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1

Palaeobotany of Gondwana basins of Orissa State, India: A bird's eye view  

Microsoft Academic Search

Gondwana basins of Orissa State constitute a major part of the Mahanadi Master Basin. These Gondwana sediments, ranging from Asselian to Albian in age, contain remnants of three basic floral assemblages i.e. Glossopteris Assemblage, Dicroidium Assemblage and Ptilophyllum Assemblage which can be recognized through the Permian, Triassic and Early Cretaceous, respectively. The megafloral assemblages of different basins of this state

Shreerup Goswami; Kamal Jeet Singh; Shaila Chandra

2006-01-01

2

Simulation-Optimization Modelling for Sustainable Groundwater Management in a Coastal Basin of Orissa, India  

Microsoft Academic Search

The Balasore coastal groundwater basin of Orissa in eastern India is under a serious threat of overdraft and seawater intrusion.\\u000a Two optimization models were developed in this study for the efficient utilization of water resources in Balasore basin during\\u000a non-monsoon periods: (a) a non-linear hydraulic management model for optimal pumpage, and (b) a linear optimization model\\u000a for optimal cropping pattern

R. Rejani; Madan K. Jha; Sudhindra N. Panda

2009-01-01

3

Pattern of sedimentation during the Late Paleozoic, Gondwanaland glaciation: An example from the Talchir Formation, Satpura Gondwana basin, central India  

Microsoft Academic Search

The Talchir Formation of Permian age is the lowermost lithostratigraphic unit of the Indian Gondwana successions preserving a record of the Late Paleozoic glaciation that affected the whole Gondwanaland. The formation unconformably overlies the Precambrian basement in all the Gondwana basins of India, and marks initiation of sedimentation after a long hiatus since the Pro- terozoic. The Talchir Formation of

Chandan Chakraborty; Sanjoy Kumar Ghosh

2008-01-01

4

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

5

An Interpretation of the Seafloor Spreading History of the West Enderby Basin between Initial Breakup of Gondwana and Anomaly C34  

Microsoft Academic Search

The seafloor spreading evolution in the Southern Indian Ocean is key to understanding the initial breakup of Gondwana. We summarize the structural lineaments deduced from the GEOSAT 10?Hz sampled raw altimetry data as well as satellite derived gravity anomaly map and the magnetic anomaly lineation trends from vector magnetic anomalies in the West Enderby Basin, the Southern Indian Ocean. The

Yoshifumi Nogi; Kumiko Nishi; Nobukazu Seama; Yoichi Fukuda

2004-01-01

6

Fluvial architecture of Early Permian Barakar rocks of Korba Gondwana basin, eastern-central India  

NASA Astrophysics Data System (ADS)

The Early Permian Barakar Formation of the Korba basin represents repeated deposition of fining upward sequences of coarse to medium grained sandstone, fine grained sandstone-shale, shale and coal. The sandstones are channel, sheet like, multistory, and profusely cross-bedded. The shale beds are lens as well sheet like and laminated; coal facies is thin to moderately thick and shows splitting. Paleocurrent analysis suggests a northwesterly paleoslope during Barakar sedimentation. However, the deflection of paleoslope towards northeast in the eastern part of the basin supports the existence of a watershed in the depositional area. The Barakar paleochannel were 4.05 m deep and 176 m wide (single channel) with an average sinuosity of 1.27. The average flow velocity and sediment load during flood stage are in the order of 1.77 m/s and 4.15. These results indicate bed-load (braided) to mixed load nature of the Barakar streams of the Korba basin. The study suggests that the Early Permian braided Barakar streams deposited the coal measure sequence subsequent to deglaciation in a northwesterly slopping paleovalley. The basin floor was highly uneven marked by the presence of a basement high in the northwestern part that bifurcates the paleostreams into northwestern and northeastern branches.

Tewari, Ram Chandra; Hota, Rabindra Nath; Maejima, Wataru

2012-06-01

7

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

8

The age of the Tunas formation in the Sauce Grande basin-Ventana foldbelt (Argentina): Implications for the Permian evolution of the southwestern margin of Gondwana  

NASA Astrophysics Data System (ADS)

New SHRIMP radiogenic isotope dating on zircons in tuffs (280.8 ± 1.9 Ma) confirms the Early Permian (Artinskian) age of the uppermost section of the Tunas Formation. Tuff-rich levels in the Tunas Formation are exposed in the Ventana foldbelt of central Argentina; they are part of a deltaic to fluvial section corresponding to the late overfilled stage of the Late Paleozoic Sauce Grande foreland basin. Recent SHRIMP dating of zircons from the basal Choiyoi volcanics exposed in western Argentina yielded an age of 281.4 ± 2.5 Ma (Rocha-Campos et al., 2011). The new data for the Tunas tuffs suggest that the volcanism present in the Sauce Grande basin can be considered as the distal equivalent of the earliest episodes of the Choiyoi volcanism of western Argentina. From the palaeoclimatic viewpoint the new Tunas SHRIMP age confirms that by early Artinskian glacial conditions ceased in the Sauce Grande basin and, probably, in adajacent basins in western Gondwana.

López-Gamundí, Oscar; Fildani, Andrea; Weislogel, Amy; Rossello, Eduardo

2013-08-01

9

Sedimentological characteristics and depositional environment of Upper Gondwana rocks in the Chintalapudi sub-basin of the Godavari valley, Andhra Pradesh, India  

NASA Astrophysics Data System (ADS)

The Kota (Early to Middle Jurassic) and Gangapur (Early Cretaceous) rocks of the Chintalapudi sub-basin of Gondwana are poorly to very poorly sorted, positively to very positively skewed, and leptokurtic to very leptokurtic. The Kota rocks show a single prominent truncation line at the inflection of saltation/suspension at 2.0 ? of the river mode of transportation. The Gangapur rocks show two truncation lines of saltation/suspension, one at 0.5-1.7 ? and the other at 2.4-4.0 ?. These are inferred to be due to a high turbulent phase of the river. On the multigroup multivariant discriminant functions V1- V2 diagram, the bulk of the samples from Kota and Gangapur fall in the field of turbidite deposition. This study supports the view that the discrimination of river from turbidite deposits on this diagram is poor since both deposits are identical in terms of settling velocity distribution. On the C- M diagram, the Kota and Gangapur rocks show segments of rolling, bottom suspension, and graded suspension during river transport of sediment. The Q-R segments of graded suspension for these rocks have a C/ M ratio of 2.5, which is close to the ratio of the turbidites. The Kota and Gangapur rocks have nearly the same assemblage of heavy minerals. The provenance is inferred to consist of basic igneous rocks, acid igneous rocks, high-grade metamorphic rocks and sedimentary rocks.

Ramamohanarao, T.; Sairam, K.; Venkateswararao, Y.; Nagamalleswararao, B.; Viswanath, K.

2003-03-01

10

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

11

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

12

Sickle cell disease in Orissa State, India.  

PubMed

A study of 131 patients with homozygous sickle cell (SS) disease in Orissa State, India, indicated that, compared with Jamaican patients, Indian patients have higher frequencies of alpha thalassaemia, higher fetal haemoglobin, total haemoglobin, and red cell counts, and lower mean cell volume, mean cell haemoglobin concentration, and reticulocyte counts. Indian patients have a greater frequency and later peak incidence of splenomegaly, and hypersplenism is common. Painful crises and dactylitis are not uncommon in Indian patients but chronic leg ulceration is rare. Homozygous sickle cell disease in Orissa is similar to that in the Eastern Province of Saudi Arabia and is very different from that in populations of West African origin. PMID:2430154

Kar, B C; Satapathy, R K; Kulozik, A E; Kulozik, M; Sirr, S; Serjeant, B E; Serjeant, G R

1986-11-22

13

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

14

Mitigation of Flooding and Cyclone Hazard in Orissa, India  

Microsoft Academic Search

Storm surges generated by the strong tangential wind stressesand normal atmospheric pressure gradients at the sea surface due to tropical cyclones (TC'S)have been studied with the goal of detecting any significant and systematic changes due to climatechange. Cyclone and storm surge data for the 19th and 20th centuries for the Bay of Bengalcoast of the state of Orissa in India

P. Chittibabu; S. K. Dube; J. B. Macnabb; T. S. Murty; A. D. Rao; U. C. Mohanty; P. C. Sinha

2004-01-01

15

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

16

Environmental health impact assessment of National Aluminum Company, Orissa  

PubMed Central

Environmental Health Impact Assessment of industries is an important tool help decision-makers make choices about alternatives and improvements to prevent disease/injury and to actively promote health around industrial sites. A rapid environmental health hazard and vulnerability assessment of National Aluminum Company was undertaken in the villages in the vicinity plant in Angul region of Orissa. Aluminum smelter plant was known to discharge hundreds of tones of fluoride in to the environment contaminating the ecosystem around the plant. The present Environmental health impact assessment was carried out in 2005-06 at the request of officials from Government of Orissa. The findings showed adverse effects on human, veterinary and ecological health. Human health effects manifestations included dental and skeletal fluorosis. Veternary health effects were manifested through skeletal fluorosis. Ecological adverse effects were manifested by damage to paddy fields and crop yield. PMID:22223954

Patil, Rajan R.

2011-01-01

17

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

18

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

19

Baltica and Siberia Inverted: A New Late Proterozoic Reconstruction Linking The Opening of The Iapetus Ocean and The Ægir Sea To The Peri-gondwana Events.  

NASA Astrophysics Data System (ADS)

Using published paleomagnetic data we propose a reassessment of the classic Wil- son Cycle paleoreconstruction depicting an Atlantic-type early Paleozoic (Iapetus) ocean between western Norway and East Greenland, suggesting that Baltica was ge- ographically inverted throughout the Neoproterozoic (peri-Urals juxtaposed to East Greenland) and that Siberia was inverted and positioned directly east of Baltica. Compared to previous models the new reconstruction presents more plausible geo- logic correlations of basement regions, ophiolites, stratigraphy and detrital zircons in sedimentary basins and tectonic events between Baltica, Laurentia, Gondwana and Siberia and a number of smaller terranes. The reconstruction furthermore dismisses the need for a near-instant 180o rotation of Baltica between Vendian breakup of non- inverted Baltica and Laurentia and the nearly synchronous Timanian collision of in- verted Baltica (in Northern Norway, Timan and Pechora) and peri-Gondwana terranes (Avalonia, Florida and Cadomia). In our reconstruction, the breakup that led to the for- mation of the Iapetus Ocean was initiated at a triple-junction between a rift (Laurentia- Gondwana), a right-lateral fault (Laurentia-Baltica), and a trench (Baltica-Gondwana), thereby linking the Late Precambrian Iapetus opening to the Timanian and Avalonian orogenies between Gondwana and an inverted Baltica. We propose that these events are intimately linked to rifting of the Ægir Sea between inverted Baltica and inverted Siberia and the Vendian Mid Baltic failed rift (the Moscov-Mesen Basin).

Hartz, E. H.; Torsvik, T. H.

20

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

21

New data refine the travels of Gondwana  

NASA Astrophysics Data System (ADS)

The supercontinent Pangea, which existed roughly 300-200 million years ago as the only landmass on Earth, plays a special role in the history of geophysics. The geological, biological, and paleontological similarities between now distant shores—once connected in Pangea—gave the first evidence for the theory of continental drift. That Pangea came apart to form the modern world is well established, but exactly how, when, and where the individual plates moved are still up for debate. Drawing on new high-quality paleomagnetic data, Domeier et al. describe the movements of Gondwana that, until its separation from Laurasia 200 million years ago, formed the southern half of Pangea. The authors collected samples drawn from the Sierra Chica, a band of ancient volcanic rocks in central Argentina. Within the samples the magnetic minerals hematite and titanomagnetite were used to calculate the geographic location of the magnetic pole 263 million years ago. Because the Earth's magnetic poles drift only slightly over time and have well-known reversal episodes, deviations in the location of the calculated pole (paleopole) from the present location are an indication that the plate underlying the volcanic rock has moved since the lava solidified. Changes in the paleopole drawn from samples of different ages from the same plate give a map for the plate's movement. (Geochemistry, Geophysics, Geosystems, doi:10.1029/2011GC003616, 2011)

Schultz, Colin

2011-09-01

22

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

23

Can Mangroves Minimize Property Loss during Big Storms? An Analysis of House Damage due to the Super Cyclone in Orissa  

Microsoft Academic Search

This paper estimates the storm protection benefits due to mangroves during the super cyclone of 1999 in Orissa. By combining GIS data with census information, the paper examines the mangrove mediated effects on residential property in the Kendrapada district of Orissa.

Saudamini Das

2010-01-01

24

Effect of the Mahanadi River on the Development of Storm Surge Along the Orissa Coast of India: A Numerical Study  

Microsoft Academic Search

River-ocean coupled models are described for the evaluation of the interaction between river discharge and surge development along the Orissa coast of India. The models are used to study the effect of fresh water discharge from the Mahanadi River on the surge response along the Orissa coast due to the October 1999 super cyclone which led to severe flooding of

S. K. Dube; P. C. Sinha; A. D. Rao; Indu Jain; Neetu Agnihotri

2005-01-01

25

Upper Permian fluviolacustrine deposits of southern Africa and the late Permian climate southern Gondwana  

SciTech Connect

Upper Permian-age fluviolacustrine deposits are widespread throughout southern Africa. In the southern part of the subcontinent, where deposition took place in foreland basin settings, the sequences are thicker and fluvial-dominated whereas, lacustrine-dominated deposits accumulated in settings of low relief, broad warping and mild faulting at the northern end. The geographic extent and lateral correlatability of these deposits suggest the existence of concurrent, perhaps interconnected, giant lakes within major fluvial frameworks throughout the subcontinent, thousands of miles inland from the sea. This period of major lake development within fluvial depositional settings suggests climatic conditions that sustained a uniquely wet continental environment, deep in the heart of the Gondwanan supercontinent. Simulations based on various general circulation and energy balance climate models predict extreme seasonal temperatures and aridity for Gondwana at the palaeolatitudes of southern Africa during the Late Permian. On the other hand, distribution of climate-sensitive rocks, palynologic and palaeobotanic data and vertebrate fossils, coroborate the temperature climate documented by sedimentologic studies. The erroneous modeling results may have arisen from the fact that the models do not employ palaeogeographies that accommodate the existence of the vast lakes and rivers of Gondwana. The Late Permian palaeogeography of series of giant lakes within major fluvial frameworks would have had considerable influences on the regional climate. This suggests that it is imperative that numerical modeling studies incorporate accurate palaeogeographies, constructed based on available geological data, in order to recreate past climates with acceptable degree of accuracy.

Yemane, K. (Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Geology Bryn Mawr Coll., PA (United States). Dept. of Geology)

1993-03-01

26

Models for evolution of Weddell basin  

Microsoft Academic Search

The evolution of the Weddell basin constitutes the keystone for Gondwana reconstructions. During the last decade major exploration efforts including marine and aerogeophysical surveys and OPD drilling have been directed toward the evolution of the Weddell sector. As a result of these efforts, they can now show that the Weddell basin formed as the result of the relative motion between

Labrecque

1987-01-01

27

Biogeography of the Monimiaceae (Laurales): a role for East Gondwana  

E-print Network

Caledonia, New Zealand, and across the Indian Ocean to Madagascar and the Mascarenes. The endemic genus Hemisphere, with fossils in East and West Gondwana. Methods We use phylogenetic analysis of DNA sequences clock model with fossil prior constraints to estimate species relationships and divergence times

Renner, Susanne

28

Hardship financing of healthcare among rural poor in Orissa, India  

PubMed Central

Background This study examines health-related "hardship financing" in order to get better insights on how poor households finance their out-of-pocket healthcare costs. We define hardship financing as having to borrow money with interest or to sell assets to pay out-of-pocket healthcare costs. Methods Using survey data of 5,383 low-income households in Orissa, one of the poorest states of India, we investigate factors influencing the risk of hardship financing with the use of a logistic regression. Results Overall, about 25% of the households (that had any healthcare cost) reported hardship financing during the year preceding the survey. Among households that experienced a hospitalization, this percentage was nearly 40%, but even among households with outpatient or maternity-related care around 25% experienced hardship financing. Hardship financing is explained not merely by the wealth of the household (measured by assets) or how much is spent out-of-pocket on healthcare costs, but also by when the payment occurs, its frequency and its duration (e.g. more severe in cases of chronic illnesses). The location where a household resides remains a major predictor of the likelihood to have hardship financing despite all other household features included in the model. Conclusions Rural poor households are subjected to considerable and protracted financial hardship due to the indirect and longer-term deleterious effects of how they cope with out-of-pocket healthcare costs. The social network that households can access influences exposure to hardship financing. Our findings point to the need to develop a policy solution that would limit that exposure both in quantum and in time. We therefore conclude that policy interventions aiming to ensure health-related financial protection would have to demonstrate that they have reduced the frequency and the volume of hardship financing. PMID:22284934

2012-01-01

29

Mangroves - A Natural Defense against Cyclones: An investigation from Orissa, India  

Microsoft Academic Search

Following this disaster in Orissa caused by a super cyclone there was a great deal of controversy over whether the high levels of mangrove forest destruction in the area had increased the impact of the cyclone. Many argued that the loss of human life caused by the storm was directly linked to the removal of the natural defenses provided by

Saudamini Das

2007-01-01

30

Social citizenship and ethnicity around a public sector steel plant in Orissa, India  

Microsoft Academic Search

This article is about a modern public sector steel plant in the state of Orissa and its promise to set standards for post-colonial India's citizenry at large. These steel plants were to provide their workforces with superior social and economic citizenship rights, which in turn were to serve as exemplary industrial relations for the industrialising nation. The steel plants were

Christian Strümpell

2011-01-01

31

An Ethno-Medico-Botanical Study of Bolangir, Orissa, India: Native Plant Remedies Against Gynaecological Diseases  

Microsoft Academic Search

The present paper enumerates 33 plant species belonging to 24 families used by the tribal of Bolangir District of Orissa for the cure of Gynaecological diseases. Tribal generally collect these plants from the nearby forest and prepare the medicine under the guidance of vaidya or village medicine man in a traditional way. These medicinal plants are becoming extinct day by

S. P. Mohapatra; H. P. Sahoo

2008-01-01

32

The Karoo basins of south-central Africa  

Microsoft Academic Search

The Karoo basins of south-central Africa evolved during the first-order cycle of supercontinent assembly and breakup of Pangea, under the influence of two distinct tectonic regimes sourced from the southern and northern margins of Gondwana. The southern tectonic regime was related to processes of subduction and orogenesis along the Panthalassan (palaeo-Pacific) margin of Gondwana, which resulted in the formation of

O. Catuneanu; H. Wopfner; P. G. Eriksson; B. Cairncross; B. S. Rubidge; R. M. H. Smith; P. J. Hancox

2005-01-01

33

Piecing Together the Eastern Australian Margin in Gondwana: Origin of Metamorphic Rocks in the Woodlark Rift, SE Papua New Guinea  

NASA Astrophysics Data System (ADS)

Fragments of the former Australian continental margin in East Gondwana occur as submarine plateaus and rises in the southwestern Pacific. This study examined the isotopic composition and zircon age populations in the low and high grade metamorphic rocks along the southern margin of the active Woodlark Basin to evaluate whether these rocks were derived from continental crust, either as detritus or as a fragment since rifted off of northeastern Australia. In the Woodlark Basin of southeastern Papua New Guinea, metamorphic grade decreases eastward from HP/UHP in the D’Entrecasteaux Islands within the western part of the basin to subgreenschist facies in the Louisiade Archipelago, on the southern rifted margin. The ~45 islands comprising the Louisiade Archipelago are distributed over >160 km with some islands reaching 100’s of km 2 in size and elevations up to 850 m asl. The metapelitic Calvados Schist is the dominant rock unit in the Louisiade Archipelago, yet none of the islands are in proximity to a source of terrigeneous sediments that are the likely protoliths of the schist. The provenance and protoliths of the HP/UHP and amphibolite facies rocks in the western Woodlark Basin remain poorly constrained. There, the shear zone carapace of metamorphic core complexes in the D’Entrecasteaux Islands contain Late Mesozoic garnet amphibolites indicating prograde metamorphism was synchronous with previously documented arc-continent collision on mainland PNG. It is possible that these rocks were rifted away from Australia prior to being metamorphosed in the complex plate-boundary zone that developed in the southwest Pacific following the breakup of East Gondwana. We examined high and low grade metamorphic rocks with a wide range of bulk and trace element compositions. The samples have a range of isotopic compositions (?Hf -0.79 to +11.85 and ?Nd -3.39 to +6.24) but none of these are the highly unradiogenic values that would be expected of Precambrian continental crust. The Nd isotopic compositions of these rocks are similar to previously reported Nd values of Late Cretaceous aged magmatic rocks and volcaniclastic sediments comprising the Whitsunday Volcanic Province (WVP) in northeastern Australia. The WVP is a Late Cretaceous rift-related igneous province whose origin is likely related to the breakup of East Gondwana. Zircons from the metamorphic rocks in the Woodlark Basin also commonly have cores with Late Cretaceous U-Pb ages that coincide temporally with WVP volcanism. The similarities between the metamorphic rocks in the Woodlark Basin and the rocks in the WVP suggest that either: 1) the metamorphic rocks now exposed in the Woodlark Basin originated as part of the Late Cretaceous aged rift-related WVP, and were rifted away from Australia during the opening of the Coral Sea basin, or 2) that detritus from that province provided the protoliths for metamorphic rocks found in the Woodlark Basin or 3) volcanic activity associated with the breakup of east Gondwana extended into the region currently occupied by these islands, and that these rocks were never actually situated near present day Australia.

Zirakparvar, N. A.; Baldwin, S.; Fitzgerald, P. G.; Vervoort, J. D.

2010-12-01

34

A new Late Triasssic phytogeographical scenario in westernmost Gondwana.  

PubMed

Floral provincialism within the Southern Hemisphere during the Late Triassic (230?Ma) is characterized by the Ipswich and Onslow provinces, recognized originally in eastern Gondwana. However, new palynological assemblages from the Ischigualasto Formation, northwestern Argentina (231-225?Ma), change the phytogeographic interpretation for the Carnian-Norian in the westernmost Gondwana, which was previously considered part of the southern floral Ipswich province. Here we show the presence of diagnostic Euramerican species within assemblages dominated by Gondwanan taxa that allows us to refer the palynofloras to the Onslow province. Our new data extend the Onslow floral belt, previously recognized from the western edge of Tethys to Timor, to the western margin of South America. This has implications for palaeophytogeography, palaeoclimate reconstructions and the palaeoecology of a Triassic ecosystem, which has yielded significant vertebrate remains and is regarded important in the early evolution of groups such as the Dinosauria. PMID:23695683

Césari, Silvia N; Colombi, Carina E

2013-01-01

35

A new Late Triasssic phytogeographical scenario in westernmost Gondwana  

NASA Astrophysics Data System (ADS)

Floral provincialism within the Southern Hemisphere during the Late Triassic (230Ma) is characterized by the Ipswich and Onslow provinces, recognized originally in eastern Gondwana. However, new palynological assemblages from the Ischigualasto Formation, northwestern Argentina (231-225Ma), change the phytogeographic interpretation for the Carnian-Norian in the westernmost Gondwana, which was previously considered part of the southern floral Ipswich province. Here we show the presence of diagnostic Euramerican species within assemblages dominated by Gondwanan taxa that allows us to refer the palynofloras to the Onslow province. Our new data extend the Onslow floral belt, previously recognized from the western edge of Tethys to Timor, to the western margin of South America. This has implications for palaeophytogeography, palaeoclimate reconstructions and the palaeoecology of a Triassic ecosystem, which has yielded significant vertebrate remains and is regarded important in the early evolution of groups such as the Dinosauria.

Césari, Silvia N.; Colombi, Carina E.

2013-05-01

36

Gondwana to Pangea: a detrital zircons tale from NW Iberia  

NASA Astrophysics Data System (ADS)

The Cantabrian Zone of NW Iberia preserves a voluminous, almost continuous, sedimentary sequence that ranges from Neoproterozoic to Early Permian in age. Its tectonic setting is controversial and recent hypotheses include (i) passive margin deposition along the northern margin of Gondwana or (ii) an active continental margin or (iii) a drifting ribbon continent. In this paper we present detrital zircon U-Pb laser ablation age data from 13 samples from the Cantabrian Zone sequence ranging from Early Silurian to Early Permian in depositional age, which, together with previously published detrital zircon ages from Ediacaran-Ordovician strata, allow a comprehensive analysis of changing provenance through time. Laser ablation U-Pb geochronological analysis of detrital zircons in thirteen samples of the Cantabrian Zone of the NW Iberian Variscan belt reveal that this portion of Iberia was part of the northern passive-margin of Gondwana from the Ordovician to Late Devonian, until the onset of collision between Gondwana and Laurentia. Zircon populations in these samples show important similarities with zircons found in coeval detrital rocks from central North Africa. Additionally, the populations found in NW Iberia are coherent with a Saharan source. We suggest that NW Iberia was situated from Ordovician to Late Devonian along the Gondwana northern passive margin close to the paleoposition of central North Africa and Saharan craton. Additionally, the Carboniferous-Permian samples studied record the provenance changes produced during the Variscan collision and basement exhumation, the Cantabrian orocline formation and the subsequent detachment of the lithospheric mantle. The provenance changes reflect major topographic variations due to the afore mentioned processes during Late Devonian to Early Permian times. Detrital zircon studies are a useful tool that can complement regional syntheses in deducing paleogeographic locations, the occurrence of major tectonic events such as terrane dispersal and amalgamation, and continental collisions, as well as the crustal response to lithospheric-scale processes such as oroclinal buckling and lithospheric delamination.

Pastor-Galán, Daniel; Gutiérrez-Alonso, Gabriel; Brendan Murphy, J.; Fernández-Suárez, Javier; Hofmann, Mandy; Linnemann, Ulf

2013-04-01

37

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

38

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

39

Early Paleozoic paleogeography of the northern Gondwana margin: new evidence for Ordovician-Silurian glaciation  

Microsoft Academic Search

During the Early Paleozoic, transgressions and the distribution of sedimentary facies on the northern Gondwana margin were controlled by a regional NNW-SSE to almost north-south striking structural relief. In Early Silurian times, a eustatic highstand enabled the sea to reach its maximum southward extent.The counterclockwise rotation of Gondwana during the Cambrian and Early Ordovician caused the northern Gondwana margin to

A.-K. Semtner; E. Klitzsch

1994-01-01

40

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

41

Multiple forecasts of kharif rice in orissa state-four year experience of fasal pilot study  

Microsoft Academic Search

Considering the requirement of multiple pre-harvest crop forecasts, the concept of Forecasting Agricultural output using Space,\\u000a Agrometeorology and Land based observations (FASAL) has been formulated. Development of procedure and demonstration of this\\u000a technique for four in-season forecasts for kharif rice has been carried out as a pilot study in Orissa State since 1998. As\\u000a the availability of cloud-free optical remote

N. K. Patel; M. Chakraborty; S. Dutta; C. Patnaik; J. S. Parihar; S. C. Moharana; A. Das; B. K. Sarangi; G. Behera

2004-01-01

42

Geochemistry of soil around a fluoride contaminated area in Nayagarh District, Orissa, India: Factor analytical appraisal  

Microsoft Academic Search

Fluoride contamination in soil was studied in the vicinity of a hot spring in Nayagarh district of Orissa. Both bulk soil from 0 to 30 cm depth and profile soils from 0 to 90 cm depth were analyzed for total fluoride (Ft) and 0.01 M CaCl2 extractable fluoride (Fca), major elements, pH, EC and Organic Carbon (OC). High concentrations of both Ft

S. Tripathy; M. K. Panigrahi; N. Kundu

2005-01-01

43

Ordovician accretion of the Argentine Precordillera terrane to Gondwana: a review  

Microsoft Academic Search

The Precordillera terrane of Argentina was rifted as a lithospheric block from the Ouachita embayment of southeastern Laurentia and accreted to western Gondwana. In various interpretations, the time of rifting of the Precordillera terrane from Laurentia ranges from Early Cambrian to Late Ordovician, and the time of accretion to Gondwana ranges from Middle–Late Ordovician to Silurian–Devonian. This review of available

William A. Thomas; Ricardo A. Astini

2003-01-01

44

New Discoveries of Devonian Vertebrates from South America, and implications for Gondwana–Euramerica contact  

Microsoft Academic Search

A new fossil fish fauna from western Venezuela provides the first South American Devonian record of antiarch and phyllolepid placoderms, and sarcopterygians including lungfishes, groups widely distributed on other continents. Endemic elements in the fish fauna indicate Gondwana affinities, and the age of the phyllolepid placoderm occurrence is consistent with a model of biotic dispersal between Gondwana and Euramerica near

Gavin C Young; John M Moody; Jhonny E Casas

2000-01-01

45

The Neoproterozoic assembly of Gondwana and its relationship to the Ediacaran–Cambrian radiation  

Microsoft Academic Search

The assembly of the Gondwana supercontinent during the waning stages of the Proterozoic provides a tectonic backdrop for the myriad biological, climatological, tectonic and geochemical changes leading up to, and including, the Cambrian radiation. A polyphase assembly of Gondwana during the East Africa, Brasiliano, Kuungan and Damaran orogenies resulted in an extensive mountain chain which delivered nutrients into a shifting

Joseph G. Meert; Bruce S. Lieberman

2008-01-01

46

Molecular investigations of dengue virus during outbreaks in Orissa state, Eastern India from 2010 to 2011.  

PubMed

Dengue is one of the most important arboviral diseases in India. Orissa state in Eastern India reported the first dengue outbreak in 2010, followed by extensive outbreaks in 2011, affecting large number of people. Detailed entomological, serological and phylogenetic investigations were performed in mosquitoes and patients serum collected from dengue virus (DENV) affected areas of Orissa. The combination of DENV specific IgM capture-ELISA and reverse-transcription PCR (RT-PCR) detected high DENV positivity in serum samples. DENV was detected in mosquitoes reared from field caught pupae by RT-PCR, which confirmed the vertical transmission of DENV that may have an important role in the recurrence of dengue outbreaks. Phylogenetic analyses revealed the circulation of Indian lineage of DENV-2 (genotype-IV) and DENV-3 (genotype-III) in vectors and patients serum in Orissa from 2010 to 2011, DENV-2 being the prevailing serotype. Selection analyses within the C-prM region showed that the emergence of DENV-2 and DENV-3 in Orissa was constrained by purifying selection which suggested the role of ecological factors like mosquito density and behavior in the recurrent outbreaks. Aedes albopictus was found to be the most abundant vector in the areas surveyed, followed by Aedes aegypti. Indoor breeding spots (earthen pots) were most abundant, with high pupal productivity (38.50) and contributed maximum Aedes species in the affected areas. The DENV infection rate estimated by maximum likelihood estimate (MLE) was high for indoor breeding Aedes (4.87; 95% CI: 1.82, 10.78) in comparison to outdoor breeding Aedes (1.55; 95% CI: 0.09, 7.55). The high MLE in Ae. albopictus (4.72; 95% CI: 1.94, 9.80) in comparison to Ae. aegypti (1.55; 95% CI: 0.09, 7.54) indicated that Ae. albopictus was the main DENV vector responsible for the outbreaks. The results indicated the circulation of two virulent serotypes of DENV in Orissa, mainly by Ae. albopictus with the implication for implementation of intradomecile vector control measures to prevent the spread of dengue. PMID:23523598

Das, Biswadeep; Das, Mumani; Dwibedi, Bhagirathi; Kar, Santanu K; Hazra, Rupenangshu K

2013-06-01

47

Rotation and offset of the Gondwana convergent margin in the New Zealand region following Cretaceous jamming of Hikurangi Plateau large igneous province subduction  

NASA Astrophysics Data System (ADS)

of the Hikurangi Plateau (large igneous province) subduction, within the Chatham Rise convergent margin of Gondwana at circa 105 Ma, led to offset and rotation of the convergent margin before subduction ceased in the New Zealand region at circa 100 Ma. The southern limit of the plateau, following leading slab break off, is highlighted by a lineament of prominent horst blocks in the southern Bounty Trough. Subduction jamming of the Gondwana margin, and accompanying compression of the onshore margin and/or extension of the offshore margin, has led to two 60 km left-lateral SSE offsets of the Chatham Rise convergent margin at the coast and in inland Canterbury. Recognition of the onshore Chatham Rise using the gravity data also highlights the correlation of the inland Chatham Rise and central South Island seismicity. In a similar manner to the rotation of Cretaceous spreading-ridge and transform-fault fabric adjacent to the Osbourn Trough spreading ridge, the convergence direction at the Gondwana margin was rotated anticlockwise to N-S between 105 and 100 Ma. Most of this rotation has been accommodated by offshore extension and margin offset. The divergence between the anticlockwise rotation of offshore crustal structure and the jammed onshore margin led to the development of the Great South Basin at 105-100 Ma. Further offshore in the Bounty Trough, extensional zones, formed between crustal blocks rotated to adjust to a changed Cretaceous direction of subduction, are evident in gravity and seismic profiles.

Davy, Bryan

2014-08-01

48

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

49

Chapter 6 The Maritimes Basin of Atlantic Canada: Basin Creation and Destruction in the Collisional Zone of Pangea  

Microsoft Academic Search

During the final assembly of Pangea, the Maritimes Basin of Atlantic Canada was tectonically active for ?120Myr from the Mid-Devonian to the Early Permian, following terrane accretion and ocean closure in the region. The basin's history records a prolonged period of convergence that post-dated the collision of Gondwana and Laurussia. The 12km of basin fill was laid down in suites

Martin R. Gibling; N. Culshaw; M. C. Rygel; V. Pascucci

2008-01-01

50

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

51

Gondwana breakup and plate kinematics: Business as usual  

NASA Astrophysics Data System (ADS)

A tectonic model of the Weddell Sea is built by composing a simple circuit with optimized rotations describing the growth of the South Atlantic and SW Indian oceans. The model independently and accurately reproduces the consensus elements of the Weddell Sea's spreading record and continental margins, and offers solutions to remaining controversies there. At their present resolutions, plate kinematic data from the South Atlantic and SW Indian oceans and Weddell Sea rule against the proposed, but controversial, independent movements of small plates during Gondwana breakup that have been attributed to the presence or impact of a mantle plume. Hence, although supercontinent breakup here was accompanied by extraordinary excess volcanism, there is no indication from plate kinematics that the causes of that volcanism provided a unique driving mechanism for it.

Eagles, Graeme; Vaughan, Alan P. M.

2009-05-01

52

Negotiating with Dharma Pinnu: towards a social history of smallpox in colonial Orissa.  

PubMed

This paper explores the social complexities associated with the history of smallpox in colonial Orissa in Eastern India. It focuses on tribal communities while taking into account their interactions with non-tribal communities and colonialism. This research grapples with the phenomenon of of the Hinduisation of tribes and the way this implies an acceptance as well as a rejection of the various aspects of non-tribal, Hindu society. Thus, I examine the specific elements of non-tribal groups inoculation, black magic, and subversive cults, demonstrating the close affinities some of these features have with tribal communities. PMID:12776728

Pati, Biswamoy

2002-01-01

53

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

54

Correlating early evolution of parasitic platyhelminths to Gondwana breakup.  

PubMed

Investigating patterns and processes of parasite diversification over ancient geological periods should involve comparisons of host and parasite phylogenies in a biogeographic context. It has been shown previously that the geographical distribution of host-specific parasites of sarcopterygians was guided, from Palaeozoic to Cainozoic times, mostly by evolution and diversification of their freshwater hosts. Here, we propose phylogenies of neobatrachian frogs and their specific parasites (Platyhelminthes, Monogenea) to investigate coevolutionary processes and historical biogeography of polystomes and further discuss all the possible assumptions that may account for the early evolution of these parasites. Phylogenetic analyses of concatenated rRNA nuclear genes (18S and partial 28S) supplemented by cophylogenetic and biogeographic vicariance analyses reveal four main parasite lineages that can be ascribed to centers of diversity, namely Australia, India, Africa, and South America. In addition, the relationships among these biogeographical monophyletic groups, substantiated by molecular dating, reflect sequential origins during the breakup of Gondwana. The Australian polystome lineage may have been isolated during the first stages of the breakup, whereas the Indian lineage would have arisen after the complete separation of western and eastern Gondwanan components. Next, polystomes would have codiverged with hyloid sensu stricto and ranoid frog lineages before the completion of South American and African plate separation. Ultimately, they would have undergone an extensive diversification in South America when their ancestral host families diversified. Therefore, the presence of polystome parasites in specific anuran host clades and in discrete geographic areas reveals the importance of biogeographic vicariance in diversification processes and supports the occurrence and radiation of amphibians over ancient and recent geological periods. PMID:21856629

Badets, Mathieu; Whittington, Ian; Lalubin, Fabrice; Allienne, Jean-Francois; Maspimby, Jean-Luc; Bentz, Sophie; Du Preez, Louis H; Barton, Diane; Hasegawa, Hideo; Tandon, Veena; Imkongwapang, Rangpenyuba; Imkongwapang, Rangpenyubai; Ohler, Annemarie; Combes, Claude; Verneau, Olivier

2011-12-01

55

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

56

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

57

PLANT CONSERVATION IN TEMPLE YARDS OF ORISSA R.B MOHANTY, B.K MOHAPATRA AND S.N PADHY*  

E-print Network

ABSTRACT: 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.

unknown authors

1996-01-01

58

'First we go to the small doctor': First contact for curative health care sought by rural communities in Andhra Pradesh & Orissa, India  

PubMed Central

Background & objectives: Against the backdrop of insufficient public supply of primary care and reports of informal providers, the present study sought to collect descriptive evidence on 1st contact curative health care seeking choices among rural communities in two States of India - Andhra Pradesh (AP) and Orissa. Methods: The cross-sectional study design combined a Household Survey (1,810 households in AP; 5,342 in Orissa), 48 Focus Group Discussions (19 in AP; 29 in Orissa), and 61 Key Informant Interviews with healthcare providers (22 in AP; 39 in Orissa). Results: In AP, 69.5 per cent of respondents accessed non-degree allopathic practitioners (NDAPs) practicing in or near their village; in Orissa, 40.2 per cent chose first curative contact with NDAPs and 36.2 per cent with traditional healers. In AP, all NDAPs were private practitioners, in Orissa some pharmacists and nurses employed in health facilities, also practiced privately. Respondents explained their choice by proximity and providers’ readiness to make house-calls when needed. Less than a quarter of respondents chose qualified doctors as their first point of call: mostly private practitioners in AP, and public practitioners in Orissa. Amongst those who chose a qualified practitioner, the most frequent reason was doctors’ quality rather than proximity. Interpretation & conclusions: The results of this study show that most rural persons seek first level of curative healthcare close to home, and pay for a composite convenient service of consulting-cum-dispensing of medicines. NDAPs fill a huge demand for primary curative care which the public system does not satisfy, and are the de facto first level access in most cases. PMID:22199101

Gautham, Meenakshi; Binnendijk, Erika; Koren, Ruth; Dror, David M.

2011-01-01

59

Potential geodynamic relationships between the development of peripheral orogens along the northern margin of Gondwana and the amalgamation of West Gondwana  

NASA Astrophysics Data System (ADS)

The Neoproterozoic-Early Cambrian evolution of peri-Gondwanan terranes (e.g. Avalonia, Carolinia, Cadomia) along the northern (Amazonia, West Africa) margin of Gondwana provides insights into the amalgamation of West Gondwana. The main phase of tectonothermal activity occurred between ca. 640-540 Ma and produced voluminous arc-related igneous and sedimentary successions related to subduction beneath the northern Gondwana margin. Subduction was not terminated by continental collision so that these terranes continued to face an open ocean into the Cambrian. Prior to the main phase of tectonothermal activity, Sm-Nd isotopic studies suggest that the basement of Avalonia, Carolinia and part of Cadomia was juvenile lithosphere generated between 0.8 and 1.1 Ga within the peri-Rodinian (Mirovoi) ocean. Vestiges of primitive 760-670 Ma arcs developed upon this lithosphere are preserved. Juvenile lithosphere generated between 0.8 and 1.1 Ga also underlies arcs formed in the Brazilide Ocean between the converging Congo/São Francisco and West Africa/Amazonia cratons (e.g. the Tocantins province of Brazil). Together, these juvenile arc assemblages with similar isotopic characteristics may reflect subduction in the Mirovoi and Brazilide oceans as a compensation for the ongoing breakup of Rodinia and the generation of the Paleopacific. Unlike the peri-Gondwanan terranes, however, arc magmatism in the Brazilide Ocean was terminated by continent-continent collisions and the resulting orogens became located within the interior of an amalgamated West Gondwana. Accretion of juvenile peri-Gondwanan terranes to the northern Gondwanan margin occurred in a piecemeal fashion between 650 and 600 Ma, after which subduction stepped outboard to produce the relatively mature and voluminous main arc phase along the periphery of West Gondwana. This accretionary event may be a far-field response to the breakup of Rodinia. The geodynamic relationship between the closure of the Brazilide Ocean, the collision between the Congo/São Francisco and Amazonia/West Africa cratons, and the tectonic evolution of the peri-Gondwanan terranes may be broadly analogous to the Mesozoic-Cenozoic closure of the Tethys Ocean, the collision between India and Asia beginning at ca. 50 Ma, and the tectonic evolution of the western Pacific Ocean.

Murphy, J. Brendan; Pisarevsky, Sergei; Nance, R. Damian

2013-10-01

60

Early Middle Ordovician evidence for land plants in Argentina (eastern Gondwana).  

PubMed

• The advent of embryophytes (land plants) is among the most important evolutionary breakthroughs in Earth history. It irreversibly changed climates and biogeochemical processes on a global scale; it allowed all eukaryotic terrestrial life to evolve and to invade nearly all continental environments. Before this work, the earliest unequivocal embryophyte traces were late Darriwilian (late Middle Ordovician; c. 463-461 million yr ago (Ma)) cryptospores from Saudi Arabia and from the Czech Republic (western Gondwana). • Here, we processed Dapingian (early Middle Ordovician, c. 473-471 Ma) palynological samples from Argentina (eastern Gondwana). • We discovered a diverse cryptospore assemblage, including naked and envelope-enclosed monads and tetrads, representing five genera. • Our discovery reinforces the earlier suggestion that embryophytes first evolved in Gondwana. It indicates that the terrestrialization of plants might have begun in the eastern part of Gondwana. The diversity of the Dapingian assemblage implies an earlier, Early Ordovician or even Cambrian, origin of embryophytes. Dapingian to Aeronian (Early Silurian) cryptospore assemblages are similar, suggesting that the rate of embryophyte evolution was extremely slow during the first c. 35-45 million yr of their diversification. The Argentinean cryptospores predate other cryptospore occurrences by c. 8-12 million yr, and are currently the earliest evidence of plants on land. PMID:20731783

Rubinstein, C V; Gerrienne, P; de la Puente, G S; Astini, R A; Steemans, P

2010-10-01

61

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

62

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

63

Neoproteozoic to Cambrian Tectonic Evolution of the Proto-Andean Margin of Gondwana: Implications for the Opening of Iapetus  

NASA Astrophysics Data System (ADS)

We present a new tectonic model for the Pampean accretion of the Arequipa-Antofalla-Pampia (AAP) ribbon continent to the Proto-Andean margin of Gondwana represented by the Amazonia and Rio de La Plata cratons, based on our studies of the Puncoviscana Formation in northern and central Argentina. A compilation of existing detrital zircon ages of the Puncoviscana Formation and correlative units along strike in the Pampean orogenic belt to the south combined with our new U-Pb SHRIMP zircon ages of Puncoviscana Formation felsic tuffs and mafic volcaniclastic rocks (c. 531 Ma) suggests this unit mainly represents an Early Cambrian arc- trench gap to foreland basin succession formed during east-directed closure of a late Neoproterozoic marginal basin. The marginal basin, which probably remained relatively narrow, initially had opened behind an east- facing 650-570 Ma island arc (eastern Pampia arc), built upon the rifted, leading edge of the AAP. The 531 Ma felsic tuffs are interpreted to represent the products of a new, short-lived Early Cambrian magmatic arc built upon the now composite Proto-Andean margin, following Late Neoproterozoic, soft-accretion of the eastern Pampia arc and a subduction polarity reversal. Puncoviscana Formation conglomerates previously interpreted as early rift-related deposits are better interpreted as late-orogenic basin fills and/or were deposited after basin closure. Our new U-Pb zircon age of the post-collision Canani tonalite (c. 517 Ma), which intruded into Tilcarian deformed Puncoviscana Formation rocks in the north westernmost part of Argentina in the Puncoviscana type locality, combined with the existing 529-517 Ma zircon ages for post-collision peraluminous granites and tonalites in the Eastern Pampean Ranges to the south indicates that the synorogenic Puncoviscana Formation formed between 540 and 517 Ma, progressively cannibalizing its orogenic hinterland over time. In addition, the Tilcarian and Pampean orogenies represent the same event. We suggest that AAP rifted-off from Laurentia between 700 and 650 Ma, shortly after Amazonia's departure during Rodinia's break-up. We emphasize that it is the departure of AAP, not Amazonia that opened Iapetus in the Late Neoproterozoic. We also suggest that Ganderia in the northern Appalachians, originally formed an extension of the AAP.

van Staal, C. R.; Escayola, M.; Davis, B.

2009-05-01

64

Politics of co-optation: community forest management versus Joint Forest Management in Orissa, India.  

PubMed

The article considers the impact of introducing government co-management policy in the form of Joint Forest Management (JFM) in an area with a five-decade-old self-organized community forest management system in Orissa, India. We ask a question that appears not to have been previously examined: What happens when JFM replaces an already existing community forest management arrangement? Our comparison of the JFM arrangement with the self-organized community forest management regime (pre- and post-2002 in a selected village) provides three conclusions: (1) The level of villager participation in forest management has declined, along with the erosion of the bundle of common rights held by them; (2) multiple institutional linkages between the village and outside agencies, and reciprocal relations with neighboring villages have been abandoned in favor of a close relationship with the Forestry Department; and (3) the administration of the forestry resource has become politicized. We conclude that the "one-size-fits-all" approach of the JFM, with its pre-packaged objectives and its narrow scope of forest management, is likely to limit experimentation, learning, and institutional innovation that characterizes community forest management. PMID:18288518

Nayak, Prateep K; Berkes, Fikret

2008-05-01

65

Important Ayurv?da literatures from the manuscripts available from Orissa (Cikits?rnava).  

PubMed

In the treasure of Ayurv?dic literature, many texts are missing or partially available. Only references or few verses from many such texts are mentioned in later texts. Unfortunately, a large number of Ayurv?dic texts are unexplored till today are likely to exist in palm-leaf manuscripts, which are decaying or undergoing permanent annihilation. As such many unique and valuable information contained in these texts are being lost. Though several Institutions have taken up work on literary Research, only few texts have been published during past decades. The present paper highlights the salient features of the text 'Cikits?rnava' authored by Vi?van?th Sena of 16th century of Orissa. Though his text on Pathy?pathya has already been published, which has got a place in the pages of history of Ayurv?da, a very little is known about this important text on therapeutics. Various aspects of this text and its author have been discussed to bring it in to the knowledge of fraternity of Ayurvedic physicians and Sanskrit scholars. PMID:17333660

Padhi, M M; Das, B; Audichya, K C; Rao, M M

2005-01-01

66

Antibiotic use, resistance development and environmental factors: a qualitative study among healthcare professionals in Orissa, India  

PubMed Central

Background Antibiotic resistance is a major public health problem affecting both current and future generations. The influence of environmental factors on antibiotic use and resistance development in bacteria is largely unknown. This study explored the perceptions of healthcare providers on antibiotic use and resistance development in relation to environmental factors i.e. physical, natural, social and behavioural factors. Methods A qualitative interview study was conducted using face-to-face, semi-structured interviews among registered allopathic doctors, veterinarians and drug dispensers in Orissa, India. The interview transcripts were analyzed using latent content analysis. Results The main findings of this study relate to two themes: 'Interrelationship between antibiotic use, resistance development and environment' and 'Antibiotic management contributing to the development and spread of resistance'. The interviewees viewed the following as possible contributors to antibiotic use/misuse and resistance development: changes in the natural and physical environment i.e. climate variability, pollution, physiography and population growth; the socioeconomic environment affecting health-seeking behaviour and noncompliance with medication; a lack of healthcare facilities and poor professional attitudes; and ineffective law enforcement regarding medicine dispensing and disposal. Conclusions Generally, the interviewees perceived that although behavioural and social environmental factors are major contributors to resistance development, changes in the physical and natural environment also influence development of antibiotic resistance. The respondents also perceived that there is a lack of information about, and poor awareness of, what constitutes prudent use of antibiotics. They suggested a need for information, education, dissemination and proper implementation and enforcement of legislation at all levels of the drug delivery and disposal system in order to improve antibiotic use and prevent pharmaceutical contamination of the environment. PMID:20964815

2010-01-01

67

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

68

A Southern Hemisphere origin for campanulid angiosperms, with traces of the break-up of Gondwana  

PubMed Central

Background New powerful biogeographic methods have focused attention on long-standing hypotheses regarding the influence of the break-up of Gondwana on the biogeography of Southern Hemisphere plant groups. Studies to date have often concluded that these groups are too young to have been influenced by these ancient continental movements. Here we examine a much larger and older angiosperm clade, the Campanulidae, and infer its biogeographic history by combining Bayesian divergence time information with a likelihood-based biogeographic model focused on the Gondwanan landmasses. Results Our analyses imply that campanulids likely originated in the middle Albian (~105 Ma), and that a substantial portion of the early evolutionary history of campanulids took place in the Southern Hemisphere, despite their greater species richness in the Northern Hemisphere today. We also discovered several disjunctions that show biogeographic and temporal correspondence with the break-up of Gondwana. Conclusions While it is possible to discern traces of the break-up of Gondwana in clades that are old enough, it will generally be difficult to be confident in continental movement as the prime cause of geographic disjunctions. This follows from the need for the geographic disjunction, the inferred biogeographic scenario, and the dating of the lineage splitting events to be consistent with the causal hypothesis. PMID:23565668

2013-01-01

69

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

70

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

71

Title of the project: Improving Basic Service Delivery to Urban Poor by Local Environmental Management: A Study of a Poor Community (Thoriasahi) in Cuttack City ,Orissa, India  

Microsoft Academic Search

Cuttack, the biggest and most populous urban agglomerations of Orissa has experiencing population pressure and the impact of urbanization. Growing population, coupled with meager resources, increasingly stresses the urban utilities and services making the urban environmental worse. The study conducted survey questionnaire, informal discussions, and observations for compiling information and collecting data as well as from published and unpublished documents.

Choudhury Mihir; Charan Mohanty; A. T. M. Nurul; Vilas Nittivatananon

72

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

73

Central South Atlantic kinematics: a 3D ocean basin-scale model of the Walvis Ridge and Rio Grande Rise  

Microsoft Academic Search

Prior to the breakup of western Gondwana, ca. 130 Ma, the Tristan da Cuhna mantle plume produced the eastern South American Parana, and western African Etendeka, flood basalts. As the South Atlantic basin opened, the ridge-centered plume produced seaward extending hotspot tracks: Rio Grande Rise on the South American Plate, and Walvis Ridge on the African Plate. Several ocean floor

D. E. Bird; S. A. Hall

2009-01-01

74

The Chachil Limestone (Pliensbachianeearliest Toarcian) Neuqun Basin, Argentina: UePb age calibration and its significance on the Early Jurassic  

E-print Network

calibration and its significance on the Early Jurassic evolution of southwestern Gondwana H.A. Leanza a,*, A Early Jurassic Chachil Limestone Precuyano Cycle Neuquén Basin a b s t r a c t New radiometric UePb ages obtained on zircon crystals from Early Jurassic ash layers found within beds of the Chachil Limestone

Mazzini, Adriano

75

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

76

Frontier sedimentary basins of New Zealand region  

SciTech Connect

Petroleum-prospective basins of New Zealand began to form by mid-Cretaceous rifting of crustal elements previously assembled at the Gondwana continental margin. During the latest Cretaceous-early Cenozoic New Zealand separated from Australia and Antarctica by sea-floor spreading. An overall transgression in widely recorded in this post-rift phase, with decreasing clastic sediment supply as land area and relief were reduced. Mid-Cenozoic initiation of the modern plate boundary has resulted in uplift of mountain ranges, subsidence and filling of troughs, progradation of the shelf, and common reactivation or eversion of older structures. Petroleum potential of less explored basins can be compared to the productive Taranki basin. Source rocks are coal-rich deposits of the rift phase, also developed in Great South, Canterbury/Chatham, Western Southland, West Coast, and Northland basins. A different source contributes to oil and gas seeps on the East Coast, a continental margin during Late Cretaceous. The main reservoirs of Taranaki are early Cenozoic coastal and fluvial sands, also present in Great South, Canterbury, and West Coast and possibly other basins. Other Taranaki reservoirs include mid-Cenozoic limestone and Miocene turbidites, which are widespread in most other basins. Pliocene limestones have excellent reservoir potential on the East Coast. Late Cenozoic tectonics, essential to trap development and significant for maturation in Taranaki, have created similar structures in basins near the plate boundary but are less significant in the development of Great South, eastern Canterbury/Chatham, and Northland basins.

Beggs, J.M. (DSIR Geology and Geophysics, Lower Hutt (New Zealand))

1991-03-01

77

The evolution of Gondwana: U-Pb, Sm-Nd, Pb-Pb and geochemical data from Neoproterozoic to Early Palaeozoic successions of the Kango Inlier (Saldania Belt, South Africa)  

NASA Astrophysics Data System (ADS)

The provenance of Neoproterozoic to Early Palaeozoic rocks at the southern margin of the Kalahari craton reveals a depositional setting and evolution with a significant position in the formation of Gondwana. The sedimentary record shows a progression from immature, moderately altered rocks in the Ediacaran Cango Caves Group; to mature, strongly altered rocks in the Early Palaeozoic Kansa Group and overlying formations; culminating below very immature quartzarenites of Ordovician age. Petrographic and geochemical observations suggest the evolution of a small restricted basin with little recycling space towards a larger continental margin where substantial turbidite deposition is observed. For the southern Kalahari craton, a tectonic evolution comparable to supracrustal rocks in southern South America, Patagonia and Antarctica is supported by similarities in U-Pb ages of detrital zircons (Mesoproterozoic, Ediacaran and Ordovician grain populations); Sm-Nd isotopes (TDM: 1.2-1.8 Ga); and Pb-Pb isotopes. The maximum depositional age of the Huis Rivier Formation (upper Cango Caves Group) is determined at 644 Ma, but a younger age is still possible due to the limited zircon yield. The Cango Caves Group developed in a retro-arc foreland basin syntectonically to the Terra Australis Orogeny, which fringed Gondwana. The Kansa Group and overlying Schoemanspoort Formation are related to an active continental margin developed after the Terra Australis Orogen, with Patagonia being the ‘missing link’ between the Central South American arc and Antarctica during the Ordovician. This explains the occurrence of Ordovician detritus in these rocks, as a source rock of this age has not been discovered in South Africa. The absence of arc characteristics defines a position distal to the active continental margin, in a retro-arc foreland basin. The similarity of isotope proxies to major tectonic provinces in Antarctica and Patagonia, with those on the margins of the Kalahari craton, also points to a common geological evolution during the Mesoproterozoic and highlights the global relevance of this study.

Naidoo, Thanusha; Zimmermann, Udo; Chemale, Farid

2013-08-01

78

Hypothesis for Cretaceous rifting of east Gondwana caused by subducted slab capture  

NASA Astrophysics Data System (ADS)

In the process of subducted slab capture, a spreading ridge approaches subparallel to a subduction zone following the trailing edge of a downgoing plate. Eventually the downgoing plate is too young and small to subduct, and spreading stops. The spreading ridge stalls many tens of kilometres outboard of the subduction zone. The subducted plate welds to the outboard plate across the dormant spreading center and is captured by it. The captured plate then acquires the motion of the plate it welded to. In the southwest Pacific the Pacific-Phoenix ridge approached the east Gondwana margin as the Phoenix plate subducted beneath New Zealand, the Chatham Rise and Campbell Plateau, the Lord Howe Rise (collectively, Zealandia), and Marie Byrd Land in Cretaceous time. Spreading and subduction shut down here between 110 and 105 Ma, and some sections of the Phoenix plate became welded to (captured by) the Pacific plate. Pacific plate northward motion began in Aptian time, pulling the captured subducted microplates with it. This movement exerted a basal traction on the overlying east Gondwana margin and resulted in extension of Zealandia and Marie Byrd Land. Continued Pacific northward motion rifted Zealandia from Marie Byrd Land at about 85 Ma.

Luyendyk, Bruce P.

1995-04-01

79

Regional deformation of the Sierra de San Luis, Argentina: Implications for the Paleozoic development of western Gondwana  

Microsoft Academic Search

Metamorphic and ductile deformation fabrics within the Sierra de San Luis, central Argentina, provide evidence for the Early to Middle Paleozoic development of the paleo-Pacific margin of Gondwana. Presumed Vendian-aged metasedimentary rocks within both the Sierra de San Luis and the Sierras de Córdoba preserve early pressure solution cleavage development. Cambrian peak metamorphism in the Sierras de Córdoba and Ordovician

Steven J. Whitmeyer; Carol Simpson

2004-01-01

80

Regional deformation of the Sierra de San Luis, Argentina: Implications for the Paleozoic development of western Gondwana  

NASA Astrophysics Data System (ADS)

Metamorphic and ductile deformation fabrics within the Sierra de San Luis, central Argentina, provide evidence for the Early to Middle Paleozoic development of the paleo-Pacific margin of Gondwana. Presumed Vendian-aged metasedimentary rocks within both the Sierra de San Luis and the Sierras de Córdoba preserve early pressure solution cleavage development. Cambrian peak metamorphism in the Sierras de Córdoba and Ordovician peak metamorphism in the Sierra de San Luis indicate that juxtaposition of these two terranes did not occur prior to the Late Ordovician. Peak metamorphism and regional folding of the Sierra de San Luis metasedimentary rocks is equated with early stages of the development and shortening of the Famatinian magmatic arc along the western margin of Gondwana. Extensive, NNE trending zones of upper greenschist- to amphibolite-facies ductile deformation within the Sierra de San Luis and along the western margin of the Sierra de Comechingones record the dextral oblique juxtaposition of the Sierra de San Luis terrane against the southwestern margin of the Sierras de Córdoba, coincident with, or closely followed by, the suture of the exotic Precordillera terrane to the western margin of Gondwana by the Early Devonian. Middle to Late Devonian restricted, lower greenschist-grade reactivation of ductile faults may record the accretion of the Chilenia terrane, the final stage of Paleozoic convergent tectonism along this segment of western Gondwana.

Whitmeyer, Steven J.; Simpson, Carol

2004-02-01

81

First record of the family Dromaeosauridae (Dinosauria: Theropoda) in the Cretaceous of Gondwana (Wadi Milk Formation, northern Sudan)  

Microsoft Academic Search

\\u000a Kurzfassung  Die cenomane Wadi Milk Formation des Sudan lieferte eine reiche kontinentale Wirbeltierfauna. Neben Fragmenten von großen\\u000a Theropoden verweisen disartikulierte Fußphalangen-Elemente und ein Zahn auf die Existenz von dromaeosauriden Theropoden in\\u000a der Oberkreide des Sudan; damit ist diese Theropodenfamilie zum ersten Mal auf den Gondwana-Kontinenten nachgewiesen.

Oliver W. M. Rauhut; Christa Werner

1995-01-01

82

Magnetic Anomalies in the Enderby Basin, the Southern Indian Ocean  

NASA Astrophysics Data System (ADS)

Magnetic anomalies in the Southern indian Ocean are vital to understanding initial breakup process of Gondwana. However, seafloor age estimated from magnetic anomalies still remain less well-defined because of the sparse observations in this area. To understand the seafloor spreading history related to the initial breakup process of Gondwana, vector magnetic anomaly data as well as total intensity magnetic anomaly data obtained by the R/V Hakuho-maru and the icebreaker Shirase in the Enderby Basin, Southern Indian Ocean, are used. The strikes of magnetic structures are deduced from the vector magnetic anomalies. Magnetic anomaly signals, most likely indicating Mesozoic magnetic anomaly sequence, are obtained almost parallel to the west of WNW-ESE trending lineaments just to the south of Conrad Rise inferred from satellite gravity anomalies. Most of the strikes of magnetic structures indicate NNE-SSW trends, and are almost perpendicular to the WNW-ESE trending lineaments. Mesozoic sequence magnetic anomalies with mostly WNW-ESE strikes are also observed along the NNE-SSW trending lineaments between the south of the Conrad Rise and Gunnerus Ridge. Magnetic anomalies originated from Cretaceous normal polarity superchron are found in these profiles, although magnetic anomaly C34 has been identified just to the north of the Conrad Rise. However Mesozoic sequence magnetic anomalies are only observed in the west side of the WNW-ESE trending lineaments just to the south of Conrad Rise and not detected to the east of Cretaceous normal superchron signals. These results show that counter part of Mesozoic sequence magnetic anomalies in the south of Conrad Rise would be found in the East Enderby Basin, off East Antarctica. NNE-SSW trending magnetic structures, which are similar to those obtained just to the south of Conrad Rise, are found off East Antarctica in the East Enderby Basin. However, some of the strikes show almost E-W orientations. These suggest complicated ridge reorganization occurred during initial breakup of Gondwana in the Enderby Basin.

Nogi, Y.; Sato, T.; Hanyu, T.

2013-12-01

83

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

84

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

85

Melanosclerites from the Late Ordovician strata of the Shiala Formation, Indian Gondwana  

NASA Astrophysics Data System (ADS)

Melanosclerites, organic-walled microfossils of problematic affinity, are recorded herein from the lower to middle part of the Shiala Formation of Late Ordovician age and is situated below Ordovician-Silurian boundary established previously by acritarchs data. The assemblages recovered yielded the melanosclerites taxa Melanoporella clava, Melanoporella bulla?, Melanoporella polonica, Melanoporella sp. 1, Melanoporella sp. 2 and Melanosteus sp. The Ordovician-Silurian sedimentary sequence discussed herein was a part of the Gondwanan palaeocontinent situated at ˜25 to 30°S. The melanosclerite assemblage recovered herein from the Shiala Formation is broadly comparable with the Öjlemyr Cherts of Sweden, situated at high palaeolatitude and also of Late Ordovician age. Melanosclerites have not previously been studied in detail from Indian Gondwana and published records on this fossil group are rare in general. The present findings improve our knowledge on this group.

Sinha, Hareshwar N.; Trampisch, Claudia

2013-10-01

86

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

87

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

NASA Astrophysics Data System (ADS)

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 terranes of eastern Australia. The two extreme views are either that none of the results from eastern Australia can be used for APWP definition or that all of them can be used. The terrane geology of eastern Australia is now reasonably well known and the paleomagnetic results can be placed in an appropriate terrane concept. This suggests that the Molong-Monaro terrane, where most results come from, was certainly accreted to the main craton by the Middle Devonian and probably by the Early Devonian. Early Devonian palaemagnetric results from the north and south of eastern Australia confirm this to be the case. However, the often used Late Carboniferous results from glacial horizons in eastern Australia are from the New England Fold Belt, where accretion to the main craton may not have been completed until the Middle Triassic. Results from this region now also confirm this to be the case. Both the geological setting and paleomagnetic results now confirm that the South Pole APWP makes a rapid transition from North Africa to south of South Africa between the Late Ordovician (455 Ma) and the Early Devonian (405 Ma). This places Bolivia and adjacent regions of South America near the south pole in Silurian times, a position supported by sedimentological evidence for glaciation in Bolivia at that time. The pole then loops back across southwest Gondwana to reach central Africa by the Early Carboniferous.

Briden, J. C.; McElhinny, M. W.

2004-12-01

88

Corrélations et évolution des bassins sédimentaires de la marge NW du continent de Gondwana au cours du Paléozoïque inférieur (de la Mauritanie au Vénézuela)  

NASA Astrophysics Data System (ADS)

The northwestern margin of Gondwana was dominated by epicontinental and continental sedimentation from the Ordovician to the Carboniferous. These sediments occur in west Africa, the Florida subsurface, and northern Venezuela. Their character suggests major periods of transgression onto the Gondwana margin occurred in the Middle (?) Ordovician, the Lower Silurian (Llandovery) and the middle Devonian (Emsian). Widespread regressions occurred in the Upper Ordovician (intercontinental glaciation) and the Lower and Upper Devonian (Siegenian and Famennian). Depositional conditions along the northwestern margin of Gondwana changed markedly in the Carboniferous as a result of tectonic activity associated with the assembly of Pangea.

Villeneuve, Michel

89

Adverse reactions following mass drug administration during the Programme to Eliminate Lymphatic Filariasis in Orissa State, India.  

PubMed

The frequency and severity of adverse reactions are the main reasons for low compliance of mass drug administration (MDA) under the Programme to Eliminate Lymphatic Filariasis (PELF). This paper reports the frequency and types of adverse reactions during two MDAs during January 2002 and September 2004 in the State of Orissa, India. Of the people who consumed the drugs, 15.5% in the 2002 MDA and 16.5% in the 2004 MDA reported one or more adverse reactions. This rate is higher (49.7%) in a group of individuals who were monitored for 6 days from the day of consumption of drugs during the 2002 MDA. However, many of these reactions were mild. No significant difference was found in the frequency of adverse reactions between MDA with diethylcarbamazine (DEC) alone and with DEC and albendazole. Significant gender differences were found in the 2004 MDA but no such differences were found in the 2002 MDA; however, the frequency of adverse reactions increased with age. Of all the adverse reactions, systemic adverse reactions typically associated with microfilarial death were more frequent. The frequency of adverse reactions was higher in microfilaraemics compared with amicrofilaraemic controls. The present study warrants developing an active adverse reaction surveillance system to minimise the impact of adverse reactions on MDA compliance. PMID:16288792

Babu, B V; Rath, K; Kerketta, A S; Swain, B K; Mishra, S; Kar, S K

2006-05-01

90

Challenges and opportunities for policy decisions to address health equity in developing health systems: case study of the policy processes in the Indian state of Orissa  

PubMed Central

Introduction Achieving health equity is a pertinent need of the developing health systems. Though policy process is crucial for planning and attaining health equity, the existing evidences on policy processes are scanty in this regard. This article explores the magnitude, determinants, challenges and prospects of 'health equity approach' in various health policy processes in the Indian State of Orissa - a setting comparable with many other developing health systems. Methods A case-study involving 'Walt-Gilson Policy Triangle' employed key-informant interviews and documentary reviews. Key informants (n = 34) were selected from the departments of Health and Family Welfare, Rural Development, and Women and Child Welfare, and civil societies. The documentary reviews involved various published and unpublished reports, policy pronouncements and articles on health equity in Orissa and similar settings. Results The 'health policy agenda' of Orissa was centered on 'health equity' envisaging affordable and equitable healthcare to all, integrated with public health interventions. However, the subsequent stages of policy process such as 'development, implementation and evaluation' experienced leakage in the equity approach. The impediment for a comprehensive approach towards health equity was the nexus among the national and state health priorities; role, agenda and capacity of actors involved; and existing constraints of the healthcare delivery system. Conclusion The health equity approach of policy processes was incomprehensive, often inadequately coordinated, and largely ignored the right blend of socio-medical determinants. A multi-sectoral, unified and integrated approach is required with technical, financial and managerial resources from different actors for a comprehensive 'health equity approach'. If carefully geared, the ongoing health sector reforms centered on sector-wide approaches, decentralization, communitization and involvement of non-state actors can substantially control existing inequalities through an optimally packaged equitable policy. The stakeholders involved in the policy processes need to be given orientation on the concept of health equity and its linkage with socio-economic development. PMID:22099141

2011-01-01

91

Lower Paleozoic relative motion of the Arequipa block and Gondwana; Paleomagnetic evidence from Sierra de Almeida of Northern Chile  

NASA Astrophysics Data System (ADS)

Paleomagnetic results have been obtained from a suite of Paleozoic samples from Sierra de Almeida within the high eastern portions of the Atacama desert. Characteristic directions are discussed for two sequences of pre-Silurian lavas of probable Cambro-Ordovician age, the Late Cambrian Choscas pluton, three Late Ordovician-Early Silurian plutons, the Devonian-Carboniferous Lila Formation and late Paleozoic volcanic units of the Pular and Cas Formations. The Choschas pluton and one lava series yield similar northerly and shallow directions which for the presence of reversals and their concordance are suggested to represent early Paleozoic Arequipa plate directions. Directions in the three Late Ordovician-Early Silurian plutons pass a tilt test using an overlying erosional unconformity, and these also include reversals. Together with directions from a second lava series (a roof pendant in an Early Silurian pluton) these define poles compatible with Silurian Gondwana results from Africa and Australia. In situ directions from the basal red beds of the Devonian Lila Formation are inconsistent with Devonian Gondwana or stable South American Poles, but (like the Devonian strata of the Appalachians) they are consistent with a tilt-corrected overprint of Kiaman Superchron age. These results, together with previous results from the late Paleozoic Cas and Pular Formations are discordant from the Gondwana path only for the latest Cambrian-earliest Ordovician. The discordance in paleomagnetic data, together with regional geologic constraints, can be explained by a model in which the Arequipa block, representing a paraautothonous finger of Gondwana (like Japan or the Iberian Peninsula) rotated about a nearby pole but was then resutured during the Silurian. Such a scenario resolves much of the discrepancies in the models which have emerged from Peru, Chile, and Argentina.

Forsythe, Randall D.; Davidson, John; Mpodozis, Constantino; Jesinkey, Christopher

1993-02-01

92

Sexual risk behaviour, knowledge and attitude related to HIV transmission: a study among a migrant tribal group living in the slums of Bhubaneswar City, Orissa, India  

Microsoft Academic Search

Objectives  The purpose was to identify the risky sexual behaviour, knowledge and attitude related to HIV transmission among migrant tribals\\u000a living in the slums of a state headquarters city in India.\\u000a \\u000a \\u000a \\u000a Methods  From four Santal tribe-dominated slums in Bhubaneswar City, Orissa, India, a sample of 113 respondents 15–40 years of age\\u000a was recruited. Both quantitative and qualitative data were obtained through semi-structured interviews.

Suchismita Mishra; Basanta Kumar Swain; Bontha Veerraju Babu

2008-01-01

93

Toarcian–Kimmeridgian depositional cycles of the south-western Morondava Basin along the rifted continental margin of Madagascar  

Microsoft Academic Search

After rifting and final breakup of Gondwana along the former East-African-Antarctic Orogen during the Toarcian–Aalenian, passive\\u000a margins formed around the Proto-Indian Ocean. Sedimentological and stratigraphic studies in the southern Morondava Basin contribute\\u000a to an improved reconstruction of palaeoenvironmental changes during the syn-rift and post-rift margin formation. Depositional\\u000a models based on outcrop and literature data in combination with subsurface data sets

Markus Geiger; Günter Schweigert

2006-01-01

94

Review on the Precambrian geotectonics of the Brazilian Shield and its correlations within West Gondwana  

NASA Astrophysics Data System (ADS)

Within the Brazilian Shield, Paleoproterozoic and Mesoproterozoic rocks are widespread in the large Amazonian Craton, as well as in the São Francisco, São Luiz, Rio de La Plata and other smaller cratonic fragments. Archean nuclei are present as granite-greenstone terrains in the Carajás region and in Central Bahia, and as medium to high-grade crustal fragments within younger belts. The Neoproterozoic tectonic provinces of Borborema, Tocantins and Mantiqueira, that include several orogenic belts active between 950 and 520 Ma, are associated to the process of agglutination of West Gondwana. Their correlative tectonic units in West and South-West Africa are the Trans-Saharan, West Congo, Damara, Gariep and Saldania belts. Juvenile, mantle derived, intra-oceanic magmatic arcs are found within the Tocantins province and the Trans-Saharan belt. They are associated to the Transbrasiliano lineament in South America, and indicate the existence of a large oceanic domain separating Amazonia and West-Africa from the São Francisco-Congo craton in the Neoproterozoic. On the other hand, the crustal signature of granitoid rocks suggests that the Neoproterozoic Adamastor ocean may not have been very large, and that the Rio de La Plata and Kalahari cratons were always relatively close together and to the São Francisco-Congo.

Cordani, U. G.

2003-04-01

95

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

96

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

97

Bio-concentration of chromium--an in situ phytoremediation study at South Kaliapani chromite mining area of Orissa, India.  

PubMed

Mine waste water at South Kaliapani usually contains toxic levels of hexavalent Cr(VI). The present in situ study was conducted at South Kaliapani chromite mine area in Orissa state, India, to assess the phytoremediation ability of three plants, namely, rice (Oryza sativa L.), paragrass (Brachiaria mutica), and an aquatic weed (Eichhornia crassipes), in attenuating Cr(VI) from mine waste water and to correlate the bio-concentration factors (BCF) of Cr. Water hyacinth (E. crassipes) showed 24% to 54% reduction whereas paragrass (B. mutica) was able to reduce 18% to 33% of Cr(VI) from mine water. This reduction was studied over a period of 100 days of plant growth. The reduction was observed through a passage of a sum total of 2,000 sq. ft. cultivated plots and ponds separately. Reduction in Cr(VI) content in mine water varies with plant age as well as with the distance of passage. Cr accumulation and BCF values increased with high soil Cr levels as well as the age of plants. High BCF and transportation index (Ti) values, i.e., 10,924 and 32.09, respectively, were noted for water hyacinth. The Ti values indicated that the root-to-shoot translocation of Cr was very high after 100 days of growth. The total accumulation rate was maximum (8.29 mg Cr kg dry biomass(-1) day (-1)) in paragrass. The BCF values for roots were noted to be higher than those of leaves, stems, and grains of the 125-day-old plants. Hence, paragrass and water hyacinth may be used as tools of phytoremediation to combat the problem of in situ Cr contamination. PMID:21487717

Mohanty, Monalisa; Pattnaik, Mausumi M; Mishra, Aruna K; Patra, Hemanta K

2012-01-01

98

Origin of graphite, and temperature of metamorphism in Precambrian Eastern Ghats Mobile Belt, Orissa, India: A carbon isotope approach  

NASA Astrophysics Data System (ADS)

The carbon isotope composition of graphite and carbon and oxygen isotope composition of associated calcite from different locations of the Eastern Ghats Mobile Belt (EGMB) of Orissa have been measured in order to understand the origin of graphite. The ? 13C values of graphite range from -2.4‰ to -26.6‰. Forty-four of sixty-one samples have ? 13C values less than -20‰. Most of these low ? 13C values graphite corresponds to schists and disseminations in khondalite and calc-silicate granulites, thus indicating graphitization of organic matter. The remaining light-carbon-graphite occurs as veins which is the result of graphitization of transported organic matter. The graphite with intermediate ? 13C value (-13‰ to -19‰) indicates carbon contributions from both organic and carbonates sources and/or mantle sources. The higher ? 13C values graphite (-2.4‰ to -8.8‰) represent mantle carbon and/or carbonate sources without significant contribution from organic carbon. The temperatures of metamorphism have been estimated using carbon isotope ratios of graphite and associated calcite of calc-silicate granulites, where typical cation exchange thermometer assemblages are lacking and significant mineral reaction textures used to calculate pressure-temperature of metamorphic events are absent. Metamorphic temperatures obtained 945 °C are close to the ultrahigh-temperature reported from the EGMB. The minimum temperature estimated using the graphite-carbonate carbon isotope ratio is 90 °C. The lower estimates of temperatures probably indicate changes in the carbon isotope ratio of calcite by decarbonation reaction or armoring of carbonaceous matter in silicates during metamorphism preventing continuous exchange with calcite.

Sanyal, Prasanta; Acharya, B. C.; Bhattacharya, S. K.; Sarkar, A.; Agrawal, S.; Bera, M. K.

2009-09-01

99

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

100

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

101

Long-lived orogenic construction along the paleo-Pacific margin of Gondwana (Deep Freeze Range, North Victoria Land, Antarctica)  

NASA Astrophysics Data System (ADS)

The paleo-Pacific margin of Gondwana records a prolonged history of convergence during the Cambrian-Early Ordovician Ross-Delamerian and the Middle Ordovician-Early Silurian Lachlan orogenies. This study describes structure, petrology, and geochronology of a set of NW-SE striking ductile shear zones that crosscut the Ross age, Early Cambrian granitoid rocks of the Wilson Terrane in the Deep Freeze Range (North Victoria Land, Antarctica). The shear zones developed under amphibolite facies metamorphic conditions (650-700°C and 0.5-0.7 GPa) and show a systematic top-to-the-NE sense of shear. The shear zone activity interferes with emplacement of late, subhorizontal leucocratic dikes and combined U-(Th)-Pb (zircon and monazite) and 40Ar-39Ar (biotite and phengite) geochronology constrains the shearing event at ˜470 Ma, with the sheared granite yielding U-Pb zircon crystallization ages of ˜508 Ma. The reconstructed P-T path followed by the granite protoliths indicates an anticlockwise trajectory, suggesting the synshearing amphibolite metamorphism was associated with the burial of an early formed, Ross continental crustal section. These new findings are interpreted as evidence of a renewed, Ordovician episode of orogenic construction at the paleo-Pacific margin of Gondwana that predated the onset of the Lachlan orogeny in the region. A polycyclic reactivation of the Ross age Wilson Terrane of North Victoria Land is suggested, which is used to propose a unitary framework for the space-time transition from the Ross-Delamerian to the Lachlan orogeny along the proto-Pacific active margin of Gondwana.

Rossetti, Federico; Vignaroli, Gianluca; di Vincenzo, Gianfranco; Gerdes, Axel; Ghezzo, Claudio; Theye, Thomas; Balsamo, Fabrizio

2011-08-01

102

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

103

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

104

Is the Palaeozoic of Istanbul a part of Gondwana-Land or Laurasia, or both?  

NASA Astrophysics Data System (ADS)

The Istanbul Zone, northwestern Turkey, located along the southwestern Black Sea coast, consists of a Neoproterozoic (almost entirely Ediacaran) middle to high-grade crystalline basement with relicts of oceanic lithosphere, volcanic arc and continental crust of unknown affinity and it is overlain by a continuous, well-developed transgressive sedimentary sequence extending from the late Ordovician to the Carboniferous. The Palaeozoic sequence was folded and thrust-faulted during the Carboniferous Hercynian orogeny, and is unconformably overlain by Lower Triassic and younger sedimentary strata. The Istanbul Zone is separated from the Sakarya Zone by the Intra- Pontide suture of early to medial Eocene and from the Strandja Massif by an inferred right-lateral strike-slip West Black Sea Fault. The Sakarya and Strandja fragments exhibit late Triassic and late Jurassic-Early Cretaceous metamorphism and deformation, respectively, which are not observed in the Istanbul Zone. The Palaeozoic sequences of Istanbul and Zonguldak have been compared and correlated with similar sequences in Europe, including the Moesian platform in Romania and Bulgaria, Moravo-Silesia (Brunovistulian) in the Czech Republic and the Rhenohercynian zone in Germany and Belgium, all deposited on the northern passive margin of the Rheic ocean. However, these correlations are based on insufficient knowledge of the correlated rock sequences. By contrast, the ?stanbul sequence resembles the Carnic Alps, the Montaigne Noir, the Bohemian (Saxo-Thuringian), the Morocco, the Pyrenean sequences and thus northern Gondwana-Land of the Palaeozoic times. Istanbul Zone thus combines the characteristics of both the north and south Hercynian margins! The Istanbul Zone shows characteristics of graben-facies deposits during the Ordovician-early Silurian followed by Atlantic-type continental margin sediments of late Silurian- late Devonian age. Since the arc is missing, the ocean facing ?stanbul must have been consumed in a now unknown direction, colliding with a now unidentified Devonian-Carboniferous magmatic arc. The Carboniferous flysch of the Trakya Formation marks the progress of this collision. That collision created a dominantly (now) west vergent marginal fold and thrust belt on the eastern side of the Bosphorous and what now seems an east vergent (but with many inconsistencies) on the western side as a retrocharriage. The region of ?stanbul shows essentially no metamorphism and only a weak cleavage development. What collided with ?stanbul is unknown. The structural style of folds and faults in ?stanbul requires a décollement underneath the whole city which thrusts the entire structure westward.

Lom, Nalan; Ülgen, Semih Can; Özgül, Necdet; Celal ?engör, A. M.

2014-05-01

105

Evolutionary sequences and hydrocarbon potential of Kenya sedimentary basins  

SciTech Connect

Kenya basins have evolved primarily through extension related to episodic continental rifting. In eastern Kenya, thick accumulations of sediments formed within grabens during the prerift phase (Precambrian to Carboniferous) of the Gondwana breakup. Synrift sedimentation (Late Carboniferous to Middle Jurassic) occurred within a north-south rift system, which included the Mandera basin, South Anza basin, and Lamu embayment. During the Early Jurassic, a marine transgression invaded the margins of the eastern Kenya rift basins, resulting in the deposition of platform carbonates and shales. A Callovian-aged salt basin formed in the offshore regions of the Lamu embayment. Intermittent tectonic activity and eustatic sea-level changes controlled sedimentation, which produced marine shales, carbonates or evaporites, and fluvio-deltaic to lacustrine sandstones. From the Early Cretaceous to recent, continental sediments were deposited within the North Anza and Turkana basins. These fluvial-lacustrine sediments are similar to the Lower Cretaceous sequences that have produced oil in the Mesozoic Sudanese Abu Gabra rift. Although exploration activities began in the early 1950s, significant occurrences of potential reservoir, source, and seal lithologies as well as trapping configurations remain in many areas. Favorable structures and sequences of reservoir sandstones and carbonates overlain by potentially sealing lacustrine or marine shales, evaporites, or volcanics have been noted. Potential source beds are believed to be present within shales of the lacustrine or marine depositional environments.

Cregg, A.K. (Western Atlas International, Inc., Carrollton, TX (United States))

1991-03-01

106

The Saint-Georges-sur-Loire olistostrome, a key zone to understand the Gondwana-Armorica  

E-print Network

, The Lanvaux Unit and the Saint-Georges-sur-Loire Unit, - a southern sub-domain made of a stack of nappes, from-pressure nappes complex and the overlying Mauges basement nappe. The Ancenis basin was opened in the Mauges Napp

Paris-Sud XI, Université de

107

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

108

Petrology of the eclogites from western Tasmania: Insights into the Cambro-Ordovician evolution of the paleo-Pacific margin of Gondwana  

Microsoft Academic Search

Eclogite facies rocks along the Paleozoic active margin of Gondwana are rare. They are limited to isolated segments of Northern Victoria Land (Antarctica), western Tasmania, and southeastern Australia. New petrological data for mafic rocks and their host garnet-kyanite schists from the Franklin Metamorphic Complex (western Tasmania) permit reconstruction of six main stages of mineral growth for the eclogite. Stages I

R. Palmeri; R. Chmielowski; S. Sandroni; F. Talarico; C. A. Ricci

2009-01-01

109

Crustal structure of the east Gondwana margin in southeast Australia revealed by transdimensional ambient seismic noise tomography  

NASA Astrophysics Data System (ADS)

Ambient seismic noise data from the ongoing WOMBAT transportable seismic array in southeast Australia, the largest deployment of its kind in the Southern Hemisphere, are used to produce a high-resolution 3-D shear wave velocity model of the region. We apply a two-stage, transdimensional, hierarchical Bayesian inversion approach to recover phase velocity maps at periods of 1-20 s and then invert phase velocity dispersion for 3-D shear wave velocity structure to the base of the crust. Data uncertainty is propagated through the sequence of inversions, ensuring that model complexity is justified by the quality and quantity of the measurements. The pattern of 3-D velocity variations helps elucidate the geometry and position of key crustal features—such as the Torrens Hinge Zone—associated with the transition from Paleozoic eastern Australia to Precambrian central and western Australia that formed along the proto-Pacific margin of east Gondwana.

Young, M. K.; Cayley, R. A.; McLean, M. A.; Rawlinson, N.; Arroucau, P.; Salmon, M.

2013-08-01

110

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

111

Late Paleozoic depositional controls in the Paradox basin, Colorado and Utah  

SciTech Connect

The Paradox evaporite basin formed during the Desmoinesian to Wolfcampian intracratonic Ancestral Rocky Mountain orogeny in response to the Laurentia-Gondwana collision. Basin subsidence resulted from the southwestward thrusting and probably lateral movement on the Uncompahgre Fault along it's northeastern margin. This created a strongly asymmetrical basin that was similar in geometry to a foreland basin, with the Definace-Zuni and Piute platforms occupying the position of a foreland bulge. The evaporite basin was separated from its southeastern extension, the San Juan Trough, by the northeast-trending Hogback fault zone. An orthogonal pattern of northeast- and northwest-trending basement faults extends from the San Juan Basin into the Paradox Basin and can be shown to have exerted significant control on depositional patterns throughout the Phanerozoic. Paleogeographic and plate reconstructions indicate that the north-south-trending Uncompahgre and Front Range highlands lay at right angles to the prevailing easterly winds--thus removed most of the moisture and produced arid to semiarid conditions throughout the Paradox Basin and San Juan Trough. As many as 35 halite-bearing cycles have been identified in the Desmoinesian Paradox Formation. Each cycle is composed of a transgressive freshening phase and a regressive evaporitic phase with either halite or potash as the final product. All of the evaporite cycles are bounded by unconformities and can be divided into higher order sequences, particularly in the correlative carbonate shelf environments to the southwest.

Huffman, A.C. Jr. (Geological Survey, Denver, CO (United States))

1992-01-01

112

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

113

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

114

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

PubMed

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

2008-09-22

115

Neoproterozoic continental growth prior to Gondwana assembly: Constraints from zircon-titanite geochronology, geochemistry and petrography of ring complex granitoids, Sudan  

NASA Astrophysics Data System (ADS)

Neoproterozoic continental growth in the Saharan Metacraton in central North Sudan is marked by juvenile A-type magmatism (the Jebel Arusa and Jebel Sherif ring complexes). Chemical features are characteristic of within plate (A-type) magmatism marked by Y/Nb ratios > 1.2 typical of the A2 group. Zircon U-Pb analyses yield an age of 707 ± 19 Ma for the Jebel Arusa complex and an age of 718 ± 18 Ma for the Jebel Sherif complex. Titanite U-Pb dating gives closely similar concordant ages of 704 ± 4 Ma and 706 ± 4 Ma for the Jebel Arusa complex and the Jebel Sherif complex, respectively. This ca. 707-718 Ma A-type magmatism in Sudan was induced by the first collisional contact in the north between East and West Gondwana. The 600 Ma titanite recrystallization ages are attributed to tectonothermal effects of the culminating phase of the Pan-African orogeny by collision of East and West Gondwana in the south, forming the Mozambique belt and the final amalgamation of East and West Gondwana to Greater Gondwana. The much younger titanite age of ca. 460 Ma, marks later recrystallization due to localized shear reactivations. Low initial 87Sr/ 86Sr ratios (0.70000 to 0.70346) and high ?Ndi values (+ 5.4 to + 6.8) indicate the juvenile nature of the A-type magma source which is characteristic of a typical Neoproterozoic asthenospheric mantle. The tightly clustered Nd model ages, identical to, or closely similar to, or slightly older than the zircon crystallization ages, depending on the depleted mantle model used, further confirm the juvenile nature of the source. This post-collisional A-type magmatism is characteristic of delamination of a thickened asthenospheric mantle triggering mantle upwelling, high heat flow and partial remelting of the juvenile sources.

Shang, C. K.; Morteani, G.; Satir, M.; Taubald, H.

2010-07-01

116

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

117

Hydrocarbon potential of the Lamu basin of south-east Kenya  

SciTech Connect

The Lamu basin occupies the coastal onshore and offshore areas of south-east Kenya. This fault bounded basin formed as a result of the Paleozoic-early Mesozoic phase of rifting that developed at the onset of Gondwana dismemberment. The resultant graben was filled by Karroo (Permian-Early Jurassic) continental siliciclastic sediments. Carbonate deposits associated with the Tethyan sea invasion, dominate the Middle to Late Jurassic basin fill. Cessation of the relative motion between Madagascar and Africa in the Early Cretaceous, heralded passive margin development and deltaic sediment progradation until the Paleogene. Shallow seas transgressed the basin in the Miocene when another carbonate regime prevailed. The basin depositional history is characterized by pulses of transgressive and regressive cycles, bounded by tectonically enhanced unconformities dividing the total sedimentary succession into discrete megasequences. Source rock strata occur within Megasequence III (Paleogene) depositional cycle and were lowered into the oil window in Miocene time, when the coastal parts of the basin experienced the greatest amount of subsidence. The tectono-eustatic pulses of the Tertiary brought about source and reservoir strata into a spatial relationship in which hydrocarbons could be entrapped. A basement high on the continental shelf has potential for Karroo sandstone and Jurassic limestone reservoirs. Halokinesis of Middle Jurassic salt in Miocene time provides additional prospects in the offshore area. Paleogene deltaic sands occur in rotated listric fault blacks. A Miocene reef Play coincides with an Eocene source rock kitchen.

Nyagah, K.; Cloeter, J.J.; Maende, A. [National Oil Corp. of Kenya, Nairobi (Kenya)

1996-12-31

118

Hydrocarbon potential of the Lamu basin of south-east Kenya  

SciTech Connect

The Lamu basin occupies the coastal onshore and offshore areas of south-east Kenya. This fault bounded basin formed as a result of the Paleozoic-early Mesozoic phase of rifting that developed at the onset of Gondwana dismemberment. The resultant graben was filled by Karroo (Permian-Early Jurassic) continental siliciclastic sediments. Carbonate deposits associated with the Tethyan sea invasion, dominate the Middle to Late Jurassic basin fill. Cessation of the relative motion between Madagascar and Africa in the Early Cretaceous, heralded passive margin development and deltaic sediment progradation until the Paleogene. Shallow seas transgressed the basin in the Miocene when another carbonate regime prevailed. The basin depositional history is characterized by pulses of transgressive and regressive cycles, bounded by tectonically enhanced unconformities dividing the total sedimentary succession into discrete megasequences. Source rock strata occur within Megasequence III (Paleogene) depositional cycle and were lowered into the oil window in Miocene time, when the coastal parts of the basin experienced the greatest amount of subsidence. The tectono-eustatic pulses of the Tertiary brought about source and reservoir strata into a spatial relationship in which hydrocarbons could be entrapped. A basement high on the continental shelf has potential for Karroo sandstone and Jurassic limestone reservoirs. Halokinesis of Middle Jurassic salt in Miocene time provides additional prospects in the offshore area. Paleogene deltaic sands occur in rotated listric fault blacks. A Miocene reef Play coincides with an Eocene source rock kitchen.

Nyagah, K.; Cloeter, J.J.; Maende, A. (National Oil Corp. of Kenya, Nairobi (Kenya))

1996-01-01

119

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

120

Disparities in child mortality trends: what is the evidence from disadvantaged states in India? the case of Orissa and Madhya Pradesh  

PubMed Central

Introduction The Millennium Development Goals prompted renewed international efforts to reduce under-five mortality and measure national progress. However, scant evidence exists about the distribution of child mortality at low sub-national levels, which in diverse and decentralized countries like India are required to inform policy-making. This study estimates changes in child mortality across a range of markers of inequalities in Orissa and Madhya Pradesh, two of India’s largest, poorest, and most disadvantaged states. Methods Estimates of under-five and neonatal mortality rates were computed using seven datasets from three available sources – sample registration system, summary birth histories in surveys, and complete birth histories. Inequalities were gauged by comparison of mortality rates within four sub-state populations defined by the following characteristics: rural–urban location, ethnicity, wealth, and district. Results Trend estimates suggest that progress has been made in mortality rates at the state levels. However, reduction rates have been modest, particularly for neonatal mortality. Different mortality rates are observed across all the equity markers, although there is a pattern of convergence between rural and urban areas, largely due to inadequate progress in urban settings. Inter-district disparities and differences between socioeconomic groups are also evident. Conclusions Although child mortality rates continue to decline at the national level, our evidence shows that considerable disparities persist. While progress in reducing under-five and neonatal mortality rates in urban areas appears to be levelling off, polices targeting rural populations and scheduled caste and tribe groups appear to have achieved some success in reducing mortality differentials. The results of this study thus add weight to recent government initiatives targeting these groups. Equitable progress, particularly for neonatal mortality, requires continuing efforts to strengthen health systems and overcome barriers to identify and reach vulnerable groups. PMID:23802752

2013-01-01

121

The role of abiotic factors in the Cambrian Substrate Revolution: A review from the benthic community replacements of West Gondwana  

NASA Astrophysics Data System (ADS)

The Cambrian Substrate Revolution refers to a substantial and "rapid" change to the nature of marine sedimentary substrates in the early Cambrian and is widely interpreted as a biologically-driven event, a direct response to evolutionary innovations in metazoan burrowing and the development of new shelly faunas. However, abiotic factors such as tectonic and climatic evolution also had the potential to restructure Cambrian substrates, and are here shown to be more plausible drivers of change in the benthic faunas of western Gondwana. The western Mediterranean region underwent a southward drift during Cambrian times, which drove a switch from subtropical carbonates to temperate siliciclastic substrates with short-term episodes of temperate carbonate productivity. As a result, microbial and shelly carbonates disappeared diachronously in a stepwise manner across the lower-middle Cambrian boundary interval. Archaeocyathan-microbial reefs were replaced by chancelloriid-eocrinoid-(spiculate) sponge meadows, in which the stepwise immigration of new echinoderm taxa was primarily controlled by extensional tectonic events, first recorded in rifting settings and later in passive-margin platforms. Availability of new kinds of substrate was thus the primary factor that controlled where and when evolutionary innovations in benthic strategies arose. Examples of this include the early Cambrian colonization of phosphatic hardgrounds and thrombolite crusts by chancelloriids, archaeocyathan and spiculate sponges, and the exploitation by benthos to the increasingly widespread availability of shelly grounds and carbonate firmgrounds by early-diagenetic cementation. A microbial mat/epifaunal antagonistic relationship is demonstrated for echinoderm pelmatozoans based on the non-overlapping palaeogeographic distributions of microbial reefs and mats versus mud-sticker pelmatozoans. Cambrian benthic communities thus evolved in parallel with substrates in response to abiotic factors rather than being the primary drivers of substrate change.

Álvaro, J. Javier; Zamora, Samuel; Clausen, Sébastien; Vizcaïno, Daniel; Smith, Andrew B.

2013-03-01

122

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

123

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

124

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

125

Structure and metamorphism of the granitic basement around Antananarivo: A key to the Pan-African history of central Madagascar and its Gondwana connections  

NASA Astrophysics Data System (ADS)

The Precambrian basement of Madagascar acquired a polyphase imprint during the Pan-African orogeny. In northern central Madagascar, emplacement of stratoid alkaline granites at midcrustal depth (4-5 kbars) led to formation of a layered crust in a postcollisional extensional regime at 630 Ma (D1). Subsequently, the structures of the stratoid granites were rotated by the sinistral and transpressive E-W Antananarivo flexure (or virgation) zone (D2). East of Antananarivo the structures of the D1 layered crust and the D2 virgation are crosscut by the steeply dipping N-S foliations of the Angavo belt. Lineations gently plunging to the north attest that the Angavo belt is a major strike-slip shear zone that formed under low-pressure granulitic conditions (3 kbars, 790°C). The nearby porphyritic Carion granite was emplaced at the end of this period of N-S shearing (D3), which can thus be no younger than 530 Ma. Late-Pan-African (580-550 Ma) strike-slip motion along broadly N-S shear zones has been recognized elsewhere in Madagascar and in its Gondwana connections. Continuation of the Angavo belt as one of the high strain belts of the Arabian-Nubian Shield is discussed in the general framework of Gondwana assembly.

NéDéLec, Anne; Ralison, Bruno; Bouchez, Jean-Luc; GréGoire, Vincent

2000-10-01

126

Comparison of the Jurassic and Cretaceous sedimentary cycles of Somalia and Madagascar: implications for the Gondwana breakup  

Microsoft Academic Search

The Jurassic and Cretaceous sedimentary history of northern Somalia and the Morondava Basin of south-western Madagascar have been studied. Both regions display an independent facial development; however, a comparison of the sequential evolution of the Mesozoic sedimentary successions in these two presently widely separated areas reveals a surprisingly high level of similarity, which probably reflects major events during the disintegration

Peter Luger; M. Gröschke; M. Bussmann; A. Dina; W. Mette; A. Uhmann; H. Kallenbach

1994-01-01

127

Evidence for Late Ordovician glaciation of Al Kufrah Basin, Libya  

NASA Astrophysics Data System (ADS)

Fieldwork at the flanks of Al Kufrah Basin, Libya, reveals that Late Ordovician ice sheets were present in the eastern Sahara and that they extended northeastward toward Egypt. Evidence for grounded ice sheets is preserved at the both the southeastern (Jabal Azbah) and northern (Jabal az-Zalmah) basin margins. Characteristic soft-sediment deformation structures, including soft-sediment folds, small-scale faults and striated pavements indicate subglacial shearing and the formation of glacial erosion surfaces. These findings support the presence of a Late Ordovician ice margin in the eastern Sahara and add vital new constraints to reconstructions of the morphology of North African grounded ice sheets. Prior to our study, there existed two plausible models on ice sheet geometry. The first was that separate ice sheets - namely a north and west African ice sheet and an Arabian ice sheet - extended over this part of western North Gondwana. The second was that ice cover was continuous. The presence of a suite of subglacially-generated deformation structures adds considerable credence to the latter interpretation.

Le Heron, Daniel Paul; Howard, James

2010-09-01

128

New 40ar\\/39ar Radiometric, Geochemistry And Structural Data On The Giant Okavango Mafic Dike Swarm And Lava-flows From The Karoo Province In Botswana: Implications For Gondwana Break-up  

Microsoft Academic Search

The lower Jurassic Karoo magmatism represents one of the most important conti- nental flood basalt (CFB) provinces of the Phanerozoic. It is dominated by tholeiites occurring as traps and apparently radiating giant dike swarms and is associated with the disruption of Gondwana and the opening of the Indian Ocean. The Karoo volcanic province located at the South-East of the African

F. Jourdan; G. Tshoso; G. Féraud; H. Bertrand; B. Legall; J. J. Tiercelin; A. B. Kampunzu

2002-01-01

129

The Peary Plateau, fragment of Gondwana (barrier in the oceanic gates of the Western Antarctica in the Scotia Sea): A part of the earth’s bipolar climatic machine  

Microsoft Academic Search

Marine geological-geophysical research in 1998? 2005, processing of the materials gathered in 2004? 2005, and compilation of a new bathymetric chart led to the discovery of the Peary underwater plateau or bank (hereafter, Peary Plateau), a large fragment of Gondwana, in the Scotia Sea (Southern Ocean). This fragment played the role of a barrier in the oceanic gates of Western

G. B. Udintsev; G. V. Shenke; A. Beier; A. V. Kol’tsova; L. G. Domoratskaya; A. F. Beresnev; N. A. Kurentsova; D. E. Teterin; V. G. Udintsev

2006-01-01

130

A Study on Ground Water Resource Management in Gondwana Formations in Western Part of West Godavari District Andhra Pradesh India  

NASA Astrophysics Data System (ADS)

Groundwater source forms nearly fifty percent of the total irrigation in the country. With green revolution, there has been an increasing demand for water for agricultural and this led to overexploitation of groundwater resources in many parts of the state and the study area is not an exception. With the success of groundwater exploration and development through deep tube wells in the study area, the farmers plunged into hectic activity of tapping groundwater. The present study was taken up to assess to groundwater recharge and draft in the area and to suggest remedial measures to redress overexploitation condition. The study area is underlain by a vide range of geological formations from Archean to Tertiary age. Crystallines consist of two-tier setting of aquifers with weathered and fracture zones. The Gondwana formations with Sandstone, shale and clay zones form unconfined to confined aquifer system. Deccan trap basalt occurs subsurface in some parts. Crystalline aquifers are exploited through borewells with a depth range of 29 to 101.5 m. Static water levels range in depth from 2.5 and 19.27 m bgl. Their yields range from 2.53 to 19.27 m3/hr. Sedimentary aquifers are exploited through tube wells with a depth range of 18 to 293 m and static water levels range from 2.1m agl to 48.0 m bgl. Yields of the wells vary form 1.3 to 67 m3 /hr. Groundwater is lifted by monoblock pumpsets of 5 HP in some places but mostly by submersible pumpsets with 5 to 12.5 HP. The tube wells are subjected to pumping from 5 to 18 hours per day depending on availability of electricity (power supply). They are operated form 90 days to throughout the year in different places. Groundwater development in the study area shows a steady increase since 1960 with number of tube wells uniformly increasing in each decade, from an initial figure of 592 wells in 1960 to 17,173 tube wells in 2002. Crop pattern was shifted from dry crops to paddy and sugar cane as major crops and irrigated dry crops like maize, tobacco, palm oil, garden crops in minor extent and coconut was planted in large extents. Piezometric surface shows uniform gradient over the entire area indicating hydraulic continuity between different geological formations. The water budgeting was computed by using norms recommended by GEC (Ground Water Estimation Committee) of CGWB 1997, Govt. of India. For the present study, June 2000 to May 2001 period is taken as groundwater year. Groundwater recharge is calculated (formation wise) by rainfall infiltration and water table fluctuation methods, and recharge from other sources reservoirs, tanks, canals, irrigation water returns etc. the total recharge comes to be 626 MCM. Groundwater draft for irrigation and domestic purposes is found to be 994.96 MCM. Groundwater balance shows overdraft by 364.15 MCM. Well density is increased from <1/Sq. km in 60s to >30/Sq.km in 2000. Piezometric surface profiles in N-S direction also show a drop from 1960 to 2000 year by 44m. Taking into consideration, the mined water during 1990-2000, the overdraft comes to 704 MCM i.e. 70.4 MCM/year. Groundwater draft in the study area is found to be 2.85 times more than the actual requirement (342 MCM) of the crops in the area due to highly permeable sandy soils. In view of the alarming imbalance in the groundwater recharge and draft, some management practices are suggested to restore the original groundwater condition which includes proper well spacing, artificial recharge, change of cropping pattern and irrigation methods to suit to the local conditions. Quality of groundwater is suitable for drinking and agricultural purposes.

Singara, S.

2006-05-01

131

Paleozoic tectonism on the East Gondwana margin: Evidence from SHRIMP U-Pb zircon geochronology of a migmatite-granite complex in West Antarctica  

NASA Astrophysics Data System (ADS)

The Fosdick Mountains migmatite-granite complex in West Antarctica records episodes of crustal melting and plutonism in Devonian-Carboniferous time that acted to transform transitional crust, dominated by immature oceanic turbidites of the accretionary margin of East Gondwana, into stable continental crust. West Antarctica, New Zealand and Australia originated as contiguous parts of this margin, according to plate reconstructions, however, detailed correlations are uncertain due to a lack of isotopic and geochronological data. Our study of the mid-crustal exposures of the Fosdick range uses U-Pb SHRIMP zircon geochronology to examine the tectonic environment and timing for Paleozoic magmatism in West Antarctica, and to assess a correlation with the better known Lachlan Orogen of eastern Australia and Western Province of New Zealand. NNE-SSW to NE-SW contraction occurred in West Antarctica in early Paleozoic time, and is expressed by km-scale folds developed both in lower crustal metasedimentary migmatite gneisses of the Fosdick Mountains and in low greenschist-grade turbidite successions of the upper crust, present in neighboring ranges. The metasedimentary rocks and structures were intruded by calc-alkaline, I-type plutons attributed to arc magmatism along the convergent East Gondwana margin. Within the Fosdick Mountains, the intrusions form a layered plutonic complex at lower structural levels and discrete plutons at upper levels. Dilational structures that host anatectic granite overprint plutonic layering and migmatitic foliation. They exhibit systematic geometries indicative of NNE-SSW stretching, parallel to a first-generation mineral lineation. New U-Pb SHRIMP zircon ages for granodiorite and porphyritic monzogranite plutons, and for leucogranites that occupy shear bands and other mesoscopic-scale structural sites, define an interval of 370 to 355 Ma for plutonism and migmatization. Paleozoic plutonism in West Antarctica postdates magmatism in the western Lachlan Orogen of Australia, but it coincides with that in the central part of the Lachlan Orogen and with the rapid main phase of emplacement of the Karamea Batholith of the Western Province, New Zealand. Emplaced within a 15 to 20 million year interval, the Paleozoic granitoids of the Fosdick Mountains are a product of subduction-related plutonism associated with high temperature metamorphism and crustal melting. The presence of anatectic granites within extensional structures is a possible indication of alternating strain states ('tectonic switching') in a supra-subduction zone setting characterized by thin crust and high heat flow along the Devonian-Carboniferous accretionary margin of East Gondwana.

Siddoway, Christine S.; Fanning, C. Mark

2009-11-01

132

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

133

Basin analysis in the Illinois basin  

SciTech Connect

In April 1989, the Illinois State Geological Survey and the Indiana and Kentucky Geological surveys formed the Illinois Basin Consortium (IBC) for the purpose of advancing the geologic understanding of the Illinois basin and of developing basin-wide studies for the assessment and wise development of the Illinois basin energy, mineral, and water resources. Cooperative efforts include work on the AAPG Interior Cratonic Sag Basin volume, Springfield coal study, Paducah CUSMAP study in cooperation with the US Geological Survey, Illinois Basin Cross Section Project, Geologic Society of America Coal Division field trip and workshop on Lower Pennsylvanian geology, workshops in basin analysis, and the Tri-State Committee on correlations in the Pennsylvanian System of the Illinois Basin. A network of 16 regional surface to basement cross sections portraying the structural and stratigraphic framework of the total sedimentary section of the entire basin is in preparation. Based on more than 140 of the deepest wells with wireline logs, the sections will show formation boundaries and gross lithofacies of the entire stratigraphic column. A set of basin-wide maps shows structure, thickness, and coal quality of the economically important Springfield coal seam. These maps were generated from recently joined computerized databases of the three member surveys of IBC. A unified stratigraphic nomenclature of the Pennsylvanian System is being developed, including seven new members and seven new formation names. The goal is to simplify, standardize, and gradually improve the stratigraphic terminology to be used in the Illinois basin.

Leighton, M.W. (Illinois State Geological Survey, Champaign (USA)); Haney, D. (Kentucky Geological Survey, Lexington (USA)); Hester, N. (Indiana Geological Survey, Bloomington (USA))

1990-05-01

134

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.

135

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

136

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

137

Major strike-slip faulting along the tectonic boundary between East and West Antarctica: implications for early Gondwana break-up and Jurassic granitic magma emplacement  

NASA Astrophysics Data System (ADS)

The fragmentation of the Gondwana supercontinent began with continental rifting between the Weddell Sea region of Antarctica and South Africa during the Jurassic. This initial Jurassic phase of continental rifting is critical for understanding the process that initiated supercontinent breakup and dispersal, including the role of mantle plumes and major intracrustal tectonic structures. However, due to the remote location and blanketing ice sheets, the tectonic and magmatic evolution of the Weddell Sea Sector of Antarctica has remained relatively poorly understood. Our recent aeromagnetic and airborne gravity investigations have revealed 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 (a possible exotic microcontinent derived from the Natal Embayment, or the Shackleton Range region of East Antarctica) from East Antarctica (Jordan et al., 2013 Tectonophysics). In this study we use GPlates plate-tectonic reconstruction software to start evaluating the influence of strike-slip faulting between East and West Antarctica on Gondwana breakup models. Specifically, we investigate the possibility of poly-phase motion along the fault system and explore scenarios involving more diffuse strike slip faulting extending into the interior of East Antarctica in the hinterland of the Transantarctic Mountains. Our preliminary models suggest that there may be a link between the prominent step in the flank of the later Cretaceous-Cenozoic West Antarctic Rift System (at the southern end of Ellsworth-Whitmore Block) and the earlier Jurassic Weddell Sea rift system. Additionally, we present preliminary joint 3D magnetic and gravity models to investigate the crustal architecture of the proposed strike-slip fault system and assess its influence on the emplacement of voluminous Jurassic granitic magmatism along the boundary of the Ellsworth-Whitmore block.

Jordan, T. A.; Ferraccioli, F.; Anderson, L.; Ross, N.; Corr, H.; Leat, P. T.; Bingham, R.; Rippin, D. M.; Le Brocq, A. M.; Siegert, M. J.

2013-12-01

138

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

139

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

140

The oldest sediments of Greece revealed by detrital zircon LA-ICP-MS U-Pb dating: Cambro-Ordovician sandstones from northern Gondwana in the External Hellenides - implications on the evolution of the eastern Mediterranean  

NASA Astrophysics Data System (ADS)

Detrital zircon U-Pb ages of a quartzite from the Feneos locality of Peloponnesus, S. Greece, were determined by LA-ICPMS. The rock classifies as a mature quartz arenite and belongs to an original shale-sandstone succession now metamorphosed into a phyllite-quartzite unit. The latter chiefly represents the External Blueschist Belt of the Hellenides widely known as the Arna or Phyllite - Quartzite (PQ) Unit. Zircon age clusters at 0.5-0.75, 0.85, 0.95-1.1, 1.75-2 and 2.4-3 Ga point at the Saharan Metacraton and the Transgondwanan Supermountain as contributing sources; the youngest concordant grain is 522 Ma old. Based on great similarities in lithology, zircon age-distribution patterns and depositional setting between the Feneos quartzite and intact Cambro-Ordovician sandstone-shale sequences of Libya (Murzuq and Kufrah basins) we propose that the protolith of the former was deposited in an epeiric sea north of Libya during the Cambro-Ordovician. Feneos, as part of the Cimmerian block, had become detached from the NE Gondwanan margin during Late Carboniferous - Early Permian times and drifted northward. In central Crete, similar-looking sequences (Galinos beds) were originally deposited in an accretionary/fore-arc complex outboard of the south Laurussian active margin (Pelagonia) between ~297-230 Ma. The southern Pelagonian margin eventually collided (mild docking) with the northward drifting Cimmerian block signaling the closure of Palaeotethys by early Late Triassic. The Gondwanan affinity of the Feneos quartzite strongly contrasts the European one of the Galinos beds; the suture of Palaeotethys can thus be traced in S. Greece within the pre-Triassic sedimentary sequences of Peloponnesus and Crete. In the eastern Mediterranean realm, rocks with similar age clusters crop out in Greece (Peloponnesus, this study; eastern Crete, Sfaka locality; north-central Macedonia, Vertiskos terrane), NW Turkey (central Sakarya terrane), Libya (Murzuq and Kufrah basins), Israel (Elat locality) and Jordan (El-Quweira locality). Their zircon age spectra plotted with respect to sediment depositional age indicate a collisional margin setting for all. Evaluating the depositional setting of the arguably similar sedimentary sequences above we demonstrate their common provenance from the Gondwana Super-fan System which draped the northern Gondwanan periphery from ~525 to 460 Ma (Lower Cambrian - Middle Ordovician). Using as anchoring points the non-metamorphosed Early Palaeozoic outcrops of Libya and the Middle East that remained intact at their original deposition sites we have traced, in space and time, the path of the remainder time- and facies-equivalent rocks presently cropping out in the Hellenic and Turkish mountain belts. The fate of the northern Gondwanan margin was multiple rifting and travelling of the fragments thereof throughout the Palaeozoic before their final incorporation into younger orogenic belts.

Kydonakis, Konstantinos; Kostopoulos, Dimitrios; Poujol, Marc; Brun, Jean-Pierre; Papanikolaou, Dimitrios; Paquette, Jean-Louis

2013-04-01

141

Depositional evolution of permo-triassic karoo basins in Tanzania with reference to their economic potential  

NASA Astrophysics Data System (ADS)

The Karoo basins of Tanzania contain in excess of 3000 m of sediments which were preserved in several NNE-NE striking half grabens or other structural basin conditions. They are all intracratonic basins, most of which filled with terrestrial sediments. In some basins situated nearer the coastal region short marine incursions occurred in the Late Permian. The Ruhuhu Rasin in SW Tanzania provides a typical depositional sequence of a Karoo basin in eastern Africa. Sedimentation commenced with glacigene deposits. These are of Late Carboniferous to Early Permian age and may be equated with other glacial successions in Africa and elsewhere in Gondwana. The glacigene beds are overlain by fluvial-deltaic coal-bearing deposits succeeded by arkoses and continental red beds. A transitionary formation of carbonaceous shales with impure coals gradually develops into thick lacustrine series which are topped by Late Permian bone bearing beds. The Triassic is characterized by a very thick fluvio-deltaic succession of siliciclastics resting with regional unconformity on the Permian. This Early Triassic sequence exhibits well-developed repetitive depositional cycles. Current azimuth measurements indicate fluctuating flow regimes in the Early Permian but relative stable source areas to the west of the basin later on. The depositional evolution of the Ruhuhu Basin is controlled by both tectonic and climatic factors. During basin evolution important energy resources were deposited such as considerable reserves of coal and source rocks of moderate potential for hydrocarbon generation. Uranium enrichment is observed in the Triassic arenaceous series where diagenetic alterations and subsequent cementation processes led to the formation of laumontite. Post Karoo dykes and plugs had only local effect on thermal evolution of potential source rocks. Enrichments of elements, i.e., Nb, Zr, Rb, Cr, and V present additional exploration targets. A comparison with the Karoo basins of the coastal region indicates possible lithological correlation by the application of sequence stratigraphy. No early Permian deposits are exposed in the coastal Karoo basins but their existence within the deeper parts of these basins cannot be ruled out. There, composition of organic matter analysed so far suggests subsidence and heat exposure exceeding post maturity stage.

Kreuser, T.; Wopfner, H.; Kaaya, C. Z.; Markwort, S.; Semkiwa, P. M.; Aslandis, P.

142

Provenance of the Lower Paleozoic Balcarce Formation (Tandilia System, Buenos Aires Province, Argentina): Implications for paleogeographic reconstructions of SW Gondwana  

NASA Astrophysics Data System (ADS)

Lower Paleozoic moderately sorted quartz-arenites from the Balcarce Formation deposited in eastern Argentina (Tandilia System) comprise mainly detrital material derived from old upper crustal material. The sources were magmatic, sedimentary, and subordinated felsic metamorphic terranes. High concentrations of tourmaline and Ti-rich heavy minerals, including zircon and nearly euhedral chromite, are common. Trace element concentrations (Nb, Cr) on rutile indicate pelitic and metabasaltic sources, respectively. Major element analyses on chromites indicate a basic volcanic protolith of mid-oceanic ridge origin, which was exposed close to the depositional basin. The delivery of chromite may be associated with convergent tectonics causing the consumption and obduction of oceanic crust during pre-Upper Ordovician times. The oblique/orthogonal collision of the Precordillera Terrane with the western border of the Rio de la Plata Craton, west of the Balcarce Basin or source further to the east from a Lower Palaeozoic extensional basin are possibilities. Geochemical and petrographic data exclude the underlying Precambrian and Cambrian sedimentary rocks as dominant sources, and favour the basement of the Río de La Plata Craton, including Cambrian rift-related granites of South Africa and the Sierras Australes (eastern Argentina), as main suppliers of detritus. Trace element geochemistry of recycled pyroclastic material, associated with the quartz-arenites, also suggests volcanic arc sources. The provenance of the pyroclastic material may either be the Puna-Famatina arc, located in north and central Argentina, or a hypothetical active margin further to the south. These ash layers are equivalent in age to volcanic zircons found in the Devonian Bokkeveld Group in western South Africa. The deposition of a glacial diamictite of Hirnantian age (Sierra del Volcán Diamictite) is interpreted as a member of the Balcarce Formation. Based on the stratigraphic re-location of the glacial diamictite and trace fossils, the Balcarce Formation is considered here to be Ordovician to Silurian in age. The Balcarce Formation can be correlated with similar rocks in South Africa, the Peninsula Formation, and the upper Table Mountain Group (Windhoek and Nardouw subgroups), including the Hirnantian glacial deposit of the Pakhuis Formation.

Zimmermann, Udo; Spalletti, Luis A.

2009-07-01

143

Santa Barbara Basin Los Angeles Basin  

E-print Network

Santa Barbara Basin 100 km Los Angeles Basin Effects of Faults On Coastal Groundwater Salinity of California, Santa Barbara Dr. Hilario Camacho SHP Ltd., Long Beach, CA Mr. Byeongju Jung Tufts University ( www.earthscope.org) Cost: ~$USD 120M #12;Santa Ynez Mountains, Santa Barbara #12;B Major Faults

Einat, Aharonov

144

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

145

Transtensional tectonics induced by oblique reactivation of previous lithospheric anisotropies during the Late Triassic to Early Jurassic rifting in the Neuquén basin: Insights from analog models  

NASA Astrophysics Data System (ADS)

The goal of this study was to determine the main factors that controlled the kinematic evolution and the structural architecture developed during the Late Triassic to Early Jurassic rifting that led to the opening of the Neuquén basin in the southwestern sector of Gondwana. We carried out a series of analog models to simulate an extensional system with a bent geometry similar to the northeastern border of the basin. In different experiments, we varied the extension direction between NNE (N10°E) and NE (N45°E) orientations, inducing rift systems with different degrees of obliquity in each sector of the extended area. We compared the kinematic evolution and the final structural architecture observed in the experiments with data from two selected representative areas of the basin: (1) the Atuel depocenter, situated in the northern Andean sector, and (2) the Entre Lomas area, situated in the northeastern Neuquén Embayment. In both cases, the good match between the field and subsurface data and the results of the analog models supports a NNE orientation of the regional extension (N30°E-N20°E) during the synrift stage. Our experimental results suggest that lithospheric weakness zones of NNW to NW trend could have controlled and localized the extension in the Neuquén basin. These previous anisotropies were linked to the sutures and rheological contrasts generated during the collision of terranes against the southwestern margin of Gondwana during the Paleozoic, as well as further modifications of the thermo-mechanical state of the lithosphere during the Late Paleozoic to Early Mesozoic evolution.

Bechis, Florencia; Cristallini, Ernesto O.; Giambiagi, Laura B.; Yagupsky, Daniel L.; Guzmán, Cecilia G.; García, Víctor H.

2014-09-01

146

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

147

Petrology of the eclogites from western Tasmania: Insights into the Cambro-Ordovician evolution of the paleo-Pacific margin of Gondwana  

NASA Astrophysics Data System (ADS)

Eclogite facies rocks along the Paleozoic active margin of Gondwana are rare. They are limited to isolated segments of Northern Victoria Land (Antarctica), western Tasmania, and southeastern Australia. New petrological data for mafic rocks and their host garnet-kyanite schists from the Franklin Metamorphic Complex (western Tasmania) permit reconstruction of six main stages of mineral growth for the eclogite. Stages I and II occurred at greenschist/amphibolite-facies conditions (ca. 500-600 °C; 0.55-0.7 GPa for stage II) before attaining high-pressure conditions (at ? 600-650 °C; > 1.5 GPa for stage III). The following stages, IV and V, record the decompression from high-pressure conditions to amphibolite-facies (ca. 500-600 °C; 0.4-1.0 GPa). Finally, stage VI represents the late greenschist-facies retrogression. However, the pelitic schist surrounding the eclogite records only the medium-pressure amphibolite-facies stage. The P- T evolution over time outlines a clockwise path that is quite steep in both the prograde and retrograde segments. The latter shows a nearly isothermal decompression between the eclogite and the high-pressure amphibolite-facies stage IV, which was achieved at deep crustal levels (? 30 km), and a final decrease in both pressure and temperature from deep/intermediate to shallow crustal levels, with a typical cooling-unloading path. The lack of a complete re-equilibration during the different stages and the high d P/d T for both the prograde and retrograde paths are indicative of a rapid burial and initially rapid exhumation. The similarity of the mafic whole-rock chemical composition, including N, T to E-MORB and of the peak metamorphic age (? 500 Ma) between the Tasmanian eclogites and the UHP rocks from Northern Victoria Land, supports the idea that they formed in the context of the same contractional event. However, the different P- T conditions and d P/d T point to different tectono-metamorphic settings for the two sectors of the paleo-Pacific margin of Gondwana during the Ross/Tyennan orogeny.

Palmeri, R.; Chmielowski, R.; Sandroni, S.; Talarico, F.; Ricci, C. A.

2009-05-01

148

Petrology and fluid inclusions of garnet-clinopyroxene rocks from the Gondwana suture zone in southern India: Implications for prograde high-pressure metamorphism  

NASA Astrophysics Data System (ADS)

The Palghat-Cauvery Suture Zone (PCSZ) in the southern granulite terrane, India, which separates Pan-African granulite blocks (e.g., Madurai and Trivandrum Blocks) to the south and Archean terrane (e.g., Salem Block and Dharwar Craton) to the north is regarded as a major suture zone in the Gondwana collisional orogeny. It probably continues westwards to the Betsimisaraka suture in Madagascar, and eastwards into Sri Lanka and possibly into Antarctica. The available geochronological data including U-Pb zircon and EPMA monazite ages indicate that the rocks along the PCSZ underwent an episode of high-grade metamorphism at ca. 530 Ma that broadly coincides with the time of final assembly of the Gondwana supercontinent. Recent investigations on high-grade metamorphic rocks in this region have identified several new occurrences of garnet-clinopyroxene rocks and associated meta-gabbros from Perundurai, Paramati, Aniyapuram, Vadugappatti, and Mahadevi areas in Namakkal region within the central domain of the PCSZ. They occur as elongated boudins of 1 m to 1 km in length within hornblende-biotite orthogneiss. The garnet-clinopyroxene mafic granulites contain coarse-grained (up to several cm) garnet (Alm30-50 Pyr30-40 Grs10-20) and clinopyroxene (XMg = 0.70-0.85) with minor pargasite, plagioclase (An30-40), orthopyroxene (hypersthene), and rutile. Garnet and clinopyroxene are both subidioblastic and contain few inclusions of clinopyroxene (in garnet) and plagioclase. Orthopyroxene occur only as Opx + Pl symplectite between garnet and clinopyroxene in almost all the localities, suggesting the progress of decompressional reaction: Grt + Cpx + Qtz => Opx + Pl, which is a dominant texture in the PCSZ. The prograde mineral assemblage of the rocks is therefore inferred to be Grt + Cpx + Qtz, although quartz was probably totally consumed by the progress of the reaction. The metamorphic P-T calculations using Grt-Cpx-Pl-Qtz geothermobarometers yield T = 850-900°C and P >13 kbar, which is consistent with the occurrence of high-pressure Mg-rich staurolite in Mg-Al-rich rocks from this region. Fluid inclusion study of some garnet-clinopyroxene rock samples identified CO2-rich fluid inclusions trapped as primary phases within garnet, suggesting that prograde high-pressure metamorphism was dominated by CO2-rich fluids. The results therefore confirmed that the PCSZ underwent regional dry high-pressure metamorphism followed by the peak ultrahigh-temperature event probably associated with the continent-continent collisional and suturing history along the PCSZ.

Tsunogae, T.

2012-04-01

149

The Huqf Supergroup of Oman: Basin development and context for Neoproterozoic glaciation  

NASA Astrophysics Data System (ADS)

The Huqf Supergroup of the Sultanate of Oman provides important information on the geological evolution of the Arabian-Persian Gulf region during a protracted period of continental dispersal and reassembly on the periphery of the Gondwanan supercontinent during the Neoproterozoic, and also provides important constraints on the nature of extreme climate swings during this critical period in the evolution of Earth's biosphere. The Huqf Supergroup spans the period ca. 725-540 Ma, and is composed of three groups. The Abu Mahara Group ( ca. 725 to < 645 Ma) hosts two glacial successions separated by an interval of non-glacial, deep to shallow marine sedimentary rocks. The base of the overlying Nafun Group ( ca.< 645-547 Ma) is marked by a transgressive post-glacial carbonate, which initiates an overstepping of basement-cored structural highs and the deposition of an extensive blanket of carbonate and siliciclastic stratigraphy. The Ara Group ( ca. 547-540 Ma), which is known mostly from the subsurface, comprises carbonates, evaporites and organic-rich shales, with interbedded ashes, deposited in a large number of N-S trending troughs and platforms. The three groups of the Huqf Supergroup correspond to three phases of basin development. The Abu Mahara Group was deposited on an eroded crystalline and metasedimentary basement. An early stage of basin formation preserved < 1.5 km of marginal to deeper marine sedimentary rocks, including an older Cryogenian glacial succession infilling erosional palaeovalleys. Renewed tectonic subsidence associated with submarine volcanism allowed the preservation of a > 1 km-thick, cyclical, rift basin-fill of glacial and non-glacial sedimentary rocks representing a younger Cryogenian icehouse epoch. Progressively older source areas were exhumed during the interval ca. 725 to < 645 Ma, with unroofed 800+ Ma granitoid plutons providing the bulk of sediment, supplemented by syn-extension volcanics, and eventually by distant Meso- and Palaeoproterozoic sources. The wide extent of the Nafun Group, basin-wide correlation of major lithostratigraphic units, and its modest thickness (˜ 1 km) suggest a period of thermal contraction following Abu Mahara rifting. The Oman area was probably a region of slightly stretched continental lithosphere (which passed to the NE into a passive continental margin), occupied by a continental margin rim basin during deposition of the Nafun Group. The Nafun Group bears little resemblance to the coeval small basin-fills choked with calc-alkaline volcanic detritus in the Arabian Shield, but the correlation of the Nafun Group with the Jibalah Group indicates that the contiguous continental rim basin extended from Oman across the tectonically deformed eastern fringe of the Arabian-Nubian Shield. Inundation of the Arabian Shield area and incorporation within the Nafun basin was probably facilitated by extensional collapse and tectonic escape. Sources for 600-640 Ma zircons, found in the Nafun Group, can readily be identified in the Arabian-Nubian Shield. Renewed volcanism, compartmentalization of the basin by N-S trending structural highs and troughs, and an increase in sediment accumulation rates, typifies the Ara Group. The Ara Group deposits formed part of an extensive, latitudinal evaporite belt, with a depocentre translated outwards relative to the Nafun basin, suggesting continuing tectonic progradation of the eastern margin of the Arabian-Nubian Shield. Subduction of ocean floor along the former passive continental margin along the periphery of eastern Gondwana is the most likely cause of Ara volcanism and tectonism, in which case the Oman area can be viewed as occupying a retro-arc setting at this stage, between a subducting margin and the East African orogen. Coeval calc-alkaline plutons and rhyolitic to andesitic volcanics are found in the Central Iranian Terrane. Neoproterozoic glaciations are recorded in the rift and passive margin stratigraphy predating the final amalgamation of continental fragments into greater Gondwana. In Oman, glaciation w

Allen, Philip A.

2007-10-01

150

Palaeomagnetic re-investigation of Early Permian rift basalts from the Baoshan Block, SW China: constraints on the site-of-origin of the Gondwana-derived eastern Cimmerian terranes  

NASA Astrophysics Data System (ADS)

A palaeomagnetic investigation was carried out on a series of rift basalts (Woniusi Formation) that accumulated on the Baoshan block (SW China) in the Early Permian, the aim being to provide quantitative palaeogeographical information on the eastern Cimmerian terrane as it detached from eastern Gondwana. Reliable data were obtained from four locations/28 individual cooling units, and when combined with the findings of an earlier study (three locations/19 sites) indicate that breakup occurred at 41.9°S (with errors, 34.2-51.2°S). Using this information, we fit Baoshan against Gondwana within a narrow longitudinal belt close to where northeast Greater India and northwest Australia were once in close proximity. Furthermore, we suggest that Sibumasu (Simao-Burma-Malyasia-Sumatra; the largest of the eastern Cimmerian blocks) lay directly to the east, offshore of Australia; Qiangtang and Lhasa almost certainly sat to the west (off northern Greater India-SE Arabia), but we are uncertain as to their exact configuration. Our findings are compared with several rather different models that have been published in recent years. The new palaeomagnetic constraint highlights the flexibility authors currently have in reconstructing the region, principally because of the overall lack of similar high-quality data from the various blocks. We explain how new data could resolve these ambiguities, thereby offering more robust explanations for eastern Gondwana's late Palaeozoic development.

Ali, Jason R.; Cheung, Haz M. C.; Aitchison, Jonathan C.; Sun, Yadong

2013-05-01

151

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

152

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

153

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

154

PICEANCE BASIN Conservation Action Plan  

E-print Network

PICEANCE BASIN Conservation Action Plan 2011 Update Dudley Bluffs bladderpod © B.Jennings Piceance ............................................................................................................................... 1 II. Vision and Goals for the Piceance Basin........................................................................... 2 IV. Piceance Basin Priority Action Area and Associated Rare Plants

155

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

156

CentralBasin Matador Arch Eastern  

E-print Network

BASIN SALINAS- HALF MOON BASIN WYTHRUSTBELT UINTA - PICEANCE BASIN GREATER GREEN RIVER BASIN PARADOX PROVINCE GULF MESOZOIC OCS PROVINCE BIGHORN BASIN WIND RIVER BASIN POWDER RIVER BASIN PERMIAN BASIN DENVER & hillshade (1 km cells) from ESRI, Inc. Ocean bathymetry is 2-minute gridded Global Relief data (ECTOPO2

157

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)...

158

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

159

Processing and interpretation of seismic reflection data from Ogaden basin, Ethiopia  

SciTech Connect

The Ogaden basin is believed to be an extensional basin created during the early rifting of Gondwana and the development of the western Indian Ocean. Preliminary studies conducted by various oil companies and national geoscientists suggest that the area is prospective for hydrocarbon accumulation. Prior to these studies, however, very little was known of the surface geology in this area and virtually nothing was known of the subsurface. The objectives of the study were to implement state-of-the-art seismic and gravity data processing and interpretation techniques in order to identify structural and/or stratigraphic trap sequences and indicate their significance in the hydrocarbon exploration of the basin. In this study, high resolution multi-channel reflection seismic data, acquired in 1993 from the Ogaden Basin, are used. The data were acquired for Hunt Oil Company using Vibroseis as an energy source. Various data enhancement techniques were applied to these data in order to produce an interpretable final seismic section for the identification of possible hydrocarbon habitats. These included discrimination and filtering of coherent noise from the signal, enhancing, focussing of the identified reflectors and static corrections. Statics solutions from shallow wells and automatic refraction statics were compared, with the best results obtained when automatic refraction solutions were applied. Our study has revealed various reflection horizons that can be potential stratigraphic traps at pinch outs and may be porous strata which are terminated by lateral transitions or interconnected lines of either elastic sediments or carbonates. We discuss these results in the light of gravity modelling designed to estimate maximum sediment thickness along the line.

Tadesse, K.; Ebinger, C.J.; Clark, R.A. (Univ. of Leeds (United Kingdom))

1996-01-01

160

Processing and interpretation of seismic reflection data from Ogaden basin, Ethiopia  

SciTech Connect

The Ogaden basin is believed to be an extensional basin created during the early rifting of Gondwana and the development of the western Indian Ocean. Preliminary studies conducted by various oil companies and national geoscientists suggest that the area is prospective for hydrocarbon accumulation. Prior to these studies, however, very little was known of the surface geology in this area and virtually nothing was known of the subsurface. The objectives of the study were to implement state-of-the-art seismic and gravity data processing and interpretation techniques in order to identify structural and/or stratigraphic trap sequences and indicate their significance in the hydrocarbon exploration of the basin. In this study, high resolution multi-channel reflection seismic data, acquired in 1993 from the Ogaden Basin, are used. The data were acquired for Hunt Oil Company using Vibroseis as an energy source. Various data enhancement techniques were applied to these data in order to produce an interpretable final seismic section for the identification of possible hydrocarbon habitats. These included discrimination and filtering of coherent noise from the signal, enhancing, focussing of the identified reflectors and static corrections. Statics solutions from shallow wells and automatic refraction statics were compared, with the best results obtained when automatic refraction solutions were applied. Our study has revealed various reflection horizons that can be potential stratigraphic traps at pinch outs and may be porous strata which are terminated by lateral transitions or interconnected lines of either elastic sediments or carbonates. We discuss these results in the light of gravity modelling designed to estimate maximum sediment thickness along the line.

Tadesse, K.; Ebinger, C.J.; Clark, R.A. [Univ. of Leeds (United Kingdom)

1996-12-31

161

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

Marshall, Jeff

162

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

163

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...

164

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

165

Lower Ipswich River basin  

USGS Publications Warehouse

The lower Ipswich River basin is that part of the Ipswich River drainage basin below the Geological Survey stream-gaging station at South Middleton in northeastern Massachusetts (fig. 1). It includes about 110 square miles between the gaging station at South Middleton and the Atlantic Ocean. This report presents basic data collected as part of an investigation of the geology and ground-water resources of the lower Ipswich River basin, Massachusetts by the U.S. Geological Survey in cooperation with the Massachusetts Department of Public Works. The data have been prepared for release in order to make available to the public basic ground-water data that will be useful in the planning of water-resources development. An earlier Basic-Data Report (Baker and Sammel, 1961) presents data pertaining to ground-water conditions in the upper part of the Ipswich River basin (the Wilmington-Reading area).

Sammel, Edward A.; Baker, John A.

1962-01-01

166

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

167

Lake Superior Rift basins  

NASA Astrophysics Data System (ADS)

Sedimentary basins of late Precambrian age have been identified beneath Lake Superior using seismic reflection profiles leased by Argonne National Laboratory, Argonne, Ill., from Grant Norpac, Inc. [McGinnis et al., 1989]. These data, along with 650 km of Great Lakes International Multidisciplinary Program for Crustal Evolution (GLIMPCE) profiles [Behrendt et al., 1988], are being used to develop an understanding of failed rift processes, from initial plate separation, through basin evolution, to final quiescence.

McGinnis, L. D.

168

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

169

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

170

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

171

Closed Basin Modes of a Dual Basin Harbour  

NASA Astrophysics Data System (ADS)

Closed basin seiches have been studied in Port Kembla, Australia, a compound harbour comprising two basins linked by a narrow channel. Despite the irregular geometry, there are well defined closed basin resonances which may be excited by long waves incident on the harbour entrance. The March 2011 Japanese tsunami excited open-basin modes, but did not significantly excite closed-basin modes. This is attributed to the very low incident wave energy at those frequencies. While the direct forcing of a closed basin mode has been extensively studied, the indirect forcing via an independent open-basin mode found here has not been extensively studied. It was found that single basin modes are more readily excited than the higher dual basin harmonics and the role of the irregular geometry in inhibiting some modes is discussed. The non-linear generation of a higher frequency mode unrelated to the forcing mode is demonstrated.

Hinwood, Jon; Luick, John

2013-11-01

172

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

173

Mechanics of forearc basins  

NASA Astrophysics Data System (ADS)

In this study, the mechanics of forearc basins will be the object of a numerical investigation to understand the relationships between wedge deformation and forearc basin formation. The aim of this work is to gain an insight into the dynamics of the formation of the forearc basin, in particular the mechanism of formation of accommodation space and the preservation of basin stratigraphy. Our tool is a two-dimensional numerical model that includes the rheological properties of the rock, including effective internal friction angle, effective basal friction angle and thermally-dependent viscosity. We also simulate different sedimentation rates in the basin, to study the influence of underfilled and overfilled basin conditions on wedge deformation. The stratigraphy of the basin will also be studied, because in underfilled conditions the sediments are more likely to undergo tectonic deformation due to inner wedge deformation. We compare the numerical model with basins along the Sunda-Java Trench. This margin shows a variety of structural-settings and basin types including underfilled and overfilled basins and different wedge geometries. We interpret and document these structural styles, using depth migrated seismic sections of the Sunda Trench, obtained in three surveys, GINCO (11/98 - 01/99), MERAMEX (16/09/04 - 7/10/04) and SINDBAD (9/10/06 - 9/11/06) and made available through the IFM-GEOMAR and the Bundesanstalt für Geowissenschaften and Rohstoffe (BGR). One important aspect of these margins that we observe is the presence of a dynamic backstop, characterized by older accreted material, that, although deformed during and after accretion, later becomes a stable part of the upper plate. We argue that, following critical wedge theory, it entered into the stable field of a wedge either by steepening or weakening of the underlying detachment. As a stable wedge, this older segment of the wedge acts as a mechanical backstop for the frontal deforming wedge. This dynamic backstop moves seaward in time, in response to isostatic loading by the growing wedge, or due to seaward retreat of the slab with a consequent steepening of the base of the wedge.

Cassola, Teodoro; Willett, Sean D.; Kopp, Heidrun

2010-05-01

174

Ecosystems of Lake Sevan Basin’s Rivers in Armenia  

E-print Network

Abstract—Taking into account the importance of Lake Sevan and Lake Sevan basin’s rivers for Armenian economy, the main goals of our investigations were the documentation of water quality and the biodiversity of invertebrates developed in Lake Sevan basin’s rivers and selected tributaries. Moderately satisfied ecological condition for the biodiversity of Lake Sevan basin’s rivers has been established, and the changes in species ’ composition of zoobenthos in Lake Sevan were detected. A growing tendency of antibiotic resistance among E. coli isolates in water resources has been shown. Keywords—Biodiversity, ecosystem, Lake Sevan, water-quality, zoobenthos.

Eugenie A. Kachvoryan; Astghik Z. Pepoyan; Maria V. Harutyunova; Anahit M. Manvelyan

175

The Sacta Limestone Member (early Wenlock): Cool-water, temperate carbonate deposition at the distal foreland of Gondwana's active margin, Bolivia  

Microsoft Academic Search

The Sacta Limestone Member is located towards the base of the Silurian Kirusillas Formation in central Bolivia, and forms part of the sedimentary record of the Peru–Bolivia Palaeozoic Basin. The early Wenlock (Sheinwoodian) age of this thin carbonate unit has been established by conodont and foraminifer biostratigraphy. During the Silurian, a thick siliciclastic wedge was deposited in the foredeep of

Enrique Díaz-Martínez

2007-01-01

176

Evolution and petrogenesis of Gondwanan volcanism from ashes within the Ecca and Beaufort Groups: Karoo Basin, South Africa  

NASA Astrophysics Data System (ADS)

Within the Permian-Jurassic Karoo basin of South Africa, the turbidite fan to shelf deposits of the Ecca Group and overlying fluvial complex of the Beaufort Group preserve numerous ash beds that were deposited along the southern margin of Gondwana. Currently the location and origin of the volcanic center that generated these ash beds remains uncertain, as is the relationship between the tectonic setting of the magmatic system and the subsidence mechanism of the Karoo basin itself. U-Pb geochronological studies using SHRIMP-RG at the Stanford-USGS Microanalysis Center have focused on zircon separated from 25 ash beds in order to provide chronostratigraphic markers to constrain the timing of deposition within the Karoo basin. For 13 of these samples, rare earth element (REE) concentrations of zircon spot analyses were also determined. Because trivalent REEs are fractionated as a function of magma genesis and magmatic evolutionary processes, REE element compositions of zircons within ashes can be used to assess the petrogenesis and chemistry of the magmatic source and to determine the tectonic setting. One current hypothesis posits that the Permian Karoo ash beds were sourced from arc-related magmatism along the southern margin of Gondwana, although little evidence of this arc remains. U/Yb vs. Hf and U/Yb vs. Y cross-plots indicate Karoo zircon lie primarily within the field associated with continental magmatic settings with some overlap into the oceanic magmatic field. This compares with results from analysis of 20 whole rock samples by XRF and XRD that suggest ash samples are bentonites with a composition that is generally dacitic. However, whole rock data compositional variability could either be due to element mobilization during transport and burial, or mixing of bentonitic ash with hemipelagic terrigenous detritus; detrital mixing is also indicated in some geochronology samples by a prevalence of reworked pre-Permian zircon. Together these results are consistent with ash generation by a magmatic system likely associated with mixing of mantle-derived magma with partial continental crustal melts, and could be associated with a mantle plume/rift from a within-plate magmatic setting or a continental magmatic arc associated with subducting oceanic crust. Modeling to test the compatibility of zircon geochemistry with magma genesis in these settings is underway.

Mckay, M. P.; Weislogel, A. L.; Rawcliffe, H.; Brunt, R.; Hodgson, D. M.; Flint, S.

2011-12-01

177

Nam Con Son Basin  

SciTech Connect

The Nam Con Son basin is the largest oil and gas bearing basin in Vietnam, and has a number of producing fields. The history of studies in the basin can be divided into four periods: Pre-1975, 1976-1980, 1981-1989, and 1990-present. A number of oil companies have carried out geological and geophysical studies and conducted drilling activities in the basin. These include ONGC, Enterprise Oil, BP, Shell, Petro-Canada, IPL, Lasmo, etc. Pre-Tertiary formations comprise quartz diorites, granodiorites, and metamorphic rocks of Mesozoic age. Cenozoic rocks include those of the Cau Formation (Oligocene and older), Dua Formation (lower Miocene), Thong-Mang Cau Formation (middle Miocene), Nam Con Son Formation (upper Miocene) and Bien Dong Formation (Pliocene-Quaternary). The basement is composed of pre-Cenozoic formations. Three fault systems are evident in the basin: north-south fault system, northeast-southwest fault system, and east-west fault system. Four tectonic zones can also be distinguished: western differentiated zone, northern differentiated zone, Dua-Natuna high zone, and eastern trough zone.

Tin, N.T.; Ty, N.D.; Hung, L.T.

1994-07-01

178

Integrated Salt Basin Evaluation  

NASA Astrophysics Data System (ADS)

Salt tectonics plays a major role in the development of many sedimentary basins. Basins containing salt thus frequently display a complex geodynamic evolution characterized by several phases of halokinesis and associated sedimentation. One classic area of salt tectonics is the Central European Basin System (CEBS). Here, the mobile Permian Zechstein salt formed a large number of salt structures such as anticlines, diapirs, pillows, sheets, stocks, and walls during an extended period of salt tectonic activity in Mesozoic and Cenozoic times. Major changes in sedimentation patterns and structural regimes are associated and common in this setting. Increasingly complex subsurface evaluation therefore requires an approach to study salt basins including analogue and numerical models, field studies and laboratory studies which combine seismic, structural and sedimentary studies with analysis of rheological properties, and geomechanic modelling. This concept can be demonstrated using case studies from Permian Salt Basins in Europe and the Late Neoproterozoic to Early Cambrian South Oman Salt Basin. There salt-influenced sedimentary responses to renewed phases of tectonism can be clearly discerned from detailed sequence analysis based on seismic and log data combined with retrodeformation modelling studies. High quality 3-D seismic data integrated with structural modelling improves the definition of the internal dynamics of salt structures and associated sediment architecture in salt-controlled sequences. Paleo-caprocks inside the diapirs point to long phases of dissolution. Salt wedges formed by extrusion and lateral flow of salt glaciers during periods of diapir emergence and reduced sediment accumulation can be accurately modelled. Although salt is widely regarded as a perfect seal, it can become permeable for one- or two-phase fluids under certain conditions of fluid pressure, temperature and deviatoric stress. The fluid pathways can be either along zones of diffuse grain boundary dilatancy, or along open fractures, depending on the fluid overpressure and deviatoric stress.

Kukla, P. A.

2012-04-01

179

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

180

Identifying glacial influences on sedimentation in tectonically-active, mass flow dominated arc basins with reference to the Neoproterozoic Gaskiers glaciation (c. 580 Ma) of the Avalonian-Cadomian Orogenic Belt  

NASA Astrophysics Data System (ADS)

Neoproterozoic 'Avalonian-Cadomian' volcanic arc basins once lay peripheral to Gondwana and are now found around the North Atlantic Ocean in New England, Atlantic Canada and northwestern Europe as 'peri-Gondwanan terranes.' Their thick (up to 9 km) marine fills are dominated by turbidites, debrites (diamictites and variably graded conglomerates), slumps and olistostromes recording the dominance of mass flow processes in arc basins oversupplied with volcaniclastic sediment. Several diamictite horizons in these basins were identified as glacial tillites more than one hundred years ago on the basis of poor textural sorting, and the lack of any understanding of mass flow processes. An association with thin-bedded turbidite facies, then interpreted as glaciolacustrine varvites, was seen as evidence for widespread glacial conditions which is still the basis today of a near global 'Gaskiers glaciation' at c. 580 Ma, despite classic sedimentological work which shows that the 'tillites' and 'varvites' of these basins are deep marine sediment gravity flow deposits. Only in two basins (Gaskiers Formation, Avalon Peninsula in Newfoundland, and the Konnarock Formation of Virginia) is a distal and regionally-restricted glacial influence on marine sedimentation identified from ice-rafted, striated dropstones in turbidites but terrestrial 'ice-contact' facies are absent. As revealed in this study, terrestrial glacial facies may not have survived frequent volcanic activity such as seen today on glaciated active plate margin volcanoes such as Mount Rainier in Washington USA, and Cotopaxi Volcano in Ecuador where primary glacial sediment is frequently reworked by lahars, pyroclastic flows, debris avalanches and outburst floods. The weight of evidence presented in this study indicates that ice covers during the Gaskiers glaciation were not widespread across the Avalonian-Cadomian back arc basins; the deep marine Grenada Basin (Caribbean Sea) filled with turbidites, debrites (lahars) and debris avalanches from the adjacent Lesser Antilles Arc is identified here as a modern analogue for these ancient basins.

Carto, Shannon L.; Eyles, Nick

2012-06-01

181

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

182

Colby Fire over LA Basin  

... NASA Spacecraft Sees Dispersion of Smoke and Ash Across LA Basin from Colby Fire     View ... 2,000 people, and sent smoke and ash across the Los Angeles Basin, prompting an air quality alert by public health officials. The ...

2014-05-15

183

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

184

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.

185

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.

186

Magmatism coeval with lower Paleozoic shelf basins in NW-Argentina (Tastil batholith): Constraints on current stratigraphic and tectonic interpretations  

NASA Astrophysics Data System (ADS)

The Tastil batholith (Eastern Cordillera, NW Argentina) holds relevant keys for interpreting the tectonic evolution of the Central Andes basement since it has always been interpreted as the subcrop of the Cambrian and Lower Ordovician basins in the Eastern Cordillera. However, in the Angosto de la Quesera section, the batholith intrudes sandstones underlying a fossiliferous Lower Tremadocian conglomerate containing Tastil granite pebbles. The precise assignation of the sandstones intruded by the granite to Cambrian Mesón Group or to the Uppermost Cambrian-Lower Tremadocian Santa Victoria Group is a key for refining the relationships between magmatic and sedimentary units. The ages of 526 Ma and 517 Ma (U/Pb, zircons) obtained from two facies of the batholith are coherent with the proposal of including these sandstones in the Mesón Group. However, the lithologic features and fossil content point to an affinity with the basal units of the Santa Victoria Group according to sedimentologic and stratigraphic studies ruled out by other authors. The intrusive relationships between the Tastil batholith and the Lower Paleozoic sandstones indicates the batholith is coeval with the Mesón and/or Santa Victoria groups basins instead of being its subcrop, which strongly contradicts previous proposals about basement evolution along the Lower Paleozoic margin of Gondwana. Therefore, the genesis and emplacement of the Tastil batholith must be related to the development of the Lower Paleozoic shelf basins rather than with the final stages of Puncoviscana-type basin evolution. The basement of central and northern Argentina records a wide spectrum of sedimentary, deformational, magmatic and metamorphic processes at a variety of crust levels during the Early Paleozoic. Tastil batholith emplacement and exhumation in the Eastern Cordillera represent shallower crustal expressions of the plutonic and high-T-low-P metamorphic events at deeper levels in the basement now exposed mainly in eastern Puna and Pampean Ranges.

Hongn, Fernando D.; Tubía, José M.; Aranguren, Aitor; Vegas, Néstor; Mon, Ricardo; Dunning, Gregory R.

2010-03-01

187

Controls on rifting in Africa and the regional tectonic model for the Nigeria and East Niger rift basins  

NASA Astrophysics Data System (ADS)

Since early Mesozoic times, three phases of rifting have occurred in Africa and are related to distinct phases of breakup of Gondwana. These contrasting rift episodes have provided an insight to the extent to which plate tectonic processes and more localised mechanical anisotropy processes within the African lithosphere have influenced rifting. Gravity modelling of the Nigeria and East Niger rift basins shows the extent and nature of the broad (regional) positive Bouguer anomaly associated with these rifts. The removal of this regional anomaly allows the delineation of the (residual) negative Bouguer anomaly which reflects the lateral extent and thickness of Mesozoic and Cenozoic sediments. This residual anomaly is interpreted using iterative three dimensional modelling, by incorporating a density-depth function derived from well logs. Results indicate that an extensive basin complex exists in eastern Niger with sedimentary sections greater than 7 km in depth and are in good agreement with the aeromagnetic data. A simple estimate of crustal extension across the East Niger rift basin indicates that up to 58 km of crustal stretching has occurred, placing an upper limit on the amount of sinistral strike-slip movement required within the Benue Trough to open the East Niger rift. A similar strike-slip and extension rift geometry is observed elsewhere in the West and Central African rift system which indicates that the Cretaceous period was an important time for strike-slip tectonics. Changes in the differential opening of the Central and South Atlantic Oceans during the Cretaceous can adequately explain the large strike-slip displacements and associated rift basins in West and North Central Africa and are considered here to more closely reflect the initial rift processes that shaped the continental margin of Africa than those associated with the modern East African rift system.

Fairhead, J. D.; Green, C. M.

188

Tectonic evolution of the Colorado Basin, offshore Argentina, inferred from seismo-stratigraphy and depositional rates analysis  

NASA Astrophysics Data System (ADS)

Based on a dense 2D seismic reflection dataset and information from 8 exploration wells, we reinterpreted the stratigraphic evolution of the Colorado Basin. The basin is located on the continental shelf and slope within 50 to 2250 m of bathymetry. The total sediment fill can be up to 16,000 m. Seismic-to-well log correlations provide a chrono-stratigraphic framework for the interpreted seismic sequences. We show that the Colorado Basin records the development of a Permian pre-rift period, a Triassic/Jurassic to Early Cretaceous rift phase and a Lower Cretaceous to Tertiary drift phase. This passive margin represents the evolution of lithospheric extension from active rifting to the thermal subsidence/drift stage. Several Cretaceous to Cenozoic slumping episodes were identified and related to progradation of the sequences and sediment build-up in the slope, as well as to the development of seaward dipping extensional faults. Assuming an accumulation time span of 25 Ma for the syn-rift succession, which corresponds to the duration of extensional phases preceding the final break-up of the South Atlantic, sedimentation rates are in the order of 118 m/Ma. By Late Cretaceous, the Gondwana break-up had stopped in almost all areas and post-rift thermal subsidence dominated the basin development. During the early phase of subsidence, high sedimentation rates of up to 122 m/Ma are recorded. An important decrease of sediment supply (30 m/Ma) occurred until the end of the sag phase during the deposition of the Colorado Formation and sedimentation took place in elongated depocenters with oceanward progradation. A second phase of increased sediment supply takes place during the Oligocene and Miocene, resulting in the development of large basinward prograding sedimentary wedges. This event seems to be associated to the interaction between continental dynamics, subsidence, and increased continental erosion during climate shift from greenhouse to icehouse conditions.

Loegering, M. J.; Anka, Z.; Autin, J.; di Primio, R.; Marchal, D.; Rodriguez, J. F.; Franke, D.; Vallejo, Eduardo

2013-09-01

189

Contrasting Permo - Carboniferous Evolution of Resita and Sirinia - Presacina Basins (South Carpathians, Romania); an overview.  

NASA Astrophysics Data System (ADS)

Two important Permo-Carboniferous molasses basins Resita and Sirinia - Presacina occur in Romanian Banat (south-western part of Carpathian chain), unconformable overlie the Getic and Danubian domains with different pre-Variscan and Variscan geodynamic history. They show differences in their lithology reflecting various geotectonic settings and evolutions. In the Resita domain the Upper Carboniferous deposits (Westphalian - Stephanian in age, according to the previous paleobotanic and palynological data) are important in volume and they contain terrigeneous siliciclastic rocks represented by sandy - conglomerate and argillaceous - sandy rocks variable in thickness with siltstone, carbonaceous shale and coal beds interlayering. There are not volcanic rocks present in Upper Carboniferous of Resita domain. In contrast with Resita in the Sirinia - Presacina basins the Upper Carboniferous deposits are volumetrically more restrictive. These deposits transgresively overlie pre-Sudetian formations and consist of continental - lacustrine terrigeneous formations, rarely associated with limnic carbonatic rocks. In this association the alternating conglomerate, siliceous sandstone, siltstone and clay with lens - like coal inter-layers prevails. In two small areas Dragosela - Tulinecea - Camenita (in the western part) and Baia Noua - Cucuiova (in the eastern part) the terrigeneous deposits are associated with basaltic andesite and andesite rocks with alkaline affinity. In both of these basins the Lower Permian deposits (according to the paleobotanic data) unconformably overlie the Upper Carboniferous formations and/or pre-Sudetian basements. The Lower Permian deposits in the Resita basin occur in two superposed formations (Nastaseanu, 1987): (1) Walchia Beds dominated by black argillaceous shales, slightly bituminous with rare sandy-conglomerate interlayers and (2) Red Beds composed by sandy-conglomerate deposits with some argillaceous intercalations, all red in color, with rarely lens-like fresh water limestone. During the Permian in the Resita basin the volcanic activity was absent. In the Sirinia - Presacina basin the Lower Permian deposits are characterized by huge volcanic and volcano - sedimentary assemblages inter-fingering with red beds detritic formations. The Permian volcanism in the Sirinia - Presacina basin is dominant rhyolitic and started in subaqueous conditions. Early subaqueous domes (as isolated or as clusters) and lava flows led to the generation at their margins of huge volume of hyaloclastic breccias that turn unstable forming marginally turbiditic hyaloclastite aprons. In the Sirinia zone, where the magmas get to the shallower waters and/or to subaerial, the volcanic activity turned progressively to be explosive, generating phreatomagmatic eruptions. The result of this activity is up to several hundred meters of various deposits represented by pyroclastic flow (dominantly non-welded and welded ignimbrites), pyroclastic surge and fall out, all rich in accretionary lapilli. At the distal, marginal part of the volcanic environs the epiclastic, mostly lahar deposits are dominating, sometimes including layers of fallout deposits with accretionary lapilli that suggest their contemporaneous deposition. In the eastern part of Sirinia - Presacina basin (Cucuiova Hill) the presence of basalts as sills in the Permian sandstone deposits may be a sign of bimodal magmatic activity. As in the some of the Central Europe Permian basins the volcanic activity from Sirinia - Presacina basin is related to intra-basinal active faults and in particular with the intersection of fault systems having a pull-apart features (e.g. Stollhofen et al., 1999). The most important factor which was controlled the Permo - Carboniferous complex evolution of the Western and Central Europe was tectonic. The continue convergence between Laurasia and Gondwana during the Upper Carboniferous - Lower Permian (Ziegler, 1990) was generated a conjugate dextral - sinistral shear fault system adjacent to the Tornquist - Teisseyre Line, which induced the fragment

Tatu, M.; Seghedi, I.; Nutu, L. M.; Nicolae, I.

2009-04-01

190

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 to 9000 years the St. Lawrence River­Great Lakes system has played an important role in the lives of many

Thorp, James H.

191

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

192

Aeromagnetic signatures reveal a back-arc basin imposed upon the inherited rifted margin of the East Antarctic craton  

NASA Astrophysics Data System (ADS)

The Wilkes Subglacial Basin (WSB) represents a largely unexplored, approximately 1400 km-long and up to 600 km-wide subglacial depression, buried beneath the over 3 km-thick East Antarctic Ice Sheet. During the 2005-06 austral summer an extensive aerogeophysical survey was flown to investigate the WSB adjacent to northern Victoria Land (NVL), and included the acquisition of new airborne radar, aeromagnetic and aerogravity data. Several contrasting models for the origin of the basin have been previously proposed, and are based primarily on relatively sparse gravity data. These range from Cenozoic flexure, to distributed crustal extension of unknown age (possibly Mesozoic to Cenozoic), and even compression along the margin of craton. Our recent aeromagnetic data reveal that the basin is structurally controlled and has a tectonic origin, at least adjacent to NVL. The eastern margin of the basin is imposed upon an Early Paleozoic thrust fault belt, which can be traced under the ice using aeromagnetic signatures from exposures in Oates Land and the Ross Sea coast. Aeromagnetic patterns reveal that the western margin of the basin is imposed upon a Proterozoic-age shear zone mapped in the Mertz Glacier, and that is interpreted from geological studies to represent the continuation of a coeval shear zone in Australia. The broad aeromagnetic and satellite magnetic low over the WSB contrasts with the high over the un-reworked Proterozoic craton to the west of the basin, and is interpreted to reflect Neoproterozoic-age sediments deposited along the rifted margin of the craton. Magnetic intrusions within the WSB are interpreted as back-arc plutons that formed later in response to Cambrian-Ordovician age subduction along the paleo-Pacific margin of Gondwana. The aeromagnetic interpretation for a former broad back-arc basin in the WSB is supported by the occurrence of low-grade metasedimentary rocks of back-arc affinity in Oates Land, and also by the similarity in long-wavelength magnetic anomaly signatures of the WSB and the back-arc mobile belt of the North American Cordillera.

Armadillo, E.; Ferraccioli, F.; Jordan, T. A.; Bozzo, E.

2009-12-01

193

Impact basin relaxation at Iapetus  

NASA Astrophysics Data System (ADS)

We investigate impact basin relaxation on Iapetus by combining a 3D thermal evolution model (Robuchon, G., Choblet, G., Tobie, G., Cadek, O., Sotin, C., Grasset, O. [2010]. Icarus 207, 959-971) with a spherical axisymmetric viscoelastic relaxation code (Zhong, S., Paulson, A., Wahr, J. [2003]. Geophys. J. Int. 155, 679-695). Due to the progressive cooling of Iapetus, younger basins relax less than older basins. For an ice reference viscosity of 10 14 Pa s, an 800 km diameter basin relaxes by 30% if it formed in the first 50 Myr but by 10% if it formed at 1.2 Gyr. Bigger basins relax more rapidly than smaller ones, because the inferred thickness of the ice shell exceeds the diameter of all but the largest basins considered. Stereo topography shows that all basins 600 km in diameter or smaller are relaxed by 25% or less. Our model can match the relaxation of all the basins considered, within error, by assuming a single basin formation age (4.36 Ga for our nominal viscosity). This result is consistent with crater counts, which show no detectable age variation between the basins examined.

Robuchon, Guillaume; Nimmo, Francis; Roberts, James; Kirchoff, Michelle

2011-07-01

194

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

Ford, Rick

195

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

196

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.

197

Crustal-scale heat-flow evolution and heterogeneity at a young convergent margin: Taranaki Basin, New Zealand  

NASA Astrophysics Data System (ADS)

The Taranaki Basin lies in the west of New Zealand's North Island, only 400 km away from the convergent Australian-Pacific plate margin. It is an exceptional example of a basin that documents the evolution from a passive to a convergent margin. In it's less than 100 million year history, the basin has developed from a rift margin to a hybrid intra-arc/back-arc basin/fold-thrust belt in response to propagation of Pacific plate subduction beneath the Australian plate in the region, starting 25 Myrs ago. Yet, the Taranaki Basin is surprisingly cold, given it's proximity to the subduction front: the surface heat-flow in Central North Island decreases from a staggering 800 mW/m2 at the volcanic arc to an average of 60 mW/m2 in the Taranaki Basin. These heat flow values are extreme if compared to established margins, which raises the question of how crustal temperature patterns evolve during the transition from a passive to an active margin. To answer this question, a 3D crustal scale forward model was developed, using the industry-standard basin-modelling software Petromod. The Taranaki Basin has been well studied during decades of petroleum exploration and therefore offers unique possibilities to investigate the thermal evolution of the crust and sedimentary cover in the proximity of an evolving subduction zone. The composition of mid and lower crustal rocks of the Taranaki Basin can be correlated with exhumed equivalents elsewhere in New Zealand. On average, 40% of the heat is generated within the crust, and so, the crustal composition is an important control, not only on thermal properties, but also on content of heat producing radioactive elements. In the case of the Taranaki Basin, the heat generation potential between granitic basement, related to the Mesozoic Gondwana margin in the west, and mafic and metasedimentary rocks in the east varies by a factor of up to three. The challenge of this study therefore was to differentiate between the effects of variability in heat generation due to crustal heterogeneity, and changes in heat advection and effects of tectono-sedimentary processes related to the formation of a subduction zone. The results of the model indicate that surface heat flow in the Taranaki Basin varies by as much as 20 mW/m2 due to the variability in crustal heat generation. Other individual factors such as change in mantle heat advection, tectonic subsidence, uplift and crustal thickening, and related sedimentary processes, only result in a variability of up to 10 mW/m2. The model further suggests that increased heating of the upper crust due to additional mantle heat advection related to the onset of subduction is still an ongoing process. Combined with low heat generation potential of parts of the crust and a cooling effect of crustal thickening, the lag in the additional heat transfer from the mantle explains why the surface heat-flow in the Taranaki Basin is 10-20 mW/m2 lower than in more typical back-arc areas around other Pacific plate margins.

Kroeger, Karsten F.; Bland, Kyle J.; Fohrmann, Miko; Funnell, Rob H.

2010-05-01

198

Basin-scale hydrogeologic modeling  

Microsoft Academic Search

Mathematical modeling of coupled groundwater flow, heat transfer, and chemical mass transport at the sedimentary basin scale has been increasingly used by Earth scientists studying a wide range of geologic processes including the formation of excess pore pressures, infiltration-driven metamorphism, heat flow anomalies, nuclear waste isolation, hydrothermal ore genesis, sediment diagenesis, basin tectonics, and petroleum generation and migration. These models

Mark Person; Jeff P. Raffensperger; Shemin Ge; Grant Garven

1996-01-01

199

3, 14811514, 2006 Cilician Basin  

E-print Network

Basin coastal system occupies the northeastern part of the Eastern Mediterranean Levantine Basin between- ranean between the Turkish Mediterranean coast, Syria and the island of Cyprus. The model initial model, within the nested modelling approach of the MFSTEP (Mediterranean Fore- casting System: Towards

Paris-Sud XI, Université de

200

Ichnofabric and basin analysis  

SciTech Connect

Utilization of ichnofabric indices for measuring recorded extent of bioturbation allows comparative studies of ichnofabric between different facies. In vertical sequences, measurements of ichnofabric indices can be normalized to percent of the total thickness measured for each ichnofabric index. These data can be presented as histograms, or ichnograms, when measurements are from strata deposited in a single genetically-defined sedimentary environment. Ichnograms can be used in conjunction with ichnofacies analysis to present a more complete summary of bioturbation in a sedimentary unit. Using a knowledge of the factors which contribute towards producing ichnofabric in different sedimentary environments, the range of possible ichnograms for any environment can be modeled. In addition to ichnograms, an average ichnofabric index also can be calculated as a useful summary characterization of the extent of bioturbation recorded in a sedimentary unit. Through measurement of ichnofabric indices, construction of ichnograms, and calculation of average ichnofabric index, broad-scale summary data are produced that can allow a more complete understanding of the physical and biological dynamics of sedimentary basins, especially when employed in conjunction with other basin analysis approaches.

Bottjer, D.J. (Univ. of Southern California, Los Angeles (United States)); Droser, M.L. (Univ. of California, Riverside (United States))

1991-06-01

201

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

202

Stratigraphic modeling of sedimentary basins  

SciTech Connect

A two-dimensional stratigraphic forward model has been successfully applied and calibrated in clastic, carbonate, and mixed clastic/carbonate regimes. Primary input parameters are subsidence, sea level, volume of clastics, and carbonate growth potential. Program output includes sequence geometries, facies distribution lithology distribution, chronostratigraphic plots, burial history plots, thermal and maturity histories, and crossplots. The program may be used to predict reservoir distribution, to constrain interpretations of well and seismic data, to rapidly test exploration scenarios in frontier basins, and to evaluate the fundamental controls on observed basin stratigraphy. Applications to data sets from Main Pass (US Gulf Coast), Offshore Sarawak (Malaysia), Rub'al Khali basin (Oman), Paris basin (France), and Baltimore Canyon (US East Coast) demonstrate that the program can be used to simulate stratigraphy on a basin-wide scale as well as on the scale of individual prospects.

Aigner, T. (Shell Research B. V., Rijswijk (Netherlands)); Lawrence, D.T. (Shell Development Co., Houston, TX (USA))

1990-11-01

203

Impact basin relaxation on Iapetus  

NASA Astrophysics Data System (ADS)

The evolution of the icy satellites is complex and currently poorly understood. Here we combine thermal evolution models with basin relaxation calculations to place tighter constraints on the early history of these bodies. We have coupled the results of a model for the internal evolution of Iapetus (Robuchon et al, 2010) with a computation of the surface relaxation (Zhong et al, 2003). The evolution of Iapetus is calculated using a 3D model with a temperature-dependent viscosity, while the relaxation is computed with a Maxwell viscoelastic rheology. Our relaxation model was benchmarked against the analytical results given by Melosh (1989) . At each timestep we recompute the effective ice viscosity using the parameters of Goldsby and Kohlstedt (2001). We also investigate the effect of a cutoff in effective viscosity (cf. Dombard and McKinnon, 2006). Our baseline simulation assumes 72ppb of 26Al, consistent with the results of Robuchon et al. (2010). Bigger basin relax more rapidly than smaller ones, because the inferred thickness of the ice shell of Iapetus exceeds the diameter of even the largest basins considered. Due to the cooling of Iapetus, the younger basins relax less than the older. Our results show a maximum relaxation of less than 20% for the older and bigger basins and less than 5% for the smaller. These results are in good agreement with measurements of basin depth (Schenk and Moore, 2007) assuming that basin formation occurred about 900 Myr after the formation of the Solar System. By linking models of internal evolution and basin relaxation, we can place tighter constraints on the histories of the Saturnian icy satellites. For instance, our initial results are consistent with basin formation at the time of the Late Heavy Bombardment. A critical observational requirement is the ages of the largest impact basins on the icy satellites.

Robuchon, Guillaume; nimmo, F.; roberts, J.

2010-10-01

204

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

205

Basin infill architecture and evolution from magnetostratigraphic cross-basin correlations in the southeastern Pyrenean foreland basin  

Microsoft Academic Search

Magnetostratigraphy, numerical dating, and facies mapping have been combined to provide the first cross-basin correlation of the Eocene southeastern Pyrenean foreland basin in northeastern Spain. This has enabled (1) depositional systems on the northern and south- ern margins of the basin to be dated and correlated across the basin and (2) changes in the rates of sediment accumulation in time

C. Taberner; J. Dinarès-Turell; J. Giménez; C. Docherty

1999-01-01

206

KE Basin Sludge Flocculant Testing  

SciTech Connect

In the revised path forward and schedule for the K Basins Sludge Retrieval and Disposal Project, the sludge in K East (KE) Basin will be moved from the floor and pits and transferred to large, free-standing containers located in the pits (so as to isolate the sludge from the basin). When the sludge is pumped into the containers, it must settle fast enough and clarify sufficiently that the overflow water returned to the basin pool will not cloud the water or significantly increase the radiological dose rate to the operations staff as a result of increased suspended radioactive material. The approach being evaluated to enhance sludge settling and speed the rate of clarification is to add a flocculant to the sludge while it is being transferred to the containers. In February 2004, seven commercial flocculants were tested with a specific K Basin sludge simulant to identify those agents that demonstrated good performance over a broad range of slurry solids concentrations. From this testing, a cationic polymer flocculant, Nalco Optimer 7194 Plus (7194+), was shown to exhibit superior performance. Related prior testing with K Basin sludge and simulant in 1994/1996 had also identified this agent as promising. In March 2004, four series of jar tests were conducted with 7194+ and actual KE Basin sludge (prepared by combining selected archived KE sludge samples). The results from these jar tests show that 7194+ greatly improves settling of the sludge slurries and clarification of the supernatant.

Schmidt, Andrew J.; Hallen, Richard T.; Muzatko, Danielle S.; Gano, Sue

2004-06-23

207

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

208

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

209

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

210

Cenozoic evolution of San Joaquin basin, California  

Microsoft Academic Search

The Neogene San Joaquin basin in the southern part of the 700-km long Great Valley of California is a successor to a late Mesozoic and earliest Tertiary forearc basin. The transition from forearc basin to the more restricted Neogene marine basin occurred principally during the Paleogene as the plate tectonic setting changed from oblique convergence to normal convergence, and finally

Bartow

1988-01-01

211

Drainage basin responses to climate change  

Microsoft Academic Search

Recent investigations have shown that the extent of the channel network in some drainage basins is controlled by a threshold for overland flow erosion. The sensitivity of such basins to climate change is analyzed using a physically based model of drainage basin evolution. The GOLEM model simulates basin evolution under the action of weathering processes, hillslope transport, and fluvial bedrock

Gregory E. Tucker; Rudy Slingerland

1997-01-01

212

Facies and petrophysical signature of the Tournaisian/Viséan (Lower Carboniferous) sea-level cycle in carbonate ramp to basinal settings of the Wales-Brabant massif, British Isles  

NASA Astrophysics Data System (ADS)

We studied the relationships between stratigraphic distribution of outcrop spectral gamma-ray, magnetic susceptibility and carbonate facies stacking patterns across the regionally significant transgressive-regressive cycle at the Tournaisian/Viséan boundary (Tn/V, early Carboniferous) in southern Great Britain and Ireland (South Wales, North Staffordshire and Dublin Basin). The Tn/V boundary coincides with a prominent climatic pulse connected with the Late Paleozoic glaciation of Gondwana. The aim was to correlate the gamma-ray and magnetic susceptibility log patterns in carbonate ramp- and basin settings and discuss the global/regional nature and magnitude of this transgressive-regressive cycle. A robust ramp-to-basin correlation was produced based on the log patterns, facies stacking patterns and foraminifer biostratigraphy. The concentrations of K and Th, the "clay" gamma-ray values and, partly, magnetic susceptibility are dependent on facies and show systematic changes along the inferred bathymetric profile from inner ramp to outer ramp and basin. A model of carbonate productivity-driven dilution of fine-grained siliciclastics in CaCO3 as the major control on the petrophysical patterns is discussed. The cleaning-up and cleaning-down petrophysical trends are related to down-dip and up-dip shifts of the carbonate factory with changing relative sea level. In middle-to-outer ramp and basin settings, this generates petrophysical trends just opposite to Paleozoic carbonate shelves where peaks in magnetic susceptibility are known to be associated with peak regressions. A distinct, late Tournaisian to early Viséan regressive-to-transgressive cycle with a prominent sequence boundary located close to the Tn/V stage boundary can be seen in the sections. Glacioeustatic origin of the sequence boundary is inferred from its correlation with Tn/V boundary sections from Europe, carbon isotope data from South China and the glacial deposits in the southern hemisphere mentioned by previous authors.

Bábek, Ond?ej; Kalvoda, Ji?í; Cossey, Patrick; Šimí?ek, Daniel; Devuyst, François-Xavier; Hargreaves, Simon

2013-02-01

213

Hydrocarbon accumulations in the Tarim basin, China  

Microsoft Academic Search

The Tarim basin is the largest and least explored inland basin in China. The areal extent of the basin reaches 560,000 km². The interior of the basin is mostly covered by the Takla Mekan Desert, which is about 330,000 km² in areal extent. The basin has become the object of special attention since China set aside first- and third-round onshore

Li Desheng; Liang Digang; Jia Chengzao; Wang Gang

1996-01-01

214

Tectonic framework of Turkish sedimentary basins  

SciTech Connect

Turkey's exploration potential primarily exists in seven onshore (Southeast Turkey platform, Tauride platform, Pontide platform, East Anatolian platform, Interior, Trace, and Adana) basins and four offshore (Black Sea, Marmara Sea, Aegean Sea, and Mediterranean Sea) regional basins formed during the Mesozoic and Tertiary. The Mesozoic basins are the onshore basins: Southeast Turkey, Tauride, Pontide, East Anatolian, and Interior basins. Due to their common tectonic heritage, the southeast Turkey and Tauride basins have similar source rocks, structural growth, trap size, and structural styles. In the north, another Mesozoic basin, the Pontide platform, has a much more complex history and very little in common with the southerly basins. The Pontide has two distinct parts; the west has Paleozoic continental basement and the east is underlain by island-arc basement of Jurassic age. The plays are in the upper Mesozoic rocks in the west Pontide. The remaining Mesozoic basins of the onshore Interior and East Anatolian basins are poorly known and very complex. Their source, reservoir, and seal are not clearly defined. The basins formed during several orogenic phases in mesozoic and Tertiary. The Cenozoic basins are the onshore Thrace and Adana basins, and all offshore regional basins formed during Miocene extension. Further complicating the onshore basins evolution is the superposition of Cenozoic basins and Mesozoic basins. The Thrace basin in the northwest and Adana basin in the south both originate from Tertiary extension over Tethyan basement and result in a similar source, reservoir, and seal. Local strike-slip movement along the North Anatolian fault modifies the Thrace basin structures, influencing its hydrocarbon potential.

Yilmaz, P.O. (Exxon Production Research Co., Houston, TX (USA))

1988-08-01

215

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

216

Basin analog approach answers characterization challenges of unconventional gas potential in frontier basins  

E-print Network

in exploratory basins. We developed software, Basin Analog System (BAS), to perform and accelerate the process of identifying analog basins. Also, we built a database that includes geologic and petroleum systems information of intensely studied North America...

Singh, Kalwant

2007-04-25

217

Flexural analysis of two broken foreland basins; Late Cenozoic Bermejo basin and Early Cenozoic Green River basin  

SciTech Connect

Lithospheric flexure that generates basin in a broke foreland setting (e.g., the Laramide foreland of Wyoming) is a three-dimensional system related to shortening along basin-bounding faults. The authors modeled the elastic flexure in three dimensions for two broken foreland basins: the early Cenozoic Green River basin and the analogous late Cenozoic Bermejo basin of Argentina. Each basin is located between a thrust belt and a reverse-fault-bounded basement uplift. Both basins are asymmetric toward the basement uplifts and have a central basement high: the Rock Springs uplift and the Pie de Palo uplift, respectively. The model applies loads generated by crustal thickening to an elastic lithosphere overlying a fluid mantle. Using the loading conditions of the Bermejo basin based on topography, limited drilling, and reflection and earthquake seismology, the model predicts the current Bermejo basin geometry. Similarly, flexure under the loading conditions in the Green River basin, which are constrained by stratigraphy, well logs, and seismic profiling and summed for Late Cretaceous (Lance Formation) through Eocene (Wasatch Formation), successfully models the observed geometry of the pre-Lance surface. Basin depocenters (> 4 km for the Green River basin; > 7 km for the Bermejo basin) and central uplifts are predicted to result from constructive interference of the nonparallel applied loads. Their Bermejo model implies that instantaneous basin geometry is successfully modeled by crustal loading, whereas the Green River basin analysis suggests that basin evolution can be modeled over large time steps (e.g., 20 Ma). This result links instantaneous basin geometry to overall basin evolution and is a first step in predicting stratigraphic development.

Flemings, P.B.; Jordan, T.E.; Reynolds, S.

1986-05-01

218

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

219

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.

Fryxell, Joan

220

Improved Basin Analog System to Characterize Unconventional Gas Resource  

E-print Network

potential in a target basin by finding a geological analog that has been explored enough that its resource potential is fully understood. In 2006, Singh developed a basin analog system BASIN (Basin Analog Systems INvestigation) in detail that could rapidly...

Wu, Wenyan 1983-

2012-10-02

221

Dynamic reorganization of river basins.  

PubMed

River networks evolve as migrating drainage divides reshape river basins and change network topology by capture of river channels. We demonstrate that a characteristic metric of river network geometry gauges the horizontal motion of drainage divides. Assessing this metric throughout a landscape maps the dynamic states of entire river networks, revealing diverse conditions: Drainage divides in the Loess Plateau of China appear stationary; the young topography of Taiwan has migrating divides driving adjustment of major basins; and rivers draining the ancient landscape of the southeastern United States are reorganizing in response to escarpment retreat and coastal advance. The ability to measure the dynamic reorganization of river basins presents opportunities to examine landscape-scale interactions among tectonics, erosion, and ecology. PMID:24604204

Willett, Sean D; McCoy, Scott W; Perron, J Taylor; Goren, Liran; Chen, Chia-Yu

2014-03-01

222

Oil in the Malvinas Basin  

SciTech Connect

The Malvinas Basin is petroliferous. The main source rocks are Late Jurassic and Early Cretaceous outer shelf to basinal shales known as the Pampa Rincon and Lower Inoceramus formations. Main reservoirs are fluvial and shallow-marine sandstones of the coeval Springhill Formation. On the western flank of the basin, 17 wells drilled the Cenozoic and Mesozoic column. Three of these wells discovered hydrocarbons within the Springhill Formation, and one discovered oil in Early Paleogene sandstones. Additionally, some wells recorded shows at different levels within the stratigraphic succession. A detailed overview of the drilled portion of the basin permitted the construction of a sequence stratigraphic framework, and yielded clues on a complex history of deformation. Interpretation of facies and stratal stacking and termination patterns determined that the main reservoir and source rocks were deposited in a ramp-style depositional setting. They represent the lower transgressive phase of a Late Jurassic to Early Cretaceous megasequence deposited during the early sag stage of the basin. Alternative reservoirs to the Springhill sandstones include early Paleogene glauconitic sandstones and carbonates, and Miocene deep-water turbidites. Structural trap styles include normal fault features of Jurassic to Early Cretaceous age, and compressional and inverted positive structures due to Neogene compression. Possible combination and stratigraphic traps include: little tested onlap pinchout of Late Jurassic to Early Cretaceous and Paleogene sandstones and untested erosionally truncated Paleogene sandstones; Early Paleogene carbonate buildups and Miocene deep-water turbidite mounds. The understanding of the geology of the western Malvinas Basin is the key to success of exploration in the huge frontier surrounding areas.

Galeazzi, J.S. [Astra, Anzoategui (Venezuela)

1996-08-01

223

Origin of the earth's ocean basins  

NASA Technical Reports Server (NTRS)

The earth's original ocean basins are proposed to be mare-type basins produced 4 billion y.a. by the flux of asteroid-sized objects responsible for the lunar mare basins. Scaling upward from the observed number of lunar basins for the greater capture cross-section and impact velocity of the earth indicates that at least 50% of an original global crust would have been converted to basin topography. These basins were flooded by basaltic liquids in times short compared to the isostatic adjustment time for the basin. The modern crustal dichotomy (60% oceanic, 40% continental crust) was established early in the history of the earth, making possible the later onset of plate tectonic processes. These later processes have subsequently reworked, in several cycles, principally the oceanic parts of the earth's crust, changing the configuration of the continents in the process. Ocean basins (and oceans themselves) may be rare occurrences on planets in other star systems.

Frey, H.

1977-01-01

224

Origin of the earth's ocean basins  

NASA Technical Reports Server (NTRS)

The earth's original ocean basins were mare-type basins produced 4 billion years ago by the flux of asteroid-sized objects responsible for the lunar mare basins. Scaling upwards from the observed number of lunar basins for the greater capture cross-section and impact velocity of the Earth indicates that at least 50 percent of an original global crust would have been converted to basin topography. These basins were flooded by basaltic liquids in times short compared to the isostatic adjustment time for the basin. The modern crustal dichotomy (60 percent oceanic, 40 percent continental crust) was established early in the history of the earth, making possible the later onset of plate tectonic processes. These later processes have subsequently reworked, in several cycles, principally the oceanic parts of the earth's crust, changing the configuration of the continents in the process. Ocean basins (and oceans themselves) may be rare occurrences on planets in other star systems.

Frex, H.

1977-01-01

225

H-Area Seepage Basins  

SciTech Connect

During the third quarter of 1990 the wells which make up the H-Area Seepage Basins (H-HWMF) monitoring network were sampled. Laboratory analyses were performed to measure levels of hazardous constituents, indicator parameters, tritium, nonvolatile beta, and gross alpha. A Gas Chromatograph Mass Spectrometer (GCMS) scan was performed on all wells sampled to determine any hazardous organic constituents present in the groundwater. The primary contaminants observed at wells monitoring the H-Area Seepage Basins are tritium, nitrate, mercury, gross alpha, nonvolatile beta, trichloroethylene (TCE), tetrachloroethylene, lead, cadmium, arsenic, and total radium.

Stejskal, G.

1990-12-01

226

Propagators and ridge jumps in a back-arc basin, the West Philippine Basin  

E-print Network

Propagators and ridge jumps in a back-arc basin, the West Philippine Basin Anne Deschamps,1 Ryuichi and Ocean Affairs Center, Philippines) Introduction The West Philippine Basin (WPB) is a currently inactive back-arc basin belonging to the Philippine Sea Plate (PSP). It has developed between two opposed

Demouchy, Sylvie

227

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

228

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"

229

Late Neogene Paleobathymetry, Relative Sea Level, and Basin-Margin Subsidence, Northwest San Joaquin Basin, California  

Microsoft Academic Search

The northwestern San Joaquin Basin remained near sea level throughout the late Neogene despite lying on a tectonically active basin margin. What may be inferred is that from latest Miocene through Late Pliocene deposition kept pace with basin subsidence. The late Neogene San Joaquin Basin was 175 km long, 100 km wide, and bounded by mountains to the east, south,

J. Richard Bowersox

2004-01-01

230

Snow Sublimation in the Upper Colorado River BasinColorado River Basin  

E-print Network

Snow Sublimation in the Upper Colorado River BasinColorado River Basin Morgan Phillips Department of Atmospheric Science C l d St t U i itColorado State University August 8 2013August 8, 2013 #12;Upper Colorado River Basin (UCRB)Upper Colorado River Basin (UCRB) Lee's FerryLee s Ferry Average annual Discharge 8

231

Caribbean basin framework, 4: Maracaibo basin, northwestern Venezuela  

SciTech Connect

The Maracaibo basin is presently located in a topographic depression on the Maracaibo block, a triangular, fault-bounded block within the Caribbean-South America plate boundary of northwestern Venezuela. Intense oil exploration over the last 50 years has produced a large amount of seismic and well data that can be used to constrain four Jurassic to Recent tectonic and depositional events that affected the region: (1). Late Jurassic rift phase and subsidence along normal faults striking north-northeast across the floor of the basin; (2) Cretaceous to early Eocene subsidence recorded by shallow to deep marine carbonate and clastic rocks that thicken from south to north and completely cover Permian rocks of the Merida arch; (3) Eocene folding, thrusting, and initial reactivation of Jurassic normal faults as convergent strike-slip and reverse faults. Eocene clastic sediments are thickest in a narrow northwest-trending foredeep on the northeastern margin of the basin; (4) Late Miocene to Recent northwest-southeast convergence is marked by continued reactivation of Jurassic normal faults as reverse and left-lateral strike-slip faults, uplift of mountain ranges bordering the basin, and deposition of up to 10 km of clastic sediment.

Lugo, J. (Univ. of Texas, Austin (United States))

1991-03-01

232

Multispectral Study of the Schrödinger Impact Basin  

Microsoft Academic Search

The Schrödinger impact basin is located on the lunar far side near the south pole (76oS, 134oE) and is one of only two young multiring impact basins on the lunar surface [1]. With a diameter size of 312 km and basin floor 2-3 km deep, Schrödinger is the least modified impact basin of its size. A peak ring structure 150

B. Shankar; G. Osinski; I. Antonenko; P. J. Stooke

2009-01-01

233

Late Paleozoic structural evolution of Permian basin  

Microsoft Academic Search

The southern Permian basin is underlain by the NNW-trending Central Basin disturbed belt of Wolfcamp age (Lower Permian), the deep Delaware basin to its west, and the shallower Midland basin to its eat. The disturbed belt is highly segmented with zones of left-lateral offset. Major segments from south to north are: the Puckett-Grey Ranch zone; the Fort Stockton uplift; the

Ewing

1984-01-01

234

Origin of the earth's ocean basins  

Microsoft Academic Search

The earth's original ocean basins are proposed to be mare-type basins produced 4 billion y.a. by the flux of asteroid-sized objects responsible for the lunar mare basins. Scaling upward from the observed number of lunar basins for the greater capture cross-section and impact velocity of the earth indicates that at least 50% of an original global crust would have been

H. Frey

1977-01-01

235

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

236

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

237

Aka Pygmies of the Western Congo Basin  

E-print Network

CHAPTER 2 Aka Pygmies of the Western Congo Basin The Aka Pygmies are foragers of the tropical Turnbull's (1965b) homogeneous portrayal of the Ituri forest, the western Congo Basin forest of the CAR sandstone, tertiary sandstone or alluvia, quartzite #12;Aka Pygmies of the Western Congo Basin seco! spec. T

238

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

239

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

240

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

241

The State of the Columbia River Basin  

E-print Network

The State of the Columbia River Basin FiSCal YeaR 2010 aNNUal RePORT To Congress and Citizens and fish and wildlife policy in the Columbia River Basin and to inform the public about energy and fish in the Columbia River Basin in Fiscal Year 2010, as well as information about salmon and steelhead returns

242

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

243

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

244

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

245

Typologies and Classification of Great Basin Pottery  

E-print Network

II Typologies and Classification of Great Basin Pottery A New Look at DeathValley Brown Wares je-g;J.therer pottery in the Great Basin are rarely more than descriptive accounts of the number, :md occasionally va-g;J.therer pottery from one small region in the Great Basin, Death Valley (see figure rI.I) is revisited. From ehe

246

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

247

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...

248

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...

249

Waters of the Makarov and Canada basins  

Microsoft Academic Search

Hydrographic measurements from the 1994 Arctic Ocean Section show how the Makarov and Canada basins of the Arctic Ocean are related, and demonstrate their oceanographic connections to the Eurasian Basin. The inflow into the Makarov Basin consists largely of well-ventilated water within a broad band of densities from a boundary flow over the Siberian end of the Lomonosov Ridge. The

J. H. Swift; E. P. Jones; K. Aagaard; E. C. Carmack; M. Hingston; R. W. MacDonald; F. A. McLaughlin; R. G. Perkin

1997-01-01

250

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

251

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

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 of a Strategic Plan, Implementation Framework, and Implementation Strategies for anadromous fish, resident fish

253

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

254

Comparative analysis of the Late Cretaceous to Recent post-breakup basin evolution of the South-American and South-African margin of the southern Atlantic  

NASA Astrophysics Data System (ADS)

Recently, considerable attempts have been made to compare the sedimentary basin evolution and the associated tectonic framework on both sides of the South-Atlantic (e.g. Mohriak et al., 2008, and references therein). Yet there are still unresolved questions. Amongst the most striking observations is that multiple phases of volcanism, uplift and subsidence are recorded after the break-up of the southern South Atlantic margin segment on both sides of the Florianopolis - Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup continental margin successions. However, the tectono-sedimentary and magmatic styles markedly differ from south to north across the volcanic complex. In seismic reflection data, voluminous extrusives are manifested by the occurrence of large wedges of seaward dipping reflector sequences south of the volcanic complex, whilst large volumes of Cretaceous mafic alkaline rocks only occur north of the Florianopolis - Walvis Ridge complex. It can be expected that these differences are of a broad importance for the understanding of both break-up and post-breakup processes. This presentation focuses on a comparison of the post-breakup stratigraphic development of the South American and South African continental margins that both record thick post-rift sedimentary successions. Basins along the southern African margin are much narrower in comparison to their South American counterparts, constituting a pronounced margin asymmetry across the Atlantic. Adding to the heterogeneity of the system, the northernmost segment of the South Atlantic rift and salt basins is also characterized by a pronounced asymmetry, with the Brazilian margin now comprising narrower and deeper rift basins with less salt than the Congo-Gabon conjugate margin. In general, it seems that in the salt-prone areas both offshore South America and southern Africa, salt-related tectonics are amongst the key parameters controlling differential post-rift margin development, adding significant complexity to the conjugate margin systems. Mohriak, W., Nem?ok M. & Enciso, G. (2008): South Atlantic divergent margin evolution: rift-border uplift and salt tectonics in the basins of SE Brazil. In: Pankhurst R.J., Trouw, R.A.J., Brito Neves, B.B. & De Wit, M.J. (eds) West Gondwana: pre-cenozoic correlations across the South Atlantic region. Geological Society, London, Special Publications, 294, 365-398.

Kukla, Peter; Back, Stefan

2010-05-01

255

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

256

New 40ar/39ar Radiometric, Geochemistry And Structural Data On The Giant Okavango Mafic Dike Swarm And Lava-flows From The Karoo Province In Botswana: Implications For Gondwana Break-up.  

NASA Astrophysics Data System (ADS)

The lower Jurassic Karoo magmatism represents one of the most important conti- nental flood basalt (CFB) provinces of the Phanerozoic. It is dominated by tholeiites occurring as traps and apparently radiating giant dike swarms and is associated with the disruption of Gondwana and the opening of the Indian Ocean. The Karoo volcanic province located at the South-East of the African continent, covers a surface of about 3x106 km2. Whereas most of the geochronological and geochemical studies were per- formed in the Southern part of the province, very few data are available in the NW. This is particularly the case for lava flows and for the N110 oriented, 1500 km long and 100 km wide giant Okavango Dike Swarm (ODS) of Botswana. Lava-flows were sampled in a 800 m deep borehole located in the SE of Botswana and consist in low- Ti tholeiites. ODS dolerites are characterized mainly by augite and plagioclase with remnants of olivine and are high UTi tholeiites (TiO2> 2 wt%) enriched in LREE relative to HREE (La/Ybn = 3.5-9.7). 40Ar/39Ar plateau ages ranging from 177.3 s´ 2.1 (2 sigma) Ma (-58m deep) to 178.0 s´ 2.2 Ma (-719m deep), and from 178.3 s´ 1.1 Ma to 179.3 s´ 1.2 Ma have been obtained on pure plagioclase separates for the lava-flows and the ODS, respectively. No significant age variation could be identified along the 661m thick lava-flow section, but these lava-flows are slightly younger than both ODS dikes and high-Ti lava-flows from Zimbabwe (Jones et al., 2000, GC, v.2, p110). However, all these basaltic events (both low- and high- Ti) from the north- ern Karoo sub-province appear significantly younger than the southern low-Ti Karoo formations, particularly if we consider 40Ar/39Ar dates obtained only on plagioclase separates, yielding ages which range between 180.3 s´ 1.8 and 184.7 s´ 0.7 Ma (Duncan et al., 1997, Jour. Geoph. Res., v. 102, p18127). Therefore, a time-related northwards migration of the magmatism is suggested. Moreover, one dated ODS dike yields Pro- terozoïc age, suggesting that this ODS branch of the so-called triple junction structure, generally attributed to the Karoo mantle plume, may be at least partly due to injection and rejuvenation of inherited Proterozoïc basement structures.

Jourdan, F.; Tshoso, G.; Féraud, G.; Bertrand, H.; Legall, B.; Tiercelin, J. J.; Kampunzu, A. B.

257

Keuper stratigraphic cycles in the Paris basin and comparison with cycles in other peritethyan basins (German basin and Bresse-Jura basin)  

NASA Astrophysics Data System (ADS)

High-resolution sequence stratigraphy of the Keuper, Paris Basin, is used to establish correlations between the basin-centre evaporite series and the basin-margin clastics series. The high-resolution correlations show stratigraphic cycle geometries. The Keuper consists of five minor base-level cycles whth occur in the upper portion of the Scythian-Carnian major base-level cycle and the lower part of the Carnian-Liassic major base-level cycle. The maximum relative rate of subsidence for the base-level fall phase of the Scythian-Carnian major cycle occurs in the eastern part of the Paris Basin. During the base-level rise phase of the Carnian-Liassic major cycle, the area of highest rate of subsidence shifted westwards and northwards. This shift records the first occurrence of an independent Paris Basin which was no longer merely the western margin of the German Basin. Two phases of tectonic movement influenced evaporite sedimentation and sequence geometries by creating areas of subsidence where halite could accumulate. The second, within the 'Marnes irisées supérieures', induced a general westward and northward tilt of the basin. Concurrent migration of depocentres to the west and north produced an intra-'Marnes irisées supérieures' truncation. Comparison of the stratigraphic records of the Paris Basin and of other Triassic Peritethyan basins (German Basin, Bresse-Jura Basin and South-East Basin) reveals numerous similarities. The coastal onlap curve of the German Keuper (Aigner and Bachmann, 1992) exhibits many similarities with the sequence evolution of the Paris Basin. But the Triassic succession is more complete in the German Basin and more cycles are observed. The major difference between these two basins during the Keuper is that the 'Marnes irisées inférieures' minor base-level cycle does not occur in the German Basin. In the Bresse-Jura Basin, the major difference concerns the Lettenkohle. One minor base-level cycle is recorded in the Paris Basin while no cycle is observed in the Bresse-Jura Basin.

Bourquin, Sylvie; Guillocheau, François

1996-09-01

258

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

259

Chronology of lunar basin formation  

NASA Technical Reports Server (NTRS)

The lunar anorthositic rocks 60025,86 and 60015,22 give Ar-40/Ar-39 ages of about 4.19 and 3.50 b.y., respectively. Two coarse fine anorthositic rock fragments 78503,7,1 and 72503,8,12 have ages of 4.13 and 3.96 b.y., respectively. The rock 60025 is the first large lunar rock with an age well in excess of 4.0 b.y. Evidence for the conclusion that the cratering events reset the radiometric ages is discussed. The chronology of the lunar basin forming events is deduced from the ages of the lunar highland impact breccias. Using the ages of lunar breccias, we have deduced a chronology for the last five lunar basin forming events. It is concluded that the 'lunar cataclysm' is the Imbrium event.

Schaeffer, O. A.; Husain, L.

1974-01-01

260

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.

261

Formation of lunar basin rings  

NASA Technical Reports Server (NTRS)

The outer rings of impact basins are interpreted as the bounding rings of the excavated basin cavities analogous to Copernicus-type crater rim crests. It is suggested that the inner rings are strata from depth uplifted during excavation of the transient cavity. Spacing relations and morphology appear to indicate a transition from central peaks to rings but not from terraces to rings. Evidence related to terrestrial craters with rings or peaks produced by meteorite impacts suggests that one or more crater rims may form inside the main, outer crater rim, resulting in nested craters. There is some evidence that peaks grade into inner rings as material is ejected from their cores in progressively larger impacts. Multiply layered materials may produce multiple rings by differential excavation of the layers.

Hodges, C. A.; Wilhelms, D. E.

1978-01-01

262

Stratigraphic Analysis of Upper Cretaceous Rocks in the Mahajanga Basin, Northwestern Madagascar: Implications for Ancient and Modern Faunas.  

PubMed

Upper Cretaceous strata of the Mahajanga Basin, northwestern Madagascar, yield some of the most significant and exquisitely preserved vertebrate fossils known from Gondwana. The sedimentology of these strata and their stratigraphic relations have been the focus of renewed geological investigations during the course of five expeditions since 1993. We here designate stratotypes and formalize the terrestrial Maevarano Formation, with three new members (Masorobe, Anembalemba, Miadana), and the overlying marine Berivotra Formation. The Maevarano Formation accumulated on a broad, semiarid alluvial plain bounded to the southeast by crystalline highlands and to the northwest by the Mozambique Channel. The Berivotra Formation was deposited in an open marine setting that evolved from a clastic- to a carbonate-dominated shelf, resulting in deposition of the overlying Betsiboka limestone of Danian age. New stratigraphic data clearly indicate that the Maevarano Formation correlates, at least in part, with the Maastrichtian Berivotra Formation, and this in turn indicates that the most fossiliferous portions of the Maevarano Formation are Maastrichtian in age, rather than Campanian as previously reported. This revised age for the Maevarano vertebrate assemblage indicates that it is approximately contemporaneous with the vertebrate fauna recovered from the Deccan basalt volcano-sedimentary sequence of India. The comparable age of these two faunas is significant because the faunas appear to be more similar to one another than either is to those from any other major Gondwanan landmass. The revised age of the Maevarano Formation, when considered in the light of our recent fossil discoveries, further indicates that the ancestral stocks of Madagascar's overwhelmingly endemic modern vertebrate fauna arrived on the island in post-Mesozoic times. The basal stocks of the modern vertebrate fauna are conspicuously absent in the Maevarano Formation. Finally, the revised age of the Maevarano Formation serves to expand our global perspective on the K/T event by clarifying the age of a diverse, and arguably the best preserved, sample of Gondwanan vertebrates from the terminal Cretaceous. PMID:10769157

Rogers; Hartman; Krause

2000-05-01

263

Operational Performance of Sedimentation Basins  

E-print Network

Engineering Management Field Project Operational Performance of Sedimentation Basins By Matthew D. Bleything Fall Semester, 2012 An EMGT Field Project report submitted to the Engineering Management Program and the Faculty... or vortex-type de-gritting units. The chambers can be square, rectangular, or circular. A velocity of 1 ft/s is commonly used to separate grit from the organic material. 11 Grit chambers are commonly constructed as fairly shallow longitudinal channels...

Bleything, Matthew D.

2012-12-14

264

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.

1996-01-01

265

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

266

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

267

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

268

Interpretation of magnetic anomalies over the Grenada Basin  

Microsoft Academic Search

The Grenada Basin is a back arc basin located near the eastern border of the Caribbean Plate. The basin is bounded on the west by the north-south trending Aves Ridge (a remnant island arc) and on the east by the active Lesser Antilles island arc. Although this physiography suggests that east-west extension formed the basin, magnetic anomalies over the basins

Dale E. Bird; Stuart A. Hall; John F. Casey; Patrick S. Millegan

1993-01-01

269

Interpretation of magnetic anomalies over the Grenada Basin  

Microsoft Academic Search

The Grenada Basin is a back arc basin located near the eastern border of the Caribbean Plate. The basin is bounded on the west by the north-south trending Aves Ridge (a remnant island arc) and on the east by the active Lesser Antilles island arc. Although this physiography suggests that east-west extension formed the basin, magnetic anomalies over the basin

Dale E. Bird; Stuart A. Hall; John F. Casey; Patrick S. Millegan

1993-01-01

270

Basin-average data: Cloud Albedo and the Diurnal Cycle  

E-print Network

. Cuenca de la Plata 41. Amazon River Xingu 42. Amazon River Madiera 43. Amazon River Solimoes 44. Amazon River Negro 45. Amazon River Purus 46. Torne River Basin 47. Rhone River Basin 48. Columbia River Basin Basin (33-39) 62. Amazon River Basin (41-45) 28-58 follow ECMWF http://www

Hurrell, James

271

K-Ar and 40Ar/ 39Ar ages of dikes emplaced in the onshore basement of the Santos Basin, Resende area, SE Brazil: implications for the south Atlantic opening and Tertiary reactivation  

NASA Astrophysics Data System (ADS)

New K-Ar and 40Ar/ 39Ar data of tholeiitic and alkaline dike swarms from the onshore basement of the Santos Basin (SE Brazil) reveal Mesozoic and Tertiary magmatic pulses. The tholeiitic rocks (basalt, dolerite, and microgabbro) display high TiO 2 contents (average 3.65 wt%) and comprise two magmatic groups. The NW-oriented samples of Group A have (La/Yb) N ratios between 15 and 32.3 and range in age from 192.9±2.2 to 160.9±1.9 Ma. The NNW-NNE Group B samples, with (La/Yb) N ratios between 7 and 16, range from 148.3±3 to 133.9±0.5 Ma. The alkaline rocks (syenite, trachyte, phonolite, alkaline basalts, and lamprophyre) display intermediate-K contents and comprise dikes, plugs, and stocks. Ages of approximately 82 Ma were obtained for the lamprophyre dikes, 70 Ma for the syenite plutons, and 64-59 Ma for felsic dikes. Because Jurassic-Early Cretaceous basic dikes have not been reported in SE Brazil, we might speculate that, during the emplacement of Group A dikes, extensional stresses were active in the region before the opening of the south Atlantic Ocean and coeval with the Karoo magmatism described in South Africa. Group B dikes yield ages compatible with those obtained for Serra Geral and Ponta Grossa magmatism in the Paraná Basin and are directly related to the breakup of western Gondwana. Alkaline magmatism is associated with several tectonic episodes that postdate the opening of the Atlantic Ocean and related to the upwelling of the Trindade plume and the generation of Tertiary basins southeast of Brazil. In the studied region, alkaline magmatism can be subdivided in two episodes: the first one represented by lamprophyre dykes of approximately 82 Ma and the second comprised of felsic alkaline stocks of approximately 70 Ma and associated dikes ranging from 64 to 59 Ma.

Guedes, Eliane; Heilbron, Monica; Vasconcelos, Paulo M.; de Morisson Valeriano, Cláudio; César Horta de Almeida, Júlio; Teixeira, Wilson; Thomaz Filho, Antonio

2005-03-01

272

Sandakan basin prospects rise following modern reappraisal  

SciTech Connect

Borneo is fringed by six large Neogene deltaic basins, all but one producing substantial hydrocarbons. The Sandakan basin off Northeast Borneo is the exception, but the latest exploration results suggest that it will not remain so. The paper describes its complex history; its exploration history; exploration results; stratigraphy; and geologic structures and traps. The Sandakan basin is conservatively estimated to contain 1 billion bbl of oil and 3tcf of gas.

Walker, T. (WMC Petroleum, Kuala Lumpur (Malaysia))

1993-05-10

273

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. Water atlas of the Volta Basin-Atlas de l'eau dans le bas- sin de la Volta. Challenge Program on Water-2-7099-1687-5 Acknowledgements Remerciements This atlas presents findings from the Volta Basin Focal Project (BFP Volta), PN55

Boyer, Edmond

274

Quaternary Faults and Basin-fill Sediments of the Las Vegas Basin, Southern Nevada  

Microsoft Academic Search

The N-S elongated extensional Las Vegas basin, southern Nevada, contains 100's of meters of Cenozoic basin-fill sediments that are cut by several Quaternary (Q) faults. These faults define or influence the basin geometry. The basin is generally an asymmetrical half graben defined by the W-dipping, Q Frenchman Mountain fault (FMF) along its E side and a series of smaller offset

W. J. Taylor; E. Fossett; B. Luke; C. Snelson; T. Rasmussen; D. McCallen; A. Rodgers; J. Louie

2003-01-01

275

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

276

Draft Columbia River Basin Monitoring, Evaluation, Research  

E-print Network

: Increasing the efficiency and effectiveness of RME efforts by facilitating communication and coordination effectiveness and the effectiveness of actions in protecting, mitigating, and enhancing the Basin's fish

277

Late Paleozoic structural evolution of Permian basin  

SciTech Connect

The southern Permian basin is underlain by the NNW-trending Central Basin disturbed belt of Wolfcamp age (Lower Permian), the deep Delaware basin to its west, and the shallower Midland basin to its eat. The disturbed belt is highly segmented with zones of left-lateral offset. Major segments from south to north are: the Puckett-Grey Ranch zone; the Fort Stockton uplift; the Monahans transverse zone; the Andector ridges and the Eunice ridge; the Hobbs transverse zone; and the Tatum ridges, which abut the broad Roosevelt uplift to the north. The disturbed belt may have originated along rift zones of either Precambrian or Cambrian age. The extent of Lower and Middle Pennsylvanian deformation is unclear; much of the Val Verde basin-Ozona arch structure may have formed then. The main Wolfcamp deformation over thrust the West Texas crustal block against the Delaware block, with local denudation of the uplifted edge and eastward-directed backthrusting into the Midland basin. Latter in the Permian, the area was the center of a subcontinental bowl of subsidence - the Permian basin proper. The disturbed belt formed a pedestal for the carbonate accumulations which created the Central Basin platform. The major pre-Permian reservoirs of the Permian basin lie in large structural and unconformity-bounded traps on uplift ridges and domes. Further work on the regional structural style may help to predict fracture trends, to assess the timing of oil migration, and to evaluate intrareservoir variations in the overlying Permian giant oil fields.

Ewing, T.E.

1984-04-01

278

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

279

Miocene temblor formation and related basin evolution, southwestern San Joaquin Basin, California  

Microsoft Academic Search

The southwestern San Joaquin basin is an area of great importance for the energy industry and academic basin analysts. Understanding basin evolution is a key concern for explorationists in this essentially pristine province. Temblor Formatio is exposed in an east-west-trending belt that comprises the north flank of the San Emigdio Mountains. Field and subsurface evidence were used to elucidate the

Blake W. Gillespie

1988-01-01

280

Basin evolution, diagenesis and uranium mineralization in the PaleoproterozicThelon Basin,  

E-print Network

during diagenetic stage1indicating that oxygenated, uranium- bearing pore water was present in the basinBasin evolution, diagenesis and uranium mineralization in the PaleoproterozicThelon Basin, Nunavut18 O values near 0% (Vienna Standard Mean OceanWater). Uranium-rich apatite cement (P1) also formed

Hiatt, Eric E.

281

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

282

Fraser River Basin &ssment Program Conceptual Monitoring Design  

E-print Network

#12;Fraser River Basin &ssment Program Conceptual Monitoring Design Prepared for Environment Canada. 1993. Fraser River Basin Assessment Program: Conceptual Monitoring Design. Pqared for Conservation the Fraser River Basin Assessment Program (FRBAP), is being designed for implementation starting

283

78 FR 9883 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013

...AGRICULTURE Office of the Secretary Lake Tahoe Basin Federal Advisory Committee AGENCY: Forest...Solicitation of nominees to the Lake Tahoe Basin Federal Advisory Committee...nominees to fill vacancies on the Lake Tahoe Basin Federal Advisory Committee...

2013-02-12

284

18 CFR 725.7 - Regional or river basin planning.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Regional or river basin planning. 725.7 Section 725.7 ...Responsibilities § 725.7 Regional or river basin planning. (a) In agreements between river basin commissions or other regional planning...

2011-04-01

285

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

Federal Register 2010, 2011, 2012, 2013

...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

286

18 CFR 725.7 - Regional or river basin planning.  

Code of Federal Regulations, 2013 CFR

... 2012-04-01 true Regional or river basin planning. 725.7 Section 725.7 ...Responsibilities § 725.7 Regional or river basin planning. (a) In agreements between river basin commissions or other regional planning...

2013-04-01

287

75 FR 6348 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013

...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

288

18 CFR 725.7 - Regional or river basin planning.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Regional or river basin planning. 725.7 Section 725.7 ...Responsibilities § 725.7 Regional or river basin planning. (a) In agreements between river basin commissions or other regional planning...

2012-04-01

289

18 CFR 725.7 - Regional or river basin planning.  

...2014-04-01 false Regional or river basin planning. 725.7 Section 725.7 ...Responsibilities § 725.7 Regional or river basin planning. (a) In agreements between river basin commissions or other regional planning...

2014-04-01

290

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

Federal Register 2010, 2011, 2012, 2013

...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

291

An entropy-based morphological analysis of river basin networks  

E-print Network

Under the assumption that the only information available on a drainage basin is its mean elevation, the connection between entropy and potential energy is explored to analyze drainage basins morphological characteristics. The mean basin elevation...

Fiorentino, Mauro; Claps, Pierluigi; Singh, Vijay P.

292

An implicit finite difference method for drainage basin evolution  

E-print Network

An implicit finite difference method for drainage basin evolution Sergio Fagherazzi,1 Alan D 24 July 2002. [1] In drainage basin evolution models the implementation of sediment transport solutions; 3210 Mathematical Geophysics: Modeling; KEYWORDS: drainage basin, landscape evolution, sediment

Fagherazzi, Sergio

293

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

294

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

295

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

296

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

297

75 FR 27360 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

298

76 FR 24515 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

299

75 FR 66389 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

300

78 FR 70574 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

301

75 FR 25877 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

302

77 FR 61784 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

303

77 FR 23508 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

304

78 FR 23784 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

305

76 FR 61382 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013

...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

306

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

307

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

308

Cenozoic evolution of San Joaquin basin, California  

SciTech Connect

The Neogene San Joaquin basin in the southern part of the 700-km long Great Valley of California is a successor to a late Mesozoic and earliest Tertiary forearc basin. The transition from forearc basin to the more restricted Neogene marine basin occurred principally during the Paleogene as the plate tectonic setting changed from oblique convergence to normal convergence, and finally to the initiation of tangential (transform) movement near the end of the Oligocene. Regional-scale tectonic events that affected the basin include: (1) clockwise rotation of the southernmost Sierra Nevada, and large-scale en echelon folding in the southern Diablo Range, both perhaps related to Late Cretaceous and early Tertiary right slip on the proto-San-Andreas fault; (2) regional uplift of southern California in the Oligocene that resulted from the subduction of the Pacific-Farallon spreading ridge: (3) extensional tectonism in the Basin and Range province, particularly in the Miocene; (4) wrench tectonism adjacent to the San Andreas fault in the Neogene; (5) northeastward emplacement of a wedge of the Franciscan complex at the west side of the Sierran block, with associated deep-seated thrusting in the late Cenozoic; and (6) the accelerated uplift of the Sierra Nevada beginning in the late Miocene. Neogene basin history was controlled principally by the tectonic effects of the northwestward migration of the Mendocino triple junction along the California continental margin and by the subsequent wrench tectonism associated with the San Andreas fault system. East-west compression in the basin, resulting from extension in the Basin and Range province was an important contributing factor to crustal shortening at the west side of the valley. Analysis of the sedimentary history of the basin, which was controlled to some extent by eustatic sea level change, enables reconstruction of the basin paleogeography through the Cenozoic.

Bartow, J.A.

1988-03-01

309

78 FR 65609 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...  

Federal Register 2010, 2011, 2012, 2013

...Thunder Basin National Grassland Prairie Dog Amendment Environmental Impact Statement...Thunder Basin National Grassland Prairie Dog Amendment EIS. The EIS will form the basis...Thunder Basin National Grassland Prairie Dog Amendment. The Open House/...

2013-11-01

310

Potential for a basin-centered gas accumulation in the Albuquerque Basin, New Mexico  

USGS Publications Warehouse

The potential that a basin-centered or continuous-type gas accumulation is present in the Albuquerque Basin in central New Mexico was investigated. The Albuquerque Basin is one of the many rift basins that make up the Rio Grand rift system, an area of active extension from Oligocene to recent time. The basin is significantly different from other Rocky Mountain basins that contain basin-centered gas accumulations because it is actively subsiding and is at near maximum burial and heating conditions at the present time. Burial reconstructions suggest that Cretaceous-age source rocks began to generate gas in the deeper parts of the basin about 20 million years ago and are still generating large amounts of gas. The high mud weights typically used while drilling the Cretaceous interval in the deeper areas of the basin suggest some degree of over-pressuring. Gas shows are commonly reported while drilling through the Cretaceous interval; however, attempts to complete gas wells in the Cretaceous have resulted in subeconomic quantities of gas, primarily because of low permeabilities. Little water has been reported. All of these characteristics suggest that a basin-centered gas accumulation of some sort is present in the Albuquerque Basin.

Johnson, Ronald C.; Finn, Thomsa M.; Nuccio, Vito F.

2001-01-01

311

Uplift and Erosion in the Northern Al Kufrah Basin (Southeast Libya)  

Microsoft Academic Search

The Al Kufrah Basin forms part of the North African continental basin system. While neighbouring basins (e.g. Murzuq Basin, Sirt Basin) are proven petroleum provinces, the Al Kufrah Basin is still in an early stage of exploration. This study combines outcrop studies from the northern basin margin (Jabal Az Zalmah) and the eastern basin margin (Jabal Azbah) with subsurface data

H. R. Gröger; H. M. Bjørnseth; S. Higgins; C. Vandré; O. Walderhaug; M. Geiger

2009-01-01

312

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

313

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

314

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.

315

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

316

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 electric Power Planning and conservation Act (Northwest Power Act) #12;Fast Facts Abut the columbia River, and fish and wildlife affected by, the columbia River Basin hydropower dams. the council is a unique

317

The resilience of big river basins  

Microsoft Academic Search

Big river basins are complex systems of people and nature. This article explores the resilience of nine case studies of big river basins. A system description and generic conceptual model suggests that resilience to changes in water quantity is critical. When water becomes limiting, the social-ecological system must adapt rapidly if key elements (for example, communities, biodiversity) are to be

Graeme S. Cumming

2011-01-01

318

Thermal state of the Arkoma Basin and the Anadarko Basin, Oklahoma  

NASA Astrophysics Data System (ADS)

One of the most fundamental physical processes that affects virtually all geologic phenomena in sedimentary basins is the flow of heat from the Earth's interiors. The Arkoma Basin and the Anadarko Basin, Oklahoma, are a prolific producer of both oil and natural gas. Both basins also have important geologic phenomena. Understanding the thermal state of the these basins is crucial to understanding the timing and extent of hydrocarbon generation, the genesis of Mississippi Valley-type ore deposits, and the origin of overpressures in the Anadarko Basin. In chapter one, heat flow and heat production in the Arkoma basin and Oklahoma Platform are discussed. Results of this study are not generally supportive of theories which invoke topographically driven regional groundwater flow from the Arkoma Basin in Late Pennsylvanian-Early Permian time (˜290 Ma) to explain the genesis of geologic phenomena. In chapter 2, different types of thermal conductivity temperature corrections that are commonly applied in terrestrial heat flow studies are evaluated. The invariance of the relative rankings with respect to rock porosity suggests the rankings may be valid with respect to in situ conditions. Chapter three addresses heat flow and thermal history of the Anadarko Basin and the western Oklahoma Platform. We found no evidence for heat flow to increase significantly from the Anadarko Basin in the south to the Oklahoma Platform to the north. In chapter four, overpressures in the Anadarko Basin, southwestern Oklahoma are discussed. Using scale analyses and a simple numerical model, we evaluated two endmember hypotheses (compaction disequilibrium and hydrocarbon generation) as possible causes of overpressuring. Geopressure models which invoke compaction disequilibrium do not appear to apply to the Anadarko Basin. The Anadarko Basin belongs to a group of cratonic basins which are tectonically quiescent and are characterized by the association of abnormal pressures with natural gas. (Abstract shortened by UMI.)

Lee, Youngmin

1999-12-01

319

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

320

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

321

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

322

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

323

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

324

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

325

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

326

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

327

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

328

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

329

Coal-generated oil in Tuha Basin  

Microsoft Academic Search

The Turpan-Harmi (abbreviated to Tuha below) Basin is a typical basin of coal-generated oil accumulation in China. The Middle-Lower\\u000a Jurassic coal measures are considered the main source beds. Hence, both desmocollinite and suberinite are considered the contributors\\u000a for coal-generated oil. Principal geochemical features of the crude oil in the Tuha Basin are rich in alkanes (70%—80%), high\\u000a pristane\\/phytane ratio (6—8),

Keming Cheng; Aiguo Su; Changyi Zhao; Zhonghua He

1997-01-01

330

INTEGRATED BASIN ANALYSIS OF THE MARCELLUS FORMATION IN THE  

E-print Network

analysis of the Marcellus Shale in the Pennsylvania-New York Appalachian Basin utilizing well logs, coresINTEGRATED BASIN ANALYSIS OF THE MARCELLUS FORMATION IN THE DEVONIAN BLACK SHALE BASIN OF PENNSYLVANIA AND NEW YORK Appalachian Basin Black Shale Group (ABBSG) Terry Engelder, Michael A. Arthur, Rudy

Slingerland, Rudy

331

Dynamic management of water transfer between two interconnected river basins  

E-print Network

determined by the Spanish government. Keywords: inter- basin water transfer; differential game; NashDynamic management of water transfer between two interconnected river basins Francisco Cabo Katrin regions with interconnected river basins. Precipitation is higher in one river-basin while water

Boyer, Edmond

332

SUTTER BASIN, SUTTER & BUTTE COUNTIES, CA FLOOD RISK MANAGEMENT PROJECT  

E-print Network

SUTTER BASIN, SUTTER & BUTTE COUNTIES, CA FLOOD RISK MANAGEMENT PROJECT 22 October 2013 ABSTRACT: The purpose of the Sutter Basin Project is to reduce overall flood risk to the Sutter Basin study area the risk to property damage due to flooding to the Sutter Basin area located in the Sutter and Butte

US Army Corps of Engineers

333

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

334

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

335

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

336

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

337

Possibilities of W. Batangas basin in Philippines South China Sea  

Microsoft Academic Search

The West Batangas basin is one of the few remaining untested basins on the Philippine side of the South China Sea. It lies about 100 km southwest of Manila, off and straddling the west coast of Batangas province, Luzon island. About 60% of the basin offshore lies in water 200 m deep or less. This promising frontier basin is probably

B. S. Austria; R. A. Jr. Reyes

1992-01-01

338

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...

2009-11-30

339

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...

2009-11-30

340

BASIN STRUCTURE FROM TWO-DIMENSIONAL SEISMIC REFLECTION DATA, CRAZY MOUNTAINS BASIN, MONTANA  

SciTech Connect

Some 140 miles of multichannel seismic reflection data, acquired commercially in the 1970's, were reprocessed by the U.S. Geological Survey in late 2000 and early 2001 to interpret the subsurface geology of the Crazy Mountains Basin, an asymmetric Laramide foreland basin located in south-central Montana. The seismic data indicate that the northwestern basin margin is controlled by a thrust fault that places basement rocks over a thick (22,000 feet) sequence of Paleozoic and Mesozoic sedimentary rocks to the south. From the deep basin trough, Paleozoic through Tertiary rocks slope gently upward to the south and southeast. The northern boundary of the basin, which is not imaged well by the seismic data, appears to be folded over a basement ridge rather than being truncated against a fault plane. Seismic data along the basin margin to the south indicate that several fault controlled basement highs may have been created by thin-skinned tectonics where a series of shallow thrust faults cut Precambrian, Paleozoic, and early Mesozoic rocks, whereas, in contrast, Cretaceous and Tertiary strata are folded. The data are further interpreted to indicate that this fault-bounded asymmetric basin contains several structures that possibly could trap hydrocarbons, provided source rocks, reservoirs, and seals are present. In addition, faults in the deep basin trough may have created enough fracturing to enhance porosity, thus developing ''sweet spots'' for hydrocarbons in basin-centered continuous gas accumulations.

David J. Taylor

2003-08-01

341

VIEW TO EAST OF THE NORTH END OF BASIN NO. ...  

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

VIEW TO EAST OF THE NORTH END OF BASIN NO. 1 (THE WESTERN-MOST BASIN) SHOWING THE CRANEWAY AND GALLERY BETWEEN BASINS NO. 1 AND 2. BASSWOOD BUOY TENDER AND THREE SMALL VESSELS ARE BERTHED IN BASIN NO. 1. LARGER VESSELS ARE BERTHED IN BASINS TO THE EAST, SEEN IN BACKGROUND - Rosie the Riveter National Historical Park, Graving Docks, Shipyard No. 3, Richmond, Contra Costa County, CA

342

The Uinta Basin Case Robert J. Bayer  

E-print Network

Overburden Tailings Oil Shale Mining Open Pit Underground Ex situ extraction Ex situ thermal conversion EIS for Oil Sands and Oil Shale Ongoing concerns with Basin-wide air quality Wildlife and wildlife

Utah, University of

343

Ecology: Drought in the Congo Basin  

NASA Astrophysics Data System (ADS)

A remote-sensing analysis of tropical forests in the Congo Basin that are experiencing chronic drought reveals consistent patterns of reduced vegetation greenness, increased temperatures and decreased water storage. See Letter p.86

Chambers, Jeffrey Q.; Roberts, Dar A.

2014-05-01

344

Tidal frequency estimation for closed basins  

NASA Technical Reports Server (NTRS)

A method was developed for determining the fundamental tidal frequencies for closed basins of water, by means of an eigenvalue analysis. The mathematical model employed, was the Laplace tidal equations.

Eades, J. B., Jr.

1978-01-01

345

Integrated geophysical model of the Thuringian Basin  

NASA Astrophysics Data System (ADS)

The INFLUINS (INtegrated FLUid dynamics IN Sedimentary basins) project aims at an improved understanding of the coupled fluid flow in sedimentary basins from the shallow aquifers to the deep layers. Hydrological, geological and geophysical investigations of the Thuringian Basin, Germany, provide a site characterization at various scales that is the basis for dynamic flow models. This study presents an integrated geophysical and structural approach that combines seismic and gravimetric observations with borehole data and surface geology. The seismic data consists of three reflection-seismic lines across the center of the basin providing high-resolution structural images. Additional piggyback recordings provide the basis for a tomographic 3D model of seismic velocities. Those studies are complemented by a 3D density model from a 2D grid of measuring points and several dense gravimetric profiles. The geophysical models provide layer thickness variations and rock properties, and, together with surface mapping, an inventory of faults, which are important prerequisites for subsequent flow models.

Bleibinhaus, F.; Krause, M.; Jahr, T.; Vinzelberg, D.; Prutkin, I.; Goepel, A.; Kukowski, N.

2013-12-01

346

K-Basins S/RIDS  

SciTech Connect

The Standards/Requirements Identification Document(S/RID) is a list of the Environmental, Safety, and Health (ES&H) and Safeguards and Security (SAS) standards/requirements applicable to the K Basins facility

Watson, D.J.

1995-09-22

347

K-Basins S/RIDS  

SciTech Connect

The Standards/Requirements Identification Document (S/RID) is a list of the Environmental, Safety, and Health (ES{ampersand}H) and Safeguards and Security (SAS) standards/requirements applicable to the K Basins facility.

Watson, D.J.

1997-08-01

348

KE Basin water dispositioning engineering study  

SciTech Connect

This engineering study is a feasibility study of KE Basin water treatment to an acceptable level and dispositioning the treated water to Columbia River, ground through ETF or to air through evaporation.

Hunacek, G.S.; Gahir, S.S.

1994-09-23

349

Quasigeostrophic Free Oscillations in Enclosed Basins.  

National Technical Information Service (NTIS)

Solutions are obtained for quasigeostrophic free oscillations in enclosed basins of dimensions comparable to the Pacific, Atlantic, and Indian oceans. The lower-order baroclinic oscillations are restricted to the regions adjacent to the equator or the oce...

M. Rattray, R. L. Charnell

1965-01-01

350

Future Climate Scenarios for the Indus Basin  

E-print Network

Examines the literature and available data on hydroclimatic variability and change on the Indus Basin plains, comparing historical fluctuations in climatic and hydrologic variables and reviewing scenarios of climate change ...

Yu, Winston

351

Pacific Basin Communication Study, volume 2  

NASA Technical Reports Server (NTRS)

Users' meeting summary report, chronology of visits, economic data for forum countries, techniques used in the study, communication choices, existing resources in the Pacific Basin, and warc 79 region 3 rules and regulations were presented in volume 2.

Young, E. L.; Hurd, J. N.

1981-01-01

352

BOULDER AREA SUSTAINABILITY INFORMATION NETWORK (BASIN)  

EPA Science Inventory

The primary goal of the Boulder Area Sustainability Information Network (BASIN) is to help citizens make meaningful connections between environmental data and their day-to-day activities and facilitate involvement in public policy development. Objectives include: ...

353

Induced Seismicity of Kuznetsk Basin  

NASA Astrophysics Data System (ADS)

A natural seismicity of Kuznetsk Basin is confined in the main to mountain frame of Kuznetsk hollow. In this paper materials of experimental work with local station networks within sediment basin are presented. Different types of seismicity display within Kuznetsk hollow has been understood: first, man-caused seismic processes, confined to mine working and concentrated on depths up to one and a half of km; secondly, seismic activations on depths of 2-5 km, not coordinated in plan with coal mines; thirdly, induced seismicity in the neighborhood of strip mines. Every of studied seismic activations consists of large quantity of earthquakes of small powers (Ms=1-3). From one to first tens of earthquakes were recorded in a day. The earthquakes near mine working shift in space along with mine working, and seismic process become stronger at the instant a coal-plough machine is operated, and slacken at the instant the preventive works are executed. Uplift is the most typical focal mechanism. Activated zone near mine working reach in diameter 1-1,5 km. Today earthquakes happen mainly under mine working, though damages of working themselves do not happen, but intensive shaking on surface calls for intent study of so dangerous phenomena. Spatial-temporal changes of technogeneous activations not coordinated in plan with mine working are noted. A spatial displacement of activation along with mine working has been found. Trigger effects in progress of man-caused seismicity have been understood. It was demonstrated that industrial explosions in neighboring open-casts have no pronounced effect on seismic process near lavas. Stoppage of mole work in lavas leads to simultaneous changes in man-caused seismicity. The number of technogeneous earthquakes is lowered in several time, the earthquakes of small powers remain. Reactivation of lava coal production restores almost instantly the seismic behavior characteristics. Research of induced seismicity in area of "Raspadskaya" coal mine immediately after crash showed an existence of seismic activated zone, where four working lavas shifted from different sides. A fact of vibration effect at 500 m distance on characteristics of technogeneous seismicity in area of working lava has been experimentally determined. This fact allows to be relied on success in making of control method of technogeneous seismicity, what is important for working protection of coal production. The technogeneous seismicity in section area of 350 m depth and size of 3 km to 12 km has been studied. The strongest earthquake in the section area had magnitude 4. In whole a seismic energy of technogeneous earthquakes is in order less, than a seismic effect of industrial explosions in open cast. The recorded large event is rare, but dangerous phenomena. The largest coal basin of Siberia, disposed in zone of moderate natural activity, is situated in stress-strain state, and development of intensive induced seismicity accompanies coal production.

Emanov, A.; Leskova, E.; Fateev, A.

2013-05-01

354

Multispectral Study of the Schrödinger Impact Basin  

NASA Astrophysics Data System (ADS)

The Schrödinger impact basin is located on the lunar far side near the south pole (76oS, 134oE) and is one of only two young multiring impact basins on the lunar surface [1]. With a diameter size of 312 km and basin floor 2-3 km deep, Schrödinger is the least modified impact basin of its size. A peak ring structure 150 km in diameter lies on the basin floor, formed by uplift of pre-Schrödinger crustal materials. Ejecta material, smooth in texture, covers the basin walls and extends out onto the surrounding surface up to 100 km in all directions. The first geological map published of Schrödinger was generated using preliminary Clementine data [1]. The map described the geology and geomorphology within the inner basin with smooth and rough plains of shocked material occupying most of the basin floor. The rough plains are identified by presence of hummocks, swales, and low knobs. Smooth plains have no discernable features identifiable. Ghost craters are found along both smooth and rough patches. A volcanic vent in the inner eastern corner of Schrödinger is interpreted as a source for pyroclastic eruptions within the area. Located along the volcanic vent is a north-east trending graben. There are thin patches of impact melt sheets along the basin walls and peak ring. A lobate ridge located near the centre of the inner basin is interpreted as having formed by buckling of the melt sheet. A more recent geologic map using high resolution Clementine UVVIS data and topography data is in agreement with the proposed geology within the Schrödinger basin [2]. Contacts between various units are better outlined in the recent map. Using spectra derived from high resolution Clementine UVVIS images and Lunar Prospector data we determine the composition of impact melt, impact ejecta, and the extent of proposed cryptomare deposits [3]. We also use Fe, Th, and Ti abundance in determining the composition of these units. Our goal is to determine the abundance and distribution of impact melt relative to volcanic products and ejecta units. We are also addressing possible differentiation of the melt sheet as a crater the size of Schrödinger has sufficient time to cool and allow for melt to differentiate. References: [1] Shoemaker, E.M., Robinson, M.S., and Eliason, E.M. (1994) Science. 266. 1851- 1854. [2] Mest, S. C.; Van Arsdall, L. E. (2008) NLSI Lunar Science Conference. Abstract 2089. [3] Antonenko, I. (1999) PhD Thesis, Brown University. Chapter 4, pp 13-14.

Shankar, B.; Osinski, G.; Antonenko, I.; Stooke, P. J.

2009-05-01

355

Ordovician chitinozoan zones of Great Basin  

SciTech Connect

Within the Basin and Range province of the Great Basin of the western US, Ordovician chitinozoans have been recovered in two major lithic facies; the western eugeosynclinal facies and the eastern miogeosynclinal facies. Chitinozoans recovered from these facies range in age from Arenig to Ashgill. Extensive collections from this area make possible the establishment of chitinozoan faunal interval zones from the Ordovician of this area. Selected species of biostratigraphic value include, in chronostratigraphic order, Lagenochitina ovoidea Benoit and Taugourdeau, 1961, Conochitina langei Combaz and Peniguel, 1972, Conochitinia poumoti Combaz and Penique, Desmochitina cf. nodosa Eisenack, 1931, Conochitina maclartii Combaz and Peniguel, 1972, Conochitina robusta Eisenack, 1959, Angochitina capitallata Eisenack, 1937, Sphaerochitina lepta Jenkins. 1970, and Ancyrochitina merga Jenkins, 1970. In many cases, these zones can be divided into additional sub-zones using chitinozoans and acritarchs. In all cases, these chitinozoan faunal zones are contrasted with established American graptolite zones of the area, as well as correlated with British standard graptolite zones. The composition of these faunas of the western US Great Basin is similar to that of the Marathon region of west Texas and the Basin Ranges of Arizona and New Mexico, to which direct comparisons have been made. There also appears to be a great similarity with the microfaunas and microfloras of the Ordovician of the Canning basin of western Australia. The Ordovician chitinozoan faunal interval zones established for the Basin and Range province of the Great Basin of the western US also appear to be applicable to the Marathon region of west Texas and the Basin Ranges of Arizona and New Mexico.

Hutter, T.J.

1987-08-01

356

Saharan dust in the Amazon Basin  

Microsoft Academic Search

Saharan dust is shown to enter the Central Amazon Basin (CAB) in bursts which accompany major wet season rain systems. Low-level horizontal convergence feeding these rain systems draws dust from plumes which have crossed the tropical Atlantic under the large-scale circulation fields. Mass exchange of air between the surface and 4km over the eastern Amazon basin is calculated using rawinsonde

R. Swap; M. Garstang; S. Greco; R. Talbot; P. Kållberg

1992-01-01

357

Tectonic history of the Shikoku marginal basin  

Microsoft Academic Search

Studies of marine magnetic anomaly data from the Shikoku basin reveal magnetic lineations which strike north- west almost parallel to the trend of the Palau-Kyushu ridge. The lineation pattern is best developed in the western part of the basin and we can confidently identify a sequence of anomalies 7 through 5E between the base of the Palau-Kyushu ridge and the

A. B. WATTS; J. K. WEISSEL

1975-01-01

358

The Future of the Amazon Basin Hydroclimatology  

Microsoft Academic Search

State-of-the art socio-economic scenarios of land-cover change in the Amazon Basin for the years 2030 and 2050 are used together with the Regional Atmospheric Modeling System (RAMS) to anticipate the hydrometeorological changes caused by deforestation expansion in that region assuming a four-year sequence (1997-2000) of meteorological conditions that include both El Niño and La Niña events. The basin-average rainfall decreases

RENATO RAMOS DA SILVA; DAVID WERTH; RONI AVISSAR

359

Permian Basin as a radioactive waste repository  

Microsoft Academic Search

The Permian Basin comprises portions of many structural basins in which halite was deposited close together aerially during the Permian Period of time. It contains at least five areas where salt beds within a formation cumulatively total greater than 200 feet, and are overlain by between 1,000 and 5,000 feet of strata: the Colorado-Kansas, Kansas, Oklahoma-Texas, Clovis and Carlsbad areas.

1975-01-01

360

The petroleum basins of the northwest Pacific  

SciTech Connect

The northwest Pacific area includes the major petroleum basins flanking the Pacific Ocean in Asia (Japanese, Isikury-West Sakhalin, North Sakhalin, West Kamchatka, Khatyrskiy, and Anadyrskiy). The petroleum basins consist of Tertiary cover (marine, coastal, and continental terrigeneous, siliceous volcanogenic, and volcanogenic-sedimentary rocks) and pre-Genozoic basement composed of geosyncline rock associations. Sediment thickness of the basins attains 10-12 km. Northwest and northeast faults control graben feature in the basement and develop rift systems. The general thickness of the Earth's crust is 27-31 km. All petroleum basins are connected with rifts. Rifting influenced the volcanic and magmatic activity, the abnormally high temperature and pressure in oil- and gas-bearing filling of basins. Analysis of data shows that the main factors affecting deposition of the source rocks and their spatial distribution and effectiveness in generating hydrocarbon reserves are geological age, regional tectonics, paleography, dominant kerogen type, and temperature. There are various types of petroleum source rocks: upper Eocene marine shales (Khatyrskiy basin), kerogen type III; upper Oligocene siliceous shales (North Sakhalin, Japanese, West Kamchatka and Anadyrskiy basins), kerogen type II and III; and middle Miocene marine shales (Japanese, Isikury-West Sakhalin and North Sakhalin basins), kerogen type II. The quantity of organic matter in source rocks is 0.6-3.4% and the geothermal gradient is 24-44{degree}C/km. The main reservoirs are Miocene-lower Pliocene sandstones, upper Miocene deltaic sandstones, and upper Oligocene-lower Miocene siliceous shales. Oil and gas accumulated in anticline structures and stratigraphic traps.

Khvedtchuk, I. (Oil and Gas Research Institute, Moscow (USSR))

1990-05-01

361

Streamflow changes over Siberian Yenisei River Basin  

Microsoft Academic Search

This study analyzes long-term (1935–99) monthly discharge data for the major sub-basins within the Yenisei River watershed in order to document significant streamflow changes induced by reservoir regulations and by natural variations\\/changes. The results show that both the unregulated upper basin and major lower streams of the watershed experienced streamflow decreases in the early melt period and discharge increases in

Daqing Yang; Baisheng Ye; Douglas L. Kane

2004-01-01

362

River Basin Planning: Theory and Practice  

NASA Astrophysics Data System (ADS)

River Basin Planning is divided into three major parts and an appendix. Part 1, Theory of River Basin Planning, is led by an introductory chapter from the editors emphasizing the major human component in the complex sociotechnical attributes of river basin development. They present a forceful argument for a truly interdisciplinary approach to river basin planning. (The appendix subsequently suggests curriculum development for courses in river basin planning.)Part 2, River Basin Planning: Environmental Issues, is supported by two chapters: one with a focus on soil conservation, the other on ecosystem protection. The soil conservation chapter by I. Douglas illustrates that slow, inadvertent changes may be more damaging in the long run than immediate, direct effects. It postulates that planning for people perforce will require planning for soil conservation as an ongoing activity. The case for environmental protection is somewhat weak because of the singular example chosen for illustration. The Gunung Mulu National Park in Sarawak, Malaysia, is in a fragile, humid, tropical forest region where any change per se is interpreted as being detrimental.

Joeres, Erhard F.

363

K basins sludge removal sludge pretreatment system  

SciTech Connect

The Spent Nuclear Fuels Program is in the process of planning activities to remove spent nuclear fuel and other materials from the 100-K Basins as a remediation effort for clean closure. The 105 K- East and K-West Basins store spent fuel, sludge, and debris. Sludge has accumulated in the 1 00 K Basins as a result of fuel oxidation and a slight amount of general debris being deposited, by settling, in the basin water. The ultimate intent in removing the sludge and fuel is to eliminate the environmental risk posed by storing fuel at the K Basins. The task for this project is to disposition specific constituents of sludge (metallic fuel) to produce a product stream through a pretreatment process that will meet the requirements, including a final particle size acceptable to the Tank Waste Remediation System (TWRS). The purpose of this task is to develop a preconceptual design package for the K Basin sludge pretreatment system. The process equipment/system is at a preconceptual stage, as shown in sketch ES-SNF-01 , while a more refined process system and material/energy balances are ongoing (all sketches are shown in Appendix C). Thus, the overall process and 0535 associated equipment have been conservatively selected and sized, respectively, to establish the cost basis and equipment layout as shown in sketches ES- SNF-02 through 08.

Chang, H.L.

1997-06-12

364

Seismic stratigraphy or Cape Sorell Basin, Tasmania  

SciTech Connect

Because large new exploration areas have become scarce, the Cape Sorell basin has become an increasingly attractive frontier area. Cape Sorell basin, located along the western passive continental margin of Tasmania formed as a result of the breakup of eastern Gondwanaland 95{plus minus}5 Ma. An extensional fault system trending west-northwest with dip-slip movement down to the south-southwest forms the northern boundary and a second fault system trending north-northwest with oblique slip down to the south-southwest creates the basin. Second order extensional faults within the basin have created wrench-type flower structures, which are potential migration pathways for hydrocarbons. Nine distinct depositional sequences identified within the Cape Sorell basin record the evolution of this passive continental margin. Late Cretaceous-early Paleocene sequences were deposited as the rifting ceased and clastic progradation over the rift terrain began. Relative lowering of sea level occurred during the Paleocene, resulting in extensive channeling of the Late Cretaceous-early Paleocene sequences. A subsequent rise in relative sea level resulted in canyon-fill deposition during the early Paleocene to early Eocene. During the Eocene, sedimentation sufficiently increased to produce a downlapping sediment progradation characterized by deltaic depositional environment. Although interrupted several times by changes in relative sea level and shifting sediment sources, deltaic deposition continued until the late Oligocene. As the rate of clastic sedimentation slowed, carbonate shelf deposition began and has typified the basin since late the Oligocene.

Bellow, T.L.

1990-05-01

365

Geothermal resources of California sedimentary basins  

USGS Publications Warehouse

The 2004 Department of Energy (DOE) Strategic Plan for geothermal energy calls for expanding the geothermal resource base of the United States to 40,000 MW of electric power generating potential. This will require advances in technologies for exploiting unconventional geothermal resources, including Enhanced Geothermal Systems (EGS) and geopressured geothermal. An investigation of thermal conditions in California sedimentary basins through new temperature and heat flow measurements reveals significant geothermal potential in some areas. In many of the basins, the combined cooling effects of recent tectonic and sedimentary processes result in relatively low (<60 mW/m2) heat flow and geothermal gradients. For example, temperatures in the upper 3 km of San Joaquin, Sacramento and Ventura basins are typically less than 125??C and do not reach 200??c by 5 km. By contrast, in the Cuyama, Santa Maria and western Los Angeles basins, heat flow exceeds 80 mW/m2 and temperatures near or above 200??C occur at 4 to 5 km depth, which represents thermal conditions equivalent to or hotter than those encountered at the Soultz EGS geothermal site in Europe. Although the extractable geothermal energy contained in these basins is not large relative to the major California producing geothermal fields at The Geysers or Salton Sea, the collocation in the Los Angeles basin of a substantial petroleum extraction infrastructure and a major metropolitan area may make it attractive for eventual geothermal development as EGS technology matures.

Williams, C. F.; Grubb, F. V.; Galanis, Jr. , S. P.

2004-01-01

366

Thermal evolution of the Newark basin  

SciTech Connect

A one-dimensional conductive thermal model is used to calculate the transient thermal history of the Newark basin, a Triassic-Jurassic continental rift basin in the eastern United States that formed during the separation of North America and Africa. The model accounts for deposition, erosion, igneous activity, lithology-dependent variations in thermal conductivity, depth-dependent radiogenic heat production, and changes in heat flow through time. A burial and erosion history for the Newark basin is constructed for the modeling, including changes in heat flow through time, emplacement of Jurassic lava flows at the surface, and emplacement of the Palisades still at depth. Vitrinite-reflectance values and apatite and zircon fission-track ages, for units of both Triassic and Jurassic age, are used to constrain the models. Use of two different data sets greatly limits the number and types of models that can reproduce the observed data. Modeling results indicate that initial formation of the Newark basin is not coincident in time with a thermal event. Elevated heat flow (on the order of 130 mW/m[sup 2] in the models) did affect the basin during its evolution, however, and was associated with igneous activity (at approximately 201-199.5 Ma in the models). Results of the modeling also indicate that the original sedimentary package in the Newark basin was approximately 2.5 km thicker than today.

Huntoon, J.E. (Michigan Technological Univ., Houghton (United States)); Furlong, K.P. (Pennsylvania State Univ., University Park (United States))

1992-09-01

367

Mesozoic evolution of the Amu Darya basin  

NASA Astrophysics Data System (ADS)

This study, granted by the Darius Programme, aims at proposing a model of tectono-stratigraphic evolution of the Amu Darya basin since the Late Palaeozoic and to understand the relationship with the nearby basins. The Amu Darya basin, as its close eastern neighbour, the Afghan-Tajik basin, lies on the Turan platform, after the closure of the Turkestan Ocean during the Late Paleozoic. These two basins, spread on mainly lowlands of Turkmenistan, southwest Uzbekistan, Tajikistan, and northern Afghanistan, are separated from one another by the South-Western Gissar meganticline, where series of the northern Amu Darya margin are outcropping. The evolution is closely controlled by several periods of crustal thinning (post-collision rifting and back-arc extension), with some marine incursions, coming in between accretions of continental blocks and collisions that succeeded from the Late Triassic-Early Jurassic (Eo-Cimmerian orogeny) to the Cenozoic times. These orogenies controlled the deposition of thick clastics sequences, and the collision of the Indian Plate with Eurasia strongly deformed the sedimentary cover of the Afghan-Tajik basin. The more than 7 km thick Meso-Cenozoic sedimentary succession of the Amu Darya basin, lies on a complex system of rifts and blocks. Their orientation and age (late Permian, Triassic?) are not well known because of deep burial. The north-eastern margin, with the Bukhara (upper margin) and Chardzhou steps, is NW oriented, parallel to the Paleozoic Turkestan suture. The orientation bends to W-E, in the part of the Gissar situated to the North of the Afghan-Tajik basin. This EW trending orientation prevails also in the south(-eastern) margin of the basin (series of North Afghanistan highs) and in the Murgab depression, the south-eastern deepest portion of the Amu Darya basin. It is in this area and in the eastern part of the Amu Darya basin that the Jurassic as well as the lower Cretaceous sediments are the thickest. The south-western part of the basin is occupied by the Pre-Kopet Dagh Cenozoic foreland basin NW oriented, possibly underlain by an earlier extensional trough. The main elements of the sedimentary pile, which can be partly observed in the South-Western Gissar are: Lower to Middle Jurassic continental to paralic clastic rocks; upper Middle to Upper Jurassic marine carbonate then thick Tithonian evaporite rocks, sealing the reservoirs in the Jurassic carbonates; continental Neocomian clastic rocks and red beds, Aptian to Paleogene marine carbonate and clastic rocks. To reconstruct the geodynamic evolution of the Amu Darya Basin, we analysed the subsidence by backstripping of some wells/pseudo-wells and of three cross-sections with some examples of thermal modelling on the periods of maturation of the potential source rocks. The crustal thinning events take place in the Permo-Triassic? (depending on the age of the rifts underlying the basin), in Early-Middle Jurassic and during the Early Cretaceous, resulting in increases of the tectonic subsidence rates.

Brunet, Marie-Françoise; Ershov, Andrey; Korotaev, Maxim; Mordvintsev, Dmitriy; Barrier, Eric; Sidorova, Irina

2014-05-01

368

Active transtensional intracontinental basins: Walker Lane in the western Great Basin  

USGS Publications Warehouse

The geometry and dimensions of sedimentary basins within the Walker Lane are a result of Plio-Pleistocene transtensive deformation and partial detachment of the Sierra Nevada crustal block from the North American plate. Distinct morpho-tectonic domains lie within this active transtensive zone. The northeast end of the Walker Lane is partly buried by active volcanism of the southern Cascades, and adjacent basins are filled or poorly developed. To the south, the basin sizes are moderate, 25–45km × 15–10 km, with narrow 8-12km wide mountain ranges mainly oriented N-S to NNE. These basins form subparallel arrays in discrete zones trending about 300° and have documented clockwise rotation. This is succeeded to the south by a releasing stepover domain ?85-100km wide, where the basins are elongated E-W to ENE, small (?15-30km long, 5-15km wide), and locally occupied by active volcanic centers. The southernmost part of the Walker Lane is structurally integrated, with high to extreme relief. Adjacent basins are elongate, 50-200km long and ?5 -20km wide. Variations in transtensive basin orientations in the Walker Lane are largely attributable to variations in strain partitioning. Large basins in the Walker Lane have 2-6km displacement across basin bounding faults with up to 3 km of clastic accumulation based on gravity and drill hole data. The sedimentary deposits of the basins may include interbedded volcanic deposits with bimodal basaltic and rhyolitic associations. The basins may include lacustrine deposits that record a wide range of water chemistry from cold fresh water conditions to saline-evaporative

Jayko, Angela S.; Bursik, Marcus

2012-01-01

369

Hydrological extreme events with Mike Basin  

NASA Astrophysics Data System (ADS)

This work is part of a broader project which aims to develop an integrated system to model and simulate of the hydrological cycle processes at river basin scale. All these processes involved in the dynamics of a watershed, which play an important role in the proper management and sustainable use of water resources, are influenced by many factors (e.g. soil use, vegetation cover, weather and climate) being of particular importance, all aspects related to the occurrence, amount and the spatial-temporal distribution of precipitation. We focus our work on the use of the MIKE Basin model and apply it to the Corgo River basin, which is a tributary of the Douro river, located in the Portuguese region of Trás-os-Montes and Alto Douro. Different datasets were used to characterize and model the river basin catchment hydrological processes, namely temperature, precipitation and runoff registered in several weather/hydrometric stations from the Institute of Information System for Water Resources (http://snirh.pt/) as well as land use/soil occupation and topography maps. The MIKE BASIN model runs on a Geographic Information System (GIS) to perform hydrologic modeling at basin-scale. This software allows a set of multisectoral water demands (domestic and industrial water supply, irrigation, hydropower generation, among others) and provides simulation and visualization in both space and time. We start by using the topography, soil type, soil use and vegetation cover of the region. Then the model is calibrated and tested, comparing model runoff estimates with observed data. Finally, the model is used to simulate the river basin catchment behavior to the typical conditions of the hydrological extreme events namely, heavy precipitation and drought. We present the geologic, hydrologic and climatologic characterization of the Corgo river catchment, list the most important factors that control the water availability in the river basin, describe the MIKE BASIN model calibration process, and discuss the role of each factor through sensibility tests and the estimated impacts of extreme events on the river basin management.

Pereira, M. G.; Carvalho, S.; Fernandes, L.; Caramelo, L.; Alencoão, A.

2012-04-01

370

Carboniferous clastic-wedge stratigraphy, sedimentology, and foreland basin evolution: Black Warrior basin, Alabama and Mississippi  

SciTech Connect

Carboniferous clastic-wedge stratigraphy and sedimentology in the Black Warrior basin of Alabama and Mississippi indicate deposition in an evolving foreland basin flanking the Appalachian-Ouachita fold-thrust belt. The strata reflect specific responses to foreland basin subsidence, orogenic activity, sediment supply, and dispersal systems. Definition of the regional stratigraphy of the clastic wedge provides for interpretation of the foreland basin subsidence history by enabling quantitative reconstruction of regional compaction and subsidence profiles. Comparison of the interpreted subsidence history with model profiles of foreland basin subsidence (predicted from loading and flexure of continental lithosphere) allows evaluation of mechanical models in terms of observed clastic-wedge sedimentology and stratigraphy. Mechanical modeling of foreland basin subsidence predicts formation of a flexural bulge that migrates cratonward ahead of the subsiding foreland basin during loading. In the Black Warrior basin, local stratigraphic thins, pinch-outs, and areas of marine-reworked sediments suggest migration of the flexural bulge. Comparison of flexural bulge migration with thermal maturation history allows evaluation of timing of stratigraphic trapping mechanisms with respect to onset of hydrocarbon generation.

Hines, R.A.

1986-05-01

371

Integrated basin chemical modelling redefines the geothermal evolution of the Arkoma Basin, Oklahoma, USA  

Microsoft Academic Search

Amoco utilized a variety of exploration technologies to become the economic success leader (EPs > 65%) in the thrusted Pennsylvanian Spiro sandstone play of the Arkoma basin, Oklahoma. It was found early in exploitation analysis that conventional thermal-history methodologies gave convicting results about the overall geothermal evolution of the basin. Within the thrusted terrain, vitrinite reflectance and bottom-hole temperature data

S. S. Foland; I. D. Meshri; S. L. Bolton

1995-01-01

372

The Deep Structure of Lunar Basins: Clues to the Understanding of Basin Formation and Modification  

NASA Technical Reports Server (NTRS)

Basin excavation has played a major role in shaping the surface and subsurface of the Moon. Though photogeologic observations provide estimates for the present volumes of lunar impact basins and their ejecta deposits, there is not sufficient information to describe completely either the geometry of the basins at the time of impact or their modification with time. Determination of the structure of the crust and upper mantle beneath large basins can provide important insight into the thermal and mechanical processes associated with basin formation and modification as well as the differences in these processes as functions of basin age and size. Using observed gravity and topography together with the seismically determined crustal thickness of the central nearside, a model for the structure of the crust and upper mantle of the nearside of the Moon is presented. With this model the deep structure of the largest lunar basins are compared. The implications for the processes of basin formation and modification at different stages in lunar history are explored.

Bratt, S. R.; Solomon, S. C.; Head, J. W.; Thurber, C. H.

1985-01-01

373

Hydrocarbon systems in the East Texas basin: A basin modeling approach  

SciTech Connect

The East Texas basin is a prolific mature hydrocarbon province, producing oil and gas from several reservoirs and a variety of trap types. Much of the liquid hydrocarbons discovered in the basin are trapped in structures related to movement of the underlying Louann Salt. By determining the structural evolution of the basin, a framework was constructed to model the generation of hydrocarbons in the basin. Geochemical data indicate three major source horizons: the Smackover formation (Jurassic oil), shales in the Pearsal Group (Lower Cretaceous oil), and the Eagleford shale (Upper Cretaceous oil). The Jurassic source is mature throughout the basin and began to expel oil approximately 88 Ma. The distribution of Jurassic oil in Cretaceous reservoirs shows that vertical migration routes predominated. Lower Cretaceous source rocks are mature only in the deep, central part of the basin where expulsion began around 47 Ma Distribution of this oil type suggests that Lower Cretaceous source rocks occur only in localized areas of the East Texas basin. The Eagleford shale is immature in the main part of the basin, but it is mature south of the Angelina-Caldwell flexure, where is reached peak generation approximately 20 Ma. Lateral migration explains the distribution of this oil. Migration routes to the giant East Texas field may be 60 mi or more.

Wescott, W.A.; Hood, W.C. (Amoco Production Company, Houston, TX (United States))

1993-09-01

374

The long wavelength topography of Beethoven and Tolstoj basins, Mercury  

NASA Astrophysics Data System (ADS)

Topography derived from Mariner 10 stereo images is used to characterize the interior structure of two mercurian basins, Beethoven and Tolstoj. Beethoven and Tolstoj basins are shallow (~2.5 km and ~2 km deep, respectively) and relatively flat-floored. Beethoven basin has an interior topographic rise near the northwest margin. The topography of Beethoven and Tolstoj basins is similar to that of lunar mare-filled basins. Well-developed basin-concentric wrinkle ridges and arcuate graben associated with lunar mascons are absent in both Beethoven and Tolstoj basins. The lack of mascon tectonic features suggests that either 1) the mercurian basins have a relatively thin veneer of fill material, 2) Mercury's elastic lithosphere was too strong for significant lithospheric flexure and subsidence to occur, or 3) the basin fill material has little or no density contrast with the surrounding crust and thus exerts little net load on the mercurian lithosphere.

André, Sarah L.; Watters, Thomas R.; Robinson, Mark S.

2005-11-01

375

Perspective of gas exploration in Ying-Qiong Basin  

SciTech Connect

The Yinggehai and Qiongdongnan Basin (Ying-Qiong Basin) in the northwest part of the South China Sea is a Cenozoic sedimentary basin, which has fast-subsiding and thick sediments. The maximum Cenozoic sediments in the center part of the basin is 20,000 m. Six sets of source rocks with prevailing Type III kerogen were developed in the basin, which has a great potential for gas generation. Different types of reservoirs and traps, leading to different assemblages of source rocks, reservoirs, and cap rocks, form good gas pools. Abnormal high temperature and high pressure in the basin resulted in many mud diapirs and made the generation, migration, and accumulation of gas more colorful. Up to now, four gas fields have been discovered in the basin. A large number of anticlines and stratigraphic-lithologic traps in the basin provide an extensive area for gas exploration. The perspective of gas exploration in the basin is vast and bright.

He, Hanyi; Zhongtiang Hu (China Offshore Oil Nanhai West Corp., Zhanjiang, Guangdong Province (China))

1996-01-01

376

Perspective of gas exploration in Ying-Qiong Basin  

SciTech Connect

The Yinggehai and Qiongdongnan Basin (Ying-Qiong Basin) in the northwest part of the South China Sea is a Cenozoic sedimentary basin, which has fast-subsiding and thick sediments. The maximum Cenozoic sediments in the center part of the basin is 20,000 m. Six sets of source rocks with prevailing Type III kerogen were developed in the basin, which has a great potential for gas generation. Different types of reservoirs and traps, leading to different assemblages of source rocks, reservoirs, and cap rocks, form good gas pools. Abnormal high temperature and high pressure in the basin resulted in many mud diapirs and made the generation, migration, and accumulation of gas more colorful. Up to now, four gas fields have been discovered in the basin. A large number of anticlines and stratigraphic-lithologic traps in the basin provide an extensive area for gas exploration. The perspective of gas exploration in the basin is vast and bright.

He, Hanyi; Zhongtiang Hu [China Offshore Oil Nanhai West Corp., Zhanjiang, Guangdong Province (China)

1996-12-31

377

Streamflow changes over Siberian Yenisei River Basin  

NASA Astrophysics Data System (ADS)

This study analyzes long-term (1935-99) monthly discharge data for the major sub-basins within the Yenisei River watershed in order to document significant streamflow changes induced by reservoir regulations and by natural variations/changes. The results show that both the unregulated upper basin and major lower streams of the watershed experienced streamflow decreases in the early melt period and discharge increases in the late melt season. These changes in snowmelt runoff pattern suggest a delay in snowcover melt in the Yenisei basin perhaps associated with cooling trends during the snowmelt months over central Siberia. This study also demonstrates that the reservoir regulation has significantly altered the monthly discharge regimes in northeast and the upper portions of the Yenisei basin. Constructions of four large dams in the northeast Yensiei regions reduced the summer peak flows in the Angara valley by 15-30% and increased the winter low flows by 5-30%. Operations of two large reservoirs in the upper Yenisei regions enhanced the winter flows by 45-85% and reduced the summer flows by 10-50%. These alterations lead to a streamflow regime change toward less seasonal variation over the eastern and lower Yenisei basin. Because of reservoir regulations, discharge records collected at the Yenisei basin outlet do not always represent natural changes and variations, they tend to underestimate the natural streamflow trends in summer and overestimate the trends in winter and fall seasons. Cold season discharge increase over the Yenisei river is not natural-caused, but mainly the effect of reservoir regulations in the Yenisei basin.

Yang, Daqing; Ye, Baisheng; Kane, Douglas L.

2004-08-01

378

Kandik basin stratigraphy, sedimentology, and structure  

SciTech Connect

East-central Alaska's Kandik basin is a structural remnant of a larger Permian to Cretaceous basin. Permian shallow-water Tahkandit Limestone and Step Conglomerate at the base of the sequence rest unconformably on Paleozoic chert-pebble conglomerate, siliceous shale, and limestone. These Permian rocks are overlain by Triassic to Lower Cretaceous open-ocean Glenn Shale, which grades upward into Lower Cretaceous (Valanginian) hummocky cross-bedded (outer shelf to upper slope) Keenan Quartzite. The quartzite grades upward into fine-grained north-northeast-flowing turbidites of the Biederman Argillite (undated). East-northeast-flowing pebbly turbidites of the Kathul Graywacke (undated) overlie Biederman strata. Locally, Cretaceous (Albian and younger) through Paleogene nonmarine rocks unconformably overlie the Kandik basin sequence. The Mesozoic part of the sequence is similar to that of Manley basin, northwest Yukon Territory, and much of the North Slope. East-directed flow for Kandik basin strata may require paleogeographic reconstructions involving local to large-scale palinspastic rotations or a western source of chert detritus. Deformation of the Mesozoic sequence in Kandik basin west of the US-Canada border shows northwest-southeast shortening. Shaly units are tightly folded with well-developed cleavage striking northeast. Strikes of beds swing from northeast to east in the extreme southwestern part of the basin, suggesting clockwise rotation. Thrust faults, reverse faults, and fold axes trend east to northeast; normal faults trend northwest. These relations are all consistent with, and probably are closely related to, right slip on the west-northwest-trending Tintina fault.

Wiley, T.J.; Howell, D.G.; Kauffman-Linam, L.; Boundy-Sanders, S.; Murray, R.W.; Jones, D.L.

1987-05-01

379

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

USGS Publications Warehouse

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, and solute fluxes and mineral weathering rates were explored for nine alpine/subalpine basins in Rocky Mountain National Park, Colorado, using correlation analyses for 1993 and 1994 data. Stream-water nitrate fluxes were correlated positively with basin characteristics associated with the talus environment; i.e., the fractional amounts of steep slopes (??? 30??), unvegetated terrain and young debris (primarily Holocene till) in the basins, and were correlated negatively with fractional amounts of subalpine meadow terrain. Correlations with nitrate indicate the importance of the talus environment in promoting nitrate flux and the mitigating effect of areas with established vegetation, such as subalpine meadows. Total mineral weathering rates for the basins ranged from about 300 to 600 mol ha-1 year -1. Oligoclase weathering accounted for 30 to 73% of the total mineral weathering flux, and was positively correlated with the amount of old debris (primarily Pleistocene glacial till) in the basins. Although calcite is found in trace amounts in bedrock, calcite weathering accounted for up to 44% of the total mineral weathering flux. Calcite was strongly correlated with steep slope, unvegetated terrain, and young debris-probably because physical weathering in steep-gradient areas exposes fresh mineral surfaces that contain calcite for chemical weathering. Oligoclase and calcite weathering are the dominant sources of alkalinity in the basins. However, atmospherically deposited acids consume much of the alkalinity generated by weathering of calcite and other minerals in the talus environment. Published in 2001 by John Wiley and Sons, Ltd.

Sueker, J.K.; Clow, D.W.; Ryan, J.N.; Jarrett, R.D.

2001-01-01

380

Role of Storage in Arctic Basins  

NASA Astrophysics Data System (ADS)

The arctic environment can be characterized as being located in the zone of continuous permafrost and of extreme annual energy fluxes/input (from winter to summer). The energy regime of the arctic has a strong influence on many water storage and release processes such as snow/glacier accumulation and ablation, ground ice, near surface ponding of water in lakes, ponds, and wetlands. Additionally, simulation of stream flow and other hydrologic processes is challenging as the extreme environment has an strong influence on storage processes in both space and time. Many of the factors that have a control on the storage process are not easily quantified beyond the point scale. In this study, we attempt to approximate the storage processes through hydrograph analysis. Following the general procedure outline in Kirchner (2009), a simple rainfall-runoff model was applied to three basins of various spatial extent in northern Alaska. A simple, first-order, non-linear differential equation that describes the storage-discharge relationship was derived from 4-5 years discharge data and is modified with active layer position. The storage-discharge relationship, along with precipitation measurements and evapotranspiration (derived using the Priestley-Taylor equation), is used to simulate the basin discharge. The simulation basins are the Imnaviat Creek Basin (~2.2 km2), the Upper Kuparuk River Basin (~142 km2), and the Putuligayuk River Basin (~470 km2). All three watersheds are north draining and are underlain with continuous permafrost. The Imnaviat Creek and Upper Kuparuk River basins are located in the northern foothills of the Brooks Range. The active layer depth ranges from 40-60 cm. In these basins, the ablation of the snow pack is a major hydrologic event of the year, although peak events occur during large summer precipitation events. The response of these large precipitation events are largely controlled by the active layer position and available soil-water capacity. The Putuligayuk River is located on the Coastal Plain and is characterized by an extremely low gradient and numerous ponds. In this basin, the dominant storage processes are snow melt ablation (largest hydrologic event every year) and surface strorage, largely controlled by the net precipitation minus evaporation. Simulation results from each of these watersheds will be presented.

Bolton, W. R.; Kane, D. L.; Hinzman, L. D.

2010-12-01

381

Quaternary Faults and Basin-fill Sediments of the Las Vegas Basin, Southern Nevada  

NASA Astrophysics Data System (ADS)

The N-S elongated extensional Las Vegas basin, southern Nevada, contains 100's of meters of Cenozoic basin-fill sediments that are cut by several Quaternary (Q) faults. These faults define or influence the basin geometry. The basin is generally an asymmetrical half graben defined by the W-dipping, Q Frenchman Mountain fault (FMF) along its E side and a series of smaller offset E-dipping faults to the W. The N terminus of the basin is controlled by the Las Vegas Valley shear zone, along which the majority of the offset occurred prior to the Q. Here, we asses the influence of the Q faults on the distribution of the sedimentary units. Well, exposure, seismic reflection and seismic refraction data show that sedimentary units of different grain sizes or seismic velocity dominate different parts of the basin. Sections dominated by coarse clastic deposits occupy a narrow area along the E side of the basin. Coarse clastic sediments are mixed with finer grained sediments in a broader area along the W side of the basin. Based on provenance and alluvial fan distribution, the coarse deposits along the E side of the basin appear to be trapped in close proximity to the W-dipping FMF. The coarse-grained deposits along the opposite, W side of the basin, are sourced from the nearby Spring Mountains. Because of the structural asymmetry of the basin, these sediments traveled farther from their source area than those on the E side. Some of these E-dipping faults influence the depth to Paleozoic bedrock and some faults form small sub-basins filled with finer grained sediments. Along a WNW trend near the center of the basin and near the present-day Las Vegas Wash, a change in the grain size distribution occurs up stratgraphic section: continuous clay layers are less common and coarse-grained deposits are more common. This difference may reflect a change from internal drainage early in the basin history to external drainage through the Las Vegas Wash in the latter history of the basin-fill sedimentation. This interpretation implies that the FMF was breached by a wash connected to the Colorado River drainage system during basin development. The basin fill deposits suggest an early history of alluvial fan dominated deposits showing internal drainage. That depositional system was followed by E- and W-sloping alluvial fans cut by a NW-trending external drainage system that probably flowed to the Colorado River. The greatest structural influence on sediment distribution was from the Q FMF on the E side of the basin and the dominantly Miocene Las Vegas Valley shear zone on the north, but the structural influence is reduced as Colorado River system and base level imposes on the basin up section.

Taylor, W. J.; Fossett, E.; Luke, B.; Snelson, C.; Rasmussen, T.; McCallen, D.; Rodgers, A.; Louie, J.

2003-12-01

382

Hydrocarbon potential of lower Magdalena basin  

SciTech Connect

The Lower Magdalena basin complex of Colombia has an areal extent of more than 87,000 km{sup 2}. The geologic setting of the different subbasins of the Lower Magdalena presents attractive play concepts for the generation, entrapment, and production of hydrocarbons. The sedimentary sequence within the basin attains a thickness in excess of 12,200 m, with the preponderance of this section being of Tertiary age. This major thickness of section contains good source and reservoir rocks and seals and an abundance of structural and stratigraphic traps, which make the basin attractive for new interpretation and evaluation. The Plato, San Jorge, and Sinu subbasins lie within the Lower Magdalena complex. Each of these presents different geological conditions, thereby offering a variety of play concepts for hydrocarbon exploration. Previous exploration in the Lower Magdalena has resulted in the discovery of 10 small to moderate-size fields, which have produced nearly 200 million bbl of oil. The density of exploration drilling within the basin is one well/435 km{sup 2}, thereby allowing the opportunity for more discoveries to be realized. The existence of a thick Tertiary section with excellent source beds and a tectonic history that allows for both structural and stratigraphic traps presents an excellent opportunity for the application of modern exploration techniques to reevaluate the potential of a basin that has not been thoroughly evaluated due to complex exploration problems.

Torres, E.; Valderrama, R. (Univ. of South Carolina, Columbia (USA))

1989-03-01

383

Shallow basins on Mercury: Evidence of relaxation?  

NASA Astrophysics Data System (ADS)

Stereo-derived topographic models have shown that the impact basins Beethoven and Tolstoj on Mercury are shallow for their size, with depths of 2.5 and 2 (± 0.7) km, respectively, while Caloris basin has been estimated to be 9 (± 3) km deep on the basis of photoclinometric measurements. We evaluate the depths of Beethoven and Tolstoj in the context of comparable basins on other planets and smaller craters on Mercury, using data from Mariner 10 and the first flyby of the MESSENGER spacecraft. We consider three scenarios that might explain the anomalous depths of these basins: (1) volcanic infilling, (2) complete crustal excavation, and (3) viscoelastic relaxation. None of these can be ruled out, but the fill scenario would imply a thick lithosphere early in Mercury's history and the crustal-excavation scenario a pre-impact crustal thickness of 15-55 km, depending on the density of the crust, in the area of Beethoven and Tolstoj. The potential for viscous relaxation of Beethoven, Tolstoj, and Caloris is explored with a viscoelastic model. Results show that relaxation of these basins could occur at plausible heat flux values for a range of crustal thicknesses. However, the amplitude of current topographic relief points to a crustal thickness of at least 60 km under this hypothesis. Relaxation of Caloris may have occurred if the floor is underlain by crust at least 20 km thick. We discuss future observations by MESSENGER that should distinguish among these scenarios.

Mohit, P. Surdas; Johnson, Catherine L.; Barnouin-Jha, Olivier; Zuber, Maria T.; Solomon, Sean C.

2009-08-01

384

Exploration in the Ombilin Intermontane Basin, West Sumatra  

SciTech Connect

The Ombilin Basin is a Tertiary intermontane basin located within the Barisan Mountain Range of Sumatra. Oil exploration commenced in the Ombilin Basin in the early 1980s when geological mapping was carried out, a synthetic aperture radar survey was flown, and a basin-wide geophysical survey was completed. This effort led to the drilling of Sinimar No. 1 to a total depth 3020 m. Sinimar No. 1 was a historic well in Indonesia`s oil industry since it was the first oil exploration well drilled in the Ombilin Basin and also the first well drilled in an intermontane basin in Indonesia. Oil, gas and condensate was tested in the well. An integrated interpretation of the well, geophysical and outcrop data indicates that despite its small areal size (30 km x 50 km), the Ombilin Basin is a deep pull-apart basin containing up to 4500 m of Tertiary sediments, ranging in age from Middle Eocene to Early Miocene. The basin currently is in an intermontane basin structural setting but it was also an intermontane basin during its Early Tertiary depositional history. During the Eocene, alluvial fans and massive debris flows were deposited on the basin margins and a large lake occupied the basin center. Fluvial deposition occurred in the basin during the Oligocene followed by deposition of marine shales, sandstones, and isolated reefs during the Miocene. Although the Ombilin Basin is located within Sumatra`s magmatic arc and is partially covered by volcanics from extinct and active volcanoes, the subsurface temperature gradients of 1.62 deg. F/100 ft. recorded in Sinimar No. I and 1.47 deg F/100 ft. measured in a deep (670 m) coal exploration core hole are significantly cooler than the average subsurface temperature gradients in the Sumatra back-arc basins. Organic-rich Eocene lacustrine shales are the likely source rocks for the hydrocarbons tested in Sinimar No. 1 and the oil seeps located along the basin margins.

Koning, T. [Texaco Overseas (Nig.) Petroleum Co., Lagos (Nigeria)

1996-12-31

385

Exploration in the Ombilin Intermontane Basin, West Sumatra  

SciTech Connect

The Ombilin Basin is a Tertiary intermontane basin located within the Barisan Mountain Range of Sumatra. Oil exploration commenced in the Ombilin Basin in the early 1980s when geological mapping was carried out, a synthetic aperture radar survey was flown, and a basin-wide geophysical survey was completed. This effort led to the drilling of Sinimar No. 1 to a total depth 3020 m. Sinimar No. 1 was a historic well in Indonesia's oil industry since it was the first oil exploration well drilled in the Ombilin Basin and also the first well drilled in an intermontane basin in Indonesia. Oil, gas and condensate was tested in the well. An integrated interpretation of the well, geophysical and outcrop data indicates that despite its small areal size (30 km x 50 km), the Ombilin Basin is a deep pull-apart basin containing up to 4500 m of Tertiary sediments, ranging in age from Middle Eocene to Early Miocene. The basin currently is in an intermontane basin structural setting but it was also an intermontane basin during its Early Tertiary depositional history. During the Eocene, alluvial fans and massive debris flows were deposited on the basin margins and a large lake occupied the basin center. Fluvial deposition occurred in the basin during the Oligocene followed by deposition of marine shales, sandstones, and isolated reefs during the Miocene. Although the Ombilin Basin is located within Sumatra's magmatic arc and is partially covered by volcanics from extinct and active volcanoes, the subsurface temperature gradients of 1.62 deg. F/100 ft. recorded in Sinimar No. I and 1.47 deg F/100 ft. measured in a deep (670 m) coal exploration core hole are significantly cooler than the average subsurface temperature gradients in the Sumatra back-arc basins. Organic-rich Eocene lacustrine shales are the likely source rocks for the hydrocarbons tested in Sinimar No. 1 and the oil seeps located along the basin margins.

Koning, T. (Texaco Overseas (Nig.) Petroleum Co., Lagos (Nigeria))

1996-01-01

386

Barents Sea crustal architecture and basin development  

NASA Astrophysics Data System (ADS)

The Barents Sea continental shelf is characterized by a complex tectonic history and thus comprises a wide range of crustal and basin architectures that formed in response to different geological processes. Overlapping Paleozoic orogenies (Timanian, Caledonian, Uralian) preceded multiple rift episodes mainly affecting the western Barents Sea and eventual breakup with Greenland to the west and Lomonosov Ridge to the north. Recent work related to the PETROBAR and BarMod projects has provided new details on basin architecture, tectonic and thermal histories, stratigraphy, paleogeography, paleo-water depths and the role of the basement grain in the structuring of the Barents Sea basins. The eastern Barents Sea comprises a wide and deep sag basin that formed by rapid subsidence in Late Permian-Early Triassic times, most likely in response to basin-forming mechanisms other than rifting. The deep East Barents Sea Basin was filled by thick uppermost Permian and Triassic sediments prograding westwards from uplifted source areas mainly in the SE (Urals). In the western Barents Sea we find more typical rift basins formed in response to at least three major post-Caledonian rift phases: Carboniferous, Late Jurassic-Early Cretaceous, and Late Cretaceous-early Paleogene. The rifting activity migrated westwards through successive tectonic phases. Carboniferous rifting affected the entire western Barents Sea and gave rise to NE-SW to N-S trending horst and graben structures following a Caledonian basement grain. These structures were covered by a regional carbonate platform before renewed faulting affected the SW Barents Sea in Late Permian time. The major prograding system reached the western Barents Sea in earliest Triassic time gradually filling in a regional basin of considerable waterdepths. Late Jurassic-Early Cretaceous oblique extension and formation of the deep SW Barents Sea basins was linked to the North Atlantic-Arctic plate tectonic evolution. Regional uplift associated with the Early Cretaceous High Arctic Large Igneous Province gave rise to a depositional system characterized by north to south progradation covering most of the Barents Sea. Volcanic extrusives are preserved in the northern Barents Sea, mainly on Franz Josef Land and eastern Svalbard, while intrusives are found widespread, particularly in the deep East Barents Sea Basin. A Late Cretaceous-Early Paleogene mega-shear system along the western Barents Sea-Svalbard margin (De Geer Zone) linked rifting, breakup and initial opening of the Norwegian-Greenland Sea and the Arctic Eurasia Basin. Narrow pull-apart basins formed within this dominantly shear system, in particular at a releasing bend in the margin SW of Bjørnøya. A restraining bend SW of Svalbard gave rise to the transpressional Spitsbergen Fold-and-Thrust Belt. Compressional structures of different styles are found widespread in the Barents Sea region. The nature and timing of these are difficult to constrain in many areas due to later uplift and erosion, but we expect that there are different causes and timing involved. At the western margin we see evidence of compressional deformation as young as Miocene in age. The entire Barents Shelf was uplifted and eroded during Neogene time and thick fans of Plio-Pleistocene glacial sediments were formed in front of bathymetric troughs characteristic of both the western and northern Barents Sea. Most of the uplift is closely linked to the glacial erosion, but tectonic uplift occurred prior to the glaciations.

Faleide, J. I.

2012-04-01

387

Independent focuses Philippines exploration on Visayan basin  

SciTech Connect

Cophil Exploration Corp., a Filipino public company, spearheaded 1995 Philippine oil and gas exploration activity with the start of its gas delineation drilling operations in Libertad, northern Cebu. Cophil and its Australian partners, Coplex Resources NL and PacRim Energy NL, have set out to complete a seven well onshore drilling program within this block this year. The companies are testing two modest shallow gas plays, Libertad and Dalingding, and a small oil play, Maya, all in northern Cebu about 500 km southeast of Manila. Following a short discussion on the geology and exploration history of the Visayan basin, this article briefly summarizes Cophil`s ongoing Cebu onshore drilling program. Afterwards, discussion focuses on identified exploration opportunities in the basin`s offshore sector.

Rillera, F.G. [Cophil Exploration Corp., Manila (Philippines)

1995-08-21

388

The origin of lunar mascon basins.  

PubMed

High-resolution gravity data from the Gravity Recovery and Interior Laboratory spacecraft have clarified the origin of lunar mass concentrations (mascons). Free-air gravity anomalies over lunar impact basins display bull's-eye patterns consisting of a central positive (mascon) anomaly, a surrounding negative collar, and a positive outer annulus. We show that this pattern results from impact basin excavation and collapse followed by isostatic adjustment and cooling and contraction of a voluminous melt pool. We used a hydrocode to simulate the impact and a self-consistent finite-element model to simulate the subsequent viscoelastic relaxation and cooling. The primary parameters controlling the modeled gravity signatures of mascon basins are the impactor energy, the lunar thermal gradient at the time of impact, the crustal thickness, and the extent of volcanic fill. PMID:23722426

Melosh, H J; Freed, Andrew M; Johnson, Brandon C; Blair, David M; Andrews-Hanna, Jeffrey C; Neumann, Gregory A; Phillips, Roger J; Smith, David E; Solomon, Sean C; Wieczorek, Mark A; Zuber, Maria T

2013-06-28

389

Subsidence modeling of the Sabah Basin, a foreland basin, Northwest Borneo, Malaysia  

SciTech Connect

The Sabah Basin is located on the northwestern side of Borneo. It is a piggy back northeast-southwest-trending basin, riding on a north-westward directed imbricate thrust system. The basin contains approximately 10 to 12 km of sediment in the deepest part deposited in two main episodes of basin development; (1) a pre-early middle Miocene phase of generally deep-marine clastic deformation, which was later subjected to compression and (2) a post-early middle Miocene episode of clastic deposition, comprising bathyal to upper coastal plain sediments. Tectonic subsidence of the post-middle Miocene sequence was determined using the 1-D Airy and 2-D flexure backstripping techniques and wells and selected dip profiles, where the effects of compaction and sediment loading were removed. Variation in paleowater depth was also taken into account. The results show an extremely rapid subsidence phase dominating the earlier part of the basin history, with the later part corresponding to passive basin infilling. The boundary between these two phases becomes younger toward the northwest. The rapid subsidence phase is attributed to tectonic loading, possibly as a result of continuing thrusting at the basin margin. The results also imply that sedimentary sequences formed during the earlier phase were tectonically controlled and marked by transgressive events, while those deposited during the later phase bear the imprints of both tectonic and eustasy.

Azim-Ibrahim, N. (Petronas Research and Scientific Services, Kuala Lumpur (Malaysia)); White, N. (Univ. of Cambridge (United Kingdom))

1994-07-01

390

Avian cholera in Nebraska's Rainwater Basin  

USGS Publications Warehouse

The first report of avian cholera in North America occurred in northwestern Texas in winter 1944 (Quortrup et al. 1946). In 1975, mortality from avian cholera occurred for the first time in waterfowl in the Rainwater Basin of Nebraska when an estimated 25,000 birds died (Zinkl et al. 1977). Avian cholera has continued to cause mortality in wild birds in specific areas of the Basin each spring since. Losses of waterfowl from avian cholera continue to be much greater in some of the wetlands in the western part of the Basin than in the east. Several wetlands in the west have consistently higher mortality and are most often the wetlands where initial mortality is noticed each spring (Figure 1). The establishment of this disease in Nebraska is of considerable concern because of the importance of the Rainwater Basin as a spring staging area for waterfowl migrating to their breeding grounds. The wetlands in this area are on a major migration route used by an estimated 5 to 9 million ducks and several hundred thousand geese. A large portion of the western mid-continental greater white-fronted goose (Anser albifrons) population stage in the Basin each spring. Occasionally, whooping cranes (Grus americana) use these wetlands during migration, and lesser sandhill cranes (Grus canadensis) staging on the nearby Platte River sometimes use wetlands where avian cholera occurs (Anonymous 1981). Our objectives were to determine whether certain water quality variables in the Rainwater Basin differed between areas of high and low avian cholera incidence. These results would then be used for laboratory studies involving the survivability of Pasteurella multocida, the causative bacterium of avian cholera. Those studies will be reported elsewhere.

Windingstad, R.M.; Hurt, J.J.; Trout, A.K.; Cary, J.

1984-01-01

391

Paleohydrogeology of the San Joaquin basin, California  

SciTech Connect

Mass transport can have a significant effect on chemical diagenetic processes in sedimentary basins. This paper presents results from the first part of a study that was designed to explore the role of an evolving hydrodynamic system in driving mass transport and chemical diagenesis, using the San Joaquin basin of California as a field area. The authors use coupled hydrogeologic models to establish the paleohydrogeology, thermal history, and behavior of nonreactive solutes in the basin. These models rely on extensive geological information and account for variable-density fluid flow, heat transport, solute transport, tectonic uplift, sediment compaction, and clay dehydration. In the numerical simulations, tectonic uplift and ocean regression led to large-scale changes in fluid flow and composition by strengthening topography-driven fluid flow and allowing deep influx of fresh ground water in the San Joaquin basin. Sediment compaction due to rapid deposition created moderate overpressures, leading to upward flow from depth. The unusual distribution of salinity in the basin reflects influx of fresh ground water to depths of as much as 2 km and dilution of saline fluids by dehydration reactions at depths greater than {approximately}2.5 km. Simulations projecting the future salinity of the basin show marine salinities persisting for more than 10 m.y. after ocean regression. Results also show a change from topography- to compaction-driven flow in the Stevens Sandstone at ca. 5 Ma that coincides with an observed change in the diagenetic sequence. Results of this investigation provide a framework for future hydrologic research exploring the link between fluid flow and diagenesis.

Wilson, A.M.; Garven, G. [Johns Hopkins Univ., Baltimore, MD (United States). Morton K. Blaustein Dept. of Earth and Planetary Sciences; Boles, J.R. [Univ. of California, Santa Barbara, CA (United States). Dept. of Geological Sciences

1999-03-01

392

Atlantic Mesozoic marginal basins: an Iberian view  

SciTech Connect

In the light of theoretical models for crustal stretching that precedes ocean opening, it is unlikely that Iberian basins have mirror image counterparts beneath North American or other European continental shelves. However, certain Iberian sedimentary sequences are comparable to those found in other basins. Of particular note are (1) the almost identical pre-rift sequences in all these areas, (2) the development of Upper Jurassic carbonate buildups in Portugal, Morocco, and beneath the Scotian Shelf, and (3) the hydrocarbon-bearing Upper Jurassic and Lower Cretaceous synrift and postrift siliciclastics of North America, Iberia, and Aquitaine. In the prerift sequences, Triassic red beds are capped by evaporites, which subsequently influenced the structural development of basins. Intertidal and supratidal carbonates occur at the base of the Jurassic and are overlain by Lower and Middle Jurassic limestone-shale sequences, which in places contain bituminous shales. In Portugal only, resedimented carbonates of Toarcian-Aalenian age are associated with an uplifted basement horst. In Portugal, Aquitaine, and eastern Canada, Middle Jurassic high-energy carbonate platforms developed. Synrift siliciclastic sequences show spectacular evidence for deposition within fault-bounded basins. In Portugal, lower Kimmeridgian clastics are up to 3 km thick, but Upper-Lower Cretaceous sequences are relatively thin (ca. 1 km), in contrast to those of the Basco-Cantabrian region where they exceed 10 km. In the latter region occurs the fluvially dominated Wealden (Upper Jurassic-Neocomian) and Urgonian carbonate platforms and associated basinal sediments. In the Asturias basin, Kimmeridgian shales and fluvially dominated deltaic sandstones succeed conglomeratic fluvial sandstones of uncertain age.

Wilson, R.C.L.

1987-05-01

393

Geothermal resources of Wyoming sedimentary basins  

SciTech Connect

Geothermal resources of Wyoming sedimentary basins have been defined through analysis of over 14,000 oil well bottom-hole temperatures, thermal logging of 380 wells, measurement of rock thermal conductivities, calculation of 60 heat-flow values, drilling of 9 geothermal exploratory wells, conductive thermal modeling, and the study of existing geologic, hydrologic, and thermal spring data. All data have been integrated into interpretations of the thermal structure of the Big Horn, Wind River, Washakie, Great Divide, Green River, Laramie, Hanna, and Shirley basins of Wyoming. Controlling factors for the formation of geothermal resources in these basins are regional heat flow, rock thermal conductivity values, depths to regional aquifers, and hydrologic flow directions. Regional basin heat-flow values range from about 40 to 80 milliwatts/m/sub 2/; measured thermal conductivities are in the general range of 1.5 to 4.0 watts/m/sup 0/K; and depths to aquifers are up to 11,000 m (36,000 ft). This results in regional geothermal gradients for Wyoming basins in the range of 15/sup 0/ to 40/sup 0/C/km (44/sup 0/ to 116/sup 0/F/mi) with predicted maximum aquifer temperatures near 300/sup 0/C (570/sup 0/F). Anomalous geothermal areas within the basins contain measured thermal gradients as high as 400/sup 0/C/km (1,160/sup 0/F/mi) over shallow depth intervals. These anomalous areas are the combined result of local geologic structures and hydrologic flow. A simplified model for such areas requires water movement through a syncline with subsequent heating due to regional heat flow and thermal conductivities of overlying rock units. Consequent flow of the heated water up over an anticline produces a localized area of anomalous geothermal gradients.

Heasler, H.P.

1983-08-01

394

Modelling depositional shifts between sedimentary basins: Sediment pathways in Paratethys basins during the Messinian Salinity Crisis  

NASA Astrophysics Data System (ADS)

The evolution of sedimentary basins separated by uplifted topographic barriers is characterised by gradual regressive deposition until one of the basins is filled and its sedimentation bypasses to the adjacent basin, defining a depositional shift. One of the critical parameters controlling these depositional shifts is sea level variation, its drop potentially triggering a depositional shift by cancelling the available accommodation space. Conversely, a sea level rise can create new accommodation space resulting in a depositional shift towards a previously overfilled basin. Here we use a three dimensional numerical model to study the sedimentary response to sea level variations of a system of two basins. In this model, a single mountainous source area is feeding an intra-continental basin that is separated by a submarine barrier from another basin with normal marine bathymetry. The sedimentary response is modelled during a cycle of sea-level drop and subsequent rebound that exposes the barrier to sub-aerial erosion. The examined parameters are the barrier height, magnitude and duration of sea level change, climate and flexural rigidity. Modelling demonstrates that shifting the bulk of sedimentation from the continental basin to the open marine environment requires some minimum magnitudes and durations of sea level drop. Moreover, given the specific geometry and parameters of our model, an intervening barrier causes a delay of up to 0.35 Myr, depending on the magnitude and duration of sea level change, to the onset of an outward depositional shift when compared to a situation without a barrier. These depositional shifts depend on changes in climate, magnitude and duration of sea level change. Model results are applied to the connectivity between the Black Sea and the Dacic Basin, suggesting that depositional shifts observed during the Messinian Salinity Crisis can be explained by a sea level drop of > 1000 m in the Black Sea.

Bartol, J.; Matenco, L.; Garcia-Castellanos, D.; Leever, K.

2012-04-01

395

3D Geophysical modelling of the Karoo Basin, South Africa, to investigate basin evolution  

NASA Astrophysics Data System (ADS)

The Karoo Basin in South Africa has recently been identified as a possible source for shale gas. The basin which was deposited in the Late Carboniferous (300 Ma) to Middle Jurassic (180 Ma) presently covers an area of 600 000 km2. However, no clear tectonic model exists for the Karoo Basin, though several have been proposed including a retroarc foreland basin and subsidence of basement blocks combined with mantle flow. This study attempts to constrain a model using isostasy and flexure studies. In this study we present the first broad-scale 3D model of the Karoo basin based on teleseismic, reflection and refraction seismic, MT, borehole and potential field data, including satellite gravity data. The basin is shallowest in the northeast where it is underlain by the strong Archean Kaapvaal craton, and deepens over the weaker Proterozoic Namaqua-Natal mobile belt which surrounds the craton to the south and west. The basin is deepest just north of the Cape fold belt which stretches along the southern and southwestern coast of South Africa. We also present preliminary backstripping results from proximal and distal regions of the basin which reveal the extent of tectonic subsidence. The importance of including Cape syn- and post-rift sediments (~ 483 to 330 Ma) in the south in the analysis is highlighted. This allows for a complete understanding of the crustal strength at the time of Karoo deposition. Investigation of flexure profiles across the basin, from on to off-craton, show the effect of varying crustal strength during cycles of Cape orogenic loading (between 292 and 215 Ma).

Scheiber-Enslin, Stephanie; Ebbing, Jörg; Webb, Susan

2014-05-01

396

Extent and architecture of major fault systems between northern Victoria Land and the eastern margin of the Wilkes Subglacial Basin (East Antarctica)  

NASA Astrophysics Data System (ADS)

Terrane bounding and intra-terrane faults of the Ross Orogen in East Antarctica are linked to several phases of Cambrian to Ordovician age subduction and accretion along the active paleo-Pacific margin of Gondwana. Here we compile and analyse new enhanced aeromagnetic anomaly images over the Northern Victoria Land (NVL) segment of the Ross Orogen and the eastern margin of the Wilkes Subglacial Basin (WSB) that help constrain the extent and structural architecture of these fault systems and enable us re-assess their tectonic evolution. Long-wavelength magnetic lows and residual Bouguer gravity highs are modelled as several-km thick inverted sedimentary basins of early Cambrian(?) age. Tectonic inversion occurred along major thrust faults during the late stages of the Ross Orogen, forming a major high-grade pop-up structure within the central Wilson Terrane, flanked by lower grade rocks. The Prince Albert Fault System can now be recongnised as being located to the west of the Exiles Thrust fault system rather than representing its southern continuation. Relatively thin sheets of mylonitic sheared granitoids and possible ultramafic lenses are associated with the late-Ross (ca 480 Ma) Exiles Thrust fault system, while significantly larger and thicker batholiths were emplaced along the Prince Albert Fault System. Recent zircon U-Pb dating over small exposures of gabbro-diorites within the Prince Albert Mountains to the south lead us to propose that this part of the magmatic arc was emplaced during an earlier phase of subduction (~520 Ma or older?), compared to the late-Ross intrusions to the east. Whether the Prince Albert Fault System was indeed a major cryptic suture in early Cambrian times (Ferraccioli et al., 2002, GRL) remains speculative, but possible. Our aeromagnetic interpretation leads us to conclude that these inherited terrane bounding and intra-terrane fault systems of the Ross Orogen exerted a key influence on Cenozoic tectonic blocks and faults of the Transantarctic Mountains, and that the eastern margin of the WSB adjacent to NVL was also strongly controlled by a complex array of major intraplate strike-slip fault systems.

Armadillo, E.; Ferraccioli, F.; Balbi, P.; Bozzo, E.

2013-12-01