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1

Alluvial Fan-lacustrine Sedimentation and its Tectonic Implications in the Cretaceous Athgarh Gondwana Basin, Orissa, India  

Microsoft Academic Search

The Athgarh Formation is the northernmost extension of the east coast Upper Gondwana sediments of Peninsular India. The formation of the present area is a clastic succession of 700 m thick and was built against an upland scarp along the north and northwestern boundary of the basin marked by an E-W-ENE-WSW boundary fault. A regular variation in the dominant facies

Banabehari Mishra; Krishna Lal Pandya; Wataru Maejima

2004-01-01

2

Geological and geophysical variations across the Talchir Gondwana basin - evidence for episodic reactivation of the North Orissa Boundary Fault, India  

NASA Astrophysics Data System (ADS)

The Talchir basin is a late Paleozoic-Mesozoic age Gondwana basin that trends NW-SE and is oriented perpendicular to the eastern cost of Peninsular India. The basin straddles the Proterozoic contact between granulites of the Eastern Ghats Mobile Belt (EGMB) and amphibolite facies rocks of the Rengali Province. At present, the northern part of the basin experiences periodic moderate seismicity by reactivation of faults located within the basin and to its north. The precise location of these faults and their relationship with pre-existing basement anisotropies remains uncertain. Geological studies to the north and south of the basin establish that the two terranes preserve early structural discrepancies, but were juxtaposed by a transpressional deformation along WNW-ESE trending Proterozoic shear zones, the southernmost of which defines the northern boundary of the Talchir basin. All total 300 gravity observations were conducted along transects that cut north to south across the basin. The Bouguer anomalies decrease systematically northwards from the EGMB, through the basin, into the Rengali Province, which is typical of suture zones along such terrane boundaries. The sharp rise in gravity across the northern and southern boundary of the basin suggests the presence of steep faults with a sharp density difference on both the sides, forming a characteristic graben structure. However, 2-D Bouguer gravity models depict distinct upper crustal structures to the north and south of the Talchir basin. This indicates that the northern fault boundary of the Talchir basin coincides with the Proterozoic suture zone. Recent seismicity also shows highest activity over the northern margin of the basin. It therefore appears that the area has been periodically reactivated from the Proterozoic time to the present, making it a seismically vulnerable zone for over 500 million years. (Keywords: Talchir basin, Rengali Province, Gravity, 2-D model, reactivation, seismicity)

Mandal, A.; Misra, S.; Mohanty, W. K.; Gupta, S.

2012-12-01

3

Pteridophytes from Lower Gondwana formations of the Ib River Coalfield, Orissa and their diversity and distribution in the Permian of India  

NASA Astrophysics Data System (ADS)

Recent extensive investigations carried out in the Ib River Coalfield, Mahanadi Master Basin, Orissa, identified numerous fossiliferous beds in the lower Gondwana deposits. Six exposures of the Barakar and lower Kamthi formations yielded diverse and abundant plant remains. The flora includes twenty-three genera representing nine groups viz., Lycopodiales, Equisetales, Sphenophyllales, Filicales, Cordaitales, Coniferales, Ginkgoales, Cycadales and Glossopteridales. Systematic descriptions of the pteridophyte taxa namely Cyclodendron (Lycopodiales), Schizoneura, Raniganjia, Bengalia, equisetaceous stems (Equisetales), Trizygia, Benlightfootia (Sphenophyllales), Neomariopteris, and Dichotomopteris (Filicales) are presented in this paper. Pteridophytic leaves comprising nine taxa viz., Cyclodendron leslii, Schizoneura gondwanensis, Raniganjia bengalensis, Bengalia raniganjensis, Trizygia speciosa, Benlightfootia indica, Neomariopteris hughesii, N. talchirensis, and Dichotomopteris sp. together with equisetaceous stems constitute about 7.88% (72 specimens) of the total plant assemblage collected from this coalfield. Among the pteridophytes, equisetaceous stems are most abundant (40.3%; 29 specimens) followed by Schizoneura gondwanensis (20.8%, 15 specimens) and Trizygia speciosa (13.9%, 10 specimens). A summary of the known diversity of pteridophytes in the Indian Permian as a whole is provided. Barakar Formation exposures have been assigned to a lower and upper series based on possession of different floristic assemblages. Pteridophytes do not occur in the lower series. On this basis the beds of Lajkura, Jurabaga collieries, Ratanpur Fireclay Quarry and the locality near Belpahar Railway Station with pteridophyte fossils are assigned to the upper Barakar Formation (late Artinskian). Based on assemblages containing different pteridophytes, beds exposed at Sitaram and Dungri Pahar are assigned to the lower Kamthi Formation (Lopingian). The floristic composition suggests a palaeoclimatic shift from temperate warm moist to warm dry conditions during the late Artinskian and warm and humid during Lopingian. The Permian pteridophytes grew in semi-aquatic conditions, i.e. in marshy places around small ponds, lakes and river-banks.

Goswami, Shreerup; Jeet Singh, Kamal; Chandra, Shaila

2006-12-01

4

Plant biodiversity in the Mahanadi Basin, India, during the Gondwana period  

NASA Astrophysics Data System (ADS)

The Mahanadi Basin is one of five major sedimentary basins of Peninsular India and is situated on the east coast. The sediments are exposed in two different regions: an extensive basin comprising Lower to Upper Gondwana with coal measures towards the west (Talchir and lb-River Sub-basins); and the Athgarh Sub-basin in the east with rocks of only Upper Gondwana age. This study is mainly concerned with plant species diversification and the development of flora in the Mahanadi Basin from the Early Permian to the Early Cretaceous. A number of successive megafloras are recognised with gaps in the sequence. A few animal records are also considered in order to examine biodiversity in the basin. Leaves are the dominant part of the preserved flora, followed by fruits. No stem or wood parts are preserved and the root parts are represented by the form genus Vertebraria. Pre-angiosperm fossil floras at species level are plotted systematically in Table 2 to examine the plant diversity through different geological formations in the Mahanadi Basin. Maximum plant diversification in gymnosperms is recorded in the Late Permian (Kamthi Formation), and in pteridophytes in the Early Cretaceous (Athgarh Formation).

Singh, K. J.

2000-07-01

5

Facies characteristics of Talchir Formation, Jharia Basin, India: Implications for initiation of Gondwana sedimentation  

NASA Astrophysics Data System (ADS)

A long phase of nondeposition that prevailed in peninsular India since the Late Proterozoic came into an end with the onset of Gondwana sedimentation. The Talchir Formation, the lowest unit of Gondwana Supergroup, deserves special attention for understanding the Late Paleozoic geological history in this part of the globe. Signatures of three major events have been identified in the Talchir Formation in different Gondwana basins of India: (1) intracratonic rifting, (2) Permo-Carboniferous glaciation and (3) marine incursion. But a unique model to explain the specific relation between these events is yet to be formulated. The present study reveals that the Talchir succession of Jharia Basin of eastern India bears certain evidences, which may lead to a possible solution to this problem. The lower part of the succession is represented by a glacigenic conglomerate, which underwent brecciation possibly due to hydraulic fracturing during deglaciation. Facies analysis leads to the conclusion that a thick fan deposit, presumably produced through resedimentation of preexisting unconsolidated glacial sediments, represents the rest of the Talchir succession. The presence of fragments of brecciated conglomerate within this fan deposit confirms a significant break in the sedimentation history. Three fining upward cycles can be identified within the proximal part of the fan succession. The lower and the middle cycles bear the signature of emplacement of subaqueous high-density flows and variations in facies pattern developed through progressive flow transformation. The upper cycle, however, is represented by sheet-flood and stream-flow deposits. Products of dominantly suspension fall-out over a vast area, with periodic influx of coarser material, constitute the distal fan deposit. The fan succession is unconformably overlain by a fluvial succession, which, in turn, interfingers with the fluviolacustrine deposits of the younger Barakar Formation derived from the opposite side of the basin. This indicates asymmetric pattern of basin-filling as expected in a continental extensional setting. The overall character of this succession indicates that: (1) emplacement of the intracratonic rift system was a post-glaciation event, (2) initial phase of deposition was dominated by resedimentation of the preexisting glacial debris, and (3) marine incursion probably followed deglaciation and persisted for a short time until isostatic equilibrium was attained before the rift system came into existence.

Dasgupta, Prabir

2006-03-01

6

Palynostratigraphy and age correlation of subsurface strata within the sub-basins in Singrauli Gondwana Basin, India  

NASA Astrophysics Data System (ADS)

In the study area, changes in the facies of sediments and spores-pollen content appear to be all causally linked with the depositional set-up. Here, the qualitative and quantitative changes observed in the spores-pollen assemblages have led to recognize 10 Assemblage-zones representing from that earliest Permian in the Talchir Formation to that latest Late Triassic in the Parsora Formation. These spores-pollen assemblages are obtained from the wider parts in the Singrauli Gondwana Basin that includes (i) Moher sub-basin (boreholes SSM-1 and 2), and (ii) Singrauli main sub-basin (boreholes SMJS-2, 3 and SMBS-1). The progressively changing spores-pollen content infer the hiatuses of varied magnitude in the sedimentary sequences during the extended time interval of Permian and Triassic.

Vijaya; Tripathi, Archana; Roy, A.; Mitra, Saibal

2012-08-01

7

Palynomorphs of Permian Gondwana coal from borehole GDH-38, Barapukuria Coal Basin, Bangladesh  

NASA Astrophysics Data System (ADS)

Thirty-two core samples of Permian Gondwana coal from three coal beds of borehole GDH-38, Barapukuria Coal Basin, Dinajpur, the north-northwestern part of Bangladesh, have been collected for palynological analysis. All samples except one yielded palynomorphs and some samples contain well-preserved and abundant palynomorphs of the gymnospermal and cryptogamic groups that are considered to be useful for future correlation studies. The lower coal bed (331.6-372.5 m) can easily be differentiated from the upper two coal beds by the presence of Alisporites, Cordaitina, Corisaccites, Hamiapollenites, Leuckisporites, Nuskoisporites, Tumoripollenites, Vestgisporites and Vittatina. It is difficult to palynologically differentiate the middle (198.1-208 m) and upper (162.3-172.9 m) coal beds as they contain a very limited number of specimens by which they can be identified. The middle bed is distinguished by the presence of Microbaculispora and Weylandites and the upper bed by the presence of a single taxon Acanthotriletes. Some of the vesiculate or saccate taxa extracted from these coal beds are typical of those occurring in Permian strata of Gondwana in India, South Africa, South America, Russia, Australia and Antarctica. They are thought to be derived from Glossopteris flora, which is characterised by an abundance of Pteridospermic plants of the gymnosperm group.

Akhtar, A.; Kosanke, R. M.

2000-07-01

8

Permo-Carboniferous proglacial-lake sedimentation in the Sahajuri Gondwana basin, India  

NASA Astrophysics Data System (ADS)

The study of lithological associations, sedimentary structures and their interrelation suggests that the Talchir rocks of the Sahajuri Gondwana basin were deposited in a proglacial lake. The lowermost lithological association of diamictites and chaotic boulder beds deposited mainly as sediment gravity flows, represent a transitional phase between terminoglacial and proglacial sub-environments. The coarsening-upward sequence, coarse steeply dipping sandstone and fining-upward sequence together represent bottomset, foreset and topset, respectively, of a Gilbert-type delta. The delta progradation to the southwest was mainly controlled by decaying of buried ice in the lake floor and consequent enlargement of the lake. The diamictites were emplaced mainly as debris flow and the chaotic boulder bed by downslope slumping.

Sen, D. P.; Banerji, Tapas

1991-04-01

9

Permian plate margin volcanism and tuffs in adjacent basins of west Gondwana: Age constraints and common characteristics  

NASA Astrophysics Data System (ADS)

Increasing evidence of Permian volcanic activity along the South American portion of the Gondwana proto-Pacific margin has directed attention to its potential presence in the stratigraphic record of adjacent basins. In recent years, tuffaceous horizons have been identified in late Early Permian-through Middle Permian (280-260 Ma) sections of the Paraná Basin (Brazil, Paraguay, and Uruguay). Farther south and closer to the magmatic tract developed along the continental margin, in the San Rafael and Sauce Grande basins of Argentina, tuffs are present in the Early to Middle Permian section. This tuff-rich interval can be correlated with the appearance of widespread tuffs in the Karoo Basin. Although magmatic activity along the proto-Pacific plate margin was continuous during the Late Paleozoic, Choiyoi silicic volcanism along the Andean Cordillera and its equivalent in Patagonia peaked between the late Early Permian and Middle Permian, when extensive rhyolitic ignimbrites and consanguineous airborne tuffaceous material erupted in the northern Patagonian region. The San Rafael orogenic phase (SROP) interrupted sedimentation along the southwestern segment of the Gondwana margin (i.e., Frontal Cordillera, San Rafael Basin), induced cratonward thrusting (i.e., Ventana and Cape foldbelts), and triggered accelerated subsidence in the adjacent basins (Sauce Grande and Karoo) located inboard of the deformation front. This accelerated subsidence favored the preservation of tuffaceous horizons in the syntectonic successions. The age constraints and similarities in composition between the volcanics along the continental margin and the tuffaceous horizons in the San Rafael, Sauce Grande, Paraná, and Karoo basins strongly suggest a genetic linkage between the two episodes. Radiometric ages from tuffs in the San Rafael, Paraná, and Karoo basins indicate an intensely tuffaceous interval between 280 and 260 Ma.

López-Gamundí, Oscar

2006-12-01

10

The breakup of East Gondwana: Assimilating constraints from Cretaceous ocean basins around India into a best-fit tectonic model  

NASA Astrophysics Data System (ADS)

models for the Cretaceous seafloor-spreading history of East Gondwana result in unlikely tectonic scenarios for at least one of the plate boundaries involved and/or violate particular constraints from at least one of the associated ocean basins. We link East Gondwana spreading corridors by integrating magnetic and gravity anomaly data from the Enderby Basin off East Antarctica within a regional plate kinematic framework to identify a conjugate series of east-west-trending magnetic anomalies, M4 to M0 (~126.7-120.4 Ma). The mid-ocean ridge that separated Greater India from Australia-Antarctica propagated from north to south, starting at ~136 Ma northwest of Australia, and reached the southern tip of India at ~126 Ma. Seafloor spreading in the Enderby Basin was abandoned at ~115 Ma, when a ridge jump transferred the Elan Bank and South Kerguelen Plateau to the Antarctic plate. Our revised plate kinematic model helps resolve the problem of successive two-way strike-slip motion between Madagascar and India seen in many previously published reconstructions and also suggests that seafloor spreading between them progressed from south to north from 94 to 84 Ma. This timing is essential for tectonic flow lines to match the curved fracture zones of the Wharton and Enderby basins, as Greater India gradually began to unzip from Madagascar from ~100 Ma. In our model, the 85-East Ridge and Kerguelen Fracture Zone formed as conjugate flanks of a "leaky" transform fault following the ~100 Ma spreading reorganization. Our model also identifies the Afanasy Nikitin Seamounts as products of the Conrad Rise hotspot.

Gibbons, Ana D.; Whittaker, Joanne M.; Müller, R. Dietmar

2013-03-01

11

Cyclic development of sedimentary basins at convergent plate margins — 1. Structural and tectono-thermal evolution of some gondwana basins of eastern Australia  

NASA Astrophysics Data System (ADS)

The Devono-Carboniferous Drummond Basin of eastern Australia formed by extensional tectonics, most probably in a back-arc setting, as an oceanic plate subducted westward under Gondwana's continental margin. Within this basin a syn-rift sequence and a relatively thick post-rift sequence are recognized, and the latter is separated from the overlying Galilee Basin by a mid-Carboniferous unconformity, which heralds a time of relatively mild compression, uplift and folding. The lower Galilee Basin formed as a foreland, secondary peripheral bulge, or mixed-style basin during the Late Carboniferous to Early Permian time interval. A mid-Permian unconformity separates it from the extensive Late Permian to Mid-Triassic upper Galilee Basin, here suggested to be a platform basin. Nest, the main, Mid- to Late Triassic compressional event led to reverse movement along previously normal faults, folding, uplift and erosion of up to 2 km of section from the Galilee and Bowen basins. During Jurassic and Cretaceous times, the Eromanga/Surat/Carpentaria Basin, a platform basin originally >1.7 million km 2 in extent, developed cratonward of the zone of continuing subduction. Subsequently, the culminating extensional event took place further east, where Lord Howe Rise rifted apart from the continental landmass and drifted eastward as oceanic seafloor spread in the Tasman Basin, and widespread uplift and erosion occurred over the eastern Australian coastal area. New data, re-interpretation of existing data and extensive literature support the interpretation of the Phanerozoic tectonic evolution of eastern Australia in a context of convergent plate margins. Within this context, overall eastward migration through time of the subduction zone and associated morphotectonic entities (e.g. the Warburton, Adavale, Drummond, Bowen and Tasman extensional basins) and vertical stacking of unconformity-bound extensional, foreland and platform basins (e.g. the Drummond, Galilee and Eromanga basins) occurred.

de Caritat, Patrice; Braun, Jean

1992-12-01

12

Glacial and proglacial Talchir sedimentation in Son-Mahanadi Gondwana basin: Paleogeographic reconstruction  

NASA Astrophysics Data System (ADS)

In the southern part of the Son-Mahanadi basin, the early Permian glacigene Talchir rocks occur in exhumed glacial valleys overlying the Precambrian basement unconformably with gentle to somewhat steeper contacts. In the broader low lying part to the north, the strata are flat lying and uninterrupted by granitic inliers. The overall sequence thickens progressively lengthwise from south (400 m) to north (800 m) and from the margins of the basin inward. Two distinct groups of facies characterize the Talchir assemblage. The first group, the proximal facies, occurs in exhumed valleys near the granitic highlands and includes diamictite, conglomerate, and sandstone. The second group, distal facies, occurs away from the highlands in the broader, northern region and abounds in fine elastics. This group includes shale and rhythmites containing dropstones. Paleocurrent analysis suggests that the ice movement and paleoflow of meltwater streams were directed locally inward and regionally along the length of the basin from southeast to northwest. The occurrence of marine fauna at Manendragarh and Umaria is the only evidence of marine ingression along the northwestern margin. However, there is no conclusive evidence of marine transgression to the south of Manendragarh. The present study suggests a somewhat plateau-like upland topography in the southern part of the Mahanadi basin, with a dissected northern edge passing into an extensive low-lying Son basin farther north. The entire southern terrain was characterized by the exhumed valleys dominated by glacial, glaciofluvial, and glaciolacustrine environments, whereas the low lying northern terrain represented deltaic milieu in the central part and tidal estuary setting along the margins of the basin in the northwest. The paper reconstructs the paleogeography of the Son-Mahanadi basin during early Permian time.

Casshyap, S. M.; Srivastava, V. K.

13

Lower Cretaceous anoxic conditions IN the Austral basin, south-western Gondwana, Patagonia Argentina  

NASA Astrophysics Data System (ADS)

The reconstruction of palaeo-oxygenation levels in marine deposits from the Cretaceous has obtained a huge interest all around the world in recent years. This fascinating topic is here pointed out for the first time in the Austral Basin using the information provided by the black shales of the Río Mayer Formation, Patagonia, Argentina. The combination of sedimentology, ichnology and geochemistry (TOC, Ce anomaly and MnO content) allow the identification of three major intervals respecting the oxygen content. During the Berriasian and early Valanginian anoxic conditions prevail in the outer shelf. After that, between the late Valanginian and Hauterivian dysoxic palaeoenvironments were developed. Finally, a more oxygenated palaeoenvironment occurred since Aptian associated with a progradation of a proximal deltaic system. The identification of anoxic conditions is of much interest for the hydrocarbon research in this stratigraphical unit, which represents the most significant source rock of the Austral Basin.

Richiano, Sebastián

2014-10-01

14

Gondwana Animation  

NSDL National Science Digital Library

This animation is one result of a determined effort to use new information to better constrain the history of continental dispersal and create a more accurate geological map of reassembled Gondwana. All the continental movements are shown relative to a number of hotspots, the position of which is held fixed with respect to the earth's rotation axis. This gives results that agree overall with paleomagnetic and paleoclimatic information for the period. The site also provides a slide show presentation about historical events that formed the Indian Ocean.

15

The Early Palaeozoic break-up of northern Gondwana, new palaeomagnetic and geochronological data from the Saxothuringian Basin, Germany  

Microsoft Academic Search

Early Palaeozoic volcanic and sedimentary rocks from the Saxothuringian Basin (Franconian Forest, northern Bavaria) have been subjected to detailed radiometric and palaeomagnetic studies in order to determine the tectonic environment and geographic setting in which they were deposited. Two hand samples were collected from the as yet undated pyroclastic flow deposits for 207Pb\\/206Pb age dating. Radiometric results for these samples,

M. Schätz; T. Reischmann; J. Tait; V. Bachtadse; H. Bahlburg; U. Martin

2002-01-01

16

New glacial evidences at the Talacasto paleofjord (Paganzo basin, W-Argentina) and its implications for the paleogeography of the Gondwana margin  

NASA Astrophysics Data System (ADS)

The Talacasto paleovalley is situated in the Central Precordillera of San Juan, Argentina, where upper Carboniferous-Permian rocks (Paganzo Group) rest on Devonian sandstones of the Punta Negra Formation. This outcrop is an excellent example of a glacial valley-fill sequence that records at least two high-frequency cycles of the advance and retreat of a glacier into the valley. The paleocurrent analysis shows transport predominantly to the south, indicating that at this site the ice flow differs from the other nearby paleovalleys. Evidence of the glacial origin of this valley can be seen in the glacial striae on the valley's sides, as well as the U-shape of the valley, indicated by very steep locally overhanging valley walls. Deglaciation is indicated by a set of retransported conglomerates deposited in a shallow-water environment followed by a transgressive succession, which suggests eustatic rise due to meltwater input to the paleofjord. The complete sedimentary succession records distinct stages in the evolution of the valley-fill, represented by seven stratigraphical units. These units are identified based on facies associations and their interpreted depositional setting. Units 1 to 5 show one cycle of deglaciation and unit 6 marks the beginning of a new cycle of glacier advance which is characterized by different types of glacial deposits. All units show evidence of glacial influence such as dropstones and striated clasts, which indicates that the glaciers were always present in the valley or in adjacent areas during sedimentation. The Talacasto paleofjord provides good evidence of the Late Paleozoic Gondwana glaciation in western Argentina and examples of sedimentary successions which have been interpreted as being deposited by a confined wet-based glacier in advance and retreat cycles, with eventual release of icebergs into the basin. The outcrop is also a key for reconstructing the local glacial paleogeography, and it suggests a new interpretation that is not in agreement with previous studies. Finally, the importance of the Talacasto paleovalley for the Paganzo basin lies in its orientation, because it allows the reconstruction of the ice paleoflow and indication, for the first time, that marine ingressions into this area were not taking place along the Jachal trough, as expected, but along a different connection to the sea, which for this work we will call the San Juan Paleotrough.

Aquino, Carolina Danielski; Milana, Juan Pablo; Faccini, Ubiratan Ferrucio

2014-12-01

17

A Late Jurassic fossil assemblage in Gondwana: Biostratigraphy and correlations of the Tacuarembó Formation, Parana Basin, Uruguay  

NASA Astrophysics Data System (ADS)

The Tacuarembó Formation has yielded a fossil assemblage that includes the best known body fossils, consisting of isolated scales, teeth, spines, and molds of bones, recovered from thin and patchy bonebeds, from the Botucatu Desert, Parana Basin, South America. The remains are preserved in the sandstones widespread around the city of Tacuarembó. We propose a new formalized nomenclature for the Tacuarembó Formation, naming its "Lower" and "Upper" members as the Batoví (new name) and Rivera (new rank) members, respectively. An assemblage zone is defined for the Batoví Member (fluviolacustrine and aeolian deposits). In this unit, the freshwater hybodontid shark Priohybodusarambourgi D'Erasmo is well represented. This species was previously recorded in Late Jurassic-Early Cretaceous units of the Sahara and the southern Arabian Peninsula. Globally considered, the fossil assemblage of this member ( P. arambourgi, dipnoan fishes, Ceratosaurus-like theropods, and conchostracans) is indicative of a Kimmeridgian-Tithonian age, which in combination with the stratigraphic relationships of the Tacuarembó Formation with the overlying basalts of the Arapey Formation (132 My average absolute age) implies that the latter was deposited during the Kimmeridgian-Hauterivian interval.

Perea, Daniel; Soto, Matías; Veroslavsky, Gerardo; Martínez, Sergio; Ubilla, Martín

2009-08-01

18

Permian phytogeography in Gondwana  

Microsoft Academic Search

Phytogeographic patterns based on multivariate techniques (Multidimensional Scaling) are proposed for the Permian vegetation of Gondwana. This approach requires a data set with broad geographic coverage based on generic composition and with good time control. In general, strong phytogeographic differentiation can be observed throughout the Permian. In order to identify short term phytogeographic patterns, the Permian period was informally divided

N. Rubén Cúneo

1996-01-01

19

Gondwana sedimentation in the Pranhita Godavari Valley: a review  

NASA Astrophysics Data System (ADS)

The post-Talchir Gondwana sequence in the central Godavari Valley consists of bands of arenaceous and argillaceous sediments of mainly fluvial origin. Limestones occur only rarely. Profusely cross-bedded, shoestring sand bodies represent point-bar deposits of the ancient Gondwana river. Thinly laminated, argillaceous, flood plain deposits interfinger with the point-bar sands. Possible dimensions of the Gondwana streams have been estimated from thicknesses of the cross-beddings. The flow velocities in the Gondwana River ranged between 0.4 and 0.7 m/s. Textural and geochemical evidence suggests marine influence during Kundaram (Permian) sedimentation, at least locally. Lacustrine sedimentation is inferred for the Early Jurassic Kota Limestone. In the coastal areas, marginal marine inundation occurred during Gollapilli (Cretaceous) sedimentation. The continental environment reappeared soon after. The petrology of the Gondwana sandstones indicates derivation from the low-grade Precambrian metamorphic rocks at the southern fringe of the Gondwana basin. This conclusion is supported by a consistently northerly palaeocurrent direction within the Gondwana rocks. A reversal of the palaeoslope during the Late Jurassic or Early Cretaceous is inferred. Sudden uplift of the source area together with quick burial of sediments is indicated by the presence of fresh feldspars in some formations. Periodic monsoonal conditions of deposition in an otherwise dry climate prevailed. Deposition was uninterrupted between Talchir and Gangapur sedimentation. Shifting river channels caused repetition of the channel and interchannel facies both in time and space. The six major 'groups' recognized by King [Geol. Surv. India Mem. 18 (1881) 151] within the Gondwana of the Godavari Valley have been reclassified by subsequent workers into a larger number of 'formations', following the criteria laid down in the Stratigraphic Code. Correlation between these formations has not always been easy. The technique of Sequence Stratigraphy, which recommends correlation by genetic criteria, might help resolve some of the confusion.

Sengupta, Supriya

2003-03-01

20

Gondwana to Asia: Preface  

NASA Astrophysics Data System (ADS)

The Korean Peninsula, China, Japan, India, Sri Lanka, and Timor, among other regions, preserve important clues for the tectonic evolution of present-day Asia derived from the break-up of Mesozoic supercontinent Pangea. Evidence for the formation, evolution, and destruction of Earth's first coherent supercontinent Columbia during Paleoproterozoic, followed by the Neoproterozoic Rodinia and late Neoproterozoic-Cambrian Gondwana supercontinents are also recorded in many of these regions. The debates surrounding some of these aspects and the state-of-the-art knowledge from these terranes were the focal themes of discussion during the "2013 Annual Convention of the International Association for Gondwana Research (IAGR) and the 10th Gondwana to Asia International Conference" held at the Korea Institute of Geoscience and Mineral Resources (KIGAM), Korea during September 30th to October 2nd 2013. The conference was attended by more than 200 delegates representing 11 countries. The discussion continued at the "International conference on Continental Dynamics" held in Xian, China during April 2014. This special issue of Journal of Asian Earth Sciences, assembling 24 research papers is an outcome of the deliberations under various sessions of the above conferences. In assembling this special issue, we attempt to provide evidence-driven discussions on the construction and destruction of Precambrian and Paleozoic supercontinents preserved in present-day Asian continents. We also address a variety of themes including magmatic, metamorphic and metallogenic processes, as well as issues related to natural environment. We hope that the papers assembled in this special issue offer new insights into some of the key issues surrounding the geological, geophysical and geodynamic milieu in Asia, and a better understanding of analogous processes in other parts of the world.

Kwon, Sanghoon; Kim, Sung Won; Santosh, M.

2014-12-01

21

Improved Moscovian part of the Gondwana APWP for paleocontinental reconstructions, obtained from a first paleomagnetic pole, age-constrained by a fold test, from In Ezzane area in the Murzuq basin (Algeria, stable Africa)  

NASA Astrophysics Data System (ADS)

To improve paleocontinental reconstructions, paleomagnetic reference curves (Apparent Polar Wander Path: APWP) feature for large continents have to be continuously refined by adding up new high-quality data. For stable Africa, the Moscovian period was favorable for such aim, with well-dated and widespread geological formations. A new study has been conducted in the Upper “Dembaba” geological formation of Lower Moscovian age outcropping in the western part of the “Murzuq” basin (Saharan platform). Well-defined ChRMs, combined with remagnetization circles data, both constrained in age by a positive fold test, yield a new significant paleomagnetic pole (? = 25.2°S, ? = 59.9°E, K = 55, A95 = 5.4°). When joined with previous African data of the same age, it gives an improved reference pole for Africa (? = 28.9°S, ? = 54.5°E, K = 106, A95 = 3.6°). The Mean Moscovian paleomagnetic pole determined from an updated Gondwana Paleozoic APWP (? = 29.4°S, ? = 51.5°E, K = 11, A95 = 1.8°), associated with the corresponding Laurussia pole (Domeier et al., 2012), yields a more constrained paleocontinental reconstruction for 310 Ma.

Amenna, M.; Derder, M. E. M.; Henry, B.; Bayou, B.; Maouche, S.; Bouabdallah, H.; Ouabadi, A.; Ayache, M.; Beddiaf, M.

2014-11-01

22

Heartbeat of a mountain: diagnosing the age of depositional events in the Karoo (Gondwana) Basin from the pulse of the Cape Orogen  

NASA Astrophysics Data System (ADS)

Careful consideration of the effects of the Cape orogeny on sedimentation in the Carboniferous-Jurassic Karoo Basin provides an indirect tool for accurately dating these rocks. Fossil and radiometric data, especially when combined with sedimentological and structural information, yield partly overlapping age brackets which can be used to correlate the successive tectonic pulses with specific depositional events. Application of these principles to associated basins in Gondwanaland can provide a firm foundation for more dependable stratigraphic correlation on a global scale. The exercise also suggests that a number of widely held opinions on the age of certain stratigraphic units in the Karoo Supergroup may be incorrect.

Le Roux, J. P.

1995-09-01

23

PLANT CONSERVATION IN TEMPLE YARDS OF ORISSA  

PubMed Central

This paper is a brief survey of the role of temples and holy places in nurturing the surrounding flora and its habitat. Eightysix kinds of plants in temple yards and gardens of orissa have been enlisted where they are cultivated and preserved for different temple rituals. These plants are seen rarely in wild but are saved from extinction by their association with temple rituals and ceremonies. PMID:22556826

Mohanty, R.B; Mohapatra, B.K; Padhy, S.N

1997-01-01

24

Women and Community Forests in Orissa: Rights and Management  

Microsoft Academic Search

In Orissa a large number of villages have been protecting and managing state forests lands as a common resource through elaborate community arrangements. Rural communities involved in forest management have also been demanding secure rights over these forests. Vasundhara and Sanhati, an alliance of NGOs in Orissa, recently facilitated a broad-based consultation process with village people and NGOs on the

Neera M. Singh

2001-01-01

25

Continental break up and the distribution of fishes of Western Gondwana during the Early Cretaceous  

Microsoft Academic Search

Many Early Cretaceous fishes were endemic to western Gondwana, making their fossils potentially useful tools in biogeographic reconstruction. These occur in a variety of tectonic settings; for example, in rift basins of the East Brazilian Rift System (EBRIS) and corresponding sites in western Africa, in non-rift basins within the EBRIS region, and in interior localities far removed from this area

John G. Maisey

2000-01-01

26

A model of plate kinematics in Gondwana breakup  

NASA Astrophysics Data System (ADS)

An accurate model of relative plate motions in Gondwana breakup is based on visual fitting of seafloor isochrons and fracture zones (FZ) from the Riiser-Larsen Sea and Mozambique Basin. Used predictively, the model precisely locates kinematic markers in the West Somali Basin, which allows the conclusion that the spreading centres in the West Somali and Mozambique basins and the Riiser-Larsen Sea formed parts of the boundary between the same two plates. The locations of FZ and less well-defined isochrons from neighbouring regions are also consistent with their formation on other lengths of this same boundary and with its relocation from the West Somali Basin and northern Natal Valley to the West Enderby Basin and Lazarev Sea during chron M10n. Small independently moving plates thus played no role in the breakup of this core part of Gondwana. In an inversion procedure, the data from these areas yield more precise finite rotations that describe the history of the two plates' separation. Breakup is most simply interpreted to have occurred in coincidence with Karoo volcanism, and a reconstruction based on the rotations shows the Lebombo and Mateke-Sabi monoclines and the Mozambique and Astrid ridges as two sets of conjugate volcanic margins. Madagascar's pre-drift position can be used as a constraint to reassess the positions of India and Sri Lanka in the supercontinent.

Eagles, Graeme; König, Matthias

2008-05-01

27

An introduction to abhinava chintamani an ayurveda treatise from orissa.  

PubMed

A synopsis of the Sanskrit text, Abhinava Chintamani is presented in this paper. Attention is paid to highlight the novel features of this text composed in 18(th) Century A. D. by Mahamati Cakrapani Das of Orissa. PMID:22556512

Kishore, P; Dash, S; Nanda, M C

1990-07-01

28

SOME LESS KNOWN FOLK CLAIMS FROM CANDAKA TRIBALS OF ORISSA  

PubMed Central

The present communication deals with a detailed account of usage of 40 species of plants in various ailments by the tribal people of chandaka forest area adjoining bhubaneswar, orissa. The author opines the importance of folk-lore claims in source of drugs trough this article. PMID:22556876

Prusti, Arati Bala

1998-01-01

29

Late Ordovician volcanism in Korea constrains the timing for breakup of Sino-Korean Craton from Gondwana  

NASA Astrophysics Data System (ADS)

In the early Paleozoic the Sino-Korean Craton (SKC) and South China Craton (SCC) were situated along the margin of east Gondwana. The SKC was connected to core Gondwana by an epeiric sea which was the site for deposition of lower Paleozoic sequences of SKC. The SKC and SCC may have drifted away from core Gondwana sometime during the mid-Paleozoic and would have been outboard microcontinents in the late Paleozoic, until they collided to form the East Asian continent in the Triassic. The breakup of SCC from Gondwana was suggested to have taken place at ?380 Ma, while no reliable suggestions have hitherto been made for breakup of SKC from Gondwana. This study presents a convincing evidence for breakup of SKC from Gondwana, based on the recognition of Late Ordovician volcanism in Korea. New SHRIMP U-Pb zircon ages, 445.0 ± 3.7 Ma and 452.5 ± 3.2 Ma, are obtained from trachytic rocks of the Ongnyeobong Formation of Taebaeksan Basin in Korea which occupied the marginal part of the SKC in the early Paleozoic. This Late Ordovician volcanism along with previous records of Ordovician volcanic activities along the western margin of the SKC is interpreted indicating the development of an incipient oceanic ridge. The oceanic ridge uplifted the SKC including the epeiric sea, which subsequently resulted in terminating the early Paleozoic sedimentation of the epeiric sea. The paucity of lower Paleozoic volcanic rocks across much of the SKC however suggests that the oceanic ridge did not extend into the epeiric sea. Instead, spreading of oceanic ridge entailed dextral movement of associated transform faults, which may have played a major role in breakup of SKC from mainland Gondwana by the end of Ordovician.

Cho, Deung-Lyong; Lee, Seung Ryeol; Koh, Hee Jae; Park, Jun-Beom; Armstrong, Richard; Choi, Duck K.

2014-12-01

30

Gondwana dispersion and Asian accretion: Tectonic and palaeogeographic evolution of eastern Tethys  

NASA Astrophysics Data System (ADS)

Present-day Asia comprises a heterogeneous collage of continental blocks, derived from the Indian-west Australian margin of eastern Gondwana, and subduction related volcanic arcs assembled by the closure of multiple Tethyan and back-arc ocean basins now represented by suture zones containing ophiolites, accretionary complexes and remnants of ocean island arcs. The Phanerozoic evolution of the region is the result of more than 400 million years of continental dispersion from Gondwana and plate tectonic convergence, collision and accretion. This involved successive dispersion of continental blocks, the northwards translation of these, and their amalgamation and accretion to form present-day Asia. Separation and northwards migration of the various continental terranes/blocks from Gondwana occurred in three phases linked with the successive opening and closure of three intervening Tethyan oceans, the Palaeo-Tethys (Devonian-Triassic), Meso-Tethys (late Early Permian-Late Cretaceous) and Ceno-Tethys (Late Triassic-Late Cretaceous). The first group of continental blocks dispersed from Gondwana in the Devonian, opening the Palaeo-Tethys behind them, and included the North China, Tarim, South China and Indochina blocks (including West Sumatra and West Burma). Remnants of the main Palaeo-Tethys ocean are now preserved within the Longmu Co-Shuanghu, Changning-Menglian, Chiang Mai/Inthanon and Bentong-Raub Suture Zones. During northwards subduction of the Palaeo-Tethys, the Sukhothai Arc was constructed on the margin of South China-Indochina and separated from those terranes by a short-lived back-arc basin now represented by the Jinghong, Nan-Uttaradit and Sra Kaeo Sutures. Concurrently, a second continental sliver or collage of blocks (Cimmerian continent) rifted and separated from northern Gondwana and the Meso-Tethys opened in the late Early Permian between these separating blocks and Gondwana. The eastern Cimmerian continent, including the South Qiangtang block and Sibumasu Terrane (including the Baoshan and Tengchong blocks of Yunnan) collided with the Sukhothai Arc and South China/Indochina in the Triassic, closing the Palaeo-Tethys. A third collage of continental blocks, including the Lhasa block, South West Borneo and East Java-West Sulawesi (now identified as the missing "Banda" and "Argoland" blocks) separated from NW Australia in the Late Triassic-Late Jurassic by opening of the Ceno-Tethys and accreted to SE Sundaland by subduction of the Meso-Tethys in the Cretaceous.

Metcalfe, I.

2013-04-01

31

Geophysical evidence for a causative process for fragmentation in western Gondwana  

SciTech Connect

The existence and subsequent fragmentation of the Gondwana supercontinent are well established in the geological literature. Debate continues, however, on the exact prefragmentation geometry and the causative process of breakup. The easter Walvis Ridge and the Agulhas and the Mozambique plateaus, which surround southern Africa, exhibit geophysically anomalous oceanic crust and lithosphere. In the vicinity of these aseismic bathymetry highs, the crust is considerably thicker than normal, and the uppermost mantle has lower than normal densities and seismic velocities. Within a Gondwana framework, these anomalies coincide with a highly fragmented region at the triple junction of the three major plates (Africa, South America, and Antarctica). This anomalous oceanic crust and lithosphere, the ubiquitous and contemporaneous magmatism, and the basin and range-type tectonism of the region are consonant with a hot-mantle-upflow tectonic framework as the causative process for fragmentation.

Antoine, L.A.G.; Moyes, A.B. (Univ. of Witwatersrand, Johannesburg (South Africa))

1992-07-01

32

Promoting Gondwana: presentation of the Gondwana Rainforests of Australia World Heritage Area in tourist brochures  

Microsoft Academic Search

An 800 km stretch of the Eastern coast of Australia contains some of the last remnant fragments of the sub-tropical rainforests that once covered much of the region. This natural resource – declared as World Heritage in 1986 as the Central Eastern Rainforest Reserves of Australia, but now known as the Gondwana Rainforests of Australia – serves as an important drawcard

Erica Wilson; Kerrie Stimpson; David Lloyd; William E. Boyd

2011-01-01

33

Mantle processes during Gondwana break-up and dispersal  

Microsoft Academic Search

This paper reviews the Mesozoic continental flood basalts (CFBs) associated with the break-up and dispersal of Gondwana from 185-60 Ma, the conditions for melt generation in mantle plumes and within the continental mantle lithosphere, and possible causes for lithospheric extension. The number of CFB provinces within Gondwana is much less than the number of mantle plumes that are likely to

Chris Hawkesworth; Simon Kelley; Simon Turner; Anton Le Roex; Bryan Storey

1999-01-01

34

Gondwana's climate history inferred from the palynological record of South Africa's coal deposits: the Early Triassic wet intermezzo  

NASA Astrophysics Data System (ADS)

Permian-Triassic coals of the South African Karoo Basin play a central role in the study and interpretation of Gondwana's climate history and related vegetational changes in time and space. The palynological record of the coal-bearing formations reveals major phases of climate amelioration succeeding the Permo-Carboniferous Gondwana glaciations. Subsequent to the melting of the Dwyka ice, cold to cool-temperate climate conditions prevailed during the Early Permian and a continuous change to hot and dry climate conditions of the Late Permian and Triassic was inferred from sedimentological and palaeontological data so far. The here presented new palynological and geochemical data from the Early Triassic Molteno coal (Stormberg Group) point to a short-term switch from dry to wet climate conditions. To date, this wet intermezzo of Gondwana's early Mesozoic climate history has been overlooked in the Molteno coal of the Karoo Basin. The spore/pollen ratios, used as a proxy for humidity changes, indicate a significant climatic change corresponding to a prominent C-isotope excursion. Ongoing studies will provide a detailed palynological inventory of the Early Triassic coal deposits on an intra-Gondwanic scale, contributing to the interpretation of early Mesozoic palaeoclimates.

Götz, Annette E.

2013-04-01

35

Gondwana (Africa) from top to base in space and time  

NASA Astrophysics Data System (ADS)

Gondwana with Africa at its core is reviewed from the unification of its several cratons in the Late Neoproterozoic, through its combination with Laurussia in the Carboniferous to form Pangea and up to its progressive fragmentation in the Mesozoic. For much of that time it was the largest continental unit on Earth and its remnants constitute 64% of all land areas today. New palaeogeographical reconstructions are presented, ranging from the Early Cambrian (540 Ma) through to just before the final Pangea breakup at 200 Ma. In Late Palaeozoic and Early Mesozoic times, Gondwana lay over the African large low shear-wave velocity province (LLSVP), one of two major thermochemical piles covering ca. 10% of the core-mantle boundary. The edges of the LLSVPs (Africa and its Pacific antipode) are the plume generation zones (PGZs) and the source regions of kimberlite intrusions and large igneous provinces (LIPs). Our palaeomagnetic reconstructions constrain the configuration of Gondwana and adjacent continents relative to the spin axis, but in order to relate deep mantle processes to surface processes in a palaeomagnetic reference frame, we have also rotated the PGZs to account for true polar wander. In this way, we visualize how the surface distribution of LIPs and kimberlites relate to Gondwana's passage over the PGZs. There are only two LIPs in the Palaeozoic (510 and 289 Ma) that directly affected Gondwanan continental crust, and kimberlites are rare (83 in total). This is because Gondwana was mostly located between the two LLSVPs. The majority of Palaeozoic kimberlites are Cambrian in age and most were derived from the African PGZ. Sixty-six Early Mesozoic kimberlites are also linked to the African LLSVP. All known LIPs (Kalkarindji, Panjal Traps, Central Atlantic Magmatic Province and Karoo) from 510 to 183 Ma (the lifetime of Gondwana) were derived from plumes associated with the African LLSVP, and three of them probably assisted the breakup of Gondwana and Pangea.

Torsvik, Trond H.; Cocks, L. Robin M.

2014-05-01

36

Ordovician K-bentonites in the Argentine Precordillera: relations to Gondwana margin evolution  

USGS Publications Warehouse

This paper is included in the Special Publication entitled 'The proto- Andean margin of Gondwana', edited by R.J. Pankhurst and C.W. Rapela. Ordovician K-bentonites have now been recorded from >20 localities in the vicinity of the Argentine Precordillera. Most occur in the eastern thrust belts, in the San Juan Limestone and the overlying the Gualcamayo Formation, but a few ash beds are known also from the central thrust belts. The oldest occur in the middle Arenig I, victoriae lunatus graptolite (Oe. evae conodont) Zone, and the youngest in the middle Llanvirn P. elegans (P. suecicus) Zone. Mineralogical characteristics, typical of other Ordovician K-bentonites, include a matrix of illite/smectite mixed-layer clay and a typical felsic volcanic phenocryst assemblage: biotite, beta-form quartz, alkali and plagioclase feldspar, apatite, and zircon, with lesser amounts of hornblende, clinopyroxene, titanite and Fe-Ti oxides. The proportions of the mineral phases and variations in their crystal chemistry are commonly unique to individual (or small groups of) K-bentonite beds. Glass melt inclusions preserved in quartz are rhyolitic in composition. The sequence is unique in its abundance of K-bentonite beds, but a close association between the Precordillera and other Ordovician sedimentary basins cannot be established. The ash distribution is most consistent with palaeogeographical reconstructions in which early Ordovician drifting of the Precordillera occurred in proximity to one or more volcanic arcs, and with eventual collision along the Andean margin of Gondwana during the mid-Ordovician Ocloyic event of the Famatinian orogeny. The Puna-Famatina terrane northeast of the Precordillera might have served as the source of the K-bentonite ashes, possibly in concert with active arc magmatism on the Gondwana plate itself.

Huff, W.D.; Bergstrom, S.M.; Kolata, D.R.; Cingolani, C.A.; Astini, R.A.

1998-01-01

37

Patterns of Gondwana plant colonisation anddiversification  

NASA Astrophysics Data System (ADS)

Charting the broad patterns of vascular plant evolution for Gondwana againstthe major global environmental shifts and events is attempted here for the first time. This is based on the analysis of the major vascular plant-bearing formations of the southern continents (plus India) correlated against the standard geological time-scale. Australia, followed closely by South America, are shown to yield by far the most complete sequences of productive strata. Ten seminal turnover pulses in the unfolding evolutionary picture are identified and seen to be linked to continental drift, climate change and mass global extinctions. The rise of vascular plants along the tropical belt, for instance, followed closely after the end-Ordovician warming and extinction. Equally remarkable is that the Late Devonian extinction may have caused both the terrestrialisation of the vertebrates and the origin of the true gymnosperms. The end-Permian extinction, closure of Iapetus, together with warming, appears to have set in motion an unparalleled, explosive, gymnosperm radiation; whilst the Late Triassic extinction dramatically curtailed it. It is suggested that the latitudinal diversity gradient clearly recognised today, where species richness increases towards the tropics, may have been partly reversed during phases of Hot House climate. Evidence hints at this being particularly so at the heyday of the gymnosperms in the Late Triassic super-Hot House world. As for the origin of terrestrial, vascular, plant life, the angiosperms seem closely linked to a phase of marked shift from Ice House to Hot House. Insect and tetrapod evolutionary patterns are discussed in the context of the plants providing the base of the ever-changing ecosystems. Intimate co-evolution is often evident. This isn't always the case, for example the non-linkage between the dominant, giant, long-necked, herbivorous sauropod dinosaurs and the dramatic radiation of the flowering plants in the Mid Cretaceous.

Anderson, J. M.; Anderson, H. M.; Archangelsky, S.; Bamford, M.; Chandra, S.; Dettmann, M.; Hill, R.; McLoughlin, S.; Rösler, O.

38

The Basement of the Andes: the Gondwana-Laurentia Connections Revisited  

NASA Astrophysics Data System (ADS)

The research performed in the last decade in the basement of the Andes have shown that the Precambrian and Paleozoic rocks have recorded a series of igneous and metamorphic events through time. These episodes can be grouped in discrete orogenic events, which have different paleogeographic distribution and intensity. The first and most important orogenic event is widely distributed along the margin and correspond to the Sunsas-Grenville orogen. Evidence of metamorphism and associated magmatic rocks are found from Colombia to the southernmost Patagonia. This episode produced the amalgamation of Amazonia, Pampia and Patagonia, among other cratonic blocks, to form Rodinia. The Rodinia break-up leaved several cratonic blocks accreted in the Gondwana side, such as Marañón, Arequipa, and Antofalla, although the generalized extension of this period produced crustal attenuation, rifted basins, and limited oceanic realms during late Proterozoic times. The Brasiliano-Pampean orogeny reamalgamated these blocks against the Gondwana margin. A new episode of break-up produced the dispersal of several Gondwanian blocks, separation along some previous sutures, crustal attenuation and magmatism in Late Cambrian times, until the new amalgamation occurred in Middle Late Ordovician times. These processes led to the Famatinian orogeny when metamorphism and arc magmatism was widely spread along the continental margin, as seen in Chibcha, Marañón, Arequipa and Sierras Pampeanas. Besides the re-accretion of some parautochthonous terranes, new exotic blocks were derived from Laurentia, such as the Cuyania terrane, which finally collided against the Andean proto-margin at ~ 460 Ma to form the Argentine Precordillera and surrounding regions. Late accretion in Early to Middle Devonian times of Chilenia and related terranes formed most of the basement of Central Andes. Final collision between Laurentia and Gondwana in the Late Carboniferous - Early Permian times to form the Alleghanides, left behind some Laurentian pieces like Tahami, Tres Lagunas and Tahuin terranes of Colombia, Ecuador and Perú. This set of rifting episodes and subsequent collisions along the continental margin of western South America were the result of changes of the absolute motion of Gondwana related to global plate reorganizations during Proterozoic to Paleozoic times.

Ramos, V. A.

2009-05-01

39

Dust accumulation and leaf pigment content in vegetation near the national highway at Sambalpur, Orissa, India  

Microsoft Academic Search

An investigation on the seasonal variation in dust accumulation on leaves and leaf pigment content of six plant species of mixed habits was carried out at the side of the National Highway (NH 6) at Sambalpur, Orissa, India. The plants selected for study were Pongamia pinnata, Tabernaemontana divaricata, Ipomea carnea, Ficus relogiosa, Ficus benghalensis, and Quisqualis indica. The observed trend

B. A. K. Prusty; P. C. Mishra; P. A. Azeez

2005-01-01

40

Vulnerability to Agricultural Drought in Western Orissa: A Case Study of Representative Blocks  

Microsoft Academic Search

The nature of vulnerability to agricultural drought in three study blocks of Bolangir district in western Orissa has been analysed. The indexing and vulnerability profile method have been used for assessing the nature of drought vulnerability, coping capacity and risk. The study has revealed that the three most influential biophysical factors of drought vulnerability are: rainfall variability, drought intensity and

Mrutyunjay Swain; Mamata Swain

2011-01-01

41

Perceived Gender Role that Shape Youth Sexual Behaviour: Evidence from Rural Orissa, India  

ERIC Educational Resources Information Center

The study attempts to understand the association of perceived gender role with youth sexual behavior using qualitative data such as focus group discussions (N = 8), in-depth interviews (N = 42), and free listing (N = 50) of rural married youths from Orissa, India. Data collection was conducted during July 2006-April 2007. Atlas. ti and ANTHROPAC…

Pradhan, Manas Ranjan; Ram, Usha

2010-01-01

42

EFFECT OF WOMEN'S NUTRITIONAL STATUS ON FERTILITY: STUDY OF A NON-INDUSTRIAL POPULATION IN ORISSA  

Microsoft Academic Search

The current paper examines plausible causal relationship if any, between women's nutritional status and fertility, among Scheduled Tribes, more or less a non- industrial rural population, in Orissa, an eastern Indian state. The variables on nutritional status of women were studied from primary data collected using anthropometric tools and techniques. For analysis, besides frequency distribution, separate ANOVA tests have been

Satyajeet Nanda

43

Family Characteristics and Adolescent Competence in India: Investigation of Youth in Southern Orissa  

Microsoft Academic Search

This study examines the relationship among a host of family characteristics and indicators of adolescent competence in a sample (N = 107) of 8th- and 9th-grade students in one school located in Berhampur city in Orissa state, India. Social competence (SC) and antisocial behavior (AB) were assessed by teachers, and adolescents evaluated various areas of their own competence on a

David K. Carson; Aparajita Chowdhury; Cecyle K. Perry; Chetana Pati

1999-01-01

44

National Initiatives, Local Effects: Trade Liberalization, Shrimp Aquaculture, and Coastal Communities in Orissa, India  

Microsoft Academic Search

Commercial shrimp farming in India expanded rapidly after trade liberalization initiatives were introduced in the early 1990s. This article examines the social, economic and environmental impacts that have been generated in communities along Orissa's Coast in east India. The results suggest that macro-level policies such as trade liberalization are useful at the national level, but at the local level they

Dolagobinda Pradhan; Mark Flaherty

2007-01-01

45

Understanding the Dynamics of Food Insecurity and Vulnerability in Orissa, India  

Microsoft Academic Search

This paper documents the main findings of a study on food insecurity and vulnerability in the Indian state of Orissa in support of promoting interventions for food security and livelihoods at state level. A similar study was undertaken in Himachal Pradesh, India. The paper analyses the main characteristics and causes of food insecurity and vulnerability. It seeks to identify who

Christian Romer Lovendal

2007-01-01

46

TRIBAL USES OF PLANTS FROM NARAYANAPATNA REGION OF KORAPUT DISTRICT, ORISSA  

PubMed Central

The paper reports the ethnomedicinal uses of 32 plants by the tribals of Narayanapatna area of koraput district, Orissa. Besides, uses of other plants or plant products are also dealt, with. Distribution of plants in the area, their field numbers, local and oriya names are appended. PMID:22556748

Dash, Sudhansu S.; Misra, Malaya K

1996-01-01

47

Oroclines in the Tasmanides of eastern Gondwana  

NASA Astrophysics Data System (ADS)

Orogenic curvature is a prominent and clearly recognisable feature of the Tethyan orogens of Eurasia. By contrast, the Tasmanides, a series of convergent orogens with overlapping active cycles spanning the whole of the Palaeozoic, have until recently been viewed as a largely linear system roughly paralleling the Proterozoic rift margin to which it is accreted. Oroclinal curvature was only recognised in the youngest part of the Tasmanides system, the New England Orogen, where mappable geology and palaeomagnetism confirm the existence of multiple, tightly refolded limbs. Much of the rest of the Tasmanides is covered by thick Mesozoic to recent platform cover, and only the acquisition of high-resolution aeromagnetic data, enhanced by the use of the tilt filter, has enabled the recognition of the Lachlan Orocline, a previously unsuspected feature that explains the apparent repetition and mirror-reflection of terranes in the southernmost part of the Tasmanides system. Radial structures in the core of the Lachlan Orocline, imaged as long-wavelength magnetic anomalies, resemble the radial conical folds resulting from compression on the inner arc of the orocline that have been modelled for the Iberian-Armorican Arc. No direct palaeomagnetic test is yet available for the Lachlan Orocline, but palaeomagnetic directions from second-order curved structures developed along the lithosphere-penetrating strike-sip fault that bounds the orocline record a related Silurian clockwise rotation. Rotation around a small-scale suspect orocline in the northern Tasmanides (the North Queensland Orogen) may record collision between a ribbon continent and Gondwana; palaeomagnetic data from within this suspect orocline show a large change in declination between the Silurian and Devonian. Late Cambrian oroclinal bending in the western Tasmanides is responsible for the rigid kink-bending of the originally linear Mount Wright volcanic chain. While this feature has also only been recognised through its aeromagnetic expression, the displacement that produced its flexure was also responsible for the growth of the Nackara Arc, a fold-thrust system in the Adelaide Fold Belt representing the retro-thrust part of the same orogeny. A re-examination of existing palaeomagnetic data from the Adelaide Fold Belt supports the view that the Nackara Arc is rotational. Taken together, the set of previously unrecognised oroclinal rotations in the Tasmanides reduce a series of apparent complexities in the Palaeozoic Gondwanan apparent polar to local vertical-axis rotations.

Musgrave, Robert

2013-04-01

48

Global deglaciation and the re-appearance of microbial matground-dominated ecosystems in the late Paleozoic of Gondwana.  

PubMed

The extensive matgrounds in Carboniferous-Permian open-marine deposits of western Argentina constitute an anachronistic facies, because with the onset of penetrative bioturbation during the early Paleozoic microbial mats essentially disappeared from these settings. Abundant microbially induced sedimentary structures in the Argentinean deposits are coincident with the disappearance of trace and body fossils in the succession and with a landward facies shift indicative of transgressive conditions. Deposits of the Late Carboniferous-Early Permian glacial event are well developed in adjacent basins in eastern Argentina, Brazil, South Africa and Antarctica, but do not occur in the western Andean basins of Argentina. However, the deglaciation phase is indirectly recorded in the studied region by a rapid rise in sea level referred to as the Stephanian-Asselian transgression. We suggest that an unusual release of meltwater during the final deglaciation episode of the Gondwana Ice Age may have dramatically freshened peri-Gondwanan seas, impacting negatively on coastal and shallow-marine benthic faunas. Suppression of bioturbation was therefore conducive to a brief re-appearance of matground-dominated ecosystems, reminiscent of those in the precambrian. Bioturbation is essential for ecosystem performance and plays a major role in ocean and sediment geochemistry. Accordingly, the decimation of the mixed layer during deglaciation in the Gondwana basins may have altered ecosystem functioning and geochemical cycling. PMID:23621394

Buatois, L A; Netto, R G; Gabriela Mángano, M; Carmona, N B

2013-07-01

49

The basins on the Argentine continental margin  

SciTech Connect

After the stabilization of the central Gondwana Craton, orogenic belts were accreted, as a result of convergence events and an extensive passive margin developed in southwestern Gondwana. Thermal subsidence in Parana, Karoo-Ventania basins and the Late Paleozoic-Early Mesozoic rifts, were modified by the Gondwana breakup and the South Atlantic opening. Early Paleozoic marine transgressions deposited the Table Mountain Group in Ventania. In southwestern Patagonia foreland clastics were deposited. Magmatic arcs and marine units indicate a tectonic trough was formed, alternating with continental sequences, over Late Paleozoic metamorphics and intrusives, resulting from plastered terrains along the Gondwana margin. In Patagonia, Permo-Carboniferous continental and glacio marine clastics infill the basins, while in Ventania, paralic sequences, grade from neritic to continental to the northeast, extending beneath the continental margin. The Triassic-Jurassic rift basins progressed onto regional widespread acid lavas and were infilled by lagoonal organic-rich sequences. Early drift phase built basins transverse to the margin, with fluvio-lacustrine sequences: Salado, Colorado, Valdes-Rawson, San Julian and North Malvinas intracratonic basins, which underwent transtensional faulting. Post-Oxfordian to Neocomian brackish sequences, onlapped the conjugate basins during the margin`s drift, with petroleum systems, as in Austral and Malvinas. In the Valanginian, basic extrusions commenced to form on the continental border, heralding the oceanic phase. Due to thermal subsidence, offlaping sediments prograded onto the remaining half-grabens. Several petroleum systems, proven and hypothetical, are identified in this region.

Urien, C.M. [Buenos Aires Technological Institute Petroleum School, Buenos Aires (Argentina)

1996-08-01

50

Optical remote sensing a potential tool for forecasting malaria in Orissa, India  

NASA Astrophysics Data System (ADS)

Information on current and anticipated moisture and thermal condition from satellite data represents a source of affordable yet careful information for malaria forecasters to implement and control of epidemic. During the last decades Orissa state in India suffered from highest level of malaria incidence. This situation requires frequent monitoring of environmental conditions and dynamics of malaria occurrence. During 1985 to 2004 the NOAA AVHRR global vegetation index (GVI) dataset and its vegetation health (VH) have been studied and used as proxy for malaria fluctuation. This paper discusses applications of VH for early detecting and monitoring malaria incidence in Orissa. A significant relationship between satellite data and annual malaria incidences is found at least three months before the major malaria transmission period.

Nizamuddin, Mohammad; Akhand, Kawsar; Roytman, Leonid; Kogan, Felix; Goldberg, Mitch

2013-05-01

51

Perceived gender role that shape youth sexual behaviour: Evidence from rural Orissa, India  

Microsoft Academic Search

The study attempts to understand the association of perceived gender role with youth sexual behavior using qualitative data such as focus group discussions (N=8), in-depth interviews (N=42), and free listing (N=50) of rural married youths from Orissa, India. Data collection was conducted during July 2006–April 2007. Atlas. ti and ANTHROPAC packages have been used for the analysis. Youths in general

Manas Ranjan Pradhan; Usha Ram

2010-01-01

52

Molecular investigations of chikungunya virus during outbreaks in Orissa, Eastern India in 2010.  

PubMed

Chikungunya virus (CHIKV), an arthritogenic alphavirus, is transmitted to humans by mosquitoes of genus Aedes, mainly Aedes aegypti and Aedes albopictus. The resurgence of CHIKV in different parts of India is a point of major public health concern. In 2010, chikungunya outbreaks with high epidemic magnitude were recorded in coastal areas of Orissa, Eastern India, affecting more than 15,000 people coupled with severe arthralgia and prolonged morbidites. Detailed entomological, serological and molecular investigation of this unprecendented outbreak was carried out by collecting and studying 1359 mosquito samples belonging to A. albopictus, A. aegypti, A. vittatus, A. edwardsii and Culex species and 220 patients serum from the affected areas. In this study, CHIKV specific IgM capture-ELISA and reverse-transcription PCR (RT-PCR) were done to detect recent infection of CHIKV in serum samples and adult mosquitoes collected from the affected areas. The high maximum likelihood estimate (MLE) (15.2) in A. albopictus mosquitoes indicated that it was the principal vector involved in transmission of CHIKV in Orissa. Phylogenetic analysis revealed that the CHIKV strains involved in the outbreak belonged to the Indian Ocean Lineage (IOL) group within the East, Central and South African (ECSA) genotype. Genetic characterization of envelope glycoprotein (E1 and E2) genes revealed that all the CHIKV isolates from Orissa had the E1-A226V mutation that enhances viral dissemination and transmissibility by A. albopictus mosquitoes along with E2-L210Q and E2-I211T mutations, which play an epistatic role with E1-A226V mutation in adaptation of CHIKV to A. albopictus by increasing its midgut infectivity, thereby favoring its vectorial capacity. Our results showed the involvement of A. albopictus vector in the recent outbreaks in Orissa and circulation of IOL strains of ECSA genotype of CHIKV with E1-A226V, E2-L210Q and E2-I211T mutations in vectors and patients serum. PMID:22484761

Das, Biswadeep; Sahu, Abhipsa; Das, Mumani; Patra, Aparna; Dwibedi, Bhagirathi; Kar, Santanu K; Hazra, Rupenangshu K

2012-07-01

53

Panjal Paleomagnetism: Implications for Early Permian Gondwana break-up  

NASA Astrophysics Data System (ADS)

The mid-Early Permian represents an important phase in Pangaea's development marking the time when the >13,000 km-long string of terranes that are collectively known as 'Cimmeria' separated from Gondwana's Tethyan margin (northern Africa-NE Arabia-northern India-NW and northern Australia). The ~289 Ma Panjal Traps of NW India (Kashmir) are one of a number of mafic suites (Abor, Sikkim etc.) that were erupted onto the Indian block possibly during the separation of the Lhasa/SE Qiangtang block. Herein, we report data from the first modern paleomagnetic study of the unit. Results from four quarry sections (15 individual cooling units) from a locality close to Srinagar together form a tectonically coherent sequence spanning 2-3 km of stratigraphy. The derived direction and paleopole yield key new information concerning (1) the Early Permian location of India, and by inference that of central Gondwana, and (2) inform debates related to Cimmeria's breakup from eastern Gondwana. Moreover, they provide a new independent control for assessing NW Greater India's extent prior to its collision with Asia and the amount of vertical-axis rotation this sector of the Himalayan range experienced in the mid to late Cenozoic.

Stojanovic, D.; Aitchison, J.; Ali, J. R.; Ahmad, T.; Ahmad Dar, R.; Agarwal, A.; Roeder, T.

2013-12-01

54

Late Triassic early Jurassic continental extension in southwestern Gondwana: tectonic segmentation and pre-break-up rifting  

NASA Astrophysics Data System (ADS)

From the earliest Jurassic to the Cenozoic, the Neuquén Basin (central Argentina and Chile) evolved as an intra-arc and transarc-retroarc depression through the gradual development of the Andean magmatic arc. However, the region adjacent to the proto-Pacific margin of Gondwana between 30 and 40°S was subject to pre-Andean continental extension that began in the Late Triassic and lasted about 30 million years until the Early Jurassic. This extension resulted in the generation of a series of rifts oriented parallel to the margins of the extended area and characterized by continental volcaniclastic and pyroclastic deposits associated with lava flows and bimodal plutonic intrusions. The inception of the Neuquén Basin as a single depocenter occurred in the Early Pliensbachian, when post-rift thermal subsidence led to a general marine transgression. The T-J extension is closely linked to structures created by previous tectonothermal episodes such as the development of a Carboniferous-Permian orogenic belt (330-280 Ma), and to events along the proto-Pacific margin of Gondwana. Lithospheric thickening related to Late Paleozoic convergence caused strong gravitational instability in the orogenic belt between 30 and 40°S. Subsequent cessation of subduction, coeval with establishment of dextral strike-slip tectonics parallel to the continental margin, caused detachment of the subducting slab and generation of an asthenospheric window. Anomalous heating of the upper mantle resulted in bimodal magmatism, uplift, thermal weakening, and gravitational collapse of the upper crust. South of this extended area, proto-Pacific subduction was active during the same Late Triassic-Early Jurassic interval. Thus, the contrasting tectonic behaviour of the Gondwana margin north and south of 40°S suggests significant pre-Andean tectonic segmentation that coincides with the southern boundary of the area extended in the Late Triassic-Early Jurassic. Previous intepretations assumed a common massive extension in the Andean and Patagonian regions of southern South America. Our results demonstrate that T-J extensional rifting and magmatism between 30 and 40°S were the result of mechanical interaction between different lithospheric plates at the pre-Andean (proto-Pacific) continental margin. On the other hand, the mechanical and thermal processes that affected much of Patagonia during the Middle and Late Jurassic were a response to the tectonic and magmatic processes that caused the initial break-up of Gondwana with the opening of the Weddell Sea after 180 Ma.

Franzese, Juan R.; Spalletti, Luis A.

2001-07-01

55

Terra Australis Orogen: Rodinia breakup and development of the Pacific and Iapetus margins of Gondwana during the Neoproterozoic and Paleozoic  

NASA Astrophysics Data System (ADS)

The Pacific Ocean formed through Neoproterozoic rifting of Rodinia and despite a long history of plate convergence, this ocean has never subsequently closed. The record of ocean opening through continental rifting and the inception of ocean convergence through the initiation of subduction are preserved in the Neoproterozoic to late Paleozoic Terra Australis Orogen. The orogen had a pre-dispersal length along the Gondwana margin of approximately 18,000 km and was up to 1600 km wide. It incorporates the Tasman, Ross and Tuhua orogens of Australia, Antarctica and New Zealand, respectively, the Cape Basin of Southern Africa, and Neoproterozoic to Paleozoic orogenic elements along the Andean Cordillera of South America. The Terra Australis Orogen can be divided into a series of basement blocks of either continental or oceanic character that can be further subdivided on the basis of pre-orogenic geographic affinity (Laurentian vs. Gondwanan) and proximity to inferred continental margin sequences (peri-Gondwanan vs. intra-oceanic). These divisions reflect initial tectonic setting and provide an insight into the character of the orogen through time. The orogen incorporates elements that are inferred to have lain outboard of both West and East Laurentia within Rodinia. Subduction of the Pacific Ocean was established at, or close to, the Gondwana margin by around 570 Ma and occurred at about the same time as major global plate reorganization associated with final assembly of Gondwana and the opening of the Iapetus Ocean. The termination of the Terra Australis Orogen at around 300-230 Ma was associated with the assembly of Pangea. It is represented by the Pan-Pacific Gondwanide Orogeny and is marked in east Gondwana by a stepping out in the position of the plate boundary and commencement of the classic late Paleozoic to Mesozoic Gondwanide Orogen. The Pacific has been cited as an example of the declining stage of the Wilson cycle of ocean basins. However, its protracted history of ongoing subduction and the absence of any indication of major continental collisions contrasts with the clear evidence for opening and closing of oceans preserved in the Iapetus/Atlantic and Tethyan realms. The Terra Australis and other orogens that bound the Pacific are accretionary orogens and did not form through the classic Wilson cycle.

Cawood, Peter A.

2005-03-01

56

A TIGHT FIT-EARLY MESOZOIC GONDWANA, A PLATE RECONSTRUCTION PERSPECTIVE  

Microsoft Academic Search

ABSTRACT Gondwana, with East Antarctica as its center, began to break up during Late Triassic to Early Jurassic time. Use of the satellite derived gravity map to approximate the ocean-continent boundary allows us to generate a much tighter fit for the reconstructed supercontinent then previously attempted. Major mantle plumes such as the Karoo-Ferrar Plume that first split Gondwana at about

Lawrence A. Lawver; Lisa M. Gahagan; Ian W. D. Dalziel

57

The break-up of Rodinia, birth of Gondwana, true polar wander and the snowball Earth  

Microsoft Academic Search

A major global plate reorganisation occurred between ?750 and ?550 Ma. Gondwana was assembled following the dispersal of Rodinia, a supercontinent centred on Laurentia in existence since ?1050 Ma. The reorganisation began when tectonic elements, later composing East Gondwana, rotated piecemeal away from the Pacific margin of Laurentia. These elements swept across the ancestral Pacific (Mozambique) Ocean that lay between

Paul F. Hoffman

1999-01-01

58

Upper Carboniferous retroarc volcanism with submarine and subaerial facies at the western Gondwana margin of Argentina  

NASA Astrophysics Data System (ADS)

During Late Carboniferous times a continental magmatic arc developed at the western margin of Gondwana in South America, as several marine sedimentary basins were formed at the same time in the retroarc region. North of 33°S, at Cordón Agua del Jagüel, Precordillera of Mendoza, Argentina, a volcanic sequence crops out which was emplaced in a submarine environment with some subaerial exposures, and it is intercalated in marine sediments of Agua del Jagüel Formation, which fills of one of these retroarc basins. This paper presents, for the first time, a facies analyses together with geochemical and isotopic data of this volcanic suite, suggesting its deposition in an ensialic retroarc marine basin. The volcanic succession comprises debris flows with either sedimentary or volcanic fragments, base surge, resedimented massive and laminated dacitic-andesitic hyaloclastite, pillow lava, basic hyaloclastite and dacitic-andesitic lavas and hyaloclastite facies. Its composition is bimodal, either basaltic or dacitic-andesitic. The geochemistry data indicate a subalkaline, low K calk-alkaline and metaluminous affinity. The geochemistry of the basalts points to an origin of the magmas from a depleted mantle source with some crustal contamination. Conversely, the geochemistry of the dacites-andesites shows an important participation of both crustal components and subduction related fluids. A different magmatic source for the basalts than for the dacites-andesites is also supported by Sr and Nd isotopic initial ratios and Nd model ages. The characteristics of this magmatic suite suggest its emplacement in an extensional setting probably associated with the presence of a steepened subduction zone at this latitude during Upper Carboniferous times.

Koukharsky, M.; Kleiman, L.; Etcheverría, M.; Quenardelle, S.; Bercowski, F.

2009-04-01

59

Role of fungi in litter decomposition associated with Casuarina equisetifolia L. plantations in coastal sand dunes, Orissa, India  

Microsoft Academic Search

Seasonal dynamics of soil microfungal populations, their metabolic activity and decomposition of leaf litter were studied in a monoculture plantation of Casuarina equisetifolia L. in coastal sandy belt of Orissa for a period of 2 years (June 2002–May 2004). Fungal succession of litter was also studied. Microbial isolation and soil analysis was performed using standard procedures and decomposition of leaf

T. Panda

2010-01-01

60

Drop-Out in Schools in India: Minor Field Studies in Orissa 1990. Educational and Psychological Interactions. No. 112.  

ERIC Educational Resources Information Center

This document consists of a report on the Minor Field Studies (MFS) program of the Swedish International Development Authority (SIDA) and contains two MFS papers by teacher trainees at the Malmo School of Education in Sweden. The papers presented are "Drop-outs in Orissa," by Elisabeth Rosen, and "Education in India: A Study of Drop-Out Children…

Ekstrand, Gudrun, Ed.

61

Petroleum system of the Gippsland Basin, Australia  

USGS Publications Warehouse

The Gippsland Basin Province 3930, located on the southeastern coast of Australia, is formed from two successive failed rifts that developed into a passive margin during the Cretaceous. Formation of this basin is related to the break up of Gondwana, which resulted in the separation of Antarctica from Australia, and the separation of the New Zealand and Lord Howe Rise continental crust from Australia. Coals and coaly shales of Late Cretaceous through Eocene age are the source rocks for oil and gas that accumulated predominantly in anticlinal traps. The basin was Australia?s major producing basin until 1996 when daily oil/condensate production from the North West Shelf surpassed it.

Bishop, Michele G.

2000-01-01

62

Genetic Structure and Wolbachia Genotyping in Naturally Occurring Populations of Aedes albopictus across Contiguous Landscapes of Orissa, India  

PubMed Central

Background Aedes albopictus has recently been implicated as a major vector in the emergence of dengue and chikungunya in several parts of India, like Orissa, which is gradually gaining endemicity for arboviral diseases. Ae. albopictus is further known to be naturally infected with Wolbachia (maternally inherited bacterium), which causes cytoplasmic incompatibility (CI) in mosquitoes leading to sperm-egg incompatibility inducing the death of embryo. Knowledge of genetic diversity of Ae. albopictus, along with revealing the type of Wolbachia infection in Ae. albopictus is important to explore the genetic and biological characteristics of Ae. albopictus, prior to exploring the uses of CI-based vector control strategies. In this study, we assessed the population genetic structure and the pattern of Wolbachia infection in Ae. albopictus mosquitoes of Orissa. Methods and Results Ae. albopictus mosquitoes were collected from 15 districts representing the four physiographical regions of Orissa from 2010–2012, analyzed for genetic variability at seven microsatellite loci and genotyped for Wolbachia strain detection using wsp gene primers. Most microsatellite markers were successfully amplified and were polymorphic, showing moderate genetic structure among all geographic populations (FST?=?0.088). Genetic diversity was high (FST?=?0.168) in Coastal Plains populations when compared with other populations, which was also evident from cluster analyses that showed most Coastal Plains populations consisted of a separate genetic cluster. Genotyping analyses revealed that Wolbachia-infected Ae. albopictus field populations of Orissa were mostly superinfected with wAlbA and wAlbB strains. Wolbachia superinfection was more pronounced in the Coastal Plain populations. Conclusion High genetic structure and Wolbachia superinfection, observed in the Coastal Plain populations of Orissa suggested it to be genetically and biologically more unique than other populations, and hence could influence their vectorial attributes. Such high genetic diversity observed among Coastal Plains populations could be attributed to multiple introductions of Ae. albopictus in this region. PMID:24714653

Das, Biswadeep; Satapathy, Truptimayee; Kar, Santanu K.; Hazra, Rupenangshu K.

2014-01-01

63

Micro-continents offshore Western Australia: implications for East Gondwana reconstructions  

NASA Astrophysics Data System (ADS)

The southern part of the Western Australian margin formed at the nexus of rifting and breakup between the East Gondwanan continents India, Australia and Antarctica in the Early Cretaceous. However, understanding the basin evolution along this margin has been hampered by a lack of data from the offshore Perth Abyssal Plain, and from the conjugate Greater Indian margin, which was highly deformed during collision with Eurasia. The Batavia Knoll and Gulden Draak Knoll are two prominent, previously unsampled, bathymetric features located >1600 km offshore Australia that have typically been assumed to be igneous features. In late 2011, successful dredges on the western flanks of both knolls recovered continental basement rocks, revealing that both knolls are micro-continents. Felsic orthogneiss and granite from Gulden Draak and Batavia knolls yield 2.8 Ga, 1.3-1.2 Ga and 540-510 Ma U-Pb zircon ages. The affinity of these geological samples, coupled with existing geological sampling and geophysical data, allow us to test alternative reconstructions for East Gondwana breakup. A number of alternative models have been proposed for the pre-rift configuration of Australia and Antarctica. Competing models make very different predictions for the kinematics of Mesozoic rifting that produced the basins along the Southern Australian margin; the magnitude of extension during rifting; and how mapped Paleozoic and Proterozoic geological terranes and fault zones can be correlated between Australia and Antarctica. We will present reconstructions that reconcile our new samples from Indian Ocean micro-continents with observations from India, Antarctica, Australia, and the evolution of the Indian Ocean.

Whittaker, Joanne; Williams, Simon; Halpin, Jacqueline; Daczko, Nathan; Gardner, Robyn

2014-05-01

64

Blindsnake evolutionary tree reveals long history on Gondwana  

PubMed Central

Worm-like snakes (scolecophidians) are small, burrowing species with reduced vision. Although largely neglected in vertebrate research, knowledge of their biogeographical history is crucial for evaluating hypotheses of snake origins. We constructed a molecular dataset for scolecophidians with detailed sampling within the largest family, Typhlopidae (blindsnakes). Our results demonstrate that scolecophidians have had a long Gondwanan history, and that their initial diversification followed a vicariant event: the separation of East and West Gondwana approximately 150 Ma. We find that the earliest blindsnake lineages, representing two new families described here, were distributed on the palaeolandmass of India+Madagascar named here as Indigascar. Their later evolution out of Indigascar involved vicariance and several oceanic dispersal events, including a westward transatlantic one, unexpected for burrowing animals. The exceptional diversification of scolecophidians in the Cenozoic was probably linked to a parallel radiation of prey (ants and termites) as well as increased isolation of populations facilitated by their fossorial habits. PMID:20356885

Vidal, Nicolas; Marin, Julie; Morini, Marina; Donnellan, Steve; Branch, William R.; Thomas, Richard; Vences, Miguel; Wynn, Addison; Cruaud, Corinne; Hedges, S. Blair

2010-01-01

65

Dust accumulation and leaf pigment content in vegetation near the national highway at Sambalpur, Orissa, India.  

PubMed

An investigation on the seasonal variation in dust accumulation on leaves and leaf pigment content of six plant species of mixed habits was carried out at the side of the National Highway (NH 6) at Sambalpur, Orissa, India. The plants selected for study were Pongamia pinnata, Tabernaemontana divaricata, Ipomea carnea, Ficus relogiosa, Ficus benghalensis, and Quisqualis indica. The observed trend of dust accumulation was in the order T. divaricata>I. carnea>P. pinnata>F. religiosa>F. benghalensis>Q. indica. One-way analysis of variance showed significant difference in dust accumulation among plant species (F1 = 4.674, P < 0.01) and between seasons (F2 = 9.240, P < 0.01). It was seen that dust load increases with increasing number of vehicles using the highway (major emission source). The result shows significant correlation (negative) between dust load and pigment content in summer and rainy season. PMID:15546639

Prusty, B A K; Mishra, P C; Azeez, P A

2005-02-01

66

World bank EMCP malaria project in Orissa, India — A field reality  

PubMed Central

Background: Under the National Vector Borne Disease Control Program, the Enhanced Malaria Control Project (EMCP) with World Bank assistance was implemented in India, in the eastern state of Orissa. Aims: This article tries to analyze the possible reasons for the poor performance of EMCP in a few states of India. Settings and Design: The eastern state of India is taken as a case study for looking into systemic, human resource, and logistics related issues that could explain the poor performance of EMCP in a few states of India. Materials and Methods: Field visits were made to some selected EMCP areas in the state of Orissa. Operational issues-related implementation of various components of the project were scrutinized. Statistical analysis: Not Applicable. Results: While the project was highly successful in a few states of India, it had limited success in some states. It was learnt that the honorarium meant for Fever Treatment depot [FTD] work was divided among all the malaria workers. In high-risk areas, presumptive radical treatment was being carried on by malaria workers for every case of fever. Using Rapid Diagnostic Tests (RDTs) in such areas seemed to have no relevance. The laboratory technician ignored malaria work, due to a high work load and no additional incentive. In the Primary Health Centers (PHCs) the Medical officers had either not visited the village under indoor residual spray or symbolically visited only five to six houses. Cement tanks had to be built for larvivorus fish breeding. However, they had not been mad. Conclusions: The success of a public health program is dependent more on project implementation, management, monitoring, and evaluation of project activities than the volume of financial resource allocation. PMID:23507915

Patil, Rajan R; Kumar, Ravi K

2011-01-01

67

Gondwana Tales: an inquiry approach to plate tectonics  

NASA Astrophysics Data System (ADS)

Plate tectonics and its effects on the constitution of seas and continents are key models in science education. Fossil evidences are usually taught in demostrative key when Wegener's discoverings about Pangea are introduced. In order to introduce inquiry-based science education (IBSE) approaches to this topic, we propose "Gondwana Tales", an activity where students are asked to use fossil data to reconstruct the geologic history of an imaginary planet. Grouped in independent teams, each team is furnished with stratigraphic columns from several sites containing faunistic successions of real organisms existing in the past in Earth. Students are told to reconstruct a model of the evolution of the continents, by making calculations of relative ages of the fossils, and relating each fossil to a geologic era. The different teams have incomplete and complementary information. After a first step where they have to propose a partial model based on incomplete data, each team receives a "visitor scientist" from another team, this implying an informal scientific communication event. This process is performed several times, engaging a discussion in each team and getting a final consensus model created by the whole class. Correct answer is not given to the students, even at the end of the activity, to keep the activity under the parameters of real scientific experience, where there is not a "correct answer" to compare. Instead of this, and following the IBSE standards, a reflection on the process is proposed to students. The lack of complete information and the need to collaborate are part of classroom dynamics focused to the understanding of the process of creation of the scientific knowledge. This activity is part of the C3 Project on Creation of Scientific Knowledge that is being applied in the school.

Domènech Casal, Jordi

2014-05-01

68

Man in Biosphere Reserve: a Remote Sensing Study in Similipal, Orissa  

NASA Astrophysics Data System (ADS)

The Similipal is a densely forested hill-range in the heart of Mayurbhanj district,Orissa, lying close to the eastern-most end of the Easternghats. Similipal Biosphere Reserve is located in the Mahanadian Biogeographical Region and within the Biotic Province, Chhotanagpur Plateau.There are 4 villages in the core and 61 villages in the buffer area of the biosphere reserve .Agriculture is not well developed and employment opportunities are very poor , most of the people derive their income from collection of NTFP and sale of firewood and timber. A collaborative work is carried out by Regional Remote Sensing Centre(East) and Anthropological survey of India,Kolkata to study the impact of those four villages in the core area of SBR on the conservation of natural resources over the decades.Change in vegetation density as measured by NDVI over the decades is analysed to study the impact of these villages on the core area of Similipal Biosphere Reserve.

Biswal, A.; Mukherjee, S.; Jeyaram, A.; Krishna Murthy, Y. V. N.

2011-08-01

69

Late Proterozoic charnockites in Orissa, India: A U-Pb and Rb-Sr isotopic study  

SciTech Connect

Charnockite formation in the Angul district of Orissa took place between 1088 + 26/ -17 Ma, the U-Pb zircon upper intercept crystallization age of a leptynite neosome, and 957 +8/ -4-956 {plus minus} 4 Ma, the U-Pb zircon-monazite upper intercept and U-Pb monazite crystallization ages of a granite. Confirmation of the Proterozoic age of the charnockites is given by (1) a U-Pb zircon upper intercept 1159 + 59/ -30 Ma age and a Rb-Sr whole-rock 1080 {plus minus} 65 Ma age for an augen gneiss which pre-dates the leptynite, and (2) U-Pb monazite ages of 973 {plus minus} 5,964 {plus minus} 4, and 953 {plus minus} 4 Ma for a gray quartzofeldspathic gneiss, the augen gneiss, and the leptynite, respectively: these late Proterozoic dates are interpreted as representing ages recorded during charnockitization. The ca. 950-980 Ma charnockite- and granite-forming events are related to the evolution of mantle-derived, CO{sub 2}-bearing basic magma emplaced into the deeper levels of an extensional tectonic-transcurrent fault regime. The ca. 1100-1150 Ma tectonothermal and igneous events represent compressional tectonism in reactivated crystalline basement in the late mid-Proterozoic Eastern Ghats orogenic belt.

Aftalion, M.; Bowes, D.R.; Dash, B.; Dempster, T.J. (Scottish Universities Research and Reactor Centre, Glasgow (Scotland))

1988-11-01

70

Mental Health Consequences of the Trauma of Super-Cyclone 1999 in Orissa  

PubMed Central

A super-cyclone hit 12 coastal districts of Orissa in October 1999 and caused over 20,000 deaths and a considerable damage to property. The psychiatric sequelae of the super-cyclone was studied using a semi-structured proforma for disaster experience, Self Reporting Questionnaire, Impact of Event Scale, Post Traumatic Symptoms Scale, Hopelessness Scale, Suicidality Screening Questionnaire, Hospital Anxiety and Depression Scale and Presumptive Stressful Life Event Scale. The coping style of the victims was also studied. It was observed that 80.4% of the subjects had probable psychiatric disorder. Posttraumatic stress disorder was found in 44.3%; anxiety disorder in 57.5% and depression in 52.7%. A considerable proportion (63.4%) of cases had comorbidity. Children and adolescents, elderly persons, lower socioeconomic status, lower educational levels, unemployment, physical injury, degree of exposure, need for evacuation, death in the family, fear of imminent death during the event, hopelessness, increased stress before disaster and past psychiatric history were associated with adverse psychological sequelae. Increase in suicidality was observed. Implications of these findings are discussed. PMID:21224904

Kar, Nilamadhab; Jagadisha; Sharma, PSVN; Murali, N.; Mehrotra, Seema

2004-01-01

71

Slope-apron deposition in an Ordovician arc-related setting: the Vuelta de Las Tolas Member (Suri Formation), Famatina Basin, northwest Argentina  

Microsoft Academic Search

The Ordovician Suri Formation is part of the infill of the Famatina Basin of northwest Argentina, which formed in an active setting along the western margin of early Paleozoic Gondwana. The lower part of this formation, the Vuelta de Las Tolas Member, records sedimentation on a slope apron formed in an intra-arc basin situated on a flooded continental arc platform.

María Gabriela Mángano; Luis Alberto Buatois

1997-01-01

72

Petrographic composition, sedimentary structures and palaeocurrent analysis in Northern Gondwana: The Lower Permian Warchha Sandstone of the Salt Range, Pakistan  

NASA Astrophysics Data System (ADS)

The Warchha Sandstone is a Lower Permian fluvial succession present in both outcrop and subsurface throughout the Salt Range and the Potwar Basin of Pakistan that originally accumulated in a palaeogeographic setting adjacent to the northern margin of Gondwana. Sandstone beds are feldspatho-quartzose, including dominantly monocrystalline quartz, more K-feldspar than plagioclase, and mainly plutonic and low-grade metamorphic rock fragments. Twenty-eight fining-upward cycles, composed of conglomerate, sandstone, siltstone and claystone are identified. A varied range of sedimentary structures is recognised, including different forms of cross-bedding, ripple marks, flute casts, load casts, desiccation cracks, rain prints, cone-in-cone structures, and a variety of types of concretions and bioturbation. The occurrence and abundance of these structures varies in a systematic manner throughout the vertical thickness of the succession. Sedimentary structures, palaeocurrent data and lithofacies arrangement indicate deposition in a high-sinuosity meandering river system. Detailed palaeocurrent analysis reveals a broad unimodal palaeoflow within each cycle with dominant flow direction having been towards the north-northwest, but with significant changes in local bedform migration direction between each cycle. The northward flowing river transported sediments from the Aravalli and Malani Ranges that lay to the south to the Salt Range, northwards to the Tethyan proto-ocean in the north.

Ghazi, Shahid; Mountney, Nigel P.

2012-10-01

73

Triassic vegetation and geography of the New Zealand portion of the Gondwana supercontinent  

NASA Astrophysics Data System (ADS)

Middle Triassic (Ladinian) coal measures of the Torlesse Supergroup cropping out in three separate areas of the South Island (Tank Gully, Long Gully, and Benmore Dam) have yielded a variety of impressions of fossil leaves, fructifications, logs, and root traces. Natural associations of these plant fossils are thought to represent several kinds of coastal vegetation: Pachydermophylletum (mangrove), Linguifolietum (swamp woodland), and Dicroidietum odontopteroidium (mesophytic woodland). Judging from associated sedimentary rocks, these narrow coastal plains were dissected by powerful braided streams and hedged in by a fold mountain range of alpine proportions, largely composed of quartzofeldspathic sandstones. The low diversity of the fossil flora and the presence of possible ice-disrupted paleosols and of ferruginized fossil logs with growth rings are indications of a humid, cool temperate paleoclimate. Plant fossils are very rare in Triassic shallow marine rocks of the Murihiku Supergroup, but a considerable amount of material from numerous localities has accumulated in museum collections over the past century. These fossils include plant chaff incorporated in prodeltaic, graded beds of sandstone and siltstone. Large leaves and fructifications from shaly beds rich in marine invertebrates may have settled from flotsam. Fossil plants found are mainly representative of coastal plant associations better known in Triassic rocks elsewhere in New Zealand and Australia. In Early to Middle Triassic (Scythian and Anisian) rocks these include the Dicroidietum zuberi (floodplain forest and coastal heath) and Taeniopteretum lentriculiformis (river and delta levee scrub); and in Middle and Late Triassic (Ladinian to "Rhaetian") rocks, the Pachydermophylletum (mangrove) and Linguifolietum (swamp woodland). Considering the composition of these sedimentary rocks, the coast from which the plants were derived was geologically complex and included active andesitic volcanoes. The fossil plants are very similar to those of the Sydney Basin, New South Wales, and the Torlesse Supergroup, New Zealand, and like these, probably lived in a humid, cool temperate paleoclimate. The close similarity between Triassic fossil plants of New Zealand and other parts of the Gondwana supercontinent is evidence that both the Torlesse and Murihiku supergroups formed in different parts of the southeastern Gondwanian coast. Juxtaposition of the Torlesse and Murihiku supergroups is more likely a result of transcurrent shuffling of continental terranes than of collision of microcontinents or island arcs.

Retallack, G. J.

74

Current status and remaining problems on the early Gondwana break-up: A geophysical perspective  

Microsoft Academic Search

The opening of the Atlantic and Indian ocean sector of teh southern ocean is in general sufficiently documented. The general geometry of the Gondwana super continent before the break-up is well constrained. Looking into details into the models, there are large gaps in our knowledge on the timing of the break-up and its relationship to the onshore volcanism. New aeromagnetic

W. Jokat

2003-01-01

75

Evolution of the APWP for Gondwana: constraints based on the geology of eastern Australia  

Microsoft Academic Search

The many iterations of the APWP for Gondwana over the past 40 years will be reviewed. They involve all the uncertainties that challenge the determination of the correct record: nature of NRM; age and correlation; geography and history of tectonic units etc. Most arguments about the Paleozoic section of this path depend upon the interpretation of results from the various

J. C. Briden; M. W. McElhinny

2004-01-01

76

A tectonic reconstruction of accreted terranes along the paleo-Pacific margin of Gondwana  

NASA Astrophysics Data System (ADS)

The southern oceanic margin of Gondwana was nearly 40,000 km long or 24,854.8 miles. The southern margin was the result of the Terra Australis orogen. Spanning 18,000 km or 11,184.7 miles and is proposed as one of the largest and longest lived orogens in Earth history. The paleo-Pacific margin of Gondwana consisted of segments of the Australian-Antarctic craton, southern South America (modern Argentina and Chile), southern South Africa, Marie Byrdland, New Zealand and its adjacent continental shelf, the Ellsworth Mountains, and the Transantarctic Mountains. The process of terrane accretion has played a substantial part in the assembly of the continents as they look today. The paleo-Pacific margin of Gondwana was an active region of terrane accretion from the Neoproterozoic to the Late Mesozoic. This research study examines the accretion of terranes across the paleo-Pacific Gondwana margin to provide a comprehensive reconstruction. A paleogeographic basemap was created using PALEOMAP Project maps and the geology data was provided by the School of Geoscience from the University of Witwatersrand of South Africa. Location and data analyzed for terranes were collected building a PDF library of journal articles across numerous geological publications.

Bammel, Brandon

77

A review of the Late Cambrian (Furongian) palaeogeography in the western Mediterranean region, NW Gondwana  

Microsoft Academic Search

The Cambrian–Ordovician transition of the western Mediterranean region (NW Gondwana) is characterized by the record of major erosive unconformities with gaps that range from a chronostratigraphic stage to a series. The hiatii are diachronous and involved progressively younger strata along the Gondwanan margin, from SW (Morocco) to NE (Montagne Noire). They can be related to development of a multi-stage rifting

J. Javier Álvaro; Annalisa Ferretti; Cristina González-Gómez; Enrico Serpagli; M. Franco Tortello; Marco Vecoli; Daniel Vizcaïno

2007-01-01

78

Early Paleozoic orogenesis along Gondwana's northern margin constrained by provenance data from South China  

NASA Astrophysics Data System (ADS)

The Cambrian-Ordovician boundary unconformity in the southern part of the South China Craton is spatially and temporally related to coeval orogenic activity along the Indian margin of east Gondwana. Detrital zircon age spectra from strata above and below the unconformity range in age from 3580-450 Ma, with peaks in the late Mesoproterozoic and Neoproterozoic. The patterns are similar to time equivalent sequences elsewhere in South China and together with regional facies relationships and paleocurrent data indicate derivation from a Gondwana source. The disconformity at the base of the Ordovician succession forms part of a regional break that has also been documented in the Himalaya, Qiangtang, Lhasa, Sibumasu, and Western Australia. All these successions have similar detrital zircon age spectra suggesting derivation from common source(s). In South China the effects of this tectonic event are relatively mild and are represented by a local disconformity at the base of the Ordovician succession, but elsewhere in north Gondwana this event is marked by an angular unconformity with metamorphism of older units and relatively widespread magmatic activity. South China was likely located in a distal location to the northeast of the pulse of tectonic activity, which was focused in the Himalaya region, and was close to the continent-ocean boundary between northern Gondwana and the proto-Tethys.

Xu, Yajun; Cawood, Peter A.; Du, Yuansheng; Huang, Hongwei; Wang, Xinyu

2014-12-01

79

Characterization and evaluation of stress and heavy metal tolerance of some predominant Gram negative halotolerant bacteria from mangrove soils of Bhitarkanika, Orissa, India  

Microsoft Academic Search

In the present study both Gram positive and Gram negative bacteria were isolated using enrichment media from five different stations from mangroves soils of Bhitarkanika, Orissa, India. Among the bacterial populations studied, the Gram negative bacterial population was found to be more in all the stations. Out of several Gram negative bacterial isolates, six predominant and morphologically distinct isolates were

Rath B

80

Post-traumatic stress disorder in children and adolescents one year after a super-cyclone in Orissa, India: exploring cross-cultural validity and vulnerability factors  

Microsoft Academic Search

BACKGROUND: It has been asserted that psychological responses to disasters in children and adolescents vary widely across cultures, but this has rarely been investigated. The objectives of the study were to clinically evaluate the construct of traumatic stress symptoms and disorder in children and adolescents after a super-cyclone in Orissa, India; to find out the prevalence at one year; compare

Nilamadhab Kar; Prasanta K Mohapatra; Kailash C Nayak; Pratiti Pattanaik; Sarada P Swain; Harish C Kar

2007-01-01

81

Short Report: Environmental Vibrio Cholerae O139 May Be the Progenitor of Outbreak of Cholera in Coastal Area of Orissa, Eastern India, 2000: Molecular Evidence  

Microsoft Academic Search

Cholera has been reported in the state of Orissa, India during the past decades. An outbreak of diarrheal disease occurred during November 1 to November 9, 2000 in Rusi- pada village near Puri, which was inhabited by a population of approximately 560. During the outbreak, Vibrio cholerae O139 strains were isolated from clinical specimens collected from patients with acute diarrhea

Hemant Kumar Khuntia; Bibhuti Bhusan Pal; Prem Kumar Meher; Guru Prasad Chhotray

2008-01-01

82

Chromium Bioaccumulation in Rice Grown in Contaminated Soil and Irrigated Mine Wastewater—A Case Study at South Kaliapani Chromite Mine Area, Orissa, India  

Microsoft Academic Search

The level of chromium (Cr) contamination in soils and irrigated mine wastewater at South Kaliapani chromite mine region of Orissa, (India) were investigated. Chromium bioaccumulation in rice plants (Oryza sativa L. cv. Khandagiri) irrigated with Cr contaminated mine wastewater was analyzed along with its attenuation from mine wastewater. The levels of Cr in irrigated mine wastewaters in successive rice grown

Monalisa Mohanty; Mousumi Madhusmita Pattnaik; Aruna Kumari Mishra; Hemanta Kumar Patra

2011-01-01

83

Non-Formal Education--A Worthwhile Alternative to the Formal Education in India? Case Studies from Ganjam, Orissa. Reprints and Miniprints, No. 757.  

ERIC Educational Resources Information Center

This report discusses the advantages and disadvantages of non-formal education (NFE) compared to the formal school system in Ganjam, a rural district on the east coast of Orissa, India. The aim of the research was to investigate whether or not NFE, would be a worthy target of aid from the Swedish aid organization SIDA (Swedish International…

Svensson, Anna

84

Child Feces Disposal Practices in Rural Orissa: A Cross Sectional Study  

PubMed Central

Background An estimated 2.5 billion people worldwide lack access to improved sanitation facilities. While large-scale programs in some countries have increased latrine coverage, they sometimes fail to ensure optimal latrine use, including the safe disposal of child feces, a significant source of exposure to fecal pathogens. We undertook a cross-sectional study to explore fecal disposal practices among children in rural Orissa, India in villages where the Government of India's Total Sanitation Campaign had been implemented at least three years prior to the study. Methods and Findings We conducted surveys with heads of 136 households with 145 children under 5 years of age in 20 villages. We describe defecation and feces disposal practices and explore associations between safe disposal and risk factors. Respondents reported that children commonly defecated on the ground, either inside the household (57.5%) for pre-ambulatory children or around the compound (55.2%) for ambulatory children. Twenty percent of pre-ambulatory children used potties and nappies; the same percentage of ambulatory children defecated in a latrine. While 78.6% of study children came from 106 households with a latrine, less than a quarter (22.8%) reported using them for disposal of child feces. Most child feces were deposited with other household waste, both for pre-ambulatory (67.5%) and ambulatory (58.1%) children. After restricting the analysis to households owning a latrine, the use of a nappy or potty was associated with safe disposal of feces (OR 6.72, 95%CI 1.02–44.38) though due to small sample size the regression could not adjust for confounders. Conclusions In the area surveyed, the Total Sanitation Campaign has not led to high levels of safe disposal of child feces. Further research is needed to identify the actual scope of this potential gap in programming, the health risk presented and interventions to minimize any adverse effect. PMID:24586864

Majorin, Fiona; Freeman, Matthew C.; Barnard, Sharmani; Routray, Parimita; Boisson, Sophie; Clasen, Thomas

2014-01-01

85

Quantification of groundwater recharge in a hard rock terrain of Orissa: a case study.  

PubMed

A study was carried out to select the best method to estimate groundwater recharge in a hard rock terrain. Various standard empirical methods, soil-moisture balance method, water table fluctuation (WTF) method and commonly adopted norms set by Groundwater Estimation Committee (GEC), Govt of India were used to estimate recharge for the Munijhara watershed in the Nayagarh block of Orissa (India). The empirical formulae gave recharge rates ranging from 13 cm to 32 cm/year with average of 22.4 cm and standard deviation of 5.34, independent of other influencing factors like soil, topography and geology. The soil-moisture balance study indicated that recharge is more dependent on the continuous heavy rainfall total annual volume of rainfall. Recharge was limited at up to 10 mm per day, possibly due to presence of hard rock below the soil surface. The rise in water table depth was 3.45 m to 5.35 m with a mean rise of 4.5 m during the year 2006-2007. Annual groundwater recharge based on the WTF approach varied from 10.3 to 16.85 cm with a mean of 13.5 cm, standard deviation of 1.57 cm and coefficient of variation 11.57%. This recharge accounted for 8 to 14% of rainfall received. With a water budget approach based on GEC norms, recharge was calculated as 17 cm per year. The study showed that the magnitudes of annual groundwater recharge as estimated by the WST method and GEC norms are in conformity with other recent findings in India under the same climate conditions. Based on the results recharge structures could be planned in suitable locations to reduce fallow areas under the watershed. PMID:19717920

Sethi, Ranu Rani; Kumar, A; Sharma, S P

2009-01-01

86

Mesozoic break-up of SW Gondwana: implications for regional hydrocarbon potential of the southern South Atlantic  

Microsoft Academic Search

This work provides new palinspastic palaeofacies reconstructions of SW Gondwana incorporating rotation of a Falkland\\/Malvinas microplate. We discuss the implications of this for the tectonic evolution of the southern South Atlantic and hence for the regional hydrocarbon potential.Existing Gondwana reconstructions display good fits of major continents but poorly constrained fits of microcontinents. In most continental reconstructions, the Falkland\\/Malvinas Plateau was

David Macdonald; Irene Gomez-Perez; Juan Franzese; Luis Spalletti; Lawrence Lawver; Lisa Gahagan; Ian Dalziel; Chris Thomas; Nigel Trewin; Malcolm Hole; Douglas Paton

2003-01-01

87

Processing and Analysis of Hyperspectral Fingerprints to Characterise Haematite of Singbhum Iron Ore Belt, Orissa, India  

NASA Astrophysics Data System (ADS)

The demand for iron ore has been increasing in the recent years, thereby requiring the adoption of fast and accurate approaches to iron ore exploration and its grade-assessment. It is in this context that hyperspectral sensing is deemed as a potential tool. This paper examines the potential of hyperspectral fingerprints in the visible, NIR and SWIR regions of the EMR to assess the grades of haematite of the western Singhbhum iron ore belt of Orissa, eastern India, in a rapid manner. Certain spectro-radiometric measurements and geochemical analysis were carried out and the results have been presented. From the spectral measurements, it is seen that the strength of reflectance and absorption at definite wavelength regions is controlled by the chemical composit ion of the iron ores. It is observed that the primary spectral characteristics of these haematites lie in the 650-750 nm, 850 to 900 nm and 2130-2230 nm regions. The laboratory based hyperspectral fingerprints and multiple regression analysis of spectral parameters and geochemical parameters (Fe% and Al2O3%) predicted the concentration of iron and alumina content in the haematite. A very strong correlation (R2 = 0.96) between the spectral parameters and Fe% in the haematite with a minimum error of 0.1%, maximum error of 7.4% and average error of 2.6% is observed. Similarly, a very strong correlation (R2 = 0.94) between the spectral parameters and Al2O3% in the iron ores with a minimum error of 0.04%, maximum error of 7.49% and average error of 2.5% is observed. This error is perhaps due to the presence of other components (SiO2, TiO2, P2O etc.) in the samples which can alter the degree of reflectance and hence the spectral parameters. Neural network based multi-layer perception (MLP) analysis of various spectral parameters and geochemical parameters helped to understand the relative importance of the spectral parameters for predictive models. The strong correlations (Iron: R2 = 0.96; Alumina: R2 = 0.94) indicate that the laboratory hyperspectral signatures in the visible, NIR and SWIR regions can give a better estimate of the grades of haematite in a rapid manner.

Magendran, T.; Sanjeevi, S.

2014-12-01

88

Influence of language and ancestry on genetic structure of contiguous populations: A microsatellite based study on populations of Orissa  

PubMed Central

Background We have examined genetic diversity at fifteen autosomal microsatellite loci in seven predominant populations of Orissa to decipher whether populations inhabiting the same geographic region can be differentiated on the basis of language or ancestry. The studied populations have diverse historical accounts of their origin, belong to two major ethnic groups and different linguistic families. Caucasoid caste populations are speakers of Indo-European language and comprise Brahmins, Khandayat, Karan and Gope, while the three Australoid tribal populations include two Austric speakers: Juang and Saora and a Dravidian speaking population, Paroja. These divergent groups provide a varied substratum for understanding variation of genetic patterns in a geographical area resulting from differential admixture between migrants groups and aboriginals, and the influence of this admixture on population stratification. Results The allele distribution pattern showed uniformity in the studied groups with approximately 81% genetic variability within populations. The coefficient of gene differentiation was found to be significantly higher in tribes (0.014) than caste groups (0.004). Genetic variance between the groups was 0.34% in both ethnic and linguistic clusters and statistically significant only in the ethnic apportionment. Although the populations were genetically close (FST = 0.010), the contemporary caste and tribal groups formed distinct clusters in both Principal-Component plot and Neighbor-Joining tree. In the phylogenetic tree, the Orissa Brahmins showed close affinity to populations of North India, while Khandayat and Gope clustered with the tribal groups, suggesting a possibility of their origin from indigenous people. Conclusions The extent of genetic differentiation in the contemporary caste and tribal groups of Orissa is highly significant and constitutes two distinct genetic clusters. Based on our observations, we suggest that since genetic distances and coefficient of gene differentiation were fairly small, the studied populations are indeed genetically similar and that the genetic structure of populations in a geographical region is primarily influenced by their ancestry and not by socio-cultural hierarchy or language. The scenario of genetic structure, however, might be different for other regions of the subcontinent where populations have more similar ethnic and linguistic backgrounds and there might be variations in the patterns of genomic and socio-cultural affinities in different geographical regions. PMID:15694006

Sahoo, Sanghamitra; Kashyap, VK

2005-01-01

89

Early Cambrian granitoids of North Gondwana margin in the transition from a convergent setting to intra-continental rifting (Ossa-Morena Zone, SW Iberia)  

NASA Astrophysics Data System (ADS)

Two distinct Cambrian magmatic pulses are recognized in the Ossa-Morena Zone (SW Iberia): an early rift-(ER) and a main rift-related event. This Cambrian magmatism is related to intra-continental rifting of North Gondwana that is thought to have culminated in the opening of the Rheic Ocean in Lower Ordovician times. New data of whole-rock geochemistry (19 samples), Sm-Nd-Sr isotopes (4 samples) and ID-TIMS U-Pb zircon geochronology (1 sample) of the Early Cambrian ER plutonic rocks of the Ossa-Morena Zone are presented in this contribution. The ER granitoids (Barreiros, Barquete, Calera, Salvatierra de los Barros and Tablada granitoid Massifs) are mostly peraluminous granites. The Sm-Nd isotopic data show moderate negative ?Ndt values ranging from -3.5 to +0.1 and TDM ages greatly in excess of emplacement ages. Most ER granitoids are crustal melts. However, a subset of samples shows a transitional anorogenic alkaline tendency, together with more primitive isotopic signatures, documenting the participation of lower crust or mantle-derived sources and suggesting a local transient advanced stage of rifting. The Barreiros granitoid is intrusive into the Ediacaran basement of the Ossa-Morena Zone (Série Negra succession) and has yielded a crystallization age of 524.7 ± 0.8 Ma consistent with other ages of ER magmatic pulse. This age: (1) constrains the age of the metamorphism developed in the Ediacaran back-arc basins before the intrusion of granites and (2) defines the time of the transition from the Ediacaran convergent setting to the Lower Cambrian intra-continental rifting in North Gondwana.

Sánchez-García, T.; Pereira, M. F.; Bellido, F.; Chichorro, M.; Silva, J. B.; Valverde-Vaquero, P.; Pin, Ch.; Solá, A. R.

2014-07-01

90

New constraints on the structure and evolution of the eastern margin of Gondwana from ambient noise Rayleigh wave anisotropic tomography  

NASA Astrophysics Data System (ADS)

The Tasmanides of Australia represent the eastern third of the Australian continent that formed along the eastern margin of Gondwana through tectonic events that took place from early Palaeozoic to Cretaceous. In southeast Australia, where the Tasmanides are represented by the Delamerian and Lachlan orogens, most of the complex geological structure inherited from those events lies below Cenozoic basins and Quaternary volcanic deposits, and is therefore not accessible via direct observation. In this work, we exploit the ambient noise wavefield recorded by the largest transportable seismic array experiment in the southern hemisphere, which has operated in eastern Australia from 1998 to present and involves the deployment of over 700 temporary stations with an average interstation distance of about 50 km. We analyze Rayleigh wave phase dispersion curves obtained in a previous study on more than 8,200 cross-correlograms using data from 450 sites, and we perform an anisotropic tomography inversion for periods ranging from 1 to 20 s in order to account for the apparent dependence of Rayleigh wavespeed on azimuthal propagation direction. While the isotropic velocity maps are in good agreement with previous tomographic studies, the anisotropic component of the velocity field brings new constraints on the crustal structure and Phanerozoic evolution of the Tasmanides in southeast Australia. One of the most remarkable results of our study is to show a fast axis of anisotropy almost mimicking the magnetic lineations which appear to wrap around a region now referred to as the Hay-Booligal Zone. That region, recently identified on the basis of high resolution aeromagnetic maps, has been interpreted as a remnant fragment of Precambrian lithosphere embedded within the Lachlan Orogen, possibly originating from the break-up of Rodinia.

Arroucau, Pierre; Rawlinson, Nicholas; Young, Mallory; Salmon, Michelle

2014-05-01

91

A Cambrian Arc Built on the Neoproterozoic Rifted Margin of Gondwana  

NASA Astrophysics Data System (ADS)

Cambrian convergence along the northeastern side of the Curnamona Craton, the Gondwana margin in southeastern Australia, resulted in the development of the Delamerian Orogen. A Neoproterozoic rifted margin, marked by the alkalic Mount Arrowsmith Volcanics, forms the substrate on which is built a NE-facing Cambrian arc, complete with a clearly delineated inner imbricate accretionary prism (the Wonnaminta Zone) and outer thin-skinned wedge (the Kayrunnera Zone). Arc volcanism, represented by the calc-alkaline Mount Wright Volcanics, exhibits mixed arc-rift geochemistry. Interpretation and modelling of magnetic data reveals a chain of volcanic edifices of the Mount Wright Arc, now below 3 to 7 km of Devonian sandstones in the Bancannia Trough. Remarkably, a simple rotation around an Euler pole reconstructs the Wonnaminta Zone against the craton, and aligns structural elements on the two sides of the trough. Arc volcanism evidently occupied a rift in marginal continental crust, and the geometry, geochemistry and geophysical properties of the Mount Wright Arc are closely analogous to the Taupo Zone of New Zealand. Rifting of the arc divided Delamerian structures, indicating that at least part of the Delamerian deformation developed in a subduction accretion setting, rather than in some terminal collision. Below the Wonnaminta Zone a 3 to 5 km thick body can be traced as a large magnetic source along the length of the zone. Overridden by the thrust stack of the accretionary prism, this body is mostly planar and dips towards the east, although it is deformed into a broad antiform in the central part of the zone. Physical properties suggest that this body may be a thick rift-volcanic pile equivalent to the Mount Arrowsmith Volcanics. In the southern part of the belt a re-entrant in the Wonnaminta Zone faces a large magnetic anomaly sourced in the basement of the Kayrunnera Zone. The geometry of the re-entrant, and the development of Silurian and Devonian basins over the surrounds, suggests analogy with structures observed in modern accretionary margins associated with the subduction of seamounts. Bounding the Kayrunnera Zone to the northeast is the Thomson Orogen, a Neoproterozoic to early Palaeozoic structural zone largely covered by Mesozoic sediments. Deformation by the Late Ordovician to Silurian Benambran Orogeny affects both the Kayrunnera Zone and the Thomson Orogen. Seismic reflection indicates overprinted NE and SE facing thrusts below the Kayrunnera Zone, and deformation features project both towards and away from the Thomson Orogen. A plausible explanation interprets the Benambran Orogeny as an arc-arc collision between the Mount Wright Arc and a Thomson Arc. Propagation of the frontal thrust of the Thomson Arc resulted in capture of former Mount Wright fore-arc. This abstract is published with the permission of the Director, Geological Survey of NSW, Department of Industry & Investment.

Musgrave, R. J.

2009-12-01

92

Geological appraisal over the Singhbhum-Orissa Craton, India using GOCE, EIGEN6-C2 and in situ gravity data  

NASA Astrophysics Data System (ADS)

The gravity field and derivatives generated with the high resolution EIGEN-6C2 gravity model which includes satellite gravity data of GOCE (Gravity field and steady-state Ocean Circulation Explorer) has been utilized for geological appraisal of the Singhbhum-Orissa Craton, India. The GOCE only field gravity data and in situ gravity data of the same area have been utilized for comparative assessment to validate the results derived by EIGEN-6C2 gravity data. The GOCE and EIGEN-6C2 Bouguer gravity data have been generated from GOCE and EIGEN-6C2 Free-air gravity data, respectively, after removing topography effect. The result shows that correlation coefficient and covariance between the Bouguer gravity anomaly distribution of in situ and EIGEN-6C2 data of the entire study area are 0.68 and 93.9 mgal2, respectively. The GOCE field compares well to the terrestrial derivative fields in the long-wavelength part of the signal. Further, EIGEN-6C2 and in situ Bouguer gravity data have been analyzed using the 1st and 2nd Vertical Derivatives, Analytical Signal and Tilt Derivative mapping techniques. Published geological and structural maps of the area have been overlapped over different derivative maps and the analytical signal map to analyze the correlation with the subsurface geology and geological structures of the area. Major distinct geological signatures, on different derivative maps and analytical signal map, are correlated well with the existing geological map. The TDR derived from the EIGEN-6C2 Bouguer anomaly has been used to map geologic contacts. The source boundaries and depths are determined from the zero contours, and the half distance between ±?/4 contours or the distance between zero and +?/4 or -?/4 contour of TDR, respectively. The gravity data generated from EIGEN-6C2 model provides sufficient resolution for understanding of the geological setting of the Singhbhum-Orissa Craton.

Pal, S. K.; Majumdar, T. J.

2015-03-01

93

Impact of 1999 Orissa Cyclone on Dynamics and Heat Budget of the Bay of Bengal  

NASA Astrophysics Data System (ADS)

The impacts of two consecutive strong tropical cyclones (TCs) - 04B and 05B in 1999 - on dynamics, thermodynamics and mixed-layer processes of the Bay of Bengal (BoB) are examined using Hybrid Coordinate Ocean Model (HYCOM). This research is composed of three unique features: a) testing the influence of strong stratification and salinity gradient of the BoB, b) examining the ocean response to a sequence of two TCs and season change, and c) examining the effect of individual TC-associated forcings by adopting Lanczos filtering method. HYCOM is driven by ERA-Interim reanalysis data, CCMP wind and TRMM 3B42 rain rate. A series of experiments are performed in order to isolate the effects of each cyclone and their individual forcings. Due to the slow translation velocity and rapid intensification as both the cyclones approach the seashore of Orissa, India, sea surface temperature (SST) decreases the most on the cyclone track, instead of to the right of the track. Mixed layer thickness is largely deepened along the TC tracks except near Ganges river mouth, where fresh river water discharge results in strong stratification. The land-sea contrast introduces evident temperature and humidity diurnal cycle to the BoB, and increases surface turbulent heat flux (sensible and latent flux) variations. On the other hand, intraseasonal variability and upcoming cold season after the TC events hamper the recovery of SST to its pre-storm values. The impact of the TCs on turbulent heat flux in the BoB accounts for substantial proportion of its monthly climatologic value. The results from the experiment run that adopts modified Rankine Vortex for the wind of 04B and 05B, which are significantly underestimated by ERA-Interim reanalysis data, exhibits much stronger SST response. TMI observations show that the SST decreases by more than 2.5 K in the eastern, northwestern and western BoB after 05B diminishes, and in the meantime increases slightly at the center. Our model SST resembles the lower SST area in the eastern and northwestern BoB. For the top 50 m, the BoB loses ~500x10^18 J, while below 50 m gains ~1600x10^18J. Surface turbulent heat flux is ~450x10^18 J upward (~92% of the total loss). Despite the enhanced downward turbulent heat flux, the model result suggests that 05B causes the sea surface to lose heat (~5.3x10^18 J) from late October to the end of 1999 when also considering radiative flux, which is ~21% of the OHC decrease for the BoB. The other ~79% is attributed to merdional OHC flux along 10°N southern boundary. Our simulations also suggest that two consecutive TCs result in 68% less surface energy loss of the top 50m than the sum of two stand-alone TCs. The comparisons between the simulations with TC-associated forcings and without TC-associated forcings show that surface shortwave radiative flux dominates the SST decrease over the eastern BoB water in the early stage of 05B, while wind stress-induced warm water advection mitigates it. Although TC-associated wind stress predominately reduce SST and enhance downward turbulent heat flux through mixing process over the northwestern BoB water in the later stage of 05B, the reduced downward solar radiation by the TC clouds significantly decreases the heat into the ocean. The overall effect of each forcing is not linearly additive.

Wang, J.; Han, W.

2011-12-01

94

Foraminiferal assemblages and geochemistry for interpreting the incidence of Early Toarcian environmental changes in North Gondwana palaeomargin (Traras Mountains, Algeria)  

NASA Astrophysics Data System (ADS)

The Early Toarcian was characterised by important environmental changes and a mass extinction event usually related to a global oceanic anoxic event. The analysis of ecostratigraphic fluctuations of foraminiferal morphogroups, elemental geochemical proxies and C and O stable isotopes of the Mellala section (Tlemcen Domain, North Algeria) makes it possible to determine the incidence of the anoxic event in this sector of the north Gondwana palaeomargin. The end of the Pliensbachian is characterised by a diverse foraminiferal assemblage with equilibrium species suggesting good oxygen and nutrient availability. The beginning of the Toarcian (Polymorphum Zone) evidences major changes in foraminifera with the disappearance of species, decreasing proportions of epifauna and shallow infauna, and fluctuations in diversity and dominance of Lenticulina toarcense and Lingulina tenera confirming a perturbation in the palaeoecological conditions in the sea-bottom. Redox proxies (Co/Al, Cr/Al and V/Al) with local maximum values suggest a decrease in oxygenation degree. A negative excursion of ?13C is recorded right at the Polymorphum/Levisoni Zone boundary, and the subsequent disappearance of epifauna, decreasing diversity and abundance of foraminifera (foram/100 g) would be related to the accentuation of stressing conditions. Also at the Polymorphum/Levisoni Zone boundary, suboxic waters at the sea-bottom indicate the maximum values of redox proxies (Co/Al, Cu/Al, Cr/Al and V/Al). The upper part of the Levisoni Zone is more calcareous, with increasing diversity of shallow infauna and a decrease in potentially deep infauna related to more favourable conditions. The incidence of the Toarcian Oceanic Anoxic Event in this context was very low in comparison with the Saharan Basin (Raknet El Kahla section, Saharan Atlas), where a benthic barren interval, higher total organic carbon and redox proxies are recorded. The low incidence of the biotic crisis and the rapid recovery of assemblages in the Tlemcen Domain is compared with the high incidence and delayed recovery in the Saharan Basin, where the palaeogeography determined restricted water circulation between the Saharan Craton and the Oran Massif.

Reolid, Matías; Marok, Abbas; Sèbane, Abbes

2014-07-01

95

Geological and geometrical constraints on reconstructions of Gondwana: implications for the derivation of Gondwanan fragments in Asia  

SciTech Connect

The relative positions of east (India, Madagascar, Antarctica, Australia, etc.) and west (Africa, S. America, Arabia) Gondwana remains controversial. The authors present a new reconstruction based on (1) tight fit of Madagascar within the Somalian embayment which satisfies both sea-floor spreading data, and Karoo and older geology: (2) a tight fit of India against a reconstructed Africa-Arabian margin, such that the east stepping margin south of Socotra is matched with the east stepping re-entrant of the Suliaman Range east of Quetta; (3) a two-phase motion history of east and west Gondwana characterized by initial NW-SE spreading, followed by essentially N-S motion parallel with the Davies Ridge. Although rifting occurred episodically within Gondwana from the Carboniferous onwards, sea floor spreading did not occur until early late Jurassic and was characterized by long right lateral transform-short ridge geometry. Break-up of E and W Gondwana succeeded early Middle Jurassic spreading along the northern margin of Gondwana from at least Oman to New Guinea. Spreading directions preserved off northwest Australia suggest that motions of the rifted fragments was directed toward the northwest into Tethys. This suggests that the Lhasa, central Pamir, Sistan, Lut (.), and Central Iranian Plateau blocks which collided with Asia after the Jurassic were derived from the southeast, as opposed to the SW as generally portrayed.

Rowley, D.B.; Ziegler, A.M.; Sahagian, D.; Nie, S.Y.; Lottes, A.L.; Jacobs, D.; Hulver, M.

1985-01-01

96

A review of the Late Cambrian (Furongian) palaeogeography in the western Mediterranean region, NW Gondwana  

NASA Astrophysics Data System (ADS)

The Cambrian-Ordovician transition of the western Mediterranean region (NW Gondwana) is characterized by the record of major erosive unconformities with gaps that range from a chronostratigraphic stage to a series. The hiatii are diachronous and involved progressively younger strata along the Gondwanan margin, from SW (Morocco) to NE (Montagne Noire). They can be related to development of a multi-stage rifting (further North), currently connected to the opening of the Rheic Ocean, and concomitant erosion on southern rift shoulders. The platforms of this margin of Gondwana occupied temperate-water, mid latitudes and were dominated by siliciclastic sedimentation, while carbonate factories were only episodically active in the Montagne-Noire platform. The Upper Cambrian is devoid of significant gaps in the southern Montagne Noire and the Iberian Chains. There, the sedimentation took place in a transgressive-dominated depositional system, with common offshore deposits and clayey substrates, and was bracketed by two major regressive trends. The Late Cambrian is also associated with the record of volcanic activity ( e.g., in the Cantabrian and Ossa-Morena zones, and the northern Montagne Noire), and widespread development of a tectonic instability that led to the episodic establishment of palaeotopographies and record of slope-related facies associations. Several immigration events are recognized throughout the latest Middle Cambrian, Late Cambrian and Tremadocian. The trilobites show a stepwise replacement of Acado-Baltic-type families ( e.g., the conocoryphid-paradoxidid-solenopleurid assemblage) characterized by: (i) a late Languedocian (latest Middle Cambrian) co-occurrence of Middle Cambrian trilobite families with the first anomocarid, dorypygid and proasaphiscid invaders; (ii) a Late Cambrian immigration replacing previous faunas, composed of trilobites (aphelaspidids, catillicephalids, ceratopygids, damesellids, eulomids, idahoiids, linchakephalids, lisariids, onchonotinids, and pagodiids), linguliformean brachiopods (acrotretids, obolids, scaphelasmatids, siphonotretids, and zhanatellids), echinoderms (mitrates, glyptocystitid cystoids, and stromatocystoids), and conodonts belonging to the lower Peltura Zone; and (iii) the subsequent input of new trilobites (asaphids, calymenids, catillicephalids, nileids and remopleurids), which marks the base of the Proteuloma geinitzi Zone, associated with pelmatozoan holdfasts ( Oryctoconus), and a distinct input of late Tremadocian conodonts ( Paltodus deltifer Zone). The biogeographic distribution of latest Middle and Late Cambrian trilobites supports brachiopod data indicating strong affinities between the western Mediterranean region, East Gondwana (North China/Korea, South China, Australia, and Antarctica) and Kazakhstania during the late Languedocian, which became significantly stronger during the Late Cambrian. This major shift may suggest modification in oceanic circulation patterns throughout Gondwana across the Middle-Late Cambrian transition.

Álvaro, J. Javier; Ferretti, Annalisa; González-Gómez, Cristina; Serpagli, Enrico; Tortello, M. Franco; Vecoli, Marco; Vizcaïno, Daniel

2007-11-01

97

Ediacaran to Cambrian oceanic rocks of the Gondwana margin and their tectonic interpretation  

NASA Astrophysics Data System (ADS)

In tectonic maps of Variscan Europe, allochthonous pieces of Cadomian basement clearly stand out with their predominant metabasic to ultrabasic elements, the so-called exotic terranes with ophiolites. Most of these domains are observed in basements of the Central Iberian Allochthone, the South Armorican domain, the nappe structures of the French Massif Central, the Saxothuringian Zone and the Bohemian Massif. Similar relics can be recognized in many Alpine basement areas, and correlations with supposedly more autochthonous basements, such as the Ossa Morena Zone and the Central Iberian basement, can be envisaged. All of these relics are thought to represent the interrupted trace of a former continuous or discontinuous structure, characterized by the presence of ocean-derived proto-Rheic rock suites. These can be interpreted as pieces of former magmatic arcs of Ediacaran to Cambrian age accreted to the Gondwana margin, which later were scattered as allochthonous units during the Variscan plate-tectonic processes. The presence of similar rock suites of Ordovician age in the Alpine realm is explained by the accretion of exotic China-derived basements and their collision with the Gondwana margin during the opening of the Rheic Ocean.

von Raumer, Jürgen F.; Stampfli, Gérard M.; Arenas, Ricardo; Sánchez Martínez, Sonia

2015-01-01

98

Regional tectonic framework of the Pranhita Godavari basin, India  

NASA Astrophysics Data System (ADS)

The Pranhita-Godavari Gondwana rift (PGR) has a co-genetic relationship with Permo-Triassic reactivation of the Narmada-Son Geofracture (NSG). The Satpura Gondwana basin represents the terminal depocentre against the NSG, which restricted the northwestward propagation of the PGR. The NE-SW tensional stress responsible for the NW-SE trending PGR could not propagate beyond the ramp formed by uplift along the NSG and transformed kinetically into an ENE directed horizontal shear along the NSG, inducing large scale strike-slip movements. The latter dynamics were responsible for ENE extension of the Satpura rift as a pull-apart basin. The PGR extends up to the present east coast of India, where it is apparently terminated by the NE-SW trending Bapatla ridge along the Eastern Ghat Rift (EGR). The subsurface data, however, shows that the PGR extends across the Bapatla ridge and continues beneath the Cretaceous-Tertiary sediments of the Krishna-Godavari basin (KG) in the EGR. Thus, the Permo-Triassic PGR appears to have continued in the Indo-Antarctic plate before the Cretaceous break up. The EGR, during break up of the continents, cuts across the PGR and the KG basin was superimposed on it. The PGR site is located on a paleo-suture between the Dharwar and Bastar proto-cratons. The master faults developed bordering the rift, and the intra-rift higher order faults followed the pre-existing fabric. The transverse transfer zones manifested as basement ridges, divide the rift into segments of tectono-sedimentary domains. The major domains are the Chintalapudi, Godavari, and Chandrapur sub-basins, each of which subsided differentially. The central Godavari sub-basin subsided most and shows maximum structural complexity and sediment accommodation. The rifting started with initial half-graben faulting along the northeastern master fault and expanded by successive half graben faulting. This gave rise to intra-basinal horsts and grabens, which exercised control on the syn-rift sedimentation. The southeastern boundary fault developed as a strike-slip fault in response to plate rotation and the rift expansion was constrained by it.The basin fill sediments were deposited during two rifting events—Early Permian to (?) Early Jurassic Lower Gondwana rifting, and Early Cretaceous Upper Gondwana rifting. The Lower Gondwana sedimentation started with a pre-rift crustal sagging over the rift site and was filled by glaciogenic Talchir sediments. This was followed by syn-rift-fluvial sedimentation in repeating cycles during the early to late rift stages. Early Cretaceous Chikiala and Gangapur sediments were deposited during the Upper Gondwana rifting. The fluvial cycles were tectonically controlled during each rift stage. The absence of igneous intrusions indicates that the PGR is a passive rift in contrast to the rifts developed in the NSG zone.

Biswas, S. K.

2003-03-01

99

Environmental pollution in rural areas of Orissa state due to industrial emissions--with special reference to fluoride.  

PubMed

Angul - Talcher belt in Central Orissa, having a number of industries contributing to a great extent to deteriorate the air quality of the surrounding villages. Previous reports showed higher SPM, SO2, NO, levels in air and prevalence of respiratory illness, skin and teeth disorders among village population. Higher ground water fluoride, urine and serum fluoride among the cattle were also reported in some villages. Present study reports SPM, SO2, NOx and Fluorides (gaseous and Particulate) in ambient air around aluminium smelter during February and August 1996. High volume sampling technique for SPM and the standard colorimetric methods (BIS) for analyses of SO2 and NOx were adopted. Fluoride in air and water were estimated by standard fluoride ion selective electrode method. Higher SPM, SO2 and NOx values than prescribed CPCB standard were obtained in February. Gaseous fluoride in village air were varied between, 1.66 - 7.64 mg/m3 in February and 1.11 - 22.75 mg/m3 in August, whereas particulate fluoride ranged between, 0.054 - 19.61 mg/m3. Water sources of the villages near the smelter showed fluoride values above permissible limit. The study indicated higher fluoride pollution in air and water of the surrounding villages. PMID:15527028

Mukherjee, A K; Ravichandran, B; Bhattacharya, S K; Ahmed, S; Roy, S K; Thakur, S; Roychowdhury, A; Saiyed, H N

2003-10-01

100

Neoproterozoic to Palaeozoic assembly, dismemberment and assembly of Peri-Gondwana -recorded in (East Avalonian) Anglesey (Ynys Môn), NW Wales, UK  

NASA Astrophysics Data System (ADS)

Late Neoproterozoic accretion at the outboard margin of East Avalonian Gondwana is recorded on Anglesey in ca. 650 Ma metamorphism in the Coedana Complex and the ca. 615 Ma supra-subduction zone Coedana Granite. Iapetan extension fragmented that assembly, crustal thinning is recorded in Anglesey by ca. 560 Ma exhumation of the Penmynydd Zone blueschists. Anglesey's present architecture is however largely a product of accretionary collisions that commenced in the Early Ordovician when coaxial to intensely non-coaxial deformation assembled those Late Neoproterozoic rocks with the Middle Cambrian (to earliest? Ordovician) Monian Supergroup greenschist facies metasediments. In western Anglesey, the Monian Supergroup rocks record NW-facing coaxial D1 deformation sheared by SE-vergent, strongly non-coaxial, D2/D3 strain after an intervening episode of mafic magmatism. In northern Anglesey, Monian Supergroup rocks record only SE-facing deformation from the onset of collision. Deformed ocean floor and slices of garnetiferous basement gneiss are located between these structurally distinct regions and imply separation of these Monian tracts prior to earliest-Arenig? onset of Caledonian collision and accretion. This deformation is contemporaneous with Penobscottian accretion in the northern Appalachians and Newfoundland. The Monian rocks were at surface (and deeply weathered?) before sub-aerial eruption of the (mid-Arenig?) Church Bay Tuff Formation. These acid to intermediate tuffs are overlain unconformably by an Upper Arenig to Llandovery marine transtensional foreland basin succession. Renewed convergence resulted in a SSE-vergent (late-Salinic?) fold and thrust imbricate stack; locally, thrusts override molasse deposits derived from an advancing thrust sheet. Active over-riding of tectonic molasse is continued in Anglesey until the Early Devonian at least. The axially sourced fluvial Old Red Sandstone of central eastern Anglesey is arranged in south-vergent folds and thrusts during Acadian deformation. The geology of Ynys Môn showcases the geometrical complexity of the continental fragments that make up late-Neoproterozoic to Palaeozoic peri-Gondwana, and of the punctuated extensional and compressional deformations that affected the exterior of that continental assembly. This fragment of the UK Caledonides provides an important trans-Atlantic link to the Appalachian geology of North America.

Leslie, Graham; Schofield, David; Wilby, Phil

2014-05-01

101

A Gigantic Sarcopterygian (Tetrapodomorph Lobe-Finned Fish) from the Upper Devonian of Gondwana (Eden, New South Wales, Australia)  

PubMed Central

Edenopteron keithcrooki gen. et sp. nov. is described from the Famennian Worange Point Formation; the holotype is amongst the largest tristichopterids and sarcopterygians documented by semi-articulated remains from the Devonian Period. The new taxon has dentary fangs and premaxillary tusks, features assumed to be derived for large Northern Hemisphere tristichopterids (Eusthenodon, Hyneria, Langlieria). It resembles Eusthenodon in ornament, but is distinguished by longer proportions of the parietal compared to the post-parietal shield, and numerous differences in shape and proportions of other bones. Several characters (accessory vomers in the palate, submandibulars overlapping ventral jaw margin, scales ornamented with widely-spaced deep grooves) are recorded only in tristichopterids from East Gondwana (Australia-Antarctica). On this evidence Edenopteron gen. nov. is placed in an endemic Gondwanan subfamily Mandageriinae within the Tristichopteridae; it differs from the nominal genotype Mandageria in its larger size, less pointed skull, shape of the orbits and other skull characters. The hypothesis that tristichopterids evolved in Laurussia and later dispersed into Gondwana, and a derived subgroup of large Late Devonian genera dispersed from Gondwana, is inconsistent with the evidence of the new taxon. Using oldest fossil and most primitive clade criteria the most recent phylogeny resolves South China and Gondwana as areas of origin for all tetrapodomorphs. The immediate outgroup to tristichopterids remains unresolved – either Spodichthys from Greenland as recently proposed, or Marsdenichthys from Gondwana, earlier suggested to be the sister group to all tristichopterids. Both taxa combine two characters that do not co-occur in other tetrapodomorphs (extratemporal bone in the skull; non-cosmoid round scales with an internal boss). Recently both ‘primitive’ and ‘derived’ tristichopterids have been discovered in the late Middle Devonian of both hemispheres, implying extensive ghost lineages within the group. Resolving their phylogeny and biogeography will depend on a comprehensive new phylogenetic analysis. PMID:23483884

Young, Ben; Dunstone, Robert L.; Senden, Timothy J.; Young, Gavin C.

2013-01-01

102

New exploration strategy for the Vlaming Sub-basin of the Perth Basin, Australia  

SciTech Connect

The offshore Vlaming Sub-basin is a major Mesozoic depocenter lying within the Perth Basin in Western Australia. Bounded by N-S trending faults between Pre-Cambrian blocks, the sub-basin formed as a rift basin associated with the breakup of Gondwana. Early Neocomian faulting, related to this rifting event, is responsible for the structural grain presently observed in the sub-basin. Faulting was followed by regional uplift, which resulted in a major Neocomian Unconformity. A total of 16 wells have been drilled in the sub-basin, resulting in the discovery of a non-commercial oil accumulation within a thin, lower Neocomian sandstone. Many of the wells were designed to target structures associated with palaeo-highs on the Neocomian Unconformity. Our dry-hole analysis shows that these plays are vulnerable to leakage through cap rocks of poor quality. Our new study has revealed that the relatively-unexplored Upper and Middle Jurassic Yarragadee Formation is favorably placed to entrap liquid hydrocarbons. The upper part of the Yarragadee Formation contains highly permeable and porous sandstones even at great depths. Source rocks of the Formation are within the oil generation window and contain 4% of TOC on average. Significantly, seismic surveys sparsely cover the inshore part of the sub-basin, where the Formation lies at relatively shallow depths and appears to be relatively unfaulted.

Miyazaki, S.; Cadman, S.J. (Bureau of Resource Sciences, Canberra, ACT (Australia))

1996-01-01

103

New exploration strategy for the Vlaming Sub-basin of the Perth Basin, Australia  

SciTech Connect

The offshore Vlaming Sub-basin is a major Mesozoic depocenter lying within the Perth Basin in Western Australia. Bounded by N-S trending faults between Pre-Cambrian blocks, the sub-basin formed as a rift basin associated with the breakup of Gondwana. Early Neocomian faulting, related to this rifting event, is responsible for the structural grain presently observed in the sub-basin. Faulting was followed by regional uplift, which resulted in a major Neocomian Unconformity. A total of 16 wells have been drilled in the sub-basin, resulting in the discovery of a non-commercial oil accumulation within a thin, lower Neocomian sandstone. Many of the wells were designed to target structures associated with palaeo-highs on the Neocomian Unconformity. Our dry-hole analysis shows that these plays are vulnerable to leakage through cap rocks of poor quality. Our new study has revealed that the relatively-unexplored Upper and Middle Jurassic Yarragadee Formation is favorably placed to entrap liquid hydrocarbons. The upper part of the Yarragadee Formation contains highly permeable and porous sandstones even at great depths. Source rocks of the Formation are within the oil generation window and contain 4% of TOC on average. Significantly, seismic surveys sparsely cover the inshore part of the sub-basin, where the Formation lies at relatively shallow depths and appears to be relatively unfaulted.

Miyazaki, S.; Cadman, S.J. [Bureau of Resource Sciences, Canberra, ACT (Australia)

1996-12-31

104

Aeromagnetic legacy of early Paleozoic subduction along the Pacific margin of Gondwana  

USGS Publications Warehouse

Comparison of the aeromagnetic signatures and geology of southeastern Australia and northern Victoria Land, Antarctica, with similar data from ancient subduction zones in California and Japan, provides a framework for reinterpretation of the plate tectonic setting of the Pacific margin of early Paleozoic Gondwana. In our model, the plutons in the Glenelg (south-eastern Australia) and Wilson (northern Victoria Land) zones formed the roots of continental-margin magmatic arcs. Eastward shifting of arc magmatism resulted in the Stavely (south-eastern Australia) and Bowers (northern Victoria Land) volcanic eruptions onto oceanic forearc crust. The turbidites in the Stawell (southeastern Australia) and Robertson Bay (northern Victoria Land zones) shed from the Glenelg and Wilson zones, respectively, were deposited along the trench and onto the subducting oceanic plate. The margin was subsequently truncated by thrust faults and uplifted during the Delamerian and Ross orogenies, leading to the present-day aeromagnetic signatures.

Finn, C.; Moore, D.; Damaske, D.; Mackey, T.

1999-01-01

105

Avian evolution, Gondwana biogeography and the Cretaceous-Tertiary mass extinction event.  

PubMed Central

The fossil record has been used to support the origin and radiation of modern birds (Neornithes) in Laurasia after the Cretaceous-Tertiary mass extinction event, whereas molecular clocks have suggested a Cretaceous origin for most avian orders. These alternative views of neornithine evolution are examined using an independent set of evidence, namely phylogenetic relationships and historical biogeography. Pylogenetic relationships of basal lineages of neornithines, including ratite birds and their allies (Palaleocognathae), galliforms and anseriforms (Galloanserae), as well as lineages of the more advanced Neoves (Gruiformes, (Capimulgiformes, Passeriformes and others) demonstrate pervasive trans-Antarctic distribution patterns. The temporal history of the neornithines can be inferred from fossil taxa and the ages of vicariance events, and along with their biogeographical patterns, leads to the conclusion that neornithines arose in Gondwana prior to the Cretaceous Tertiary extinction event. PMID:11296857

Cracraft, J.

2001-01-01

106

Plume-Lithosphere Interaction in the Ethiopian CFB Province: Breaking up Gondwana  

NASA Astrophysics Data System (ADS)

The Ethiopia-Yemen continental flood basalt (CFB) province formed 30 Ma and today covers some 600,000 sq. km with an approximate total volume of 350,000 sq. km of basalt and associated rhyolite. The majority of lavas were extruded over about 1 my (Baker et al. 1996; Pik et al. 1998) and have not been subject to tectonism, making this area ideal for study of processes associated with continental break-up, mantle plume impacts and CFB magmatism. The Ethiopian province is the youngest of the Mesozoic CFB occurrences associated with break-up of Gondwana, following the Karoo and Ferrar (180-175 Ma), Parana-Etendeka (134- 132 Ma) and Deccan (67-65 Ma) events. In Ethiopia, as with other Gondwana CFB provinces, basalts have been separated into high titanium (HT) and low titanium (LT) series (Pik et al. 1998). Stratigraphic studies indicate HT and LT units erupted contemporaneously so temporal control cannot explain the chemical variations; Pik et al (1998) drew a NE-SW trending line separating the region into HT and LT sub-provinces. Detailed investigation of new study sites along the SW margin of the flood basalt province (Tesfaye 2006) found interlayered LT and HT units indicating more complex spatial controls. Our investigation of Ethiopian CFBs evaluates source and process heterogeneities that could produce voluminous mafic magmatism in these two distinctive series. To first order the mildly alkalic HT lavas have higher incompatible trace element abundances than the tholeiitic LT basalts (Pik et al. 1998, 1999; Keiffer et al. 2004), suggesting derivation of the former by lower degrees of partial melting at greater pressures (Furman et al. 2006). Sr-Nd-Pb isotopic signatures of the LT and HT series largely overlap with one another and with the modern Afar plume; in detail the highest Ti-lavas (HT2 of Pik et al. 1998) are isotopically and geochemically distinct from LT and HT1 basalts, which form a broad continuum in all representations of data. HT2 basalts have mantle-like values of Ba/Rb, Rb/Sr, Ce/Pb, La/Nb whereas LT and HT1 basalts show contributions from enriched mantle or crustal sources. Comparison of Ethiopian CFBs to other Gondwana provinces reveals temporal, and possibly spatial, patterns of basalt genesis. Notably, Ethiopian basalts have lower Sr isotope values than those observed in the other CFB provinces. Ethiopian lavas include the greatest contribution from mantle plume source material relative to enriched mantle and crust, with high He isotopic values that are not observed in the other provinces. Crustal thicknesses in Ethiopia are not anomalously thin, suggesting that gradual lithospheric erosion took place during prolonged break-up of Gondwana over the South African Superplume (e.g., Hawkesworth et al. 1999). Baker et al. 1996, Geochim Cosmochim Acta, 60, 2559-2581; Furman et al 2006, J Geol Soc London, Sp. Pub. 269, 95-119; Hawkesworth et al. 1999, J Af Earth Sci, 28, 239-261; Kieffer et al. 2004, J Petrology, 45, 793-834; Pik et al. 1998, J Volcan Geotherm Res, 81, 91-111; Pik et al. 1999, Geochim Cosmochim Acta 63, 2263-2279; Tesfaye 2006, MS thesis: Addis Ababa University, 106 pp

Plummer, C. L.; Furman, T.

2006-12-01

107

A new glucose-6-phosphate dehydrogenase variant, G6PD Orissa (44 Ala{yields}Gly), is the major polymorphic variant in tribal populations in India  

SciTech Connect

Deficiency of glucose-6-phosphate dehydrogenase (G6PD) is usually found at high frequencies in areas of the world where malaria has been epidemic. The frequency and genetic basis of G6PD deficiency have been studied in Africa, around the Mediterranean, and in the Far East, but little such information is available about the situation in India. To determine the extent of heterogeneity of G6PD, we have studied several different Indian populations by screening for G6PD deficiency, followed by molecular analysis of deficient alleles. The frequency of G6PD deficiency varies between 3% and 15% in different tribal and urban groups. Remarkably, a previously unreported deficient variant, G6PD Orissa (44 Ala{yields}Gly), is responsible for most of the G6PD deficiency in tribal Indian populations but is not found in urban populations, where most of the G6PD deficiency is due to the G6PD Mediterranean (188 Ser{yields}Phe) variant. The K{sup NADP}{sub m} of G6PD Orissa is fivefold higher than that of the normal enzyme. This may be due to the fact that the alanine residue that is replaced by glycine is part of a putative coenzyme-binding site. 37 refs., 2 figs., 3 tabs.

Kaeda, J.S.; Bautista, J.M.; Stevens, D. [Univ. College London Medical School (United Kingdom)] [and others

1995-12-01

108

Metamorphic Evolution of the Main Collisional Suture Zone Between East and West Gondwana  

NASA Astrophysics Data System (ADS)

Petrological and metamorphic constraints from five metamorphic complexes which were exhumed during the collision between East- and West-Gondwana across the main collisional suture zone are presented. These include: (a) Meatiq complex in Eastern Desert of Egypt, (b) Feiran-Solaf complex in Sinai, Egypt (c) Sa'al-Zaghra complex in Sinai, Egypt, (d) Great Ruaha River area in the Mozambique Belt, and (e) Western Dronning Maud Land, East Antarctica. The metamorphic results from these complexes are compared and provide insight into the nature of Pan-African crust formation processes during Gondwana assembly. In this study we present differences and similarities between various field areas in the central collisional suture zone of Gondwana that sheds light on the crustal accretion and supercontinent assembly process from a metamorphic perspective. The Meatiq complex in the Eastern Desert of Egypt consists of a low-grade volcanic arc sequence that covers a higher-grade, biotite-garnet gneiss metamorphic core complex. A sinistral shear zone - the Najd Fault System - separates the high-grade rocks from the low-grade volcanic sequence. The combination between published data and new thermodynamic modeling shows that both the high-grade and the low-grade rocks record single clockwise P -T paths. The peak metamorphic conditions of the high-grade rocks are T = 650-700 oC and P = 7-7.5 kbar, whereas the low-grade rocks record conditions of T = 400-450 oC and P = 3-4 kbar. In Sinai, the Najd Fault System is not exposed due to the voluminous intrusion of ca. 540 Ma post-tectonic granites. However, both the garnet-biotite gneisses of the Feiran-Solaf complex (T = 700-750 oC and P = 7-8 kbar) and the low-grade rocks (T = 400-450 oC and P = 2-3 kbar) of Wadi El Kid record very similar metamorphic conditions and clockwise P -T paths to those in Eastern Desert, Egypt. Conversely, the Sa'al-Zaghra complex shows anticlockwise P-T path with peak conditions of 2.5 kbar and 42 oC. It worth mention that the peak metamorphic age of the Sa'al-Zaghra complex is much older than the Pan-African event (ca. 1100 Ma). In western Dronning Maud Land (Antarctica), a petrological and metamorphic comparison of Mesoproterozoic metabasic rocks on the eastern margin of the Archean Grunehogna Craton and the adjacent Maud Belt, revealed a difference in peak metamorphic conditions from T = 280 ± 30 oC to 710-750 oC and P = 2 ± 1.5 to 8.5-11 kbar over a distance of only 30 km across a major glacial valley. The high-grade PT-constraints derived for the western extreme of the Maud Belt, is very similar to that reported for the eastern Maud Belt dated at ca. 550 Ma. These PT-constraints do not support the presence of a westward decreasing metamorphic field gradient within the Maud Belt as previously proposed. The data presented here suggests that the inferred sub-glacial boundary between the Grunehogna Craton and the Maud Belt, might reflect a major Pan-African thrust, with the Maud Belt representing the continuation of the East African Mozambique Belt into East Antarctica.

Abu-Alam, Tamer; Grosch, Eugene

2013-04-01

109

Late Paleozoic paleolatitude and paleogeography of the Midland basin, Texas  

SciTech Connect

During the Late Pennsylvanian through Early Permian, the Midland basin was located in the low latitudes. In the Desmoinesian (Strawn), the basin was astride the equator; during the Missourian (Canyon), the center of the basin had migrated northward so it was located at 1-2N latitude. In the Virgilian (Cisco), the basin center was located around 2-4N latitude, and by the Wolfcampian, it was positioned at around 4-6N latitude. From the Desmoinesian (312 Ma) through the Missourian (306 Ma), the relative motion of the basin was 63NE. Later during the Virgilian (298 Ma) to Wolfcampian (280 Ma), the direction of motion was 24NE. This change in motion reflects a major tectonic event, occurring between the Missourian and Virgilian, that greatly modifed the movement of the Laurentian (North American) plate. At that time, Laurentia had collided with Gondwana and become part of the supercontinent Pangea. Throughout the late Paleozoic, Laurentia was rotated so the Midland basin was oriented 43{degree} northeast from its current setting. Late Paleozoic paleogeography and paleolatitude controlled the direction of prevailing winds and ocean currents, thereby influencing the distribution of carbonate facies in the Midland basin. Present prevailing winds and ocean currents have been shown to have a major impact on modern carbonate sedimentation and facies distribution in Belize, the Bahamas and Turks, and Caicos. A clearer understanding of how late Paleozoic latitude and geography affected sedimentation helps explain and predict the distribution of carbonates throughout the Midland basin.

Walker, D.A. (Mobil Exploration and Producing U.S., Midland, TX (United States)); Golonka, J. (Mobil Exploration and Producing Services Inc., Dallas, TX (United States)); Reid, A.M.; Reid, S.T. (Consulting Geologist, Midland, TX (United States))

1992-04-01

110

The Break-up of a Long-term Relationship: the Cretaceous Separation of New Zealand from Gondwana  

Microsoft Academic Search

After a prolonged period of convergent margin tectonics in the Late Paleozoic and Mesozoic, resulting in terrane accretion, uplift and erosion of the New Zealand segment of Gondwana, the region saw a rapid change to extensional tectonics in mid-Cretaceous times. The change in regime is commonly marked by a major angular unconformity that separates the older, often strongly-deformed subduction-related ‘basement’

M. G. Laird; J. D. Bradshaw

2004-01-01

111

Filling the Gondwana gaps: new species and new reports of Beatogordius Heinze, 1934 (Nematomorpha) from Australia and Madagascar  

Microsoft Academic Search

We describe two new species of Beatogordius Heinze, 1934 (Nematomorpha), B. australiensis and B. lineatus, from Queensland, Australia. One further species, B. abbreviatus (Villot, 1874), which was known from Reunion, is reported from Madagascar. These new reports extend the range of Beatogordius from Africa and South America to include Madagascar and Australia. Beatogordius was likely distributed over the Gondwana continent prior to the

Andreas Schmidt-Rhaesa; Malcom S. Bryant

2004-01-01

112

The Pangea Problem: Insights from New Permo-Triassic Paleomagnetic Data from Gondwana  

NASA Astrophysics Data System (ADS)

Assuming the widely accepted Pangea reconstruction, the so called ‘A-fit’ wherein the eastern margin of North America abuts northwest Africa (e.g. Bullard et al., 1965), Permian and Triassic paleopoles from Gondwana and Laurasia do not statistically coincide, unless heavy filtering is applied to the existing global paleomagnetic database. Forcing a fit of these paleopoles, while maintaining the internal geometry of the supercontinent, results in an unacceptable overlap of continental elements on the order of 10 degrees (~1000 km). To alleviate this problem, alternative paleogeographies and non-dipole field (NDF) models have been invoked. Alternative reconstructions are unfavorable geologically, as they inevitably require large transformative events (i.e. a 3500 km transcontinental megashear) for which there is little structural evidence. NDF arguments lack a causative mechanism, and undermine a central tenet of paleomagnetism, the geocentric axial dipole (GAD) hypothesis. Given the implications of these solutions, it is important to first examine the possibility that the problem could be an artifact of flawed data, arising from erroneous age assignments or directional biases rooted in local block rotations, shallowed inclinations, unrecognized remagnetizations, etc. Experiments with data filtering add credence to this notion, as cratonic overlap is reduced by using only high-quality paleopoles - but at the expense of severely thinning the dataset. In order to test this hypothesis more rigorously, new high-quality Mid-to-Late Permian and Early Triassic paleomagnetic data have been collected from Argentina. Our sampling strategy targeted volcanics to minimize the effects of inclination shallowing, and AMS/AARM was employed to improve structural control. Coupled thermal/AF demagnetization and rock magnetic experiments were utilized to fully characterize the magnetic components and remanence carriers. Age constraints on the volcanics have been improved with new geochronologic work and early/primary magnetic acquisition is demonstrable through stability tests. These new results refute the necessity of alternative reconstructions or NDF models during Late Permian-Early Triassic time, as the paleomagnetic data allow Gondwana and Laurasia to be restored to a tight ‘A-type’ fit, without producing impossible continental overlap. Thus, alternative reconstructions of Pangea should be restricted to the Late Carboniferous-Early Permian, and the transformative megashearing event must have occurred prior to the Late Permian, if at all.

Domeier, M. M.; van der Voo, R.; Tomezzoli, R.; Torsvik, T. H.; Tohver, E.; Hendriks, B.; Vizan, H.; Dominguez, A. R.

2009-12-01

113

Origin of Nama Basin bitumen seeps: Petroleum derived from a Permian lacustrine source rock traversing southwestern Gondwana  

Microsoft Academic Search

Biodegraded bitumens associated with quartz and calcite veins in the Cambrian Fish River Subgroup sediments of the Nama Group of southern Namibia have a geochemical signature diagnostic for organic matter that was deposited in a saline lacustrine palaeoenvironment. In particular, they contain abundant gammacerane, ?-carotane and 3?-methylhopanes while 24-isopropyl cholestanes and dinosteroids are not detectable. Sealed tube hydrous pyrolysis of

Roger E. Summons; Janet M. Hope; Roger Swart; Malcolm R. Walter

2008-01-01

114

Paired ?34S data from carbonate-associated sulfate and chromium-reducible sulfur across the traditional Lower-Middle Cambrian boundary of W-Gondwana  

NASA Astrophysics Data System (ADS)

In this study, we present the first high-resolution data from coupled ?34S analyses of carbonate-associated sulfate (CAS) and chromium-reducible sulfur (CRS) from three Lower-Middle Cambrian sections in western Gondwana. CAS and CRS were extracted and analyzed from marine dolostone, limestone, and nodular limestone from Spanish and French successions. In parallel, carbonate samples were also analyzed for ?13Ccarb, ?18Ocarb, and major/trace element concentrations (Ca, Fe, Mg, Mn, Sr). ?34SCAS values vary between 17.6‰ and 33.2‰, with a maximum CAS concentration of ca. 900 ppm. ?34SCRS data show a similar broad range between -5.1‰ and 29.7‰, with maximal CRS contents up to ca. 3700 ppm. Notably, there is little stratigraphic variation in the ?34SCAS data in each of the sections confounding inter-basinal chemostratigraphic correlations. Nonetheless, the absolute differences in ?34SCAS between sections as well as variations in CAS and CRS concentrations are attributed to paleoenvironmental differences between proximal and distal parts of the carbonate ramp, as well as effects of subaerial exposure and riverine input. Thus, the generated ?34SCAS data deliver not only valuable paleoecological and paleoenvironmental information, they also illustrate a heterogeneity in the seawater sulfate sulfur isotopic composition of the western Gondwanan ocean. Consequently, the lack of correlation between our Gondwanan ?34SCAS data and time equivalent sections of Laurentia and Siberia is probably not only caused by the absence of an internationally accepted biostratigraphic correlation, but rather supports the view that sulfate was non-conservative anion in seawater during the Cambrian Period.

Wotte, Thomas; Strauss, Harald; Fugmann, Artur; Garbe-Schönberg, Dieter

2012-05-01

115

P- T conditions of the cratonic rocks and Eastern Ghats granulites along the Eastern Ghats Frontal Thrust, Jeypore (Orissa), India  

NASA Astrophysics Data System (ADS)

The Eastern Ghats Frontal Thrust (EGFT) demarcates the boundary between the Archaean/Paleoproterozoic cratonic rocks to the west, and the Meso/Neoproterozoic granulites of the Eastern Ghats Mobile Belt (EGMB) to the east. At Jeypore (Orissa, India), mafic schists and granites of the cratonic domain document a spatial increase in the metamorphic grade from greenschist facies (garnet, clinozoisite - absent varieties) in the foreland to amphibolite facies (clinozoisite- and garnet-bearing variants) progressively closer to the EGFT. Across the EGFT, the enderbite-charnockite gneisses and mafic granulites of EGMB preserves a high-grade granulite facies history; amphibolite facies overprinting in the enderbite-charnockite gneisses at the cratonic fringe is restricted to multi-layered growth of progressively Al, Ti - poor hornblende at the expense of pyroxene and plagioclase. In associated mafic granulites, the granulite facies gneissic layering is truncated by sub-centimeter wide shear bands defined by synkinematic hornblende + quartz intergrowth, with post-kinematic garnet stabilized at the expense of hornblende and plagioclase. Proximal to the contact, these granulites of the Eastern Ghats rocks are intruded by dolerite dykes. In the metadolerites, the igneous assemblage of pyroxene-plagioclase is replaced by intergrown hornblende + quartz ± calcite that define the thrust-related fabric and are in turn mantled by coronal garnet overgrowth, while scapolite is stabilized at the expense of recrystallized plagioclase and calcite. Petrogenetic grid considerations and thermobarometry of the metamorphic assemblages in metadolerites intrusive into granulites and mafic schists within the craton confirm that the rocks across the EGFT experienced prograde heating ( Tmax value ˜650-700 °C at P ˜ 6-8 kbar) along the prograde arm of a seemingly clockwise P- T path. Since the dolerites were emplaced post-dating the granulite facies metamorphism, the prograde heating is correlated with renewed metamorphism of the granulites proximal to the EGFT. A review of available age data from rocks neighboring the EGFT suggests that the prograde heating of the cratonic granites and the re-heating of the Eastern Ghats granulites are Pan - African in age. The re-heating may relate to an Early Paleozoic Pan-Gondwanic crustal amalgamation of older terrains or reactivation along an old suture.

Mahato, Sadhana; Bhattacharya, Abhijit

2010-11-01

116

Ediacaran 2,500-km-long synchronous deep continental subduction in the West Gondwana Orogen.  

PubMed

The deeply eroded West Gondwana Orogen is a major continental collision zone that exposes numerous occurrences of deeply subducted rocks, such as eclogites. The position of these eclogites marks the suture zone between colliding cratons, and the age of metamorphism constrains the transition from subduction-dominated tectonics to continental collision and mountain building. Here we investigate the metamorphic conditions and age of high-pressure and ultrahigh-pressure eclogites from Mali, Togo and NE-Brazil and demonstrate that continental subduction occurred within 20 million years over at least a 2,500-km-long section of the orogen during the Ediacaran. We consider this to be the earliest evidence of large-scale deep-continental subduction and consequent appearance of Himalayan-scale mountains in the geological record. The rise and subsequent erosion of such mountains in the Late Ediacaran is perfectly timed to deliver sediments and nutrients that are thought to have been necessary for the subsequent evolution of sustainable life on Earth. PMID:25319269

Ganade de Araujo, Carlos E; Rubatto, Daniela; Hermann, Joerg; Cordani, Umberto G; Caby, Renaud; Basei, Miguel A S

2014-01-01

117

Geometry and kinematics of the late Proterozoic Angavo Shear Zone, Central Madagascar: Implications for Gondwana Assembly  

NASA Astrophysics Data System (ADS)

This paper documents the 20 to 60 km wide N-S trending Angavo Shear Zone (ASZ) in central Madagascar and its tectonic implications by examining its structural styles, kinematics and geometry. Our study indicates that the ASZ is characterized by at least two ductile Late Proterozoic deformation events (D1 and D2) followed by a brittle neotectonic deformation (D3). The early D1 event produced a regionally extensive S1 foliation, stretching/flattening mineral lineation L1 and symmetrical structural fabrics such as recumbent and isoclinal intra-folial folds (F1), implying a flattening deformation. D1 deformational fabrics are locally overprinted by D2 structures. D2 is characterized by a penetrative S2 foliation, shallow south plunging L2 lineation, asymmetric and sheath folds (F2) consistent with a right lateral sense of movement exhibited by delta- and sigma-type porphyroclast systems and asymmetric boudinage fabrics. D2 represents a non-coaxial flow regime formed in a dextral west over east shear zone during a partitioned transpression in response to east-west-directed compression during the assembly of Gondwana. A close resemblance with the Achankovil shear zone in India is noticed; however the continuation of the ASZ in Africa is uncertain.

Raharimahefa, Tsilavo; Kusky, Timothy M.; Toraman, Erkan; Rasoazanamparany, Christine; Rasaonina, Imboarina

2013-04-01

118

Ediacaran 2,500-km-long synchronous deep continental subduction in the West Gondwana Orogen  

NASA Astrophysics Data System (ADS)

The deeply eroded West Gondwana Orogen is a major continental collision zone that exposes numerous occurrences of deeply subducted rocks, such as eclogites. The position of these eclogites marks the suture zone between colliding cratons, and the age of metamorphism constrains the transition from subduction-dominated tectonics to continental collision and mountain building. Here we investigate the metamorphic conditions and age of high-pressure and ultrahigh-pressure eclogites from Mali, Togo and NE-Brazil and demonstrate that continental subduction occurred within 20 million years over at least a 2,500-km-long section of the orogen during the Ediacaran. We consider this to be the earliest evidence of large-scale deep-continental subduction and consequent appearance of Himalayan-scale mountains in the geological record. The rise and subsequent erosion of such mountains in the Late Ediacaran is perfectly timed to deliver sediments and nutrients that are thought to have been necessary for the subsequent evolution of sustainable life on Earth.

Ganade de Araujo, Carlos E.; Rubatto, Daniela; Hermann, Joerg; Cordani, Umberto G.; Caby, Renaud; Basei, Miguel A. S.

2014-10-01

119

A late Devonian impact event and its association with a possible extinction event on Eastern Gondwana  

NASA Technical Reports Server (NTRS)

Evidence from South China and Western Australia for a 365-Ma impact event in the Lower crepida conodont zone of the Famennian stage of the Late Devonian (about 1.5 Ma after the Frasnian/Famennian extinction event) includes microtektitelike glassy microspherules, geochemical anomalies (including a weak Ir), a probable impact crater (greater than 70 k) at Taihu in South China, and an Ir anomaly in Western Australia. A brachiopod faunal turnover in South China, and the 'strangelove ocean'-like c-delta 13 excursions in both Chinese and Australian sections indicate that at least a regional-scale extinction might have occurred at the time of the impact. A paleoreconstruction shows that South China was very close to and facing Western Australia in the Late Devonian. The carbon isotopic excursions, which occur at the same stratigraphic level in both South China and Western Australia cannot be explained as being coincidental. The c-delta 13 excursions and the brachiopod faunal turnover in South China indicate that there might have been at least a regional (possibly global) extinction in the Lower crepida zone. The impact-derived microspherules and geochemical anomalies (especially the Ir) indicate a Lower crepida zone impact event on eastern Gondwana. The location, type of target rocks, and possibly age of the Taihu Lake crater qualify as the probable site of this Late Devonian impact.

Wang, K.; Geldsetzer, H. H. J.

1992-01-01

120

Sedimentological and sequence stratigraphic analysis of Carboniferous deposits in western Libya: Recording the sedimentary response of the northern Gondwana margin to climate and sea-level changes  

NASA Astrophysics Data System (ADS)

Detailed sedimentological and sequence stratigraphic analysis of Carboniferous (Tournaisian to Moscovian) strata exposed in the north-western Murzuq Basin and southern Ghadames Basin, western Libya, provides new insights into the sedimentary response of the northern Gondwana margin to climate and sea-level change. The Lower Carboniferous Marar and Assedjefar Formations can be divided into five depositional sequences of 3rd order. In total 27 facies types are defined, grouped into four facies associations: offshore shales, shallow marine clastics, fluvial sandstones and marine carbonates. The bulk of the Lower Carboniferous interval is dominated by an alternation of offshore shales and shallow marine clastics, which were deposited during the transgressive and highstand systems tracts. The clastic deposits mostly consist of laterally persistent coarsening and thickening upward cycles with a common succession from basal hummocky cross-stratified sandstones to ripple-laminated sandstones, capped by multidirectional cross-stratified sandstones. Within the lowstand systems tracts, lenticular sandbodies have been identified, which vary in thickness from 1.5 m (ca. 40 m wide) to 50 m (ca. 1.5 km wide). These are interpreted to be fluvial channel complexes based on their geometry, erosive base, and presence of thick stacked sandstones with unidirectional planar and trough cross-bedding, the absence of bioturbation and occurrence of land plant fragments. These channel complexes mostly cut down into offshore shales, and are interpreted to be bound at the base by sequence boundaries. Palaeogeographic maps generated for each lowstand system show the location and palaeoflow direction of these fluvial channel complexes. They are interpreted to represent large incised valleys filled with thick fluvial sandstones. Their identification and distribution indicates repeated exposure of large areas of western Libya, most-likely controlled by major eustatic sea-level changes. The Assedjefar Formation exibits a gradual decrease in coarse clastic sediment supply throughout the Serpukhovian and by the Bashkirian and Moscovian during the deposition of the Dembaba Formation a carbonate depositional system was established. Limestones are dominantly made up of a heterozoan fauna (brachiopods, crinoids, bryozoans, gastropods) and are mostly preserved as shallow marine storm and coastal deposits. It is hypothesised that a local increase in aridity and/or the gradual erosion and decreasing topography of the hinterland mountains, with the resulting reduction in discharge, controlled this shift from clastic to carbonate deposition. Available data indicate that the Murzuq Basin was interconnected with the Ghadames Basin at this time and is a postdepositional basin with respect to the Carboniferous interval. The sedimentological and sequence stratigraphic data from the present study offer new insights into the depositional setting and facies distribution in the Carboniferous, and the recognition of major incised fluvial systems has significant implications in the search for potential Carboniferous hydrocarbon reservoirs in the Murzuq, Ghadames, and Illizi Basins.

Fröhlich, Sebastian; Petitpierre, Laurent; Redfern, Jonathan; Grech, Paul; Bodin, Stéphane; Lang, Simon

2010-06-01

121

Metamorphic Evolution of Selected Pan-African Terrains across central Gondwana  

NASA Astrophysics Data System (ADS)

New petrological and metamorphic constraints from three Pan-African mobile belts across the main collisional suture zone that separates East and West Gondwana are presented. These include: (a) the Wadi Kariem area in Eastern Desert of Egypt, (b) the Wadi Taba-El-Kid in Sinai, Egypt and (c) Western Dronning Maud Land, East Antarctica. The metamorphic results from these three terrains are compared and provide insight into the nature of Pan-African crust formation processes during Gondwana assembly. Thermodynamic modelling in THERMOCALC combined with conventional thermobarometry is used to derive metamorphic PT-estimates. However, we show that for low-grade rocks deriving PT-constraints is challenging and requires a multi-disciplinary thermodynamic modelling approach. In addition, a new thermodynamic solid-solution model is presented for the epidote mineral group, whereby the M2 site contains only Al3+ and Fe3+ and Mn3+ prefers to substitute Al3+ in the M3 site. Pseudosection modelling shows that the substitution process between Fe3+ and Al3+ in the M3 and the M1 sites is sensitive to pressure, which suggests using epidote mineral compositions in geobarometry. Wadi Kariem in the Eastern Desert of Egypt consists of a low-grade volcanic arc sequence that covers a higher-grade, biotite-garnet gneiss metamorphic core complex, namely the Meatiq Complex. A sinistral shear zone, the Najd Fault System, separates the high-grade rocks from the low-grade volcanic sequence. Using pseudosection modelling combined with epidote mineral isopleths, both the high-grade and the low-grade rocks show single clockwise P-T paths. The peak metamorphic conditions of the high-grade rocks are T = 700-750 oC and P = 6-7 kbar, whereas the low-grade rocks record conditions of T = 350-400 oC and P = 3-4 kbar. In Sinai, the Najd Fault System is not exposed due to the voluminous intrusion of ca. 540 Ma post-tectonic granites. However, both the garnet-biotite gneisses of the Taba area (T = 650-700 oC and P = 6 kbar) and the low-grade rocks (T = 400-450 oC and P = 2-3 kbar) of Wadi El Kid record very similar metamorphic conditions and clockwise P-T paths to those in Eastern Desert, Egypt. In western Dronning Maud Land (Antarctica), a petrological and metamorphic comparison of Mesoproterozoic metabasic rocks on the eastern margin of the Archean Grunehogna Craton and the adjacent Maud Belt, revealed a difference in peak metamorphic conditions from T = 280 ± 30 oC to 710-750 oC and P = 2 ± 1.5 to 8.5-11 kbar over a distance of only 30 km across a major glacial valley. The high-grade PT-constraints derived for the western extreme of the Maud Belt, is very similar to that reported for the eastern Maud Belt dated at ca. 550 Ma. These PT-constraints do not support the presence of a westward decreasing metamorphic field gradient within the Maud Belt as previously proposed. The data presented here suggests that the inferred sub-glacial boundary between the Grunehogna Craton and the Maud Belt, might reflect a major Pan-African thrust, with the Maud Belt representing the continuation of the East African Mozambique Belt into East Antarctica.

Abu-Alam, T. S.; Grosch, E. G.

2012-12-01

122

Early to mid Cretaceous vegetation of northern Gondwana - the onset of angiosperm radiation and climatic implications  

NASA Astrophysics Data System (ADS)

Early Cretaceous Northern Gondwana seems to be the cradle of many early flowering plants, especially mesangiosperms that include magnoliids and monocots and basal eudicots. So far our knowledge was based mostly on dispersed pollen and small flowering structures. New fossil finds from Brazil include more complete plants with attached roots, leaves and flowers. Taxonomic studies show that these fossils belonged to clades which are, based on macroscopic characters and molecular data, also considered to be rather basal, such as several members of Nymphaeales, Piperales, Laurales, Magnoliales, monocots (Araliaceae) and Ranunculales. Various parameters can be used in order to understand the physiology and habitat of these plants. Adaptations to climate and habitat are partly mirrored in their root anatomy (evidence of tap roots), leaf size and shape, leaf anatomy including presence of glands, and distribution of stomata. An important ecophysiolocical parameter is vein density as an indicator for the plants' cabability to pump water, and the stomatal pore index, representing the proportion of stomatal pore area on the leaf surface, which is related to the water vapor resistance of the leaf epidermis. During the mid-Cretaceous leaf vein density started to surpass that of gymnosperms, one factor that made angiosperms very successful in conquering many kinds of new environments. Using data on these parameters we deduce that during the late Early to mid Cretaceous angiosperms were already diverse, being represented as both herbs, with aquatic members, such as Nymphaeles, helophytes (e.g. some monocots) and plants that may have grown in shady locations. Other life forms included shrubs and perhaps already small trees (e.g. Magnoliales). These flowering plants occupied various habitats, ranging from xeric (e.g. some Magnoliales) to mesic and shady (e.g. Piperales) or aquatic (e.g. Araceae, Nymphaeales). Overall, it seems that several of these plants clearly exhibited some mechanisms to withstand drought, which in turn let us assume that the climate was characterized by dry and wet seasons.

Coiffard, Clément; Mohr, Barbara

2014-05-01

123

Serbo-Macedonian revisited: A Silurian basement terrane from northern Gondwana in the Internal Hellenides, Greece  

NASA Astrophysics Data System (ADS)

New geochronological and geochemical data on basement orthogneisses from the Vertiskos Unit of the Serbo-Macedonian Massif (SMM), Internal Hellenides, northern Greece, are used in order to constrain the pre-Alpine tectonic history of the basement units in the metamorphic hinterland of the Hellenides. The prevailing rock types in the Vertiskos crystalline basement are coarse-grained biotite augengneisses with subordinate leucocratic muscovite gneisses and two-mica gneisses. Zircon Pb-Pb and U-Pb ages on 20 samples range from 425.9 ± 4.2 Ma to 443.4 ± 5.5 Ma with a mean of 432.2 ± 3.2 Ma and are interpreted as primary crystallisation ages of the basement granites on the basis of the magmatic internal structure of the zircon grains. Trace-element and isotope geochemistry of the gneisses show that they originated in a magmatic-arc setting, but also contain material from pre-existing continental crust. The rocks are slightly peraluminous and some leucocratic gneisses are strongly depleted in incompatible trace elements. The zircon ages document an early Silurian magmatic phase in the Internal Hellenides. The association of lithologies and ages is distinctly different from that of the adjacent basement massifs. This difference in basement provenance and the fact that the Vertiskos Unit is bordered by ophiolitic material both to the west and to the east leads to the conclusion that this part of the SMM is an exotic terrane of northern Gondwanan origin, which was finally accreted to its present position during the Alpine orogeny. The Vertiskos Terrane may have been part of the Hun Superterrane, which evolved at the northern active continental margin of Gondwana in the early Palaeozoic and rifted away from it during the opening of the Rheic Ocean in the Cambrian to Silurian. Parts of this superterrane such as the Vertiskos Terrane are present throughout the Variscan and Alpine orogens.

Himmerkus, F.; Reischmann, T.; Kostopoulos, D.

2009-07-01

124

Episodic growth of the Gondwana supercontinent from hafnium and oxygen isotopes in zircon.  

PubMed

It is thought that continental crust existed as early as 150 million years after planetary accretion, but assessing the rates and processes of subsequent crustal growth requires linking the apparently contradictory information from the igneous and sedimentary rock records. For example, the striking global peaks in juvenile igneous activity 2.7, 1.9 and 1.2 Gyr ago imply rapid crustal generation in response to the emplacement of mantle 'super-plumes', rather than by the continuous process of subduction. Yet uncertainties persist over whether these age peaks are artefacts of selective preservation, and over how to reconcile episodic crust formation with the smooth crustal evolution curves inferred from neodymium isotope variations of sedimentary rocks. Detrital zircons encapsulate a more representative record of igneous events than the exposed geology and their hafnium isotope ratios reflect the time since the source of the parental magmas separated from the mantle. These 'model' ages are only meaningful if the host magma lacked a mixed or sedimentary source component, but the latter can be diagnosed by oxygen isotopes, which are strongly fractionated by rock-hydrosphere interactions. Here we report the first study that integrates hafnium and oxygen isotopes, all measured in situ on the same, precisely dated detrital zircon grains. The data reveal that crust generation in part of Gondwana was limited to major pulses at 1.9 and 3.3 Gyr ago, and that the zircons crystallized during repeated reworking of crust formed at these times. The implication is that the mechanisms of crust formation differed from those of crustal differentiation in ancient orogenic belts. PMID:16452978

Kemp, A I S; Hawkesworth, C J; Paterson, B A; Kinny, P D

2006-02-01

125

Geology and metallogeny of the Ar Rayn terrane, eastern Arabian shield: Evolution of a Neoproterozoic continental-margin arc during assembly of Gondwana within the East African orogen  

USGS Publications Warehouse

The Neoproterozoic Ar Rayn terrane is exposed along the eastern margin of the Arabian shield. The terrane is bounded on the west by the Ad Dawadimi terrane across the Al Amar fault zone (AAF), and is nonconformably overlain on the east by Phanerozoic sedimentary rocks. The terrane is composed of a magmatic arc complex and syn- to post-orogenic intrusions. The layered rocks of the arc, the Al Amar group (>689 Ma to ???625 Ma), consist of tholeiitic to calc-alkaline basaltic to rhyolitic volcanic and volcaniclastic rocks with subordinate tuffaceous sedimentary rocks and carbonates, and are divided into an eastern and western sequence. Plutonic rocks of the terrane form three distinct lithogeochemical groups: (1) low-Al trondhjemite-tonalite-granodiorite (TTG) of arc affinity (632-616 Ma) in the western part of the terrane, (2) high-Al TTG/adakite of arc affinity (689-617 Ma) in the central and eastern part of the terrane, and (3) syn- to post-orogenic alkali granite (607-583 Ma). West-dipping subduction along a trench east of the terrane is inferred from high-Al TTG/adakite emplaced east of low-Al TTG. The Ar Rayn terrane contains significant resources in epithermal Au-Ag-Zn-Cu-barite, enigmatic stratiform volcanic-hosted Khnaiguiyah-type Zn-Cu-Fe-Mn, and orogenic Au vein deposits, and the potential for significant resources in Fe-oxide Cu-Au (IOCG), and porphyry Cu deposits. Khnaiguiyah-type deposits formed before or during early deformation of the Al Amar group eastern sequence. Epithermal and porphyry deposits formed proximal to volcanic centers in Al Amar group western sequence. IOCG deposits are largely structurally controlled and hosted by group-1 intrusions and Al Amar group volcanic rocks in the western part of the terrane. Orogenic gold veins are largely associated with north-striking faults, particularly in and near the AAF, and are presumably related to amalgamation of the Ar Rayn and Ad Dawadimi terranes. Geologic, structural, and metallogenic characteristics of the Ar Rayn terrane are analogous to the Andean continental margin of Chile, with opposite subduction polarity. The Ar Rayn terrane represents a continental margin arc that lay above a west-dipping subduction zone along a continental block represented by the Afif composite terrane. The concentration of epithermal, porphyry Cu and IOCG mineral systems, of central arc affiliation, along the AAF suggests that the AAF is not an ophiolitic suture zone, but originated as a major intra-arc fault that localized magmatism and mineralization. West-directed oblique subduction and ultimate collision with a land mass from the east (East Gondwana?) resulted in major transcurrent displacement along the AAF, bringing the eastern part of the arc terrane to its present exposed position, juxtaposed across the AAF against a back-arc basin assemblage represented by the Abt schist of the Ad Dawadimi terrane. Our findings indicate that arc formation and accretionary processes in the Arabian shield were still ongoing into the latest Neoproterozoic (Ediacaran), to about 620-600 Ma, and lead us to conclude that evolution of the Ar Rayn terrane (arc formation, accretion, syn- to postorogenic plutonism) defines a final stage of assembly of the Gondwana supercontinent along the northeastern margin of the East African orogen. ?? 2007 Elsevier B.V. All rights reserved.

Doebrich, J.L.; Al-Jehani, A. M.; Siddiqui, A.A.; Hayes, T.S.; Wooden, J.L.; Johnson, P.R.

2007-01-01

126

Efficacy of permethrin treated long-lasting insecticidal nets on malaria transmission and observations on the perceived side effects, collateral benefits and human safety in a hyperendemic tribal area of Orissa, India  

Microsoft Academic Search

Studies were conducted on the efficacy of Olyset nets—a long-lasting insecticidal net (LLIN) factory treated with 2% (w\\/w) permethrin on malaria transmission in an area under the influence of pyrethroid susceptible vector species Anopheles culicifacies and A. fluviatilis in Sundargarh District, Orissa, India. The study area comprised 22 villages that were randomized into three clusters and designated as Olyset net,

Surya K. Sharma; Prajesh K. Tyagi; Ashok K. Upadhyay; Mohammed A. Haque; Suman S. Mohanty; Kamaraju Raghavendra; Aditya P. Dash

2009-01-01

127

Provenance of north Gondwana Cambrian-Ordovician sandstone: U-Pb SHRIMP dating of detrital zircons from Israel and Jordan  

USGS Publications Warehouse

A vast sequence of quartz-rich sandstone was deposited over North Africa and Arabia during Early Palaeozoic times, in the aftermath of Neoproterozoic Pan-African orogeny and the amalgamation of Gondwana. This rock sequence forms a relatively thin sheet (1-3 km thick) that was transported over a very gentle slope and deposited over a huge area. The sense of transport indicates unroofing of Gondwana terranes but the exact provenance of the siliciclastic deposit remains unclear. Detrital zircons from Cambrian arkoses that immediately overlie the Neoproterozoic Arabian-Nubian Shield in Israel and Jordan yielded Neoproterozoic U-Pb ages (900-530 Ma), suggesting derivation from a proximal source such as the Arabian-Nubian Shield. A minor fraction of earliest Neoproterozoic and older age zircons was also detected. Upward in the section, the proportion of old zircons increases and reaches a maximum (40%) in the Ordovician strata of Jordan. The major earliest Neoproterozoic and older age groups detected are 0.95-1.1, 1.8-1.9 and 2.65-2.7 Ga, among which the 0.95-1.1 Ga group is ubiquitous and makes up as much as 27% in the Ordovician of Jordan, indicating it is a prominent component of the detrital zircon age spectra of northeast Gondwana. The pattern of zircon ages obtained in the present work reflects progressive blanketing of the northern Arabian-Nubian Shield by Cambrian-Ordovician sediments and an increasing contribution from a more distal source, possibly south of the Arabian-Nubian Shield. The significant changes in the zircon age signal reflect many hundreds of kilometres of southward migration of the provenance. ?? 2006 Cambridge University Press.

Kolodner, K.; Avigad, D.; McWilliams, M.; Wooden, J.L.; Weissbrod, T.; Feinstein, S.

2006-01-01

128

Geothermal structure of Australia's east coast basins  

NASA Astrophysics Data System (ADS)

The east coast sedimentary basins of Australia formed on an active margin of eastern Gondwana, and constitute an important hydrocarbon resource. The 1600km long Sydney-Gunnedah-Bowen Basin (SGBB) is largest east coast basin system, with thick Permian to Jurassic sedimentary successions overlying Palaeozoic basement rocks. The SGBB has been the focus of renewed geothermal exploration interest, however, the thermal state and geothermal potential of the system is largely unconstrained. Geothermal exploration programs require an accurate estimate of subsurface temperature information, in addition to favourable geology, to make informed decisions on potential targe developments. Primarily temperature information comes from downhole measurements, generally non-equilibrated, which are traditionally extrapolated to depth, however such extrapolation does not take into account variations in geological structure or thermal conductivity. Here we import deep 3D geological models into finite element conduction simulations, using the code Underworld, to calculate the deep thermal structure of the basin system. Underworld allows us to incorporate complex, detailed geological architecture models, incorporating different material properties for different layers, with variable temperature and depth-dependent properties. We adopt a fixed top boundary temperature on a variable topographic surface, and vary the bottom surface boundary condition, to converge of models which satisfy equilibrated downhole temperature measurement constraints. We find coal plays an important role in insulating sedimentary basins. Heat refracts around the coal interval and produces elevated temperatures beneath thick sediments, especially where thick coal intervals are present. This workflow has been formalized into an Underworld geothermal model library, enabling model centric computational workflows. Using the imported model architecture from the geology, data can be continuously updated and added to the system and models quickly re-run to take advantage of the most up to date information. The thermal models we’ve produced for the SGBB are an efficient regional assessment of the geothermal resource potential in this basin system.

Danis, C. R.; O'Neill, C.

2010-12-01

129

Structural framework, stratigraphy, and evolution of Brazilian marginal basins  

SciTech Connect

The structural framework of the Brazilian continental margin is basically composed of eight structural types: antithetic tilted step-fault blocks, synthetic untilted step-fault blocks, structural inversion axes, hinges with compensation grabens, homoclinal structures, growth faults with rollovers, diapirs, and igneous structures. The antithetic tilted and synthetic untilted step-fault blocks are considered as synchronous, complementary structural systems, separated by an inversion axis. Two evaporitic cycles (Paripueira and Ibura) were differentiated in the Sergipe-Alagoas type basin and tentatively correlated to the evaporitic section of other Brazilian marginal basis. Four phases are considered in the evolution of the Brazilian marginal basins: pre-rift, rift, transitional, and drift. During the pre-rift phase (Late Jurassic-Early Cretaceous), continental sediments were deposited in peripheral intracratonic basins. In the rift phase (Early Cretaceous), the breakup of the continental crust of the Gondwana continent gave rise to a central graben and rift valleys where lacustrine sediments were deposited. The transitional phase (Aptian) developed under relative tectonic stability, when evaporitic and clastic lacustrine sequences were being deposited. In the drift phase (Albian to Holocene), a regionl homoclinal structure developed, consisting of two distinct sedimentary sequences, a lower clastic-carbonate and an upper clastic. From the Albian to the Holocene Epoch, structures associated to plastic displacement of salt or shale developed in many Brazilian marginal basins. Two phases of major igneous activity occurred: one in the Early Cretaceous associated with the rift phase of the Gondwana continent, and the other in the Tertiary during the migration phase of the South American and African plates.

Ojeda, H.A.O.

1982-06-01

130

Isotopic characterisation of the sub-continental lithospheric mantle beneath Zealandia, a rifted fragment of Gondwana  

NASA Astrophysics Data System (ADS)

The greater New Zealand region, known as Zealandia, represents an amalgamation of crustal fragments accreted to the paleo-Pacific Gondwana margin and which underwent significant thinning during the subsequent split from Australia and Antarctica in the mid-Cretaceous following opening of the Tasman Sea and the Southern Ocean. We present Sr, Nd and Pb isotopes and laser ablation trace element data for a comprehensive suite of clinopyroxene separates from spinel peridotite xenoliths (lherzolite to harzburgite) from the sub-continental lithospheric mantle across southern New Zealand. These xenoliths were transported to the surface in intra-plate alkaline volcanics that erupted across the region in the Eocene and Miocene (33-10 m.y.a.). Most of the volcanic suites have similar geochemical and isotopic properties that indicate melting of an OIB-like mantle source in the garnet stability zone and that contained a HIMU component. The volcanics have tapped two adjacent but chemically contrasting upper mantle domains: a fertile eastern domain and an extremely depleted western domain. Both domains underlie Mesozoic metasedimentary crust. Radiogenic isotope compositions of the clinopyroxene have 87Sr/86Sr between 0.7023 to 0.7035, 143Nd/144Nd between 0.5128 and 0.5132 (corresponding to ?Nd between +3 and +13) with a few samples extending to even more depleted compositions, 206Pb/204 Pb between ca. 19.5 to 21.5 and 208Pb/204 Pb between ca. 38.5 to 40.5. No correlations are observed between isotopic composition, age or geographical separation. These isotopic compositions indicate that the sub-continental lithospheric mantle under southern New Zealand has a regionally distinct and pervasive FOZO to HIMU - like signature. The isotopic signatures are also similar to those of the alkaline magmas that transported the xenoliths and suggest that most of the HIMU signature observed in the volcanics could be derived from a major source component in the sub-continental lithospheric mantle. Trace element abundances in clinopyroxene are highly heterogeneous and vary from LREE-enriched, relatively flat and MORB-like, strongly LREE-depleted, through to patterns displaying evidence for depletion and subsequent re-enrichment. These variations occur throughout the region and also between different xenoliths from a single eruption site. There are no clear correlations between REE characteristics and isotopic composition suggesting that much of the depletion and re-enrichment is relatively recent. A broad scatter of increasing 143Nd/144Nd with increasing Sm/Nd, plotting broadly between 150-350 Ma isochrons, may provide some constraints on these events.

Waight, Tod E.; Scott, James M.; van der Meer, Quinten H. A.

2013-04-01

131

Petrography of Permian "Gondwana" coals from boreholes in northwestern Bangladesh, based on semiautomated reflectance scanning  

USGS Publications Warehouse

Drilling through Quaternary alluvium and Tertiary cover at low-gravity anomalies in northwestern Bangladesh showed the presence of Permian sedimentary rocks in depressions that may be as much as a thousand meters deep in the crystalline basement. These Permian strata include low-sulfur, high-volatile bituminous coals in beds as thick as 15 m. The maceral group composition of these coals was determined by semiautomated reflectance scanning with a motorized microscope stage, rather than by point counting. This method was chosen to give objectively recorded raw analytical data and to provide a graphical picture of each sample. The coals are mostly "Gondwana" type (poorly layered "plum pudding" with abundant minerals and inertinite in a vitrinite groundmass) that would be classed as semi-dull (inerto-gelitite) coals. However, six samples have more than 70% vitrinite. None of the samples would be classed as sapropelic (liptinitic). The upper, middle, and lower main seams in borehole GDH-45 were sampled in 10 benches (0.1-3 m thick) each. Inertinite ranges from 7 to 100 vol% (mineral free basis) in individual benches, but composite seam averages are 41, 54 and 67%. Inertinite increases toward the top of two main seams so the bottom would yield the most valuable first mine slices. Some benches with extremely high inertinite content, such as the top 7 m of the lower thick seam, might be mined specially for blending with foreign low-inert coals to increase coke strength. The free swelling index reaches 7.5 in several vitrinite-rich benches, which can indicate good coking coal. Much of the vitrinite is fluorescent, which indicates secondary bituminization characteristic of vitrinite in good coking coals. Ash yields range from 8 to 52%, with composite seam averages of 15, 14 and 24%. Rare visible pyrite is in veinlets or small nodules; framboids and dispersed pyrite are absent. In borehole GDH-40 near Barapukuria (200-500 m depth), the mean random reflectance of vitrinite "A" ranges from 0.60 to 0.80% Ro and vitrinite "B" ranges from 0.55 to 0.65%. In borehole GDH-45 near Khalaspir (287-442 m), the reflectance of vitrinite ranges from 0.79 to 0.94%. In individual cases, the vitrinite is difficult to define because of semivitrinite at higher reflectance (forming a separate peak on several reflectograms) and because of surface bitumen films or resinous (?) inclusions at lower reflectance. On the basis of vitrinite reflectance, the coals can be considered to have entered the "main phase of bitumen generation" of organic thermal maturation as understood in petroleum geochemistry. ?? 1991.

Bostick, N.H.; Betterton, W.J.; Gluskoter, H.J.; Nazrul, Islam M.

1991-01-01

132

Sub-horizontal channel flow: an exhumation mechanism during the Gondwana collision  

NASA Astrophysics Data System (ADS)

The Arabian-Nubian Shield is made up of juvenile crust which was formed due to arc-arc accretion during the East- and West-Gondwana collision (Pan-African event) and the closing of the Mozambique Ocean. Thus the shield is composed of ophiolitic and volcanic material with oceanic affinity. However rocks with continental affinity can be found as high grade metamorphic complexes that were exposed from underneath the arc-related rocks during the late stages of the Pan-African event. Two tectonic models explain the exhumation mechanism of these metamorphic complexes. The first model is exhumation as core complexes in extension setting. This model appears to pertain to the metamorphic complexes of the Eastern Desert of Egypt. The second model is exhumation in oblique transpressional regime as it was found - for example - for the Feiran-Solaf complex of Sinai Peninsula. These models are correct with regard to the structural elements in the outer zones of the metamorphic complexes, which formed during the final exhumation mechanism during the later stages of the deformation history (e.g. D3 of the Feiran complex). However the models cannot explain the sub-horizontal lineations that formed during the early deformation phases and are still recorded in the core of the metamorphic complexes (e.g. D1 of the Feiran-Solaf complex). Here we propose sub-horizontal channel flow as a mechanism to exhume the metamorphic complexes and a mechanism that can account for both types of structural elements as part of one exhumation history. We suggest that the rocks flowed horizontally at mid-crustal levels to the NW of the Arabian-Nubian Shield. The front of the channel flows was then exhumed to the Earth surface in a transpression regime. This middle crustal flow will produce extensional tectonic regime in the upper crust (i.e. ?3 is horizontal and oriented in the NW-SE direction). This extensional setting produces low-angle detachments which assisted the middle crustal rocks to be exhumed as tectonic windows of the Eastern Desert of Egypt. The complexes then can be exhumed completely to the Earth surface in either extensional or oblique transpressional regime depend on the orientation of the principle stresses. Examples from Saudi Arabia will be presented during the EGU2013 to demonstrate this new tectonic model.

Abu-Alam, Tamer; Stüwe, kurt

2013-04-01

133

The Río de la Plata craton and the assembly of SW Gondwana  

NASA Astrophysics Data System (ADS)

The extent and nature of the Archaean-Palaeoproterozoic craton of Río de la Plata of southern South America, a major but poorly understood crustal component in Neoproterozoic plate reconstructions, as well as the depositional, metamorphic and magmatic history of the surrounding orogenic belts, are reviewed and reassessed, in part through the analysis of material recovered from deep boreholes in western Argentina that penetrated Palaeozoic cover into basement. U-Pb SHRIMP zircon ages for these samples of 2162 ± 6 Ma (diorite), 2189 ± 14 Ma (amphibolitic schist) and 2088 ± 6 Ma (granite) encompass the range of ages determined for the major Palaeoproterozoic orogenic events in the exposed parts of the craton close to the Atlantic coasts of Uruguay and Argentina. Taken together with the geochemical and Nd-isotope characteristics of these samples and an olivine gabbro from a further borehole that failed to yield zircon, these results strongly suggest that the Río de la Plata craton is extremely uniform in its dominant chrono-tectonic and lithological make-up, and that it extends westwards as far as the 535-520 Ma Pampean orogenic belt, against which it probably has a fault contact. U-Pb SHRIMP zircon detrital age patterns are presented for representative metasedimentary samples from the craton cover in the Tandilia belt of eastern Argentina, and from the Pampean (Cambrian) and Famatinian (Ordovician) belts to the west of the craton. Whereas the oldest cover rocks in Tandilia clearly show material derived from the underlying craton, such detritus only appears in the younger (Ordovician) units to the west. Sedimentary protoliths in the Pampean belt were dominated by Neoproterozoic (broadly ˜ 600 Ma) and late Mesoproterozoic (broadly ˜ 1100 Ma) provenance, and derivation from the Río de la Plata craton is highly unlikely. Regional considerations, including previously published zircon data, palaeocurrent and structural data, suggest that these rocks must have had an origin within Gondwana-forming blocks, for which the closest identifiable sources are 'Brazilian' and 'African' (Namaqua-Natal). Consequently, the preferred model for the Pampean orogeny is that the Río de la Plata craton reached its present position by large-scale dextral strike-slip movement against fore-arc sedimentary sequences that had developed on the southern and western margins of the Kalahari craton during the Early Cambrian. In the final stage the displaced sedimentary sequences outboard of the RPC collided with the Mesoproterozoic Western Sierras Pampeanas terrane, which was at the time attached to the large Amazonia craton and other smaller continental blocks, such as Arequipa-Antofalla and Río Apa. Protracted relative displacement of the RPC after the Pampean Orogeny led to its final position.

Rapela, C. W.; Pankhurst, R. J.; Casquet, C.; Fanning, C. M.; Baldo, E. G.; González-Casado, J. M.; Galindo, C.; Dahlquist, J.

2007-07-01

134

The evolution of mammal-like crocodyliforms in the Cretaceous Period of Gondwana  

Microsoft Academic Search

Fossil crocodyliforms discovered in recent years have revealed a level of morphological and ecological diversity not exhibited by extant members of the group. This diversity is particularly notable among taxa of the Cretaceous Period (144-65million years ago) recovered from former Gondwanan landmasses. Here we report the discovery of a new species of Cretaceous notosuchian crocodyliform from the Rukwa Rift Basin

Patrick M. O'Connor; Joseph J. W. Sertich; Nancy J. Stevens; Eric M. Roberts; Michael D. Gottfried; Tobin L. Hieronymus; Zubair A. Jinnah; Ryan Ridgely; Sifa E. Ngasala; Jesuit Temba

2010-01-01

135

The largest flying reptile from Gondwana: a new specimen of Tropeognathus cf. T. mesembrinus Wellnhofer, 1987 (Pterodactyloidea, Anhangueridae) and other large pterosaurs from the Romualdo Formation, Lower Cretaceous, Brazil.  

PubMed

A very large pterosaur (MN 6594-V) from the Romualdo Formation (Aptian/Albian), Santana Group, Araripe Basin, is described. The specimen is referred to Tropeognathus cf. T. mesembrinus mainly due to the presence of a low and blunt frontoparietal crest, the comparatively low number of teeth and the inclined dorsal part of the occipital region. Two distinct wingspan measurements for pterosaurs are introduced: the maximized wingspan (maxws), which essentially consists of doubling the addition of all wing elements and the length of the scapula or the coracoid (the smaller of the two), and the normal wingspan (nws), which applies a reducing factor (rfc) to the maximized wingspan to account for the natural flexures of the wing. The rfc suggested for pteranodontoids is 5%. In the case of MN 6594-V, the maxws and nws are 8.70 m and 8.26 m, respectively, making it the largest pterosaur recovered from Gondwana so far. The distal end of a larger humerus (MCT 1838-R) and a partial wing (MPSC R 1395) are also described showing that large to giant flying reptiles formed a significant part of the pterosaur fauna from the Romualdo Formation. Lastly, some comments on the nomenclatural stability of the Santana deposits are presented. PMID:23538956

Kellner, Alexander W A; Campos, Diogenes A; Sayão, Juliana M; Saraiva, Antônio A F; Rodrigues, Taissa; Oliveira, Gustavo; Cruz, Lilian A; Costa, Fabiana R; Silva, Helder P; Ferreira, Jennyfer S

2013-03-01

136

The Choiyoi volcanic province at 34°S-36°S (San Rafael, Mendoza, Argentina): Implications for the Late Palaeozoic evolution of the southwestern margin of Gondwana  

NASA Astrophysics Data System (ADS)

The Choiyoi rhyolitic province of Chile and Argentina (23°S-42°S) was emplaced at the SW margin of Gondwana during the Permian. The San Rafael Massif (Mendoza, Argentina, 34°-36°S), is a key area to analyse the relative timing of Choyoi magmatism and related deformation as it bears one of the most complete and well exposed succession. Stratigraphic, structural and magmatic studies indicate that major changes of geodynamic conditions occurred during the Permian since arc-related sequences syntectonic with transpression (lower Choiyoi) were followed by transitional to intraplate, postorogenic suites coeval with transtension (upper Choiyoi). During the Early Permian, a major event of N-NNW dextral transpressional motions deformed the Carboniferous foreland basin in the San Rafael Massif. This event is attributed to the first episode of the San Rafael orogeny and can be related to oblique subduction (Az. 30°) of the Palaeo-Pacific plate. Ca. 280 Ma the inception of voluminous calc-alkaline volcanism (lower Choiyoi) syntectonic with WNW sinistral transpression of the second episode of the San Rafael orogeny, is associated with an eastward migration of the magmatic arc at this latitude. To the southeast of San Rafael, magmatism and transpression continued to migrate inland suggesting that a progressively younger, WNW, sinistral, thick skinned deformation belt broadens into the foreland and can be traced from San Rafael to Sierra de la Ventana, linking the San Rafael orogeny with the Gondwanide orogeny of the Cape Fold Belt in South Africa. This distribution of magmatism and deformation is interpreted as being the consequence of a progressive shallowing of the Palaeo-Pacific plate starting to the north of San Rafael, and culminating with a flat-slab region south of 36°S. Ca. 265 Ma the onset of predominantly felsic volcanism (upper Choiyoi) in San Rafael occurred in a Post-San Rafael extensional setting. Kinematic indicators and strain fabric analyses of San Rafael orogeny transpression and Post-San Rafael extension show a tectonic reversion. The Post-San Rafael event could be the result of the extensional collapse of the San Rafael orogen, triggered by continental-scale clockwise rotations. These rotations would account for subduction ceasing earlier in the north (31°S-36°S) than in the south, thus explaining the coexistence, after ˜ 265 Ma, of extension in San Rafael with compression in the Sierra de la Ventana-Cape Fold Belt area.

Kleiman, Laura E.; Japas, María S.

2009-08-01

137

Punctuated Caledonian accretion on the fragmented (East Avalonian) Palaeozoic margin of Peri-Gondwana - a record from Anglesey (Ynys Môn), NW Wales, UK  

NASA Astrophysics Data System (ADS)

Late Neoproterozoic accretion at the outboard margin of East Avalonia is recorded on Anglesey in ca. 650 Ma metamorphism in the Coedana Complex, the ca. 615 Ma supra-subduction zone Coedana Granite, and ca. 560 Ma exhumation of the Penmynydd Zone blueschists. However, much of Anglesey's present architecture is a product of accretionary collisions that commenced in the Early Ordovician when coaxial to intensely non-coaxial deformation assembled the Late Neoproterozoic rocks with the Middle Cambrian (to earliest? Ordovician) Monian Supergroup greenschist facies metasediments. In western Anglesey, the Monian Supergroup rocks record initial (D1) NW-facing coaxial deformation but SE-vergent, strongly non-coaxial, D2/D3 strain reorients the earlier structures after an episode of mafic magmatism. In northern Anglesey, Monian Supergroup rocks record only SE-facing deformation from the onset of collision. Deformed mafic igneous rocks and slices of garnetiferous basement gneiss are located between these structurally distinct regions and suggest separation of the Monian tracts prior to the (earliest-Arenig?) onset of collision. This cycle is contemporaneous with Penobscottian accretion in the northern Appalachians and Newfoundland. The Monian rocks were at surface (and deeply weathered?) before sub-aerial eruption of the (mid-Arenig?) Church Bay Tuff Formation. The tuffs are overlain unconformably by a Upper Arenig to Llandovery marine transtensional foreland basin succession. Renewed convergence resulted in a SSE-vergent (late-Salinic?) fold and thrust imbricate stack. Locally, thrusts override molasse deposits derived from an advancing thrust sheet and the basal thrust must have been emergent at the foot of an active fault. This theme of active over-riding of tectonic molasse is continued in Anglesey until the Early Devonian at least. The axially sourced fluvial Old Red Sandstone of central eastern Anglesey is arranged in south-vergent folds and thrusts during Acadian deformation. This fragment of the UK Caledonides is an important trans-Atlantic link to the Appalachian geology of North America. The geology of Ynys Môn serves to remind us of the geometrical complexity of the continental fragments that make up Palaeozoic peri-Gondwana, and of the episodic collision that accompanied punctuated accretion of the orogenic wedge. There is no single key to a solution - only total geology.

Leslie, Graham; Schofield, David; Wilby, Philip

2013-04-01

138

Prepared to react? Assessing the functional capacity of the primary health care system in rural Orissa, India to respond to the devastating flood of September 2008  

PubMed Central

Background Early detection of an impending flood and the availability of countermeasures to deal with it can significantly reduce its health impacts. In developing countries like India, public primary health care facilities are frontline organizations that deal with disasters particularly in rural settings. For developing robust counter reacting systems evaluating preparedness capacities within existing systems becomes necessary. Objective The objective of the study is to assess the functional capacity of the primary health care system in Jagatsinghpur district of rural Orissa in India to respond to the devastating flood of September 2008. Methods An onsite survey was conducted in all 29 primary and secondary facilities in five rural blocks (administrative units) of Jagatsinghpur district in Orissa state. A pre-tested structured questionnaire was administered face to face in the facilities. The data was entered, processed and analyzed using STATA® 10. Results Data from our primary survey clearly shows that the healthcare facilities are ill prepared to handle the flood despite being faced by them annually. Basic utilities like electricity backup and essential medical supplies are lacking during floods. Lack of human resources along with missing standard operating procedures; pre-identified communication and incident command systems; effective leadership; and weak financial structures are the main hindering factors in mounting an adequate response to the floods. Conclusion The 2008 flood challenged the primary curative and preventive health care services in Jagatsinghpur. Simple steps like developing facility specific preparedness plans which detail out standard operating procedures during floods and identify clear lines of command will go a long way in strengthening the response to future floods. Performance critiques provided by the grass roots workers, like this one, should be used for institutional learning and effective preparedness planning. Additionally each facility should maintain contingency funds for emergency response along with local vendor agreements to ensure stock supplies during floods. The facilities should ensure that baseline public health standards for health care delivery identified by the Government are met in non-flood periods in order to improve the response during floods. Building strong public primary health care systems is a development challenge. The recovery phases of disasters should be seen as an opportunity to expand and improve services and facilities. PMID:22435044

Phalkey, Revati; Dash, Shisir R.; Mukhopadhyay, Alok; Runge-Ranzinger, Silvia; Marx, Michael

2012-01-01

139

Factors affecting treatment-seeking for febrile illness in a malaria endemic block in Boudh district, Orissa, India: policy implications for malaria control  

PubMed Central

Background Orissa state in eastern India accounts for the highest malaria burden to the nation. However, evidences are limited on its treatment-seeking behaviour in the state. We assessed the treatment-seeking behaviour towards febrile illness in a malaria endemic district in Orissa. Methods A cross-sectional community-based survey was carried out during the high malaria transmission season of 2006 in Boudh district. Respondents (n = 300) who had fever with chills within two weeks prior to the day of data collection were selected through a multi-stage sampling and interviewed with a pre-tested and structured interview schedule. Malaria treatment providers (n = 23) were interviewed in the district to gather their insights on factors associated with prompt and effective treatment through a semi-structured and open-ended interview guideline. Results Majority of respondents (n = 281) sought some sort of treatment e.g. government health facility (35.7%), less qualified providers (31.3%), and community level health workers and volunteers (24.3%). The single most common reason (66.9%) for choosing a provider was proximity. Over a half (55.7%) sought treatment from appropriate providers within 48 hours of onset of symptoms. Respondents under five years (OR 2.00, 95% CI 0.84-4.80, P = 0.012), belonging to scheduled tribe community (OR 2.13, 95% CI 1.11-4.07, P = 0.022) and visiting a provider more than five kilometers (OR 2.04, 95% CI 1.09-3.83, P = 0.026) were more likely to have delayed or inappropriate treatment. Interviews with the providers indicated that patients' lack of trust in community volunteers providing treatment led to inappropriate treatment-seeking from the less qualified providers. The reasons for the lack of trust included drug side effects, suspicions about drug quality, stock-outs of drugs and inappropriate attitude of the provider. Conclusion Large-scale involvement of less qualified providers is suggested in the malaria control programme as volunteers after appropriate capacity development since the community has more trust in them. This should be supported by uninterrupted supply of drugs to the community volunteers, and involvement of the community-based organizations and volunteers in the planning, implementation, and monitoring of malaria control services. There is also a need for continuous and rigorous impact evaluations of the program to make necessary modifications, scale up and to prevent drug resistance. PMID:21192825

2010-01-01

140

Crustal structure of the Filchner-Ronne shelf and Coats Land, Antarctica, from gravity and magnetic data: Implications for the breakup of Gondwana  

Microsoft Academic Search

Understanding the tectonic evolution of the Weddell Sea embayment provides valuable insights on the breakup of Gondwana. Existing geodynamic models for this region differ mainly in the nature of the crust beneath the Filchner-Ronne shelf and the movement of the Ellsworth-Whitmore Mountains (EWM) crustal block. New gravity data presented here constrain the area and timing of this EWM movement from

Michael Studinger; Heinz Miller

1999-01-01

141

Extreme freshwater release during the late Paleozoic Gondwana deglaciation and its impact on coastal ecosystems  

NASA Astrophysics Data System (ADS)

Strata in the Paganzo, Tarija, and Paraná Basins of Argentina and Brazil provide evidence for reconstructing the effects of late Paleozoic glacial retreat. The depositional environment of the transgressive and early highstand fine-grained deposits has been controversial, with interpretations ranging from normal-marine shelves to estuaries to lakes. Whereas their counterparts from shallow-marine settings not influenced by glaciation host diverse, fully marine ichnofaunas, these fine-grained postglacial deposits are dominated by nonspecialized grazing trails, simple feeding traces, arthropod trackways, and fish trails. They are typical of freshwater environments and represent examples of the Mermia and Scoyenia ichnofacies. However, the local presence of acritarchs indicates sporadic marine influence. These observations suggest a new interpretation, that freshwater conditions in fjordlike settings across South America were widespread because Gondwanan basins were overwhelmed by strong meltwater discharge issuing from melting of the continental ice masses.

Buatois, Luis A.; Netto, Renata G.; Mángano, M. Gabriela; Balistieri, Patricia R. M. N.

2006-12-01

142

Biochemical Characterization and 16S rRNA Sequencing of Few Lipase-Producing Thermophilic Bacteria from Taptapani Hot Water Spring, Orissa, India.  

PubMed

Three lipase-producing thermophilic bacteria (AK-P1, AK-P2, and AK-P3) were isolated from the Taptapani hot water spring in Orissa, India. The crude extra cellular lipases from cell-free culture supernatant were reacted in an olive oil mixture, and their lipolytic activities were compared. Identification of the bacteria was carried out using biochemical tests, 16SrRNA sequencing and sequences submitted to NCBI GenBank. Strain AK-P3, exhibited the highest lipolytic activity of 5.5?U/mL was identified as Porphyrobacter sp. The lipolytic activities of strains AK-P1 and AK-P 2 were 4.5?U/mL and 3.5?U/mL, respectively. Strains AK-P1 and AK-P2 were identified as Acinetobacter sp. and Brevibacillus spp. The GenBank accession numbers of the 16S rRNA gene sequences determined in this study for the strains AK-P1, AK-P2, and AK-P3 are HM359120, HM359119, and HM359118, respectively. PMID:21541249

Bisht, Satpal S; Panda, Amrita K

2011-01-01

143

New Rb-Sr mineral ages temporally link plume events with accretion at the margin of Gondwana  

USGS Publications Warehouse

Five of six Rb-Sr muscovite mineral isochron ages from the Scotia Metamorphic Complex of the South Orkney Islands, West Antarctica, average 190 ± 4 Ma. The muscovite ages are interpreted to date foliation-formation and thus also accretion and subduction at the Gondwana margin. Coincident picrite and ferropicrite magmatism, indicative of melts from deep-seated depleted mantle, permits a causative link between accretion and the arrival of the Karoo – Ferrar – Chon Aike mantle plume in the Early Jurassic. Three biotite Rb-Sr mineral isochron ages are consistently younger and average 176 ± 5 Ma. The biotite ages may record post-metamorphic cooling or more likely retrogressive metamorphic effects during uplift.

Flowerdew, M.J.; Daly, J.S.; Riley, T.R.

2007-01-01

144

Cyclicity and stacking patterns in Carboniferous strata of the Black Warrior Foreland Basin  

SciTech Connect

Cyclicity in Carboniferous stratigraphic successions has long been attributed to tectonism and climate, but the ways these variables interact to determine the architecture of sedimentary basin fills remain a subject of intense debate. Geophysical well logs and cores from the Black Warrior basin were used to test the effects of tectonism and climate on cyclicity and stacking patterns in a foreland-basin setting. The Black Warrior basin formed in Carboniferous time by diachronous tectonic loading of the Alabama continental promontory along the Appalachian-Ouachita juncture. Climatic changes affecting the basin during this time include drift of southeastern North America from the arid southern tradewind belt toward the humid equatorial belt, as well as the onset of a major Gondwana glaciation just prior to the end of the Chesterian. The fill of the Black Warrior basin comprises carbonate and coal-bearing depositional cycles, and the composition, frequency, and stacking patterns of those cycles reflect dynamically interwoven tectonic and climatic factors. Tectonic loading evidently gave rise to flexural movements that determined cycle stacking patterns by controlling spatial and temporal variation of subsidence rate. Evolving tectonic highlands, moreover, fostered a shift from cratonic to orogenic sources of terrigenous elastic sediment, thereby affecting stratal geometry. Climate, by contrast, regulated the composition and frequency of the cycles. The transition from carbonate-bearing cycles with oxidized, calcic paleosols to coal-bearing cycles with reduced, histic paleosols reflects drift of southeastern North America into the humid equatorial belt. Change of average cycle duration from 1.3 m.y. to less than 0.4 m.y. corresponds with the onset of Gondwana glaciation, suggesting significant climatic forcing of sea level variation.

Pashin, J.C. [Geological Survey of Alabama, Tuscaloosa, AL (United States)

1994-09-01

145

Silurian high-pressure granulites from Central Qiangtang, Tibet: Constraints on early Paleozoic collision along the northeastern margin of Gondwana  

NASA Astrophysics Data System (ADS)

High-pressure (HP) granulites are commonly regarded as indicators of plate convergence and collision following the subduction of oceanic or continental crust. In this study we report the discovery of Silurian HP basic granulites from Central Qiangtang on the Tibetan Plateau. Detailed petrology and geochronology reveal a three-stage metamorphic history based on inclusions, reaction textures, and garnet zoning patterns. Peak metamorphism at 830-860 °C and 1.15-1.45 GPa (M1) is defined by high-Ca garnet cores, high-Al clinopyroxene, and high-Na plagioclase. Symplectites or coronas of orthopyroxene + plagioclase ± magnetite around garnet porphyroblasts indicate garnet breakdown reactions at ca. 810-830 °C and 0.65-0.85 GPa (M2). Kelyphites of amphibole + plagioclase around garnet formed during the cooling process at about 590-650 °C and 0.62-0.82 GPa (M3). These results help define a sequential P-T path containing near-isothermal decompression (ITD) and near-isobaric cooling (IBC) stages. Identification of mineral inclusion assemblages in zircons dated by U-Pb SHRIMP and LA-ICP-MS reveals peak HP metamorphism at ca. 427-422 Ma, subsequent near-isothermal decompression with associated retrograde reactions at ca. 392-389 Ma, and continued cooling at ca. 360 Ma. The P-T-t path of HP basic granulites reflects collision followed by extensional exhumation during early Paleozoic orogenesis. The present results indicate the occurrence of a collisional event along the northern margin of Indo-Australian Gondwana during the Silurian. Renewed Gondwana-directed subduction and subsequent collision probably led to the opening of the Paleo-Tethys Ocean.

Zhang, Xiu-Zheng; Dong, Yong-Sheng; Li, Cai; Deng, Ming-Rong; Zhang, Le; Xu, Wang

2014-11-01

146

Deep seismic reflection profiling of sedimentary basins offshore Brazil: Geological objectives and preliminary results in the Sergipe Basin  

NASA Astrophysics Data System (ADS)

The first deep seismic reflection profiles offshore Brazil were acquired in Campos Basin and processed to 10 s TWT in 1984. Starting in 1989, Petrobrás acquired an extensive data set of deep seismic profiles using special acquisition equipment capable of effectively penetrating through the sedimentary layers and imaging the whole crustal architecture. These deep (18 s TWT) seismic reflection profiles extend across the Atlantic-type marginal basins, from the platform to the deepwater province, presently considered frontier regions for petroleum exploration. This work addresses the geological objectives of a deep seismic profile in the Sergipe Basin and discusses the results obtained by integrating regional seismic, gravity and magnetic data. When combined, these data provide evidence that deep seismic reflectors observed in the Sergipe Basin are related to intracrustal-upper mantle structures rather than sedimentary features. The deep seismic reflection profile in the Sergipe Basin also suggests that, rather than a non-volcanic passive margin, the deepwater extension of this basin is marked by several magmatic structures, including thick wedges of seaward-dipping reflectors and volcanic plugs. These magmatic features are associated with basinforming processes resulting from lithospheric extension during the breakup of Gondwana in the Early Cretaceous and subsequent emplacement of oceanic crust. These results are compared to the crustal scale structures observed in the Campos Basin, in the southeastern margin of Brazil. The interpretation of the deep structure of these basins indicates that final separation between the South American and African plates formed passive margins characterized by different patterns of crustal attenuation underlying the rift blocks.

Mohriak, Webster Ueipass; Lira Rabelo, JoséHenrique; De Matos, Renato Darros; De Barros, Mozart C.

1995-12-01

147

Stratigraphy of Midland basin in regional and global context  

SciTech Connect

A new correlation of 85 well logs provides the data for a continuous set of structure and isopach maps covering one square degree of longitude and latitude from 101 to 102 west and 32 to 33 north. A corresponding set of maps showing paleogeography and tectonics relates each of the above maps to its surroundings in the southwest quarter of North America. A further set of maps of the globe then relates the paleogeographic settings to global plate tectonics. The logs were chosen for an even distribution throughout the study areas and they illustrate the stratigraphic development of the Midland basin from the Early Ordovician up to the middle of the Leonardian stage, i.e., up to the union of Gondwana.

Robinson, R.M. (Robinson Drilling of Texas, Big Spring, TX (United States)); Hayner, D. (Greenstar Exploration, Dallas TX (United States))

1994-03-01

148

Geodynamic basin classification  

SciTech Connect

Four criteria (continental margin type, basin position within a plate, crustal type, geodynamic models and processes of basin formation) are used to classify sedimentary basins. Within plate interiors, cratonic margin basins and interior cratonic basins are distinguished by position on a tectonic plate. In passive margins, rift basins, aulacogens, and flexure basins are distinguished by orientation with respect to margins (rifts parallel and aulacogens normal to margins) and geodynamic process (rifts and aulacogens form by stretching, flexure basins by elastic or viscoelastic flexure). Basins associated with active continental margins are distinguished by position with respect to margin, crustal type, and stress regimen. Trench-slope basins involve compressional-extensional regimens, whereas trench basins, forearc basins and retroarc basins form in compressional regimes (retroarc basins on continental crust; forearc and trench basins occupy different positions on margin boundaries). Extensional intra-arc basins form on continental crust whereas backarc basins form by rifting oceanic crust and rapid thermal subsidence. Both pull-apart and transform basins form in transform margins by rifting and thermal subsidence with different translational stress regimens. In collision margins, foreland basins occur within continental plates, and superposed (or collage) basins occur along suture zones. Polyhistory basins include successor basins involving changing tectonic styles, and resurgent basins involving repeated tectonic styles. Many mapped basins show polyhistory. Thus the cratonic Illinois basin evolved through stages of a rift basin, followed by thermal subsidence akin to passive margins, followed by viscoelastic basin formation akin to a foreland basin.

Klein, G.

1987-05-01

149

The effect of improved rural sanitation on diarrhoea and helminth infection: design of a cluster-randomized trial in Orissa, India  

PubMed Central

Background Infectious diseases associated with poor sanitation such as diarrhoea, intestinal worms, trachoma and lymphatic filariasis continue to cause a large disease burden in low income settings and contribute substantially to child mortality and morbidity. Obtaining health impact data for rural sanitation campaigns poses a number of methodological challenges. Here we describe the design of a village-level cluster-randomised trial in the state of Orissa, India to evaluate the impact of an ongoing rural sanitation campaign conducted under the umbrella of India’s Total Sanitation Campaign (TSC).We randomised 50 villages to the intervention and 50 villages to control. In the intervention villages the implementing non-governmental organisations conducted community mobilisation and latrine construction with subsidies given to poor families. Control villages receive no intervention. Outcome measures include (1) diarrhoea in children under 5 and in all ages, (2) soil-transmitted helminth infections, (3) anthropometric measures, (4) water quality, (5) number of insect vectors (flies, mosquitoes), (6) exposure to faecal pathogens in the environment. In addition we are conducting process documentation (latrine construction and use, intervention reach), cost and cost-effectiveness analyses, spatial analyses and qualitative research on gender and water use for sanitation. Results Randomisation resulted in an acceptable balance between trial arms. The sample size requirements appear to be met for the main study outcomes. Delays in intervention roll-out caused logistical problems especially for the planning of health outcome follow-up surveys. Latrine coverage at the end of the construction period (55%) remained below the target of 70%, a result that may, however, be in line with many other TSC intervention areas in India. Conclusion We discuss a number of methodological problems encountered thus far in this study that may be typical for sanitation trials. Nevertheless, it is expected that the trial procedures will allow measuring the effectiveness of a typical rural sanitation campaign, with sufficient accuracy and validity. PMID:23148587

2012-01-01

150

A Megaraptor-like theropod (Dinosauria: Tetanurae) in Australia: support for faunal exchange across eastern and western Gondwana in the Mid-Cretaceous  

PubMed Central

The fossil record of Australian dinosaurs in general, and theropods in particular, is extremely sparse. Here we describe an ulna from the Early Cretaceous Eumeralla Formation of Australia that shares unique autapomorphies with the South American theropod Megaraptor. We also present evidence for the spinosauroid affinities of Megaraptor. This ulna represents the first Australian non-avian theropod with unquestionable affinities to taxa from other Gondwanan landmasses, suggesting faunal interchange between eastern and western Gondwana during the Mid-Cretaceous. This evidence counters claims of Laurasian affinities for Early Cretaceous Australian dinosaur faunas, and for the existence of a geographical or climatic barrier isolating Australia from the other Gondwanan continents during this time. The temporal and geographical distribution of Megaraptor and the Eumeralla ulna is also inconsistent with traditional palaeogeographic models for the fragmentation of Gondwana, but compatible with several alternative models positing connections between South America and Antarctica in the Mid-Cretaceous. PMID:18544511

Smith, Nathan D; Makovicky, Peter J; Agnolin, Federico L; Ezcurra, Martín D; Pais, Diego F; Salisbury, Steven W

2008-01-01

151

Callisto basin  

NASA Technical Reports Server (NTRS)

This picture of a multi=ring basin on Callisto was taken the morning of March 6, 1979, from a distance of about 200,000 km. The complicated circular structure seen at left center is similar to the large circular impact basins that dominate the surface of the Earth's moon and also the planet Mercury. The inner parts of these basins are generally surrounded by radially lineated ejecta and several concentric mountainous ring structures that are thought to form during the impact event. This multi-ring basin on Callisto consists of light floored central basin some 300 k m in diameter surrounded by at least eight to ten discontinuous rhythmically spaced ridges. No radially lineated ejecta can be seen. The ring structures on Moon and Mercury have been likened to ripples produced on a pond by a rock striking the water. The great number of rings observed around this basin on Callisto is consistent with its low planetary density and probable low internal strength. JPL manages and controls the Voyager project for NASA's Office of Space Science.

1979-01-01

152

Thermo-tectonic history of Taranaki Basin (New Zealand) using Apatite Fission Track Analysis (AFTA)  

SciTech Connect

The Taranaki basin, which extends offshore between the north and south island of New Zealand, contains several large gas fields (e.g., Maui field) and smaller oil fields. The Taranaki basin is New Zealand's only productive hydrocarbon basin. The basin trends north-south, is asymmetrical in cross section, and is faulted with up to 7 km of displacement along parts of its eastern margin. Preliminary results from Apatite Fission Track Analysis (AFTA) reveal the timing and magnitude of basin inversion. Four well cross sections from the southern part of the basin have been used. Initially, basin tectonics and sedimentation were associated with extension and the formation of half-grabens that began in the Late Cretaceous with the breakup of Gondwana. However, most of the observed subsidence and sedimentation resulted from mid-Cenozoic rifting throughout western New Zealand. Following the formation of the modern Australia-Pacific plate boundary during the early Miocene, the southern part of the basin, which lies 60 km from the Alpine fault in places, was partially inverted. AFTA parameters (apparent age and length) downhold at the Fresne-1 well show a distinct break in slope at 1,100 m depth (currently at 30/sup 0/C) where the apparent age is 15 Ma for the Late Cretaceous Parkawau Coal Measures. The data indicate that basin inversion began about 15 Ma and was accompanied by the removal of 2-3 km of section. Sedimentation began again in the Taranaki basin during the mid-Pliocene. The source of the gas and gas condensate in the basin is probably the Eocene coal measures. The maturation history of these beds and the overlying reservoirs was modeled using the constraints from AFTA data. Discrepancies exist between estimates of maximum paleotemperature from AFTA results and from vitrinite reflectance.

Kamp, P.J.J.; Hegarty, K.A.; Green, P.F.

1988-01-01

153

Linking the Indochina block and Gondwana during the Early Paleozoic: Evidence from U-Pb ages and Hf isotopes of detrital zircons  

NASA Astrophysics Data System (ADS)

To constrain the paleoposition of Indochina within Gondwana during the Early Paleozoic, we performed in-situ U-Pb and Hf isotope analyses on detrital zircons from three river sediment samples in the Truong Son Belt of the Indochina block. The age distributions yield dominant Neoarchean (~ 2.5 Ga), Mesoproterozoic (1.7-1.4 Ga), Grenvillian (~ 0.95 Ga), and Pan-African (0.65-0.5 Ga) age groups and minor Paleo- to Meso-archean zircons. Hf isotope compositions of zircons for each age group exhibit large ranges of ?Hf(T), suggesting that the zircon host rocks have diverse sources. The oldest Hf model ages for zircons of Neoarchean, Grenvillian, and Pan-African age group yield ~ 3.7 Ga or older, while those of Mesoproterozoic age group show ~ 3.3 Ga. The remarkable similarity of age distribution and Hf isotope compositions among detrital zircons of Indochina and those of Tethyan Himalaya, western Cathaysia, and Qiangtang suggests that Indochina was located outboard of Qiangtang and south of South China in the Indian margin of Gondwana during the Early Paleozoic. Our results are consistent with the paleontological correlations of east Gondwana margin during the Early Paleozoic.

Usuki, Tadashi; Lan, Ching-Ying; Wang, Kuo-Lung; Chiu, Han-Yi

2013-02-01

154

Tectonic and paleoenvironmental evolution of Mesozoic sedimentary basins along the Andean foothills of Argentina (32°-54°S)  

NASA Astrophysics Data System (ADS)

Chronoenvironmental and tectonic charts are presented for Mesozoic basins located along the Andean foothills of the South American plate. On the basis of the main tectonic events, pre-Andean basins, break-up-related basins, extensional back-arc basins, and Andean foreland basins are recognized. The pre-Andean basins were formed by continental extension and strike-slip movement before the development of the Mesozoic-Cenozoic Andean magmatic arc. Upper Permian to Middle Triassic extension along Palaeozoic terrane sutures resulted in rifting, bimodal magmatism (Choiyoi group), and continental deposition (Cuyo basin). From the Late Triassic to the Early Jurassic, continental extension related to the collapse of the Gondwana orogen initiated a series of long, narrow half-grabens that filled with continental volcaniclastic deposits. These depocenters were later integrated into the Neuquén basin. Coeval development of the shallow marine Pampa de Agnia basin (42-44°S) is related to short-lived extension, probably driven by dextral displacement along major strike-slip faults (e.g. the Gastre fault system). Widespread extension related to the Gondwana breakup (180-165 Ma) and the opening of the Weddell Sea reached the western margin of the South American plate. As a result, wide areas of Patagonia were affected by intraplate volcanism (Chon Aike province), and early rifting occurred in the Magallanes basin. The Andean magmatic arc was almost fully developed by Late Jurassic times. A transgressive stage with starvation and anoxia characterized the Neuquén basin. In western Patagonia, back-arc and intra-arc extension produced the opening of several grabens associated with explosive volcanism and lava flows (e.g. R?´o Mayo, El Quemado). To the south, a deep marginal basin floored by oceanic crust (Rocas Verdes) developed along the back-arc axis. In mid-to late Cretaceous times, Andean compressional tectonics related to South Atlantic spreading caused the inversion of previous extensional structures and the beginning of a retro-arc foreland phase in the Neuquén and Austral basins.

Franzese, Juan; Spalletti, Luis; Pérez, Irene Gómez; Macdonald, David

2003-05-01

155

Triassic arc-derived detritus in the Triassic Karakaya accretionary complex was not derived from either the S Eurasian margin (Istanbul terrane) or the N Gondwana margin (Taurides)  

NASA Astrophysics Data System (ADS)

We present new U-Pb zircon source age data for Upper Triassic sandstones of the Istanbul Terrane (S Eurasian margin) and also for Triassic sandstones of the Taurides (N Gondwana margin). The main aim is to detect and quantify the contribution of Triassic magmatism as detritus to either of these crustal blocks. This follows the recent discovery of a Triassic magmatic arc source for the Triassic sandstones of the Palaeotethyan Karakaya subduction-accretion complex (Ustaömer et al. 2013; this meeting). Carboniferous (Variscan) zircon grains also form a significant detrital population, plus several more minor populations. Six sandstone samples were studied, two from the ?stanbul Terrane (Bak?rl?k?ran Formation of the Kocaeli Triassic Basin) and four from the Tauride Autochthon (latest Triassic Üzümdere Formation and Mid-Triassic Kas?mlar Formations; Bey?ehir region). Detrital zircon grains were dated by the laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) U-Pb method at Goethe University, Frankfurt. Our results do not reveal Triassic detritus in the Üzümdere Formation. The U-Pb age of the analysed zircon grains ranges from 267 Ma to 3.2 Ga. A small fraction of Palaeozoic zircons are Permian (267 to 296 Ma), whereas the remainder are Early Palaeozoic. Ordovician grains (4%) form two age clusters, one at ca. 450 Ma and the other at ca. 474 Ma. Cambrian-aged grains dominate the zircon population, while the second largest population is Ediacaran (576 to 642 Ma). Smaller populations occur at 909-997 Ma, 827-839 Ma, 1.8-2.0 Ga and 2.4-2.6 Ga. The sandstones of the Kas?mlar Formation have similar zircon age cluster to those of the somewhat younger Üzümdere Formation, ranging from 239 Ma to 2.9 Ga. A few grains gave Anisian ages. Cambrian zircon grains are less pronounced than in the Kas?mlar Formation compared to the Üzümdere Formation. The detrital zircon record of Tauride sandstones, therefore, not indicates significant contribution of Triassic or Carboniferous (Variscan) arc sources, in marked contrast to those of the Triassic Karakaya subduction complex. In comparison, the ages of the analysed zircons in the Upper Triassic sandstones of the Istanbul Terrane range from 294 Ma to 3.1 Ga. Triassic zircons are again absent, while Variscan-aged zircons (294 to 339 Ma) dominate the zircon population. Additional zircon populations are dated at 554 to 655 Ma, 0.9 to 1.2 Ga, 1.5 Ga, 1.65 Ga, 2.0 to 2.15 and 2.5 to 2.8 Ga. The Precambrian zircon age spectra are compatible with derivation from an Avalonian/Amazonian/Baltic crustal provenance. In summary, there is no evidence in either the Triassic sandstones of the ?stanbul Terrane or of the Taurides of the Triassic magmatic arc source that dominates the Triassic Karakaya subduction-accretion complex. Where then was the source of the Karakaya arc detritus? A likely option is that the Karakaya subduction-accretion complex is an exotic terrane that was detached from a source magmatic arc and displaced to its present location, probably prior the initial deposition of the Early Jurassic cover sediments. This study was supported by TUBITAK, Project No: 111R015

Ustaömer, Timur; Ayda Ustaömer, Petek; Robertson, Alastair H. F.; Gerdes, Axel; Zulauf, Gernold

2014-05-01

156

Palynology of Sub-Saharan Karoo Basins: Key to Early Mesozoic palaeoclimate reconstruction  

NASA Astrophysics Data System (ADS)

Palynological data of Permian-Triassic formations of the Sub-Saharan Karoo basins play a crucial role in the study and for the understanding of Gondwana's climate history and biodiversity in this time of major global changes in terrestrial and marine ecosystems. The palynological record reflects changes in land plant communities and vegetational patterns related to climate change and thus provides significant data for high-resolution palaeoclimate reconstructions in deep time. Recent palynological investigations of Triassic successions of South Africa, Mozambique and Tanzania document major changes in palaeoclimate. The spore/pollen ratios are used as a proxy for humidity changes. Stratal variations in the composition of the pollen group indicate warming and cooling phases. Variations in the amount and in the type, size and shape of phytoclasts reflect short-term changes in transport and weathering. The detected palaeoclimate signals are used for high-resolution correlation on basin-wide, intercontinental and intra-Gondwanic scales.

Götz, Annette E.

2014-05-01

157

Promoting latrine construction and use in rural villages practicing open defecation: process evaluation in connection with a randomised controlled trial in Orissa, India  

PubMed Central

Background Our group conducted a cluster-randomised trial in 100 villages of Orissa, India to measure the impact of a rural sanitation intervention implemented under the government of India's Total Sanitation Campaign, on diarrhoea and soil-transmitted helminth infections. This paper reports on a process evaluation conducted in the context of the trial. Methods Process evaluation data were collected through review of key documentation, quantitative surveys, direct observations, and semi-structured interviews with staff from implementing NGOs and community members. Between March 2011 and March 2012, trained enumerators recorded observations on latrine construction status every 6–8 weeks in the 50 intervention villages and noted activities reported to have taken place based on NGO staff interviews and review of NGO records. A survey among 10% of households in intervention and control villages was conducted to compare levels of awareness of key intervention components. In addition, 10% of village water and sanitation committee (VWSC) members were interviewed to measure their level of involvement in the intervention delivery. Results The percentage of households with a latrine (completed or under construction) increased from 8% at baseline to 66% one year after the start of the intervention in March 2012. Almost none of the intervention households recall any form of participatory community-level activities at the start of the programme, although intervention households were generally more aware of the Total Sanitation Campaign (91% versus 49%, p?

2014-01-01

158

Association of TNF-? Promoter Polymorphism with HBV Associated Disease Outcome Among HBV Infected Patients from Orissa, Southern Part of East India  

PubMed Central

Background TNF-? promoter polymorphism has been known to be a potential predictive factor in patients with HBV infection. We therefore tried to investigate whether the TNF-? promoter polymorphism at position ?238, ?857 and ?863 was associated with the outcome of HBV infection in a population from Orissa, southern part of East India. Methods A total of 195 patients recruited for the study were classified into 85 controls and 110 HBV infected cases, which included 34 IC, 30 CLD, 32 LC and 14 HCC patients. The polymorphisms at the respective sites were detected by a PCR-RFLP followed by statistical analysis. Results The frequency of the genotype ?238 GG and the allele ?238G in the cases (89.0% and 92.7% respectively) was significantly higher than that in the controls (68.2% and 82.2% respectively) (P < 0.001, OR = 3.8 and P = 0.001, OR = 2.73). Whereas the ?238 GA genotype was significantly high in the control group (28.2%) when compared to the cases (7.2%) (P < 0.001, OR = 0.2). Similarly, the frequency of ?863CC and the allele ?863C was significantly higher among the cases (24.5% and 49.5%) compared to controls (1.17% and 34.7%), (P < 0.001, OR = 27.32 and P = 0.003, OR = 1.85), whereas the ?863CA genotype was significantly high in the controls (67.0%) when compared to the cases (50.0%) (P = 0.01, OR = 0.49). Haplotype ?863C/?857C/?238G in cases was significantly higher than controls (P = 0.002). Multivariate logistic regression analysis indicates that the genotype ?863CC bears a negative association with liver disease progression. Conclusion The present study established an association of polymorphisms at site ?238 and ?863 of the TNF-? promoter with the outcome HBV infection and disease progression. PMID:25755561

Panigrahi, Rajesh; Sarkar, Neelakshi; Biswas, Avik; Pal, Ananya; Saha, Debraj; Singh, Shivaram P.; Panigrahi, Manas K.; Bandopadhyay, Manikanana; Chakrabarti, Sekhar; Chakravarty, Runu

2014-01-01

159

Sundaland basins  

NASA Astrophysics Data System (ADS)

The continental core of Sundaland, comprising Sumatra, Java, Borneo, the Thai-Malay Peninsula and Indochina, was assembled during the Triassic Indosinian orogeny, and formed an exposed landmass during Pleistocene lowstands. Because the region includes extensive shallow seas, and is not significantly elevated, it is often assumed to have been stable for a long period. This stability is a myth. The region is today surrounded by subduction and collision zones, and merges with the India-Asia collision zone. Cenozoic deformation of Sundaland is recorded in the numerous deep sedimentary basins alongside elevated highlands. Some sediment may have been supplied from Asia following Indian collision but most was locally derived. Modern and Late Cenozoic sediment yields are exceptionally high despite a relatively small land area. India-Asia collision, Australia-SE Asia collision, backarc extension, subduction rollback, strike-slip faulting, mantle plume activity, and differential crust-lithosphere stretching have been proposed as possible basin-forming mechanisms. In scale, crustal character, heat flow and mantle character the region resembles the Basin and Range province or the East African Rift, but is quite unlike them in tectonic setting. Conventional basin modeling fails to predict heat flow, elevation, basin depths and subsidence history of Sundaland and overestimates stretching factors. These can be explained by interaction of a hot upper mantle, a weak lower crust, and lower crustal flow in response to changing forces at the plate edges. Deformation produced by this dynamic model explains the maintenance of relief and hence sediment supply over long time periods.

Hall, Robert; Morley, Christopher K.

160

Santa Barbara Basin Los Angeles Basin  

E-print Network

#12;Silurian 420 ma Michigan Illinois Appalachian Sources of Salinity: Ancient Sedimentary Basins, USASanta Barbara Basin 100 km Los Angeles Basin Effects of Faults On Coastal Groundwater Salinity of Groundwater Salinity Seawater Intrusion Mixing with Basinal Brines Dissolution of Evaporites Evaporation

Einat, Aharonov

161

The relationship of Palaeozoic metamorphism and S-type magmatism on the paleo-Pacific Gondwana margin  

NASA Astrophysics Data System (ADS)

A massive pulse of granitic magma was rapidly emplaced into the once contiguous West Antarctic and New Zealand segments of the palaeo-Pacific margin of the Gondwana supercontinent at ~ 371 Ma. In New Zealand, these Late Devonian S-type granitoids cover an areal extent of > 3400 km2, but the tectonic setting for crustal partial melting has remained unclear because most of the exposure represents either emplacement-level, or rocks that have been reworked during Cretaceous orogenesis. New petrologic data indicate that aluminous paragneisses and orthogneisses in the Bonar Range represent a rare portion of Devonian middle crust that preserves evidence for the initiation of crustal melting. The investigated rocks outline the tail of a clockwise P-T path that involved partial melting at peak conditions (~ 670 °C, 5.1 kb), deformation during the immediately following near-isothermal decompression, and then partial re-equilibration under static conditions. Syn- to post-kinematic growth of zoned monazite establishes the timing of recrystallisation to a ~ 16 Ma period that began at 373.4 ± 4.1 Ma. This age overlaps with the initiation of regional Karamea S-type granitic magmatism. Although estimated metamorphic conditions were insufficient for large amounts of melt to have been produced from Bonar Range pelites (calculated melt volumes are < 10%), they do provide evidence consistent with widespread heating and partial melting in the deeper crust. This heating episode was contemporaneous with partial melting in Fiordland (New Zealand) and West Antarctica, although Mesozoic thermal and deformational events complicate the Palaeozoic record in both those areas. Nevertheless, the apparent 1000 s km of along-strike crustal partial melting indicates that a continental-scale tectonic plate margin re-organisation took place at this time. The cause in the New Zealand segment was most likely, but not unequivocally, an extensional tectonic regime with an elevated geothermal gradient caused by conductive heating from a shallowed lithospheric mantle.

Scott, James; Muhling, Janet; Fletcher, Ian; Billia, Marco; Palin, J. Michael; Elliot, Tim; Günter, Christina

2011-12-01

162

Correlation between plate motions and tectonic subsidence of sedimentary basins in Africa  

SciTech Connect

From the early Mesozoic until the Holocene, the African continent was generally in a state of extension, based on plate tectonic reconstructions and sedimentary basin subsidence studies. Beginning with the breakup of Gondwana in the Permian-Triassic, this resulted in the formation of the present-day African continental margins and a series of intracontinental rift basins, located mainly on older (late Proterozoic) shear zones. Numerous wells from marginal, as well as intracontinental rift basins, have been backstripped to elucidate their Mesozoic and Tertiary tectonic histories. They show a generally consistent patterns of subsidence and uplift phases in all basins. During the evolution of these basins, the direction of African plate motion changed several times. This was related to the differential opening of the central and south Atlantic oceans, changes in spreading rates in both the Atlantic and Indian oceans, and the collision between Africa and Europe. Episodes of compressional deformation related to these plate tectonic changes are revealed in backstripped tectonic subsidence curves.

Janssen, M.E. (Vrije Universiteit, Amsterdam (Netherlands))

1993-09-01

163

Provenance study of Pliocene-Pleistocene sands based on ancient detrital zircons (Alvalade Basin, SW Iberian Atlantic coast)  

NASA Astrophysics Data System (ADS)

Pliocene-Pleistocene sand of the Alvalade basin was taken from the sea-cliffs of SW Iberia coast for a provenance study using radiometric dating. The U-Pb ages obtained revealed a wide interval ranging from Cretaceous to Archean, with predominance of Paleozoic, Neoproterozoic and Cretaceous zircon ages. Cretaceous ages interpreted to indicate a Sines Massif provenance are dominant in sands close to Cape Sines but are absent in sand sampled 12 km north. Carboniferous ages younger than ca. 315 Ma suggesting a possible contribution from the Central-Iberian Zone originally; however, these zircons may be multi-cyclic, having been reworked from Eocene-Miocene siliciclastic deposits related to transport from central Iberia (Lower Tagus basin drainage evolution). These signatures provide important constraints on the location and extent of the Pliocene-Pleistocene topography and drainage system that were probably controlled by: i) Miocene to Pleistocene landscape rejuvenation driven by Alpine movements along major faults; and ii) residual reliefs related to inherited Variscan structure. The U-Pb ages obtained also trace the pre-Cenozoic paleotectonic evolution of SW Iberia recorded in their sources: i) the North Gondwana accretion and breakup; ii) the Gondwana and Laurussia collision; and iii) the Pangea breakup and opening of the Atlantic Ocean.

Albardeiro, Luís; Pereira, Manuel Francisco; Gama, Cristina; Chichorro, Martim; Hofmann, Mandy; Linnemann, Ulf

2014-06-01

164

News and Views: Making a name; Lightning storm rages on Saturn; Bumper haul for Swift's GRB hunters; Whatever happened to Gondwana? Observing Earth; X-ray outburst timer  

NASA Astrophysics Data System (ADS)

The combination of continents into supercontinents, and their subsequent fragmentation and rearrangement is an accepted part of the history of the Earth, but how it happens in detail is not always clear. Did supercontinents split into a few large pieces, or were many small fragments formed in the break-up? Now geophysical measurements have answered this conundrum - which has implications for later continental reconstructions - for the break-up of Gondwana, the supercontinent that existed from about 500-180 million years ago.

2008-06-01

165

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

NASA Astrophysics Data System (ADS)

The Pedroches basin, straddling the boundary between the Ossa Morena (OMZ) and the Central Iberian (CIZ) zones of the Iberian Massif, forms one of the largest exposures of Mississippian rocks in the Iberian Peninsula. With the only exception of transitional facies near the northern and southern margins, the basin fill mostly consists of volcanic and sedimentary rocks deposited in relatively shallow continental shelf environments, in which storm activity was the main process of sediment supply and dispersal. Significantly, the Pedroches basin is split into several compartments (structural units), among which three syn-sedimentary, sigmoidal shape igneous belts, produced the most severe facies, structural and palaeogeographic changes. Owing to its timing of formation during the period of Variscan convergence, its location within an area undergoing active Variscan deformation, and the fact that the basin fill was itself affected by the Variscan orogeny, the Pedroches basin was considered a typical example of a syn-orogenic, peripheral foreland basin. Recent stratigraphical, sedimentological and isotope geology work has allowed a reinterpretation of the basin fill, in which two different sequences may be distinguished, with distinct tectono-stratigraphic significance. Above a basal conglomerate, the several hectometres thick lower part of the basin fill succession shows the highest variability among the various structural units in terms of lithology, facies and thickness. Most volcanic rocks are located within this lower part, within and in between the igneous belts, suggesting the important role of lithosphere-through, extension-related faulting in the origin of the basin. Significant across-strike thickness changes attest for syn-sedimentary horst and graben formation at this stage. On the contrary, the upper part of the basin fill is very similar in all units and corresponds to flyschoid greywacke-mudstone alternations (Culm facies). The change between the lower and the upper parts of the basin fill is interpreted as evidence for a transition from an overall extensional (transtensional?) regime during basin generation to an overall transpressional one, during which the basin was transformed into a sort of peripheral foreland basin and inverted soon after. A possibility opened to further research, here outlined as a provocative hypothesis, is that during the Variscan collision between Laurussia and Gondwana the latter might have been pushed southeastwards and eventually collided with a Palaeotethys spreading ridge or, perhaps, a branch departing from it. In this context, the first part of the evolution of the Pedroches basin could in fact be the consequence of a combination of both transtension and the overriding of a slab window developed as a result of ridge-trench collision, itself inducing rifting in the upper (Iberian) plate. Final collision of the southern margin of the OMZ (south Iberian part of Gondwana) with Laurussia by the late Viséan, which culminated the closure of this part of the Rheic Ocean, imposed a change to more orthogonal strain conditions that may have caused the abortion of the propagating rift and also triggered subsequent basin inversion.

Armendáriz, Maider; Quesada, Cecilio; Rosales, Idoia

2013-04-01

166

Sands of West Gondwana: An archive of secular magmatism and plate interactions — A case study from the Cambro-Ordovician section of the Tassili Ouan Ahaggar (Algerian Sahara) using U-Pb-LA-ICP-MS detrital zircon ages  

NASA Astrophysics Data System (ADS)

Enormous masses of highly mature quartz sands were deposited in Western Gondwana during the Cambrian-Ordovician time, and provide a wide range of information concerning magmatic events through time, provenance, paleoclimate, and basin history. We present a provenance study based on 630 U-Pb (LA-ICP-MS) ages of detrital zircon from the latest Cambrian to Ordovician siliciclastic rocks of the Tassili Ouan Ahaggar basin situated in the Algerian Sahara. Most authors suggest local sources only for the sandstones. Instead, we demonstrate that the detritus is derived from different cratons and terranes which contributed to the deposition of a Cambrian-Ordovician overstep sequence covering western and northern Africa. Most zircon ages (61.0%) fall in the range of ~ 540 to 740 Ma and are interpreted to have been derived from Pan-African orogenic belts such as the Trans-Saharan Belt of NW Africa and previously from the Brazila belt of South America. Other potential sources for this zircon population are terranes of Cadomian affinity situated marginal to West Africa. The second-largest zircon population (20.2%) is 2.0 to 2.2 Ga, and is attributed to sources in the West African craton, such as the Birimian basement and the Eburnean orogenic belt, with possible partial input from the Amazonian craton. A zircon population of 7.1% yields Mesoproterozoic and early Paleoproterozoic ages in the range of ~ 1.3 to ~ 1.8 Ga and was probably derived from source rocks outside of the West African basement, the Tuareg shield and other adjoining areas. The Amazonian craton is a potential source region. A population of 6.7% of all zircon ages scatter from ~ 750 Ma to ~ 980 Ma and may reflect input from latest stages of the formation of Rodinia and its subsequent dispersal. A smaller population (3.2%) of zircon ages lie between ~ 2.3 and 2.65 Ga, and may be derived from late Paleoproterozoic to early Archaean rocks from the West African craton and possibly from Amazonia. Less than 1% of all zircons are Meso- to Paleoarchaean ones and provide evidence for the input of very old cratonic basement, most likely from cratonic inliers of the West African craton (Leonian, Liberian). Because of the potential input of detrital zircon from the Amazonian craton, which is reflected in the Mesoproterozoic and late Paleoproterozoic grains, we speculate that some of the Paleoproterozoic to Neoarchean (2.0 Ga to 2.6 Ga) zircons were also derived from Amazonia. Due to the total lack of 1.0-1.2 Ga old zircon, our data set excludes all crustal domains situated in the Arabian-Nubian shield and the East African belt, as well as the Sunsás belt of Amazonia ("Sunsás-Grenvillian") as potential sediment sources. Sedimentation in the Tassili Ouan Ahaggar basin started in uppermost Cambrian to Ordovician time due to the opening of the Rheic Ocean. This event led to subsidence related to the rift and drift of Avalonia and related terranes from the northwestern Gondwanan margin. The basal Early Tassili quartzite has detrital zircon populations that suggest a local provenance either from West African or from a related terrane in the Tuareg shield. A dramatic change occurs in the deltaic to shallow marine strata of the Lower Ordovician Ajjers Formation and in the overlying marine sandstones of the Middle Ordovician d'In Azaoua Formation. Our data for both formations indicate the Pan-African orogen, and very likely Cadomian terranes as the main source for the detritus. During this time, the region was affected by rift tectonics due to the opening of the Rheic Ocean and therefore amenable to erosion at rift shoulders and escarpments. Our data also indicate that glacial erosion in Upper Ordovician (Hirnantian) time must have affected larger areas of old cratonic surfaces as the populations of Paleoproterozoic to Archaean zircons are significantly higher than in other age clusters. Large parts of highly mature sands of the Cambro-Ordovician section in the Tassili Ouan Ahaggar basin were derived from a peneplain in the interior of Gondwana, that formed during Cambrian time

Linnemann, Ulf; Ouzegane, Khadidja; Drareni, Amar; Hofmann, Mandy; Becker, Sindy; Gärtner, Andreas; Sagawe, Anja

2011-04-01

167

Effect of Household-Based Drinking Water Chlorination on Diarrhoea among Children under Five in Orissa, India: A Double-Blind Randomised Placebo-Controlled Trial  

PubMed Central

Background Boiling, disinfecting, and filtering water within the home can improve the microbiological quality of drinking water among the hundreds of millions of people who rely on unsafe water supplies. However, the impact of these interventions on diarrhoea is unclear. Most studies using open trial designs have reported a protective effect on diarrhoea while blinded studies of household water treatment in low-income settings have found no such effect. However, none of those studies were powered to detect an impact among children under five and participants were followed-up over short periods of time. The aim of this study was to measure the effect of in-home water disinfection on diarrhoea among children under five. Methods and Findings We conducted a double-blind randomised controlled trial between November 2010 and December 2011. The study included 2,163 households and 2,986 children under five in rural and urban communities of Orissa, India. The intervention consisted of an intensive promotion campaign and free distribution of sodium dichloroisocyanurate (NaDCC) tablets during bi-monthly households visits. An independent evaluation team visited households monthly for one year to collect health data and water samples. The primary outcome was the longitudinal prevalence of diarrhoea (3-day point prevalence) among children aged under five. Weight-for-age was also measured at each visit to assess its potential as a proxy marker for diarrhoea. Adherence was monitored each month through caregiver's reports and the presence of residual free chlorine in the child's drinking water at the time of visit. On 20% of the total household visits, children's drinking water was assayed for thermotolerant coliforms (TTC), an indicator of faecal contamination. The primary analysis was on an intention-to-treat basis. Binomial regression with a log link function and robust standard errors was used to compare prevalence of diarrhoea between arms. We used generalised estimating equations to account for clustering at the household level. The impact of the intervention on weight-for-age z scores (WAZ) was analysed using random effect linear regression. Over the follow-up period, 84,391 child-days of observations were recorded, representing 88% of total possible child-days of observation. The longitudinal prevalence of diarrhoea among intervention children was 1.69% compared to 1.74% among controls. After adjusting for clustering within household, the prevalence ratio of the intervention to control was 0.95 (95% CI 0.79–1.13). The mean WAZ was similar among children of the intervention and control groups (?1.586 versus ?1.589, respectively). Among intervention households, 51% reported their child's drinking water to be treated with the tablets at the time of visit, though only 32% of water samples tested positive for residual chlorine. Faecal contamination of drinking water was lower among intervention households than controls (geometric mean TTC count of 50 [95% CI 44–57] per 100 ml compared to 122 [95% CI 107–139] per 100 ml among controls [p<0.001] [n?=?4,546]). Conclusions Our study was designed to overcome the shortcomings of previous double-blinded trials of household water treatment in low-income settings. The sample size was larger, the follow-up period longer, both urban and rural populations were included, and adherence and water quality were monitored extensively over time. These results provide no evidence that the intervention was protective against diarrhoea. Low compliance and modest reduction in water contamination may have contributed to the lack of effect. However, our findings are consistent with other blinded studies of similar interventions and raise additional questions about the actual health impact of household water treatment under these conditions. Trial Registration ClinicalTrials.gov NCT01202383 Please see later in the article for the Editors' Summary PMID:23976883

Boisson, Sophie; Stevenson, Matthew; Shapiro, Lily; Kumar, Vinod; Singh, Lakhwinder P.; Ward, Dana; Clasen, Thomas

2013-01-01

168

Structural Architecture of Northern Victoria Land (antarctica) in the Perspective of the Paleo-Pacific Margin of Gondwana  

NASA Astrophysics Data System (ADS)

Northern Victoria Land (Antarctica) was part of the active proto-Pacific plate margin of Gondwana, which has been site of protracted convergence during the Paleozoic. This study supplies new insights into the structural architecture of the Transantarctic Mountains in northern Victoria Land, with original structural data on the boundary area between the Bowers and Robertson Bay terranes. This area is characterized by the occurrence of the Millen Schist (MS) belt, that is a high strain equivalent of the adjoining terranes. At present the boundary between the terranes and the MS is marked by two faults with regional relevance: the Leap Year and the Handler faults. Our study reveals that such faults represent an oblique slip system, characterized by positive flower structures, and overprint a transitional pre-existing ductile deformational boundary. Both Leap Year and Handler faults are associated to a significant syn-tectonic fluids circulation, mineralization, and a significant rock-fluid interaction that resemble the one responsible for the gold mineralization, described in the Bowers Mts (northern Victoria Land). The MS belt is made up of two tectonic elements, superposed in a duplex thrust system, with a top-to-NE sense of tectonic transport. This thrust overprints the ductile structures of the MS, that are usually interpreted as due to the Ross-Delamerian Orogeny. Moreover, the CAT is overprinted by LYF and HFS and this testifies to an ongoing transpressional regime. Hence, the overall structural architecture of the Bowers-Robertson boundary is the result of a long-lasting SW-NE oblique contractional regime that started during the Ross-Delamerian Orogeny and was still active after that. The increasing abundance of data indicating a post-Ross contractional event suggests a prolongation into Antarctica of the Lachlan Orogeny of southeastern Australia. The similarity in the structural architecture, in the setting of the gold mineralization and the convergence in rock type and age support a correlation of both the Bowers and the Robertson Bay terranes with the Stawell Zone of the Lachlan Fold Belt. In our new tectonic scenario the Lanterman Fault (northern Victoria Land) plays the same role as the Moyston Fault (southeastern Australia) and the Leap Year and Handler faults are the correlatives of "intra-zone faults" of the Stawell Zone.

Capponi, G.; Crispini, L.

2013-12-01

169

Reassembling Gondwana: A new high quality constraint from vibroseis exploration of the sub-ice shelf geology of the East Antarctic continental margin  

NASA Astrophysics Data System (ADS)

The breakup of Gondwana is manifested by coeval early Jurassic Karoo magmatism in South Africa and East Antarctica. In South Africa, the large volumes of volcanic rocks of the adjoining Lebombo and Mwenetzi-Save monoclines represent a volcanic rift margin, and in East Antarctica, a corresponding feature, the Explora Wedge is buried below sediments and floating ice shelves on the continental margin of Dronning Maud Land. We use the seismic vibrator source to explore the sub-ice geology in Antarctica, and the new seismic reflection and available regional aeromagnetic data enable us to outline a dogleg landward extent of the Explora Wedge in Dronning Maud Land. The congruent inboard wedge geometries on the two continents define a high quality constraint, which facilitate for the first time, a geologically consistent and tight reconstruction of Africa relative to East Antarctica within Gondwana. The uncertainties in correlations of major geological features (mobile belts) from one continent to the other may now be of the order of ten's of kilometers rather than hundreds of kilometers.

Kristoffersen, Yngve; Hofstede, Coen; Diez, Anja; Blenkner, Richard; Lambrecht, Astrid; Mayer, Christoph; Eisen, Olaf

2014-12-01

170

The first stages of evolution of the Western Somali Basin  

NASA Astrophysics Data System (ADS)

The rifted and transform margins created by the separation of Madagascar and Africa offer an opportunity to jointly investigate the structural and geodynamic evolution of conjugate continental passive margins. It is generally accepted that the continental breakup of Gondwana in the East African region began with the onset of the southward drift of Madagascar (then connected with Antarctica and India) along the Davie Fracture Zone probably during the Middle Jurassic, and subsequently led to the opening of the western Somali Basin. Although published kinematic models are able to explain and date some of the broad scale features of the Somali and Mozambique oceanic basins, the exact timing of rifting, the early stages of seafloor spreading and the timing of seafloor cessation in the western Somali Basin remain debatable. Our new study aims to investigate the relationship between the long history of rifting along the East African margins and the breakup structures by constructing a consistent database that contains structural elements and information about their evolution from updated published literature. Next, a thorough investigation of the potential field data (magnetic and gravity anomalies) is undertaken in order to establish the structure (and possibly timing) of the early seafloor spreading. An analysis of multichannel seismic reflection, gravity, magnetic and bathymetric datasets is aimed to identify deep crustal structure and continent-ocean transition zone in the study area. We present preliminary results showing the evolution of the East African margin (along Somali and Mozambique basins), the location of the transition zone between the continental and oceanic crust, and a regional kinematic analysis of the Jurassic-mid Cretaceous tectonic events.

Labails, Cinthia; Gaina, Carmen; Skogseid, Jakob; Pilskog, Bjørn; Graue, Knut

2010-05-01

171

Neocomian half graben in the western San Jorge basin, Argentina: Petroleum systems, origin and tectonic inversion  

SciTech Connect

During late Jurassic-early Cretaceous times, the extension related to the Gondwana break-up generated many isolated small half-graben basins, with a NW-SE structural trend, in the central part of Patagonia Terrane. The sedimentary record, which overlays an igneous metamorphic prejurassic basement, is made up by three megasequences that represent different stages in rifting evolution. The main source rock, composed of Neocomian lacustrine dark organic-rich shales, with type I kerogen, rests on a late Jurassic volcanic and sedimentary complex, and it is found within Megasequence I (early and late rift). This megasequence ends with fluvial deltaic and tidal sandstones as the oldest reservoir rocks. The main reservoirs, made up of upper Cretaceous braided and meander sandstones, are found within Megasequence II (early and late sag), which ends with thick pyroclastic overbank deposits as the regional seal. Megasequence III, composed of Tertiary marine and continental rocks, lacking source and reservoirs levels, solely acts as overburden rock. After a W-E Tertiary compression, these basins were partially inverted, to different degrees, according to the orientation of pre-existing faults. Likewise, the thermal maturity history of the source rock, the migration pathways and the traps vary in each of these basins. This study sets out to show how analogous basins with the same stratigraphic record became independent petroleum systems due to a different tectonic evolution.

Figari, E.; de la Paz, C.; Laffitte, M.; Lafeitte, G. [YPF, S.A., Area Exploration (Argentina)

1996-08-01

172

Stable carbon isotope chemostratigraphy and tectonic setting of the Pennsylvanian Ely-Bird Spring basin, Nevada and Utah: interpreting three-dimensional basin evolution using multiple stratigraphic techniques  

NASA Astrophysics Data System (ADS)

The Pennsylvanian was a tectonically active time throughout Laurasia. In western Laurasia, the Ely-Bird Spring basin (EBSB) formed during early to middle Pennsylvanian time as one of a series of tectonically-generated, stacked, late Paleozoic basins. Timing and extent of these basins is well constrained; but the tectonic framework that resulted in basin formation is poorly known. Farther east, Ancestral Rocky Mountain basins and uplifts formed synchronously with the EBSB, as a far-field response to collision between Laurasia and Gondwana. This dissertation was undertaken in order to develop a method that combines whole-rock carbon isotope chemostratigraphy with lithostratigraphy and biostratigraphy. These data were used to elucidate the three-dimensional evolution and tectonic setting of the EBSB. To do this, six nearly complete sections located throughout Nevada and western Utah were densely sampled for carbon isotope stratigraphy. The results of this work are presented in three chapters as outlined below. Chapter 1 tests the hypotheses that carbon isotope shifts mirror cyclothemic lithologic shifts and that these systematic isotopic shifts can be used as a correlation tool. Three sections from the north, central, and southern portions of the EBSB were densely sampled for carbon isotope stratigraphy. Generally, the isotopes tracked changes in rock type, with shifts to more positive carbon isotope values toward the tops of shallowing-upward lithologic cycles. Therefore, pattern matching of whole-rock isotope shifts, tied to lower resolution biostratigraphy, is a feasible method for high-resolution correlation within the basin. Chapter 2 presents new fine-scale carbon isotope stratigraphy from six sections around the basin, combined with existing biostratigraphy, to elucidate the three- dimensional evolution of the basin. Correlations between sections were investigated using Match-2.3 (Lisiecki and Lisiecki, 2002), a dynamic programming algorithm developed for stratigraphic signal correlation. Based on these correlations, the highest initial relative sediment accumulation rates occurred in the eastern part of the basin. However, for most of the life of the basin, the highest relative accumulation rates were in the northwestern part of the basin. High rates of sediment accumulation in the northwestern part of the basin may be a response to renewed tectonism to the west. This corroborates previous work which shows that tectonism culminated in angular unconformities and overturned folding that deformed the northern basin strata during middle Pennsylvanian time, but left southern basin strata relatively unaffected. Chapter 3 compares the three-dimensional evolution of the EBSB to broadly coeval Ancestral Rocky Mountains basins. The purpose was to test whether the Ancestral Rocky Mountains and EBS basins were related tectonically. Geohistory analyses for the EBSB and four Ancestral Rocky Mountains basins indicate that the basins were in different tectonic settings. Three-dimensional subsidence analysis of the EBSB suggests it is more compatible with a foreland basin subsidence model whereas most of the Ancestral Rocky Mountains basins are consistent with subsidence models for strike-slip basins.

Sturmer, Daniel M.

173

"SE Asia was rifted parts of the Early Paleozoic NW Australia Gondwana", GEOSEA'98 (Ninth Regional Congress on Geology, Mineral and Energy Resources of Sotheast Asia, Kuala Lumpur, Malaysia (with Bunopas,  

E-print Network

"SE Asia was rifted parts of the Early Paleozoic NW Australia Gondwana", GEOSEA'98 (Ninth Regional Congress on Geology, Mineral and Energy Resources of Sotheast Asia, Kuala Lumpur, Malaysia (with Bunopas, S Thailand and East Asia" GEOSEA '98 (Ninth Regional Congress on Geology, Mineral and Energy Resources

Banbara, Mutsunori

174

A Permo-Carboniferous tide-storm interactive system: Talchir formation, Raniganj Basin, India  

NASA Astrophysics Data System (ADS)

Sandstone/siltstone-mudstone interbedded facies of the Permo-Carboniferous Talchir formation, Gondwana Supergroup, is exposed in the Raniganj Basin and records the activities of tidal currents in a terminoglacial, storm-influenced shallow marine setting. Tidal bundles of various types with pause plane drapes, evidence of time-velocity asymmetry and rare bidirectional current flow patterns are indicative of tidal activity. Chance preservation of such structures from storm reworking might have occurred due to dampening of storm waves on the low-gradient muddy substrate of the tidal flat. The tide-generated stratifications are draped by over-thickened muddy-siltstone with wavy/hummocky laminations. Increased suspended sediment concentrations following a storm yielded such thick mudstone drapes. Thin beds containing tidal structures indicate poor sediment supply in a blind tidal embayment.

Bhattacharya, H. N.; Bhattacharya, Biplab

2006-08-01

175

U-Pb LA-SF-ICP-MS zircon geochronology of the Serbo-Macedonian Massif, Greece: palaeotectonic constraints for Gondwana-derived terranes in the Eastern Mediterranean  

NASA Astrophysics Data System (ADS)

The Pirgadikia Terrane in northern Greece forms tectonic inliers within the Vardar suture zone bordering the Serbo-Macedonian Massif to the southwest. It comprises Cadomian basement rocks of volcanic-arc origin and very mature quartz-rich metasedimentary rocks. U-Pb laser ablation sector-field inductively-coupled plasma mass spectrometry analyses of detrital zircons from the latter reveal a marked input from a Cadomian-Pan-African source with minor contribution from Mesoproterozoic, Palaeoproterozoic and Archaean sources. The metasedimentary rocks are correlated with Ordovician overlap sequences at the northern margin of Gondwana on the basis of their maturity and zircon age spectra. The Pirgadikia Terrane can be best interpreted as a peri-Gondwana terrane of Avalonian origin, which was situated close to the Cadomian terranes in the Late Neoproterozoic-Early Palaeozoic, very much like the Istanbul Terrane. The second unit investigated is the Vertiskos Terrane, which constitutes the major part of the Serbo-Macedonian Massif in Greece. It comprises predominantly igneous rocks of Silurian age and minor metasedimentary rocks of unknown age and provenance. U-Pb analyses of detrital zircons from a garnetiferous mica schist of the Vertiskos Terrane indicate derivation from 550 to 1,150 Ma-old source rocks with a major Cadomian peak. This, combined with minor input of >1,950 Ma-old zircons and the absence of ages between ca. 1.2 and 1.7 Ga suggests a NW Africa source. The protolith age of the garnetiferous mica schist is presumably Early Ordovician. One sample of garnet-bearing biotite gneiss, interpreted as meta-igneous rock, comprises predominantly subhedral zircons of igneous origin with late Middle Ordovician to Silurian ages. We suggest that the rock association of the Vertiskos Terrane is part of an ancient active-margin succession of the Hun superterrane, comparable to successions of the Austro- and Intra-Alpine Terranes. The new data of this study provide evidence of occurrences of Avalonia- and Armorica-derived terranes in the Eastern Mediterranean and moreover help to clarify palaeogeographic reconstructions for the peri-Gondwana realm in the Early Palaeozoic.

Meinhold, Guido; Kostopoulos, Dimitrios; Frei, Dirk; Himmerkus, Felix; Reischmann, Thomas

2010-06-01

176

Break-up of Gondwana and opening of the South Atlantic: Review of existing plate tectonic models  

USGS Publications Warehouse

each model. We also plot reconstructions at four selected epochs for all models using the same projection and scale to facilitate comparison. The diverse simplifying assumptions that need to be made in every case regarding plate fragmentation to account for the numerous syn-rift basins and periods of stretching are strong indicators that rigid plate tectonics is too simple a model for the present problem.

Ghidella, M.E.; Lawver, L.A.; Gahagan, L.M.

2007-01-01

177

Puncoviscana folded belt in northwestern Argentina: testimony of Late Proterozoic Rodinia fragmentation and pre-Gondwana collisional episodes  

Microsoft Academic Search

Stratigraphic correlations and tectonic analysis suggest that the Puncoviscana fold belt of northwestern Argentina was an\\u000a intracontinental basin with bimodal igneous suites that formed in connection with the breakup of the Rodinia supercontinent\\u000a (at ?800?Ma). Several lines of evidences point to an initial lithosphere rupture, possibly induced by a rising mantle plume.\\u000a The earliest synrift igneous products are represented by

R. H. Omarini; R. J. Sureda; H.-J. Götze; A. Seilacher; F. Pflüger

1999-01-01

178

Permian and Triassic microfloral assemblages from the Blue Nile Basin, central Ethiopia  

NASA Astrophysics Data System (ADS)

Palynological investigation was carried out on surface samples from up to 400 m thick continental siliciclastic sediments, here referred to as “Fincha Sandstone”, in the Blue Nile Basin, central Ethiopia. One hundred sixty species were identified from 15 productive samples collected along a continuous road-cut exposure. Six informal palynological assemblage zones have been identified. These assemblage zones, in ascending order, are: “Central Ethiopian Permian Assemblage Zone - CEPAZ I”, earliest Permian (Asselian-Sakmarian); “CEPAZ II”, late Early Permian (Artinskian-Kungurian); CEPAZ III - Late Permian (Kazanian-Tatarian); “CETAZ IV”, Lower Triassic (Olenekian Induan); “CETAZ V”, Middle Triassic (Anisian Ladinian); “CETAZ VI”, Late Triassic (Carnian Norian). Tentative age ranges proposed herein are compared with faunally calibrated palynological zones in Gondwana. The overall composition and vertical distribution of miospores throughout the studied section reveals a wide variation both qualitatively and quantitatively. The high frequency of monosaccate pollen in CEPAZ I may reflect a Glossopterid-dominated upland flora in the earliest Permian. The succeeding zone is dominated by straite/taeniate disaccate pollen and polyplicates, suggesting a notable increase in diversity of glossopterids. The decline in the diversity of taeniate disaccate pollen and the concomitant rise in abundance of non-taeniate disaccates in CEPAZ III may suggest the decline in Glossopteris diversity, though no additional evidence is available to equate this change with End-Permian extinction. More diverse and dominant non-taeniate, disaccate, seed fern pollen assignable to FalcisporitesAlisporites in CETAZ IV may represent an earliest Triassic recovery flora. The introduction of new disaccate forms with thick, rigid sacci, such as Staurosaccites and Cuneatisporites, in CETAZ V and VI may indicate the emergence of new gymnospermous plants that might have favourably adapted to coastal plain wetland environments with the return of humid conditions in the Middle to early Late Triassic. The present data constitute the first paleontologically substantiated record for the existence of Permian strata in the Blue Nile Basin. The new results allow for the first time a reliable biostratigraphic subdivision of the central Ethiopia Karoo and its correlation with coeval strata of adjacent regions in Gondwana. From a phytogeographic point of view, the overall microfloral evidence is in support of the position of central Ethiopia occupying the northern part of the southern Gondwana palynofloral province. In view of palaeoecological and paleoclimatic conditions, the microfloral change from the base to the top of the studied section may indicate a response to shifting climatic belts from warm- and cool-temparate climate in the earliest Permian to progressively drier seasonal conditions at successively higher palaeolatitudes during the Late Permian to Middle Triassic.

Dawit, Enkurie L.

2014-11-01

179

Correlation of Triassic stratigraphy between the Simao and Lampang-Phrae Basins: implications for the tectonopaleogeography of Southeast Asia  

NASA Astrophysics Data System (ADS)

Based on our extensive fieldwork in southwestern Yunnan and northern Thailand, followed by detailed stratigraphic and paleontological studies, we propose that the Triassic Simao Basin in Yunnan can be correlated with the Triassic Lampang-Phrae Basin in Thailand. Strata equivalent to those in the southern Lancangjiang sub-basin have not been identified in northern Thailand. We consider that during the Triassic the Simao and the Lampang-Phrae Basins belonged to the same tectonopaleogeographic unit. The orogenic belt to the east of this unit includes the Nan-Uttaradit and Ailaoshan sutures. The 'Shan-Thai Block' in northern Thailand, can be divided from east to west into the Sukhothai, the Inthanon, and the Shan terranes. According to tectonopaleogeographic correlation, our results support the idea that the Sukhothai Terrane, including the Lampang-Phrae Basin, belongs to the Cathaysian domain and not to Gondwana domain, and that the geosuture corresponding to the Changning-Menglian Suture in Yunnan must lie to the west of the Sukhothai Terrane in Thailand.

Feng, Qinglai; Chonglakmani, Chongpan; Helmcke, Dietrich; Ingavat-Helmcke, Rucha; Liu, Benpei

2005-03-01

180

New Sakmarian ages for the Rio Bonito formation (Paraná Basin, southern Brazil) based on LA-ICP-MS U-Pb radiometric dating of zircons crystals  

NASA Astrophysics Data System (ADS)

Two ash fall beds (tonstein) sampled from the post-glacial Permian deposits of the Paraná Basin have provided new U-Pb radiometric age constraints for this stratigraphic interval. The zircon grains were recovered from tonstein layers interbedded with fine-grained and carbonaceous lithologies in the middle portion of the Rio Bonito Formation. In both samples, the dominant population is interpreted as generated by explosive volcanism, as having formed immediately before the eruption. Based on 238U/206Pb, the selected zircon grains from the dominant population have weighted mean ages of 290.6 ± 2.8 Ma and 281.7 ± 3.2 Ma, corresponding to the Sakmarian and Kungurian ages in the Cisuralian epoch, respectively. These ages constrain the time of the deposition of the tonstein horizons and have important stratigraphic implications for the Late Paleozoic evolution of both the Paraná Basin and the southwestern region of Gondwana. The results presented here and the radiometric data already published suggest that deposition of the post-glacial coal-bearing deposits of the Rio Bonito Formation was probably initiated before the Early Permian. Thus, we infer that the climate had already ameliorated by this period in order to allow for the formation and accumulation of peat in this region of Gondwana.

Cagliari, Joice; Lavina, Ernesto Luiz Correa; Philipp, Ruy Paulo; Tognoli, Francisco Manoel Wohnrath; Basei, Miguel Angelo Stipp; Faccini, Ubiratan Ferrucio

2014-12-01

181

Diachronism in the late Neoproterozoic-Cambrian arc-rift transition of North Gondwana: A comparison of Morocco and the Iberian Ossa-Morena Zone  

NASA Astrophysics Data System (ADS)

In the northwestern border of the West African craton (North Gondwana), a transition from late Neoproterozoic subduction/collision to Cambrian rift processes was recorded in the Anti-Atlas (Morocco) and in the Ossa-Morena Zone (Iberia). Cambrian rifting affected both Pan-African and Cadomian basements in a stepwise and diachronous way. Subsequently, both areas evolved into a syn-rift margin episodically punctuated by uplift and tilting that precluded Furongian sedimentation. A comparison of sedimentary, volcanic and geodynamic evolution is made in the late Neoproterozoic (Pan-African and Cadomian) belts and Cambrian rifts trying to solve the apparent diachronous (SW-NE-trending) propagation of an early Palaeozoic rifting regime that finally led to the opening of the Rheic Ocean.

Álvaro, J. Javier; Bellido, Félix; Gasquet, Dominique; Pereira, M. Francisco; Quesada, Cecilio; Sánchez-García, Teresa

2014-10-01

182

New African Lower Carboniferous paleomagnetic pole from intrusive rocks of the Tin Serririne basin (Southern border of the Hoggar, Algeria)  

NASA Astrophysics Data System (ADS)

A paleomagnetic study has been conducted on intrusive doleritic rocks cropping out within Devonian horizontal tabular formations of the Saharan craton (Tin Serririne basin, South of Hoggar shield). The 40K/ 40Ar dating of the dolerites gave an age of 347.6 ± 8.1 Ma, i.e. Tournaisian. The paleomagnetic data present three different directions. The first has a paleomagnetic pole close to the previous African poles of Permian age. This direction is therefore interpreted as a Permian remagnetization. The second direction, which is defined by both linear regression and remagnetization circles analysis, is considered as the primary magnetization. It yields a new African Tournaisian paleomagnetic pole ( ? = 18.8° S, ? = 31.2° E, K = 29, A95 = 7.5°) very close to the Ben Zireg Tounaisian pole [Aifa, T., Feinberg, H., Pozzi, J.P., 1990. Devonian/Carboniferous paleopoles for Africa. Consequences for Hercynian geodynamics. Tectonophysics, 179, 288-304]. The third direction has intermediate orientation between those of the first or second directions and that of the Upper Cenozoic field. It is interpreted as related to a composite magnetization. This new Tin Serririne pole improves the APWP of Gondwana, for this key period of the evolution of the Pangea. This APWP confirms the previous paleogeographic reconstruction which shows that the pre-Hercynian ocean between Gondwana and Laurussia is still not close during the beginning of the Carboniferous.

Derder, M. E. M.; Henry, B.; Bayou, B.; Ouabadi, A.; Bellon, H.; Djellit, H.; Khaldi, A.; Amenna, M.; Baziz, K.; Hemmi, A.; Guemache, M. A.

2006-06-01

183

Forearc basin correlations from around the Texas Orocline, New England Orogen, east Australia  

NASA Astrophysics Data System (ADS)

The late Paleozoic to early Mesozoic New England Orogen occupies much of the eastern seaboard of Australia. The orogen formed by west-dipping subduction (present-day coordinates) of the paleo-Pacific plate beneath eastern Gondwana. The southern part of the orogen exhibits a series of tight bends (oroclines) that are evident in the curvature of a Devonian-Carboniferous subduction complex, in particular the forearc basin and accretionary complex. The Emu Creek Block is thought to be part of the forearc basin that is exposed in the eastern limb of the Texas Orocline, but until now the tectonostratigraphic origin of the Emu Creek Block has only been inferred from limited geological data. Here we present detrital zircon geochronology (U/Pb ICP-MS ages), a new geological map of the block, and a revised stratigraphic section. Lithological investigation of strata within the block and the age distribution of detrital zircons indicate that the sediments in the Emu Creek Block were derived from a Carboniferous magmatic arc and were most likely deposited in a forearc basin. Our new geochronological constraints indicate deposition during the late Carboniferous. We therefore propose that rocks in the Emu Creek Block are arc-distal correlatives of the forearc basin in the opposing (western) limb of the Texas Orocline, specifically the Willuri and Currabubula formations. Extensive orocline-parallel structures in the forearc basin indicate that the eastern limb of the Texas Orocline was rotated in the course of oroclinal bending by approximately 135 degrees relative to the western limb. The correlation of the forearc basin blocks on opposite limbs of the Texas Orocline provides an independent constraint on its geometry and further improves our understanding of New England Orogen tectonostratigraphy and the crustal structure of eastern Australia.

Hoy, Derek; Rosenbaum, Gideon; Shaanan, Uri; Wormald, Richard

2014-05-01

184

Rapid vertebrate recuperation in the Karoo Basin of South Africa following the End-Permian extinction  

NASA Astrophysics Data System (ADS)

The mass extinction that occurred at the end of the Permian Period approximately 251 Mya is widely accepted as the most devastating extinction event in Earth's history. An estimated 75-90% of global diversity from both marine and terrestrial realms disappeared synchronously within at most one million and perhaps as little as 100,000 years. To date, most research has focused on the marine record and it is only recently that a few fully preserved terrestrial Permo-Triassic boundary sequences have been discovered. The main Karoo Basin of South Africa hosts several well-preserved non-marine Permo-Triassic boundary sequences that have been the focus of intensive research into the nature of the extinction and its possible causes. This study uses sedimentological and biostratigraphic data from boundary sequences near Bethulie in the southern Karoo Basin to make assumptions about the rates and timing of recovery of the terrestrial fauna in this portion of southern Gondwana after the extinction event. The biostratigraphic data gathered from 277 in situ vertebrate fossils allows us to define more accurately the temporal ranges of several taxa. These data also confirm a more precise extinction rate in this part of the basin of 54% of latest Permian vertebrate taxa, followed by the onset of a relatively rapid recovery, within an estimated 40-50 thousand years (based on the calculation of floodplain aggradation rates and compaction ratios) that included the origination of at least 12 new vertebrate taxa from amongst the survivors.

Botha, J.; Smith, R. M. H.

2006-08-01

185

Water Basins Civil Engineering  

E-print Network

Water Basins Civil Engineering Objective · Connect the study of water, water cycle, and ecosystems with engineering · Discuss how human impacts can effect our water basins, and how engineers lessen these impacts: · The basic concepts of water basins are why they are important · To use a topographic map · To delineate

Provancher, William

186

Sedimentary basin analysis constrained by 3d seismic and subsidence modelling: the case of the Phanerozoic evolution of the Dampier Sub-basin, North West Shelf of Australia.  

NASA Astrophysics Data System (ADS)

The North West Shelf of Australia has been a long term passive margin, which underwent a polyphased tectonic history associated with the disintegration of Eastern Gondwana. Several Phanerozoic sedimentary basins like the Northern Carnarvon Basin developed during the rifting phases culminating in the opening of the NeoTethys during the Late Paleozoic and the abyssal plains during the Mesozoic. In order to accurately constrain the Phanerozoic evolution of the proximal part of the Dampier Sub-basin (Mermaid Nose), a thorough 3D structural and stratigraphic analysis was performed on the basis of 2D/3D seismic data. It has enabled to highlight about twenty depositional sequences from Early Permian (Late Carboniferous?) to Late Cretaceous. The cuttings description of the deepest well of the area (Roebuck-1, 2871 mRT) was (has been) interpreted on the basis of the lithological changes and 19 units were highlighted from the Kungurian Kennedy Group to the Campanian Withnell Formation. The association of the 2D/3D seismic data and the regional Late Palaeozoic units described in the literature allows to generate a pseudo-well below Roebuck-1 total depth reaching the (Late Carboniferous?) Early Permian Lyons Group sequences. The sediments of the glacially-related Lyons Group have been interpreted on the seismic data as representing the first syntectonic infilling a half-graben. This extensional episode is linked to the NeoTethys rifting that extended up to the eastern Mediterranean area removing slivers of continents from Gondwana, known as the Cimmerian terranes. Stratigraphic, sedimentary and paleontological data provided by well and seismic analysis from the Mermaid Nose have been combined to produce subsidence curves. The subsidence modelling for the Mermaid Nose clearly emphasises the predominance of the effects of the NeoTethys rifting that took place under an ice-sheet whereas the extension coeval with the opening of the abyssal plains that occurred later and closer to the present day margin had only limited effects with the development of a restricted graben associated with faults reactivations.

Langhi, L.; Borel, G. D.

2003-04-01

187

Palaeoenvironmental and geochemical approach of Archaeocyath-rich facies from Lower Cambrian of Western Gondwana margin at Central Iberian Zone (Urda, Toledo Mountains, Spain)  

NASA Astrophysics Data System (ADS)

Archaeocyath-rich facies are located in a quarry close to Urda village, at Toledo Mountains, Spain. The outcrops belong to the Caliza de los Navalucillos Formation and they record a considerably high diverse archaeocyath assemblage in the Lower Cambrian successions from the Central Iberian Zone (Julivert et al. 1972 [1974]). In fact, it is first time recorded the presence of Agyrekocyathus, Dokidocyathus, and Plicocyathus in the Central Iberian Zone. Therefore Plicocyathus is no longer exclusive to biozone VI in Spain. The presence of Anthomorpha is characteristic for the early Botomian, presently early Stage 4 (ICS, 2009), and the assemblage corresponds to the biozone VII (late Ovetian, following the biozonation of Perejón & Moreno-Eiris, 2006). The fossiliferous part of the succession is formed by seven lithofacies, all of them tectonically folded and with a low grade metamorphic overprint. They are comprised by two main groups of facies: (a) mound-shaped to massive lithofacies (A1, A2, A3, A4) and (b) massive to bedded and nodular lithofacies (B1, B2, B3). Archaeocyaths occur in several facies: (A1) mound-shaped white marble with irregular to stromatactoid cavities; (A2) massive mottled white to grey limestone; (A3) massive grey limestone with slumps levels; (A4) massive archaeocyath-rich orange limestone; as well as in carbonate nodules embedded in siltstones and cherts (B1, B2 and B3). The best preserved assemblage comes from the nodule record, where fossils are partially pyritized. This type of preservation is exceptional and has never been described before. XRD and wavelength-dispersive electron microprobe analyses reveal the presence of pyrite and pyrrotine partially altered to iron oxides and hydroxides (hematite and goethite) surrounding the archaeocyath cups. In Central Iberian Zone, the development of mounds and nodular facies like those described here is unusual, although the Botomian marks the peak for Early Cambrian archaeocyathan-microbial mounds in Western Gondwana margin. Powdered microsamples have been analysed for their elemental and isotopic composition (?13C values range from + 0.41 to + 3.05). Sulphur minerals and silicates where analyzed with XRD and wavelength-dispersive electron microprobe. Major elements were measured with ICP-OES and minor and trace elements were analyzed with ICP-MS. These are the first palaeontological, sedimetological, geochemical and isotopical data provided to reconstruct the depositional environment of these Archaeocyath-rich facies at the Western Gondwana margin. References Julivert, M., Fontboté, J.M., Ribeiro, A., Nabais Conde L.E. 1972. Mapa tectónico de la Península Ibérica y Baleares, Escala 1: 1.000.000, Memoria Explicativa [1974], 113 pp. Instituto Geológico y Minero de España. Perejón, A., Moreno-Eiris, E. 2006. Biostratigraphy and palaeobiography of the archaeocyaths on the south-western margin of Gondwana. Zeitschrift der Deutschen Gesellschaft für Geowissenschaften 157 (4): 611-627.

Menéndez, Silvia; Rodríguez-Martínez, Marta; Moreno-Eris, Elena; Perejón, Antonio; Reitner, Joachim

2010-05-01

188

Ogaden Basin subsidence history: Another key to the Red Sea-Gulf of Aden tectonic puzzle  

SciTech Connect

Previous work has attempted to understand the tectonic evolution of the Red Sea-Gulf of Aden region through a focus upon plate kinematics and reconstruction of plate interactions in a two dimensional sense. A significant complement to the three dimensional puzzle can be derived from a critical examination of the vertical component, tectonic subsidence analysis. By removing the isostatic contributions of sediment loading and unloading, and fluctuations in sea level, the remaining thermal-mechanical contribution to a basin`s subsidence can be determined. Such an analysis of several Ogaden Basin wells reveals multiple pulses of tectonic subsidence and uplift which correspond to far-field tectonic activities in the Red Sea and Gulf of Aden. One of the more dramatic is a Jurassic tectonic pulse circa 145-130 m.a., and a later extensional event which correlates to a major subsidence event ubiquitous through-out the Gulf of Aden, related to Gondwana Land breakup activities. Tectonic uplift during the Tertiary coincides with early Red Sea rifting episodes. Such activities suggest the Ogaden Basin has been a relatively stable East African cratonic basin, but with heating-extension events related to nearby plate interactions. In terms of hydrocarbon generation, the use of steady state present day geothermal gradients, coupled with subsidence analysis shows that potential Paleozoic and Mesozoic source rocks initiated generation as early as the Jurassic. The generating potential of Paleozoic source rocks would only be exacerbated by later heating events. Furthermore, cooling and tectonic uplift during the Tertiary would tend to arrest on-going hydrocarbon generation for Jurassic source rocks in the Ogaden area.

Pigott, J.D. [Univ. of Oklahoma, Norman, OK (United States); Neese, D. [Maxus Energy, Dallas, TX (United States); Carsten, G. [Preussag Energie, Lingen (Germany)

1995-08-01

189

Upper Cisuralian palynology and palaeoclimate of Manuguru area Godavari basin, India and their global correlation  

NASA Astrophysics Data System (ADS)

The Permian system of the Palaeozoic Erathem is divided into three series, the Early Permian Cisuralian Series, the Middle Permian Guadalupian Series, and the Late Permian Lopingian Series. The Cisuralian Series encompasses the Asselian to Kungurian stages which constitute the basal part of the Gondwana supersequence I. In India, they are represented lithostratigraphically by the Talchir, Karharbari, and Barakar formations. This paper presents the palynological results from the Barakar Formation of the Upper Cisuralian Series from Manuguru which lies in the southeastern part of the Godavari basin. The succession studied comprises 35 subsurface samples from bore hole 1007 represented by clay, shale, sandstone, and coal. The palynofloras in this sequence have a homogenous composition demonstrating that not many significant floral changes took place through the considered stratigraphic range. The entire sequence is characterized by the dominance of nonstriate bisaccate genus Scheuringipollenites and sub-dominance of striate bisaccate genus Faunipollenites(= Protohaploxypinus). The other pollen genera among the nonstriate bisaccates are Rhizomaspora, Primuspollenites, Ibisporites, and Platysaccus. The striate bisaccates include Striatites, Striatopodocarpites, and Stroterosporites. The taeniate taxa are represented by Lueckisporites and Lunatisporites. The common monosaccate genera include Caheniasaccites, Potoniesporites, and Barakarites. Spores are less common and include Latosporites, Brevitriletes, Horriditriletes, Microbaculispora, and Callumispora. They characterize the palynofloral composition of the Lower Barakar Formation. The correlation of this assemblage with some of the biostratigraphic palynozones proposed previously for the Cisuralian sequences of the Paraná Basin of South America, Kalahari Karoo Basin of South Africa, Ruhuhu Basin of Tanzania, East Africa as well as palynoassemblages from South Victoria Land and Dronning Maud Land, Antarctica and Collie Basin of west Australia point out to their Early Permian (Late Sakmarian-Early Artinskian) age. Palynomorphs such as Botryococcus sp., Tetraporinia sp., Balmeela sp. and Leiosphaeridia sp. are also recorded which suggest that these sediments were deposited during post-glacial near shore, cool and humid environment.

K, Pauline Sabina; Jha, Neerja

2014-10-01

190

Biostratigraphy, taxonomic diversity and patterns of morphological evolution of Ordovician acritarchs (organic-walled microphytoplankton) from the northern Gondwana margin in relation to palaeoclimatic and palaeogeographic changes  

NASA Astrophysics Data System (ADS)

Acritarchs, the fossilizable, resting cysts of phytoplanktonic algal protists, are the dominant component of marine organic-walled microfossils in the Palaeozoic. The majority of acritarchs show strong similarities with dinoflagellate cysts in morphological and biogeochemical features, as well as distributional patterns in the sediments. The production of these organic-walled microfossils and their distribution and survivorship in the sediments were controlled by differences in ecological tolerances and life cycle (autecology) of the planktonic parent organisms. Calculation of evolutionary rates and development of a detailed diversity curve at specific level, form the basis for discussing the influence of global palaeoenvironmental perturbations on the evolution of organic-walled microphytoplankton in northern Gondwana during latest Cambrian through Ordovician times. The potential of acritarchs for biostratigraphic correlation at the regional scale (northern Gondwana domain) is much improved by our detailed revision of distributional patterns of 245 acritarch taxa. The most important Cambro-Ordovician acritarch bio-events are short periods of diversification, which also correspond to introduction of morphological innovations, observed in latest Cambrian and earliest Tremadoc, late Tremadoc, early Arenig, basal Llanvirn, and latest Ashgill, and an important extinction phase in the early Caradoc. Overall, acritarch diversity increased from the basal Ordovician up to the middle Llanvirn, then declined in the early and middle Caradoc. During Ashgill times, the assemblages are poorly diversified at the generic level as a result of a combined effect of sea level drawdown and onset of glacial conditions, but no major extinction event is observed in connection with the end-Ordovician biotic crisis. The peak in acritarch diversity during Middle Ordovician times appears to be correlated to maximum spread of palaeogeographical assembly. Acritarch dynamics appear largely uncorrelated to second order sea-level oscillations; the primary abiotic controls on acritarch evolution were palaeogeographical and the associated palaeoceanographic changes (especially during Middle Ordovician), and the end-Ordovician palaeoclimatic shift. The acritarch fossil record provides important information on the evolution of oceanic primary producers, however, the relationships between acritarch diversity, oceanic productivity, and evolution of invertebrate animals are proving much more complex than previously thought. In particular, the hypothesis of a causal relationship between changes in acritarch diversity and metazoan evolution in the Palaeozoic is not supported by our data.

Vecoli, Marco; Le Hérissé, Alain

2004-10-01

191

Pampean deformation in the Sierra Norte de Córdoba, Argentina: Implications for the collisional history at the western pre-Andean Gondwana margin  

NASA Astrophysics Data System (ADS)

In the Sierra Norte de Córdoba, Argentina, at the inferred western pre-Andean Gondwana margin, structural analyses show that Upper Proterozoic-Lower Cambrian strips of metamorphic clastic rocks underwent two stages of a compressive deformational history. The D1 deformation led to the formation of an S1 cleavage/foliation and affected an older granite. It is related to F1 folding around ˜N-S to NE-SW trending axes that partly record a steep plunge. Reconstructed fold structures display maximum wavelengths and amplitudes on a scale of hundreds of meters to kilometers. A steep to overturned dip of thick packages of metaconglomerates and metasandstones is related to this folding event. Also, because of variably oriented L1 lineations and dextral shearing, structures of the D1 deformation are assigned to different structural domains interpreted as the result of strain partitioning during dextral transpression. Strips of post-D1 granite and clastic mylonites with a dextral sense of shear are attributed to the second-stage deformational event. The late stage dextral shearing and mylonitization locally affected intrusions of granites and dacitic porphyries. In the country rocks it took place along preexisting S1 planes or locally developed S2/C2 planes related to F2 fold structures with steeply plunging axes. The regional metamorphism accompanying the deformation was in the range of the subgreenschist facies-greenschist facies transition and greenschist facies. The emplacement of synkinematic intrusions presumably followed active dextral shear zones. It cannot be excluded that during compressive deformation, older (normal) fault lines were reactivated and caused strain partitioning and later dextral shearing. After cessation of compressive deformation, granites and granodiorites intruded the deformed clastic succession and led to contact metamorphism of variable extent. Younger high-level intrusions record chilled margins also at angular xenoliths. Isotopic dates from granitoids, dacites, and metaclastic rocks in the Sierra Norte area and surroundings suggest that compressive deformations and metamorphism took place during the Early Cambrian Pampean orogeny. The deformational and metamorphic history can be attributed to either ridge subduction/collision or collision of the Pampean terrane with the western pre-Andean Gondwana margin. The two-stage kinematics suggests that (oblique?) collision was followed by a change to dextral displacements in the upper plate during the final state of and after collisional tectonics. The Sierra Norte area represented the upper (eastern) plate as supposed part of the Río de la Plata craton and its cover, overriding the lower plate that consisted of an accretionary complex in the west.

von Gosen, W.; Prozzi, C.

2010-04-01

192

Divergent/passive margin basins  

SciTech Connect

This book discusses the detailed geology of the four divergent margin basins and establishes a set of analog scenarios which can be used for future petroleum exploration. The divergent margin basins are the Campos basin of Brazil, the Gabon basin, the Niger delta, and the basins of the northwest shelf of Australia. These four petroleum basins present a wide range of stratigraphic sequences and structural styles that represent the diverse evolution of this large and important class of world petroleum basins.

Edwards, J.D. (Shell Oil Company (US)); Santogrossi, P.A. (Shell Offshore Inc. (US))

1989-01-01

193

CentralBasin Matador Arch Eastern  

E-print Network

63 41, 50, 19 16 21 24 68 69 74, 42 70 65 91 59 12, 72 87 47 32 13 100 WILLISTON BASIN MICHIGAN BASINSalina Basin East Texas Basin Midland Basin Delaware Basin Val Verde Basin Northwest Shelf CentralBasin Platform Matador Arch Eastern Shelf Hugoton Embayment 63 79 SANTA MARIA BASIN VENTURA BASIN LOS ANGELES

194

The Namuskluft and Dreigratberg sections in southern Namibia (Kalahari Craton, Gariep Belt): a geological history of Neoproterozoic rifting and recycling of cratonic crust during the dispersal of Rodinia until the amalgamation of Gondwana  

NASA Astrophysics Data System (ADS)

This paper presents combined U/Pb, Th/U and Hf isotope analyses on detrital and magmatic zircon grains together with whole-rock geochemical analyses of two basement and eight sedimentary rock samples from the Namuskluft and the Dreigratberg in southern Namibia (Gariep Belt). The sedimentary sections evolved during the Cryogenian on the SW part of the Kalahari Craton and where therefore deposited in an active rift setting during the break-up of Rodinia. Due to insufficient palaeomagnetic data, the position of the Kalahari Craton within Rodinia is still under discussion. There are possibilities to locate Kalahari along the western side of Australia/Mawsonland (Pisarevski et al. in Proterozoic East Gondwana: supercontinent assembly and break-up, Geological Society, London, 2003; Evans in Ancient Orogens and modern analogues. Geological Society, London, 2009; and others) or together with the Congo-Sao Francisco and Rio de la Plata Cratons (Li et al. in Prec Res 45: 203-2014, 2008; Frimmel et al. in Int J Earth Sci (Geol Rundsch) 100: 323-354, 2011; and others). It is sill unclear which craton rifted away from the Kalahari Craton during the Cryogenian. Although Middle to Upper Cryogenian magmatic activity is known for the SE Kalahari Craton (our working area) (Richtersveld Suite, Rosh Pinah Fm), all the presented samples show no U/Pb zircon ages younger than ca. 1.0 Ga and non-older than 2.06 Ga. The obtained U/Pb ages fit very well to the exposed basement of the Kalahari Craton (1.0-1.4 Ga Namaqua Province, 1.7-2.0 Ga Vioolsdrif Granite Suite and Orange River Group) and allow no correlation with a foreign craton such as the Rio de la Plata or Australia/Mawsonland. Lu-Hf isotopic signatures of detrital zircon point to the recycling of mainly Palaeoproterozoic and to a smaller amount of Archean crust in the source areas. ?Hf( t) signatures range between -24 and +14.8, which relate to TDM model ages between 1.05 and 3.1 Ga. Only few detrital zircon grains derived from magmas generated from Mesoproterozoic crustal material show more juvenile ?Hf( t) signatures of +14, +8 to +4 with TDM model ages of 1.05-1.6 Ga. During Neoproterozoic deposition, only old cratonic crust with an inherited continental arc signature was available in the source area clearly demonstrated by Hf isotope composition of detrital zircon and geochemical bulk analysis of sedimentary rocks. The granodiorites of the Palaeoproterozoic basement underlying Namuskluft section are ca. 1.9 Ga old and show ?Hf( t) signatures of -3 to -5.5 with TDM model ages of 2.4-2.7 Ga. These basement rocks demonstrate the extreme uplift and deep erosion of the underlying Kalahari Craton at its western margin before general subsidence during Cryogenian and Ediacaran time. The sedimentary sequence of the two examined sections (Namuskluft and Dreigratberg) proposes the presence of a basin and an increasing subsidence at the SW part of the Kalahari Craton during the Cryogenian. Therefore, we propose the initial formation of an intra-cratonic sag basin during the Lower Cryogenian that evolved later to a rift basin at the cratonic margin due to increasing crustal tension and rifting together with the opening of the Adamastor Ocean. As the zircons of the sedimentary rocks filling this basin show neither rift-related U/Pb ages nor an exotic craton as a possible source area, the only plausible sedimentary transport direction providing the found U/Pb ages would be from the E or the SE, directly from the heart of the Kalahari Craton. Due to subsidence and ongoing sedimentation from E/SE directions, the rift-related magmatic rocks were simply covered by the input of old intra-cratonic material that explains the absence of Neoproterozoic zircon grains in our samples. The geochemical analyses show the erosion of a continental arc and related sedimentary rocks with an overall felsic provenance. The source area was a deeply eroded and incised magmatic arc that evolved on continental crust, without any evidence for a passive margin. All of this can be explained by the erosion of rocks related

Hofmann, Mandy; Linnemann, Ulf; Hoffmann, Karl-Heinz; Gerdes, Axel; Eckelmann, Katja; Gärtner, Andreas

2014-07-01

195

Wash-resistance and field evaluation of alphacypermethrin treated long-lasting insecticidal net (Interceptor) against malaria vectors Anopheles culicifacies and Anopheles fluviatilis in a tribal area of Orissa, India.  

PubMed

A field trial was conducted on the efficacy of Interceptor nets-a long-lasting insecticidal net (LLN) factory treated with alphacypermethrin 0.667% (w/w) corresponding to 200mg/m(2), against malaria vectors Anopheles culicifacies and Anopheles fluviatilis in one of the highly endemic areas of Orissa. The study area comprised 19 villages which were randomized into three clusters and designated as Interceptor net cluster, untreated net cluster, and no net cluster. Baseline studies showed that both the vector species An. culicifacies and An. fluviatilis were 100% susceptible to alphacypermethrin. Results of wash-resistance and bio-efficacy of Interceptor nets showed 100% mortality in An. culicifacies and An. fluviatilis even after 20 washings. Bioassays on the Interceptor nets while in use in the field conditions showed a knockdown effect on 70-90% mosquitoes during different months of intervention after 3 min of exposure and 100% mortality was recorded after 24h of recovery period. The median knockdown time for these species ranged between 4.10-5.25 min and 4.00-5.00 min respectively during intervention period. In Interceptor net study area, there was a significant reduction of 88.9, 96.3 and 90.6% in the entry rate of An. culicifacies, An. fluviatilis and other anopheline species respectively with an over all reduction of 87.5% in total mosquitoes. The overall feeding success rate of mosquitoes in the trial villages was only 12.8% in comparison to 35.0 and 78.8% in villages with untreated nets and no nets respectively. A significant reduction was also recorded in parity rate and human blood index of vector species in Interceptor net area. The results of the study showed that Interceptor nets are effective against the malaria vectors and may be used as a suitable intervention strategy in high-risk areas. PMID:20465990

Sharma, Surya K; Upadhyay, Ashok K; Haque, Mohammed A; Tyagi, Prajesh K; Raghavendra, K; Dash, Aditya P

2010-10-01

196

Efficacy of permethrin treated long-lasting insecticidal nets on malaria transmission and observations on the perceived side effects, collateral benefits and human safety in a hyperendemic tribal area of Orissa, India.  

PubMed

Studies were conducted on the efficacy of Olyset nets-a long-lasting insecticidal net (LLIN) factory treated with 2% (w/w) permethrin on malaria transmission in an area under the influence of pyrethroid susceptible vector species Anopheles culicifacies and A. fluviatilis in Sundargarh District, Orissa, India. The study area comprised 22 villages that were randomized into three clusters and designated as Olyset net, untreated net, and no net area. Malaria incidence in the study population was measured through longitudinal active surveillance at fortnightly intervals. There was a reduction of 65-70% in malaria incidence in Olyset net area as compared to the control areas. The attack rate of Plasmodium falciparum or number of episodes per person per year in different age groups also showed significant reduction in Olyset net area as compared to untreated net and no net areas. Cross-sectional point prevalence surveys showed 45.7% reduction of malaria prevalence in Olyset net users, whereas there was an increase of 33.3% and 51% in untreated net and no net villages respectively. The compliance rate of Olyset net usage in the study population was 80-98% during different months, whereas it was between 70% and 90% for untreated nets. There were minimal complains of skin irritation (4%), itching (8%) and eye irritation (1.2%). However, these effects were only transitory in nature lasting for few hours of the first usage. Olyset nets also provided collateral benefits in terms of relief not only from mosquitoes and malaria but also from other household pests such as head lice, bed bugs, cockroaches, ants and houseflies. The Olyset nets were found to be safe to humans as no adverse event was recorded in the net users that can be attributed to the use of net. The study showed that Olyset nets are effective personal protection tool that can be used in a community based intervention programme. PMID:19647715

Sharma, Surya K; Tyagi, Prajesh K; Upadhyay, Ashok K; Haque, Mohammed A; Mohanty, Suman S; Raghavendra, Kamaraju; Dash, Aditya P

2009-11-01

197

Magnetic Fabric of the Itararé Group, Paraná Basin Brazil: Preliminary Results  

NASA Astrophysics Data System (ADS)

The late Paleozoic Itararé Group and equivalent beds in the Paraná Basin of Brazil extend into Paraguay, Argentina, and Uruguay. The Itararé Group contains the most extensive lithological record of Gondwana glaciation in the world. The succession has a maximum subsurface thickness of around 1400 m and extends over a total area greater than 1 million km2. The lower boundary of the Itararé Group is nonconformable with Precambrian to early Paleozoic crystalline basement and with Devonian strata of the Furnas and Ponta Grossa Formations, which together constitute the base of the Gondwana supersequence of the Paraná Basin. This boundary encompasses a hiatus that is loosely estimated in 45 Ma. The upper contact with the overlying Rio Bonito Formation is described as conformable to partially erosional. We performed our study on 13 sites from sedimentary rocks (sandstones and siltites) from the Itararé beds in the Brazilian portion of the Paraná Basin (mainly in São Paulo State). Magnetic fabrics were determined on oriented cylindrical specimens (2.54 cm x 2.2 cm) using the anisotropy of low-field magnetic susceptibility (AMS). Rock-magnetic analyses reveal that magnetite is the main magnetic mineral. In one of the sampled site, however, the ferromagnetic minerals are both magnetite and hematite. Regarding the eingenvector orientations, the sites usually gave good results. The analysis at the individual-site scale defines three AMS fabric types. The first type (7 sites) shows Kmin perpendicular to the bedding plane while Kmax and Kint are scattered within the bedding plane itself. This fabric is usually interpreted as primary (sedimentary-compactional), typical of undeformed sediments. The second type (5 sites) shows good clustering of the AMS principal axes with Kmin still sub-perpendicular to the bedding plane. The third type, pertaining to an intensely folded site previously interpreted as slumped, is characterized in geographic coordinates by well-clustered Kmax in the bedding plane, while Kmin and Kint are distributed along a NE-SW girdle with a sub-vertical, yet elongate Kmin distribution. In stratigraphic coordinates Kmax maintains the same NNW-SSE clustering, yet Kmin and Kint become scattered within the girdle. The second fabric type would be interpreted as combination of sedimentary-compactional and tectonic contributions if some strain markers or evidence for tectonic deformation had been found in the studied area. On the other hand, the tight Kmax grouping in this fabric type could be explained by the action of currents since they cause Kmax to be aligned sub-parallel to the paleocurrent direction.

Raposo, M. B.; Bilardello, D.; Santos, P. R.

2012-12-01

198

The Tunas Formation (Permian) in the Sierras Australes foldbelt, east central Argentina: evidence for syntectonic sedimentation in a foreland basin  

NASA Astrophysics Data System (ADS)

The Tunas Formation, extensively exposed in the Sierras Australes foldbelt of eastern central Argentina, completes the sedimentation of the Gondwanan (Late Carboniferous-Permian) sequence, locally known as the Pillahuincó Group. The underlying units of the Group show an integrated depositional history which can be explained in terms of glaciomarine sedimentation (Sauce Grande Formation) and postglacial transgression (Piedra Azul and Bonete Formations). This succession also has a rather uniform quartz-rich, sand-sized composition indicative of a cratonic provenance from the Tandilia Massif to the northeast. Early to Late Permian deformation folded and thrusted the southwestern basin margin (Sierras Australes) and triggered the deposition of a 1,500 m — thick, synorogenic prograding wedge, the Tunas Formation, in the adjacent foreland basin (Sauce Grande or Claromecó Basin). Sandstone detrital modes for the Tunas deposits show moderate to low contents of quartz and abundant lithics, mostly of volcanic and metasedimentary origin. Paleocurrents are consistently from the SW. Tuffs interbedded with sandstones in the upper half of Tunas Formation (Early — early Late? Permian) are interpreted as being derived from volcanic glass-rich tuffs settled in a body of water. Extensive rhyolitic ignimbrites and consanguineous airborne tuffaceous material erupted in the northern Patagonian region during that period. The age constraints and similarities in composition between these volcanics and the tuffaceous horizons present in the Sauce Grande, Parana and Karoo Basins suggest a genetic linkage between these two episodes. The intimate relationship between volcanic activity inboard of the paleo-Pacific margin, deformation in the adjacent orogenic belt and subsidence and sedimentation in the contiguous foreland basin constitutes a common motif in the Sauce Grande and Karoo Basins of southwestern Gondwana.

Lopez-Gamundi, O. R.; Conaghan, P. J.; Rossello, E. A.; Cobbold, P. R.

1995-04-01

199

Thermochronological Constraints on Detrital Sediments of the Late Permian Karoo Basin: Insights Into Uplift History of the Cape Fold Belt  

NASA Astrophysics Data System (ADS)

The Karoo Basin and its equivalents cover most of southern Africa, with correlative basins found also in South America. The vast geographic expanse of these basins indicates a common history of deposition along the active Panthalassan margin of southern Gondwana. The early Paleozoic history of the Karoo Basin is marked by early glacio-marine to later shallow marine-deltaic sedimentation with a final shift to a continental setting by the late Permian. In South Africa, this transition to a fluvial environment is defined by the deposition of the Beaufort Group, a ca. 5 km thick sequence of meandering river channel sandstones and muddy overbank deposits. We have identified an 800 m thick sequence of the lowermost Beaufort Group where magnetostratigraphy and U-Pb dating of zircon in volcanic tuffs establish a depositional age of 264-268 Ma. Detrital zircon from sandstone samples were dated by U-Pb SHRIMP, revealing age populations typical of the cratonic/metamorphic provinces of the Kalahari craton (Kaapval and Namaqua-Natal provinces) as well as late Paleozoic magmatic zircons probably from southern South America. Populations of detrital muscovite dated using the 40Ar/39Ar step-heating technique are dominated by a tight cluster of ca. 272 Ma cooling ages, indicating rapid exhumation of the tectonically active Cape Fold belt and short lag times (4-8 Ma) for detritus deposited into the Karoo foreland basin, similar to rates observed for modern sediments of Himalayan-draining rivers. Ongoing work will reveal whether the Cape Belt is the source for the sediments of the Karoo foreland basin.

Tohver, E.; Arosio, R.; Schmieder, M.; Jourdan, F.; Wilson, A.; Flint, S.

2012-12-01

200

Refined stratigraphy of the Middle Permian Abrahamskraal Formation (Beaufort Group) in the southern Karoo Basin  

NASA Astrophysics Data System (ADS)

Fluvially deposited rocks of the Abrahamskraal Formation of the lower Beaufort Group in the South African Karoo record sediment deposition during the Middle Permian, the earliest terrestrial environment of Gondwana. A rich diversity of fossil tetrapods from this Formation provides a unique opportunity for understanding Middle Permian biodiversity changes in Gondwanan terrestrial ecosystems, but this is dependent on the existence of a robust stratigraphic framework that has been hampered by lack of lateral continuity of lithological markers combined with structural complexities relating to formation of the Cape Fold Belt. Because the Abrahamskraal Formation covers a large geographic area of the main Karoo Basin previous stratigraphic studies have been undertaken over large areas. This study combines geology and palaeontology to refine the stratigraphy of the Abrahamskraal Formation in a part of the southwestern Karoo Basin and revealed mappable lithological units with lateral continuity throughout the study area. The measured stratigraphic section manifests a total thickness of 2565 m for the Formation (the thickest occurrence of the Abrahamskraal Formation in the Beaufort Group). For the first time stratigraphic ranges of biostratigraphically important Middle Permian index taxa which have restricted stratigraphic ranges have been determined and, apart from dicynodonts, include the parareptile Eunotosaurus and the biarmosuchid therapsid Hipposaurus. The Abrahamskraal Formation comprises a 1104 m thick basal Eodicynodon Assemblage Zone, overlain by a 1441 m thick Tapinocephalus Assemblage Zone whose upper limit is 20 m below the Poortjie Member of the Teekloof Formation.

Jirah, Sifelani; Rubidge, Bruce S.

2014-12-01

201

Leaiid conchostracans from the uppermost Permian strata of the Paraná Basin, Brazil: Chronostratigraphic and paleobiogeographic implications  

NASA Astrophysics Data System (ADS)

Conchostracan fossils are abundant and relatively diversified in the Rio do Rasto Formation (Passa Dois Group, Paraná Basin, southern Brazil), but leaiids (' Leaia pruvosti' [Reed, F.R.C., 1929. Novos Phyllopodos Fósseis do Brasil. Boletim do Serviço Geológico e Mineralógico do Brasil 34, 2-16]) were previously found at only one locality of the formation in the northern Santa Catarina State. New specimens of the Family Leaiidae, collected from two outcrops in central Paraná State near the top of the formation, stimulated a revision of related taxa. Both the new and the previously known leaiids are herein assigned to Hemicycloleaia mitchelli [Etheridge Jr., R., 1892. On Leaia mitchelli Etheridge. Proceedings of the Linnean Society of New South Wales 7, 307-310] based on the presence of three carinae and subovate shape. This species was originally recorded in the upper Tatarian (Wuchiapingian, Late Permian) of Sydney Basin, eastern Australia and therefore corroborates the interpretation that the leaiid bearing strata of the Rio do Rasto Formation cannot be younger than Permian. H. mitchelli possibly was one of the most widespread, eurytopic and conservative Late Paleozoic conchostracans of Gondwana (although records from Africa, India and Antarctica must still be confirmed) and it was also found in the Tatarian of Russia. The sudden disappearance of leaiids after their apparent success is consistent with the hypothesis about the biotic crisis around the Permo-Triassic boundary.

Ferreira-Oliveira, Luis Gustavo; Rohn, Rosemarie

2010-03-01

202

Stratigraphy and reservoir potential of glacial deposits of the Itarare Group (Carboniferous-Permian), Parana basin, Brazil  

SciTech Connect

Drilling in the Parana basin of Brazil in the mid-1980s discovered gas and condensate in the Itarare Group, and showed that glacial deposits in Brazil can contain hydrocarbons. The reservoir potential of the Carboniferous-Permian Itarare Group of the basin is analyzed using new subsurface data from 20 deep wells drilled in the early to middle 1980s. Central to the analysis was the construction of over 3000 km of cross sections based on more than 100 wells, the description of more than 400 m of core, and study of 95 thin sections. Subsurface exploration and mapping of the Itarare are greatly aided by the recognition of three recently defined and described formations and four members, which are traceable for hundreds of kilometers. These units belong to three major glacial cycles in which the pebbly mudstones and shales are seals and glacially related sandstones are reservoirs. The best sandstone reservoirs in the deep subsurface belong to the Rio Segredo Member, the upper-most sandy unit of the Itarare. The Rio Segredo Member is the best petroleum target because it is overlain by thick seals and massive pebbly mudstones and shales, and because it is shallower and less compacted than underlying, more deeply buried sandstones. This member has little detrital matrix and much of its porosity is secondary, developed by carboxylic acid and CO{sub 2} generated when Jurassic-Cretaceous basalts, sills, and dikes were intruded into the Parana basin as Gondwana broke up.

Franca, A.B. (Petrobras/Depex/Nexpar, Curitiba (Brazil)); Potter, P.E. (Univ. of Cincinnati, OH (United States))

1991-01-01

203

ST. LAWRENCE RIVER BASIN  

E-print Network

#12;983 22 ST. LAWRENCE RIVER BASIN system can travel at least 3260km from western Lake Superior the river system draws sustenance from nine states (Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio surviving record of the basin's exploration by Europeans dates to 1535, during a period of exploration

Thorp, James H.

204

MICHIGAN BASIN PROVINCE (063)  

Microsoft Academic Search

Indiana, five counties in northwest Ohio, and adjoining parts of the Great Lakes. The Michigan Basin is a classic interior cratonic basin whose edges are defined by a series of highs. Counterclockwise from the west, these are the Wisconsin Arch, the Kankakee Arch, the Findlay Arch of Ohio, Algonquin Arch of Ontario, and the Canadian Shield. Virtually the entire assessment

Gordon L. Dolton

205

ROANOKE RIVER BASIN DATA  

EPA Science Inventory

Data files for the Roanoke River Basin provided for use with the Roanoke River Basin Reservoir Model. Includes data on daily pan evaporation, monthly water usage and daily inflow. (see http://www.dwr.ehnr.state.nc.us/roanoke/index.htm)...

206

WILLISTON BASIN PROVINCE (031)  

Microsoft Academic Search

Plains and extends northward into Canada. The basin region is a generally flat lying, moderately dissected plain with minimum topographic relief. The basin is bordered on the east and southeast by the Canadian Shield and the Sioux Uplift. The western and southwestern borders are defined by the Black Hills Uplift, Miles City Arch, Porcupine Dome, and Bowdoin Dome. The United

James A. Peterson; James W. Schmoker

207

K Basins hazard analysis  

SciTech Connect

The 105-K East (KE) and 105-K West (KW) Basins in the 100 K Area of the Hanford Site have been used for storage of irradiated N Reactor and single-pass reactor fuel. Remaining spent fuel is continuing to be stored underwater in racks and canisters in the basins while fuel retrieval activities proceed to remove the fuel from the basins. The Spent Nuclear Fuel (SNF) Project is adding equipment to the facility in preparation for removing the fuel and sludge from the basins. In preparing this hazard analysis, a variety of hazard analysis techniques were used by the K Basins hazard analysis teams, including hazard and operability studies, preliminary hazard analyses, and ''what if'' analyses. This document summarizes the hazard analyses performed as part of the safety evaluations for the various modification projects and combines them with the original hazard analyses to create a living hazard analysis document.

MCCALL, T.B.

2002-10-09

208

K Basin Hazard Analysis  

SciTech Connect

The 105-K East (KE) and 105-K West (KW) Basins in the 100 K Area of the Hanford Site have been used for storage of irradiated N Reactor and single-pass reactor fuel. Remaining spent fuel is continuing to be stored underwater in racks and canisters in the basins while fuel retrieval activities proceed to remove the fuel from the basins. The Spent Nuclear Fuel (SNF) Project is adding equipment to the facility in preparation for removing the fuel and sludge from the basins. In preparing this hazard analysis, a variety of hazard analysis techniques were used by the K Basins hazard analysis teams, including hazard and operability studies, preliminary hazard analyses, and ''what if'' analyses. This document summarizes the hazard analyses performed as part of the safety evaluations for the various modification projects and combines them with the original hazard analyses to create a living hazard analysis document.

MCCALL, T.B.

2002-03-21

209

Drainage Basins Field Lab  

NSDL National Science Digital Library

This exercise begins with a field trip to the San Gabriel Mountain foothills near our campus. Students are given a set of topographic maps and asked to follow our progress as we hike into a small drainage basin in the Claremont Wilderness Park. Through interactive discussion, we explore regional landscape and the geomorphic form, function, and processes of a drainage basin system. Students are expected to complete their assignment on drainage basin analysis during the following week, working from the maps provided. Students are asked to identify the basic landscape units in the San Gabriel Mountain foothill region, delineate a set of drainage basins, and analyze the geomorphic characteristics of these basins using longitudinal profiles and morphometric indices. From this information, they are expected to draw basic conclusions about the geomorphic processes affecting this landscape system, and its relative state of equilibrium. Designed for a geomorphology course

Jeff Marshall

210

Early Cretaceous volcano-sedimentary successions along the eastern Australian continental margin: Implications for the break-up of eastern Gondwana  

Microsoft Academic Search

We report on three large volume Early Cretaceous volcanic and sedimentary provinces: the Whitsunday Volcanic Province and Great Artesian Basin system, both of northeastern Australia, and the Otway\\/Gippsland basin system along the southeastern margin of Australia. The Whitsunday Volcanic Province is part of a mafic to silicic, high-K calc-alkaline pyroclastic volcanic belt that extends for more than 900 km along

S. E Bryan; A. E Constantine; C. J Stephens; A Ewart; R. W Schön; J Parianos

1997-01-01

211

Geochemistry, zircon U-Pb geochronology and Hf isotopes of granites in the Baoshan Block, Western Yunnan: Implications for Early Paleozoic evolution along the Gondwana margin  

NASA Astrophysics Data System (ADS)

The leucogranites in the Baoshan Block of the Tethyan belt in Western Yunnan, are composed mainly of two-mica granite with subordinate muscovite granite. Here we present zircon U-Pb ages from four intrusions that show ages of 448-476 Ma suggesting that these rocks were emplaced during the Ordovician. The leucogranites are high-K calc-alkaline and strongly peraluminous, with K2O/Na2O > 1 and A/CNK = 1.12-1.54. These rocks are enriched in large-ion lithophile elements (LILEs) and light rare-earth elements (LREEs) [(La/Yb)N = 1.13-32.4] and Pb, and are depleted in high field-strength elements (HFSEs). They show similar chondrite-normalized REE patterns, with negative Eu anomalies (Eu/Eu* = 0.03-0.46). A wide range of zircon ?Hf(t) values (- 9.6 to - 2.6) and varying Hf-isotope crustal model ages (2.1-1.6 Ga) are also observed. The geochemical signatures indicate that the leucogranites are S-type granites derived mainly from the anatexis of ancient crustal materials. The ages, geochemistry and tectonics in the Baoshan Block and the Lhasa Terrane are closely comparable, suggesting that the Baoshan Block might represent part of an Early Paleozoic magmatic arc in the Gondwana continental margin facing the proto-Tethyan Ocean. The Pinghe granites of the early phase in the Baoshan Block which are coeval with the Cambrian magmatism (ca. 492 Ma) identified in the central and southern Lhasa subterranes can be interpreted as products of the slab break-off associated with the subduction of proto-Tethyan oceanic lithosphere. However, the late leucogranite stocks are analogous to the North Himalayan leucogranites, which formed in a short-lived extensional setting caused by the slab break-off associated with the subduction-collision system.

Dong, Meiling; Dong, Guochen; Mo, Xuanxue; Santosh, M.; Zhu, Dicheng; Yu, Junchuan; Nie, Fei; Hu, Zhaochu

2013-10-01

212

A new Late Triassic age for the Puesto Viejo Group (San Rafael depocenter, Argentina): SHRIMP U-Pb zircon dating and biostratigraphic correlations across southern Gondwana  

NASA Astrophysics Data System (ADS)

The Puesto Viejo Group crops out in the San Rafael Block, southwest Mendoza, at approximately 35° S and 68°20? W. It consists of the basal mainly grayish Quebrada de los Fósiles Formation (QF) overlying by the reddish Río Seco de la Quebrada Formation (RSQ). The basal unit includes both plant remains (pleuromeians and sphenopsids) and vertebrates (scattered fish scales, dicynodont synapsids and remains of an archosauriform). In contrast, the RSQ beds have yielded only tetrapods, although a more diverse fauna. The latter includes cynodonts as Cynognathus, Pascualognathus and Diademodon, and also dicynodonts (Vinceria and Kannemeyeria). Based on the assemblage of tetrapod taxa the bearing levels were correlated to the Cynognathus AZ of South Africa and thus referred to the Middle Triassic (Anisian). We obtained a SHRIMP 238U/206Pb age of 235.8 ± 2.0 Ma from a rhyolitic ignimbrite interdigitated between the QF and RSQ formations at the Quebrada de los Fósiles section. This new radiometric date for the Puesto Viejo Group suggests that the tetrapod fauna in the RSQ beds existed, instead, during the Late Triassic (early Carnian) some 10 Ma later than the currently accepted age. Two scenarios might explain our results: first, the Cynognathus AZ of South Africa is wrongly assigned to the lower Middle Triassic (Anisan) and should be considered younger in age, Late Triassic (Carnian); second, the relative age of the Cynognathus AZ of South Africa is correct but the inferred range of Cynognathus and Diademodon is incorrect as they were present during the Late Triassic (Carnian) at least in South America. In any case, this new date pose serious doubts about the validity of biostratigraphic correlations based solely on tetrapod taxa, a common practice for Triassic continental successions across Gondwana.

Ottone, Eduardo G.; Monti, Mariana; Marsicano, Claudia A.; de la Fuente, Marcelo S.; Naipauer, Maximiliano; Armstrong, Richard; Mancuso, Adriana C.

2014-12-01

213

UPPER SNAKE RIVER BASIN, PRELIMINARY BASIN EVALUATION  

EPA Science Inventory

The purpose of this paper was to provide a process and a plan by which the Environmental Protection Agency can insure that water quality goals established in the Water Pollution Control Act Amendments of 1972 are met in the waters of the Upper Snake Basin (17040201, 17040206, 170...

214

Phanerozoic tectono-stratigraphic evolution of the Trans-Pecos and Permian basin regions (Mexico, Texas, New Mexico) using Landsat imagery, subsurface and outcrop data  

SciTech Connect

Integrating regional Landsat imagery, outcrop field studies, and subsurface data has resulted in a more comprehensive understanding and delineation of the tectono-stratigraphic evolution of the Trans-Pecos region. Landsat imagery were acquired and registered to the existing 1:25000 scale maps and mosaiced to create a regional view of the Trans-Pecos and Permian basin region. The imagery were used to extrapolate and map key stratigraphic and tectonic elements after calibration from documented outcrop and subsurface data. The interpretations aided in the extrapolation of scattered control information and were critical in the complete reconstruction of the geologic history of the area. The Trans-Pecos Phanerozoic history comprises five tectono-depositional phases, and these have controlled the shape of the modem landscape: (1) Late Proterozoic rifting (Gondwana from Laurentia), and development of the Early-Middle Paleozoic Tobosa basin; (2) Pennsylvanian collision (South and North Americas), and differentiation of the Tobosa basin into the Midland, Delaware, Orogrande, and Pedregosa basins separated by basement blocks: Central Basin Platform, Diablo Platform, Burro-Florida Platform; (3) Middle Mesozoic transtensional rifting (Mexico from North America), and Late Jurassic failed rifting of the Mexican Chihuahua and Coahuila Troughs west and south of the Diablo Platform; (4) Late Mesozoic Laramide collision (Mexico and Texas), and development of the Chihuahua fold/thrust belt limited by the western margin of the Diablo Platform; (5) Late Cenozoic North American basin and Range rifting, and development of Rio Grande grabens, block-faulted mountains, and volcanics. The Tobosa basin was a passive-margin interior sag; its continental margin was south of the Marathons.

Markello, J.R.; Sarg, J.F. [Mobil Technology Corporation, Dallas, TX (United States)

1996-08-01

215

Late Permian Palynology and depositional environment of Chintalapudi sub basin, Pranhita-Godavari basin, Andhra Pradesh, India  

NASA Astrophysics Data System (ADS)

The present study deals with the palynological dating, correlation and depositional setting of the sediments from bore cores MGP-11 and MGP-4 from Gauridevipet area of Chintalapudi sub-basin of Godavari master basin, south India. On the basis of palynological studies, three palynoassemblages have been identified, one in bore core MGP-11 a Faunipollenites (=Protohaploxypinus) and Striasulcites assemblage and two in bore core MGP-4; one is characterized by the dominance of striate bisaccates and Densipollenites and the other by Striatopodocarpites and Cresentipollenites palynoassemblages. The other stratigraphically significant taxa include Guttulapollenites hannonicus, Lunatisporites noviaulensis, Lunatisporites pellucidus, Densoisporites contactus, Chordasporites australiensis, Goubinispora spp., Lundbladispora microconata, Lundbladispora raniganjensis and Klausipollenites schaubergeri. The recovered taxa suggest a Late Permian, Lopingian age for these rocks. This interpretation is based on the correlation of the assemblages with similar assemblages from previous Gondwana studies chiefly Densipollenites magnicorpus Zone of Damodar Basin, India and Late Permian palynoassemblages from Africa, Antarctica, Australia and South America. On the basis of palaeobotanical affinity of the identified microflora it has been inferred that the peat forming plant community was composed mainly of gymnosperm pollen attributable to glossopterids, that includes striate and non-striate bisaccates and paucity of cordaites which includes monosaccates. Spores are subordinate and are derived from lycopsids (Lundbladispora, Densoisporites), sphenopsids (Latosporites) and filicopsids (Horriditriletes, Lophotriletes, Verrucosisporites, Osmundacidites, Leiotriletes, Callumispora, Brevitriletes and Microbaculispora) occurring in variable proportions. The dominance of subarborescent/arborescent vegetation suggests a development in a forest swamp probably in a small distant marginal part of the mire or periods of standing water. This flooding environment favoured the growth of herbaceous lycopsids, filicopsids and sphenopsids in the palaeomire. More or less similar environments of deposition have been deduced for both the sedimentary sequences on the basis of palynofacies analysis. Anaerobic, reducing, water logged peat-forming conditions have been inferred based on the abundance of phytoclasts. The relative abundance of structured organic matter implies the existence of a fairly dense vegetation cover in the hinterland. The charcoal fragments recovered from the present study area reflects a possible wildfire in the accumulated swamps or a wildfire in the hinterland after which the sediments were flushed by fluvial systems into the swamps.

Jha, Neerja; Pauline Sabina, K.; Aggarwal, Neha; Mahesh, S.

2014-01-01

216

Tectono-stratigraphic evolution and exhumation of the Haymana basin: Unravelling the subduction and collision history of Neotethys in Turkey  

NASA Astrophysics Data System (ADS)

The Haymana basin straddles the Izmir-Ankara-Erzincan Suture Zone (IAESZ) in the north and Intra-Tauride Suture Zone (ITSZ) in the south. The two suture zones developed in response to the subduction and demise of Neotethys Ocean in Turkey during the late Cretaceous to early Tertiary; the tectonic significance of the basin and its relationship with the ITSZ are still poorly constrained. In order to unravel subduction and subsequent collision history of the Neotethys in the region, we have carried out a detailed analysis of the stratigraphy and sedimentology of the Haymana basin infill and, using a combination of palaeomagnetic and thermochronometric data we have unravelled its structural evolution since its formation. The basin developed on the IAESZ and comprises fore-arc late Cretaceous to foreland Middle Eocene sedimentary sequences. The analysis of the sedimentogical facies and depositional environments indicate four Late Cretaceous to Paleogene key sequences in the basin. These sequences grade laterally and vertically into each other and are continuous from the late Cretaceous to Eocene whereas local progressive syn-sedimentary unconformities and frequent depocenter migrations are common. Late Cretaceous sequences fine upward whereas coarsening upwards sequences are common in the later units. These characteristics possibly reflect the response to local uplift and subsidence in front of south-verging thrust faults associated with the transition from fore-arc to foreland basin settings, following the terminal subduction of the Neotethys at the end of Cretaceous. About 4000 paleomagnetic and magnetostratigraphic data from the basin infill units and the Neogene cover indicate large clockwise vertical axes rotations in the NW and counter-clockwise rotations in the SE part of the basin. We suggest that these rotations are related to the northward movement and indentation of the Gondwana-derived continental blocks into Eurasia. A model of southward thrust propagation is also supported by apatite fission track (AFT) and (U+Th)/He thermochronometric data from 12 samples of basin infill, which show a consistent northward age increase. The major change in the rotation senses and structural trends within the basin are related to a large strike-slip fault which might be the westward extension into the Haymana Basin of the Savc?l? Thrust Zone, an important structural feature that separated the K?rsehir Block into two sectors.Fault kinematic analysis, based on 2000 fault slip data from 50 stations, indicates that the basin was subjected to NE-SW directed compression and coeval E-W extension during the late Cretaceous to Neogene. Constructed and balanced cross-sections for different time intervals indicate northward thickening, wedge-like geometry of the basin and large vertical axes rotations. We propose that the Haymana basin was a fore-arc basin developed at the southern margin of Eurasia along the northwards subducted Neotethys Ocean. From the Palaeogene, the basin evolved into a foreland basin in front of a south-vergent fold and thrust belt developed during continental collision. The northward move- ment of KB caused the basin to rotate along vertical axes, whereas the thrust propagation promoted its exhumation.

Gülyüz, Erhan; Özkaptan, Murat; Lefebvre, Côme; Kaymakci, Nuretdin; Persano, Cristina; Stuart, Finlay M.

2014-05-01

217

Tharsis Basin Aquifer System  

NSDL National Science Digital Library

This is a QuickTime movie animating an enormous ancient drainage basin and aquifer system in the Tharsis region of Mars. The movie shows the geological stages of the aquifer system, as reported in a University of Arizona study.

University of Arizona

218

Aquifer - Basin and range  

NSDL National Science Digital Library

Aquifer basics outlining the makeup of the basin and range aquifers. Description and maps of unconsolidated sand and gravel aquifers. This site consists of information for the Southwestern portion of the United States, consisted of Arizona, California, Nevada, and Utah.

219

The tectonic evolution of Cenozoic extensional basins, northeast Brazil: Geochronological constraints from continental basalt 40Ar/39Ar ages  

NASA Astrophysics Data System (ADS)

The Boa Vista and Cubati Basins, Paraíba, Brazil, are NW-SE extension-related intracratonic basins that resulted from tectonic stresses after the opening of the South Atlantic. These basins contain lacustrine fossiliferous sediments, bentonite beds, and basalt flows that preserve Cenozoic continental records. 40Ar/39Ar ages for six whole-rocks from two distinct basaltic flows underlying the sediments in the Boa Vista basin are 27.3 ± 0.8 and 25.4 ± 1.3 Ma, while three grains from a basaltic flow overlying the sediments yield 22.0 ± 0.2 Ma. The sediments at the nearby Cubati Basin are overlain by a basalt flow with ages of ˜25.4 Ma. Three whole-rocks from an NE-SW-trending trachytic dyke cross cutting the sediments at the Boa Vista Basin yield 40Ar/39Ar ages of ˜12.45 ± 0.06, 12.59 ± 0.07, and 12.58 ± 0.07 Ma. Three whole-rocks from a nearby volcanic plug (Chupador) yield an age of 23.4 ± 0.1 Ma. The geochronological results combined with stratigraphic correlations between the two basins allow bracketing the age of the main sedimentary and bentonic units within the Boa Vista and Cubati Basins between 25.5 ± 1.3 and 24.9 ± 0.1 Ma. The ages, combined with field observations reveal that the formation of the Boa Vista and Cubati basins is associated with mantle-derived magmas channelled through reactivated Precambrian shear zones. Our geochronological results suggest that a temporal link with the Fernando de Noronha and Saint Helena hot spots can be excluded as possible sources of the Boa Vista and Cubati magmas. Rather, the extensional tectonics in the 30-20 Ma interval, long after Gondwana break-up, may be associated with the re-activation of continental-scale shear zones that channelled small batches of mantle-derived magmas.

de Souza, Zorano Sérgio; Vasconcelos, Paulo Marcos; Knesel, Kurt Michael; da Silveira Dias, Luiz Gustavo; Roesner, Eduardo Henrique; Cordeiro de Farias, Paulo Roberto; de Morais Neto, João Marinho

2013-12-01

220

K Basins Hazard Analysis  

SciTech Connect

This report describes the methodology used in conducting the K Basins Hazard Analysis, which provides the foundation for the K Basins Safety Analysis Report (HNF-SD-WM-SAR-062, Rev.4). This hazard analysis was performed in accordance with guidance provided by DOE-STD-3009-94, Preparation Guide for U. S. Department of Energy Nonreactor Nuclear Facility Safety Analysis Reports and implements the requirements of DOE Order 5480.23, Nuclear Safety Analysis Report.

WEBB, R.H.

1999-12-29

221

K Basin Hazard Analysis  

SciTech Connect

This report describes the methodology used in conducting the K Basins Hazard Analysis, which provides the foundation for the K Basins Final Safety Analysis Report. This hazard analysis was performed in accordance with guidance provided by DOE-STD-3009-94, Preparation Guide for U. S. Department of Energy Nonreactor Nuclear Facility Safety Analysis Reports and implements the requirements of DOE Order 5480.23, Nuclear Safety Analysis Report.

PECH, S.H.

2000-08-23

222

Exotic ingredients in the mélange at Port Macquarie, southern New England Orogen, reveal a spicy history of crustal kneading along eastern Gondwana  

NASA Astrophysics Data System (ADS)

An exotic assemblage of Paleozoic subduction complex rocks occurs within the serpentinite mélange at Port Macquarie in the southern New England Orogen, eastern Australia. New U-Pb zircon dating of key components within the mélange reveals surprising results that require a complete re-evaluation of the tectonic evolution of the New England Orogen. The Rocky Beach eclogite contains detrital igneous zircon populations of Carboniferous and Permo-Triassic age which contradict previous Ordovician K-Ar ages. The Tacking Point gabbro was thought to represent a Permian intrusive equivalent to the Clarence River suite but is Devonian (390×7 Ma). Volcaniclastic sandstones of the Watonga Formation yielded 452×10 Ma igneous zircons confirming previous Ordovician conodont ages. However, volaniclastic sandstones structurally below the serpentinite melange contain volcanic/detrital zircons as young as 335 Ma that were derived from a Carboniferous arc. Post-serpentinite mafic-felsic dykes were emplaced into the mélange at ~250 Ma. We suggest that the eastern margin of Gondwana underwent episodic, thin-skinned island-arc collisions paired with widespread deformation events (e.g. Macquarie Arc - Benambran Orogeny; Gamilaroi terrane - Kanimblan Orogeny; and Gympie terrane - Hunter Bowen Orogeny). These arc collisions are followed by subduction flips that lead to periods of continental margin 'Andean-type' magmatism and accretion marked by the voluminous intrusion of S- and I-type granites. Oroclinal bending has been proposed by some to explain the overall northward displacement of the Port Macquarie serpentinite relative to the Peel Fault to the west. We introduce a new hypothesis to explain apparent oroclines within the New England Orogen involving vertical rather than lateral displacements. We propose that the Hunter-Bowen compressional event is responsible for exhuming portions of the Gamilaroi + Djungati terranes from under their Carboniferous carapace. Thus, the northward (sinistral) displacement of the Port Macquarie and Hastings Blocks and the dextral displacement of the Coffs Harbour Block associated with the Texas orocline, is apparent only, and due more in part to vertical displacements of an extensive, thin-skinned oceanic terranes that underlie the Tablelands Complex, rather than extensive lateral movements. Thus, there is no need to invoke large-scale ';oroclinal' folding or significant sinistral faulting to explain the repetition of Hastings and Port Macquarie blocks in the southern New England.

Buckman, S.; Nutman, A.

2013-12-01

223

Gondwana to Asia: Plate tectonics, paleogeography and the biological connectivity of the Indian sub-continent from the Middle Jurassic through latest Eocene (166 35 Ma)  

NASA Astrophysics Data System (ADS)

Using the most up-to-the-date information available, we present a considerably revised plate tectonic and paleogeographic model for the Indian Ocean bordering continents, from Gondwana's Middle Jurassic break-up through to India's collision with Asia in the middle Cenozoic. The landmass framework is then used to explore the sometimes complex and occasionally counter-intuitive patterns that have been observed in the fossil and extant biological records of India, Madagascar, Africa and eastern Eurasia, as well those of the more distal continents. Although the paleogeographic model confirms the traditional view that India became progressively more isolated from the major landmasses during the Cretaceous and Paleocene, it is likely that at various times minor physiographic features (principally ocean islands) provided causeways and/or stepping-stone trails along which land animals could have migrated to/from the sub-continent. Aside from a likely link (albeit broken by several marine gaps) to Africa for much of this time (it is notable, that the present-day/recent biota of Madagascar indicates that the ancestors of five land-mammal orders, plus bats, crossed the > 400-km-wide Mozambique Channel at different times in the Cenozoic), it is possible that the Kerguelen Plateau connected India and Australia-Antarctica in the mid-Cretaceous (approximately 115-90 Ma). Later, the Seychelles-Mascarene Plateau and nearby elevated sea-floor areas could have allowed faunas to pass between southern India and Madagascar in the Late Cretaceous, from around 85-65 Ma, with an early Cenozoic extension to this path forming as a result of the Reunion hot-spot trace islands growing on the ocean floor to the SSW of India. The modelling also suggests that India's northward passage towards Asia, with eventual collision at 35 Ma, involved the NE corner of the sub-continent making a glancing contact with Sumatra, followed by Burma from ~ 57 Ma (late Paleocene) onwards, a scenario which is compatible with the fossil record indicating that India-Asia faunal exchanges began occurring at about this time. Finally, we contend that a number of biologically-based direct terrestrial migration routes that have been proposed for last 15 m.y. of the Cretaceous (Asia to India; Antarctica to Madagascar and/or India) can probably be dismissed because the marine barriers, likely varying from > 1000 up to 2500 km, were simply too wide.

Ali, Jason R.; Aitchison, Jonathan C.

2008-06-01

224

Petrology and mineral equilibrium modeling of incipient charnockite from the Trivandrum Granulite Block, southern India: implications for granulite formation in a Gondwana fragment  

NASA Astrophysics Data System (ADS)

The Southern Granulite Terrane (SGT) in India is known for its classic exposures of regionally metamorphosed granulite-facies rocks formed during the collisional orogeny related to the amalgamation of Gondwana supercontinent. The SGT is composed of a collage of Proterozoic crustal blocks dissected by large Late Neoproterozoic shear/suture zones. The Trivandrum Granulite Block (TGB) is comprises dominantly metasedimentary sequence with khondalites, leptynites and charnockites with subordinate quartzite, mafic granulite, calc-silicate rocks, and meta-ultramafic rocks. The TGB is known as one of the classic examples for the spectacular development of 'incipient charnockites' within orthopyroxene-free felsic gneisses as exposed in several quarry sections in the states of Kerala and Tamil Nadu. The charnockite-forming process in the TGB is considered to have been triggered by the infiltration of CO2-rich anhydrous fluids along structural pathways within upper amphibolite facies gneisses, resulting in the lowering of water activity and stabilization of orthopyroxene through the breakdown of biotite. However, no quantitative study on the stability of charnockitic mineral assemblage using mineral equilibrium modeling approach has been done so far. In this study, we report a new occurrence of incipient charnockite from Mavadi in the TGB and discuss the petrogenesis of granulite formation in an arrested stage on the basis of petrography, geothermobarometry, and mineral equilibrium modeling. In Mavadi, patches and lenses of charnockite (Kfs + Qtz + Pl + Bt + Grt + Opx + Ilm + Mag) of about 30 to 120 cm in length occur within Opx-free Grt-Bt gneiss (Kfs + Qtz + Pl + Bt + Grt + Ilm) host rocks. The application of mineral equilibrium modeling on charnockite assemblage in NCKFMASHTO system to constrain the conditions of charnockitization defines a P - T range of 800° C at 4.5 kbar to 850° C at 8.5 kbar, which is broadly consistent with the results from the conventional geothermobarometry (810-880° C at 7.7-8.0 kbar) on these rocks. The P - T conditions are lower than the inferred peak metamorphic conditions from the ultrahigh-temperature granulites of the study area (T >900° C), which might suggest heterogeneity in peak P - T conditions within this crustal block in relation to local buffering of metamorphic temperature by Opx-Bt-Kfs-Qtz assemblage. The result of T versus mole H2O (M(H2O)) modeling demonstrated that Opx-free assemblage in Grt-Bt gneiss is stable at M(H2O) = 0.3 to 1.5 mol.%, and orthopyroxene occurs as a stable mineral at M(H2O)

Endo, T.; Tsunogae, T.; Santosh, M.

2012-04-01

225

Aerogeophysical evidence for strike-slip faulting at the boundary between East and West Antarctica: implications for Jurassic magma emplacement and Gondwana breakup models  

NASA Astrophysics Data System (ADS)

Fragmentation of the Gondwana supercontinent began in the Jurassic and was the most significant reconfiguration of the continents of the southern hemisphere in the last 500 Ma. Jurassic continental rifting began adjacent to South Africa in the Weddell Sea region of Antarctica. This region is therefore critical for understanding the process that initiated supercontinent breakup, including the role of mantle plumes, magmatism, and major plate and microplate re-configurations. However, due to the remote location and blanketing ice sheets, the magmatic and tectonic evolution of the Weddell Sea sector of Antarctica has remained poorly understood and controversial. Our recent aeromagnetic and airborne gravity investigations reveal the inland extent of the Weddell Sea Rift system beneath the West Antarctic Ice Sheet, and indicate the presence of a major left-lateral strike slip fault system, separating the Ellsworth Whitmore block from East Antarctica (Jordan et al., 2013 Tectonophysics). In this study we use 3D inversion of magnetic data to investigate the geometry and emplacement mechanism of Jurassic granites both along the boundary and within the Ellsworth-Whitmore block. Our models demonstrate a high degree of structural control on Jurassic granite emplacement along the newly identified left-lateral Pagano Shear Zone that flanks the Ellsworth-Whitmore block. Other granitoids emplaced further west within the Ellsworth-Whtimore block itself do not appear to have the same structural control, suggesting that this possible microplate or block was relatively more rigid. Extensive and likely more rigid Precambrian basement of Grenvillian-age is clearly delineated from aeromagnetic signatures at the northern edge of the Ellsworth-Whitmore block, lending support to this interpretation. Most intriguing, it that the high amplitude anomalies over the northern margin of the Ellsworth-Whitmore block are remarkably similar to those previously mapped over the Shackleton Range in East Antarctica. In the Shackleton Range, the association between Grenvillian-age basement and aeromagnetic anomalies is less well-constrained but nevertheless possible. Here we test in Gplates our new geodynamic model that involves the Ellsworth Whitmore block being originally closer to the Shackleton Range region in East Antarctica and then translated to West Antarctica in Jurassic times via ca 300 km of crustal extension in the Weddell Sea rift. We compare and contrast our new model with the currently more widely accepted geodynamic model that predicts significantly more complex movements of the Ellsworth-Whitmore microplate, including 180 degree rotation, and ~1500 km of strike-slip displacement from the Natal Embayment adjacent to South Africa to its current position in West Antarctica.

Jordan, Tom; Ferraccioli, Fausto

2014-05-01

226

SURVEY OF CROSS-BASIN BOAT TRAFFIC, ATCHAFALAYA BASIN, LOUISIANA  

EPA Science Inventory

For flood control and for the preservation and enhancement of environmental quality of overflow swamp habitats, introduction of sediment from the Atchafalaya Basin Main Channel into backwater areas of the Atchafalaya Basin Floodway should be minimized. This introduction occurs ma...

227

RETENTION BASIN Definition  

E-print Network

A retention basin is a stormwater facility which includes a permanent impoundment, or pool of water, and, therefore, is normally wet, even during non-rainfall periods. Inflows from stormwater runoff may be temporarily stored above this permanent pool. Purpose A retention basin provides for long-term water quality enhancement of stormwater runoff. Stormwater inflows may also be temporarily stored above the permanent pool for downstream flood control and channel erosion control. A retention basin is considered one of the most reliable and versatile BMPs available. Water Quality Enhancement High removal rates of particulate and soluble pollutants (nutrients) can be achieved in retention basins through gravitational settling, biological uptake and decomposition. When an even higher degree of pollutant removal efficiency is required, the basin can be enhanced by using various modifications relating to the size and design of the permanent pool. Monitoring studies have shown sediment removal efficiencies to range from 50-90%, total phosphorus removal efficiencies to range from 30-90 % and soluble nutrient removal efficiencies to

Figure Figures Page

228

Age and position of the sedimentary basin of the Ocoee Supergroup western Blue Ridge tectonic province, southern Appalachians  

SciTech Connect

The stratigraphic continuity of the Ocoee Supergroup established recently allows one to extrapolate the Paleozoic age of the Walden Creek Group determined on paleontological evidence to the entire Ocoee succession. The Walden Creek Group rocks contain a fossil assemblage of fenestrate bryozoan, algal, trilobite, ostracod, brachiopod and echinozoan fragments and agglutinated foraminifer tests that indicate Silurian or younger Paleozoic age. The fossils occur in carbonate clasts in polymict conglomerates, and debris-flow breccia beds, and in olistoliths of bedded carbonate and shale, and calcarenite turbidite beds. These carbonate lithologies form a minor, but characteristic constituent of the Walden Creek Group. Fossil have been found also in shale and mudstone siliciclastic lithologies of the Walden Creek Group. The fossils are fragmented and poorly preserved because of several cycles of cementation and solution in the carbonate rocks and a pervasive cleavage in the fine-grained siliciclastic rocks. Recently reported Mississippian plant fossils from the Talladega belt indicate widespread occurrence of Middle Paleozoic basins in the Western Blue Ridge. These pull-apart basins formed in the stress field generated by northward movement of Laurentia past the western margin of Gondwana after the Taconian-Famatinian collision in the Ordovician.

Unrug, R.; Unrug, S. (Wright State Univ., Dayton, OH (United States). Dept. of Geological Sciences); Ausich, W.I. (Ohio State Univ., Columbus, OH (United States). Dept. of Geological Sciences); Cuffey, R.J. (Pennsylvania State Univ., University Park, PA (United States). Dept. of Geosciences); Mamet, B.L. (Univ. de Montreal, Quebec (Canada). Dept. de Geologie); Palmes, S.L. (Florida State Univ., Tallahassee, FL (United States). Dept. of Geology)

1994-03-01

229

Sedimentary cycles related to the late Palaeozoic cold-warm climate change, Talchir Formation, Talchir Basin, India  

NASA Astrophysics Data System (ADS)

Attributes of sedimentary facies within Permo-Carboniferous Talchir Formation (Gondwana Supergroup), Talchir Basin, India, attest to sedimentation under glaciomarine setting. Facies architecture reveals three sedimentary cycles of distinct orders. Cycle-1 sediments are 10s of m thick and are represented by repeated occurrences of glacigenic/reworked-glacigenic sediments followed by storm-reworked glacial outwash deposits. Juxtaposition of multiple Cycle-1 sequences indicate repeated ice-front advance-retreats related to climatic fluctuations, which led to accumulation of glacier-laden coarse-grained sediments, and subsequent flooding by marine storm surges. Cm-thin sandstone-mudstone interbeds of Cycle-2 belong within the Cycle-1 sequences and represent deposition from episodic storm surges. Mm-thin Cycle-3 sediments occur within the Cycle-2 sequences and attribute their genesis to semi-diurnal tidal fluctuations. Open marine storm surges have reworked these tidal sediments. In absence of major tectonic influences, the studied sedimentary cycles and associated palaeogeographic changes in the ice-marginal Talchir marine basin bear direct relation to late Palaeozoic cold-warm climatic transitions.

Bhattacharya, Biplab

2013-06-01

230

Sedimentology of the Neoproterozoic (c. 580 Ma) Squantum 'Tillite', Boston Basin, USA: Mass flow deposition in a deep-water arc basin lacking direct glacial influence  

NASA Astrophysics Data System (ADS)

The Squantum 'Tillite' (c. 593-570 Ma) consists of thick (up to 215 m) massive and crudely-stratified diamictites conformably interbedded with subaqueously-deposited conglomerates and sandstones within a thick (~ 7 km) Boston Basin fill which is dominated by argillite turbidites. The Squantum Tillite was first interpreted as being glacigenic in origin in 1914 because of the presence of diamictites; argillites were interpreted as glaciolacustrine 'varves' with rare ice-rafted debris, and conglomerates as glaciofluvial outwash. More recently these have been shown to be the product of deep marine mass flow processes with no glacial influence, yet because of its age equivalence with the deep marine, glacially-influenced Gaskiers Formation, the Squantum Tillite is still seen by some as supporting evidence for a widespread 'Snowball Earth' event at c. 580 Ma. New sedimentological work confirms that conglomerate and sandstone facies are deep marine sediment gravity flows genetically related to massive (homogeneous) and crudely-stratified (heterogeneous) diamictites produced subaqueously by downslope mixing of gravel and cobbles with muddy facies. Rare horizons of 'ice rafted debris' in thin-bedded and laminated turbidite facies interbedded with thick debrites show a weak but positive correlation of lamina thickness with grain size, suggesting these facies are non-glacial co-genetic 'debrite-turbidite' couplets. A significant volcanic influence on sedimentation is identified from reworked lapilli tuff beds and reworked ash in turbidites. The depositional setting of the Squantum 'Tillite' appears to be that of a submarine slope/fan setting in an open marine volcanic arc basin receiving large volumes of poorly-sorted sediment on the mid-latitude active margin of Gondwana. No direct glacial influence is apparent.

Carto, Shannon L.; Eyles, Nick

2012-08-01

231

NILE BASIN INITIATIVE Claire Stodola  

E-print Network

.1 (2004): 47-63. EBSCOhost. Web. 3 Oct. 2010. Nile Basin Initiative. Nile Basin Initiative. Web. 24 Sept Initiative (NBI)." Alternatives: Turkish Journal of International Relations 7.4 (2008): 34-43. EBSCOhost. Web

New Hampshire, University of

232

Great Basin National Park  

NSDL National Science Digital Library

This National Park Service site describes the biology of Great Basin's plants and animals; geology and ecology of the Lehman Caves; air quality of the park; and past human activities in the Great Basin such as farming, ranching, and gold mining. There is a list of historical, geological, and archeological dates important to the park and an instructor guide containing activities such as creating a nature notebook and adopting a tree. There is also information on: planning a visit to the park and the Lehman Caves, park projects such as weeding out non-native plants and the reintroduction of Bonneville Cutthroat Trout, and a self-guided geology field trip.

233

Denver Basin Project  

NSDL National Science Digital Library

At this website, the Denver Museum of Nature and Science provides updates on the progress of the Museum and the USGS's research efforts to understand the geology of the Denver Basin. Researchers can find clear explanations of the current research projects including examining the paleosol, stratigraphy, and temperatures in the drill hole. Students can find explanations on radiometric dating, paleomagnetic dating, GIS, and other methods used to study the basin's geologic history. The website offers images of the workers drilling the well and descriptions of the rock layers.

234

Viscoelastic Relaxation of Lunar Basins  

Microsoft Academic Search

The large lunar impact basins provide a unique glimpse into early lunar history. Here we investigate the possibility that the relief of the oldest lunar basins (with the exception of South-Pole Aitken) has decayed through viscous relaxation. We identify nine ancient multi-ring basins with very low relief and low-amplitude Bouguer and free-air gravity anomalies. The characteristics of these basins are

P. S. Mohit; R. J. Phillips

2004-01-01

235

Late Mississippian (Chesterian) carbonate to carbonate-clastic cycles in the eastern Illinois Basin  

SciTech Connect

Late Mississippian (Chesterian) rocks of the eastern Illinois Basin in Kentucky and Indiana show depositional cycles (3--20 meters thick) composed of a range of facies deposited during the transition from carbonate-dominated deposition of the Middle Mississippian to the predominantly siliciclastic regime of the Pennsylvanian. Within the basal Ste. Genevieve Formation (30--70 meters thick) there are five predominantly carbonate cycles. Cycle bases vary from thin calcareous sandstone near the northern clastic source to ooid-quartz dolomitic pelletal grainstone and mudstone further south. Massive cross-bedded and channeled ooid-skeletal grainstones represent the cycle tops and are commonly capped by caliche and subaerial breccia, particularly where there was no subsequent siliciclastic deposition. The cycles are interpreted to be driven by fourth-order (400 k.y.) glacio-eustatic sea-level fluctuations based on coincidence of the calculated cycle period with the long-term eccentricity signal, the Late Mississippian onset of Gondwana glaciation and cycle correlation over more than 100 kilometers. The breccia and caliche formed during lowstands, the siliciclastics, eolianites and dolomitic pelletal grainstones are transgressive facies and the ooid-skeletal grainstones represent sea-level highstands.

Smith, L.B.; Read, J.F. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

1994-03-01

236

3, 14811514, 2006 Cilician Basin  

E-print Network

OSD 3, 1481­1514, 2006 Cilician Basin forecasting E. ¨Ozsoy and A. S¨ozer Title Page Abstract Forecasting circulation in the Cilician Basin of the Levantine Sea E. ¨Ozsoy and A. S¨ozer Institute Marine;OSD 3, 1481­1514, 2006 Cilician Basin forecasting E. ¨Ozsoy and A. S¨ozer Title Page Abstract

Paris-Sud XI, Université de

237

Geochemical and isotopic composition of Pan-African metabasalts from southwestern Gondwana: Evidence of Cretaceous South Atlantic opening along a Neoproterozoic back-arc  

NASA Astrophysics Data System (ADS)

A lithogeochemical and Sr-Nd-Pb isotope study of former oceanic crustal rocks from the Cuchilla Dionisio Terrane in the southern Dom Feliciano Belt, Uruguay (La Tuna amphibolites) and metabasites in the Chameis Subterrane of the Marmora Terrane in the Gariep Belt, Namibia/South Africa shows that these rocks are compositionally very similar and probably represent the same unit on opposite sides of the modern South Atlantic. The mafic rocks from both terranes are tholeiitic metabasalts and -andesites and have depleted rare earth element patterns, generally low TiO2 (< 1.5 wt.%), very low Th/Nb ratios and lack negative Nb-Ta anomalies, all features that are typical of ‘normal' mid-ocean ridge basalts (N-MORB) and/or back-arc basin basalts (BABB). In addition, both rock suites have extremely depleted Nd isotope compositions (?Nd630 Ma = 6.7-9.4), superchondritic 147Sm/144Nd ratios, and low 206Pb/204Pb and 207Pb/204Pb initial ratios. The 87Sr/86Sr initial ratios of the La Tuna mafic rocks are low, whereas the Chameis metagabbro samples have higher, possibly alteration-related ratios. The geochemical and isotopic signatures are consistent with the formation of both rock suites in the same mature Neoproterozoic back-arc basin (Marmora Basin), supporting conclusions drawn from earlier provenance studies of metasedimentary units from these terranes. Other mafic rocks from the Marmora Terrane are interpreted as ocean island basalts that formed in a within-plate setting. A corollary of the conclusion that the mafic rocks in the Cuchilla Dionisio and Marmora Terranes formed in the same back-arc basin is (1) that the main Pan-African suture between the Río de la Plata Craton and the Kalahari Craton lies to the west of the Dom Feliciano Belt in South America, and (2) that the opening of the modern South Atlantic did not occur along that suture but along the axis of the Neoproterozoic Marmora back-arc basin.

Will, Thomas M.; Frimmel, Hartwig E.; Gaucher, Claudio; Bossi, Jorge

2014-08-01

238

A review of stratigraphy and sedimentary environments of the Karoo Basin of South Africa  

NASA Astrophysics Data System (ADS)

The Karoo Supergroup covers almost two thirds of the present land surface of southern Africa. Its strata record an almost continuous sequence of continental sedimentation that began in the Permo-Carboniferous (280 Ma) and terminated in the early Jurassic 100 million years later. The glacio-marine to terrestrial sequence accumulated in a variety of tectonically controlled depositories under progressively more arid climatic conditions. Numerous vertebrate fossils are preserved in these rocks, including fish, amphibians, primitive aquatic reptiles, primitive land reptiles, more advanced mammal-like reptiles, dinosaurs and even the earliest mammals. Palaeoenvironmental analysis of the major stratigraphic units of the Karoo sequence demonstrates the effects of more localised tectonic basins in influencing depositional style. These are superimposed on a basinwide trend of progressive aridification attributed to the gradual northward migration of southwestern Gondwanaland out of polar climes and accentuated by the meteoric drying effect of the surrounding land masses. Combined with progressive climatic drying was a gradual shrinking of the basin brought about by the northward migration of the subducting palaeo-Pacific margin to the south. Following deposition of the Cape Supergroup in the pre-Karoo basin there was a period of uplift and erosion. At the same time the southern part of Gondwana migrated over the South Pole resulting in a major ice-sheet over the early Karoo basin and surrounding highlands. Glacial sedimentation in both upland valley and shelf depositories resulted in the basal Karoo Dwyka Formation. After glaciation, an extensive shallow sea remained over the gently subsiding shelf fed by large volumes of meltwater. Black clays and muds accumulated under relatively cool climatic conditions (Lower Ecca) with perhaps a warmer "interglacial" during which the distinctive Mesosaurus-bearing, carbonaceous shales of the Whitehill Formation were deposited. Deformation of the southern rim of the basin, caused by the subducting palaeo-Pacific plate, resulted in mountain ranges far to the south. Material derived from this source, as well as granitic uplands to the west and morth-east, was deposited on large deltas that built out into the Ecca sea (Upper Ecca). The relatively cool climate and lowland setting promoted thick accumulations of peat on the coastal and delta plains and which now constitute the major coal reserves of southern Africa. Later the prograding deltas coalesced to fill most of the basin after which fluvial sedimentation of the Beaufort Group dominated. The climate by this time (Late Permian) had warmed to become semi-arid with highly seasonal rainfall. The central parts of the basin were for the most part drained by fine-grained meanderbelts and semi-permanent lakes. Significant stratabound uranium reserves have been delimited in the channel sandstones of the Beaufort Group in the southwestern parts of the basin. Pulses of uplift in the southern source areas combined with a possible orogenic effect resulted in two coarser-grained alluvial fans prograding into the more central parts of the basin (Katberg Sandstone Member and Molteno Formation). In the upper Karoo sequence progressive aridification dominated depositional style with playa lake and wadi-type environments (Elliot Formation) that finally gave way to a dune sand dominated system (Clarens Formation). Basinwide volcanic activity of the early Jurassic Drakensberg Group brought deposition in the Karoo Basin to a close.

Smith, R. M. H.

239

Zircon U-Pb geochronology of granitic rocks of the Cordón de Lila and Sierra de Almeida ranges, northern Chile: 30 m.y. of Ordovician plutonism on the western border of Gondwana  

NASA Astrophysics Data System (ADS)

In this paper we determined the chronology of Lower Paleozoic arc-related granitic rocks in the Cordón de Lila and Sierra de Almeida ranges, northern Chile, based on new U-Pb ages obtained by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) on single zircons. Plutonism lasted ?30 m.y., spanning from 490 to 460 Ma (Lower to Mid Ordovician). The obtained ages correspond to the plutonic units' crystallization ages and fit well with the observed contact relationships with their country rocks and mutual intrusion relationships, and also with biostratigraphical data from the sedimentary country rocks. Our geochronological results on the granitic rocks of Cordón de Lila and Sierra de Almeida ranges broadly agree with the known ages of the plutonic rocks in the Argentinian Puna, strengthening the idea that they formed part of the same magmatic arc in the western border of west Gondwana during the Early to Middle Ordovician.

Niemeyer, Hans; Meffre, Sebastien; Guerrero, Ricardo

2014-12-01

240

SOME ETHNOMEDICINAL PLANTS OF KORAPUT DISTRICT ORISSA  

PubMed Central

The paper presents the ethnomedicinal use of 35 plants by the tribals of Koraput district to cure 25 diseases they suffer from. Apart from this, a note on the vegetation pattern, tribal population and geography of the district is given here. PMID:22557632

Das, P.K.; Misra, M.K.

1988-01-01

241

Crustal geoelectric structure of the Sikkim Himalaya and adjoining Gangetic foreland basin  

NASA Astrophysics Data System (ADS)

We present the results of a broadband magnetotelluric survey along a 200-km-long profile across the Sikkim Himalaya. The data were acquired at average station spacing of 5-6 km and transfer functions of 31 sites in 0.01-1000 s period range have been used for 2-D joint inversion of TE and TM modes. The composite model incorporating the effect of transverse strike reveals several features that correlate with the available seismic and kinematic models of the region. A major result of the present study is that the Main Himalayan Thrust forms the base of several resistive blocks within the wedge and that a ramp structure is present south of the Main Central Thrust Zone (MCTZ). Another significant result is that the crust and mantle lithosphere beneath the MCTZ and the Higher Himalayan Crystallines (HHC) seem to be compositionally/geologically different from the lithosphere south of the MCTZ. A steep crustal-scale fault with the Moho offset of 14 km is inferred to be separating these two blocks. The deep crustal seismicity could be related to this fault whereas shallow seismicity can be linked to the deformation within the wedge. The results also reveal the presence of some more conductors. We relate the conductor within the HHC to the sedimentary rocks of the Tethyan sequence exposed in a window about 40 km west of the profile and north of the South Tibetan Detachment System (STDS). The conductor at 90 km profile location is linked to the Gondwana rocks exposed in the Rangit Window. A 4-6 km thick sedimentary layer overlies the basement in the Gangetic foreland basin. We also delineate a sub-crustal conductor at 50-60 km depth beneath the foreland basin at the southern end of the profile, the cause of which is not apparent and needs to be explored.

Pavan Kumar, G.; Manglik, A.; Thiagarajan, S.

2014-12-01

242

Albuquerque Basin seismic network  

USGS Publications Warehouse

The U.S. Geological Survey has recently completed the installation of a seismic network around the Albuquerque Basin in New Mexico. The network consists of two seismometer arrays, a thirteen-station array monitoring an area of approximately 28,000 km 2 and an eight-element array monitoring the area immediately adjacent to the Albuquerque Seismological Laboratory. This report describes the instrumentation deployed in the network.

Jaksha, Lawrence H.; Locke, Jerry; Thompson, J.B.; Garcia, Alvin

1977-01-01

243

Caribbean basin framework, 3: Southern Central America and Colombian basin  

SciTech Connect

The authors recognize three basin-forming periods in southern Central America (Panama, Costa Rica, southern Nicaragua) that they attempt to correlate with events in the Colombian basin (Bowland, 1984): (1) Early-Late Cretaceous island arc formation and growth of the Central American island arc and Late Cretaceous formation of the Colombian basin oceanic plateau. During latest Cretaceous time, pelagic carbonate sediments blanketed the Central American island arc in Panama and Costa Rica and elevated blocks on the Colombian basin oceanic plateau; (2) middle Eocene-middle Miocene island arc uplift and erosion. During this interval, influx of distal terrigenous turbidites in most areas of Panama, Costa Rica, and the Colombian basin marks the uplift and erosion of the Central American island arc. In the Colombian basin, turbidites fill in basement relief and accumulate to thicknesses up to 2 km in the deepest part of the basin. In Costa Rica, sedimentation was concentrated in fore-arc (Terraba) and back-arc (El Limon) basins; (3) late Miocene-Recent accelerated uplift and erosion of segments of the Central American arc. Influx of proximal terrigenous turbidites and alluvial fans in most areas of Panama, Costa Rica, and the Colombian basin marks collision of the Panama arc with the South American continent (late Miocene early Pliocene) and collision of the Cocos Ridge with the Costa Rican arc (late Pleistocene). The Cocos Ridge collision inverted the Terraba and El Limon basins. The Panama arc collision produced northeast-striking left-lateral strike-slip faults and fault-related basins throughout Panama as Panama moved northwest over the Colombian basin.

Kolarsky, R.A.; Mann, P. (Univ. of Texas, Austin (United States))

1991-03-01

244

Drainage Basin Morphometry  

NSDL National Science Digital Library

The goal of this activity is for to students to observe and quantify the inherent organization within the channel network of a single drainage basin (a la Horton, 1945). The students will use the contour-crenulation method to flesh out the channel network within a selected drainage basin. They will then use the Strahler system to deterime the stream order of each channel segment. They then measure and average various attributes (slope, length, etc.) of the channel segments, by stream order. These data will then be plotted on semi-log graph paper to illustrate the matematical relationships between channel attributes and stream order. This activity gives students practice in delineating drainage divides and channel networks on topographic maps, using map scales to measure distances on topographic maps, and graphing data using a semi-log format. In addition, they are asked to compare their "real-world" results against the classic "laws" of basin morphometry presented in their textbook. This permits a discussion of sample size and measurement error versus theoretical relationships presented in a textbook. Designed for a geomorphology course

Rick Ford

245

Rift architecture and evolution: The Sirt Basin, Libya: The influence of basement fabrics and oblique tectonics  

NASA Astrophysics Data System (ADS)

The Cretaceous-Tertiary northwest-trending Sirt Basin system, Libya, is a rift/sag basin formed on Pan-African to Paleozoic-aged basement of North Africa. In this study, we investigate the rift-basin architecture and tectonic framework of the western Sirt Basin. Using remote sensed data, supported by borehole data from about 300 deep wells and surface geologic maps, we constructed geological cross sections and surface geology maps. Indication of the relative timing of structures and movement along faults has been determined where possible. Direction statistics for all the interpreted linear features acquired in the study area were calculated and given as a total distribution and then the totals are broken down by the major basin elements of the area. Hundreds of lineaments were recognized. Their lengths, range between a hundred meters up to hundreds of kilometers and the longest of the dominant trends are between N35W-N55W and between N55E-N65E which coincides with Sirt Basin structures. The produced rose diagrams reveal that the majority of the surface linear features in the region have four preferred orientations: N40-50W in the Zallah Trough, N45-55W in the Dur al Abd Trough, N35-55W in the Az Zahrah-Al Hufrah Platform, and in contrast in the Waddan Uplift a N55-65E trend. We recognize six lithostratigraphic sequences (phases) in the area's stratigraphic framework. A Pre-graben (Pre-rift) initiation stage involved the Pre-Cretaceous sediments formed before the main Sirt Basin subsidence. Then followed a Cretaceous to Eocene graben-fill stage that can divided into four structurally-active and structurally-inactive periods, and finally a terminal continental siliciclastics-rich package representing the post-rift stage of the development in post-Eocene time. In general five major fault systems dissect and divide the study area into geomorphological elevated blocks and depressions. Most of the oil fields present in the study area are associated with structural hinge zones and adjoining highs. Late Eocene rocks exposed in the western part of the basin exhibit a complex network of branching segmented normal and strike-slip faults, generally with a NNW-SSE structural orientations. Many surface structural features have been interpreted from satellite images which confirm sinistral strike-slip kinematics. Relay ramp structures, numerous elongate asymmetric synclines associated with shallow west limbs and steeper dipping east limbs are developed in the hangingwalls adjacent to west downthrowing normal faults. These structural patterns reflect Cretaceous/Tertiary extensional tectonics with additional control by underlying pre-existing Pan-African basement fabrics and ENE-WSW trending Hercynian structures. We relate the Sirt Basin rift development as exemplified in our study area to the break-up of Gondwana represented by the structural evolution of the West-Central African rift system, and the South and Central Atlantic, the Tethys and the Indian Oceans.

Abdunaser, K. M.; McCaffrey, K. J. W.

2014-12-01

246

Rock physics template (RPT) analysis of well logs and seismic data for lithology and fluid classification in Cambay Basin  

NASA Astrophysics Data System (ADS)

The Cambay Basin is 450-km-long north-south-trending graben with an average width of 50 km, having maximum depth of about 7 km. The origin of the Cambay and other Basins on the western margin of India are related to the break up of the Gondwana super-continent in the Late-Triassic to Early-Jurassic (215 ma). The structural disposition of the Pre-Cambrian basement—a complex of igneous and metamorphic rocks exposed in the vicinity of the Cambay Basin—controls its architecture. The principal lineaments in the Basin are aligned towards NE-SE, ENE-WSW and NNW-SSE, respectively. Rock physics templates (RPTs) are charts and graphs generated by using rock physics models, constrained by local geology, that serve as tools for lithology and fluid differentiation. RPT can act as a powerful tool in validating hydrocarbon anomalies in undrilled areas and assist in seismic interpretation and prospect evaluation. However, the success of RPT analysis depends on the availability of the local geological information and the use of the proper model. RPT analysis has been performed on well logs and seismic data of a particular study area in mid Cambay Basin. Rock physics diagnostic approach is adopted in the study area placed at mid Cambay Basin to estimate the volume in the reservoir sands from 6 wells (namely; A, B, C, D, E and F) where oil was already encountered in one well, D. In the study area, hydrocarbon prospective zone has been marked through compressional (P wave) and shear wave (S wave) impedance only. In the RPT analysis, we have plotted different kinds of graphical responses of Lame's parameters, which are the function of P-wave velocity, S-wave velocity and density. The discrete thin sand reservoirs have been delineated through the RPT analysis. The reservoir pay sand thickness map of the study area has also been derived from RPT analysis and fluid characterization. Through this fluid characterization, oil-bearing thin sand layers have been found in well E including well D. The sand distribution results prove that this methodology has able to perform reservoir characterization and seismic data interpretation more quantitatively and efficiently.

Datta Gupta, Saurabh; Chatterjee, Rima; Farooqui, M. Y.

2012-07-01

247

Multiple Oscillatory Modes of the Argentine Basin. Part II: The Spectral Origin of Basin Modes  

E-print Network

Multiple Oscillatory Modes of the Argentine Basin. Part II: The Spectral Origin of Basin Modes In this paper the spectrum of barotropic basin modes of the Argentine Basin is shown to be connected to the classical Rossby basin modes of a flat-bottom (constant depth), rectangular basin. First, the spectrum

Gille, Sarah T.

248

Master1RservoirsGologiquesDynamiquedesBassins-MichelSranne Cratonic Basins: Michigan Basin -> old rift ???  

E-print Network

Master1RéservoirsGéologiquesDynamiquedesBassins-MichelSéranne 17 Cratonic Basins: Michigan Basin-cratonic Basins Master1RéservoirsGéologiquesDynamiquedesBassins-MichelSéranne 18 Taoudenni Basin : the largest sedimentary basin in the World From Moussine & al. 3- Intra-cratonic Basins #12;Master1Réservoirs

Demouchy, Sylvie

249

Basin plains; Giant sedimentation events  

Microsoft Academic Search

The study of 13 modern basin plains ranging in size from the 200-km2 Navidad Basin up to the giant (> 100,000-km2) Hatteras and Sohm Abyssal Plains has reveaied that these features owe their existence to large-volume turbidity currents capable of covering the entire basin floor. Such convulsive events flatten out the topographic irregularities formed by the deposition of small flows

Orrin H. Pilkey

250

A conditional random field-based downscaling method for assessment of climate change impact on multisite daily precipitation in the Mahanadi basin  

NASA Astrophysics Data System (ADS)

Downscaling to station-scale hydrologic variables from large-scale atmospheric variables simulated by general circulation models (GCMs) is usually necessary to assess the hydrologic impact of climate change. This work presents CRF-downscaling, a new probabilistic downscaling method that represents the daily precipitation sequence as a conditional random field (CRF). The conditional distribution of the precipitation sequence at a site, given the daily atmospheric (large-scale) variable sequence, is modeled as a linear chain CRF. CRFs do not make assumptions on independence of observations, which gives them flexibility in using high-dimensional feature vectors. Maximum likelihood parameter estimation for the model is performed using limited memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) optimization. Maximum a posteriori estimation is used to determine the most likely precipitation sequence for a given set of atmospheric input variables using the Viterbi algorithm. Direct classification of dry/wet days as well as precipitation amount is achieved within a single modeling framework. The model is used to project the future cumulative distribution function of precipitation. Uncertainty in precipitation prediction is addressed through a modified Viterbi algorithm that predicts the n most likely sequences. The model is applied for downscaling monsoon (June-September) daily precipitation at eight sites in the Mahanadi basin in Orissa, India, using the MIROC3.2 medium-resolution GCM. The predicted distributions at all sites show an increase in the number of wet days, and also an increase in wet day precipitation amounts. A comparison of current and future predicted probability density functions for daily precipitation shows a change in shape of the density function with decreasing probability of lower precipitation and increasing probability of higher precipitation.

Raje, Deepashree; Mujumdar, P. P.

2009-10-01

251

Fast Facts About the Columbia River Basin  

E-print Network

Fast Facts About the Columbia River Basin Pocket Guide 2013 Edition #12;PAGe 2 > POCKET GUIDE Basin , and fish and wildlife affected by, the columbia River Basin hydropower dams. the council is a unique

252

Columbia River Basin Monitoring, Evaluation,  

E-print Network

Columbia River Basin Monitoring, Evaluation, Research, and Reporting (MERR) Plan Council document 2010-4 #12;9 March 2010 Draft 2 Executive Summary This Monitoring, Evaluation, Research and Reporting Plan (MERR Plan) ensures the Council's Columbia River Basin Fish and Wildlife Program (Program) goals

253

MASSACHUSETTS DRAINAGE SUB-BASINS  

EPA Science Inventory

MassGIS has produced a statewide digital datalayer of the approximately 2300 sub-basins as defined and used by the USGS Water Resources Division and the Mass Water Resources Commission and as modified by Executive Office of Environmental Affairs (EOEA) agencies. These sub-basins...

254

River basin management in Namibia  

NASA Astrophysics Data System (ADS)

The present trend in water resources management is to work on a basin level, the reasons being the need to devolve information sharing, co-ordinating and decision-making level down from a centralised system and the fact that water resources are shared within a basin. In Namibia, the water sector is being reformed, also, to introduce the concept of integrated water resources management on basin level. An important aspect is the establishment of Basin Management Committees to manage water along hydrological boundaries and to involve the local communities more actively in the planning, operation and management of their water supplies and resources. As such it compliments community based management program government is implementing. To this end, basins have been demarcated using several set criteria and piloting of the stressed basin, regarding availability of water and environmental degradation, started. This paper will look at the introduction of basin management concept in Namibia and how the communities in piloted basin are embracing it. So far the communities have shown willingness to manage their own water resources as compared to the past when everything was dictated to them from centrally located decision-makers. The question however is what are the challenges this task will present to them in managing this scarce and vulnerable resource, with regard to the capacity available.

Amakali, Maria; Shixwameni, Loise

255

Estancia Basin dynamic water budget.  

SciTech Connect

The Estancia Basin lies about 30 miles to the east of Albuquerque, NM. It is a closed basin in terms of surface water and is somewhat isolated in terms of groundwater. Historically, the primary natural outlet for both surface water and groundwater has been evaporation from the salt lakes in the southeastern portion of the basin. There are no significant watercourses that flow into this basin and groundwater recharge is minimal. During the 20th Century, agriculture grew to become the major user of groundwater in the basin. Significant declines in groundwater levels have accompanied this agricultural use. Domestic and municipal use of the basin groundwater is increasing as Albuquerque population continues to spill eastward into the basin, but this use is projected to be less than 1% of agricultural use well into the 21st Century. This Water Budget model keeps track of the water balance within the basin. The model considers the amount of water entering the basin and leaving the basin. Since there is no significant surface water component within this basin, the balance of water in the groundwater aquifer constitutes the primary component of this balance. Inflow is based on assumptions for recharge made by earlier researchers. Outflow from the basin is the summation of the depletion from all basin water uses. The model user can control future water use within the basin via slider bars that set values for population growth, water system per-capita use, agricultural acreage, and the types of agricultural diversion. The user can also adjust recharge and natural discharge within the limits of uncertainty for those parameters. The model runs for 100 years beginning in 1940 and ending in 2040. During the first 55 years model results can be compared to historical data and estimates of groundwater use. The last 45 years are predictive. The model was calibrated to match to New Mexico Office of State Engineer (NMOSE) estimates of aquifer storage during the historical period by making adjustments to recharge and outflow that were within the parameters uncertainties. Although results of this calibrated model imply that there may be more water remaining in the aquifer than the Estancia Water Plan estimates, this answer is only another possible result in a range of answers that are based on large parameter uncertainties.

Thomas, Richard P.

2004-09-01

256

Advanced Chemistry Basins Model  

SciTech Connect

The objective of this project is to: (1) Develop a database of additional and better maturity indicators for paleo-heat flow calibration; (2) Develop maturation models capable of predicting the chemical composition of hydrocarbons produced by a specific kerogen as a function of maturity, heating rate, etc.; assemble a compositional kinetic database of representative kerogens; (3) Develop a 4 phase equation of state-flash model that can define the physical properties (viscosity, density, etc.) of the products of kerogen maturation, and phase transitions that occur along secondary migration pathways; (4) Build a conventional basin model and incorporate new maturity indicators and data bases in a user-friendly way; (5) Develop an algorithm which combines the volume change and viscosities of the compositional maturation model to predict the chemistry of the hydrocarbons that will be expelled from the kerogen to the secondary migration pathways; (6) Develop an algorithm that predicts the flow of hydrocarbons along secondary migration pathways, accounts for mixing of miscible hydrocarbon components along the pathway, and calculates the phase fractionation that will occur as the hydrocarbons move upward down the geothermal and fluid pressure gradients in the basin; and (7) Integrate the above components into a functional model implemented on a PC or low cost workstation.

Blanco, Mario; Cathles, Lawrence; Manhardt, Paul; Meulbroek, Peter; Tang, Yongchun

2003-02-13

257

RESERVES IN WESTERN BASINS PART IV: WIND RIVER BASIN  

SciTech Connect

Vast quantities of natural gas are entrapped within various tight formations in the Rocky Mountain area. This report seeks to quantify what proportion of that resource can be considered recoverable under today's technological and economic conditions and discusses factors controlling recovery. The ultimate goal of this project is to encourage development of tight gas reserves by industry through reducing the technical and economic risks of locating, drilling and completing commercial tight gas wells. This report is the fourth in a series and focuses on the Wind River Basin located in west central Wyoming. The first three reports presented analyses of the tight gas reserves and resources in the Greater Green River Basin (Scotia, 1993), Piceance Basin (Scotia, 1995) and the Uinta Basin (Scotia, 1995). Since each report is a stand-alone document, duplication of language will exist where common aspects are discussed. This study, and the previous three, describe basin-centered gas deposits (Masters, 1979) which contain vast quantities of natural gas entrapped in low permeability (tight), overpressured sandstones occupying a central basin location. Such deposits are generally continuous and are not conventionally trapped by a structural or stratigraphic seal. Rather, the tight character of the reservoirs prevents rapid migration of the gas, and where rates of gas generation exceed rates of escape, an overpressured basin-centered gas deposit results (Spencer, 1987). Since the temperature is a primary controlling factor for the onset and rate of gas generation, these deposits exist in the deeper, central parts of a basin where temperatures generally exceed 200 F and drill depths exceed 8,000 feet. The abbreviation OPT (overpressured tight) is used when referring to sandstone reservoirs that comprise the basin-centered gas deposit. Because the gas resources trapped in this setting are so large, they represent an important source of future gas supply, prompting studies to understand and quantify the resource itself and to develop technologies that will permit commercial exploitation. This study is a contribution to that process.

Robert Caldwell

1998-04-01

258

K-Basins design guidelines  

SciTech Connect

The purpose of the design guidelines is to enable SNF and K Basin personnel to complete fuel and sludge removal, and basin water mitigation by providing engineering guidance for equipment design for the fuel basin, facility modifications (upgrades), remote tools, and new processes. It is not intended to be a purchase order reference for vendors. The document identifies materials, methods, and components that work at K Basins; it also Provides design input and a technical review process to facilitate project interfaces with operations in K Basins. This document is intended to compliment other engineering documentation used at K Basins and throughout the Spent Nuclear Fuel Project. Significant provisions, which are incorporated, include portions of the following: General Design Criteria (DOE 1989), Standard Engineering Practices (WHC-CM-6-1), Engineering Practices Guidelines (WHC 1994b), Hanford Plant Standards (DOE-RL 1989), Safety Analysis Manual (WHC-CM-4-46), and Radiological Design Guide (WHC 1994f). Documents (requirements) essential to the engineering design projects at K Basins are referenced in the guidelines.

Roe, N.R.; Mills, W.C.

1995-06-01

259

Winter in Hellas Basin  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Right now on Mars it is winter in the southern hemisphere. This means that the usually cloudy Hellas Basin is relatively free from clouds. Even though there is little cloud cover, the atmosphere is still much thicker due to the deeper basin compared to elsewhere on Mars, making image details not as crisp as when viewed through thinner atmosphere. In the center of the image are several dark streaks which originate from the side of a higher standing butte. The dark material is likely being eroded from a single layer within the cliff face. Wind has moved some of the eroded dark material to form the streaks.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2002-01-01

260

Basin width control of faulting in the Naryn Basin, south central Kyrgyzstan  

E-print Network

Basin width control of faulting in the Naryn Basin, south central Kyrgyzstan Joseph K. Goode,1 are commonly found within intramontane basins that separate its constituent ranges. In order to explore the controls on this intramontane basin deformation, we study the Naryn Basin of south central Kyrgyzstan

Bookhagen, Bodo

261

Permian-Carboniferous arc magmatism in southern Mexico: U-Pb dating, trace element and Hf isotopic evidence on zircons of earliest subduction beneath the western margin of Gondwana  

NASA Astrophysics Data System (ADS)

Undeformed felsic to mafic igneous rocks, dated by U-Pb zircon geochronology between 311 and 255 Ma, intrude different units of the Oaxacan and Acatlán metamorphic complexes in southwestern Mexico. Rare earth element concentrations on zircons from most of these magmatic rocks have a typical igneous character, with fractionated heavy rare earths and negative Eu anomalies. Only inherited Precambrian zircons are depleted in heavy rare earth elements, which suggest contemporaneous crystallization in equilibrium with metamorphic garnet during granulite facies metamorphism. Hf isotopic signatures are, however, different among these magmatic units. For example, zircons from two of these magmatic units (Cuanana pluton and Honduras batholith) have positive ?Hf values (+3.8-+8.5) and depleted mantle model ages (using a mean crustal value of 176Lu/177Hf = 0.015) ( T DMC) ranging between 756 and 1,057 Ma, whereas zircons from the rest of the magmatic units (Etla granite, Zaniza batholith, Carbonera stock and Sosola rhyolite) have negative ?Hf values (-1 to -14) and model ages between 1,330 and 2,160 Ma. This suggests either recycling of different crustal sources or, more likely, different extents of crustal contamination of arc-related mafic magmas in which the Oaxacan Complex acted as the main contaminant. These plutons thus represent the magmatic expression of the initial stages of eastward subduction of the Pacific plate beneath the western margin of Gondwana, and confirm the existence of a Late Carboniferous-Permian magmatic arc that extended from southern North America to Central America.

Ortega-Obregón, C.; Solari, L.; Gómez-Tuena, A.; Elías-Herrera, M.; Ortega-Gutiérrez, F.; Macías-Romo, C.

2014-07-01

262

Terminal suturing of Gondwana along the southern margin of South China Craton: Evidence from detrital zircon U-Pb ages and Hf isotopes in Cambrian and Ordovician strata, Hainan Island  

NASA Astrophysics Data System (ADS)

Hainan Island, located near the southern end of mainland South China, consists of the Qiongzhong Block to the north and the Sanya Block to the south. In the Cambrian, these blocks were separated by an intervening ocean. U-Pb ages and Hf isotope compositions of detrital zircons from the Cambrian succession in the Sanya Block suggest that the unit contains detritus derived from late Paleoproterozoic and Mesoproterozoic units along the western margin of the West Australia Craton (e.g., Northampton Complex) or the Albany-Fraser-Wilkes orogen, which separates the West Australia and Mawson cratons. Thus, in the Cambrian the Sanya Block was not part of the South China Craton but rather part of the West Australian Craton and its environs. In contrast, overlying Late Ordovician strata display evidence for input of detritus from the Qiongzhong Block, which constituted part of the southeastern convergent plate margin of the South China Craton in the early Paleozoic. The evolving provenance record of the Cambrian and Ordovician strata suggests that the juxtaposition of South China and West Australian cratons occurred during the early to mid-Ordovician. The event was linked with the northern continuation of Kuungan Orogeny, with South China providing a record of final assembly of Gondwana.

Xu, Yajun; Cawood, Peter A.; Du, Yuansheng; Zhong, Zengqiu; Hughes, Nigel C.

2014-12-01

263

The Amazon basin in transition.  

PubMed

Agricultural expansion and climate variability have become important agents of disturbance in the Amazon basin. Recent studies have demonstrated considerable resilience of Amazonian forests to moderate annual drought, but they also show that interactions between deforestation, fire and drought potentially lead to losses of carbon storage and changes in regional precipitation patterns and river discharge. Although the basin-wide impacts of land use and drought may not yet surpass the magnitude of natural variability of hydrologic and biogeochemical cycles, there are some signs of a transition to a disturbance-dominated regime. These signs include changing energy and water cycles in the southern and eastern portions of the Amazon basin. PMID:22258611

Davidson, Eric A; de Araújo, Alessandro C; Artaxo, Paulo; Balch, Jennifer K; Brown, I Foster; C Bustamante, Mercedes M; Coe, Michael T; DeFries, Ruth S; Keller, Michael; Longo, Marcos; Munger, J William; Schroeder, Wilfrid; Soares-Filho, Britaldo S; Souza, Carlos M; Wofsy, Steven C

2012-01-19

264

Contrasting deglacial sedimentary architecture along paleofjord systems due to distance to open-sea, and its importance for hydrocarbon generation; Late Carboniferous units of W-Gondwana, Argentina  

NASA Astrophysics Data System (ADS)

The sedimentary fill of several exhumed paleovalleys cropping out at the Precordillera of San Juan Province Argentina, is compared. All these paleovalley fills show the fairly fast passage from proglacial conditions, well defined by dropstones or by redeposited units contained striated clasts, and eventually by the presence of striated pavements, to non-glacial deep water conditions defined by the lack of proglacial indicators, but instead a much finer-grained sedimentary unit, indicating a quite rapid transgression due to the eustatic rise after deglaciation. On spite of a similar climate-eustatic evolution, the paloefjord fills are quite contrasting in their detailed sedimentary architecture and in their capacity to produce source rock lithologies. We have basically differentiated three main type-cases, and we studied a few examples of each. Each type-case correspond to a realm (internal, intermediate, and marginal) that seems to be related to the distance to the open sea, and hence the capacity to produce restricted conditions in that local segment of the flooded paleovalley. The internal realm is characterized by its closest position to the ice-cap and hence records a maximum degree of glacioisostatic load and minimum connection to open sea processes. As a result, during deglaciation, these basins become deeper and more isolated and thus, better suited for source rock production. The degree of reworking of the deposits is minimum, and preservation is maximum and it is often to record high-slope systems prograding directly onto a fjord deep basin floor. Two paloefjords were studied in detail to characterize this sedimentation mode: the Quebrada Grande and Quebrada de las Lajas paleopjords. The intermediate realm is characterized by a medial position from the ice cap and the continent margin, and it is likely to only have recorded outlet glaciers presence. The glaciostatic load was not so strong and the resulting deglacial sequences are not as thick not so muddy as well. There is not accumulation of source rocks, although some coal beds can be produced during the last stage of palefjord filling. Accumulation at this realm is quite varied, from typical estuarine conditions to slope-complexes generated at the front of braid- and fan-deltas, but there is a high degree of reworking of the deposits due to limited accommodation space and high sediment yield, and as a result sequences are in general much sandier, although their granulometric evolution is similar to that of the internal realm. Two paleofjords were studied in this realm: the Talacasto and Rí San Juan paloefjords. The external realm is characterized by its furthest position with respect to the ice load and as a result the deglacial interval is the thinnest, although due to its distal position, this place has the advantage of recording more previous glacial advances, that were overridden at intermediate and internal positions in the last major glacial advance. At this realm, the postglacial transgression is again quite muddy, as in the internal realm, but in this case, there are no signs of restriction and muds tend to be green, and depleted of organic matter in spite of the rich marine invertebrate fauna, that was not observed at the other sectors. The quantity of wave structures suggest that wave action was much more intense than in the other cases, and in general, there are much less sediments product of gravity flows. We inspected in detail the El Paso and Hoyada Verde paloefjords. This study shows thus, that there is a very important paleogeographic control of depositional processes that have some economic importance. Potential hydrocarbon source rocks would be favored at the inner belt of these palefjords, some doubtful conditions would exist at intermediate positions and basically no source rock would be generated at the outer belt, bear the exits of these paleofjords into the open sea.

Milana, J. P.; Kneller, B.; Dykstra, M.

2009-04-01

265

Basin development and petroleum potential of offshore Otway basin, Australia  

SciTech Connect

The Bass Strait region in southeastern Australia contains three sedimentary basins, which are, from east to west, the Gippsland, Bass, and Otway basins. The offshore Gippsland basin is Australia's most prolific petroleum-producing province and supplies over 90% of the country's production. In contrast, exploration has been unsuccessful in the offshore portion of the Otway basin; 17 wells have been drilled, and although shows of oil and gas have been common, no commercial discoveries have been made. Many of these wells, drilled in the 1960s and 1970s, were sited using poor-quality seismic data and, as a consequence, were frequently off structure. Seismic data quality has, however, improved significantly in recent years. The present study by the Australian Bureau of Mineral Resources (BMR) involved the collection, in the offshore Otway basin, of 3700 km of high-quality, 48-channel seismic reflection data by the BMR research vessel R/V Rig Seismic. These data have been integrated with existing industry seismic data, well data, limited dredged material, and geohistory analyses in a framework study of basin development and hydrocarbon potential in this under-explored area. The offshore Otway basin extends 500 km along the southern coastline and is typically 50 km wide in water depths of less than 200 m. It contains up to 10 km of predominantly late Mesozoic to early Cenozoic sediments, which are overlain by a thin sequence of middle to late Tertiary shelf carbonates. It has been divided into three main structural elements: the Mussel Platform in the east, the central Voluta Trough, and the Crayfish Platform in the west. The basin was initiated at the end of the Jurassic as part of the Bassian rift. Up to 6 km of Lower Cretaceous sediments were deposited prior to breakup at the end of the Early Cretaceous and the onset of sea-floor spreading between Australia and Antarctica.

Williamson, P.E.; O'Brien, G.W.; Swift, M.G.; Scherl, A.S.; Marlow, M.S.; Exon, N.F.; Falvey, D.A.; Lock, J.; Lockwood, K.

1987-05-01

266

Codell Sandstone, Denver basin - frontier exploration in a mature basin  

Microsoft Academic Search

The Codell Sandstone Member of the Carlile Shale is a new exploration target for oil and gas in the northern Denver basin. The Codell interval ranges in thickness from a wedge edge to approximately 100 ft (30.5 m), the average being 15 to 20 ft (4.5 to 6.1 m). The Codell is well developed in the southern Denver basin, is

R. J. Weimer; S. A. Sonnenberg

1983-01-01

267

Hydrocarbon discoveries in Paleozoic Solimoes basin, Upper Amazon region, Brazil  

Microsoft Academic Search

The Solimoes basin, previously known as Upper Amazon basin, is located in northern Brazil and has a prospectable area of more than 300,000 km². The Purus arch, a regional positive feature, separates this basin from the Amazonas basin. As far as the basin geology is concerned, the Solimoes basin is strikingly different from its neighboring basin due to certain structural

N. Apoluceno; A. Ferreira; K. Tsubone

1989-01-01

268

Basin Electric Leland Olds Station  

USGS Multimedia Gallery

Basin Electric Leland Olds Station located near Stanton, North Dakota. It is a coal-fired power plant that use the Missouri River water for cooling. Photo taken by USGS personnel on a Civil Air Patrol flight....

269

Provenance and basin evolution, Zhada basin, southwestern Tibet  

NASA Astrophysics Data System (ADS)

The Zhada basin is a late Miocene - Pliocene intermontane basin situated at high elevations in the Himalayan hinterland. The fluvial and lacustrine sediments of the Zhada formation are undeformed and sit in angular unconformity above the deformed Tethyan Sedimentary Sequence (TSS). The basin sits just south of the Indus suture in a structural position occupied elsewhere in the Himalayan orogen by some of the highest mountains on earth, including Everest. The occurrence of a basin at this location demands explanation. Currently, the Sutlej River flows parallel to the structural grain of the Himalaya, westward through the basin, towards the Leo Pargil (Qusum) range. Near the range front it takes a sharp southward turn, cuts across the structural grain of the Himalaya and out into the Gangetic foreland. Palaeocurrent indicators in the lower part of the Zhada formation show that the basin originated as a northwest flowing axial river. Palaeocurrent indicators are consistently northwest oriented, even to within to within 10 km of the Leo Pargil range front in the north-western end of the basin. This implies that at the onset of sedimentation in Zhada basin the Leo Pargil range was not a barrier as it is today. In the upper part of the Zhada formation, palaeocurrent indicators are generally directed towards the centre of the basin. In the central and southern portions of the basin this indicates a transition from an axial, northwest flowing river to prograding fluvial and alluvial fans. However, in the north-western part of the basin the change between lower and upper Zhada formation involves a complete drainage reversal. This change in palaeocurrent orientation is also reflected in the detrital zircon signal from basin sediments. Low in the Zhada formation the detrital zircon signal is dominated by zircons from the Kailash (Gangdese) batholith (or associated extrusives, see below). However, higher in the sections, a local source, either from the TSS or the core of the Leo Pargil range dominates the detrital zircon signal. Finally, there is a shift in the sandstone composition from unmetamorphosed sedimentary lithic fragments and extrusive felsic volcanic fragments in the lower part of the Zhada formation to metasedimentary and metaigneous fragments in the upper part of the Zhada formation. This is likely linked either to unroofing of the source terrain or a change to another source terrain. Based on the palaeocurrent and detrital zircon data, a change to another source terrain is favoured. This combination of evidence suggests that the Zhada basin evolved from a through-going fluvial plain to a dammed lake primarily due to uplift of the Leo Pargil range. This uplift would have dammed and ponded the river, and exposed higher grade metamorphic rocks at the surface for incorporation into Zhada formation sandstones. It also would have introduced a new source for detrital zircons. Uplift of the Leo Pargil range along a low angle normal fault would also have evacuated portions of the mid-crust, providing a mechanism for subsidence in the Zhada region. Lacustrine sedimentation would have coincided with progradation of marginal alluvial fans and would have continued until the basin was filled in to the level of a new spill point. At this time incision and re- establishment of the Sutlej River would have occurred.

Saylor, J.; Decelles, P.; Gehrels, G.; Kapp, P.

2007-12-01

270

Influence of the Neotethys rifting on the development of the Dampier Sub-basin (North West Shelf of Australia), highlighted by subsidence modelling  

NASA Astrophysics Data System (ADS)

During the Late Palaeozoic and the Mesozoic, the development and evolution of the North West Shelf of Australia have been mostly driven by rifting phases associated with the break-up of Gondwana. These extensional episodes, which culminated in the opening of the Neotethys Ocean during the Permo-Carboniferous and a series of abyssal plains during the Jurassic-Cretaceous, are characterised by different stress regimes and modes of extension, and therefore had distinctive effects on the margin, and particularly on the Northern Carnarvon Basin. Interpretation of 3D and 2D seismic data enables a structural and stratigraphic analysis of the Late Palaeozoic sediments deposited in the proximal part of the Dampier Sub-basin (Mermaid Nose). Based on their seismic characters, stratigraphic relationship, internal patterns, lateral continuity, and architecture, these units are associated here with the Pennsylvanian?-Early Sakmarian glaciogenic Lyons Group and the Sakmarian-Artinskian Callytharra Formation. The former were deposited in a half-graben whose development is associated with the onset of the Neotethys rifting, and the latter is characterised by restricted deposition, inversion of prograding patterns, and uplift. The integration of seismo-stratigraphic characterisation of the Late Palaeozoic sequences and Mesozoic data from one exploration well (Roebuck-1) enables the construction of subsidence curves for the Mermaid Nose and the interpretation of its geohistory. The tectonic subsidence curves show a striking Permo-Carboniferous rifting phase related to the Neotethys rifting and a discrete Late Jurassic-Early Cretaceous event coeval with the opening and the spreading of the Argo Abyssal Plain. This result points out the predominance of the effects of the Permo-Carboniferous Neotethys episode, whereas the extension related to the Argo Abyssal Plain rifting that occurred later and closer to the studied area, had only limited effects on the subsidence of the proximal Dampier Sub-basin. Therefore, it supports a tectonic model with two distinct modes of extension for the Late Palaeozoic (widespread) and the Mesozoic (localised) rifting phases.

Langhi, Laurent; Borel, Gilles D.

2005-03-01

271

Subsidence analysis and quantitative basin modelling in the Styrian Basin (Pannonian Basin System, Austria)  

NASA Astrophysics Data System (ADS)

We present the results of subsidence analysis and of quantitative basin modelling using isostatical and flexural models for basin evolution along four cross-sections in the Styrian Basin, the westernmost subbasin of the Pannonian Basin System. Subsidence analysis reveals a first Ottnangian-Karpatian synrift phase. Our local isostatic models predict crustal stretching values up to 1.3 and subcrustal stretching values of 1.6 for this event. Stretching factors of a minor Sarmatian extension phase are below 1.04. The termination of subsidence during the Pannonian and a rapid Quaternary uplift phase can be explained by major changes in the regional stress field. A W-E cross-section through the northern Fürstenfeld Subbasin provides a key for the understanding of the dynamics of basin formation. It crosses a narrow Karpatian rift basin, the metamorphic core complex of the Penninic Eisenberg Window and shows an eastward tilting of the easternmost part of the basin during Pannonian times. Uplift of the Penninic window can only be modelled with an extremely weak lithosphere (equivalent elastic thickness (EET) ? 2 km), whereas a best fit between observed and modelled tilting is obtained with an EET value of 5 km. These results suggest that the lithosphere was extremely weak during the onset of basin evolution in Ottnangian-Karpatian times, probably caused by high extension rates and high heat flows associated with Karpatian to early Badenian magmatic activity. Subsequent cooling led to a pronounced increase in flexural rigidity. An EET of 5 km fits well with estimations in other parts of the Pannonian realm. Depth-dependent rheology models based on palaeo-heat flow estimates indicate a similar increase in lithospheric strength with time. The impact of Plio-Pleistocene volcanism on rheology appears to be relatively modest, which can be explained by a deep position of the magma chamber for this event.

Sachsenhofer, Reinhard F.; Lankreijer, Anco; Cloetingh, Sierd; Ebner, Fritz

1997-05-01

272

Viscoelastic Relaxation of Lunar Basins  

NASA Astrophysics Data System (ADS)

The large lunar impact basins provide a unique glimpse into early lunar history. Here we investigate the possibility that the relief of the oldest lunar basins (with the exception of South-Pole Aitken) has decayed through viscous relaxation. We identify nine ancient multi-ring basins with very low relief and low-amplitude Bouguer and free-air gravity anomalies. The characteristics of these basins are consistent with either 1) relaxation of topographic relief by ductile flow (e.g. Solomon et al., 1982) or 2) obliteration of basin topography during crater collapse immediately following impact. Both scenarios require that the basins formed early in lunar history, when the Moon was hot. The latter possibility appears to be unlikely due to the great topographic relief of South Pole-Aitken basin (SPA), the largest and oldest impact basin on the Moon (with the possible exception of the putative Procellarum basin; Wilhelms, 1987). On the other hand, the thin crust beneath SPA may not have allowed ductile flow in its lower portions, even for a hot Moon, implying that a thicker crust is required beneath other ancient basins for the hypothesis of viscous relaxation to be tenable. Using a semi-analytic, self-gravitating viscoelastic model, we investigate the conditions necessary to produce viscous relaxation of lunar basins. We model topographic relaxation for a crustal thickness of 30 km, using a dry diabase flow law for the crust and dry olivine for the mantle. We find that the minimum temperature at the base of the crust (Tb) permitting nearly complete relaxation of topography by ductile flow on a timescale < 108 yrs is 1400 K, corresponding to a heat flow of 55mW/m2, into the crust. Ductile flow in the lower crust becomes increasingly difficult as the crustal thickness decreases. The crust beneath SPA, thinned by the impact, is only 15-20 km thick and would require Tb ? 1550 K for relaxation to occur. The fact that SPA has maintained high-amplitude relief suggests that Tb dropped below ˜ 1550 K no later than 100 Myr after the formation of SPA. When did these basins form? The formation of a stable lunar crust ( ˜4.4 Ga) is clearly an upper limit on their age. The precipitation of ilmenite from the magma ocean is predicted to occur at ˜1373 K, which suggests that the lunar magma ocean had not fully crystallized when the oldest basins formed. From thermal evolution models (e.g., Solomon and Longhi, 1977) and crystallization ages of Mg-suite rocks (mostly 4.2-4.4 Ga; Nyquist and Shih, 1992; Snyder et al., 1995) 4.2 Ga appears to be a lower bound on the freezing of the magma ocean (although some residual liquid may have remained in the Procellarum KREEP Terrane). Therefore, the basins that relaxed almost completely due to high crustal base temperatures probably formed between 4.2-4.4 Ga.

Mohit, P. S.; Phillips, R. J.

2004-12-01

273

Structural framework for the emplacement of Proterozoic anorthosite massif in the Eastern Ghats Granulite Belts, India: implications for post Rodinia - pre Gondwana tectonics  

NASA Astrophysics Data System (ADS)

This article deals with the origin of massif type anorthosite (950-1000 Ma) at the vicinity of Eastern Ghat Province (EGP), east coast of India - proto-Indian craton contact. The EGP comprises multiply deformed ortho and para gneiss and foliated igneous rocks intrusive into the otho- and para-gneiss. The earliest deformation is defined by prominent mineral segregation layering (D1) in the host gneiss around Bolangir, EGP, India. The mineral layering is isoclinally folded (D2) with development of pervasive foliation (S2). Asymmetric folds (F3) having short E-W trending and strongly attenuated NNE/NE-trending limbs in the host gneiss characterize D3deformation (950-1000 Ma). D4 deformation is manifested by a set of N/NNE-trending west-vergent folds and coeval shear zones (550 Ma). The gratitoid is characterized by an asymmetrically mono-phase fabric defined by stretched out K-feldspar + biotite + quartz that gradually disappear into a disjunctive foliation away from the pluton margin. The anorthosite pluton is characterized by outward dipping margin parallel foliation that dies out towards the pluton interior. In the southern part of the massif, N-S trending mm- 50 m wide Fe-Ti-Zr rich melt bands are emplaced transverse to the recrystallized igneous features in anorthosite and granitoids. Deflection of S2 foliation of the host gneiss around the pluton indicates that pluton was emplaced after D2 deformation. Evidence of a) diffusion creep in plagioclase within anorthosite, b) asymmetrically folded gneissic fabric in the granotoids, c) the similar ?tpole distribution of margin parallel foliation in anorthosite and ?tpole of S2 foliation in the host gneiss indicate that the pluton and granitoid rocks were emplaced during the D3deformation. The orientation of the shear and shear related fractures in anorthosite (N-S) overlaps with the S4 fabric of the host gneiss. Mean attitude of magnetic foliation (AMS) from the southern and western margin of the pluton confirms that D4 as the last deformation in the complex. In the central part of the pluton, NNE-SSW trending magnetic foliation is similar with the D3-deformation induced mesoscopic fabric. Sub-horizontal deflection of foliation-parallel lineation with increasing magnetic anisotropy (P/) and oblate shape parameter (T>0) in the complex indicate that AMS fabric was developed during transpressional orogeny. The anorthosite and the granitoids were emplaced post D2, syn D3 and pre D4 deformation. The observed mesoscopic and AMS data indicate a switch in the stress field from NNE-SSW (D3, 950-1000 Ma) to E-W (D4, around 550 Ma). The switch is significant in the context of tectonic architecture of Bolangir massif. Breakup of Columbia opened a new ocean between India and Antarctica where the sedimentary sequence of EGP was deposited in the Mesoproterozoic. Inversion of the rift basin tectonics occurred around 1000 Ma, that lead to the collision of eastern India-EGP-Antarctica as a part of Rodinia assembly. However recent studies indicate that EGP did not collide with the proto-Indian craton until the Paleozoic (around 550 Ma) after the final break up stage of Rodinia. This study indicate that anorthosite emplacement in EGP needs to be re-evaluated with recent paleo-geographic models coupled with structural studies.

Nasipuri, P.; Bhadra, S.

2012-04-01

274

Floor of Hellas Basin  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

With a diameter of roughly 2000 km and a depth of over 7 km, the Hellas Basin is the largest impact feature on Mars. Because of its great depth, there is significantly more atmosphere to peer through in order to see its floor, reducing the quality of the images taken from orbit. This THEMIS image straddles a scarp between the Hellas floor and an accumulation of material at least a half kilometer thick that covers much of the floor. The southern half of the image contains some of this material. Strange ovoid landforms are present here that give the appearance of flow. It is possible that water ice or even liquid water was present in the deposits and somehow responsible for the observed landscape. The floor of Hellas remains a poorly understood portion of the planet that should benefit from the analysis of new THEMIS data.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2002-01-01

275

Basin Overflow Floods on Mars  

NASA Astrophysics Data System (ADS)

On Earth, the most intense recognized historical and paleofloods have been ice dambursts or overflows of large basins, often initiated by abundant runoff or meltwater from the contributing watersheds. Many impact craters and other basins also overflowed in the Martian cratered highlands, and some of their incised outlet valleys similarly record evidence of erosive floods. Otherwise, the commonly small, enclosed watersheds on Mars contain poorly developed valley networks and relatively simple depositional landforms, which record little evidence of intense (by terrestrial standards) meteorological floods. For these reasons, basin overflows may have been disproportionately important mechanisms for incision of large valleys on Mars. Many of the Martian outflow channels head in topographic settings that favored ponding, including large canyons, impact or intercrater basins, chaotic terrain basins, and grabens. This topography may have accumulated somewhat slower groundwater discharges from the subsurface to support peak channel discharges of 106-108 m3/s. To yield a discharge of 106, 107, and 108 m3/s from a dam failure with a width/depth ratio of 5, the model predicts that a breach of ~100, 250, and 640 m, respectively, must form rapidly with respect to the decline of lake level. Terrestrial damburst floods have not exceeded ~106 m3/s for earthen dams and ~107 m3/s for ice dams, but brecciation of the Martian surface by impact cratering may have allowed larger damburst failures, whereas solid bedrock was exposed at shallower depths in the terrestrial examples. Moreover, many of the Martian basins were much larger than enclosed continental basins on Earth, so long-lived overflows may have facilitated entrenchment of deeper channels. Some large, mid-latitude basins overflowed to carve Ma'adim Vallis and the Uzboi-Ladon-Margaritifer Valles system, which are similar in scale to the terrestrial Grand Canyon but record much larger formative discharges. Models of damburst floods yield peak discharges that are similar to values derived from channel dimensions in several cases. Smaller basin overflows incised smaller outlet valleys at many locations on Mars.

Irwin, R. P.

2006-12-01

276

Rainbow Basin, CA mapping project  

NSDL National Science Digital Library

Rainbow Basin is just north of Barstow, CA, and is an excellent badlands-style exposure of the Barstow syncline in the Miocene Barstow Formation. In the first mapping class, their assignment is to map the basic geology of the basin, using a couple of distinctive marker beds within the Barstow Formation. Several faults postdate the fold, and three different ages of alluvial deposits occur within the basin. We camp in the nearby Owl Canyon campground, and spend three days in the field. More time could be spent with an introductory class, but three suffices to get most of the basin on the map. They are charged with writing up descriptions of the rock units they encounter. From the field map, students transfer information to an office copy, add a map explanation, and draw a cross-section through the map area. Mapping is done on a topographic map, specifically developed for the basin, with 10-foot contour intervals. This is a proprietary map, so permission is needed for its use.

Joan Fryxell

277

Active Tectonics in the Ohrid Basin (Macedonia\\/Albania)  

Microsoft Academic Search

The Ohrid Basin is a major N-S trending graben structure located on the border of Macedonia and Albania, associated with other basins (Korce basin) in the Dinaride mountain belt. Within the basin an \\

K. Reicherter; N. Hoffmann; T. Fernández-Steeger

2009-01-01

278

Evolution of the San Juan basin, Colorado, and New Mexico basin analysis case study  

Microsoft Academic Search

During 1985 to 1989, the US Geological Survey conducted a basin analysis study that investigated the sedimentological and structural history of the San Juan basin and vicinity. The San Juan basin is a large asymmetric basin in southwest Colorado and northwest New Mexico near the southeastern edge of the Colorado Plateau. It formed as a result of northeast-directed compression coupled

J. L. Ridgley; A. C. Jr. Huffman

1990-01-01

279

Inter-basin dynamics on multidimensional potential surfaces. I. Escape rates on complex basin surfaces  

E-print Network

Inter-basin dynamics on multidimensional potential surfaces. I. Escape rates on complex basin prescription for computing the escape rate of the system from a basin with full consideration of the topographical fingerprint of that basin. The method is based on a solution of the reduced Fokker­Planck equation

Berry, R. Stephen

280

Basin Research (1993)5, 153-1 77 Tectonic evolution of the Alboran Sea basin  

E-print Network

Basin Research (1993)5, 153-1 77 Tectonic evolution of the Alboran Sea basin A. 6. Watts, J. P is an extensional basin of Neogene age that is surrounded by highlv arcuate thrust belts. Multichannel seismic (IMCS)reflection profile data suggest the basin has a complex tectonic fabric that includes extensional, compressional

Watts, A. B. "Tony"

281

Effect of basin physical characteristics on solute fluxes in nine alpine\\/subalpine basins, Colorado, USA  

Microsoft Academic Search

Alpine\\/subalpine basins may exhibit substantial variability in solute fluxes despite many apparent similarities in basin characteristics. An evaluation of controls on spatial patterns in solute fluxes may allow development of predictive tools for assessing basin sensitivity to outside perturbations such as climate change or deposition of atmospheric pollutants. Relationships between basin physical characteristics, determined from geographical information system (GIS) tools,

Julie K. Sueker; David W. Clow; Joseph N. Ryan; Robert D. Jarrett

2001-01-01

282

Water Saving in the Yellow River Basin, China. 2. Assessing the Potential for Improving Basin Irrigation  

Microsoft Academic Search

A study focusing the improvement of the basin irrigation is performed in the Huinong Irrigation District (HID), in the upper reaches of the Yellow River basin, Ningxia Province, and in the Bojili Irrigation District (BID), in the lower reaches of the basin, Shandong Province. Studies include the field evaluation of current basin irrigation practices and the use of the simulation

M. S. Fabião; J. M. Gonçalves; L. S. Pereira; A. A. Campos; Y. Liu; Y. N. Li; Z. Mao; B. Dong

283

Hellas Basin Dunes  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 15 April 2004

The Odyssey spacecraft has completed a full Mars year of observations of the red planet. For the next several weeks the Image of the Day will look back over this first mars year. It will focus on four themes: 1) the poles - with the seasonal changes seen in the retreat and expansion of the caps; 2) craters - with a variety of morphologies relating to impact materials and later alteration, both infilling and exhumation; 3) channels - the clues to liquid surface flow; and 4) volcanic flow features. While some images have helped answer questions about the history of Mars, many have raised new questions that are still being investigated as Odyssey continues collecting data as it orbits Mars.

This daytime VIS image was collected on December 14, 2003 during the southern summer season on the Hellas Basin Rim.

Image information: VIS instrument. Latitude -41.3, Longitude 46.4 East (313.6 West). 19 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

284

Basin-average data: Cloud Albedo and the Diurnal Cycle  

E-print Network

49. Colorado River Basin 50. Congo River Basin 51. Danube River Basin 52. Lena River Basin 53. Mekong 31. Mississippi Ohio 32. Mississippi Lower Mississippi- Tennessee 33. MacKenzie Peel River Basin + Mackenzie Delta 34. MacKenzie Great Bear Lake 35. MacKenzie Great Slave Lake 36. MacKenzie Liard River Basin

Hurrell, James

285

Phosphorus budget-basin relationships for Lake Okeechobee tributary basins  

Microsoft Academic Search

Accelerated cultural eutrophication of Lake Okeechobee, FL by excessive phosphorus (P) loading has generated a need to determine P sources and sinks in the watershed. Average annual P budgets were estimated for each of the 19 tributary basins in the northern Lake Okeechobee watershed for the period 1985–1989. Net P imports were estimated based on P usage by land use

C. F. Boggess; E. G. Flaig; R. C. Fluck

1995-01-01

286

Relation between Tethys sea and Tarim basin  

Microsoft Academic Search

The Tarim basin is the largest continental basin in China. It is known as the heart of central Asia. Still it was related to the Mediterranean Sea in the geological past. Based on the investigations of paleontology, stratigraphy, tectonics, and remote sensing, it is suggested that Tethys and the Tarim basin should be connected from the Late Cretaceous to Miocene.

Wei Junchao

1988-01-01

287

Atlas of the Columbia River Basin  

E-print Network

#12;Atlas of the Columbia River Basin Oregon State University Computer-Assisted Cartography Course & GEOVISUALIZATION GROUP UNIVERSITY #12;2013 Oregon State University Atlas of the Columbia River Basin FOREWORDAtlas, Montana, Nevada, Wyoming, and Utah. 2013 Oregon State University Atlas of the Columbia River Basin

Jenny, Bernhard

288

33 CFR 401.48 - Turning basins.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Turning basins. 401.48 Section 401.48 Navigation...Seaway Navigation § 401.48 Turning basins. No vessel shall be turned about in...South Shore Canal: (a) Turning Basin No. 1—Opposite Brossard. (b)...

2010-07-01

289

33 CFR 401.48 - Turning basins.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Turning basins. 401.48 Section 401.48 Navigation...Seaway Navigation § 401.48 Turning basins. No vessel shall be turned about in...South Shore Canal: (a) Turning Basin No. 1—Opposite Brossard. (b)...

2011-07-01

290

3, 37273770, 2006 Colorado River basin  

E-print Network

HESSD 3, 3727­3770, 2006 Colorado River basin climate change impacts N. Christensen and D and water resources of the Colorado River basin N. Christensen and D. P. Lettenmaier Department of Civil@u.washington.edu) 3727 #12;HESSD 3, 3727­3770, 2006 Colorado River basin climate change impacts N. Christensen and D

Boyer, Edmond

291

6, 839877, 2006 Mexico City basin  

E-print Network

ACPD 6, 839­877, 2006 Mexico City basin ventilation and urban plume B. de Foy et al. Title Page Discussions Rapid ventilation of the Mexico City basin and regional fate of the urban plume B. de Foy 1 , J. R is licensed under a Creative Commons License. 839 #12;ACPD 6, 839­877, 2006 Mexico City basin ventilation

Boyer, Edmond

292

LAND USE AND OWNERSHIP, POWDER RIVER BASIN  

E-print Network

Chapter PM LAND USE AND OWNERSHIP, POWDER RIVER BASIN By T.T. Taber and S.A. Kinney In U........................................PM-1 Map Information for the Powder River Basin Land Use and Land Cover map...........................................................PM-2 Map Information for the Powder River Basin Subsurface Ownership map

293

7, 1303513076, 2007 Basin-scale  

E-print Network

ACPD 7, 13035­13076, 2007 Basin-scale meteorology in the MCMA B. de Foy et al. Title Page Abstract Discussions Basin-scale wind transport during the MILAGRO field campaign and comparison to climatology using, 13035­13076, 2007 Basin-scale meteorology in the MCMA B. de Foy et al. Title Page Abstract Introduction

Paris-Sud XI, Université de

294

Complex Ruelle Operator in a Parabolic Basin  

E-print Network

Complex Ruelle Operator in a Parabolic Basin Dynamical Systems _ where it is and where it is going". 1. Parabolic basin and holomorphic quadratic- __ __ ciated to a parabolic basin of a complex dynamical system. Let R : |C! |C be a rational mapping

Ushiki, Shigehiro

295

33 CFR 401.48 - Turning basins.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Turning basins. 401.48 Section 401.48 Navigation...Seaway Navigation § 401.48 Turning basins. No vessel shall be turned about in...South Shore Canal: (a) Turning Basin No. 1—Opposite Brossard. (b)...

2013-07-01

296

Logical Framework Based Program Development David Basin  

E-print Network

Logical Framework Based Program Development David Basin Institut f¨ur Informatik, Universit¨at Freiburg D­79110 Freiburg, Germany basin@informatik.uni­freiburg.de We propose a methodology the ap­ plication of proof rules. For example, by adopting ideas from [Bundy et al. 1991; Basin and Walsh

Basin, David

297

33 CFR 401.48 - Turning basins.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Turning basins. 401.48 Section 401.48 Navigation...Seaway Navigation § 401.48 Turning basins. No vessel shall be turned about in...South Shore Canal: (a) Turning Basin No. 1—Opposite Brossard. (b)...

2014-07-01

298

33 CFR 401.48 - Turning basins.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Turning basins. 401.48 Section 401.48 Navigation...Seaway Navigation § 401.48 Turning basins. No vessel shall be turned about in...South Shore Canal: (a) Turning Basin No. 1—Opposite Brossard. (b)...

2012-07-01

299

Geological Modeling of Dahomey and Liberian Basins  

E-print Network

The objective of this thesis is to study two Basins of the Gulf of Guinea (GoG), namely the Dahomey and the Liberian Basins. These Basins are located in the northern part of the GoG, where oil and gas exploration has significantly increased...

Gbadamosi, Hakeem B.

2010-01-16

300

Supplementary information on K-Basin sludges  

SciTech Connect

Three previous documents in this series have been published covering the analysis of: K East Basin Floor and Pit Sludge, K East Basin Canister Sludge, and K West Basin Canister Sludge. Since their publication, additional data have been acquired and analyses performed. It is the purpose of this volume to summarize the additional insights gained in the interim time period.

MAKENAS, B.J.

1999-03-15

301

Environmental management in the Colorado River Basin  

Microsoft Academic Search

THe needs, conditions, and prospects for achieving a coordinated and basin-wide program of environmental management in the Colorado River Basin were explored. Analyses are presented. Political and institutional perspectives and the prospects of using environmental indices and the concept of carrying capacity in comprehensive planning are discussed. Since aridity and the limited assimilative capacity of the basin's environmental media place

A. B. Crawford; D. F. Peterson

1974-01-01

302

IMPROVEMENTS IN PUMP INTAKE BASIN DESIGN  

EPA Science Inventory

Pump intake basins (or wet wells or pump sumps) designed in accordance with accepted criteria often pose many operation and maintenance problems. The report summarizes field surveys of three trench-type pump intake basins representative of 29 such basins that have been in satisfa...

303

IMPROVEMENTS IN PUMP INTAKE BASIN DESIGN  

EPA Science Inventory

Pump intake basins (or wet wells or pump sumps) designed in accordance with accepted criteria often pose many operation and maintenance problems. he report summarizes field surveys of three trench-type pump intake basins representative of 29 such basins that ave been in satisfact...

304

Isotope Image of the Central Indian Ocean Basin 50 MY Ago: Dupal Versus Reunion Hotspot Influence  

NASA Astrophysics Data System (ADS)

The central Indian Ocean Basin (CIOB) results from the activity of both the Central and Southeast Indian Ridges; It is crosscut by the track of the Rodrigues triple junction and the Reunion Hotspot was in the vicinity when formed the studied area around 53 Ma ago. The question addressed here in the first place is the composition of the Indian upper mantle 50 Ma ago i.e. its level of isotope heterogeneities within the model in which the breakup of the Gondwana has introduced continental derived material in it. Secondly, the potential input of Reunion hotspot derived material is also investigated. Samples were recovered by dredging in an area comprised between 72-80°E and 9-15°S. They are on axis formed MORB and off axis seamounts. All samples are MORB in composition and slightly depleted in incompatible trace elements. Isotopically (Sr,Nd, Hf and Pb), samples can be separated in four groups. One group contains the most depleted samples in Sr-Nd and Hf isotopes. It also exhibits amongst the least radiogenic Pb isotopes found in Indian MORBs and is regarded as the depleted Indian MORB mantle 50Ma ago. Two groups of samples have similar low 206Pb for higher 208Pb and intend to have even lower 206Pb than the previous group. But they have quite to very radiogenic Sr and accordingly unradiogenic Nd isotopes in agreement with a clear to very pronounced DUPAL signature. The last group has more radiogenic Pb isotopes, and slightly lower Nd for identical St isotopes of the DMM group. This is clearly regarded as representative of recycled oceanic crust material such as seen in Ocean Island Basalts. Mixing models suggest that three components and two stages of mixing are needed to account for the results. The local DMM is firstly contaminated by African Lower Continental Crust (LCC) Material such as granulites during continental breakup. There is some evidence that the contaminant is far from homogeneous and may have contained various amount of phlogopite and/or garnet to account for isotope differences between two groups of samples. Then, the Reunion hotspot may have input some material, the influence of which is seen in the fourth group of samples. The geographic distribution of the groups and modeling suggests that the main DUPAL component was first involved in the melting zone. Later, the least DUPAL component and the Reunion plume material were involved. 0.5 to 3% of African granulitic material is needed within the local upper mantle for the radiogenic two groups whereas 3 to 10% of plume derived material might be necessary to account for the fourth group sample composition. In conclusion, the very depleted local DM and the extreme DUPAL compositions support the concept of LCC contamination of the upper mantle during the Gondwana breakup as 50Ma ago, the mixing and assimilation of the LCC being less advanced than in today Indian upper mantle. This leads to more extreme resulting isotope composition than today.

Hemond, C.; Delavault, H.; Janin, M.; Das, P.; Iyer, S. D.

2012-12-01

305

K Basins Groundwater Monitoring Task, K Basins Closure Project: Report for July, August, and September 2006  

SciTech Connect

This report provides information on groundwater monitoring at the K Basins during July, August, and September 2006. Conditions remain very similar to those reported in the previous quarterly report, with no evidence in monitoring results to suggest groundwater impact from current loss of basin water to the ground. The K Basins monitoring network will be modified in the coming quarters as a consequence of remedial action at KE Basin, i.e., removal of sludge and basin demolition.

Peterson, Robert E.

2006-12-08

306

Basin width control of faulting in the Naryn Basin, south-central Kyrgyzstan  

NASA Astrophysics Data System (ADS)

In Central Asia's Tien Shan, deformation is distributed across the wide orogen, a characteristic of intracontinental mountain building. Active faults are commonly found within intramontane basins that separate its constituent ranges. In order to explore the controls on this intramontane basin deformation, we study the Naryn Basin of south-central Kyrgyzstan. A series of five balanced cross-sections reveals a transition in patterns of faulting from faults confined to basin margins to faults focused within the basin center. The 20-km-wide eastern Naryn Basin displays deformation attributed to low-angle splays of the northern, basin-bounding fault. In the 40-km-wide western Naryn Basin, the pattern of deformation linked to the northern range remains, but is accompanied by steeper faults that dip both south and north without being directly linked to the basin-bounding fault. We compare these cross-sections to synthetic aperture radar interferometry (InSAR) measurements of surface deformation. Profiles of InSAR-derived surface deformation rates across the Naryn Basin reveal that in the west, deformation is distributed across the broad basin interior, whereas in the east, rapid uplift is concentrated at the margin of the narrower basin. From the geodetic and structural data, we infer that in the western Naryn Basin, deformation has migrated away from the northern basin margin and into the interior. Deformation of the eastern basin interior, however, remains linked to the basin-bounding fault. A simple mechanical model demonstrates that basin width may control basin deformation whereby basin-interior faulting in the narrow, eastern Naryn Basin is inhibited by the overburden of adjacent ranges.

Goode, Joseph K.; Burbank, Douglas W.; Bookhagen, Bodo

2011-12-01

307

Evolution of the Congo Basin  

NASA Astrophysics Data System (ADS)

The Congo Basin is one of the largest basins in the World with very little knowledge on the geological evolution as well as the oil and gas potential. In the past, oil seeps are recorded in the central part of the basin. Four sides in the Congo basin have been drilled so far. The cores of the two drill sides Dekese and Samba are located at the Musée royal de l'Afrique Centrale, Belgium. In a reconnaissance survey, we sampled both drill cores in a nearly even spacing of ~ 150 m covering the whole stratigraphy from Albian to Proterozoic. The red and green to grey sandstone samples were prepared by usual heavy minerals separation technique. Most of the samples revealed enough apatite and zircon grains for the two thermochronometric techniques fission track and (U-Th-Sm)/He. The time-temperature (t-T) evolution for the two drill locations were modelled by using the determined thermochronological data within the software code HeFTy. We tested various geological evolutionary constrains. Both techniques provide us information on the thermal and exhumation of the possible source area and on the drill location by themselves.

Glasmacher, U. A.; Bauer, F. U.; Kollenz, S.; Delvaux, D.

2012-04-01

308

The Murray-Darling Basin  

E-print Network

Balancing the priorities of agriculture and the environment Teacher guide and lesson plans Lower secondaryThe Murray-Darling Basin: Balancing the priorities of agriculture and the environment Teacher guide and lesson plans – Lower secondary ISBN: 978-1-74200-129-6 SCIS order number: 1523393 Full bibliographic details are available from

unknown authors

309

BASIN: Beowulf Analysis Symbolic INterface  

NASA Astrophysics Data System (ADS)

BASIN (Beowulf Analysis Symbolic INterface) is a flexible, integrated suite of tools for multiuser parallel data analysis and visualization that allows researchers to harness the power of Beowulf PC clusters and multi-processor machines without necessarily being experts in parallel programming. It also includes general tools for data distribution and parallel operations on distributed data for developing libraries for specific tasks.

Vesperini, Enrico; Goldberg, David M.; McMillan, Stephen L. W.; Dura, James; Jones, Douglas

2013-08-01

310

Polyphemidae of the Pontocaspian Basin  

Microsoft Academic Search

Polyphemidae constitute one of the most characteristic groups of the peculiar auchtochthonous fauna of the Caspian Sea. While in all open seas and freshwaters of the globe they are represented by 8 species only, in Caspian Sea 24 polyphemid species are found and about 15 intraspecific forms. Except one species, all of them are endemic for the Pontocaspian basin (and

Mordukhai-Boltovskoi

1965-01-01

311

GOLF COURSES FRASER RIVER BASIN  

E-print Network

#12;INVENTORY OF GOLF COURSES IN THE FRASER RIVER BASIN FINAL REPORT DOE FRAP 1996-25 Prepared for of Environment Canada. ACKNOWLEDGEMENTS Environment Canada appreciates the contributions of the golf courses who Prevention Section Environment Canada 224 W. Esplanade North Vancouver, B.C. V7M 3H7 #12;ABSTRACT The golf

312

Petrogenesis of Cretaceous mafic intrusive rocks in the Fosdick Mountains, Marie Byrd Land, West Antarctica: melting of metasomatized sub-continental arc mantle along the active plate margin of Gondwana  

NASA Astrophysics Data System (ADS)

A diorite pluton and widely distributed mafic dykes occur in the Fosdick migmatite-granite complex, which is interpreted to represent middle-to-lower crustal rocks of the paleo-Pacific active continental margin of Gondwana. The mafic dykes exhibit a variety of relationships with host rocks in the field ranging from undeformed dykes with sharp contacts with host gneisses to dismembered dykes with comingled textures and numerous back-veins of leucosome intruded from host migmatitic gneisses suggestive of significant interaction with crustal rocks. U-Pb ages for magmatic zircon in these rocks yields Cretaceous crystallization ages ranging from ca. 113 Ma to ca. 98 Ma for the mafic dykes and ca. 100 Ma for the diorite pluton. These mafic intrusive rocks, which contain abundant hydrous minerals, are medium- to high-K-series calc-alkaline rocks with basic-intermediate compositions (47-59 wt % SiO2 for mafic dykes and 52-56 wt % SiO2 for the diorite pluton). They have trace element patterns characterized by LILE enrichments and negative Nb anomalies indicating an origin from a hydrous mantle source metasomatized by slab-derived components. The samples without evidence of interaction with crustal rocks, which are likely to better reflect the mantle source composition, have positive ?Sr(100Ma) values (+8.1 to +14.5) and negative to slightly positive ?Nd(100Ma) values (-1.6 to +2.5) consistent with derivation from an enriched mantle source. These samples may be divided into two groups either characterized by higher LILE/HFSE ratios, less radiogenic ?Sr(100Ma) values and more radiogenic ?Nd(100Ma) values, or characterized by relatively lower LILE/ HFSE ratios, more radiogenic ?Sr(100Ma) values and less radiogenic ?Nd(100Ma) values suggesting differences in the mantle source. The results of this study are consistent with melting of a variably metasomatized sub-arc mantle source during a transition from a wrench to a transtensional tectonic setting, but are inconsistent with a mantle plume origin.

Saito, S.; Brown, M.; Korhonen, F. J.; Mcfadden, R. R.; Siddoway, C. S.

2013-12-01

313

The Late Cambrian Takaka Terrane, NW Nelson, New Zealand: Accretionary-prism development and arc collision followed by extension and fan-delta deposition at the SE margin of Gondwana  

NASA Astrophysics Data System (ADS)

Re-evaluation of field and lab data indicates that the Cambrian portion of the Takaka Terrane in the Cobb Valley area of NW Nelson, New Zealand preserves the remnants of an accretionary prism complex, across which the Lockett Conglomerate fan-delta was deposited as a consequence of extension. Previous work has recognized that the structurally disrupted lower Takaka Terrane rocks present an amalgam of sedimentary and igneous rocks generated prior to convergence (Junction Formation) or during convergence (Devil River Volcanics Group, Haupiri Group), including arc-related and MORB components. Portions of the sequence have in the past been loosely described as an accretionary prism. Reevaluation of the detailed mapping, sedimentological and provenance studies shows that remnants of a stratigraphic sequence (Junction Formation, Devil River Volcanics Group, Haupiri Group) can be traced through 10 fault-bounded slices, which include a mélange-dominated slice (Balloon Mélange). These slices are the remnants of the accretionary prism; the stratigraphy within each slice generally youngs to the east, and the overall pattern of aging (based on relative age from provenance studies, sparse fossils, stratigraphic relations, and limited isotopic data) indicates that the older rocks generally dominate fault slices to the east, and younger rocks dominate fault slices to the west, delineating imbricate slices within an eastward-dipping subduction zone, in which the faults record a complex history of multi-phase reactivation. The Lockett Conglomerate is a ~500-m thick fan-delta conglomerate that is the preserved within one of the fault slices, where it is stratigraphically and structurally highest unit in the lower Takaka Terrane; it is also present as blocks within the Balloon Melange. The Lockett Conglomerate is marine at its base and transitions upwards to fluvial facies. The Lockett Conglomerate has previously been interpreted to result from erosion consequent on continued convergence, but is reinterpreted here as a ';true' fan-delta deposit, sedimentologically similar to deposits associated with extension. Textural and compositional data for the Lockett Conglomerate indicates rapid supply of new material (including quartzite, granite, gabbro, and amphibolitic metavolcanics). The Lockett Conglomerate is proposed here to record the initiation of extension, during which basement faults in the hinterland exposed previously buried source rocks. This new interpretation of the Lockett Conglomerate places that initiation of extension and subsequent passive margin sedimentation (Mt. Ellis and Mt. Arthur Groups) earlier (late Middle Cambrian) than previous work has suggested (Late Cambrian or Early Ordovician). These new interpretations provide input useful for correlations and interpretations of the complex mosaic that preserves a record of tectonic activity and processes at the Antarctic, Tasmanian and SE Australian portions of the Cambrian Gondwana margin.

Pound, K. S.

2013-12-01

314

THE ADVANCED CHEMISTRY BASINS PROJECT  

SciTech Connect

In the next decades, oil exploration by majors and independents will increasingly be in remote, inaccessible areas, or in areas where there has been extensive shallow exploration but deeper exploration potential may remain; areas where the collection of data is expensive, difficult, or even impossible, and where the most efficient use of existing data can drive the economics of the target. The ability to read hydrocarbon chemistry in terms of subsurface migration processes by relating it to the evolution of the basin and fluid migration is perhaps the single technological capability that could most improve our ability to explore effectively because it would allow us to use a vast store of existing or easily collected chemical data to determine the major migration pathways in a basin and to determine if there is deep exploration potential. To this end a the DOE funded a joint effort between California Institute of Technology, Cornell University, and GeoGroup Inc. to assemble a representative set of maturity and maturation kinetic models and develop an advanced basin model able to predict the chemistry of hydrocarbons in a basin from this input data. The four year project is now completed and has produced set of public domain maturity indicator and maturation kinetic data set, an oil chemistry and flash calculation tool operable under Excel, and a user friendly, graphically intuitive basin model that uses this data and flash tool, operates on a PC, and simulates hydrocarbon generation and migration and the chemical changes that can occur during migration (such as phase separation and gas washing). The DOE Advanced Chemistry Basin Model includes a number of new methods that represent advances over current technology. The model is built around the concept of handling arbitrarily detailed chemical composition of fluids in a robust finite-element 2-D grid. There are three themes on which the model focuses: chemical kinetic and equilibrium reaction parameters, chemical phase equilibrium, and physical flow through porous media. The chemical kinetic scheme includes thermal indicators including vitrinite, sterane ratios, hopane ratios, and diamonoids; and a user-modifiable reaction network for primary and secondary maturation. Also provided is a database of type-specific kerogen maturation schemes. The phase equilibrium scheme includes modules for primary and secondary migration, multi-phase equilibrium (flash) calculations, and viscosity predictions.

William Goddard; Peter Meulbroek; Yongchun Tang; Lawrence Cathles III

2004-04-05

315

Environmental change in the Mississippi River Basin  

NASA Astrophysics Data System (ADS)

Land use, land cover change and hydrological modification are important factors affecting discharge, sediment yield, nutrient flows and precipitation at small and large scales. This presentation analyses the changes in crop and pasture land as well as dam and reservoir construction from 1900 to the present in the Mississippi River Basin (including six main sub-basins), to assess their influence on sediment and nutrient dynamics in the basin. Total cropland and pastureland from 1900-2007 are characterized at 0.5 degree x 0.5 degree spatial resolution from existing satellite-derived datasets. From 1900s to 2000s, total cropland in the Ohio River Basin and the Tennessee River Basin in the east exhibited a decreasing trend. The other sub-basins and the basin as a whole exhibited an increasing trend. The area under pasture in the Ohio, the Tennessee and the Upper Mississippi river basins decreased; it increased in the other sub-basins. The areas of corn, wheat and soybean, the three dominant crops in the United States, from 1950 to 2000 are characterized at 5’ x 5’ spatial resolution from existing inventory and satellite-data. The fractional coverage of soybean and wheat increased in most sub-basins, whereas the fraction of corn remained constant or decreased in most sub-basins. The distribution of dams and large dams (those with a normal storage capacity of 5000 acre-feet or more) built in each decade was generated from the data published by National Atlas of the United States. The analysis showed that the majority of the dams in Mississippi River Basin were built in 1960s and 1970s, but the majority of the large dams were built before the 1950s. These spatial and temporal changes in land use, land cover and hydrological modifications are linked to sediment, nutrient and environmental change of the basin.

Xu, X.; Wynn, G.; Hassan, M. A.; Donner, S. D.; Sivapalan, M.

2010-12-01

316

Animals of the Great Basin  

NSDL National Science Digital Library

The Biological Resources Research Center of the University of Nevada at Reno provides this resource on the Animals of the Great Basin. Organized under two main sections (Invertebrates and Vertebrates), the site offers a series of hyperlinked state species lists, distribution maps, and photos of select fauna. In addition, an annotated, indexed bibliography on Trout points users to more in-depth information on that taxa. While not all fauna (nor states within the Great Basin) are represented in every case, this site nevertheless serves a useful purpose in centralizing available information on certain taxa and states. In addition, users will appreciate the care that site authors have taken in providing information on the authority behind each information source.

317

CLEAR LAKE BASIN 2000 PROJECT  

SciTech Connect

The following is a final report for the Clear Lake Basin 2000 project. All of the major project construction work was complete and this phase generally included final details and testing. Most of the work was electrical. Erosion control activities were underway to prepare for the rainy season. System testing including pump stations, electrical and computer control systems was conducted. Most of the project focus from November onward was completing punch list items.

LAKE COUNTY SANITATION DISTRICT

2003-03-31

318

Indians of the Great Basin  

NSDL National Science Digital Library

Tad Beckman, professor at Harvey Mudd College, has developed the Indians of the Great Basin site in conjunction with a course he taught on "Indigenous People of the Western United States" at Harvey Mudd College. The eleven "chapters" discuss the archaeology of the region; the material, social, and political cultures; spiritualism; and the arts. Illustrations (photos and maps) and related Internet resources accompany each discussion. Finally, a complete bibliography of all the cited works is available.

Beckman, Tad.

319

Analysing diagenetic effects of flood basalts on sedimentary basins during Gondwanan break-up: case studies from NW Namibia.  

NASA Astrophysics Data System (ADS)

ABSTRACT The eruption of large volumes of lava associated with the break-up and dispersal of the Gondwana Supercontinent is a phenomenon that has been well documented in literature. The Etendeka Flood Basalt Province of NW Namibia is correlated with the Paraná Flood Basalt Province of South America and was extruded between 139Ma for the earliest flows and 130Ma for the most recent. The passive, inflated pahoehoe lava flows have preserved bedforms within sand dunes found in the Huab Basin without significant deformation. This allows the internal structures of the palaeo-dunes to be analysed with great accuracy; a phenomenon rarely seen within the geological record. The sediments directly beneath, and interbedded with, the Etendeka Flood Basalt are lithostratigraphically similar to those in the Kudu Gas Province, offshore Namibia, where gas-bearing aeolian sands are interspersed with lava flows. Research by the authors is focussed on the diagenetic effects, both direct and indirect, of the emplacement of the lava, and the associated sills and dykes, on the aeolian sands. Specific interests include: the compartmentalisation of the basin by sills/dykes/lava: how does this affect fluid flow paths? Diagenesis along hot contacts: is the dramatic reduction in porosity/permeability along such contacts the result of the igneous bodies alone or do they need ground water present? Can large igneous events trigger the movement of hot fluids through the basin and to what extent does this cause alteration to sediments? To address these issues we have identified a number of outcrop case studies within the Huab Basin in NW Namibia. Here, excellent 3 dimensional outcrop coupled with almost 100 percent exposure allows detailed sampling strategies to be employed on locations of interest. In some cases igneous dykes have acted as flow barriers to pore fluids and have therefore altered the type and degree of cementation either side of the dyke. Geochemical analysis of the cement can shed some light on the origin of the associated fluids and determine whether hot fluids have been triggered by the lava. The systematic burial of aeolian landforms by pahoehoe lava flows has preserved the original features in many of the dunes and has created ponds of lava in inter-dune areas. Suites of samples collected from the igneous contact have been analysed to assess the extent of diagenesis related, either directly or indirectly, to the lava eruption. The sandstone is shown to be well-cemented in an indurated zone (visually 1-2m wide) beside the contact but less well-cemented with distance from it. The degree of porosity change away from the contact has been measured using image analysis software on stained thin sections and the chemistry of pore-filling cement analysed using laser microsampling and spectroscopic analysis. Normalised del.18O values decrease steadily from values of 15.6 (+/- 0.2)percent at the contact to 14.4 (+/- 0.2)percent at a distance of 4m from it. The sediments from the Etendeka in NW Namibia provide examples of intrusion and lava contacts in an essentially dry basin setting. This allows the investigation of the direct effect of the igneous bodies on the sediments without massive overprinting due to further diagenesis caused by ground water. In the few areas where later groundwater fluids have entered the basin we are able to successfully compare the direct with indirect effects of the igneous rocks. ACKNOWLEDGEMENTS This research is part of a PhD thesis currently being undertaken by Graham Thompson under the supervision of Dr. Dougal Jerram and Dr. Graham Pearson. The research is funded by Enterprise Oil / Shell (UK). I acknowledge with gratitude Dr. Chris Harris and his colleagues at the University of Cape Town who provided oxygen isotope data for a number of samples.

Thompson, G. A.; Jerram, D. A.; Harris, C.; Pearson, D. G.

2003-04-01

320

UPPER SNAKE RIVER PRIORITY BASIN ACCOMPLISHMENT PLAN, APRIL 1973  

EPA Science Inventory

The Upper Snake Accomplishment Basin (17040104, 170402, 170501) is defined as the Idaho and Oregon portions of 2 STORET Basins, the Upper Snake Basin and the Central Snake Basin. The Basin drains approximately 62,100 square miles in Southern Idaho and Southeastern Oregon. Four ...

321

Neuse River Basin, North Carolina Ecosystem Restoration Project  

E-print Network

Neuse River Basin, North Carolina Ecosystem Restoration Project 5 October 2012 ABSTRACT: The study area encompasses the Neuse River Basin, the third-largest river basin in North Carolina. The Basin. The study investigated the quality of the overall Neuse River Basin ecosystem and the level of flood risk

US Army Corps of Engineers

322

Permian geology of Gondwana countries: An overview  

SciTech Connect

Earliest Permian sequences of Antarctica, southern and east-central Africa, the southern part of the Arabian Peninsula, Pakistan, peninsular and Himalayan India, Tibet, western and eastern Australia, New Zealand, and South America are all characterized by glacial deposits and cold-water marine faunas. In the course of the Permian, considerable faunal (and floral) and climatic divergence occurred. Although folding is not necessarily present, the effects of the strong compressive tectonic phase (Hunter-Bowen Orogenic Folding Phase of Dickins) beginning in the mid-Permian (traditional two-fold subdivision) and of acidic and intermediate volcano-magmatic activity are apparent in all these regions as in other parts of the world. The progressive continentality of the Upper Permian (worldwide regression) culminates at the Permian-Triassic (Changxingian-Griesbachian) boundary.

Dickins, J.M. (Australian Bureau of Mineral Resources, Canberra (Australia))

1992-10-01

323

Slope-apron deposition in an ordovician arc-related setting: The Vuelta de Las Tolas Member (Suri Formation), Famatina Basin, northwest Argentina  

USGS Publications Warehouse

The Ordovician Suri Formation is part of the infill of the Famatina Basin of northwest Argentina, which formed in an active setting along the western margin of early Paleozoic Gondwana. The lower part of this formation, the Vuelta de Las Tolas Member, records sedimentation on a slope apron formed in an intra-arc basin situated on a flooded continental arc platform. The coincidence of a thick Arenig-Llanvirn sedimentary succession and volcanic-plutonic arc rocks suggests an extensional or transtensional arc setting, and is consistent with evidence of an extensional regime within the volcanic arc in the northern Puna region. The studied stratigraphic sections consist of volcanic rocks and six sedimentary facies. The facies can be clustered into four facies associations. Association 1, composed of facies A (laminated siltstones and mudstones) and B (massive mudstones and siltstones), is interpreted to have accumulated from silty-muddy high-and low-density turbidity currents and highly fluid, silty debris flows, with subsequent reworking by bottom currents, and to a lesser extent, hemipelagic suspension in an open-slope setting. Facies association 2 is dominated by facies C (current-rippled siltstones) strata. These deposits are interpreted to record overbank sedimentation from fine-grained turbidity currents. Facies E (matrix-supported volcanic breccias) interbedded with andesitic lava units comprises facies association 3. Deposition was contemporaneous with subaqueous volcanic activity, and accumulated from cohesive debris flows in a coarse-grained wedge at the base of slope. Facies association 4 is typified by facies D (vitric fine-grained sandstones and siltstones) and F (channelized and graded volcanic conglomerates and breccias) deposits. These strata commonly display thinning-and fining-upward trends, indicating sedimentation from highly-concentrated volcaniclastic turbidity currents in a channelized system. The general characteristics of these deposits of fresh pyroclastic detritus suggest that their accumulation was contemporaneous with, or post-dated shallow-water or subaereal explosive volcanism. The Vuelta de Las Tolas Member tends to show an overall random facies patterns reflecting the strong influence of non-cyclical episodic processes related to arc volcanism and slope sedimentation. The scarcity of resident ichnofaunas and the presence of thick packages of uniform mudstones suggest deposition under oxygen-depleted conditions in a topographically confined, ponded sub-basin. Interbasinal correlations favor comparison with Middle Arenig slope-apron successions formed in the northern Puna Basin and suggest a southward prolongation of the Arenig volcanic arc.

Mangano, M.G.; Buatois, L.A.

1997-01-01

324

Fault kinematics and depocenter evolution of oil-bearing, continental successions of the Mina del Carmen Formation (Albian) in the Golfo San Jorge basin, Argentina  

NASA Astrophysics Data System (ADS)

Up to 10% of the liquid hydrocarbons of the Golfo San Jorge basin come from the Mina del Carmen Formation (Albian), an ash-dominated fluvial succession preserved in a variably integrated channel network that evolved coeval to an extensional tectonic event, poorly analyzed up to date. Fault orientation, throw distribution and kinematics of fault populations affecting the Mina del Carmen Formation were investigated using a 3D seismic dataset in the Cerro Dragón field (Eastern Sector of the Golfo San Jorge basin). Thickness maps of the seismic sub-units that integrate the Mina del Carmen Formation, named MEC-A-MEC-C in ascending order, and mapping of fluvial channels performed applying geophysical tools of visualization were integrated to the kinematical analysis of 20 main normal faults of the field. The study provides examples of changes in fault throw patterns with time, associated with faults of different orientations. The "main synrift phase" is characterized by NE-SW striking (mean Az = 49°), basement-involved normal faults that attains its maximum throw on top of the volcanic basement; this set of faults was active during deposition of the Las Heras Group and Pozo D-129 formation. A "second synrift phase" is recognized by E-W striking normal faults (mean Az = 91°) that nucleated and propagated from the Albian Mina del Carmen Formation. Fault activity was localized during deposition of the MEC-A sub-unit, but generalized during deposition of MEC-B sub-unit, producing centripetal and partially isolated depocenters. Upward decreasing in fault activity is inferred by more gradual thickness variation of MEC-C and the overlying Lower Member of Bajo Barreal Formation, evidencing passive infilling of relief associated to fault boundaries, and conformation of wider depocenters with well integrated networks of channels of larger dimensions but random orientation. Lately, the Mina del Carmen Formation was affected by the downward propagation of E-W to ESE-WNW striking normal faults (mean Az = 98°) formed during the "third rifting phase", which occurs coeval with the deposition of the Upper Member of the Bajo Barreal Formation. The fault characteristics indicate a counterclockwise rotation of the stress field during the deposition of the Chubut Group of the Golfo San Jorge basin, likely associated to the rotation of Southern South America during the fragmentation of the Gondwana paleocontinent. Understanding the evolution of fault-controlled topography in continental basins allow to infer location and orientation of coeval fluvial systems, providing a more reliable scenario for location of producing oil wells.

Paredes, José Matildo; Plazibat, Silvana; Crovetto, Carolina; Stein, Julián; Cayo, Eric; Schiuma, Ariel

2013-10-01

325

Evolution of extensional basins and basin and range topography west of Death Valley, California  

E-print Network

Neogene extension in the Death Valley region, SE California, has produced a variety of sedimentary basins. Diachronous movements on an array of strike-slip and normal fault systems have resulted in the uplift and preservation of older basins...

Hodges, K. V.; McKenna, L. W.; Stock, J.; Knapp, J.; Page, L.; Sternlof, K.; Silverberg, D.; Wust, G.; Walker, J. Douglas

1989-06-01

326

The West Philippine Basin: An Eocene to early Oligocene back arc basin opened between two opposed subduction zones  

E-print Network

The West Philippine Basin: An Eocene to early Oligocene back arc basin opened between two opposed Basin and its boundaries, we propose a comprehensive Cenozoic history of the basin. Our model shows that it is a back arc basin that developed between two opposed subduction zones. Rifting started around 55 Ma

Demouchy, Sylvie

327

Reserve estimates in western basins. Part 2: Piceance Basin  

SciTech Connect

This study characterizes an extremely large gas resource located in low permeability, sandstone reservoirs of the Mesaverde group in the Piceance Basin, Colorado. Total in place resource is estimated at 307.3 Tcf. Via application of geologic, engineering and economic criteria, the portion of this resource potentially recoverable as reserves is estimated. Those volumes estimated include probable, possible and potential categories and total 5.8 Tcf as a mean estimate of recoverable gas for all plays considered in the basin. About 82.6% of the total evaluated resource is contained within sandstones that have extremely poor reservoir properties with permeabilities considered too low for commerciality using current frac technology. Cost reductions and technology improvements will be required to unlock portions of this enormous resource. Approximately 2.7% of the total resource is contained within sandstone reservoirs which do not respond to massive hydraulic fracture treatments, probably due to their natural lenticular nature. Approximately 6.8% of the total resource is located in deeply buried settings below deepest established production. Approximately 7.9% of the total resource is considered to represent tight reservoirs that may be commercially exploited using today`s hydraulic fracturing technology. Recent technology advances in hydraulic fracturing practices in the Piceance Basin Mesaverde has resulted in a marked improvement in per well gas recovery which, where demonstrated, has been incorporated into the estimates provided in this report. This improvement is so significant in changing the risk-reward relationship that has historically characterized this play, that previously uneconomic areas and resources will graduate to the economically exploitable category. 48 refs., 96 figs., 18 tabs.

NONE

1995-10-01

328

Reserves in western basins: Part 1, Greater Green River basin  

SciTech Connect

This study characterizes an extremely large gas resource located in low permeability, overpressured sandstone reservoirs located below 8,000 feet drill depth in the Greater Green River basin, Wyoming. Total in place resource is estimated at 1,968 Tcf. Via application of geologic, engineering and economic criteria, the portion of this resource potentially recoverable as reserves is estimated. Those volumes estimated include probable, possible and potential categories and total 33 Tcf as a mean estimate of recoverable gas for all plays considered in the basin. Five plays (formations) were included in this study and each was separately analyzed in terms of its overpressured, tight gas resource, established productive characteristics and future reserves potential based on a constant $2/Mcf wellhead gas price scenario. A scheme has been developed to break the overall resource estimate down into components that can be considered as differing technical and economic challenges that must be overcome in order to exploit such resources: in other words, to convert those resources to economically recoverable reserves. Total recoverable reserves estimates of 33 Tcf do not include the existing production from overpressured tight reservoirs in the basin. These have estimated ultimate recovery of approximately 1.6 Tcf, or a per well average recovery of 2.3 Bcf. Due to the fact that considerable pay thicknesses can be present, wells can be economic despite limited drainage areas. It is typical for significant bypassed gas to be present at inter-well locations because drainage areas are commonly less than regulatory well spacing requirements.

Not Available

1993-10-01

329

Regional geophysics and the basement of cratonic basins: a comparative study with the Michigan basin  

SciTech Connect

The basement of the Michigan basin consists of four major provinces - the complex metasedimentary, metavolcanic, and igneous rocks of the Penokean orogenic assemblage in the north, the felsic anorogenic igneous rocks to the south, the highly metamorphosed schists, gneisses, and related igneous intrusions of the Grenville province in the east, and a middle Proterozoic rift zone, which transects the basin from the north to the southeast margin. Sparse basement drill holes and characteristic geophysical patterns support this interpretation. The direct geologic information on the basement of other cratonic basins is not as well known. However, regional geophysical surveys and sparse, poorly distributed basement drill holes provide information on the complex character and structural relationships of the basement of other basins. Like the Michigan basin, many cratonic basins (e.g., Illinois, Williston, and Paris basins) are underlain by dense and commonly more magnetic rocks than adjacent areas. As in the Michigan basin, these rocks are interpreted to have a profound effect on the origin and tectonic development of the basins. Geologic and geophysical evidence indicates that many of these dense basement rocks originated in rifts that formed hundreds of millions of years prior to basin development. A comparison of the basement in cratonic basins provides important constraints on the origin and tectonic development of the Michigan basin.

Hinze, W.J.; Lidiak, E.G.

1986-08-01

330

Water management and decisionmaking in the Nile Basin: A case study of the Nile Basin Initiative  

Microsoft Academic Search

The management of international waterways presents riparian nations with a challenging set of political, economic, environmental, and geographic difficulties. Historically, the Nile Basin has exemplified many of these problems as witnessed by inter-basin conflict, devastating floods, crippling drought, and unstable political and economic development. Despite their tumultuous past the ten riparian nations of the Nile Basin established a supranational water

John C Merrill

2008-01-01

331

Petrography and major element geochemistry of the Permo-Triassic sandstones, central India: Implications for provenance in an intracratonic pull-apart basin  

NASA Astrophysics Data System (ADS)

Detrital mode, composition of feldspars and heavy minerals, and major element chemistry of sandstones from the Permo-Triassic succession in the intracratonic Satpura Gondwana basin, central India have been used to investigate provenance. The Talchir Formation, the lowermost unit of the succession, comprises glacio-marine and glacio-fluvial deposits. The rest of the succession (base to top) comprising the Barakar, Motur, Bijori, Pachmarhi and Denwa formations, largely represent variety of fluvial depositional systems with minor fluvio-deltaic and fluvio-lacustrine sedimentation under a variety of climatic conditions including cold, warm, arid, sub-humid and semi-arid. QFL compositions of the sandstones indicate a predominantly continental block provenance and stable cratonic to fault-bounded basement uplift tectonic setting. Compositional maturity of sandstones gradually increases upwards from the Early Permian Talchir to the Middle Triassic Denwa but is punctuated by a sharp peak of increased maturity in the Barakar sandstones. This temporal change in maturity was primarily controlled by temporal variation in fault-induced basement uplift in the craton and was also influenced by climatic factors. Plots of different quartz types suggest plutonic source rocks for the Talchir sandstones and medium-to high-rank metamorphic plus plutonic source rocks for the younger sandstones. Composition of alkali feldspars in the Permo-Triassic sandstones and in different Precambrian rocks suggests sediment derivation from felsic igneous and metasedimentary rocks. Compositions of plagioclase in the Talchir and Bijori sandstones are comparable with those of granite, acid volcanic and metasedimentary rocks of the Precambrian basement suggesting the latter as possible source. Rare presence of high-K plagioclase in the Talchir sandstones, however, indicates minor contribution from volcanic source rock. Exclusively plagioclase-bearing metasedimentary rock, tonalite gneiss and mafic rocks are the probable sources of plagioclase in the Upper Denwa sandstones. Quartz-rich nature of the sandstones, predominance of K-feldspar over plagioclase and albite rich character of plagioclase in the sandstones is consistent with deposition in an intracratonic, pull-apart basin like the Satpura Gondwana basin. Composition of garnet and its comparison with that from the Precambrian basement rocks suggests mica-schist and amphibolite as possible sources. Predominance of dravite variety of tourmaline in the Permian sandstones suggests sediment supply from metasedimentary rocks. Presence of both dravite and schorl variety of tourmaline in subequal amount in the Triassic sandstones indicates sediment derivation from granitic and metasedimentary rocks. However, schorl-bearing rocks are absent in the basement complex of the study area. A-CN-K plot suggests granites, acid volcanic rock and meta-sediments of the basement as possible sources of the Talchir sandstones and metasedimentary rocks for the Barakar to Pachmarhi sandstones. The Denwa sandstones were possibly derived from K-feldspar-free, plagioclase-bearing metasediments, mafic rocks and tonalite gneiss. Chemical Index of Alteration (CIA) values suggest low intensity source rock weathering for the Talchir sandstones and higher intensity source rock weathering for the others. Various bivariate plots of major oxides composition of the sandstones suggest passive to active continental margin setting and even arc tectonic setting for a few samples.

Ghosh, Sampa; Sarkar, Soumen; Ghosh, Parthasarathi

2012-01-01

332

Magnetic Fabric of the Aquidauana Formation, western border of the Paraná Basin Central Brazil: Preliminary Results  

NASA Astrophysics Data System (ADS)

The glaciogenic sedimentation (Carboniferous-Permian) on the western border of the Paraná Basin is represented by reddish-brown strata of the Aquidauana Formation. Subsurface data suggest that this Formation is equivalent to the Itararé Group, which contains the most extensive lithological record of Gondwana glaciation in the world. The Aquidauna Formation crops out as an NNE-SSW-oriented elongated belt at the western portion of the Maracaju-Campo Grande Plateau in Mato Grosso do Sul State (Central part of Brazil), and extents to the north up to Mato Grosso and Goias states. This Formation is composed of a variety of types of sandstones, siltites, and mudstones. The magnetic studies were performed on sites of undeformed reddish-brown sandstones, siltites, and mudstones, which crop out mainly in Mato Grosso do Sul State. Magnetic fabrics were determined on oriented cylindrical specimens (2.54 cm x 2.2 cm) using anisotropy of low-field magnetic susceptibility (AMS). Rock-magnetic analyses reveal that both magnetite and hematite are the main magnetic minerals in the majority of the analyzed sites. Regarding the eingenvector orientations, the sites usually gave good results. The analysis at the individual-site scale defines two AMS fabric types. The first type shows Kmin perpendicular to the bedding plane, while Kmax and Kint are scattered within the bedding plane itself. This fabric is usually interpreted as primary (sedimentary-compactional), typical of undeformed sediments and is dominant among the sites. The second type shows good clustering of the AMS principal axes with Kmin still either perpendicular or sub-perpendicular to the bedding plane. This fabric type could be interpreted as a combination of sedimentary-compactional and tectonic contributions if some strain markers or evidence for tectonic deformation had been found in the studied area. On the other hand, the tight Kmax grouping in this fabric type could be explained by the action of currents since they cause Kmax to be aligned sub-parallel to the paleocurrent direction.

Raposo, M. B.

2013-05-01

333

76 FR 23276 - Lake Tahoe Basin Federal Advisory Committee (LTFAC)  

Federal Register 2010, 2011, 2012, 2013, 2014

...OF AGRICULTURE Forest Service Lake Tahoe Basin Federal Advisory Committee (LTFAC) AGENCY...SUMMARY: The Lake Tahoe Basin Federal Advisory Committee will hold a...Date) Contact: Arla Hains, Lake Tahoe Basin Management Unit, Forest Service, 35...

2011-04-26

334

75 FR 6348 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013, 2014

...OF AGRICULTURE Forest Service Lake Tahoe Basin Federal Advisory Committee AGENCY: Forest...SUMMARY: The Lake Tahoe Basin Federal Advisory Committee (LTFAC) will...INFORMATION CONTACT: Arla Hams, Lake Tahoe Basin Management Unit (LTBMU), Forest...

2010-02-09

335

75 FR 13252 - Lake Tahoe Basin Federal Advisory Committee (LTFAC)  

Federal Register 2010, 2011, 2012, 2013, 2014

...OF AGRICULTURE Forest Service Lake Tahoe Basin Federal Advisory Committee (LTFAC) AGENCY...SUMMARY: The Lake Tahoe Basin Federal Advisory Committee will hold a...date) Contact: Arla Hams, Lake Tahoe Basin Management Unit, Forest Service, 35...

2010-03-19

336

78 FR 23784 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Public Law...

2013-04-22

337

76 FR 61382 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

2011-10-04

338

77 FR 23508 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

2012-04-19

339

75 FR 66389 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

2010-10-28

340

76 FR 24515 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...announces that the Colorado River Basin Salinity Control Advisory Council (Council...INFORMATION: The Colorado River Basin Salinity Control Advisory Council was...

2011-05-02

341

75 FR 27360 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

2010-05-14

342

78 FR 70574 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...REG0000, RR04084000] Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub....

2013-11-26

343

77 FR 61784 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control Act of 1974 (Pub. L....

2012-10-11

344

75 FR 25877 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bureau of Reclamation Colorado River Basin Salinity Control Advisory Council AGENCY: Bureau...SUMMARY: The Colorado River Basin Salinity Control Advisory Council (Council) was established by the Colorado River Basin Salinity Control [[Page 25878

2010-05-10

345

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Caribbean Basin Trade Initiative. 25.405 Section 25.405...SOCIOECONOMIC PROGRAMS FOREIGN ACQUISITION Trade Agreements 25.405 Caribbean Basin Trade Initiative. Under the Caribbean Basin...

2014-10-01

346

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Caribbean Basin Trade Initiative. 25.405 Section 25.405...SOCIOECONOMIC PROGRAMS FOREIGN ACQUISITION Trade Agreements 25.405 Caribbean Basin Trade Initiative. Under the Caribbean Basin...

2010-10-01

347

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Caribbean Basin Trade Initiative. 25.405 Section 25.405...SOCIOECONOMIC PROGRAMS FOREIGN ACQUISITION Trade Agreements 25.405 Caribbean Basin Trade Initiative. Under the Caribbean Basin...

2013-10-01

348

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Caribbean Basin Trade Initiative. 25.405 Section 25.405...SOCIOECONOMIC PROGRAMS FOREIGN ACQUISITION Trade Agreements 25.405 Caribbean Basin Trade Initiative. Under the Caribbean Basin...

2011-10-01

349

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Caribbean Basin Trade Initiative. 25.405 Section 25.405...SOCIOECONOMIC PROGRAMS FOREIGN ACQUISITION Trade Agreements 25.405 Caribbean Basin Trade Initiative. Under the Caribbean Basin...

2012-10-01

350

Basin-scale relations via conditioning  

USGS Publications Warehouse

A rainfall-runoff model is used in conjunction with a probabilistic description of the input to this model to obtain simple regression-like relations for basin runoff in terms of basin and storm characteristics. These relations, similar to those sought in regionalization studies, are computed by evaluating the conditional distribution of model output given basin and storm characteristics. This method of conditioning provides a general way of examining model sensitivity to various components of model input. The resulting relations may be expected to resemble corresponding relations obtained by regionalization using actual runoff to the extent that the rainfall-runoff model and the model input specification are physically realistic. The probabilistic description of model input is an extension of so-called "random-model" of channel networks and involves postulating an ensemble of basins and associated probability distributions that mimic the variability of basin characteristics seen in nature. Application is made to small basins in the State of Wyoming. Parameters of the input variable distribution are estimated using data from Wyoming, and basin-scale relations are estimated both, parametrically and nonparametrically using model-generated runoff from simulated basins. Resulting basin-scale relations involving annual flood quantiles are in reasonable agreement with those presented in a previous regionalization study, but error estimates are smaller than those in the previous study, an artifact of the simplicity of the rainfall-runoff model used in this paper. We also obtain relations for peak of the instantaneous unit hydrograph which agree fairly well with theoretical relations given in the literature. Finally, we explore the issues of sensitivity of basin-scale, relations and error estimates to parameterization of the model input probability distribution and of how this sensitivity is related to making inferences about a particular ungaged basin. ?? 1989 Springer-Verlag.

Troutman, B.M.; Karlinger, M.R.; Guertin, D.P.

1989-01-01

351

Delaware Basin Monitoring Annual Report  

SciTech Connect

The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. EPA requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard and must consider inadvertent drilling into the repository at some future time.

Washington Regulatory and Environmental Services; Washington TRU Solutions LLC

2001-09-28

352

K Basins Groundwater Monitoring Task, K Basins Closure Project: Report for October, November, and December 2006  

SciTech Connect

This report provides information on groundwater monitoring at the K Basins during October, November, and December 2006. Conditions remained very similar to those reported in the previous quarterly report, with no evidence in monitoring results to suggest groundwater impact from current loss of basin water to the ground. The K Basins monitoring network will be modified in the coming months as a consequence of new wells having been installed near KW Basin as part of a pump-and-treat system for chromium contamination, and new wells installed between the KE Basin and the river to augment long-term monitoring in that area.

Peterson, Robert E.

2007-03-22

353

Evidence for In-situ Cretaceous Volcanism From La Conception Quarry in the Noumea Basin, New Caledonia  

NASA Astrophysics Data System (ADS)

The Noumea Basin in New Caledonia, forms a narrow band, about 10-30km wide that extends from the city of Noumea north-westward towards La Tontouta for about 60km. The Noumea Basin represents a sequence of late Cretaceous basalts, rhyolites and marginal marine sedimentary typical of continental margin volcanic arcs. Directly north of the Tina Peninsula, in the Bay of La Conception, there is an old basalt quarry known as the La Conception Quarry. This project involved mapping La Conception quarry, which may be an extinct volcano. This is of particular importance as it is one of the only in-situ volcanic centers that exist in the South Pacific during the late Cretaceous. Through petrophraphic analyses of the basalts we determined that they have experienced minimal low-grade metamorphism, and that the temperatures and pressures never increased enough to re-orientate the phenocrysts. The quarry is roughly oval in shape, and is oriented north-south. The area of the exposed rock is roughly 0.5km2 and the quarry lake itself encompasses about of the exposed area. We mapped this site by using orientation of phenocrysts and vesicles to determine the direction of flow. We took measurements on the exposed rock every meter by setting up a square meter grid around the entire quarry. This was achieved by establishing a starting point, with a known GPS position, in the quarry and then having two groups of two people move directly north and south from that point. Compasses were used to orientate the lines of the grid; spray paint was used to mark the grid. According to the data we compiled, there are three different basaltic flows in La Conception quarry. These flows were discernable only on the west side of the quarry lake, and are stacked one on top of the other, forming a steep sided mound. On the east side of the quarry all orientations were random and there were no recognizable flows. Of the three flows we identified, the upper flow has random orientation of phenocrysts, the middle flow has a westward orientation, and the bottom is again random. Further work includes: electron microprobe and laser ablation mass spectrometry analyses to determine if there are chemical differences between the three flow units, and possibly then determine the chemical evolution of the magma chamber. If the La Conception quarry is an in-situ eruptive center, its existence supports the hypothesis that there was extensive subduction beneath the eastern Gondwana margin during the late Cretaceous and helps us to model the processes active during this phase of volcanism.

Rickey, C.; Alexander, A.; Grande, R.; Robinson, S.; Nicholson, K.

2009-05-01

354

Timing and Tectonic implications of basin inversion in the Nam Con Son Basin and adjacent areas, southern South China Sea  

E-print Network

The Nam Con Son (NCS) Basin, located offshore of SE Vietnam, is one of several Tertiary rift basins that formed during initial Eocene(?)-Oligocene rifting. Following cessation of rifting at the end of Oligocene time, these basins were subjected...

Olson, Christopher Charles

2001-01-01

355

Maceral composition and environment of deposition of Permian coals from the Parana Basin, Brazil  

Microsoft Academic Search

The petrographic composition of polished pellets,blocks and thin sections of the Bonito and Barro Branco coal beds from Santa Catarina State, Charqueadas coal bed from Rio Grande do Sul State and Rio de Peixe coal bed from Parana State, Brazil were studied. These Gondwana coals are characterized by high percentage of inertinite, mineral matter and the fine grained macerals--vitrodetrinite, liptodetrinite

W. A. Kneller; C. H. Wu

1985-01-01

356

Improving Flood Forecasting in International River Basins  

Microsoft Academic Search

In flood-prone international river basins (IRBs), many riparian nations that are located close to a basin's outlet face a major problem in effectively forecasting flooding because they are unable to assimilate in situ rainfall data in real time across geopolitical boundaries. NASA's proposed Global Precipitation Measurement (GPM) mission, which is expected to begin in 2010, will comprise high-resolution passive microwave

Faisal Hossain; Nitin Katiyar

2006-01-01

357

Basin wildrye: the forgotten grass revisited  

Technology Transfer Automated Retrieval System (TEKTRAN)

Basin wildrye was once a very abundant and widely occurring species throughout the landscapes of northern Nevada. When Captain Simpson, of the topographical Engineers, explored the route for a wagon road across the central Great Basin he marveled at the grass in the valley bottoms that reached to h...

358

Mackenzie - Liard Valley Hydrocarbon Basins, NWT  

Microsoft Academic Search

The Mackenzie - Liard area of the mainland Northwest Territories (NWT) is underlain by a series of superimposed sedimentary basins formed over the last billion years. Many of these basins have established hydrocarbon systems in which stacked reservoir rocks, trap seals and source rocks have been identified. The area includes the southern NWT where oil and gas pipelines are presently

James R. Taylor

359

GUNNISON BASIN CLIMATE CHANGE VULNERABILITY ASSESSMENT  

E-print Network

of climate change on land and water resources to help inform management and conservation activities Basin, Colorado, are likely to be most at risk to projected climatic changes and why they are likelyGUNNISON BASIN CLIMATE CHANGE VULNERABILITY ASSESSMENT For the Gunnison Climate Working Group

Neff, Jason

360

Relation between Tethys sea and Tarim basin  

SciTech Connect

The Tarim basin is the largest continental basin in China. It is known as the heart of central Asia. Still it was related to the Mediterranean Sea in the geological past. Based on the investigations of paleontology, stratigraphy, tectonics, and remote sensing, it is suggested that Tethys and the Tarim basin should be connected from the Late Cretaceous to Miocene. The northern branch of the Tethys sea channel began to pass through the Alay gap and invade the Tarim basin at the beginning of the Late Cretaceous. Up to the Miocene, marine invasion and marine regression must have happened six times in the western Tarim basin. The Paleocene marine invasion encroached upon the widest area and lasted the longest of the six times, which extended to the region of the southern Hotan River. The occurrence of the Paleocene marine fossils in the Kuqa Seg indicates the influence of the marine invasion. At the end of the Miocene, seawater receded fully from the Tarim basin. A Miocene petroleum field has been found in the Yecheng Seg of the western Tarim basin. According to the relationship between Tethys and the Tarim basin, the potentialities of the Late Cretaceous-Miocene hydrocarbon source are considered to be great.

Wei Junchao (Lanzhou Institute of Geology, Lanzhou (China))

1988-08-01

361

Amazon Basin: A System in Equilibrium  

Microsoft Academic Search

Despite the very active deforestation of the last decade, the Amazon Basin is still primarily covered with trees and is a system in equilibrium. The Andes form a barrier at the western end of the basin and, coupled with the prevailing easterly winds, ensure an almost unique precipitation and water-recycling regime. On average 50 percent of the precipitation is recycled,

Eneas Salati; Peter B. Vose

1984-01-01

362

Modelling conservation in the Amazon basin  

Microsoft Academic Search

Expansion of the cattle and soy industries in the Amazon basin has increased deforestation rates and will soon push all-weather highways into the region's core. In the face of this growing pressure, a comprehensive conservation strategy for the Amazon basin should protect its watersheds, the full range of species and ecosystem diversity, and the stability of regional climates. Here we

Britaldo Silveira Soares-Filho; Daniel Curtis Nepstad; Lisa M. Curran; Gustavo Coutinho Cerqueira; Ricardo Alexandrino Garcia; Claudia Azevedo Ramos; Eliane Voll; Alice McDonald; Paul Lefebvre; Peter Schlesinger

2006-01-01

363

Oil, gas accumulations in China's continental basins  

Microsoft Academic Search

China is well known for its continental deposits in Meso-Cenozoic basins, in which giant and medium-size oil and gas fields with various types of pools currently produce 100 million tons of oil annually. Focusing on the characteristics of oil and gas migration and accumulation and the formation conditions of giant oil fields in continental basins, this study suggests defining depression,

G. Zhai; W. Zhang; C. Hu

1982-01-01

364

European Immigration to America's Great Basin, 18501870  

Microsoft Academic Search

Nineteenth-century European immigrants bound for America's Great Basin evinced considerable variation in occupational mobility. White-collar and skilled workers frequently abandoned their European human capital to work in agriculture, and European planters remained farmers. Unskilled laborers who entered agriculture in the Great Basin, however, experienced substantial up-ward occupational mobility from their original economic status.

Scott Alan Carson

2004-01-01

365

A deep borehole in the Michigan Basin  

Microsoft Academic Search

Heat flow, in situ stress, in situ S wave and P wave velocities, and in situ density from borehole gravity were successfully measured in a 5.3-km-deep borehole in the Michigan basin. Precambrian (?) red beds and two altered basic igneous bodies were encountered beneath the known Cambrian succession of the basin. Petrological and paleomagnetic studies were undertaken on oriented samples

Norman H. Sleep; L. L. Sloss

1978-01-01

366

Gladden Pull-Apart Basin, offshore Belize  

Microsoft Academic Search

The junction of the American and Caribbean plates in Belize has created a complex structural setting for oil and gas exploration. Recent seismic offshore Belize has been used to identify three structural provinces, from west to east: a shallow thrust zone, a narrow upthrown wrench faulted zone and a deeper extensional basin, named the Gladden Pull-Apart Basin. Hydrocarbon leakage from

Morrice

1993-01-01

367

Devonian shale gas resource assessment, Illinois basin  

Microsoft Academic Search

In 1980 the National Petroleum Council published a resource appraisal for Devonian shales in the Appalachian, Michigan, and Illinois basins. Their Illinois basin estimate of 86 TCFG in-place has been widely cited but never verified nor revised. The NPC estimate was based on extremely limited canister off-gas data, used a highly simplified volumetric computation, and is not useful for targeting

R. M. Cluff; S. G. Cluff; C. M. Murphy

1996-01-01

368

Geology Fieldnotes: Great Basin National Park, Nevada  

NSDL National Science Digital Library

This Great Basin National Park site contains park geology information, park maps, visitor information, and teacher features (educational resources and links for teaching geology using National Park examples). The park geology section discusses the region's biogeography, glacial history, and the Lehman Caves. A park map and a features/relief map of the Great Basin National Park are included.

369

Water Atlas of the Volta Basin  

E-print Network

W A Water Atlas of the Volta Basin Atlas de l'eau du Bassin de la Volta Jacques LemoaLLe Devaraj de Condappa 2009 Challenge Program Water and Food Institut de Recherche pour le Développement Mise. Water atlas of the Volta Basin-Atlas de l'eau dans le bas- sin de la Volta. Challenge Program on Water

Boyer, Edmond

370

BASINS/HSPF WATERSHED MODEL TRAINING  

EPA Science Inventory

Basins is an interactive Windows based interface to several DOS based water quality computer simulations, of which HSPF is one. The training course helped train 30 water quality modelers from the USEPA, States and Tribes in the use of Basins and HSPF. The training was three da...

371

Subsidence of the Paris Basin  

NASA Astrophysics Data System (ADS)

We discuss the main results of a systematic quantitative analysis of the subsidence of the Paris basin made on 100 wells. Backstripping techniques with decompaction as well as sea level and water depth corrections are used to derive tectonic subsidence curves (in the absence of water and sediment loading) assuming local as well as regional compensation. A best fitting sea level variations curve is derived for the deepest central part on the basis of the resulting tectonic subsidence curve. The adopted amplitude of the regression since Upper Cretaceous is 330 m. The spatial and temporal distribution of tectonic subsidence is reconstructed and discussed. It is shown that rigidity of the lithosphere (with an adopted 50-km flexural parameter) plays a significant role. These results are then quantitatively interpreted in terms of the lithospheric stretching model. This interpretation is reasonable provided it is made in terms of volumetric subsidence over the whole basin, because of the thermal conduction and the rigidity low-pass filtering effects. The subsidence can be explained if the axial zone was thinned during Permo-Triassic by a factor of about 1.3 with respect to the adjacent lithosphere. It is shown that either the initial altitude was more than 500 m above sea level or the lower part of the lithosphere was lost at the beginning of the Permo-Triassic phase of extension, resulting in a rapid uplift of several hundreds of meters. The similarity of the Permo-Triassic initiating extensional phase with active continental rifting is shown.

Brunet, Marie-FrançOise; Le Pichon, Xavier

1982-10-01

372

Hydrological research basins and the environment  

NASA Astrophysics Data System (ADS)

The role and relative importance of experimental and representative basins in pre-dieting anthropogenic effects on water resources and the environment was the goal of the International Conference on Hydrological Research Basins and the Environment, held in Wageningen, the Netherlands, September 24-28, 1990. About 70 persons, almost exclusively from Europe, attended the meeting, which was organized by the Committee of the European Network of Experimental and Representative Basins and the National Committee of the Netherlands for the International Hydrological Program of Unesco.During the conference, the 3rd General Meeting of the European Network of Experimental and Representative Basins was held. This network of basins, covering nine countries in Europe, organizes periodic meetings and tries to enhance the compatibility of observations and methods of analysis, and to implement research projects of common interest.

Alley, V. M.; Warmerdam, P. M. M.

373

BASINS  

EPA Science Inventory

Resource Purpose: The U.S EPA's water programs and their counterparts in states and pollution control agencies are increasingly emphasizing watershed- and water quality-based assessment and integrated analysis of point and nonpoint sources. Better Assessment Science Integra...

374

Basin Width Control of Faulting and Structural Style  

NASA Astrophysics Data System (ADS)

A series of 5 balanced cross-sections across the Naryn Basin, Kyrgyzstan, reveals a transition in patterns of faulting. Each section is based on surface mapping of deformed basin-filling strata. Beginning in the 25-km-wide Eastern Naryn Basin, deformation within the basin is attributed to faults that are low-angle splays of the northern basin-bounding reverse fault. In 40-km-wide Western Naryn Basin, the pattern of deformation linked to the northern range front remains, but is accompanied by steeper faults that are both south and north dipping. These steeper faults in the west do not appear to be directly linked to the northern range-bounding fault, and likely penetrate the through the entire section of Cenozoic basin fill into the underlying Paleozoic limestone that forms the surrounding ranges. We compare these cross-sections to geodetic measurements of surface deformation. Synthetic aperture RADAR interferometry (InSAR) provides a measure of satellite line-of-sight range changes through time, a close approximation of vertical surface uplift rates. Profiles of deformation rates across the Naryn Basin reveal that in the west, surface deformation is distributed across the broad basin interior. In the east, uplift is concentrated at the northern basin margin of the narrower basin. From the geodetic and structural data, we infer that in the Western Naryn Basin, deformation has migrated away from the northern basin margin and into the interior. Deformation of the eastern basin interior, however, remains linked to the northern basin-bounding fault. These changes along the length of the basin are not accompanied by a consistent change in elevation of the basin-bounding range. Basin width may control basin deformation whereby formation of basin-interior faults in the narrow, eastern Naryn Basin is inhibited by the proximity of the basin-bounding ranges.

Goode, J. K.; Burbank, D. W.

2010-12-01

375

Metabolic principles of river basin organization  

PubMed Central

The metabolism of a river basin is defined as the set of processes through which the basin maintains its structure and responds to its environment. Green (or biotic) metabolism is measured via transpiration and blue (or abiotic) metabolism through runoff. A principle of equal metabolic rate per unit area throughout the basin structure is developed and tested in a river basin characterized by large heterogeneities in precipitation, vegetation, soil, and geomorphology. This principle is suggested to have profound implications for the spatial organization of river basin hydrologic dynamics, including the minimization of energy expenditure known to control the scale-invariant characteristics of river networks over several orders of magnitude. Empirically derived, remarkably constant rates of average transpiration per unit area through the basin structure lead to a power law for the probability distribution of transpiration from a randomly chosen subbasin. The average runoff per unit area, evaluated for subbasins of a wide range of topological magnitudes, is also shown to be remarkably constant independently of size. A similar result is found for the rainfall after accounting for canopy interception. Allometric scaling of metabolic rates with size, variously addressed in the biological literature and network theory under the label of Kleiber’s law, is similarly derived. The empirical evidence suggests that river basin metabolic activity is linked with the spatial organization that takes place around the drainage network and therefore with the mechanisms responsible for the fractal geometry of the network, suggesting a new coevolutionary framework for biological, geomorphological, and hydrologic dynamics. PMID:21670259

Rodriguez-Iturbe, Ignacio; Caylor, Kelly K.; Rinaldo, Andrea

2011-01-01

376

Metabolic principles of river basin organization.  

PubMed

The metabolism of a river basin is defined as the set of processes through which the basin maintains its structure and responds to its environment. Green (or biotic) metabolism is measured via transpiration and blue (or abiotic) metabolism through runoff. A principle of equal metabolic rate per unit area throughout the basin structure is developed and tested in a river basin characterized by large heterogeneities in precipitation, vegetation, soil, and geomorphology. This principle is suggested to have profound implications for the spatial organization of river basin hydrologic dynamics, including the minimization of energy expenditure known to control the scale-invariant characteristics of river networks over several orders of magnitude. Empirically derived, remarkably constant rates of average transpiration per unit area through the basin structure lead to a power law for the probability distribution of transpiration from a randomly chosen subbasin. The average runoff per unit area, evaluated for subbasins of a wide range of topological magnitudes, is also shown to be remarkably constant independently of size. A similar result is found for the rainfall after accounting for canopy interception. Allometric scaling of metabolic rates with size, variously addressed in the biological literature and network theory under the label of Kleiber's law, is similarly derived. The empirical evidence suggests that river basin metabolic activity is linked with the spatial organization that takes place around the drainage network and therefore with the mechanisms responsible for the fractal geometry of the network, suggesting a new coevolutionary framework for biological, geomorphological, and hydrologic dynamics. PMID:21670259

Rodriguez-Iturbe, Ignacio; Caylor, Kelly K; Rinaldo, Andrea

2011-07-19

377

Delaware Basin Monitoring Annual Report  

SciTech Connect

The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. The EPA environmental standards for the management and disposal of transuranic (TRU) radioactive waste are codified in 40 CFR Part 191 (EPA 1993). Subparts B and C of the standard address the disposal of radioactive waste. The standard requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard. This assessment must include the consideration of inadvertent drilling into the repository at some future time.

Washington Regulatory and Environmental Services; Washington TRU Solutions LLC

2005-09-30

378

Delaware Basin Monitoring Annual Report  

SciTech Connect

The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. The EPA environmental standards for the management and disposal of transuranic (TRU) radioactive waste are codified in 40 CFR Part 191 (EPA 1993). Subparts B and C of the standard address the disposal of radioactive waste. The standard requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard. This assessment must include the consideration of inadvertent drilling into the repository at some future time.

Washington Regulatory and Environmental Services; Washington TRU Solutions LLC

2003-09-30

379

Delaware Basin Monitoring Annual Report  

SciTech Connect

The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. The EPA environmental standards for the management and disposal of transuranic (TRU) radioactive waste are codified in 40 CFR Part 191 (EPA 1993). Subparts B and C of the standard address the disposal of radioactive waste. The standard requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard. This assessment must include the consideration of inadvertent drilling into the repository at some future time.

Washington Regulatory and Environmental Services

1999-09-30

380

Delaware Basin Monitoring Annual Report  

SciTech Connect

The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. The EPA environmental standards for the management and disposal of transuranic (TRU) radioactive waste are codified in 40 CFR Part 191 (EPA 1993). Subparts B and C of the standard address the disposal of radioactive waste. The standard requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard. This assessment must include the consideration of inadvertent drilling into the repository at some future time.

Washington Regulatory and Environmental Services; Washington TRU Solutions LLC

2004-09-30

381

Delaware Basin Monitoring Annual Report  

SciTech Connect

The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. The EPA environmental standards for the management and disposal of transuranic (TRU) radioactive waste are codified in 40 CFR Part 191 (EPA 1993). Subparts B and C of the standard address the disposal of radioactive waste. The standard requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard. This assessment must include the consideration of inadvertent drilling into the repository at some future time.

Washington Regulatory and Environmental Services; Washington TRU Solutions LLC

2002-09-21

382

Delaware Basin Monitoring Annual Report  

SciTech Connect

The Delaware Basin Drilling Surveillance Program (DBDSP) is designed to monitor drilling activities in the vicinity of the Waste Isolation Pilot Plant (WIPP). This program is based on Environmental Protection Agency (EPA) requirements. The EPA environmental standards for the management and disposal of transuranic (TRU) radioactive waste are codified in 40 CFR Part 191 (EPA 1993). Subparts B and C of the standard address the disposal of radioactive waste. The standard requires the Department of Energy (DOE) to demonstrate the expected performance of the disposal system using a probabilistic risk assessment or performance assessment (PA). This PA must show that the expected repository performance will not release radioactive material above limits set by the EPA's standard. This assessment must include the consideration of inadvertent drilling into the repository at some future time.

Washington Regulatory and Environmental Services; Washington TRU Solutions LLC

2000-09-28

383

Thermal conditions in the Anadarko basin, Oklahoma  

SciTech Connect

Heat flow, bottom-hole temperature (BHT), and thermal conductivity data are used to evaluate the present thermal conditions in the Anadarko basin. Heat flow values decrease from 54-62 mWm{sup {minus}2} in the northern part of the basin to 39-53 mWm{sup {minus}2} in the southern portion of the basin. The variation in the regional conductive heat flow is controlled by basin geometry and by the distribution of radiogenic elements in the basement. The heat flow, thermal conductivity, and lithologic information were combined to construct a 3-D model of the temperature structure of the Anadarko basin. The highest temperatures sedimentary rocks older than Pennsylvanian are offset 35 km north-northwest of the deepest part of the basin. This offset is related to the regional increase in heat flow to the north and to the presence of high thermal conductivity granite wash adjacent to the Wichita Mountains. A plot of the temperature difference between the equilibrium temperatures estimated from the model and the measured BHTs as a function of depth is remarkably similar to the published correction curve for BHTs for wells in Oklahoma. Vitrinite reflectance and apatite fission-track (FT) data are used to estimate the paleogeothermal conditions in the basin. Published vitrinite reflectance values are consistent with a past geographic temperature distribution comparable to the observed distribution with the maximum values offset from the basin axis. FT analysis of sandstones from wells in the southeastern portion of the basin indicates that subsurface temperatures were at least 30C higher than at present, suggest the possibility of substantial erosion in this area.

Kelley, S.A.; Gallardo, J.D.; Carter, L.C.; Blackwell, D.D. (Southern Methodist Univ., Dallas, TX (United States))

1991-03-01

384

Tectono-stratigraphic evolution of an inverted extensional basin: the Cameros Basin (north of Spain)  

NASA Astrophysics Data System (ADS)

The Cameros Basin is a part of the Mesozoic Iberian Rift. It is an extensional basin formed during the late Jurassic and early Cretaceous, in the Mesozoic Iberian Rift context, and it was inverted in the Cenozoic as a result of the Alpine contraction. This work aims to reconstruct the tectono-stratigraphic evolution of the basin during the Mesozoic, using new and revised field, geophysical and subsurface data. The construction of a basin-wide balanced section with partial restorations herein offers new insights into the geometry of the syn-rift deposits. Field data, seismic lines and oil well data were used to identify the main structures of the basin and the basin-forming mechanisms. Mapping and cross-sectional data indicate the marked thickness variation of the depositional sequences across the basin, suggesting that the extension of the depositional area varied during the syn-rift stage and that the depocentres migrated towards the north. From field observation and seismic line interpretation, an onlap of the depositional sequences to the north, over the marine Jurassic substratum, can be deduced. In the last few decades, the structure and geometry of the basin have been strongly debated. The structure and geometry of the basin infill reconstructed herein strongly support the interpretation of the Cameros Basin as an extensional-ramp synclinal basin formed on a blind south-dipping extensional ramp. The gradual hanging-wall displacement to the south shifted the depocentres to the north over time, thus increasing the basin in size northwards, with onlap geometry on the pre-rift substratum. The basin was inverted by means of a main thrust located in a detachment located in the Upper Triassic beds (Keuper), which branched in depth with the Mesozoic extensional fault flat. The reconstruction of the tectono-stratigraphic evolution of the Cameros Basin proposed herein represents a synthesis and an integration of previous studies of the structure and geometry of the basin. This study can be used as the basis for future basin-scale research and for modelling the ancient petroleum system of the basin.

Omodeo Salè, Silvia; Guimerà, Joan; Mas, Ramón; Arribas, José

2014-09-01

385

Highly Complicated Basins of Periodic Attractors in Coupled Chaotic Maps  

NASA Astrophysics Data System (ADS)

The basin structure of the coupled logistic maps is considered. It is found that a synchronous periodic attractor coexists with other periodic attractors in several regions of the parameter space. These periodic attractors have highly complicated basins which are similar to riddled basins. Basins of a roulette is also discussed.

Inoue, M.; Nishi, Y.

1996-03-01

386

YARD NO. 3 BASINS (GRAVING DOCKS), VIEW TO EASTNORTHEAST AT ...  

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

YARD NO. 3 BASINS (GRAVING DOCKS), VIEW TO EAST-NORTHEAST AT THE SOUTH END OF THE CRANEWAY AND GALLERY BETWEEN BASINS NO. 1 AND 2, LOOKING ACROSS SOUTH END OF BASIN NO. 1 (THE WESTERN-MOST BASIN) - Rosie the Riveter National Historical Park, Graving Docks, Shipyard No. 3, Richmond, Contra Costa County, CA

387

American River Watershed, Common Features Project Natomas Basin, CA  

E-print Network

American River Watershed, Common Features Project Natomas Basin, CA 27 September 2010 Abstract Basin in the City of Sacramento. Located in Sacramento and Sutter Counties, the Natomas Basin is home and stability issues could cause a catastrophic failure of the levee system around the Natomas Basin, resulting

US Army Corps of Engineers

388

The Basin and Range Province 7.1. Introduction  

E-print Network

Chapter 7 The Basin and Range Province T. Parsons 7.1. Introduction The Basin and Range province-1). Seismicity, high heat flow, and recent basaltic vol- canism indicate that the Basin and Range province- sional block-faulting that left the characteristic pat- tern of alternating basins and ranges across

389

BULL MOUNTAIN BASIN, MONTANA By G.D. Stricker  

E-print Network

Chapter SM BULL MOUNTAIN BASIN, MONTANA By G.D. Stricker in U.S. Geological Survey Professional................................................................................................SM-7 Figures SM-1. Location of the Bull Mountain Basin, south-central Montana. Bull Mountain Basin Basin, southeastern Montana (modified from Woolsey and others, 1917; Connor, 1989). SM-3. Coal

390

Structural and depositional history, Jefferson and Madison basins, southwestern Montana  

Microsoft Academic Search

Recent seismic and gravity data from the Cenozoic Jefferson and Madison basins provide new information concerning their structural and depositional histories. Both basins are north-south elongated structural basins formed as a result of horizontal extension after Laramide horizontal thrusting. Gravity data show that each basin in the subsurface is asymmetric with a large steep west-dipping fault on the east flank,

D. L. Rasmussen; R. W. Fields

1983-01-01

391

Native American Salt Basins in the Sierra Nevada  

USGS Multimedia Gallery

Native Americans of the Miwok tribe in the northern Sierra Nevada, California carved these basins into the granite bedrock to produce salt for trade. They filled the basins with water from a salt spring and let the water evaporate, leaving a salt residue in the basin. The basins are about a meter in...

392

Native American Salt Basins in the Sierra Nevada  

USGS Multimedia Gallery

Native Americans of the Miwok tribe in the northern Sierra Nevada, California carved these basins into the granite bedrock to produce salt for trade. They filled the basins with water from a salt spring and let the water evaporate, leaving a salt residue in the basin. The basins are approximately on...

393

Chapter 4 The Appalachian Foreland Basin in Eastern United States  

Microsoft Academic Search

The Appalachian Basin is a composite, retroarc foreland basin that in many ways is the “type” foreland basin and the “type area” for the Wilson cycle. Our understanding of the basin, and others like it worldwide, is largely the legacy of a single observation by James Hall in 1857, an observation that also effectively established the framework for the later

Frank R. Ettensohn

2008-01-01

394

K Basins isolation barriers summary report  

SciTech Connect

The 105-K East and 105-K West fuel storage basins (105-K Basins) were designed and constructed in the early 1950`s for interim storage of irradiated fuel following its discharge from the reactors. The 105-K- East and 105-K West reactor buildings were constructed first, and the associated storage basins were added about a year later. The construction joint between each reactor building structure and the basin structure included a flexible membrane waterstop to prevent leakage. Water in the storage basins provided both radiation shielding and cooling to remove decay heat from stored fuel until its transfer to the Plutonium Uranium Extraction (PUREX) Facility for chemical processing. The 105-K West Reactor was permanently shut down in February 1970; the 105-K East Reactor was permanently shut down in February 1971. Except for a few loose pieces, fuel stored in the basins at that time was shipped to the PUREX Facility for processing. The basins were then left idle but were kept filled with water. The PUREX Facility was shut down and placed on wet standby in 1972 while N Reactor continued to operate. When the N Reactor fuel storage basin began to approach storage capacity, the decision was made to modify the fuel storage basins at 105-K East and 105-K West to provide additional storage capacity. Both basins were subsequently modified (105-K East in 1975 and 105-K West in 1981) to provide for the interim handling and storage of irradiated N Reactor fuel. The PUREX Facility was restarted in November 1983 to provide 1698 additional weapons-grade plutonium for the United States defense mission. The facility was shut down and deactivated in December 1992 when the U.S. Department of Energy (DOE) determined that the plant was no longer needed to support weapons-grade plutonium production. When the PUREX Facility was shut down, approximately 2.1 x 1 06 kg (2,100 metric tons) of irradiated fuel aged 7 to 23 years was left in storage in the 105-K Basins pending a decision on final disposition of the material. The Hanford Federal Facility Agreement and Consent Order (Ecology et al. 1994), also known as the Tri-Party Agreement, commits to the removal of all fuel and sludge from the 105-K Basins by the year 2002.

Strickland, G.C., Westinghouse Hanford

1996-07-31

395

Raditladi and Rachmaninoff basins: Numerical Modelling  

NASA Astrophysics Data System (ADS)

Mercury hosts the largest population of peak-ring basins among all the rocky planets and satellites of the Solar System. Among the database of such structures, we take into analysis two recently imaged peak-ring basins, Raditladi and Rachmaninoff, both located in the northern hemisphere and about 300 km in diameter. In this work, we present the numerical simulations carried out through the iSALE shock code, along with the comparison with observations, in order to shed light on the primary impactor source of these basins.

Martellato, E.; Benkhoff, J.; Cremonese, G.; Foing, B.; Massironi, M.; Oberst, J.; Preusker, F.

2012-09-01

396