane, 1915. Se redescribe Hedruris orestiae Moniez, 1889 y se describen cuatro especies nuevas: Hedruris moniezi sp. n., Falcaustra condorcanquii sp. n., Falcaustra pumacahuai sp. n. y Falcaustra tiahuanaquensis sp. n.The collection of large numbers of nematodes from amphibians (Telmatobius sp. and fish Orestias luteus Valenciennes, 1839 Arequipa, Puno, and Titicaca Lake in South Peru has made possible the revision of one species and the description of our new species: Hedruris orestiae Moniez, 1889 is re-described; Hedruris moniezi sp. n., Falcaustra condorcanquii sp. n., Falcaustra pumacahuai sp. and Falcaustra tiahuanaquensis sp. n. are described.

  11. Inhalants in Peru.

    Science.gov (United States)

    Lerner, R; Ferrando, D

    1995-01-01

    In Peru, the prevalence and consequences of inhalant abuse appear to be low in the general population and high among marginalized children. Inhalant use ranks third in lifetime prevalence after alcohol and tobacco. Most of the use appears to be infrequent. Among marginalized children, that is, children working in the streets but living at home or children living in the street, the problem of inhalant abuse is a serious problem. Among children working in the streets but living at home, the lifetime prevalence rate for inhalant abuse is high, ranging from 15 to 45 percent depending on the study being cited. For children living in the streets, the use of inhalant is even more severe. As mentioned earlier in this chapter, most of these street children use inhalants on a daily basis. The lack of research on the problem of inhalant abuse is a serious impediment to development of intervention programs and strategies to address this problem in Peru. Epidemiologic and ethnographic research on the nature and extent of inhalant abuse are obvious prerequisites to targeted treatment and preventive intervention programs. The urgent need for current and valid data is underscored by the unique vulnerability of the youthful population at risk and the undisputed harm that results from chronic abuse of inhalants. Nonetheless, it is important to mention several programs that work with street children. Some, such as the Information and Education Center for the Prevention of Drug Abuse, Generation, and Centro Integracion de Menores en Abandono have shelters where street children are offered transition to a less marginal lifestyle. Teams of street educators provide the children with practical solutions and gain their confidence, as well as offer them alternative socialization experiences to help them survive the streets and avoid the often repressive and counterproductive environments typical of many institutions. Most of the children who go through these programs tend to abandon

  12. Identification and simulation of space-time variability of past hydrological drought events in the Limpopo river basin, Southern Africa

    Directory of Open Access Journals (Sweden)

    P. Trambauer

    2014-03-01

    droughts in the Limpopo river basin in the period 1979–2010 with a view to identifying severe droughts that have occurred in the basin. Evaporation, soil moisture, groundwater storage and runoff estimates from the model were derived at a spatial resolution of 0.05° (approximately 5 km on a daily time scale for the entire basin. PCR-GLOBWB was forced with daily precipitation, temperature and other meteorological variables obtained from the ERA-Interim global atmospheric reanalysis product from the European Centre for Medium-Range Weather Forecasts. Two agricultural drought indicators were computed: the Evapotranspiration Deficit Index (ETDI and the Root Stress Anomaly Index (RSAI. Hydrological drought was characterised using the Standardized Runoff Index (SRI and the Groundwater Resource Index (GRI, which make use of the streamflow and groundwater storage resulting from the model. Other more widely used drought indicators, such as the Standardized Precipitation Index (SPI and the Standardized Precipitation Evaporation Index (SPEI were also computed for different aggregation periods. Results show that a carefully set up process-based model that makes use of the best available input data can successfully identify hydrological droughts even if the model is largely uncalibrated. The indicators considered are able to represent the most severe droughts in the basin and to some extent identify the spatial variability of droughts. Moreover, results show the importance of computing indicators that can be related to hydrological droughts, and how these add value to the identification of droughts/floods and the temporal evolution of events that would otherwise not have been apparent when considering only meteorological indicators. In some cases, meteorological indicators alone fail to capture the severity of the drought. Therefore, a combination of some of these indicators (e.g. SPEI-3, SRI-6, SPI-12 is found to be a useful measure for identifying hydrological droughts in

  13. Tectono-thermal History of the Southern Nenana Basin, Interior Alaska: Implications for Conventional and Unconventional Hydrocarbon Exploration

    Science.gov (United States)

    Dixit, N. C.; Hanks, C. L.

    2014-12-01

    The Tertiary Nenana basin of Interior Alaska is currently the focus of both new oil exploration and coalbed methane exploitation and is being evaluated as a potential CO2sequestration site. The basin first formed as a Late Paleocene extensional rift with the deposition of oil and gas-prone, coal-bearing non-marine sediments with excellent source potential. Basin inversion during the Early Eocene-Early Oligocene times resulted in folding and erosion of higher stratigraphic levels, forming excellent structural and stratigraphic traps. Initiation of active faulting on its eastern margin in the middle Oligocene caused slow tectonic subsidence that resulted in the deposition of reservoir and seal rocks of the Usibelli Group. Onset of rapid tectonic subsidence in Pliocene that continues to the present-day has provided significant pressure and temperature gradient for the source rocks. Apatite fission-track and vitrinite reflectance data reveals two major paleo-thermal episodes: Late Paleocene to Early Eocene (60 Ma to 54.8 Ma) and Late Miocene to present-day (7 Ma to present). These episodes of maximum paleotemperatures have implications for the evolution of source rock maturity within the basin. In this study, we are also investigating the potential for coalbed methane production from the Late Paleocene coals via injection of CO2. Our preliminary analyses demonstrate that 150 MMSCF of methane could be produced while 33000 tonnes of CO2 per injection well (base case of ~9 years) can be sequestered in the vicinity of existing infrastructure. However, these volumes of sequestered CO2and coal bed methane recovery are estimates and are sensitive to the reservoir's geomechanical and flow properties. Keywords: extensional rift, seismic, subsidence, thermal history, fission track, vitrinite reflectance, coal bed methane, Nenana basin, CO2 sequestration

  14. Serological evidence for Saint Louis encephalitis virus in free-ranging New World monkeys and horses within the upper Paraná River basin region, Southern Brazil

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    Walfrido Kühl Svoboda

    2014-06-01

    Full Text Available Introduction Saint Louis encephalitis virus (SLEV primarily occurs in the Americas and produces disease predominantly in humans. This study investigated the serological presence of SLEV in nonhuman primates and horses from southern Brazil. Methods From June 2004 to December 2005, sera from 133 monkeys (Alouatta caraya, n=43; Sapajus nigritus, n=64; Sapajus cay, n=26 trap-captured at the Paraná River basin region and 23 blood samples from farm horses were obtained and used for the serological detection of a panel of 19 arboviruses. All samples were analyzed in a hemagglutination inhibition (HI assay; positive monkey samples were confirmed in a mouse neutralization test (MNT. Additionally, all blood samples were inoculated into C6/36 cell culture for viral isolation. Results Positive seroreactivity was only observed for SLEV. A prevalence of SLEV antibodies in sera was detected in Alouatta caraya (11.6%; 5/43, Sapajus nigritus (12.5%; 8/64, and S. cay (30.8%; 8/26 monkeys with the HI assay. Of the monkeys, 2.3% (1/42 of A. caraya, 6.3% 94/64 of S. nigritus, and 15.4% (4/26 of S. cay were positive for SLEV in the MNT. Additionally, SLEV antibodies were detected by HI in 39.1% (9/23 of the horses evaluated in this study. Arboviruses were not isolated from any blood sample. Conclusions These results confirmed the presence of SLEV in nonhuman primates and horses from southern Brazil. These findings most likely represent the first detection of this virus in nonhuman primates beyond the Amazon region. The detection of SLEV in animals within a geographical region distant from the Amazon basin suggests that there may be widespread and undiagnosed dissemination of this disease in Brazil.

  15. Potential field studies of the central San Luis Basin and San Juan Mountains, Colorado and New Mexico, and southern and western Afghanistan

    Science.gov (United States)

    Drenth, Benjamin John

    This dissertation includes three separate chapters, each demonstrating the interpretive utility of potential field (gravity and magnetic) geophysical datasets at various scales and in various geologic environments. The locations of these studies are the central San Luis Basin of Colorado and New Mexico, the San Juan Mountains of southwestern Colorado, and southern and western Afghanistan. The San Luis Basin is the northernmost of the major basins that make up the Rio Grande rift, and interpretation of gravity and aeromagnetic data reveals patterns of rifting, rift-sediment thicknesses, distribution of pre-rift volcanic and sedimentary rocks, and distribution of syn-rift volcanic rocks. Syn-rift Santa Fe Group sediments have a maximum thickness of ˜2 km in the Sanchez graben near the eastern margin of the basin along the central Sangre de Cristo fault zone. Under the Costilla Plains, thickness of these sediments is estimated to reach ˜1.3 km. The Santa Fe Group sediments also reach a thickness of nearly 1 km within the Monte Vista graben near the western basin margin along the San Juan Mountains. A narrow, north-south-trending structural high beneath San Pedro Mesa separates the graben from the structural depression beneath the Costilla Plains. Aeromagnetic anomalies are interpreted to mainly reflect variations of remanent magnetic polarity and burial depth of the 5.3-3.7 Ma Servilleta basalt of the Taos Plateau volcanic field. Magnetic-source depth estimates indicate patterns of subsidence following eruption of the basalt and show that the Sanchez graben has been the site of maximum subsidence. One of the largest and most pronounced gravity lows in North America lies over the rugged San Juan Mountains in southwestern Colorado. A buried, low-density silicic batholith related to an Oligocene volcanic field coincident with the San Juan Mountains has been the accepted interpretation of the source of the gravity low since the 1970s. However, this interpretation was

  16. Thermal evolution of the Sisters shear zone, southern New Zealand; Formation of the Great South Basin and onset of Pacific-Antarctic spreading

    Science.gov (United States)

    Kula, Joseph; Tulloch, Andy J.; Spell, Terry L.; Wells, Michael L.; Zanetti, Kathleen A.

    2009-10-01

    The separation of Zealandia from West Antarctica was the final stage in the Cretaceous breakup of the Gondwana Pacific margin. Continental extension resulting in formation of the Great South Basin and thinning of the Campbell Plateau leading to development of the Pacific-Antarctic spreading ridge was partially accommodated along the Sisters shear zone. This east-northeast striking brittle-ductile structure exposed along the southeast coast of Stewart Island, New Zealand, is a greenschist facies extensional shear zone that separates a hanging wall of chloritic, brecciated granites, and undeformed conglomerate from a footwall of mylonitic Carboniferous and Early Cretaceous granites. This complex structure exhibits bivergent kinematics and can be subdivided into a northern and southern segment. The 40Ar/39Ar thermochronology indicates that cooling of the shear zone footwall began at ˜94 Ma with accelerated cooling over the interval ˜89-82 Ma. Structural and thermochronological data indicate a spatial and temporal link between the Sisters shear zone, initial sedimentation within the offshore Great South Basin, extension of the Campbell Plateau, and initiation of the Pacific-Antarctic spreading ridge.

  17. Identification of spatial and temporal contributions of rainfalls to flash floods using neural network modelling: case study on the Lez Basin (Southern France

    Directory of Open Access Journals (Sweden)

    T. Darras

    2015-04-01

    Full Text Available Flash floods pose significant hazards in urbanised zones and have important human and financial implications in both the present and future due to the likelihood that global climate change will exacerbate their consequences. It is thus of crucial importance to better model these phenomena especially when they occur in heterogeneous and karst basins where they are difficult to describe physically. Toward this goal, this paper applies a recent methodology (KnoX methodology dedicated to extracting knowledge from a neural network model to better determine the contributions and time responses of several well-identified geographic zones of an aquifer. To assess the interest of this methodology, a case study was conducted in Southern France: the Lez hydrosystem whose river crosses the conurbation of Montpellier (400 000 inhabitants. Rainfall contributions and time transfers were estimated and analysed in four geologically-delimited zones to estimate the sensitivity of flash floods to water coming from the surface or karst. The Causse de Viol-le-Fort is shown to be the main contributor to flash floods and the delay between surface and underground flooding is estimated to be three hours. This study will thus help operational flood warning services to better characterise critical rainfall and develop measurements to design efficient flood forecasting models. This generic method can be applied to any basin with sufficient rainfall–runoff measurements.

  18. Web application to access U.S. Army Corps of Engineers Civil Works and Restoration Projects information for the Rio Grande Basin, southern Colorado, New Mexico, and Texas

    Science.gov (United States)

    Archuleta, Christy-Ann M.; Eames, Deanna R.

    2009-01-01

    The Rio Grande Civil Works and Restoration Projects Web Application, developed by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers (USACE) Albuquerque District, is designed to provide publicly available information through the Internet about civil works and restoration projects in the Rio Grande Basin. Since 1942, USACE Albuquerque District responsibilities have included building facilities for the U.S. Army and U.S. Air Force, providing flood protection, supplying water for power and public recreation, participating in fire remediation, protecting and restoring wetlands and other natural resources, and supporting other government agencies with engineering, contracting, and project management services. In the process of conducting this vast array of engineering work, the need arose for easily tracking the locations of and providing information about projects to stakeholders and the public. This fact sheet introduces a Web application developed to enable users to visualize locations and search for information about USACE (and some other Federal, State, and local) projects in the Rio Grande Basin in southern Colorado, New Mexico, and Texas.

  19. First record of Lophodinium polylophum (Daday Lemmermann 1910 (Dinophyceae: Lophodiniaceae in Peru

    Directory of Open Access Journals (Sweden)

    Iris Samanez

    2015-04-01

    Full Text Available Herein, the first record of Lophodinium polylophum from Peru is presented. This fresh water dinoflagellate was identified in plankton samples from the lagoon Picoplancha of Santuario Nacional Pampas del Heath (Madre de Dios and from a stream in the Puinahua River basin in Loreto.

  20. Fault-Related CO2 Degassing, Geothermics, and Fluid Flow in Southern California Basins--Physiochemical Evidence and Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Garven, Grant [Tufts University

    2015-08-11

    Our studies have had an important impact on societal issues. Experimental and field observations show that CO2 degassing, such as might occur from stored CO2 reservoir gas, can result in significant stable isotopic disequilibrium. In the offshore South Ellwood field of the Santa Barbara channel, we show how oil production has reduced natural seep rates in the area, thereby reducing greenhouse gases. Permeability is calculated to be ~20-30 millidarcys for km-scale fault-focused fluid flow, using changes in natural gas seepage rates from well production, and poroelastic changes in formation pore-water pressure. In the Los Angeles (LA) basin, our characterization of formation water chemistry, including stable isotopic studies, allows the distinction between deep and shallow formations waters. Our multiphase computational-based modeling of petroleum migration demonstrates the important role of major faults on geological-scale fluid migration in the LA basin, and show how petroleum was dammed up against the Newport-Inglewood fault zone in a “geologically fast” interval of time (less than 0.5 million years). Furthermore, these fluid studies also will allow evaluation of potential cross-formational mixing of formation fluids. Lastly, our new study of helium isotopes in the LA basin shows a significant leakage of mantle helium along the Newport Inglewood fault zone (NIFZ), at flow rates up to 2 cm/yr. Crustal-scale fault permeability (~60 microdarcys) and advective versus conductive heat transport rates have been estimated using the observed helium isotopic data. The NIFZ is an important deep-seated fault that may crosscut a proposed basin decollement fault in this heavily populated area, and appears to allow seepage of helium from the mantle sources about 30 km beneath Los Angeles. The helium study has been widely cited in recent weeks by the news media, both in radio and on numerous web sites.

  1. El-Niño southern oscillation and rainfall erosivity in the headwater region of the Grande River Basin, Southeast Brazil

    Directory of Open Access Journals (Sweden)

    C. R. Mello

    2011-12-01

    Full Text Available Relationships between regional climate and oceanic and atmospheric anomalies are important tools in order to promote the development of models for predicting rainfall erosivity, especially in regions with substantial intra-annual variability in the rainfall regime. In this context, this work aimed to analyze the rainfall erosivity in headwaters of Grande River Basin, Southern Minas Gerais State, Brazil. This study considered the two most representative environments, the Mantiqueira Range (MR and Plateau of Southern Minas Gerais (PSM. These areas are affected by the El Nino Southern Oscillation (ENSO indicators Sea Surface Temperature (SST for Niño 3.4 Region and Multivariate ENSO Index (MEI. Rainfall erosivity was calculated for individual rainfall events from January 2006 to December 2010. The analyses were conducted using the monthly data of ENSO indicators and the following rainfall variables: rainfall erosivity (EI30, rainfall depth (P, erosive rainfall depth (E, number of rainfall events (NRE, number of erosive rainfall events (NEE, frequency of occurrence of an early rainfall pattern (EP, occurrence of late rainfall pattern (LP and occurrence of intermediate rainfall patter (IP. Pearson's coefficient of correlation was used to evaluate the relationships between the rainfall variables and SST and MEI. The coefficients of correlation were significant for SST in the PSM sub-region. Correlations between the rainfall variables and negative oscillations of SST were also significant, especially in the MR sub-region, however, the Person's coefficients were lesser than those obtained for the SST positive oscillations. The correlations between the rainfall variables and MEI were also significant but lesser than the SST correlations. These results demonstrate that SST positive oscillations play a more important role in rainfall erosivity, meaning they were more influenced by El-Niño episodes. Also, these results have shown

  2. Elevation-Dependent Vegetation Greening of the Yarlung Zangbo River Basin in the Southern Tibetan Plateau, 1999–2013

    Directory of Open Access Journals (Sweden)

    Haidong Li

    2015-12-01

    Full Text Available The Yarlung Zangbo River basin is an important alley to transport moisture from the Indian Ocean to the inner Tibetan Plateau. With a wide range of elevations from 147 m to over 7000 m above sea level (a.s.l., ecosystems respond differently to climate change at various elevations. However, the pattern of elevation-dependent vegetation change and how it responds to recent warming have been rarely reported. Here, we investigated the pattern of vegetation greening at different elevations in this river basin using SPOT normalized difference vegetation index (NDVI data during 1999–2013, and examined its relationship with elevation-dependent changes in temperature and precipitation. The annual NDVI has increased by 8.83% from 1999 to 2013. In particular, the NDVI increased more apparently at lower elevations, but remained relatively stable or even decreased at high elevations. It seems that rising temperature has driven the basin-wide vegetation greening, but the greening rate is in contrast to the pattern of elevation-dependent warming (EDW with more significant temperature increase at higher elevations. It appears that decreasing precipitation does not reverse the overall increasing trend in NDVI, but relatively limited precipitation (<500 mm may constrain the NDVI increases, causing apparently stable or even decreased NDVI at higher elevations (>4000 m.

  3. Three-dimensional mathematical model to simulate groundwater flow in the lower Palar River basin, southern India

    Science.gov (United States)

    Senthilkumar, M.; Elango, L.

    A three-dimensional mathematical model to simulate regional groundwater flow was used in the lower Palar River basin, in southern India. The study area is characterised by heavy ion of groundwater for agricultural, industrial and drinking water supplies. There are three major pumping stations on the riverbed apart from a number of wells distributed over the area. The model simulates groundwater flow over an area of about 392 km2 with 70 rows, 40 columns, and two layers. The model simulated a transient-state condition for the period 1991-2001. The model was calibrated for steady- and transient-state conditions. There was a reasonable match between the computed and observed heads. The transient model was run until the year 2010 to forecast groundwater flow under various scenarios of overpumping and less recharge. Based on the modelling results, it is shown that the aquifer system is stable at the present rate of pumping, excepting for a few locations along the coast where the groundwater head drops from 0.4 to 1.81 m below sea level during the dry seasons. Further, there was a decline in the groundwater head by 0.9 to 2.4 m below sea level in the eastern part of the area when the aquifer system was subjected to an additional groundwater withdrawal of 2 million gallons per day (MGD) at a major pumping station. Les modèles mathématiques en trois dimensions de l'écoulement souterrain régional sont très utiles pour la gestion des ressources en eau souterraine, car ils permettent une évaluation des composantes des processus hydrologiques et fournissent une description physique de l'écoulement de l'eau dans un aquifère. Une telle modélisation a été entreprise sur une partie du bassin inférieur de la rivière Palar, dans le sud de l'Inde. La zone d'étude est caractérisée par des prélèvements importants d'eau souterraine pour l'agriculture, l'industrie et l'eau potable. Il existe trois grandes stations de pompage sur la rivière en plus d'un certain nombre

  4. A new bush anole (Iguanidae, Polychrotinae, Polychrus) from the upper Marañon basin, Peru, with a redescription of Polychrus peruvianus (Noble, 1924) and additional information on Polychrus gutturosus Berthold, 1845.

    Science.gov (United States)

    Koch, Claudia; Venegas, Pablo J; Garcia-Bravo, Antonio; Böhme, Wolfgang

    2011-01-01

    We herein describe a new colorful species of Polychrus with a conspicuous sexual dimorphism from the dry forest of the northern portion of Región de La Libertad, Peru. The new species differs from all other Polychrus species, in that this species has very small dorsal scales and thus a higher number of scales around midbody and in the middorsal line from behind the occipital scales to the level of the posterior edge of the thigh. Furthermore, we redescribe Polychrus peruvianus whose original description is short and lacks information on intraspecific variation and sexual dimorphism. Also, we add some information on intraspecific variation and ecology of Polychrus gutturosus. Finally, we synonymize Polychrus spurrelli Boulenger with Polychrus gutturosus.

  5. A new bush anole (Iguanidae, Polychrotinae, Polychrus) from the upper Marañon basin, Peru, with a redescription of Polychrus peruvianus (Noble, 1924) and additional information on Polychrus gutturosus Berthold, 1845

    Science.gov (United States)

    Koch, Claudia; Venegas, Pablo J.; Garcia-Bravo, Antonio; Böhme, Wolfgang

    2011-01-01

    Abstract We herein describe a new colorful species of Polychrus with a conspicuous sexual dimorphism from the dry forest of the northern portion of Región de La Libertad, Peru. The new species differs from all other Polychrus species, in that this species has very small dorsal scales and thus a higher number of scales around midbody and in the middorsal line from behind the occipital scales to the level of the posterior edge of the thigh. Furthermore, we redescribe Polychrus peruvianus whose original description is short and lacks information on intraspecific variation and sexual dimorphism. Also, we add some information on intraspecific variation and ecology of Polychrus gutturosus. Finally, we synonymize Polychrus spurrelli Boulenger with Polychrus gutturosus. PMID:22287882

  6. Sedimentology, rhythmicity and basin-fill architecture of a carbonate ramp depositional system with intermittent terrigenous influx: The Albian Kharfot Formation of the Jeza-Qamar Basin, Dhofar, Southern Oman

    Science.gov (United States)

    Salad Hersi, O.; Abbasi, I. A.; Al-Harthy, A.

    2016-01-01

    which received fine-grained siliciclastic influx from the land (westward). In southern Oman where Kharfot Formation accumulated, the platform was unrimmed ramp type basin with high fine clastic influx along with elevated carbonate production.

  7. Aqueducts and geoglyphs : the response of Ancient Nasca to water shortages in the desert of Atacama (Peru)

    Science.gov (United States)

    Masini, Nicola; Lasaponara, Rosa

    2016-04-01

    The desert of Atacama is a plateau in South America, covering a 1,000-kilometre strip of land on the Pacific coast, west of the Andes mountains, between Chile and Peru. Due to the confluence of a cold ocean current (the Humboldt Current) along with other climatic factors, connected to the particular topography and geomorphology of the region, Atacama desert is one of the most arid areas of the world. In particular, in Nasca region (Southern Peru) the lack of water was (and still is) due to the following causes: (i) the scarce pluvial precipitations and the (ii) high infiltration capacity, and the consequent yearly significant reduction of the surface water (Schreiber & Lancho Rojas 2009). Over the millennia long periods of drought occurred and frequently the lack of water was persistent for several decades. Despite the arid and extreme nature of the environment, this region was populated by important civilizations, such as Paracas and Nasca, which flourished in the Early Intermediate period (200 BCE-500 AD) (Silvermann & Proulx 2002). In particular the Nasca civilization is well-known for its refined and colourful pottery, characterized by a rich icononographic repertory, and, above all, by the huge and mysterious geoglyphs drawn on the arid plateaus of the Rio Grande de Nasca Basin. In order to practice agriculture, the Nasca developed adequate strategies to cope with hostile environmental factors and water scarcity, building a very efficient aqueduct system. They were aided by the fact that underground water was likely enough close to the surface and accessible by constructing wells and underground aqueducts, known with quechua name of puquios (Schreiber & Lancho Rojas 2009; Lasaponara & Masini 2012a; 2012b) The effectiveness of the techniques of hydraulic engineering depended on the climate and the weather events that sometimes underwent drastic changes, as results of the cyclical phenomenon of El Niño Southern Oscillation (commonly called ENSO). Hence the

  8. Pottery from Peru. A Handbook. Second Edition.

    Science.gov (United States)

    Rammage, Alix

    One of three handbooks dealing with pottery traditions from around the world, this packet draws together information about historical, ethnographic, and pottery traditions of Peru. The first of 13 brief subsections focuses on Peru's land and people. A presentation of a potter's history of Peru is followed by a discussion of the Chavin Cult (800…

  9. Is the extension of the Mexican Mesa Central (southern Basin & Range province) related to a gravitational collapse toward the Gulf of Mexico?

    Science.gov (United States)

    Andreani, L.; Rangin, C.; Le Pichon, X.; Martínez-Reyes, J.; Le Roy, C.

    2009-04-01

    The middle to late Cenozoic extension that generated the Basin and Range province (western North America) is one of the most important tectonic events to affect the North American plate. The characteristics of this extension have been extensively studied, but its origin is equally extensively debated. Proposed origins can be broadly categorized into interplate mechanisms that focus on various interactions between the Pacific or Farallon and North American plates and intraplate mechanisms that interpret extension to result from the gravitational collapse of a previously overthickened crust. It is commonly admitted that the Basin and Range extension in western Mexico migrated from East to West toward the Gulf of California. Middle to late Miocene extension around the Gulf of California (Gulf Extensional Province) is commonly interpreted as resulting from partitioning of oblique Pacific-North American plate motion into strike-slip displacement along the margin and ENE extension perpendicular to the margin within the North American plate. It is generally assumed that this mechanism also applies to the kinematically similar, predominantly ENE extension that occurred at the same time throughout the southern Basin and Range province. However structural data we collected in the Mesa Central area, along the eastern part of the Mexican Basin and Range province, argue for a post-27My N130° extension toward the Gulf of Mexico that produced highly asymmetrical grabens, with a major motion along their western flanks. Our recent works, based on the interpretation of seismic profiles, also show that the late Oligocene to present deformation along the western margin of the Gulf of Mexico was generated by a crustal shortening. In spite of a low crustal thickness the Mesa Central is an uplifted plateau with a mean altitude of 1800m. This elevation of the Mesa Central is mainly due to the high thermal gradients that characterize the back arc domain. By contrast the crust of the Gulf

  10. Species composition and phytosociology of xerophytic plant communities after extreme rainfall in South Peru

    NARCIS (Netherlands)

    Montesinos, D.B.; Sykora, K.V.; Quipuscoa-Silvestre, Victor; Cleef, A.M.

    2015-01-01

    Abstract: We present a phytosociological overview of the arid and semi-arid montane vegetation of the province
    of Arequipa in southern Peru. The xerophytic vegetation was studied after extreme rainfall had promoted
    exceptionally lush vegetation and a high aboveground floristic diversity. We

  11. Paleostress analysis applied to fault-slip data from the southern margin of the Central European Basin System (CEBS)

    Energy Technology Data Exchange (ETDEWEB)

    Sippel, J.; Scheck-Wenderoth, M. [GFZ Potsdam (Germany); Reicherter, K. [RWTH Aachen (Germany); Mazur, S. [Wroclaw Univ. (Poland)

    2007-09-13

    We investigate the paleostress fields which controlled the post-Variscan evolution of the Central European Basin System (CEBS). Therefore, field studies are carried out in the marginal areas of the CEBS where Late Palaeozoic and Mesozoic rocks of the basin fill are present in outcrops bearing the imprints of several deformation phases that affected the basin system since the latest Carboniferous. Field studies including structural analysis, measurement of fault-slip data and careful collection of kinematic indicators provide the data base for this study. In the case of polyphase tectonics, the chronology of successive events is deduced and the total fault population from each site is qualitatively divided into different subsets, each being consistent with one specific stress regime. Since the stratigraphy and evolution of the CEBS are well known, temporal and spatial correlations of paleostress orientations are possible. Beside cross-cutting relationships derived from outcrops, we apply different graphical and numerical methods to separate the faults into homogeneous subsets. Depending on (1) the nature of faults (i.e. neoformed or reactivated), (2) the distribution of fault-slip data and (3) the deformation style, the deviatoric stress tensor is calculated for each subset using either the Numeric Dynamic Analysis (Spang, 1972; Sperner et al., 1993) or the Multiple Inverse Method (Yamaji 2000). The results are obtained in terms of a reduced stress tensor, consisting of (1) the orientations of the three principal stress axes {sigma}{sub 1}, {sigma}{sub 2} and {sigma}{sub 3} with {sigma}{sub 1}{>=}{sigma}{sub 2}{>=}{sigma}{sub 3} and (2) the ratio of principal stress differences, R=({sigma}{sub 2}-{sigma}{sub 3})/({sigma}{sub 1}-{sigma}{sub 3}) with 1{>=}{phi}{>=}0. (orig.)

  12. The Mediterranean Basin and Southern Europe in a warmer world: what can we learn from the past?

    Directory of Open Access Journals (Sweden)

    Joel eGuiot

    2015-06-01

    Full Text Available Since the late-nineteenth century, surface temperatures have non-uniformly increased worldwide. The repercussion of the global warming in drylands, such as in the Mediterranean, may become a main source of concern in a near future, as it is often accompanied by increased droughts, that will severely degrade water supply and quality. History shows that access to water resources has always presented a challenge for societies around the Mediterranean throughout the Holocene (roughly the last 10,000 years. Repeatedly, adverse climate shifts seem to have interacted with social, economic and political variables, exacerbating vulnerabilities in drier regions. We present a reconstruction of the Holocene climate in the Mediterranean Basin using an innovative method based on pollen data and vegetation modeling. The method consists in calculating the inputs of the vegetation model so that the outputs fit the pollen data, using a Bayesian framework. This model inversion is particularly suited to deal with increasing dissimilarities between past millennia and the last century, especially due to a direct effect of CO2 on vegetation. The comparison of fardistant past and last century shows that the intensity of century-scale precipitation fall, amplified by higher temperatures and then evapotranspiration, appears to be unmatched over the last 10,000 years and the comparison between west and east precipitation anomalies show a clear see-saw effect through all the Holocene, in particular during the dry episodes of Near and Middle East. As a consequence that Tthe recent climatic change seems thento have been unprecedented during the last 10,000 years in the Mediterranean Basin,.over the next few decades, Mediterranean societies will likely be more critically vulnerable to climate change, than at any dry period of the past. We show also that adverse climate shifts are often correlated with the decline or collapse of Mediterranean civiliszations, particularly in

  13. The 2001-present induced earthquake sequence in the Raton Basin of northern New Mexico and southern Colorado

    Science.gov (United States)

    Rubinstein, Justin L.; Ellsworth, William L.; McGarr, Arthur F.; Benz, Harley M.

    2014-01-01

    We investigate the ongoing seismicity in the Raton Basin and find that the deep injection of wastewater from the coal‐bed methane field is responsible for inducing the majority of the seismicity since 2001. Many lines of evidence indicate that this earthquake sequence was induced by wastewater injection. First, there was a marked increase in seismicity shortly after major fluid injection began in the Raton Basin in 1999. From 1972 through July 2001, there was one M≥4 earthquake in the Raton Basin, whereas 12 occurred between August 2001 and 2013. The statistical likelihood that such a rate change would occur if earthquakes behaved randomly in time is 3.0%. Moreover, this rate change is limited to the area of industrial activity. Earthquake rates remain low in the surrounding area. Second, the vast majority of the seismicity is within 5 km of active disposal wells and is shallow, ranging between 2 and 8 km depth. The two most carefully studied earthquake sequences in 2001 and 2011 have earthquakes within 2 km of high‐volume, high‐injection‐rate wells. Third, injection wells in the area are commonly very high volume and high rate. Two wells adjacent to the August 2011 M 5.3 earthquake injected about 4.9 million cubic meters of wastewater before the earthquake, more than seven times the amount injected at the Rocky Mountain Arsenal well that caused damaging earthquakes near Denver, Colorado, in the 1960s. The August 2011 M 5.3 event is the second‐largest earthquake to date for which there is clear evidence that the earthquake sequence was induced by fluid injection.

  14. Investigation for Uranium Dispersion Adjacent to Cretaceous Phosphatic Outcrops in Al-Nassrieh Basin, Southern Palmyrides, Syria

    Institute of Scientific and Technical Information of China (English)

    Mohamed Al-Hilal; Ahmad Al-Ali

    2016-01-01

    A detailed radiometric survey including soil gas radon measurements and field gamma-ray survey, in accordance with geochemical and geological investigations were carried out in Al-Nassrieh Basin (central Syria), for the purpose of uranium exploration. Thirty-six samples were col-lected from various lithofacies of the survey area and analyzed byγ-ray spectrometric technique for de-termining the concentration values of major radioelements. The relationships between the concentra-tions of equivalent eU, eTh, and their ratios were examined in order to define their trend of variations and evaluate the degree of uranium remobilization and redistribution. Although the initial results indi-cate that uranium enrichment is mostly restricted to the Upper Cretaceous phosphate rocks, a consi-derable portion of uranium appeared to be leached out of the primary phosphatic source and dispersed in the adjacent recent sediments. Further, notable increases of radon level associated with relatively high values of uranium concentration and gamma count rates were found to be spatially correlated with the transition zone between the marine Paleogene and continental Neogene formations throughout the study basin. This observation demonstrates the importance of the concerned zone as a suitable geo-logical environment for hosting probable uranium mineralization along a chemically reducing interface where surface water of terrestrial and marine origin mingled at depth and away from surficial condi-tions.

  15. Accumulation of coal-bed methane in the south-west part of the Upper Silesian Coal Basin (southern Poland)

    Energy Technology Data Exchange (ETDEWEB)

    Kedzior, Slawomir [University of Silesia, Faculty of Earth Science, Bedzinska 60, 41-200 Sosnowiec (Poland)

    2009-10-01

    The archives of the Polish Geological Institute house a wealth of coal-bed methane (CBM) data from surface boreholes and excavations in coal from the deposits of the Upper Silesian Coal Basin (USCB). These data support a model for the origin of substantial methane accumulations in the south-west part of the basin that reflects the interplay of the factors controlling methane sorption capacity and those controlling methane content. The factors controlling the sorption capacity of coal include coal rank, temperature, pressure, moisture content and maceral composition. Methane-content controls include lithology, stratigraphy, tectonics, hydrogeology and mining activity. The nature of the coal-bearing Carboniferous horizons, the sorption/desorption properties of the coals, the disposition of faults and folds, the topography of the Carboniferous palaeosurface and the presence of an impermeable Miocene cover were key controls. The methane accumulated in coal seams and in their host rocks in settings comparable with those in which petroleum and gas deposits are trapped. (author)

  16. Hydrogeological behaviour of the Fuente-de-Piedra playa lake and tectonic origin of its basin (Malaga, southern Spain)

    Science.gov (United States)

    Rodriguez-Rodriguez, Miguel; Martos-Rosillo, Sergio; Pedrera, Antonio

    2016-12-01

    Changes in the quantity of groundwater input due to water extraction for irrigation and urban supply has modified the water balance in the Fuente de Piedra playa lake. We have analysed the hydrogeology of the playa-lake system and developed a water-level model by means of a simple long-term water balance and piezometric analysis. In addition, a tectonic model is proposed to explain the endorheic basin development that led to the formation of the playa. Upright folds developed since the late Miocene and density-driven subsidence favoured the setting-up of and endorheic system located between the Atlantic and the Mediterranean basins in the Quaternary. The underlying low permeability rocks beneath the playa form a very stable aquitard with highly saline groundwater that prevents groundwater recharge of the lake into the aquitard. The hydrological modelling allowed us to simulate the evolution of the wáter level under a scenario of unaltered conditions during a 13-year period, showing that the percentage of days with dry conditions varies from 24.8% of the time under altered conditions to 14.9% as far as an unaltered scenario is concerned.

  17. A new Xenacanthiformes shark (Chondrichthyes, Elasmobranchii from the Late Paleozoic Rio do Rasto Formation (Paraná Basin, Southern Brazil

    Directory of Open Access Journals (Sweden)

    VICTOR E. PAULIV

    2014-03-01

    Full Text Available The Brazilian records on Xenacanthiformes include teeth and cephalic spines from the Parnaíba, Amazonas and Paraná basins. This work describes a new species of Xenacanthidae, collected in an outcrop of Serrinha Member of Rio do Rasto Formation (Wordian to Wuchiapingian, Paraná Basin, municipality of Jacarezinho, State of Paraná. The teeth of the new species are two or three-cuspidated and the aboral surface show a smooth concavity and one rounded basal tubercle. The coronal surface presents one semi-spherical and subcircular coronal button, and also two lateral main cusps and one central (when present with less than one fifth of the size of the lateral cusps in the labial portion. The lateral cusps are asymmetric or symmetric, rounded in transversal section, lanceolate in longitudinal section, devoid of lateral carinae and lateral serrations, and with few smooth cristae of enameloid. In optical microscope the teeth show a trabecular dentine (osteodentine base, while the cusps are composed by orthodentine, and the pulp cavities are non-obliterated by trabecular dentine. The fossil assemblage in the same stratigraphical level and in the whole Rio do Rasto Formation indicates another freshwater record for xenacanthid sharks.

  18. A new Xenacanthiformes shark (Chondrichthyes, Elasmobranchii) from the Late Paleozoic Rio do Rasto Formation (Paraná Basin), Southern Brazil.

    Science.gov (United States)

    Pauliv, Victor E; Dias, Eliseu V; Sedor, Fernando A; Ribeiro, Ana Maria

    2014-03-01

    The Brazilian records on Xenacanthiformes include teeth and cephalic spines from the Parnaíba, Amazonas and Paraná basins. This work describes a new species of Xenacanthidae, collected in an outcrop of Serrinha Member of Rio do Rasto Formation (Wordian to Wuchiapingian), Paraná Basin, municipality of Jacarezinho, State of Paraná. The teeth of the new species are two or three-cuspidated and the aboral surface show a smooth concavity and one rounded basal tubercle. The coronal surface presents one semi-spherical and subcircular coronal button, and also two lateral main cusps and one central (when present) with less than one fifth of the size of the lateral cusps in the labial portion. The lateral cusps are asymmetric or symmetric, rounded in transversal section, lanceolate in longitudinal section, devoid of lateral carinae and lateral serrations, and with few smooth cristae of enameloid. In optical microscope the teeth show a trabecular dentine (osteodentine) base, while the cusps are composed by orthodentine, and the pulp cavities are non-obliterated by trabecular dentine. The fossil assemblage in the same stratigraphical level and in the whole Rio do Rasto Formation indicates another freshwater record for xenacanthid sharks.

  19. Status and understanding of groundwater quality in the two southern San Joaquin Valley study units, 2005-2006 - California GAMA Priority Basin Project

    Science.gov (United States)

    Burton, Carmen A.; Shelton, Jennifer L.; Belitz, Kenneth

    2012-01-01

    Groundwater quality in the southern San Joaquin Valley was investigated from October 2005 through March 2006 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project is conducted by the U.S. Geological Survey (USGS) in collaboration with the California State Water Resources Control Board and the Lawrence Livermore National Laboratory. There are two study units located in the southern San Joaquin Valley: the Southeast San Joaquin Valley (SESJ) study unit and the Kern County Subbasin (KERN) study unit. The GAMA Priority Basin Project in the SESJ and KERN study units was designed to provide a statistically unbiased, spatially distributed assessment of untreated groundwater quality within the primary aquifers. The status assessment is based on water-quality and ancillary data collected in 2005 and 2006 by the USGS from 130 wells on a spatially distributed grid, and water-quality data from the California Department of Public Health (CDPH) database. Data was collected from an additional 19 wells for the understanding assessment. The aquifer systems (hereinafter referred to as primary aquifers) were defined as that part of the aquifer corresponding to the perforation interval of wells listed in the CDPH database for the SESJ and KERN study units. The status assessment of groundwater quality used data from samples analyzed for anthropogenic constituents such as volatile organic compounds (VOCs) and pesticides, as well as naturally occurring inorganic constituents such as major ions and trace elements. The status assessment is intended to characterize the quality of untreated groundwater resources within the primary aquifers in the SESJ and KERN study units, not the quality of drinking water delivered to consumers. Although the status assessment applies to untreated groundwater, Federal and California regulatory and non-regulatory water-quality benchmarks that apply to drinking water are used

  20. Folding, thrusting and development of push-up structures during the Miocene tectonic inversion of the Austral Basin, Southern Patagonian Andes (50°S)

    Science.gov (United States)

    Zerfass, Henrique; Ramos, Victor A.; Ghiglione, Matias C.; Naipauer, Maximiliano; Belotti, Hugo J.; Carmo, Isabela O.

    2017-03-01

    Rift and post-rift sections of the Austral Basin in the Southern Patagonian fold and thrust belt were examined in outcrop and in 2D seismic reflection sections to evaluate geometric and kinematic aspects of the extension and subsequent inversion. The syn-rift section is composed of dacitic lava flows of the El Quemado Complex (Jurassic), the lowermost unit of the basin. The coastal sandstones of the Springhill Formation (Tithonian-Berriasian) and marine shales of the Río Mayer Formation (Berriasian-Albian) are thought to be sag units. However, field data suggest that these units are also part of the syn-rift successions, as evidenced by extensional growth strata in the lower levels of the Río Mayer Formation. A dacitic flow that is texturally and compositionally similar to those of the syn-rift phase and that is termed here the Río Guanaco dacite is interfingered with the basal strata of the Río Mayer Formation and has a U-Pb zircon crystallization age of c. 141 Ma (Berriasian). The outcropping section was inverted by compression in the early Miocene, according to structural and isotopic data of adjacent areas, producing a broad anticline with inverted and fossil extensional faults as well as newly generated thrusts. At the seismic scale, most of the extensional master faults present negligible reverse slip, and shortening was accommodated in hanging wall push-up structures. This situation is interpreted as a result of the competent metamorphic basement and volcanic syn-rift section, inducing frictional lock-up of the master faults.

  1. Cenozoic faults and faulting phases in the western Tarim Basin (NW China): Effects of the collisions on the southern margin of the Eurasian Plate

    Science.gov (United States)

    Li, Yue-Jun; Zhang, Qiang; Zhang, Guang-Ya; Tian, Zuo-Ji; Peng, Geng-Xin; Qiu, Bin; Huang, Zhi-Bin; Luo, Jun-Cheng; Wen, Lei; Zhao, Yan; Jia, Tie-Gan

    2016-12-01

    The Bachu Rise in the western Tarim Basin is the fore-bulge of the Kunlun late Cenozoic intra-continental foreland basin system formed under the far-field effect of India-Asia collision. Cenozoic faults and faulting are abnormally developed in the Bachu Rise and its adjacent area. Taking the Niaoshan-Gudongshan area on the southern boundary of the Bachu Rise as the key study area, 5 Cenozoic faulting phases were identified in the Bachu Rise and its adjacent area after careful seismic interpretation. They are end Cretaceous ∼ beginning Paleogene (ca. 65 Ma) décollement-thrusting, end Paleogene ∼ beginning Neogene (ca. 23 Ma) décollement-thrusting, end Miocene ∼ beginning Pliocene (ca. 5 Ma) basement-involved thrusting, late Pliocene ∼ early Pleistocene (ca. 3-2 Ma) normal faulting, middle Pleistocene ∼ Holocene (ca. <1.5 Ma) décollement-thrusting and strike-slip faulting. The Middle Cambrian and Paleogene gypsum-salt layers serve as the two main décollement layers in the study area. Thrusting of ca. 65 Ma was under the far-field effect of the collision between Lhasa (part of the Cimmerian Continent) and Asia; and the other 4 Cenozoic faulting phases were all under the far-field effect of the India-Asia collision. The late Cenozoic faulting is characterized by pulse thrust. There is one tectonic pause between each two successive thrust pulses. The compressive tectonic stress is weaker and even evolved into a slight tensional tectonic stress and forms normal fault in the tectonic pauses.

  2. Deformation mechanisms and petrophysical properties of chert and limestone fault rocks within slope-to-basin succession (Gargano Promontory, Southern Italy)

    Science.gov (United States)

    Korneva, Irina; Tondi, Emanuele; Balsamo, Fabrizio; Agosta, Fabrizio

    2016-10-01

    In this work, we examine faults that crosscut limestone and chert rocks pertaining to a slope-to-basin succession of the eastern Gargano Promontory (southern Italy). Based on field data, microstructural observations, and quantitative analysis of cataclastic fabric, two stages of faulting are recognized. The first one, the pre-lithification faulting stage, took place within partially lithified sediments prior to their complete lithification. Differently, the second one, the post-lithification faulting stage, occurred within cohesive, well-lithified rocks. The structural properties of pre-lithification faults were likely controlled by the competence contrast between limestone and chert sediments. In fact, due to their different lithification stages, faulting occurred when chert was still not completely lithified, and hence was dragged along the fault planes. As a consequence, the pre-lithification fault cores are mainly composed of chert clasts. On the contrary, post-lithification fault cores are mostly made up of limestone clasts. The results of both microstructural and image analyses show that the carbonate fault rock includes a higher percentage of bigger clasts with lower values of angularity than the chert fault rock. Mercury-intrusion porosimetry indicates that the chert fault rock is characterized by larger pore throats and a lower amount of total porosity with respect to the limestone fault rock. The permeability values obtained for the limestone fault rock are lower than those for the chert fault rock, probably because of the lower amount of pore connectivity within the former fault rock. Results of this multidisciplinary work highlight the role played by cherty layers present within well-layered, slope-to-basin carbonate successions on both microtextural and petrophysical fault rock properties. Furthermore, these results increase our ability to predict how lithological heterogeneities and amount of lithification influence the deformation mechanisms, hence

  3. New Middle Permian palaeopteran insects from Lodève Basin in southern France (Ephemeroptera, Diaphanopterodea, Megasecoptera

    Directory of Open Access Journals (Sweden)

    Jakub Prokop

    2011-09-01

    Full Text Available Three new palaeopteran insects are described from the Middle Permian (Guadalupian of Salagou Formation in the Lodève Basin (South of France, viz. the diaphanopterodean Alexrasnitsyniidae fam. n., based on Alexrasnitsynia permiana gen. et sp. n., the Parelmoidae Permelmoa magnifica gen. et sp. n., and Lodevohymen lapeyriei gen. et sp. n. (in Megasecoptera or Diaphanopterodea, family undetermined. In addition the first record of mayflies attributed to family Syntonopteridae (Ephemeroptera is reported. These new fossils clearly demonstrate that the present knowledge of the Permian insects remains very incomplete. They also confirm that the Lodève entomofauna was highly diverse providing links to other Permian localities and also rather unique, with several families still not recorded in other contemporaneous outcrops.

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

    KAUST Repository

    Farid, Asam M.

    2014-07-10

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

  5. Impact of riparian land-use patterns on Ephemeroptera community structure in river basins of the southern Western Ghats, India

    Directory of Open Access Journals (Sweden)

    Selvakumar C.

    2014-02-01

    Full Text Available This study analysed the impact of riparian land use in structuring the larval ephemeropteran communities from 25 sites in streams and rivers of Kalakad-Mundanthurai Tiger Reserve (KMTR of the southern end of the Western Ghats, India. A total of twenty-eight species belonging to twenty-four genera of six families were collected across all the sites. Baetidae and Leptophlebiidae were the most numerous and ubiquitous families, comprising eight genera in each family and eleven and nine species, respectively. The physico-chemical parameters and species richness and abundance of mayflies varied across streams and rivers with different riparian land-use types. Species distribution was influenced by the environmental gradients. Canonical Correspondence Analysis revealed a clear separation of the mayfly assemblages along water quality and riparian land-use gradients. The results of this study suggest that Ephemeroptera taxa can be potentially used as sensitive indicators of riparian land use in lotic ecosystems.

  6. Distribution of Aboveground Live Biomass in the Amazon Basin

    Science.gov (United States)

    Saatchi, S. S.; Houghton, R. A.; DosSantos Alvala, R. C.; Soares, J. V.; Yu, Y.

    2007-01-01

    The amount and spatial distribution of forest biomass in the Amazon basin is a major source of uncertainty in estimating the flux of carbon released from land-cover and land-use change. Direct measurements of aboveground live biomass (AGLB) are limited to small areas of forest inventory plots and site-specific allometric equations that cannot be readily generalized for the entire basin. Furthermore, there is no spaceborne remote sensing instrument that can measure tropical forest biomass directly. To determine the spatial distribution of forest biomass of the Amazon basin, we report a method based on remote sensing metrics representing various forest structural parameters and environmental variables, and more than 500 plot measurements of forest biomass distributed over the basin. A decision tree approach was used to develop the spatial distribution of AGLB for seven distinct biomass classes of lowland old-growth forests with more than 80% accuracy. AGLB for other vegetation types, such as the woody and herbaceous savanna and secondary forests, was directly estimated with a regression based on satellite data. Results show that AGLB is highest in Central Amazonia and in regions to the east and north, including the Guyanas. Biomass is generally above 300Mgha(sup 1) here except in areas of intense logging or open floodplains. In Western Amazonia, from the lowlands of Peru, Ecuador, and Colombia to the Andean mountains, biomass ranges from 150 to 300Mgha(sup 1). Most transitional and seasonal forests at the southern and northwestern edges of the basin have biomass ranging from 100 to 200Mgha(sup 1). The AGLB distribution has a significant correlation with the length of the dry season. We estimate that the total carbon in forest biomass of the Amazon basin, including the dead and below ground biomass, is 86 PgC with +/- 20% uncertainty.

  7. Late Pleistocene evolution of the Rhine-Meuse system in the southern North Sea basin: imprints of climate change, sea-level oscillation and glacio-isostacy

    Science.gov (United States)

    Busschers, F. S.; Kasse, C.; van Balen, R. T.; Vandenberghe, J.; Cohen, K. M.; Weerts, H. J. T.; Wallinga, J.; Johns, C.; Cleveringa, P.; Bunnik, F. P. M.

    2007-12-01

    High-resolution continuous core material, geophysical measurements, and hundreds of archived core descriptions enabled to identify 13 Late Pleistocene Rhine-Meuse sedimentary units in the infill of the southern part of the North Sea basin (the Netherlands, northwestern Europe). This sediment record and a large set of Optical Stimulated Luminescence dates, 14C dates and biostratigraphical data, allowed to establish detailed relationships between climate change, sea-level oscillation, glaciation history and the sedimentary development of the Rhine fluvial system during the last glacial cycle (Marine Isotope Stages 5e-2, Eemian-Weichselian). A well-preserved Eemian sediment record was encountered as the infill of a Late Saalian (MIS6) subglacial basin. Part of this record reflects groundwater rise controlled (fine-grained) sedimentation as a result of postglacial (early) Eemian sea-level rise. It shows strong analogy to developments known from the Holocene Rhine-Meuse delta. Outside of the glacial depressions near coastal deposits are only fragmentarily preserved. The Early Glacial Rhine sediment record is dominated by organic debris and peat layers, marking landscape stability and low fluvial activity. Part of this record may have been formed under near coastal conditions. Significant amounts of reworked marine biomarkers in the lag-deposits of Early Pleniglacial (MIS4) fluvial systems indicate that this period is characterized by extensive reworking of older (MIS5) near-coastal sediments. Despite the marked Early Pleniglacial climatic cooling, input of new sediment from the drainage basin was relatively low, a feature that is related to the presence of regolith protective relic soil complexes in the basin. During the early Middle Pleniglacial, a major Rhine avulsion indicates the system was in an aggrading mode and that sediment supply into the lower reaches of the Rhine had strongly increased. This increase in sediment supply coincided with the timing of major

  8. Holocene late Pleistocene non-tropical carbonate sediments and tectonic history of the western rift basin margin of the southern Gulf of California

    Science.gov (United States)

    Halfar, Jochen; Godinez-Orta, Lucio; Goodfriend, Glenn A.; Mucciarone, David A.; Ingle, James C.; Holden, Peter

    2001-10-01

    Using high-resolution seismic reflection profiling and dating of (1) shallow marine vibracores and (2) sediments collected from uplifted marine terraces we reconstruct the tectonic history and sediment accumulation patterns of Holocene to late Pleistocene warm-temperate to subtropical carbonates in the southern Gulf of California, Mexico. The study was conducted in the vicinity of La Paz where carbonates form along the fault bounded narrow western shelf of the tectonically active Gulf of California rift basin. The non-tropical nature of the setting is responsible for (1) poor cementation of the bioclastic carbonates, and (2) a composition which is dominated by rhodoliths (coralline red algae), corals and mollusks. Unrimmed carbonate flats forming in small pocket bays and a rhodolith bioherm, which has a surface area of more than 20 km 2 and is up to 16 m thick, constitute the major carbonate factories. Holocene carbonate accumulation rates were deduced from seismic and core data and are highest on the rhodolith bioherm (260 cm/ka) and in subtidal zones of pocket bays (210 cm/ka), and lowest on the inner and middle shelf (100 cm/ka). Taken together, rates of carbonate accumulation are intermediate in magnitude between higher rates recorded in fully tropical carbonate settings and lower rates typical of cool-water carbonates. Seismic reflection profiles demonstrate that Isla Espiritu Santo in the center of the study area is a west dipping fault block, which is tectonically influenced by two distinct faults, the La Paz and Espiritu Santo faults. The latter fault accommodates at least 700 m of east-side down normal offset, and forms a steep eastern escarpment leading into the La Paz slope basin. Some of the sediments produced in the shallow carbonate factories of the narrow La Paz shelf are transported across this escarpment and are redeposited in the slope basin at a water depth of 750 m. Uranium-series dates of marine terraces exposed on Isla Espiritu Santo indicate

  9. Deformation and incision of the western margin of the Central Andean Plateau, S. Peru and N. Chile

    Science.gov (United States)

    Schildgen, T.

    2012-12-01

    The western margin of the Central Andean Plateau in southern Peru and northern Chile hosts a rich geologic and geomorphic record of crustal deformation and river incision that developed during a period of regional plateau uplift. Significant growth of topography likely occurred in the western Central Andes starting at ca. 30 Ma, when the regionally extensive silts and sandstones of the Moquegua and Azapa Group sediments gave way to coarse sandstones and conglomerates. Apatite (U-Th)/He thermochronology, 3D thermal modeling, and infilling volcanic flows show that a subsequent major phase of canyon incision started in the middle reaches of Ocoña Canyon (southern Peru) between 11 and 8 Ma, with ca. 2-km of incision occurring between ca. 11 and 5 Ma. Surface uplift coeval with this incision has been documented in northern Chile, where rotated forearc basin deposits reveal 1 to 2 km of differential uplift between the Coastal Cordillera and the plateau margin that started after 11 to 10 Ma. In contrast with the 11 to 8 Ma onset of incision in the middle reaches of Ocoña Canyon, the currently 1-km-high coastal/piedmont region appears not to have been affected by incision until after 5 Ma, as documented by the 50-km-wide alluvial and colluvial plain that remained occupied by rivers until at least 5 Ma. Apatite (U-Th)/He thermochronology pointing to a final 1-km of incision in the middle reaches of Ocoña Canyon after ca. 5 Ma is supported by apatite 4He/3He thermochonometry, which documents the passage of a km-scale knickpoint through the same region between ca. 7 and 4 Ma. Although river incision provides only a minimum time constraint for the start of surface uplift, the broadly coincident start of incision with the rotation of forearc basin deposits in northern Chile implies a close temporal coupling between the start of surface uplift and the onset of incision in Ocoña Canyon. Furthermore, the delayed incision of the coastal/piedmont region until after 5 Ma shows

  10. [Palaeoparasitological analysis of guinea pig mummies of the Chiribaya culture, Moquegua Valley, Peru].

    Science.gov (United States)

    Dittmar de la Cruz, Katharina; Ribbeck, Regine; Daugschies, Arwid

    2003-01-01

    During several excavations of archeological sites in the Moquegua Valley, Southern Peru, various guinea pig mummies (Cavia aperea f. porcellus) have been discovered. They belong to the Chiribaya Culture (900-1100 AD). The outstanding preservation of the mummified animals gave rise to the idea of a paleoparasitological analysis. In the fur, numerous well preserved ectoparasites (lice, fleas, mites) could be recovered. Generally, ectoparasite remains are rarely found among archeological material. This is the first account of an extensive ectoparasitological analysis of animal mummies in Peru. A modified technique for recovery and preservation of the ectoparasites has been developed.

  11. Petrography and geochemistry of Oligocene bituminous coal from the Jiu Valley, Petrosani basin (southern Carpathian Mountains), Romania

    Energy Technology Data Exchange (ETDEWEB)

    Belkin, Harvey E.; Tewalt, Susan J. [U.S. Geological Survey, 956 National Center, Reston, VA 20192 (United States); Hower, James C. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); Stucker, J.D. [University of Kentucky Center for Applied Energy Research, 2540 Research Park Drive, Lexington, KY 40511 (United States); University of Kentucky Department of Earth and Environmental Sciences, Lexington, KY 40506 (United States); O' Keefe, Jennifer M.K. [Morehead State University, Morehead, KY, 40351 (United States); Tatu, Calin A. [University of Medicine and Pharmacy, Department of Immunology, Clinical Laboratory No. 1, Pta. E. Murgu No. 2, RO-1900 Timisoara (Romania); Buia, Grigore [University of Petrosani, Department of Geology, University St. 20, RO-2675 Petrosani (Romania)

    2010-05-01

    Belt samples of Oligocene (Chattian) bituminous coal from 10 underground mines located in the Jiu Valley, Hunedoara County, Petrosani basin, Romania, have been examined and analyzed for proximate and ultimate analysis, major-, minor- and trace-element chemistry, organic petrography, and vitrinite reflectance. The mineral chemistry and mode of occurrence of trace elements also have been investigated using SEM and electron microprobe techniques. Twenty coal beds occur in the Jiu Valley and most of the samples are from bed no. 3, the most productive bed of the Dilja-Uricani Formation of Oligocene age. The Petrosani basin, oriented SW-NE, is 48-km long, 10-km wide at the eastern part and 2-km wide at the western part. The coal mines are distributed along the center of the valley generally following the Jiu de Vest River. Reflectance measurements indicate that the rank of the coals ranges from high-volatile B to high-volatile A bituminous. Overall, rank decreases from the southwest to the northeast. In bed no. 3, R{sub max} varies from 0.75% in the northeast to 0.93% in the southwest. Although, most Oligocene coals in Romania and adjacent countries are lignite in rank, the Jiu Valley bituminous coals have been affected by regional metamorphism and attending hydrothermal fluids related to the Alpine orogenic event. The coals are all dominated by vitrinite; resinite and funginite are important minor macerals in most of the coals. Pyrite and carbonate generally dominate the mineral assemblages with carbonate more abundant in the northwest. Siderite occurs as nodules and masses within the macerals (generally vitrinite). Dolomite and calcite occur as fracture fillings, plant-cell fillings, and in other authigenic forms. Late-stage fracture fillings are siderite, dolomite, calcite, and ankerite. In one instance, two populations of siderite ({proportional_to} 35 and {proportional_to} 45 wt.% FeO) plus ankerite fill a large fracture. Late-stage pyrite framboid alteration is Ni

  12. [Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

    Science.gov (United States)

    Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

    2016-04-15

    We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P carbon contents and other environmental factors (P > 0.05).

  13. Drought, floods and water quality: Drivers of a severe hypoxic blackwater event in a major river system (the southern Murray-Darling Basin, Australia)

    Science.gov (United States)

    Whitworth, Kerry L.; Baldwin, Darren S.; Kerr, Janice L.

    2012-07-01

    SummaryHypoxic blackwater events are characterised by high levels of dissolved organic carbon in the water column, the metabolism of which depletes dissolved oxygen, which can cause fish and crustacean mortality. Understanding the drivers of and controls on hypoxic blackwater events is important in order to reduce the potential for detrimental water quality impacts from both managed and natural flows. After a decade-long drought in south-eastern Australia, a series of spring and summer flood events in 2010-2011 resulted in a large-scale hypoxic blackwater event in the southern Murray-Darling Basin that affected over 2000 km of river channels and persisted for 6 months. We examined the biogeochemistry and hydrology underpinning this extreme event and found that multiple drivers contributed to the development and persistence of hypoxic blackwater. Inundation of both forested and agricultural floodplains that had not been flooded for over a decade mobilised large stores of reactive carbon. Altered flow seasonality, due to a combination of climatic effects and river regulation, not only increased the risk of hypoxic blackwater generation but also shifted the proportion of bioavailable carbon that was returned to the river channels. Hypolimnetic weir discharge also contributed to hypoxia at some sites. These findings highlight the need for a whole-of-system perspective for the management of regulated river systems - especially in the face of a changing climate.

  14. Formation mechanisms and sequence response of authigenic grain-coating chlorite: evidence from the Upper Triassic Xujiahe Formation in the southern Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Yu Yu

    2016-11-01

    Full Text Available Abstract Authigenic grain-coating chlorite is widely distributed in the clastic rocks of many sedimentary basins around the world. These iron minerals were mainly derived from flocculent precipitates formed when rivers flow into the ocean, especially in deltaic environments with high hydrodynamic conditions. At the same time, sandstone sequences with grain-coating chlorites also tend to have relatively high glauconite and pyrite content. EPMA composition analysis shows that glauconites with “high Al and low Fe” content indicate slightly to semi-saline marine environments with weak alkaline and weakly reducing conditions. By analyzing the chlorite-containing sandstone bodies of the southern Sichuan Xujiahe Formation, this study found that chlorite was mainly distributed in sedimentary microfacies, including underwater distributary channels, distributary channels, shallow lake sandstone dams, and mouth bars. Chlorite had a tendency to form in the upper parts of sandstone bodies with signs of increased base level, representing the influence of marine (lacustrine transgression. This is believed to be influenced by megamonsoons in the Middle and Upper Yangtze Region during the Late Triassic Epoch. During periods of abundant precipitation, river discharges increased and more Fe particulates flowed into the ocean (lake. In the meantime, increases or decreases in lake level were only affected by precipitation for short periods of time. The sedimentary environment shifted from weakly oxidizing to weak alkaline, weakly reducing conditions as sea level increased, and Fe-rich minerals as authigenic chlorite and glauconite began to form and deposit.

  15. Occurrence, thermal evolution and primary migration processes derived from studies of organic matter in the Lucaogou source rock at the southern margin of the Junggar Basin, NW China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Lucaogou Formation carbonate-rich oil shale source rock is exposed at the southern margin of the Junggar Basin, Xinjiang, NW China. We have sampled it in detail and conducted microstructural, mineralogical and geochemical studies, including thin section petrography, UV fluorescence petrography, X-ray diffraction, vitrinite reflectance, bitumen reflectance, fluid inclusion analysis and Raman spectroscopy. Organic matter is disseminated through the carbonate-bearing siltstone source rocks and concentrated in numerous bedding parallel stylolites and in two sets of carbonate veins, one along bedding parallel fractures and the other cross-cutting stylolites and bedding. The research about maturity of organic matter finds vitrinite reflectance values increase from the dispersed kerogen (0.64%) to the stylolites (the one of oriented vitrinite is 0.72% and the one of migrated bitumen is 2.38%); Homogenization temperatures of fluid inclusions in veins containing hydrocarbon fluid inclusions show an increase from 178.5℃ in the bedding parallel veins to 222℃ in the cross-cutting veins, confirmed by Raman spectroscopy. These results support a model of progressive heating accompanied by fluid loss during later stages of thermal maturation of source rock and the onset of primary migration. Obviously, the occurrence of organic matter is the trace of hydrocarbon primary migration, and the bedding lamination surfaces and cross-cutting fissures are the principal pathways of hydrocarbon-bearing fluids migration. Bedding lamination surfaces evolved into stylolites along the earliest primary migration pathways, followed by bedding parallel and cross-cutting fissures.

  16. Permeability prediction in deep coal seam: a case study on the No. 3 coal seam of the Southern Qinshui Basin in China.

    Science.gov (United States)

    Guo, Pinkun; Cheng, Yuanping

    2013-01-01

    The coal permeability is an important parameter in mine methane control and coal bed methane (CBM) exploitation, which determines the practicability of methane extraction. Permeability prediction in deep coal seam plays a significant role in evaluating the practicability of CBM exploitation. The coal permeability depends on the coal fractures controlled by strata stress, gas pressure, and strata temperature which change with depth. The effect of the strata stress, gas pressure, and strata temperature on the coal (the coal matrix and fracture) under triaxial stress and strain conditions was studied. Then we got the change of coal porosity with strata stress, gas pressure, and strata temperature and established a coal permeability model under tri-axial stress and strain conditions. The permeability of the No. 3 coal seam of the Southern Qinshui Basin in China was predicted, which is consistent with that tested in the field. The effect of the sorption swelling on porosity (permeability) firstly increases rapidly and then slowly with the increase of depth. However, the effect of thermal expansion and effective stress compression on porosity (permeability) increases linearly with the increase of depth. The most effective way to improve the permeability in exploiting CBM or extracting methane is to reduce the effective stress.

  17. Permeability Prediction in Deep Coal Seam: A Case Study on the No. 3 Coal Seam of the Southern Qinshui Basin in China

    Directory of Open Access Journals (Sweden)

    Pinkun Guo

    2013-01-01

    Full Text Available The coal permeability is an important parameter in mine methane control and coal bed methane (CBM exploitation, which determines the practicability of methane extraction. Permeability prediction in deep coal seam plays a significant role in evaluating the practicability of CBM exploitation. The coal permeability depends on the coal fractures controlled by strata stress, gas pressure, and strata temperature which change with depth. The effect of the strata stress, gas pressure, and strata temperature on the coal (the coal matrix and fracture under triaxial stress and strain conditions was studied. Then we got the change of coal porosity with strata stress, gas pressure, and strata temperature and established a coal permeability model under tri-axial stress and strain conditions. The permeability of the No. 3 coal seam of the Southern Qinshui Basin in China was predicted, which is consistent with that tested in the field. The effect of the sorption swelling on porosity (permeability firstly increases rapidly and then slowly with the increase of depth. However, the effect of thermal expansion and effective stress compression on porosity (permeability increases linearly with the increase of depth. The most effective way to improve the permeability in exploiting CBM or extracting methane is to reduce the effective stress.

  18. Natural gas distribution network of Lima and Callao, Peru

    Energy Technology Data Exchange (ETDEWEB)

    Maroye, Stephane; Aerssens, Andre [Tractebel Engineering, Lima (Peru)

    2005-07-01

    In May 2002, Suez-Tractebel was awarded by the government of Peru a 30-year concession for the construction and operation of the gas distribution network in Lima, Peru. On 10 July, 2004, first gas was delivered to Lima, 1 month ahead of the official date. This gas distribution network, operated by GNLC (Gas Natural de Lima y Callao), delivers gas to some of the largest industries and power generators in and around Lima and the harbour area of Callao. Gas delivered in Lima comes through a 700 km HP gas pipeline from Camisea fields. This pipeline is operated by TGP (Transportadora de Gas del Peru). A City Gate is located at Lurin, on the southern side of the city. The gas distribution network is made of a 62 km main pipeline (20') with 25 km laterals. The main pipeline is operated at 50 bar, as the main customer, the Etevensa power plant, is located on the northern side of the city. Due to this high operating pressure combined to the surroundings, specific design philosophies were adopted to meet the extreme safety requirements. This paper highlights the specific measures taken during construction phase and the experience of the first months of operation of this challenging project. (author)

  19. Single basin double slope solar still: Year round performance prediction for local climatic conditions at Southern India

    Directory of Open Access Journals (Sweden)

    Kulandaivel Kalidasa Murugavel

    2014-01-01

    Full Text Available In this work, performance of a single basin double slope solar still has been studied theoretically and experimentally. The theoretical model is used to predict the year round performance of the still at the local climatic conditions for the year 2008. Average values of maximum and minimum atmospheric temperatures, wind velocities were taken from meteorological data for last five years. Radiation models were used to predict the global and diffused irradiances on the inclined covers. The time to time variations in transmittance of the cover were considered. The rate of production variation and the total production for first day of the every month had been calculated. The overall production of the still was higher during March, April, August, November and December and it is around 4 liters/day. The average production of the still was 2.1 liters/day/m2. The economy of the still was also studied and the payback period of the still was three years.

  20. Marine-continental tephra correlations: Volcanic glass geochemistry from the Marsili Basin and the Aeolian Islands, Southern Tyrrhenian Sea, Italy

    Science.gov (United States)

    Albert, P. G.; Tomlinson, E. L.; Smith, V. C.; Di Roberto, A.; Todman, A.; Rosi, M.; Marani, M.; Muller, W.; Menzies, M. A.

    2012-06-01

    Major, minor and trace element analysis of volcanic glass in proximal and distal (Lipari (Monte Pilato; 776 cal AD); (2) Vulcano; and (3) Campi Flegrei (Soccavo 1; 11,915-12,721 cal years BP). Whether a polymictic coarse grained volcaniclastic turbidite in the Marsili Basin originated from collapse on Salina remains unresolved because multi-elemental analysis raises doubt about the published correlation to the Pollara region. It is evident that correlation of proximal continental and distal marine tephras, at a high level of confidence, requires a full complement of major, minor and trace element data. In conjunction with considerations of the mineralogy and morphology of juvenile deposits these data help define petrological lineages such that precise provenance can be established. Whilst a precise proximal-distal match must be based on identical major, minor and trace element concentrations it is clear that resurgent activity from a single volcano can produce magmas with identical compositions. In such cases stratigraphic relationships must complement any geochemical study. Occasionally proximal stratigraphies may be unrepresentative of the complete eruptive history because of a lack of exposure due to burial by more recent effusive and explosive activity, or sector collapse which can remove vital stratigraphy particularly on volcanic islands.

  1. Holocene dinoflagellate cyst record of climate and marine primary productivity change in the Santa Barbara Basin, southern California.

    Science.gov (United States)

    Pospelova, Vera; Mertens, Kenneth N.; Hendy, Ingrid, L.; Pedersen, Thomas F.

    2015-04-01

    High-resolution sedimentary records of dinoflagellate cysts and other marine palynomorphs from the Santa Barbara Basin (Ocean Drilling Program Hole 893A) demonstrate large variability of primary productivity during the Holocene, as the California Current System responded to climate change. Throughout the sequence, dinoflagellate cyst assemblages are characterized by the dominance of cysts produced by heterotrophic dinoflagellates, and particularly by Brigantedinium, accompanied by other upwelling-related taxa such as Echinidinium and cysts of Protoperidinium americanum. During the early Holocene (~12-7 ka), the species richness is relatively low (16 taxa) and genius Brigantedinium reaches the highest relative abundance, thus indicating nutrient-rich and highly productive waters. The middle Holocene (~7-3.5 ka) is characterized by relatively constant cyst concentrations, and dinoflagellate cyst assemblages are indicative of a slight decrease in sea-surface temperature. A noticeable increase and greater range of fluctuations in the cyst concentrations during the late Holocene (~3.5-1 ka) indicate enhanced marine primary productivity and increased climatic variability, most likely related to the intensification of El Niño-like conditions. Keywords: dinoflagellate cysts, Holocene, North Pacific, climate, primary productivity.

  2. Status of groundwater quality in the Southern, Middle, and Northern Sacramento Valley study units, 2005-08: California GAMA Priority Basin Project

    Science.gov (United States)

    Bennett, George L.; Fram, Miranda S.; Belitz, Kenneth

    2011-01-01

    Groundwater quality in the Southern, Middle, and Northern Sacramento Valley study units was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study units are located in California's Central Valley and include parts of Butte, Colusa, Glenn, Placer, Sacramento, Shasta, Solano, Sutter, Tehama, Yolo, and Yuba Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey and the Lawrence Livermore National Laboratory. The three study units were designated to provide spatially-unbiased assessments of the quality of untreated groundwater in three parts of the Central Valley hydrogeologic province, as well as to provide a statistically consistent basis for comparing water quality regionally and statewide. Samples were collected in 2005 (Southern Sacramento Valley), 2006 (Middle Sacramento Valley), and 2007-08 (Northern Sacramento Valley). The GAMA studies in the Southern, Middle, and Northern Sacramento Valley were designed to provide statistically robust assessments of the quality of untreated groundwater in the primary aquifer systems that are used for drinking-water supply. The assessments are based on water-quality data collected by the USGS from 235 wells in the three study units in 2005-08, and water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer systems (hereinafter, referred to as primary aquifers) assessed in this study are defined by the depth intervals of the wells in the CDPH database for each study unit. The quality of groundwater in shallow or deep water-bearing zones may differ from quality of groundwater in the primary aquifers; shallow groundwater may be more vulnerable to contamination from the surface. The status of the current quality of the groundwater resource was assessed by using data from samples analyzed for volatile organic

  3. The Danxia Landforms in Sichuan Basin and the Castles of Southern Song Dynasty for Resistance Against Mongolia%四川盆地丹霞地貌与南宋抗蒙城寨

    Institute of Scientific and Technical Information of China (English)

    罗成德; 王付军

    2015-01-01

    四川盆地是中国著名的红层盆地,其中由侏罗系和白垩系地层为主,构成了大量的丹霞地貌和假丹霞地貌.由于顶平身陡的地貌特点,为南宋军民所利用,在上构筑了坚固的抗蒙城寨. 它们星罗棋布于盆地内,这些军事堡垒的坚固,大大延缓了南宋灭亡的时间. 它们的遗迹成为四川盆地一项宝贵的旅游资源.%Sichuan Basin is a famous red basin in China. It has many Danxia Landforms and Artificial Danxia Landforms,formed with Jurassic and Cretaceous system mainly and featured with flat tops and steep slopes. And these landforms were used to build military castles as strong resistance strongholds against the Mongolian military in the Southern Song Dynasty. These military castles spread all over Sichuan Basin. Due to their indestructibility,the castles slowed down the dooming of the Southern Song Dynasty. These historical castles are valuable tourism resource in Sichuan Basin.

  4. Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

    Science.gov (United States)

    Shimeld, John; Li, Qingmou; Chian, Deping; Lebedeva-Ivanova, Nina; Jackson, Ruth; Mosher, David; Hutchinson, Deborah

    2016-01-01

    The Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is encoded in seismic wide-angle reflections and refractions recorded with expendable sonobuoys between 2007 and 2011. Velocity-depth samples within the sedimentary succession are extracted from published analyses for 142 of these records obtained at irregularly spaced stations across an area of 1.9E + 06 km2. The samples are modelled at regional, subregional and station-specific scales using an exponential function of inverse velocity versus depth with regionally representative parameters determined through numerical regression. With this approach, smooth, non-oscillatory velocity-depth profiles can be generated for any desired location in the study area, even where the measurement density is low. Practical application is demonstrated with a map of sedimentary thickness, derived from seismic reflection horizons interpreted in the time domain and depth converted using the velocity-depth profiles for each seismic trace. A thickness of 12-13 km is present beneath both the upper Mackenzie fan and the middle slope off of Alaska, but the sedimentary prism thins more gradually outboard of the latter region. Mapping of the observed-to-predicted velocities reveals coherent geospatial trends associated with five subregions: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. Comparison of the subregional velocity-depth models with published borehole data, and interpretation of the station-specific best-fitting model parameters, suggests that sandstone is not a predominant lithology in any of the five subregions. However, the bulk sand-to-shale ratio likely increases towards the Mackenzie fan, and the model for this subregion compares favourably with

  5. Response of the diatom flora in the Gdańsk Basin (southern Baltic Sea) to eutrophication in the last century

    Science.gov (United States)

    Witak, Małgorzata

    2016-04-01

    The diatom flora in six short cores (length of 10-20 cm) taken from Gdańsk Basin, southern Baltic Sea, was analyzed in order to response of diatoms to environmental changes over the past 100 years. This study is a part of CLISED project (Climate Change Impact on Ecosystem Health - Marine Sediments Indicators) funded from Norway Grants in the Polish-Norwegian Research Programme. Three cores P116, M1 and P1 were retrieved from the Gdańsk Deep region, whereas P104, BMPK10 and P110 were drilled from the shallower part - Gulf of Gdańsk. The sediment cores were dated by 210Pb and represented time interval of AD 1895-2015. In this period an artificial mouth of the Vistula River near Świbno was excavated and riverine waters flowed directly to the Gulf of Gdańsk. Urbanization, progressive industrialization and an increase in the inflow of waste water had a strong influence on ecosystem in the last 120 years. The transport of large amounts of nutrients, organic matter and pollutants by the rivers resulted in environmental degradation of the Gdańsk Basin and its progressive eutrophication in particular. Diatoms, being the major component of algal assemblages, are excellent bioindicators for assessing the state of basin ecosystems. They are usually abundant in marine sediments, diverse and sensitive to numerous environmental variables, including physical (e.g. light, temperature, water transparency) and chemical (e.g. pH, alkalinity, nutrient availability) factors. Changes in nutrients concentrations may lead to substantial transformations in the structure of diatom assemblages. Samples for diatom analyses (ca. 0.3-2.0 g dry sediment) were prepared following the standard procedure for diatom observation under light microscope (Battarbee, 1986). To estimate the concentration of siliceous microfossils per unit weight of dry sediment (absolute abundance), a random settling technique was used (Bodén, 1991). Permanent diatom preparations were mounted in Naphrax® (refractive

  6. Seismic velocities within the sedimentary succession of the Canada Basin and southern Alpha-Mendeleev Ridge, Arctic Ocean: evidence for accelerated porosity reduction?

    Science.gov (United States)

    Shimeld, John; Li, Qingmou; Chian, Deping; Lebedeva-Ivanova, Nina; Jackson, Ruth; Mosher, David; Hutchinson, Deborah R.

    2016-01-01

    The Canada Basin and the southern Alpha-Mendeleev ridge complex underlie a significant proportion of the Arctic Ocean, but the geology of this undrilled and mostly ice-covered frontier is poorly known. New information is encoded in seismic wide-angle reflections and refractions recorded with expendable sonobuoys between 2007 and 2011. Velocity–depth samples within the sedimentary succession are extracted from published analyses for 142 of these records obtained at irregularly spaced stations across an area of 1.9E + 06 km2. The samples are modelled at regional, subregional and station-specific scales using an exponential function of inverse velocity versus depth with regionally representative parameters determined through numerical regression. With this approach, smooth, non-oscillatory velocity–depth profiles can be generated for any desired location in the study area, even where the measurement density is low. Practical application is demonstrated with a map of sedimentary thickness, derived from seismic reflection horizons interpreted in the time domain and depth converted using the velocity–depth profiles for each seismic trace. A thickness of 12–13 km is present beneath both the upper Mackenzie fan and the middle slope off of Alaska, but the sedimentary prism thins more gradually outboard of the latter region. Mapping of the observed-to-predicted velocities reveals coherent geospatial trends associated with five subregions: the Mackenzie fan; the continental slopes beyond the Mackenzie fan; the abyssal plain; the southwestern Canada Basin; and, the Alpha-Mendeleev magnetic domain. Comparison of the subregional velocity–depth models with published borehole data, and interpretation of the station-specific best-fitting model parameters, suggests that sandstone is not a predominant lithology in any of the five subregions. However, the bulk sand-to-shale ratio likely increases towards the Mackenzie fan, and the model for this subregion compares

  7. Depositional architecture of a mixed travertine-terrigenous system in a fault-controlled continental extensional basin (Messinian, Southern Tuscany, Central Italy)

    Science.gov (United States)

    Croci, Andrea; Della Porta, Giovanna; Capezzuoli, Enrico

    2016-03-01

    The extensional Neogene Albegna Basin (Southern Tuscany, Italy) includes several thermogene travertine units dating from the Miocene to Holocene time. During the late Miocene (Messinian), a continental fault-controlled basin (of nearly 500-km2 width) was filled by precipitated travertine and detrital terrigenous strata, characterized by a wedge-shaped geometry that thinned northward, with a maximum thickness of nearly 70 m. This mixed travertine-terrigenous succession was investigated in terms of lithofacies types, depositional environment and architecture and the variety of precipitated travertine fabrics. Deposited as beds with thickness ranging from centimetres to a few decimetres, carbonates include nine travertine facies types: F1) clotted peloidal micrite and microsparite boundstone, F2) raft rudstone/floatstone, F3) sub-rounded radial coated grain grainstone, F4) coated gas bubble boundstone, F5) crystalline dendrite cementstone, F6) laminated boundstone, F7) coated reed boundstone and rudstone, F8) peloidal skeletal grainstone and F9) calci-mudstone and microsparstone. Beds of terrigenous deposits with thickness varying from a decimetre to > 10 m include five lithofacies: F10) breccia, F11) conglomerate, F12) massive sandstone, F13) laminated sandstone and F14) claystone. The succession recorded the following three phases of evolution of the depositional setting: 1) At the base, a northward-thinning thermogene travertine terraced slope (Phase I, travertine slope lithofacies association, F1-F6) developed close to the extensional fault system, placed southward with respect to the travertine deposition. 2) In Phase II, the accumulation of travertines was interrupted by the deposition of colluvial fan deposits with a thickness of several metres (colluvial fan lithofacies association, F10 and F12), which consisted of massive breccias, adjacent to the alluvial plain lithofacies association (F11-F14) including massive claystone and sandstone and channelized

  8. Jurassic onychites (hooks from squid-like cephalopods) associated with statolith occurrences in the Wessex Basin, southern England

    Science.gov (United States)

    Hart, Malcolm; Page, Kevin; Price, Gregory; Smart, Christopher; Wilby, Philip

    2016-04-01

    Modern coleoid (squid-like) cephalopods have arms that carry arrays of both suckers and hardened, organic hooks. Fossil arm hooks have been known since the description of Sternberg in 1823, although he identified them as plant remains. During the twentieth century there were a number of brief descriptions of hooks but it was Kulicki & Szaniawski (1972) who described 22 morphotypes from the Jurassic of Poland. These authors gave these 'forms' names using a binomial classification though, with many lacking defined (and figured) holotypes and, in some cases, only one recorded specimen, some of their designations should be regarded as invalid. Some of the morphotypes have, however, been reported from DSDP sites on the Falkland Plateau as well as New Zealand, Germany, Poland and the United Kingdom. It is clear that the hooks must belong to widely distributed members of the Belemnitida and Phragmoteuthida. Exceptional soft-bodied preservation of species such as Belemnotheutis antiquus from the Callovian-Oxfordian of the United Kingdom has allowed the identification of the host animal of some morphotypes, though the majority remain non-attributable. In the Christian Malford lagerstätte (Upper Callovian) of Wiltshire large numbers of hooks (including forms described as Acanthuncus, Arites, Deinuncus, Falcuncus, Longuncus and Paraglycerites) are found associated with an abundance of statoliths (cephalopod 'ear bones') and macrofossil evidence of both belemnites and teuthids, some of which includes exceptional soft-bodied preservation (see Wilby et al., 2004, 2008; Hart et al., in press). Using the abundance of material available to us from the Wessex Basin, we are attempting to identify, where possible, the host animals. If this can be established then it should be possible, using micropalaeontological samples, to determine the stratigraphical and palaeoecological ranges of some of the host macro-fossils, many of which are otherwise rarely preserved. HART, M.B., DE JONGHE

  9. Integrated geophysical studies on the area east of Abu Gharadig basin, southern Cairo, Egypt, using potential field data

    Science.gov (United States)

    El-Awady, Mohammed Mohamed; El-Badrawy, Hussein Tawfek; Abuo El-Ela, Amin Mohamed; Solimaan, Mohamed Refaat; Alrefaee, Hamed Abdelhamid; Elbowab, Mostafa

    2016-12-01

    Potential field data of the area east of Abu Gharadig basin were used to delineate the tectonic framework of probable economic interest and for future development plans for the area. To achieve this goal, the RTP and Bouguer gravity maps of the study area were subjected to several filtering and processing techniques. The regional magnetic map shows NE-SW high regional magnetic trends at the northwestern and southeastern parts as well as low magnetic trends at the central part reflecting thick non-magnetized sediments and/or deep highly magnetized basement rocks. Similarly, the regional gravity map shows NE-SW diagonal high and low gravity trends across the entire area of study as well as a distinct increase of gravity values toward the northwest corner reflecting thickening of sedimentary cover and/or deepening of denser basement rock at the central part. The residual maps reveal many anomalies of shallow sources with different polarities, amplitudes and extensions in the form of alternating high and low gravity and magnetic indicating that the basement rocks are dissected by faults forming uplifted and downthrown blocks. Edge detection techniques outlined effectively the boarders and extensions of the structural highs and lows through showing gravity and magnetic maxima over the edges of these tectonic features. Moreover, the River Nile course is controlled by shallow normal faults affecting the recent Nile sediments and is clearly shown by edge detection maps of gravity data. Euler deconvolution of magnetic and gravity data reveals clustering of solution along fault trends or causative bodies centers. The Euler depth estimate to the basement surface shows a good correlation with the depth determined by the power spectrum method where its value ranges around 4 km. The interpreted basement tectonic map of the study area is dominated by ENE-WSW Syrian Arc, NW-SE Gulf of Suez and Red Sea, NE-SW Aqaba, E-W Mediterranean and N-S East Africa tectonic trends. The older

  10. Status and understanding of groundwater quality in the Tahoe-Martis, Central Sierra, and Southern Sierra study units, 2006-2007--California GAMA Priority Basin Project

    Science.gov (United States)

    Fram, Miranda S.; Belitz, Kenneth

    2012-01-01

    Groundwater quality in the Tahoe-Martis, Central Sierra, and Southern Sierra study units was investigated as part of the Priority Basin Project of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program. The three study units are located in the Sierra Nevada region of California in parts of Nevada, Placer, El Dorado, Madera, Tulare, and Kern Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board, in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The project was designed to provide statistically robust assessments of untreated groundwater quality within the primary aquifer systems used for drinking water. The primary aquifer systems (hereinafter, primary aquifers) for each study unit are defined by the depth of the screened or open intervals of the wells listed in the California Department of Public Health (CDPH) database of wells used for municipal and community drinking-water supply. The quality of groundwater in shallower or deeper water-bearing zones may differ from that in the primary aquifers; shallower groundwater may be more vulnerable to contamination from the surface. The assessments for the Tahoe-Martis, Central Sierra, and Southern Sierra study units were based on water-quality and ancillary data collected by the USGS from 132 wells in the three study units during 2006 and 2007 and water-quality data reported in the CDPH database. Two types of assessments were made: (1) status, assessment of the current quality of the groundwater resource, and (2) understanding, identification of the natural and human factors affecting groundwater quality. The assessments characterize untreated groundwater quality, not the quality of treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentrations divided by benchmark concentrations) were used for evaluating groundwater quality for those

  11. Peruánská gastronomie

    OpenAIRE

    2013-01-01

    The aim of this thesis is to characterize culture and gastronomy of Peru as a specific tourist destination. First part -- the theoretical one -- deals with explanation of main terms from the fields of tourism and gastronomy. Following parts include characteristics of Peru and its gastronomy. The second chapter, in particular, involves basic information about realia, geography and history of Peru, followed by characteristics of tourism in the country. The third chapter, first of all, explains ...

  12. Natural Offshore Oil Seepage and Related Tarball Accumulation on the California Coastline - Santa Barbara Channel and the Southern Santa Maria Basin: Source Identification and Inventory

    Science.gov (United States)

    Lorenson, T.D.; Hostettler, Frances D.; Rosenbauer, Robert J.; Peters, Kenneth E.; Dougherty, Jennifer A.; Kvenvolden, Keith A.; Gutmacher, Christina E.; Wong, Florence L.; Normark, William R.

    2009-01-01

    Oil spillage from natural sources is very common in the waters of southern California. Active oil extraction and shipping is occurring concurrently within the region and it is of great interest to resource managers to be able to distinguish between natural seepage and anthropogenic oil spillage. The major goal of this study was to establish the geologic setting, sources, and ultimate dispersal of natural oil seeps in the offshore southern Santa Maria Basin and Santa Barbara Basins. Our surveys focused on likely areas of hydrocarbon seepage that are known to occur between Point Arguello and Ventura, California. Our approach was to 1) document the locations and geochemically fingerprint natural seep oils or tar; 2) geochemically fingerprint coastal tar residues and potential tar sources in this region, both onshore and offshore; 3) establish chemical correlations between offshore active seeps and coastal residues thus linking seep sources to oil residues; 4) measure the rate of natural seepage of individual seeps and attempt to assess regional natural oil and gas seepage rates; and 5) interpret the petroleum system history for the natural seeps. To document the location of sub-sea oil seeps, we first looked into previous studies within and near our survey area. We measured the concentration of methane gas in the water column in areas of reported seepage and found numerous gas plumes and measured high concentrations of methane in the water column. The result of this work showed that the seeps were widely distributed between Point Conception east to the vicinity of Coal Oil Point, and that they by in large occur within the 3-mile limit of California State waters. Subsequent cruises used sidescan and high resolution seismic to map the seafloor, from just south of Point Arguello, east to near Gaviota, California. The results of the methane survey guided the exploration of the area west of Point Conception east to Gaviota using a combination of seismic instruments. The

  13. Supervising road safety in Peru

    OpenAIRE

    Sagástegui, Freddy; Abogado, Adjuntía para el Medio Ambiente, Servicios Públicos y Pueblos Indígenas, Defensoría del Pueblo. Lima, Perú.

    2010-01-01

    In this article some problems in road safety are described, which have been detected by the Ombudsman of Peru, as part of its role of public administration supervisor, amongst these problems we mention: lack of and inadequate elaboration of the statistics on road traffic accidents, the inconsistency of the National Council for Road Security and the lack of responsibility of the local and regional governments reflected by the lack of application of the National Plan of Road Safety. facing ...

  14. Spatio-Temporal Analysis of Model and Satellite Based Soil Moisture Estimations for Assessing Coupling Hot Spots in the Southern La Plata Basin

    Science.gov (United States)

    Bruscantini, C. A.; Karszenbaum, H.; Ruscica, R. C.; Spennemann, P.; Salvia, M.; Sorensson, A. A.; Grings, F. M.; Saulo, C.

    2015-12-01

    The southern La Plata Basin, located in southeastern South America (SESA), a region of great importance because of its hydrological characteristics, the fact that it has the largest population density and is one of the most productive regions in terms of agriculture, cattle raising and industry of the continent, has been identified as a strong hotspot between soil moisture (SM) and the atmosphere by different regional studies. Among them, Ruscica et al. (2014, Atmos. Sci. Let, Int. J. Climatol.), and Spennemann et al. (2015, Int. J. Climatol.) show, through different modeling approaches, the presence of strong soil moisture-precipitation and evapotranspiration interactions during austral summer in SESA, revealing similar hotspots. Nevertheless these studies have diverse limitations related to model assumptions and to vegetation parameterizations, as well as the lack of observational data for the evaluation of models performance (Ferguson and Wood, 2011, J. of Hydrometeorology). On the other hand, in the last decade several instruments on board satellites are providing soil moisture products globally and in a continuous way. A recent work by Grings et al. (2015, IEEE JSTARS, in press), done over the Pampas Plains in SESA showed characteristic soil moisture patterns that follow the Standardized Precipitation Index (SPI) under extreme wet and dry conditions In order to deepen and overcome some of the mentioned model limitations, this work adds satellite soil moisture and vegetation products in the spatio-temporal analysis of the regions of strong soil moisture-atmosphere interactions. The main objectives and related outcomes are: the verification of already identified regions where soil moisture anomalies may have an influence on subsequent precipitation, evapotranspiration and temperature anomalies, and the study of their seasonal characteristics and land cover influences.

  15. Monitoring the Genotoxic and Cytotoxic Potential and the Presence of Pesticides and Hydrocarbons in Water of the Sinos River Basin, Southern Brazil.

    Science.gov (United States)

    Bianchi, Eloisa; Lessing, Gustavo; Brina, Karisa Roxo; Angeli, Larissa; Andriguetti, Natália Bordin; Peruzzo, Jaqueline Regina Soares; do Nascimento, Carlos Augusto; Spilki, Fernando Rosado; Ziulkoski, Ana Luiza; da Silva, Luciano Basso

    2017-04-01

    The Sinos River is one of the most polluted rivers in Brazil. The purpose of this work was to monitor the presence of some pesticides and hydrocarbons as well as the genotoxic and cytotoxic potential on HEp-2 cells from water samples collected at seven sites in the Sinos River Basin (SRB), southern Brazil. Nine samples were taken from the three main rivers in the SRB and used as a solution to dilute the HEp-2 cell culture medium after microfiltration. Twenty-four pesticides and 19 hydrocarbons were measured. Cytotoxicity was assessed by methyl thiazolyl tetrazolium (MTT) and neutral red (NR) assays, in which cells were exposed to different concentrations of the water samples for 24 h. Genotoxicity of the microfiltrated raw water samples was assessed by comet assay after 6 and 24 h of exposure. Among the chemicals analyzed, only the 2,4-D, dichloromethane, tetrachloroethene, chloroform, bromodichloromethane, styrene, and toluene were detected, but they were all lower than the limit established by Brazilian regulations. Twenty samples from a total of 60 had a cytotoxic effect in the MTT assay and 30 in the NR assay. The comet assay indicated the presence of genotoxic substances in the water at the seven locations monitored. Temporal and spatial variation was observed in the cytotoxicity and genotoxicity assays. Results indicated that the water in all stretches of the SRB is contaminated and it can cause harmful effects to humans and to the aquatic biota. This HEp-2 cell-line approach can be an additional tool for environmental monitoring.

  16. Kaolinite, illite and quartz dissolution in the karstification of Paleozoic sandstones of the Furnas Formation, Paraná Basin, Southern Brazil

    Science.gov (United States)

    Melo, Mário Sérgio de; Guimarães, Gilson Burigo; Chinelatto, Adilson Luiz; Giannini, Paulo César Fonseca; Pontes, Henrique Simão; Chinelatto, Adriana Scoton Antonio; Atencio, Daniel

    2015-11-01

    Karstification processes in sandstones of the Furnas Formation, Silurian to Devonian of the Paraná Basin, have been described since the mid-twentieth century. However, some geologists still doubt the idea of true karst in sandstones. St