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Sample records for eastern cordillera differences

  1. GPS velocities and the construction of the Eastern Cordillera of the Colombian Andes

    NASA Astrophysics Data System (ADS)

    Mora-Páez, Héctor; Mencin, David J.; Molnar, Peter; Diederix, Hans; Cardona-Piedrahita, Leonardo; Peláez-Gaviria, Juan-Ramón; Corchuelo-Cuervo, Yuli

    2016-08-01

    GPS velocities across the northeast trending Eastern Cordillera of Colombia show oblique convergence at 8.8 ± 1.7 mm/yr, consisting of 8.0 ± 1.7 mm/yr of right-lateral strike-slip shear along the mountain range and 3.7 ± 0.3 mm/yr of northwest southeast shortening. Faster convergence occurs only at the northeast end of the Cordillera, where its eastern edge trends northwest and the highest mountains lie. The strike-slip shear corroborates geologic work suggesting such movement southwest and northeast of the range. Given the ~200 km width of the Eastern Cordillera, the ~100-150 km of crustal shortening inferred from balanced cross sections and implied by recent estimates of crustal thickness would require ~25-40 Myr of shortening at ~4 mm/yr. The present-day GPS measurements, therefore, are inconsistent with the inference, based on paleobotanical observations that the entire Eastern Cordillera rose 1500-2500 m since 3-6 Ma and called for a different interpretation of those data.

  2. DNA Barcoding Survey of Anurans across the Eastern Cordillera of Colombia and the Impact of the Andes on Cryptic Diversity.

    PubMed

    Guarnizo, Carlos E; Paz, Andrea; Muñoz-Ortiz, Astrid; Flechas, Sandra V; Méndez-Narváez, Javier; Crawford, Andrew J

    2015-01-01

    Colombia hosts the second highest amphibian species diversity on Earth, yet its fauna remains poorly studied, especially using molecular genetic techniques. We present the results of the first wide-scale DNA barcoding survey of anurans of Colombia, focusing on a transect across the Eastern Cordillera. We surveyed 10 sites between the Magdalena Valley to the west and the eastern foothills of the Eastern Cordillera, sequencing portions of the mitochondrial 16S ribosomal RNA and cytochrome oxidase subunit 1 (CO1) genes for 235 individuals from 52 nominal species. We applied two barcode algorithms, Automatic Barcode Gap Discovery and Refined Single Linkage Analysis, to estimate the number of clusters or "unconfirmed candidate species" supported by DNA barcode data. Our survey included ~7% of the anuran species known from Colombia. While barcoding algorithms differed slightly in the number of clusters identified, between three and ten nominal species may be obscuring candidate species (in some cases, more than one cryptic species per nominal species). Our data suggest that the high elevations of the Eastern Cordillera and the low elevations of the Chicamocha canyon acted as geographic barriers in at least seven nominal species, promoting strong genetic divergences between populations associated with the Eastern Cordillera.

  3. DNA Barcoding Survey of Anurans across the Eastern Cordillera of Colombia and the Impact of the Andes on Cryptic Diversity

    PubMed Central

    Guarnizo, Carlos E.; Paz, Andrea; Muñoz-Ortiz, Astrid; Flechas, Sandra V.; Méndez-Narváez, Javier; Crawford, Andrew J.

    2015-01-01

    Colombia hosts the second highest amphibian species diversity on Earth, yet its fauna remains poorly studied, especially using molecular genetic techniques. We present the results of the first wide-scale DNA barcoding survey of anurans of Colombia, focusing on a transect across the Eastern Cordillera. We surveyed 10 sites between the Magdalena Valley to the west and the eastern foothills of the Eastern Cordillera, sequencing portions of the mitochondrial 16S ribosomal RNA and cytochrome oxidase subunit 1 (CO1) genes for 235 individuals from 52 nominal species. We applied two barcode algorithms, Automatic Barcode Gap Discovery and Refined Single Linkage Analysis, to estimate the number of clusters or “unconfirmed candidate species” supported by DNA barcode data. Our survey included ~7% of the anuran species known from Colombia. While barcoding algorithms differed slightly in the number of clusters identified, between three and ten nominal species may be obscuring candidate species (in some cases, more than one cryptic species per nominal species). Our data suggest that the high elevations of the Eastern Cordillera and the low elevations of the Chicamocha canyon acted as geographic barriers in at least seven nominal species, promoting strong genetic divergences between populations associated with the Eastern Cordillera. PMID:26000447

  4. The Servita Fault, Colombian Eastern Cordillera: Origin, Geotectonics, and Seismicity

    NASA Astrophysics Data System (ADS)

    Chicangana, G.; Kammer, A.; Vargas Jiménez, C. A.; Caneva, A.; Pedraza, P.; Salcedo, E.; Gomez, A.; Muñoz, F.

    2014-12-01

    The Servita fault is a thrust located in the center of Colombia and whose main scarp is at 5 km west of Villavicencio (500.000 inhabitants). According to geophysics data as gravity, magnetic, and seismic, this fault was confirmed how a large cortical structure in the Colombian Eastern Cordillera. The Servita fault possibly was originated like a suture that derived of a continental collision in Late Mesoproterozoic times when Rodinia was conform totally. The Servita Fault as normal fault in Mesozoic times contributed to the Colombian Cretaceous basin development. In Late Cretaceous because to collision of the Caribbean plate with the northwestern corner of South America a strong compressive stress was occur and kinematics changes were presented in the normal faults restrained to the basin like among others the Servita Fault, where these were converted in inverse faults. From early Pliocene until Present times the Servita Fault controlled the growth of the Cordillera and the Llanos foothills in this sector of Central Colombia. Result of this is the seismicity activity registered for this region from historical times (less of 500 years for Colombian case). Two earthquakes have transcended in this region in last three centuries: the first one occurred on October 18th, 1743 with a current probabilistic magnitude greater than 6.5 and the second one struck on May 24th, 2008 with a M = 5.9. In this work we show how this fault has develop from its origin, and how this can would produce a M > 6.5 earthquake very close to metropolitan area of Bogota D.C., and Villavicencio. This earthquake would destroy both urban areas resulting in high losses in lives and economic terms. The seismicity activity of the Servita Fault and its associated structures is registered by the National Seismological Network of Colombia and the Sabana de Bogotá Seismological Network.

  5. Emeralds in the Eastern Cordillera of Colombia: Two tectonic settings for one mineralization

    NASA Astrophysics Data System (ADS)

    Branquet, Yannick; Laumonier, Bernard; Cheilletz, Alain; Giuliani, Gaston

    1999-07-01

    Colombian emeralds are formed through a hydrothermal-sedimentary process. On the western side of the Eastern Cordillera, the deposits are linked by tear faults and associated thrusts developed during a compressive tectonic phase that occurred at the time of the Eocene-Oligocene boundary, prior to the major uplift of the Cordillera during the Andean phase (middle Miocene). On the eastern side of the Cordillera, emerald mineralization occurred earlier, at the time of the Cretaceous-Tertiary boundary, during a thin-skinned extensional tectonic event linked to evaporite dissolution. This event predates the Andean phase, during which this part of the chain was folded and thrust over the Llanos foreland.

  6. Cenozoic contractional reactivation of Mesozoic extensional structures in the Eastern Cordillera of Colombia

    NASA Astrophysics Data System (ADS)

    Mora, AndréS.; Parra, Mauricio; Strecker, Manfred R.; Kammer, Andreas; Dimaté, Cristina; RodríGuez, Fernando

    2006-04-01

    The Eastern Cordillera of Colombia is key to understanding the role of inherited basement anisotropies in the evolution of active noncollisional mountain belts. In particular, the Rio Blanco-Guatiquía region of the Eastern Cordillera is exemplary in displaying a variety of phenomena that document the importance of the orientation, geometry, and segmentation of preorogenic anisotropies. We document the first unambiguous evidence that extensional basement structures played an important role in determining the locus of deformation during contractional reactivation in the Eastern Cordillera. Detailed structural field mapping and analysis of industry seismic reflection profiles have helped to identify the inherited San Juanito, Naranjal, and Servitá normal faults and associated transfer faults as important structures that were inverted during the Cenozoic Andean orogeny. Apparently, the more internal faults in the former rift basin were not properly oriented for an efficient reactivation in contraction. However, these faults have a fundamental role as strain risers, as folding is concentrated west of them. In contrast, reactivated normal faults such as the more external Servitá fault are responsible for uplifting the eastern flank of the Eastern Cordillera. In addition, these structures are adjacent and intimately linked to the development of thin-skinned faults farther east. In part, the superimposed compression in this prestrained extensional region is compensated by lateral escape. The dominant presence of basement involved buckling and thrusting, and the restricted development of thin-skinned thrusting in this inversion orogen makes the Eastern Cordillera a close analog to the intraplate Atlas Mountains of Morocco and other inverted sectors of the Andean orogen farther south.

  7. Active shallow extension in central and eastern Betic Cordillera from CGPS data

    NASA Astrophysics Data System (ADS)

    Galindo-Zaldivar, J.; Gil, A. J.; Sanz de Galdeano, C.; Lacy, M. C.; García-Armenteros, J. A.; Ruano, P.; Ruiz, A. M.; Martínez-Martos, M.; Alfaro, P.

    2015-11-01

    The Betic Cordillera is an Alpine belt formed in the western Mediterranean by the westward displacement of the Alboran Domain in between the Eurasian and African convergent plates. New CGPS data from the central and eastern Betic Cordillera and its foreland-obtained mainly from the Topo-Iberia project-allowed us to precisely determine the rate of tectonic deformation. Most of the displacements of the central and eastern Betics are westward, with a variable southwestward component, in relation to the Eurasian stable plate. While in the Iberian foreland the displacements are extremely low, some deformation related to low compressional deformation occurs in the easternmost foreland basin and eastern Betic Cordillera. The displacement increases substantially southwards and westwards in relation to present-day extensional deformation. Major active discontinuities correspond to the NW-SE normal fault zones, which dip westwards; they are located in Almeria-Tabernas; Balanegra, and western Sierra de Gador; whereas the Padul fault zone located west of Sierra Nevada extends northwards to the Granada Basin. NW-SE extensional faults are also observed to the north, in the Baza Basin. Moreover, the activity of dextral faults along the Sorbas-Tabernas-Alpujarras-Guajares band, generally considered as a transfer fault zone, is evidenced by the displacement data. These results come to demonstrate the low activity or inactivity of the large northern E-W oriented folds of the central and eastern Internal Zone, such as the Sierra de Los Filabres antiform. They also point to the possible residual activity of the northern part of the NE-SW Sierra Nevada antiform, where the maximum relief of the Cordillera is found. Altogether, our data support a heterogeneous present-day westward extension that affects the upper crust of the Betic Cordillera and increases towards the thinned continental crust of the Alboran Sea and towards the west, which is compatible with roll-back subduction along

  8. Oblique transpression in the western thrust front of the Colombian Eastern Cordillera

    NASA Astrophysics Data System (ADS)

    Acosta, J.; Lonergan, L.; Coward, M. P.

    2004-11-01

    New kinematic data reveal that the main faults of the western foothills of the Colombian Eastern Cordillera are a series of left-lateral to oblique thrusts that are offset by steeply dipping, northwest-trending, left-lateral, strike-slip faults. Kinematic data were collected from the main structures that dominate the 350-km length of the western foothills of the Eastern Cordillera, north of Bogota (La Salina-Bituima, Cambrás, Dos Hermanos-Alto del Trigo, and Bucaramanga faults). These data indicate that transpression is responsible for the Cenozoic formation of the folds and thrusts that deform the Mesozoic and Cenozoic sedimentary sequences of the Middle Magdalena Valley. Kinematic and structural data suggest that the La Salina-Bituima fault changed from a reverse fault to a fault with a left-lateral, strike-slip sense of displacement during middle to late Miocene times. As it propagated, a transpressive zone was generated in the western foothills of the Eastern Cordillera, with the development of arcuate, oblique-reverse secondary faults on the leading edge of the Magdalena basin (e.g. Cambrás, Dos Hermanos). This development implies that during the Neogene (?), the tectonics of the western foothills were dominated by nonplanar deformation with shortening accompanied by significant left-lateral, strike-slip displacements. These new data indicate that the oblique convergence vector imposed by convergence among the Nazca, Caribbean, and South American plates is not fully partitioned in space but instead must be distributed in a diffuse zone of transpressional deformation along the western margin of the Eastern Cordillera and its associated foreland basin.

  9. A distinctive new subspecies of Scytalopus griseicollis (Aves, Passeriformes, Rhinocryptidae) from the northern Eastern Cordillera of Colombia and Venezuela

    PubMed Central

    Avendaño, Jorge Enrique; Donegan, Thomas M.

    2015-01-01

    Abstract We describe a new subspecies of Pale-bellied Tapaculo Scytalopus griseicollis from the northern Eastern Cordillera of Colombia and Venezuela. This form differs diagnosably in plumage from described subspecies Scytalopus griseicollis griseicollis and Scytalopus griseicollis gilesi and from the latter in tail length. It is also differentiated non-diagnosably in voice from both these populations. Ecological niche modelling analysis suggests that the new subspecies is restricted to the Andean montane forest and páramo north of both the arid Chicamocha valley and the Sierra Nevada del Cocuy. PMID:26085800

  10. The basement of the Eastern Cordillera, Colombia: An allochthonous terrane in northwestern South America

    NASA Astrophysics Data System (ADS)

    Forero Suarez, A.

    The fault system of the Borde Llanero of Colombia represents the limit between two early Paleozoic geologic provinces: the Guiana Shield (Gondwana) to the east, and an allochthonous terrane — formerly a piece of the North American continent — to the west. The Baudó Range, the Western Cordillera, and the western flank of the Central Cordillera are the result of post-Jurassic accretion. In contrast the pre-Emsian metamorphic rocks of the eastern flank of the Central Cordillera, of the Eastern Cordillera of Colombia, and of the Mérida Andes correspond to an allochthonous terrane that was accreted to the north-western continental border of South America during the collision between North America and Gondwana in Silurian-Early Devonian times. Geochronologic and petrographic data indicate the presence of the Grenvillian granulite belt, represented by the Garzón-Sierra Nevada de Santa Marta belt. This belt is separated from the Guiana Shield by a magmatic tract which is parallel to the Borde Llanero of Venezuela and Colombia. The late Paleozoic regional metamorphism in the Northern Andes of Colombia occurred during Late Silurian-Early Devonian times. Since the late Emsian, a sedimentary cycle was initiated on this allochthonous basement. The faunal records of northwestern South America and the North American continent are indistinguishable for that time. This similarity clearly shows that both northwestern South America and the North American regions of the Appalachians and New Mexico belong to the same paleobiogeographic province. The faunal communication in this case supports the idea of the immediate neighborhood of the two continents.

  11. The final phase of tropical lowland conditions in the axial zone of the Eastern Cordillera of Colombia: Evidence from three palynological records

    NASA Astrophysics Data System (ADS)

    Ochoa, D.; Hoorn, C.; Jaramillo, C.; Bayona, G.; Parra, M.; De la Parra, F.

    2012-11-01

    Deformation of the Eastern Cordillera, as a double-verging thrust belt that separates the Magdalena Valley from the Llanos Basin, is a defining moment in the history of the northern Andes in South America. Here we examine the age and depositional setting of the youngest stratigraphic unit in three sectors of the Eastern Cordillera: (i) the Santa Teresa Formation (western flank), (ii) the Usme Formation (southern central axis), and (iii) the Concentración Formation (northeastern central axis). These units were deposited prior to the main Neogene deformation events. They represent the last preserved record of lowland conditions in the Eastern Cordillera, and they are coeval with a thick syn-orogenic deposition reported in the Llanos Basin and Magdalena Valley. Based on palynological data, we conclude that the upper Usme Formation was deposited during the Bartonian-earliest Rupelian? (Late Eocene-earliest Oligocene?); the Concentración Formation was deposited during the Late Lutetian-Early Rupelian (Middle Eocene to Early Oligocene), and the upper Santa Teresa Formation was accumulated during the Burdigalian (Early Miocene). These ages, together with considerations on maximum post-depositional burial, provide important time differences for the age of initial uplift and exhumation along the axial zone and western foothills of the Eastern Cordillera. The switch from sediment accumulation to erosion in the southern axial zone of the Eastern Cordillera occurred during the Rupelian-Early Chattian (Oligocene, ca 30 to ca 26 Ma), and in the northeastern axial zone occurred prior to the latest Chattian-Aquitanian (latest Oligocene-Early Miocene ca 23 Ma). In contrast, in the western flank, the switch occurred during the Tortonian (Late Miocene, ca 10 Ma). In addition, we detected a marine transgression affecting the Usme and Concentración formations during the Late Eocene; coeval marine transgression has been also documented in the Central Llanos Foothills and Llanos Basin

  12. The El Abra stadlal in the Eastern Cordillera of Colombia (South America)

    NASA Astrophysics Data System (ADS)

    Kuhry, P.; Hooghiemstra, H.; van Geel, B.; van der Hammen, T.

    The El Abra stadial is a climatic cooling event defined in the Eastern Cordillera of Colombia, which corresponds both in timing and intensity to the Younger Dryas climatic oscillation of the northern North Atlantic region. The stadial was preceded by the relatively warm Guantiva interstadial and followed by the warm Holocene. Colder climatic conditions during the El Abra stadial caused a 400 m lowering of the upper Andean forest limit below its altitudinal location during the preceding Guantiva interstadial. Translated in temperature change, this represents a drop in mean annual temperature of approximately 2 to 3°C. The lowering of the upper forest limit and inferred temperature change for the El Abra stadial, compared to Late Holocene conditions, are in the order of 600 m and 4°C, respectively. The transition of the Guantiva interstadial to the El Abra stadial has been radiocarbon dated at 11,210 ± 90 BP and 10,820 ± 60 BP. Climatic warming may have started shortly after 10,380 ± 90 BP, and near present-day temperatures were reached at least as early as 8920 ± 100 BP. Maximum cooling was probably attained between 10,800 BP and 10,300 BP. Further (AMS) radiocarbon dating is planned to establish more exactly the timing of the El Abra stadial. A glacial advance of El Abra age, the Bocatoma stade, has been recognized in the highest part of the Colombian Eastern Cordillera, the Sierra Nevada del Cocuy. During this advance, glaciers extended some 700 m lower than at present. A climatic cooling event of El Abra age, associated with shifts of the upper Andean forest limit and glacial advances, has also been recognized in other parts of Andean Colombia, including the Central Cordillera and the Sierra Nevada de Santa Marta.

  13. Multiproxy paleolimnological evidence of Holocene temperature and precipitation variability from the Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Bixler, C. W.; Shanahan, T. M.

    2011-12-01

    The late Holocene was characterized by a number of significant, widespread multi-century climate anomalies, the most prominent and well documented of which are the Little Ice Age and the Medieval Warm Period. Existing paleoclimate reconstructions from South and Central America provide evidence for anomalous climate conditions during these time periods but the spatial and temporal resolution of existing records is limited and quantitative data on the magnitudes of these events is lacking. These limitations make it difficult to fully evaluate the causes and large scale impacts of these apparently global events. Here, we present new high-resolution multiproxy lacustrine records of late Holocene climate change in the Eastern Cordillera of Colombia over the last 2 millennia by combining high-resolution core scanning approaches with molecular and stable isotope analysis of lipid biomarkers. Preliminary paleoclimate reconstructions from these archives suggest that the northern tropics of South America strongly reflect global century-scale climate variability over this time period, with significant hydrologic and temperature anomalies that are broadly synchronous with events in the high latitudes of the northern hemisphere. The magnitude and widespread nature of late Holocene century-scale droughts in this region likely had significant ecological and societal impacts in the Eastern Cordillera.

  14. Growth and gravitational collapse of a mountain front of the Eastern Cordillera of Colombia

    NASA Astrophysics Data System (ADS)

    Kammer, Andreas; Montana, Jorge; Piraquive, Alejandro

    2016-04-01

    The Eastern Cordillera of Colombia is bracketed between the moderately east-dipping flank of the Central Cordillera on its western and the gently bent Guayana shield on its eastern side. It evolved as a response to a considerable displacement transfer from the Nazca to the Southamerican plate since the Oligocene break-up of the Farallon plate. One of its distinctive traits refers to its significant shortening by penetrative strain at lower and folding at higher structural levels, approximating a wholesale pure-shear in analogy to a vice model or a crustal welt sandwiched between rigid buttresses. This contrasting behavior may be explained by the spatial coincidence between Neogene mountain belt and a forebulge that shaped the foreland trough during a Cretaceous subduction cycle and was very effective in localizing a weakening of the backarc region comprised between two basin margin faults. In this paper we examine a two-phase evolution of the Eastern mountain front. Up to the late Miocene deformation was restrained by the inherited eastern basin margin fault and as the cordilleran crust extruded, a deformation front with an amplitude similar the present structural relief of up to 10.000 m may have built up. In the Pliocene convergence changed from a roughly strike-perpendicular to an oblique E-W direction and caused N-S trending faults to branch off from the deformation front. This shortening was partly driven by a gravitational collapse of the Miocene deformation front, that became fragmented by normal faults and extruded E on newly formed Pliocene thrust faults. Normal faults display displacements of up to 3000 m and channelized hydrothermal fluids, leading to the formation of widely distributed fault breccias and giving rise to a prolific Emerald mineralization. In terms of wedge dynamics, the Pliocene breaching of the early formed deformation front helped to establish a critical taper.

  15. Structural and thermochronological evidence for Paleogene basement-involved shortening in the axial Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Saylor, Joel E.; Horton, Brian K.; Stockli, Daniel F.; Mora, Andrés; Corredor, Jaime

    2012-11-01

    Although most recent studies regard the northern Andes primarily as a low-shortening inversion orogen, new mapping and thermochronology along the paired basement-involved Floresta massif and Floresta basin in the axial Eastern Cordillera of Colombia suggest major Paleogene shortening in a ramp-flat fold-thrust belt. Field mapping indicates that the hanging wall of the east-directed Soápaga fault system contains a series of upright thrust sheets with flat-on-flat cutoff relationships and a deformed footwall characterized by a complex triangle zone. These geometries necessitate roughly east-west shortening exceeding that of a previously mapped overturned hanging wall anticline and disharmonic footwall folds. Zircon (U-Th)/He (ZHe) ages indicate exhumation-induced cooling of the Soápaga hanging wall through the ˜180 °C closure temperature at 31-25 Ma. This cooling postdated documented shortening to the west and predated shortening to the east, suggesting an eastward progression of Paleogene deformation. Synorogenic Oligocene footwall strata of the Floresta basin contain distal fine-grained sediments and lack growth strata or Oligocene detrital ZHe ages, suggesting relatively high heave along the Soápaga fault system. These results are consistent with a rapidly eastward-propagating, basement-involved fold-thrust belt with ramp-flat structures that accommodated tens of km of shortening. Long-term stasis of the deformation front on the eastern and western flanks of the Eastern Cordillera due to localization of Neogene shortening along Mesozoic rift-bounding normal faults indicates a shift in deformational style in late Oligocene-early Miocene time. This geometric and temporal framework implies: 1) a total shortening in the northern Andes exceeding most current estimates; 2) Paleogene deformation in the Eastern Cordillera marked by rapid advances of the deformation front along a ramp-flat thrust system; and 3) focused Neogene reactivation (inversion) of master rift

  16. The magmatic history of the Vetas-California mining district, Santander Massif, Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Mantilla Figueroa, Luis C.; Bissig, Thomas; Valencia, Víctor; Hart, Craig J. R.

    2013-08-01

    The Vetas-California Mining District (VCMD), located in the central part of the Santander Massif (Colombian Eastern Cordillera), based on U-Pb dating of zircons, records the following principal tectono-magmatic events: (1) the Grenville Orogenic event and high grade metamorphism and migmatitization between ˜1240 and 957 Ma; (2) early Ordovician calc-alkalic magmatism, which was synchronous with the Caparonensis-Famatinian Orogeny (˜477 Ma); (3) middle to late Ordovician post-collisional calc-alkalic magmatism (˜466-436 Ma); (4) late Triassic to early Jurassic magmatism between ˜204 and 196 Ma, characterized by both S- and I-type calc-alkalic intrusions and; (5) a late Miocene shallowly emplaced intermediate calc-alkaline intrusions (10.9 ± 0.2 and 8.4 ± 0.2 Ma). The presence of even younger igneous rocks is possible, given the widespread magmatic-hydrothermal alteration affecting all rock units in the area. The igneous rocks from the late Triassic-early Jurassic magmatic episodes are the volumetrically most important igneous rocks in the study area and in the Colombian Eastern Cordillera. They can be divided into three groups based on their field relationships, whole rock geochemistry and geochronology. These are early leucogranites herein termed Alaskites-I (204-199 Ma), Intermediate rocks (199-198 Ma), and late leucogranites, herein referred to as Alaskites-II (198-196 Ma). This Mesozoic magmatism is reflecting subtle changes in the crustal stress in a setting above an oblique subduction of the Panthalassa plate beneath Pangea. The lower Cretaceous siliciclastic Tambor Formation has detrital zircons of the same age populations as the metamorphic and igneous rocks present in the study area, suggesting that the provenance is related to the erosion of these local rocks during the late Jurassic or early Cretaceous, implying a local supply of sediments to the local depositional basins.

  17. 18,000 years of environmental change in the Eastern Cordillera of the Bolivian Andes

    NASA Astrophysics Data System (ADS)

    Williams, J. J.; Gosling, W. D.; Coe, A. L.; Brooks, S. J.

    2010-12-01

    Mountainous regions are considered to be early warning sites for climatic change because narrow vertical species ranges mean even small temperature/precipitation variation can result in species movement. This is especially true in the tropical Andes where the complex topography of the Andean valleys allows biodiverse woodland to be separated from grassland and snow dominated peaks by just a few kilometers, with microclimates clearly playing an important role. To begin to predict the likely impacts of future climatic changes and to help protect Andean woodlands, an understanding of baseline ecological conditions and previous responses to longer-term climatic shifts is vital. The Cochabamba Basin and surrounding mountain peaks is situated within the Eastern Andean Cordillera on the margin between the Altiplano and Yungas cloud forest. We present here multi-proxy data from two high elevation (>3400 m) lake sediment records which reveal sub-500 year ecosystem response to climatic shifts since the last glacial period and the impact of pre-Hispanic human populations. The sediment cores recovered from Lakes Challacaba (17°33’ S, 65°34’ W, 3400 m) and Khomer Kocha (17°16’ S, 65°43’ W, 4153 m) span the last c. 4000 and c. 18,000 years respectively. The two sites are only 35 km apart but are positioned within very different climatic and vegetation zones; Challacaba is within a cold and seasonally dry valley, and Khomer Kotcha is located on the steep slopes above the Yungas cloud forests. Analysis of pollen, chironomid, charcoal, geochemical and physical proxies from within the sediment cores provided insight into the drivers of environmental change at a local and regional scale. The Challacaba and Khomer Kocha records are the first from the eastern flank of the Bolivian Andes to record the last 4000 years and help to fill a gap in our understanding of vegetation succession and subsequent climatic variability since the late glacial. Our results suggest that, prior

  18. Drainage reorganization during mountain building in the river system of the Eastern Cordillera of the Colombian Andes

    NASA Astrophysics Data System (ADS)

    Struth, Lucía; Babault, Julien; Teixell, Antonio

    2015-12-01

    The Eastern Cordillera of Colombia is a thick-skinned thrust-fold belt that is characterized by two topographic domains: (1) the axial zone, a high altitude plateau (the Sabana de Bogotá, 2500 masl) with low local relief and dominated by longitudinal rivers, and (2) the Cordillera flanks, where local relief exceeds 1000 m and transverse rivers dominate. On the basis of an analysis of digital topography and river parameters combined with a review of paleodrainage data, we show that the accumulation of shortening and crustal thickening during the Andean orogeny triggered a process of fluvial reorganization in the Cordillera. Owing to a progressive increase of the regional slope, the drainage network evolves from longitudinal to transverse-dominated, a process that is still active at present. This study provides the idea of progressive divide migration toward the inner part of the mountain belt, by which the area of the Sabana de Bogotá plateau is decreasing, the flanks increase in area, and ultimately transverse rivers will probably dominate the drainage of the Cordillera.

  19. On the lag time between internal strain and basement involved thrust induced exhumation: The case of the Colombian Eastern Cordillera

    NASA Astrophysics Data System (ADS)

    Mora, Andrès; Blanco, Vladimir; Naranjo, Julian; Sanchez, Nelson; Ketcham, Richard A.; Rubiano, Jorge; Stockli, Daniel F.; Quintero, Isaid; Nemčok, Michal; Horton, Brian K.; Davila, Hamblet

    2013-07-01

    Thrust sheets accumulate internal strain before they start moving along discrete fault planes. However, there are no previous studies evaluating the time difference between initiation of strain and fault displacement. In this paper we use observations from the Eastern Cordillera of Colombia to evaluate this interval. We utilize multiple thermochronometers and paleothermometers to refine the timing of deformation. Based on these new data we build time-temperature path estimates that together with geometric outcrop-based structural analysis and fluid inclusions allow us to assign relative timing to features associated with strain, such as cleavage, veins and certain types of fractures, and compare that with the timing of thrusting. We find that cleavage was only formed close to maximum paleotemperatures, almost coeval with the onset of thrust-induced denudation by the Late Oligocene. The corresponding structural level of fold-related veins suggest that they were formed later but still when the country rocks were at temperatures higher than 160 °C, mostly during the Early Miocene and still coexisted with the latest stages of cleavage formation. Our data show that the main period of strain hardening was short (probably a few million years) and occurred before first-order basement thrusting was dominant, but was associated with second-order folding.

  20. Three-dimensional structural evolution and kinematics of the Piedemonte Llanero, Central Llanos foothills, Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Egbue, Obi; Kellogg, James

    2012-11-01

    The Piedemonte Llanero is a wedge duplex zone in the Llanos foothills on the eastern flank of the Eastern Cordillera of Colombia. It is located northeast of the Cusiana and Cupiagua hydrocarbon fields. The area is characterized by a series of moderate to high-angle duplexes with east-southeast verging thin-skinned and thick-skinned tectonics. We present a structural model constrained by 2-D and 3-D seismic reflection data, surface geology, and well data. The structural analysis is based on backward modeling (kinematic restoration) and forward modeling using transfer-flexural slip and fault slip fold algorithms. The structures are significantly tighter in the northern segment compared to the southern segment of the overthrust trend. We estimate approximately 17 km of shortening in the northern duplex zone, and about 26 km total shortening for the southern duplex zone. We propose that thin-skinned in-sequence imbricate thrust stack deformation produced most of the shortening. The main Andean deformation (80% of the total shortening) commenced in the Piedemonte area about 6 Ma with rapid shortening and uplift in the area resulting in the development of an active-roof duplex structure as the cover was bulldozed forward by a horse block (Monterralo anticline) ramping up to a detachment at the base of C2, then ramping to the surface as the Yopal thrust. Later the horse blocks in the wedge rose, underthrusting the cover in a passive-roof duplex triangle zone. This was followed by an out-of-sequence Laramide-style thick-skinned basement-uplift of the range which produced much of the structural relief of the Eastern Cordillera. Cenozoic deformation in the Eastern Cordillera has been primarily range-normal, but has involved an increasing component of mountain-parallel right-lateral shear in the last 2 Ma.

  1. Eastward extent of the Late Eocene-Early Oligocene onset of deformation across the northern Andes: constraints from the northern portion of the Eastern Cordillera fold belt, Colombia

    NASA Astrophysics Data System (ADS)

    Corredor, Freddy

    2003-12-01

    New geologic information supports an interpretation of the initiation of tectonic uplift in the eastern margin of the Eastern Cordillera of Colombia and the onset of deformation across the northern Andes during the Late Eocene-Early Oligocene. The eastern edge of Late Eocene-Early Oligocene deformation was located at the present site of the eastern margin of the Eastern Cordillera. This uplift can be linked to tectonic events already described for the western margin of the Eastern Cordillera. On the basis of an interpretation of geologic maps, a new regional balanced cross-section across the region, seismic reflection profiles, remote sensing images, and biostratigraphic data, three major deformation events are invoked to describe the evolution of this fold belt. The first event occurred early during the Late Eocene-Early Oligocene and formed a NE-vergent imbricate fan. This imbricate fan was eroded and covered by Late Oligocene deposits, which formed a major angular unconformity. A subsequent compressional event in Miocene-Pliocene times (Andean orogeny) reactivated preexisting thrust faults and created new ones that folded those formed during the earlier event. These younger thrust faults also offset and folded the angular unconformity. Finally, a more recent tectonic event refolded the structures from the previous events. The thin-skinned thrust system of the northeastern margin of the Eastern Cordillera of Colombia can be linked to a foot wall shortcut of the inverted Servitá fault formed during the Late Eocene-Recent inversion of a Jurassic-Cretaceous extensional basin.

  2. Faults delineation and stress orientations from the microseismicity analysis of the Servita Fault System, Colombian Eastern Cordillera

    NASA Astrophysics Data System (ADS)

    Pedraza García, P.; Dimate, C.

    2014-12-01

    The Servita Fault System (SFS) is located in the eastern foothills of the Colombian Andes Eastern Cordillera. This region is a structurally complex area with high seismogenic potential. The refined analysis of the microseismicity registered by a portable seismic network allows to delineate the main active faults and to estimate the direction of the regional tectonic stress. We analyzed a high quality microearthquake data-set consisting of 890 events occurred during 2011-2012 with a local magnitude range between 0.1 and 3.2 and depths up to 40km. The refined locations of the events show a general SW-NE trend that follows the trace of the SFS. Selected focal mechanisms show predominantly right-lateral strike slip motion. Results show that seismicity to the northern sector of the SFS is distributed in two groups, one on the axial zone of the cordillera and the other on the eastern flank. Most of the microearthquakes are concentrated in the rupture zone of Quetame earthquake (2008, Mw=5.9). Alignment of hypocenters along the eastern flank and some focal mechanisms suggest a fault plane dipping to the west, which is interpreted as the Servita Fault plane. Southwards of the Rio Negro, seismicity decreases and loses continuity. This feature coincides with the trace of the WSW-ENE Rio Blanco Fault which possibly segments the Servita Fault. Southwards, seismicity is spread over a wider area and exhibits deeper hypocenters compared to the northern sector. Hypocenter distribution and focal mechanisms in this sector suggest two planes dipping to the west which we interpret as segments of the Algeciras Fault and another plane (northwards) steeply dipping to the southeast interpreted as the fault plane of the Altamira Fault.

  3. Geochemistry, paleoenvironment and timing of Lower Aptian organic rich beds of Paja Formation (Eastern Cordillera, Colombia)

    NASA Astrophysics Data System (ADS)

    Gaona Narvaez, T.; Maurrasse, F. J.; Etayo Serna, F.

    2011-12-01

    High-resolution analyses were carried out on two sections of the Colombian Eastern Cordillera to determine the stratigraphic and geochemical relationship between some Aptian-age organic-rich levels within the Paja Fm and the Oceanic Anoxic Event 1a. These analyses included: petrography, total inorganic carbon (TIC, wt% CaCO3), total organic carbon (TOC, wt% C), stable carbon isotopes in the organic matter (δ13Corg), and ammonite biostratigraphy. In a global context, the Lower Aptian organic-rich marine sediments are believed to include an episode of anoxia referred as the "Oceanic Anoxic Event 1a" (OAE-1a), which correlates with δ13C stages C3 to C6, and had a duration of about 1.0 to 1.3 MA [1,2]. At the Villa de Leiva section (Tunja-Villa de Leiva road), a 115 m succession of the Paja Fm Arcillolitas Abigarradas Member was studied. At this locality the unit has a prominent 4m-thick interval of black shale, ten meters below the base of the lowest Upper Aptian (Gargasian) Dufrenoyia sanctorum-Stoyanowiceras treffryanus ammonite assemblage zone [3]. Similarly, at Curiti Quarry (San Gil-Curiti road), a 12 m section includes an 8 m-thick organic-rich shale at the basal interval of the Paja Fm. At this locality the succession overlies the Barremian-age carbonate ramp deposits of the Rosablanca Fm; and the base of the Paja Fm yielded a reworked and phosphatized assemblage of middle Barremian to lowest Aptian ammonites of the genera Pulchellia, Gerhardtia, Toxancycloceras, Karsteniceras and Prodeshayesites. At Villa de Leiva, the 4 m-thick interval of TOC-rich clay-shale and marlstones (191.6 m to 195.5 m), shows horizontal laminae associated with gypsum, absence of bioturbation and benthic fossils, and presence of pyritic concretions. At this locality the studied interval has TOC values between 1.17% and 5.33%; and the Fm Paja is interpreted as have been deposited under anoxic conditions in a subtidal, hypersaline environment. Carbon isotope data below the base of the

  4. New thermo and geochronological constraints on the Pliocene-Pleistocene eruption history of the Paipa-Iza volcanic complex, Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Bernet, Matthias; Urueña, Cindy; Amaya, Sergio; Peña, Mary L.

    2016-11-01

    The Paipa-Iza volcanic complex is the only volcanic edifice in the Eastern Cordillera of Colombia. Zircon fission-track and Usbnd Pb data from deposits of two eruption epochs presented in this study constrain the time of volcanic activity between 5.9 Ma in the late Miocene and at least 1.8 Ma during the early Pleistocene. These ages correspond to 3.6 to 4.7 Ma zircon fission-track ages reported from tephra deposits of the Tierra Negra region to the southwest of the Paipa-Iza volcanic complex in the Eastern Cordillera. A 4 Myr period of volcanic activity is longer than the previously documented 2.5 Ma to 1.9 Ma activity in the Paipa-Iza area. Therefore, our data show that the Paipa-Iza volcanic complex was active during the entire Pliocene phase of rapid surface uplift, when the Eastern Cordillera reached its present-day elevation. Unclear is if the magma chamber of the Paipa-Iza volcanic complex was passively uplifted with the rest of the Eastern Cordillera, or if magmatism contributed to surface uplift. Hydrothermal activity and steep thermal gradients in the study area today indicate that a magma chamber is still present at depth. In both the zircon fission-track and Usbnd Pb data of this study the recycling of zircon from underlying Mesozoic sedimentary rocks is evident in the wide age spectra. The fission-track data show that many recycled zircons were affected at least by partial annealing, but further research is needed for constraining the thermal impact of the Paipa-Iza volcanism on the Eastern Cordillera.

  5. A new colorful species of Pristimantis (Anura: Craugastoridae) from the eastern flank of the Cordillera Central in Colombia .

    PubMed

    Rivera-Prieto, Diego A; Rivera-Correa, Mauricio; Daza, Juan M

    2014-12-22

    We describe a new species of Pristimantis from the humid forests on the eastern flank of the northern Cordillera Central in Colombia (6º 23' 19.3554" N, 75º 1' 24.0594" W; ca. 1150 m.a.s.l.). Pristimantis jaguensis sp. nov. is characterized by an extraordinary variation in color and is readily distinguished from congeneric species by lacking nuptial pads, discoidal fold and conical calcar tubercles; flanks and belly white to cream without blotches as well as iris yellow ocher to copper with thick brown reticulation and cream sclera. Molecular phylogenetic analyses recovered the new species in a clade with species mostly distributed in Ecuador. Our finding suggests that new taxa can still be discovered in the Middle Magdalena River valley of Colombia despite the extensive sampling this region has received during the last decades. 

  6. A Middle Miocene (13.5-12 Ma) deformational event constrained by volcanism along the Puna-Eastern Cordillera border, NW Argentina

    NASA Astrophysics Data System (ADS)

    Aramayo, Alejandro; Guzmán, Silvina; Hongn, Fernando; del Papa, Cecilia; Montero-López, Carolina; Sudo, Masafumi

    2017-04-01

    The features of Middle Miocene deposits in the Puna-Eastern Cordillera transition (Valles Calchaquíes) indicate that Cenozoic deformation, sedimentation and volcanism follow a complex spatiotemporal relationship. The intense volcanic activity recorded in the eastern Puna border between 14 and 11.5 Ma coincides with the occurrence of one of the most important deformation events of the Neogene tectonic evolution in the region. Studies performed across the Puna-Eastern Cordillera transition show different relationships between volcanic deposits of ca. 13.5-12.1 Ma and the Oligocene-Miocene Angastaco Formation. In this paper we describe the ash-flow tuff deposits which are the first of this type found concordant in the sedimentary fill of Valles Calchaquíes. Several analyses performed on these pyroclastic deposits allow a correlation to be made with the Alto de Las Lagunas Ignimbrite (ca. 13.5 Ma) of the Pucarilla-Cerro Tipillas Volcanic Complex located in the Puna. Outcrops of the ca. 13.5 Ma pyroclastic deposits are recognised within the Puna and the Valle Calchaquí. However, in the southern prolongation of the Valle de Hualfín (Tiopampa-Pucarilla depression) that separates the Puna from the Valle Calchaquí at these latitudes, these deposits are partially eroded and buried, and thus their occurrence is recorded only by abundant volcanic clasts included in conglomerates of the Angastaco Formation. The sedimentation of the Angastaco Formation was aborted at ca. 12 Ma in the Tiopampa-Pucarilla depression by the Pucarilla Ignimbrite, which unconformably covers the synorogenic units. On the contrary, in the Valle Calchaquí the sedimentation of the Angastaco Formation continued until the Late Miocene. The different relationships between the Miocene Angastaco Formation and the ignimbrites with ages of ca. 13.5 and ca. 12 Ma reveal that in this short period ( 1.5 m.y.) a significant deformation event took place and resulted in marked palaeogeographic changes, as

  7. Testing the sensitivity of geomorphic indices in areas of low-rate active folding (eastern Betic Cordillera, Spain)

    NASA Astrophysics Data System (ADS)

    Pedrera, Antonio; Pérez-Peña, José Vicente; Galindo-Zaldívar, Jesús; Azañón, José Miguel; Azor, Antonio

    2009-04-01

    Active deformation structures have an incidence in topography that can be quantified by using geomorphic indices. Most of these indices have been checked in faulted regions with high-deformation rates. The application of several geomorphic indices (hypsometric curve analysis, normalized stream-length gradient, and valley width-to-valley height ratio) to the drainage network of the southern limb of the Sierra de Las Estancias antiform (Internal Zones, eastern Betic Cordillera), where low-rate active folding has been recognized, allows us to investigate the suitability of these indices to identify active structures in such a scenario. Hypsometric curves clearly identify regions with recent uplift and young topography, but they do not provide any constraint on the location of active folds. Local valley width-to-valley height index variations have been detected just coinciding whit the position of ENE-WSW active folds. Normalized stream-length gradient index serves to locate active folds in areas of hard rock substratum, but not in those areas with soft sediments (Neogene-Quaternary sedimentary basins). This is most likely due to the fact that in the basins erosion is much more intense than in the hard rock sectors. In view of these results, we consider that geomorphic indices constitute a valuable tool for identifying sectors affected by low-rate uplift related to active folding, with the best results obtained in hard rock areas.

  8. New Constraints on the Timing and Magnitude of Deformation and Basin Exhumation in the Eastern Cordillera of NW Argentina.

    NASA Astrophysics Data System (ADS)

    Trimble, J. D.; Carrapa, B.; Stockli, D. F.; Stutz, J.

    2008-12-01

    The Angastaco Basin is a ~20km wide and ~6km thick intramontane basin within the Eastern Cordillera (EC) of NW Argentina. The basin is bounded to the east and west by reverse faults that put basement rocks of the Paleozoic Puncoviscana and Cretaceous Santa Barbara Group on top of the Cenozoic sequence. Numerous faults and folds disrupt the basin internally. Some, if not most, of these structures seem to be the result of reactivation of previous normal faults related to the Salta Rift (Carrera et al. , 2006). Recent structural and thermochronological data from the EC of Argentina suggest tectonic deformation in the Eocene-Miocene (e.g., Coutand et al., 2006; Hogn et al., 2007). Data from the EC in Bolivia suggest that deformation ceased by ca. 10.7 Ma (McQuarrie et al., 2005). Therefore, different challenging questions remain open such as: (1) Are all the structures observed in the basin and along its margin a result of reactivation? (2) When was the timing and what was the magnitude of deformation within the basin and surrounding region? New detailed mapping and cross-sections in the Angastaco Basin reveal a number of faults and folds never before documented, including several km-scale west vergent folds interspersed with a complex arrangement of smaller, more angular, east-vergent faults and folds. Clear influence from both east and west-vergent deformation within the basin suggests interplay between the eastward propagation of EC related structures and westward reactivation of Santa Barbara System structures. A lack of structural continuity across the roughly E-W trending portions of Rio Calchaqui suggests that the river follows one or more unexposed strike- slip faults as it cuts across the Tertiary section from W to E. Minor offsets and lack of lateral continuity suggest that these faults are likely tear-faults coeval with deformation in the basin, although they may have been active during multiple pulses of tectonism. With an east-west trend, these structures

  9. Are scale detrital zircon age spectra from modern sands representative of their catchment sources? : An empirical test from the Eastern Cordillera of Colombia

    NASA Astrophysics Data System (ADS)

    Knowles, J.; Bande, A.; Ramirez, J. C.; Mora, A.; Horton, B. K.; Nie, J.; Saylor, J.

    2010-12-01

    Despite potential pitfalls, detrital zircon U-Pb geochronology remains a widely used method to determine provenance and age, and conduct tectonic reconstructions. Potential problems include whether the zircon populations from sandstone samples accurately capture both the presence and relative abundances of zircon populations within the catchment. Sand and sandstone samples were collected and analyzed from two rivers, the Rio Cravo Sur and Rio Cusiana, and the various Cretaceous-Cenozoic formations present in their respective catchments (areas= XX, YY km2, respectively). Using digital watershed delineation, mapped surface geology, the areal extent of each formation, and the measured detrital zircon U-Pb age spectrum for each formation, model zircon populations were generated to represent each catchment. We compared this to the measured river data using both qualitative and statistical analysis methods in order to determine whether sampled formations yield representative populations. Statistical tests including the coefficient of determination (R-squared), overlap-similarity comparison, and the Chi-square test support the conclusion that populations reflect their contributors. Modern river sediments sampled in the Eastern Cordillera of the Colombian Andes reveal U-Pb age spectra that are representative of the contributing formations. Significantly, not only do river samples accurately reflect the presence of zircon populations, they also closely reflect the relative abundance of those populations. We attribute deviations between model and measured spectra to differences in zircon concentration, or erosion.

  10. Provenance through the limit: integrated provenance from the Devonian sedimentary and basement rocks from the northern segment of the Eastern Cordillera of the Colombian Andes

    NASA Astrophysics Data System (ADS)

    Cardona, Agustin; Valencia, Victor; Lotero, Andrea; Villafañez, Yohana; Augustsson, Carita; Bayona, German; Ibañez, Mauricio

    2013-04-01

    The provenance record of sedimentary rocks is sometimes the only available archive of the geological evolution in continuously active continental margins where continuous exhumation, erosion and along strike fragmentation of continental margins destroy geological evidences. New integrated provenance constraints from segmented exposures of Devonian rocks of the northern segment of the Eastern Cordillera of Colombia are used to reconstruct overimposed Paleozoic, Mesozoic and Cenozoic paleogeographic scenarios of the northern Andes. Sandstones from deltaic to platform environments are characterized by very high quartz contents, stable to ultrastable heavy minerals and mostly angular fragments. U-Pb detrital zircon geochronology reveals prominent Silurian to Ordovician and Mesoproterozoic (Grenvillian) age populations with minor Devonian zircons. Tourmaline geochemistry and detrital quarz characterization suggest prominent low grade metamorphic sources. These provenance fingerprints can be related to the erosion of the older metasedimentary basement exposed in the same region and record the transition from a terrane collisional event to the formation of a new subduction zone before the final Late Paleozoic events that end in the agglutination of Pangea. The U-Pb detrital record of the Devonian and basement rocks of the Eastern Cordillera are also comparable with Early to Middle Paleozic Paleozoic rocks form the Northern segment of the eastern Peruvian Andes re-inforcing the view of along strike terrane thousand of kilometer transport along the Mesozoic proto-Andean margin. Petrographic and heavy mineral petrofacies and stratigraphic correlation between Devonian localities are also used as piercing points to document Cenozoic ten of kilometers strike slip displacements along the northern termination of the Eastern Cordillera.

  11. Quantitative subsidence-uplift analysis of the Bajo Segura Basin (eastern Betic Cordillera, Spain): tectonic control on the stratigraphic architecture

    NASA Astrophysics Data System (ADS)

    Soria, J. M.; Alfaro, P.; Fernández, J.; Viseras, C.

    2001-04-01

    The Bajo Segura Basin is located in the eastern Betic Cordillera, at present connected with the Mediterranean Sea to the east. It has a complete stratigraphic record from the Tortonian to the Quaternary, which has been separated into six units bounded by unconformities. This paper is concerned with the northern edge of the basin, controlled by a major strike-slip fault (the Crevillente Fault Zone, CFZ), where the most complete stratigraphic successions are found. The results obtained (summarised below) are based on an integrated analysis of the sedimentary evolution and the subsidence-uplift movements. Unit I (Early Tortonian) is transgressive on the basin basement and is represented by ramp-type platform facies, organised in a shallowing-upward sequence related to tectonic uplift during the first stages of movement along the CFZ. Unit II (lower Late Tortonian) consists of shallow platform facies at bottom and pelagic basin facies at top, forming a deepening-upward sequence associated with tectonic subsidence due to sinistral motion along the CFZ. Unit III (middle Late Tortonian) is made up of exotic turbiditic facies related to a stage of uplift and erosion of the southern edge of the basin. Unit IV (upper Late Tortonian) consists of pelagic basin facies at bottom and shallow platform facies at top, defining a shallowing-upward sequence related to tectonic uplift during continued sinistral movement on the basin-bounding fault. Units V (latest Tortonian-Messinian) and VI (Pliocene-Pleistocene p.p.) consist of shallowing-upward sequences deposited during folding and uplift of the northern margin of the basin. No definitive evidence of any major eustatic sea-level fall, associated with the 'Messinian salinity crisis', has been recorded in the stratigraphic sections studied.

  12. Antisana volcano: A representative andesitic volcano of the eastern cordillera of Ecuador: Petrography, chemistry, tephra and glacial stratigraphy

    NASA Astrophysics Data System (ADS)

    Hall, Minard L.; Mothes, Patricia A.; Samaniego, Pablo; Militzer, Annemarie; Beate, Bernardo; Ramón, Patricio; Robin, Claude

    2017-01-01

    Antisana volcano is representative of many active andesitic strato-volcanoes of Pleistocene age in Ecuador's Eastern Cordillera. This study represents the first modern geological and volcanological investigation of Antisana since the late 1890's; it also summarizes the present geochemical understanding of its genesis. The volcano's development includes the formation and destruction of two older edifices (Antisana I and II) during some 400 + ka. Antisana II suffered a sector collapse about 15,000 years ago which was followed by the birth and growth of Antisana III. During its short life Antisana III has generated ≥50 eruptions of small to medium intensity, often associated with andesitic to dacitic lava flows and tephra, as well as with late Pleistocene and Holocene glacial advances. Throughout its long history Antisana's lavas have been characterized by a persistent mineral assemblage, consisting of 30-40 vol% phenocrysts of plagioclase, both clino- and orthopyroxene, and Fe-Ti oxides, with rare occurrences of olivine or amphibole, frequently in a microcrystalline to glassy matrix. This uniformity occurs despite the magma's progressive chemical evolution over ≥400 ka from early basic andesites (53-58 wt% SiO2) to intermediate and Si-rich andesites (58-62% SiO2), and recently to dacites (63-67% SiO2). Chemical diagrams suggest that crystal fractionation was the most likely magmatic process of evolution. The exception to this slowly evolving history was the short-lived emission at ∼210 ka of the Cuyuja lavas from Antisana II that generated a 73 km long andesitic lava flow. Contrasting with Antisana's general magmatic trend, Cuyuja lava (∼11 km3) is a high-Mg andesite with unusually high concentrations of incompatible elements. Antisana developed within the Chacana caldera complex, a large active siliceous center that began ∼3 Ma ago, however its lavas are chemically distinct from coeval lavas of Chacana.

  13. The isolation of the temperature effect on branched GDGT distribution in an elevation transect of the Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Anderson, V. J.; Shanahan, T. M.; Saylor, J.; Horton, B. K.

    2012-12-01

    Recently, the distribution of branched GDGT's (glycerol dialkyl glycerol tetraethers) has been proposed as a proxy for temperature and pH in soils via the MBT/CBT index, and has been used to reconstruct past temperature variations in a number of settings ranging from marine sediments to loess deposits and paleosols. However, empirical calibrations of the MBT/CBT index against temperature show significant scatter, leading to uncertainties as large as ±2 degrees C . In this study we seek to add to and improve upon the existing soil calibration using a new set of samples spanning a large elevation (and temperature) gradient in the Eastern Cordillera of Colombia. At each site we buried temperature loggers to constrain the diurnal and seasonal temperature experienced by each soil sample. Located only 5 degrees north of the equator, our sites experience a very small seasonal temperature variation - most sites display an annual range of less than 4 degrees C. In addition, the pH of all of the soils is almost invariant across the transect, with the vast majority of samples having pH's between 4 and 5. This dataset represents a "best-case" scenario - small variations in seasonal temperature, pH, and well-constrained instrumental data - which allow us to examine the brGDGT-temperature relationship in the absence of major confounding factors such as seasonality and soil chemistry. Interestingly, the relationship between temperature and the MBT/CBT index is not improved using this dataset, suggesting that these factors are not the cause of the anomalous scatter in the calibration dataset. However, we find that using other parameterizations for the regression equation instead of the MBT and CBT indices, the errors in our temperature estimates are significantly reduced.

  14. Controls on the isotopic composition of surface water and precipitation in the Northern Andes, Colombian Eastern Cordillera

    NASA Astrophysics Data System (ADS)

    Saylor, Joel E.; Mora, Andrés; Horton, Brian K.; Nie, Junsheng

    2009-12-01

    Empirical datasets provide the constraints on the variability and causes of variability in stable isotope compositions (δD or δ 18O) of surface water and precipitation that are essential not only for models of modern and past climate but also for investigations of paleoelevation. This study presents stable isotope data for 76 samples from four elevation transects and three IAEA GNIP stations in the Eastern Cordillera of Colombia and the northern Andean foreland. These data are largely consistent with theories of stable isotope variability developed based on a global dataset. On a monthly basis, the precipitation-amount effect exerts the dominant control on δD p and δ 18O p values at the IAEA GNIP stations. At the Bogotá station (2547 m), the δD p and δ 18O p values vary seasonally, with isotopic minima correlating with maxima in precipitation-amount. Although surface water samples from Eastern Cordilleran streams and rivers fall on the Global Meteoric Water Line, samples from three of four lakes (2842-3459 m) have evaporatively elevated δD sw and δ 18O sw values. The IAEA GNIP station data averaged over multiple years, combined with stream and river water data, define vertical lapse rates of -1.8‰ km -1 for Δδ 18O and -14.6‰ km -1 for ΔδD, and are a close fit to a common thermodynamically based Rayleigh distillation model. Elevation uncertainties for these relationships are also evaluated. Comparison of this Colombian dataset with the elevation uncertainties generated by the thermodynamically based model shows that the model underestimates uncertainty at high Δδ 18O and ΔδD values while overestimating it for low Δδ 18O and ΔδD values. This study presents an independent, empirical assessment of stable isotope-based elevation uncertainties for the northern Andes based on a dataset of sufficient size to ensure statistical integrity. These vertical lapse rates and associated uncertainties form the basis for stable isotope paleoelevation studies

  15. Biostratigraphy of the Santa Rosita Formation (Furongian-Tremadocian) in its type area, Eastern Cordillera, NW Argentina

    NASA Astrophysics Data System (ADS)

    Voldman, G. G.; Albanesi, G. L.; Ortega, G.; Monaldi, C. R.; Zeballo, F. J.; Giuliano, M. E.

    2012-04-01

    The Cambrian - Lower Ordovician stratigraphic units from the Eastern Cordillera were originally defined in the Santa Victoria Range, Salta Province, NW Argentina. At the southern margin of the Santa Victoria River, near the homonymous locality, the Santa Rosita Formation is conformably overlain by the Acoite Formation. These stratigraphic units are dated by means of conodont, graptolite and trilobite biostratigraphy in the type sections. The upper interval (ca. 700 m) of the Santa Rosita Formation consists of sandstones interbedded with purplish to grayish shales and occasional coquinas, which were sampled for microfossils. 15 carbonate samples (35 kg) were processed following standard laboratory techniques for conodont recovery. A number of species from the genera Acanthodus, Acodus, Decoriconus, Drepanodus, Drepanoistodus, Iapetognathus, Kallidontus, Paltodus, Utahconus, Teridontus and the protoconodont Phakelodus were recovered from 5 productive samples. The conodont elements exhibit a CAI 3 and correspond to the Paltodus deltifer deltifer Subzone of the P. deltifer Zone (middle Tremadocian, Tr2). Pelites of the Acoite Formation, at 300 m from its base, bear Araneograptus murrayi and Thysanopyge sp., whose ranges span the Tremadocian - Floian boundary. Conodonts and graptolites were also yielded by outcrops of the Santa Rosita Formation at the Nazareno area, 30 km to the south of the Santa Victoria type locality. The conodont associations were recorded from calcareous levels of the Alfarcito and Rupasca members, including Drepanodus arcuatus, Drepanoistodus chucaleznensis, Teridontus gallicus, Utahconus humahuacensis, Acanthodus sp. and Utahconus sp. They also integrate the eponymous subspecies from the Paltodus deltifer pristinus and P. d. deltifer subzones of the P. deltifer Zone (middle Tremadocian, Tr2). The Santa Rosita Formation correlates with a thick heterolithic succession at the Zenta Range, 120 km to the southwest of the Santa Victoria type area. This

  16. Transverse zones controlling the structural evolution of the Zipaquira Anticline (Eastern Cordillera, Colombia): Regional implications

    NASA Astrophysics Data System (ADS)

    García, Helbert; Jiménez, Giovanny

    2016-08-01

    We report paleomagnetic, magnetic fabric and structural results from 21 sites collected in Cretaceous marine mudstones and Paleogene continental sandstones from the limbs, hinge and transverse zones of the Zipaquira Anticline (ZA). The ZA is an asymmetrical fold with one limb completely overturned by processes like gravity and salt tectonics, and marked by several axis curvatures. The ZA is controlled by at least two (2) transverse zones known as the Neusa and Zipaquira Transverse Zones (NTZ and ZTZ, respectively). Magnetic mineralogy methods were applied at different sites and the main carriers of the magnetic properties are paramagnetic components with some sites being controlled by hematite and magnetite. Magnetic fabric analysis shows rigid-body rotation for the back-limb in the ZA, while the forelimb is subjected to internal deformation. Structural and paleomagnetic data shows the influence of the NTZ and ZTZ in the evolution of the different structures like the ZA and the Zipaquira, Carupa, Rio Guandoque, Las Margaritas and Neusa faults, controlling several factors as vergence, extension, fold axis curvature and stratigraphic detatchment. Clockwise rotations unraveled a block segmentation following a discontinuos model caused by transverse zones and one site reported a counter clockwise rotation associated with a left-lateral strike slip component for transverse faults (e.g. the Neusa Fault). We propose that diverse transverse zones have been active since Paleogene times, playing an important role in the tectonic evolution of the Cundinamarca sub-basin and controlling the structural evolution of folds and faults with block segmentation and rotations.

  17. Provenance of the late Proterozoic to early Cambrian metaclastic sediments of the Sierra de San Luis (Eastern Sierras Pampeanas) and Cordillera Oriental, Argentina

    NASA Astrophysics Data System (ADS)

    Drobe, Malte; López de Luchi, Mónica G.; Steenken, André; Frei, Robert; Naumann, Rudolf; Siegesmund, Siegfried; Wemmer, Klaus

    2009-10-01

    Provenance studies have been performed utilising major and trace elements, Nd systematics, whole rock Pb-Pb isotopes and zircon U/Pb SHRIMP data on metasedimentary rocks of the Sierra de San Luis (Nogolí Metamorphic Complex, Pringles Metamorphic Complex, Conlara Metamorphic Complex and San Luis Formation) and the Puncoviscana Formation of the Cordillera Oriental. The goal was the characterisation of the different domains in the study area and to give insights to the location of the source rocks. An active continental margin setting with typical composition of the upper continental crust is depicted for all the complexes using major and trace elements. The Pringles Metamorphic Complex shows indications for crustal recycling, pointing to a bimodal provenance. Major volcanic input has to be rejected due to Th/Sc, Y/Ni and Cr/V ratios for all units. The ɛNd (540 Ma) data is lower for the San Luis Formation and higher for the Conlara Metamorphic Complex, as compared to the other units, in which a good consistency is given. This is similar to the TDM ages, where the metapsammitic samples of the San Luis Formation are slightly older. The spread of data is largest for the Pringles Metamorphic Complex, again implying two different sources. The whole rock 207Pb/ 206Pb isotopic data lies in between the South American and African sources, excluding Laurentian provenances. The whole rock Pb-Pb data is almost indistinguishable in the different investigated domains. Only the PMC shows slightly elevated 208Pb/ 204Pb values. Possible source rocks for the different domains could be the Quebrada Choja in the Central Arequipa-Antofalla domain, the Southern domain of the Arequipa-Antofalla basement, the Brazilian shield or southern Africa. Zircon SHRIMP data point to a connection between the Puncoviscana Formation and the Conlara Metamorphic Complex. Two maxima around 600 Ma and around 1000 Ma have been determined. The Nogolí Metamorphic Complex and the Pringles Metamorphic Complex

  18. The Eastern delta-fan deposits on the Granada Basin as tectonic indicators of the Sierra Nevada uplift (Betic Cordillera, South Spain)

    NASA Astrophysics Data System (ADS)

    Roldán, Francisco Javier; Azañon, Jose Miguel; Mateos, Rosa Maria

    2014-05-01

    A geological mapping in detail of the Eastern sector of the Granada Basin (South Spain) reveals two different groups of Gilbert delta-fans related to the Sierra Nevada uplift. The first group, in the southern part and with a surface of 6 km2, has three major coarsening-upward sequences. They are composed of very coarse deposits, those of conglomerates, sands and silts. Progradational strata units to the basin have been observed. The dominantly fluvial facies association has locally developed shallow marine foreset deposits (partially with reef colonization) as well as topset red soils (Dabrio, et al., 1978; Braga et a., 1990; García-García, et al., 1999) . All the sequences are discordant over marine facies (calcarenites) dated over 8,26 Ma (Late Tortonian). The second group, in the northern part and with an extension of 12 km2, has similar characteristics, but some of the boulders have ostreids and lamellibranchs species which reveal their former position in a previous marine environment. The Sierra Nevada uplift caused the remobilization of these boulders, being transported by debris-flow inside the delta-fan bodies (García-García, et al., 2006). The dating of ostreids shells with Sr techniques reveals ages over 7,13, 6,61 and 5,45 Ma, from the lower to the upper delta-fan deposits, which are related to the three main sequences observed and with three major tectonic pulses during the Late Miocene. These interpretations are in agreement with apatite fision-track studies carried out in some boulders of these coarse delta-fan deposits (Clark and Dempster, 2013). They reveal a detailed record of Neogene denudation from the Sierra Nevada basement and with uplift periods between 5,45Ma- 2 Ma. The latest pulses affected the delta-fan sediments given rise to new fan systems in the Granada Basin (Alhambra Formation). The thoroughly study of the Miocene delta-fan sediments allows us to conclude that they were related to a sin-sedimentary tectonic activity linked to the

  19. A new tectonic model for the development of the Eastern Cordillera, Altiplano, and Subandean zones, Bolivian Central Andes, 20[degrees]S latitude

    SciTech Connect

    Gubbels, T.L.; Isacks, B.L. ); Koch, R.W. )

    1993-02-01

    Construction of a regional transect across the central Andes at 20[degrees]S sheds new light on the relationship between the Altiplano, Eastern Cordillera (EC), and Subandean zones and allows us to refine the two-stage model of Isacks (1988) for the growth of the Central Andes. This new model is based on examination of the regional geology and geophysics, coupled with field investigations, satellite image analysis, and new Ar-Ar geochronology. In this model, widespread Oligocene to mid-Miocene compressional deformation in the Altiplano and EC was followed in the late-Miocene and Pliocene by thrusting localized east of the EC within the Subandean fold-thrust belt. During the first stage of deformation, the Altiplano basin underwent important subsidence and internal deformation. The EC was both deformed internally and thrust westwards over the Altiplano basin, while the present Subandean zone was the site of an early, broad foreland basin which received material eroded from the EC. During the second stage, beginning at [approximately]10 ma, deformation terminated within the EC and became concentrated within the fold-thrust belt in response to large scale overthrusting of the EC above the Brazilian shield; this resulted in major thrusting along the Cabalgamiento Frontal Principal (CFP), which soles into the master Subandean decollement, and [approximately]100 km of telescoping within the early, broad foreland basin. In the EC, this second stage is marked by the elaboration of a regionally extensive erosion surface, ponding of gravels in shallow basins, and the emplacement of giant ignimbrite sheets. The Eastern Cordillera can thus be thought of as a crustal-scale wedge which has been extruded upward and outward on alternate sides during successive stages of late Cenozoic deformation. This motion has served to drive subsidence in both the Altiplano and Subandean foreland basins, as well as shortening in the fold-thrust belt.

  20. Studies in Neotropical Paleobotany. XV. A Mio-Pliocene palynoflora from the Eastern Cordillera, Bolivia: implications for the uplift history of the Central Andes.

    PubMed

    Graham, A; Gregory-Wodzicki, K M; Wright, K L

    2001-09-01

    An assemblage of 33 fossil pollen and spores, recovered from the 3600-m high Pislepampa locality of E. W. Berry, Eastern Cordillera, Bolivia, adds considerably to our knowledge of three aspects of the region in late Neogene time: (1) the paleovegetation, (2) the paleoclimate, and (3) the paleoelevation of the Central Andes. The plant microfossils recognized are Isoetes, Lycopodium (three types), Cnemidaria, Cyathea (three types), Grammitis, Hymenophyllum, Pteris, trilete fern spores (two types), Danaea, monolete fern spores (four types), Podocarpus, Gramineae, Palmae, Ilex, cf. Oreopanax, Cavanillesia, cf. Pereskia, Compositae (three types), Ericaceae, Tetrorchidium, and unknowns (three types). The diversity of the Compositae suggest that this flora has a maximum age around the Miocene-Pliocene boundary, that is, 6-7 million years. All members of the paleocommunity presently grow in the bosque montano húmedo (cloud forest) along the eastern slope of the Central Andes of Bolivia, which occurs between MATs (mean annual temperatures) of ∼10° and 20°C. The Pislepampa flora probably represents the lower limits of this forest because the fossil leaves collected by Berry from the same locality all have entire margins, suggesting that the flora grew near the cloud forest-tropical forest transition. Presently, the lower limit of the cloud forest forest has MATs of ∼20°C, a mean annual precipitation between 1000 and 1500 mm, and that part containing most of the identified genera of fossil pollen is found at elevations ∼1200-1400 m. These conditions are thus inferred for the Pislepampa flora; however, because of the uncertainty of the magnitude of global climate change and of possible changes in the ecological range of plant genera, we estimate an error of at least ±1000 m for the paleoelevation estimate. When the total uplift is corrected for probable amounts of erosionally driven isostatic rebound, the paleoelevation estimate suggests that from one-third to one

  1. "High resolution seismic imaging of an active fault in the eastern Guadalquivir Basin (Betic Cordillera, Southern Spain)"

    NASA Astrophysics Data System (ADS)

    Serrano, Inmaculada; Torcal, Federico; Martín, José Benito

    2015-10-01

    We calculated the high resolution seismic velocity, Poisson's ratio, crack density and saturation ratio structures in and around the source areas of the Torreperogil seismic series (October 2012-April 2013). This seismic series, characterized by a large number of low magnitude (below Mw 3.7 or Md 3.9) and very shallow microearthquakes, took place in the Guadalquivir Basin, a large flexural foreland basin with a linear ENE-WSW trending bounded to the north by the Iberian Massif and to the south by the Betic Cordillera and filled from a middle Miocene to Plio-Quaternary sedimentary sequence. In the upper layers of the crust, strong low-velocity anomalies are extensively distributed under the central zone, which together with high Poisson's ratio and crack density values may correspond to rocks which are less likely to fracture, perhaps due to the accumulation of tectonic and seismic stress. 93% of the earthquakes occurred at depths of up to 8 km, which could indicate that the base of the seismogenic zone lies at this depth. The seismic series was concentrated in layers of strong structural heterogeneities (in the boundary area between low and high anomalies), which were likely to generate earthquakes due to differential strain accumulation beneath the region. The high velocity areas are also considered to be strong yet brittle parts of the fault zone, which may generate earthquakes (at depths of between 5 km and 9 km). By contrast, low velocity areas are less prone to fracture, allowing seismic slippage to take place (from 2 to 4 km depth). The best estimate of the depth of the main shock (mbLg 3.9) is 7.6 km, which could tend to nucleate at the base of the seismogenic zone, at the "fault end" on the boundary between a low velocity zone to the east and a high velocity zone to the west, indicating the fault plane which separates both areas laterally. Assuming that this seismic contrast is one of the main Torreperogil faults it could imply that stress has accumulated

  2. Distribution and characteristics of metamorphic belts in the south- eastern Alaska part of the North American Cordillera

    USGS Publications Warehouse

    Brew, D.A.; Himmelberg, G.R.; Loney, R.A.; Ford, A.B.

    1992-01-01

    The Cordilleran orogen in south-eastern Alaska includes 14 distinct metamorphic belts that make up three major metamorphic complexes, from east to west: the Coast plutonic-metamorphic complex; the Glacier Bay-Chichagof plutonic-metamorphic complex; and the Chugach plutonic-metamorphic complex. Each of these complexes is related to a major subduction event. The metamorphic history of the Coast complex is lengthy and is related to the Late Cretaceous collision of the Alexander and Wrangellia terranes and the Gravina overlap assemblage to the west against the Stikine terrane to the east. The metamorphic history of the Glacier Bay-Chichagof complex is relatively simple and is related to the roots of a Late Jurassic to late Early Cretaceous island arc. The metamorphic history of the Chugach is complicated and developed during and after the Late Cretaceous collision of the Chugach terrane with the Wrangellia and Alexander terranes. -from Authors

  3. Mississippian through Permian orogenesis in eastern Nevada: Post-Antler, pre-Sonoma tectonics of the western cordillera

    SciTech Connect

    Trexler, J.; Cashman, P. ); Snyder, W.; Spinoza, C.; Gallegos, D. )

    1991-02-01

    Mississippian through Permian strata in eastern Nevada document a series of tectonic events that are either generally unrecognized, or assigned to the Antler or Sonoma orogenies. Some of these events were local and some were regional in scale; none fit either the Antler or Sonoma events as normally defined: Antler orogeny (ends Late Devonian or earliest Mississippian) - emplacement of accretionary wedge on the passive margin; Wendover phase (Early Mississippian) - regional uplift, erosion; Diamond Range phase (Middle Mississippian) - folding, uplift, and erosion; Humboldt orogeny (Pennsylvanian) - uplift, tilting and erosion; Dry Mountain event (Late Pennsylvanian-Early Permian) - uplift, tilting and erosion, and basin segmentation; Sonoma orogeny (Permian-Triassic) - allochthon emplacement. Each event is documented by deformation and erosional truncation of older strata, and by clastic sequences that fill newly formed basins. These tectonic events have mostly escaped notice until now for two reasons: (1) established cratonal stratigraphy, when applied to highly variable craton-edge sequences, tends to obscure important local perturbations, and (2) the assumption of only two Paleozoic orogenies leaves little room for more complexity, and inevitably leads to unresolvable arguments about timing and style. Little-used older terminology (e.g., Wendover phase') is available to describe these events in some cases; refinement or abandonment of existing terminology may be necessary in others. Careful, objective stratigraphic studies will result in a more accurate, and complex regional history.

  4. Valley fill in the Andean Eastern Cordillera: a response to transient incision of the Río Iruya, NW Argentina

    NASA Astrophysics Data System (ADS)

    Bovay, C.; Harbor, D. J.; Rahl, J. M.; Staffo, K.; Galli, C.

    2010-12-01

    Headwater valley fill in the Río Iruya chronicles a complex record of deposition and incision at the eastern flank of the Andes. Other intramontane valley fills in NW Argentina have been interpreted to record important dynamics of climate, tectonics, and hillslope failure; specific mechanisms of aggradation include Late Cenozoic climate change, rock uplift and defeat of the channel network, and landslide- or tributary-induced damming. The valley fill is dominated by a horizontally bedded, muddy, coarse-grained, angular conglomerate with few channel cuts, interpreted as gravel-bed, braided river deposits with significant tributary fan volume. The fill contains almost no fine-grained, laminated, or lacustrine deposits, and a general lack of soil horizons in the up to 300 m-thick fill likely indicates continuous deposition. The geometry of preexisting and modern channel network is largely similar. Downstream, the river is actively incising bedrock and has removed most of the fill. In contrast, the headwater reaches contain well-preserved and abundant fill terraces and the river is less commonly eroding bedrock in the valley bottom. The fill becomes mostly eroded downstream of several major tributaries that provided a significant volume of sediment. Ongoing and alternating aggradation and incision are evident in both inset terraces and the modern channel. We consider the applicability of previously established interpretations of valley fill generation. In addition, we evaluate the potential for complex response to base level lowering to cause the aggradation and incision in the Río Iruya. Hypothesized drainage basin reorganization and capture would produce a base level drop, resulting in enormous sediment flux. To estimate the maximum possible erosion rate in the headwaters region, we studied the valley fill sediments using differential GPS. The contact between the fill and the bedrock along the channel was measured to determine the total volume of the fill

  5. Strong lateral strength contrasts in the mantle lithosphere of continents: A case study from the hot SW Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Hardebol, N. J.; Beekman, F.; Cloetingh, S. A. P. L.

    2013-08-01

    This study aims at quantifying the 3-D variability in lithosphere strength of the south-eastern Canadian Cordillera and adjacent craton to the east. Strength is calculated in a forward manner, starting from rheological laws of brittle and ductile deformation. The work flow calculates a temperature model based on a multi-layer compositional model and subsequently estimates the strength distribution from both the compositional and temperature models. The temperature modeling involves numerical inversion and cubic spline algorithms which enable to impose boundary conditions that account better for strong lateral variations in lithosphere thickness and lateral heat flow. This addresses the lithosphere structure between the Canadian Cordillera and craton. The Canadian Cordillera is marked by a hot and thin lithosphere of ~ 60 km thickness that stands in contrast to a cold and thick craton of ~ 170 km thickness to the east, which consequently results in pronounced changes in bulk lithosphere strength. The high surface heat flow of the Cordillera interior and its contrast with the Foreland Basin can be reproduced by temperature models that combine elevated mantle heat flow due to the thin lithosphere and higher crustal heat production from magmatic intrusions. A series of rheological models, which examines the role of different temperature input models, composition and strain rate, shows that the first-order strength pattern is persistent. For the hot Canadian Cordillera, strength resides for > 80% in the upper crust and with integrated lithosphere strength of 2.0-3.5ṡ106 MPaṡm. For the cold craton, the upper mantle provides > 75% of the integrated strength with values of 4.0-8.0ṡ106 MPaṡm for the crust and 20-65ṡ106 MPaṡm for the lithosphere. Effective elastic thickness is estimated between 5 and 15 km for the Cordillera and 40-80 km for the craton. This illustrates the Cordillera to craton transition as a prominent rheological feature for upper mantle flow

  6. EAST END FROM MID SPAN OF EASTERN SPAN (THREE DIFFERENT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    EAST END FROM MID SPAN OF EASTERN SPAN (THREE DIFFERENT TRUSSES, EAST SOUTHEAST 110 DEGREES) - Honey Run Bridge, Spanning Butte Creek, bypassed section of Honey Run Road (originally Carr Hill Road), Paradise, Butte County, CA

  7. Multi-stage evolution of the lithospheric mantle beneath the westernmost Mediterranean: Geochemical constraints from peridotite xenoliths in the eastern Betic Cordillera (SE Spain)

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

    Spinel (± plagioclase) peridotite xenoliths from the Tallante and Los Perez volcanic centres in the eastern Betics (SE Spain) range from depleted (clinopyroxene-poor) harzburgites to fertile (clinopyroxene-rich) lherzolites and orthopyroxene-free wehrlites. Significantly, only one harzburgite, which is depleted in heavy rare earth elements (HREE), retains the imprint of ca. 20% ancient melting of an original garnet lherzolite source. In contrast, REE abundances of other harzburgites and lherzolites from the eastern Betics have been increased by melt-rock reaction. The whole-rock and mineral compositions of these mantle rocks are largely controlled by three types of modal metasomatism: 1) common clinopyroxene-orthopyroxene addition and olivine consumption which increased FeOt, SiO2 and Al2O3, and decreased MgO compared to the refractory melting products; 2) subordinate orthopyroxene dissolution and precipitation of clinopyroxene and olivine, which led to higher FeOt and MgO and lower SiO2 than in common (orthopyroxene-rich) lherzolites; and 3) rare orthopyroxene consumption and olivine addition that caused higher FeOt and lower SiO2 compared to the original melting residues. These mineral modal and major element variations have been produced mostly by interactions with relatively FeOt-rich/SiO2-poor melts, likely derived from a peridotite-pyroxenite lithospheric mantle with a highly heterogeneous isotopic composition. Melting of the lithospheric mantle in the western Mediterranean was triggered by upwelling of the asthenosphere induced by back-arc extension in the Late Oligocene-Early Miocene. Trapping of small fractions of exotic melts in whole-rocks - likely the parental magmas of Miocene back-arc dykes that intruded the Betic crust - caused local disequilibrium between the trace element signatures and Pb isotopic compositions of clinopyroxene and whole-rock. Subsequent interaction with SiO2-undersaturated magmas, similar to the parental melts of the Pliocene

  8. Geochronology of Tropical Alpine Glaciations From the Cordillera Huayhuash, Peru

    NASA Astrophysics Data System (ADS)

    Hall, S. R.; Farber, D. L.; Rodbell, D. T.; Finkel, R. C.; Ramage, J. M.; Smith, J. A.; Mark, B. G.; Seltzer, G. O.

    2004-12-01

    The Cordillera Huayhuash of the Central Peruvian Andes (10.3° S, 76.9° W) is an ideal range to study regional climate signals and variations in paleo-ice volumes. Located between the Cordillera Blanca to the north and the Junin region to the south, the range trends nearly north-south with modern glaciers confined to the high peaks (>4800 m). Cross-cutting relationships, geomorphology, and correlation with surface exposure dated moraines in the nearby Cordillera Blanca suggest the region preserves a rich record of tropical glaciation. In order to determine the glacial chronology we mapped and dated glacial features of the Jahuacocha valley (which drains the western side of the range) and two eastern drainages, the Mitococha valley, and the Carhuacocha valley. At each locality we used ASTER data, aerial photographs, and GPS to map glacial features both within main valleys and tributaries. We sampled quartz-bearing erratics on moraine crests as well as ice-polished bedrock surfaces for exposure age dating using in situ produced cosmogenic 10Be and 26Al. In the Jahuacocha valley, the greatest ice extent reached an elevation of ˜4090m and moraine crest boulders yield and age of ˜11.2 ±0.6 ka suggesting a significant late Glacial ice advance or stillstand. A younger cluster of moraines exists ˜1 km up-valley at an elevation of ˜4100m. These moraines, dated at ˜8.0 ±1.0 ka, suggest an early Holocene advance. In the Mitococha valley, a young moraine and polished bedrock dated at ˜0.2 ka and ˜11.4 ±0.4 ka respectively span the late Glacial through recent. The late Glacial features of this eastern drainage occur at an elevation of ˜4100m while the recent events occur at an elevation of ˜4380m. Our preliminary results suggest that all three valleys experienced a very similar glacial history with minor differences likely due to the variations in valley morphology. Comparing the chronology of glaciation in the Cordillaera Huayhuash with that in regions to the

  9. Geochronology of Quaternary glaciations from the tropical Cordillera Huayhuash, Peru

    NASA Astrophysics Data System (ADS)

    Hall, Sarah R.; Farber, Daniel L.; Ramage, Joan M.; Rodbell, Donald T.; Finkel, Robert C.; Smith, Jacqueline A.; Mark, Bryan G.; Kassel, Christopher

    2009-12-01

    The Cordillera Huayhuash in the central Peruvian Andes (10.3°S, 76.9°W) is an ideal mountain range in which to study regional climate through variations in paleoglacier extents. The range trends nearly north-south with modern glaciers confined to peaks >4800 m a.s.l. Geomorphology and geochronology in the nearby Cordillera Blanca and Junin Plain reveal that the Peruvian Andes preserve a detailed record of tropical glaciation. Here, we use ASTER imagery, aerial photographs, and GPS to map and date glacial features in both the western and eastern drainages of the Cordillera Huayhuash. We have used in situ produced cosmogenic 10Be concentrations in quartz bearing erratics on moraine crests and ice-polished bedrock surfaces to develop an exposure age chronology for Pleistocene glaciation within the range. We have also collected sediment cores from moraine-dammed lakes and bogs to provide limiting 14C ages for glacial deposits. In contrast to the ranges to the north and south, most glacial features within the Cordillera Huayhuash are Lateglacial in age, however we have identified features with ages that span ˜0.2 to ˜38 ka with moraine sets marking the onset of glacier retreat at ˜0.3 ka, ˜9-10 ka, ˜13-14 ka, ˜20-22 ka, and >26 ka. The range displays a pronounced east-west variation in maximum down-valley distance from the headwall of moraine crests with considerably longer paleoglaciers in the eastern drainages. Importantly, Lateglacial paleoglaciers reached a terminal elevation of ˜4000 m a.s.l. on both sides of the Cordillera Huayhuash; suggesting that temperature may have been a dominant factor in controlling the maximum glacier extent. We suggest that valley morphology, specifically valley slope, strongly influences down-valley distance to the maximum glacier extent and potential for moraine preservation. While regionally there is an extensive record of older (>50 ka) advances to the north (Cordillera Blanca) and to the south (Junin region), the apparent

  10. Soil respiration under different land uses in Eastern China.

    PubMed

    Fan, Li-Chao; Yang, Ming-Zhen; Han, Wen-Yan

    2015-01-01

    Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84-98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q10 was 2.40, 2.00, and 1.86-1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q10 after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were

  11. An Investigation of Perceptional Differences between Eastern and Western Adolescents in Online Social Communication

    ERIC Educational Resources Information Center

    Zheng, Robert

    2013-01-01

    The current study focused on an important issue pertaining to online social communication by investigating perceptional differences between eastern and western adolescents. A total of 309 participants were recruited from three countries: China, Singapore, and the United States. Significant differences were found between eastern and western…

  12. Porphyry deposits of the Canadian Cordillera

    USGS Publications Warehouse

    McMillan, W.J.; Thompson, J.F.H.; Hart, C.J.R.; Johnston, S.T.

    1996-01-01

    Porphyry deposits are intrusion-related, large tonnage low grade mineral deposits with metal assemblages that may include all or some of copper, molybdenum, gold and silver. The genesis of these deposits is related to the emplacement of intermediate to felsic, hypabyssal, generally porphyritic intrusions that are commonly formed at convergent plate margins. Porphyry deposits of the Canadian Cordillera occur in association with two distinctive intrusive suites: calc-alkalic and alkalic. In the Canadian Cordillera, these deposits formed during two separate time periods: Late Triassic to Middle Jurassic (early Mesozoic), and Late Cretaceous to Eocene (Mesozoic-Cenozoic). Deposits of the early Mesozoic period occur in at least three different arc terranes (Wrangellia, Stikinia and Quesnellia) with a single deposit occurring in the oceanic assemblage of the Cache Creek terrane. These terranes were located outboard from continental North America during formation of most of their contained early Mesozoic porphyry deposits. Some of the deposits of this early period may have been emplaced during terrane collisions. Metal assemblages in deposits of the calc-alkalic suite include Mo-Cu (Brenda), Cu-Mo (Highland Valley, Gibraltar), Cu-Mo-Au-Ag (Island Copper, Schaft Creek) and Cu-Au (Kemess, Kerr).The alkalic suite deposits are characterized by a Cu-Au assemblage (Copper Mountain, Afton-Ajax, Mt. Milligan, Mount Polley, Galore Creek). Although silver is recovered from calc-alkalic and alkalic porphyry copper mining operations, silver data are seldom included in the published reserve figures. Those available are in the range of 1-2 grams per tonne (g??t-1). Alkalic suite deposits are restricted to the early Mesozoic and display distinctive petrology, alteration and mineralization that suggest a similar tectonic setting for both Quesnellia and Stikinia in Early Jurassic time. The younger deposits, late Mesozoic to Cenozoic in age, formed in an intracontinental setting, after the

  13. The Cretaceous stratigraphy of the Western Cordillera Oriental, Columbia

    SciTech Connect

    Allen, R.B.; Alfonso, C.A.; Ressetar, R.; Salazar, A. ); Ballesteros, I.; Cardozo, E.; Laverde, F.; Ramirez, C. ); Moreno, J.M. ); Rubiano, J.; Sarmiento, L. )

    1993-02-01

    During 1987 and 1988, a major field project sponsored by Tenneco was undertaken along the west flank of the Cordillera Oriental of Colombia between Alpujarra (between the Neiva and Girardot Sub-Basins) and the Middle Magdalena Basin (Cimitarra area). An important result of this study was the documentation of pronounced regional variation in the age, thickness, and facies of the Cretaceous section. The maximum thickness estimated was 7 km for the Bogota-Villeta section, with ages as old as Berriasian. This section can be divided into 4 or 5 depositional sequences. A clastic source to the west or southwest is indicated for the lower sequence 1 (and 2 ), an eastern source dominated sequences 3 and 4, and eastern and western sources supplied the upper sequence. Toward the north the section thins to an estimated 3-5 km but still ranges in age throughout the Cretaceous. Southward, on the other hand, the Cretaceous thins to about 2 km and is restricted to Aptian-Albian and younger ages. The variations in ages, facies, and thickness are consistent with recent models of the evolution of the Cretaceous basin. During the Neocomian, the Bogata area formed the main depocenter of the basin and was characterized by restricted facies and turbidites, suggesting steep, possibly faulted basin margins. Facies to the north, near the Middle Magdalena Basin, indicate shallower water, possibly a platform. By the end of the Early Cretaceous, expansion of the marine basin out of the central Cordillera Oriental and regionally more constant facies indicate the onset of dominantly thermal subsidence. The end of the Cretaceous was marked by regression and asymmetric clastic input from east and west of the basin.

  14. Geochronology and Equilibrium Line Altitudes of LLGM through Holocene Glaciations from the Tropical Cordillera Huayhuash, Peru

    NASA Astrophysics Data System (ADS)

    Hall, S. R.; Ramage, J. M.; Rodbell, D. T.; Finkel, R. C.; Smith, J. A.; Mark, B. G.; Farber, D. L.

    2006-12-01

    gradients assuming a constant temperature depression. Our results suggest that variations in glacial extent (and therefore paleo-ELAs) are strongly correlated with differences in valley orientation and morphology as eastern drainages receive more moisture and have shallower topographic gradients than western drainages. Additionally, while there is an extensive record of older (>39.9±1.4ka) advances to the north (Cordillera Blanca) and to the south (Junin region), the confined morphology of the Cordillera Huayhaush valleys may have inhibited the preservation of older glacial geomorphologic features, thereby explaining the apparent lack of old moraines in this range.

  15. Precambrian crust beneath the Mesozoic northern Canadian Cordillera discovered by Lithoprobe seismic reflection profiling

    NASA Astrophysics Data System (ADS)

    Cook, Frederick A.; Clowes, Ronald M.; Snyder, David B.; van der Velden, Arie J.; Hall, Kevin W.; Erdmer, Philippe; Evenchick, Carol A.

    2004-04-01

    The Cordillera in northern Canada is underlain by westward tapering layers that can be followed from outcrops of Proterozoic strata in the Foreland belt to the lowermost crust of the orogenic interior, a distance of as much as 500 km across strike. They are interpreted as stratified Proterozoic rocks, including ˜1.8-0.7 Ga supracrustal rocks and their basement. The layering was discovered on two new deep seismic reflection profiles in the Yukon (Line 3; ˜650 km) and northern British Columbia (Line 2; ˜1245 km in two segments) that were acquired as part of the Lithoprobe Slave-Northern Cordillera Lithospheric Evolution (SNORCLE) transect. In the Mackenzie Mountains of the eastern Yukon, the layering in Line 3 is visible between 5.0 and 12.0 s (˜15 to 36 km depth). It is followed southwestward for nearly 650 km (˜500 km across strike) and thins to less than 1.0 s (˜3.0-3.5 km thickness) near the Moho at the Yukon-Alaska international boundary. In the northern Rocky Mountains of British Columbia, the upper part of the layering on Line 2 correlates with outcrops of Proterozoic (1.76-1.0 Ga) strata in the Muskwa anticlinorium. At this location, the layering is at least 15 km thick and is followed westward then southward into the middle and lower crust for ˜700 km (˜300 km across strike). It disappears as a thin taper at the base of the crust ˜150 km east of the coast of the Alaskan panhandle. The only significant disruption in the layering occurs at the Tintina fault zone, a late to postorogenic strike-slip fault with up to 800 km of displacement, which appears as a vertical zone of little reflectivity that disrupts the continuity of the deep layering on both profiles (˜300 km apart). The base of the layered reflection zone coincides with the Moho, which exhibits variable character and undulates in a series of broad arches with widths of ˜150 km. In general, the mantle appears to have few reflections. However, at the southwest end of Line 3 near the Alaska

  16. Regional differences in rates of plant speciation and molecular evolution: a comparison between eastern Asia and eastern North America.

    PubMed

    Xiang, Qiu-Yun Jenny; Zhang, Wen Heng; Ricklefs, Robert E; Qian, Hong; Chen, Zhi Duan; Wen, Jun; Hua, Jian L

    2004-10-01

    The eastern Asian (EAS)-eastern North American (ENA) floristic disjunction is one of the best-known biogeographic patterns in the Northern Hemisphere. Recent paleontological and molecular analyses have illuminated the origins of the biogeographic pattern, but subsequent diversification and evolution of the disjunct floras in each of the two continents after isolation remains poorly understood. Although similar in climate and floristic composition, EAS has twice as many species as ENA in genera occurring in both regions. Explaining such differences in species diversity between regions with similar environmental conditions (diversity anomalies) is an important goal of the study of the global patterns of biodiversity. We used a phylogenetic approach to compare rates of net speciation and molecular evolution between the two regions. We first identified EAS-ENA disjunct sister clades from ten genera (Asarum, Buckleya, Carpinus, Carya, Cornus, Hamamelis, Illicium, Panax, Stewartia, and Styrax) that represent diverse angiosperm lineages using phylogenetic analyses of ITS (internal transcribed spacer of nuclear ribosomal DNA) sequence data. Species richness and substitution rate of ITS between sister clades were compared. The results revealed a pattern of greater species diversity in the EAS counterparts. A positive relationship between species diversity and ITS substitution rate was also documented. These results suggest greater net speciation and accelerated molecular evolution in EAS. The data support the idea that a regional difference in net speciation rate related to topographic heterogeneity contributes to the diversity anomaly between EAS and ENA. The close relationship between rates of ITS evolution and species richness further suggests that species production may be directly linked to rate of nucleotide substitution.

  17. Tectonics of the North American Cordillera near the Fortieth Parallel

    USGS Publications Warehouse

    King, P.B.

    1978-01-01

    The North American Cordillera near the Fortieth Parallel consists of the following tectonic units: 1. (A) To the east is a reactivated cratonic area, in the Southern Rocky Mountains and Colorado Plateau, in which the supracrustal rocks (Cambrian to Cretaceous) were broadly deformed during the late Cretaceous-Paleocene Laramide orogeny, and the Precambrian basement was raised in folds of wide amplitude. 2. (B) West of it is a miogeosynclinal belt, in the eastern Great Basin, in which a thick sequence of Paleozoic carbonates and related deposits was thrust eastward along low-angle faults during the middle to late Cretaceous Sevier orogeny. The miogeosyncline is the downwarped western margin of the original North American continent, and its rocks accumulated on Precambrian basement. 3. (C) Beyond is a eugeosynclinal belt, in the western Great Basin, in which Paleozoic graywackes, cherts, and volcanics were thrust easteastward along low-angle faults during several Paleozoic orogenies - the mid-Paleozoic Antler orogeny which produced the Roberts thrust on the east, and the end-Paleozoic Sonoma orogeny which produced the Golconda thrust farther west. The Paleozoic eugeosynclinal rocks accumulated on oceanic basement. They are overlapped from the west by Triassic and Jurassic shelf deposits, which pass westward into eugeosynclinal deposits. 4. (D) A volcanic island-arc belt existed on the sites of the Sierra Nevada in Paleozoic and early Mesozoic time, which produced thick bodies of sediments and volcanics. During the mid-Mesozoic Nevadan orogeny these were steeply deformed and thrust westward over subduction zones, and were intruded by granitic rocks that rose from the upper mantle to form great batholiths. 5. (E) West of the Sierra Nevada, in the Great Valley, is a great sedimentary embankment of later Mesozoic flysch or turbidite, largely younger than the supracrustal rocks of the Sierra Nevada and the Nevadan orogeny. It was formed of the erosional products of the

  18. Evolution of near-surface ramp-flat-ramp normal faults and implication during intramontane basin formation in the eastern Betic Cordillera (the Huércal-Overa Basin, SE Spain)

    NASA Astrophysics Data System (ADS)

    Pedrera, Antonio; Galindo-ZaldíVar, Jesús; Lamas, Francisco; Ruiz-ConstáN, Ana

    2012-08-01

    The nucleation, propagation, and associated folding of ramp-flat-ramp normal faults were analyzed from field examples developed in a brittle/ductile multilayer sequence of the Huércal-Overa Basin (SE Spain). Gently dipping sandy silt layers, which display a low cohesive strength (C0 = 7 kPa, μ= 34°), favor the development of extensional detachments. A tectonic origin instead of a possible gravitational origin is supported by the perpendicularity between the paleoslope direction of the fluvial-deltaic environment inferred from imbricated pebbles, and the senses of movement deduced from fault slicken-lines. The link between high-angle normal faults (HANFs) —formed at different levels in the layered sequence— with horizontal fault segments comes to develop ramp-flat-ramp normal faults with associated roll-over in the hanging wall. Observed extensional duplexes are formed by parallel detachments connected through synthetic Riedel faults. These Riedel faults would produce the back-rotation of the individual blocks (horses), i.e., extensional folding of the originally subhorizontal layers. There is no correlation between the analyzed ramp-flat-ramp normal faults, accommodating south-southeastward extension during Serravallian-lower Tortonian, and either the regional Alpujarride/Nevado-Filabride west-directed extensional shear zone or the top-to-the-north detachments within Alpujarride units, which are clearly sealed by Serravallian-lower Tortonian sediments. Therefore, the studied normal faults are restricted to the brittle/ductile multilayer fluvio/deltaic sequence and accommodate moderate late extension instead of belonging to a large crustal extensional system connected with a regional detachment at depth. Therefore, the basin formed in a moderate crustal thickness context where small and medium-scale extensional systems were subordinate structures. These natural examples support the development of low-angle normal faults at very shallow crustal levels in

  19. Evaluation of recent glacier recession in the Cordillera Blanca, Peru (AD 1962 1999): spatial distribution of mass loss and climatic forcing

    NASA Astrophysics Data System (ADS)

    Mark, Bryan G.; Seltzer, Geoffrey O.

    2005-11-01

    We use a combination of aerial photogrammetry, satellite imagery, and differential GPS mapping to quantify the volume of ice lost between AD 1962 and 1999 from three glaciers on Nevado Queshque in the Cordillera Blanca, Perú (˜10°S). The largest averaged surface lowering (thinning) occurred in the southwest aspect (22 m) and the least in the eastern aspect (5 m). A heuristic sensitivity analysis indicates that 9.3 W m -2 was required to melt the total observed ice loss and this can be explained by sensible heat transfer related to a temperature rise of 1 °C, combined with a latent heat decrease related to a 0.14 g kg -1 increase in specific humidity. A first-difference analysis of temperature records from 29 stations in the Cordillera Blanca shows an average rising trend of 0.26 °C per decade over the 37 year interval, more than adequate to supply the hypothesized sensible heat transfer. A simple transmittivity model within a digital elevation model indicates solar radiation related to altered cloudiness was not a predominant climatic forcing. The distribution of glacier area with altitude calculated with the digital terrain model explains the observed asymmetrical ice melt.

  20. New geochronological control for the tectono-magmatic evolution of the metamorphic basement, Cordillera Real and El Oro Province of Ecuador

    NASA Astrophysics Data System (ADS)

    Aspden, J. A.; Harrison, S. H.; Rundle, C. C.

    1992-08-01

    Some 150 new isotopic age determinations on metamorphic rocks from the Cordillera Real and parts of El Oro Province in Ecuador, using K-Ar, Rb-Sr, and Sm-Nd methods, help to clarify a complex succession of magmatic and tectonic events. The earliest regional metamorphic/plutonic event recognized, from the Tahuin Group in El Oro, is dated as between ca. 220 and 200 Ma (Late Triassic-Early Jurassic). Similar but less well constrained ages were also obtained from orthogneisses of the Sabanilla and Tres Lagunas subdivisions in the Cordillera Real. Major calc-alkaline granitoids were emplaced ca. 190-150 Ma (Middle-Late Jurassic) in the eastern part of the Cordillera Real, to the north of 2°S, and throughout the sub-Andean zone. Between ca. 140 and 120 Ma (Early Cretaceous), the Oriente region was uplifted and eroded and the Cordillera was affected by an important shearing (dynamothermal) event which results in the resetting of older plutonic ages. From ca. 20 to 85 Ma, conditions were relatively stable, but during ca. 85 to 65 Ma (Late Cretaceous), the Cordillera and Oriente were again uplifted. This uplift corresponds to a second widespread thermal overprinting, which produced a regional disturbance in the K-Ar isotopic systems. Throughout the Cordillera, a number of generally small, undeformed, dominantly lower Tertiary plutons are also present. A few older ( i.e., pre-Mesozoic) dates have been obtained but their interpretation remains uncertain.

  1. The differences in morphological development between the intertidal flats of the Eastern and Western Scheldt

    NASA Astrophysics Data System (ADS)

    de Vet, P. L. M.; van Prooijen, B. C.; Wang, Z. B.

    2017-03-01

    Human interventions have a large impact on estuarine morphology. The intertidal flats in the Eastern Scheldt and Western Scheldt estuaries (The Netherlands) have faced substantial morphological changes over the past decades. These changes are thought to be caused by human interventions, such as the construction of the storm surge barrier in the mouth of the Eastern Scheldt, and the deepening of the navigation channels of the Western Scheldt. This paper analyses several datasets and numerical simulations of hydrodynamics, providing an overview of the various morphological characteristics of the intertidal flats in the two estuaries over time and space. Apart from the volume, area and average height of these areas, also the integral steepness of each flat is quantified based on its full geometry. The analyses focus on the intertidal flats surrounded by water, which allows for a robust comparison between the different flats. The intertidal flats in the Western Scheldt appear to be substantially steeper compared to those in the Eastern Scheldt. The data indicates that a larger average height of a flat is related to a larger steepness. Despite variations in the evolution of the different flats, distinct characteristics of both estuaries are observed. An opposed trend is identified over time: the flats in the Western Scheldt have mainly increased in height, whereas the flats in the Eastern Scheldt have lowered after the completion of the storm surge barrier. This opposing development is associated with differences in tidal flow velocities in the estuaries, which are the result of human interventions.

  2. Gender differences in immigrant health: the case of Mexican and Middle Eastern immigrants.

    PubMed

    Read, Jen'nan Ghazal; Reynolds, Megan M

    2012-03-01

    This article draws on theories of gender inequality and immigrant health to hypothesize differences among the largest immigrant population, Mexicans, and a lesser known population of Middle Easterners. Using data from the 2000-2007 National Health Interview Surveys, we compare health outcomes among immigrants to those among U.S.-born whites and assess gender differences within each group. We find an immigrant story and a gender story. Mexican and Middle Eastern immigrants are healthier than U.S.-born whites, and men report better health than women regardless of nativity or ethnicity. We identify utilization of health care as a primary mechanism that contributes to both patterns. Immigrants are less likely than U.S.-born whites to interact with the health care system, and women are more likely to do so than men. Thus, immigrant and gender health disparities may partly reflect knowledge of health status rather than actual health.

  3. Diurnal Convection Peaks over the Eastern Indian Ocean over Sumatra during Different MJO Phases

    NASA Astrophysics Data System (ADS)

    Fujita, M.; Nasuno, T.; Yoneyama, K.

    2015-12-01

    The diurnal convection peak characteristics over the eastern Indian Ocean over the island of Sumatra during different phases of the Madden-Julian oscillation (MJO) were investigated. During MJO phases 2 to 3 (P2 and P3) defined by Wheeler and Hendon (2004), prominent diurnal variation in convection was observed by satellites when moderate low-level westerly winds were dominant over the eastern Indian Ocean. The diurnal convection peaks were prominent over the island of Sumatra in the evening, while migrations of the convection toward the Indian Ocean were observed in the early morning. By using the Global Positioning System around the western region offshore of Sumatra, a significant reduction in water vapor was observed from evening until midnight, compensating for the upward motion over the island. During midnight to early morning, the water vapor increased in the western offshore region as the convections migrated from the island. During P2 to P3, the atmosphere over the eastern Indian Ocean contains abundant water vapor, while the Maritime Continent is fairly well heated by solar radiation under calm conditions. This situation should be favorable for the development of two diurnal convection peaks: the evening convection over the land induced by solar radiative heating and the midnight convection over the ocean triggered by convergence of the low-level westerly wind and the land breeze.

  4. Recent glacier retreat and climate trends in Cordillera Huaytapallana, Peru

    NASA Astrophysics Data System (ADS)

    López-Moreno, J. I.; Fontaneda, S.; Bazo, J.; Revuelto, J.; Azorin-Molina, C.; Valero-Garcés, B.; Morán-Tejeda, E.; Vicente-Serrano, S. M.; Zubieta, R.; Alejo-Cochachín, J.

    2014-01-01

    We analyzed 19 annual Landsat Thematic Mapper images from 1984 to 2011 to determine changes of the glaciated surface and snow line elevation in six mountain areas of the Cordillera Huaytapallana range in Peru. In contrast to other Peruvian mountains, glacier retreat in these mountains has been poorly documented, even though this is a heavily glaciated area. These glaciers are the main source of water for the surrounding lowlands, and melting of these glaciers has triggered several outburst floods. During the 28-year study period, there was a 55% decrease in the surface covered by glaciers and the snowline moved upward in different regions by 93 to 157 m. Moreover, several new lakes formed in the recently deglaciated areas. There was an increase in precipitation during the wet season (October-April) over the 28-year study period. The significant increase in maximum temperatures may be related to the significant glacier retreat in the study area. There were significant differences in the wet season temperatures during El Niño (warmer) and La Niña (colder) years. Although La Niña years were generally more humid than El Niño years, these differences were not statistically significant. Thus, glaciers tended to retreat at a high rate during El Niño years, but tended to be stable or increase during La Niña years, although there were some notable deviations from this general pattern. Climate simulations for 2021 to 2050, based on the most optimistic assumptions of greenhouse gas concentrations, forecast a continuation of climate warming at the same rate as documented here. Such changes in temperature might lead to a critical situation for the glaciers of the Cordillera Huaytapallana, and may significantly impact the water resources, ecology, and natural hazards of the surrounding areas.

  5. East-west thrusting and anomalous magnetic declinations in the Sierra Gorda, Betic Cordillera, southern Spain

    NASA Astrophysics Data System (ADS)

    Platzman, E. S.

    1994-01-01

    Structural and palaeomagnetic studies in the Sierra Gorda (Sierra de Loja), located in the External zone of the Betic Cordillera, indicate that westward-directed thrusting is not associated with significant rotations about a vertical axis. Detailed mapping and slip vector analysis show that the Sierra Gorda is a thrust complex composed of three thrust sheets. The uppermost thrust places Early Jurassic pelagic carbonates on top of Jurassic to Oligocene sediments that form a large doubly-plunging footwall syncline. The eastern limb of this syncline has been overturned and is tectonically thinned as a result of the overthrusting. Palaeomagnetic results from Mesozoic and Tertiary sediments both within and around the perimeter of the Sierra Gorda indicate that: (1) the average remanence vector of the seven Late Jurassic localities sampled within the Sierra Gorda has a direction (D = 328° and I = 38°) that is not significantly different from the expected declination for the Upper Jurassic of stable Iberia; and (2) there is no significant difference between the remanences in the two upper thrust sheets indicating that differential rotation did not occur during the initiation and displacement on the thrusts. In contrast, the one Late Jurassic site that was sampled to the west of the Sierra Gorda is rotated, like the rest of the Subbetics, 60° clockwise of the reference direction. The unrotated directions obtained in the Sierra suggest, either that it has rotated in a clockwise sense concordant with the rest of the Subbetic zone and has then been backrotated, or that it has never rotated relative to stable Iberia. In the latter, simpler hypothesis the unrotated declinations may be explained in terms of orthogonal convergence along an irregular continental margin.

  6. Evaluating regional differences in macroinvertebrate communities from forested depressional wetlands across eastern and central North America.

    SciTech Connect

    Batzer, Darold, P.; Dietz-Brantley, Susan E.; Taylor, Barbera E.; DeBiase, Adrienne E.

    2005-02-12

    Batzer, Darold, P., Susan E. Dietz-Brantley, Barbera E. Taylor, and Adrienne E. DeBiase. 2005. Evaluating regional differences in macroinvertebrate communities from forested depressional wetlands across eastern and central North America. J. N. Am. Benthol. Soc. 24(2):403-414. Abstract. Forested depressional wetlands are an important seasonal wetland type across eastern and central North America. Macroinvertebrates are crucial ecosystem components of most forested depressional wetlands, but community compositions can vary widely across the region. We evaluated variation in macroinvertebrate faunas across eastern and central North America using 5 published taxa lists from forested depressional wetlands in Michigan, Ontario, Wisconsin, Florida, and Georgia. We supplemented those data with quantitative community descriptions generated from 17 forested depressional wetlands in South Carolina and 74 of these wetlands in Minnesota. Cluster analysis of presence/absence data from these 7 locations indicated that distinct macroinvertebrate communities existed in northern and southern areas. Taxa characteristic of northern forested depressionalwetlands included Sphaeriidae, Lumbriculidae, Lymnaeidae, Physidae, Limnephilidae, Chirocephalidae, and Hirudinea (Glossophoniidae and/or Erpodbellidae) and taxa characteristic of southern sites included Asellidae, Crangonyctidae, Noteridae, and Cambaridae. Quantitative sampling in South Carolina and Minnesota indicated that regionally characteristic taxa included some of the most abundant organisms, with Sphaeriidae being the 2nd most abundant macroinvertebrate in Minnesota wetlands and Asellidae being the 2nd most abundant macroinvertebrate in South Carolina wetlands. Mollusks, in general, were restricted to forested depressional wetlands of northern latitudes, a pattern that may reflect a lack of Ca needed for shell formation in acidic southern sites. Differences in community composition probably translate into region

  7. Documenting and describing the redox evolution of the Neoproterozoic ocean: lessons from the Canadian Cordillera (Invited)

    NASA Astrophysics Data System (ADS)

    Johnston, D. T.; Poulton, S. W.; Langmuir, C. H.; MacDonald, F. A.; Chen, Z.; Knoll, A.

    2009-12-01

    The geological record of the Neoproterozoic preserves evidence for large-scale perturbations in Earth’s climate and changes in tectonic configuration. During the terminal Proterozoic, and within the context of these changes, Earth’s fluid envelope achieved a level of oxygenation that allowed for the evolution and subsequent radiation of complex multi-cellular life. As such, better constraining the geochemical evolution of the oceans and atmosphere throughout the entire Neoproterozoic will allow for a more mechanistic understanding of the links between changing environmental chemistry and biological innovation. Further, it will provide information on the relative timing of these changes and, where robust dates are available, estimates on the absolute rates of change (both chemical and biological). To this end, our ongoing work has focused on constructing high stratigraphic resolution geochemical records through mixed lithological packages of sedimentary rocks from eastern Alaska and the Canadian Cordillera. Here, we present detailed chemostratigraphic reconstructions of redox sensitive proxies, including Fe-speciation and trace element budgets, that provide an integrated window into Neoproterozoic marine oxidant budgets. These oxidant budgets then allow for the modeling of the relative influence of different aerobic and anaerobic microbial processes on the overall carbon cycle. Taken together, it is this cascade of microbial processes that drives remineralization reactions, the sum of which serves to counter-act organic carbon export, which is ultimately responsible for the buildup of O2. This simple framework serves as the foundation for our interpretation of Neoproterozoic biogeochemistry and informs our view of late Precambrian marine ecosystems. This approach can be further applied to more specific, and perhaps even more anomalous intervals of Neoproterozoic Earth history, including the Cryogenian Bitter Springs event and the Ediacaran Shuram anomaly; both

  8. Disentangling Topographic and Climatic Change during the Late Cretaceous and Cenozoic in the Western US Cordillera

    NASA Astrophysics Data System (ADS)

    Snell, K. E.; Eiler, J. M.; Wernicke, B. P.; Peppe, D. J.; Fox, D. L.; Fetrow, A. C.; Passey, B. H.

    2014-12-01

    A diverse suite of tectonic and climatic drivers influenced the topographic evolution of the western USA Cordillera. Despite years of study, considerable uncertainty remains about fundamentals of this evolution, such as the timing and magnitude of maximum average elevations for the different physiographic provinces; the drivers and topographic effects of different episodes of extension during the Cenozoic; and the relative relief of peaks and intermontane basins within the Cordillera at different times and in different places. Numerous tectonic models have been developed to explain the evolution of the Cordillera, and understanding these details is key for distinguishing between these different models. In addition, the topographic changes in the Cordillera have important implications for regional and local climate of the western US at different times in the past, and may drive important differences in local climatic responses to global climate changes through the Cenozoic. The majority of the tools that currently exist for quantitatively reconstructing changes in topography through time and space rely on paleoclimate proxy data. Thus it is also important to be able to disentangle climatic change from elevation change in terrestrial paleoclimate records. To address some of these outstanding questions, we have generated and compiled paleotemperature estimates from the Late Cretaceous through the Miocene of the western US. In this presentation, we will focus on the latest installment of the project, which utilizes Oligocene paleotemperature records from central Utah and South Dakota and Miocene-Holocene paleotemperature records from Kansas. The data are dominantly composed of mean annual temperature estimates from leaf margin analysis and summer temperature estimates from carbonate clumped isotope thermometry. We will discuss how these data compare to temperature data from the Paleogene from the western US, what general trends exist within all the data and how these

  9. Gender differences in risk profile and outcome of Middle Eastern patients undergoing percutaneous coronary intervention

    PubMed Central

    Jarrah, Mohamad I.; Hammoudeh, Ayman J.; Al-Natour, Dalal B.; Khader, Yousef S.; Tabbalat, Ramzi A.; Alhaddad, Imad A.; Kullab, Susan M.

    2017-01-01

    Objectives: To determine the gender differences in cardiovascular risk profile and outcomes among patients undergoing percutaneous coronary intervention (PCI). Methods: In a prospective multicenter study of consecutive Middle Eastern patients managed with PCI from January 2013 to February 2014 in 12 tertiary care centers in Amman and Irbid, Jordan. Clinical and coronary angiographic features, and major cardiovascular events were assessed for both genders from hospital stay to 1 year. Results: Women comprised 20.6% of 2426 enrolled patients, were older (mean age 62.9 years versus 57.2 years), had higher prevalence of hypertension (81% versus 57%), diabetes (66% versus 44%), dyslipidemia (58% versus 46%), and obesity (44% versus 25%) compared with men, p<0.001. The PCI for ST-segment elevation myocardial infarction was indicated for fewer women than men (23% versus 33%; p=0.001). Prevalence of single or multi-vessel coronary artery disease was similar in women and men. More women than men had major bleeding during hospitalization (2.2% versus 0.6%; p=0.003) and at one year (2.5% versus 0.9%; p=0.007). There were no significant differences between women and men in mortality (3.1% versus 1.7%) or stent thrombosis (2.1% versus 1.8%) at 1 year. Conclusion: Middle Eastern women undergoing PCI had worse baseline risk profile compared with men. Except for major bleeding, no gender differences in the incidence of major adverse cardiovascular events were demonstrated. PMID:28133687

  10. Cretaceous Exhumation of the North American Cordillera Measured through Mineral Multi-Dating: Insights into Basin Filling Models and Orogenic Architecture

    NASA Astrophysics Data System (ADS)

    Painter, C. S.; Carrapa, B.; DeCelles, P. G.; Gehrels, G. E.; Thomson, S. N.

    2015-12-01

    Apatite fission track (AFT) thermochronology is an effective thermochronometer to measure source exhumation in the North American Cordillera, western U.S.A. We use a combination of thermochronology and geochronology to measure lag times, i.e., the difference in time between the cooling and depositional ages of a mineral crystal. These lag-time measurements using source exhumation ages, measured with AFT thermochronology, and depositional ages, measured with biostratigraphy and detrital zircon U-Pb geochronology, indicate constant to decreasing lag times of 0-5 m.y. throughout the Cretaceous. These lag times are consistent with rapid exhumation rates of ~0.9->1 km/m.y. One pitfall of using detrital thermochronology to measure source exhumation is assuring that the apatite crystals are exhumed apatites and not volcanic apatites introduced into the system from the volcanic arc. To do this we use U-Pb geochronology to remove samples contaminated with young arc derived apatites and keep those with old exhumed apatites. Five of the seven detrital AFT samples were significantly contaminated with young volcanic apatites, showing that U-Pb geochronology should be a routine step in measuring lag times. Our findings demonstrate that coarse-grained foreland basin deposits in the Cretaceous Western Interior, in both the proximal and distal settings, were deposited during times of active tectonism and exhumation and that sediments are not stored in wedge-top and proximal foredeep settings for long periods of time, i.e. >5 m.y., and then subsequently reworked distally. Exhumation rates of ~0.9->1 km/m.y. are not sustainable over the entire orogenic belt for the duration of the Sevier orogeny, indicated by the lack of deep-crustal material exhumed in the North American Cordillera. High exhumation rates were likely concentrated over the eastward-propagating Sevier fold-thrust belt, whereas the Nevadaplano and hinterland experienced much slower rates of exhumation. This variation in

  11. Luminescence dating of glacial deposits near the eastern Himalayan syntaxis using different grain-size fractions

    NASA Astrophysics Data System (ADS)

    Hu, Gang; Yi, Chao-Lu; Zhang, Jia-Fu; Liu, Jin-Hua; Jiang, Tao

    2015-09-01

    Numerical dating of glacial deposits is important for understanding Quaternary glacial evolution. Optically stimulated luminescence (OSL) dating is one of the techniques widely used on such sediments. Owing to the short distances traveled before deposition, the incomplete bleaching of luminescence signals in glacial sediments may introduce serious dating problems vis-à-vis glacial and any associated sediments. Here, we report a comparison of OSL ages obtained from the fine (4-11 μm) and medium (38-63 μm) grain size fractions of quartz extracted from glaciofluvial sediments and from glacial tills in the Basongcuo catchment near the eastern Himalayan syntaxis. Initially, four glacial stages were identified based on field observations of moraine distribution and geomorpho-stratigraphic relations. A total of 39 OSL samples were then collected from glaciofluvial sand layers or lenses and from till. Quartz grains in the fine (4-11 μm) and medium (38-63 μm) size fractions were extracted from each sample, and dated using the single-aliquot regeneration (SAR) protocol. The modern supraglacial sediment sample was dated to ˜0.2 (fine grain) to ˜0.7 (medium grain) ka, suggesting that the sediment was not completely bleached on deposition. Contrary to previous experience suggesting that coarse grains are usually better bleached than fine grains prior to deposition, our results show that estimated OSL ages for fine grains are generally younger than those for medium grains. This suggests that the two fractions may have come from different sources and thus have different bleaching histories, and that fine-grained quartz may be more suitable for OSL dating of these materials. Applying the minimum age model to data from medium-grained quartz yields ages close to those obtained from fine-grained quartz, suggesting that both can be used for dating glacial advances. The OSL dates suggest that glaciers in the studied area advanced at 0.1-1.3 ka, ˜7.5 ka and 11-13 ka, and were

  12. Microbial community diversity of the eastern Atlantic Ocean reveals geographic differences

    NASA Astrophysics Data System (ADS)

    Friedline, C. J.; Franklin, R. B.; McCallister, S. L.; Rivera, M. C.

    2012-01-01

    Prokaryotic communities are recognized as major drivers of the biogeochemical processes in the oceans. However, the genetic diversity and composition of those communities is poorly understood. The aim of this study was to investigate the eubacterial communities in three different water layers: surface (2-20 m), deep chlorophyll maximum (DCM; 28-90 m), and deep (100-4600 m) at nine stations along the eastern Atlantic Ocean from 42.8° N to 23.7° S. In order to describe the dynamics of the eubacterial assemblages in relation to depth, associated environmental properties, and Longhurstian ecological provinces community DNA was extracted from 16 samples, from which the V6 region of 16s rDNA was PCR-amplified with eubacteria-specific primers, and the PCR amplicons were pyrosequenced. A total of 352 029 sequences were generated; after quality filtering and processing, 257 260 sequences were clustered into 2871 normalized Operational Taxonomic Units (OTU) using a definition of 97% sequence identity. Comparisons of the phylogenetic affiliation of those 2871 OTUs show more than 54% of them were assigned to the Proteobacteria, with the Alphaproteobacteria representing 4% of the total Proteobacteria OTUs, and the Gammaproteobacteria representing 22%. Within the Alphaproteobacteria-affiliated OTUs, 44% of the OTUs were associated with the ubiquitous SAR11 clade. The phylum Cyanobacteria represent 10% of the reads, with the majority of those reads among the GpIIa family including Prochlorococcus and Synechococcus. Among the Gammaproteobacteria, a single OTU affiliated to Alteromonas comprises ~3% of the abundance. The phyla Bacteroidetes, Verrucomicrobia, Actinobacteria, and Firmicutes represent approximately 7%, 0.8%, 2%, and 0.05% of the read abundance, respectively. Community ecology statistical analyses and a novel implementation of Bayesian inference suggests that eastern Atlantic Ocean eubacterial assemblages are vertically stratified and associated with water layers

  13. Different algal symbionts explain the vertical distribution of dominant reef corals in the eastern Pacific.

    PubMed

    Iglesias-Prieto, R; Beltrán, V H; LaJeunesse, T C; Reyes-Bonilla, H; Thomé, P E

    2004-08-22

    Symbiotic reef corals occupy the entire photic zone; however, most species have distinct zonation patterns within the light intensity gradient. It is hypothesized that the presence of specific symbionts adapted to different light regimes may determine the vertical distribution of particular hosts. We have tested this hypothesis by genetic and in situ physiological analyses of the algal populations occupying two dominant eastern Pacific corals, over their vertical distribution in the Gulf of California. Our findings indicate that each coral species hosts a distinct algal taxon adapted to a particular light regime. The differential use of light by specific symbiotic dinoflagellates constitutes an important axis for niche diversification and is sufficient to explain the vertical distribution patterns of these two coral species.

  14. Different algal symbionts explain the vertical distribution of dominant reef corals in the eastern Pacific.

    PubMed Central

    Iglesias-Prieto, R.; Beltrán, V. H.; LaJeunesse, T. C.; Reyes-Bonilla, H.; Thomé, P. E.

    2004-01-01

    Symbiotic reef corals occupy the entire photic zone; however, most species have distinct zonation patterns within the light intensity gradient. It is hypothesized that the presence of specific symbionts adapted to different light regimes may determine the vertical distribution of particular hosts. We have tested this hypothesis by genetic and in situ physiological analyses of the algal populations occupying two dominant eastern Pacific corals, over their vertical distribution in the Gulf of California. Our findings indicate that each coral species hosts a distinct algal taxon adapted to a particular light regime. The differential use of light by specific symbiotic dinoflagellates constitutes an important axis for niche diversification and is sufficient to explain the vertical distribution patterns of these two coral species. PMID:15306298

  15. Seasonal frost conditions in different periglacial landforms in the Eastern Pyrenees from 2003 to 2015

    NASA Astrophysics Data System (ADS)

    Salvador-Franch, Ferran; Salvà-Catarineu, Montserrat; Oliva, Marc; Gómez-Ortiz, Antonio

    2016-04-01

    Glaciers shaped the headwaters and valley floors in the Eastern Pyrenees during the Last Glaciation at elevations above 2100-2200 m. Since the deglaciation of these areas, periglacial processes have generated a wide range of periglacial landforms, such as rock glaciers, patterned ground and debris slopes. The role of soil temperatures is decisive for the degree of activity of periglacial processes: cryoturbation, solifluction, frost weathering, etc. Nowadays, periglacial processes in the Eastern Pyrenees are driven by a seasonal frozen layer extending 5-7 months. In general, at 2100 m the seasonal frost reaches 20 cm depth, while at 2700 m reaches 50 cm depth. However, soil temperatures, and thus, periglacial processes are strongly controlled by the large interannual variability of the snow cover. With the purpose of understanding the rhythm and intensity of soil freezing/thawing in 2003 we set up several monitoring sites along a vertical transect from the valley floors (1100 m) to the high plateaus (2700 m) across the southern slope of the Puigpedrós massif (2914 m), in the Eastern Pyrenees. The monitoring of soil temperatures has been conducted from 2003 to 2015 in different periglacial landforms using UTL and Hobo loggers. These loggers were installed at depths of 5, 20 and 50 cm at five sites: Calmquerdós (2730 m), Malniu (2230 m), La Feixa (2150 m), Meranges (1600 m) and Das (1097 m). Air temperatures used as reference come from two automatic stations of the Catalan Meteorological Survey in Malniu and Das, and with two loggers installed in La Feixa and Meranges. No permafrost regime was detected in none of the sites. Data shows evidence of the control of snow cover on the depth of the frozen layer and on the number of freeze-thaw cycles. Air temperatures at 2000-2200 m show a mean of 150 freeze-thaw cycles per year. In La Feixa, with very thin snow cover, only 67 cycles are recorded at 5 cm depth and 5 cycles at 50 cm depth. In Malniu, located at a higher

  16. Slope stability of moraines, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Klimes, J.; Novotny, J.

    2012-12-01

    Landslides originating from inner slopes of moraine dams are often capable of producing glacial lakes outburst floods (GLOFs). Therefore assessing stability conditions of the moraines is important for predicting this potentially damaging phenomenon. Characteristics of the basic mechanical properties of the material and geophysical investigations were applied to collect necessary information for slope stability assessment of the Palcacocha Lake moraine dam, Peru. The lake is situated in the Cordillera Blanca Mts. at the altitude of about 4,500m asl and produced catastrophic GLOF in 1941. Another minor flood originated in 2003 due to landslide impact into the lake. Detailed investigations of this landslide site included geomorphological mapping, geophysical investigations and characterization of basic mechanical properties of the forming material. Geomorphological mapping identified dormant landslide with scarp up to 2m high which developed on the edge of the inner moraine slope. It is conditioned by set of parallel extension trenches which also affected the origin of 2003 landslide. Within its scarp area, significant water bearing layer was noticed around 10 m bellow the moraine surface. Three profiles were investigated using electric resistivity tomography performed on 4poing light instrument with 24 electrodes and with spacing ranging from 1 to 4m. Results helped to verify geometry of the main shear plane of the mapped landslide as well as the spacing and depth of extension trenches. Significant heterogeneity in the moraine resistivity characteristics was found. The high resistivity regions are explained by rock block accumulation whereas the low resistivity may represent wet layers within the moraine body. Grain size distribution of 33 disturbed soil samples originating from moraine material within the Cordillera Blanca Mts., Peru were determined and classified according to the UCSC classification system. The samples were taken from moraine dams and slopes

  17. K-Ar dates from the Altiplano and Cordillera Oriental of Bolivia: implications for Cenozoic stratigraphy and tectonics

    NASA Astrophysics Data System (ADS)

    Kennan, L.; Lamb, S.; Rundle, C.

    1995-04-01

    New K-Ar dates from tuffs, lavas and granites, collected in the Bolivian Altiplano and Cordillera Oriental, constrain the evolution of the Bolivian Andes. A phlogopite megacryst from a post-cleavage kimberlite dike near Independencia gave an age of ca. 98 Ma. In the central Altiplano, a widespread suite of basaltic to andesitic lavas, sills and rhyolitic tuffs has yielded dates of 25-22 Ma, coeval with the first major influx of conglomerates in the central Altiplano basin. Rapid early Miocene erosion of the Cordillera Oriental is suggested by biotites from the Quimsa Cruz Granite in the Cordillera Oriental, which vary in age between 32-22 Ma, and also by zircon fission track data. Gentle folding in the Cordillera Oriental near Potosi pre-dates the early Miocene Mondragon Formation which contains a ca. 19 Ma ignimbrite near its base. Further folding here occurred prior to the eruption of the flat-lying ca. 7 Ma ignimbrites of the Condor Nasa Meseta and ca. 12 Ma ignimbrites from the central Los Frailes Meseta. Intense folding in the central Altiplano also occurred between 9 Ma and 5 Ma, and younger tuffs are only slightly tilted. In the Cochabamba region, sedimentary infill of the Parotani Basin contains a ca. 20 Ma tuff horizon, and folded tuffs from the nearby Sacaba Basin have been dated at ca. 2.2 Ma. These ages suggest a protracted history for associated basin-margin ESE sinistral strike-slip and normal faults. However, regional folding pre-dates the San Juan del Oro Surface, which formed an extensive flatlying peneplain, preserved at ca. 3000 m in the central and eastern Cordillera Oriental. The age of valley-fill tuffs suggest that dissection of this surface had commenced in the Cochabamba region by 6.5 Ma. However, near Sucre, flat-lying tuffs, dated between 3.5 and 1.4 Ma, mantle the surface and predate the deep Pleistocene dissection of the central Cordillera Oriental. Deformation has been concentrated in the Subandean foreland thrust belt since the

  18. Different survival outcomes after curative R0-resection for Eastern Asian and European gastric cancer

    PubMed Central

    Kim, Young-Woo; Joo, Jungnam; Yoon, Hong Man; Eom, Bang Wool; Ryu, Keun Won; Choi, Il Ju; Kook, Myeong Cherl; Schuhmacher, Christoph; Siewert, Joerg Ruediger; Reim, Daniel

    2016-01-01

    Abstract Several retrospective analyses on patients who underwent gastric cancer (GC) surgery revealed different survival outcomes between Eastern (Korean, Japanese) and Western (USA, Europe) countries due to potential ethnical and biological differences. This study investigates treatment outcomes between specialized institution for GC in Korea and Germany. The prospectively documented databases of the Gastric Cancer Center of the National Cancer Center, Korea (NCCK) and the Department of Surgery of the Technische Universitaet Muenchen (TUM), Germany were screened for patients who underwent primary surgical resection for GC between 2002 and 2008. Baseline characteristics were compared using χ2 testing, and 2 cohorts were matched using a propensity score matching (PSM) method. Patients’ survival was estimated using Kaplan–Meier method, and multivariable Cox proportional hazard model was used for comparison. Three thousand seven hundred ninety-five patients were included in the final analysis, 3542 from Korea and 253 from Germany. Baseline characteristics revealed statistically significant differences for age, tumor location, pT stage, grading, lymphatic vessel infiltration (LVI), comorbidities, number of dissected lymph nodes (LN), postoperative complications, lymph-node ratio stage, and application of adjuvant chemotherapy. After PSM, 171 patients in TUM were matched to NCCK patients, and baseline characteristics for both cohorts were well balanced. Patients in Korea had significantly longer survival than those in Germany both before and after PSM. When the analysis was performed for each UICC stage separately, same trend was found over all UICC stages before PSM. However, significant difference in survival was observed only for UICC I after PSM. This analysis demonstrates different survival outcomes after surgical treatment of GC on different continents in specialized centers after balancing of baseline characteristics by PSM. PMID:27428238

  19. Two new species of Salamanders, Genus Bolitoglossa (Amphibia: Plethodontidae), from the Eastern Colombian Andes.

    PubMed

    Acevedo, Aldemar A; Wake, David B; Márquez, Roberto; Silva, Karen; Franco, Rosmery; Amézquita, Adolfo

    2013-01-25

    The salamander fauna of Colombia is very poorly known, probably because most research efforts have been devoted to anurans during the last two decades. Here, we describe two new species of the genus Bolitoglossa (Eladinea) from the eastern flank of the Eastern Colombian Andes (Cordillera Oriental), near the border with Venezuela. Bolitoglossa tamaense sp. nov. is distributed between 2000 to 2700 m.a.s.l. and Bolitoglossa leandrae sp. nov. is distributed in the low-lands at about 600 m. The new species are diagnosed by a combination of molecular (16S rRNA sequences), coloration, body size, and morphometric (number of maxillary and vomerine teeth and differences in foot webbing) characters. Both species face threats such as chytridiomycosis infections and habitat fragmentation that have already affected other sala-manders in the country. Thus, intensive field and museum work is needed to better document and perhaps protect the local salamander diversity.

  20. Liquefaction and fluidization structures in Messinian storm deposits (Bajo Segura Basin, Betic Cordillera, southern Spain)

    NASA Astrophysics Data System (ADS)

    Alfaro, P.; Delgado, J.; Estévez, A.; Molina, J. M.; Moretti, M.; Soria, J. M.

    2002-05-01

    Synsedimentary deformation structures are recognized in Upper Miocene deposits of the eastern Betic Cordillera (SE Spain). A singular stratigraphic section in these deposits shows several levels with soft-sediment deformation structures (load casts, ball-and-pillows and pipes) induced by liquidization (liquefaction and/or fluidization) of sandy sediments. The morphologic analysis of these structures reveals a liquidized sediment thickness ranging from 0.1 to 1.5 m. Although they have been previously interpreted as a result of seismic shocks, their origin was most likely related to the action of storm waves as the structures are always associated with tempestites. Facies analysis, geometrical features of the deformed beds and appraisal of geotechnical properties for shelf and coastal sediments allow the soft-sediment deformation structures to be interpreted as a result of the cyclic effect of storm waves on unconsolidated sediments, and excludes other processes such as overloading, tsunamis or the impact of breaking waves.

  1. Landsat TM and ETM+ derived snowline altitudes in the Cordillera Huayhuash and Cordillera Raura, Peru, 1986-2005

    NASA Astrophysics Data System (ADS)

    McFadden, E. M.; Ramage, J.; Rodbell, D. T.

    2011-05-01

    The Cordilleras Huayhuash and Raura are remote glacierized ranges in the Andes Mountains of Peru. A robust assessment of modern glacier change is important for understanding how regional change affects Andean communities, and for placing paleo-glaciers in a context relative to modern glaciation and climate. Snowline altitudes (SLAs) derived from satellite imagery are used as a proxy for modern (1986-2005) local climate change in a key transition zone in the Andes. Clear sky, dry season Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) satellite images from 1986-2005 were used to identify snowline positions, and their altitude ranges were extracted from an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital elevation model (DEM). Based on satellite records from 31 glaciers, average snowline altitudes (SLAs), an approximation for the equilibrium line altitude (ELA), for the Cordillera Huayhuash (13 glaciers) and Cordillera Raura (18 glaciers) from 1986-2005 were 5051 m a.s.l. from 1986-2005 and 5006 m a.s.l. from 1986-2002, respectively. During the same time period, the Cordillera Huayhuash SLA experienced no significant change while the Cordillera Raura SLA rose significantly from 4947 m a.s.l. to 5044 m a.s.l.

  2. Landsat TM and ETM+ derived snowline altitudes in the Cordillera Huayhuash and Cordillera Raura, Peru, 1986-2005

    NASA Astrophysics Data System (ADS)

    McFadden, E. M.; Ramage, J.; Rodbell, D. T.

    2010-10-01

    The Cordilleras Huayhuash and Raura are remote glacierized ranges in the Andes Mountains of Peru. A robust assessment of modern glacier change is important for understanding how regional change affects Andean communities, and for placing paleo-glaciers in a context relative to modern glaciation and climate. Snowline altitudes (SLAs) derived from satellite imagery are used as a proxy for modern (1986-2005) local climate change in a key transition zone in the Andes. Clear sky, dry season Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) satellite images from 1986-2005 were used to identify snowline positions, and their altitude ranges were extracted from an Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) DEM. Based on satellite records from 31 glaciers, mean snowline altitudes (SLAs), an approximation for the equilibrium line altitudes (ELAs), for the Cordillera Huayhuash (13 glaciers) and Cordillera Raura (18 glaciers) were 5046 m a.s.l. and 5013 m a.s.l., respectively, from 1986-2005. The rate of SLA rise was 25 m/decade in the Cordillera Huayhuash and 62 m/decade in the Cordillera Raura.

  3. Mollusc and plant assemblages controlled by different ecological gradients at Eastern European fens

    NASA Astrophysics Data System (ADS)

    Schenková, Veronika; Horsák, Michal; Hájek, Michal; Plesková, Zuzana; Dítě, Daniel; Pawlikowski, Paweł

    2014-04-01

    Ecological patterns of mollusc assemblages and vegetation in relation to water chemistry, water regime, nutrient availability and climate were studied in eastern Polish lowland fens. Our goal was to examine if major compositional changes differ for molluscs and vegetation under the joint influence of multiple ecological gradients. Altogether 32 fen sites were investigated in 2010-2011, and analyzed using metric multidimensional scaling, cluster analysis and generalized additive models. Two major gradients driving the differences in mollusc species composition were revealed. The main direction of compositional changes was associated with the water table gradient, governing a species turnover from inundated and strongly water-logged sites occupied mostly by aquatic mollusc species, to moderately wet sites with the predominance of fen and meadow species. The second most important gradient for molluscs was that of mineral richness. For vegetation, three major gradients explained the changes in species composition. The highest importance was assigned to the nitrogen-to-phosphorus availability gradient (defined as a shift from N-limited to P-limited vegetation), followed by the water table gradient, and the mineral richness gradient. Our results demonstrate that the impact of mineral richness gradient, which has been often reported as the major determinant of compositional changes of fen molluscs and vegetation, can be exceeded by other ecological gradients of comparable variation. We also document for the first time that the main species turnover of fen vegetation is not accompanied by the analogous change in species composition of mollusc assemblages, due to a different sensitivity of these taxa to particular environmental factors (i.e. water level dynamics and type of nutrient limitation).

  4. Investigating Differences in Vigilance Tactic Use within and between the Sexes in Eastern Grey Kangaroos

    PubMed Central

    Rieucau, Guillaume; Blanchard, Pierrick; Martin, Julien G. A.; Favreau, François-René; Goldizen, Anne W.; Pays, Olivier

    2012-01-01

    Aggregation is thought to enhance an animal’s security through effective predator detection and the dilution of risk. A decline in individual vigilance as group size increases is commonly reported in the literature and called the group size effect. However, to date, most of the research has only been directed toward examining whether this effect occurs at the population level. Few studies have explored the specific contributions of predator detection and risk dilution and the basis of individual differences in the use of vigilance tactics. We tested whether male and female (non-reproductive or with young) eastern grey kangaroos (Macropus giganteus) adopted different vigilance tactics when in mixed-sex groups and varied in their reliance on predator detection and/or risk dilution as group size changed. This species exhibits pronounced sexual dimorphism with females being much smaller than males, making them differentially vulnerable toward predators. We combined field observations with vigilance models describing the effects of detection and dilution on scanning rates as group size increased. We found that females with and without juveniles relied on predator detection and risk dilution, but the latter adjusted their vigilance to the proportion of females with juveniles within their group. Two models appeared to equally support the data for males suggesting that males, similarly to females, relied on predator detection and risk dilution but may also have adjusted their vigilance according to the proportion of mothers within their group. Differential vulnerability may cause sex differences in vigilance tactic use in this species. The presence of males within a group that do not, or only partially, contribute to predator detection and are less at risk may cause additional security costs to females. Our results call for reexamination of the classical view of the safety advantages of grouping to provide a more detailed functional interpretation of gregariousness. PMID

  5. Earthquake Interactions at Different Scales: an Example from Eastern California and Western Nevada, USA.

    NASA Astrophysics Data System (ADS)

    Verdecchia, A.; Carena, S.

    2015-12-01

    Earthquakes in diffuse plate boundaries occur in spatially and temporally complex patterns. The region east of the Sierra Nevada that encompasses the northern Eastern California Shear Zone (ECSZ), Walker Lane (WL), and the westernmost part of the Basin and Range province (B&R) is such a kind of plate boundary. In order to better understand the relationship between moderate-to major earthquakes in this area, we modeled the evolution of coseismic, postseismic and interseismic Coulomb stress changes (∆CFS) in this region at two different spatio-temporal scales. In the first example we examined seven historical and instrumental Mw ≥ 6 earthquakes that struck the region around Owens Valley (northern ECSZ) in the last 150 years. In the second example we expanded our study area to all of the northern ECSZ, WL and western B&R, examining seventeen paleoseismological and historical major surface-rupturing earthquakes (Mw ≥ 6.5) that occurred in the last 1400 years. We show that in both cases the majority of the studied events (100% in the first case and 80% in the second) are located in areas of combined coseismic and postseismic positive ∆CFS. This relationship is robust, as shown by control tests with random earthquake sequences. We also show that the White Mountain fault has accumulated up to 30 bars of total ∆CFS (coseismic + postseismic + interseismic) in the last 150 years, and the Hunter Mountain, Fish Lake Valley, Black Mountain, and Pyramid Lake faults have accumulated 40, 45, 54 and 37 bars respectively in the last 1400 years. Such values are comparable to the average stress drop in a major earthquake, and all these faults may be therefore close to failure.

  6. Aerosol Optical Depth spatiotemporal variability and contribution of different aerosol types over Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Georgoulias, Aristeidis K.; Alexandri, Georgia; Kourtidis, Konstantinos; Zanis, Prodromos; Pöschl, Ulrich; Lelieveld, Jos; Levy, Robert; Amiridis, Vassilis; Marinou, Eleni; Tsikerdekis, Athanasios; Pozzer, Andrea

    2015-04-01

    In this work, we study the aerosol spatiotemporal variability over the region of Eastern Mediterranean, for the time period 2000-2012, using a 0.1-degree gridded dataset compiled from level-2 MODIS TERRA and MODIS AQUA AOD550 and FMR550 data. A detailed validation of the AOD550 data was implemented using ground-based observations from the AERONET, also showing that the gridding methodology we followed allows for the detection of several local hot spots that cannot be seen using lower resolutions or level-3 data. By combining the MODIS data with data from other satellite sensors (TOMS, OMI), data from a global chemical-aerosol-transport model (GOCART), and reanalysis data from MACC and ERA-interim, we quantify the relative contribution of different aerosol types to the total AOD550 for the period of interest. For this reason, we developed an optimized algorithm for regional studies based on results from previous global studies. Over land, anthropogenic, dust, and fine-mode natural aerosols contribute to the total AOD550, while anthropogenic, dust and maritime AODs are calculated over the ocean. The dust AOD550 over the region was compared against dust AODs from the LIVAS CALIPSO product, showing a similar seasonal variability. Finally, we also look into the aerosol load short-term trends over the region for each aerosol type separately, the results being strongly affected by the selected time period. The research leading to these results has received funding from the European Social Fund (ESF) and national resources under the operational programme Education and Lifelong Learning (EdLL) within the framework of the Action "Supporting Postdoctoral Researchers" (QUADIEEMS project) and from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 226144 (C8 project).

  7. Soil seed bank in different habitats of the Eastern Desert of Egypt.

    PubMed

    Gomaa, Nasr H

    2012-04-01

    The floristic composition and species diversity of the germinable soil seed bank were studied in three different habitats (desert salinized land, desert wadi, and reclaimed land) in the Eastern Desert of Egypt. Moreover, the degree of similarity between the seed bank and the above-ground vegetation was determined. The seed bank was studied in 40 stands representing the three habitats. Ten soil samples (each 25 × 20 cm and 5 cm depth) were randomly taken per stand. The seed bank was investigated by the seedling emergence method. Some 61 species belonging to 21 families and 54 genera were identified in the germinable seed bank. The recorded species include 43 annuals and 18 perennials. Ordination of stands by Detrended Correspondence Analysis (DCA) indicates that the stands of the three habitats are markedly distinguishable and show a clear pattern of segregation on the ordination planes. This indicates variations in the species composition among habitats. The results also demonstrate significant associations between the floristic composition of the seed bank and edaphic factors such as CaCO3, electrical conductivity, organic carbon and soil texture. The reclaimed land has the highest values of species richness, Shannon-index of diversity and the density of the germinable seed bank followed by the habitats of desert wadi and desert salinized land. Motyka's similarity index between the seed bank and the above-ground vegetation is significantly higher in reclaimed land (75.1%) compared to desert wadi (38.4%) and desert salinized land (36.5%).

  8. Genetic Diversity of Eukaryotic Plankton Assemblages in Eastern Tibetan Lakes Differing by their Salinity and Altitude

    PubMed Central

    2011-01-01

    Eukaryotic plankton assemblages in 11 high-mountain lakes located at altitudes of 2,817 to 5,134 m and over a total area of ca. one million square kilometers on the Eastern Tibet Plateau, spanning a salinity gradient from 0.2 (freshwater) to 187.1 g l−1 (hypersaline), were investigated by cultivation independent methods. Two 18S rRNA gene-based fingerprint approaches, i.e., the terminal restriction fragment length polymorphism and denaturing gradient gel electrophoresis (DGGE) with subsequent band sequencing were applied. Samples of the same lake type (e.g., freshwater) generally shared more of the same bands or T-RFs than samples of different types (e.g., freshwater versus saline). However, a certain number of bands or T-RFs among the samples within each lake were distinct, indicating the potential presence of significant genetic diversity within each lake. PCA indicated that the most significant environmental gradient among the investigated lakes was salinity. The observed molecular profiles could be further explained (17–24%) by ion percentage of chloride, carbonate and bicarbonate, and sulfate, which were also covaried with change of altitude and latitude. Sequence analysis of selected major DGGE bands revealed many sequences (largely protist) that are not related to any known cultures but to uncultured eukaryotic picoplankton and unidentified eukaryotes. One fourth of the retrieved sequences showed ≤97% similarity to the closest sequences in the GenBank. Sequences related to well-known heterotrophic nanoflagellates were not retrieved from the DGGE gels. Several groups of eukaryotic plankton, which were found worldwide and detected in low land lakes, were also detected in habitats located above 4,400 m, suggesting a cosmopolitan distribution of these phylotypes. Collectively, our study suggests that there was a high beta-diversity of eukaryotic plankton assemblages in the investigated Tibetan lakes shaped by multiple geographic and environmental factors

  9. Dual origins of lode gold deposits in the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Nesbitt, Bruce E.; Murowchick, James B.; Muehlenbachs, Karlis

    1986-06-01

    From Late Jurassic to late Tertiary time, two geologically, geochemically, and genetically distinct gold mineralization processes were active in the Canadian Cordillera. One group of deposits can be characterized as epithermal because of its association with intermediate to felsic volcanics, regional caldera structures, low pH alteration zones, low Au/Ag values, and quartz-chalcedony-barite-fluorite gangue. The second group of deposits is mesothermal in character and has strong similarities to the Mother Lode deposits of California, being associated with transcurrent faults, intermediate pH alteration zones, and quartz ± carbonate, albite, mariposite, pyrite, arsenopyrite, scheelite gangue. Compared to epithermal deposits, mesothermal deposits have higher As, W, and Au/Ag values, higher CO2 content in fluid inclusions, and δ18O values of ore-forming fluids of +3‰ to +10‰ vs. -14‰ to -7‰ for epithermal deposits. Like the gold deposits in Nevada and Colorado, epithermal mineralization in the Canadian Cordillera formed from the shallow circulation of meteoric water in subaerial, intermediate to felsic volcanic complexes. In contrast, mesothermal gold deposits throughout the North American Cordillera are shown to be the product of deep circulation and evolution of meteoric water in structures associated with major, transcurrent fault zones. Similarities between Archean lode gold deposits and mesothermal deposits of the Cordillera suggest that Archean lode deposits may have been produced by processes similar to those involved in the formation of Cordilleran mesothermal deposits.

  10. Tectonic differences between eastern and western sub-basins of the Qiongdongnan Basin and their dynamics

    NASA Astrophysics Data System (ADS)

    Liu, Jianbao; Sun, Zhen; Wang, Zhenfeng; Sun, Zhipeng; Zhao, Zhongxian; Wang, Zhangwen; Zhang, Cuimei; Qiu, Ning; Zhang, Jiangyang

    2015-03-01

    The central depression of the Qiongdongnan Basin can be divided into the eastern and western sub-basins by the Lingshui-Songnan paleo-uplift. To the northwest, the orientation of the faults turns from NE, to EW, and later to NW; In the southwest, the orientation of the faults turns from NE, to NNE, and then to NW, making the central depression much wider towards the west. In the eastern sub-basin, the NE-striking faults and the EW-striking faults made up an echelon, making the central depression turn wider towards the east. Fault activity rates indicate that faulting spreads gradually from both the east and west sides to the middle of the basin. Hence, extensional stress in the eastern sub-basin may be related to the South China Sea spreading system, whereas the western sub-basin was more under the effect of the activity of the Red River Fault. The extreme crustal stretching in the eastern sub-basin was probably related to magmatic setting. It seems that there are three periods of magmatic events that occurred in the eastern sub-basin. In the eastern part of the southern depression, the deformed strata indicate that the magma may have intruded into the strata along faults around T60 (23.3 Ma). The second magmatic event occurred earlier than 10.5 Ma, which induced the accelerated subsidence. The final magmatic event commenced later than 10 Ma, which led to today's high heat flow. As for the western sub-basin, the crust thickened southward, and there seemed to be a southeastward lower crustal flow, which happened during continental breakup which was possibly superimposed by a later lower crustal flow induced by the isostatic compensation of massive sedimentation caused by the right lateral slipping of the Red River Fault. Under the huge thick sediment, super pressure developed in the western sub-basin. In summary, the eastern sub-basin was mainly affected by the South China Sea spreading system and a magma setting, whereas the western sub-basin had a closer

  11. Virological Characteristics of Acute Hepatitis B in Eastern India: Critical Differences with Chronic Infection

    PubMed Central

    Sarkar, Neelakshi; Pal, Ananya; Das, Dipanwita; Saha, Debraj; Biswas, Avik; Bandopadhayay, Bhaswati; Chakraborti, Mandira; Ghosh, Mrinmoy; Chakravarty, Runu

    2015-01-01

    Hepatitis B Virus (HBV) manifests high genetic variability and is classifiable into ten genotypes (A-J). HBV infection can lead to variable clinical outcomes, ranging from self-limiting acute hepatitis to active chronic hepatitis, cirrhosis and hepatocellular carcinoma. The present study characterizes HBV strains circulating among patients with acute (AHB) and chronic HBV infection (CHB). Among a total of 653 HBsAg positive cases, 40 manifested acute infection. After sequencing the surface(S), basal core promoter/pre-core(BCP/PC) and the X gene regions, phylogenetic tree was constructed using MEGA4 by neighbor-joining method. Statistical robustness was established with bootstrap analysis. Nucleotide diversity was determined by Shannon entropy per site using the Entropy program of the Los Alamos National Laboratories. Analyses of acute patients revealed that HBV/D2 is the major circulating sub-genotype and commonly associated with sexual promiscuity and the age group between15-30 years. Comparison of AHB and CHB patients revealed that HBeAg positivity, ALT levels and genotype D were significantly high in AHB, whereas CHB patients were predominantly male, had a high viral load, and were commonly associated with genotype C. The frequencies of mutations in the S, BCP/PC, and X gene were low in AHB as compared to CHB. Drug resistant mutations were not detectable in the polymerase gene of AHB. Average nucleotide diversity in AHB was considerably low as compared to CHB. Further, the highest average ΔH (average difference in entropy between chronic and acute infection) was observed in the BCP/PC region implying that this region was most vulnerable to mutations upon HBV persistence, especially in case of genotype C. Additionally, among all substitutions, the A1762T and G1764A BCP mutations were the strongest indicators of chronicity. In conclusion, the study exhibits a general portrait of HBV strains circulating among acute hepatitis B patients in Eastern India and their

  12. Different controls of tropical cyclone activity in the Eastern Pacific for two types of El Niño

    NASA Astrophysics Data System (ADS)

    Boucharel, Julien; Jin, Fei-Fei; Lin, I. I.; Huang, Hsiao-Ching; England, Matthew H.

    2016-02-01

    The El Niño-Southern Oscillation (ENSO) is known to have different modes of expression, characterized by different dynamics and spatial anomalies patterns: the Eastern Pacific (EP) and Central Pacific (CP) El Niño. The main region of influence of the former is located in the Eastern Pacific, while CP events have a stronger signature of ocean/climate anomalies in the Central West Pacific. This leads to distinctive oceanic and atmospheric signatures that likely have different influences on tropical cyclone (TC) activity in the Eastern Pacific, the second most active region in the world. In this study we investigate the respective role of oceanic and atmospheric conditions on TC formation and intensification in the Eastern Pacific associated with these two flavors of ENSO. We find that the oceanic control, through meridional redistribution of subsurface heat, is the main driver of TC activity during the hurricane season following EP events. In contrast, atmospheric conditions tend to be destructive to TC intensification after those events. The altered atmospheric circulation, in particular the reduction of vertical wind shear and the increase in relative humidity, tends to be more influential in controlling TC activity post CP events. However, unlike for subsurface heat, these changes in atmospheric conditions are not statistically distinct between these two ENSO flavors—although they are consistent across all atmospheric data sets tested. Overall, unlike after EP El Niño events, the hurricane season activity following a CP event is not significantly different from neutral or even La Niña years.

  13. Late Quaternary geomorphic history of a glacial landscape - new sedimentary and chronological data from the Cordillera de Cochabamba (Bolivia)

    NASA Astrophysics Data System (ADS)

    May, J.-H.; Preusser, F.; Zech, R.; Ilgner, J.; Veit, H.

    2009-04-01

    Throughout the Central Andes, glacial landscapes have long been used for the reconstruction of Late Quaternary glaciations and landscape evolution. Much work has focused on the Andes in Peru, Chile and the Bolivian Altiplano, whereas relatively little data has been published on glaciation history in the eastern Andean ranges and slopes. Even less is known with regard to the postglacial evolution of these glacial landscapes. In the Cordillera de Cochabamba (Bolivia), local maximum advances probably peaked around 20-25 ka BP and were followed by significant readvances between ~12-16 ka BP. This generally points to temperature controlled maximum glacial advances along the humid eastern slopes of the Central Andes, which is supported by glacier-climate-modelling studies. However, most studies include only marginal information with regard to the complex geomorphic and sedimentary situation in the Cordillera de Cochabamba. Furthermore, the chronological results are afflicted with several methodological uncertainties inherent to surface exposure dating and call for application of alternative, independent age dating methods. Therefore this study aims at i) documenting and interpreting the complex glacial geomorphology of the Huara Loma valley in the Cordillera de Cochabamba (Bolivia), ii) analyzing the involved units of glacial sediments, and iii) improving the chronological framework by applying optically stimulated luminescence (OSL) and radiocarbon dating (14C). For this purpose, geomorphic mapping was combined with field documentation of sedimentary profiles. The involved sediments were subject to geochemical and mineralogical analysis in order to deduce information on their erosional and weathering histories. In addition, the interpretation of OSL ages from glacial and proglacial sediments integrated several methodological procedures with regard to sample preparation and statistical analysis of the measurements in order to increase the degree of confidence. These

  14. Chemical Defense of the Eastern Newt (Notophthalmus viridescens): Variation in Efficiency against Different Consumers and in Different Habitats

    PubMed Central

    Marion, Zachary H.; Hay, Mark E.

    2011-01-01

    Amphibian secondary metabolites are well known chemically, but their ecological functions are poorly understood—even for well-studied species. For example, the eastern newt (Notophthalmus viridescens) is a well known secretor of tetrodotoxin (TTX), with this compound hypothesized to facilitate this salamander's coexistence with a variety of aquatic consumers across the eastern United States. However, this assumption of chemical defense is primarily based on observational data with low replication against only a few predator types. Therefore, we tested the hypothesis that N. viridescens is chemically defended against co-occurring fishes, invertebrates, and amphibian generalist predators and that this defense confers high survivorship when newts are transplanted into both fish-containing and fishless habitats. We found that adult eastern newts were unpalatable to predatory fishes (Micropterus salmoides, Lepomis macrochirus) and a crayfish (Procambarus clarkii), but were readily consumed by bullfrogs (Lithobates catesbeianus). The eggs and neonate larvae were also unpalatable to fish (L. macrochirus). Bioassay-guided fractionation confirmed that deterrence is chemical and that ecologically relevant concentrations of TTX would deter feeding. Despite predatory fishes rejecting eastern newts in laboratory assays, field experiments demonstrated that tethered newts suffered high rates of predation in fish-containing ponds. We suggest that this may be due to predation by amphibians (frogs) and reptiles (turtles) that co-occur with fishes rather than from fishes directly. Fishes suppress invertebrate consumers that prey on bullfrog larvae, leading to higher bullfrog densities in fish containing ponds and thus considerable consumption of newts due to bullfrog tolerance of newt chemical defenses. Amphibian chemical defenses, and consumer responses to them, may be more complex and indirect than previously appreciated. PMID:22164212

  15. 'They have embraced a different behaviour': transactional sex and family dynamics in eastern Congo's conflict.

    PubMed

    Maclin, Beth; Kelly, Jocelyn; Kabanga, Justin; VanRooyen, Michael

    2015-01-01

    The decades-long conflict in eastern Democratic Republic of the Congo (DRC) has resulted in major changes to local economies, strained social networks and insecurity. This environment forces many to pursue unconventional and, at times, socially stigmatised avenues for income. This paper explores the ways in which individuals in eastern DRC engage in, and are affected by, the commoditisation of sex within the context of decades of violent conflict. Focus group discussions conducted with men and women in 2009-2010 highlight how the war in the region has placed individuals, particularly women, in dire economic circumstances, while also changing their roles within families. In the face of severe poverty, women and girls may choose to engage in transactional sex in order to support themselves and their families. Discussants detailed how engaging in transactional sex due to an economic imperative has nonetheless damaged women's relationships with family members between spouses as well as parents and their children through breach of trust and failure to provide. These focus group discussions elucidate how transactional sex is both a symptom of, and a catalyst for, changes within family dynamics in eastern DRC.

  16. Isotopic evolution of the idaho batholith and Challis intrusive province, Northern US Cordillera

    USGS Publications Warehouse

    Gaschnig, R.M.; Vervoort, J.D.; Lewis, R.S.; Tikoff, B.

    2011-01-01

    The Idaho batholith and spatially overlapping Challis intrusive province in the North American Cordillera have a history of magmatism spanning some 55 Myr. New isotopic data from the ???98 Ma to 54 Ma Idaho batholith and ???51 Ma to 43 Ma Challis intrusions, coupled with recent geochronological work, provide insights into the evolution of magmatism in the Idaho segment of the Cordillera. Nd and Hf isotopes show clear shifts towards more evolved compositions through the batholith's history and Pb isotopes define distinct fields correlative with the different age and compositionally defined suites of the batholith, whereas the Sr isotopic compositions of the various suites largely overlap. The subsequent Challis magmatism shows the full range of isotopic compositions seen in the batholith. These data suggest that the early suites of metaluminous magmatism (98-87 Ma) represent crust-mantle hybrids. Subsequent voluminous Atlanta peraluminous suite magmatism (83-67 Ma) results primarily from melting of different crustal components. This can be attributed to crustal thickening, resulting from either subduction processes or an outboard terrane collision. A later, smaller crustal melting episode, in the northern Idaho batholith, resulted in the Bitterroot peraluminous suite (66-54 Ma) and tapped different crustal sources. Subsequent Challis magmatism was derived from both crust and mantle sources and corresponds to extensional collapse of the over-thickened crust. ?? The Author 2011. Published by Oxford University Press. All rights reserved.

  17. Travels of the Cache Creek Terrane: a paleomagnetic, geobarometric and 40Ar/ 39Ar study of the Jurassic Fourth of July Batholith, Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Harris, Michael J.; Symons, David T. A.; Blackburn, William H.; Hart, Craig J. R.; Villeneuve, Mike

    2003-02-01

    The Middle Jurassic Fourth of July Batholith and cross-cutting mafic dikes have been studied geochronologically, geobarometrically and paleomagnetically to estimate subsequent tectonic motion of the Cache Creek Terrane (CCT) in the northern Canadian Cordillera. 40Ar/ 39Ar hornblende ages from a granodiorite phase are similar to U-Pb zircon ages and indicate rapid cooling of the batholith upon intrusion, suggesting that the magnetization age is coincident with the 173-Ma crystallization age. Argon ages of biotite from the granodiorite and two mafic dikes have similar ages of ˜165 Ma, which dates cooling through ˜280 °C. Aluminum-in-hornblende geobarometry indicates differential uplift of the batholith across a north-south fault zone along Atlin Lake with >6 km more uplift on its eastern side. Also, the eastern side has been tilted downward to the south-southwest by ˜9°. Combined paleomagnetic data from 20 granitoid and 11 mafic dike sites yield an in situ paleopole at 55°W, 63°N ( dp=5°, dm=5°) and a tilt-corrected paleopole at 81°W, 55°N ( dp=5°, dm=6°). Compared to the 173-Ma reference pole for the North American craton, the tilt-corrected pole suggests a significant southward translation of 16.1±3.7° and a significant clockwise rotation of 107±7°. The translation estimate is similar to the Jurassic Teslin Crossing pluton in the Stikine Terrane, however, the rotation estimate is very different. This could indicate that the Cache Creek Terrane was at a similar latitude of the Stikine Terrane, but the two were not yet amalgamated.

  18. Lack of significant differences in immunity against diphtheria between populations of Eastern and Western regions of Poland.

    PubMed

    Chudnicka, Alina; Walory, Jarosław

    2003-01-01

    Incidents of diphtheria in countries which were formerly part of the Soviet Union (Ukraine, Russia and Belorus) resulted in the need to evaluate thoroughly the effectiveness of preventive vaccination in Poland, especially in the border regions of the country where the biggest migration of population can be observed. The aim of this work was a comparison of the immunity to diphtheria in two geographically different regions of Poland--eastern (Lublin) and western (Zielona Gora) ones. It showed immunoprophylaxis to diphtheria that was implemented on these areas. Diphtheria antitoxin level (IgG) was determined with application of the ELISA method in 1236 (529/707) people. No significant differences were found in the level of antibodies in the groups < 2 years of age and > 19 years of age in people below the protective titre (0.1 IU/ml). The difference occurring in the interval between 2nd and 18th year of life (in western Poland 7.6% and in eastern Poland 16%) may result from different implementation of the vaccination program in these regions (booster doses). Recommendations for vaccination to diphtheria in people over 25 years of age should be implemented especially in the frontier regions of Poland adjoining countries threatened with diphtheria occurrence.

  19. Structural differences between the western and eastern Qiongdongnan Basin: evidence of Indochina block extrusion and South China Sea seafloor spreading

    NASA Astrophysics Data System (ADS)

    Zhang, Cuimei; Wang, Zhenfeng; Sun, Zhipeng; Sun, Zhen; Liu, Jianbao; Wang, Zhangwen

    2013-12-01

    Located at the intersection between a NW-trending slip system and NE-trending rift system in the northern South China Sea, the Qiongdongnan Basin provides key clues for us to understand the proposed extrusion of the Indochina Block along with Red River Fault Zone and extensional margins. In this paper we for the first time systematically reveal the striking structural differences between the western and eastern sector of the Qiongdongnan Basin. Influenced by the NW-trending slip faults, the western Qiongdongnan Basin developed E-W-trending faults, and was subsequently inverted at 30-21 Ma. The eastern sector was dominated by faults with NE orientation before 30 Ma, and thereafter with various orientations from NE, to EW and NW during the period 30-21 Ma; rifting display composite symmetric graben instead of the composite half graben or asymmetric graben in the west. The deep and thermal structures in turn are invoked to account for such deformation differences. The lithosphere of the eastern Qiongdongnan Basin is very hot and thinned because of mantle upwelling and heating, composite symmetric grabens formed and the faults varied with the basal plate boundary. However, the Southern and Northern Uplift area and middle of the central depression is located on normal lithosphere and formed half grabens or simple grabens. The lithosphere in the western sector is transitional from very hot to normal. Eventually, the Paleogene tectonic development of the Qiongdongnan Basin may be summarized into three stages with dominating influences, the retreat of the West Pacific subduction zone (44-36 Ma), slow Indochina block extrusion together with slab-pull of the Proto-South China Sea (36-30 Ma), rapid Indochina block extrusion together with the South China Sea seafloor spreading (30-21 Ma).

  20. On the effect of different aerosol types on surface solar radiation levels over the region of Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Alexandri, Georgia; Georgoulias, Aristeidis K.; Kourtidis, Konstantinos; Meleti, Charikleia; Balis, Dimitris

    2014-05-01

    In this work, we examine the direct effect of different aerosol types on the surface solar radiation (SSR) levels in the region of Eastern Mediterranean. Simulations with the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model were performed using ground and satellite-based data as input. An IDL tool that "feeds" SBDART with the appropriate input data was developed allowing us to simulate SSR with a time step of 1 hour. Level-2 aerosol optical depth, cloud optical depth, cloud fraction, effective droplet radius, cloud top pressure, precipitable water and surface albedo data from MODIS, as well as ozone total column data from Earth Probe TOMS and OMI satellite sensors, coarse resolution cloud data from the ISCCP and single scattering albedo, asymmetry factor and Angström exponent sunphotometric data from the AERONET are used in our radiative transfer simulations. Simulations are performed over selected spots within Eastern Mediterranean for clear, liquid cloud and ice cloud covered skies and for different aerosol types (maritime, dust, anthropogenic, fine-mode natural). The optical properties of aerosols were determined using a combination of satellite, ground-based, model and reanalysis products. The aerosol direct radiative effect is defined as the difference between simulations done with and without the presence of aerosols. This research has been financed by EPAN II and PEP under the national action "Bilateral, multilateral and regional R&T cooperations" (AEROVIS Sino-Greek project).

  1. Offshore-onshore recent tectonic deformations in the eastern Rif and its foreland (Alhoceima-Nador, Morocco)

    NASA Astrophysics Data System (ADS)

    Ruano, Patricia; Galindo-Zaldívar, Jesús; Comas, Menchu; Chalouan, Ahmed; Azzouz, Omar; Jesús Román-Alpiste, Manuel; Pedrera, Antonio; Sanz de Galdeano, Carlos; López-Garrido, Ángel Carlos; Benmakhlouf, Mohamed; Roldán-García, Francisco Javier; Anahnah, Farida; González-Castillo, Lourdes

    2014-05-01

    The Rif Cordillera is formed by the southwestwards emplacement of the internal zones on the African foreland in the western Alboran Sea. However, the recent deformations are driven also by interaction with the NW-SE convergence of the Eurasian and African plates. The eastern Rif and its foreland constitute a key region to study the variability in structure and stresses related to a lateral boundary of this Alpine Cordillera. The continental crust of the Rif thinned toward Alboran Sea. The onshore and offshore area nearby the coast line, between Al Hoceima and Nador are suitable for recent tectonics studies due to the presence of wide Neogene and Quaternary basins that contribute to record the activity of recent structures. Multichannel seismic reflection data obtained along the coast during the GASALB cruise in November 2011, together with available data, allows to characterize the differences of the Rif and forleland Neogene-Quaternary basins. Offshore results are compared with field observations, that detailed cover several areas. In the Rif Cordillera (Al Hoceima area), recent basins open towards the Alboran Sea are formed by the active roughly N-S oriented faults in this seismogenic area. They are mainly normal in onshore area and becomes strike-slip offshore connecting with sinistral Al-Idrisi fault zone. In contrast, in the foreland represented by the Trois Fourches area, onshore N-S faults are inactive and are developed above a very well exposed folded detachment. Paleostress data in this area support the activity of the exhumed low-angle faults with NE-SW extension and a late radial extension. These new data allows underline the different stresses and age of deformation in the Rif and its foreland and support a westward displacement of deformation along recent time. Then, the most active and hence higher seismic hazard along Moroccan coast, also related to possible tsunamogenic faults, are located offshore Alhoceima area.

  2. Microsatellite mutation rates in the eastern tiger salamander (Ambystoma tigrinum tigrinum) differ 10-fold across loci.

    PubMed

    Bulut, Zafer; McCormick, Cory R; Gopurenko, David; Williams, Rod N; Bos, David H; DeWoody, J Andrew

    2009-07-01

    Microsatellites are commonly used for mapping and population genetics because of their high heterozygosities and allelic variability (i.e., polymorphism). Microsatellite markers are generally more polymorphic than other types of molecular markers such as allozymes or SNPs because the insertions/deletions that give rise to microsatellite variability are relatively common compared to nucleotide substitutions. Nevertheless, direct evidence of microsatellite mutation rates (MMRs) is lacking in most vertebrate groups despite the importance of such estimates to key population parameters (e.g., genetic differentiation or theta = 4N (e)micro). Herein, we present empirical data on MMRs in eastern tiger salamanders (Ambystoma tigrinum tigrinum). We conducted captive breeding trials and genotyped over 1,000 offspring at a suite of microsatellite loci. These data on 7,906 allele transfers provide the first direct estimates of MMRs in amphibians, and they illustrate that MMRs can vary by more than an order of magnitude across loci within a given species (one locus had ten mutations whereas the others had none).

  3. Profile of micronucleus frequencies and nuclear abnormalities in different species of electric fishes (Gymnotiformes) from the Eastern Amazon

    PubMed Central

    Melo, Karina Motta; Alves, Ingrid Reale; Pieczarka, Julio Cesar; de Oliveira David, José Augusto; Nagamachi, Cleusa Yoshiko; Grisolia, Cesar Koppe

    2013-01-01

    The frequency of spontaneous micronucleus (MN) formation in fish species needs to be determined to evaluate their usefulness for genotoxic biomonitoring. The definition of a good bioindicator takes into account the current knowledge of its metabolic traits as well as other factors including its feeding behavior and relationship to the environment. In this study, we compared the basal frequencies of micronucleated erythrocytes and nuclear abnormalities (NA) among different species of the fish Order Gymnotiformes (Rhamphichthys marmoratus, Steatogenys elegans, Sternopygus macrurus, Parapteronotus hasemani, Gymnotus mamiraua, Gymnotus arapaima, Brachyhypopomus beebei, Brachyhypopomus n. sp. BENN) sampled in several localities of the Eastern Amazon. A baseline of MN and NA frequency in these fish was determined, enabling the identification of potentially useful species as models for genotoxicity studies. Only one impacted sample collected at a site in the River Caripetuba showed a significant number of NAs, which may be due to the release of wastewater by neighbouring mining industries and by the burnt fuel released by the small boats used by a local community. Our results may provide support for further studies in areas of the Eastern Amazon affected by mining, deforestation and other anthropogenic activities. PMID:24130451

  4. Heavy Metal Pollution Characteristics of Surface Sediments in Different Aquatic Ecosystems in Eastern China: A Comprehensive Understanding

    PubMed Central

    Tang, Wenzhong; Shan, Baoqing; Zhang, Wenqiang; Zhang, Hong; Wang, Lishuo; Ding, Yuekui

    2014-01-01

    Aquatic ecosystems in eastern China are suffering threats from heavy metal pollution because of rapid economic development and urbanization. Heavy metals in surface sediments were determined in five different aquatic ecosystems (river, reservoir, estuary, lake, and wetland ecosystems). The average Cd, Cr, Cu, Ni, Pb, and Zn concentrations were 0.716, 118, 37.3, 32.7, 56.6, and 204 mg/kg, respectively, and the higher concentrations were mainly found in sediment samples from river ecosystems. Cd was the most anthropogenically enriched pollutant, followed by Zn and Pb, indicated by enrichment factors >1.5. According to consensus-based sediment quality guidelines, potential ecological risk indices, and risk assessment codes, all five types of aquatic ecosystems were found to be polluted with heavy metals, and the most polluted ecosystems were mainly rivers. Cd was the most serious pollutant in all five aquatic ecosystems, and it was mainly found in the exchangeable fraction (about 30% of the total Cd concentration, on average). The results indicate that heavy metal contamination, especially of Cd, in aquatic ecosystems in eastern China should be taken into account in the development of management strategies for protecting the aquatic environment. PMID:25268385

  5. Heavy metal pollution characteristics of surface sediments in different aquatic ecosystems in eastern China: a comprehensive understanding.

    PubMed

    Tang, Wenzhong; Shan, Baoqing; Zhang, Wenqiang; Zhang, Hong; Wang, Lishuo; Ding, Yuekui

    2014-01-01

    Aquatic ecosystems in eastern China are suffering threats from heavy metal pollution because of rapid economic development and urbanization. Heavy metals in surface sediments were determined in five different aquatic ecosystems (river, reservoir, estuary, lake, and wetland ecosystems). The average Cd, Cr, Cu, Ni, Pb, and Zn concentrations were 0.716, 118, 37.3, 32.7, 56.6, and 204 mg/kg, respectively, and the higher concentrations were mainly found in sediment samples from river ecosystems. Cd was the most anthropogenically enriched pollutant, followed by Zn and Pb, indicated by enrichment factors >1.5. According to consensus-based sediment quality guidelines, potential ecological risk indices, and risk assessment codes, all five types of aquatic ecosystems were found to be polluted with heavy metals, and the most polluted ecosystems were mainly rivers. Cd was the most serious pollutant in all five aquatic ecosystems, and it was mainly found in the exchangeable fraction (about 30% of the total Cd concentration, on average). The results indicate that heavy metal contamination, especially of Cd, in aquatic ecosystems in eastern China should be taken into account in the development of management strategies for protecting the aquatic environment.

  6. Measurement and modeling of rainfall interception by two differently aged secondary forests in upland eastern Madagascar

    NASA Astrophysics Data System (ADS)

    Prasad Ghimire, Chandra; Adrian Bruijnzeel, L.; Lubczynski, Maciek W.; Ravelona, Maafaka; Zwartendijk, Bob W.; van Meerveld, H. J. (Ilja)

    2017-02-01

    Secondary forests occupy a larger area than old-growth rain forests in many tropical regions but their hydrological functioning is still poorly understood. In particular, little is known about the various components of evapotranspiration in these possibly vigorously regenerating forests. This paper reports on a comparison of measured and modeled canopy interception losses (I) from a semi-mature (ca. 20 years) and a young (5-7 years) secondary forest in the lower montane rain forest zone of eastern Madagascar. Measurements of gross rainfall (P), throughfall (Tf), and stemflow (Sf) were made in both forests for one year (October 2014-September 2015) and the revised analytical model of Gash et al. (1995) was tested for the first time in a tropical secondary forest setting. Overall measured Tf, Sf and derived I in the semi-mature forest were 71.0%, 1.7% and 27.3% of incident P, respectively. Corresponding values for the young forest were 75.8%, 6.2% and 18.0%. The high Sf for the young forest reflects the strongly upward thrusting habit of the branches of the dominant species (Psiadia altissima), which favours funneling of P. The value of I for the semi-mature forest is similar to values reported for old-growth tropical lower montane rain forests elsewhere but I for the younger forest is higher than reported for similarly aged tropical lowland forests. These findings can be explained largely by the prevailing low rainfall intensities and the frequent occurrence of small rainfall events. The revised analytical model was able to reproduce measured cumulative I at the two sites accurately and succeeded in capturing the variability in I associated with the seasonal variability in rainfall intensity, provided that Tf-based values for the average wet-canopy evaporation rates were used instead of values derived with the Penman-Monteith equation.

  7. Differences in essential newborn care at birth between private and public health facilities in eastern Uganda.

    PubMed

    Waiswa, Peter; Akuze, Joseph; Peterson, Stefan; Kerber, Kate; Tetui, Moses; Forsberg, Birger C; Hanson, Claudia

    2015-01-01

    Background In Uganda and elsewhere, the private sector provides an increasing and significant proportion of maternal and child health services. However, little is known whether private care results in better quality services and improved outcomes compared to the public sector, especially regarding care at the time of birth. Objective To describe the characteristics of care-seekers and assess newborn care practices and services received at public and private facilities in rural eastern Uganda. Design Within a community-based maternal and newborn care intervention with health systems strengthening, we collected data from mothers with infants at baseline and endline using a structured questionnaire. Descriptive, bivariate, and multivariate data analysis comparing nine newborn care practices and three composite newborn care indicators among private and public health facilities was conducted. Results The proportion of women giving birth at private facilities decreased from 25% at baseline to 17% at endline, whereas overall facility births increased. Private health facilities did not perform significantly better than public health facilities in terms of coverage of any essential newborn care interventions, and babies were more likely to receive thermal care practices in public facilities compared to private (68% compared to 60%, p=0.007). Babies born at public health facilities received an average of 7.0 essential newborn care interventions compared to 6.2 at private facilities (p<0.001). Women delivering in private facilities were more likely to have higher parity, lower socio-economic status, less education, to seek antenatal care later in pregnancy, and to have a normal delivery compared to women delivering in public facilities. Conclusions In this setting, private health facilities serve a vulnerable population and provide access to service for those who might not otherwise have it. However, provision of essential newborn care practices was slightly lower in private

  8. Late Triassic, arc-related, potassic igneous rocks in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Mortimer, N.

    1986-12-01

    Igneous rocks of Late Triassic age are widespread in the Cordillera of western North America and, except in Wrangellia, consist of subduction-related plutonic and volcanic suites. Many of these, including those in the Stikinia, Quesnellia, Rattlesnake Creek, and Jackson terrenes and in southern California, are clinopyroxene rich and belong to high-potassium and shoshonitic rock series, features that are generally absent from older and younger igneous rocks in the same terranes. The Late Triassic subduction-related rocks are exposed in two discontinuous belts that lie east and west of the Cache Creek terrane in Canada and correlative melange terranes farther south. Stratigraphic and structural data suggest that these belts were spatially separate magmatic arcs in Late Triassic time. Tectonic implications of this analysis include an explanation of Middle Jurassic Cordilleran deformation as the result of collision of the western with the eastern belt, absence of Late Triassic links between Stikinia and Quesnellia, disassociation of Stikinia with terranes in northwestern Nevada, and tentative correlation of the Wallowa (Seven Devils) terrane with Stikinia rather than Wrangellia. *Present address: New Zealand Geological Survey, Department of Scientific and Industrial Research, Private Bag, Dunedin, New Zealand

  9. Spatiotemporal variability and contribution of different aerosol types to the aerosol optical depth over the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Georgoulias, Aristeidis K.; Alexandri, Georgia; Kourtidis, Konstantinos A.; Lelieveld, Jos; Zanis, Prodromos; Pöschl, Ulrich; Levy, Robert; Amiridis, Vassilis; Marinou, Eleni; Tsikerdekis, Athanasios

    2016-11-01

    This study characterizes the spatiotemporal variability and relative contribution of different types of aerosols to the aerosol optical depth (AOD) over the Eastern Mediterranean as derived from MODIS (Moderate Resolution Imaging Spectroradiometer) Terra (March 2000-December 2012) and Aqua (July 2002-December 2012) satellite instruments. For this purpose, a 0.1° × 0.1° gridded MODIS dataset was compiled and validated against sun photometric observations from the AErosol RObotic NETwork (AERONET). The high spatial resolution and long temporal coverage of the dataset allows for the determination of local hot spots like megacities, medium-sized cities, industrial zones and power plant complexes, seasonal variabilities and decadal averages. The average AOD at 550 nm (AOD550) for the entire region is ˜ 0.22 ± 0.19, with maximum values in summer and seasonal variabilities that can be attributed to precipitation, photochemical production of secondary organic aerosols, transport of pollution and smoke from biomass burning in central and eastern Europe and transport of dust from the Sahara and the Middle East. The MODIS data were analyzed together with data from other satellite sensors, reanalysis projects and a chemistry-aerosol-transport model using an optimized algorithm tailored for the region and capable of estimating the contribution of different aerosol types to the total AOD550. The spatial and temporal variability of anthropogenic, dust and fine-mode natural aerosols over land and anthropogenic, dust and marine aerosols over the sea is examined. The relative contribution of the different aerosol types to the total AOD550 exhibits a low/high seasonal variability over land/sea areas, respectively. Overall, anthropogenic aerosols, dust and fine-mode natural aerosols account for ˜ 51, ˜ 34 and ˜ 15 % of the total AOD550 over land, while, anthropogenic aerosols, dust and marine aerosols account ˜ 40, ˜ 34 and ˜ 26 % of the total AOD550 over the sea, based on

  10. Active faulting in the frontal Rif Cordillera (Fes region, Morocco): Constraints from GPS data

    NASA Astrophysics Data System (ADS)

    Chalouan, Ahmed; Gil, Antonio J.; Galindo-Zaldívar, Jesús; Ahmamou, M.'Fedal; Ruano, Patricia; de Lacy, Maria Clara; Ruiz-Armenteros, Antonio Miguel; Benmakhlouf, Mohamed; Riguzzi, Federica

    2014-07-01

    The southern Rif cordillera front, between Fes and Meknes, is formed by the Prerif Ridges, which constitute a thrust and fold belt, in contact with the Saïss foreland basin. Geological evidence and regional GPS network data support recent and active tectonics of this Alpine cordillera, with a top-to-the-S-SW motion with respect to stable Africa. A local non-permanent GPS network was installed in 2007 around Fes to constrain the present-day activity of the mountain front. Six GPS sites are located in the Prerif mountain front (jbel Thratt and jbel Zalarh), the Saïss basin and the foreland constituted by the tabular Middle Atlas. Measurements of the GPS network in 2007, 2009 and 2012, over a five year span, seem to indicate that this region is tectonically active and is subjected to significant horizontal motions: (i) a regional displacement toward the SW with respect to stable Africa, showing an average rate of 2 mm/yr; (ii) a southwestward convergent motion between the jbel Thratt with respect to the Saïss basin and the eastern Zalarh ridge, with an average rate of about 4 mm/yr; and (iii) moderate NNE-SSW divergent dextral motion between the Saïss basin and the northern front of the tabular Middle Atlas with an average rate of about 1-2 mm/yr. The regional southwestward motion is related to the activity of the NE-SW sinistral North Middle Atlas-Kert fault zone, which follows the Moroccan Hot Line. Convergence between the Prerif ridges, located at the southern edge of the Rif, and the Saïss basin is accommodated by ENE-WSW striking northward dipping reverse sinistral faults and south vergent folds. In addition, increasing deformation toward the western ridges is in agreement with the stepped mountain front and the development of the arched structures of the Prerif ridges. Normal faults located south of the Saïss basin are responsible for local extension. Whereas the most active deformation occurs in the southern front of the jbel Thratt near Fes, the Sa

  11. Evaluating processes and rates of surface denudation at the Eastern Altiplano margin, Bolivia

    NASA Astrophysics Data System (ADS)

    Hippe, Kristina; Kober, Florian; Zeilinger, Gerold; Ivy-Ochs, Susan; Kubik, Peter; Maden, Colin; Wieler, Rainer

    2010-05-01

    For the Andes Mountains, it has been hypothesized that variations in climate govern variations in erosional intensity that acts as a first-order control on topographic evolution [1]. However, to test these geodynamic models the erosional history of the mountains has to be quantified independently. While absolute erosion rates are known for the Eastern and Western Cordillera, few data exists on erosional processes and rates on the large, internally drained, high-elevation Altiplano plateau. We investigate the Late Quaternary erosional history of the eastern Altiplano based on paired terrestrial cosmogenic nuclide analyses (10Be and 26Al). The Eastern margin of the Bolivian Altiplano is a flat, low-relief landscape with erosion dominated by diffusive hillslope processes and eolian processes. Low precipitation with a strong interannual variability causes episodic fluvial transport of sediment in often small, ephemeral channels. For 13 river sediment samples collected from catchments along the Altiplano margin, catchment wide denudation (CWD) rates have been obtained by 10Be and 26Al. CWD rates based on 10Be are very low and vary between 0.003 to 0.026 mm/yr, with an integration time of 24-230 ky. 26Al data indicate also low, though slightly higher single CWD rates between 0.004 to 0.032 mm/yr. In combination with 10Be, this suggests a complex exposure history with a significant component of sediment storage. These results agree with geomorphological observations of (a) very low slopes, (b) low relief and (c) transient river channels that might account for locally and/or temporarily ineffective erosional and transport processes on the eastern Altiplano. Inter-catchment comparison shows a positive correlation between CWD rates and geomorphometric catchment parameters, but also further influence by lithology and anthropogenic interferences. The slow and complex erosion transport processes on the Altiplano differ significantly from those of the neighbouring Rio La Paz

  12. Late Jurassic plutonism in the southwest U.S. Cordillera

    USGS Publications Warehouse

    Barth, A.P.; Wooden, J.L.; Howard, K.A.; Richards, J.L.

    2008-01-01

    Although plate reconstructions suggest that subduction was an approximately steady-state process from the mid-Mesozoic through the early Tertiary, recent precise geochronologic studies suggest highly episodic emplacement of voluminous continental-margin batholiths in the U.S. Cordillera. In central and southern California and western Arizona, major episodes of batholithic magmatism are known to have occurred in Permian-Triassic, Middle Jurassic, and late Early to Late Cretaceous time. However, recent studies of forearc-basin and continental-interior sediments suggest that Late Jurassic time was probably also a period of significant magmatism, although few dated plutons of this age have been recognized. We describe a belt of Late Jurassic plutonic and hypabyssal rocks at least 200 km in length that extends from the northwestern Mojave Desert through the Transverse Ranges. The belt lies outboard of both the voluminous Middle Jurassic arc and the ca. 148 Ma Independence dike swarm at these latitudes. The plutons include two intrusive suites emplaced between 157 and 149 Ma: a calc-alkaline suite compositionally unlike Permian-Triassic and Middle Jurassic mon-zonitic suites but similar to Late Cretaceous arc plutons emplaced across this region, and a contemporaneous but not comagmatic alkaline suite. The Late Jurassic was thus a time of both tectonic and magmatic transitions in the southern Cordillera. ?? 2008 The Geological Society of America.

  13. An autochthonous geological model for the eastern Andes of Ecuador

    NASA Astrophysics Data System (ADS)

    Pratt, Warren T.; Duque, Pablo; Ponce, Miguel

    2005-04-01

    collision of an oceanic terrane(s) with the South American continent. Young fault movements have subsequently juxtaposed different structural levels through the Cordillera Real orogen.

  14. Ethno-botanical survey of edible wild fruits in Benguet, Cordillera administrative region, the Philippines

    PubMed Central

    Chua-Barcelo, Racquel Tan

    2014-01-01

    Objective To conduct a survey on the common name/s, traditional uses and cultural importance of the edible wild fruits in different municipalities of Benguet, Cordillera administrative region. Methods Interviews using questionnaires with barangay leaders and indigenous people were conducted with 176 key informants from June 2011 to July 2013. Results A total of 36 fruit species were found in different municipalities of Benguet. These fruit species belong to 27 genera and 20 families. Among the 13 municipalities of Benguet, Kibungan has the highest number of species. There are many uses of wild fruits which ranged from food (snack/dessert/table food), forage (especially for birds, monkeys and wild animals such as cloud rat and grass eaters), offertory, processed/preserved (as jam, jellies, candies, juice and wine), condiment or ingredient (for cooking), source of dye or ink, decoration (to garnish food) and as medicine to common ailments or health problems. Based on the inventory and calculated cultural importance index, Garcinia binucao (balokok) belonging to Clusiaceae is the most abundant fruit, hence it is the commonly used fruit for various purposes such as food, forage, processing/preservation and condiment/ingredient; Vaccinium myrtoides (ayusip) for offerings and as source of dye/ink; Saurauia elegans (uyok) for decoration, and, Antidesma bunius (bugnay) for medicine. Conclusions Benguet province in the Cordillera region provides a diversity of edible wild fruits. The data gathered from the study signifies that collection, processing and utilization of edible wild fruits are still part of the daily activities of the people in Benguet. PMID:25183144

  15. Occurrence and trends of eastern and central Pacific El Niño in different reconstructed SST data sets

    NASA Astrophysics Data System (ADS)

    Diamond, Michael S.; Bennartz, Ralf

    2015-12-01

    Interest in El Niño diversity has increased in the past decade, with much attention given to the hypothesis that there exist distinct eastern Pacific and central Pacific (CP) types. It is well known that classification systems in the literature differ, sometimes dramatically, by methodology. We test to what extent differences may occur due to the use of different sea surface temperature (SST) reconstructions, focusing on the newly released version 4 of the Extended Reconstructed Sea Surface Temperature (ERSST) data set, two earlier versions of the ERSST data set, and an independent data set, Hadley Centre Global Sea Ice and Sea Surface Temperature (HadISST). The updated ERSST data set identifies more CP El Niños than the two older versions of ERSST and HadISST. Classification differences occur throughout the entire record rather than being restricted to the early period. We explore the potential influence of SST data set choice on the study of El Niño diversity impacts using precipitation anomalies in the western United States.

  16. Slab flattening, dynamic topography and normal faulting in the Cordillera Blanca region (northern Peru)

    NASA Astrophysics Data System (ADS)

    Margirier, A.; Robert, X.; Laurence, A.; Gautheron, C.; Bernet, M.; Simon-Labric, T.; Hall, S. R.

    2015-12-01

    Processes driving surface uplift in the Andes are still debated and the role of subduction processes as slab flattening on surface uplift and relief building in the Andes is not well understood. Some of the highest Andean summits, the Cordillera Blanca (6768 m) and the Cordillera Negra (5187 m), are located above a present flat subduction zone (3-15°S), in northern Peru. In this area, both the geometry and timing of the flattening of the slab are well constrained (Gutscher et al., 1999; Rosenbaum et al., 2005). This region is thus a perfect target to explore the effect of slab flattening on the Andean topography and uplift. We obtained new apatite (U-Th)/He and fission-track ages from three vertical profiles located in the Cordillera Blanca and the Cordillera Negra. Time-temperature paths obtained from inverse modeling of the thermochronological data indicates a Middle Miocene cooling for both Cordillera Negra profiles. We interpret it as regional exhumation in the Cordillera Occidental starting in Middle Miocene, synchronous with the onset of the subduction of the Nazca ridge (Rosenbaum et al., 2005). We propose that the Nazca ridge subduction at 15 Ma and onset of slab flattening in northern Peru drove regional positive dynamic topography and thus enhanced exhumation in the Cordillera Occidental. This study provides new evidence of the impact subduction processes and associated dynamic topography on paleogeography and surface uplift in the Andes.

  17. Time and mode of exhumation of the Cordillera Blanca batholith (Peruvian Andes)

    NASA Astrophysics Data System (ADS)

    Margirier, Audrey; Audin, Laurence; Robert, Xavier; Herman, Frédéric; Ganne, Jérôme; Schwartz, Stéphane

    2016-08-01

    The Cordillera Blanca batholith (12-5 Myr) forms the highest Peruvian summits and builds the footwall of the Cordillera Blanca normal fault (CBNF). Even if several models have been proposed, the processes driving both the exhumation of the Cordillera Blanca and extensional deformation along the CBNF are still debated. Here we quantify the emplacement depth and exhumation of the batholith of the northern Peru arc from the late Miocene to present. Based on a compilation of crystallization ages and new thermobarometry data in the Cordillera Blanca batholith, we propose that the batholith was emplaced at a depth of ~3 km in successive sills from 14 to 5 Ma. By contrast, the younger rocks exposed at the surface were emplaced the deepest (i.e., ~6 km) and are located close to the CBNF, suggesting post 5 Ma tilting. Furthermore, a formal inversion of the thermochronologic data indicates an increase of the exhumation rates in the Cordillera Blanca during the Quaternary. The higher predicted exhumation rates correlate with areas of high relief, both in the northern and central part of the Cordillera Blanca, suggesting that Quaternary valley carving by glaciations have a significant impact on the latest stage of the Cordillera Blanca exhumation (2-0 Ma).

  18. A new climate and glacier baseline for the Cordillera Vilcanota, Peru, reduces critical information gaps

    NASA Astrophysics Data System (ADS)

    Salzmann, Nadine; Huggel, Christian; Rohrer, Mario; Silverio, Walter; Mark, Bryan G.; Cochachin, Alejo; Suarez, Wilson; Giráldez, Claudia

    2013-04-01

    The Cordillera Vilcanota in the Southern Peruvian Andes is the second largest ice-covered Cordillera in Peru (after the Cordillera Blanca) and serves for the Cusco Region as a temporary water storage for fresh-water and hydropower generation and irrigation. Despite the Cordillera Vilcanota's size and socio-economic relevance, there has so far no comprehensive baseline data been available for climate and glacier evolution. In the framework of two jointly launched -Peruvian-Swiss climate change impact and adaptation programs (Climate Change Adaptation Programm - PACC; Glacier Change Adaptation and Desaster Risk Reduction Programm - Glacier 513) significant efforts have been undertaken and are on the way to create a climate, glacier and hazard baseline for the Cordillera Vilcanota. Because of the remoteness of the area and the scarcity of available data, multiple sources such as climate stations, climate reanalysis and satellite data have been collected, processed and analyzed. Based on our data, we found only marginal glacier changes between 1962 and 1985, but a massive ice loss since 1985 (about 30% of area and about 45% of volume). These high numbers corroborate studies from other glacierized cordilleras in Peru. The climate data show overall a moderate increase in air temperature, and mostly weak and not significant trends for precipitation sums, which probably cannot fully explain the observed substantial ice loss. The likely increase of specific humidity in the upper troposphere, where the glaciers are located, probably played a major role in the observed massive of the Cordillera Vilcanota over the past decades. The mass balance measurements initiated in 2010 on two glaciers of the Cordillera Vilcanota, and the climate station installed in 2011 on one of the glaciers, preliminarily indicate that ice loss (in water equivalent) is clearly lower that in the Cordillera Blanca. In the near future the data will provide new and important insights on climate and

  19. Sources and pathways of stream generation in tropical proglacial valleys of the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Gordon, Ryan P.; Lautz, Laura K.; McKenzie, Jeffrey M.; Mark, Bryan G.; Chavez, Daniel; Baraer, Michel

    2015-03-01

    Tropical glaciers supply approximately half of dry-season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows and other proglacial geomorphic features. A better understanding of the hydrogeology of alpine groundwater, including sources, storage zones, and the locations and magnitudes of contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrologic budget, and for our ability to make predictions about future water resources as glaciers retreat. This field study focuses on two high-elevation meadows in valleys of the Cordillera Blanca, in headwaters and mid-valley locations. Tracer measurements of stream and spring discharge and groundwater-surface water exchange were combined with synoptic sampling of water isotopic and geochemical composition in order to characterize and quantify contributions to streamflow from different groundwater reservoirs. At the headwaters site, groundwater supplied approximately half of stream discharge from a small meadow, with most originating in an alluvial fan adjacent to the meadow and little (6%) from the meadow itself; however, at the mid-valley site, where meadows are extensive, local groundwater has a large impact on streamflow and chemistry through large net contributions to discharge and turnover of surface water due to gross exchanges with groundwater. At the mid-valley site, stream discharge increased by 200 L s-1 (18% of average discharge) over 1.2 km as it descended a moraine between two meadows. Such valley-crossing moraines, which create significant steps in the down-valley slope, are likely locations of substantial groundwater contribution to streams.

  20. Guerrero terrane of Mexico: Its role in the Southern, Cordillera from new geochemical data

    NASA Astrophysics Data System (ADS)

    Centeno-García, Elena; Ruíz, Joaquín; Coney, Peter J.; Patchett, P. Jonathan; Ortega-Gutiérrez, Fernando

    1993-05-01

    The Guerrero terrane makes up most of the western part of Mexico, is one of the largest terranes of the North American Cordillera, and is characterized by an Upper Jurassic-Lower Cretaceous volcanic-sedimentary sequence of are affinity. Metamorphic rocks that crop out in the western area of the terrane (Arteaga complex) may represent its basement. They are mostly composed of terrigenous sediments (Varales Formation) with minor basaltic pillow lavas, chert, tuff, and limestone. Initial ɛNd values (+13) and rare earth element (REE) values for pillow lavas of the Arteaga complex are characteristic of mid-ocean ridge basalts (MORB). In contrast, the Varales Formation sedimentary rocks from the Arteaga complex have negative initial ɛNd (-6.2 and -7.2) and are enriched in light REEs. These data indicate that the sediments of the Varales Formation were supplied from an evolved continental crust. The overlying Jurassic(?)-Cretaceous arc-related rocks have initial ɛNd (+7.9 to +3.9) and REE patterns similar to those of evolved intraoceanic island arcs. These data show that the evolution of the Guerrero terrane had an early pre-Cretaceous(?) stage, which consisted of an oceanic crust receiving sediments from a continental source, and a Cretaceous stage, which was the development of an island arc.The oceanic-continental isotopic signature of the Arteaga complex is different from other western North American Cordilleran terranes (e.g., Alexander, Wrangelfia) that are more completely "oceanic" in affinity. Nevertheless, the extensive Jurassic(?).Cretaceous arc represents additions of juvenile material to the western North American Cordillera.

  1. An enigmatic frog of the genus Atelopus (Family Bufonidae) from Parque Nacional Chirripó, Cordillera de Talamanca, Costa Rica.

    PubMed

    Savage, Jay M; Bolaños, Federico

    2009-01-01

    A distinctive new species of Atelopus is described from Parque Nacional Chirrip6 Grande, Cordillera de Talamanca (3,400-3,500 m). It closely resembles populations of the Atelopus ignescens complex from the Andes of northern Ecuador and southern Colombia. It differs most significantly from these frogs in the pattern of spiculae and coni development on the throat, chest, hands and feet. The Costa Rican species appears to be an outlier of the complex inexplicably separated geographically from its nearest allies by an over land distance of about 1,600 km.

  2. Western honeybee drones and workers (Apis mellifera ligustica) have different olfactory mechanisms than eastern honeybees (Apis cerana cerana).

    PubMed

    Woltedji, Dereje; Song, Feifei; Zhang, Lan; Gala, Alemayehu; Han, Bin; Feng, Mao; Fang, Yu; Li, Jianke

    2012-09-07

    The honeybees Apis mellifera ligustica (Aml) and Apis cerana cerana (Acc) are two different western and eastern bee species that evolved in distinct ecologies and developed specific antennal olfactory systems for their survival. Knowledge of how their antennal olfactory systems function in regards to the success of each respective bee species is scarce. We compared the antennal morphology and proteome between respective sexually mature drones and foraging workers of both species using a scanning electron microscope, two-dimensional electrophoresis, mass spectrometry, bioinformatics, and quantitative real-time polymerase chain reaction. Despite the general similarities in antennal morphology of the drone and worker bees between the two species, a total of 106 and 100 proteins altered their expression in the drones' and the workers' antennae, respectively. This suggests that the differences in the olfactory function of each respective bee are supported by the change of their proteome. Of the 106 proteins that altered their expression in the drones, 72 (68%) and 34 (32%) were overexpressed in the drones of Aml and Acc, respectively. The antennae of the Aml drones were built up by the highly expressed proteins that were involved in carbohydrate metabolism and energy production, molecular transporters, antioxidation, and fatty acid metabolism in contrast to the Acc drones. This is believed to enhance the antennal olfactory functions of the Aml drones as compared to the Acc drones during their mating flight. Likewise, of the 100 proteins with expression changes between the worker bees of the two species, 67% were expressed in higher levels in the antennae of Aml worker contrasting to 33% in the Acc worker. The overall higher expressions of proteins related to carbohydrate metabolism and energy production, molecular transporters, and antioxidation in the Aml workers compared with the Acc workers indicate the Aml workers require more antennal proteins for their olfactory

  3. Proglacial Groundwater Flux and Storage in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Chavez, D.; McKenzie, J. M.; Baraer, M.; Mark, B. G.

    2012-12-01

    As tropical glaciers continue to rapidly retreat in the Cordillera Blanca, Peru, dry-season water resources are becoming more dependent on groundwater baseflow. Therefore, understanding the flux and storage of proglacial groundwater is necessary to forecast how groundwater storage can offset decreasing water resources. Recent studies of the Rio Santa Watershed, which drains the western slopes of the Cordillera Blanca, have identified that groundwater is the largest contributor to outflow from many watersheds during the dry season and that the flux of groundwater is temporarily available (< 4years). These groundwater estimates are based on chemical mass balance models that use hydrochemical and isotopic results primarily from surface water samples and stream discharge measurements. Although effective, this approach is limited by the absence of data from proglacial aquifers. In July, 2012, we installed six groundwater monitoring wells to a maximum depth of 6 m in two proglacial valleys in the Cordillera Blanca. For each well, water samples were collected for hydrochemical and isotopic analysis, slug-tests were conducted to measure hydraulic conductivity, and water levels were continuously monitored using pressure transducers. In both valleys we observed an upper layer of clay to silt sized glaciolacustrine material at each drill site. This layer was typically less than 5 m in thickness and had a low hydraulic conductivity (< 10-7 m/s). Underlying the clay layer were water bearing units of course material (either well-sorted sand/gravel or talus deposits) with an average hydraulic conductivity of 10-5 m/s. Additionally numerous discontinuous sand lenses and localized glaciofluvial gravel deposits were observed within the clay layer. The glaciolacustrine deposits behave as confining units that were capable of generating localized artesian conditions in the coarse grain units. The occurrence of the clay units adjacent to the main stream channels suggests that the

  4. Winter effect on soil microorganisms under different tillage and phosphorus management practices in eastern Canada.

    PubMed

    Shi, Yichao; Lalande, Roger; Hamel, Chantal; Ziadi, Noura

    2015-05-01

    Determining how soil microorganisms respond to crop management systems during winter could further our understanding of soil phosphorus (P) transformations. This study assessed the effects of tillage (moldboard plowing or no-till) and P fertilization (0, 17.5, or 35 kg P·ha(-1)) on soil microbial biomass, enzymatic activity, and microbial community structure in winter, in a long-term (18 years) corn (Zea mays L.) and soybean (Glycine max L.) rotation established in 1992 in the province of Quebec, Canada. Soil samples were collected at 2 depths (0-10 and 10-20 cm) in February 2010 and 2011 after the soybean and the corn growing seasons, respectively. Winter conditions increased the amounts of soil microbial biomasses but reduced the overall enzymatic activity of the soil, as compared with fall levels after corn. P fertilization had a quadratic effect on the amounts of total, bacterial, arbuscular mycorrhizal fungi phospholipid fatty acid markers after corn but not after soybean. The soil microbial community following the soybean and the corn crops in winter had a different structure. These findings suggest that winter conditions and crop-year could be important factors affecting the characteristics of the soil microbial community under different tillage and mineral P fertilization.

  5. Substance abuse In Middle Eastern adolescents living in two different countries: spiritual, cultural, family and personal factors.

    PubMed

    Badr, Lina Kurdahi; Taha, Asma; Dee, Vivien

    2014-08-01

    It is estimated that the percentage of students using illicit substances by sixth grade has tripled over the last decade not only in developed countries but in developing countries as well probably due to the transition to a more Western society. Although much has been done to understand the mechanisms underlying substance abuse, few studies have been conducted with minority ethnic and religious groups such as Middle Eastern Youth. The primary goal of this study was to determine whether there are differences in factors contributing to substance abuse in adolescents from Lebanon versus the U.S.A. and to decipher the role of spirituality, religion, and culture among other factors that may influence substance abuse. A correlational cross-sectional design was used with adolescents living in two different countries: Los Angeles, California and Beirut, Lebanon. Muslim adolescents had significantly less rates of alcohol and substance use than Christians in both Lebanon and Los Angeles. More years lived in the U.S.A. increases the likelihood of abuse for both Muslims and Christians. Attachment to God and family was negatively associated with substance abuse. These results among others facilitate a better understanding of the influence of culture, religion, family and personal factors on substance abuse. Culturally sensitive interventions could benefit from the findings of this pilot study.

  6. Distribution of arbuscular mycorrhizal fungi associated with different land use systems of Arunachal Pradesh of Eastern Himalayan region.

    PubMed

    Bordoloi, A; Nath, P C; Shukla, A K

    2015-10-01

    Arbuscular mycorrhizal fungi are the main component of soil microbial population in most agroecosystems. They forms a close association with more than 80% of the plant species making immobilized mineral nutrients available to the plants in order to sustain normal growth and reproduction. In this study the diversity of mycorrhizal fungi has been examined in seven land use ecosystems of Arunachal Pradesh in Eastern Himalayan region. A total of 24 species of AM fungi belonging to 4 genera viz., Glomus, Scutellospora, Aculospora and Gigaspora were isolated from the soil samples collected from different land use systems. Glomus was the dominant genera and Glomus occulatum was the most abundant species in all the seven land use systems. Total spore number was highly variable among all the land use systems. Species richness was recorded highest in natural forest that maintains a faster nutrient cycle with the highest diversity index. The Jhum fallow land and tea garden has the least number of AM fungal species due to high disturbance of fire and application of fungicides and inorganic fertilizer. Further the plant species composition, particularly the ground vegetation coverage and disturbance level affects the distribution of the AM fungal species. In our study it has been shown that AMF diversity is significantly affected by the land use practices practiced by the people. Hence, the AM fungi isolated from different land use system may be useful in improving the agriculture practices particularly the plantation crops in the region.

  7. Slope deformations in high-mountain regions as observed by InSAR: Examples from the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Frey, Holger; Strozzi, Tazio; Caduff, Rafael; Huggel, Christian; Klimeš, Jan; Vilímek, Vít; Wiesmann, Andreas; Kääb, Andreas; Cochachin, Alejo; Plummer, Stephen

    2016-04-01

    Steep topography, the world's highest concentration of tropical glaciers, numerous glacial lakes and strong seismic activity combined with a densely populated valley bottom in the Rio Santa basin characterize the Cordillera Blanca in Peru. Besides glacier-related processes, a variety of landslide types and processes is present outside the glaciated areas, favoured by the steep terrain, geological conditions, sparse vegetation, intense precipitation, and strong seismicity. This combination of high hazard potentials and vulnerabilities results in a long list of natural disasters. Information on surface displacements is very valuable for early detection of emerging hazard potentials and their assessment. Interferometric processing of SAR data (InSAR) provides the possibility to remotely detect different types of surface displacement processes, also in remote locations where no other monitoring data are available. This contribution, developed under the ESA-funded S:GLA:MO project (sglamo.gamma-rs.ch), shows the potential of InSAR products for hazard assessments and glaciological investigations in high-mountain regions. We present a selection of different surface displacements as observed in the Cordillera Blanca based on InSAR data: a landslide zone near the Rampac Grande village, where in 2009 a landslide caused casualties and property loss; a landslide at the entry of the Santa Cruz Valley, northern Cordillera Blanca, where the displacement history could be reconstructed over five years; surface displacements at the interior moraine slopes surrounding Laguna Palcacocha, a major glacier lake above the city of Huaraz, which are compared to and complemented by geophysical investigations in the field; surface displacements at the moraine damming Laguna Safuna Alta, a glacier lake in the northern part of the Cordillera Blanca; glacier velocities across the entire Cordillera Blanca, revealing ice flow velocities of more than 200 m yr-1 at certain locations at the end of

  8. Net Ecosystem Exchange and Net Biome Productivity of different land use in eastern Germany

    NASA Astrophysics Data System (ADS)

    Grünwald, Thomas; Prescher, Anne-Katrin; Bernhofer, Christian

    2010-05-01

    The carbon (CO2-C) budgets of a managed forest (spruce), grassland and a cropland (crop rotation) have been determined and compared. The sites are part of the Tharandt cluster which features low intersite variability in climate due to the small distances between the sites. This allows the comparison of management effects on the carbon budget of different land use among other things. At the forest site, continuous CO2 flux measurements are available from 1997 to 2008, the common observation period of the grassland and cropland sites was 2005 to 2008. With regard to annual net ecosystem exchange NEE (based on eddy covariance flux measurements), the forest showed the highest net sink (-698 g C m-2 (1999) to -444 g C m-2 (2003)). In contrast the grassland and cropland sites were significantly lower sinks in terms of NEE (-177 g C m-2 (2004) to -62 g C m-2 (2005) and -115 g C m-2 (2005) to -32 g C m-2 (2007 and 2008), respectively). To quantify the net biome productivity (NBP) carbon exports due to thinning or harvest as well as carbon imports due to organic fertilisation are considered besides NEE. Carbon exports and imports change the carbon budget in terms of NBP. At the forest site only the 2002 NBP is a carbon source (+221 g C m-2) due to the thinning in April 2002 when around 43 m3 ha-1 solid wood was removed from the ecosystem. After the thinning the annual NEE is reduced by around 100 g C m-2 until 2007. The grassland NBP alternated between carbon source and sink (+25 g C m-2 (2008) to -28 g C m-2 (2006)) indicating the carbon balance was approximately neutral. Low NEE and NBP values at the grassland site were a consequence of carbon export due to several cuts per year. The NBP of the cropland ecosystem was mainly influenced by the crop type (winter or spring crop) and the application of organic fertiliser (manure) resulting in carbon budgets between +484 g C m-2 (2007) and -89 g C m-2 (2006). The different timing and length of the growing season of winter and

  9. Genetic Characterization of Soybean Rhizobia Isolated from Different Ecological Zones in North-Eastern Afghanistan.

    PubMed

    Habibi, Safiullah; Ayubi, Abdul Ghani; Ohkama-Ohtsu, Naoko; Sekimoto, Hitoshi; Yokoyama, Tadashi

    2017-03-31

    Seventy rhizobial isolates were obtained from the root nodules of two soybean (Glycine max) cultivars: Japanese cultivar Enrei and USA cultivar Stine3300, which were inoculated with different soil samples from Afghanistan. In order to study the genetic properties of the isolates, the DNA sequences of the 16S rRNA gene and symbiotic genes (nodD1 and nifD) were elucidated. Furthermore, the isolates were inoculated into the roots of two soybean cultivars, and root nodule numbers and nitrogen fixation abilities were subsequently evaluated in order to assess symbiotic performance. Based on 16S rRNA gene sequences, the Afghanistan isolates obtained from soybean root nodules were classified into two genera, Bradyrhizobium and Ensifer. Bradyrhizobium isolates accounted for 54.3% (38) of the isolates, and these isolates had a close relationship with Bradyrhizobium liaoningense and B. yuanmingense. Five out of the 38 Bradyrhizobium isolates showed a novel lineage for B. liaoningense and B. yuanmingense. Thirty-two out of the 70 isolates were identified as Ensifer fredii. An Ensifer isolate had identical nodD1 and nifD sequences to those in B. yuanmingense. This result indicated that the horizontal gene transfer of symbiotic genes occurred from Bradyrhizobium to Ensifer in Afghanistan soil. The symbiotic performance of the 14 tested isolates from the root nodules of the two soybean cultivars indicated that Bradyrhizobium isolates exhibited stronger acetylene reduction activities than Ensifer isolates. This is the first study to genetically characterize soybean-nodulating rhizobia in Afghanistan soil.

  10. Phosphorus speciation of sediments from lakes of different tropic status in Eastern China.

    PubMed

    Zhang, Wenqiang; Rong, Nan; Jin, Xin; Li, Jie; Ding, Yuekui; Zhu, Xiaolei; Shan, Baoqing

    2016-04-01

    Information about the chemical composition of phosphorus (P) in sediment is critical for understanding P dynamics and eutrophication in lake ecosystems. Eutrophication as a result of P pollution still persists so we chose to determine the P characteristics of sediments from ten lakes of different trophic status and the relationships between P fractions and environmental factors. The results show that the Standards, Measurements and Testing (SMT) method combined with (31)P-nuclear magnetic resonance ((31)P-NMR) can efficiently show the P characteristics of sediment. Phosphorus concentrations in sediments decreased as the trophic status of the lake improved. Inorganic P (Pi) was the dominant form of total P (TP) in most of the lake sediments and was mainly comprised of HCl-Pi, a stable Pi fraction. Results of (31)P-NMR analysis show that the extracts were dominated by ortho-P (36.4-94.8%) and mono-P (4.0-36.2%), with smaller amounts of diester-P (.6-23.1%), pyro-P (.2-4.4%), and phon-P (.3-.7%). Analysis of the relationships between the P composition and the trophic status of the lakes indicated that the bioavailability of P forms has an influence on the surface water trophic conditions and the health of aquatic ecosystems.

  11. Microbial communities and soil fertility in flood irrigated orchards under different management systems in eastern spain

    NASA Astrophysics Data System (ADS)

    Morugán-Coronado, Alicia; García-Orenes, Fuensanta; Caravaca, Fuensanta; Roldán, Antonio

    2016-04-01

    Unsuitable land management such as the excessive use of herbicides can lead to a loss of soil fertility and a drastic reduction in the abundance of microbial populations and their functions related to nutrient cycling. Microbial communities are the most sensitive and rapid indicators of perturbations in agroecosystems. A field experiment was performed in an orange-trees orchard (Citrus sinensis) to assess the long-term effect of three different management systems on the soil microbial community biomass, structure and composition (phospholipid fatty acids (PLFAs) total, pattern, and abundance). The three agricultural systems assayed were established 30 years ago: herbicides (Glyphosate (N-(phosphonomethyl)glycine) with inorganic fertilizers (H), intensive ploughing and inorganic fertilizers (NPK 15%) (P) and organic farming (chipped pruned branches and weeds, manure from sheep and goats) (O). Nine soil samples were taken from each system. The results showed that the management practices including herbicides and intensive ploughing had similar results on soil microbial properties, while organic fertilization significantly increased microbial biomass, shifted the structure and composition of the soil microbial community, and stimulated microbial activity, when compared to inorganic fertilization systems; thus, enhancing the sustainability of this agroecosystem under semiarid conditions.

  12. Large Scale Deformation of the Western U.S. Cordillera

    NASA Technical Reports Server (NTRS)

    Bennett, Richard A.

    2002-01-01

    Over the past couple of years, with support from NASA, we used a large collection of data from GPS, VLBI, SLR, and DORIS networks which span the Western U.S. Cordillera (WUSC) to precisely quantify present-day large-scale crustal deformations in a single uniform reference frame. Our work was roughly divided into an analysis of these space geodetic observations to infer the deformation field across and within the entire plate boundary zone, and an investigation of the implications of this deformation field regarding plate boundary dynamics. Following the determination of the first generation WUSC velocity solution, we placed high priority on the dissemination of the velocity estimates. With in-kind support from the Smithsonian Astrophysical Observatory, we constructed a web-site which allows anyone to access the data, and to determine their own velocity reference frame.

  13. Large Scale Deformation of the Western U.S. Cordillera

    NASA Technical Reports Server (NTRS)

    Bennett, Richard A.

    2002-01-01

    Over the past couple of years, with support from NASA, we used a large collection of data from GPS, VLBI, SLR, and DORIS networks which span the Westem U.S. Cordillera (WUSC) to precisely quantify present-day large-scale crustal deformations in a single uniform reference frame. Our work was roughly divided into an analysis of these space geodetic observations to infer the deformation field across and within the entire plate boundary zone, and an investigation of the implications of this deformation field regarding plate boundary dynamics. Following the determination of the first generation WUSC velocity solution, we placed high priority on the dissemination of the velocity estimates. With in-kind support from the Smithsonian Astrophysical Observatory, we constructed a web-site which allows anyone to access the data, and to determine their own velocity reference frame.

  14. Large Scale Deformation of the Western US Cordillera

    NASA Technical Reports Server (NTRS)

    Bennett, Richard A.

    2001-01-01

    Destructive earthquakes occur throughout the western US Cordillera (WUSC), not just within the San Andreas fault zone. But because we do not understand the present-day large-scale deformations of the crust throughout the WUSC, our ability to assess the potential for seismic hazards in this region remains severely limited. To address this problem, we are using a large collection of Global Positioning System (GPS) networks which spans the WUSC to precisely quantify present-day large-scale crustal deformations in a single uniform reference frame. Our work can roughly be divided into an analysis of the GPS observations to infer the deformation field across and within the entire plate boundary zone and an investigation of the implications of this deformation field regarding plate boundary dynamics.

  15. Genetic Characterization of Soybean Rhizobia Isolated from Different Ecological Zones in North-Eastern Afghanistan

    PubMed Central

    Habibi, Safiullah; Ayubi, Abdul ghani; Ohkama-Ohtsu, Naoko; Sekimoto, Hitoshi; Yokoyama, Tadashi

    2017-01-01

    Seventy rhizobial isolates were obtained from the root nodules of two soybean (Glycine max) cultivars: Japanese cultivar Enrei and USA cultivar Stine3300, which were inoculated with different soil samples from Afghanistan. In order to study the genetic properties of the isolates, the DNA sequences of the 16S rRNA gene and symbiotic genes (nodD1 and nifD) were elucidated. Furthermore, the isolates were inoculated into the roots of two soybean cultivars, and root nodule numbers and nitrogen fixation abilities were subsequently evaluated in order to assess symbiotic performance. Based on 16S rRNA gene sequences, the Afghanistan isolates obtained from soybean root nodules were classified into two genera, Bradyrhizobium and Ensifer. Bradyrhizobium isolates accounted for 54.3% (38) of the isolates, and these isolates had a close relationship with Bradyrhizobium liaoningense and B. yuanmingense. Five out of the 38 Bradyrhizobium isolates showed a novel lineage for B. liaoningense and B. yuanmingense. Thirty-two out of the 70 isolates were identified as Ensifer fredii. An Ensifer isolate had identical nodD1 and nifD sequences to those in B. yuanmingense. This result indicated that the horizontal gene transfer of symbiotic genes occurred from Bradyrhizobium to Ensifer in Afghanistan soil. The symbiotic performance of the 14 tested isolates from the root nodules of the two soybean cultivars indicated that Bradyrhizobium isolates exhibited stronger acetylene reduction activities than Ensifer isolates. This is the first study to genetically characterize soybean-nodulating rhizobia in Afghanistan soil. PMID:28321006

  16. Comparison of the Eastern and Western Kentucky coal fields (Pennsylvanian), USA-why are coal distribution patterns and sulfur contents so different in these coal fields?

    USGS Publications Warehouse

    Greb, S.F.; Eble, C.F.; Chesnut, D.R.

    2002-01-01

    More than 130 Mt of Pennsylvanian coal is produced annually from two coal fields in Kentucky. The Western Kentucky Coal Field occurs in part of the Illinois Basin, an intercratonic basin, and the Eastern Kentucky Coal Field occurs in the Central Appalachian Basin, a foreland basin. The basins are only separated by 140 km, but mined western Kentucky coal beds exhibit significantly higher sulfur values than eastern Kentucky coals. Higher-sulfur coal beds in western Kentucky have generally been inferred to be caused by more marine influences than for eastern Kentucky coals. Comparison of strata in the two coal fields shows that more strata and more coal beds accumulated in the Eastern than Western Kentucky Coal Field in the Early and Middle Pennsylvanian, inferred to represent greater generation of tectonic accommodation in the foreland basin. Eastern Kentucky coal beds exhibit a greater tendency toward splitting and occurring in zones than time-equivalent western Kentucky coal beds, which is also inferred to represent foreland accommodation influences, overprinted by autogenic sedimentation effects. Western Kentucky coal beds exhibit higher sulfur values than their eastern counterparts, but western Kentucky coals occurring in Langsettian through Bolsovian strata can be low in sulfur content. Eastern Kentucky coal beds may increase in sulfur content beneath marine zones, but generally are still lower in sulfur than mined Western Kentucky coal beds, indicating that controls other than purely marine influences must have influenced coal quality. The bulk of production in the Eastern Kentucky Coal Field is from Duckmantian and Bolsovian coal beds, whereas production in the Western Kentucky Coal Field is from Westphalian D coals. Langsettian through Bolsovian paleoclimates in eastern Kentucky were favorable for peat doming, so numerous low-sulfur coals accumulated. These coals tend to occur in zones and are prone to lateral splitting because of foreland tectonic and

  17. Association between Ambient Air Pollution and Asthma Prevalence in Different Population Groups Residing in Eastern Texas, USA.

    PubMed

    Gorai, Amit Kr; Tchounwou, Paul B; Tuluri, Francis

    2016-03-29

    Air pollution has been an on-going research focus due to its detrimental impact on human health. However, its specific effects on asthma prevalence in different age groups, genders and races are not well understood. Thus, the present study was designed to examine the association between selected air pollutants and asthma prevalence in different population groups during 2010 in the eastern part of Texas, USA.The pollutants considered were particulate matter (PM2.5 with an aerodynamic diameter less than 2.5 micrometers) and surface ozone. The population groups were categorized based on age, gender, and race. County-wise asthma hospital discharge data for different age, gender, and racial groups were obtained from Texas Asthma Control Program, Office of Surveillance, Evaluation and Research, Texas Department of State Health Services. The annual means of the air pollutants were obtained from the United States Environmental Protection Agency (U.S. EPA)'s air quality system data mart program. Pearson correlation analyzes were conducted to examine the relationship between the annual mean concentrations of pollutants and asthma discharge rates (ADR) for different age groups, genders, and races. The results reveal that there is no significant association or relationship between ADR and exposure of air pollutants (PM2.5, and O₃). The study results showed a positive correlation between PM2.5 and ADR and a negative correlation between ADR and ozone in most of the cases. These correlations were not statistically significant, and can be better explained by considering the local weather conditions. The research findings facilitate identification of hotspots for controlling the most affected populations from further environmental exposure to air pollution, and for preventing or reducing the health impacts.

  18. Association between Ambient Air Pollution and Asthma Prevalence in Different Population Groups Residing in Eastern Texas, USA

    PubMed Central

    Gorai, Amit Kr.; Tchounwou, Paul B.; Tuluri, Francis

    2016-01-01

    Air pollution has been an on-going research focus due to its detrimental impact on human health. However, its specific effects on asthma prevalence in different age groups, genders and races are not well understood. Thus, the present study was designed to examine the association between selected air pollutants and asthma prevalence in different population groups during 2010 in the eastern part of Texas, USA.The pollutants considered were particulate matter (PM2.5 with an aerodynamic diameter less than 2.5 micrometers) and surface ozone. The population groups were categorized based on age, gender, and race. County-wise asthma hospital discharge data for different age, gender, and racial groups were obtained from Texas Asthma Control Program, Office of Surveillance, Evaluation and Research, Texas Department of State Health Services. The annual means of the air pollutants were obtained from the United States Environmental Protection Agency (U.S. EPA)’s air quality system data mart program. Pearson correlation analyzes were conducted to examine the relationship between the annual mean concentrations of pollutants and asthma discharge rates (ADR) for different age groups, genders, and races. The results reveal that there is no significant association or relationship between ADR and exposure of air pollutants (PM2.5, and O3). The study results showed a positive correlation between PM2.5 and ADR and a negative correlation between ADR and ozone in most of the cases. These correlations were not statistically significant, and can be better explained by considering the local weather conditions. The research findings facilitate identification of hotspots for controlling the most affected populations from further environmental exposure to air pollution, and for preventing or reducing the health impacts. PMID:27043587

  19. Slab flattening driving regional uplift in the Cordilleras Blanca and Negra, Western Andes

    NASA Astrophysics Data System (ADS)

    Margirier, Audrey; Audin, Laurence; Robert, Xavier; Bernet, Matthias; Gautheron, Cécile

    2015-04-01

    The Andean range topographic evolution is known to have had a strong impact on regional climate by building an orographic barrier that preserved its western flank from the south Atlantic moisture. Even if largely invoked, the impact of subduction processes on the uplift and relief building is not yet well understood in the Andes. The northern Peru is characterized by a present day flat subduction zone (3-15°S), where both the geometry and temporal evolution of the flat-slab are well constrained. The subduction of two buoyant anomalies, the Nazca ridge and the lost Inca plateau controlled the slab flattening. The highest Peruvian peaks in the Cordillera Blanca (6768 m), and the Cordillera Negra (5187 m) are located just above the flat-slab segment. Both ranges trend parallel to the subduction zone and are separated by the NW-SE Rio Santa valley. The Cordillera Blanca batholith emplaced at 8-5 Ma and renders of an abnormal magmatic activity over a planar subduction. This area is a perfect target to explore the impact of slab flattening on the topography and uplift in the Occidental Cordillera of the Andes. We present new AHe and AFT data from three vertical profiles located in both the Cordilleras Blanca and Negra. We compare time-temperature paths obtained from inverse modeling of the thermochronological data with the timing of the slab flattening, the arrival of the Nazca ridge and magmatism. Our thermochronological data evidences a regional exhumation in the Occidental Cordillera from ~10 Ma. We propose that the Nazca ridge subduction below the Occidental Cordillera (11 Ma) and slab flattening (8 Ma) drive the Occidental Cordillera uplift and thus exhumation. We evidence the important contribution of the magmatism in the Cordillera Blanca exhumation and high relief building in the Occidental Cordillera. Our new thermochronological data highlight the control of both the subduction processes and magmatism on the paleogeography and uplift in the Andes. Finally, the

  20. Variations of the Crustal Structure in the Rif Cordillera, N-Morocco from Wide-Angle Seismic Data

    NASA Astrophysics Data System (ADS)

    Gallart, J.; Gil, A.; Diaz, J.; Carbonell, R.; Harnafi, M.; Levander, A.; Palomeras, I.; Cordoba, D.

    2012-12-01

    The Rif Cordillera, located in North Morocco forms, together with the Betic Cordillera, the Gibraltar Arc around the Alboran Sea. This asymmetric curved mountain belt originated during a Miocene continent-continent collision as a result of the westward motion of the Alboran domain between northwest Africa and Iberia. The complexity of the area favored the proposition of diverse tectonic models, poorly constrained by available geophysical data. Previous numerical models that integrate both elevation, geoid and gravity anomalies assuming local isostasy suggest a poorly marked orogenic root beneath the Rif Cordillera, whereas a recent receiver function study from Topo-Iberia project reveals large variations of at least 10 km in crustal thicknesses under northern Morocco, similarly to values obtained in station terms from a Pn tomography. In order to constrain the seismic velocity structure of the Rif Cordillera and to delineate the Moho topography, in October 2011, within the Spanish project RIFSIS complemented by the US-PICASSO one, wide-angle reflection and refraction seismic data were acquired for the first time along two 330 km-length profiles, oriented respectively N-S and E-W. The N-S line was extended northwards by a 70 km long segment in Spain, along the Betics. Southwards, this profile connects with the one recorded in 2010 across the Atlas Mountains (SIMA project), hence delineating a 700 km-long wide-angle seismic transect across the Betic-Rif-Atlas systems. Seismic energy released at 5 shot points was generated by the detonation of 1 TN of explosives and was recorded by ~ 900 Texans stations from the IRIS-PASCAL pool, with an average station spacing of about 750 m. Crustal phases Pg, PcP and PiP and Moho reflected PmP phases are clearly identified in the processed datasets. Preliminary analyses by forward modeling already reveal the existence of major variations in crustal thicknesses, especially along the E-W profile that documents differences of about 20

  1. Sandbox modeling of evolving thrust wedges with different preexisting topographic relief: Implications for the Longmen Shan thrust belt, eastern Tibet

    NASA Astrophysics Data System (ADS)

    Sun, Chuang; Jia, Dong; Yin, Hongwei; Chen, Zhuxin; Li, Zhigang; Shen, Li; Wei, Dongtao; Li, Yiquan; Yan, Bin; Wang, Maomao; Fang, Shaozhi; Cui, Jian

    2016-06-01

    To understand the effects of substantial topographic relief on deformation localization in the seismically active mountains, like the Longmen Shan thrust belt in the eastern Tibet, sandbox experiments were performed based on the framework of the critical taper theory. First, a reference experiment revealed that the critical taper angle was 12° for our experimental materials. Subsequently, different proto wedges (subcritical (6° in taper angle), critical (12°), and supercritical (20°)) were introduced to cover the range of natural topographic relief, and we used two setups: setup A considered only across-strike topographic relief, whereas setup B investigated along-strike segmentation of topography, consist of two adjacent proto wedges. In all experiments, thrust wedges grew by in-sequence accretion of thrust sheets. Setup A revealed an alternating mode of slip partitioning on the accreted thrusts, with large-displacement thrust and small-displacement thrust developing in turn. And contrasting wedge evolutions occurred according to whether the proto wedge was subcritical or critical-supercritical. In setup B, the differential deformation along the strike produced transverse structures such as tear fault and lateral ramp during frontal accretion. The observed tear fault and its associated thrust system resemble the seismogenic fault system of the 2008 Mw7.9 Wenchuan earthquake. Our experimental results could also explain first-order deformation features observed in the Longmen Shan. Consequently, we conclude that topographic features, including topographic relief across the range and along-strike segmentation of topography, contribute significantly to the kinematics and deformation localization in such active mountains.

  2. Impact of different metabolic syndrome classifications on the metabolic syndrome prevalence in a young Middle Eastern population.

    PubMed

    Chedid, Rima; Gannagé-Yared, Marie-Hélène; Khalifé, Simon; Halaby, Georges; Zoghbi, Fernand

    2009-06-01

    The metabolic syndrome (MetS) prevalence in a young Middle Eastern population has never been studied. We studied this prevalence in a randomly selected population of Lebanese students using different MetS classifications. Three hundred eighty-one subjects aged 18 to 30 years were included in the study. Anthropometric and biological parameters (waist circumference [WC], systolic and diastolic blood pressures, fasting plasma glucose, triglycerides, total cholesterol, high-density lipoprotein cholesterol, and homeostasis model assessment [HOMA] index to assess insulin resistance) were measured. Receiver operating characteristic (ROC) curves were generated to determine population-specific cutoff values for MetS parameters and HOMA index. The MetS prevalence was calculated using the National Cholesterol Education Program's Adult Treatment Panel III (ATP-III), the actualized ATP-III, and our cutoffs, either with or without HOMA index as an extra risk factor. The MetS prevalence using the ATP-III and the actualized ATP-III was, respectively, 5.25% and 5.28%. It increased to 9.19% when using our cutoff values and to 12.64% when HOMA index was added. This increase was significant only in men. The identified cutoff values are, for WC, 91 cm in women and 99.5 cm in men and, for HOMA index, 2.32. Among the MetS components, WC was the best MetS predictor, whereas fasting plasma glucose was the poorest. Our study shows that the MetS prevalence in Lebanon is comparable with other countries. In addition, we identified in our population new cutoff points for MetS parameters and HOMA index that allow the detection of a higher number of subjects with the MetS, mainly in the male population.

  3. Reconstructing early Cenozoic topography of the North American Cordillera from authigenic mineral δ18O-Moving beyond Rayleigh distillation

    NASA Astrophysics Data System (ADS)

    Feng, R.; Poulsen, C. J.; Werner, M.

    2012-12-01

    -elevation relationships. In some regions, compensation is not complete, and as a result, ECHAM5-wiso precipitation δ18O does not agree with estimates from a Rayleigh distillation model. For example, in the interior of the northern portion of the cordillera, ECHAM5-wiso predicts high snowfall and lower precipitation δ18O. Because Rayleigh distillation does not account for this, it likely overestimates past elevations by ~2000m. Similarly, along the eastern flanks of the southern cordillera, ECHAM5-wiso simulates energetic convective precipitation, vapor recycling, and higher precipitation δ18O that is not accounted by Rayleigh distillation, it likely underestimates past elevations by ~1000m. In sum, though our results generally support an early Cenozoic north-to-south propagation of high topography in the North American Cordillera, they do not support the underlying assumptions of isotopic fractionation through Rayleigh distillation upon which the elevation reconstruction is based.

  4. New glaciological research projects in the Cordillera Vilcanota - Cusco - Peru

    NASA Astrophysics Data System (ADS)

    Montoya, Nilton; Molina, Edwin; Schauwecker, Simone; Haeberli, Wilfried; Giraldez, Claudia; Drenkhan, Fabian; Huggel, Christian

    2015-04-01

    Tropical glaciers are highly sensitive to alterations in climate and therefore good indicators for global climate change. Glaciers located in Peru represent 71% of all tropical glaciers in the world, and have shown a significant area reduction of about 43% within the last 40 years mainly due to the increase in surface temperature. Tropical glaciers play a particular role as freshwater reservoirs and buffers to river discharge variability and water scarcity within a pronounced wet and dry season. Their monitoring is extraordinarily important but few studies exist on mass balance. The Cordillera Vilcanota, at the origin of the Rio Vilcanota-Urubamba, contains about 25% of all glaciers in Peru. In recent decades, glacier shrinkage has accelerated in this mountain range. Between 1988 and 2010, glacier area was reduced at an annual rate of about 4 km2 (1.1 %) from some 360 km2 to about 270 km2 (25%). A total volume loss of 40-45% (from 17-20 km3 to 9.2-12.4 km3) can be estimated for the period 1962-2006, with an accelerated rate since the 1980s. In 2010/11, first point net mass balance measurements were carried out on Suyuparina glacier and the adjacent Quisoquipina glacier. In 2013, mass balance measurements were reinitiated in the frame of a long-term monitoring campaign. The first year of direct mass balance measurements (stakes and pits) show that ablation is highly influenced by the complex microtopography of the glacier, mainly characterized by the existence of ice cliffs, causing a spatially heterogeneous ablation pattern. There is a large scatter in point mass balance in function of elevation, which makes it difficult to estimate accurately the equilibrium line altitude (ELA) and the annual total glacier mass balance from these point measurements. For the hydrological year 2013/14, stake measurements for sites on the lower part of the glacier varied between +0.2 and -4 m w.e. (water equivalent), while accumulation in the uppermost part of the glacier showed

  5. The plot size effect on soil erosion on rainfed agriculture land under different land uses in eastern Spain

    NASA Astrophysics Data System (ADS)

    Cerdà, A.; Bodí, M. B.; Burguet, M.; Segura, M.; Jovani, C.

    2009-04-01

    Soil erosion at slope scale is dependent on the size of the plot. This is because soil erosion is a scale-dependent process due to the spatial variability in infiltration, the potential for sediment to be captured by vegetation and other roughness components, and the changes in erosion rates and processes with increasing amounts of runoff. The effects of plot size may also vary with land use, as plot size may be less important in areas with a more homogeneous plant cover or bares soils; meanwhile the soil transmission losses will higher on vegetation covered soils and on patchy distributed plants. A series of study plots were established in 2003 at the El Teularet experimental Station in the Sierra de Enguera in eastern Spain. The overall goal is to assess runoff and erosion rates from different land uses at different spatial scales. Thirteen sets of plots have been established, and each set consists of five adjacent plots that vary in size from 1 m2 (1 x 1 m), 2 m2 (1 x 2 m), 4 m2 (1 x 4 m), 16 m2 (2 x 8 m) and 48 m2 (3 m wide x 16 m length). Each set of plots has a different land use, and the land uses being tested in the first year of this study are fallow, ploughed but unplanted, untilled oats and beans, tilled oats and beans, straw mulch, mulched with chipped olive branches, a geotextile developed to control erosion on agricultural fields, scrub oaks (Quercus coccifera), gorse (Ulex parviflorus), and three herbicide treatments—a systemic herbicide, a contact herbicide, and a persistent herbicide. From those plots, three plots were selected to analyse the effect of the size of the plot on the soil erosion assessment. Herbicide (bare), Catch crops (oat) and scrubland were selected to analyze the soil losses during 2004 and 2005. The results shows that sediment delivery is highly dependent on the land use and land management as the scrubland contributed with null sediment yield, meanwhile the herbicide reached the largest soil loss. The soil erosion was higher

  6. Relative Quantification of Costal Cordillera (Ecuador) Uplift : Preliminary Results from Quantitative Geomorphology

    NASA Astrophysics Data System (ADS)

    Reyes, Pedro; Dauteuil, Olivier; Michaud, François

    2010-05-01

    The coastal cordillera of Ecuador (culminating point around 800 m) includes on its littoral margins uplifted marine terraces (maximum known 360 m). The coastal cordillera constitutes an important barrier of drainage and on nearly 600 km the drainage resulting from the Andes is diverted towards Río Guayas in the South and Río Esmeraldas in North. What is the uplifting mode of the coastal cordillera? For how long it has constituted a barrier of drainage? Does the coastal cordillera rising be linked with the littoral margin rising? Does the cordillera have raised in a homogeneous or segmented way? What is the geodynamic process of the uplift of the cordillera? Can this uplift be related with the subduction of the Carnegie ridge? The first objective of this work is to analyze the morphology of the coastal cordillera with helps of quantitative geomorphology using digital techniques such as DEM (realized with a resolution of 30 m by Marc Souris, IRD), to specify the evolution of the coastal cordillera uplift. This study was carried out starting combining analysis of morphology, maps derived from the slopes and anomalies of the drainage of the hydrographic network. In the second time, three methods were applied to DEM data using the ArcGIS software: 1) the digitalization and the interpolation of basal surface of the last marine formation of regional distribution (the Borbón formation on the geological map of Ecuador) to determine paleo-horizontal and to see its deformation; 2) the extraction of 109 profiles of rivers which allow us to calculate for each river the vertical, horizontal, and total deviation compared to the theoretical profile of the river and the associated SL index; 3) the measurement of the relief incision (depth + half width of the valley, on the whole 7500 measurements) according to the method of Bonnet et al. (1998). We adapted this method to be able to represent the state of incision in any point, correcting from the influence of the lithology and

  7. On the Urban-Rural Differences in Classroom Environment in Compulsory Education in the Eastern Coastal Developed Areas of China

    ERIC Educational Resources Information Center

    Sun, Furong; Xie, Limin

    2008-01-01

    Totally 789 students from 18 schools (9 primary schools and 9 junior high schools) at a medium managed level from Shanghai, Wenzhou, and Aojiang, which are located in the Eastern coastal developed areas of China were investigated with the questionnaire of Hong Kong Classroom Environment Scale in this study. The result indicates that the actual…

  8. Metallogeny of epithermal gold deposits in the western US Cordillera

    SciTech Connect

    Duke, N.A.

    1985-01-01

    The mid-Tertiary sediment-, volcanic-, and detachment fault-hosted epithermal gold deposits (EGDs) of the western US Cordillera favor the outboard side of the tectonically thickened miogeoanticlines. Post Mesozoic accretion, this cratonic shelf-oceanic basin transition zone underwent a period of extensional uplift that thinned the brittle upper crust through listric-normal and detachment faulting, and the decoupled metamorphic infrastructure by ductile necking. The EDGs formed in the upper crust peripheral to tectonically exposed metamorphic core complexes synchronously with active extension. They demonstrate close space/time relationships to the centers of ash flow tuff eruptions that characterized this period. In general the metal concentrated in EDGs had a common source and transport mechanism. The fact that major EGDs occur along obducted oceanic thrust plates indicates that the gold was originally scavaged from oceanic successions during dewatering along the thrust structures. The metal was again mobilized in meteoric dominated hot spring systems operating within volcani-tectonic sinks occurring at ignimbrite eruptive centers. As a result, the siting of both sediment- and volcanic-hosted EGDs is controlled largely by proximity to the mid-Tertiary paleosurface. Specific controls for the precipitation of gold varies with deposit type but critical behavior of the ore-bearing fluid and/or redox reactions between migrating fluids and reduced lithology crosscut by permeable structures are primary.

  9. The North American Cordillera - an Impediment to Growing the Continent-wide Laurentide Ice Sheet

    NASA Astrophysics Data System (ADS)

    Löfverström, M.; Liakka, J.; Kleman, J.

    2015-12-01

    Much effort has been devoted to understanding the climate of the Last Glacial Maximum (LGM) when the continent-wide Laurentide Ice Sheet resided in North America. It has been established, however, that the massive LGM ice sheet was a relatively short lasting (5-15 kyrs) "glacial extreme", and the longer build-up phase (around 75-85 kyrs in length) was dominated by an east-heavy ice configuration and largely ice-free conditions in the interior of the continent. The present study aims to investigate whether first-order (large scale) interactions between the atmosphere and ice sheets can explain the asymmetric ice evolution and the limited glaciation of the continental interior in the larger part of the last glacial cycle. Simulations are conducted using a comprehensive atmospheric circulation model asynchronously coupled to an ice-sheet model. The atmospheric state is updated for every 2×106 km3 increase in ice volume and the coupled model is integrated to steady state. We resort to a simplified model setup, using a triangular representation of North America, with and without the influence of the Cordilleran region, in order to isolate the influence of the mountain range on the ice sheet evolution. In the first experiment we use a flat continent with no background topography. The ice sheet evolves fairly zonally symmetric and the equilibrium ice sheet is continent wide and has the highest point in the center of the continent. In the second experiment we include a simplified representation of the Cordilleran region. The ice sheet's equilibrium state is here structurally different from the flat continent case; the center of mass is strongly shifted to the east and the interior of the continent remains ice-free - an outline resembling the geologically determined pre-LGM state. The ice sheet induces both mechanically and thermally forced stationary waves that result in a reduced cloudiness and hence an increased downwelling of radiation at the surface. This yields

  10. Downscaling reanalysis data to high-resolution variables above a glacier surface (Cordillera Blanca, Peru)

    NASA Astrophysics Data System (ADS)

    Hofer, Marlis; Mölg, Thomas; Marzeion, Ben; Kaser, Georg

    2010-05-01

    Recently initiated observation networks in the Cordillera Blanca provide temporally high-resolution, yet short-term atmospheric data. The aim of this study is to extend the existing time series into the past. We present an empirical-statistical downscaling (ESD) model that links 6-hourly NCEP/NCAR reanalysis data to the local target variables, measured at the tropical glacier Artesonraju (Northern Cordillera Blanca). The approach is particular in the context of ESD for two reasons. First, the observational time series for model calibration are short (only about two years). Second, unlike most ESD studies in climate research, we focus on variables at a high temporal resolution (i.e., six-hourly values). Our target variables are two important drivers in the surface energy balance of tropical glaciers; air temperature and specific humidity. The selection of predictor fields from the reanalysis data is based on regression analyses and climatologic considerations. The ESD modelling procedure includes combined empirical orthogonal function and multiple regression analyses. Principal component screening is based on cross-validation using the Akaike Information Criterion as model selection criterion. Double cross-validation is applied for model evaluation. Potential autocorrelation in the time series is considered by defining the block length in the resampling procedure. Apart from the selection of predictor fields, the modelling procedure is automated and does not include subjective choices. We assess the ESD model sensitivity to the predictor choice by using both single- and mixed-field predictors of the variables air temperature (1000 hPa), specific humidity (1000 hPa), and zonal wind speed (500 hPa). The chosen downscaling domain ranges from 80 to 50 degrees west and from 0 to 20 degrees south. Statistical transfer functions are derived individually for different months and times of day (month/hour-models). The forecast skill of the month/hour-models largely depends on

  11. New insights on the crustal thickness and its lateral variations beneath the Rif Cordillera

    NASA Astrophysics Data System (ADS)

    Gil de la Iglesia, A.; Diaz Cusi, J.; Gallart, J.; Carbonell, R.; Harnafi, M.; Levander, A.

    2014-12-01

    The Rif cordillera forms, together with the Betic ranges, one of the tightest orogenic arcs on Earth. This continental boundary zone is dominated now by the slow convergence between Nubia and Eurasia, but with clear evidences of extensional tectonics. One of the missing elements to constrain the complex geodynamics of the Gibraltar Arc System is the knowledge on crustal structure beneath northern Morocco. In the last decade a major effort has been done in this sense, from active and passive seismics. We compile here the recent results available from the Rif domains. Two 330 km long wide angle DSS profiles were recorded end of 2011 across the Rif in NS and EW transects within the Rifsis project, complemented by onshore recordings of the Gassis-WestMed marine profiles. At the same period, BB seismic arrays were deployed in the area within Topo-Iberia and Picasso projects, allowing receiver function analyses of crustal depths. The ray-tracing modeling of the Rifsis profiles reveal a large Moho step and an area of crustal thickening both in EW and NS directions, grossly coincident with the Bouguer gravity anomalies. The deployment logistics allowed that all the stations recorded all the shots, thus providing useful offline data. We will use here all available in-line and offline data to provide a map of the crustal thickness in northern Morocco. We combined two approaches: i) a hyperbolic time reduction applied to the seismic data, resulting in low-fold stacks in which the reflections from the Moho should appear as subhorizontal lines; ii) the arrival times of the observed PmP phases allow, assuming a mean crustal velocity, to assign a midpoint crustal thickness to each lecture. Although some uncertainties may be inherent to those approaches, a large crustal root, reaching more than 50 km, is well documented in the central part of the Rif Cordillera, close to the zone where the Alboran slab may still be attached to the lithosphere. We also compared these results with

  12. Petrographic and Geochemical Characterization of the Cambumbia STOCK in Andean Central Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

    Rojas Lequerica, S.; Jaramillo Mejía, J.; Concha Perdomo, A.

    2012-12-01

    The Cambumbia Stock is located on the western flank of the Central Cordillera of the northern Andes. The goals of this study were to petrographic and geochemically characterize the Cambumbia igneous body and to establish its petrogenetic history. 41 samples were collected, 28 for petrographic analysis and 14 for elementary chemical determination by ICP-MS. Petrographically the samples were classified as hornblende and pyroxene-gabbros varying to diorites, gabbronorites and tonalites, the rock texture varies from medium to coarse granular grain, with local microporfiritic texture. It was concluded from the major elements analysis that the samples correspond to the sub-alkaline series with low K content, mainly in the calc-alkaline series, within the gabbros and diorites fields. By using the SiO2 vs TiO2 (Jaramillo, 1980), Th/Yb vs Ta/Yb (Pearce, 1984) (Fig. 1) and Zr/117-Th-Nb/16 (Wood, 1979) diagrams it was determined that these rocks were generated in two geotectonic environments: one type MOR (extension) and other island arc (subduction, compression). Petrographic and geochemical comparisons between the rocks of Cambumbia Stock and Diorite and Gabbro El Pueblito (Giraldo, 2009) (located about 25 km to the north-west) may postulate a possible genetic link between them. Recently, a U/Pb age was obtained by the Universidad de Caldas in zircon in 2009 (not published data), yielded an age of 233.41 ± 3.4 Ma (Middle Triassic). This age is consistent with the global event of the extension and fragmentation of Pangea supercontinent. In addition, the mantle nature of the source and the petrogenetic evolution of the magmatic system were established. References GIRALDO, M.I., (2009): Esquema geodinámica de la parte noroccidental de la cordillera Central de Colombia. (Thesis). p.56-68. Universidad Nacional de Colombia, Medellín. JARAMILLO, J.M. (1980): Petrology and geochemistry of the Nevado del Ruiz Volcano northern Andes, Colombia (Thesis). 167 p. University of Houston

  13. Active rollback in the Gibraltar Arc: Evidences from CGPS data in the western Betic Cordillera

    NASA Astrophysics Data System (ADS)

    Gonzalez-Castillo, L.; Galindo-Zaldivar, J.; de Lacy, M. C.; Borque, M. J.; Martinez-Moreno, F. J.; García-Armenteros, J. A.; Gil, A. J.

    2015-11-01

    The Gibraltar Arc, located in the western Mediterranean Sea, is an arcuate Alpine orogen formed by the Betic and Rif Cordilleras, separated by the Alboran Sea. New continuous GPS data (2008-2013) obtained in the Topo-Iberia stations of the western Betic Cordillera allow us to improve the present-day deformation pattern related to active tectonics in this collision area between the Eurasian and African plates. These data indicate a very consistent westward motion of the Betic Cordillera with respect to the relatively stable Iberian Massif foreland. The displacement in the Betics increases toward the south and west, reaching maximum values in the Gibraltar Strait area (4.27 mm/yr in Ceuta, CEU1, and 4.06 mm/yr in San Fernando, SFER), then progressively decreasing toward the northwestern mountain front. The recent geological structures and seismicity evidence moderate deformation in a roughly NW-SE to WNW-ESE compressional stress setting in the mountain frontal areas, and moderate extension toward the internal part of the cordillera. The mountain front undergoes progressive development of folds affecting at least up to Pliocene deposits, with similar recent geological and geodetical rates. This folded strip helps to accommodate the active deformation with scarce associated seismicity. The displacement pattern is in agreement with the present-day clockwise rotation of the tectonic units in the northern branch of the Gibraltar Arc. Our data support that the westward emplacement of the Betic Cordillera continues to be active in a rollback tectonic scenario.

  14. Space-time evolution of a growth fold (Betic Cordillera, Spain). Evidences from 3D geometrical modelling

    NASA Astrophysics Data System (ADS)

    Martin-Rojas, Ivan; Alfaro, Pedro; Estévez, Antonio

    2014-05-01

    We present a study that encompasses several software tools (iGIS©, ArcGIS©, Autocad©, etc.) and data (geological mapping, high resolution digital topographic data, high resolution aerial photographs, etc.) to create a detailed 3D geometric model of an active fault propagation growth fold. This 3D model clearly shows structural features of the analysed fold, as well as growth relationships and sedimentary patterns. The results obtained permit us to discuss the kinematics and structural evolution of the fold and the fault in time and space. The study fault propagation fold is the Crevillente syncline. This fold represents the northern limit of the Bajo Segura Basin, an intermontane basin in the Eastern Betic Cordillera (SE Spain) developed from upper Miocene on. 3D features of the Crevillente syncline, including growth pattern, indicate that limb rotation and, consequently, fault activity was higher during Messinian than during Tortonian; consequently, fault activity was also higher. From Pliocene on our data point that limb rotation and fault activity steadies or probably decreases. This in time evolution of the Crevillente syncline is not the same all along the structure; actually the 3D geometric model indicates that observed lateral heterogeneity is related to along strike variation of fault displacement.

  15. Cache Creek terrane entrapment: Oroclinal paradox within the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Mihalynuk, Mitch G.; Nelson, Joanne; Diakow, Larry J.

    1994-06-01

    Exotic and far-traveled oceanic crustal rocks of the Cache Creek terrane (CC) are bordered by less exotic Quesnel (QN) and Stikine (ST) arc terranes to the east, north, and west. All of these terranes are enveloped by an arcuate belt of displaced continental margin rocks; the Kootenay (KO), Nisling (NS), and parts of the Yukon-Tanana (YTT) terranes, that have indirect ties to ancestral North America (NA). Initial 87Sr/86Sr isopleths conform to this arcuate pattern. Such a pattern of concentric belts presents a geological conundrum: How did the QN, ST, and CC come to be virtually enveloped by terranes with ties to NA? Past and current models that explain assembly of the Canadian Cordillera are deficient in their treatment of this problem. We propose that Early Mesozoic QN and ST were joined through their northern ends as two adjacent arc festoons that faced south toward the Cache Creek ocean (Panthalassa?). Oceanic plateau remnants within the CC today were transported from the Tethyan realm and collided with these arcs during subduction of the Cache Creek ocean. Counterclockwise oroclinal rotation of ST and NS terranes in the Late Triassic to Early Jurassic caused enclosure of the CC. Rotation continued until these terranes collided with QN in the Middle Jurassic. Paleomagnetic declination data provide support for this model in the form of large average anticlockwise rotations for Permian to Early Jurassic sites in ST but moderate clockwise rotations for sites in QN. Specific modern analogues for the Cordilleran orocline include the Yap trench, where the Caroline rise is colliding end-on with the Mariana Arc and the Banda Arc, located on the southeastern "tail" of the Asian plate, which is being deformed into a tight loop by interactions with the Australian and Pacific plates.

  16. Mid-tertiary volcano-tectonic development of the Southwestern Cordillera of North America

    NASA Technical Reports Server (NTRS)

    Nelson, Kerri L.

    1987-01-01

    In the Southwestern Cordillera (SC) of North America, volcanic style changed from dominantly calcalkaline stratovolcanoes to caldera-related magmatism during the mid-Tertiary. The dominant tectonic process affecting the region during this time was convergence of the Farallon and North American Plates. The change in style of volcanism indicates a change in the operative stress regime: compressional for the earlier calcalkaline volcanism and tensional for development of the calderas. The development of the centers were compared to evaluate the volcano-tectonic relationship of caldera development within and between centers and determine the relationships between the earlier calcalkaline and later caldera-style volcanisms. The calderas exhibit three distinct stages of development that are closely associated with the East Pacific Rise/trench collision. The spatial and temporal association of the calcalkaline and caldera-related volcanism argues for the SC representing a region of continued arc magnetism in which the style of volcanism varied in response to differences in regional stresses.

  17. Mantle plume influence on the Neogene uplift and extension of the US western Cordillera?

    USGS Publications Warehouse

    Parsons, T.; Thompson, G.A.; Sleep, Norman H.

    1994-01-01

    Despite its highly extended and thinned crust, much of the western Cordillera in the United States is elevated more than 1km above sea level. Therefore, this region cannot be thought of as thick crust floating isostatically in a uniform mantle; rather, the lithospheric mantle and/or the upper asthenosphere must vary in thickness or density across the region. Utilizing crustal thickness and density constraints, the residual mass defcicit that must occur in the mantle lithosphere and asthenosphere beneath the western Cordillera was modelled. A major hot spot broke out during a complex series of Cenozoic tectonic events that included lithospheric thickening, back-arc extension, and transition from subduction to a transform plate boundary. It is suggested that many of the characteristics that make the western Cordillera unique among extensional provinces can be attributed to the mantle plume that created the Yellowstone hot spot. -Authors

  18. A new golden frog species of the genus Diasporus (Amphibia, Eleutherodactylidae) from the Cordillera Central, western Panama

    PubMed Central

    Hertz, Andreas; Hauenschild, Frank; Lotzkat, Sebastian; Köhler, Gunther

    2012-01-01

    Abstract We describe the frog species Diasporus citrinobapheus sp. n. from the Cordillera Central of western Panama. The new species differs from all other species in its genus in coloration, disk cover and disk pad shape, skin texture, advertisement call, and size. It is most similar to Diasporus tigrillo, from which it differs in dorsal skin texture, relative tibia length, number of vomerine teeth, ventral coloration, dorsal markings, and relative tympanum size, and to Diasporus gularis, from which it can be distinguished by the lack of membranes between the toes, adult size, posterior thigh coloration, and position of the choanae. We provide data on morpho- logy, vocalization, and distribution of the new species, as well as brief information on its natural history. PMID:22679389

  19. Bio- and toxic elements in edible wild mushrooms from two regions of potentially different environmental conditions in eastern Poland.

    PubMed

    Brzezicha-Cirocka, Justyna; Mędyk, Małgorzata; Falandysz, Jerzy; Szefer, Piotr

    2016-11-01

    In the present study, the composition of bio-elements (K, Na, Mg, Ca, Fe, Cu, Zn) and toxic elements (Ag, Cd) in seven edible mushrooms from the rural and woodland region of Morąg (north-eastern Poland) and the rural and industrial region of the Tarnobrzeska Upland (south-eastern Poland) were investigated using a validated method. The species examined were Boletus edulis, Cantharellus cibarius, Leccinum aurantiacum, Leccinum versipelle, Lycoperdon perlatum, Suillus luteus, and Xerocomus subtomentosus. Final determination was carried out by flame atomic absorption spectroscopy (FAAS) after microwave-assisted decomposition of sample matrices with solutions of concentrated nitric acid in the pressurized polytetrafluoroethylene vessels. The contents of the alkali elements and alkali earth elements were determined in the species surveyed. The alkali elements, earth alkali elements, and transition metals (Ag, Cu, Zn, Fe, and Mn) were at typical concentrations as was determined for the same or similar species elsewhere in Poland and Europe. The results may suggest a lack of local and regional emissions of those metallic elements from industrialization of some sites in the Tarnobrzeska Plain. Cadmium was at elevated concentrations in L. versipelle from the Tarnobrzeska Plain but the reason-pollution or geogenic source-was unknown, while it was at typical concentrations in other species.

  20. Hydrogen Isotope Evidence for Giant Meteoric-Hydrothermal Systems Associated with Extension and Magmatism in the Southern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Holk, G. J.; McCarthy, A.

    2014-12-01

    Over 400 published mineral and fluid inclusion δD values from the southern Canadian Cordillera and our new data from the Eocene Penticton Group Volcanics and Coryell Intrusive Suite of the Southern Omineca Belt and the Western Metamorphic Belt of the Central Coast Orogen are compiled using GIS. δDH2O is estimated using published D/H fractionation factors at 400°C; the error is ±20‰, small enough to distinguish deep magmatic/metamorphic fluids from meteoric-hydrothermal fluids. Histogram plots of δDH2O values estimated from minerals reveal peaks at δD = -60‰ (deep fluid) and ­-110‰ (Early Cenozoic meteoric-hydrothermal fluid); this provides a clear distinction between the two kinds of fluid. Our analysis reveals that syn-extensional meteoric-hydrothermal systems (δDH2O < -80‰) affected the eastern margin of the Coast Ranges Batholith between latitude 49° and 55° and the Omineca Belt between latitude 49° and 52°45'; both regions were affected by detachment faulting during late stages of magmatism in the Early Cenozoic (e.g., Parrish et al., 1988; Crawford et al., 2009). Zones that escaped the effects of meteoric-hydrothermal systems, preserving the D/H signature of deep fluids (δD > -80‰), include the Western Metamorphic Belt, the Western and Central Coast Ranges Batholith, the belt of Jurassic metamorphism that extends from the Cariboo Mountains to the Purcell Mountains, and the deepest structural levels of the Shuswap Metamorphic Core Complex; most of these samples have quartz-feldspar 18O/16O fractionations indicative of magmatic temperatures. High δDH2O values (> -50‰) suggest seawater alteration of the plutons of Vancouver Island (Magaritz and Taylor, 1986). Histogram plots of vein quartz fluid inclusion δD values (Nesbitt and Muehlenbachs, 1995) reveal three peaks that include the two produced by the mineral δD values, but these data are dominated by a large peak at δD = -150, a value similar to modern meteoric waters in the region

  1. New method for assessing the susceptibility of glacial lakes to outburst floods in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Emmer, A.; Vilímek, V.

    2014-09-01

    This paper presents a new and easily repeatable method for assessing the susceptibility of glacial lakes to outburst floods (GLOFs) within the Peruvian region of the Cordillera Blanca. The presented method was designed to: (a) be repeatable (from the point of view of the demands on input data), (b) be reproducible (to provide an instructive guide for different assessors), (c) provide multiple results for different GLOF scenarios and (d) be regionally focused on the lakes of the Cordillera Blanca. Based on the input data gained from remotely sensed images and digital terrain models/topographical maps, the susceptibility of glacial lakes to outburst floods is assessed using a combination of decision trees for clarity and numerical calculation for repeatability and reproducibility. A total of seventeen assessed characteristics are used, of which seven have not been used in this context before. Also, several ratios and calculations are defined for the first time. We assume that it is not relevant to represent the overall susceptibility of a particular lake to outburst floods by one result (number), thus it is described in the presented method by five separate results (representing five different GLOF scenarios). These are potentials for (a) dam overtopping resulting from a fast slope movement into the lake, (b) dam overtopping following the flood wave originating in a lake situated upstream, (c) dam failure resulting from a fast slope movement into the lake, (d) dam failure following the flood wave originating in a lake situated upstream and (e) dam failure following a strong earthquake. All of these potentials include two or three components and theoretically range from 0 to 1. The presented method was verified on the basis of assessing the pre-flood conditions of seven lakes which have produced ten glacial lake outburst floods in the past and ten lakes which have not. A comparison of these results showed that the presented method successfully identified lakes

  2. [Two new species of fresh water crab (Brachyura: Pseudothelphusidae) from Serranía de Los Paraguas, Cordillera Occidental, Colombia].

    PubMed

    Ramos-Tafur, Gabriel E

    2006-09-01

    Two new species of freshwater crabs of the genus Hypolobocera from Serranía de Los Paraguas, Cordillera Occidental, Colombia, are described. Hypolobocera solimani n. sp. is closely related to H. alata Campos 1989, but can be distinguished from it by smooth upper margin of third maxilliped merus, the size and shape of apex of first gonopod, and the internal lobe or papilla of spermatic channel, which is concave, raised, with ends with minute papillae or rounded tubercles. Hypolobocera triangula n. sp. is very similar to H. rotundilobata Rodríguez 1994, but differs from it by the shape and size of the lateral lobe, an oblique basal ridge of tubercles and by the apex of first gonopod. With the two new species, the total number of valid members of the genus Hypolobocera known from western Colombia or biogeographic Chocó is 20.

  3. Karst evolution in the Cordillera de la Sal (Atacama, Chili)

    NASA Astrophysics Data System (ADS)

    de Waele, J.; Forti, P.; Picotti, V.; Zini, L.; Cucchi, F.; Brook, G.

    2009-04-01

    Rock salt composed of halite is at least three orders of magnitude more soluble than limestone. Because of this very high solubility rock salt rarely crops out extensively at the surface and is readily dissolved leaving insoluble residue (mainly clays and marls). Rock salt can only survive at the surface where climate is extremely arid and normally displays a large set of typical solution morphologies similar to those developed on limestone. Solution of rock salt also leads to the formation of underground caves several km long. Close to the village of San Pedro de Atacama, North of the Salar de Atacama basin, there is an important NNE-SSW trending elongated anticlinal ridge composed of Oligo-Miocene evaporitic rocks known under the name Cordillera de la Sal. The thick salt beds of this ridge, even in this hyperarid climate (mean annual rainfall is below 20 mm/y and there may be no rain for several years), have been karstified by occasional rains and have a well developed surface karst geomorphology with extremely sharp rillenkarren often isolating salt pinnacles of up to 15 m in height. During the past 10 years interesting salt caves have been discovered in these halite beds and a detailed morphological study has been carried out both at the surface and in the most important caves with the aim of understanding the mechanisms responsible for their formation and evolution. Sixteen wood and bone fragments from the ceilings of caves and from diamictons in passages have been AMS radiocarbon dated, allowing us to determine when the cave systems formed and when the major sediment units were emplaced. In fact, cave formation appears to have been very rapid, with development of huge cave passages in salt (more than 10 m wide and 30 m high) in less than 2,000 years. Moreover, detailed surveys of cave morphology (e.g. meanders, erosion benches) and sediments (diamictons) suggest that the caves were formed by short-lived flash floods, probably produced by single extreme

  4. Evaporite deposits of Bogota area, Cordillera Oriental, Colombia

    USGS Publications Warehouse

    McLaughlin, Donald H.

    1972-01-01

    Four evaporite-bearing stratigraphic zones are known in Cretaceous strata of the Cordillera Oriental of Colombia north and east of Bogota. The easternmost and oldest zone is probably of Berriasian to Valanginian age. The next oldest is probably late Barremian to early Aptian in age. The third appears to be Aptian. The westernmost and best known sequence in the Sabana de Bogota is Turonian to early Coniacian in age. This youngest sequence contains the thickest salt deposits known in Colombia and is probably the most widespread geographically. Most of the rock salt exposed in the three accessible mines (at Zipaquira, Nemocon, and Upin) has a characteristic lamination of alternating slightly argillaceous and highly argillaceous salt layers of varied but moderate thickness. Black, calcareous claystone, commonly very pyritic, is interbedded conformably with the laminated salt in many places throughout the deposits. Fragments of black claystone derived from the thinner interbeds are ubiquitous in all deposits, both as concordant breccia zones and as isolated clasts. Anhydrite is scarce at Zipaquira and apparently even rarer at Nemocon and Upin. Gypsum is produced at three small deposits in the oldest evaporite zone where it probably was concentrated by leaching of salt initially associated with it. The two intervening evaporite zones are not exposed, but their existence and distribution are indicated by brine springs and locally by "rute," a distinctive black, calcareous mud formed by the leaching of salt beds. Fossils show that the youngest salt-claystone zone, in the Sabana de Bogota, is contemporary with associated hematitic sandstone and siltstone, and with carbonaceous and locally coaly claystone. Although evidence is poor, this same facies relation probably exists within the other three evaporite zones. All salt deposits in this study probably are associated with anticlines, a relation best exemplified by the deposits on the Sabana de Bogota. Within these

  5. Detection and prevalence of four different hemotropic Mycoplasma spp. in Eastern North Carolina American black bears (Ursus americanus).

    PubMed

    Westmoreland, Lori S H; Stoskopf, Michael K; Maggi, Ricardo G

    2017-02-01

    Hemotropic Mycoplasma spp. are globally emerging, obligate parasitic, epierythrocytic bacteria that infect many vertebrates, including humans. Hemoplasma infection can cause acute life-threatening symptoms or lead to a chronic sub-clinical carrier state. Hemotropic Mycoplasma spp. transmission, prevalence, and host specificity are uncertain. The purpose of this study was to determine the molecular prevalence of Mycoplasma species in blood from 68 free-ranging black bears from the eastern coast of North Carolina. DNA amplification of Mycoplasma 16S rRNA gene identified four distinct species infecting 34/68 (50%) of the black bear blood samples, including Candidatus M. haematoparvum. The high prevalence of hemotropic Mycoplasma infection in this wildlife species highlights the importance of understanding intra and inter species transmission. Black bears may play a role in the transmission of hemotropic Mycoplasma spp. between animals, arthropod vectors, and humans. Further studies are needed to elucidate black bears as a potential reservoir for hemotropic Mycoplasma infections.

  6. Population Declines of Mountain Coqui (Eleutherodactylus portoricensis) in the Cordillera Central of Puerto Rico

    PubMed Central

    Barker, Brittany S.; Ríos-Franceschi, Alejandro

    2014-01-01

    The Mountain Coqui (Eleutherodactylus portoricensis) is a frog endemic to montane rainforests in the Cordillera Central and Luquillo Mountains of Puerto Rico. Classified as endangered by the IUCN Red List and as vulnerable by the Department of Natural and Environmental Resources of Puerto Rico, this species has undergone considerable decline in the Luquillo Mountains. To evaluate the population status of E. portoricensis across its entire range, we conducted ~87 hours of surveys at 18 historical localities and 25 additional localities that we considered suitable for this species. We generated occupancy models to estimate the probability of occurrence at surveyed sites and to identify geographic and climatic factors affecting site occupancy. We also constructed a suitability map to visualize population status in relation to the presence of land cover at elevations where the species has been documented, and determined the dates when populations were last detected at historical localities. Eleutherodactylus portoricensis was detected at 14 of 43 localities, including 10 of 18 historical localities, but it was not detected at any localities west of Aibonito (western Cordillera Central). Occupancy models estimated the probability of occurrence for localities in the western Cordillera Central as zero. Site occupancy was positively associated with montane cloud forest, and negatively associated with the western Cordillera Central, maximum temperature, and precipitation seasonality. The suitability map suggests that declines have occurred despite the presence of suitable habitat. We suggest upgrading the extinction risk of E. portoricensis and potentially developing a captive breeding program for this species. PMID:25685250

  7. Cenozoic Evolution of the Eastern Colombian Andes: a New Perspective from Thermokinematic Modeling and Quantitative Detrital Geochronology

    NASA Astrophysics Data System (ADS)

    Parra, M.; Mora, A.; Caballero, V. M.; Horton, B. K.; Reyes-Harker, A.; Ramirez-Arias, J. C.

    2015-12-01

    The reconstruction of the kinematic evolution of the northern Andes in Eastern Colombia reveals two main stages of orogenic development, each one displaying a different dominant factor controlling mountain building. In a context of oblique arc-continent convergence associated to dextral shearing along the Caribbean-South American plate boundary, the Late Cretaceous to late Miocene growth of the Andes in eastern Colombia was mainly modulated by the location of inherited basement anisotropies that constituted normal faults in the early Mesozoic. Shortening budget reconstructions show that the main exogenous driver for this first stage of Cenozoic deformation is the Oligocene increase in westward drift of the South American Plate. A second stage is characterized by thick-skinned basement uplift occurring at peak rates in the last ~5 Ma. This rapid uplift has led to the main topographic construction and the ensuing orographic precipitation favoring enhanced erosion in the eastern Andean watersheds, which in turn has potentially triggered positive tectonic-climate feedbacks. Thermokinematic modeling of detrital apatite fission track and apatite and zircon (U-Th)/He data suggest that up to 50% of the shortening along the main frontal reverse fault that bounds the Eastern Cordillera to the east occurred in the last ~2 My. This Cenozoic portrait of orogen evolution results from the detailed reconstruction of the upper crustal architecture and deformation kinematics enabled by the integration of (1) surface mapping and subsurface geology based interpretation of industry seismic reflection data, (2) a new detailed biostratrigraphically constrained chronology of foreland basin sediment accumulation, (3) the evolution of sediment source areas based on the quantitative comparison of various sedimentary provenance proxies, mainly detrital zircon U-Pb, and (4) thermokinematic modeling of a multi-method thermochronometric extensive database using our own software development.

  8. Plio-Pleistocene drainage development in an inverted sedimentary basin: Vera basin, Betic Cordillera, SE Spain

    NASA Astrophysics Data System (ADS)

    Stokes, Martin

    2008-08-01

    The Vera basin is one of a series of interconnected Neogene-Quaternary sedimentary basins located within the Internal Zone of the Betic Cordillera (southeast Spain). Since the Pliocene the Vera basin has been subjected to low uplift rates (11-21 m Ma - 1 ) and inverted via compressive tectonics that are related to the ongoing oblique collision between the African and Iberian plates. Within this paper the sedimentary and geomorphic response to basin inversion is explored. Sedimentary processes and environments are established for key stratigraphic units of the Pliocene/Plio-Pleistocene basin fill and Pleistocene dissectional landscape. These data are subsequently utilised to reconstruct an evolving basin palaeogeography. Fault and uplift data are employed to discuss the role of tectonically driven basin inversion for controlling the resultant palaeogeographic changes and associated patterns of drainage development. During the Early-Mid Pliocene the Vera basin was characterised by shallow marine shelf conditions (Cuevas Formation). A major palaeogeographic reorganisation occurred during the Mid-Late Pliocene. Strike-slip movement along the eastern basin margin, coupled with uplift and basin emergence created a protected, partially enclosed marine embayment that was conducive for Gilbert-type fan-delta sedimentation from fluvial inputs along the northern and eastern basin margins (Espíritu Santo Formation). The Vera basin then became fully continental and internally drained through the development of a consequent drainage network that formed following the withdrawal of marine conditions during the Late Pliocene to Early Pleistocene. Alluvial fans developed along the northern and western basin margins, grading to a bajada and terminating in a playa lake in central basin areas (Salmerón Formation). During the Early-Mid Pleistocene a switch from basin infilling to dissection took place, recorded by alluvial fan incision, a switch to braided river sedimentation and

  9. Investigating Glacier Surface Conditions using High-Definition Ground Based Infrared Imagery: Insight from the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Aubry-Wake, C.; Baraer, M.; McKenzie, J. M.; Mark, B. G.; Wigmore, O.; Hellstrom, R.

    2014-12-01

    The Cordillera Blanca, Peru, has the highest concentration of glaciers in the tropics. These glaciers, which in some valleys provide up to 70% of the dry season runoff, are rapidly retreating, with potential impacts on water resources. To predict the future changes in water resource in the region, it is important to better understand the processes driving tropical glacier ablation at the headwater of these systems. However, due to the glaciers' high altitude and the remote location, new techniques are needed to investigate these processes. Here we use high-definition ground-based infrared thermal imagery, paired with traditional weather monitoring instruments located on and adjacent to the glacier, to obtain high temporal and spatial resolution temperature maps of the surface of the Cuchillacocha glacier in the Cordillera Blanca. For four consecutive dry seasons (July 2011-2014), 24 to 48 hours of time-lapse imagery (5-30 minute spacing) of the glacier surface and surrounding area were acquired in conjunction with climate data. We compare the spatial and temporal variability of the surface temperature with numerous factors, including the surface conditions (e.g. ice, firn, debris cover, etc.), the thermal gradient at the edge of the glacier and with night time radiative cooling under different atmospheric conditions. The results show that sub-daily fluctuations in runoff from the glacier can be explained in large part by the incoming solar radiation and that the heating not only of the ice surface, but the surround bedrock, are important controls on the rate of meltwater generation. This study shows the potential utility for collecting and analyzing ground based infrared imagery for glacier studies, with implications for hydrologic and water resource applications.

  10. Population structure of guppies in north-eastern Venezuela, the area of putative incipient speciation

    PubMed Central

    2014-01-01

    Background Geographic barriers to gene flow and divergence among populations in sexual traits are two important causes of genetic isolation which may lead to speciation. Genetic isolation may be facilitated if these two mechanisms act synergistically. The guppy from the Cumaná region (within the Cariaco drainage) of eastern Venezuela has been previously described as a case of incipient speciation driven by sexual selection, significantly differentiated in sexual colouration and body shape from the common guppy, Poecilia reticulata. The latter occurs widely in northern Venezuela, including the south-eastern side of Cordillera de la Costa, where it inhabits streams belonging to the San Juan drainage. Here, we present molecular and morphological analyses of differentiation among guppy populations in the Cariaco and San Juan drainages. Our analyses are based on a 953 bp long mtDNA fragment, a set of 15 microsatellites (519 fish from 20 populations), and four phenotypic traits. Results Both microsatellite and mtDNA data showed that guppies inhabiting the two drainages are characterised by a significant genetic differentiation, but a higher proportion of the genetic variance was distributed among populations within regions. Most guppies in the Cariaco drainage had mtDNA from a distinct lineage, but we also found evidence for widespread introgression of mtDNA from the San Juan drainage into the Cariaco drainage. Phenotypically, populations in the two regions differed significantly only in the number of black crescents. Phenotypic clustering did not support existence of two distinct groupings, but indicated a degree of distinctiveness of Central Cumaná (CC) population. However, CC population showed little differentiation at the neutral markers from the proximate populations within the Cariaco drainage. Conclusions Our findings are consistent with only partial genetic isolation between the two geographic regions and indicate that the geographic barrier of Cordillera de

  11. Differences between near-surface equivalent temperature and temperature trends for the Eastern United States. Equivalent temperature as an alternative measure of heat content

    USGS Publications Warehouse

    Davey, C.A.; Pielke, R.A.; Gallo, K.P.

    2006-01-01

    There is currently much attention being given to the observed increase in near-surface air temperatures during the last century. The proper investigation of heating trends, however, requires that we include surface heat content to monitor this aspect of the climate system. Changes in heat content of the Earth's climate are not fully described by temperature alone. Moist enthalpy or, alternatively, equivalent temperature, is more sensitive to surface vegetation properties than is air temperature and therefore more accurately depicts surface heating trends. The microclimates evident at many surface observation sites highlight the influence of land surface characteristics on local surface heating trends. Temperature and equivalent temperature trend differences from 1982-1997 are examined for surface sites in the Eastern U.S. Overall trend differences at the surface indicate equivalent temperature trends are relatively warmer than temperature trends in the Eastern U.S. Seasonally, equivalent temperature trends are relatively warmer than temperature trends in winter and are relatively cooler in the fall. These patterns, however, vary widely from site to site, so local microclimate is very important. ?? 2006 Elsevier B.V. All rights reserved.

  12. Impact of drought and heat events on carbon exchanges in temperate pine forests of different ages in Eastern Canada

    NASA Astrophysics Data System (ADS)

    Arain, M. A.; MacKay, S. L.; Khomik, M.; Brodeur, J. J.; Schumacher, J.; Hartmann, H.; Peichl, M.

    2012-04-01

    North American forests play an important role in the global carbon cycle because they offset a large portion of global fossil fuel carbon dioxide (CO2) emissions. A substantial fraction of these carbon sequestering forests are located in the north-eastern temperate climate zones, where spring through early summer is the most productive period of the growing season. Therefore, variations in carbon sequestration rates due to environmental constraints during this period may have a profound impact on seasonal and annual net ecosystem productivity (NEP) of forest ecosystems in the region. Recent studies suggest that, in the future, summer warming and drought events may be shifted to both spring and autumn shoulder seasons and concurrent heat and drought events may exacerbate the negative effects of drought on carbon cycling in these forests. In this study the impact of seasonal and annual climate variability as well as extreme climatic events on gross primary productivity (GEP), ecosystem respiration (RE), net ecosystem productivity (NEP) and evapotranspiration (Ec) in an age-sequence (72, 37 and 9 years old) of planted temperate pine (white pine, Pinus strobus L.) forests, north of Lake Erie in southern Ontario, Canada will be examined using eight years (2003-2010) of eddy covariance flux and meteorological data. These sites are known as the Turkey Point Flux Station and had been part of the Canadian Carbon Program (CCP) or the Fluxnet-Canada Research Network (FCRN. The response of canopy transpiration (Et) and forest growth rates to experimentally reduced precipitation during the early growing season will also be evaluated in the 72-year old forest. A 20 m x 20 m throughfall exclusion setup was established and throughfall was excluded from April 1 to July 3, 2009. During this period 270 mm precipitation (27% of annual total) fell, of which 90% was excluded excluded. Sapflow measurements suggested that Et was 14% less in the drought plot compared to the reference plot

  13. Mother–offspring distances reflect sex differences in fine-scale genetic structure of eastern grey kangaroos

    PubMed Central

    King, Wendy J; Garant, Dany; Festa-Bianchet, Marco

    2015-01-01

    Natal dispersal affects life history and population biology and causes gene flow. In mammals, dispersal is usually male-biased so that females tend to be philopatric and surrounded by matrilineal kin, which may lead to preferential associations among female kin. Here we combine genetic analyses and behavioral observations to investigate spatial genetic structure and sex-biased dispersal patterns in a high-density population of mammals showing fission–fusion group dynamics. We studied eastern grey kangaroos (Macropus giganteus) over 2 years at Wilsons Promontory National Park, Australia, and found weak fine-scale genetic structure among adult females in both years but no structure among adult males. Immature male kangaroos moved away from their mothers at 18–25 months of age, while immature females remained near their mothers until older. A higher proportion of male (34%) than female (6%) subadults and young adults were observed to disperse, although median distances of detected dispersals were similar for both sexes. Adult females had overlapping ranges that were far wider than the maximum extent of spatial genetic structure found. Female kangaroos, although weakly philopatric, mostly encounter nonrelatives in fission–fusion groups at high density, and therefore kinship is unlikely to strongly affect sociality. PMID:26045958

  14. Effects of Air Pollution on Hospital Emergency Room Visits for Respiratory Diseases: Urban-Suburban Differences in Eastern China.

    PubMed

    Liu, Peng; Wang, Xining; Fan, Jiayin; Xiao, Wenxin; Wang, Yan

    2016-03-19

    A study on the relationships between ambient air pollutants (PM2.5, SO₂ and NO₂) and hospital emergency room visits (ERVs) for respiratory diseases from 2013 to 2014 was performed in both urban and suburban areas of Jinan, a heavily air-polluted city in Eastern China. This research was analyzed using generalized additive models (GAM) with Poisson regression, which controls for long-time trends, the "day of the week" effect and meteorological parameters. An increase of 10 μg/m³ in PM2.5, SO₂ and NO₂ corresponded to a 1.4% (95% confidence interval (CI): 0.7%, 2.1%), 1.2% (95% CI: 0.5%, 1.9%), and 2.5% (95%: 0.8%, 4.2%) growth in ERVs for the urban population, respectively, and a 1.5% (95%: 0.4%, 2.6%), 0.8% (95%: -0.7%, 2.3%), and 3.1% (95%: 0.5%, 5.7%) rise in ERVs for the suburban population, respectively. It was found that females were more susceptible than males to air pollution in the urban area when the analysis was stratified by gender, and the reverse result was seen in the suburban area. Our results suggest that the increase in ERVs for respiratory illnesses is linked to the levels of air pollutants in Jinan, and there may be some urban-suburban discrepancies in health outcomes from air pollutant exposure.

  15. Local Differences in HIV Prevalence: A Comparison of Social Venue Patrons, Antenatal Patients, and STI Patients in Eastern Kinshasa

    PubMed Central

    Mwandagalirwa, Kashamuka; Jackson, Elizabeth F.; McClamroch, Kristi; Ryder, Robert W.; Weir, Sharon S.

    2013-01-01

    Background This study compares the sexual behavior and HIV prevalence of men and women at social venues where people meet new sexual partners in Eastern Kinshasa with the HIV prevalence and behavior of STI treatment and antenatal clinic patients in the same area. Methods ANC clinic patients, STI clinic patients and social venue patrons were interviewed, asked to provide a blood sample onsite, and provided information about obtaining test results. All social venue patrons at all identified social venues in the study area were invited to participate. Results 1,116 pregnant women; 66 male and 229 female STI clinic patients; and 952 male and 247 female patrons of social venues were interviewed and tested. HIV prevalence ranged by group: ANC patients (4%); female venue patrons (12%); female STI patients (16%); male venue patrons (2%); and male STI patients (23%). HIV prevalence among sexworkers at social venues (29%) was higher than the prevalence among other female patrons with new or multiple partnerships (19%) or among female patrons denying sexwork (6%). However, the absolute number of infected women was higher among women reporting recent new or multiple partnerships than the smaller group of sexworkers (23 vs 18). Two-thirds of the infected female STI patients (24/36) reported no more than one sexual partner in the past year. Conclusion Improving prevention programs in Kinshasa is essential. Prevention efforts should not neglect women at social venues who do not self-identify as sexworkers but have high rates of new sexual partnerships. PMID:19525891

  16. Crust structure across the Rif Cordillera from 'RIFSIS' seismic refraction and wide-angle reflection experiment

    NASA Astrophysics Data System (ADS)

    Gil, Alba; Gallart, Josep; Díaz, Jordi; Carbonell, Ramon; Harnafi, Mimoun; Levander, Alan

    2013-04-01

    The Rif Cordillera, located in North Morocco forms, together with the Betic Range, the Gibraltar Arc around the Alboran Sea. This asymmetric curved mountain belt originated during a Miocene continent-continent collision as a result of the westward motion of the Alboran domain between northwest Africa and Iberia. The complexity of the area favored the proposition of diverse tectonic models, such as roll-back, accompanied and followed by lithospheric convective down-welling, and delamination. In this study, we present models of crustal structure derived from a seismic refraction and wide-angle reflection experiment which took place in October 2011 within the Spanish project RIFSIS complemented by the US-PICASSO one. Two profiles oriented N-S and E-W respectively were carried out across the Rif domains. Five shots of 1 Tn each were detonated along the lines and at the crossing point, recorded by about 900 stations from US-Iris pool deployed at an average spacing of 750 m. The N-S line was extended northwards by a 70 km long segment in Spain, in the Betic Range. Southwards, this profile connects with the one recorded in 2010 across the Atlas Mountains, within the SIMA project. The interpreted crustal structure differentiates two sedimentary layers on top of the basement, inferred from the observed first arrivals at short offsets, followed by upper, mid and lower crustal levels constrained by reflected phases visible in the record sections. The bottom of the crust is well defined from PmP phases, although the absence of Pn arrivals prevents to constrain upper mantle velocities. Average velocity values for the different layers in the models are respectively: 3.5 and 4.2 km/s for the sediments, 5.9, 6.3 and 6.6 km/s within the crust, and 8 km/s below Moho. These velocity depth models obtained at the Rif Cordillera hold major variations in crustal thickness, especially along the E-W profile, that shows a rapid change of 15-20 km in Moho depths within 30 km horizontal

  17. New paleomagnetic data from the northern Puna and western Cordillera Oriental, Argentina: a new insight on the timing of rotational deformation

    NASA Astrophysics Data System (ADS)

    Prezzi, Claudia; Caffe, Pablo J.; Somoza, Rubén

    2004-09-01

    Along the Central Andes a pattern of vertical axis tectonic rotations has been paleomagnetically identified. The rotations are clockwise in southern Bolivia, northern Chile and northwestern Argentina. Various models have been proposed to explain the geodynamic evolution of the Central Andes, but the driving mechanism of these rotations remains controversial. Constraining the spatial variability and the timing of the rotations may contribute to a better understanding of their origin. Our results complement information from previous studies, improving the knowledge of tectonic rotations in the region of the northern Argentine Puna and western Cordillera Oriental. In the San Juan de Oro basin (SJOB), 132 cores were drilled from the middle Miocene Tiomayo Formation in the zone of Tiomayo-Santa Ana (22°30'S-66°30'W), and from the ˜17 Ma Casa Colorada dacite dome complex. Another 114 cores were collected from middle Miocene dacitic dome centers emplaced in the zone of Laguna de Pozuelos basin (22°30'S-66°00'W). The results of our paleomagnetic study suggest that the sampled zones underwent very low, statistically insignificant rotation since middle Miocene. However, a tendency for low magnitude rotation appears when observing our data together with paleomagnetic results from coeval rocks in neighbouring areas. If so, this low rotation could be related to middle Miocene thrust activity in the central and eastern parts of the Cordillera Oriental. The combined analysis of paleomagnetic and structural data illustrates the probable, direct relationship between timing of significant rotations and timing of local deformation in the sourthern Central Andes.

  18. New method for assessing the potential hazardousness of glacial lakes in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Emmer, A.; Vilímek, V.

    2014-02-01

    This paper presents a new and easily repeatable objective method for assessing the potential hazardousness of glacial lakes within the Peruvian region of Cordillera Blanca (excluding ice-dammed lakes, which do not reach significant volumes in this region). The presented method was designed to meet four basic principles, which we considered as being crucial. These are: (a) principle of regional focus; (b) principle of objectivity; (c) principle of repeatability; and (d) principle of multiple results. Potential hazardousness is assessed based on a combination of decision trees for clarity and numerical calculation for objectivity. A total of seventeen assessed characteristics are used, of which seven have yet to be used in this context before. Also, several ratios and calculations are defined for the first time. We assume that it is not relevant to represent the overall potential hazardousness of a particular lake by one result (number), thus the potential hazardousness is described in the presented method by five separate results (representing five different glacial lake outburst flood scenarios). These are potentials for: (a) dam overtopping resulting from a dynamic slope movement into the lake; (b) dam overtopping following the flood wave originating in a lake situated upstream; (c) dam failure resulting from a dynamic slope movement into the lake; (d) dam failure following the flood wave originating in a lake situated upstream; and (e) dam failure following a heavy earthquake. All of these potentials theoretically range from 0 to 1. The presented method was verified on the basis of assessing the pre-flood conditions of seven lakes which have produced ten glacial lake outburst floods in the past and ten lakes which have not. A comparison of these results showed that the presented method successfully identifies the potentially hazardous lakes.

  19. Fluid flow along North American Cordillera detachments determined from stable isotope and high resolution chemical analyses

    NASA Astrophysics Data System (ADS)

    Quilichini, A.; Teyssier, C.; Mulch, A.; Nachlas, W.

    2009-12-01

    Fluid flow is likely a major parameter controlling the dynamics of extensional detachment zones. Buoyancy-driven fluid flow is generated by high heat flow beneath the detachment zone, where heat is advected by crustal thinning and magma intrusions. This hydrothermal convective flow is focused in the detachment zone for the duration of activity of the detachment at relatively high temperature (300-500°C), resulting in very significant fluid-rock interaction and isotopic exchange. Quantifying sources and fluid flux in detachments is a challenge because permeability of ductilely deforming rocks is poorly understood. In order to solve these problems, we studied two different Eocene extensional systems in the North American Cordillera: the quartzitic detachment which borders the Kettle dome metamorphic core complex (WA), and the quartzo-feldspathic Bitterroot shear zone along the Idaho batholith (MT). The Kettle Dome detachment provides a continuous section of ~200 m thick quartzite mylonite where high-resolution sampling (~5 m) indicates that Deuterium isotopic ratios that are obtained from synkinematic muscovite grains are consistent with a meteoric fluid source (-130 per mil). In the Bitterroot shear zone, Coyner (2003) reported similar Deuterium isotopic ratios (down to -140 per mil) in muscovite from mylonites and ultramylonites. Microprobe analyses were obtained for white mica porphyroclasts by performing transects perpendicular to the basal (001) cleavage in order to determine intragrain chemical zoning. Preliminary results for the Kettle dome indicate increasing phengite composition with depth, suggesting enhanced activity of the Tschermak exchange. The variations of the phengitic signature in muscovite indicates that temperature diminuish downsection, which is contradictory with the results obtained by the Qz-Ms oxygen isotope thermometer along the Kettle section. Our recent work provides geologic data for numerical models that address the permeability of

  20. New measurements of particulates in glacial snow and ice in the Cordillera Blanca mountains of Peru

    NASA Astrophysics Data System (ADS)

    All, J.; Schmitt, C.; Celestian, A. J.; Rucks, M.; Arnott, W. P.; Cole, R.

    2012-12-01

    During the local dry season (June/July) of 2011 and 2012, the American Climber Science Program (organized with the assistance of the American Alpine Club) conducted scientific expeditions in Huascaran National Park in Peru. The Park is located in the Cordillera Blanca mountain range and contains the world's largest collection of tropical mountain glaciers. One component of the environmental research program was sampling particulates on glacier surfaces by means of snow collection and filtration. Over 150 samples were collected during the two expeditions by volunteer climbers working with scientists in the field. Glacier snows were collected on over fifteen peaks throughout the range at altitudes from 4800 to nearly 6800 meters. Snow samples were kept frozen until the climber-scientists returned to basecamp - at which point they were rapidly melted and then immediately filtered through 0.7 micron PallFlex tissuequartz filters. The particulates captured on the filters have been analyzed for their bulk heat absorption properties as well as to determine the properties of individual particles through X-ray diffraction for bulk mineral identification, and Raman microscopy for chemical mapping of minerals. Preliminary results indicate that snow age, altitude, as well as geographic location (with respect to urban areas, mines, and predominant wind direction) all play significant roles in the amount and types of contaminants. Multiple locations were sampled during both expeditions as well as at different times during the same climbing season. Results include the relative heating capacity of the samples at various wavelengths as well as mineral composition information across the range. Local weather patterns and geographic observations will be used to identify potential sources of contaminants. Sampling will continue under the American Climber Science Program in 2013 and beyond.

  1. Infrared Imaging and Modeling of Proglacial Stream Temperature in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Baker, E. A.; Lautz, L.; McKenzie, J. M.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.; Glose, A.; Glas, R. L.; Mark, B. G.

    2015-12-01

    In the tropical Andes, glacial meltwater is an important water resource for downstream communities, especially during the dry season. Due to climate change, glacial retreat is accelerating and straining already limited water resources in the region. It is hypothesized that groundwater storage and discharge will play a critical role in sustaining future river flows. To improve our understanding of the hydrologic fluxes in proglacial valleys of the tropical Andes, we monitored a ~1.2 km reach of the Quilcayhuanca River, in the Cordillera Blanca, Peru, using a high resolution infrared (IR) camera and in-stream temperature sensors. We positioned the IR camera on the southern valley wall, 96 m above the valley floor, and collected >700 IR images at 10 minute intervals over 5 days. We deployed 40 temperature sensors along the stream at ~25 m intervals and 10 sensors at additional control points throughout the surrounding valley, recording temperature at 10 minute intervals. Groundwater temperature was recorded in 6 wells in the study area. The reach had diurnal temperature fluctuations from ~4 to 13°C, but did not exhibit large longitudinal temperature differences. Stream temperature profiles within the water column show stream water is well mixed, improving the ability of the IR camera to accurately observe the stream temperature at this research site. Temperature sensors in 4 reach tributaries recorded warmer temperatures than the main channel. The daily temperatures of one tributary fluctuated within the range of the groundwater temperature (~9 to 11°C), while another tributary exhibited a range of ~18°C. A weather station in the study area recorded climate data (air temperature, humidity, wind speed, solar radiation) at 10 minute intervals. We used this field data as input for a spatial and temporal energy balance model of the reach. Our model demonstrates the utility of IR imagery to monitor stream temperatures and improves our understanding of energy fluxes in

  2. Recent evolution and mass balance of Cordón Martial glaciers, Cordillera Fueguina Oriental

    NASA Astrophysics Data System (ADS)

    Strelin, Jorge; Iturraspe, Rodolfo

    2007-10-01

    Past and present glacier changes have been studied at Cordón Martial, Cordillera Fueguina Oriental, Tierra del Fuego, providing novel data for the Holocene deglaciation history of southern South America and extrapolating as well its future behavior based on predicted climatic changes. Regional geomorphologic and stratigraphic correlations indicate that the last glacier advance deposited the ice-proximal ("internal") moraines of Cordón Martial, around 330 14C yr BP, during the Late Little Ice Age (LLIA). Since then glaciers have receded slowly, until 60 years ago, when major glacier retreat started. There is a good correspondence for the past 100 years between the surface area variation of four small cirque glaciers at Cordón Martial and the annual temperature and precipitation data of Ushuaia. Between 1984 and 1998, Martial Este Glacier lost 0.64 ± 0.02 × 10 6 m 3 of ice mass (0.59 ± 0.02 × 10 6 m 3 w.e.), corresponding to an average ice thinning of 7.0 ± 0.2 m (6.4 ± 0.2 m w.e), according to repeated topographic mapping. More detailed climatic data have been obtained since 1998 at the Martial Este Glacier, including air temperature, humidity and solar radiation. These records, together with the monthly mass balance measured since March 2000, document the annual response of the Martial Este Glacier to the climate variation. Mass balances during hydrological years were positive in 2000, negative in 2001 and near equilibrium in 2002. Finally, using these data and the regional temperature trend projections, modeled for different future scenarios by the Atmosphere-Ocean Model (GISS-NASA/GSFC), potential climatic-change effects on this mountain glacier were extrapolated. The analysis shows that only the Martial Este Glacier may survive this century.

  3. Differences in heat shock protein 70 expression during larval and early spat development in the Eastern oyster, Crassostrea virginica (Gmelin, 1791).

    PubMed

    Ueda, Nobuo; Boettcher, Anne

    2009-07-01

    For a variety of species, changes in the expression of heat shock proteins (HSP) have been linked to key developmental changes, i.e., gametogenesis, embryogenesis, and metamorphosis. Many marine invertebrates are known to have a biphasic life cycle where pelagic larvae go through settlement and metamorphosis as they transition to the benthic life stage. A series of experiments were run to examine the expression of heat shock protein 70 (HSP 70) during larval and early spat (initial benthic phase) development in the Eastern oyster, Crassostrea virginica. In addition, the impact of thermal stress on HSP 70 expression during these early stages was studied. C. virginica larvae and spat expressed three HSP 70 isoforms, two constitutive, HSC 77 and HSC 72, and one inducible, HSP 69. We found differences in the expression of both the constitutive and inducible forms of HSP 70 among larval and early juvenile stages and in response to thermal stress. Low expression of HSP 69 during early larval and spat development may be associated with the susceptibility of these stages to environmental stress. Although developmental regulation of HSP 70 expression has been widely recognized, changes in its expression during settlement and metamorphosis of marine invertebrates are still unknown. The results of the current study demonstrated a reduction of HSP 70 expression during settlement and metamorphosis in the Eastern oyster, C. virginica.

  4. Assessing the variability of glacier lake bathymetries and potential peak discharge based on large-scale measurements in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Cochachin, Alejo; Huggel, Christian; Salazar, Cesar; Haeberli, Wilfried; Frey, Holger

    2015-04-01

    .9 km3 while the volume of all glacial lakes of the Cordillera Blanca ranges between 1.15 and 1.29 km3. The small difference in volume of the large lake sample as compared to the smaller sample of bathymetrically surveyed lakes is due to the large size of the measured lakes. The different distributions for lake volume and peak discharge indicate the range of variability in such estimates, and provides valuable first-order information for management and adaptation efforts in the field of water resources and flood prevention.

  5. Regional Analysis of the Hazard Level of Glacial Lakes in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Chisolm, Rachel E.; Jhon Sanchez Leon, Walter; McKinney, Daene C.; Cochachin Rapre, Alejo

    2016-04-01

    The Cordillera Blanca mountain range is the highest in Peru and contains many of the world's tropical glaciers. This region is severely impacted by climate change causing accelerated glacier retreat. Secondary impacts of climate change on glacier retreat include stress on water resources and the risk of glacial lake outburst floods (GLOFs) from the many lakes that are forming and growing at the base of glaciers. A number of GLOFs originating from lakes in the Cordillera Blanca have occurred over the last century, several of which have had catastrophic impacts on cities and communities downstream. Glaciologists and engineers in Peru have been studying the lakes of the Cordillera Blanca for many years and have identified several lakes that are considered dangerous. However, a systematic analysis of all the lakes in the Cordillera Blanca has never before been attempted. Some methodologies for this type of systematic analysis have been proposed (eg. Emmer and Vilimek 2014; Wang, et al. 2011), but as yet they have only been applied to a few select lakes in the Cordillera Blanca. This study uses remotely sensed data to study all of the lakes of the Glacial Lake Inventory published by the Glaciology and Water Resources Unit of Peru's National Water Authority (UGRH 2011). The objective of this study is to assign a level of potential hazard to each glacial lake in the Cordillera Blanca and to ascertain if any of the lakes beyond those that have already been studied might pose a danger to nearby populations. A number of parameters of analysis, both quantitative and qualitative, have been selected to assess the hazard level of each glacial lake in the Cordillera Blanca using digital elevation models, satellite imagery, and glacier outlines. These parameters are then combined to come up with a preliminary assessment of the hazard level of each lake; the equation weighting each parameter draws on previously published methodologies but is tailored to the regional characteristics

  6. Ophiolites and Continental Margins of the Mesozoic Western U.S. Cordillera

    NASA Astrophysics Data System (ADS)

    Dilek, Y.

    2001-12-01

    counterpart of the east-facing S-GV-CR system to the south. The Guerrero intra-oceanic island arc system in Mexico was also part of the ensimatic arc terrane. Incorporation of this super arc terrane into the North American continent occurred diachronously along the irregular continental margin in the Middle Jurassic (in the north) through Early Cretaceous (in the south) during an arc-continent collision, marking a collisional orogenic episode in the North American Cordilleran history. Rifting of this accreted arc in the Late Jurassic (155-148 Ma) might have resulted from a sinistral transtensional deformation associated with the rapid NW motion of North America. Magmas generated during this rifting event probably migrated through the accreted arc crust and the continental margin units in the tectonic lower plate. The Franciscan subduction zone dipping eastwards beneath the continent was established in the latest Jurassic, following the collisional event and restoring the North American Cordillera back into an accretionary-type, Andean-style orogen. Different episodes of orogen-parallel intra-continental strike-slip faulting facilitated lateral dispersion of accreted terranes and continental margin units during the Early Cretaceous and transpressional deformation and batholithic magmatism in the Sierra Nevada magmatic arc in the Late Cretaceous. A Jurassic-Cretaceous island arc system (Wrangellia-Insular Superterrane) that had developed west of the Jurassic archipelago collapsed into the edge of North America during Late Cretaceous-Tertiary time and underwent northward lateral translation along the continental margin. These observations and interpretations have strong implications for the tectonic evolution of Central America and the Caribbean region.

  7. Correlation by Rb-Sr geochronology of garnet growth histories from different structural levels within the Tauern Window, Eastern Alps

    SciTech Connect

    Christensen, John N.; Selverstone, Jane; Rosenfeld, John L.; Depaolo, Donald J.

    1993-06-01

    In order to evaluate rates of tectonometamorphic processes, growth rates of garnets from metamorphic rocks of the Tauern Window, Eastern Alps were measured using Rb-Sr isotopes. The garnet growth rates were determined from Rb-Sr isotopic zonation of single garnet crystals and the Rb-Sr isotopic compositions of their associated rock matrices. Garnets were analyzed from the Upper Schieferhulle (USH) and Lower Schieferhulle (LSH) within the Tauern Window. Two garnets from the USH grew at rates of 0.67(-0.13)+0.19 mm/million years and 0.88(-0.19)+0.34 mm/million years, respectively, indicating an average growth duration of 5.4 +- 1.7 million years. The duration of growth coupled with the amount of rotation recorded by inclusion trails in the USH garnets yields an average shear-strain rate during garnet growth of 2.7(-0.7)+1.2 x 10(-14) s-1 . Garnet growth in the sample from the USH occurred between 35.4 +- 0.6 and 30 +- 0.8 Ma. The garnet from the LSH grew at a rate of 0.23 +- 0.015 mm/mil lion years, between 62 +- 1.5 Ma and 30.2 +- 1.5 Ma. Contemporaneous cessation of garnet growth in both units at approximately 30 Ma is in accord with previous dating of the thermal peak of metamorphism in the Tauern Window. Correlation with previously published pressure-temperature paths for garnets from the USH and LSH yields approximate rates of burial, exhumation and heating during garnet growth. Assuming that these P - T paths are applicable to the garnets in this study, the contemporaneous exhumation rates recorded by garnet in the USH and LSH were approximately 4(-2)+3 mm/year and 2 +- 1 mm/year, respectively. [References: 34

  8. Effects of Air Pollution on Hospital Emergency Room Visits for Respiratory Diseases: Urban-Suburban Differences in Eastern China

    PubMed Central

    Liu, Peng; Wang, Xining; Fan, Jiayin; Xiao, Wenxin; Wang, Yan

    2016-01-01

    A study on the relationships between ambient air pollutants (PM2.5, SO2 and NO2) and hospital emergency room visits (ERVs) for respiratory diseases from 2013 to 2014 was performed in both urban and suburban areas of Jinan, a heavily air-polluted city in Eastern China. This research was analyzed using generalized additive models (GAM) with Poisson regression, which controls for long-time trends, the “day of the week” effect and meteorological parameters. An increase of 10 μg/m3 in PM2.5, SO2 and NO2 corresponded to a 1.4% (95% confidence interval (CI): 0.7%, 2.1%), 1.2% (95% CI: 0.5%, 1.9%), and 2.5% (95%: 0.8%, 4.2%) growth in ERVs for the urban population, respectively, and a 1.5% (95%: 0.4%, 2.6%), 0.8% (95%: −0.7%, 2.3%), and 3.1% (95%: 0.5%, 5.7%) rise in ERVs for the suburban population, respectively. It was found that females were more susceptible than males to air pollution in the urban area when the analysis was stratified by gender, and the reverse result was seen in the suburban area. Our results suggest that the increase in ERVs for respiratory illnesses is linked to the levels of air pollutants in Jinan, and there may be some urban-suburban discrepancies in health outcomes from air pollutant exposure. PMID:27007384

  9. Summary terrane, mineral deposit, and metallogenic belt maps of the Russian Far East, Alaska, and the Canadian Cordillera

    USGS Publications Warehouse

    Nokleberg, Warren J.; West, Timothy D.; Dawson, Kenneth M.; Shpikerman, Vladimir I.; Bundtzen, Thomas K.; Parfenov, Leonid M.; Monger, James W.; Ratkin, Vladimir V.; Baranov, Boris V.; Byalobzhesky, Stanislauv G.; Diggles, Michael F.; Eremin, Roman A.; Fujita, Kazuya; Gordey, Steven P.; Gorodinskiy, Mary E.; Goryachev, Nikolai A.; Feeney, Tracey D.; Frolov, Yuri F.; Grantz, Arthur; Khanchuk, Alexander I.; Koch, Richard D.; Natal'in, Boris A.; Natapov, Lev M.; Norton, Ian O.; Patton, William W.; Plafker, George; Pozdeev, Anany I.; Rozenblum, Ilya S.; Scholl, David W.; Sokolov, Sergei D.; Sosunov, Gleb M.; Stone, David B.; Tabor, Rowland W.; Tsukanov, Nickolai V.; Vallier, Tracy L.

    1998-01-01

    This report is part of a project on the major mineral deposits, metallogenesis, and tectonics of the Russian Far East, Alaska, and the Canadian Cordillera. The project is to provide critical information for collaborators and customers on bedrock geology and geophysics, tectonics, major metalliferous mineral resources, metallogenic patterns, and crustal origin and evolution of mineralizing systems for the Russian Far East, Alaska, and the Canadian Cordillera.

  10. Eastern Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this SeaWiFS image of eastern Alaska, the Aleutian Islands, Kodiak Island, Yukon and Tanana rivers are clearly visible. Also visible, but slightly hidden beneath the clouds, is a bloom in Bristol Bay. Credit: Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  11. Oligo-Miocene Deposition Along the Eastern Margin of the Altiplano Plateau, Salla, Bolivia

    NASA Astrophysics Data System (ADS)

    Leier, A. L.; Long, S.; McQuarrie, N.

    2006-12-01

    The Eastern Cordillera of the Bolivian Andes forms the eastern boundary of the Altiplano plateau, an internally- drained hinterland basin that occupies an area of 150,000 km2 and has an average elevation of 4 km. Almost all tectonic models of the region indicate an important causal relationship existed between early Tertiary deformation in the Eastern Cordillera and initial development of the Altiplano plateau. We examined Oligo- Miocene strata deposited along the eastern margin of the Altiplano plateau and within the Eastern Cordillera near the village of Salla (100 km south of La Paz) to constrain the depositional and deformational history of the region. Stratigraphic units in the study area consist of the Oligocene Luribay Conglomerate and the overlying Oligo-Miocene Salla Beds. The Luribay Conglomerate comprises up to 500 m of pebble- to boulder- conglomerate with interbedded coarse-grained sandstone. Clast-compositions, thicknesses, facies, and paleocurrent directions vary considerably between outcrop exposures. Conglomerate beds were deposited by gravity flows in alluvial fan settings and by traction transport in fluvial systems. Growth strata within the Luribay Conglomerate record syn-deformational deposition. The overlying Salla Beds consist of roughly 500 m of clay- and siltstone, with minor amounts of sandstone and rare conglomerate lenses. Extensive evidence of pedogenesis within the succession suggests the region was characterized by well-drained interfluve environments during Late Oligocene-Early Miocene time. Although the Salla Beds are folded and faulted, they are generally less deformed than the underlying Luribay Conglomerate. Deposition near Salla commenced during Oligocene time in a number of discrete basins separated from one another by topographic highs, which were produced by upper crustal folding and faulting in the west verging portion of the Andean fold-thrust belt. Sediments within these basins were derived from local sources and deposited

  12. Cultural inter-population differences do not reflect biological distances: an example of interdisciplinary analysis of populations from Eastern Adriatic coast

    PubMed Central

    Bašić, Željana; Fox, Ayano R; Anterić, Ivana; Jerković, Ivan; Polašek, Ozren; Anđelinović, Šimun; Holland, Mitchell M; Primorac, Dragan

    2015-01-01

    Aim To compare the population group from the Šopot graveyard with population groups from traditional Croatian medieval graveyards by using anthropological, craniometrics, and mitochondrial (mtDNA) analysis and to examine if the cultural differences between population groups reflect biological differences. Methods We determined sex, age at death, pathological, and traumatic changes of skeletal remains from the Šopot graveyard and compared them with a cumulative medieval sample from the same region. We also performed principal component analysis to compare skeletal remains from Šopot with those from Ostrovica and other Central European samples according to 8 cranial measurements. Finally, we compared 46 skeletons from Šopot with medieval (Ostrovica) and contemporary populations using mDNA haplogroup profiling. Results The remains from Šopot were similar to the cumulative sample in lifestyle and quality of life markers. Principal component analysis showed that they were closely related to Eastern Adriatic coast sites (including Ostrovica and Šopot) in terms of cranial morphology, indicating similar biological makeup. According to mDNA testing, Šopot population showed no significant differences in the haplogroup prevalence from either medieval or contemporary populations. Conclusion This study shows that the Šopot population does not significantly differ from other medieval populations from this area. Besides similar quality of life markers, these populations also had similar biological markers. Substantial archeological differences can therefore be attributed to apparent cultural influences, which in this case do not reflect biological differences. PMID:26088847

  13. Origins and movement of fluids during deformation and metamorphism in the canadian cordillera.

    PubMed

    Nesbitt, B E; Muehlenbachs, K

    1989-08-18

    Stable isotope data from quartz veins in the Canadian Cordillera indicate that crustal fluids were heterogeneous in terms of sources and flow paths during Mesozoic-Cenozoic metamorphism and deformation. In regions of strike-slip and extensional faulting, the fluid regime to depths of at least 15 kilometers was dominated by convected, chemically evolved meteoric water. In contrast, in thrust faulted regions, the fluid regime was dominated by fluids derived from metamorphic devolatilization reactions. Deep convection of meteoric water implies that fluid pressures are hydrostatic in such systems not lithostatic, as had been commonly assumed. The occurrence of significantly lower fluid pressures would necessitate reevaluation of the manner in which metamorphic phase equilibria and stress relations in the crust are modeled. In addition, this study indicates that mesothermal gold deposits in the Canadian Cordillera are a product of the meteoric water convection process.

  14. Metallogenesis and tectonics of the Russian Far East, Alaska, and the Canadian Cordillera

    USGS Publications Warehouse

    Nokleberg, Warren J.; Bundtzen, Thomas K.; Eremin, Roman A.; Ratkin, Vladimir V.; Dawson, Kenneth M.; Shpikerman, Vladimir I.; Goryachev, Nikolai A.; Byalobzhesky, Stanislav G.; Frolov, Yuri F.; Khanchuk, Alexander I.; Koch, Richard D.; Monger, James W.H.; Pozdeev, Anany I.; Rozenblum, Ilya S.; Rodionov, Sergey M.; Parfenov, Leonid M.; Scotese, Christopher R.; Sidorov, Anatoly A.

    2005-01-01

    The Proterozoic and Phanerozoic metallogenic and tectonic evolution of the Russian Far East, Alaska, and the Canadian Cordillera is recorded in the cratons, craton margins, and orogenic collages of the Circum-North Pacific mountain belts that separate the North Pacific from the eastern North Asian and western North American Cratons. The collages consist of tectonostratigraphic terranes and contained metallogenic belts, which are composed of fragments of igneous arcs, accretionary-wedge and subduction-zone complexes, passive continental margins, and cratons. The terranes are overlapped by continental-margin-arc and sedimentary-basin assemblages and contained metallogenic belts. The metallogenic and geologic history of terranes, overlap assemblages, cratons, and craton margins has been complicated by postaccretion dismemberment and translation during strike-slip faulting that occurred subparallel to continental margins. Seven processes overlapping in time were responsible for most of metallogenic and geologic complexities of the region (1) In the Early and Middle Proterozoic, marine sedimentary basins developed on major cratons and were the loci for ironstone (Superior Fe) deposits and sediment-hosted Cu deposits that occur along both the North Asia Craton and North American Craton Margin. (2) In the Late Proterozoic, Late Devonian, and Early Carboniferous, major periods of rifting occurred along the ancestral margins of present-day Northeast Asia and northwestern North America. The rifting resulted in fragmentation of each continent, and formation of cratonal and passive continental-margin terranes that eventually migrated and accreted to other sites along the evolving margins of the original or adjacent continents. The rifting also resulted in formation of various massive-sulfide metallogenic belts. (3) From about the late Paleozoic through the mid-Cretaceous, a succession of island arcs and contained igneous-arc-related metallogenic belts and tectonically paired

  15. Doctoring in Eastern Europe

    PubMed Central

    Wilde, Henry

    1983-01-01

    Health care in Eastern Europe has not achieved world standards nor the goals of planners of socialist societies. With luck, perseverance, bribes or good connections, it is possible to obtain good medical and surgical care in Eastern Europe for a major illness. Primary and even secondary care usually are substandard, however, and often completely unacceptable to most Western foreigners. The reasons for this are complex but mainly rooted in different attitudes of health workers towards their patients, poor physical plants, poor salary structures, inadequate advancement opportunities for health care workers, poor social status and professional recognition for nurses and almost complete isolation of the average primary care doctor from hospital medicine. PMID:6659504

  16. Modes of active deformation in Eastern Hispaniola

    NASA Astrophysics Data System (ADS)

    García-Senz, J.; Pérez-Estaún, A.

    2012-04-01

    Eastern Hispaniola and the Puerto Rico Island are the emerged part of a doubly vergent thrust wedge formed by oblique arc-continent collision with subduction and underthrusting of the North America Plate in the Puerto Rico trench and underthrusting of the Caribbean crust in The Muertos trough (Dolan et al. 1998, Mann et al., 2002, ten Brink et al. 2010). In the relatively small area of Eastern Hispaniola several types of active crustal deformation have been recognized: 1) At the prowedge of the orogene, the rear of the accretionary prism is cut by the strike-slip Septentrional Fault, bounding a sliver plate (Mann et al, 2002). Recent detailed mapping and aeromagnetic surveys in the onshore part of the prism (Samaná Peninsula and Septentrional Cordillera, Sysmin Team) revealed that the internal structure of the sliver is made of parallel bands of sigmoidal, left-lateral, NW-SE thrust splays, bounded by steep strike-slip faults. We interpreted these structures as transpressional strike-slip duplex. It is worth to note the similarity between the strike and dip of the thrust splays and the 303, 62, 74 focal mechanism calculated by Russo and Villaseñor (1995) for the thrust event of the August 4, 1946 Hispaniola earthquake. 2) The uplifted core of the orogen extends between the accretionary prism and the beginning of the Muertos retrowedge. Half of this area is occupied by the Oriental Cordillera, a recent uplift of cretaceous island-arc rocks arching the Late Neogene reef. The rest of the territory is the Caribbean Coastal Plain modelled on the Late Neogene reef. The Oriental Cordillera is made of two en echelon left-stepping uplifts: the domal-shaped Haitises and the rhombohedral-shaped Seibo (García-Senz et al, 2007); the latter share structural similarities and scaling relations with the 90° neutral stepover model of McClay and Bonora (2001). Therefore we interpret it as a restraining stepover developed over a blind splay of the Septentrional Fault, and the main

  17. The Columbia Plateau Revealed; Low Temperature Thermochronology Across the Canadian Cordillera and Links to Lithospheric Delamination.

    NASA Astrophysics Data System (ADS)

    Guest, B.; Bacque, D.; Miles, N.; Stockli, D. F.

    2014-12-01

    Active deformation and mountain building in the Canadian Cordillera ceased in the Paleogene, a period during which this orogen was among the highest on earth. The present morphology, relief and altitude of the mountains and the foothills in the adjacent foreland belt are the result of a feedback relationship between erosion and isostatic compensation. Our low temperature thermochronology data (U-Th/He ages on zircon and apatite) were collected from 5 sample-transects spanning the Intermontane, Omineca, Foreland, and Foothills belts along a Jasper-Vancouver transect. The data show rapid cooling (>15℃/Ma) from >180℃ to <70℃ in the interior belts to the west of the Rocky Mountain Trench (RMT) during the Eocene (56 - 33 Ma). In the Foreland and Foothills belts to the east of the RMT the data show modest cooling (~4℃/Ma) during the latest Cretaceous to Early Eocene (~80Ma - 55 Ma) followed by rapid cooling (~15℃/Ma) between ~55 Ma and ~45 Ma transitioning to slower cooling (~1℃/Ma) after 45 Ma. This cooling pattern is consistent with rapid regional uplift and exhumation across the interior belts of the Cordillera during a regional transition from contraction to extension in the early to middle Eocene. At the same time in the Foreland and Foothills belts, during a period of accelerated cooling, contraction was continuing. The combination of rapid exhumation and extension in the interior belts and rapid exhumation and contraction in the Foreland and Foothills belts is similar to what is observed around the Altiplano and Tibetan plateaus. This suggests that the Canadian Cordillera is a fossil plateau (Columbia Plateau) that formed in the Eocene. The lack of a mantle lithosphere beneath the interior belts of the Canadian Cordillera (west of the RMT) and the regional extent of rapid exhumation suggests that the Columbia Plateau formed in response to a large-scale lithosphere removal event; possibly wholesale delamination.

  18. Regional variations of mantle anisotropy across the Canadian Cordillera from teleseismic shear-wave splitting

    NASA Astrophysics Data System (ADS)

    Zandt, G.; Frassetto, A. M.; Cassidy, J. F.; Bostock, M. G.

    2009-12-01

    The Canadian Cordillera overlies a slab window developed after the cessation of ocean-continent subduction during the mid-Cenozoic. Widespread basaltic volcanism occurring over the last 20 million years throughout the Cordillera appears geochemically depleted when compared to magmas generated within continental lithosphere. Characterizing seismic anisotropy constrains ongoing deformation in the upper mantle beneath the Cordillera and provides an opportunity to investigate the potential source of these magmas. We use the rotation correlation, eigenvalue minimization, and energy minimization methods through the Splitlab software package to analyze teleseismic SKS phases recorded by seismometers deployed as part of the Batholiths and Nechako Experiments and increased regional monitoring. Splitting measurements collected across the central British Columbia, southeastern Alaska, and the southern Yukon reveal regional patterns in seismic anisotropy. Stations closest to the southern Denali and Queen Charlotte faults show large splitting times (1.5-2.0 s) along orientations consistent with the dextral transform between the North American and Pacific plates. Stations within the coastal region show generally null patterns. A robust pattern of east-west oriented splitting across the central Coast Mountains Batholith and Interior Plateau cannot be easily explained in terms of lithospheric structural fabric, and its regional coherency and magnitude (up to 1.5 s) indicates that a significant amount of anisotropy occurs within asthenospheric mantle. When combined with other geophysical and geochemical constraints, the pattern of anisotropy suggests upwelling and lateral flow of asthenosphere around the northern edge of the subducting Juan de Fuca slab. Asthenospheric flow into a complex slab window north of the Juan de Fuca plate would explain the lack of splitting seen in certain regions of the Cordillera and provide a mechanism for fueling the post-subduction volcanism observed

  19. Source terrains and diagenetic imprints of Cretaceous marine rocks of the Cordillera Oriental, Colombia

    SciTech Connect

    Segall, M.P.; Allen, R.B. ); Rubiano, J.; Sarmiento, L. )

    1993-02-01

    Cretaceous marine rocks of the western Cordillera Oriental of Colombia are exposed in stratigraphic sections which reveal multiple source terrains and variable diagenetic histories that were imposed by later thrusting XRD and petrographic analyses indicate that earliest Cretaceous rocks were derived from a nearly plutonic source (Triassic-Jurassic Ibague Batholith of the Cordillera Central) which provided feldspathic lithic fragments and clay-sized illite. High smectite concentrations in the overlying Hauterivian-Barremian strata reflect contemporaneous volcanism, possibly in the Cordillera Central. This signal decreased upsection to the upper Aptian, where detrital clays (kaolinite, chlorite, feldspar, amphibole) indicate a shift to a cratonic source, probably the Guayana Shield. Cratonic detrital input continues into the Turonian-Coniacian and is accompanies by high concentrations of smectite representing another period of volcanic activity. Later tectonic activity divided the area into two regions, each with unique diagenetic signatures. Three primary clastic sources are inferred for the section east of the thrust belt, however, the mineral assemblage is masked by later diagenesis. Sediments within the thrust belt show greater variability in the relative abundance of mineral assemblages and more poorly crystallized illite than occurs to the east of the thrust section. The preservation of much of the original mineralogic components within the thrust section indicates that these sediments have experienced only limited diagenetic overprinting as a result of a relatively short burial history. These contrasting signatures have important implications for hydrocarbon maturation within Cretaceous source rocks in a structurally complex region.

  20. Religion and Subjective Well-Being: Western and Eastern Religious Groups Achieved Subjective Well-Being in Different Ways.

    PubMed

    Shiah, Yung-Jong; Chang, Frances; Chiang, Shih-Kuang; Tam, Wai-Cheong Carl

    2016-08-01

    Culture can moderate which variables most influence subjective well-being (SWB). Because religion can be conceptualized as culture, religious differences can be considered cultural differences. However, there have been few studies comparing how different religious groups evaluate SWB at any given time. This study is among the first to investigate this issue. The present study compared Buddhists, Taoists, Christians, and atheists. In addition to demographic items, 451 Chinese adults completed Chinese version of the Socially Oriented Cultural Conception of SWB Scale. Religious belief was distributed as follows: 10 % Christian, 20 % Buddhist, 25 % Taoist, and 43 % atheists. As predicted, the socially oriented cultural conception of SWB was found to be highest among Buddhists, followed in order by Taoists, atheists, and Christians. It was concluded that the various religious groups achieved SWB in different ways.

  1. Timescale dependence of erosion rates, a case of study: Marinelli Glacier, Cordillera Darwin, southern Patagonia

    NASA Astrophysics Data System (ADS)

    Fernandez-Vasquez, R. A.; Anderson, J. B.; Wellner, J. S.

    2009-12-01

    Glaciers play a key role in understanding the coupling between tectonics and climate through a number of processes and temporal/spatial scales, ranging from short-term glacial advances and retreats and millennial-scale glacial cycles, to million year-scale orogenies and global climate changes. In particular, glacier erosion is a first order control on mountain range exhumation and isostatic processes through the evacuation and removal of crustal material from orogens and its subsequent transport to continental margins. Erosion rates and associated sediment yield have been estimated for a number of glaciated basins. With few exceptions, all of these estimations are based on modern observations (last few decades) of sediment fluxes, and may not represent long-term (centennial, millennial or million-year time scales) fluxes. Indeed, recent works indicate that contemporary high sediment yields and erosion rates might be the result of high ice fluxes associated with the retreat of modern glaciers from their last Neoglacial positions (Little Ice Age) and that long-term erosion rates could be derived by extrapolating the relationship between short-term erosion v/s retreat rates to the steady state condition of no retreat. However, there is an almost absolute lack of empirical studies that support this statement. We use time-constrained sediment volumes delivered by calving glaciers into Marinelli Fjord (55S), an outlet glacier of the Cordillera Darwin Ice Cap, Southern Patagonian Andes in Tierra del Fuego Island, to estimate sediment yields and erosion rates at different timescales. Sediment volumes are derived using a dense grid of high- and low-frequency single channel seismic data and swath bathymetry data along with piston and Kasten cores. Our results show dramatic differences in erosion rates over different timescales. The recent decadal erosion rate (= 29.31± 10.84 mm/yr; estimated for the last 45 years) is 5 times greater than the centennial value (= 5

  2. Genetic differentiation of octopuses from different habitats near the Korean Peninsula and eastern China based on analysis of the mDNA cytochrome C oxidase 1 gene.

    PubMed

    Kang, J-H; Park, J-Y; Choi, T-J

    2012-11-21

    Distributed along the coastal waters of Korea and China, Octopus minor is found in various habitats, including the mud flats in the southern and western coasts of the Korean Peninsula and the rocky areas around Jeju Island; however, the genetic relationships among the different populations are unknown and have not been studied. We compared 630-nucleotide sequences of the CO1 gene from O. minor specimens collected from five regions around the Korean Peninsula and three regions from eastern China in order to determine population structure and genetic relationships. Based on the sequences at 12 polymorphic sites in this region, 11 haplotypes were identified from 85 specimens. Individuals from Jeju Island had unique haplotypes, including two haplotypes not found in the other populations. Nucleotide and haplotype diversity for all populations ranged from 0.03-0.37 and 0.20-0.64, respectively. Pairwise F(ST) values indicated significant genetic differences in populations from Korea and China. An UPGMA dendrogram showed separation of the eight populations into three clusters; one included only the Jeju population, another included the rest of the Korean populations and some from Dalian, China; a third cluster consisted of two other populations from China. We conclude that there are discrete genetic differences in O. minor from the different habitats, suggesting that the populations should be considered as management units in the ongoing recovery program.

  3. Potentiometric surface and water-level difference maps of selected confined aquifers of Southern Maryland and Maryland's Eastern Shore, 1975-2011

    USGS Publications Warehouse

    Curtin, Stephen E.; Andreasen, David C.; Staley, Andrew W.

    2012-01-01

    Groundwater is the principal source of freshwater supply in most of Southern Maryland and Maryland's Eastern Shore. It is also the source of freshwater supply used in the operation of the Calvert Cliffs, Chalk Point, and Morgantown power plants. Increased groundwater withdrawals over the last several decades have caused groundwater levels to decline. This report presents potentiometric surface maps of the Aquia, Magothy, upper Patapsco, lower Patapsco, and Patuxent aquifers using water levels measured during September 2011. Water-level difference maps also are presented for the first four of these aquifers. The water-level differences in the Aquia aquifer are shown using groundwater-level data from 1982 and 2011, whereas the water-level differences in the Magothy aquifer are presented using data from 1975 and 2011. Water-level difference maps in both the upper Patapsco and lower Patapsco aquifers are presented using data from 1990 and 2011. These maps show cones of depression ranging from 25 to 198 feet (ft) below sea level centered on areas of major withdrawals. Water levels have declined by as much as 112 ft in the Aquia aquifer since 1982, 85 ft in the Magothy aquifer since 1975, and 47 and 71 ft in the upper Patapsco and lower Patapsco aquifers, respectively, since 1990.

  4. Factorial Kriging analysis and sources of heavy metals in soils of different land-use types in the Yangtze River Delta of Eastern China.

    PubMed

    Zhou, Jie; Feng, Ke; Li, Yinju; Zhou, Yang

    2016-08-01

    The objectives of this study are to analyse the pollution status and spatial correlation of soil heavy metals and identify natural and anthropogenic sources of these heavy metals at different spatial scales. Two hundred and twenty-four soil samples (0-20 cm) were collected and analysed for eight heavy metals (Cd, Hg, As, Cu, Pb, Cr, Zn and Ni) in soils of different land-use types in the Yangtze River Delta of Eastern China. The multivariate methods and factorial Kriging analysis were used to achieve the research objectives. The results indicated that the human and natural effects of different land-use types on the contents of soil heavy metals were different. The Cd, Hg, Cu, Pb and Zn in soils of industrial area were affected by human activities, and the pollution level of these heavy metals in this area was moderate. The Pb in soils of traffic area was affected by human activities, and eight heavy metals in soils of residential area and farmland area were affected by natural factor. The ecological risk status of eight heavy metals in soils of the whole study area was light. The heavy metals in soils showed three spatial scales (nugget effect, short range and long range). At the nugget effect and short range scales, the Cd, Hg, Cu, Pb and Zn in soils were affected by human and natural factors. At three spatial scales, the As, Cr and Ni in soils were affected by soil parent materials.

  5. U-Th-Pb geochronology of meta-carbonatites and meta-alkaline rocks in the southern Canadian Cordillera: A geodynamic perspective

    NASA Astrophysics Data System (ADS)

    Millonig, Leo J.; Gerdes, Axel; Groat, Lee A.

    2012-11-01

    U-Pb and Th-Pb ages of zircons from seven meta-carbonatite and three meta-alkaline rock samples provide evidence for three distinct episodes of carbonatite and alkaline magmatism in the southern Canadian Cordillera spanning a period of ~ 460 Ma. The earliest, Neoproterozoic event occurred at ~ 800-700 Ma and coincides with the postulated initial break-up of Rodinia. The second, previously undocumented, event of carbonatitic magmatism is constrained to the Late Cambrian at ~ 500 Ma and corresponds to a period of extensional tectonics that affected the western continental margin of North America from the Canadian Cordillera to the southwestern United States. The youngest and most prevalent period of alkaline igneous activity occurred in Late Devonian to Early Carboniferous times at ~ 360-340 Ma and resulted from extensional tectonics, presumably caused by slab rollback. In addition, different episodes of amphibolite-facies metamorphism subsequently affected the igneous rocks between ~ 155 and 50 Ma. This dataset puts new constraints on the timing of carbonatite and alkaline igneous activity and the evolution of (ancestral) North America's western continental margin from Neoproterozoic to Carboniferous times.

  6. Retrograde metasomatic effects on phase assemblages in an interlayered blueschist-greenschist sequence (Coastal Cordillera, Chile)

    NASA Astrophysics Data System (ADS)

    Halama, Ralf; Konrad-Schmolke, Matthias

    2015-02-01

    Interlayered blueschists and greenschists of the Coastal Cordillera (Chile) are part of a Late Palaeozoic accretionary complex. They represent metavolcanic rocks with oceanic affinities based on predominantly OIB-type REE patterns and immobile trace element ratios. Both rock types have similar mineralogies, albeit with different mineral modal abundances. Amphibole is the major mafic mineral and varies compositionally from glaucophane to actinolite. The presence of glaucophane relicts as cores in zoned amphiboles in both blueschists and greenschists is evidence for a pervasive high-pressure metamorphic stage, indicating that tectonic juxtaposition is an unlikely explanation for the cm-dm scale interlayering. During exhumation, a retrograde greenschist-facies overprint stabilized chlorite + albite + winchitic/actinolitic amphibole + phengitic white mica ± epidote ± K-feldspar at 0.4 ± 0.1 GPa. Geochemical variability can be partly ascribed to primary magmatic and partly to secondary metasomatic processes that occurred under greenschist-facies conditions. Isocon diagrams of several adjacent blueschist-greenschist pairs with similar protolith geochemistry were used to evaluate metasomatic changes due to retrograde fluid-rock interaction. The most important geochemical changes are depletion of Si and Na and addition of water in the greenschists compared to the blueschists. Transition metals and LILE are mobilized to varying degrees. The unsystematic deviations from magmatic fractionation trends suggest open system conditions and influx of an external fluid. Pseudosection and water isopleth calculations show that the rocks were dehydrating during most of their exhumation history and remained at water-saturated conditions. The mineralogical changes, in particular breakdown of blue amphibole and replacement by chlorite, albite and calcic/sodic-calcic amphibole, are the prime cause for the distinct coloring. Pseudo-binary phase diagrams were used as a means to link bulk

  7. Comparison between two vegetation indices for measuring different types of forest damage in the north-eastern United States

    NASA Technical Reports Server (NTRS)

    Vogelmann, J. E.

    1990-01-01

    The relative effectiveness of the Landsat TM-derived normalized difference vegetative index (NDVI) and the short-wave IR to NIR ratio (SWIR/NIR) index was examined in measurements of different types of damage in several forest communities. The forests examined included a site with well-defined fir waves in New Hampshire, a site undergoing well-documented coniferous forest decline in Vermont, and predominantly deciduous regions in Vermont and northwestern Massachusetts seriously impacted by pear thrips. Both NDVI and SWIR/NIR images were produced for each area. Results demonstrated that the SWIR/NIR index was superior to NDVI in distinguishing between high and low conifer damage at both fir-wave and forest decline sites; high and low deciduous-forest damage sites were easily separable using either NDVI or SWIR/NIR, but the NDVI was superior in separation between medium and low deciduous damage.

  8. Evaluation of strength parameters and quality assessment of different lithotype levels of Edremit (Van) Travertine (Eastern Turkey)

    NASA Astrophysics Data System (ADS)

    Erdoğan, Onur; Özvan, Ali

    2015-06-01

    Travertine deposits have an economic value due to their chemical composition and widespread use in the construction industry. Travertines reveal different lithotypes depending on their depositional process and this can affect mechanical and engineering properties of travertine. Edremit travertine displays various structural features in lateral and vertical distributions. In this study, Edremit travertine is firstly differentiated into three different levels such as crystalline crust, shrub and reed based on the mechanical, physical properties and field observations. A strength map of different lithotypes is prepared and crystalline crust level is investigated for using in marble industry. For this purpose, the long-term performance/durability of crystalline crust travertine is investigated against various environmental processes by using several accelerated weathering tests. Accordingly, compared to the crystalline crust other levels of travertine (shrub and reed) are much more affected from atmospheric conditions. Among these levels, the crystalline crust level is recommended to be used as marble according to laboratory test results whereas other levels are appropriate for cement industry.

  9. Lateralization in escape behaviour at different hierarchical levels in a gecko: Tarentola angustimentalis from Eastern Canary Islands.

    PubMed

    García-Muñoz, Enrique; Rato, Catarina; Jorge, Fátima; Carretero, Miguel A

    2013-01-01

    At the individual level, to be behaviourally lateralized avoids costly duplication of neural circuitry and decreases possible contradictory order from the two brain hemispheres. However, being prey behaviour lateralized at higher hierarchical levels could generate different negative implications, especially if predators are able to make predictions after multiple encounters. These conflicting pressures, namely between the advantages for individuals and the disadvantages for populations could be concealed if higher-level lateralization would arise from the combination of lateralized behaviours of individuals which are mutually dependent. Here, we investigated the lateralization patterns in the escape behaviour of the gecko Tarentola angustimentalis undergoing a predatory attack simulation in a "T" maze experiment. Results showed that gecko populations displayed different degrees of lateralization, with an overall dominance of right-biased individuals. This trend is similar to that observed in the Podarcis wall lizards, which share predators with Tarentola. In addition, different morphological parameters plausible to affect refuge selection were explored in order to link directional asymmetries at morphological level with lateralization during refuge selection.

  10. Above- and belowground controls on water use by trees of different wood types in an eastern US deciduous forest.

    PubMed

    Meinzer, Frederick C; Woodruff, David R; Eissenstat, David M; Lin, Henry S; Adams, Thomas S; McCulloh, Katherine A

    2013-04-01

    Stomata control tree transpiration by sensing and integrating environmental signals originating in the atmosphere and soil, and co-occurring species may differ in inherent stomatal sensitivity to these above- and belowground signals and in the types of signals to which they respond. Stomatal responsiveness to environmental signals is likely to differ across species having different types of wood (e.g., ring-porous, diffuse-porous and coniferous) because each wood type differs in the structure, size and spatial distribution of its xylem conduits as well as in the scaling of hydraulic properties with stem diameter. The objective of this study was to evaluate the impact of variation in soil water availability and atmospheric evaporative demand on stomatal regulation of transpiration in seven co-occurring temperate deciduous forest species representing three wood types. We measured whole-tree sap flux and soil and atmospheric variables in a mixed deciduous forest in central Pennsylvania over the course of a growing season characterized by severe drought and large fluctuations in atmospheric vapor pressure deficit (D). The relative sensitivity of sap flux to soil drying was ∼2.2-2.3 times greater in the diffuse-porous and coniferous species than in the ring-porous species. Stomata of the ring-porous oaks were only about half as responsive to increased D as those of trees of the other two wood types. These differences in responsiveness to changes in the below- and aboveground environment implied that regulation of leaf water potential in the ring-porous oaks was less stringent than that in the diffuse-porous angiosperms or the conifers. The results suggest that increases in the frequency or intensity of summer droughts in the study region could have multiple consequences for forest function, including altered successional time courses or climax species composition and cumulative effects on whole-tree architecture, resulting in a structural and physiological legacy that

  11. [Soil microorganisms, nutrients and enzyme activity of Larix kaempferi plantation under different ages in mountainous region of eastern Liaoning Province, China].

    PubMed

    Niu, Xiao-yun; Sun, Xiao-mei; Chen, Dong-sheng; Zhang, Shou-gong

    2015-09-01

    We studied the community of soil microorganisms, enzyme activity and soil nutrients under 11-, 20-, 34-and 47-year-old Larix kaempferi plantations in mountainous region of eastern Liaoning Province to discuss the soil biological properties of L. kaempferi plantations of different stand ages and their relationships with soil nutrients. The results showed that the indexes reflecting soil micro-organisms, enzyme activity and soil nutrients of L. kaempferi plantations were the highest under the 11- or 47-year-old stand and the lowest in the 20- or 34-year-old stand. Soil productivity appeared in a decline trend with the increasing stand age, and the changes of soil microbial community structure and enzyme activity were responsive to soil degradation. The difference of fungi community was more noticeable than that of bacteria community among the plantations with different stand ages. The results of CCA showed soil nutrient and pH had no effect on seasonal difference of community structure, but had effects on community, structure among different stand ages. The total N, organic carbon, C/N, available nitrogen, exchangeable Mg2+ and pH had greater effects on bacteria community, while available P, total K and pH had greater effect on fungi community among different age forests. The main T-RFs of bacteria and fungi had higher correlation with N and P, and the fungi community had higher correlation with organic carbon and K than bacteria community. The microor-ganism community of the 11- and 47-year-old stands had greater correlation with soil nutrients and enzyme activity than that of 20- and 34-year-old stands. Consequently, soil organisms, in particular soil fungi, could be used to indicate soil degradation.

  12. Coupling data from U-series and 10Be CRN to evaluate soil steady-state in the Betic Cordillera

    NASA Astrophysics Data System (ADS)

    Schoonejans, Jerome; Vanacker, Veerle; Opfergelt, Sophie; Granet, Mathieu; Chabaux, François

    2015-04-01

    The regolith mantel is produced by weathering of bedrock through physical and biochemical processes. At the same time, the upper part of the regolith is eroded by gravity mass movements, water and wind erosion. Feedback's between production and erosion of soil material are important for soil development, and are essential to reach long-term steady-state in soil chemical and physical properties. Nowadays, long-term denudation rates of regolith can be quantified by using in-situ cosmogenic nuclides (CRN). If the soil thickness remains constant over sufficiently long time, soil production rates can be determined. However, the a priori assumption of long-term steady-state can be questionable in highly dynamic environments. In this study, we present analytical data from two independent isotopic techniques, in-situ cosmogenic nuclides and Uranium series disequilibrium. The disequilibrium of Uranium isotopes (238U, 234U, 230Th, 226Ra) is an alternative method that allows assessing soil formation rates through isotopic analysis of weathering products. Nine soil profiles were sampled in three different mountain ranges of the Betic Cordillera (SE Spain): Sierra Estancias, Filabres, Cabrera. All soils overly fractured mica schist and are very thin (< 60cm). In each soil profile, we sampled 4 to 6 depth slices in the soil profile, the soil-bedrock interface and (weathered) bedrock. Three of the nine soil profiles were sampled for U-series isotope measurements at EOST (University of Strasbourg). The surface denudation rates (CRN) are about the same in the Sierra Estancias and Filabres (26 ± 10 mm/ky) and increase up to 103 ± 47 mm/ky in the Sierra Cabrera. The spatial variation in soil denudation rates is in agreement with the variation in catchment-wide denudation rates presented by Bellin et al. (2014) which present the highest rates in the Sierra Cabrera (104-246mm/kyr). Moreover it roughly coincides with the pattern of long-term exhumation of the Betic Cordillera. Results

  13. Dynamic response of the scenic beauty value of different forests to various thinning intensities in central eastern China.

    PubMed

    Deng, Songqiu; Yin, Na; Guan, Qingwei; Katoh, Masato

    2014-11-01

    Forest management has a significant influence on the preferences of people for forest landscapes. This study sought to evaluate the dynamic effects of thinning intensities on the landscape value of forests over time. Five typical stands in Wuxiangsi National Forest Park in Nanjing, China, were subjected to a thinning experiment designed with four intensities: unthinned, light thinning, moderate thinning, and heavy thinning. People's preferences for landscape photographs taken in plots under various thinning intensities were assessed through scenic beauty estimation (SBE) at 2 and 5 years after thinning. The differences in scenic beauty value between different thinning intensities were then analyzed with a paired samples t test for the two periods. The results indicated that the landscape value of all of the thinned plots significantly exceeded that of the unthinned plots 2 years after thinning (p < 0.01) and that the heavily thinned plots were most appreciated, showing an average improvement of 9.71 % compared with the control plots. Additionally, the heavily thinned plots were judged to be more beautiful than the lightly thinned and moderately thinned plots, whereas there was no significant difference between moderate thinning and light thinning. At 5 years after thinning, however, the moderately thinned plots received the highest preference scores among the four intensities, displaying an average improvement of 11.32 % compared with the unthinned plots. A multiple linear regression (MLR) model indicated that landscape value improved with increases in the average diameter at breast height (DBH) and with the improvement of environmental cleanliness in the stand, whereas the value decreased with an increasing stem density, species diversity, litter coverage, and canopy density. In addition, we found that the performance of a neural network model based on a multilayer perception (MLP) algorithm for predicting scenic beauty was slightly better than that of

  14. Comparison, cross-validation and consolidation of the results from two different geodynamic projects working in the eastern Carpathians

    NASA Astrophysics Data System (ADS)

    Ambrosious, B.; Dinter, G.; van der Hoeven, A.; Mocanu, V.; Nutto, M.; Schmitt, G.; Spakman, W.

    2003-04-01

    Since 1995 several projects/programmes are working in the Vrancea-region in Romania with partly different intensions. First of all, the CERGOP project installed the CEGRN-network and performed GPS-measurements ('95,'96,'97,'99,'01), mainly to realise a geodetic reference frame for local geodynamic projects. In the framework of the Collaborative Research Center CRC461 "Strong Earthquakes" the Geodetic Institute of the University Karlsruhe (GIK) Densified the network up to 35 stations and carried out three GPS-campaigns ('97, '98 and '00). First results of this project were presented at the EGS-meeting 2001 in Nice. In 2002 a new geodynamic research project was initiated at the Delft Institute of Earth-Oriented Space Research (DEOS). In the context of this project, 4 permanent stations and 10 new campaign stations were installed, which leads to a common network of about 50 stations. In tight cooperation with the GIK and the University of Bucarest (Departement of Geophysics) the currently last GPS-campaign was successfully carried out in 2002. Now the great challenge and at the same time the great difficulty is a correct combination of all available GPS datasets particularly in consideration of station excentricities and variations of antenna- and receiver-types. Different evalutation strategies and software packages (Bernese-GPS-Software, GIPSY) were used to analyse the GPS data and to estimate the station velocities. Main focus of this joint-presentation is the comparison of the results from the German and Dutch geodynamic projects. The results of the two working groups are cross-validated and finally joined together in a most reasonable solution. Even if three-dimensional analysis is in work, the presentation is limited to the horizontal component.

  15. Prevalence of common gastrointestinal nematode parasites in scavenging pigs of different ages and sexes in eastern centre province, Burkina Faso.

    PubMed

    Tamboura, H H; Banga-Mboko, H; Maes, D; Youssao, I; Traore, A; Bayala, B; Dembele, M A

    2006-03-01

    The range and infestation intensities of gastrointestinal parasitic nematode species depend on the type of swine production system. The present study focused mainly on nematodes of veterinary importance in scavenging pigs in Burkina Faso, and aimed at determining the prevalence of gastro-intestinal nematode parasites by means of faecal egg per gram (EPG) counts. Between November 2001 and October 2002, faecal samples from 383 pigs of different sexes and ages (< 5 months, 5-12 months and > 12 months) were collected from the rectum and examined for gastrointestinal nematodes parasites using the Mc Master method. Of the 383 pigs examined, 91% were infected by one or more parasites. Ascaris suum (40%; 100-1 400 EPG) was the most prevalent parasite followed by Strongyloides ransomi (21%; 100-4200 EPG), Oesophagostomum spp. (18%; 100-1000 EPG), Hyostrongylus rubidus (11%; 100-1 800 EPG), Globocephalus spp. (10%; 100-400 EPG) and Trichuris suis (1 %; 100-200 EPG). The prevalence was significantly higher in female pigs (n = 239) than in males. In addition, females excreted significantly (P < 0.05) more eggs in their faeces than males, except in the case of Globocephalus spp. The age of the animal had no effect on the prevalence of A. suum whereas there were significant differences in age categories concerning S. ransomi, H. rubidus, Oesophagostumum spp. and Globocephalus spp. Unexpectedly, the high prevalence of these common parasites was not accompanied by elevated EPG values, which suggests the existence of moderate infestations. The present work indicates that the common nematode infestations in pigs do not necessarily need a systematic herd anthelmintic treatment, as only a small number of worms is required to induce immunity. A further study is needed to formulate appropriate and cost-effective strategies for the control of gastro-intestinal nematode parasites in pigs in Burkina Faso.

  16. Surface-exposure Dating of Late Quaternary Glacial Advances in the Cordillera Blanca, Peruvian Andes (9°-10°S)

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Zehner, S. P., Jr.; Bowen, D. R.; Rodbell, D. T.

    2013-12-01

    New 10Be surface-exposure ages from boulders on lateral moraines bordering Querococha Valley (9°44.6' S, 77°21.6' W) in the southern Cordillera Blanca, Peru, indicate that late-glacial (˜16 ka) ice extended as much as 15 km downvalley from the headwall(s). With the glacier terminus at ˜3900 masl and the headwall at ˜5200 masl, THAR reconstruction (THAR=0.45) places the late-glacial equilibrium-line altitude (ELA) at ˜4485 masl, as compared to an estimated modern ELA of ˜5100 masl. The late-glacial Querococha advance was coeval with late-glacial advances at the Nevado Jeulla Rajo (NJR) massif at the southern end of the Cordillera Blanca (10°00'S, 77°16'W; peaks ˜5600 masl), ˜35 km to the south, where we have dated multiple moraines. Surface-exposure ages (10Be) indicate that the largest lateral moraines from Jeullesh Valley at NJR are compound features deposited during both the local last glacial maximum (˜30 ka) and a late-glacial readvance (˜15 ka). Late-glacial moraines are the largest lateral moraines in neighboring Quenua Ragra and Tuco valleys. The timing of the late-glacial advances in the Cordillera Blanca suggests a link to increased precipitation associated with Heinrich Event I (˜17 ka). Additional new 10Be surface-exposure ages from boulders on a moraine crossing a side valley in the upper reaches of Jeullesh Valley are early Holocene (˜9-11 ka), suggesting retreat of 3-4 km from the late-glacial terminal position in ˜4 kyr. Using the same THAR methodology, the late-glacial ELA in Jeullesh Valley was ˜4815 masl and the early Holocene ELA was ˜4995 masl. The active, west-dipping Cordillera Blanca Normal Fault (CBNF) vertically offsets the crests of 10Be-dated moraines in six valleys where we have profiled CBNF scarps: Jeullesh, Quenua Ragra, and Tuco valleys in the NJR massif; and Llaca, Cojup, and Querococha valleys in the south-central Cordillera Blanca (9°28'-45'S, 77°28'-21'W). In Jeullesh Valley, the CBNF scarp offsets both late

  17. Cross-sectional Biomonitoring of Metals in Adult Populations in Post-war Eastern Croatia: Differences Between Areas of Moderate and Heavy Combat

    PubMed Central

    Jergović, Matijana; Miškulin, Maja; Puntarić, Dinko; Gmajnić, Rudika; Milas, Josip; Sipos, Laszlo

    2010-01-01

    Aim To determine differences in metal and metalloid exposure between residents of areas in eastern Croatia exposed to heavy fighting during the war in Croatia and residents of areas exposed to moderate fighting. Methods Concentrations of aluminum (Al), arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), uranium (U), vanadium (V), and zinc (Zn), reported to be associated with military operations, were determined in hair, serum, and urine samples using inductively-coupled plasma mass spectroscopy. A total of 127 and 46 participants from areas of heavy and moderate fighting, respectively, were included. Results Compared with participants from areas exposed to moderate fighting, participants from areas exposed to heavy fighting had significantly higher serum concentrations of Al (87.61 vs 42.75 μg/L, P = 0.007), As (5.05 ± 1.79 vs 4.16 ± 1.55 μg/L, P = 0.003), Ba (7.12 vs 6.01 μg/L, P = 0.044), and V (17.98 vs 16.84 μg/L, P = 0.008); significantly higher urine concentrations of As (43.90 vs 11.51 μg/L, P < 0.001) and Cd (0.67 vs 0.50 μg/L, P = 0.031); and significantly higher hair concentrations of Al (12.61 vs 7.33 μg/L, P < 0.001), As (0.32 vs 0.05 μg/L, P < 0.001), Cd (0.03 vs 0.02 μg/L, P = 0.002), Fe (22.58 vs 12.68 μg/L, P = 0.001), Pb (1.04 vs 0.69 μg/L, P = 0.006), and V (0.07 vs 0.03 μg/L, P < 0.001). Conclusion Differences between populations from eastern Croatian areas exposed to heavy and populations exposed to moderate fighting point to the need for extensive monitoring of metal and metalloid exposure, emphasizing the role of biomonitoring through ecologic and preventive activities. PMID:20960595

  18. Crustal root beneath the Rif Cordillera as imaged from both active seismic data and teleseismic receiver functions.

    NASA Astrophysics Data System (ADS)

    Diaz, Jordi; Gil, Alba; Gallart, Josep; Carbonell, Ramon; Harnafi, Mimoun; Levander, Alan

    2015-04-01

    The Rif cordillera forms, together with the Betic ranges, one of the tightest orogenic arcs on Earth. This continental boundary zone is dominated now by the slow convergence between Nubia and Eurasia, but with clear evidences of extensional tectonics. One of the missing elements to constrain the complex geodynamics of the Gibraltar Arc System is the knowledge of the crustal architecture beneath northern Morocco. In the last decade a major effort has been done in this sense, from active and passive seismics. We compile here the recent results available from the Rif domains. Two 330 km long wide angle DSS profiles were recorded end of 2011 across the Rif in NS and EW transects within the Rifsis project, complemented by onshore recordings of the Gassis-WestMed marine profiles. At the same period, BB seismic arrays were deployed in the area within Topo-Iberia and Picasso projects, allowing receiver function analyses of crustal depths. The ray-tracing modeling of the Rifsis profiles reveal a large Moho step and an area of crustal thickening both in EW and NS directions, grossly coincident with the Bouguer gravity anomalies. The deployment logistics allowed that all the stations recorded all the shots, thus providing useful offline data. We will use here all available in-line and offline data to provide a map of the crustal thickness in northern Morocco. We combined two approaches: i) a hyperbolic time reduction applied to the seismic data, resulting in low-fold stacks in which the reflections from the Moho should appear as subhorizontal lines; ii) the arrival times of the observed PmP phases allow, assuming a mean crustal velocity, to assign a midpoint crustal thickness to each lecture. Although some uncertainties may be inherent to those approaches, a large crustal root, reaching more than 50 km, is well documented in the central part of the Rif Cordillera, close to the zone where the Alboran slab may still be attached to the lithosphere. We also compared these results

  19. Tectonic provinces and different types of hydrocarbon traps in the maturin sub-basin, Eastern Venezuela Basin

    SciTech Connect

    Gonzalez, A.; Fuentes, J.; Navarro, J.; Lander, R. )

    1993-02-01

    During the Oligo-Miocene, the transcollision of the Caribbean and South American plates, caused the northern flank of the Maturin Sub-basin to deform. This geodynamic process transformed the original passive margin basin into a foreland basin. As a result, the tectonic elements that distinguish this basin can be subdivided into three categories, the allochthonous block, the parautochthonous block and thrust belt, and the authochthonous block. The integrated interpretation of 7000 Km of seismic data and 25 wells has enabled us to elucidate the structural framework of the basin. A [open quotes]forward breaking[close quotes] sequence is proposed starting at the Pirital Thrust in the north and ending at the Furrial-Tejero Thrust in the south. However, the presence of a Post-Middle Miocene unconformity, folding of Early-Middle Miocene sediments and the development of a back thrust and its subsequent delta zone strongly suggests that movement towards the north also occurred. Between the Pirital and Tala faults, a lateral ramp known as the Urica fault, separates two zones that have been deformed by different mechanisms. The Urica fault has been interpreted by several authors as a dextral strike-slip fault. Hydrocarbons occur in three areas. The most important province occurs in the parautochthonous blocks with hydrocarbons occurring in cylindrical folds associated with the thrusts. To the south, conical folds associated with a strike-slip fault zone form good structural traps. The traditional Oficina fields lie still further south, in an area of normal faulting lightly affected by the Oligo-Miocene plate collision to the north.

  20. Soil properties and species composition under different grazing intensity in an alpine meadow on the eastern Tibetan Plateau, China.

    PubMed

    Yang, Zhen'an; Xiong, Wan; Xu, Yingyi; Jiang, Lin; Zhu, Erxiong; Zhan, Wei; He, Yixin; Zhu, Dan; Zhu, Qiuan; Peng, Changhui; Chen, Huai

    2016-12-01

    As the main form of land use and human disturbance of grassland, livestock grazing has great influences on the soil resources and plant communities. This study observed the variation of soil properties and community characteristics of four treatments of different grazing intensity (no grazing, UG; light grazing, LG; moderate grazing, MG; and heavy grazing, HG) in an alpine meadow of Sichuan Province on the northeastern margin of the Tibetan Plateau. The results showed that grazing increased the pH, soil bulk density (BD), and contents of total carbon (TC) and total nitrogen (TN), and the BD increased while the others decreased with the grazing intensity. At the community level, with the increase of the grazing intensity, the vegetation coverage (R (2) = 0.61, P < 0.001), mean height of community (R (2) = 0.37, P < 0.001), aboveground biomass (R (2) = 0.54, P < 0.001), litter biomass (R (2) = 0.84, P < 0.001), and percentage of aboveground biomass of palatable grasses to total biomass (R (2) = 0.74, P < 0.001) significantly decreased, while the belowground biomass (R (2) = 0.72, P < 0.001) and the root/shoot (R/S) ratio (R (2) = 0.65, P < 0.001) increased. The species richness was the greatest at LG and the total biomass at UG. With grazing, the dominant species of the plant community shifted from palatable grasses (Gramineae and Cyperaceae) to unpalatable grasses (Compositae and Ranunculaceae). Based on the results, LG may be the optimal grassland management mode to be used in the long time in the alpine meadow of the Tibetan Plateau.

  1. Growth and reproductive ecology of the eastern brook trout, Salvelinus fontinalis, in streams of differing vulnerability to acidic atmospheric deposition

    SciTech Connect

    Light, R.W.

    1983-01-01

    Three naturally infertile streams of differing vulnerability to acidic atmospheric deposition were studied to determine the status of their brook trout, Salvelinus fontinalis, populations and associated benthic communities. Of the three streams, Upper Three Runs was judged to be the least fertile, followed by Little Fishing Creek, with Roaring Run being the most fertile. The median weighted pH of acidic deposition impacting the watersheds was 3.8 for Upper Three Runs and 4.0 for Little Fishing Creek and Roaring Run. Brook trout from Roaring Run grew at a similar rate to those from Little Fishing Creek, with trout from Upper Three Runs showing the slowest growth. Roaring Run brook trout also had the highest relative condition of the three streams. Brook trout from Roaring Run and Little Fishing Creek generally matured one year later (age group II) than those from Upper Three Runs. Early maturity may be selected for in Upper Three Runs due to small annual increases in fecundity in higher age groups. Although the data were limited, there was a trend for brook trout from Upper Three Runs to produce fewer and larger ova. Roaring Run had higher volumes of benthos during fall and summer, and higher numbers during fall. Roaring Run and Little Fishing Creek had more, larger crayfish present, which added significantly to the volume of benthos in these streams. Qualitatively, Upper Three Runs had more shredders and fewer scrapers on a volume basis than the other two streams. On a per fish basis, the drift available to the fish in Roaring Run was always highest in volume, and highest in number during fall and spring. The brook trout from Roaring Run therefore had an advantage over those in the other two streams, by having a higher drift available per fish.

  2. [Pollution distribution and potential ecological risk assessment of heavy metals in sediments from the different eastern dredging regions of Lake Taihu].

    PubMed

    Mao, Zhi-Gang; Gu, Xiao-Hong; Lu, Xiao-Ming; Zeng, Qing-Fei; Gu, Xian-Kun; Li, Xu-Guang

    2014-01-01

    In order to investigate the distribution characteristics of nutrients and heavy metals in sediments from different eastern dredging regions of Lake Taihu, the surface and core sediment samples at 5 sites (in East Taihu Lake and Xukou Bay) were collected in 2012. Contents of nutrients (TOC, TN and TP) and heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in the sediments were measured and the pollution degrees of heavy metals were evaluated with the potential ecological risk method. The results showed that the heavy metal contents in Xukou Bay were generally higher than those in East Taihu Lake, whereas the nutrients contents showed the reverse trend. There were significant differences between the phytoplankton-dominated and culture lake regions. The concentrations of both nutrients and heavy metals decreased with increasing profile depth. Moreover, the contents of nutrients and heavy metals in the sediments of all dredged areas were lower than those in the un-dredged areas, suggesting that dredging may be a useful approach for decreasing nutrients and heavy metals loading in sediments, but its effectiveness decreased with time. Significant positive correlations were found among different heavy metals and nutrients, indicating that they were from the same pollution source. The Hakanson potential ecological risk index was applied for assessing the status of sediment heavy metal enrichment and the result indicated that sediment dredging could reduce the extent of potential ecological risk. The risk index in different sites followed the order: X1 > D1 > D3 > X2 > D2, while the risk index in site X1 of Xukou Bay was higher than that in site D1 of East Taihu Lake. And the comprehensive ecological risk grades in sites X1 and D1 were in the moderate range, while the sites D2, D3 and X2 were low.

  3. Regression of the level of different heavy metals to size of marine organisms harvested from the "Jiyeh" oil spill zone of the eastern Mediterranean Sea.

    PubMed

    Barbour, Elie K; Shaib, Houssam A; Yaghi, Ryan H; Sabra, Alia H

    2009-08-01

    This study aimed to establish a baseline data on regression of the levels of Lead (Pb), Nickel (Ni) and Vanadium (V) to specific size dimensions of selected marine organisms harvested from an oil spill zone of the Eastern Mediterranean Sea. Twenty samples of each of Siganus rivulatus, Mullets and oysters were collected from each of six harvest sites. A total of 1, 3, and 3 respective significant regression equations (p < 0.01) were established between Pb, Ni, V and specific size dimensions of the selected marine organisms. The significant correlation associated with the highest R (2) value was obtained between the Pb (y) level and the width (x) of the Siganus rivulatus (y = -86.833x + 417.72). The other six statistically significant correlations were associated with lower values of R (2) ranging between 0.338 and 0.380. This baseline data will be used in the future to evaluate the self-purification process of pollutants in different sizes of indicator-marine organisms in this part of the Mediterranean Sea.

  4. Resolving the tectonic transition between ancestral North America and the northern Cordillera

    NASA Astrophysics Data System (ADS)

    Schaeffer, A. J.; Audet, P.; Lebedev, S.

    2015-12-01

    The northern Cordillera, situated in the Canadian northwest, is one of the most actively deforming regions in Canada and host to the highest earthquake activity in the country. Furthermore, it presents a largely contiguous snapshot through almost 4 Gyr of Earth's history across a zone <2000 km in linear extent. Deformation is thought to be driven by tectonic forces transferred from the Alaska-Pacific plate collision eastwards to the Cordilleran Deformation Front (CDF), where the westward edge of the Canadian Shield acts as a rigid backstop. Past studies in the southern Yukon indicate a sharp transition into the craton underlying the CDF and evidence of craton growth through shallow subduction. Further north the proximity of the craton edge to the CDF remains largely unresolved; based on studies of the southern Cordillera and Alaska, significant variations in lithospheric architecture are expected. Additionally, significant seismicity is observed further north off the Beaufort Shelf; however, its relationship to the regional stress fields and associated tectonic forcing is unclear. Despite the high seismicity levels across, detailed study of this region has been limited by insufficient coverage of seismological infrastructure, hindering resolution in past models. With the deployment of the USArray Transportable Array in Alaska over the last several years, combined with regional arrays such as the Yukon-Northwest Seismic Network (YNSN), Banks Island Seismic Network (BISN) and Mackenzie Mountains Experiment, new studies will leverage these datasets enabling more detailed imaging of the structure and seismicity across the region. Here we present a new high-resolution, vertically polarized shear speed and azimuthal model of northwestern Canada and Alaska, constrained by vertical component seismogram fits computed using the Automated Multimode Inversion of Surface, S, and multiple-S waveforms. With this new model, we aim to address key questions relating to the dynamics

  5. Lithofacies control in detrital zircon provenance studies: Insights from the Cretaceous Methow basin, southern Canadian Cordillera

    USGS Publications Warehouse

    DeGraaff-Surpless, K.; Mahoney, J.B.; Wooden, J.L.; McWilliams, M.O.

    2003-01-01

    High-frequency sampling for detrital zircon analysis can provide a detailed record of fine-scale basin evolution by revealing the temporal and spatial variability of detrital zircon ages within clastic sedimentary successions. This investigation employed detailed sampling of two sedimentary successions in the Methow/Methow-Tyaughton basin of the southern Canadian Cordillera to characterize the heterogeneity of detrital zircon signatures within single lithofacies and assess the applicability of detrital zircon analysis in distinguishing fine-scale provenance changes not apparent in lithologic analysis of the strata. The Methow/Methow-Tyaughton basin contains two distinct stratigraphic sequences of middle Albian to Santonian clastic sedimentary rocks: submarine-fan deposits of the Harts Pass Formation/Jackass Mountain Group and fluvial deposits of the Winthrop Formation. Although both stratigraphic sequences displayed consistent ranges in detrital zircon ages on a broad scale, detailed sampling within each succession revealed heterogeneity in the detrital zircon age distributions that was systematic and predictable in the turbidite succession but unpredictable in the fluvial succession. These results suggest that a high-density sampling approach permits interpretation of finescale changes within a lithologically uniform turbiditic sedimentary succession, but heterogeneity within fluvial systems may be too large and unpredictable to permit accurate fine-scale characterization of the evolution of source regions. The robust composite detrital zircon age signature developed for these two successions permits comparison of the Methow/Methow-Tyaughton basin age signature with known plutonic source-rock ages from major plutonic belts throughout the Cretaceous North American margin. The Methow/Methow-Tyaughton basin detrital zircon age signature matches best with source regions in the southern Canadian Cordillera, requiring that the basin developed in close proximity to the

  6. Miocene latitudinal climatic and topographic variability within the central North American Cordillera

    NASA Astrophysics Data System (ADS)

    Gébelin, Aude; Mulch, Andreas; Teyssier, Christian; Heizler, Matthew

    2010-05-01

    The long-term climatic evolution and atmospheric circulation patterns of the Earth are influenced by the topography of large mountain chains whose topography is in turn controlled by links and feedbacks of surface processes and those acting within the Earth's interior. Stable isotopes in precipitation change systematically with elevation in many modern mountain ranges and have become an increasingly important tool in reconstructing the long-term topographic and climatic evolution of the world's largest mountain ranges. Here, we present stable isotope data from meteoric fluids trapped in orogen-scale deformation zones and associated fault-bounded basin sediments that record paleoelevation and also link the geodynamics of orogens with the overall long-term landscape and climate histories. To reconstruct the Cenozoic paleoelevation history of the central part of the North American Cordillera, we focus on the metamorphic core complexes of the Snake Range (Nevada) and Buckskin Mountains (Arizona). The Snake Range and Buckskin Mountains represent both classic examples of normal fault-bounded metamorphic core complexes that developed as a consequence of Oligocene Miocene extension of the Basin and Range Province. Synkinematic muscovites collected systematically over the top-300 m of section within the Snake Range detachment reveal a pattern of increasingly younger 40Ar/39Ar ages (26.9 Ma to 21.3 Ma) from the top to the bottom of the detachment. Across the same section dD muscovite values as low as -150 per mil occur at the top of the detachment zone and attain progressively higher values of up to -72 per mil towards the bottom of the section. This hydrogen stable isotope trend suggests that meteoric fluids percolated 10s to 100s of meters into the ductile segment of the detachment over the time scale of mylonitic deformation (ca. 27 to 23 Ma). In contrast, dDmuscovite values of similarly aged mylonitic quartzites from the Buckskin Mountains are much higher and range

  7. Pedological and mineralogical investigations on a soil-paleosoil sequence within Andosols in the Western Cordillera of the Peruvian Andes (region Laramate, 14.5S)

    NASA Astrophysics Data System (ADS)

    Leceta Gobitz, Fernando; Mächtle, Bertil; Schukraft, Gerd; Meyer, Hans-Peter; Eitel, Bernhard

    2016-04-01

    An integrated research project of environmental sciences focuses on a group of four Andosol profiles in Western flank of the Peruvian southern Andes. Aim of this study is to contribute to the reconstruction of the paleo environmental conditions in the Western Cordillera of the Peruvian Andes. Standard pedological and sedimentological analysis has been conducted in order to identify morphological and geochemical features generated by climatic variations during the middle and late Holocene. Though a provenance analysis of sediments, all potential lithological sources around the town of Laramate are being examined under the scanning electron microscope, in order to find significant mineralogical associations downward the soil-profile. Preliminary results reveal two edaphic cycles within a soil-paleo soil-sequence: a relative poor developed "Ah" topsoil, mostly composed by fine grain sediments, is underlain by a well preserved "2Ah" paleo soil; a "2Bwt" subsoil exhibits signs of alteration and clay translocation; parent material in slight weathered statement at "2C" culminates the sequence. Mineralogical analytical data supports the premise, that materials in the uppermost horizons are relatable to distal geological units of the Western and Eastern Cordillera, therefore also related to other described aeolian archives from the region: "Desert Margin Loess" at the Andean foot-zone and "Mixed Loess" in the Puna grassland. The amphibole varieties Actinolite, Mg-Hornblende and Edenite could be only distinguished within the soil sediments. The fluvial transport to its current position is excluded, insofar mentioned varieties stem from the granodiorites of Coastal Batholite (downstream the study area), and the vulcanites of the Anta und Andahuaylas Formation (eastward the continental divide). References: Eitel, B., et al. (2005). "Geoarchaeological evidence from desert loess in the Nazca-Palpa region, southern Peru : Palaeoenvironmental changes and their impact on Pre

  8. Superposition of tectonic structures leading elongated intramontane basin: the Alhabia basin (Internal Zones, Betic Cordillera)

    NASA Astrophysics Data System (ADS)

    Martínez-Martos, Manuel; Galindo-Zaldivar, Jesús; Martínez-Moreno, Francisco José; Calvo-Rayo, Raquel; Sanz de Galdeano, Carlos

    2017-01-01

    The relief of the Betic Cordillera was formed since the late Serravallian inducing the development of intramontane basins. The Alhabia basin, situated in the central part of the Internal Zones, is located at the intersection of the Alpujarran Corridor, the Tabernas basin, both trending E-W, and the NW-SE oriented Gádor-Almería basin. The geometry of the basin has been constrained by new gravity data. The basin is limited to the North by the Sierra de Filabres and Sierra Nevada antiforms that started to develop in Serravallian times under N-S shortening and to the south by Sierra Alhamilla and Sierra de Gádor antiforms. Plate convergence in the region rotated counter-clockwise in Tortonian times favouring the formation of E-W dextral faults. In this setting, NE-SW extension, orthogonal to the shortening direction, was accommodated by normal faults on the SW edge of Sierra Alhamilla. The Alhabia basin shows a cross-shaped depocentre in the zone of synform and fault intersection. This field example serves to constrain recent counter-clockwise stress rotation during the latest stages of Neogene-Quaternary basin evolution in the Betic Cordillera Internal Zones and underlines the importance of studying the basins' deep structure and its relation with the tectonic structures interactions.

  9. Latest extension of the Laujar fault in a convergence setting (Sierra Nevada, Betic Cordillera)

    NASA Astrophysics Data System (ADS)

    Martínez-Martos, Manuel; Galindo-Zaldívar, Jesus; Sanz de Galdeano, Carlos; García-Tortosa, Francisco Juan; Martínez-Moreno, Francisco José; Ruano, Patricia; González-Castillo, Lourdes; Azañón, José Miguel

    2017-02-01

    The present-day relief of the Betic Cordillera formed since the Late Miocene through the regional N-S to NW-SE Africa-Eurasia convergence that developed large folds. The Laujar Fault Zone is a south-dipping E-W oriented structure located at the northern boundary of the Alpujarran Corridor Neogene intramontane basin, which separates Sierra Nevada and Sierra de Gador antiforms, in the Internal Zones of the Betic Cordillera. The fault zone acted in a first stage as a dextral strike-slip fault. Currently it moves as a normal fault evidenced by striated calcretes, also in agreement with regional continuous GPS (CGPS) data that support the hypothesis of an active N-S extension in the fault area. In order to analyse the deep geometry of the Laujar Fault Zone, we combined several geophysical techniques (gravity, magnetic, electric resistivity tomography and audio-magnetotelluric data) with field geological observations. Fault surfaces seem to join at a southward-dipping shallow detachment level, including faults covered by the sedimentary infill. The fault zone was developed in a previously weakened area by wrench faults parallel to the Alpujarran Corridor. The recent normal activity of this fault zone may be a consequence of a change in the Africa-Eurasia convergence orientation, which implies a decrease in the N-S compression component. This structure along the southern limb of Sierra Nevada antiform evidences the gravitational collapse of previously thickened crust in a regional compressional context simultaneous to metamorphic core uplift.

  10. Polyphase rifting within Rodinia as seen through multiple episodes of mafic volcanism within the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Cox, G. M.; Halverson, G. P.; Roots, C. F.; MacDonald, F. A.; Plavsa, D.

    2010-12-01

    Neoproterozoic continental flood basalts (CFB) are known from the North American Cordillera and are thought to be associated with the breakup of Rodinia. However, unlike the short eruptive timeframe of Phanerozoic flood basalt provinces, instances of Neoproterozoic CFB within the North American Cordillera are separated by the unusually long time interval of ca 56 My (ca 780 Ma Gunbarrel Event and the ca 717 Ma Franklin Igneous Event), suggestive of poly-phase rifting and a long lived thermal anomaly and/or fertile mantle situated under ancient Laurentia. The Neoproterozoic Tatonduk Inlier, spanning the Alaskan-Yukon border, preserves both mafic volcanics (Pleasant Creek Volcanics) and a large arcuate dyke swarm (Tindir Dyke Swarm). Previous K/Ar dates on the dikes ranging from 532 ± 11 Ma to 644 ± 18 Ma appear to be inconsistent with geological constraints and correlations between the Tatonduk strata and the Neoproterozoic sequence of the well-dated Coal Creek Inlier to the east. We present geochemical data and discuss age and correlative constraints on these mafic rocks and relate these results in terms of the breakup history of Rodinia, timing of mafic magmatism within the possible conjugate margins to Neoproterozoic Laurentia (e.g. Australia and South China) and the role of a mantle plume in the rifting of Rodinia.

  11. Setting and occurrence of Late Paleozoic radiolarians in the Sylvester allochthon, part of a proto-Pacific ocean floor terrane in the Canadian Cordillera

    USGS Publications Warehouse

    Harms, T.A.; Murchey, B.L.

    1992-01-01

    Late Paleozoic radiolarians have been used to establish th allochthon of the Slide Mountain terrane in British Columbia, and have thereby greatly clarified the geology and tectonic history of the terrane. As the Sylvester radiolarian fauna is limited, age assignments were based on a few distinctive and diagnostic robust forms. Radiolarians occur in cherts from a wide variety of different oceanic sequences that are structurally juxtaposed within the Sylvester allochthon. Like others in a suite of correlative terranes that lie along the length of the Cordillera, the Sylvester allochthon and the radiolarian bearing cherts in it derive from the telescoping together of slices from what was, in the late Paleozoic, a large area of the proto-Pacific ocean. ?? 1992.

  12. Precambrian crust and lithosphere beneath the Northern Canadian Cordillera discovered by LITHOPROBE seismic reflection profiling

    NASA Astrophysics Data System (ADS)

    Clowes, R. M.; Cook, F. A.; Snyder, D. B.; van der Velden, A. J.; Hall, K. W.; Erdmer, P.; Evenchick, C. A.

    2003-04-01

    The Cordillera in northern Canada is underlain by westward tapering layers that can be followed from outcrops of Proterozoic strata in the Foreland Belt to the lowermost crust of the orogenic interior, a distance of as much as 500 km across strike. The layering was discovered on two new deep seismic reflection profiles in the Yukon (Line 3; ~650 km) and northern British Columbia (Line 2; ~1245 km in two segments) that were acquired as part of the LITHOPROBE Slave - Northern Cordillera Lithospheric Evolution (SNORCLE) transect. Along Line 3, the layering is visible between 5.0 and 12.0 s (~15 to 36 km depth). It is followed southwestward for nearly 650 km (~500 km across strike) and thins to less than 1.0 s (~3.0-3.5 km thickness) near the Moho at the Yukon-Alaska international boundary. Farther south, along Line 2, the upper part of the layering correlates with outcrops of Proterozoic (1.76-1.0 Ga) strata on the east. Near the outcrop, the layering is >15 km thick. It projects westward into the middle and lower crust for ~700 km (~300 km across strike) where it disappears as a thin taper at the base of the crust. The layering is disrupted at the Tintina fault zone, a late to post-orogenic strike-slip fault with up to 800 km of displacement, which appears as a vertical zone of little reflectivity on both profiles (~300 km apart). The base of the layered reflection zone coincides with the Moho, which exhibits variable character and undulates in a series of broad (~150 km) arches. Although the mantle is generally non-reflective, an event dips eastward from ~14.0 s (~45 km) at the western end of Line 3 near the coast to ~21.0 s (73 km depth) beneath exposed Eocene magmatic rocks. It is interpreted as a relict subduction surface of the Kula plate. Some implications of the interpretation of Proterozoic layered rocks beneath most of the northern Cordillera are: (1) ancient North American crust and lithosphere project westward beneath most of the Northern Cordillera, (2

  13. Evaluating the performance of selective-bred lines of eastern oysters, Crassostrea virginica, at different locations along the east coast of the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Populations of the economically important eastern oyster, Crassostrea virginica have been severely affected in the last few decades by diseases such as Dermo, MSX, SSO, and ROD. As the demand for a fast-growing, disease-resistant oyster increases, so has the need for effective breeding programs that...

  14. Relationship between trunk diameter and nut yield of grafted named varieties of eastern black walnut is different from that of native trees

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many landowners in the United States have little access to information on economic returns from agroforestry practices. Despite the existence of agroforestry economic simulators, data bases are lacking to predict returns from nuts produced by eastern black walnut (EBW), Julgans nigra L., a hardwood...

  15. Anthelmintic activity of Pistacia lentiscus foliage in two Middle Eastern breeds of goats differing in their propensity to consume tannin-rich browse.

    PubMed

    Landau, S; Azaizeh, H; Muklada, H; Glasser, T; Ungar, E D; Baram, H; Abbas, N; Markovics, A

    2010-10-29

    The Damascus and Mamber breeds of goats thrive in Middle Eastern Mediterranean regions where the tannin-rich (20% of polyethylene glycol-binding tannins) brush species Pistacia lentiscus L. (lentisk) is ubiquitous. In light of the increasing recognition of the anthelmintic activity of plant tannins, we examined the effect of offering lentisk foliage for 24 days on fecal egg excretion in 5.5-month-old Damascus and Mamber kid goats (n=28) following infection with 10,000 L3 larvae of mixed gastro-intestinal nematodes (GIN). Lentisk foliage was consumed with or without a daily supplement of 20 g polyethylene glycol (PEG; MW 4000). Lentisk tannins showed a strong protein-depletive effect that was totally reversed by the addition of PEG. At the peak of infection, kids of the two breeds lost weight unless they were fed with lentisk without PEG. Fecal egg counts (FEC) were lowest - and did not differ from 0 - in kids fed lentisk without PEG, highest in the controls fed hay as roughage, and intermediate in kids fed lentisk and PEG (241, 1293, and 705 eggs per gram, respectively, SEM 180; P<0.001); therefore, the anthelmintic activity of lentisk was only partly attributable to tannins. The suppressive effect of lentisk on FEC ceased when feeding was discontinued, suggesting that female parasites were not killed but their fertility was reversibly impaired. Damascus kids showed lower FEC than their Mamber counterparts, inferring that the effect of foraging on tannin-rich species is only additive to genetic differences between goat breeds in their sensitivity to GIN infection. On the basis of our results we would expect yearlong lentisk grazing to result in no or very low GIN infection, and Damascus goats to have some advantage over Mamber goats where chemical control of GIN is unfeasible. There appears to be a trade-off between the benefits of lentisk tannin as drug and its side-effects (protein depletion) when given at high level; how goats balance this trade-off requires

  16. Testing the enemies hypothesis in peach orchards in two different geographic areas in eastern China: the role of ground cover vegetation.

    PubMed

    Wan, Nian-Feng; Ji, Xiang-Yun; Jiang, Jie-Xian

    2014-01-01

    Many studies have supported the enemies hypothesis, which suggests that natural enemies are more efficient at controlling arthropod pests in polyculture than in monoculture agro-ecosystems. However, we do not yet have evidence as to whether this hypothesis holds true in peach orchards over several geographic locations. In the two different geographic areas in eastern China (Xinchang a town in the Shanghai municipality, and Hudai, a town in Jiangsu Province) during a continuous three-year (2010-2012) investigation, we sampled arthropod pests and predators in Trifolium repens L. and in tree canopies of peach orchards with and without the ground cover plant T. repens. No significant differences were found in the abundances of the main groups of arthropod pests and predators in T. repens between Hudai and Xinchang. The abundance, richness, Simpson's index, Shannon-Wiener index, and Pielou evenness index of canopy predators in ground cover areas increased by 85.5, 27.5, 3.5, 16.7, and 7.9% in Xinchang, and by 87.0, 27.6, 3.5, 17.0 and 8.0% in Hudai compared to those in the controls, respectively. The average abundance of Lepidoptera, Coleoptera, Homoptera, true bugs and Acarina canopy pests in ground cover areas decreased by 9.2, 10.2, 17.2, 19.5 and 14.1% in Xinchang, and decreased by 9.5, 8.2, 16.8, 20.1 and 16.6% in Hudai compared to that in control areas, respectively. Our study also found a higher density of arthropod species resources in T. repens, as some omnivorous pests and predators residing in T. repens could move between the ground cover and the orchard canopy. In conclusion, ground cover in peach orchards supported the enemies hypothesis, as indicated by the fact that ground cover T. repens promoted the abundance and diversity of predators and reduced the number of arthropod pests in tree canopies in both geographical areas.

  17. Testing the Enemies Hypothesis in Peach Orchards in Two Different Geographic Areas in Eastern China: The Role of Ground Cover Vegetation

    PubMed Central

    Wan, Nian-Feng; Ji, Xiang-Yun; Jiang, Jie-Xian

    2014-01-01

    Many studies have supported the enemies hypothesis, which suggests that natural enemies are more efficient at controlling arthropod pests in polyculture than in monoculture agro-ecosystems. However, we do not yet have evidence as to whether this hypothesis holds true in peach orchards over several geographic locations. In the two different geographic areas in eastern China (Xinchang a town in the Shanghai municipality, and Hudai, a town in Jiangsu Province) during a continuous three-year (2010–2012) investigation, we sampled arthropod pests and predators in Trifolium repens L. and in tree canopies of peach orchards with and without the ground cover plant T. repens. No significant differences were found in the abundances of the main groups of arthropod pests and predators in T. repens between Hudai and Xinchang. The abundance, richness, Simpson's index, Shannon-Wiener index, and Pielou evenness index of canopy predators in ground cover areas increased by 85.5, 27.5, 3.5, 16.7, and 7.9% in Xinchang, and by 87.0, 27.6, 3.5, 17.0 and 8.0% in Hudai compared to those in the controls, respectively. The average abundance of Lepidoptera, Coleoptera, Homoptera, true bugs and Acarina canopy pests in ground cover areas decreased by 9.2, 10.2, 17.2, 19.5 and 14.1% in Xinchang, and decreased by 9.5, 8.2, 16.8, 20.1 and 16.6% in Hudai compared to that in control areas, respectively. Our study also found a higher density of arthropod species resources in T. repens, as some omnivorous pests and predators residing in T. repens could move between the ground cover and the orchard canopy. In conclusion, ground cover in peach orchards supported the enemies hypothesis, as indicated by the fact that ground cover T. repens promoted the abundance and diversity of predators and reduced the number of arthropod pests in tree canopies in both geographical areas. PMID:24963719

  18. The Taxonomic Status of Mazama bricenii and the Significance of the Táchira Depression for Mammalian Endemism in the Cordillera de Mérida, Venezuela.

    PubMed

    Gutiérrez, Eliécer E; Maldonado, Jesús E; Radosavljevic, Aleksandar; Molinari, Jesús; Patterson, Bruce D; Martínez-C, Juan M; Rutter, Amy R; Hawkins, Melissa T R; Garcia, Franger J; Helgen, Kristofer M

    2015-01-01

    We studied the taxonomy and biogeography of Mazama bricenii, a brocket deer classified as Vulnerable by the IUCN, drawing on qualitative and quantitative morphology and sequences of the mitochondrial cytochrome-b gene. We used Ecological Niche Modeling (ENM) to evaluate the hypothesis that M. bricenii of the Venezuelan Cordillera de Mérida (CM) might have become isolated from populations of its putative sister species, Mazama rufina, in the Colombian Cordillera Oriental (CO). This hypothesis assumes that warm, dry climatic conditions in the Táchira Depression were unsuitable for the species. Our analyses did not reveal morphological differences between specimens geographically attributable to M. bricenii and M. rufina, and phylogenetic analyses of molecular data recovered M. bricenii nested within the diversity of M. rufina. These results indicate that M. bricenii should be regarded as a junior synonym of M. rufina. ENM analyses revealed the existence of suitable climatic conditions for M. rufina in the Táchira Depression during the last glacial maximum and even at present, suggesting that gene flow between populations in the CO and CM may have occurred until at least the beginning of the current interglacial period and may continue today. Because this pattern might characterize other mammals currently considered endemic to the CM, we examined which of these species match two criteria that we propose herein to estimate if they can be regarded as endemic to the CM with confidence: (1) that morphological or molecular evidence exists indicating that the putative endemic taxon is distinctive from congeneric populations in the CO; and (2) that the putative endemic taxon is restricted to either cloud forest or páramo, or both. Only Aepeomys reigi, Cryptotis meridensis, and Nasuella meridensis matched both criteria; hence, additional research is necessary to assess the true taxonomic status and distribution of the remaining species thought to be CM endemics.

  19. The Taxonomic Status of Mazama bricenii and the Significance of the Táchira Depression for Mammalian Endemism in the Cordillera de Mérida, Venezuela

    PubMed Central

    Gutiérrez, Eliécer E.; Maldonado, Jesús E.; Radosavljevic, Aleksandar; Molinari, Jesús; Patterson, Bruce D.; Martínez-C., Juan M.; Rutter, Amy R.; Hawkins, Melissa T. R.; Garcia, Franger J.; Helgen, Kristofer M.

    2015-01-01

    We studied the taxonomy and biogeography of Mazama bricenii, a brocket deer classified as Vulnerable by the IUCN, drawing on qualitative and quantitative morphology and sequences of the mitochondrial cytochrome-b gene. We used Ecological Niche Modeling (ENM) to evaluate the hypothesis that M. bricenii of the Venezuelan Cordillera de Mérida (CM) might have become isolated from populations of its putative sister species, Mazama rufina, in the Colombian Cordillera Oriental (CO). This hypothesis assumes that warm, dry climatic conditions in the Táchira Depression were unsuitable for the species. Our analyses did not reveal morphological differences between specimens geographically attributable to M. bricenii and M. rufina, and phylogenetic analyses of molecular data recovered M. bricenii nested within the diversity of M. rufina. These results indicate that M. bricenii should be regarded as a junior synonym of M. rufina. ENM analyses revealed the existence of suitable climatic conditions for M. rufina in the Táchira Depression during the last glacial maximum and even at present, suggesting that gene flow between populations in the CO and CM may have occurred until at least the beginning of the current interglacial period and may continue today. Because this pattern might characterize other mammals currently considered endemic to the CM, we examined which of these species match two criteria that we propose herein to estimate if they can be regarded as endemic to the CM with confidence: (1) that morphological or molecular evidence exists indicating that the putative endemic taxon is distinctive from congeneric populations in the CO; and (2) that the putative endemic taxon is restricted to either cloud forest or páramo, or both. Only Aepeomys reigi, Cryptotis meridensis, and Nasuella meridensis matched both criteria; hence, additional research is necessary to assess the true taxonomic status and distribution of the remaining species thought to be CM endemics. PMID

  20. Air temperature, radiation budget and area changes of Quisoquipina glacier in the Cordillera Vilcanota (Peru)

    NASA Astrophysics Data System (ADS)

    Suarez, Wilson; Macedo, Nicolás; Montoya, Nilton; Arias, Sandro; Schauwecker, Simone; Huggel, Christian; Rohrer, Mario; Condom, Thomas

    2015-04-01

    The Peruvian Andes host about 71% of all tropical glaciers. Although several studies have focused on glaciers of the largest glaciered mountain range (Cordillera Blanca), other regions have received little attention to date. In 2011, a new program has been initiated with the aim of monitoring glaciers in the centre and south of Peru. The monitoring program is managed by the Servicio Nacional de Meteorología e Hidrología del Perú (SENAMHI) and it is a joint project together with the Universidad San Antonio Abad de Cusco (UNSAAC) and the Autoridad Nacional del Agua (ANA). In Southern Peru, the Quisoquipina glacier has been selected due to its representativeness for glaciers in the Cordillera Vilcanota considering area, length and orientation. The Cordillera Vilcanota is the second largest mountain range in Peru with a glaciated area of approximately 279 km2 in 2009. Melt water from glaciers in this region is partly used for hydropower in the dry season and for animal breeding during the entire year. Using Landsat 5 images, we could estimate that the area of Quisoquipina glacier has decreased by approximately 11% from 3.66 km2 in 1990 to 3.26 km2 in 2010. This strong decrease is comparable to observations of other tropical glaciers. In 2011, a meteorological station has been installed on the glacier at 5180 m asl., measuring air temperature, wind speed, relative humidity, net short and longwave radiation and atmospheric pressure. Here, we present a first analysis of air temperature and the radiation budget at the Quisoquipina glacier for the first three years of measurements. Additionally, we compare the results from Quisoquipina glacier to results obtained by the Institut de recherche pour le développement (IRD) for Zongo glacier (Bolivia) and Antizana glacier (Ecuador). For both, Quisoquipina and Zongo glacier, net shortwave radiation may be the most important energy source, thus indicating the important role of albedo in the energy balance of the glacier

  1. Geochronology, geochemistry and tectonic evolution of the Western and Central cordilleras of Colombia

    NASA Astrophysics Data System (ADS)

    Villagómez, Diego; Spikings, Richard; Magna, Tomas; Kammer, Andreas; Winkler, Wilfried; Beltrán, Alejandro

    2011-08-01

    Autochthonous rocks of the pre-Cretaceous continental margin of NW South America (the Tahami Terrane) are juxtaposed against a series of para-autochthonous rock units that assembled during the Early Cretaceous. Allochthonous, oceanic crust of the Caribbean Large Igneous Province collided with and accreted onto the margin during the Late Cretaceous. We present the first regional-scale dataset of zircon U-Pb LA-ICP-MS ages for intrusive and metamorphic rocks of the autochthonous Tahami Terrane, Early Cretaceous igneous para-autochthonous rocks and accreted oceanic crust. The U-Pb zircon data are complemented by multiphase 40Ar/ 39Ar crystallization and cooling ages. The geochronological data are combined with whole rock major oxide, trace element and REE data acquired from the same units to constrain the tectonic origin of the rock units and terranes exposed in the Western Cordillera, Cauca-Patía Valley and the Central Cordillera of Colombia. The Tahami Terrane includes lower Paleozoic orthogneisses (~ 440 Ma) that may have erupted during the active margin stage of the Rheic Ocean. Basement gneisses were intruded by Permian, continental arc granites during the final assembly of Pangea. Triassic sedimentary rocks were subsequently deposited in rift basins and partially melted during high-T metamorphism associated with rifting of western Pangea during 240-220 Ma. Continental arc magmatism during 180-145 Ma is preserved along the whole length of the Central Cordillera and was followed by an Early Cretaceous out-board step of the arc axis and the inception of the Quebradagrande Arc that fringed the continental margin. Back-stepping of the arc axis may have been caused by the collision of buoyant seamounts, which were coeval with plateau rocks exposed in the Nicoya Peninsular of Costa Rica. Rapid westward drift of South America closed the Quebradagrande basin in the late Aptian and caused medium-high P-T metamorphic rocks of the Arquía Complex to exhume and obduct onto

  2. Seismic investigations of the Earth's lithosphere and asthenosphere in two unique convergent margin settings: The Carpathians, Romania, and U.S. Cordillera, Idaho-Oregon

    NASA Astrophysics Data System (ADS)

    Stanciu, Adrian Christian

    Proposed mechanisms for the unusual seismicity ~100 km southeast of the contact between the Transylvanian Basin and the Eastern Carpathians in Romania have included tearing and rollback of a subducted slab of oceanic lithosphere and gravitational instability and delamination of continental lithosphere. We examined the upper mantle fabrics using shear wave splitting of SK(K)S phases recorded at four broadband seismic stations in the Transylvanian Basin. Our results indicate a regional NW-SE splitting trend, with measurements that reflect an abrupt change from this regional flow field in the vicinity of the Vrancea body to a NE-SW trend that is consistent with redirection of mantle flow. Crustal thickness measurements show 28-30 km in the western part of the Transylvanian Basin, 34-39 km at the contact with the Eastern Carpathians, and 40-45 km further east. These results, along with previous estimates, constrain the locus of the inferred Miocene suture between the southeastern-most portion of the Tisza-Dacia terrane and the East European Platform. The second convergent margin system represented here is in the North American Cordillera in Idaho and Oregon, where subduction and accretion of exotic terranes have modified the western margin of North America. We used teleseismic receiver functions from 85 broadband stations to analyze the geometry of the Salmon River suture zone, the western Idaho shear zone, and the Grouse Creek-Farmington zone boundary. Results show a clear break in crustal thickness from ~28 km beneath the accreted terranes to 36 km east of the surface expression of the WISZ. A strong mid-crustal converter at ~20 km depth is consistent with tectonic wedging during accretion of the Blue Mountains terranes. An eastern Moho offset of ~6 km is consistent with the Archean Grouse Creek-Farmington zone boundary. We used deep converted phases generated beneath the study area to image the mantle transition zone. We observe a continuous high amplitude P410s

  3. A new species of Choerophryne (Anura, Microhylidae) from the central cordillera of Papua New Guinea.

    PubMed

    Iannella, Amy; Richards, Stephen; Oliver, Paul

    2014-01-09

    We describe a new species of very small microhylid frog in the genus Choerophryne from the upper Strickland River area, Western and Southern Highlands Provinces, Papua New Guinea. Choerophryne gracilirostris sp. nov. can be distinguished from congeners by the following combination of characters: small size (SUL 13.5-14.7 mm), moderately long and narrow snout, first finger without expanded disk and advertisement call consisting of 3-5 distinctly pulsed notes repeated in long sequences. Males in the type series were calling from within leaf litter in primary hill rainforest (213-1368 m a.s.l.). The new species is the third Choerophryne known from the southern side of New Guinea's central cordillera. Measurements of a juvenile specimen (rare because most Choerophryne collected are calling males) demonstrate that the distinctive rostral projection of this genus exhibits pronounced positive allometry.

  4. Stable isotopic constraints on the nature of the syntectonic fluid regime of the Canadian cordillera

    SciTech Connect

    Nesbitt, B.E.; Muehlenbacks, K. )

    1991-05-01

    Oxygen, hydrogen and carbon isotopic analyses of rocks from the Canadian Cordillera document regional variations in the origins and evolution of crustal fluids. High temperature systems in unmetamorphosed, felsic volcanic rocks are characterized by low {delta}{sup 18}O values. Veins in regional metamorphic rocks are characterized by {delta}{sup 18}O values that reflect approximate oxygen isotopic equilibration of the fluids with regional rock units. The {delta} D studies indicate that both systems were dominated by meteoric water. The {delta}{sup 13}C values for vein carbonate indicate a regional lithologic control on {delta}{sup 13}C values. The data indicate that convection of surface fluids to depth of 10 or more kilometers during orogenesis was common. The existence of deep convection cells involving meteoric water further indicates that fluid pressures to these depths must have been approximately hydrostatic. Regional structural style appears to exert an important control on the depth of penetration of surface fluids.

  5. Miocene non-marine diatoms from the western Cordillera basins of northern Peru

    USGS Publications Warehouse

    Fourtanier, E.; Gasse, F.; Bellier, O.; Bonhomme, M.G.; Robles, I.

    1993-01-01

    Diatom assemblages are documented from diatomite layers of two Miocene fluvio-lacustrine units from the basins of the western Cordillera of northern Peru: the Namora Formation and the Cajabamba Formation. Emphasis is given to taxa of particular stratigraphic interest. The diatom assemblages indicate for the Namora Formation the occurrence of swampy conditions with very dilute, low alkalinity water. The diatom assemblages of the Cajabamba Formation reflect the occurrence of fresh, slightly alkaline, eutrophic lakes with deep water in some samples, and swampy conditions with relatively high salt content in other samples. The Namora formation is late Miocene in age based on the diatom assemblages and radiometric analyses. The diatom layers of the Cajabamba Formation are dated as late middle to early late Miocene. -from Authors

  6. The unusual nature of recent snowpack declines in the North American cordillera.

    PubMed

    Pederson, Gregory T; Gray, Stephen T; Woodhouse, Connie A; Betancourt, Julio L; Fagre, Daniel B; Littell, Jeremy S; Watson, Emma; Luckman, Brian H; Graumlich, Lisa J

    2011-07-15

    In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpack reconstructions from 66 tree-ring chronologies in key runoff-generating areas of the Colorado, Columbia, and Missouri River drainages. Over the past millennium, late 20th century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains and in their north-south synchrony across the cordillera. Both the snowpack declines and their synchrony result from unparalleled springtime warming that is due to positive reinforcement of the anthropogenic warming by decadal variability. The increasing role of warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

  7. Holocene Paleoglacier History of Glaciar Dalla Vedova, Cordillera DARWIN, Tierra del Fuego, Chile

    NASA Astrophysics Data System (ADS)

    Reynhout, S.

    2015-12-01

    Southernmost South America is unique in its position immediately north of the present-day Antarctic Convergence, making it ideally suited for the evaluation of Antarctic influences on terrestrial paleoclimate. Here we present a glacial geomorphic interpretation of the paleoglacial history of Glaciar Dalla Vedova in Bahía Blanca, Cordillera Darwin, Chile (53°S). This interpretation is further constrained by radiocarbon dating, cosmogenic dating, dendrochronology, and historical photogrammetry. Preliminary field work suggests that Holocene glacier fluctuations have been constrained to within 3 km of the present glacier boundary, punctuated by rapid recent glacier retreat over the past century. By comparing the observed chronology with the record contained further north in Patagonia, we will evaluate possible mechanisms of regional climate variability over the Holocene across southernmost South America.

  8. The Unusual Nature of Recent Snowpack Declines in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Pederson, Gregory T.; Gray, Stephen T.; Woodhouse, Connie A.; Betancourt, Julio L.; Fagre, Daniel B.; Littell, Jeremy S.; Watson, Emma; Luckman, Brian H.; Graumlich, Lisa J.

    2011-07-01

    In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpack reconstructions from 66 tree-ring chronologies in key runoff-generating areas of the Colorado, Columbia, and Missouri River drainages. Over the past millennium, late 20th century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains and in their north-south synchrony across the cordillera. Both the snowpack declines and their synchrony result from unparalleled springtime warming that is due to positive reinforcement of the anthropogenic warming by decadal variability. The increasing role of warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

  9. The timing of Jurassic orogenesis in the continental arc terrane of the western US Cordillera: Jackston Mountains, northwestern Nevada

    SciTech Connect

    Quinn, M.J.; Wright, J.E. . Dept. of Geology and Geophysics)

    1993-04-01

    Pre-Nevadan, Jurassic orogenesis appears to be characteristic of many Mesozoic arc assemblages of the western US Cordillera. In most places this deformation is Middle Jurassic ([approximately]170--160 Ma). The authors recent work in the Black Rock Desert (BRD) documents an episode of Early Jurassic metamorphism and tectonism in the Jackson Mountains (JM). Here, an extensive arc section, including the Norian to Middle ( ) Jurassic Happy Creek Volcanics and Early to Middle Jurassic plutons, indicate vigorous arc magmatism in the arly Mesozoic. Among the southwest flank of the range the lower Mesozoic section is overridden by an east vergent thrust sheet carrying upper Paleozoic rocks of the McGill Canyon Unit. Another thrust package is located on the same side of the range, but further to the north, and contains variably metamorphosed clastic rocks, carbonate, and mafic volcanics. There is also an abrupt drop in metamorphic grade across the main thrust fault where greenschist facies rocks are in contact with virtually unmetamorphosed Happy Creek Volcanics. Two plutons with U/Pb zircon age of 188 [+-] 2 Ma and 193 [+-] 3 Ma crosscut the northern thrust fault. These relations suggest than an episode of regional metamorphism followed by E-W compressional tectonism was completed during the Early Jurassic in this portion of the arc terrane. These results differ significantly from previous studies that have interpreted all compressive deformation in the JM to have taken place between the Middle Jurassic and Cretaceous. The authors new data indicate that pre-Nevada Jurassic deformation is somewhat older in the BRD than that documented in other parts of the Mesozoic arc. Because voluminous Jurassic magmatism also began at an earlier time (Early Jurassic) in the BRD than elsewhere, they suggest that deformation and metamorphis within the arc may be facilitated and localized during periods of high heat flux related to magmatic input.

  10. Ichnological analysis in high-resolution sequence stratigraphy: The Glossifungites ichnofacies in Triassic successions from the Betic Cordillera (southern Spain)

    NASA Astrophysics Data System (ADS)

    Rodríguez-Tovar, Francisco J.; Pérez-Valera, Fernando; Pérez-López, Alberto

    2007-06-01

    This study integrates ichnological and sedimentological data in order to refine sequence stratigraphy and interpretations of sea-level dynamics for the Ladinian (Middle Triassic), Muschelkalk succession (Siles Formation) in the Betic Cordillera (southern Spain). Facies analysis was integrated with a detailed ichnological study, focused on the middle part of the lower member of the Muschelkalk succession (transgressive systems tract), which is characterized by an abundant and conspicuous trace fossil assemblage. Seven lithofacies were recognized, recording sediment accumulation in tidal flat, and inner to outer marine carbonate ramp, depositional environments. Thin-bedded marly limestones with bioclastic shelly beds (Facies E: middle ramp, with storm influence), are characterized by Diplocraterion and Rhizocorallium. Diplocraterion is protrusive, usually eroded on top, and mainly recorded in the marly limestone intervals. Rhizocorallium preserves well defined scratch-marks, and is commonly emplaced in bioclastic, shelly beds. The assemblage represents the Glossifungites ichnofacies. Sedimentological and ichnological data are interpreted to record a complex transgressive context, associated with high-frequency sea-level dynamics that allowed formation of transgressive surfaces of erosion (TSE, i.e., ravinement surfaces) of different orders. Major TSE, associated with continuous bioclastic shelly beds, delimit parasequences; the absence of the Glossifungites suite reveals that there was little time between erosion and deposition. Intermediate TSE, associated with discontinuous shell beds, are related to comparatively less significant sea-level rises and occur within parasequences. The Glossifungites suite reveals colonization of firmgrounds during relatively prolonged times between erosion and deposition related to intermediate TSE. Minor order TSE, recorded between the intermediate TSE, are related to punctuated, highest frequency sea-level changes; phases of

  11. Measurements of light absorbing particulates on the glaciers in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J. D.; Schwarz, J. P.; Arnott, W. P.; Cole, R. J.; Lapham, E.; Celestian, A.

    2014-10-01

    Glaciers in the tropical Andes have been rapidly losing mass since the 1970s. In addition to the documented increase in air temperature, increases in light absorbing particulates deposited on glaciers could be contributing to the observed glacier loss. Here we report on measurements of light absorbing particulates sampled from glaciers during three surveys in the Cordillera Blanca in Peru. During three research expeditions in the dry seasons (May-August) of 2011, 2012 and 2013, two hundred and forty snow samples were collected from fifteen mountain peaks over altitudes ranging from 4800 to nearly 6800 m. Several mountains were sampled each of the three expeditions and some mountains were sampled multiple times during the same expedition. Collected snow samples were melted and filtered in the field then later analyzed using the Light Absorption Heating Method (LAHM), a new technique that measures the ability of particulates on filters to absorb visible light. LAHM results have been calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). As sample filters often contain dust in addition to BC, results are presented in terms of effective Black Carbon (eBC). During the 2013 survey, snow samples were collected and kept frozen for analysis with a Single Particle Soot Photometer (SP2). Calculated eBC mass from the filter analysis and the SP2 refractory Black Carbon (rBC) results were well correlated (r2 = 0.92). These results indicate that a substantial portion of the light absorbing particulates in the more polluted areas were likely BC. The three years of data show that glaciers in the Cordillera Blanca Mountains close to human population centers have substantially higher levels of eBC (as high as 70 ng g-1) than remote glaciers (as low as 2.0 ng g-1 eBC), indicating that population centers can influence local glaciers by sourcing BC.

  12. Measurements of light-absorbing particles on the glaciers in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J. D.; Schwarz, J. P.; Arnott, W. P.; Cole, R. J.; Lapham, E.; Celestian, A.

    2015-02-01

    Glaciers in the tropical Andes have been rapidly losing mass since the 1970s. In addition to the documented increase in temperature, increases in light-absorbing particles deposited on glaciers could be contributing to the observed glacier loss. Here we report on measurements of light-absorbing particles sampled from glaciers during three surveys in the Cordillera Blanca Mountains in Peru. During three research expeditions in the dry seasons (May-August) of 2011, 2012 and 2013, 240 snow samples were collected from 15 mountain peaks over altitudes ranging from 4800 to nearly 6800 m. Several mountains were sampled each of the 3 years and some mountains were sampled multiple times during the same year. Collected snow samples were melted and filtered in the field then later analyzed using the Light Absorption Heating Method (LAHM), a new technique that measures the ability of particles on filters to absorb visible light. LAHM results have been calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). As sample filters often contain dust in addition to BC, results are presented in terms of effective black carbon (eBC). During the 2013 survey, snow samples were collected and kept frozen for analysis with a Single Particle Soot Photometer (SP2). Calculated eBC mass from the LAHM analysis and the SP2 refractory black carbon (rBC) results were well correlated (r2 = 0.92). These results indicate that a substantial portion of the light-absorbing particles in the more polluted regions were likely BC. The 3 years of data show that glaciers in the Cordillera Blanca Mountains close to human population centers have substantially higher levels of eBC (as high as 70 ng g-1) than remote glaciers (as low as 2.0 ng g-1 eBC), indicating that population centers can influence local glaciers by sourcing BC.

  13. Crustal shortening and Eocene extension in the southeastern Canadian Cordillera: Some thermal and rheological considerations

    NASA Astrophysics Data System (ADS)

    Liu, Mian; Furlong, Kevin P.

    1993-06-01

    Metamorphic core complexes in the southeastern Canadian Cordillera were formed during Eocene crustal extension, shortly (within a few millions of years) after Late Jurassic-Paleocene crustal shortening. Thermal-rheological modeling, constrained by geological and geochronological studies of the Valhalla core complex and other core complexes in this region, is used to investigate two major problems concerning the formation of these core complexes: (1) the dynamic links between crustal shortening and extension and (2) the cooling history and unroofing rates during extension. Thermal-rheological effects associated with crustal shortening are integrated through the history of crustal compression, since crustal shortening in this region was a long and slow process and cannot be treated as an instantaneous event. Our results suggest that crustal shortening may have played an important role in Eocene extension in the southeastern Canadian Cordillera by (1) producing a thickened and therefore unstable crust and (2) thermally weakening the lithosphere. However, heat generated by crustal shortening is not enough to account for the thermal state of the Valhalla complex, and additional heat sources at depth may be necessary. We then investigate thermal evolution during extension in both a simple shear model and a progressive pure stretching model. We show that the geotherm in an extensional region is time-and space-dependent and is affected by many variables including the preextensional thermal history and the mode of extension. Thus caution needs to be exercised when inferring unroofing rates from thermochronologic data. The cooling history of the Valhalla core complex may be explained by unroofing at rates of 1-2 mm/yr.

  14. Isotopic characteristics of mantle sources for Quaternary continental alkaline magmas in the northern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Carignan, Jean; Ludden, John; Francis, Don

    1994-12-01

    Three mantle compositions are identified as potential source end members for Quaternary to recent alkaline volcanic rocks from Fort Selkirk, Llangorse-Hirschfeld, Alligator Lake and Mt. Edziza in the northern Canadian Cordillera. These are: (1) an amphibole-rich source, characterized by unradiogenic Sr, Nd and Pb, from which the olivine nephelinite lavas formed, (2) the continental lithospheric mantle which is characterised by high Pb-207/Pb-204 and appears to be involved in the formation of the alkali olivine basalts of Fort Selkirk, and (3) a mantle with radiogenic Pb and unradiogenic Sr (HIMU-type) represented by lavas from Mt. Edziza. The Mt. Edziza volcano is the largest of the volcanic centres in the region, and is considered to reflect melting of sublithospheric mantle of HIMU composition below central British Columbia. Incipient melting of amphibole-veined subcontinental mantle lithosphere resulted from plume upwelling and/or transtensional pressure release and produced the small nephelinite to olivine basalt centres of the northern Cordilleran Province. The source of the nephelinite magmas is slightly more radiogenic than present-day Pacific Mid-Ocean ridge basalts (MORB), and is best represented by the most depleted component of the Aleutian magmas. This suggests enrichment of the subcontinental lithosphere in the northern Cordillera by melts of this isotopic composition during Cretaceous subduction. The Alligator Lake complex is anomalous and charaterized by the most radiogenic lavas. Despite the presence of crustal xenoliths there is no clear geochemical signature for crustal contamination and, in contrast to the other volcanic centers which were erupted through the Intermontain Belt, the lavas of this center may have been derived from a highly radiogenic lithospheric mantle beneath the Coast Plutonic complex.

  15. Climate in the Western Cordillera of the Central Andes over the last 4300 years

    NASA Astrophysics Data System (ADS)

    Engel, Zbyněk; Skrzypek, Grzegorz; Chuman, Tomáš; Šefrna, Luděk; Mihaljevič, Martin

    2014-09-01

    The Distichia peat core obtained in the Carhuasanta valley near Nevado Mismi, Cordillera Chila, provides information on climatic and environmental conditions over the last ˜4300 years. The relative changes in the stable carbon isotope composition of plant remains preserved in the core reflect major temperature fluctuations in the Western Cordillera of the southern Peruvian Andes. These temperature variations can be additionally linked with the changes in precipitation patterns by analysing C% and C/N ratio in the core. Relatively warm and moist conditions prevailed from 4280 to 3040 cal. yrs BP (BC 2330-1090) with a short colder dry episode around 3850 cal. yrs BP (BC 1900). The most prominent climate changes recorded in the peat occurred between 3040 and 2750 cal. yrs BP (BC 1090-800) when the initial warming turned to a rapid cooling to temperatures at least 2 °C lower than the mean for the Late Holocene. Initially drier conditions within this event turned to a short wet phase after 2780 cal. yrs BP (BC 830) when the temperature increased again. This event coincides with significant changes in peat and ice core records in the Central Andes matching the timing of the global climate event around 2.8 cal. ka BP. Climatic conditions in the study area became relatively dry and stable after the event for about 800 years. Highly variable temperatures and humidity prevailed during the last 2000 years when an extended warm and relatively humid period occurred between 640 and 155 cal. yrs BP (AD 1310-1795) followed by predominantly colder and drier conditions. The established δ13C peat record represents the first continuous proxy for the temperature in the southern Peruvian Andes dated by the AMS 14C. Distichia peat is wide spread in the Andes and the proposed approach can be applied elsewhere in high altitudes, where no other traditional climate proxies are available.

  16. Cenozoic sedimentary and deformational history of hispaniola, 1: southeastern Cordillera Central

    SciTech Connect

    Heubeck, C.; Mann, P.

    1988-01-01

    The Cordillera Central approximates an elongate (220 km), elevated (>3 km), thrust-bounded anticline cored by Cretaceous-Paleogene arc rocks and uplifted during Miocene to recent time by convergent strike-slip movements between the North American and Caribbean plates. The southeastern termination of the anticline plunges beneath a thick (>6 km), well-exposed marine clastic sedimentary sequence. Because uplift-related faulting is minimal in this hinge region of the Cordillera Central anticline, the authors have carried out detailed mapping of the area to determine (1) relation of Cretaceous-Paleogene arc basement to overlying Cenozoic sedimentary cover, and (2) Cenozoic deformational history of arc and basin sequences. Mapping has clearly distinguished three superimposed Cenozoic basins lying on arc basement. The lowest basin (basin 1) is Paleocene-Eocene in age and consists of alternations of arc-derived turbidies with interbedded pelagic limestone and red mudstone. In apparent conformity above this basin is an approximately 4-km thick marine clastic sequence of medial Eocene through early Miocene age (basin 2). These sediments consist of fining-upward turbiditic sequence derived from the northwest and northeast. Arc basement and overlying basins 1 and 2 were shortened approximately 25% in a short-lived, northwest-southeast-directed compressional event that resulted in the formation of large open synclines and tightly folded and faulted anticlines with fold amplitudes of 1-6 km. Underformed, medial Miocene sediments of a mixed clastic and carbonate shelf facies (basin 3) unconformably overlie the folded latest Oligocene-early Miocene rocks of basin 2 and thus constrain the age of folding as early to middle Miocene.

  17. Asymmetrical Growth of Footwall Topography in the Cordillera Blanca, Peru: Implications for Normal Fault Control on Landscape Evolution

    NASA Astrophysics Data System (ADS)

    Giovanni, M. K.; Horton, B. K.

    2007-12-01

    Morphometric parameters and hypsometry of the >5-km-high Cordillera Blanca in Peru provide insights into the topographic evolution of the uplifted footwall of an active, high-magnitude-slip, low-angle normal fault within a contractional orogenic belt. The modern tectonic activity, mappable fault trace, high relief, and uniform footwall lithology make the Cordillera Blanca an ideal locality to test models for the evolution of topography related to normal faulting. Most models for normal fault growth suggest a tectonic and geomorphic symmetry in which maximum slip and maximum surface uplift occur along the central segments of the fault, with net slip, footwall uplift, and hangingwall subsidence diminishing along strike toward the fault tips. A digital elevation model (DEM) of the Cordillera Blanca permits extraction of important geomorphic metrics for footwall transverse drainages and the hanging-wall axial river, including hypsometry, drainage area, drainage length, relief, channel gradient, surface slope, aspect ratio, and longitudinal profile. These data reveal a pronounced asymmetry in which footwall relief, exposed fault relief, channel gradient, and surface slope are greatest along the northern fault segment and become systematically lower southward along strike. In contrast to most models for normal fault growth, largely based on late Cenozoic systems in the Basin and Range province of the western United States, the Cordillera Blanca demonstrates that abrupt and significant along-strike variations in displacement and footwall uplift are possible in major normal fault systems. The causes of an asymmetric distribution of fault slip and footwall topography in the Cordillera Blanca may be related to: (a) mechanical coupling between the subducting flat Nazca slab and the overriding South American plate; (b) gravitational collapse of overthickened crust along reactivated thrust faults; (c) climatic processes linked to the effect of glacial erosion in the footwall

  18. Eastern American Indian Communities.

    ERIC Educational Resources Information Center

    Thomas, Robert K.

    Identification of social and cultural commonalities among American Indians of the eastern U.S. reveal 4 geographical areas--(1) the eastern seaboard (the largest group in both number of distinct groups and population); (2) the inland area; (3) Louisiana (a combination of inland and seaboard characteristics); (4) the eastern Great Lakes area…

  19. Upper-Mantle Seismic Structure Beneath the Western Cordillera in Oregon and Idaho: Preliminary Results from EarthScope IDOR Teleseismic Travel Time Tomography

    NASA Astrophysics Data System (ADS)

    Stanciu, A. C.; Russo, R.; Mocanu, V. I.; VanDecar, J. C.; Hongsresawat, S.; Bremner, P. M.; Torpey, M. E.; Panning, M. P.

    2015-12-01

    We present new results of the upper-mantle velocity structure beneath the Western U.S. Cordillera from travel time inversion of teleseismic P and S waves recorded at the 85 broadband seismic stations of the EarthScope IDOR passive experiment, deployed in Eastern Oregon and Idaho between 2011 and 2013. Tectonics that could have affected seismic structure still present in this region include long-term subduction of the Farallon plate beneath North America, processes associated with the Columbia River flood basalts and Yellowstone mantle plume, Basin and Range extension, and the current Juan de Fuca subduction just west of the IDOR deployment. Fragments of the Farallon slab, clearly identified elsewhere beneath North America, might be present in the upper mantle of the study region. One such slab remnant, due to subduction associated with accretion of the Siltezia terrane, has been identified in the upper mantle just NW of our study region (Schmandt and Humphreys, 2011). The Juan de Fuca microplate, another remnant of the Farallon slab, subducts eastward beneath North America and is resolved at upper mantle depths regionally. In addition, the distribution of upper mantle asthenosphere is likely affected by the Yellowstone mantle plume and ongoing Basin and Range extension in our study area. We analyzed 239 teleseismic events recorded at the IDOR network with an epicentral distance between 30 and 95 degrees and magnitudes of 5.5 and higher. We picked P and S arrivals using the Automated and Interactive Measurement of Body-wave Arrival Times (AIMBAT) tool, based on the multi-channel cross-correlation method of VanDecar and Crosson (1990). We determined more than 7600 travel-time measurements. Preliminary results indicate a significant variation from west to east in delay times for event-station pairs across the IDOR network.

  20. Different trends in euthanasia acceptance across Europe. A study of 13 western and 10 central and eastern European countries, 1981-2008.

    PubMed

    Cohen, Joachim; Van Landeghem, Paul; Carpentier, Nico; Deliens, Luc

    2013-06-01

    We examined how acceptance of euthanasia among the general public has changed between 1981 and 2008 in western and central and eastern European (CEE) countries using data of the European Values Surveys. Data were collected in 1981, 1990, 1999 and 2008 for 13 western European countries and in 1990, 1999 and 2008 for 10 CEE countries. Euthanasia acceptance increased each decade up until 2008 in 11 of 13 western European countries; in CEE countries, it decreased or did not increase between 1999-2008 in 8 of 10 countries. A number of explanations for and implications of this apparent east-west polarization are suggested.

  1. Nd isotopic characterization of metamorphic rocks in the Coast Mountains, Alaskan and Canadian Cordillera: Ancient crust bounded by juvenile terranes

    NASA Astrophysics Data System (ADS)

    Samson, Scott D.; Patchett, P. Jonathan; McClelland, William C.; Gehrels, George E.

    1991-08-01

    Nd isotopic data are reported for 52 samples from the crustal region between the Alexander-Wrangellia terrane and the Stikine terrane of the Alaskan and Canadian Cordillera. This region is composed of the Gravina belt, a Jurassic-Cretaceous assemblage of volcanic and clastic sedimentary rocks, the Taku terrane, a terrane of probable Early Permian to Late Triassic age, and four assemblages of metamorphic rocks that occur to the west of and within the Coast Mountains batholith. The Gravina belt has ɛNd(T) values that range from -1.1 to +8.3, similar to values of the underlying Alexander terrane, and consistent with the interpretation that it is a juvenile belt that formed in a back-arc or intra-arc basin within the Alexander terrane. Mid-Cretaceous plutons that were emplaced into the Gravina belt have ɛNd(T) values of +4.4 to +5.7 and were probably produced by mantle-derived melts that incorporated some Alexander terrane crust. The Taku terrane has ɛNd(0) values that range from -5.5 to +3.3, with corresponding depleted-mantle model (TDM) ages of 440 to 1430 Ma. A mid-Cretaceous pluton intruding the Taku terrane has an ɛNd(T) value of +5.1, a value indistinguishable from those determined for Cretaceous plutons intruding the Gravina belt. Metamorphic rocks east of and structurally overlying the Taku terrane are divided into the Tracy Arm assemblage, ɛNd(0)=-26 to 0, TDM=800-2450 Ma; the Endicott Arm assemblage, eNd(0)=-10 to -1.3, TDM=950-1500 Ma; the Port Houghton assemblage, ɛNd(0)=-9.4 to +1.1, TDM = 550-1500 Ma; and the Ruth assemblage, ɛNd(0) = -9.4 to +2.0, TDM=650-1300 Ma. These isotopic signatures indicate that a substantial component of each metamorphic assemblage was derived from Precambrian continental crust. The metamorphic rocks from these assemblages are lithologically very similar to rocks of the Yukon-Tanana (YTT) terrane of eastern Alaska and Yukon Territory and have such similar U-Pb detrital zircon ages and Nd isotopic compositions to YTT

  2. Calibration and Assessment of a Distributed Hydrologic Model Applied to a Glacierized Basin in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Burns, P. J.; Nolin, A. W.; Lettenmaier, D. P.; Clarke, G. K.; Naz, B. S.; Gleason, K. E.

    2011-12-01

    Glacier retreat has been well documented in the Cordillera Blanca of the Peruvian Andes. It is becoming clearer that changes in glacier area and volume will negatively affect water resources in this region, particularly during the dry season (May to September). Previous studies focusing on this issue in the Cordillera Blanca have had success modeling runoff but did so using somewhat over-simplified hydrologic models. The question driving this study is: How well does the Distributed Hydrology Soil and Vegetation Model (DHSVM) coupled with a new dynamic glacier sub-model replicate runoff in a test basin of the Cordillera Blanca, namely Llanganuco. During the 2011 dry season we collected data on stream discharge, meteorological conditions, soil, and vegetation in the basin. We installed two stage height recorders in the middle reaches of the watershed to complement a third which delineates the basin outlet. Flow data collected at these points will be used for model calibration and/or validation. For geochemical validation we collected spring and meltwater samples for use in a two component isotopic mixing model. We also mapped dominant soil and vegetation types for model input. We use satellite imagery (ASTER and Landsat) to map the change in glacier extent over approximately the last 30 years as this will be another model input. Coupled together, all of these data will be used to run, validate, and refine a model which will also be implemented in other regions of the world where glacier melt is crucial at certain times of the year.

  3. Diversity and abundance of forest frogs (Anura: Leptodactylidae) before and after Hurricane Georges in the Cordillera Central of Puerto Rico

    USGS Publications Warehouse

    Vilella, F.J.; Fogarty, J.H.

    2005-01-01

    Caribbean hurricanes often impact terrestrial vertebrates in forested environments. On 21 September 1998, Hurricane Georges impacted Puerto Rico with sustained winds in excess of 166 km/hr, causing damage to forests of the island's principal mountain range; the Cordillera Central. We estimated forest frog abundance and diversity from call counts conducted along marked transects before and after Hurricane Georges in two forests reserves of the Cordillera Central (Maricao and Guilarte). We used distance sampling to estimate density of Eleutherodactylus coqui and recorded counts of other species. After the hurricane, the abundance of E. coqui increased in both reserves compared to prehurricane levels while abundance of other frog species decreased. In Maricao, relative abundance of E. richmondi (P = 0.013) and E. brittoni (P = 0.034) were significantly lower after the hurricane. Moreover, species richness and evenness of the Maricao and Guilarte frog assemblages declined after the hurricane. Our results on abundance patterns of the forest frog assemblages of Maricao and Guilarte Forests were similar to those reported from the Luquillo Experimental Forest after Hurricane Hugo in September 1989. Long-term demographic patterns of the forest frog assemblages in the Cordillera Central may be associated with changes due to the ecological succession in post-hurricane forests. Copyright 2005 College of Arts and Sciences.

  4. Transgressive stratigraphy, anoxia, and regional correlations within the late Precambrian Windermere grit of the southern Canadian Cordillera

    SciTech Connect

    Ross, G.M.; Murphy, D.C.

    1988-02-01

    The Windermere grit system in the southern Canadian Cordillera comprises the depositional record of a late Precambrian continental basin of uncertain tectonic affinity. Attempts to analyze the basin by means of these largely nonfossiliferous turbiditic rocks have been frustrated by a lack of chronostratigraphic marker units, a problem common in Precambrian sedimentary sequences. Stratigraphic analysis and regional mapping in the Cariboo Mountains (southeastern Canadian Cordillera) suggest that comparison of Precambrian sequences with Phanerozoic analogues holds promise for constructing chronologically significant sea-level lithostratigraphy. In the Cariboo and western Rocky mountains, a distinctive upward-thinning, dominantly pelitic succession (120 m thick) of rhythmic marble-silty pelite that is capped by a 20-m-thick carbonaceous sulfidic pelite represents a dramatic departure from sandy turbidite deposition and is interpreted as the depositional response of the turbidite system to eustatic sea-level rise. This marker unit appears to persist throughout Windermere grits in the southern Canadian Cordillera and, by analogy with well-constrained Phanerozoic examples of black shale deposition, is inferred to represent a synchronous basinwide highstand event. When analyzed within the context of black-shale depositional models, facies variations within the marker unit provide important constraints on basin shape, possibly water depth, and the magnitude of transcurrent fault movement in the southern Rocky Mountain trench.

  5. Petrological characteristics of Plio-Quaternary 'Sencca' Ignimbrites, Western Cordillera of the Central Andes in Peru

    NASA Astrophysics Data System (ADS)

    Çubukçu, H. E.; Gerbe, M.-C.; Thouret, J.-C.; de la Rupelle, A.; Boivin, P.

    2012-04-01

    Large-volume ignimbrite deposits have been emplaced between 24.6 and 1.37 Ma in the western Andean Cordillera of Southern Peru. The ignimbrites older than 9 Ma (Nazca, Alpabamba, Huaylillas and Caraveli ignimbrites) have formed plateaus, whereas the deep valleys incised in plateaus have been filled by younger Lower-Upper Sencca (~5- 2 Ma) and Las Lomas ignimbrites. Among the younger valley-filling units, Lower and Upper Sencca ignimbrites, with intercalated Upper Barroso lavas, have probably originated from a source beneath the Nevado Coropuna volcano. The unwelded-to-loose, crystal-poor pumice flows of Las Lomas unit (c.1.56-1.37 Ma) can be readily distinguished in the field from the rhyolitic Sencca ignimbrites. In contrast, discriminating Lower Sencca from Upper Sencca deposits in the field is difficult due to comparable lithofacies characteristics. Such a distinction is, however, essential in order to determine temporal constraints on valley incision. The Lower Sencca compound ignimbrite sheet is more widespread (~800 km2) than the Upper Sencca ignimbrite sheet (~600 km2). The Lower Sencca ignimbrites usually form terraces hanging on valley sides but Upper Sencca form deposits crop out near the present valley bottoms or in shallow valleys on high plateaus around Barroso volcanoes. The Lower Sencca ignimbrite is composed of multiple cooling units with a crystal- and fiamme-rich vitrophyric base, overlain by strongly welded, eutaxitic subunits towards the top. Uppermost subunits exhibit an indurated ash and pumice rich vapour-phase facies. The Upper Sencca ignimbrite sheet comprises two subunits only: (1) the basal, black vitrophyre, overlain by a fiamme- and crystal-rich, strongly welded, eutaxitic subunit; 2) the upper subunit with an indurated or slightly welded, crystal-poor, pumice-rich vapour phase facies The dominant mineralogy of Lower Sencca compound ignimbrites includes plagioclase (An13-68) + alkali feldspar (Or38-65) + biotite (XMg: Mg/Mg+Fe= 0

  6. Thermal and exhumation history of the Coastal Cordillera arc of northern Chile revealed by thermochronological dating

    NASA Astrophysics Data System (ADS)

    Juez-Larré, Joaquim; Kukowski, Nina; Dunai, Tibor J.; Hartley, Adrian J.; Andriessen, Paul A. M.

    2010-11-01

    The thermal and erosional history of convergent plate boundaries is important for understanding the links between subduction, arc magmatism, genesis of ore deposits, topography and climate of orogenic belts. Unlike the continent-continent collision that formed many of the largest orogenic belts known today, the Central Andes of South America is a unique case where an oceanic-continent collision has given rise to the Earth's longest and second tallest orogenic belt. Over the last thirty years a plethora of models have been suggested in an attempt to explain how a plateau-type orogen formed at the leading edge of western South America. In the Central Andes most research have focussed attention on the study of the evolution of the arc and backarc, since continuous subduction erosion of the forearc has left little trace of the interplate dynamics that initiated the orogenic belt. In this article, we present a new insight into the thermal and exhumation history of the forearc along the Coastal Cordillera of northern Chile based on biotite K-Ar, apatite fission-track, and apatite/zircon (U-Th)/He dating. We collected diorite samples in a 2 km thick crustal section at the coastal cliff (~ 22°S), and a sea level isoelevation profile between 21 and 27°S. Results from all three dating methods show that the cooling of Coastal Cordillera took place shortly after emplacement during a period of rifting in Jurassic times. Cooling took place in two episodes, mainly in Late Jurassic-Early Cretaceous (~ 118-152 Ma) but also during Late Cretaceous (60-80 Ma) due to the resumption of compression, rift closure, arc uplift, exhumation, eastward migration of magmatic arc activity, and thermal relaxation. The youngest apatite (U-Th)/He ages reveal a cooling event, never reported previously, between 40 and 50 Ma (Eocene). This thermal event affected a > 500 km long and > 1 km thick section of the Coastal Cordillera in northern Chile. Rock cooling recorded in the Eocene cannot be

  7. Historical and future hydrologic response to glacier recession in the Cordillera Real, Bolivia

    NASA Astrophysics Data System (ADS)

    Frans, C. D.; Istanbulluoglu, E.; Naz, B.; Lettenmaier, D. P.; Condom, T.; Clarke, G. K.; Burns, P. J.; Nolin, A. W.

    2013-12-01

    In many partially glaciated watersheds climate-forced glacier recession has altered and will continue to alter seasonal water availability, leading to profound implications for water supply systems. The tropical glaciers of the Cordillera Real, Bolivia, whose melt water significantly contributes to water supply and energy production for the densely populated La Paz area, have retreated at unprecedented rates since the 1970's. This glacier recession will continue with ongoing increasing temperatures projected for the subtropical Andes. We use a recently developed glacio-hydrological model to evaluate the contribution of glacier melt to watershed discharge, and track this contribution in time with changing glacier area. A glacier model, solving time-evolving and spatially-distributed balance equations for glacier mass and momentum, is integrated within the Distributed Hydrology Soil Vegetation Model (DHSVM). The glacio-hydrologic behavior of Cordillera Real watersheds is simulated during the historical period of 1987-2010. This model application is validated through comparisons with satellite derived glacier extent estimates and in-situ mass balance, surface energy flux, and stream discharge measurements. The retrospective analysis indicates that glacier melt contributed, on average, 31% (63%) of total annual (dry season-JJA) watershed discharge. Further, the modeling approach is used to predict the transitioning contribution of glacier melt and watershed hydrology through the 21st century. Multiple realizations of the 21st century meteorological data, used to force the glacier-hydrological model, are produced using a stochastic statistical downscaling technique. In this technique a weather generator (Advanced Weather Generator, AWE-GEN) is employed with statistical parameters of the future climate obtained from predictions of 11 CMIP5 general circulation models (GCMs). Future simulations indicate a 17% (23%) decrease in annual (JJA) runoff by the end of the 21st

  8. Constraining the crustal root geometry beneath the Rif Cordillera (North Morocco)

    NASA Astrophysics Data System (ADS)

    Diaz, Jordi; Gil, Alba; Carbonell, Ramon; Gallart, Josep; Harnafi, Mimoun

    2016-04-01

    The analyses of wide-angle reflections of controlled source experiments and receiver functions calculated from teleseismic events provide consistent constraints of an over-thickened crust beneath the Rif Cordillera (North Morocco). Regarding active source data, we investigate now offline arrivals of Moho-reflected phases recorded in RIFSIS project to get new estimations of 3D crustal thickness variations beneath North Morocco. Additional constrains on the onshore-offshore transition are derived from onland recording of marine airgun shots from the coeval Gassis-Topomed profiles. A regional crustal thickness map is computed from all these results. In parallel, we use natural seismicity data collected throughout TopoIberia and PICASSO experiments, and from a new RIFSIS deployment, to obtain teleseismic receiver functions and explore the crustal thickness variations with a H-κ grid-search approach. The use of a larger dataset including new stations covering the complex areas beneath the Rif Cordillera allow us to improve the resolution of previous contributions, revealing abrupt crustal changes beneath the region. A gridded surface is built up by interpolating the Moho depths inferred for each seismic station, then compared with the map from controlled source experiments. A remarkably consistent image is observed in both maps, derived from completely independent data and methods. Both approaches document a large modest root, exceeding 50 km depth in the central part of the Rif, in contrast with the rather small topographic elevations. This large crustal thickness, consistent with the available Bouguer anomaly data, favor models proposing that the high velocity slab imaged by seismic tomography beneath the Alboran Sea is still attached to the lithosphere beneath the Rif, hence pulling down the lithosphere and thickening the crust. The thickened area corresponds to a quiet seismic zone located between the western Morocco arcuate seismic zone, the deep seismicity area

  9. Review of past and present geotectonic concepts of eastern indonesia

    NASA Astrophysics Data System (ADS)

    Katili, John A.

    equatorial Indo-Pacific region, for example, has recently been compared to the terrane map of the North American Cordillera. The position of eastern Indonesia within the plate-tectonic framework is the key to resolving contradictory views on the tectonics of the Banda Sea. For example, did the Indonesian orogeny take place at the Gondwana margin or the Asian margin, are Timor and Seram a tectonic melange and thus part of the Tertiary Indonesian island arcs, or are these two islands a part of the passive Australian margin? Oceanic magnetic stripes from the Sulu, Celebes and Banda Seas all trend NE-SW. These new data suggest that the Sulu, Celebes and probably the Banda Sea represent areas of trapped Indian Ocean crust. Deep sea drilling in the Banda Sea can resolve much controversy. The Banda Sea occupies a critical position in the complex convergent zone between Australia, Southeast Asia and the Philippine Sea Plate. The determination of the stratigraphy and basement ages of the Banda Sea will constrain evolutionary models which have been proposed. Another unsolved question of key importance in our understanding of the evolution of Sulawesi and the Moluccas is the function and timing of events of the Birdhead 'bacon slicer', or the tectonic shaving in Irian Jaya. Once this mechanism is understood, the development and timing of the various structural features of Sulawesi, Halmahera and the Banda Arc will be classified. Opinions still differ regarding the 'birthplace' of the micro-continents in the Banda Sea. Some regard them as a result of Jurassic rifting of Gondwana in northwestern Australia while others consider them displaced westward from northern Irian Jaya along the Sorong transform fault. Several authors suggested that the eastern parts of Sulawesi, Buru and Seram represent micro-continents which originated from Irian Jaya, while others considered East Sulawesi and north Sulawesi remnants of ophiolite belts or fragments of island arcs that originate from the Pacific

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

    NASA Astrophysics Data System (ADS)

    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

  11. Citizenship Norms in Eastern Europe.

    PubMed

    Coffé, Hilde; van der Lippe, Tanja

    2010-05-01

    Research on Eastern Europe stresses the weakness of its civil society and the lack of political and social involvement, neglecting the question: What do people themselves think it means to be a good citizen? This study looks at citizens' definitions of good citizenship in Poland, Slovenia, the Czech Republic and Hungary, using 2002 European Social Survey data. We investigate mean levels of civic mindedness in these countries and perform regression analyses to investigate whether factors traditionally associated with civic and political participation are also correlated with citizenship norms across Eastern Europe. We show that mean levels of civic mindedness differ significantly across the four Eastern European countries. We find some support for theories on civic and political participation when explaining norms of citizenship, but also demonstrate that individual-level characteristics are differently related to citizenship norms across the countries of our study. Hence, our findings show that Eastern Europe is not a monolithic and homogeneous bloc, underscoring the importance of taking the specificities of countries into account.

  12. Faulted hybrid joints: an example from the Campo de Dalias (Betic Cordilleras, Spain)

    NASA Astrophysics Data System (ADS)

    Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; Rodríguez-Fernández, Luís. Roberto; González-Lodeiro, Francisco

    2004-11-01

    The development of hybrid and faulted joints has not been studied in detail in natural outcrops. This field study in the Campo de Dalias (Betic Cordilleras) establishes the distinctive features of these structures as compared with those predicted by theoretical studies. Hybrid joints appear as two sets of vertical joints forming variable angles, but generally about 25°, with opening directions orthogonal to joint planes. Their development requires low differential stresses with a tensile minimum stress. The main criteria that indicate the existence of faulted joints are: (1) the presence of subvertical fault planes with oblique slip forming a complex pattern of dextral and sinistral faults developed under a single stress regime; (2) faults with similar geometries as joints in the same outcrop, showing an inconsistent cross-cutting relationship; and (3) the development of small basins with variable polarity of asymmetric wedge filling. A permutation in stress orientation since the Tortonian in the Campo de Dalias was responsible for the development of a faulted hybrid joint system, with a constant ENE-WSW extension trend and a switch of σ1 between NNW-SSE and vertical.

  13. Results of land cover change detection analysis in and around Cordillera Azul National Park, Peru

    USGS Publications Warehouse

    Sleeter, Benjamin M.; Halsing, David L.

    2005-01-01

    The first product of the Optimizing Design and Management of Protected Areas for Conservation Project is a land cover change detection analysis based on Landsat thematic mapper (TM) and enhanced thematic mapper plus (ETM+) imagery collected at intervals between 1989 and 2002. The goal of this analysis was to quantify and analyze patterns of forest clearing, land conversion, and other disturbances in and around the Cordillera Azul National Park in Peru. After removing clouds and cloud shadows from the imagery using a series of automatic and manual processes, a Tasseled Cap Transformation was used to detect pixels of high reflectance, which were classified as bare ground and areas of likely forest clearing. Results showed a slow but steady increase in cleared ground prior to 1999 and a rapid and increasing conversion rate after that time. The highest concentrations of clearings have spread upward from the western border of the study area on the Huallaga River. To date, most disturbances have taken place in the buffer zone around the park, not within it, but the data show dense clearings occurring closer to the park border each year.

  14. Serological survey of leptospiral infections in sheep, goats and dogs in Cordillera province, Bolivta.

    PubMed

    Ciceroni, L; Bartoloni, A; Pinto, A; Guglielmetti, P; Valdez Vasquez, C; Gamboa Barahona, H; Roselli, M; Giannico, F; Paradisi, F

    1997-01-01

    A serological survey for antibodies to Leptospira spp. was conducted on sheep, goat and dog serum samples collected in three localities in Cordillera province in the southern part of the Santa Cruz Department (Bolivia) in 1992. A total of 98 sheep, 218 goats and 43 dogs were tested against 29 leptospiral serovars using the microscopic agglutination test. At the time of blood collection all of the examined animals appeared healthy and presented no clinical sign suggestive of leptospirosis. Antibody prevalences, as determined by positive results at a 1:100 dilution or higher, was 14.3% in sheep, 19.7% in goats, and 14.0% in dogs. Agglutinins against six serovars (poi. shermani, pomona, canicola, javanica, djasiman) were found in positive animals. The highest serological prevalence in sheep and goats was recorded for serovar poi, followed by pomona in sheep and shermani in goats. Titres to shermani were the commonest in dogs. The results of this survey indicate that leptospiral infection is common in south-east Bolivia and that serovars of several serogroups concur in the etiology.

  15. Varve deposition and the sediment yield record at three small lakes of the southern Canadian Cordillera

    SciTech Connect

    Desloges, J.R. )

    1994-05-01

    Lacustrine sediments deposited in three small glacier-fed lakes of the southern Canadian Cordillera are derived primarily from subglacial erosion and delivered via short proglacial streams or by direct melting and calving of cirque glaciers. Sediment transport and deposition during early summer is controlled by runoff-generated bottom currents and in the late summer through winter by settling from suspension. This forms distinct rhythmic laminations of silt and clay in distal lake areas. Cesium-137 content in all three lakes indicates that these are varve sediments. Time series of varve thickness covering the interval 1863 to present show distinct declines in sediment yield from 310 to less than 150 t km[sup [minus]2] a[sup [minus]1]. The decline is related to sediment exhaustion following glacier retreat from Little Ice Age maxima and the opening of intervening sediment storage sites. Annual varve thickness is significantly related to fluctuations in summer or late summer temperature highlighting the importance of ice ablation, melt-water runoff, and subglacial sediment sources in controlling deposition rates. Singular climate events, such as autumn storms provide distinctive sedimentary signatures in the varve record. Reconstructed sediment yield for the Little Ice Age is as much as 100% greater than the average Holocene rate. 39 refs., 8 figs., 2 tabs.

  16. The unusual nature of recent snowpack declines in the North American cordillera

    USGS Publications Warehouse

    Pederson, Gregory T.; Gray, Stephen T.; Woodhouse, C.A.; Betancourt, Julio L.; Fagre, Daniel B.; Littell, Jeremy S.; Watson, Emma; Luckman, B.H.; Graumlich, Lisa J.

    2015-01-01

    In western North America, snowpack has declined in recent decades, and further losses are projected through the 21st century. Here, we evaluate the uniqueness of recent declines using snowpackreconstructions from 66 tree-ring chronologies in key runoff-generating areas of the Colorado, Columbia, and Missouri River drainages. Over the past millennium, late 20th century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains and in their north-south synchrony acrossthe cordillera. Both the snowpack declines and their synchrony result from unparalleled springtime warming that is due to positive reinforcement of the anthropogenic warming by decadal variability. The increasing roleof warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

  17. [Lipid and fatty acid profile of Perna viridis, green mussel (Mollusca: Bivalvia) in different areas of the Eastern Venezuela and the West Coast of Trinidad].

    PubMed

    Koftayan, Tamar; Milano, Jahiro; D'Armas, Haydelba; Salazar, Gabriel

    2011-03-01

    The species Perna viridis is a highly consumed species, which fast growth makes it an interesting aquaculture alternative for Venezuelan and Trinidad coasts. With the aim to contribute with its nutritional value information, this study analyzed lipid and fatty acid contents from samples taken in five locations from Eastern Venezuela and three from Trinidad West Coast. Total lipids were extracted and quantified, from a pooled sample of 100 organisms per location, by standard gravimetric methods, and their identification and quantification was done by TLC/FID (Iatroscan system). Furthermore, the esterified fatty acids of total lipid, phospholipids and triacylglycerols were identified and quantified by gas chromatography. Eastern Venezuela samples from Los Cedros, La Brea and Chaguaramas showed the highest total lipid values of 7.92, 7.74 and 7.53, respectively, and the minimum values were obtained for La Restinga (6.08%). Among lipid composition, Chacopata samples showed the lowest phospholipid concentration (48.86%) and the maximum values for cholesterol (38.87%) and triacylglycerols (12.26%); besides, La Esmeralda and Rio Caribe samples exhibited maximum phospholipids (88.71 and 84.93 respectively) and minimum cholesterol (6.50 and 4.42%) concentrations. Saturated fatty acids represented between 15.04% and 65.55% within total lipid extracts, with maximum and minimum values for La Esmeralda and Chacopata, respectively. Polyunsaturated results resulted between 7.80 and 37.18%, with higher values in La Brea and lower values in La Esmeralda. For phospholipids, saturated fatty acids concentrations varied between 38.81 and 48.68% for Chaguaramas and Chacopata samples, respectively. In the case of polyunsaturated fatty acids, these varied between non detected and 34.51%, with high concentrations in Los Cedros (27.97%) and Chaguaramas (34.51%) samples. For the triacylglycerols, the saturated fatty acids composition oscillated between 14.27 and 53.80% with low

  18. Population dynamics of Eleutherodactylus coqui in cordillera forest reserves of Puerto Rico

    USGS Publications Warehouse

    Fogarty, J.H.; Vilella, F.J.

    2002-01-01

    Various aspects of population structure and dynamics of Eleutherodactylus coqui in two forest reserves (Maricao and Guilarte) of the central mountain range of Puerto Rico were determined between July 1997 and June 1998. Adult density ranged from 8-25 animals/100 m2 for the wet season and 3-19 animals/100 m2 for the dry season. Abundance of froglets and juveniles was also greater in the wet season compared to the dry season. By contrast, egg mass counts were greater in the dry season compared to the wet season. Adult body size increased from wet to dry season as population density declined and was found to differ significantly between forests. Adult E. coqui trapped at similar elevations were larger in Guilarte compared to those in Maricao. Average body size for Maricao and Guilarte populations were smaller than those reported for populations in eastern Puerto Rico. Comparing average snout-vent length among frogs from the Luquillo Mountains, Guilarte Forest, and Maricao Forest, a gradient of decreasing body size was observed from east to west across the island.

  19. Where do people from different socio-economic groups receive diagnosis and treatment for presumptive malaria, in south-eastern Nigeria?

    PubMed

    Onwujekwe, O; Ojukwu, J; Uzochukwu, B; Dike, N; Ikeme, A; Shu, E

    2005-07-01

    The relationship between the socio-economic status (SES) of a household and its sources of malaria diagnosis and treatment was explored in south-eastern Nigeria. One aim was to see if, as seems likely, the poorest people generally seek care from 'low-level' providers, such as traditional healers and community-based healthworkers, because of their severe budget constraints. Interviewer-administered questionnaires were used to collect information from 1197 randomly selected respondents from four villages where malaria is holo-endemic. An index was used to categorize the study households into SES quartiles. The self-diagnosis of presumptive malaria and the use of patent-medicine dealers for treatment were very common among all the SES groupings. Compared with the other interviewees, however, the least-poor were significantly more likely to rely on laboratory tests for diagnosis and to visit hospitals when seeking treatment for presumptive malaria. The most-poor, in contrast, were significantly more likely to seek treatment from traditional healers or community-based healthworkers. Thus, even though the use of low-level providers was so common, there was still evidence of wealth-related inequity--in terms of the probabilities of the good diagnosis and treatment of malaria. Improvements in the quality of malaria diagnosis and treatment by the providers patronised by the most-poor villagers would help to redress this inequity, at least in the short- to medium-term.

  20. Eastern Europe's Silicon Rush

    ERIC Educational Resources Information Center

    Woodard, Colin

    2007-01-01

    This article presents how the fast expansion of information technology industry in eastern Slovakia is putting a strain on its labor supply. Suddenly, computer-science graduates have become one of the former Eastern Bloc's greatest assets, attracting multinational technology companies hungry for skilled programmers, technicians, and engineers.…

  1. Late Cenozoic Deformation of the Coastal Cordillera, Northern Chilean Forearc, 18- 25°S

    NASA Astrophysics Data System (ADS)

    Allmendinger, R. W.; González, G.; Loveless, J. P.; Carrizo, D.

    2004-12-01

    Overlying the only part of the South American continental crust that is in direct contact with the subducting Nazca Plate, the Coastal Cordillera of northern Chile and southern Peru should provide the most complete geological record of the coupling between the two plates. This record of coupling is exquisitely preserved in the hyperarid Atacama Desert. This preservation is both one of the major advantages and major challenges of working in this region: On the positive side, exposure of geomorphic surfaces is complete and unencumbered by erosion or vegetation, and brittle saline soils preserve subtle deformation features that would quickly be obliterated in more humid environments. On the negative side, ancient geomorphic features are just as fresh as Recent one and the lack of organic material precludes radiocarbon dating, a traditional tool of paleoseismology. During the last several years, we have concentrated on documenting three fundamental characteristics of late Cenozoic forearc deformation: (1) NS shortening on reverse faults striking at a high angle to, and dextral-reverse faults striking oblique to, the continental margin; (2) N-striking normal faults of the forearc and their reactivation, locally, as reverse faults; and (3) extensive suites of tension cracks. Reverse faults striking at a high angle to the margin are present between 19 and 21.5°S, straddling the topographic symmetry plane that marks the axis of the Bolivian orocline. Limited dating of tuffs and surfaces shows that these structures have been active for at least the last 6 Ma. At least 5 of these structures -- Atajaña, Pisagua, Iquique north and south, and Barranco Alto -- cut the Pleistocene marine terraces of the coastal platform, producing 20 to 50 m of vertical offset. A forearc crustal earthquake just south of Pisagua in March 2007 demonstrates that margin parallel shortening continues to the present and that permanent deformation occurs during the interseismic part of the plate

  2. Late Cenozoic Deformation of the Coastal Cordillera, Northern Chilean Forearc, 18- 25°S

    NASA Astrophysics Data System (ADS)

    Allmendinger, R. W.; González, G.; Loveless, J. P.; Carrizo, D.

    2007-12-01

    Overlying the only part of the South American continental crust that is in direct contact with the subducting Nazca Plate, the Coastal Cordillera of northern Chile and southern Peru should provide the most complete geological record of the coupling between the two plates. This record of coupling is exquisitely preserved in the hyperarid Atacama Desert. This preservation is both one of the major advantages and major challenges of working in this region: On the positive side, exposure of geomorphic surfaces is complete and unencumbered by erosion or vegetation, and brittle saline soils preserve subtle deformation features that would quickly be obliterated in more humid environments. On the negative side, ancient geomorphic features are just as fresh as Recent one and the lack of organic material precludes radiocarbon dating, a traditional tool of paleoseismology. During the last several years, we have concentrated on documenting three fundamental characteristics of late Cenozoic forearc deformation: (1) NS shortening on reverse faults striking at a high angle to, and dextral-reverse faults striking oblique to, the continental margin; (2) N-striking normal faults of the forearc and their reactivation, locally, as reverse faults; and (3) extensive suites of tension cracks. Reverse faults striking at a high angle to the margin are present between 19 and 21.5°S, straddling the topographic symmetry plane that marks the axis of the Bolivian orocline. Limited dating of tuffs and surfaces shows that these structures have been active for at least the last 6 Ma. At least 5 of these structures -- Atajaña, Pisagua, Iquique north and south, and Barranco Alto -- cut the Pleistocene marine terraces of the coastal platform, producing 20 to 50 m of vertical offset. A forearc crustal earthquake just south of Pisagua in March 2007 demonstrates that margin parallel shortening continues to the present and that permanent deformation occurs during the interseismic part of the plate

  3. Mesozoic igneous activity in the southern Cordillera of North America: Implications for tectonics and magma genesis

    SciTech Connect

    Asmerom, Y.

    1988-01-01

    A representative section in Santa Rita Mountains is dated using the zircon U-Th-Pb isotopic method. The oldest unit, the lower member of the Mt. Wrightson Formation, is concordantly dated at 210 {plus minus} 3 Ma. Initial basaltic andesite to andesite volcanism was followed by deposition of red beds and associated volcanic rocks that are dated at 200 Ma. Felsic volcanism and eolian sand deposition may have spanned from 190 to 170 Ma. The Piper Gulch Granodiorite, representing the earliest Mesozoic intrusive equivalent, gives concordant dates of 188 {plus minus}2 Ma. A second cycle of andesite and rhyolitic volcanism and sedimentation is dated at 151 {plus minus} 5 Ma using the whole-rock Rb-Sr isotopic method. The Hovatter Volcanics in the Little Harquahala Mountains, southwestern Arizona is dated at 165 Ma. Whole-rock Rb-Sr isotopic method on the same rocks gives a coherent reset isochron of 70 {plus minus} 3 Ma. A new stratigraphic correlation is proposed based on the dating data. This part of the Cordillera was an uplifted arc terrane during the Early Mesozoic and may have provided volcanic detritus to the Late Triassic Chinle Formation in the Colorado Plateau. The second part deals with magma evolution and crust modification during arc magmatism. Rocks in southeastern Arizona have {sub Nd} values of {minus}3.4 to {minus}6.4, while rocks to the west have {sub Nd} values ranging from {minus}8.5 to {minus}9.2. Combined REE and isotopic data indicate that assimilation of lower crust by mantle melts followed by fractional crystallization took place.

  4. Paleontologic and stratigraphic relations of phosphate beds in Upper Cretaceous rocks of the Cordillera Oriental, Colombia

    USGS Publications Warehouse

    Maughan, Edwin K.; Zambrano O., Francisco; Mojica G., Pedro; Abozaglo M., Jacob; Pachon P., Fernando; Duran R., Raul

    1979-01-01

    Phosphorite crops out in the Cordillera Oriental of the Colombian Andes in rocks of Late Cretaceous age as strata composed mostly of pelletal carbonate fluorapatite. One stratum of Santonian age near the base of the Galembo Member of the La Luna Formation crops out at many places in the Departments of Santander and Norte de Santander and may be of commercial grade. This stratum is more than one meter thick at several places near Lebrija and near Sardinata, farther south it is locally one meter thick or more near the base of the Guadalupe Formation in the Department of Boyaca. Other phosphorite beds are found at higher stratigraphic levels in the Galembo Member and the Guadalupe Formation, and at some places these may be commercial also. A stratigraphically lower phosphorite occurs below the Galembo Member in the Capacho Formation (Cenomanian age) in at least one area near the town of San Andres, Santander. A phosphorite or pebbly phosphate conglomerate derived from erosion of the Galembo Member forms the base of the Umir Shale and the equivalent Colon Shale at many places. Deposition of the apatite took place upon the continental shelf in marine water of presumed moderate depth between the Andean geosyncline and near-shore detrital deposits adjacent to the Guayana shield. Preliminary calculations indicate phosphorite reserves of approximately 315 million metric tons in 9 areas, determined from measurements of thickness, length of the outcrop, and by projecting the reserves to a maximum of 1,000 meters down the dip of the strata into the subsurface. Two mines were producing phosphate rock in 1969; one near Turmeque, Boyaca, and the other near Tesalia, Huila.

  5. Diagnosing the imbalance of Yanamarey Glacier in the Cordillera Blanca of Peru

    NASA Astrophysics Data System (ADS)

    Hastenrath, Stefan; Ames, Alcides

    1995-03-01

    A detailed glaciological observation program was conducted on the Yanamarey Glacier in the Cordillera Blanca of Peru, including the monitoring of net balance and ice flow velocity during 1977-1988 and mappings of the surface topography in 1973, 1982, and 1988. These observations are here evaluated to combine net balance, surface lowering, and ice flow into a consistent picture of the mode of operation of a tropical glacier on the scale of a decade. The glacier extends between 5100 and 4500 m with a total area of 9×105 m2 and length of about 1.3 km. Maximum flow velocity is 17.4 m yr-1 and maximum volume flux 336×103 m3 yr-1. In the ablation area, net balance is about -6 m yr-1 and surface lowering 3 m yr-1. About half of the mean annual water discharge from the glacier of 80 L s-1 is not renewed by precipitation but supplied by the ice thinning. The rate of surface lowering of 1.5 m yr-1 liquid water equivalent translates to a glacier average departure heat supply for melting of 16 W m-2. Sensitivity analyses indicate that this could be produced by a cloudiness increase of less than one tenth, an air temperature decrease of 2°C, an increment in specific humidity of less than 1 g kg-1, or some combination of heat budget processes. Such changes in the atmospheric environment would be required to stabilize the glacier at its recent volume. As another indication of the recent imbalance, the maximum volume flux is found some 100 m below the equilibrium line altitude. Under continuation of the recent climatic conditions, the glacier may survive for more than half a century.

  6. Water Resources and Groundwater in a Glaciated Andean Watershed (Cordillera Blanca, Peru)

    NASA Astrophysics Data System (ADS)

    McKenzie, J. M.; Gordon, R.; Baraer, M.; Lautz, L.; Mark, B. G.; Wigmore, O.; Chavez, D.; Aubry-Wake, C.

    2014-12-01

    It is estimated that almost 400 million people live in watersheds where glaciers provide at least 10% of the runoff, yet many questions remain regarding the impact of climate change and glacier recession on water resources derived from these high mountain watersheds. We present research from the Cordillera Blanca, Peru, an area with the highest density of glaciers in the tropics. While glacier meltwater buffers stream discharge throughout the range, groundwater is a major component of dry season runoff, contributing up to 50-70% of outflow in some tributaries. In order to predict future changes to water resources it is critical to understand how groundwater can offset future hydrologic stress by maintaining stream baseflow, including recharge mechanisms, subsurface pathways, storage, and net fluxes to rivers. We present a synthesis of results based on hydrologic modeling, drilling/piezometers, geophysics, and artificial and natural hydrologic tracers. Our findings show that 'pampas', low-relief mountain valleys, are critical for baseflow generation by storing groundwater on interannual timescales. Pampas have a total area of ~65 km2 and are comprised of unconsolidated glacial, talus, lacustrine and wetland (bofedales) deposits. The valleys commonly have buried talus aquifers that are overlain by low permeability, glaciolacustrine deposits. Glaciofluvial outwash deposits and small wetlands also act as unconfined aquifers. These groundwater systems appear to be primarily recharged by wet season precipitation, and at higher elevations also by glacial meltwater. Additionally a ubiquitous feature in the valleys are springs, often located at the base of talus deposits, which generate a large hydrologic flux within the hydrologic systems. While glaciers are the most visible and vulnerable component of the Andean waterscape, we argue that it is crucial to understand the complete mountain hydrologic cycle, including groundwater, in order to understand the ongoing

  7. Hydrological and depositional processes associated with recent glacier recession in Yanamarey catchment, Cordillera Blanca (Peru).

    PubMed

    López-Moreno, J I; Valero-Garcés, B; Mark, B; Condom, T; Revuelto, J; Azorín-Molina, C; Bazo, J; Frugone, M; Vicente-Serrano, S M; Alejo-Cochachin, J

    2017-02-01

    In this study, we investigate changes in the glaciated surface and the formation of lakes in the headwater of the Querococha watershed in Cordillera Blanca (Peru) using 24 Landsat images from 1975 to 2014. Information of glacier retreat was integrated with available climate data, the first survey of recent depositional dynamics in proglacial Yanamarey Lake (4600m a.s.l.), and a relatively short hydrological record (2002-2014) at the outlet of Yanamarey Lake. A statistically significant temperature warming (0.21°C decade(-1) for mean annual temperature) has been detected in the region, and it caused a reduction of the glacierized area since 1975 from 3.5 to 1.4km(-2). New small lakes formed in the deglaciated areas, increasing the flooded area from1.8ha in 1976 to 2.8ha in 2014. A positive correlation between annual rates of glacier recession and runoff was found. Sediment cores revealed a high sedimentation rate (>1cmyr(-1)) and two contrasted facies, suggesting a shift toward a reduction of meltwater inputs and higher hydrological variability likely due to an increasing role of precipitation on runoff during the last decades. Despite the age control uncertainties, the main transition likely occurred around 1998-2000, correlating with the end of the phase with maximum warming rates and glacier retreat during the 1980s and 1990s, and the slowing down of expansion of surface lake-covered surface. With this hydrological - paleolimnological approach we have documented the association between recent climate variability and glacier recession and the rapid transfer of hydroclimate signal to depositional and geochemical processes in high elevation Andean environments. This, study also alerts about water quality risks as proglacial lakes act as secondary reservoirs that trap trace and minor elements in high altitude basins.

  8. Building A Middle Eastern Alliance

    DTIC Science & Technology

    2015-02-12

    implementation of NATO model to METO by reviewing NATO and suggesting some applications . Thesis This paper proposes building a Middle Eastern alliance to...ranging from terror activity and insurgency to a full- scale conventional war. The US contribution to the alliance may also include extending its...and alliance history is no different. NATO was founded to oppose a Soviet threat. The threat is long gone but NATO is still extremely relevant and

  9. Time-scales of assembly and thermal history of a composite felsic pluton: constraints from the Emerald Lake area, northern Canadian Cordillera, Yukon

    NASA Astrophysics Data System (ADS)

    Coulson, Ian M.; Villeneuve, Mike E.; Dipple, Gregory M.; Duncan, Robert A.; Russell, James K.; Mortensen, James K.

    2002-05-01

    Knowledge of the time-scales of emplacement and thermal history during assembly of composite felsic plutons in the shallow crust are critical to deciphering the processes of crustal growth and magma chamber development. Detailed petrological and chemical study of the mid-Cretaceous, composite Emerald Lake pluton, from the northern Canadian Cordillera, Yukon Territory, coupled with U-Pb and 40Ar/ 39Ar geochronology, indicates that this pluton was intruded as a series of magmatic pulses. Intrusion of these pulses produced a strong petrological zonation from augite syenite, hornblende quartz syenite and monzonite, to biotite granite. Our data further indicate that multiple phases were emplaced and cooled to below the mineral closure temperatures over a time-scale on the order of the resolution of the 40Ar/ 39Ar technique (˜1 Myr), and that emplacement occurred at 94.3 Ma. Simple thermal modelling and heat conduction calculations were used to further constrain the temporal relationships within the intrusion. These calculations are consistent with the geochronology and show that emplacement and cooling were complete in less than 100 kyr and probably 70±5 kyr. These results demonstrate that production, transport and emplacement of the different phases of the Emerald Lake pluton occurred essentially simultaneously, and that these processes must also have been closely related in time and space. By analogy, these results provide insights into the assembly and petrogenesis of other complex intrusions and ultimately lead to an understanding of the processes involved in crustal development.

  10. High-resolution clay mineralogy as a proxy for orbital tuning: Example of the Hauterivian-Barremian transition in the Betic Cordillera (SE Spain)

    NASA Astrophysics Data System (ADS)

    Moiroud, Mathieu; Martinez, Mathieu; Deconinck, Jean-François; Monna, Fabrice; Pellenard, Pierre; Riquier, Laurent; Company, Miguel

    2012-12-01

    The response of clay mineral assemblages to potential orbital forcing is tested in Mesozoic hemipelagic marl-limestone rhythmites of the Río Argos section (Betic Cordillera, Southeastern Spain). Along the section, marls are pervasively enriched in kaolinite and illite, whereas limestones are enriched in smectite-rich illite/smectite mixed-layers, suggesting that marl-limestone alternations are produced by cyclic high-frequency fluctuations of continental runoff. Spectral analyses show that clay mineral assemblages evolve accordingly to precession, obliquity and eccentricity cycles. Durations of ammonite zones are assessed at 535 kyr for the Late Hauterivian Pseudothurmannia ohmi Zone and at 645 kyr and for the Early Barremian Taveraidiscus hugii Zone. These durations are in agreement with other cyclostratigraphic estimates but significantly differ from the Geologic Time Scale 2004 and 2008. Clay minerals display enhanced amplitude of the eccentricity cycles during the Faraoni Oceanic Anoxic Event due to enhanced continental weathering conditions prevailing at that time. Sedimentary expression of the 405-kyr eccentricity is disturbed by palaeoclimate changes during the Faraoni OAE, challenging the hypothesis of Cretaceous OAE triggered by eccentricity cycles. Although palaeoceanographic events (e.g. Faraoni OAE) may induce disturbances in the clay mineral record, this study demonstrates the potential of these minerals to be used as a proxy for orbital calibration in Mesozoic times.

  11. Constraining Subsurface Structure and Composition Using Seismic Refraction Surveys of Proglacial Valleys in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Glas, R. L.; Lautz, L.; McKenzie, J. M.; Mark, B. G.; Baker, E. A.; Aubry-Wake, C.; Somers, L. D.; Wigmore, O.

    2015-12-01

    As tropical glaciers rapidly recede in response to climate change, the storage and discharge of groundwater will play an increasing role in regulating river baseflow, particularly during the dry season, when stream flow is currently sustained predominantly by glacial melt. Little is understood regarding the hydrogeologic processes controlling base flow characteristics of low-gradient proglacial valleys of the Cordillera Blanca in Northwestern Peru, which has the world's highest density of tropical glaciers. To better understand the processes of groundwater storage and discharge in proglacial meadows, we completed seismic refraction surveys in three representative valleys of the Cordillera Blanca range: the Quilcayhuanca, Yanamarey, and Pachacoto valleys. The locations of survey transects were chosen based on locations of previous sediment core sampling, GPR lines, and quantification of groundwater-surface water interaction derived from dye and temperature tracing experiments. The seismic surveys consisted of 48 vertical component geophones with 2.5 m spacing. Across the three representative valleys a total of 15 surveys were conducted, covering a distance of 1800 m in cross, down, and oblique-valley directions. Preliminary interpretation of the seismic refraction data indicates a maximum imaging depth of 16 m below land surface, and a transition from glacio-lacustrine sediments to buried saturated talus at a depth of 6 m in the Quilcayhuanca valley. The organic-rich glacio-lacustrine sediments in the Yanamarey valley have seismic velocities ranging from 300 to 800 m/s and are >16 m in thickness at mid- valley. Weathered metasedimentary bedrock in the Pachacoto valley was imaged at ~5 m below the valley surface, exhibiting a p-wave velocity of 3400 m/s. The knowledge of hydrogeologic structure derived from seismic refraction surveys will provide crucial boundary conditions for future groundwater models of the valleys of the Cordillera Blanca.

  12. Glacier Inventory of the Cordillera Real - Bolivia using high resolution satellite images ALOS and CBERS-2B

    NASA Astrophysics Data System (ADS)

    Ramirez, E.; Ribeiro, R.; Machaca, A.; Fuertes, R.; Simões, J.

    2012-04-01

    The Andes represent approximately 99% of tropical glaciers worldwide. In Bolivia (South America) the glacier coverage represents 20% of the Andean glaciers. During the last 30 years a dramatic reduction of glacier surfaces in the Bolivian Andes were observed (Ramirez et al. 2001), leading to fears about the disappearance of several small glaciers in the next three decades. The first glacier inventory in this region was made based on aerial photographs for the 70's and 80's using geodetic methods (Jordan 1991). However, the realization of new photogrammetric flights over the Andes is expensive, which made it impossible to update the glacier inventory. Most Bolivian glaciers are less than 1 km2 making it difficult to use conventional satellite imagery with average resolutions (15 m or 30m). The development of new high resolution sensors mounted on observational satellites with stereoscopic capabilities permits the application of photogrammetric techniques for the precise delimitation of glacier boundaries. A new glacier inventory of the Cordillera Real in Bolivia was performed using high-resolution images (2.5 m) from ALOS (Japan) and CBERS-2B (China-Brazil) satellites within the framework of the Andean Regional Project on Climate Change Adaptation (PRAA) supported by the World Bank. The PRISM sensor of ALOS satellite (Panchromatic Remote-sensing Instrument for Stereo Mapping) and HRC of CBERS-2B satellite (High Resolution Panchromatic Camera) were used in this study. 57 ground control points (GCP) were measured along the Cordillera Real through dual-frequency DGPS's. The boundaries of 476 glaciers were identified and digitized by a digital photogrammetric station. The current glacier surface of the Cordillera Real is 185.5 km2. Compared with the previous inventory of the 80's it represent a loss of 43% of the glacier area.

  13. Cretaceous exhumation history of Cordillera Darwin, southern Patagonia, from patchily recrystallized garnet and U-Th-Pb monazite dating

    NASA Astrophysics Data System (ADS)

    Maloney, K. T.; Clarke, G. L.; Klepeis, K. A.; Fanning, C. M.; Wang, W.

    2010-12-01

    Garnet in amphibolite facies pelitic schists from Bahía Pia of Cordillera Darwin displays patchy textures whereby a single grain may have regions of turbid garnet with comparatively large inclusions of biotite, muscovite, plagioclase and quartz, juxtaposed against a region of clear, “ordinary” garnet. Clear areas with S1 inclusion trails are grossular rich, whereas post-S1 turbid areas are comparatively spessartine-pyrope rich. Raman spectroscopy identified the presence of an aqueous solution in turbid regions of garnet, lacking from clear areas. Turbid patches are associated with the growth of S2 kyanite and staurolite. Pseudosection modelling in Na2O-CaO-K2O-FeO-MgO-Al2O3-SiO2-H2O-TiO2-Fe2O3 (NCKFMASHTO) is consistent with garnet mode decreasing from c. 5% to less than 1% during exhumation of Cordillera Darwin, coinciding with the growth of S2 kyanite and staurolite at P≈9 kbar and T≈625°C. Turbid garnet in patchy and atoll-style textures is inferred to reflect recrystallization facilitated by fluid ingress whereby garnet cores, formed at higher P-T conditions than the rims, were preferentially recrystallised along grain cracks and boundaries. P-T paths inferred from the modelling indicate higher metamorphic conditions than previously documented, P conditions declining from 12 to 9 kbar over T= 610 to 630°C. U-Th-Pb dating of S2 monazite indicates that rapid exhumation was underway before 72.61±1.13 Ma, reflecting a tectonic shift from burial to uplift of Cordillera Darwin between c. 86 and c. 73 Ma. Sillimanite-bearing assemblages are restricted to contact aureoles associated with the intrusion of the Late Cretaceous Beagle Suite at shallower crustal conditions.

  14. Mapping Glacier Dynamics and Proglacial Wetlands with a Multispectral UAV at 5000m in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Wigmore, O.; Mark, B. G.

    2015-12-01

    The glaciers of the Cordillera Blanca, Peru are rapidly retreating as a result of rising temperatures, transforming the hydrology and impacting the socio-economic and environmental systems of the Rio Santa basin. Documenting the heterogeneous spatial patterns of these changes to understand processes of water storage and flow is hindered by technologic and logistic challenges. Highly complex topography, cloud cover and coarse spatial resolution limit the application of satellite data while airborne data collection remains costly and potentially dangerous. However, recent developments have made Unmanned Aerial Vehicle (UAV) technology a viable and potentially transformative method for studying glacier dynamics and proglacial hydrology. The extreme altitudes (4000-6700m) of the Cordillera Blanca limit the use of 'off the shelf' UAVs. Therefore we developed a low cost multispectral (visible, near-infrared and thermal infrared) multirotor UAV capable of conducting fully autonomous aerial surveys at elevations over 5000m within the glacial valleys of the Cordillera Blanca. Using this platform we have completed repeat aerial surveys (in 2014 and 2015) of the debris covered Llaca Glacier, generating highly accurate 10-20cm DEM's and 5cm orthomosaics using a structure from motion workflow. Analysis of these data reveals a highly dynamic system with some areas of the glacier losing as much as 16m of vertical elevation, while other areas have gained up to 5m of elevation over one year. The magnitude and direction of these changes appears to be associated with the presence of debris free ice faces and meltwater ponds. Additionally, we have mapped proglacial meadow and wetland systems. Thermal mosaics at 10-20cm resolution are providing novel insights into the hydrologic pathways of glacier meltwater including mapping the distribution of artesian springs that feed these wetland systems. The high spatial resolution of these UAV datasets facilitates a better understanding of the

  15. Crustal and upper mantle anisotropy associated with fossilized transpression along the Denali Fault, northern Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Rasendra, N.; Bonnin, M.; Marechal, A.; Tiberi, C.; Mazzotti, S.

    2013-12-01

    The Denali Fault is a major, ~1200 km-long, continental strike-slip fault that participates to the plate boundary system of western North America since the Early Cenozoic. In southwest Yukon, it accommodated ~400 km of dextral displacement in a late Cretaceous - Eocene transpression phase during which allochtonous terranes were accreted to the North America margin. Smaller strike-slip and thrust faults mark a 50 - 100 km wide tectonic corridor between the St. Elias Mountains and the central Yukon plateau, with the Denali Fault along its eastern edge. We examine the crustal and upper mantle structure in SW Yukon using a combination of receiver function (RF) and shear-wave splitting (SKS) analysis on a network of eleven seismic stations deployed in the Denali Fault region. To first order, crustal thickness (35 - 41 km) correlates well with the topography, indicating a ~5 km crustal root beneath the eastern side of the St. Elias Mountains. RFs display a strong P-to-S conversion within the crust, which systematically varies with back-azimuth. Stacking and inversion of RF according the two complementary back-azimuth ranges show a strong Vs anisotropy (> 10%) at mid-crustal depths (15 - 20 km) for a subset of stations within 5 - 25 km of the Denali Fault and inside its tectonic corridor. Other stations, further away or in a different geological setting, show a weaker (< 5%) anisotropy. This Vs anisotropy occurs in a low-velocity zone with the slow velocity axis perpendicular to the Denali Fault trend. Similarly, SKS splitting measurements indicate a strong Vs anisotropy in the upper mantle, with the fast direction parallel to the Denali Fault trend at all but one station within +/- 25 km from the fault. Present-day tectonics is well constrained by an array of campaign and permanent GPS stations in SE Alaska and SW Yukon. These data indicate that the Denali fault and its associated fault array currently accommodate less than 2 mm/yr of transpressional, dextral motion (< 5

  16. Eastern Equine Encephalitis

    MedlinePlus

    ... Facebook Tweet Share Compartir Image of Culiseta melanura mosquito, photo taken by Jason Williams, reproduced by permission from the Virginia Mosquito Control Association. Eastern equine encephalitis virus (EEEV) is ...

  17. Role of plate kinematics and plate-slip-vector partitioning in continental magmatic arcs: Evidence from the Cordillera Blanca, Peru

    SciTech Connect

    McNulty, B.A.; Farber, D.L.; Wallace, G.S.; Lopez, R.; Palacios, O.

    1998-09-01

    New structural and geochronological data from the Cordillera Blanca batholith in the Peruvian Andes, coupled with Nazca-South American plate-slip-vector data, indicate that oblique convergence and associated strike-slip partitioning strongly influenced continental magmatic arc evolution. Both the strain field and mode of magmatism (plutonism vs. volcanism) in the late Miocene Peruvian Andes were controlled by the degree to which the arc-parallel component of the plate slip vector was partitioned into the arc. Strong strike-slip partitioning at ca. 8 Ma produced arc-parallel sinistral shear, strike-slip intercordilleran basins and east-west-oriented tension fractures that facilitated emplacement of the Cordillera Blanca batholith (ca. 8.2 {+-} 0.2 Ma). Periods during which the strike-slip component was not partitioned into the arc (ca. 10 and ca. 7 Ma) were associated with roughly arc-normal contraction and ignimbrite volcanism. The data thus support the contention that contraction within continental magmatic arcs favors volcanism, whereas transcurrent shear favors plutonism. The tie between oblique convergence and batholith emplacement in late Miocene Peruvian Andes provides a modern analogue for batholiths emplaced as the result of transcurrent shear in ancient arcs.

  18. Recent trends in annual snowline variations in the northern wet outer tropics: case studies from southern Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Veettil, Bijeesh Kozhikkodan; Wang, Shanshan; Bremer, Ulisses Franz; de Souza, Sergio Florêncio; Simões, Jefferson Cardia

    2016-03-01

    This paper describes the changes in the annual maximum snowlines of a selected set of mountain glaciers at the southern end of the Cordillera Blanca between 1984 and 2015 using satellite images. Furthermore, we analysed the existing glacier records in the Cordillera Blanca since the last glacial maximum to understand the evolution of glaciers in this region over a few centuries. There was a rise in the snowline altitude of glaciers in this region since the late 1990s with a few small glacier advances. Historical to the present El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) records were also analysed to understand whether there was a teleconnection between the glacier fluctuations in the region and the phase changes of ENSO and PDO. We also assessed the variations in three important climatic parameters that influence the glacier retreat—temperature, precipitation, and relative humidity—over a few decades. We calculated the anomalies as well as the seasonal changes in these variables since the mid-twentieth century. There was an increase in temperature during this period, and the decrease in precipitation was not so prominent compared with the temperature rise. There was an exceptionally higher increase in relative humidity since the early 2000s, which is relatively higher than that expected due to the observed rate of warming, and this increase in humidity is believed to be the reason behind the unprecedented rise in the snowline altitudes since the beginning of the twenty-first century.

  19. Structure of the Cordillera de la Costa Belt, North-Central Venezuela: Implications for plate tectronic models

    SciTech Connect

    Ave Lallemant, H.G.; Sisson, V.B.; Wright, J.E. )

    1993-02-01

    Preliminary results of an on-going study of the Cordillera de la Costa belt between Puerto Cabello and Choroni, north-central Venezuela, indicate that the deformational history is far more complicated than expected from simple plate-tectonic models. The Cordillera de la Costa belt consists of oceanic rocks (e.g., serpentinites, amphibilites, with lenses of eclogite and blueschist) intimately intermixed with metamorphosed continental margin deposits (e.g., mica and graphite schist, quartzite, marble). Locally, large granitic (basement ) complexes of Lower Paleozoic age are included as well. In late Cretaceous time, the entire belt was involved in four synmetamorphic deformations phases (D[sub 1a] to D[sub 1d]); the first (D[sub 1a]) occurred at depths of at 35-40 km and the later ones at successively shallower depths. This deformation occurred in a subduction zone, related to right-oblique convergence of the Farallon and Atlantic plates. The most penetrative structures resulted from (all in present coordinates) north-south contraction and east-west dextral simple shear (D[sub 1b]). During an Early Tertiary ( ) event (D[sub 2]), the belt was emplaced southward onto the South American continental margin. Subsequent deformational structures (D[sub 3]) resulted in cross folds and faults (with small pull-apart basins) which are consistent with the eastward passage of the Caribbean past the South American plate.

  20. Simultaneous batholith emplacement, terrane/continent collision, and oroclinal bending in the Blue Mountains Province, North American Cordillera

    NASA Astrophysics Data System (ADS)

    Žák, Jiří; Verner, Kryštof; Tomek, Filip; Holub, František V.; Johnson, Kenneth; Schwartz, Joshua J.

    2015-06-01

    The North American Cordillera is a classic example of accretionary orogen, consisting of multiple oceanic terranes attached to the western margin of Laurentia during the Mesozoic times. Although the Cordillera is linear for most parts, terrane boundaries are at a high angle to the overall structural grain in several segments of the orogen, which has been a matter of longstanding controversy as to how and when these orogenic curvatures formed. This paper discusses mechanisms, kinematics, and timing of initiation of one of these major curvatures, the Blue Mountains Province in northeastern Oregon. Here magmatic fabric patterns and anisotropy of magnetic susceptibility in the Wallowa batholith record three phases of progressive deformation of the host Wallowa terrane during Early Cretaceous. First is terrane-oblique ~NE-SW shortening, interpreted as recording attachment of the amalgamated oceanic and fringing terranes to the continental margin during dextral convergence at ~140 Ma. Deformation subsequently switched to pure shear-dominated ~NNE-SSW shortening associated with crustal thickening, caused by continued impingement of the amalgamated Blue Mountains superterrane into a presumed westward concave reentrant in the continental margin at ~135-128 Ma. Upon impingement (at ~126 Ma), the northern portion of the superterrane became "locked," leading to reorientation of the principal shortening direction to ~NNW-SSE while its still deformable southern portion rotated clockwise about a vertical axis. We thus propose oblique bending as the main mechanism of the orocline formation whereby horizontal compressive forces resulting from plate convergence acted at an angle to the terrane boundaries.

  1. Volcanism subprogram: Volcanological interpretation of the northern part of the Occidental Cordillera of Bolivia, utilizing ERTS imagery

    NASA Technical Reports Server (NTRS)

    Brockmann, C. E. (Principal Investigator); Kussmaul, S.

    1973-01-01

    The author has identified the following significant results. In the present study, 6 ERTS-1 images have been interpreted on a 1:1 million scale (black and white) with the respective field reconnaissance. The area studied is located in the region bordering with Chile and includes the western part of the Bolivian Altiplano, the volcano Cordillera (western cordillera) and the northern part of Chile to the Pacific Coast. The greater part of this region is formed by Pliocene/Pleistocene volcani rock, which is discordant with the Tertiary sediments with intercalations of calcareous tuff. The ERTS-1 imagery permits the tracing of regional boundaries of the great volcanic formations and the alinements of the volcanic bodies along the fault zones. They also permit a clear examination of the volcanic apparatus, including their secondary forms, such as lava flows, parasitic cones, and lava domes. Because of the great scale, it is not possible to identify either the small structures or those of low relief. On the basis of the interpretation of the images, it is possible to give an idea of the relative age of the volcanoes.

  2. Tectonic and unroofing history of Neogene Manantiales foreland basin deposits, Cordillera Frontal (32°30'S), San Juan Province, Argentina

    NASA Astrophysics Data System (ADS)

    Pérez, Daniel J.

    2001-12-01

    The Miocene Manantiales foreland basin is located in Cordillera Frontal of San Juan, between 32°30' and 33°S. The unroofing study of the synorogenic Miocene deposits provides information about the structural evolution of Cordón de La Ramada fold-and-thrust belt. These Tertiary deposits are represented by the Chinches Formation and comprise seven members (Tc0-Tc6). They are the result of the uplift of Mesozoic sequences that crop out in La Ramada fold-and-thrust belt of the Cordillera Principal. Quaternary deposits unconformably overlying the Chinches Formation are composed of granitic and rhyolitic blocks, and represent the final uplift of the Cordón del Espinacito and a series of out-of-sequence thrusts. The unroofing studies also provide sufficient information to establish the out-of-sequence timing of the deformation at this latitude. Initial deposition of the Tertiary deposits can be dated at about 20 Ma, or early Miocene. Andesitic lavas dated in 9.2±0.3, 10.7±0.7, and 12.7±0.7 Ma unconformably overlie the structure of La Ramada fold-and-thrust belt. These facts constrain the uplift of the High Andes between 20 and 10 Ma at this latitude. The unconformity between Tertiary and Quaternary deposits suggests final uplift during Pliocene-Pleistocene times.

  3. Recent glacier retreat and lake formation in the Querecocha watershed, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    López Moreno, J.; Valero-Garces, B.; Revuelto, J.; Azorín-Molina, C.; Bazo, J.; Cochachin, A.; Fontaneda, S.; Mark, B. G.

    2013-12-01

    In the Andes, and specifically in the Peruvian mountains a marked decrease of the glaciated area has occurred since the end of the Little Ice Age, and it has been accelerated since the last decades of the 20th century. As a result of the glacier retreat new pro-glaciar lakes are originated, and often the area and volume of existing ones increases. The study of these newly-formed lakes and their recent evolution may provide a better understanding of the hydrological and geomorphological evolution of deglaciated areas, and a better evaluation of the risk of glacial lakes outburst floods (GLOFS). In this work, we use 26 annual Landsat Thematic Mapper images from 1975 to 2010 to determine changes of the glaciated surface, snow line elevation and lakes formation in the headwaters of the Querecocha watershed in Cordillera Blanca (Perú). We also present the information derived from 10 short sediment cores (up to 50 cm long) retrieved along several transects in Yanamarey Lake. Both data sets inform of the sediment yield and lake development in recently deglaciated environments of the Andes. Results demonstrate that only one third of the surface covered by ice in 1975 remained in 2010. In this period, snowline has shifted up more than 100 meters in elevation in both, Yanamarey North and South areas respectively. At the same time, new lakes have been formed very quickly in these deglaciated areas. Preliminary 137Cs dating of Yanamarey sediment core indicates that at least the top 50 cm of the lake sequence deposited after 1960. This is coherent with the Landsat image of 1975 that showed the current surface of the lake still covered by ice. The high sediment rate (> 1 cm/yr) in the lake demonstrates the very high sediment yield in these geomorphically active settings. The sediment cores are composed of cm-thick sequences defined by grain-size (silt-clay) common in proglacial lakes reflecting the variability of hydrological response associated to the glacier retreat in the

  4. Structural analysis of the Cordillera Blanca detachment: Geometry, kinematics and fault rocks

    NASA Astrophysics Data System (ADS)

    Shaw, C. A.; Jessup, M. J.; Hughes, C. A.; Newell, D. L.

    2015-12-01

    The Cordillera Banca Detachment (CBD) in the north-central Peruvian Andes is recognized as a rare example of active extension parallel to the direction of shortening within a convergent orogenic setting. Despite longstanding interest in the geodynamic significance of the CBD relatively little work has been done to characterize the basic geometry, kinematics and evolution of the detachment or the petrology and distribution of brittle and ductile tectonites within the fault zone. This contribution presents preliminary results of a basic structural analysis of the CBD based on field observations, laboratory results, and GIS analysis. Basic structural observations of fault geometry and kinematics are needed to constrain the regional geodynamic role of the CBD. The NNW topographic trace of the CBD is defined by faceted ridges up to 2000 m in height. The lower slopes of the facets are locally cut by steep fault scarps that offset quaternary glacial moraines, debris fans and colluvium. The shear zone comprises both brittle and ductile tectonites including mylonite series rocks, pseudotachylyte, and breccia - often highly silicified. Highly polished mirrored surfaces are observed locally. Deformation mechanisms show a consistent progression from plastic in structurally lower positions to brittle in structurally higher positions. Evidence for overprinting deformation mechanisms is preserved in many samples. The shear zone ranges up to about 200 m thick. The average orientation of mylonitic foliation and fault slip surfaces (strike/dip = 140/30) and lineations/slickenlines (plunge-trend = 35-235) is quite consistent along the ~200 km detachment, but some systematic variation along strike may be related to concave fault segments or corrugations. Slip indicators are nearly down-dip with a minor left-lateral or right-lateral component in some locations. Offsets in marker horizons constrain total offset between about 4500 m near the central section of the fault to near zero

  5. Remelting of Nanogranites in Peritectic Garnet from Granulites of Jubrique, Betic Cordillera, Southern Spain

    NASA Astrophysics Data System (ADS)

    Acosta-Vigil, A.; Barich, A.; Bartoli, O.; Poli, S.; Cesare, B.; Garrido, C. J.

    2014-12-01

    Peritectic minerals in migmatites can trap droplets of melt that form via incongruent melting during crustal anatexis. In most cases, these melts crystallize and form nanogranites upon slow cooling of the anatectic terrane. To obtain information on the primary compositions of crustal melts, nanogranites must be remelted and rehomogenized before analysis. A new occurrence of nanogranites was reported in granulitic gneisses at the bottom of the prograde metamorphic sequence of Jubrique, located on top of the Ronda peridotite slab (Betic Cordillera, S Spain). These nanogranites are trapped in garnet porphyroblasts. They show partially irregular to well facetted negative crystal shapes, and have variable size from ~5-10 μm and reach ~200 μm in diameter. They appear at the core and rim of large Grt crystals, and are composed of rare glass, daughter Qz, Pl, Kfs, Bt and Ms, and solid inclusions of Ky and less frequently Gr, Hc, Rt, Ilm, Zrn and Mnz. Ky was the main solid phase that favored the trapping of melt inclusions (MI) during Grt growth. The presence of Ky+Rt within MI, and their occurrence in the high-P cores of Grt, suggest that partial melting in the gneisses initiated at relatively high P conditions, and that most Grt in these rocks crystallized in the presence of melt. To recover the major and trace element composition of the primary melt during anatexis, we performed remelting experiments on chips of MI-bearing Grt separated from a sample of gneiss at Jubrique, using a piston cylinder apparatus. Experiments were run at 800, 825 and 850°C, 15 Kbar and dry conditions (i.e. no added H2O) for 24 hrs. Preliminary results of the first experiment at 850º show that nanogranites have been successfully remelted; they all contain glass regardless of their textural position. Glass is leucogranitic (SiO2≈65wt%; FeO+MgO≈2wt%), potassic (K#≈12), high in ASI (close to peraluminous) and hydrous (H2O≈11wt.%.). The degree of remelting, however, varies among

  6. Barriers in access to healthcare in countries with different health systems. A cross-sectional study in municipalities of central Colombia and north-eastern Brazil.

    PubMed

    Garcia-Subirats, Irene; Vargas, Ingrid; Mogollón-Pérez, Amparo Susana; De Paepe, Pierre; da Silva, Maria Rejane Ferreira; Unger, Jean Pierre; Vázquez, María Luisa

    2014-04-01

    There are few comprehensive studies available on barriers encountered from the initial seeking of healthcare through to the resolution of the health problem; in other words, on access in its broad domain. For Colombia and Brazil, countries with different healthcare systems but common stated principles, there have been no such analyses to date. This paper compares factors that influence access in its broad domain in two municipalities of each country, by means of a cross-sectional study based on a survey of a multistage probability sample of people who had had at least one health problem within the last three months (2163 in Colombia and 2155 in Brazil). The results reveal important barriers to healthcare access in both samples, with notable differences between and within countries, once differences in sociodemographic characteristics and health needs are accounted for. In the Colombian study areas, the greatest barriers were encountered in initial access to healthcare and in resolving the problem, and similarly when entering the health service in the Brazilian study areas. Differences can also be detected in the use of services: in Colombia greater geographical and economic barriers and the need for authorization from insurers are more relevant, whereas in Brazil, it is the limited availability of health centres, doctors and drugs that leads to longer waiting times. There are also differences according to enrolment status and insurance scheme in Colombia, and between areas in Brazil. The barriers appear to be related to the Colombian system's segmented, non-universal nature, and to the involvement of insurance companies, and to chronic underfunding of the public system in Brazil. Further research is required, but the results obtained reveal critical points to be tackled by health policies in both countries.

  7. Potentiometric surface and water-level difference maps of selected confined aquifers in Southern Maryland and Maryland’s Eastern Shore, 1975-2015

    USGS Publications Warehouse

    Curtin, Stephen E.; Staley, Andrew W.; Andreasen, David C.

    2016-01-01

    Key Results This report presents potentiometric-surface maps of the Aquia and Magothy aquifers and the Upper Patapsco, Lower Patapsco, and Patuxent aquifer systems using water levels measured during September 2015. Water-level difference maps are also presented for these aquifers. The water-level differences in the Aquia aquifer are shown using groundwater-level data from 1982 and 2015, while the water-level differences are shown for the Magothy aquifer using data from 1975 and 2015. Water-level difference maps for both the Upper Patapsco and Lower Patapsco aquifer systems are shown using data from 1990 and 2015. The water-level differences in the Patuxent aquifer system are shown using groundwater-level data from 2007 and 2015. The potentiometric surface maps show water levels ranging from 53 feet above sea level to 164 feet below sea level in the Aquia aquifer, from 86 feet above sea level to 106 feet below sea level in the Magothy aquifer, from 115 feet above sea level to 115 feet below sea level in the Upper Patapsco aquifer system, from 106 feet above sea level to 194 feet below sea level in the Lower Patapsco aquifer system, and from 165 feet above sea level to 171 feet below sea level in the Patuxent aquifer system. Water levels have declined by as much as 116 feet in the Aquia aquifer since 1982, 99 feet in the Magothy aquifer since 1975, 66 and 83 feet in the Upper Patapsco and Lower Patapsco aquifer systems, respectively, since 1990, and 80 feet in the Patuxent aquifer system since 2007.

  8. CO2-rich thermomineral groundwater in the Betic Cordilleras, southeastern Spain: Genesis and tectonic implications

    NASA Astrophysics Data System (ADS)

    Cerón, J. C.; Martín-Vallejo, M.; García-Rossell, L.

    The CO2-rich thermal groundwater in the Betic Cordilleras in Spain has been studied with regard to the geological and hydrogeological setting, physical and chemical characteristics, and 13C-isotope content. The study area is about 60km northeast of Almería city, in southeastern Spain. The thermomineral waters are plentiful and are related to regional geothermal anomalies. Temperatures of 20 -41°C, high bicarbonate concentrations (183-1824mg/L), and high amounts of PCO2 (<1.1bar) characterize the groundwater. CO2 spatial variations are related to proximity to the Carboneras, Palomares, and Guadalentín fault systems, which may be the surface representation of the zone of crustal thinning and magmatism. δ13C values probably indicate a deep source for the CO2, either the mantle or perhaps carbonate rocks in the metamorphic substratum. The high amount of CO2 in the groundwater causes problems in wells and severely restricts water usage. The hydrothermal features of this area are probably related to neotectonic activity. Résumé Les eaux thermales à teneurs élevées en CO2 des Cordillères Bétiques ont étéétudiées, spécialement en ce qui concerne les aspects géologiques et hydrogéologiques, leurs caractéristiques physiques et chimiques, et leurs teneurs en 13C. La zone d'étude est située à 60km environ au nord-est de la ville d'Almería, au sud-est de l'Espagne. Les eaux thermominérales sont nombreuses et sont en relation avec les anomalies géothermales régionales. L'eau souterraine a une température comprise entre 20-41°C, une concentration élevée en bicarbonates (entre 183 et 1824mg/L), et PCO2élevée (<1.1bars). Les variations spaciales de CO2 sont en rapport avec la proximité des systèmes de failles de Carboneras, Palomares et Guadalentin, et peuvent être la manifestation en surface d'une zone d'amincissement cortical. Les données de δ13C indiquent un apport probable d'origine profonde de CO2, éventuellement du manteau et/ou des

  9. PREDICTING OF RISKS OF GROUNDWATER AND SURFACE WATER POLLUTION WITH DIFFERENT CLASSES OF HERBICIDES IN SOIL IN EASTERN EUROPE CLIMATE CONDITIONS.

    PubMed

    Korshun, M; Dema, O; Kucherenko, O; Korshun, O; Garkavyi, S; Pelio, I; Antonenko, A; Velikaia, N

    2016-11-01

    Application of pesticides in modern agriculture is a powerful permanent risk factor for public health and the natural environment. The aim of the study was a comparative hygienic assessment of the danger of contamination of ground and surface water sources with most widely used herbicides of different chemical classes (sulfonylureas, imidazolinones, pirimidinilkarboksilovye compounds semicarbazones). Field hygienic experiments for studying of the residues dynamics of studied herbicides concentration in agrocenosis objects were made by us in different types of soils: chernozem, sod-podzolic, podzolized forest. Then the half-life periods (DT50) of the substances in the soil were calculated. It was found that according to GUS index there is a high probability of leaching into groundwater of sulfonylureas and imidazolinones; according to LEACH index all investigated substances have a high risk of run-off into groundwater and surface water.

  10. Timing of uplift in the Argentine Frontal Cordillera (34-32.5°S), through (U-Th)/He Thermochronology

    NASA Astrophysics Data System (ADS)

    Graber, N. R.; Hoke, G. D.; Metcalf, J. R.

    2010-12-01

    We use the apatite (U-Th)/He low temperature thermochronometer to study the rock uplift history in the Frontal Cordillera of Argentina between 32.5-34°S, where an abrupt transition in the subduction angle of the Nazca Plate occurs. The Andes in our study area are composed of three major physiographic and tectonic provinces, which have been uplifted as the deformation front stepped eastward over the last 20 Ma. From west to east they are the Principal Cordillera, Frontal Cordillera and Precordillera. The thin-skinned Aconcagua fold-thrust-belt, which today comprises the Principal Cordillera was active between ~20-8 Ma. The thick-skinned Frontal Cordillera began uplifting around 9 Ma. Finally, in the northern part of the study area, uplift and deformation of the Precordillera commenced between 5-2 Ma. South of 33°S, in the absence of the Precordillera, the total amount of crustal shortening is half that of the north, despite similar average and peak range elevations. Remnants of a regionally extensive paleolandscape are preserved in both areas. Two age-elevation profiles were collected from the granitic Permo-Triassic Choiyoi Group in the headwaters of the Rio Tunuyán (south of 33°S) and Rio Mendoza (north of 33°S). In the Tunyán area, 7 samples were collected between 2600 and 4500 m, with paleolandscape remnants at an elevation of ~5000 m. Total local relief in the Río Mendoza sampling area is 2800 m, from which the lower 1400 m were sampled between elevations of 2100 and 3500 m. We aim to constrain 1) the timing of the initiation of deformation-related exhumation of the proximal foredeep associated with the Aconcagua fold and thrust belt and 2) the rate of rock uplift induced river incision of the Rio Mendoza and Rio Tunyán as a proxy for surface uplift.

  11. La Niña-like conditions in the eastern equatorial Pacific and a stronger Choco jet in the northern Andes during the last glaciation

    NASA Astrophysics Data System (ADS)

    MartíNez, Ignacio; Keigwin, Lloyd; Barrows, Timothy T.; Yokoyama, Yusuke; Southon, John

    2003-06-01

    Six deep sea cores from the eastern equatorial Pacific (EEP) were analyzed for planktonic foraminifera and stable isotopes in order to reconstruct sea surface temperatures (SST) for the last 40 ka. South of the Equatorial Front the abundance of Globorotalia inflata increased, and SST decreased by >5°C (core ODP846B), creating a stronger SST meridional gradient and advection of the Peru Current than present for the ˜16-35 ka interval. A sharper SST meridional gradient forced stronger Choco jet events and a moisture increase in western Colombia, which supplied, through the San Juan River and the south-flowing equatorial and the Peru-Chile countercurrents, abundant hemipelagic quartz over the northern Peru basin (core TR163-31B). The Choco jet, and its associated mesoscale convective cells, provoked an increase in snow precipitation over the Central Cordillera of Colombia and the advance of the Murillo glacier. In synchrony with the intensified Choco jet events, the "dry island" effect over the Eastern Cordillera of Colombia intensified, and the level of Fuquene Lake dropped.

  12. Different routes of demographic changes in former Eastern bloc states at the turn of the 21st century based on the examples of Poland and Ukraine

    NASA Astrophysics Data System (ADS)

    Flaga, Małgorzata

    2012-01-01

    The article concerns the most important demographic processes that took place in two post-communist countries, Poland and Ukraine, after 1990. These countries differ in terms of economic changes that they have gone through so far. In case of Poland we may consider it as a success in reforming the economy, despite the fact that it caused certain negative social phenomena, e.g. large unemployment. On the other hand, in Ukraine, economic crisis was not stopped, but it is also deepening and its results have become significant modifiers of population processes. The changes in population number, natural growth and migration in both countries are the subjects of detailed analyses. They were presented in the context of the "secondary demographic transition", which Poland and Ukraine entered rapidly at the beginning of 1990, along with economic transformation and social changes.

  13. Differences in extreme low salinity timing and duration differentially affect eastern oyster (Crassostrea virginica) size class growth and mortality in Breton Sound, LA

    NASA Astrophysics Data System (ADS)

    La Peyre, Megan K.; Eberline, Benjamin S.; Soniat, Thomas M.; La Peyre, Jerome F.

    2013-12-01

    Understanding how different life history stages are impacted by extreme or stochastic environmental variation is critical for predicting and modeling organism population dynamics. This project examined recruitment, growth, and mortality of seed (25-75 mm) and market (>75 mm) sized oysters along a salinity gradient over two years in Breton Sound, LA. In April 2010, management responses to the Deepwater Horizon oil spill resulted in extreme low salinity (<5) at all sites through August 2010; in 2011, a 100-year Mississippi River flood event resulted in low salinity in late spring. Extended low salinity (<5) during hot summer months (>25 °C) significantly and negatively impacted oyster recruitment, survival and growth in 2010, while low salinity (<5) for a shorter period that did not extend into July (<25 °C) in 2011 had minimal impacts on oyster growth and mortality. In 2011, recruitment was limited, which may be due to a combination of low spring time salinities, high 2010 oyster mortality, minimal 2010 recruitment, cumulative effects from 10 years of declining oyster stock in the area, and poor cultch quality. In both 2010 and 2011, Perkinsus marinus infection prevalence remained low throughout the year at all sites and almost all infection intensities were light. Oyster plasma osmolality failed to match surrounding low salinity waters in 2010, while oysters appeared to osmoconform throughout 2011 indicating that the high mortality in 2010 may be due to extended valve closing and resulting starvation or asphyxiation in response to the combination of low salinity during high temperatures (>25 °C). With increasing management of our freshwater inputs to estuaries combined with predicted climate changes, how extreme events affect different life history stages is key to understanding variation in population demographics of commercially important species and predicting future populations.

  14. Differences in extreme low salinity timing and duration differentially affect eastern oyster (Crassostrea virginica) size class growth and mortality in Breton Sound, LA

    USGS Publications Warehouse

    LaPeyre, Megan K.; Eberline, Benjamin S.; Soniat, Thomas M.; La Peyre, Jerome F.

    2013-01-01

    Understanding how different life history stages are impacted by extreme or stochastic environmental variation is critical for predicting and modeling organism population dynamics. This project examined recruitment, growth, and mortality of seed (25–75 mm) and market (>75 mm) sized oysters along a salinity gradient over two years in Breton Sound, LA. In April 2010, management responses to the Deepwater Horizon oil spill resulted in extreme low salinity (<5) at all sites through August 2010; in 2011, a 100-year Mississippi River flood event resulted in low salinity in late spring. Extended low salinity (<5) during hot summer months (>25 °C) significantly and negatively impacted oyster recruitment, survival and growth in 2010, while low salinity (<5) for a shorter period that did not extend into July (<25 °C) in 2011 had minimal impacts on oyster growth and mortality. In 2011, recruitment was limited, which may be due to a combination of low spring time salinities, high 2010 oyster mortality, minimal 2010 recruitment, cumulative effects from 10 years of declining oyster stock in the area, and poor cultch quality. In both 2010 and 2011, Perkinsus marinusinfection prevalence remained low throughout the year at all sites and almost all infection intensities were light. Oyster plasma osmolality failed to match surrounding low salinity waters in 2010, while oysters appeared to osmoconform throughout 2011 indicating that the high mortality in 2010 may be due to extended valve closing and resulting starvation or asphyxiation in response to the combination of low salinity during high temperatures (>25 °C). With increasing management of our freshwater inputs to estuaries combined with predicted climate changes, how extreme events affect different life history stages is key to understanding variation in population demographics of commercially important species and predicting future populations.

  15. Accelerometers Identify New Behaviors and Show Little Difference in the Activity Budgets of Lactating Northern Fur Seals (Callorhinus ursinus) between Breeding Islands and Foraging Habitats in the Eastern Bering Sea

    PubMed Central

    Battaile, Brian C.; Sakamoto, Kentaro Q.; Nordstrom, Chad A.; Rosen, David A. S.; Trites, Andrew W.

    2015-01-01

    We tagged 82 lactating northern fur seals (Callorhinus ursinus) with tri-axial accelerometers and magnetometers on two eastern Bering Sea islands (Bogoslof and St. Paul) with contrasting population trajectories. Using depth data, accelerometer data and spectral analysis we classified time spent diving (30%), resting (~7%), shaking and grooming their pelage (9%), swimming in the prone position (~10%) and two types of previously undocumented rolling behavior (29%), with the remaining time (~15%) unspecified. The reason for the extensive rolling behavior is not known. We ground-truthed the accelerometry signals for shaking and grooming and rolling behaviors—and identified the acceleration signal for porpoising—by filming tagged northern fur seals in captivity. Speeds from GPS interpolated data indicated that animals traveled fastest while in the prone position, suggesting that this behavior is indicative of destination-based swimming. Very little difference was found in the percentages of time spent in the categorical behaviors with respect to breeding islands (Bogoslof or St. Paul Island), forager type (cathemeral or nocturnal), and the region where the animals foraged (primarily on-shelf <200m, or off-shelf > 200m). The lack of significant differences between islands, regions and forager type may indicate that behaviors summarized over a trip are somewhat hardwired even though foraging trip length and when and where animals dive are known to vary with island, forager type and region. PMID:25807552

  16. Accelerometers identify new behaviors and show little difference in the activity budgets of lactating northern fur seals (Callorhinus ursinus) between breeding islands and foraging habitats in the eastern Bering Sea.

    PubMed

    Battaile, Brian C; Sakamoto, Kentaro Q; Nordstrom, Chad A; Rosen, David A S; Trites, Andrew W

    2015-01-01

    We tagged 82 lactating northern fur seals (Callorhinus ursinus) with tri-axial accelerometers and magnetometers on two eastern Bering Sea islands (Bogoslof and St. Paul) with contrasting population trajectories. Using depth data, accelerometer data and spectral analysis we classified time spent diving (30%), resting (~7%), shaking and grooming their pelage (9%), swimming in the prone position (~10%) and two types of previously undocumented rolling behavior (29%), with the remaining time (~15%) unspecified. The reason for the extensive rolling behavior is not known. We ground-truthed the accelerometry signals for shaking and grooming and rolling behaviors--and identified the acceleration signal for porpoising--by filming tagged northern fur seals in captivity. Speeds from GPS interpolated data indicated that animals traveled fastest while in the prone position, suggesting that this behavior is indicative of destination-based swimming. Very little difference was found in the percentages of time spent in the categorical behaviors with respect to breeding islands (Bogoslof or St. Paul Island), forager type (cathemeral or nocturnal), and the region where the animals foraged (primarily on-shelf <200 m, or off-shelf > 200 m). The lack of significant differences between islands, regions and forager type may indicate that behaviors summarized over a trip are somewhat hardwired even though foraging trip length and when and where animals dive are known to vary with island, forager type and region.

  17. Eastern Pacific Ocean Conference

    NASA Astrophysics Data System (ADS)

    The promotion of interaction among investigators of all oceanographic disciplines studying the eastern Pacific Ocean was the goal of the 1990 Eastern Pacific Ocean Conference (EPOC), held October 17-19 on the snow-covered slopes of Mt. Hood, Oreg. Thirty oceanographers representing all disciplines attended.Dick Barber, Duke University Marine Lab, Beaufort, N.C., chaired a session on the eastern equatorial Pacific Ocean, emphasizing issues related to biological activity. Steve Ramp of the Naval Postgraduate School in Montery, Calif., chaired a session on recent results from northern and central California experiments. On October 19, following an early morning earthquake, a business meeting and discussions regarding a collaboration in future experiments were held.

  18. Striated and pitted pebbles as paleostress markers: an example from the central transect of the Betic Cordillera (SE Spain)

    NASA Astrophysics Data System (ADS)

    Ruano, Patricia; Galindo-Zaldívar, Jesús

    2004-02-01

    Striated and pitted pebbles provide scarce structures that preserve information on the stresses that their host rocks have undergone. This information can be obtained by the measurement of a large number of microfaults with striae and solution marks within a small rock volume. For non-rotational deformation, the statistical procedures for microfault analysis provide a valid tool for determining the overprinting of successive stress ellipsoids, including their axial ratios and the orientations of the main axes. The trends of compressions obtained from striae can be compared with the determinations from the pole of pebble solution pits. However, in complex tectonics settings, the solution pits of several deformation phases are mixed and only striae analysis allows overprinted paleostresses to be accurately distinguished. The analysis of several pebbles from the same outcrop, including five from moderately complex settings, allows determination of the homogeneity of the paleostresses at outcrop scale, the detection of redeposited pebbles, and supports the results of microtectonic analysis for large areas. Solution mark distributions on pebbles depend on the burial and tectonic stresses. Conglomerates from shallow levels, such as those from Quaternary fluvial terraces, only record horizontal compressional solution marks because the minimum vertical stress needed to develop these structures are not reached by burial. In the central Betic Cordillera, striated and pitted pebbles are composed of carbonate surrounded by a matrix containing siliciclastic elements. The study of several outcrops located across a transect of the Cordillera shows a change in the recent stress field. While conglomerates near the Internal-External zone boundary show extensional stresses that may be related to the uplift of the Cordillera since Tortonian times, the outcrops located in the External Zone and up to the mountain front indicate the existence of horizontal NW-SE and NE-SW compressions

  19. Inequities in access to health care in different health systems: a study in municipalities of central Colombia and north-eastern Brazil

    PubMed Central

    2014-01-01

    Introduction Health system reforms are undertaken with the aim of improving equity of access to health care. Their impact is generally analyzed based on health care utilization, without distinguishing between levels of care. This study aims to analyze inequities in access to the continuum of care in municipalities of Brazil and Colombia. Methods A cross-sectional study was conducted based on a survey of a multistage probability sample of people who had had at least one health problem in the prior three months (2,163 in Colombia and 2,167 in Brazil). The outcome variables were dichotomous variables on the utilization of curative and preventive services. The main independent variables were income, being the holder of a private health plan and, in Colombia, type of insurance scheme of the General System of Social Security in Health (SGSSS). For each country, the prevalence of the outcome variables was calculated overall and stratified by levels of per capita income, SGSSS insurance schemes and private health plan. Prevalence ratios were computed by means of Poisson regression models with robust variance, controlling for health care need. Results There are inequities in favor of individuals of a higher socioeconomic status: in Colombia, in the three different care levels (primary, outpatient secondary and emergency care) and preventive activities; and in Brazil, in the use of outpatient secondary care services and preventive activities, whilst lower-income individuals make greater use of the primary care services. In both countries, inequity in the use of outpatient secondary care is more pronounced than in the other care levels. Income in both countries, insurance scheme enrollment in Colombia and holding a private health plan in Brazil all contribute to the presence of inequities in utilization. Conclusions Twenty years after the introduction of reforms implemented to improve equity in access to health care, inequities, defined in terms of unequal use for equal need

  20. Sex differences in the effect of birth order and parents' educational status on stunting: a study on Bengalee preschool children from eastern India.

    PubMed

    Biswas, Sadaruddin; Bose, Kaushik

    2010-08-01

    One of the greatest problems facing developing countries, including rural India, is undernutrition in terms of stunting among under 5-year-old children. However, there exists scanty information on the prevalence of stunting among preschool children in India and in particular in West Bengal. This study investigated prevalence of stunting and identified the predictor(s) of stunting among 1-5-year-old Bengalee rural preschool children of Integrated Child Development Services (ICDS) centres. This cross-sectional study was undertaken at different ICDS centres of Chapra Block, Nadia District, West Bengal, India. A total of 673 preschool children (323 boys and 350 girls), aged 1-5 years were selected from 30 randomly selected ICDS centres to study the impact of parents' educational status and child birth order on stunting. The overall (age and sex combined) rate of stunting was 39.2%. Child birth order (BO) (chi(2)=14.10, df=1, p<0.001), father educational status (FES) (chi(2)=21.11, p<0.001) and mother educational status (MES) (chi(2)=14.34, df=1, p>0.001) were significantly associated with the prevalence of stunting among girls. Logistic regression analyses revealed that both FES (Wald=19.97, p<0.001) as well as MES (Wald=13.95, p<0.001) were strong predictors of stunting among girls. Similarly BO (Wald=13.71, p<0.001) was a strong predictor of stunting among girls. Girls with >or=3rd BO had significantly higher risk (OR=2.49, CI=1.54-4.03) of stunting than those with or=secondary level. Similarly, girls with MESor=secondary level. In conclusion our study revealed that BO as well as parents' educational status were strong predictors of stunting among girls but not boys. Sex discrimination could be a likely cause for this

  1. Site fidelity, size, and morphology may differ by tidal position for an intertidal fish, Bathygobius cocosensis (Perciformes-Gobiidae), in Eastern Australia.

    PubMed

    Malard, Lucie A; McGuigan, Katrina; Riginos, Cynthia

    2016-01-01

    The intertidal zone is a transitional environment that undergoes daily environmental fluctuations as tides rise and fall. Relatively few fish species are adapted to endure the physiological pressures of this environment. This study focused on Bathygobius cocosensis (Gobiidae), a common intertidal fish in New South Wales, Australia. We investigated whether shore height impacted site fidelity, survival probability, fish size, and morphological traits with respect to tidal height. Mark-recapture methods were used over a five month period to determine if individuals in high shore pools had greater site fidelity; fish in high tide pools were more than twice as likely to be recaptured in their original pool than fish from low tide pools. High pool individuals were, on average, smaller with larger eyes and longer snouts relative to their size as compared to low pool individuals. We discuss several mechanisms that could cause the observed pattern in morphological variation. Ultimately, this study suggests that within species behaviour and morphology differ by tidal position for an intertidal fish.

  2. Site fidelity, size, and morphology may differ by tidal position for an intertidal fish, Bathygobius cocosensis (Perciformes-Gobiidae), in Eastern Australia

    PubMed Central

    Malard, Lucie A.; McGuigan, Katrina

    2016-01-01

    The intertidal zone is a transitional environment that undergoes daily environmental fluctuations as tides rise and fall. Relatively few fish species are adapted to endure the physiological pressures of this environment. This study focused on Bathygobius cocosensis (Gobiidae), a common intertidal fish in New South Wales, Australia. We investigated whether shore height impacted site fidelity, survival probability, fish size, and morphological traits with respect to tidal height. Mark-recapture methods were used over a five month period to determine if individuals in high shore pools had greater site fidelity; fish in high tide pools were more than twice as likely to be recaptured in their original pool than fish from low tide pools. High pool individuals were, on average, smaller with larger eyes and longer snouts relative to their size as compared to low pool individuals. We discuss several mechanisms that could cause the observed pattern in morphological variation. Ultimately, this study suggests that within species behaviour and morphology differ by tidal position for an intertidal fish. PMID:27547568

  3. Emerging Glacial Lakes in the Cordillera Blanca, Peru: A Case Study at Arteson Glacier

    NASA Astrophysics Data System (ADS)

    Chisolm, R. E.; Mckinney, D. C.; Gomez, J.; Voss, K.

    2012-12-01

    Tropical glaciers are an essential component of the water resources systems in the mountainous regions where they are located, and a warming climate has resulted in the accelerated retreat of Andean glaciers in recent decades. The shrinkage of Andean glaciers influences the flood risk for communities living downstream as new glacial lakes have begun to form at the termini of some glaciers. As these lakes continue to grow in area and volume, they pose an increasing risk of glacial lake outburst floods (GLOFs). Ice thickness measurements have been a key missing link in studying the tropical glaciers in Peru and how climate change is likely to impact glacial melt and the growth of glacial lakes. Ground penetrating radar (GPR) has rarely been applied to glaciers in Peru to measure ice thickness, and these measurements can tell us a lot about how a warming climate will affect glacier mass balance. This study presents GPR data taken in July 2012 at the Arteson glacier in the Cordillera Blanca, Peru. A new lake has begun to form at the terminus of the Arteson glacier, and this lake has key features, including overhanging ice and loose rock likely to create landslides, that could trigger a catastrophic GLOF if the lake continues to grow. This new lake is part of a series of three lakes that have formed below the Arteson glacier. The two lower lakes, Artesonraju and Paron, are much larger so that if there were an avalanche or landslide into the new lake below Arteson glacier, the impact could potentially be more catastrophic than a GLOF from one single lake. Estimates of how the lake mass balance is likely to evolve due to the retreating glacier are key to assessing the flood risk from this dynamic three-lake system. Because the glacier mass balance and lake mass balance are closely linked, the ice thickness measurements and measurements of the bed slope of the Arteson glacier and underlying bedrock give us a clue to how the lake is likely to evolve. GPR measurements of

  4. Early Cretaceous continental sedimentation in the Coastal Cordillera (Atajaña Formation), Northern Chile

    NASA Astrophysics Data System (ADS)

    Fuentes, G.; Garcia, M.; Sepulveda, F.; Vasquez, P.

    2013-12-01

    Early Cretaceous continental sedimentation development at the Coastal Cordillera of northern Chile has been described in a broad sense. The Atajaña Formation represents this continental sedimentation, south of Arica (18°30S), where it exposes mostly as an elongated swath oriented N70°E, forming a 20 km long and 8 km wide area of outcrop. Northward, these deposits occur as isolated outcrops at the bottom of Chiza, Camarones, Vitor and Azapa valleys. The Atajaña succession was deposited in apparent angular unconformity over Cuya Formation (Middle-Late Jurassic) and Chiza Formation (Bajocian-Oxfordian). The Atajaña Formation is overlain, conformable and transitional, by the Blanco Formation (Aptian-Albian) and overlain in erosion unconformity by the Suca Formation (upper Early Cretaceous). Angular unconformity contact between Atajaña Formation and Cenozoic units (Azapa Formation and alluvial deposits) is exposed at previously named valleys. In the Camarones valley, the Atajaña Formation unconformably overlies Middle to Late Jurassic intrusive rocks. In this work, the Atajaña Formation is divided in three facies associations, exposed close to Atajaña hill and Chiza valley (Kia1, Kia2 y Kia2a). Reddish conglomerates and sedimentary breccias facies (Kia1) consists of an up to 850 m thick. These rocks are massive, polymictic and poorly-sorted, and form laterally extensive beds. Clasts are mostly composed by diorites, monzodiorites, grayish fine sandstones, fine calcareous sandstones, limestones, volcarenites and porphyric andesites. Facies Kia1 includes interbedded red calcareous sandstones and siltstones, some of them displaying low-angle cross bedding. Facies Kia2 consists of an up to 570 m thick of red sandstone and siltstone, interbedded with conglomerates. This well stratified succession, parallel bedded and minor cross bedded, form continuous beds with subrounded and well-sorted clasts. Previous authors described dessication cracks in the red siltstones

  5. Remelting of nanogranites in peritectic garnet from granulites of Jubrique, Betic Cordillera, Southern Spain

    NASA Astrophysics Data System (ADS)

    Barich, Amel; Bartoli, Omar; Acosta-Vigil, Antonio; Poli, Stefano; Cesare, Bernardo; Garrido, Carlos J.

    2014-05-01

    Peritectic minerals in migmatites can trap droplets of melt that form via incongruent melting reactions during crustal anatexis [1]. In most cases, these melts crystallize and form nanogranites upon slow cooling of the anatectic terrane [2]. To obtain information on the primary compositions of crustal melts, including volatile concentrations in melt and information on fluid regimes, nanogranites must be remelted and rehomogenized before analysis [3]. A new occurrence of nanogranites was recently reported in granulitic gneisses at the bottom of the prograde metamorphic sequence of Jubrique, located on top of the Ronda peridotite slab (Betic Cordillera, S Spain) [4]. These nanogranites are trapped in garnet porphyroblasts. They show partially irregular to well facetted negative crystal shapes, and have variable size from ~5-10 μm to several tens of μm or even ~200 μm in diameter. They appear at the core and rim of large Grt crystals, and are composed of rare glass, daughter Qz, Pl, Kfs, Bt and Ms, and solid inclusions of Ky and less frequently Gr, Hc, Rt, Ilm, Zrn and Mnz. Ky was the main solid phase that favored the trapping of melt inclusions (MI) by poisoning crystal surfaces during Grt growth. The presence of Ky+Rt within MI, and their occurrence in the high-P cores of Grt, suggest that partial melting in the gneisses initiated at relatively high P conditions, and that most Grt in these rocks crystallized in the presence of melt. To recover the major and trace element composition of the primary melt during anatexis, we performed remelting experiments on chips of MI-bearing Grt separated from a sample of gneiss at Jubrique, using a piston cylinder apparatus. Experiments were run at 800, 825 and 850° C, 15 Kbar and dry conditions (i.e. no added H2O) for 24 hrs. Preliminary results of the first experiment at 850º show that nanogranites have been successfully remelted; they all contain glass regardless of their textural position, i.e. at the core and rim of

  6. The Meaning of High K2O Volcanism In the U.S. Cordillera

    NASA Astrophysics Data System (ADS)

    Putirka, K. D.; Busby, C.

    2010-12-01

    K2O contents provide a highly effective discriminant between volcanic rocks erupted in the Cascades and Basin-and Range-provinces, with Cascades volcanics having lower K2O contents at a given SiO2. To differentiate these suites, we use a K-index, where K-index = K2Oobserved - 0.12[SiO2] + 5.1 (oxides in wt. %). In the Sierra Nevada, regional K2O contents are not controlled by wall-rock assimilation. In addition, none are candidates for K-metasomatism, and none are likely to be derived by partial melting of a K-metasomatized source. As to the latter issue, even volcanic rocks with the highest K2O in the Sierra Nevada have K2O/Na2O <5, and most such ratios are <3. In contrast, K-metasomatized rocks have K2O/Na2O >5, and as high as 30-40 (Brooks and Snee (1996). Also, Sierra-wide K2O variations are not connected to indices of subduction-related mantle enrichments (such as La/Nb, Ba/Nb or Sr/P2O5), and so K2O is unconnected to regional variations in source composition. K2O contents are instead controlled by the degree of partial melting (F) in the mantle source and fractional crystallization. Putirka and Busby (2007) show that maximum K2O in the Sierra increases with increasing crust thickness, and this relationship also holds across the U.S. the Cordillera (at 39oN latitude). This relationship implies that low F magmas more easily transit thick, low-density upper crust (Putirka and Busby, 2007), which is a consequence of the fact that low F melts are enriched not just in K2O, but also in H2O, which greatly lowers magma density (Ochs and Lange, 1999). This model can explain the contrast in Cascade and Basin-and-Range K2O contents: the modern Cascades are built on the thinner crust of accreted terranes, while typical Basin-and-Range volcanics are erupted on older, and thicker, cratonized crust. Mean crust density, however, cannot be the only explanation of high K2O. In the central Sierra Nevada, the Colorado River Extensional Corridor, and at the Lunar Crater

  7. Plutons for Every Occasion in the Northern U.S. Cordillera

    NASA Astrophysics Data System (ADS)

    Gaschnig, R. M.; Vervoort, J. D.; Tikoff, B.; Lewis, R.

    2011-12-01

    Continental arcs represent major centers of both crustal growth and processing, and changes in the relative importance of the two processes and overall magmatic flux appear to occur in cycles in some localities (e.g., Haschke et al., 2002; Decelles et al., 2009). This appears to be the case with the Idaho batholith region in the northern U.S. Cordillera, which experienced five distinct phases of magmatism, each representing a distinct phase in the tectonic evolution of this portion of the continental margin. The earliest autochthonous magmatism occurred around 105 Ma within the suture between the previously accreted Blue Mountains province and Precambrian North American lithosphere, leading to the formation of the suture zone suite. These rocks probably reflect arc magmatism due to renewed subduction outboard of the Blue Mountains and have a hybrid crust-mantle origin. The suture zone suite experienced large amounts of tectonic shortening immediately after emplacement due to the formation of the transpressional western Idaho shear zone. Simultaneously, arc magmatism migrated eastward producing hybrid tonalites and granodiorites of the border zone and early metaluminous suites, primarily between 93 and 86 Ma. These rocks were compositionally similar to and coeval with the voluminous Late Cretaceous components of the Cordilleran batholiths to the south, suggesting a continuous igneous system from Baja California to Canada at that time. Much of the border zone and early metaluminous suites were obliterated by a massive pulse of predominantly crustal melting, leading to the formation of the Atlanta peraluminous suite between 83 and 67 Ma, representing the largest component of the Idaho batholith presently preserved. This pulse of magmatism was triggered by regional thrusting and crustal thickening. Although it is conceivable that the Atlanta peraluminous suite represents the next stage in the evolution of a single subduction system, this ignores the probable accretion

  8. Food habits of bobcats in eastern Tennessee

    SciTech Connect

    Story, J.D.; Galbraith, W.J.; Kitchings, J.T.

    1982-01-01

    Food habits of bobcats (Lynx rufus) in eastern Tennessee were determined from analyzing 176 cat samples collected on the Oak Ridge National Environmental Research Park. Remains of cottontail rabbits (Sylvilagus floridanus) were the most frequently occurring food item. White-tail deer (Odocoileus virginianus) and pine vole (Microtus pinetorum) remains also were found frequently in samples. Data obtained from this study indicated that food preferences for bobcats in eastern Tennessee are similar to those in other southeastern states where the habitat is similar to the Oak Ridge area and somewhat different from those with significantly different habitat.

  9. Regional polyphase deformation of the Eastern Sierras Pampeanas (Argentina Andean foreland): strengths and weaknesses of paleostress inversion

    NASA Astrophysics Data System (ADS)

    Traforti, Anna; Zampieri, Dario; Massironi, Matteo; Viola, Giulio; Alvarado, Patricia; Di Toro, Giulio

    2016-04-01

    The Eastern Sierras Pampeanas of central Argentina are composed of a series of basement-cored ranges, located in the Andean foreland c. 600 km east of the Andean Cordillera. Although uplift of the ranges is partly attributed to the regional Neogene evolution (Ramos et al. 2002), many questions remain as to the timing and style of deformation. In fact, the Eastern Sierras Pampeanas show compelling evidence of a long lasting brittle history (spanning the Early Carboniferous to Present time), characterised by several deformation events reflecting different tectonic regimes. Each deformation phase resulted in further strain increments accommodated by reactivation of inherited structures and rheological anisotropies (Martino 2003). In the framework of such a polyphase brittle tectonic evolution affecting highly anisotropic basement rocks, the application of paleostress inversion methods, though powerful, suffers from some shortcomings, such as the likely heterogeneous character of fault slip datasets and the possible reactivation of even highly misoriented structures, and thus requires careful analysis. The challenge is to gather sufficient fault-slip data, to develop a proper understanding of the regional evolution. This is done by the identification of internally consistent fault and fracture subsets (associated to distinct stress states on the basis of their geometric and kinematic compatibility) in order to generate a chronologically-constrained evolutionary conceptual model. Based on large fault-slip datasets collected in the Sierras de Cordoba (Eastern Sierras Pampeanas), reduced stress tensors have been generated and interpreted as part of an evolutionary model by considering the obtained results against: (i) existing K-Ar illite ages of fault gouges in the study area (Bense et al. 2013), (ii) the nature and orientation of pre-existing anisotropies and (iii) the present-day stress field due to the convergence of the Nazca and South America plates (main shortening

  10. Two new species of Choerophryne (Anura, Microhylidae) from the northern versant of Papua New Guinea's central cordillera.

    PubMed

    Iannella, Amy; Oliver, Paul; Richards, Stephen

    2015-12-17

    We describe two new species of small microhylid frogs in the genus Choerophryne from the northern slopes of Papua New Guinea's central cordillera. Choerophryne epirrhina sp. nov. can be distinguished from congeners by the combination of moderately small size (SUL 14.9-15.0 mm), distinctly elongated snout (OHG/SUL 0.09-0.10), first finger without expanded disk, and advertisement call consisting of 3-4 distinctly pulsed notes repeated in long sequences. Choerophryne grylloides sp. nov. can be distinguished from congeners by the combination of very small size (SUL 12.5 mm), moderately long snout (OHG/SUL 0.08), long legs (TL/SUL 0.42), first finger without expanded disk and advertisement call consisting of 4-5 distinctly pulsed notes, the last of which has many more pulses than preceding notes (9-10 vs. 3-4).

  11. Deformation and melt transport in a highly depleted peridotite massif from the Canadian Cordillera: Implications to seismic anisotropy above subduction zones

    NASA Astrophysics Data System (ADS)

    Tommasi, Andréa; Vauchez, Alain; Godard, Marguerite; Belley, France

    2006-12-01

    Seismic anisotropy in subduction zones results from a combination of various processes. Although it depends primarily on the orientation of olivine in response to flow, the presence of water and melt in the wedge may modify the deformation of olivine. The melt distribution also influences anisotropy. Direct observations of the deformation and melt-rock interactions in a strongly depleted spinel-harzburgite massif from the Cache Creek terrane in the Canadian Cordillera allow evaluating the relative contribution of each process. Structural mapping shows that this massif has recorded high-temperature, low-stress deformation, high degrees of partial melting, and synkinematic melt-rock interaction at shallow depths (< 70 km) in the mantle, probably above an oblique subduction. Deformation, marked by shallow-dipping lineations and steep foliations, controlled melt distribution: reactive dunites and pyroxenite dykes are dominantly parallel to the foliation. Analysis of olivine crystal preferred orientations (CPO) indicates deformation by dislocation creep with dominant [100] glide. Glide planes are however different in harzburgites and dunites, suggesting that higher melt contents may favor glide on (001) relative to (010). Seismic properties, calculated by considering explicitly the large-scale structure of the massif, the olivine and pyroxene CPO, and possible melt distributions, show that the strain-induced olivine CPO results in up to 5% P- and S-wave anisotropy with fast seismic directions parallel to the lineation. Synkinematic melt transport by diffuse porous flow leading to melt pockets or dykes aligned in the foliation may significantly enhance this anisotropy, in particular for S-waves. In contrast, focused melt flow is not recorded by seismic anisotropy, unless associated with very high instantaneous melt fractions. Orientation of pyroxenite dykes suggests that the present orientation of the structures is representative of the pre-obduction situation, implying

  12. Eastern and Western Approaches to Medicine

    PubMed Central

    Tsuei, Julia J.

    1978-01-01

    An objective comparison of Eastern and Western approaches to medicine is necessary to further evaluate the validity of Oriental medical techniques such as acupuncture. The development of medicine in Western nations follows the way of hypothetical deduction and the Eastern approach uses the inductive method. The Western approach clearly divides the health from the disease, yet the Eastern approach considers health as a balanced state versus disease as an unbalanced state. The Western approach tends to change the environment and the Eastern way is to prefer to adapt to the environment. There are numerous difficulties in comparing these two approaches. The same terminology may apply to entirely different facts, the teaching and learning methods are quite different, and the evaluation of the treatment is almost not comparable. In order to help understand the Eastern approach better, an understanding is needed of the basic Chinese concepts: the concept of a small universe living in a large universe; the duality concept of yin and yang; the concept of anatomy; the concept of physiology in Chinese medicine—the state of equilibrium expressed by the five elements; the concept of pathophysiology expressed by the external and internal insults; the concept of maintaining and promoting health expressed by the circulation of chi and hsieh; the therapeutic concept in Chinese medicine—the normalization or reestablishment of balance of the body function; the concept of preventive medicine. PMID:664653

  13. Review Article: Lake and breach hazard assessment for moraine-dammed lakes: an example from the Cordillera Blanca (Peru)

    NASA Astrophysics Data System (ADS)

    Emmer, A.; Vilímek, V.

    2013-06-01

    Glacial lake outburst floods (GLOFs) and related debris flows represent a significant threat in high mountainous areas across the globe. It is necessary to quantify this threat so as to mitigate their catastrophic effects. Complete GLOF hazard assessment incorporates two phases: the probability of water release from a given glacial lake is estimated through lake and breach hazard assessment while the endangered areas are identified during downstream hazard assessment. This paper outlines a number of methods of lake and breach hazard assessment, which can be grouped into three categories: qualitative, of which we outline eight; semi-quantitative, of which we outline two; and quantitative, of which we outline three. It is considered that five groups of critical parameters are essential for an accurate regionally focused hazard assessment method for moraine-dammed lakes in the Cordillera Blanca. These comprise the possibility of dynamic slope movements into the lake, the possibility of a flood wave from a lake situated upstream, the possibility of dam rupture following a large earthquake, the size of the dam freeboard (or ratio of dam freeboard), and a distinction between natural dams and those with remedial work. It is shown that none of the summarised methods uses all these criteria with, at most, three of the five considered by the outlined methods. A number of these methods were used on six selected moraine-dammed lakes in the Cordillera Blanca: lakes Quitacocha, Checquiacocha, Palcacocha, Llaca, Rajucolta, and Tararhua. The results have been compared and show that each method has certain advantages and disadvantages when used in this region. These methods demonstrate that the most hazardous lake is Lake Palcacocha.

  14. Continental underthrusting and obduction during the Cretaceous closure of the Rocas Verdes rift basin, Cordillera Darwin, Patagonian Andes

    NASA Astrophysics Data System (ADS)

    Klepeis, Keith; Betka, Paul; Clarke, Geoffrey; Fanning, Mark; Hervé, Francisco; Rojas, Lisandro; Mpodozis, Constantino; Thomson, Stuart

    2010-06-01

    The Patagonian Andes record a period of Cretaceous-Neogene orogenesis that began with the compressional inversion of a Late Jurassic rift called the Rocas Verdes basin. Detrital zircon ages from sediment that filled the southern part of the basin provide a maximum depositional age of ˜148 Ma, suggesting that the basin opened approximately simultaneously along its length during the Late Jurassic. Structural data and U-Pb isotopic ages on zircon from granite plutons near the Beagle Channel (55°S) show that basin inversion involved two stages of shortening separated by tens of millions of years. An initial stage created a small (˜60 km wide) thrust wedge that placed the basaltic floor of the Rocas Verdes basin on top of adjacent continental crust prior to ˜86 Ma. Structures and metamorphic mineral assemblages preserved in an exhumed middle to lower crustal shear zone in Cordillera Darwin suggest that this obduction was accompanied by south directed subduction of the basaltic crust and underthrusting of continental crust to depths of ˜35 km beneath a coeval volcanic arc. A subsequent stage of out-of-sequence thrusting, culminating in the Paleogene, shortened basement and Upper Jurassic igneous rock in the internal part of the belt by at least ˜50 km, forming a bivergent thrust wedge. This latter period coincided with the exhumation of rocks in Cordillera Darwin and expansion of the fold-thrust belt into the Magallanes foreland basin. This orogen provides an important example of how orogenesis initiated and led to continental underthrusting and obduction of basaltic crust during closure of a quasi-oceanic rift basin.

  15. Eastern Frequency Response Study

    SciTech Connect

    Miller, N.W.; Shao, M.; Pajic, S.; D'Aquila, R.

    2013-05-01

    This study was specifically designed to investigate the frequency response of the Eastern Interconnection that results from large loss-of-generation events of the type targeted by the North American Electric Reliability Corp. Standard BAL-003 Frequency Response and Frequency Bias Setting (NERC 2012a), under possible future system conditions with high levels of wind generation.

  16. 3D geometry of growth strata in a fault-propagation fold: insights into space-time evolution of the Crevillente Fault (Abanilla-Alicante sector), Betic Cordillera, Spain

    NASA Astrophysics Data System (ADS)

    Martin-Rojas, I.; Alfaro, P.; Estévez, A.

    2015-07-01

    This work presents a 3D geometric model of growth strata cropping out in a fault-propagation fold associated with the Crevillente Fault (Abanilla-Alicante sector) from the Bajo Segura Basin (eastern Betic Cordillera, southern Spain). The analysis of this 3D model enables us to unravel the along-strike and along-section variations of the growth strata, providing constraints to assess the fold development, and hence, the fault kinematic evolution in space and time. We postulate that the observed along-strike dip variations are related to lateral variation in fault displacement. Along-section variations of the progressive unconformity opening angles indicate greater fault slip in the upper Tortonian-Messinian time span; from the Messinian on, quantitative analysis of the unconformity indicate a constant or lower tectonic activity of the Crevillente Fault (Abanilla-Alicante sector); the minor abundance of striated pebbles in the Pliocene-Quaternary units could be interpreted as a decrease in the stress magnitude and consequently in the tectonic activity of the fault. At a regional scale, comparison of the growth successions cropping out in the northern and southern limits of the Bajo Segura Basin points to a southward migration of deformation in the basin. This means that the Bajo Segura Fault became active after the Crevillente Fault (Abanilla-Alicante sector), for which activity on the latter was probably decreasing according to our data. Consequently, we propose that the seismic hazard at the northern limit of the Bajo Segura Basin should be lower than at the southern limit.

  17. ANTIGENIC VARIANTS OF EASTERN EQUINE ENCEPHALITIS VIRUS

    PubMed Central

    Casals, Jordi

    1964-01-01

    A study by hemagglutination-inhibition test showed that 19 strains of eastern equine encephalitis virus grouped themselves in two main types, which have been designated North American and South American. The former consists of ten strains from the eastern half of the United States, from Massachusetts to Florida; Jamaica, the Dominican Republic, and, subject to confirmation, Thailand. The South American type comprises nine strains from Panama, Trinidad, British Guiana, Brazil, and Argentina. The strains were isolated from different natural hosts over a period of 30 years. PMID:14151098

  18. The circulation of the eastern tropical Pacific: A review

    NASA Astrophysics Data System (ADS)

    Kessler, William S.

    2006-05-01

    During the 1950s and 1960s, an extensive field study and interpretive effort was made by researchers, primarily at the Scripps Institution of Oceanography, to sample and understand the physical oceanography of the eastern tropical Pacific. That work was inspired by the valuable fisheries of the region, the recent discovery of the equatorial undercurrent, and the growing realization of the importance of the El Niño phenomenon. Here we review what was learned in that effort, and integrate those findings with work published since then as well as additional diagnoses based on modern data sets. Unlike the central Pacific, where the winds are nearly zonal and the ocean properties and circulation are nearly independent of longitude, the eastern tropical Pacific is distinguished by wind forcing that is strongly influenced by the topography of the American continent. Its circulation is characterized by short zonal scales, permanent eddies and significant off-equatorial upwelling. Notably, the Costa Rica Dome and a thermocline bowl to its northwest are due to winds blowing through gaps in the Central American cordillera, which imprint their signatures on the ocean through linear Sverdrup dynamics. Strong annual modulation of the gap winds and the meridional oscillation of the Intertropical Convergence Zone generates a Rossby wave, superimposed on the direct forcing, that results in a southwestward-propagating annual thermocline signal accounting for major features of observed thermocline depth variations, including that of the Costa Rica Dome, the Tehuantepec bowl, and the ridge-trough system of the North Equatorial Countercurrent (NECC). Interannual variability of sea surface temperature (SST) and altimetric sea surface height signals suggests that the strengthening of the NECC observed in the central Pacific during El Niño events continues all the way to the coast, warming SST (by zonal advection) in a wider meridional band than the equatorially trapped thermocline

  19. Curved thrusts from associated basin depocenters. Basement Paleozoique the morphologyc control. The Rides Prerifaines in the Volubilis Basin (Rif Cordillera, Morocco)

    NASA Astrophysics Data System (ADS)

    Roldán, Francisco Javier; Galindo, Jesus; Ruano, Patricia; Chalouan, Ahmed; Pedrera, Antonio; Ahmamoud, Mfedal; Ruiz, Ana; Sanz, Carlos; Benmakhlouf, Mohammed; Lopez, Angel Carlos; Gonzalez, Lourdes

    2014-05-01

    The Volubilis Basin is located between two structural arcs formed by the Prerif Ridges that developed during and after sedimentation (Roldán et al., 2013). The arcs correspond with WSW-verging anticline culminations, limited by NE-SW strike-slip lateral ramps (Chalouan et al., 2006). Sedimentary infill took place during two stages of ridge formation and propagation. The first stage occurred in the Middle Miocene-Early Tortonian? and was determined by the deposition of the Nappe Prérifaine in the northern part of the basin, and continental and marine sediments over the Prerif Ridges. The second one, Late Miocene in age (Tortonian-Messinian), corresponds to the sedimentation of calcarenites and bioclastic limestones at the basin edges, with a lateral transition to white and blue marls towards the center of the basin (Faugères 1978). There is clear evidence of synsedimentary deformation, suggesting the interaction of sedimentation and tectonics. Geophysical data allow us to characterize the stratigraphic architecture of the Volubilis Basin and the geometry of the top of the Paleozoic basement. An approximately N-S Tortonian-Messinian asymmetric depocenter is located close to the front of the eastern arc. This research illustrates the nucleation, progressive thrust bending and segmentation, and the propagation of folds interacting with sedimentation. Thrust nucleation agrees with Paleozoic basement highs under the detachment surface (Roldán et al., 2013). The progressive development of these tectonic structures conditioned the formation, segmentation and final continentalization of the Volubilis Basin, which can be considered as a piggy-back basin (Roldán et al., 2009). References: Chalouan, A., Galindo-Zaldívar, J., Akil, M., Marín, C., Chabli, A., Ruano, P., Bargach, K., Sanz de Galdeano, C., Benmakhlouf, M., Ahmamou, M. and Gourari, I. (2006). Tectonic wedge escape in the southwestern front of the Rif Cordillera (Morocco) . In: Tectonics of the Western

  20. Chemical evaluation and sensory quality of sauerkrauts obtained by natural and induced fermentations at different NaCl levels from Brassica oleracea Var. capitata Cv. Bronco grown in eastern Spain. Effect of storage.

    PubMed

    Peñas, Elena; Frias, Juana; Sidro, Beatriz; Vidal-Valverde, Concepción

    2010-03-24

    The aim of the present work was to optimize fermentation conditions of white cabbage ( Brassica oleracea L. var. capitata cv. Bronco) grown in winter in eastern Spain. The influence of two salt concentrations (0.5 and 1.5% NaCl) in combination with spontaneous or induced cabbage fermentation on the content of ascorbigen (ABG) and vitamin C as well as on the sensory quality of sauerkraut was investigated. The effect of storage at 4 degrees C for 1-3 months was also studied. ABG content increased from 14 micromol/100 g of dm in raw cabbage to 63-137 micromol/100 g of dm during fermentation, whereas vitamin C decreased from 354 to 236-277 mg/100 g of dm, and the variations depended on the fermentation conditions. Sauerkrauts obtained by Leuconostoc mesenteroides at 0.5% NaCl showed the highest ABG content and a large amount of vitamin C. Refrigeration for 1-3 months led to a reduction of ABG and vitamin C levels, but L. mesenteroides sauerkrauts presented considerable amounts of both compounds at the end of the storage period (74-82 micromol/100 g of dm and 33-44 mg/100 g of dm, respectively), higher than those found with Lactobacillus plantarum and the mixed starter culture before storage. Experimental sauerkrauts presented better organoleptic properties than the commercial products, and no differences in overall acceptability were found among natural fermentations and those performed with starter cultures. These results suggest than low-salted sauerkraut produced with L. mesenteroides provided highly beneficial antioxidant and anticarcinogenic compounds and low sodium content, which is in accordance with the general trend in industrialized countries of reducing the salt level of foods to prevent cardiovascular diseases.

  1. A cosmogenic 10Be chronology for the local last glacial maximum and termination in the Cordillera Oriental, southern Peruvian Andes: Implications for the tropical role in global climate

    NASA Astrophysics Data System (ADS)

    Bromley, Gordon R. M.; Schaefer, Joerg M.; Hall, Brenda L.; Rademaker, Kurt M.; Putnam, Aaron E.; Todd, Claire E.; Hegland, Matthew; Winckler, Gisela; Jackson, Margaret S.; Strand, Peter D.

    2016-09-01

    Resolving patterns of tropical climate variability during and since the last glacial maximum (LGM) is fundamental to assessing the role of the tropics in global change, both on ice-age and sub-millennial timescales. Here, we present a10Be moraine chronology from the Cordillera Carabaya (14.3°S), a sub-range of the Cordillera Oriental in southern Peru, covering the LGM and the first half of the last glacial termination. Additionally, we recalculate existing 10Be ages using a new tropical high-altitude production rate in order to put our record into broader spatial context. Our results indicate that glaciers deposited a series of moraines during marine isotope stage 2, broadly synchronous with global glacier maxima, but that maximum glacier extent may have occurred prior to stage 2. Thereafter, atmospheric warming drove widespread deglaciation of the Cordillera Carabaya. A subsequent glacier resurgence culminated at ∼16,100 yrs, followed by a second period of glacier recession. Together, the observed deglaciation corresponds to Heinrich Stadial 1 (HS1: ∼18,000-14,600 yrs), during which pluvial lakes on the adjacent Peruvian-Bolivian altiplano rose to their highest levels of the late Pleistocene as a consequence of southward displacement of the inter-tropical convergence zone and intensification of the South American summer monsoon. Deglaciation in the Cordillera Carabaya also coincided with the retreat of higher-latitude mountain glaciers in the Southern Hemisphere. Our findings suggest that HS1 was characterised by atmospheric warming and indicate that deglaciation of the southern Peruvian Andes was driven by rising temperatures, despite increased precipitation. Recalculated 10Be data from other tropical Andean sites support this model. Finally, we suggest that the broadly uniform response during the LGM and termination of the glaciers examined here involved equatorial Pacific sea-surface temperature anomalies and propose a framework for testing the viability

  2. Inflammatory Bowel Disease in Children of Middle Eastern Descent

    PubMed Central

    Naidoo, Christina Mai Ying; Leach, Steven T.; Day, Andrew S.; Lemberg, Daniel A.

    2014-01-01

    Increasing rates of inflammatory bowel disease (IBD) are now seen in populations where it was once uncommon. The pattern of IBD in children of Middle Eastern descent in Australia has never been reported. This study aimed to investigate the burden of IBD in children of Middle Eastern descent at the Sydney Children's Hospital, Randwick (SCHR). The SCHR IBD database was used to identify patients of self-reported Middle Eastern ethnicity diagnosed between 1987 and 2011. Demographic, diagnosis, and management data was collected for all Middle Eastern children and an age and gender matched non-Middle Eastern IBD control group. Twenty-four patients of Middle Eastern descent were identified. Middle Eastern Crohn's disease patients had higher disease activity at diagnosis, higher use of thiopurines, and less restricted colonic disease than controls. Although there were limitations with this dataset, we estimated a higher prevalence of IBD in Middle Eastern children and they had a different disease phenotype and behavior compared to the control group, with less disease restricted to the colon and likely a more active disease course. PMID:24987422

  3. Volcanism in Eastern Africa

    NASA Technical Reports Server (NTRS)

    Cauthen, Clay; Coombs, Cassandra R.

    1996-01-01

    In 1891, the Virunga Mountains of Eastern Zaire were first acknowledged as volcanoes, and since then, the Virunga Mountain chain has demonstrated its potentially violent volcanic nature. The Virunga Mountains lie across the Eastern African Rift in an E-W direction located north of Lake Kivu. Mt. Nyamuragira and Mt. Nyiragongo present the most hazard of the eight mountains making up Virunga volcanic field, with the most recent activity during the 1970-90's. In 1977, after almost eighty years of moderate activity and periods of quiescence, Mt. Nyamuragira became highly active with lava flows that extruded from fissures on flanks circumscribing the volcano. The flows destroyed vast areas of vegetation and Zairian National Park areas, but no casualties were reported. Mt. Nyiragongo exhibited the same type volcanic activity, in association with regional tectonics that effected Mt. Nyamuragira, with variations of lava lake levels, lava fountains, and lava flows that resided in Lake Kivu. Mt. Nyiragongo, recently named a Decade volcano, presents both a direct and an indirect hazard to the inhabitants and properties located near the volcano. The Virunga volcanoes pose four major threats: volcanic eruptions, lava flows, toxic gas emission (CH4 and CO2), and earthquakes. Thus, the volcanoes of the Eastern African volcanic field emanate harm to the surrounding area by the forecast of volcanic eruptions. During the JSC Summer Fellowship program, we will acquire and collate remote sensing, photographic (Space Shuttle images), topographic and field data. In addition, maps of the extent and morphology(ies) of the features will be constructed using digital image information. The database generated will serve to create a Geographic Information System for easy access of information of the Eastem African volcanic field. The analysis of volcanism in Eastern Africa will permit a comparison for those areas from which we have field data. Results from this summer's work will permit

  4. Eastern European risk management

    SciTech Connect

    Honey, J.A. )

    1992-01-01

    Here the authors assess Eastern European risk management practices through the evaluation of the nuclear power plants in the region. This evaluation is limited to the Soviet-designed and -built VVER-440 pressurized water reactors (PWRs) that are currently operating in Bulgaria, Czechoslovakia, Hungary, Russia, and the Ukraine and until recently operated at Greifswald in the former East Germany. This evaluation is based on the basic design of the plants, a safety evaluation of the Greifswald facility by representatives from the Federal Republic of Germany and personal visits by the author to Greifswald and Loviisa.

  5. Collisional orogenesis in the northern Canadian Cordillera: Implications for Cordilleran crustal structure, ophiolite emplacement, continental growth, and the terrane hypothesis

    NASA Astrophysics Data System (ADS)

    English, Joseph M.; Johnston, Stephen T.

    2005-04-01

    During Upper Triassic to Lower Jurassic time, arc magmatic rocks of the Stikine terrane, arc-marginal sediments of the Whitehorse Trough, igneous and mantle rocks of the Cache Creek 'ophiolite' and Kutcho assemblage, and oceanic sedimentary and volcanic rocks of the Cache Creek terrane represented a magmatic arc, forearc basin, forearc basement, and subduction complex, respectively. The Cache Creek subduction complex was thrust to the southwest over the Whitehorse Trough forearc basin and the Stikine terrane in the Middle Jurassic during collision with an inboard continental domain. Interpretation of the various lithotectonic assemblages of the northern Intermontane belt in terms of a new plate tectonic model has a number of important implications for the Canadian Cordillera: (a) the model allows comparisons to be drawn with available seismic reflection interpretations of Cordilleran crustal structure; (b) 'ophiolite' emplacement was achieved by ramping of forearc oceanic lithosphere onto thick crustal parts of a subducting plate during collisional orogenesis; (c) island-arc collision and accretion were the principal mechanisms for continental growth with relatively minor contributions from 'sliced-off' oceanic seamounts and/or plateaux; and (d) some terrane-bounding faults such as the Nahlin Fault do not represent major lithospheric-scale boundaries and their importance in tectonic reconstructions has been overemphasised.

  6. Late Quaternary Glacial Chronology in the Cordillera de Talamanca, Costa Rica, Investigated Using Cosmogenic Cl-36 Surface Exposure Dating

    NASA Astrophysics Data System (ADS)

    Li, Y.; Potter, R.; Horn, S.; Orvis, K. H.

    2015-12-01

    The role of the tropics in past and future climate change has garnered significant attention in recent decades, but debate still exists over climate linkages between the tropics and the middle and high latitudes. Glaciers in tropical mountains are highly sensitive indicators of climate, and glacial landforms left behind by past glacier fluctuations provide key evidence of paleoclimate trends and their forcing mechanisms. We investigated late Quaternary glacial chronology from two glaciated valleys on the Chirripó massif in the Cordillera de Talamanca, Costa Rica. Previous studies in this highland have constrained the most recent deglaciation to 12.4-9.7 ka cal BP based on radiocarbon dates on basal sediments of glacial lakes within the cirque at the head of the Morrenas Valley. However, no studies have been conducted to constrain the ages of the moraines located down valley. We dated the formation ages of these moraines in the Morrenas and Talari valleys using cosmogenic Cl-36 surface exposure dating. Our results indicate a major glacial event ~21-18 ka, broadly synchronous with the global Last Glacial Maximum (LGM). Glaciers during this period advanced 3.2-3.4 km down valley on both sides of the Chirripó massif. Our ages also suggest periods of glacial retreat or standstills ~18-10 ka before complete deglaciation of this highland ~10 ka. These results provide insight into the timing and extent of glacial events in this tropical highland that is of critical importance for reconstructing regional and global climate patterns.

  7. Stratigraphic and isotopic link between the northern Stikine terrane and an ancient continental margin assemblage, Canadian Cordillera

    SciTech Connect

    Jackson, J.L.; Gehrels, G.E.; Patchett, P.J. ); Mihalynuk, M.G. )

    1991-12-01

    Geologic and isotopic data strongly imply a Late Triassic depositional link between a juvenile volcanic arc (northern Stikine terrane) and an outboard ancient continental margin assemblage (Nisling terrane) in the Canadian Cordillera. Two sandstone samples and a schist clast from a conglomerate layer at the base of the Upper Triassic Stuhini Group (northern Stikine terrane) have Nd-depleted mantle model ages of 1400-1430 and 1600 Ma, respectively; other Stuhini Group rocks have model ages of 390,660 and 690 Ma. Three samples of Nisling terrane schist and gneiss yield Nd model ages of 910, 1770, and 2450 Ma and highly radiogenic {sup 87}Sr/{sup 86}Sr ratios. These isotopic data corroborate stratigraphic evidence that detritus at the base of northern Stikine was shed from the Nisling terrane and strengthen interpretations that these terranes became linked by Late Triassic time. Thus, Upper Triassic strata of the northern Stikine terrane may have accumulated on top of or adjacent to an exotic continental fragment, a rifted fragment of the North American margin, or the in situ North American margin.

  8. Eastern Europe scenario

    SciTech Connect

    Hafele, W.

    1996-12-31

    The Russian situation is key to Eastern Europe if present trends continue. Its strategy for the establishment of the nuclear fuel cycle was conceived decades ago when the former USSR still existed. It was based on the fuel recycle with attention given to the requirements of the military. The former Warsaw Pact Countries (WPC) were not meant to have independent fuel cycles, and their irradiated fuel elements were scheduled to go back to Russian territory. In 1976 a fuel cycle center was built at Mayak/Chelyabinsk, centered on the RT-1 plant with a nominal capacity of 400 tonnes/yr plant for the reprocessing of spent fuel from VVER-440 reactors, fast reactors (BN-350 and BN-600) icebreaker and submarine transport units, research reactors, and other power units. The plan provided for the reprocessing of spent fuel from the WPC all having VVER-440 reactors. All together, 3000 tonnes of spent fuel have been processed there. Nuclear waste went to vitrification. A new reprocessing facility is under construction in the neighborhood of Krasnoyarsk 26, the RT-2 plant. It is scheduled to operate after 2005, and its design capacity is 1500 tonne/yr. A storage for 6000 tonnes of spent fuel from VVER-1000 reactors is in operation since 1985. A second mixed-oxide plant for VVER-1000 reactors is under consideration. Now, there are no fuel cycle facilities in the newly independent countries. The fuel cycle problems in Eastern Europe and Russia are discussed.

  9. Anemia among school children in eastern Nepal.

    PubMed

    Khatiwada, Saroj; Gelal, Basanta; Gautam, Sharad; Tamang, Man Kumar; Shakya, Prem Raj; Lamsal, Madhab; Baral, Nirmal

    2015-06-01

    Anemia is one of the most common public health problems in developing countries like Nepal. This study was done to find the prevalence of anemia among the children aged 4-13 years in eastern Nepal. A cross-sectional study was conducted in 2012 in four districts (Morang, Udayapur, Bhojpur and Ilam) of eastern Nepal to find the prevalence of anemia among the school children of eastern Nepal. Children aged 4-13 years were selected randomly from different schools of above districts and 618 venous blood samples were collected. Hemoglobin level was estimated by using cyanmethemoglobin method. The mean hemoglobin level was 12.2 ± 1.82 gm/dl. About 37.9% (n = 234) children were found anemic. Anemia prevalence was 42.4% (n = 78), 31.6% (n = 60), 45.3% (n = 48) and 34.8% (n = 48) among school children of Morang, Udayapur, Bhojpur and Ilam district, respectively. The study finds anemia as a significant health problem among the school children of eastern Nepal.

  10. Subsurface structure of the eastern Arkoma basin

    SciTech Connect

    Vanarsdale, R.B. ); Schweig, E.S. III )

    1990-07-01

    Analysis of 425 km of seismic reflection data in the eastern Arkoma basin reveals a structure and history quite different from those previously reported for the Arkoma basin. The eastern Arkoma basin has three structural styles that formed in the following chronological order: deep, steep normal faults; shallow listric normal faults; and thrust faults. The origin of the structural styles and the Paleozoic history of the eastern Arkoma basin may be summarized as follows. Late Proterozoic or Early Cambrian rifting was followed by deposition of Cambrian through Upper Mississippian strata on a passive plate margin. The Mississippian-Pennsylvanian boundary marks a time of major down-to-the-south normal faulting with coincident folding of the footwall blocks and truncation of the faulted and folded terrain by a pre-Morrowan (Mississippian-Pennsylvanian) unconformity. The unconformity slopes southward and steepens locally across the erosionally truncated footwall blocks. During the Pennsylvanian, down-to-the-south listric normal faults cut the Atokan and Morrowan sections and merged with, but did not displace, the steeper segments of the sub-Morrowan unconformity. Surface folds north of the Ross Creek thrust are rollover anticlines overlying these listric normal faults. Major deformation in the eastern Arkoma basin terminated with emplacement of the Ross Creek thrust in the Late Pennsylvanian. 4 figs., 1 tab.

  11. The odyssey of the Cache Creek terrane, Canadian Cordillera: Implications for accretionary orogens, tectonic setting of Panthalassa, the Pacific superwell, and break-up of Pangea

    NASA Astrophysics Data System (ADS)

    Johnston, S. T.; Borel, G. D.

    2007-01-01

    The Cache Creek terrane (CCT) of the Canadian Cordillera consists of accreted seamounts that originated adjacent to the Tethys Ocean in the Permian. We utilize Potential Translation Path plots to place quantitative constraints on the location of the CCT seamounts through time, including limiting the regions within which accretion events occurred. We assume a starting point for the CCT seamounts in the easternmost Tethys at 280 Ma. Using reasonable translation rates (11 cm/a), accretion to the Stikinia-Quesnellia oceanic arc, which occurred at about 230 Ma, took place in western Panthalassa, consistent with the mixed Tethyan fauna of the arc. Subsequent collision with a continental terrane, which occurred at about 180 Ma, took place in central Panthalassa, > 4000 km west of North America yielding a composite ribbon continent. Westward subduction of oceanic lithosphere continuous with the North American continent from 180 to 150 Ma facilitated docking of the ribbon continent with the North American plate. The paleogeographic constraints provided by the CCT indicate that much of the Canadian Cordilleran accretionary orogen is exotic. The accreting crustal block, a composite ribbon continent, grew through repeated collisional events within Panthalassa prior to docking with the North American plate. CCT's odyssey requires the presence of subduction zones within Panthalassa and indicates that the tectonic setting of the Panthalassa superocean differed substantially from the current Pacific basin, with its central spreading ridge and marginal outward dipping subduction zones. A substantial volume of oceanic lithosphere was subducted during CCT's transit of Panthalassa. Blanketing of the core by these cold oceanic slabs enhanced heat transfer out of the core into the lowermost mantle, and may have been responsible for the Cretaceous Normal Superchron, the coeval Pacific-centred mid-Cretaceous superplume event, and its lingering progeny, the Pacific Superswell. Far field

  12. Metamorphic and structural evidence for significant vertical displacement along the Ross Lake fault zone, a major orogen-parallel shear zone in the Cordillera of western North America

    USGS Publications Warehouse

    Baldwin, J.A.; Whitney, D.L.; Hurlow, H.A.

    1997-01-01

    Results of an investigation of the petrology and structure of the Skymo complex and adjacent terranes constrain the amount, timing, and sense of motion on a segment of the > 600-km-long Late Cretaceous - early Tertiary Ross Lake fault zone (RLFZ), a major orogen-parallel shear zone in the Cordillera of western North America. In the study area in the North Cascades, Washington state, the RLFZ accommodated significant pre-middle Eocene vertical displacement, and it juxtaposes the Skymo complex with upper amphibolite facies (650??-690??C and 6-7 kbar) Skagit Gneiss of the North Cascades crystalline core to the SW and andalusite-bearing phyllite of the Little Jack terrane (Intermontane superterrane) to the NE. The two main lithologic units of the Skymo complex, a primitive mafic intrusion and a fault-bounded block of granulite facies metasedimentary rocks, are unique in the North Cascades. Granulite facies conditions were attained during high-temperature (> 800??C), low pressure (??? 4 kbar) contact metamorphism associated with intrusion of the mafic magma. P-T estimates and reaction textures in garnet-orthopyroxene gneiss suggest that contact metamorphism followed earlier, higher pressure regional metamorphism. There is no evidence that the Skagit Gneiss experienced high-T - low-P contact metamorphism. In the Little Jack terrane, however, texturally late cordierite ?? spinel and partial replacement of andalusite by sillimanite near the terrane's fault contact with Skymo gabbro suggest that the Little Jack terrane experienced high-T (??? 600??C) - low-P (??? 4 kbar) contact metamorphism following earlier low-grade regional metamorphism. Similarities in the protoliths of metasedimentary rocks in the Skymo and Little Jack indicate that they may be part of the same terrane. Differences in pressure estimates for the Little Jack versus Skymo for regional metamorphism that preceded contact metamorphism indicate vertical displacement of ??? 10 km (west side up) on the strand

  13. From Source to Sink: Exhumation of the North America Cordillera Revealed by Multi-dating of Detrital Minerals from Upper Jurassic-Upper Cretaceous Sevier Foreland Basin

    NASA Astrophysics Data System (ADS)

    Painter, C. S.; Carrapa, B.; DeCelles, P. G.; Gehrels, G. E.; Thomson, S. N.

    2013-12-01

    We sampled twenty-two Late Jurassic to Late Cretaceous syn-orogenic conglomerate clasts in proximal units in the Sevier fold-thrust belt and their distal sandstone equivalents up to 300 km east of the thrust front, in Utah, Colorado, Wyoming, and South Dakota. To better constrain depositional ages, these samples were analyzed using detrital zircon U-Pb (DZ U-Pb) geochronology. To identify a thermochronometer that measures source exhumation in the North America Cordillera, both zircon (U-Th)/He and apatite fission track (AFT) thermochronology was utilized, on both the conglomerate cobbles and sandstone (detrital) samples. Eleven samples were analyzed with zircon (U-Th)/He; however, discordant ages in the conglomerate cobble samples suggest that this system was not fully reset and never experienced T> ~180 °C in the source stratigraphy during the Sevier orogeny. Eleven other samples are analyzed using apatite fission track thermochronology (AFT); AFT ages are generally similar or older than depositional ages indicating that the detrital ages record source exhumation signals, and that exhumation depth corresponds to T>~120 °C. In order to test whether or not the youngest cooling AFT age population represents a source exhumation signal or a co-magmatic signal we here performed double dating of the detrital AFT samples using apatite U-Pb thermochronology. Maximum depositional ages using DZ U-Pb match existing age controls on basin stratigraphy. Our study shows that AFT is an effective thermochronometer to detect source exhumation for Cretaceous foreland stratigraphy in the western U.S.A. Lag-times (i.e. the difference between the source exhumation age and depositional age) are ~0 to 5 Myr with relatively steady-state to slightly increasing exhumation rates suggesting orogenic growth at this time. The very short lag times also indicate limited to no storage time between source and sink. The AFT lag time of the Early Cretaceous Kelvin Formation is ~5 Myr and represents

  14. Pleistocene mafic volcanoes in the Puna Cordillera Oriental boundary, NW-Argentina

    NASA Astrophysics Data System (ADS)

    Guzmán, S. R.; Petrinovic, I. A.; Brod, J. A.

    2006-11-01

    Los Gemelos and El Saladillo are both monogenetic, strombolian, basaltic-shoshonitic volcanoes that constitute the easternmost recognized examples of mafic Plio-Quaternary volcanism in the southern Central Andes. Two regional faults delimit the borders of the Calchaquí valley, as thrusts with opposite vergence: the eastern Calchaquí fault and the western Toro Muerto fault. While Los Gemelos are set in the hanging wall of Calchaquí back-thrust fault, El Saladillo are set in the footwall of Toro Muerto fault. As Los Gemelos volcanoes have well preserved morphological features, we highlight some relationship between them and their tectonic setting. Kinematic data and one new measurement, that indicate right strike-slip movement in the vicinity of Los Gemelos during the Pleistocene-Holocene. The emplacement of these volcanoes should be related to a transpression zone parallel to the valley, where the alignment of the cones is outlining the trend of conjugated faults. The magmas were derived from a small degree of partial melting of an enriched, garnet-bearing mantle source. The analysed rocks have primitive signature (high Ni, Cr, Co and MgO concentrations; presence of chromite and forsteritic olivine) and evidence for crustal contamination with felsic rocks (quartz ± plagioclase ± K-feldspar xenocrysts with coronas, reaction rims and/or embayments; high 87Sr/ 86Sr ratios, negative ɛNd values). The high Cr and Ni content, high Mg# and low crystal content suggest that no major fractional crystallization occurred, therefore precluding long residence periods. Rapid magma ascent across 60 km of continental crust was guided by magmatic overpressure favoured by important tectonic stresses also avoiding significant residence time at upper crust depth. Thus, we invoke a process of assimilation during turbulent ascent (ATA) to explain the contamination at crustal levels. Los Gemelos volcanoes were formed around 35,000 yr. as inferred from the age of lacustrine sediments

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

    USGS Publications Warehouse

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

    2004-01-01

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

  16. Rhinoplasty in Middle Eastern Patients.

    PubMed

    Sajjadian, Ali

    2016-01-01

    Rhinoplasty in patients of Middle Eastern origin requires complete understanding of nasal morphology and an individualized approach to create a racially congruent and aesthetically pleasing outcome. In this article, common anatomic features and characteristics and detailed steps, surgical techniques, and operative maneuvers that can lead to predictable outcome in rhinoplasty of Middle Eastern patients are discussed.

  17. Metamorphic origin of ore-forming fluids for orogenic gold-bearing quartz vein systems in the North American Cordillera: constraints from a reconnaissance study of δ15N, δD, and δ18O

    USGS Publications Warehouse

    Jia, Y.; Kerrich, R.; Goldfarb, R.

    2003-01-01

    The western North American Cordillera hosts a large number of gold-bearing quartz vein systems from the Mother Lode of southern California, through counterparts in British Columbia and southeastern Alaska, to the Klondike district in central Yukon. These vein systems are structurally controlled by major fault zones, which are often reactivated terrane-bounding sutures that formed in orogens built during accretion and subduction of terranes along the continental margin of North America. Mineralization ages span mid-Jurassic to early Tertiary and encompass much of the evolution ofthe Cordilleran orogen. Nitrogen contents and δ15N values of hydrothermal micas from veins are between 130 and 3,500 ppm and 1.7 to 5.5 per mil, respectively. These values are consistent with fluids derived from metamorphic dehydration reactions within the Phanerozoic accretion-subduction complexes, which have δ15N values of 1 to 6 per mil. The δ18O values of gold-bearing vein quartz from different locations in the Cordillera are between 14.6 and 22.2 per mil but are uniform for individual vein systems. The δD values of hydrothermal micas are between -110 and -60 per mil. Ore fluids have calculated δ18O values of 8 to 16 per mil and δD values of -65 to -10 per mil at an estimated temperature of 300δC; δD values of ore fluids do not show any latitudinal control. These results indicate a deep crustal source for the ore-forming fluids, most likely of metamorphic origin. Low δDH2O values of -120 to -130 per mil for a hydrous muscovite from the Sheba vein in the Klondike district reflect secondary exchange between recrystallizing mica and meteoric waters. Collectively, the N, H, and O isotope compositions of ore-related hydrothermal minerals indicate that the formation of these gold-bearing veins involved dilute, aqueous carbonic, and nitrogen-bearing fluids that were generated from metamorphic dehydration reactions at deep crustal levels. These data are not consistent with either mantle

  18. Quantifying the Anthropogenic Footprint in Eastern China

    NASA Astrophysics Data System (ADS)

    Meng, Chunlei; Dou, Youjun

    2016-04-01

    Urban heat island (UHI) is one of the most focuses in urban climate study. The parameterization of the anthropogenic heat (AH) is crucial important in UHI study, but universal method to parameterize the spatial pattern of the AH is lacking now. This paper uses the NOAA DMSP/OLS nighttime light data to parameterize the spatial pattern of the AH. Two experiments were designed and performed to quantify the influences of the AH to land surface temperature (LST) in eastern China and 24 big cities. The annual mean heating caused by AH is up to 1 K in eastern China. This paper uses the relative LST differences rather than the absolute LST differences between the control run and contrast run of common land model (CoLM) to find the drivers. The heating effect of the anthropogenic footprint has less influence on relatively warm and wet cities.

  19. Quantifying the Anthropogenic Footprint in Eastern China

    PubMed Central

    Meng, Chunlei; Dou, Youjun

    2016-01-01

    Urban heat island (UHI) is one of the most focuses in urban climate study. The parameterization of the anthropogenic heat (AH) is crucial important in UHI study, but universal method to parameterize the spatial pattern of the AH is lacking now. This paper uses the NOAA DMSP/OLS nighttime light data to parameterize the spatial pattern of the AH. Two experiments were designed and performed to quantify the influences of the AH to land surface temperature (LST) in eastern China and 24 big cities. The annual mean heating caused by AH is up to 1 K in eastern China. This paper uses the relative LST differences rather than the absolute LST differences between the control run and contrast run of common land model (CoLM) to find the drivers. The heating effect of the anthropogenic footprint has less influence on relatively warm and wet cities. PMID:27067132

  20. Decadal variability in the Eastern North Atlantic

    NASA Astrophysics Data System (ADS)

    Köllner, Manuela; Klein, Birgit; Kieke, Dagmar; Klein, Holger; Rhein, Monika; Roessler, Achim; Denker, Claudia

    2016-04-01

    The strong warming and salinification of the Eastern North Atlantic starting in the mid 1990s has been attributed to a westward contraction of the subpolar gyre and stronger inflow of waters from the subtropical gyre. Temporal changes in the shape and strength of the two gyres have been related to the major mode of atmospheric variability in the Atlantic sector, the NAO. Hydrographic conditions along the Northwest European shelf are thus the result of different processes such as variations in transports, varying relative contributions of water masses from the two gyres and property trends in the source water masses. We examine the decadal variability in the eastern North Atlantic based on Argo data from 2000-2015 and have constructed time series for four water masses (Subpolar Mode Water (SPMW), Intermediate Water (IW), upper Labrador Sea Water (uLSW) and deep Labrador Sea Water (dLSW)) at selected locations along the Northwest European shelf. Data from the Rockall Trough and the Iceland Basin are chosen to represent advective pathways in the subpolar gyre at two major branches of the North Atlantic Current towards the Nordic Seas and the Arctic Ocean. Temporal variability of subtropical waters transported northward along the eastern boundary is studied at Goban Spur around 48°N. The Argo data are extended in time with long-term hydrographic observations such as the Extended Ellet Line data and other climatological sources in the region. For the study of transport fluctuations time series from the RACE (Regional circulation and Global change) program (2012-2015) and predecessor programs have been used. These programs have monitored the subpolar gyre in the western basin and provide time series of transports and hydrographic anomalies from moored instruments at the western flank of the Mid Atlantic Ridge (MAR). First results show that the temperatures and salinities remained at high levels for the upper waters (SPMW and IW) until 2010 and have been decreasing since

  1. Extensional Detachment faulting in melange rocks. Plurikilometres migration by W the External Zone (Cordillera Bética, Spain)

    NASA Astrophysics Data System (ADS)

    Roldán, Francisco Javier; Azañon, Jose Miguel; Rodríguez, Jose; Mateos, Rosa Maria

    2014-05-01

    The synthesis and correlation of units carried out in the continuous geological map (Roldán et al., 2012), has revealed a fragmentation of the carbonate outcrops belong to the Subbetic Domain (García-Hernández et al., 1980). Subbetic NW verging thrust and fold axial traces have not lateral continuity and Jurassic carbonate outscrops appear as klippes on the olistotromic unit. These ductile structures that can be observed in the internal structure of these jurassic blocks are unrelated to the brittle-ductile deformation bands observed at the basal pelitic levels. Basal detachments are rooted in: a) the Olistostromic unit, a Upper Langhian-Lower Serravallian breccia constituted by gypsum-bearing clay and marls; b) Cretaceous-Tertiary marly sedimentary rocks (Rodríguez-Fernández, et al., 2013) . In both kind of rocks, cataclastic structures allows to infer a top-to-the WSW displacement. Paleostress measurements, made on these detachments levels, are compatible with a extensional regime (Roldán et al., 2012). At the same time, the analysis and interpretation of subsurface data (seismic surveys and borehole testing) shows that the Subbetic Domain (External Subbetic, Molina 1987) are affected by westward low-angle normal faults. A balanced cross-section, based on morphological and cartographic data in the area between Sierra de Cabra and Sierra de Alta Coloma (Valdepeñas de Jaén), shows plurikilometric displacements which has been produced during Late Serravallian-Early Tortonian times. References: García-Hernández, M., López-Garrido, A.C., Rivas, P., Sanz de Galdeano, C., Vera, J.A. (1980): Mesozoic paleogeographic evolution of the zones of the Betic Cordillera. Geol. Mijnb. 59 (2). 155-168. Molina, J.M. (1987). Análisis de facies del Mesozoico en el Subbético. Tesis Doctoral, Univ. Granada. 518 p. Rodríguez-Fernández, J., Roldán, F. J., Azañón, J.M. y García-Cortés, A. (2013). El colapso gravitacional del frente orogénico a lpino en el Dominio Subb

  2. Lake and Bog Sediment Records of Holocene Climate and Glacier Variability in the Cordillera Vilcabamba of Southern Peru

    NASA Astrophysics Data System (ADS)

    Schweinsberg, A.; Licciardi, J. M.; Rodbell, D. T.; Stansell, N.

    2013-12-01

    Records of past fluctuations in climatically sensitive tropical glaciers are among the best indicators of regional paleoclimatic trends and forcings. However, continuous sediment records in this region remain limited, particularly during the Holocene. Here we present the first continuous records of glacier activity in the Cordillera Vilcabamba (13°20'S) of southern Peru from lake and bog sediment cores in stratigraphic contact with 10Be-dated moraines. Completed analyses include sediment lithostratigraphy, magnetic susceptibility, and biogenic silica, in conjunction with AMS radiocarbon dates on charcoal. Carbon measurements, bulk density, and bulk sedimentation rates are used to derive a record of clastic sediment flux that serves as a proxy indicator of former glacier activity. Visually distinct sedimentological variations, magnetic susceptibility peaks, and radiocarbon dates were correlated among adjacent cores to construct one composite record representative of each coring site. Three composite cores are presented: two from the Rio Blanco valley and one from the Yanama valley. Sediment records from these two glaciated valleys suggest a series of environmental changes during the last ~12,000 calendar years BP. Clastic sediment flux trends are broadly consistent with published evidence that the early to middle Holocene was relatively warm and arid in the southern Peruvian Andes. An episode of high clastic flux in the late Holocene may reflect enhanced glacial activity in response to the onset of cooler and wetter conditions. A prominent peak in magnetic susceptibility at 1660 cal yr BP is present in all composite cores and serves as a chronostratigraphic marker. In addition, our new basal radiocarbon ages place limits on the cosmogenic 10Be production rate in the high Andes, suggesting the cosmogenic 10Be production rate is considerably lower than previously published estimates.

  3. Unraveling Tropical Mountain Hydroclimatology by Coupling Autonomous Sensor Observations and Climate Modeling: Llanganuco Valley, Cordillera Blanca, Peru.

    NASA Astrophysics Data System (ADS)

    Hellstrom, R. A.; Fernandez, A.; Mark, B. G.; Covert, J. M.

    2015-12-01

    Northern Peru will face critical water resource issues in the near future as permanent ice retreats. Much of current global and regional climate research neglects the meteorological forcing of lapse rates and valley wind dynamics on critical components of the Peruvian Andes' water-cycle. In 2004 and 2005 we installed an autonomous sensor network (ASN) within the glacierized Llanganuco Valley, Cordillera Blanca (9°S), consisting of discrete, cost-effective, automatic temperature loggers located along the valley axis and anchored by two automatic weather stations. Comparisons of these embedded atmospheric measurements from the ASN and climate modeling (CM) by dynamical downscaling using the Weather Research and Forecasting (WRF) model elucidate distinct diurnal and seasonal characteristics of the mountain valley winds and lapse rates. Wind, temperature, humidity, and cloud simulations by WRF suggest that thermally driven valley winds converging with easterly flow aloft enhance late afternoon and evening cloud development which helps explain detected nocturnal precipitation maxima measured by the ASN. We attribute sustained evapotranspiration (ET), as estimated by the FAO-56 Penman-Monteith model, to an abundance of glacial melt-water during the dry season and strong pre-noon solar heating during the wet season. Furthermore, the extreme diurnal variability of along-valley-axis lapse rates and valley wind detected from ground observations and confirmed by dynamical downscaling demonstrate the importance of realistic scale parameterizations of the boundary layer to improve regional CM projections in mountainous regions. Our findings portray ET as an integral yet poorly represented process in Andean hydroclimatology. We show that coupling ASN and CM can improve understanding of multi-scale atmospheric and associated hydrological processes in mountain valleys.

  4. Investigating potential precipitation changes with impacts on small-scale farming in mountain villages, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Gurgiser, Wolfgang; Hofer, Marlis; Juen, Irmgard; Schauwecker, Simone; Singer, Katrin; Neuburger, Martina; Kaser, Georg

    2015-04-01

    Small subsistence farmers on the slopes above the city of Huaraz in the Peruvian Cordillera Blanca assign recent challenges in agricultural production - beyond other factors - to decreasing precipitation during the early crop cultivation period in August and September. In general, local climate is characterized by low annual variation in air temperature but a strong seasonality in precipitation. While driest conditions prevail in June and July, precipitation increases gradually towards the October to April wet season with strong topographically induced gradients. Because seeding occurs soon after the core dry months, cultivation is highly vulnerable to potential alterations in the transition period from dry to wet conditions. Within this study we try to find "data-based" evidence for changes in precipitation patterns, even though the availability of meteorological information for proving precipitation trends is generally poor for this region. We currently investigate the respective potential of connecting approx. 10 years (2003-2013) of ground measurements (weekly resolution with some gaps) with ERA-interim total precipitation output (0.75 deg. resolution) by (1) selecting those adjacent model grid points that explain measured precipitation variability best and by (2) fitting the data from the selected grid points to the measurements with quantile mapping. Uncertainties arising from the transfer functions are assessed with a cross validation approach. Our preliminary results suggest that (1) ground measurements are fairly explained by ERA interim data (despite the very complex topography), that (2) no significant trends in precipitation at the end of the dry season (August, September) are detectable for the period 1979-2013, but relatively high year-to-year variability occurs and that (3) process based limited area modeling might be required to effectively assess specific requests of user groups related to local precipitation variability.

  5. Geology, K-Ar geochronology and paleomagnetism of parts of the coastal cordillera of central Chile, South America

    SciTech Connect

    Irwin, J.J.

    1986-01-01

    A complex composed of ultrabasic and basaltic lavas, chert-argillite, arkose and conglomerate was assembled in the coast of north central Chile prior to 220 Ma ago. Three major episodes of deformation and metamorphism have been observed in this area. The first episode of deformation and metamorphism (F/sub 1/) produced a compositional layering (S/sub 1/) and amphibolite facies metamorphism within the formations listed above. This episode of deformation and metamorphism occurred coevally with intrusion of a regionally extensive 220-200 Ma fine grained gabbro and granitic complex. The second episode of deformation and metamorphism locally formed tight, recumbent folds in S/sub 1/ and at least one low angle reverse fault. K-Ar and Rb-Sr ages on units in which F/sub 2/ folds are well developed range between 163 and 140 Ma. A third episode of deformation and low grade metamorphism (F/sub 3/) locally formed upright, open to tight folds with sharp hinges and axial planes that strike north and dip steeply east. Igneous intrusions that were affected by F/sub 3/ yield K-Ar ages between 140 Ma and 126 Ma. Undeformed cross cutting mafic dykes have been dated by K-Ar at 121 Ma. Paleomagnetic samples collected from 19 sites in radioisotopically dated (using the K-Ar and /sup 40/Ar-/sup 39/Ar techniques) Jurassic mafic dykes and plutons in the coastal cordillera of Chile yield mean paleomagnetic poles that are consistent with the average pole from coeval sequences within the South American craton. The paleomagnetic directions are consistent over the latitudinal range and variety of lithologies encompassed by this study. Paleomagnetic results presented here indicate that no major rotation or translation of crustal blocks has been taken place in this part of central Chile since middle Jurassic time.

  6. Structural controls on karstic conduits in a collisional orogen (Sierra de las Nieves, Betic Cordillera, S Spain)

    NASA Astrophysics Data System (ADS)

    Pedrera, A.; Luque-Espinar, J. A.; Martos-Rosillo, S.; Pardo-Igúzquiza, E.; Durán-Valsero, J. J.; Martínez-Moreno, F.; Guardiola-Albert, C.

    2015-06-01

    We characterize the fracture pattern, including both meso-scale joints and macro-scale faults, within the central sector of Sierra de las Nieves (Betic Cordillera, S Spain), which contains one of the largest karstification systems in Europe. Structural data were compared with the direction pattern of the karstic conduit network of the largest caves. Carbonate rocks were deformed in a collisional setting and exposed at the surface since the early Miocene. Normal and normal-oblique faults trending NW-SE to WNW-ESE are the most prominent brittle structures, having formed coevally with shorter NE-SW normal to normal-dextral after the main thrusting phase. In addition, two main open joint sets striking NW-SE and NE-SW developed on a broad scale. Orthogonal normal faults and open joints suggest an extensional setting characterized by horizontal minimum (S3) and intermediate (S2) stress axes of similar magnitudes that intermittently shifted their positions during the middle-to-late Miocene. Vertical water flow coming from direct recharge sectors tends to infiltrate across these high-dipping faults, mainly concentrating at fault intersections, thus favoring sub-vertical conduit formation within the vadose zone. Horizontal paleo-phreatic levels are perched linked to the recent uplift undergone by the sector, giving us the opportunity to analyze the incidence of fractures at the phreatic zone. Joint sets determine the hydraulic anisotropy within the former phreatic levels. Because our study illustrates the primary role of diverse tectonic structures during massive multiphase cave development above and below the water table, it could contribute to better constraining of the models of karstic conduit formation.

  7. Time-lapse and UAV Thermal Imaging of Glacial and Periglacial Environments in the Peruvian Andes (Cordillera Blanca, Peru)

    NASA Astrophysics Data System (ADS)

    McKenzie, J. M.; Wigmore, O.; Aubry-Wake, C.; Mark, B. G.; Hellstrom, R. A.; Lautz, L.

    2015-12-01

    In the tropics, the acquisition of high-resolution geospatial data of high-mountain glacial and periglacial systems presents unique challenges due to remote site access and very high elevations. For glaciers and hydrologic systems, a key variable of interest is surface temperature as it constrains glacier melt rates, traces hydrologic processes, and is needed for the calibration of energy budget models. We present results from two studies that acquired high resolution temperature data from the Cuchillacocha Glacier, Peru (9.24°S, 77.21°W). The glacier resides on the western drainage of the Cordillera Blanca with an elevation range of 4700 to 6096 m. In the first study we use high resolution time-lapse infrared imagery (5-10 minute interval over 3 days; 0.6 m2 pixel size) to observe diel changes in the surface energy budget of the glacier and to demonstrate how radiation from bare rock adjacent to the glacier may affect melt rates. In the second study we use a newly developed, inexpensive unmanned aerial vehicle (UAV) for high resolution multispectral mapping of the glacier (2 cm resolution orthomosaic and 5 cm resolution DEM). We present results showing how the time-lapse and the high-resolution UAV imagery can be combined to further strengthen our understanding of the Cuchillacocha Glacier's energy budget and possible insights about turbulent heat fluxes. While the new instruments provide unprecedented data acquisition capabilities, there is an outstanding need for proper data correction. Spatial/thermal control points and post-processing algorithms are needed to produce quantifiable datasets. For example, our post-processed time-lapse imagery has an r2 > 0.9 after emissivity, transmissivity and offset corrections.

  8. Late Pleistocene and Holocene Hydroclimate Variability in the Tropical Andes from Alpine Lake Sediments, Cordillera de Mérida, Venezuela

    NASA Astrophysics Data System (ADS)

    Larsen, D. J.; Abbott, M. B.; Polissar, P. J.

    2014-12-01

    The tropics play a major role in the global hydrologic cycle and changes to tropical rainfall patterns have critical implications for water resources and ecosystem dynamics over large geographic scales. In tropical South America, late Pleistocene and Holocene precipitation variability has been documented in geologic records and associated with numerous external and internal variables, including changes in summer insolation, South American summer monsoon strength, Pacific Ocean sea surface temperatures, continental moisture recycling, and other climate processes. However, there are few records from the northern hemisphere tropical Americas, a key region for understanding interhemispheric linkages and the drivers of tropical hydroclimate variability. Here, we present a ~13 ka record of coupled hydroclimate and environmental changes from Laguna Brava, a small (~0.07 km2), hydrologically closed lake basin situated at 2400 m asl in the Cordillera de Mérida, Venezuela. Sediment cores collected from varying water depths and proximity to shore are placed in a chronologic framework using radiocarbon ages from terrestrial macrofossils, and analyzed for a suite of physical, bulk geochemical, and stable isotopic parameters. Compound specific hydrogen isotope (D/H) measurements of terrestrial plant waxes (long-chain n-alkanes) show a sharp increase in the late Pleistocene, followed by a long-term trend toward more negative values that suggest a ~20‰ decrease in the D/H ratios of South American tropical precipitation during the Holocene. This pattern is consistent in sign and magnitude to other South American precipitation reconstructions from both hemispheres, indicating interhemispheric similarities in tropical hydroclimate variability. Superimposed on this continent-scale trend are changes in moisture balance and environmental conditions in the Venezuelan Andes. We reconstruct these parameters at Laguna Brava at multidecadal and centennial resolution and evaluate this

  9. Tectonic accretion and the origin of the two major metamorphic and plutonic welts in the Canadian Cordillera

    NASA Astrophysics Data System (ADS)

    Monger, J. W. H.; Price, R. A.; Tempelman-Kluit, D. J.

    1982-02-01

    The Omineca Crystalline Belt and Coast Plutonic Complex are the two major regional tectonic welts in the Canadian Cordillera in which were concentrated intense deformation, regional metamorphism, granitic magmatism, uplift, and erosion. The welts, which formerly were thought to result from subduction of Pacific Ocean lithosphere beneath the western edge of North America, can now be viewed partly as the result of tectonic overlap and/or compressional thickening of crustal rocks during collisions between North America and two large, composite, allochthonous terranes that were accreted to its ancient western margin. The inner composite terrane, Terrane I, includes four smaller terranes that apparently were together by the end of Triassic time. The outer composite terrane, Terrane II, comprises two terranes, amalgamated by Late Jurassic time. The Omineca Crystalline Belt formed mainly from mid-Jurassic time onward, during and following the collision of Terrane I with North America. This belt straddles the zone of overlap of autochthonous and allochthonous terranes, and its characteristic metamorphism and structure are superimposed on both. The Coast Plutonic Complex formed mainly in Cretaceous to early Tertiary time during and following the attachment of Terrane II to the new, Jurassic, continental margin. It lies along the boundary of Terrane I and Terrane II and involves elements of both terranes. The collisions took place within the overall setting of the North American plate moving relatively westward into various Pacific plates from Jurassic time onward and in conjunction with subduction of Pacific Ocean lithosphere. *Present address: Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A OE8, Canada

  10. Alternative models for Late Jurassic and Early Cretaceous paleogeography of the western Cordillera, California to SE Alaska

    SciTech Connect

    Cowan, D.S. . Geological Sciences)

    1993-04-01

    The Franciscan-Great Valley-Sierran triad is indisputable evidence for late Mesozoic, west-facing subduction along the California sector of the N. American margin. In the northwestern sector (N of 48[degree]N), however, neither the configuration of plate boundaries, nor the paleogeographic disposition of the Insular and Intermontane superterranes, is confidently established. Models divide into two groups. One set, based entirely on geologic evidence such as the age and nature of deformational events, or putative stratigraphic links among terranes, places the two superterranes exclusively to the north of the Franciscan-Sierran system from 150 to 90 Ma. These hypotheses, which ignore or reject paleomagnetic data from mid-Cretaceous rocks, yield a paleogeography not too different from today's, but they are incompatible with the Franciscan and Great Valley rocks caught between the superterranes in the mid-Cretaceous San Juan-Cascade thrust system. An alternative model fully respecting paleomagnetic data from mid-Cretaceous rocks with paleohorizontal control restores most of the Intermontane superterrane [approximately]1,200 km south of its expected (i.e. present) latitudinal position with respect to North America, and the Insular superterrane [approximately]2,900 km south, at 95--105 Ma. The mid-Cretaceous thrust system along the eastern margin of the Insular superterrane records the collision of Wrangellia et al. with the southern continuation of the Franciscan subduction zone. The thrust system, a silver of hanging wall, and the Insular superterrane were all subsequently translated > 2,500 km northward by post-80, pre-60 Ma coast-parallel dextral slip, accommodated on the proto-Pasayten and proto-Yalakom faults, and along or near the Coast Range shear zone.

  11. Eastern Han's Cunning Depiction

    NASA Astrophysics Data System (ADS)

    Chiu, B. C.

    1998-09-01

    It is still only speculation, but an earlier visit to a Han dynasty (202 BC - 220 AD) tomb has started the idea, and a recently found study of another Han tomb has convinced me it is worth pursuing. What it is is that the ancient Chinese Sky Animal which represents North was not the turtle or tortoise until about the time of Han. My own visit was to an Eastern (later period) Han tomb which had been moved to a museum near the ancient capital of Luoyang. The ceiling of the inner chamber was rounded, made of brick. Drawings of a tiger and a red bird were clear to the west and south. A rounded object was at the north. Outside the tomb was a sign which said it was 'cun,' which means village. Chinese characters often have homonyms, but 'cun' has few. I have also visited the neolithic village of Banpo, near the Yellow River in the north. It has noticeably large and deep trenches to keep out wild animals, and one separates the residential area from the business area. This village is dated earlier than 4000 BC. The trenches definitely remind me of later depictions of the turtle with a snake wound about it. The recent findings of a tomb at Puyang with shapes of tiger and dragon have dated it to 3000 BC. Nothing was placed at the south side. Something was at the north, but one might argue about that. Finally, I found this article in Chinese Studies in Archaeology (1979), translated by S. Cahill of UC, Berkeley, called "Analysis of the Western Han Murals in the Luouyang Tomb of Bo Qianqiu" by Sun Zuoyun. Although Western Han is earlier than Eastern, the pictures in the tomb were well preserved. There were tiger, dragon, vermilion bird, and other animals, but no tortoise. Instead, there was a sun with a bird inside, and the moon with a frog. Several hundred miles north of the Yellow River, there is the Amur River. The natives there had robes decorated with snakes, lizards, and frogs, and other animals, but no turtle. Later reasons for having the turtle or tortoise is a separate

  12. Lower Jurassic unconformity (J-O) from the Colorado Plateau to the eastern Mojave Desert: evidence of a major tectonic event at the close of the Triassic

    SciTech Connect

    Marzolf, J.E. )

    1991-04-01

    From southern Nevada to the eastern Mojave Desert, the Lower Jurassic basal unconformity (J-0) cuts down section from the Upper Triassic Chinle Formation to deformed Paleozoic carbonate rocks. The Chinle Formation is not present southwest of the central Spring Mountians. Stratigraphic relations suggest correlation of J-0 with unconformities in western Arizona and the Inyo Mountains. Close proximity of J-0 in time and space to (1) first appearance of western-derived volcanic clasts in lower Mesozoic cratonal stratigraphy, (2) early Mesozoic thrust faults, and (3) the J-1 cusp in the apparent polar wander path imply a major change in tetonic setting of the southwestern Cordillera at the Triassic/Jurassic boundary.

  13. Evaluation of metasomatic changes in an interlayered blueschist-greenschist sequence (Coastal Cordillera, Chile) by combining geochemical data with equilibrium assemblage diagrams

    NASA Astrophysics Data System (ADS)

    Halama, Ralf; Konrad-Schmolke, Matthias

    2014-05-01

    In the Coastal Cordillera of Central Chile, a spectacular sequence of interlayered blueschists and greenschists occurs in coastal outcrops near Pichilemu. Three explanations are generally proposed to interpret the interlayering of metamorphic rocks that represent distinct metamorphic facies: 1. Differences in the pressure-temperature (P-T) conditions of equilibration and late-stage tectonic juxtaposition, 2. Chemical differences between the layers inherited from the protolith, and 3. Differences in the degree of metasomatic overprint during metamorphism. Investigations of such interlayered sequences can shed light on the mobility of elements and fluid-rock interaction during metamorphism. To identify the processes responsible for interlayering, geochemical analyses were combined with petrologic investigations involving the calculation of isothermal and isobaric binary phase diagrams using the THERIAK-DOMINO [1] software. Major mineral phases in blueschist and greenschist layers are amphibole, white mica, chlorite, and albite with subordinate amounts of titanite, epidote, hematite and apatite. The mineralogy of blueschist and greenschist layers is similar, albeit the modal proportions differ, causing the distinct colouring. Peak P-T conditions of blueschists reach 370±20 °C at 10±1 kbar [2]. The layering on a cm-to-dm scale and the similar mineralogy suggest that both blueschist and greenschist layers experienced a similar P-T evolution. For adjacent blueschist-greenschist pairs, blueschists have consistently higher Si and Na contents, whereas greenschists are relatively enriched in Al, Mg and total Fe. However, the observed major element geochemical trends are inconsistent with magmatic differentiation. For several blueschist-greenschist pairs, ratios of incompatible trace elements, which are indicative of the protolith composition and considered as relatively immobile during low-T metamorphism (Th/Yb, Nb/Yb), are near identical. These features point to

  14. Eastern Siberia terrain intelligence

    USGS Publications Warehouse

    ,

    1942-01-01

    The following folio of terrain intelligence maps, charts and explanatory tables represent an attempt to bring together available data on natural physical conditions such as will affect military operations in Eastern Siberia. The area covered is the easternmost section of the U.S.S.R.; that is the area east of the Yenisei River. Each map and accompanying table is devoted· to a specialized set of problems; together they cover such subjects as geology, construction materials, mineral fuels, terrain, water supply, rivers and climate. The data is somewhat generalized due to the scale of treatment as well as to the scarcity of basic data. Each of the maps are rated as to reliability according to the reliability scale on the following page. Considerable of the data shown is of an interpretative nature, although precise data from literature was used wherever possible. The maps and tables were compiled  by a special group from the United States Geological Survey in cooperation with the Intelligence Branch of the Office, Chief of Engineers, War Department.

  15. Issues in Health Care of Middle Eastern Patients

    PubMed Central

    Lipson, Juliene G.; Meleis, Afaf I.

    1983-01-01

    Relationships between Middle Eastern patients and Western health care professionals are often troubled by mutual misunderstanding of culturally influenced values and communication styles. Although Middle Easterners vary ethnically, they do share a core of common values and behavior that include the importance of affiliation and family, time and space orientations, interactional style and attitudes toward health and illness. Problems in providing health care involve obtaining adequate information, “demanding behavior” by a patient's family, conflicting beliefs about planning ahead and differing patterns of communicating grave diagnoses or “bad news.” There are guidelines that will provide an understanding of the cultural characteristics of Middle Easterners and, therefore, will improve rather than impede their health care. A personal approach and continuity of care by the same health care professional help to bridge the gap between Middle Eastern cultures and Western medical culture. In addition, periodic use of cultural interpreters helps ameliorate the intensity of some cultural issues. PMID:6364575

  16. Early Paleozoic blueschist from the schist of Skookum Gulch, eastern Klamath Mountains, northern California

    SciTech Connect

    Cotkin, S.J. ); Cotkin, M.L. ); Armstrong, R.L. )

    1992-05-01

    Late Ordovician blueschist from the schist of Skookum Gulch, eastern Klamath Mountains, California, is the oldest known blueschist in California and one of the oldest in North America. Lawsonite-bearing glaucophane schist occurs as lenses intimately interlayered with chlorite schist, quartz-albite schist, and dolomite marble. Detailed investigation of a portion of the Skookum Gulch schist demonstrates that these rock types share a common deformational and metamorphic history. The first deformation occurred during blueschist metamorphism and produced similar-style isoclinal folds and an axial-planar foliation. During subsequent deformations, parallel-style open to tight folds and local kink bands deformed foliation but produced no recognizable recrystallization. A phengite Rb-Sr date of 447 {plus minus} 9 Ma (Late Ordovician) is statistically indistinguishable from previously published K-Ar dates and is interpreted as the time of blueschist-facies metamorphism. Mineral separates from one rock yield a date of 353 {plus minus} 18 Ma, suggesting resetting during a Devonian to Early Mississippian thermal event. The schist of Skookum Gulch is a critical component of the Middle Ordovician to Early Silurian Callahan event, which included volcanism, plutonism, metamorphism, deformation, and sedimentation and occurred in response to collisional tectonics. Paleontological and provenance information indicate that the Callahan event occurred relatively close to the North American continental margin. In this regard, features produced by the Callahan event record the earliest period of Phanerozoic plate convergence recognized within the US Cordillera.

  17. Petrology and geochemistry of the Eastern Loma de Cabrera Batholith, Dominican Republic

    SciTech Connect

    Cribb, J.W.; Lewis, J.F.

    1985-01-01

    The Eastern Loma de Cabrera Batholith, located in the NW Cordillera Central, Dominican Republic, is a heterogeneous intrusive complex composed of a zoned ultramafic-mafic core surrounded by tonalite and diorite. The batholith intrudes metasbasaltic rocks of the Duarte Complex of early Cretaceous age. The ultramafic-mafic core consists of peridotite, olivine-pyroxenite, pyroxenite, and augite-hypersthene gabbro-norite. Pyroxenites and gabbro-norites exhibit large scale interlayering and small scale layering involving a regular variation in the proportions of ortho- and clinopyroxene. Tonalities and diorites are mafic to leucocratic, some being porphyritic. Petrographic types include hornblende, hornblende-pyroxene, hornblende-biotite, and muscovite-biotite types. Aplites are abundant. Intrusive relations suggest that ultramafic-mafic complex is the oldest intrusive phase, and was partially amphibolitized during later intrusion of the felsic rocks. Ultramafic-mafic rocks contain 43-54% SiO/sub 2/ and MgO ranges from 8-45%. Trace and REE in these rocks are relatively depleted. Tonalitic rocks range in SiO/sub 2/ from 53-76%, with K/sub 2/O varying from 0.15-2.9%. In addition, they are LREE enriched. A small Eu anomaly is best explained by fractionation of plagioclase and hornblende. Trends shown by Rb-Sr data suggest that fractional crystallization of hornblende and plagioclase, that is high level fractionation, is the important factor in controlling chemical variation in the tonalites.

  18. Modelling cascading and erosional processes for glacial lake outburst floods in the Quillcay catchment, Huaraz, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Baer, Patrick; Huggel, Christian; Frey, Holger; Chisolm, Rachel; McKinney, Daene; McArdell, Brian; Portocarrero, Cesar; Cochachin, Alejo

    2016-04-01

    Huaraz as the largest city in Cordillera Blanca has faced a major disaster in 1941, when an outburst flood from Lake Palcacocha killed several thousand people and caused widespread destruction. Recent studies on glacial lake outburst flood (GLOF) modelling and early warning systems focussed on Lake Palcacocha which has regrown after the 1941 event, from a volume of half a million m3 in 1974 to a total volume of more than 17 million m3 today. However, little research has been conducted so far concerning the situation of other lakes in the Quillcay catchment, namely Lake Tullparaju (12 mill. m3) and Cuchillacocha (2.5 mill. m3), which both also pose a threat to the city of Huaraz. In this study, we modelled the cascading processes at Lake Tullparaju and Lake Cuchillacocha including rock/ice avalanches, flood wave propagation in the lake and the resulting outburst flood and debris flows. We used the 2D model RAMMS to simulate ice avalanches. Model output was used as input for analytical 2D and 3D calculations of impact waves in the lakes that allowed us to estimate dam overtopping wave height. Since the dimension of the hanging glaciers above all three lakes is comparable, the scenarios in this study have been defined similar to the previous study at Lake Palcacocha. The flow propagation model included sediment entrainment in the steeper parts of the catchment, adding up to 50% to the initial flow volume. The results for total travel time as well as for inundated areas and flow depth and velocity in the city of Huaraz are comparable to the previous studies at Lake Palcacocha. This underlines the importance of considering also these lakes within an integral hazard analysis for the city of Huaraz. A main challenge for modelling GLOFs in the Quillcay catchment using RAMMS is the long runout distance of over 22 km combined with the very low slope gradient of the river. Further studies could improve the process understanding and could focus on more detailed investigations

  19. Unraveling an antique subduction process from metamorphic basement around Medellín city, Central Cordillera of Colombian Andes

    NASA Astrophysics Data System (ADS)

    Bustamante, Andres; Juliani, Caetano

    2011-10-01

    varies between 400 and 555 °C at pressures of 5-6 kbar in the retrograde metamorphic path. The El Retiro rocks evidence strong decompression with narrow variation in temperature, showing pressure values between 8.7 and 2.7 kbar at temperatures of 740-633 °C. These metamorphic fragments of the basement in the Central Cordillera of the Colombian Andes could represent a close relationship with an antique subduction zone.

  20. Origin of gem corundum in calcite marble: The Revelstoke occurrence in the Canadian Cordillera of British Columbia

    NASA Astrophysics Data System (ADS)

    Dzikowski, Tashia J.; Cempírek, Jan; Groat, Lee A.; Dipple, Gregory M.; Giuliani, Gaston

    2014-06-01

    The calcite marble-hosted gem corundum (ruby, sapphire) occurrence near Revelstoke, British Columbia, Canada, occurs in the Monashee Complex of the Omineca Belt of the Canadian Cordillera. Corundum occurs in thin, folded and stretched layers with green muscovite + Ba-bearing K-feldspar + anorthite (An0.85-1) ± phlogopite ± Na-poor scapolite. Other silicate layers within the marble are composed of: (1) diopside + tremolite ± quartz and (2) garnet (Alm0.7-0.5Grs0.2-0.4) + Na-rich scapolite + diopside + tremolite + Na,K-amphiboles. Non-silicate layers in the marble are either magnetite- or graphite-bearing. Predominantly pink (locally red or purple) opaque to transparent corundum crystals have elevated Cr2O3 (≤ 0.21 wt.%) and variable amounts of TiO2; rare blue rims on the corundum crystals contain higher amounts of TiO2 (≤ 0.53 wt.%) and Fe2O3 (≤ 0.07 wt.%). The associated micas have elevated Cr, V, Ti, and Ba contents. Petrography of the silicate layers show that corundum formed from muscovite at the peak of metamorphism (~ 650-700 °C at 8.5-9 kbar). Because the marble is almost pure calcite (dolomite is very rare), the corundum was preserved because it did not react with dolomite to spinel + calcite during decompression. The scapolite-bearing assemblages formed during or after decompression of the rock at ~ 650 °C and 4-6 kbar. Gem-quality corundum crystals formed especially on borders of the mica-feldspar layers in an assemblage with calcite. Whole rock geochemistry data show that the corundum-bearing silicate (mica-feldspar) layers formed by mechanical mixing of carbonate with the host gneiss protolith; the bulk composition of the silicate layers was modified by Si and Fe depletion during prograde metamorphism. High element mobility is supported by the homogenization of δ18O and δ13C values in carbonates and silicates for the marble and silicate layers. The silicate layers and the gneiss contain elevated contents of Cr and V due to the volcanoclastic

  1. Precise Surface Exposure Dating of Early Holocene and Little Ice Age Moraines in the Cordillera Vilcabamba of Southern Peru

    NASA Astrophysics Data System (ADS)

    Licciardi, J. M.; Schaefer, J. M.; Lund, D. C.; Taggart, J. R.

    2008-12-01

    We have established precise ages of two glacial events in the tropical Andean highlands of southern Peru. The field site is located on the flanks of Nevado Salcantay (6271 m asl; 13°20'S latitude), the highest peak in the Cordillera Vilcabamba. A two-fold sequence of nested lateral and end moraines was mapped in a glacial trough emanating from the south face of Salcantay. Well-defined outer and inner moraines were deposited by valley glaciers that terminated 5 km and 3 km, respectively, from their head on the Salcantay massif. Cosmogenic 10Be surface exposure dating of boulders on the outer (n = 7) and inner (n = 7) moraine crests expands upon initial age control for these deposits and improves substantially on the precision of earlier 10Be measurements. The new results yield mean ages of 9.0 ± 0.3 ka for the outer moraine and 195 ± 24 years for the inner moraine, corresponding to glacial events during the early and latest Holocene. These ages are derived using the CRONUS-Earth 10Be exposure age calculator with Lal-Stone production rate scaling and the default height-pressure relationship. The inner moraine age correlates with the timing of the Little Ice Age as defined from northern mid- and high latitude records, and indicates considerable expansion of glaciers heading on Nevado Salcantay during this climatic minimum. Recent geomorphic mapping has identified similar sequences of moraines in adjacent drainages on and near Salcantay, suggesting a broader regional signal of two prominent Holocene glacial events in this segment of the southern Peruvian Andes; 10Be dating of these additional moraines is underway. Our new glacier chronologies complement ice core and lacustrine paleoclimate records in the vicinity, thereby increasing spatial and temporal coverage for identifying patterns of climate change in the tropical Andes during the Holocene. Apart from their paleoclimatic significance, the results also demonstrate a newly- developed capability of 10Be exposure

  2. Microstructures and petrology of melt inclusions in the anatectic sequence of Jubrique (Betic Cordillera, S Spain): Implications for crustal anatexis

    NASA Astrophysics Data System (ADS)

    Barich, Amel; Acosta-Vigil, Antonio; Garrido, Carlos J.; Cesare, Bernardo; Tajčmanová, Lucie; Bartoli, Omar

    2014-10-01

    We report a new occurrence of melt inclusions in polymetamorphic granulitic gneisses of the Jubrique unit, a complete though strongly thinned crustal section located above the Ronda peridotite slab (Betic Cordillera, S Spain). The gneissic sequence is composed of mylonitic gneisses at the bottom and in contact with the peridotites, and porphyroblastic gneisses on top. Mylonitic gneisses are strongly deformed rocks with abundant garnet and rare biotite. Except for the presence of melt inclusions, microstructures indicating the former presence of melt are rare or absent. Upwards in the sequence, garnet decreases whereas biotite increases in modal proportion. Melt inclusions are present from cores to rims of garnets throughout the entire sequence. Most of the former melt inclusions are now totally crystallized and correspond to nanogranites, whereas some of them are partially made of glass or, more rarely, are totally glassy. They show negative crystal shapes and range in size from ≈ 5 to 200 μm, with a mean size of ≈ 30-40 μm. Daughter phases in nanogranites and partially crystallized melt inclusions include quartz, feldspars, biotite and muscovite; accidental minerals include kyanite, graphite, zircon, monazite, rutile and ilmenite; glass has a granitic composition. Melt inclusions are mostly similar throughout all the gneissic sequence. Some fluid inclusions, of possible primary origin, are spatially associated with melt inclusions, indicating that at some point during the suprasolidus history of these rocks granitic melt and fluid coexisted. Thermodynamic modeling and conventional thermobarometry of mylonitic gneisses provide peak conditions of ≈ 850 °C and 12-14 kbar, corresponding to cores of large garnets with inclusions of kyanite and rutile. Post-peak conditions of ≈ 800-850 °C and 5-6 kbar are represented by rim regions of large garnets with inclusions of sillimanite and ilmenite, cordierite-quartz-biotite coronas replacing garnet rims, and the

  3. Microstructures and Petrology of Melt Inclusions in the Anatectic Sequence of Jubrique (Betic Cordillera, S Spain): Implications for Crustal Anatexis

    NASA Astrophysics Data System (ADS)

    Acosta-vigil, A.; Barich, A.; Garrido, C. J.; Cesare, B.; Tajčmanová, L.; Bartoli, O.

    2014-12-01

    We report a new occurrence of melt inclusions in polymetamorphic granulitic gneisses of the Jubrique unit, a complete though thinned crustal section located above the Ronda peridotite slab (Betic Cordillera, S Spain). The gneissic sequence is composed of mylonitic gneisses at the bottom and porphyroblastic gneisses on top. Mylonitic gneisses are strongly deformed rocks with abundant garnet and rare biotite. Except for the presence of melt inclusions, microstructures indicating the former presence of melt are rare or absent. Upwards in the sequence garnet decreases whereas biotite increases in proportion. Melt inclusions are present from cores to rims of garnets throughout the entire sequence. Most of the former melt inclusions are now totally crystallized and correspond to nanogranites, whereas some of them are partially made of glass or, more rarely, are totally glassy. They show negative crystal shapes and range in size from ≈5 to 200 micrometers, with a mean size of ≈30-40 micrometers. Daughter phases in nanogranites and partially crystallized melt inclusions include quartz, feldspars, biotite and muscovite; accidental minerals include kyanite, graphite, zircon, monazite, rutile and ilmenite; glass has a granitic composition. Melt inclusions are mostly similar throughout all the gneissic sequence. Some fluid inclusions, of possible primary origin, are spatially associated with melt inclusions, indicating that at some point during the suprasolidus history of these rocks granitic melt and fluid coexisted. Thermodynamic modeling and conventional thermobarometry of mylonitic gneisses provide peak conditions of ≈850 ºC and 12-14 kbar, corresponding to cores of large garnets with inclusions of kyanite and rutile. Post-peak conditions of ≈800-850 ºC and 5-6 kbar are represented by rim regions of large garnets with inclusions of sillimanite and ilmenite, cordierite-quartz-biotite coronas replacing garnet rims, and the matrix with oriented sillimanite. Previous

  4. The dynamics of serpentinite dehydration reactions in subduction zones: Constrains from the Cerro del Almirez ultramafic massif (Betic Cordillera, SE Spain)

    NASA Astrophysics Data System (ADS)

    Dilissen, Nicole; Garrido, Carlos J.; López Sánchez-Vizcaíno, Vicente; Padrón-Navarta, José Alberto

    2015-04-01

    Arc volcanism, earthquakes and subduction dynamics are controlled by fluids from downgoing slabs and their effect on the melting and rheology of the overlying mantle wedge. High pressure dehydration of serpentinite in the slab and the subduction channel is considered as one of the main sources of fluids in subduction zones. Even though this metamorphic reaction is essential in subduction activities, the behavior of the fluids, the kinetics and thermodynamics during the breakdown reaction are still poorly understood. The Cerro del Almirez (Nevado-Filábride Complex, Betic Cordillera, SE Spain) uniquely preserves the dehydration front from antigorite serpentinite to chlorite-harzburgite and constitutes a unique natural laboratory to investigate high-pressure dehydration of serpentinite. This reaction occurred in a subduction setting releasing up to 13 wt% of water, contributing significantly to the supply of fluids to the overlying mantle wedge. A key to the understanding of the metamorphic conditions prevailing during serpentinite dehydration is to study the two prominent textures -granofels and spinifex-like chlorite harzburgite- occurring in this reaction product. The detailed texture differences in the Chl-harzburgite can provide insights into diverse kinetic and thermodynamic conditions of this dehydration reaction due to variations in effective pressure and drainage conditions. It has been proposed that difference in overpressure (P') and deviation from growth equilibrium, i.e. overstepping, is responsible for these two types of textures [Padrón-Navarta et al., 2011]. The magnitude and duration of P' is highly dependent on dehydration kinetics [Connolly, 1997]. The fast pressure drop, with spinifex-texture as a product, can be linked to draining events expected after hydrofracturing, which are recorded in grain size reduction zones in this massif. According to this hypothesis, mapping of textural variation in Chl-harzburgite might be used as a proxy to

  5. Modeling modern glacier response to climate changes along the Andes Cordillera: A multiscale review

    NASA Astrophysics Data System (ADS)

    Fernández, Alfonso; Mark, Bryan G.

    2016-03-01

    Here we review the literature preferentially concerned with modern glacier-climate modeling along the Andes. We find a diverse range of modeling approaches, from empirical/statistical models to relatively complex energy balance procedures. We analyzed these models at three different spatial scales. First, we review global approaches that have included the Andes. Second, we depict and analyze modeling exercises aimed at studying Andean glaciers as a whole. Our revision shows only two studies dealing with glacier modeling at this continental scale. We contend that this regional approach is increasingly necessary because it allows for connecting the "average-out" tendency of global studies to local observations or models, in order to comprehend scales of variability and heterogeneity. Third, we revise small-scale modeling, finding that the overwhelming number of studies have targeted glaciers in Patagonia. We also find that most studies use temperature-index models and that energy balance models are still not widely utilized. However, there is no clear spatial pattern of model complexity. We conclude with a discussion of both the limitations of certain approaches, as for example the use of short calibration periods for long-term modeling, and also the opportunities for improved understanding afforded by new methods and techniques, such as climatic downscaling. We also propose ways to future developments, in which observations and models can be combined to improve current understanding of volumetric glacier changes and their climate causes.

  6. Development of unusual rock weathering features in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Rodbell, Donald T.; Frey, Holli M.; Manon, Matthew R. F.; Smith, Jacqueline A.; McTurk, Nicholas A.

    2012-01-01

    Mylonite textures in granodiorite boulders are responsible for higher rates of surface denudation of host rocks and the progressive development of unusual rock weathering features, termed weathering posts. These textures are characterized by smaller grain sizes, higher biotite content, and a higher biotite axial ratio in host rocks relative to weathering posts. Elemental concentrations do not show a significant difference between weathering posts and the host rocks in which they are found, and this reflects the absence of a weathering residue on the rock surfaces. Chemical weathering loosens the bonds between mineral grains through the expansion of biotite, and the loosened grains fall off or are blown off the boulder surface and continue their chemical alteration in the surrounding soil. The height of weathering posts on late Quaternary moraines increases at a linear rate of ~ 1.45 ± 0.45 cm (1000 yr)- 1 until post heights reach the diameter of host rocks. Such a rate of boulder denudation, if unrecognized, would generate significant errors (> 20%) in cosmogenic exposure ages for Pleistocene moraines. Given the paucity of boulders with diameters that significantly exceed 1.5 m, the maximum age of utility of weathering posts as a numeric age indicator is ~ 100 ka.

  7. Two sympatric new species of woodlizards (Hoplocercinae, Enyalioides) from Cordillera Azul National Park in northeastern Peru

    PubMed Central

    Venegas, Pablo J.; Torres-Carvajal, Omar; Duran, Vilma; de Queiroz, Kevin

    2013-01-01

    Abstract We report the discovery of two sympatric new species of Enyalioides from a montane rainforest of the Río Huallaga basin in northeastern Peru. Among other characters, the first new species is distinguishable from other Enyalioides by the combination of the following characters: strongly keeled ventral scales, more than 37 longitudinal rows of dorsals in a transverse line between the dorsolateral crests at midbody, low vertebral crest on the neck with vertebrals on neck similar in size to those between hind limbs, projecting scales on body or limbs absent, 96 mm maximum SVL in both sexes, and caudals increasing in size posteriorly within each autotomic segment. The second new species differs from other species of Enyalioides in having strongly keeled ventral scales, scales posterior to the superciliaries forming a longitudinal row of strongly projecting scales across the lateral edge of the skull roof in adults of both sexes, 31 or fewer longitudinal rows of strongly keeled dorsals in a transverse line between the dorsolateral crests at midbody, vertebrals on neck more than five times the size of vertebrals between hind limbs in adult males, projecting scales on body or limbs absent, and caudals increasing in size posteriorly within each autotomic segment. We also present an updated molecular phylogenetic tree of hoplocercines including new samples of Enyalioides rudolfarndti, Enyalioides rubrigularis, both species described in this paper, as well as an updated identification key for species of Hoplocercinae. PMID:23794824

  8. Two sympatric new species of woodlizards (Hoplocercinae, Enyalioides ) from Cordillera Azul National Park in northeastern Peru.

    PubMed

    Venegas, Pablo J; Torres-Carvajal, Omar; Duran, Vilma; de Queiroz, Kevin

    2013-01-01

    We report the discovery of two sympatric new species of Enyalioides from a montane rainforest of the Río Huallaga basin in northeastern Peru. Among other characters, the first new species is distinguishable from other Enyalioides by the combination of the following characters: strongly keeled ventral scales, more than 37 longitudinal rows of dorsals in a transverse line between the dorsolateral crests at midbody, low vertebral crest on the neck with vertebrals on neck similar in size to those between hind limbs, projecting scales on body or limbs absent, 96 mm maximum SVL in both sexes, and caudals increasing in size posteriorly within each autotomic segment. The second new species differs from other species of Enyalioides in having strongly keeled ventral scales, scales posterior to the superciliaries forming a longitudinal row of strongly projecting scales across the lateral edge of the skull roof in adults of both sexes, 31 or fewer longitudinal rows of strongly keeled dorsals in a transverse line between the dorsolateral crests at midbody, vertebrals on neck more than five times the size of vertebrals between hind limbs in adult males, projecting scales on body or limbs absent, and caudals increasing in size posteriorly within each autotomic segment. We also present an updated molecular phylogenetic tree of hoplocercines including new samples of Enyalioides rudolfarndti, Enyalioides rubrigularis, both species described in this paper, as well as an updated identification key for species of Hoplocercinae.

  9. Climate Change and Mountain Community Fire Management in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    All, J.; Medler, M.; Cole, R. J.; Arques, S.; Schmitt, C. G.

    2014-12-01

    In the central Andes of Peru, climate change is altering fire risk through changes in local meteorology and fuel loading. Greater moisture and favorable growing conditions are increasing vegetative productivity, which in turn increases fuel loads. This process is accentuated during El Nino events and potentially results in increased fire occurrence and frequency during relatively dry La Nina events. Park officials are concerned about the ramification of the changes on local ecology and tourist use of the resources. However, using a time-series of two different products from the MODIS Terra and Aqua platforms (Active Fire and Burned Area), TRMM 3B43 precipitation data, and Multivariate ENSO Index data we document fire occurrence and extent from 2000 to 2010 and our analysis indicates that fires are burning exclusively during winter months when there are no natural ignition sources. Globally, fire is used in conjunction with grazing to improve the regeneration and yield of grasses. During our interviews, locals claimed to only set fires in the buffer zone outside of the park, but our analysis indicates that the buffer zone rarely burns and that most fires begin within the park and only occasionally move into the buffer zones. Additionally, we determined that although this is small-scale fire activity every year, overall fire is having a very minor effect on local systems. The park service must develop programs to work with local grazing stakeholders to better limit the impacts of fire, while also address the negative perceptions from tourists in the future. In this instance, fire perception and fire reality are not the same and the challenge for resource managers is how to reconcile these two factors in order to more effectively manage the parklands.

  10. Arboreal spiders in eastern hemlock.

    PubMed

    Mallis, Rachael E; Rieske, Lynne K

    2011-12-01

    Eastern hemlock [Tsuga canadensis (L.) Carrière] is a foundation species in forests of eastern North America that plays a key role in ecosystem function. It is highly susceptible to the exotic invasive hemlock woolly adelgid (Adelges tsugae Annand), which is causing widespread hemlock mortality. We surveyed the spider communities of eastern hemlock and deciduous canopies over 2 yr, collecting over 4,000 spiders from 21 families. We found that eastern hemlock canopies harbored a more abundant, rich, and diverse spider community than did deciduous canopies. Five spider families were present in our hemlock collections that were absent from the deciduous collections, including Mysmenidae, Theridiosomatidae, Mimetidae, Lycosidae, and Agelenidae. In hemlock canopies there were 4× the number of web builders, consisting primarily of the Tetragnathidae and Araneidae, than active hunters, consisting primarily of the Anyphaenidae and the Salticidae. Ours is the first in depth study of the spider community in eastern hemlock. Spider abundance in hemlock canopies suggest that they may play a role regulating herbivore populations, and could possibly affect the invasive hemlock woolly adelgid, either through direct consumption of the adelgids themselves or through interactions with classical biological control agents.

  11. Paleoclimate and paleoelevation in the western US Cordillera, 80 Ma to Present

    NASA Astrophysics Data System (ADS)

    Snell, K. E.; Thompson, J. M.; Foreman, B. Z.; Wernicke, B. P.; Chamberlain, C. P.; Eiler, J. M.; Koch, P. L.

    2011-12-01

    . Throughout the Late Mesozoic and Cenozoic, both MAT and summer paleotemperature estimates are higher than modern MAT and summer temperature, but the relatively consistent difference between these records implies a seasonal range in temperature that was similar to modern. Summer temperatures from low paleoelevation sites during the Late Cretaceous to the Early Eocene are relatively warm (30 - 40 degrees C), though these values may include a few degrees of radiant solar heating of the surface. Interestingly, Early Eocene-aged carbonate samples from southwest Montana are cooler on average than other carbonate samples of roughly the same age, but are similar in temperature to samples thought to be at high elevation during the Late Cretaceous. Thus, these samples may reflect high elevation summer temperatures, rather than low elevation temperatures, demonstrating the utility of this combined spatial and temporal approach to evaluating terrestrial paleoenvironmental records.

  12. The Spatial Variation of Modern and LLGM Reconstructed ELAs in the Cordilleras Raura and Huayhuash, Peru

    NASA Astrophysics Data System (ADS)

    Galster, J. C.; McFadden, E.; Ramage, J. M.; Rodbell, D. T.

    2006-12-01

    The estimation of glacial equilibrium line altitudes (ELAs) can be an important proxy for climate change, and the comparison of ELAs is particularly robust when examined over both space and time. Small, high altitude remnant glaciers and the preserved moraines of previous glaciations in the Peruvian Andes preserve a record of past temperature and moisture fluxes between the Amazon basin and the Pacific Ocean. This comparison between modern, high-resolution records and longer but broader records allow for more robust conclusions and implications for future temperature changes. A suite of satellite images were used to measure the modern ice cover and ELAs from 1986 to 2005, and a combination of satellite and digital elevation data to map and reconstruct the probable extent of local last glacial maximum (LLGM) glaciation on two adjacent ranges, C. Huayhuash (10° 15' S, 77° 55' W) and C. Raura (10° 25' S, 76° 48' W). Modern ELAs were quantified using late-dry season Landsat images for minimum snow cover and delineating the snowline for each glacier approximately annually between 1986 and 2005. The snowline at the time of annual minimum snow cover approximates the ELA. Modern ELAs have risen approximately 14 m over the 20 year record, although there are spatial differences in the magnitudes of change in ELAs which range from 114 to -20. The observed temporal and spatial trends in modern ELAs allow for the spatial trends in ELA and ELA-depression during the LLGM to be evaluated in the context of terrain features, including the influence of elevation, slope, aspect, and orientation with respect to and distance from the prevailing moisture source. Paleo-ELAs were reconstructed for the Pleistocene LLGM and for well-preserved intermittent stages using ASTER and SRTM data, known glacial limits, and the individual valley's hypsometry to recreate the paleo-glacier's surface morphometry. Calculating ELAs from the known glacial limits and the individual valley hypsometries

  13. Development of Ideas About Holocene and Latest Pleistocene Glacier Advances in the North American Cordillera

    NASA Astrophysics Data System (ADS)

    Osborn, G.

    2014-12-01

    dismissed in the literature and have not gained general acceptance.Most recently, Menounos found so-called "monster moraines" well downstream of LIA moraines in northern British Columbia and the Yukon where there are no small Crowfoot-type outer moraines. New dates suggest these monsters are a different manifestation of the YD associated with the decaying Cordilleran Ice Sheet.

  14. Glacial and periglacial geomorphology and chronology around the Nevado de Chañi (Cordillera Oriental of Jujuy): implication for past climate in NW Argentina

    NASA Astrophysics Data System (ADS)

    Martini, M. A.; Strelin, J. A.; Kaplan, M. R.; Schaefer, J. M.

    2012-12-01

    The Nevado de Chañi (24°3' 45'' S; 65° 44' 43'' W) is one of the highest massifs in northwestern Argentina (5882 masl). It is the summit of a N-S trending mountain range located just north of the Arid Diagonal, which separates the southern Pacific westerlies from the South American Summer Monsoon domains. This range consists of Precambrian and Paleozoic sedimentary rocks intruded by Ordovician granites. It has been broadly eroded by glaciers during the Late Pleistocene but today no glaciers exist in the area due to aridity, and periglacial activity takes a main role in the development of the landscape above 4600m. The orographically-driven climate conditions, with seasonal summer wet-air masses moving from the Atlantic, determine that the west side of the massif is clearly drier and probably warmer than the east-facing side. Three main groups of moraines are recognized on both sides of Chañi. We collected moraine boulders from the different glacial landforms for 10Be surface exposure dating, which is in progress. Seven peat bogs were cored to obtain minimum-limiting radiocarbon ages of the deglaciation and limnogeologic change during the post glacial period. Ten preliminary 10Be dates reveal pre-LGM (Last Glacial Maximum) and post LGM ages for the glacier moraines on the west side of the massif. The periglacial geomorphology around Chañi is mainly represented by scree activity, giving way to solifluction and formation of protalus lobes. We focused especially on rock glacier formation. Active, inactive, and fossil rock glaciers were distinguished taking into account geomorphological characteristics such as the frontal slope and ridge and furrows preservation. The lower limit for active and inactive/fossil rock glaciers is located above ~4700m and ~4500m, respectively. Cross-cutting relations with the dated moraines will provide the maximum age of these geomorphic features. Active rock glaciers at present have predominately S and E slopes and are located bellow

  15. Geologic constraints and controls on petroleum migration in eastern Venezuela basin

    SciTech Connect

    Aymard, R.; Baker, D.R.; Lander, R.

    1986-05-01

    This work focuses on the petroleum accumulations of the Anaco, Greater Oficina, and Faja (heavy-oil) areas along a north-south transect through the Eastern Venezuela basin. The authors believe these major accumulations are directly related to the Tertiary generative basin defined by the enormous fill of Tertiary sediments extending from the Guayana shield shelf edge on the south to the loci of Tertiary depocenters adjacent to the Venezuela coastal cordillera on the north. Factors that place constraints on the evolution of petroleum development in the Eastern Venezuela basin include: (1) accumulations of heavy oil in the Faja are unusually large; (2) petroleum in the Greater Oficina area is dominantly paraffinic-naphthenic, but is variable; (3) paraffinic (waxy) petroleum occurs within the Anaco area (4) petroleum is concentrated in the basal part of the Tertiary section; (5) most of the petroleum in sandstone reservoirs occurs near the shelf edge within immature sections, i.e., below the oil-generation threshold; and (6) petroleum is trapped on the north (basinal) side of faults. The major controls of petroleum variability and occurrence appear to be: (1) the temporal relationship between the generation and fluid expulsion history of the Tertiary basin fill; (2) the stratigraphic framework involving distinctive regressive-transgressive sequences that progressively onlap the shelf edge and are characterized by repetitive sedimentary packages (lower prodelta and upper transgressive shales separated by medial sandstones), which behaved as semi-independent units of generation, expulsion, and migration; (3) the related temporal development of the faults as effective seals.

  16. Tectonics and volcanism of Eastern Aphrodite Terra: No subduction, no spreading

    NASA Technical Reports Server (NTRS)

    Hansen, Vicki L.; Keep, Myra; Herrick, Robert R.; Phillips, Roger J.

    1992-01-01

    Eastern Aphrodite Terra is approximately equal in size to the western North American Cordillera, from Mexico to Alaska. Its size and unique landforms make it an important area for understanding the tectonics of Venus, yet models for its formation are diametrically opposed. This region is part of the Equatorial Highlands, which was proposed as a region of lithospheric thinning, isostatic uplift, and attendant volcanism. Eastern Aphrodite Terra is dominated by circular structures within which deformation and volcanism are intimately related. These structures are marked by radial and concentric fractures, and volcanic flows that emanate from a central vent, as well as from concentric fracture sets. Cross-cutting relations between flows and concentric fracture sets indicate that outer concentric fracture sets are younger than inner fracture sets. The circular structures are joined by regional northeast- to east-trending fractures that dominantly postdate formation of the circular structures. We propose that the circular structures 'grow' outward with time. Although these structures probably represent addition of crust to the lithosphere, they do not represent significant lithospheric spreading or convergence, and the region does not mark the boundary between two distinct tectonic plates. This region is not easily explained by analogy with either terrestrial midocean rifts or subduction zones. It is perhaps best explained by upwelling of magma diapirs that blister the surface, but do not cause significant lithospheric spreading. Further study of the structural and volcanic evolution of this region using Magellan altimetry and SAR data should lead to better understanding of the tectonic evolution of this region.

  17. Managing glacier related risks in the Chucchún Catchment, Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Muñoz, Randy; Gonzáles, César; Price, Karen; Frey, Holger; Huggel, Christian; Cochachin, Alejo; García, Javier; Mesa, Luis

    2015-04-01

    On April 11 2010, the city of Carhuaz and settlements in the Chucchún Catchment (Ancash region, Peru) suffered the impact of a glacier lake outburst flood. An avalanche of rock and ice from the Mount Hualcán hit the glacier lake 513, triggering a glacial lake outburst flood (GLOF) of 1 million m3 which destroyed farmland and several infrastructures. Although there was no loss of human life, the event caused panic in the population. In consequence, the Municipality of Carhuaz prioritized GLOF-related risk management. The Glacier Project, funded by Swiss Agency for Development and Cooperation, and executed by CARE Peru and the University of Zurich, fosters the coordination among public institutions (Glaciological Unit of the National Water Authority, the Ministry of Environment and Municipality) and the population for risk management. In this contribution we present all components of the risk management strategy as well as the lessons learned during the implementation. Risk management involves managing both glacier hazard as well as the vulnerability of the population. In this framework a glaciological and geomorphological characterization of Mount Hualcán and lake 513 was perfomed in order to model past and potential future outburst floods and to assess the slope stability conditions. Based on three potential GLOF scenarios of different magnitudes, a hazard map was produced for the entire catchment, which served as the basis for the vulnerability and risk assessment as well as for the design and the implementation of an Early Warning System (EWS), including evacuation planning. The EWS consists of 4 components: 1) knowledge of risk, through hazard and vulnerability characterization; 2) monitoring and alert, through the installation of monitoring stations on lake 513 for detecting avalanches with geophones and cameras; 3) broadcasting and communications, through the implementation of communication protocols between the Municipality of Carhuaz and emergency

  18. Prevalence of acute mountain sickness in the Eastern Alps.

    PubMed

    Mairer, Klemens; Wille, Maria; Bucher, Thomas; Burtscher, Martin

    2009-01-01

    Little information is available on the prevalence of acute mountain sickness (AMS) in the Eastern Alps compared with the Western Alps. Because of differences regarding the populations of mountaineers, we hypothesized that the prevalence differs between the Eastern and Western Alps. Thus, we determined the prevalence and risk factors of AMS at four different altitudes in the Eastern Alps of Austria. Four hundred and thirty-one recreational hikers were studied using questionnaires on the morning of their first night at high altitude. A diagnosis of AMS was based on a Lake Louise Score > or =4, the presence of headache, and at least one additional symptom. Overall 16.2% of the subjects met the criteria for AMS, and the prevalence of AMS increased significantly with altitude (2200 m: 6.9%; 2500 m: 9.1%; 2800 m: 17.4%; 3500 m: 38.0%). Heavy perceived exertion, a history of migraine, the absolute altitude reached, little mountaineering experience, and inadequate water intake (< or =2 L) were independent AMS risk factors. The reported altitude-related AMS prevalence in the Western Alps is 4% to 8% lower compared with that found in this study for the Eastern Alps. In conclusion, the prevalence of AMS is higher in the tourist population of the Eastern Alps compared to the more experienced mountaineers of the Western Alps. Consideration of easily modifiable risk factors such as individual exertion and water intake could markedly reduce AMS and contribute to the enjoyment of mountaineering.

  19. Ungulate predation and ecological roles of wolves and coyotes in eastern North America.

    PubMed

    Benson, John F; Loveless, Karen M; Rutledge, Linda Y; Patterson, Brent R

    2017-01-08

    Understanding the ecological roles of species that influence ecosystem processes is a central goal of ecology and conservation biology. Eastern coyotes (Canis latrans) have ascended to the role of apex predator across much of eastern North America since the extirpation of wolves (Canis spp.) and there has been considerable confusion regarding their ability to prey on ungulates and their ecological niche relative to wolves. Eastern wolves (C. lycaon) are thought to have been the historical top predator in eastern deciduous forests and have previously been characterized as deer specialists that are inefficient predators of moose because of their smaller size relative to gray wolves (C. lupus). We investigated intrinsic and extrinsic influences on per capita kill rates of white-tailed deer (Odocoileus virginianus) and moose (Alces alces) during winter by sympatric packs of eastern coyotes, eastern wolves, and admixed canids in Ontario, Canada to clarify the predatory ability and ecological roles of the different canid top predators of eastern North America. Eastern coyote ancestry within packs negatively influenced per capita total ungulate (deer and moose combined) and moose kill rates. Furthermore, canids in packs dominated by eastern coyote ancestry consumed significantly less ungulate biomass and more anthropogenic food than packs dominated by wolf ancestry. Similar to gray wolves in previous studies, eastern wolves preyed on deer where they were available. However, in areas were deer were scarce, eastern wolves killed moose at rates similar to those previously documented for gray wolves at comparable moose densities across North America. Eastern coyotes are effective deer predators, but their dietary flexibility and low kill rates on moose suggest they have not replaced the ecological role of wolves in eastern North America.

  20. Zircon U-Pb geochronology and heavy mineral composition of the Camaná Formation, southern Peru: Constraints on sediment provenance and uplift of the Coastal and Western Cordilleras

    NASA Astrophysics Data System (ADS)

    Alván, Aldo; von Eynatten, Hilmar; Dunkl, István; Gerdes, Axel

    2015-08-01

    In the forearc of the Central Andes of southern Peru, the Cenozoic Camaná Basin (16°25‧S to 17°15‧S) forms a ∼NW-SE elongated depression filled with coarse-grained deltaic and fluvial deposits. These deposits are termed Camaná Formation. We have applied for the first time, advanced multi-method analytical techniques to sediments of the Camaná Formation in order to define precise sedimentation ages, unravel sediment provenance, and to explain its tectono-sedimentary evolution. Zircon U-Pb geochronology and multiple geological evidences suggest that the Camaná Formation ranges in age from Late Oligocene to Late Miocene, and may even extend into the Pliocene. We propose a provenance model for the Camaná Formation based on U-Pb geochronology, heavy mineral analysis, and single-grain mineral chemistry by LA-ICP-MS. This model suggests that sediments of the lower part of the Camaná Formation derive from rocks forming the Coastal Cordillera (i.e. the Arequipa Massif and the San Nicolas Batholith) and the widespread ignimbrites of the ∼24-10 Ma Huaylillas volcanic arc. In contrast, sediments of the upper part of the Camaná Formation derive predominantly from rocks forming the Western Cordillera (i.e. the Arequipa Massif, the Tacaza Group, and the Coastal Batholith) and products of the ∼10-3 Ma Lower Barroso volcanic arc). Accordingly, we infer that uplift of the Coastal Cordillera has strongly influenced deposition of the Camaná Formation since Late Oligocene. A marked shift in provenance within the Camaná Formation at around Middle to Late Miocene time (14-12 Ma) suggests drastic uplift of the Western Cordillera at that time. This uplift has triggered increased relief and erosion in the Western Cordillera, and subsequent deposition of fluvial conglomerates in the Camaná Basin.

  1. Spatiotemporal monthly rainfall forecasting for south-eastern and eastern Australia using climatic indices

    NASA Astrophysics Data System (ADS)

    Montazerolghaem, Maryam; Vervoort, Willem; Minasny, Budiman; McBratney, Alex

    2014-05-01

    Knowledge about future rainfall would significantly benefit land, water resources and agriculture management, as this assists with planning and management decisions. Forecasting spatiotemporal monthly rainfall is difficult, especially in Australia where there is a complex interaction between topography and the effect of Indian and Pacific Ocean. This study describes a method for spatiotemporal monthly rainfall forecasting in south-eastern and eastern part of Australia using climatic and non-climatic variables. Rainfall data were obtained from Bureau of Meteorology (BoM) from 136 high quality weather stations from the south-eastern and eastern part of Australia with monthly rainfall records from 1879 to 2012. To reduce spatial complexity of the area and improve model accuracy, spatial classification (regionalization) was considered as first step. Significant predictors for each sub-region among lagged climatic input variables were selected using Fuzzy Ranking Algorithm (FRA). Climate classification: 1) discovered homogenous sub-regions with a similar rainfall patterns and investigated spatiotemporal rainfall variations in the area, 2) allowed selection of significant predictors with a fine resolution for each area, 3) improved the prediction model and increased model accuracy. PCA was used to reduce the dimensions of the dataset and to remove the rainfall time series correlation. K-means clustering was used on the loadings of PCs describing 93% of long-term monthly rainfall variations. The analysis was repeated for different numbers of sub-regions (3 - 8) to identify the best number of clusters to improve the forecast model performance. Subsequently, a Fuzzy Ranking Algorithm (FRA) was applied to the lagged climatic predictors and monthly rainfall in each sub-region to identify the best predictors. After these two stages of pre-processing, a Neural Network model was developed and optimized for each of the sub-regions as well as for the entire area. It is concluded

  2. Precipitation and temperature changes in eastern India by multiple trend detection methods

    NASA Astrophysics Data System (ADS)

    Sharma, Chandra Shekhar; Panda, Sudhindra N.; Pradhan, Rudra P.; Singh, Amanpreet; Kawamura, Akira

    2016-11-01

    The present study deals with spatial and temporal trend analysis of precipitation and temperature (1970-2004) in eastern India. Long-term trend direction and magnitude of change over time (annual and seasonal) were detected and analyzed by Mann-Kendall test, Sen's slope estimator, Least square linear regression, Spearman rank correlation and Sequential Mann-Kendall test. In addition to it, correlation analysis was also performed. Trend analysis of annual rainfall by different methods indicated similar annual trends in eastern India. North-eastern, south-eastern and western parts of eastern India indicated increasing trend, whereas the north-western, central and southern parts showed decreasing trend. A similar trend was observed by different methods in case of seasonal rainfall. During winter season, decreasing trend was observed in the central part, whereas similar results were obtained for pre-and post-monsoon in the western part. The trend during monsoon season was found similar to annual rainfall trend. Abrupt change in trend of rainfall with time was lacking in eastern India. Maximum temperature analysis indicated increasing trend in the western part for all the seasons (except in monsoon) and decreasing trend in the eastern part. On the contrary, increasing trend was observed in the eastern part and decreasing trend in the western half of the study area for all the seasons in case of minimum temperature. Significant changes were observed during monsoon season as compared to other seasons. A decreasing trend in mean temperature was observed in the central, southern and north western parts, whereas it was found to be increasing in the north-eastern, western and south-eastern parts. In majority of the eastern India region, any abrupt change of trend in temperatures with time was not clearly observed. Negative correlation between rainfall and maximum temperature was observed in the entire eastern India. Similar results were observed in case of minimum temperature

  3. Reducing risks from hazardous glacier lakes in the Cordillera Blanca (Peru): Six decades of experience and perspectives for the future

    NASA Astrophysics Data System (ADS)

    Portocarrero, Cesar; Cochachin, Alejo; Frey, Holger; González, Cesar; Haeberli, Wilfried; Huggel, Christian

    2016-04-01

    Outbursts from glacier lakes at various spatial and temporal scales have had marked geomorphological effects in many mountain ranges. In many glacierized Andean mountain regions substrates of human settlements made out of flood and debris-flow deposits are testimonies of such events. Examples in the Cordillera Blanca, Peru, are the towns of Caraz, Carhuaz or parts of Huaraz. Continued glacier shrinking since the end of the Little Ice Age caused the formation or enlargement of numerous lakes. The outburst of Laguna Palcacocha, destroying the centre of Huaraz and causing more than 1800 losses of life in December 1941, marked the beginning of systematic risk reduction work in Peru. Corresponding efforts included glacier and lake inventories, hazard assessments, definition of high-risk situations, and completion of engineering work for lake-level lowering in more than 30 cases. The latter comprises outlet reinforcements on morainic dams as well as artificial tunnels in bedrock thresholds. This work has been remarkably efficient as documented in the latest case of the Laguna Huallcacocha (Carhuaz-Ancash), where the earlier made installations withstood the erosive power of an impact wave from an ice avalanche in 2015. In the case of the Laguna 513, the impact wave and far-reaching flood caused by a rock/ice avalanche from Nevado Hualcán in April 2010 showed that the risk had been essentially reduced by the preventive lake-level lowering in the early 1990s but not to zero. Risk assessments, planning, construction and non-structural risk reduction efforts continue. Work is in progress to increase the safety of Laguna Palcacocha where extensive assessments and model calculations had been carried out. Risks related to rock/ice avalanches into lakes from steep icy slopes and related to de-buttressing processes as well as long-term permafrost degradation increases. Based on morphological indications and numerical modelling (GlabTop) an inventory of possible future lakes

  4. Isotopic composition of Pb in ore deposits of the Betic Cordillera, Spain; origin and relationship to other European deposits

    USGS Publications Warehouse

    Arribas , Antonio; Tosdal, Richard M.

    1994-01-01

    The Betic Cordillera in southern Spain is a complex Alpine fold belt that resulted from the Cretaceous through Cenozoic collision of Africa with Europe. The region is illustrative of one of the characteristics of the Alpine-Mediterranean orogen: the occurrence over a limited area of mineral deposits with a wide variety of host rocks, mineralization ages, and styles. The metamorphic basement in the Betic zone is characterized by a nappe structure of superimposed tectonostratigraphic units and consists of lower Paleozoic to Lower Triassic clastic metasedimentary rocks. This is overlain by Middle to Upper Triassic platform carbonate rocks with abundant strata-bound F-Pb-Zn-(Ba) deposits (e.g., Sierra de Gador, Sierra Alhamilla). Cretaceous to Paleogene subduction-related compression in southeastern Spain was followed by Miocene postcollisional extension and resulted in the formation of the Almeria-Cartagena volcanic belt and widespread hydrothermal activity and associated polymetallic mineralization. Typical Miocene hydrothermal deposits include volcanic-hosted Au (e.g., Rodalquilar) and Ag-rich base metal (e.g., Cabo de Gata, Mazarron) deposits as well as complex polymetallic veins, mantos, and irregular replacement bodies which are hosted by Paleozoic and Mesozoic metamorphic rocks and Neogene sedimentary and volcanic rocks (e.g., Cartagena, Sierra Almagrera, Sierra del Aguilon, Loma de Bas).Lead isotope compositions were measured on sulfide samples from nine ore districts and from representative fresh samples of volcanic and basement rock types of the region. The results have been used to evaluate ore-forming processes in southeastern Spain with emphasis on the sources of metals. During a Late Triassic mineralizing event, Pb was leached from Paleozoic clastic metasedimentary rocks and incorporated in galena in strata-bound F-Pb-Zn-(Ba) deposits ( 206 Pb/ 204 Pb = 18.332 + or - 12, 207Pb/ 204 Pb = 15.672 + or - 12, 208 Pb/ 204 Pb = 38.523 + or - 46). The second

  5. The eastern Asian and eastern and western North American floristic disjunction: congruent phylogenetic patterns in seven diverse genera.

    PubMed

    Xiang, Q Y; Soltis, D E; Soltis, P S

    1998-10-01

    originated at different geological times. Analysis of divergence times using the molecular clock indicates that species of Cornus, Boykinia, and Calycanthus may have diverged at different geological times, suggesting that the floristic disjunction involving eastern Asia and North America may not be simple; it may have involved multiple historical events at very different geological times in different genera.

  6. Comparison of Glacial Records From 10°S and 11°S in the Peruvian Andes Suggests Similar Forcings but Different Local Influences

    NASA Astrophysics Data System (ADS)

    Smith, J. A.; Rodbell, D. T.

    2010-12-01

    Moraine records of glaciation from three sites in the central Peruvian Andes are broadly consistent over the last glacial cycle (since MIS 5). Surface-exposure dating (10Be) of moraines east and west of Lake Junin (11°00'S, 76°00'W, 4082 masl) and 180 km northwest at the Nevado Jeulla Rajo (NJR) massif (10°00'S, 77°16'W) at the southern end of the Cordillera Blanca suggests a link between glacial advances and increased precipitation associated with Heinrich events. On the eastern side of Lake Junin, the most extensive moraines are >150 ka, but end moraines farther upvalley date to the local last glacial maximum (LLGM, 25-30 ka) and a late-glacial stillstand or readvance (14-18 ka). Surface-exposure ages on a moraine and bedrock in the Santuario Nacional Bosque de Piedras de Huayllay (BPH) on the western side of Lake Junin (10°59'S, 76°20'W) are consistent with 10Be ages on younger moraines on the eastern side: ~26 and ~20 ka on two quartz boulders, ~14-15 ka on four ignimbrite boulders, and ~45 ka on bedrock below a trimline in the valley wall. The NJR massif (ca. 5600 masl) hosts a number of small glaciers within a cirque on its southwestern face; large lateral moraines extend onto the Conococha Plain (ca. 4050 masl) from west-facing valleys. Fault scarps on moraines and valley floors on the western side of NJR show the trace of the active, west-dipping Cordillera Blanca Normal Fault (CBNF). At NJR, 10Be ages indicate that the largest lateral moraines were deposited during similar intervals (27-32 ka and 15-18 ka) to the younger moraines in the eastern Junin valleys and BPH. Differences between the Junin/BPH and NJR records are intriguing. NJR lacks the morphologically distinct pre-MIS 5 moraines that are present in valleys east of Lake Junin, although the Conococha Plain adjacent to NJR is underlain by till and outwash that is likely >50 ka, based on 10Be ages of surface cobbles. At NJR, avulsion of two glacial valleys preserved older, smaller pairs of

  7. Fall management of eastern gamagrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recent research has suggested that eastern gamagrass (EGG) may be an effective alternative to chopped straw in the blended diets of dairy heifers and cows. Most extension materials discussing appropriate fall management of EGG recommend avoiding harvest within 6 weeks of first frost. Using this guid...

  8. Eastern New Mexico University. Exemplars.

    ERIC Educational Resources Information Center

    Iannozzi, Maria

    This report describes efforts by Eastern New Mexico University (ENMU) to recast its mission more narrowly while at the same time reducing the sense of remoteness and disconnection, as well as geographic isolation, between the main campus and its branch campuses. In the early 1980s, ENMU suffered from mission drift, in part as a result of its…

  9. Citizenship Norms in Eastern Europe

    ERIC Educational Resources Information Center

    Coffe, Hilde; van der Lippe, Tanja

    2010-01-01

    Research on Eastern Europe stresses the weakness of its civil society and the lack of political and social involvement, neglecting the question: What do people themselves think it means to be a good citizen? This study looks at citizens' definitions of good citizenship in Poland, Slovenia, the Czech Republic and Hungary, using 2002 European Social…

  10. Levelling Profiles and a GPS Network to Monitor the Active Folding and Faulting Deformation in the Campo de Dalias (Betic Cordillera, Southeastern Spain)

    PubMed Central

    Marín-Lechado, Carlos; Galindo-Zaldívar, Jesús; Gil, Antonio José; Borque, María Jesús; de Lacy, María Clara; Pedrera, Antonio; López-Garrido, Angel Carlos; Alfaro, Pedro; García-Tortosa, Francisco; Ramos, Maria Isabel; Rodríguez-Caderot, Gracia; Rodríguez-Fernández, José; Ruiz-Constán, Ana; de Galdeano-Equiza, Carlos Sanz

    2010-01-01

    The Campo de Dalias is an area with relevant seismicity associated to the active tectonic deformations of the southern boundary of the Betic Cordillera. A non-permanent GPS network was installed to monitor, for the first time, the fault- and fold-related activity. In addition, two high precision levelling profiles were measured twice over a one-year period across the Balanegra Fault, one of the most active faults recognized in the area. The absence of significant movement of the main fault surface suggests seismogenic behaviour. The possible recurrence interval may be between 100 and 300 y. The repetitive GPS and high precision levelling monitoring of the fault surface during a long time period may help us to determine future fault behaviour with regard to the existence (or not) of a creep component, the accumulation of elastic deformation before faulting, and implications of the fold-fault relationship. PMID:22319309

  11. Language in Education in Eastern Africa.

    ERIC Educational Resources Information Center

    Gorman, T. P., Ed.

    This volume contains the papers given at the first Eastern Africa Conference on Language and Linguistics, held in Dar es Salaam in December 1968, under the auspices of the Survey of Language Use and Language Teaching in Eastern Africa. The chief aim of the Conference was to bring together scholars and teachers working in Eastern Africa interested…

  12. The role of western Mediterranea tectonic evolution in the geometry of a karstic domain in the Betic Cordilleras (Sierra Gorda, Spain): Importance of a tardy extensional regime

    NASA Astrophysics Data System (ADS)

    Pistre, Séverin; Lopez-Chicano, Manuel; Pulido-Bosch, Antonio; Drogue, Claude

    1999-01-01

    Located in the central part of the Betic Cordilleras, the large carbonate Sierra Gorda Massif provides an example of a west-Mediterranean karstic aquifer. In spite of a complex polyphased tectonic history, the fracturing presents, from aerial views and at outcrop scale a quite organised geometry. Four fracture directions are found over the massif: N000-010, N050-070, N090-100 and N140-170. The statistical and geostatistical approach allows the characteristics (lengths, orientations) and the spatial structure for each fracture set to be determined. The NOOO-010 and N140-170 sets are grouped in packets whereas the two other sets are grouped in bands. The microtectonic study describes the evolution of the massif in the geodynamic context of this part of Mediterranea, distinguishing three recent stages of brittle tectonic activity in the massif: a WNW-ESE Middle Miocene compression, then a NNW-SSE to NW-SE compression with a poorly wrenching regime, and finally a probably pre-Quaternary N-S radial distension. This last stage is essential for the karstification of the massif and groundwater circulation. From the combined analysis of fracture network geometry and palaeostresses a multiple porosity model in agreement with hydrological observations made inside the massif can be proposed: in particular, the hectometric N090-100 (and N050-070) fractures which are essential for the network connectivity, and have a major drainage role at aquifer scale, while the N000-010 and N140-170 ones have a more local drainage role. This extensive tardy regime, which is for the first time described separately from the internal zones of the Cordilleras, must be considered as a significant phenomenon on a regional scale, and henceforth integrated in future geodynamic schemes of this part of Mediterranea.

  13. Long-term monitoring of tropical alpine habitat change, Andean anurans, and chytrid fungus in the Cordillera Vilcanota, Peru: Results from a decade of study.

    PubMed

    Seimon, Tracie A; Seimon, Anton; Yager, Karina; Reider, Kelsey; Delgado, Amanda; Sowell, Preston; Tupayachi, Alfredo; Konecky, Bronwen; McAloose, Denise; Halloy, Stephan

    2017-03-01

    The Cordillera Vilcanota in southern Peru is the second largest glacierized range in the tropics and home to one of the largest high-alpine lakes, Sibinacocha (4,860 m). Here, Telmatobius marmoratus (marbled water frog), Rhinella spinulosa (Andean toad), and Pleurodema marmoratum (marbled four-eyed frog) have expanded their range vertically within the past century to inhabit newly formed ponds created by ongoing deglaciation. These anuran populations, geographically among the highest (5,200-5,400 m) recorded globally, are being impacted by the chytrid fungus Batrachochytrium dendrobatidis (Bd), and the disease it causes, chytridiomycosis. In this study, we report results from over a decade of monitoring these three anuran species, their habitat, and Bd infection status. Our observations reveal dynamic changes in habitat including ongoing rapid deglaciation (18.4 m/year widening of a corridor between retreating glaciers from 2005 to 2015), new pond formation, changes in vegetation in amphibian habitat, and widespread occurrence of Bd in amphibians in seven sites. Three of these sites have tested positive for Bd over a 9- to 12-year period. In addition, we observed a widespread reduction in T. marmoratus encounters in the Vilcanota in 2008, 2009, and 2012, while encounters increased in 2013 and 2015. Despite the rapid and dynamic changes in habitat under a warming climate, continued presence of Bd in the environment for over a decade, and a reduction in one of three anuran species, we document that these anurans continue to breed and survive in this high Andean environment. High variability in anuran encounters across sites and plasticity in these populations across habitats, sites, and years are all factors that could favor repopulation postdecline. Preserving the connectivity of wetlands in the Cordillera Vilcanota is therefore essential in ensuring that anurans continue to breed and adapt as climate change continues to reshape the environment.

  14. Spatiotemporal variability and differentiation between anthropogenic and natural contamination of heavy metals of surface water: a case study in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Guittard, A.; Baraer, M.; McKenzie, J. M.; Mark, B. G.; Fernandez, A.; Walsh, E.; Santos Perez, A.

    2015-12-01

    The Rio Santa, Peru, drains the western slopes of the glacierized Cordillera Blanca and provides water resources at almost all levels of the watershed. As it flows away from the valleys of the Cordillera Blanca, the Rio Santa takes out pollution from numerous sources, including acid mine drainage and natural sulfide oxidation by-products. The Rio Santa dry season discharge decline that is projected to be a consequence of glaciers retreat will probably have implications for the evolution of water pollution. This threat makes the characterization of the actual contamination mechanisms of primary importance. The present study focuses, first, on the spatiotemporal variability of heavy metal contamination across the entire Rio Santa Watershed and secondly on differentiating anthropogenic and natural contaminated sites. First, a macroscale sampling has been done during the summer 2013 to provide an overview of the contamination by trace metal, in water, suspended sediments and riverbed sediments. In addition, 30 water samples were taken from a point next to the city of Huaraz at a frequency of once every 2 weeks and analyzed for trace metals. Secondly, in order to identify hydrochemical contaminant origin dependant signatures in the Rio Santa watershed, 5 areas of known contamination origins were sampled during the summer 2014.Spatially speaking, we observed that most pollution is located in the south of the watershed, and that a large part of the arsenic that reaches the Santa in an aqueous phase does not make it to the outlet but remains trapped in the riverbed. Annual variation in water shows a very unusual fluctuation in Mn compare to other trace metal which are relatively stable. By differencing anthropogenic and natural sites and by considering glaciers melt and decrease water in future what would be the impact of the part of natural contaminated sites versus anthropogenic, mining and cities, on the water quality? Preliminary results show that anthropogenic sites

  15. Forecasting damaging earthquakes in the central and eastern United States.

    PubMed

    Nishenko, S P; Bollinger, G A

    1990-09-21

    Analysis of seismograph network data, earthquake catalogs from 1727 to 1982, and paleoseismic data for the central and eastern United States indicate that the Poisson probability of a damaging earthquake (magnitude >/= 6.0) occurring during the next 30 years is at a moderate to high level (0.4 to 0.6). When differences in seismic wave attenuation are taken into account, the central and eastern United States has approximately two-thirds the likelihood of California to produce an earthquake with comparable damage area and societal impact within the next 30 years.

  16. Characterization of eastern US spruce-fir soils. Book chapter

    SciTech Connect

    Fernandez, I.J.

    1992-01-01

    The spruce-fir forest of the eastern United States encompasses a diverse range of edaphic conditions due to differences in surficial geology, mineralogy, elevation, and climate. This chapter describes the characteristics of soils supporting eastern spruce-fir ecosystems, including soil properties that are important in understanding forest function and the consequences of atmospheric deposition to forested ecosystems. Chapter 1 describes the silvical characteristics of the spruce-fir forest. The Spruce-Fir Research Cooperative included six intensive study sites; five were high-elevation research sites located from western North Carolina to New Hampshire, with one low-elevation site in Maine. Information gained from research at these sites, and other relevant research from these regions, provides the basis for this description of eastern U. S. spruce-fir soils.

  17. Competent Counseling for Middle Eastern American Clients: Implications for Trainees

    ERIC Educational Resources Information Center

    Soheilian, Sepideh S.; Inman, Arpana G.

    2015-01-01

    The authors used a factorial multivariate analysis of variance (MANOVA) to determine whether counselor trainees' group differences on measures of multicultural competence, empathy, and multicultural counseling self-efficacy (CSE) when working with Middle Eastern American (MEA) clients were moderated by trainee race. Two hundred and fifty-six…

  18. The Prevalence of Extreme Middle Eastern Ideologies around the World

    ERIC Educational Resources Information Center

    Loza, Wagdy; Abd-El-Fatah, Youssef; Prinsloo, Johan; Hesselink-Louw, Anni; Seidler, Katie

    2011-01-01

    The Belief Diversity Scale (BDS) was administered to Australian, Canadian, Egyptian, and South African participants of different religious backgrounds. The BDS is a 33-item, six subscale instrument that is designed to quantitatively measure Middle Eastern extremist ideologies on risk areas that are reported in the literature. Results demonstrated…

  19. Military Spending in Eastern Europe,

    DTIC Science & Technology

    1987-05-01

    on defense (the sums are less than the corresponding expenditures by the republics) or whether they involve military spending above and beyond that...certain military expenditures on personnel are included in budgetary categories other than defense spending . Transportation of soldiers to their first... expenditures and forces and military spending decisions in Eastern Europe. iii L SUMMARY Although the Soviet Union is the most threatening potential

  20. Environmental gap analysis to prioritize conservation efforts in eastern Africa.

    PubMed

    van Breugel, Paulo; Kindt, Roeland; Barnekow Lillesø, Jens-Peter; van Breugel, Michiel

    2015-01-01

    Countries in eastern Africa have set aside significant proportions of their land for protection. But are these areas representative of the diverse range of species and habitats found in the region? And do conservation efforts include areas where the state of biodiversity is likely to deteriorate without further interventions? Various studies have addressed these questions at global and continental scales. However, meaningful conservation decisions are required at finer geographical scales. To operate more effectively at the national level, finer scale baseline data on species and on higher levels of biological organization such as the eco-regions are required, among other factors. Here we adopted a recently developed high-resolution potential natural vegetation (PNV) map for eastern Africa as a baseline to more effectively identify conservation priorities. We examined how well different potential natural vegetations (PNVs) are represented in the protected area (PA) network of eastern Africa and used a multivariate environmental similarity index to evaluate biases in PA versus PNV coverage. We additionally overlaid data of anthropogenic factors that potentially influence the natural vegetation to assess the level of threat to different PNVs. Our results indicate substantial differences in the conservation status of PNVs. In addition, particular PNVs in which biodiversity protection and ecological functions are at risk due to human influences are revealed. The data and approach presented here provide a step forward in developing more transparent and better informed translation from global priorities to regional or national implementation in eastern Africa, and are valid for other geographic regions.

  1. Environmental Gap Analysis to Prioritize Conservation Efforts in Eastern Africa

    PubMed Central

    van Breugel, Paulo; Kindt, Roeland; Lillesø, Jens-Peter Barnekow; van Breugel, Michiel

    2015-01-01

    Countries in eastern Africa have set aside significant proportions of their land for protection. But are these areas representative of the diverse range of species and habitats found in the region? And do conservation efforts include areas where the state of biodiversity is likely to deteriorate without further interventions? Various studies have addressed these questions at global and continental scales. However, meaningful conservation decisions are required at finer geographical scales. To operate more effectively at the national level, finer scale baseline data on species and on higher levels of biological organization such as the eco-regions are required, among other factors. Here we adopted a recently developed high-resolution potential natural vegetation (PNV) map for eastern Africa as a baseline to more effectively identify conservation priorities. We examined how well different potential natural vegetations (PNVs) are represented in the protected area (PA) network of eastern Africa and used a multivariate environmental similarity index to evaluate biases in PA versus PNV coverage. We additionally overlaid data of anthropogenic factors that potentially influence the natural vegetation to assess the level of threat to different PNVs. Our results indicate substantial differences in the conservation status of PNVs. In addition, particular PNVs in which biodiversity protection and ecological functions are at risk due to human influences are revealed. The data and approach presented here provide a step forward in developing more transparent and better informed translation from global priorities to regional or national implementation in eastern Africa, and are valid for other geographic regions. PMID:25855968

  2. Taxonomic revision of the moss salamander Nototriton barbouri (Schmidt (Caudata: Plethodontidae), with description of two new species from the Cordillera Nombre de Dios, Honduras.