Note: This page contains sample records for the topic gondwana basin orissa from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Optimal crop planning and water resources allocation in a coastal groundwater basin, Orissa, India  

Microsoft Academic Search

Intensive rice cultivation in a coastal groundwater basin in Balasore district of Orissa province (eastern India) during monsoon and winter seasons has resulted in extensive pumping of groundwater by a network of shallow, mini-deep and deep tubewells. Particularly, shallow tubewell owners using centrifugal pumps are unable to lift groundwater during winter seasons due to rapid drawdown of groundwater table below

Laxmi Narayan Sethi; Sudhindra N. Panda; Manoj K. Nayak

2006-01-01

2

Subduction, megashear systems and Late Palaeozoic basin development in the African segment of Gondwana  

Microsoft Academic Search

Basins within the African sector of Gondwana contain a Late Palaeozoic to Early Mesozoic Gondwana sequence unconformably overlying Precambrian basement in the interior and mid-Palaeozoic strata along the palaeo-Pacific margin. Small sea-board Pacific basins form an exception in having a Carboniferous to Early Permian fill overlying Devonian metasediments and intrusives. The Late Palaeozoic geographic and tectonic changes in the region

Johan N. J. Visser; Hermann E. Praekelt

1996-01-01

3

Provenance of Gondwana sandstones of the Parana basin, Brazil  

SciTech Connect

Gondwana sedimentation in the Parana basin was initiated as a result of epeirogenic uplift of the Brazilian craton during Upper Carboniferous glaciation. Uninterrupted sedimentation continued until the end of the Permian and resulted in deposition of three marine/marginal-marine/continental facies. A second episode of cratonic uplift in Triassic time was responsible for deposition of two additional continental facies. Based on mineralogical composition of the arenites, five petrofacies have been identified that correspond to five lithofacies. A cyclical compositional trend of the petrofacies, in chronological order from the base, have the following QFL values: 87:9:4 (petrofacies 1) in the glaciomarine facies {yields} 97:3:0 (Petrofacies 2) in the marginal marine Coal Measures {yields} 90:9:1 (Petrofacies 3) in the continental sandstone-red/green shale facies {yields} 76:23:1 (Petrofacies 4) in the fluvial sand {yields} and 93:7:0 (Petrofacies 5) in the eolian sand. Compositional maturity of Petrofacies 2 relative to Petrofacies 1 is attributed to the chemical decay of unstable grains in a humid climate that prevailed during coal formation. The relative immaturity and presence of fresh feldspars in Petrofacies 1 is presumably due to the presence of some granitic source rock and lack of chemical weathering in the glacial climate. Petrofacies 3 swings back to immaturity possibly due to the decline of the humid climate as indicated by the absence of coal and the beginning of a global arid trend. Petrofacies 4 represents the most immature unit of the entire succession and is related to aridity and another tectonic uplift of the craton that resulted in unroofing of some more granitic rock. Maturity of Petrofacies V relative to the underlying fluvial sand is possibly due to mechanical destruction of feldspars through eolian processes.

Dutta, P.K. (Indiana State Univ., Terre Haute (United States)); Santos, P.R. (Inst. de Geosciences, Sao Paulo (Brazil))

1991-03-01

4

Mesozoic history of the Fairway-Aotea Basin: Implications for the early stages of Gondwana fragmentation  

NASA Astrophysics Data System (ADS)

The Fairway Ridge is a buried continental structure that separates the Fairway Basin from the New Caledonia Basin. The proposed Cretaceous age of the Fairway Basin has remained highly hypothetical to date. Deep offshore petroleum exploration wells revealed well-dated Mesozoic carbonaceous sedimentary rocks in the Taranaki Basin at the southern end of the Aotea Basin. In this paper we use geophysical data to confirm the continuity of the 2000 km long Fairway-Aotea Basin connecting New Caledonia to New Zealand and prove its early Late Cretaceous age. Analysis of seismic reflection profiles together with newly compiled gravity and magnetic maps reveals Late Cretaceous NE-SW trending lineaments projecting northeastward from major Tasman Sea fracture zones and the Bellona Trough, which demonstrate that the opening of the Fairway-Aotea Basin predates the opening of the Tasman Sea. This result combined with observations of the Mesozoic regional geology suggests that the Lord Howe, Fairway, and Norfolk ridges are part of a remnant late Early Cretaceous continental arc, which was fragmented into three pieces by the late Early to early Late Cretaceous. This event might be contemporaneous with a plate motion change between the Gondwana and Pacific plates and/or the arrival of the Hikurangi plateau in the subduction zone around 105 Ma, which caused the cessation of subduction along this plate boundary. We interpret either of those two events as being possible trigger events for the post-Early Cretaceous fragmentation of the eastern Gondwana margin in a slab retreat process.

Collot, J.; Herzer, R.; Lafoy, Y.; GéLi, L.

2009-12-01

5

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

6

Ichnology of a Late Palaeozoic ice-marginal shallow marine succession: Talchir Formation, Satpura Gondwana basin, central India  

Microsoft Academic Search

The Late Palaeozoic, glaciomarine Talchir Formation in the Satpura Gondwana basin, central India hosts sparse to profuse trace fossils of various kinds, although sporadically. Among the three principal depositional systems that gave rise to the Talchir succession, deposits of the ice-contact fan delta system and the glacial outwash braidplain delta system lack trace fossils of any kind. On the other

Soumen Sarkar; Sanjoy Kumar Ghosh; Chandan Chakraborty

2009-01-01

7

Geochemistry and age of the Nouméa Basin lavas, New Caledonia: Evidence for Cretaceous subduction beneath the eastern Gondwana margin  

Microsoft Academic Search

The Nouméa Basin in New Caledonia is perhaps the best preserved sequence of in-situ Late Cretaceous marine sediments and volcanic rocks in the western Pacific region. Previous tectonic interpretations suggest that the basin formed during a period of large-scale extension between New Caledonia and Antarctica during the break-up of the eastern Gondwana margin. However, new geochemical analyses have identified continental

K. N. Nicholson; P. Maurizot; P. M. Black; C. Picard; A. Simonetti; A. Stewart; A. Alexander

2011-01-01

8

The Raniganj Coal Basin: an example of an Indian Gondwana rift  

Microsoft Academic Search

Rifting occurred in peninsular India during Permian–Triassic Gondwana sedimentation. The rocks of the Paleozoic–Mesozoic Indian Gondwana Supergroup succeed the Mesoproterozoic Vindhyan sedimentary rocks and the Indian Precambrian shield unconformably, and are renowned for their coal resources. The rocks of the Gondwana Supergroup occur mainly in trough-like depressions arranged in a more or less en echelon fashion along distinct shear\\/fault zones,

S. C Ghosh

2002-01-01

9

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

10

The Early Palaeozoic Break-up of Northern Gondwana: Sedimentology, Physical Volcanology and Geochemistry of a Submarine Volcanic Complex in the Bavarian Facies Association, Saxothuringian Basin, Germany  

Microsoft Academic Search

Ordovician volcano-sedimentary successions of the Bavarian facies association in the Saxothuringian basin record the continental rift phase of the separation of the Saxothuringian Terrane from Gondwana. An 80 m succession from the Vogtendorf beds and Randschiefer Series (Arenig-Middle Ordovician), exposed along the northern margin of the Münchberg Gneiss Massif in northeast Bavaria, were subjected to a study of their sedimentology,

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

2003-01-01

11

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

12

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

Microsoft Academic Search

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

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

2003-01-01

13

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

14

The Chachil Limestone (Pliensbachian-earliest Toarcian) Neuquén Basin, Argentina: U-Pb age calibration and its significance on the Early Jurassic evolution of southwestern Gondwana  

NASA Astrophysics Data System (ADS)

New radiometric U-Pb ages obtained on zircon crystals from Early Jurassic ash layers found within beds of the Chachil Limestone at its type locality in the Chachil depocentre (southern Neuquén Basin) confirm a Pliensbachian age (186.0 ± 0.4 Ma). Additionally, two ash layers found in limestone beds in Chacay Melehue at the Cordillera del Viento depocentre (central Neuquén Basin) gave Early Pliensbachian (185.7 ± 0.4 Ma) and earliest Toarcian (182.3 ± 0.4 Ma) U-Pb zircon ages. Based on these new datings and regional geological observations, we propose that the limestones cropping out at Chacay Melehue are correlatable with the Chachil Limestone. Recent data by other authors from limestones at Serrucho creek in the upper Puesto Araya Formation (Valenciana depocentre, southern Mendoza) reveal ages of 182.16 ± 0.6 Ma. Based on these new evidences, we consider the Chachil Limestone an important Early Jurassic stratigraphic marker, representing an almost instantaneous widespread flooding episode in western Gondwana. The unit marks the initiation in the Neuquén Basin of the Cuyo Group, followed by widespread black shale deposition. Accordingly, these limestones can be regarded as the natural seal of the Late Triassic -earliest Jurassic Precuyano Cycle, which represents the infill of halfgrabens and/or grabens related to a strong extensional regime. Paleontological evidence supports that during Pliensbachian-earliest Toarcian times these limestones were deposited in western Gondwana in marine warm water environments.

Leanza, H. A.; Mazzini, A.; Corfu, F.; Llambías, E. J.; Svensen, H.; Planke, S.; Galland, O.

2013-03-01

15

Gondwana breakup via double-saloon-door rifting and seafloor spreading in a backarc basin during subduction rollback  

NASA Astrophysics Data System (ADS)

A model has been developed where two arc-parallel rifts propagate in opposite directions from an initial central location during backarc seafloor spreading and subduction rollback. The resultant geometry causes pairs of terranes to simultaneously rotate clockwise and counterclockwise like the motion of double-saloon-doors about their hinges. As movement proceeds and the two terranes rotate, a gap begins to extend between them, where a third rift initiates and propagates in the opposite direction to subduction rollback. Observations from the Oligocene to Recent Western Mediterranean, the Miocene to Recent Carpathians, the Miocene to Recent Aegean and the Oligocene to Recent Caribbean point to a two-stage process. Initially, pairs of terranes comprising a pre-existing retro-arc fold thrust belt and magmatic arc rotate about poles and accrete to adjacent continents. Terrane docking reduces the width of the subduction zone, leading to a second phase during which subduction to strike-slip transitions initiate. The clockwise rotated terrane is caught up in a dextral strike-slip zone, whereas the counterclockwise rotated terrane is entrained in a sinistral strike-slip fault system. The likely driving force is a pair of rotational torques caused by slab sinking and rollback of a curved subduction hingeline. By analogy with the above model, a revised five-stage Early Jurassic to Early Cretaceous Gondwana dispersal model is proposed in which three plates always separate about a single triple rift or triple junction in the Weddell Sea area. Seven features are considered diagnostic of double-saloon-door rifting and seafloor spreading:earliest movement involves clockwise and counterclockwise rotations of the Falkland Islands Block and the Ellsworth Whitmore Terrane respectively;terranes comprise areas of a pre-existing retro-arc fold thrust belt (the Permo-Triassic Gondwanide Orogeny) attached to an accretionary wedge/magmatic arc; the Falklands Islands Block is initially attached to Southern Patagonia/West Antarctic Peninsula, while the Ellsworth Whitmore Terrane is combined with the Thurston Island Block;paleogeographies demonstrate rifting and extension in a backarc environment relative to a Pacific margin subduction zone/accretionary wedge where simultaneous crustal shortening occurs;a ridge jump towards the subduction zone from east of the Falkland Islands to the Rocas Verdes Basin evinces subduction rollback;this ridge jump combined with backarc extension isolated an area of thicker continental crust — The Falkland Islands Block;well-documented EW oriented seafloor spreading anomalies in the Weddell Sea are perpendicular to the subduction zone and propagate in the opposite direction to rollback;the dextral strike-slip Gastre and sub-parallel faults form one boundary of the Gondwana subduction rollback, whereas the other boundary may be formed by inferred sinistral strike-slip motion between a combined Thurston Island/Ellsworth Whitmore Terrane and Marie Byrd Land/East Antarctica.

Martin, A. K.

2007-12-01

16

Sedimentary sequences and timing of a complex rift to stable passive margin transition during Gondwana Breakup - the Morondava Basin of western Madagascar  

NASA Astrophysics Data System (ADS)

The tectono-sedimentary interpretation of seismic sections and detailed microfacies and mesofacies analyses of Bajocian to Kimmeridgian sediments from outcrops in the southern Morondava Basin, their basinwide correlation, and their integration into modern basin concepts led to a temporally more precise and conceptionally more perspicuous model of the Gondwana rifting and breakup history. The breakup of Gondwana along the East-African/Antarctic Orogen was preceded by a complex polyphase rift activity from the Late Carboniferous to the Early Jurassic, while Karoo aged sediments were being deposited. At the end of these Karoo Rifts, the final crustal separation of East- and West-Gondwana commenced after the westward migration of the rift axis during the Toarcian/Aalenian (Clark and Ramanampisoa, 2002). The sedimentary successions of this Gondwana Breakup Rift can be ascribed to three depositional stages: (1) The prerift stage comprises basement and Karoo aged strata; (2) deposits of the synrift stage related to the Andafia Fm. filled the half graben structures above tilted blocks; (3) during the postrift stage a carbonate platform developed from the Bajocian on the stable passive margin above the breakup unconformity, namely the Sakaraha/Bemaraha Fms. Compared to the sediment succession architecture of different rifts, the particular synrift strata of the Andafia Fm. in the Morondava Basin are mainly marine. Characterized by the wide absence of volcanics, the nonvolcanic Atlantic-type margin is built up by temporally and spatially varying carbonate and clastic sequences. The filling of the passive margin basin was mainly controlled by third order sealevel fluctuations (Hardenbol et al., 1998). The Bemaraha/Sakaraha Fms. carbonate platform environment represents the response to the global Bajocian to Lower Bathonian sealevel high, whereas the clastic pulse of the Ankazoabo/Sakananvaka Fms. during the Upper Bathonian to Lower Callovian was initiated by a eustatic sealevel fall. Comparable sedimentary response in the northern parts of the Morondava Basin is documented by the Besabora Fm. A basinwide transgression during the Callovian introduced an open marine environment (Duvalia Fm.), until clastic pulses of perideltaic sandstones recorded a regressional cycle during the Lower Oxfordian. At the end of the Lower Oxfordian a quick eustatic sealevel rise re-established open marine conditions with a comparably thin succession of condensed carbonate beds (maximum flooding) throughout the Oxfordian. These beds are succeeded by distal open marine shales of Lower Kimmeridgian Age, which are finally cut by the Aptian transgression. Clark, D.N. and Ramanampisoa, L. 2002. Review of the Occurrence and Distribution of Potential Source Rocks in Madagascar. In: Tracts, Plays and Fairways Along the Tethyan Margin - Abstracts and Programme. Kingston University, unpaged. Kingston. Hardenbol, J., Thierry, J., Farley, M.B., Jacquin, T., De Graciansky, P.-C. and Vail, P.R. 1998. Jurassic Sequence Chronostratigraphy. In: Mesozoic and Cenozoic Sequence Stratigraphy of European Basins (Eds P.-C. De Graciansky, J. Hardenbol, T. Jacquin and P.R. Vail), 60. SEPM Spec. Publ.

Geiger, M.; Clark, D. N.

2003-04-01

17

Provenance, volcanic record, and tectonic setting of the Paleozoic Ventania Fold Belt and the Claromecó Foreland Basin: Implications on sedimentation and volcanism along the southwestern Gondwana margin  

NASA Astrophysics Data System (ADS)

This study focuses on the provenance, volcanic record, and tectonic setting of the Paleozoic Ventania System, a geologic province which comprises the Cambro-Devonian Ventania Fold Belt and the adjoining Permo-Carboniferous Claromecó Foreland Basin, located inboard the deformation front. The Ventania Fold Belt is formed of the Curamalal and Ventana groups, which are composed mainly of mature quartzites that were unconformably deposited on igneous and metamorphic basement. The Pillahuincó Group is exposed as part of the Claromecó Basin and it has lithological and structural features totally distinct from the lowermost groups. This group is composed of immature arkoses and subarkoses with intercalated tuff horizons, unconformably overlaying the quartzites and associated with glacial-marine deposits of the lower Late Carboniferous to Early Permian section. The petrography, as well as major and trace elements (including rare earth elements) support that the Ventania quartzites were derived from cratonic sources and deposited in a passive margin environment. For the Pillahuincó Group, we suggest a transition between rocks derived from and deposited in a passive margin environment to those with geochemical and petrographical signatures indicative of an active continental margin provenance. LA-MC-ICP-MS analysis performed on euhedral and prismatic zircon grains of the tuffs revealed an age of 284 ± 15 Ma. The geochemical fingerprints and geochronological data of the tuffs found in the Claromecó Basin support the presence of an active and widespread Lower Permian pyroclastic activity in southwestern Gondwana, which is interpreted as part of the Choiyoi Volcanic Province in Argentina and Chile.

Alessandretti, Luciano; Philipp, Ruy Paulo; Chemale, Farid; Brückmann, Matheus Philipe; Zvirtes, Gustavo; Matté, Vinícius; Ramos, Victor A.

2013-11-01

18

Global changes during Carboniferous Permian glaciation of Gondwana: Linking polar and equatorial climate evolution by geochemical proxies  

Microsoft Academic Search

The most prevalent Phanerozoic glaciation occurred during the Carboniferous Permian on the Southern Hemisphere Gondwana supercontinent. Sediments from the Pennsylvanian Dwyka Group deposited in the Karoo Basin of South Africa provide a complete record of glaciation and deglaciation phases. The direct correlation of glaciation events in southern Gondwana basins with the well-studied climate evolution of equatorial regions was previously hampered

K. Scheffler; S. Hoernes; L. Schwark

2003-01-01

19

The relations between Cadomian peri-Gondwana blocks and the interior of Gondwana  

NASA Astrophysics Data System (ADS)

The Variscan and Alpine orogenic edifices of Europe-Turkey contain many blocks that were located along the periphery of Gondwana in Late Neoproterozoic and Early Paleozoic times. In particular the Cadomian-type blocks were probably located next to the West and North Africa and Arabia (WNAA) part of Gondwana. Here the relations between them, and their implications for the plate tectonic setting and paleogeography, are examined. As the WNAA formed by assembly of many originally separate terranes 650-620 Ma ago or somewhat later, it was only then a continuous peripheral array of terranes could form along the margin of this part of Gondwana. In earlier periods these terranes were most likely not adjacent to the components of WNAA. To accrete to the WNAA, oceanic areas between them had to be eliminated. When positioned next to the WNAA, the peripheral terranes were delimited by a subduction zone, whereas the plate boundaries that separated the components of the WNAA were eliminated. In the Ediacaran WNAA was stabilized and considerably eroded in the aftermath of the Pan African orogeny, while in the peripheral domain igneous activity occurred in many places, and sedimentary basins formed. Then many areas were affected to various extents by the Cadomian orogenic phase. Since the Cambrian the WNAA became a stable platform, usually without any igneous activity, and was covered by an extensive veneer of mature silici-clastics. In contrast, in the Cambrian and Ordovician igneous activity occurred in the peripheral domain, while differential vertical motions and faulting created sedimentary basins and eroded highs. Most likely this activity was usually related to extension or transtension. During these periods the WNAA supplied abundant sediments to the peripheral domain. However, it appears that some sediments had sources located within the peripheral domain or along the junction of the two domains. Examination of the conditions that were required to allow the dispersal of the sediments provides important constrains on the paleogeography of the peripheral domain. Though the available information is still incomplete, an a wide zone along the junction between the WNAA and the peri-Gondwana domains is not exposed, examination of their relation can provided significant insights regarding the plate tectonic setting in which they developed. Moreover, the information regarding the nature and the dispersal of sediments over these domains provides important insights regarding their paleogeography and structure.

Garfunkel, Zvi

2013-04-01

20

Tribal remedies for snakebite from orissa.  

PubMed

This communication presents an account of usage of 13 species of plant in the treatment of Snakebite by the tribals of Orissa, Botanical name, family, local name and Sanskrit name, if available of the plants along with mode of administration and place collection of the claims are enumerated. PMID:22557560

Murthy, K S; Sharma, P C; Kishore, P

1986-10-01

21

Geodynamic evolution of the early Paleozoic Western Gondwana margin 14°–17°S reflected by the detritus of the Devonian and Ordovician basins of southern Peru and northern Bolivia  

Microsoft Academic Search

We present results of a combined study of in situ U–Pb and Lu–Hf analyses on detrital zircons of Ordovician to Devonian sandstone successions of the Eastern Cordillera of Peru and Bolivia, as well as of the Altiplano and Coastal Cordillera of Peru (14°–17°S). We use our data to constrain the provenance and tectonic evolution of this part of the Gondwana

C. R. Reimann; H. Bahlburg; E. Kooijman; J. Berndt; A. Gerdes; V. Carlotto; S. López

2010-01-01

22

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

23

Patterns of Gondwana plant colonisation anddiversification  

Microsoft Academic Search

Charting the broad patterns of vascular plant evolution for Gondwana againstthe major global environmental shifts and events is attempted here for the first time. This is based on the analysis of the major vascular plant-bearing formations of the southern continents (plus India) correlated against the standard geological time-scale. Australia, followed closely by South America, are shown to yield by far

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

1999-01-01

24

Unfolding an Orocline Restores Australian Siluro-Devonian Poles to the Gondwana APWP  

NASA Astrophysics Data System (ADS)

Palaeozoic apparent polar wander for Gondwana has long been a source of controversy because of the reliance on Silurian to Late Carboniferous poles from the potentially mobile Lachlan Orogen, part of the late Neoproterozoic to Palaeozoic Tasmanides of eastern Australia. Despite the introduction of new poles and a series of reviews that have eliminated less reliable data, poles from the Molong-Monaro terrane, the eastern part of the Lachlan Orogen assembled around the Ordovician Macquarie Arc, remain stubbornly incompatible with the cratonic Gondwana path prior to about 400 Ma. Amalgamation of a mobile Molong-Monaro terrane with Gondwana at that time has been suggested, but a truly allochthonous origin for the terrane is precluded by sedimentological links with the rest of the Tasmanides. Recognition in aeromagnetic imagery of a megafold, obscured by sediments of the overlying Murray Basin, has prompted a new model for the Silurian to Early Devonian in the Lachlan Orogen, which explains apparent duplication of terrane elements in Victoria. Clockwise oroclinal rotation of the Molong-Monaro terrane through about 90 degrees is a corollary of the tectonic model. Silurian to Early Devonian poles from the Molong-Monaro terrane define a small circle around the pole of rotation of the orocline, supporting the tectonic model. Restoring the rotation brings these poles into agreement with the Gondwana APWP, and leaves the Macquarie Arc parallel to suspected arc structures in the Thomson Orogen, another element of the Tasmanides. The same rotation applied to Ordovician poles from the Molong-Monaro terrane displaces these away from the Gondwana APWP, requiring a still earlier phase of anticlockwise rotation of the formerly-unified Macquarie and "Thomson" arcs. This earlier rotation may be linked to a mid-Ordovician change in subduction polarity of the Macquarie Arc.

Musgrave, R. J.; Cayley, R.

2011-12-01

25

Characterization of the Sukinda and Nausahi ultramafic complexes, Orissa, India by platinum-group element geochemistry  

USGS Publications Warehouse

Samples of 20 chromitite, 14 ultramafic and mafic rock, and 9 laterite and soil samples from the Precambrian Sukinda and Nausahi ultramafic complexes, Orissa, India were analyzed for platinum-group elements (PGE). The maximum concentrations are: palladium, 13 parts per billion (ppb); platinum, 120 ppb; rhodium, 21 ppb; iridium, 210 ppb; and ruthenium, 630 ppb. Comparison of chondrite-normalized ratios of PGE for the chromitite samples of lower Proterozoic to Archean age with similar data from Paleozoic and Mesozoic ophiolite complexes strongly implies that these complexes represent Precambrian analogs of ophiolite complexes. This finding is consistent with the geology and petrology of the Indian complexes and suggests that plate-tectonic and ocean basin developement models probably apply to some parts of Precambrian shield areas. ?? 1985.

Page, N. J.; Banerji, P. K.; Haffty, J.

1985-01-01

26

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

27

Principal players in utility restructuring: the case of Orissa  

Microsoft Academic Search

Research on reform and restructuring in the Electricity Supply Industry does not adequately focus on the process of actual implementation. Using the restructuring of Orissa State Electricity Board as a case study, this paper identifies the principal players and their roles during the restructuring of an electric utility. The key players in a utility restructuring exercise are the Government, top

Rajan A. Thillai

2003-01-01

28

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

29

The Mesozoic Continental Magmatism in Brazil: its Role in the Western Gondwana Evolution from Integrated Paleomagnetic and Geochemical Data  

NASA Astrophysics Data System (ADS)

Most of the Paleozoic era in the South American platform represents a period of tectonic quiescence during which large sedimentary basins evolved. Subsequently an intense magmatic activity took place preceding the disclosure of the Gondwana from Pangea, and later the disruption of the western Gondwana blocks (South America and Africa separation). In Brazil Early Jurassic (~220-180 Ma) tholeiitic basalts erupted mostly in the northern area (Amazonas and Parnaíba basins), whereas the Early Cretaceous (~140-120 Ma) is best represented by the huge magmatism of the Serra Geral Formation (Paraná basin, southeastern Brazil). An intense associated intrusive activity in the form of dykes and sills of both ages is widespread all over the country but tends to concentrate towards the continental margins. The integration of paleomagnetic and geochemical data on the Brazilian Mesozoic magmatism put some constraints on the timing, duration and the mantle sources involved in the generation of the magma products related to the different magmatic events.

Ernesto, M.; Marques, L. S.

2011-12-01

30

Gondwana Six: Structure, Tectonics, and Geophysics  

NASA Astrophysics Data System (ADS)

This volume contains many of the papers presented at the Sixth International Gondwana Symposium, held at the Institute of Polar Studies, The Ohio State University, Columbus, Ohio, August 19-23, 1985. The symposium was the first held outside the Gondwanaland continents; other symposia were held in Buenos Aires, Argentina, 1967; Cape Town and Johannesburg, South Africa, 1970; Canberra, Australia, 1973; Calcutta, India, 1977; and Wellington, New Zealand, 1980. The Columbus symposium attracted 150 scientist from 19 countries to five days of technical sessions, six field trips, commission and working group meetings, and workshops. Topics covered in the technical sessions were generally similar to those of earlier meetings and included reconstruction of Gondwanaland, vertebrate and invertebrate paleontology, biogeography, glacial geology, Gondwana stratigraphy, economic geology, and tectonics and sedimentation at plate margins. A notable difference was in geographic coverage. As might be expected at a meeting co-hosted by the Institute of Polar Studies and the Department of Geology and Minerology at The Ohio State University, the focus of the meeting was on Antarctica, with 45% of the 102 papers covering the Ross Sea sector, West Antarctica, and northern Victoria Land.

McKenzie, Garry D.

31

NGOs in health care in Orissa: a profile.  

PubMed

India's National Health Policy recognized non governmental organizations (NGOs) as potential partners in the delivery of health services in an integrated manner because of their experience, expertise, motivation, and innovative and personalized approach in solving health problems. There are about 4000 NGOs registered in the state of Orissa. About 300 NGOs are engaged in health activities: 10 hospitals, 50 dispensaries, 100 development-action groups, and 140 service youth clubs. The voluntary health effort in Orissa comprises: 1) specialized community health programs: decentralized, low-cost, community-based programs with the support of local village health workers for the prevention of disease and health education; 2) integrated development programs; 3) health care for special groups; e.g., orphanages and rehabilitation centers for the handicapped; 4) government NGOs that implement various government programs like family planning, immunization, and Integrated Child Development Service; 4) centralized health care programs that concentrate on treatment of diseases and include hospitals and clinics. The Orissa Voluntary Health Association (OVHA) is as federation of member NGOs working in health related fields with about 150 members, of which about 70 are active. It organizes training programs, seminars, symposia, and campaigns on health issues; acts as a liaison between members and the government; collects health-related information and produces circulars and newsletters; assists in planning, implementing, and evaluating programs; produces educational materials; translates and reproduces health massages; and conducts research on health problems. The greatest health impact will emanate from a safe water supply, female education, and health and nutrition education. The government needs to focus on immunization, oral rehydration, prevention of diarrheal diseases, micro nutrient supplementation in underserved rural/tribal areas and for marginalized, underprivileged groups. This is the most significant aspect of the community health drive being promoted by NGOs in Orissa. PMID:12318297

Ali, A

1993-06-01

32

An assessment of the olive ridley turtle ( Lepidochelys olivacea) nesting population in Orissa, India  

Microsoft Academic Search

Olive ridley mass nesting events or ‘arribadas’ have been documented in Orissa, India since 1974. However, since standardised techniques have not been used to census turtles, actual population trends remain unknown. Herein, we summarise information on nesting populations in Orissa, using data from multiple sources to arrive at consensus estimates and to derive trends. We conducted a quantitative estimate of

Kartik Shanker; Bivash Pandav; B. C. Choudhury

2004-01-01

33

Global changes during Carboniferous Permian glaciation of Gondwana: Linking polar and equatorial climate evolution by geochemical proxies  

NASA Astrophysics Data System (ADS)

The most prevalent Phanerozoic glaciation occurred during the Carboniferous Permian on the Southern Hemisphere Gondwana supercontinent. Sediments from the Pennsylvanian Dwyka Group deposited in the Karoo Basin of South Africa provide a complete record of glaciation and deglaciation phases. The direct correlation of glaciation events in southern Gondwana basins with the well-studied climate evolution of equatorial regions was previously hampered by lack of precise radiometric dating. As dating has now become available for the Karoo Basin, the Gondwana glaciation can be viewed in a global paleoclimatic framework with high temporal resolution. Element geochemical proxies (CIA [chemical index of alteration], Zr/Ti, Rb/K, V/Cr) record three confined shifts in climate and paleoenvironment of the Karoo Basin. These shifts were induced by changes in sea level, weathering rate, provenance, and redox conditions. Because of the low availability and diagenetic overprint of carbonates, ocean and atmosphere pCO2 variations had to be reconstructed from ?13Corg values of marine organic matter. The ?13Corg signatures are affected by variable proportions of marine versus terrestrially derived organic matter and its state of preservation. Organic geochemical investigations (TOC [total organic carbon], C/N, lipid biomarkers) indicate the organic matter in the central Karoo Basin was primarily of algal origin. In agreement with element proxies, the varying ?13Corg values mirror shifts in pCO2, rather than variations of organic-matter type. A covariation trend between carbon isotope signatures of equatorial carbonates and ?13Corg values from the Karoo Basin argues against local forcing factors and instead implies a global climate-control mechanism. The 5 7 m.y. duration of a complete glacial cycle is not in tune with any known orbital frequency. Processes such as changes in equator-pole temperature gradients or newly developing atmosphere-ocean circulation pathways can be regarded as controlling factors.

Scheffler, K.; Hoernes, S.; Schwark, L.

2003-07-01

34

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

NASA Astrophysics Data System (ADS)

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

Götz, Annette E.

2013-04-01

35

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

36

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

37

Evolutionary sequences and hydrocarbon potential of Kenya sedimentary basins  

Microsoft Academic Search

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

1991-01-01

38

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

NASA Astrophysics Data System (ADS)

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

Ramos, V. A.

2009-05-01

39

Oroclines in the Tasmanides of eastern Gondwana  

NASA Astrophysics Data System (ADS)

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

Musgrave, Robert

2013-04-01

40

CO 2 degassing and trapping during hydrothermal cycles related to Gondwana rifting in eastern Australia  

NASA Astrophysics Data System (ADS)

Intensive carbonate and clay mineral authigenesis took place throughout the Late Permian Bowen-Gunnedah-Sydney basin system in eastern Australia. We conducted isotopic and trace element analyses of carbonate and clay minerals from clastic sedimentary rocks of the Gunnedah Basin and the Denison Trough in the Bowen Basin. Rb-Sr isochron age data of the illitic clays are consistent with episodic hydrothermal fluid flow events that occurred in association with Gondwana rifting accompanied by alkaline magmatism at ˜85 Ma and ˜95 Ma. Stable isotope data of carbonate and clay minerals from the Gunnedah Basin are indicative of meteoric waters from a high-latitude environment as the main fluid source, whereas trace element, Sr and Nd isotope data highlight mixing of meteoric fluids with magmatic and/or crustal components, with a possible input from marine carbonates for some samples. Trace metals, oxygen and strontium isotopes of dawsonites from the Denison Trough are interpreted to have been mobilised by fluids that interacted with evolved clastic sedimentary and marine carbonate end members. According to the carbon isotope data, CO 2 for calcite and ankerite precipitation was sourced mainly from thermal degradation of organic matter and magmatism, whereas the CO 2 used for dawsonite formation is inferred to have been derived from magmatic and marine sources. In the low permeability environments (particularly in coal seams), the increasing accumulation and oversaturation of CO 2 particularly promote the precipitation of dawsonite.

Uysal, I. Tonguç; Golding, Suzanne D.; Bolhar, Robert; Zhao, Jian-Xin; Feng, Yue-Xing; Baublys, Kim A.; Greig, Alan

2011-10-01

41

Application of IRS-P4 OCM data to study the impact of cyclone on coastal environment of Orissa  

Microsoft Academic Search

ORISSA coast was affected by a severe cyclone , with a high wind speed of above 200 km\\/h on 29 October 1999. This was probably the cyclone of highest intensity recor - ded during the last century. The coastline of Orissa cover - ing districts Jagatsingh Pur, Kendrapara and Balasore was severely affected. The region most affected is the coastal

S. R. Nayak; R. K. Sarangi; A. S. Rajawat

42

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

43

Simulation Modeling for Efficient Groundwater Management in Balasore Coastal Basin, India  

Microsoft Academic Search

The Balasore coastal groundwater basin in Orissa, India is under a serious threat of overdraft and seawater intrusion. The\\u000a overexploitation resulted in abandoning many shallow tubewells in the basin. The main intent of this study is the development\\u000a of a 2-D groundwater flow and transport model of the basin using the Visual MODFLOW package for analyzing the aquifer response\\u000a to

R. Rejani; Madan K. Jha; S. N. Panda; R. Mull

2008-01-01

44

Gondwana evolution; its assembly at around 600MaÉvolution du Gondwana; son assemblage autour de 600 Ma.  

NASA Astrophysics Data System (ADS)

Gondwana was formed at about 600 Ma at the end of the Pan-African-Brasiliano orogeny. It resulted from the collision between three lithospheric mega-plates generated by the break-up of the Rodinia supercontinent, between 1?000 and 700 Ma. The two main collisional zones are roughly submeridional in orientation. The western one, in relation to Africa which at that time was upside down with Cape Horn pointing northwards, is outlined by the Mozambique mega-belt which delineated western and central Gondwana. The eastern one is defined by a string of belts extending from the Sahara to the Cape of Good Hope. This collisional zone divides central and southeastern Gondwana. Laurentia or North America which, attached to South America, also participated in the Gondwana assembly, drifted early, at about 550 Ma, from the newly amalgamated Gondwana. The very low values (0.704) of 87Sr/ 86Sr, measured in carbonates deposited at around 850 Ma, may signify fragmentation of Rodinia, whereas high values (0.709) at around 550 Ma correspond to deep erosion of mountain belts generated by the Pan-African-Brasiliano collisions. ?13C is generally high and positive (+ 5 to + 9 ‰) in Neoproterozoic carbonates, reflecting intensive biological productivity and accumulation of large volumes of organic carbon on oceanic floor. A few abrupt excursions towards negative low values (-5 ‰) are associated with glacial episodes. They are either associated with rapid overturn of deep oceanic circulation or with a snowball Earth model in which a worldwide ice cover induces the slowing down, and even the stopping, of all biological activities.

Trompette, Roland

2000-03-01

45

The palaeomagnetism of the Tumblagooda Sandstone, Western Australia: Gondwana palaeozoic apparent polar wandering  

NASA Astrophysics Data System (ADS)

A magnetic polarity reversal near the top of the Tumblagooda Sandstone, in the Carnarvon Basin, Western Australia, has been intensively investigated in five coastal sections and four inland sections, all located near the top of the formation. A further four inland sections towards the base of the formation were also sampled. Of the inland sections, all but two are suspected to have been largely remagnetized in similar fashion to Late Palaeozoic and Mesozoic sediments to the south. At the remaining seven sections a zone of normal magnetization overlies a zone of mixed (coexisting normal and reversed) magnetization, and the boundary between them coincides with a unique marker horizon of pebbly sandstone. The intimate relationship of the (virtual) reversal and the pebble marker horizon lends strong support to the suggestion that erosional stripping accompanied the formation of the pebble marker. The pebble marker is best interpreted as a lag deposit. The stratigraphic coincidence does not necessarily signify the concurrence of a reversal with the formation of the marker horizon, but rather that the relationship represents a variation on the unconformity test. The record of the actual geomagnetic reversal has been physically removed from most sections. These results show conclusively that the age of the magnetization of the Tumblagooda Sandstone is very close to the age of deposition, and can therefore provide an important pole for the definition of the Gondwana apparent polar wander path. However, the suggested Silurian age must be questioned on the basis of the palaeomagnetism which best accords with an Ordovician age. The lower parts of the sequence may be as old as the Cambrian. While the age of the palaeomagnetic pole from the Tumblagooda Sandstone is therefore not well constrained, its position is well defined and in combination with other Gondwana poles indicates a period of rapid polar motion during the Ordovician/Silurian. A collision with Laurasia at the end of the Silurian and beginning of the Devonian may explain the timing of the Caledonian/Acadian Orogenies.

Schmidt, P. W.; Embleton, B. J. J.

1990-12-01

46

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

NASA Astrophysics Data System (ADS)

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 of Eastern Gondwana during the Jurassic and Cretaceous. Although in Jurassic times the onset of transgressions and regressions in both areas compares well with eustatic development, major deviations in combination with the tectonic activities of different degrees are observed in the Early and Late Cretaceous synchronously in both regions. Transgressions are observed in Toarcian, Bajocian (not dated in northern Somalia), Callovian, Valanginian (Madagascar only), Aptian and Campanian times. Tectonism is noted before the Aptian and Campanian transgressions in northern Somalia and the Morondava Basin of south-western Madagascar.

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

1994-12-01

47

Chronology of deformation within the turbidite-dominated, Lachlan orogen: Implications for the tectonic evolution of eastern Australia and Gondwana  

NASA Astrophysics Data System (ADS)

Ar-Ar data from fabric-forming white mica in slates, syntectonic quartz veins and granitic mylonites constrain the timing of metamorphism, deformation, and exhumation in the Lachlan orogen, Australia. These data also help define the tectonic evolution of the Tasmanides during Paleozoic time. The Lachlan orogen formed by the progressive accretion of a thick turbidite fan sequence and volcanic terrains to Gondwana during the closing of a small marginal ocean or back arc basin. This tectonic setting was similar to the present western and southwestern Pacific region. Accretion of the Lachlan orogen to Gondwana occurred by closing of the basin system by subduction-accretion processes and some translation. The process is typified in the western Lachlan orogen by a major eastward migrating deformation involving chevron folding and faulting over an eastward propagating decollement/melange zone and is recorded by Ar-Ar mica ages ranging from ˜455 Ma in the western part to ˜390 Ma in the eastern part. In the central Lachlan orogen, deformation migrated southwestward from ˜440-430 to 405 Ma away from the high-temperature Wagga-Omeo metamorphic complex, where deformation/metamorphism occurred between >440 and 400 Ma. In the north, ˜400 Ma mica ages record deformation and inversion of structures in the Cobar basin. In the eastern Lachlan orogen, Ar-Ar mica dates range from 450 to 340 Ma. Ages of 455-445 Ma are yielded by the Narooma accretionary complex, 405-390 Ma ages are found along the major thrust faults bounding high-grade metamorphic complexes, and 360-340 Ma cooling ages are found in the inverted extensional basins (e.g., Hill End) and related structural zones. The Ar-Ar results also document periods of reactivation on early-formed structures during later deformation elsewhere in the orogen.

Foster, David A.; Gray, David R.; Bucher, Martin

1999-06-01

48

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

Microsoft Academic Search

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

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

1999-01-01

49

Contingent valuation in project planning and evaluation: the case of social forestry in Orissa, India  

Microsoft Academic Search

There have been few applications of the contingent valuation method (CVM) to forests in developing countries. When applied, the method is seldom utilized to improve the implementation of development projects. In this paper an application of CVM to the Orissa Social Forestry Project is reported. The results show considerable variation between villages and the analysis of the bid function shows

GUNNAR KÖHLIN

2001-01-01

50

Learning from self-initiated community forest management in Orissa, India  

Microsoft Academic Search

There is growing recognition in tropical countries that safeguarding forests requires the active involvement of local communities, but knowledge of how best to do this is limited. Orissa's extensive experience of community forest management (CFM) provides some valuable lessons and insights regarding: (a) how and why communities manage their forests; and (b) the sustainability of CFM initiatives. The paper discusses

Czech Conroy; Abha Mishra; Ajay Rai

2002-01-01

51

Female headship, poverty and child welfare: A study of rural orissa, India  

Microsoft Academic Search

First, on the basis of primary data collected in a rural setting in the State of Orissa, an attempt has been made in this paper to compare the socioeconomic status of male- and female- headed households. Subsequently the differences in the use of resources (time and money) between male-headed and female-headed households have been analysed. Finally, the paper explores the

Pradeep Kumar Panda

1997-01-01

52

Theatre as Social Work in Orissa, India: Natya Chetana's Theatre for Awareness  

Microsoft Academic Search

Natya Chetana (Theatre for Awareness) is a theatre group based in the state of Orissa in Eastern India. Depicting and addressing local situations of structural violence, lack of social justice, and unmet basic needs in its plays, the group, as well as the local people that know the group, regard the group's theatre work also as social work. This is

Satu Ranta-Tyrkkö

2010-01-01

53

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

ERIC Educational Resources Information Center

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

Pradhan, Manas Ranjan; Ram, Usha

2010-01-01

54

PERFORMANCE OF BUILT ENVIRONMENT IN THE OCT 1999 ORISSA SUPER CYCLONE  

Microsoft Academic Search

The October 1999, Super Cyclone ransacked and devastated vast portions of the Indian State of Orissa, leaving behind a huge trail of death and destruction. Rated as one of the worst cyclones to hit the Indian coast ever, the super cyclone surpassed the tragedy of the 1977 Chirala cyclone, killing nearly 15,000 people and causing extensive damage to property, crops

Simon Francis; Prasad V S K Gunturi; Munish Arora

55

Livestock Production and the Rural Poor in Andhra Pradesh and Orissa States, India  

Microsoft Academic Search

This paper analyzes the political economy of the livestock sector in two Indian states, Andhra Pradesh and Orissa. The aim is to identify politically feasible interventions that could have broad positive effects on poor rural livestock producers in these states. To that end, the paper assesses the relationship between land, livestock, and poverty, describes the organization of the sector, and

Robin L. Turner

2004-01-01

56

An Upper Paleozoic bio-chronostratigraphic scheme for the western margin of Gondwana  

NASA Astrophysics Data System (ADS)

The Carboniferous and Permian fossiliferous sequences of the central-western Argentina contain abundant plant remains, palynomorphs and invertebrates. They include a continuous record of large distribution in the Paganzo, Rio Blanco, Calingasta-Uspallata and San Rafael Basins. The most recent biostratigraphic schemes recognize a floristic succession represented by the biozones: Archaeosigillaria-Frenguellia (AF Biozone), Frenguellia eximia-Nothorhacopteris kellaybelenensis-Cordaicarpus cesarii (FNC Biozone), Nothorhacopteris-Botrychiopsis- Ginkgophyllum (NBG Biozone), Interval Biozone and Gangamopteris Biozone. The associated palynological record is represented by the biozones: Reticulatisporites magnidictyus-Verrucosisporites quasigobbetti (MQ Biozone), Raistrickia densa-Convolutispora muriornata (DM Biozone), Pakhapites fusus-Vittatina subsaccata (FS Biozone), and Lueckisporites-Weylandites (LW Biozone). The precise age of the Upper Paleozoic western Gondwanan biozones has been under discussion and remains controversial to date in some regions. The main issue hampering an integrated comparison of the Gondwanan biozones was its imprecise chronostratigraphic framework. However, new studies in some Argentinian stratigraphic sections bearing floras and faunas have yielded several radiometric ages. From these 206Pb/ 238U zircon datings it is possible to determine the chronostratigraphic range of many fossiliferous assemblages in this sector of Gondwana. In this way, the AF and MQ Biozones are restricted to the Late Mississippian and they would be not younger than 335 Ma according to radiometric ages. 206Pb/ 238U ages suggest that the NBG, DMa and DMb Biozones characterize the Late Serpukhovian glacial deposits and persisted up to the Late Bashkirian. Beds containing the Interval and DMc Biozones have yielded 206Pb/ 238U ages of 312.82 ± 0.11 Ma and 310.71 ± 0.1 Ma which would indicate that both zones characterize the Moscovian. The remains of Gangamopteris Biozone found in the Paganzo Basin overlie basalt levels ranging between 308 ± 6 and 293 ± 6 Ma. Therefore, the incoming of the first glossopterids was closely associated to the Carboniferous-Permian boundary in this part of Gondwana. The data presented in this paper are used for establishing comparisons with other Gondwanan biozones, constrained by absolute ages.

Césari, Silvia N.; Limarino, Carlos O.; Gulbranson, Erik L.

2011-05-01

57

Hydrogeochemical processes controlling the high fluoride concentration in groundwater: a case study at the Boden block area, Orissa, India  

Microsoft Academic Search

The present investigation reports the assessment of hydrochemical\\/geochemical processes controlling the concentration of fluoride\\u000a in groundwater of a village in India (Boden block, Orissa). Boden block is one of the severely affected fluoride-contaminated\\u000a areas in the state of Orissa (India). The sampling and subsequent analysis of water samples of the study area was carried\\u000a out following standard prescribed methods. The

R. K. Dey; S. K. Swain; Sulagna Mishra; Prachi Sharma; Tanushree Patnaik; V. K. Singh; B. N. Dehury; Usha Jha; R. K. Patel

58

Structural and depositional controls on the sedimentary fill of the Algoa Basin-South Africa, and its hydrocarbon potential  

Microsoft Academic Search

The Algoa Basin, located on the southeastern margin of South Africa, is a Mesozoic rift basin covering an offshore area of 4000 square kilometers. This half graben is bounded by Recife arch and Port Alfred arch, and its offshore portion is composed of two sub basins, the Port Elizabeth and Uitenhage Troughs, initiated during the breakup of Gondwana in the

Muatasam Hassan Al-Raisi

2000-01-01

59

Title: Geophysical definition of PARANAPANEMA Proterozoic Block and its importance for the Rodinia to Gondwana evolutionary theories  

NASA Astrophysics Data System (ADS)

For the last decade, only three cratonic blocks (Amazonian, S. Francisco and Rio de LaPlata) were attributed to the South America portion for the Rodinia reconstitution. The probability of existing other blocks has been ignored. Taking into account a large gravity survey, the premise of a considerable Paleoproterozoic fragment as part of the Paraná basin basement is highly probable. After removing the gravity contribution of its sedimentary load, the gravity pattern of the basin basement framework discriminates the boundaries of a high density block (Paranapanema) from other structures, most of which outcrop beyond the limits of the basin itself. The gravity high, bounded by deep gradients is clearly isolated from the other structures, among which the buried segments of Goiás Arch, Ribeira and Brasilia Belts, and Rio de LaPlata Craton, are easily identified through their outcropping portion. The Goiás Arch gravity signature merges with the topographically defined Paraguay Arch. Important faults as Jacutinga and Lancinha-Cubatäo (NE) and Torres-Posadas lineament (NW) are clearly identified through the geophysical signature; these structures define contacts among blocks at East and South of Paranapanema. The geophysical analysis also shows that any liaison between this block and Rio de LaPlata (south), or Luis Alves / Curitiba (east) Proterozoic blocks is improbable. Deep borehole data provided the lithology, thickness and area distribution of each volcano and sedimentary layer, as well as a geochronology age determination for a number of basement samples. Through a back stripping geophysical analysis, based on borehole data, the maximum attenuation distribution was identified for the two main extensional tectonic events that formed the Paraná basin, for a time interval that lasted from the Silurian to the Triassic. Results, based on a thermo-mechanical model, indicate that for both events the maximum attenuation sites are sub-parallel to the Brasiliano faults (NE), while the lineaments Torres-Posadas and Tietê (NW), better denoted for the second event, are parallel to the Early Cretaceous Ponta Grossa Arch. From geological observations, the Apiaí Belt, a continental Atlantic margin to the East, the Goiás Arch, an active margin to the northwest, and the Socorro-Guaxupé Orogen, an active margin with arch formation to the northeast of Paranapanema, assign great importance to this block for describing the western Gondwana evolution and assembly. Therefore, Paranapanema should be taken into account among the lithosphere segments derived from Rodinia, and later from Western Gondwana, after undergoing a series of orogenic events. Samples from deep boreholes prove the existence of a Paleoproterozoic basement buried by volcano-sedimentary Paleo to Mesoproerozoic layers as also been observed for the Amazonian and the S. Francisco craton. Moreover, geological and geochronology studies of the Ribeira Belt infrastructure identify an increase of Mesoproterozoic rocks towards the border of Paranapanema. Shear faults of Late-Brasiliano age developed significant transitional depressions forming the precursor rifts filled with Silurian to Triassic sediments. As for Paranapanema, analogous blocks may exist under the Parnaiba basin and other structures that were activated during the Brasiliano Cycle to form Gondwana. In this light, we consider that a revision is required in order to amend the present theories on the evolutionary process from Rodinia to Gondwana.

Mantovani, M.; de Brito Neves, B.; Quintas, M.; Shukowsky, W.

2003-04-01

60

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

61

Amalgamating eastern Gondwana: The evolution of the Circum-Indian Orogens  

Microsoft Academic Search

The Neoproterozoic global reorganisation that saw the demise of Rodinia and the amalgamation of Gondwana took place during an incredibly dynamic period of Earth evolution. To better understand the palaeogeography of these times, and hence help quantify the interrelations between tectonics and other Earth systems, we here integrate Neoproterozoic palaeomagnetic solutions from the various blocks that made up eastern Gondwana,

Alan S. Collins; Sergei A. Pisarevsky

2005-01-01

62

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

63

Use and variation of Pandanus tectorius Parkinson ( P. fascicularis Lam.) along the coastline of Orissa, India  

Microsoft Academic Search

Pandanus tectorius Parkinson (\\u000a P. fascicularis Lam.) of the family Pandanaceae constitutes one of the major bioresources of Ganjam coast, Orissa; used mainly in small scale\\u000a perfume industry for aromatic compound extracted from the male inflorescences. In order to establish genetic diversity, if\\u000a any related to perfume yield, samples of P. tectorius representing male populations from seven locations representing populations

Kamal K. Panda; Anath B. Das; Brahma B. Panda

2009-01-01

64

GENDER INEQUALITY IN HOUSEHOLD HEALTH EXPENDITURE: THE CASE OF URBAN ORISSA  

Microsoft Academic Search

Biologically determined sex and socially constructed gender have strong bearing on the household out-of-pocket health expenditure. In this connection, the present makes an modest attempt to study the gender inequalities in household health expenditure in urban Orissa. The study shows that there is a significant difference between male and female out-of-pocket health expenditure in urban area. But the female out-of-pocket

Rout Himanshu Sekhar

2006-01-01

65

Sedimentary history of the Tethyan margins of Eastern Gondwana during the Mesozoic  

NASA Astrophysics Data System (ADS)

A composite Mesozoic geological history for the Gondwana margins to the Eastern Tethys Ocean can be assembled from stratigraphic successions on the Australian and Himalayan margins and from drill sites of Ocean Drilling Program Legs 122 and 123. During the Triassic, this region drifted northwards, entering tropical paleolatitudes during the Late Triassic-Early Jurassic, then returned to mid-latitudes for the Middle Jurassic through Early Cretaceous. Shallow-water carbonates are restricted to the tropical-latitude interval; at other times, the margins are dominated by clastic deposition. Episodes of deltaic sandstone progradation over the shelves are caused by eustatic sealevel fluctuations, by wet climatic conditions within the source regions and by local tectonic activity. A major hiatus between Callovian shallow-water shelf deposits and Oxfordian deep-water sediments is an ubiquitous feature, which may be related to a widespread plate tectonic reorganization and the cascading effects of associated sealevel rise and elevated carbon dioxide levels. Off Northwest Australia, this Callovian/Oxfordian event also coincides with an episode of block faulting. Marginal sediments deposited during the Late Jurassic are mainly marine claystone containing abundant terrigenous organic matter. Shallow depths of carbonate compensation (CCD) during the Late Jurassic through Early Cretaceous prevented the preservation of carbonate over most of the Argo basin off Northwest Australia, and these deep-sea sediments consist mainly of condensed, oxygenated radiolarian-rich claystone. During the late Kimmeridgian-early Tithonian, a downward excursion in the CCD enabled limited preservation of some larger nannofossils and mollusc fragments within the pelagic deposits, a feature also recorded in coeval deposits in the Atlantic. Explosive volcanism accompanied the final stages of rifting between India and Australia during the late Berriasian and Valanginian, producing volcaniclastic debris washing into the deltas and widespread ash deposits. The late Barremian and Aptian sediments indicate a rise in the CCD, accompanied by warming of the region and an increased delivery of organic-rich claystone into the basins.

Ogg, James G.; Gradstein, Felix M.; Dumoulin, Julie A.; Sarti, Massimo; Bown, Paul

66

Himalayan ironstones, "superplumes," and the breakup of Gondwana  

NASA Astrophysics Data System (ADS)

Oolitic ironstones or glauco-phosphorites were deposited all along the northern India continental margin during major tectonically enhanced transgressions in Frasnian, Permian, Norian, Callovian, Early Cretaceous, and Paleocene time. These regional events of starvation and drowning were commonly associated with alkalic to tholeiitic magmatism and invariably coincided in time with multiple rifting events that punctuated the progressive disintegration of Gondwana. Deposition of major condensed horizons enriched in iron, silica, and phosphorus was fostered by global factors such as eustatic rise, warm "greenhouse" climates, sluggish circulation, increased fertility, and poor ventilation in the oceans. Such anomalous sedimentary conditions recurred synchronously during magnetic quiet zones, pointing to successive episodes of global fast spreading and accelerated terrestrial heat loss. Multiple "pulsations" of Earth are inferred to have triggered supercontinent breakup and widespread volcanism, thus altering the atmosphere and hydrosphere, and dramatically affecting sedimentary and biological systems.

Garzanti, Eduardo

1993-02-01

67

Petrology and geochemistry of the Salma dike, Raniganj coalfield (Lower Gondwana), eastern India: linkage with Rajmahal or Deccan volcanic activity?  

NASA Astrophysics Data System (ADS)

The Gondwana (Early Permian to Early Cretaceous) basins of eastern India have been intruded by ultramafic ultrapotassic (minette, lamproite and orangeite) and mafic (dolerite) rocks. The Salma dike is the most prominent among mafic intrusives in the Raniganj basin. This dike is tholeiitic in composition; MgO varies from 5.4 to 6.3% and the mg number from 54 to 59. In general, the major and trace element abundances are uniform both along and across the strike. There is geochemical and mineralogical evidence for fractional crystallization. The chondrite normalized REE pattern of the Salma dike (La/Ybn=3.5) is similar to that of Deccan dikes of the Son Narmada rift zone, western India. 87Sr/86Sr varies from 0.70552 to 0.70671 suggesting assimilation of crustal material. Some trace element abundances (e.g. Ti, Zr, Y) of the Salma dike are comparable to Group I Rajmahal basalts. The 40Ar 39Ar whole rock age of 65 Ma for the Salma dike is less than the ca. 114 Ma age for the Rajmahal basalt, but is similar to the generally accepted age for Deccan volcanic rocks. Despite geographical proximity with the Rajmahal basalt, the Salma dike is believed to be related to late phase of Deccan volcanic activity.

Paul, D. K.

2005-11-01

68

Frontier sedimentary basins of New Zealand region  

Microsoft Academic Search

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

1991-01-01

69

Trace-element study of manganese ores of the Barbil area, Keonjhar district Orissa, India  

NASA Astrophysics Data System (ADS)

An attempt has been made to study the distribution pattern and concentration trends of eight significant metallic trace elements in the manganese ores of a few opencast workings of Barbil, Keonjhar district, Orissa, India. Cu, Pb, Zn, Co, Ni, Sr, Mo, and V are the trace elements that were chemically determined from 60 samples of manganese ores collected from the study area. Since the mean concentrations of most of the trace elements concerned in the Barbil manganese ores are generally lower than those found in the manganese ores known to be volcanogenic origin, the manganese was probably derived from some nonvolcanogenic terrestrial rock source.

Ajmal, M.

1990-05-01

70

Influence of Soil Environment and Surface Vegetation on Soil Micro Flora in a Coastal Sandy Belt of Orissa, India  

Microsoft Academic Search

A total of 141 species belonging 64 genera of fungi were isolated from coastal sandy belt of Orissa. The most dominant genera were Aspergillus, Penicillium, Trichoderma and Fusarium spp. Higher fungal and bacterial population was encountered in soil B than in soil A. Surface layer possessed higher fungal population, more soil nutrients and less moisture. Fungal population was positively correlated

T. Panda; B. Panda; B. K. Prasad; N. Mishra

71

Operational feasibility of rapid diagnostic kits & blister packs use for malaria control in high transmission areas of Orissa & Chhattisgarh  

Microsoft Academic Search

Background & objectives: Early diagnosis and prompt treatment of cases with malaria are two important components of malaria control strategy. The independent assessment of the operational feasibility of rapid diagnostic kits and blister packs for malaria in some selected high transmission areas of Orissa and Chhattisgarh was done with the objectives to assess the knowledge and skills of the paramedical

A. M. Reetha; S. K. Sharma; P. K. Tyagi; Neena Valecha; B. N. Nagpal; A. P. Dash

72

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

ERIC Educational Resources Information Center

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

Ekstrand, Gudrun, Ed.

73

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

Microsoft Academic Search

BACKGROUND: We have examined genetic diversity at fifteen autosomal microsatellite loci in seven predominant populations of Orissa to decipher whether populations inhabiting the same geographic region can be differentiated on the basis of language or ancestry. The studied populations have diverse historical accounts of their origin, belong to two major ethnic groups and different linguistic families. Caucasoid caste populations are

Sanghamitra Sahoo; VK Kashyap

2005-01-01

74

A Comparison of Fuel wood consumption and Woody biomass accumulation in the tribal village ecosystem of Bolangir (Orissa)  

Microsoft Academic Search

A thorough study of fuel wood consumption and woody biomass accumulation in the tribal dominated village ecosystem of Bolangir district of Orissa was made to find out a relation between the two. The three village complex such as Chikalbahal, Kudasingha and Bhutyarbahal were taken in the study area where people of Gond, Kondha and Sabar tribe inhabit and their main

Sarada Prasad Mohapatra

2011-01-01

75

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

2011-08-18

76

The Triassic of the Thakkhola (Nepal). II: Paleolatitudes and comparison with other Eastern Tethyan Margins of Gondwana  

Microsoft Academic Search

During the Triassic, the Thakkhola region of the Nepal Himalaya was part of the broad continental shelf of Gondwana facing a wide Eastern Tethys ocean. This margin was continuous from Arabia to Northwest Australia and spanned tropical and temperate latitudes.A compilation of Permian, Triassic and early Jurassic paleomagnetic data from the reconstructed Gondwana blocks indicates that the margin was progressively

J. G. Ogg; U. von Rad

1994-01-01

77

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

Microsoft Academic Search

The North West Shelf of Australia has been a long term passive margin, which underwent a polyphased tectonic history associated with the disintegration of Eastern Gondwana. Several Phanerozoic sedimentary basins like the Northern Carnarvon Basin developed during the rifting phases culminating in the opening of the NeoTethys during the Late Paleozoic and the abyssal plains during the Mesozoic. In order

L. Langhi; G. D. Borel

2003-01-01

78

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

79

Some remarks on the evolution of sedimentary basins along the eastern Brazilian continental margin  

Microsoft Academic Search

This work provides a general overview of the tectono-stratigraphic evolution of the Eastern Brazilian Margin, discussing the main phases of subsidence and sedimentation and in particular, the structural styles and depositional megasequences of selected basins. The Mesozoic sedimentation along the Brazilian continental margin started with the breakup of Western Gondwana in the Late Juras- sic\\/Early Cretaceous. The rifting of the

César Cainelli; Webster U. Mohriak

80

An Outbreak of Cholera Associated with an Unprotected Well in Parbatia, Orissa, Eastern India  

PubMed Central

In November 2003, an outbreak (41 cases; attack rate–4.3%; no deaths) of severe diarrhoea was reported from a village in Orissa, eastern India. Thirteen of these cases were hospitalized. A matched case-control study was conducted to identify the possible exposure variables. Since all wells were heavily chlorinated immediately after the outbreak, water samples were not tested. The cases were managed symptomatically. Descriptive epidemiology suggested clustering of cases around one public well. Vibrio cholerae El Tor O1, serotype Ogawa was isolated from four of six rectal swabs. The water from the public well was associated with the outbreak (matched odds ratio: 12; 95% confidence interval 1.2–44.1). On the basis of these conclusions, access to the well was barred immediately, and it was protected. This investigation highlighted the broader use of field epidemiology methods to implement public-health actions guided by epidemiologic data to control a cholera epidemic.

Das, Amitav; Hutin, Yvan; Pal, B.B.; Chhotray, G.P.; Kar, S.K.; Gupte, M.D.

2009-01-01

81

Determinants of breast-feeding and post-partum amenorrhoea in Orissa.  

PubMed

A life table analysis is made of the duration of breast-feeding and post-partum amenorrhoea in Orissa, India, taking one variable at a time using data from a baseline survey of fertility and mortality (BSFM) conducted on the lines of the World Fertility Survey. Then a multivariate (proportional hazard) analysis showed that socioeconomic factors including residence, caste status and education influence the breast-feeding and post-partum amenorrhoea periods. There was no effect of maternal age on the length of breast-feeding, but mean length of post-partum amenorrhoea varied with age. The durations of breast-feeding and post-partum amenorrhoea are strongly related. PMID:2768294

Srinivasan, K; Pathak, K B; Pandey, A

1989-07-01

82

Improving maternal health through social accountability: a case study from Orissa, India.  

PubMed

As maternal health specialists accelerate efforts towards Millennium Development Goal Five, attention is focusing on how to best improve service accountability to target communities as a strategy for more effective policy implementation. We present a case study of efforts to improve accountability in Orissa, India, focusing on the role of local women, intermediary groups, health providers and elected politicians. We highlight three drivers of success: (1) the generation of demand for rights and better services, (2) the leverage of intermediaries to legitimise the demands of poor and marginalised women and (3) the sensitisation of leaders and health providers to women's needs. We use the concepts of critical consciousness, social capital and 'receptive social spaces' to outline a social-psychological account of the pathways between accountability and service effectiveness. PMID:23230827

Papp, Susan A; Gogoi, Aparajita; Campbell, Catherine

2012-12-12

83

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

84

The Karoo basins of south-central Africa  

NASA Astrophysics Data System (ADS)

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 a retroarc foreland system known as the “main Karoo” Basin, with the primary subsidence mechanisms represented by flexural and dynamic loading. This basin preserves the reference stratigraphy of the Late Carboniferous Middle Jurassic Karoo time, which includes the Dwyka, Ecca, Beaufort and Stormberg lithostratigraphic units. North of the main Karoo Basin, the tectonic regimes were dominated by extensional or transtensional stresses that propagated southwards into the supercontinent from the divergent Tethyan margin of Gondwana. Superimposed on the tectonic control on basin development, climatic fluctuations also left a mark on the stratigraphic record, providing a common thread that links the sedimentary fill of the Karoo basins formed under different tectonic regimes. As a general trend, the climate changed from cold and semi-arid during the Late Carboniferous earliest Permian interval, to warmer and eventually hot with fluctuating precipitation during the rest of Karoo time. Due to the shifts in tectonic and climatic conditions from the southern to the northern margins of Africa during the Karoo interval, the lithostratigraphic character of the Karoo Supergroup also changes significantly across the African continent. For this reason, the Karoo basins sensu stricto, which show clear similarities with the main Karoo Basin of South Africa, are generally restricted to south-central Africa, whereas the Karoo-age successions preserved to the north of the equator are distinctly different. This paper focuses on the Karoo basins sensu stricto of south-central Africa, synthesizing their sedimentological and stratigraphic features in relation to the tectonic and climatic controls on accommodation and sedimentation.

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

2005-10-01

85

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

86

A Mesozoic crustal suture on the Gondwana margin in the New Zealand region  

Microsoft Academic Search

Marine crustal multichannel seismic data, recorded offshore South Island, New Zealand, are used to provide constraints on the evolution of the Gondwana margin in this region. Lower crustal and upper mantle seismic reflectivity off southeastern Stewart Island, south of South Island, is interpreted in terms of a northeast dipping paleosubduction zone. This inferred suture is considered to be related to

F. J. Davey

2005-01-01

87

Fossil evidence in Australia for oldest known freshwater crayfish of Gondwana  

Microsoft Academic Search

Early Cretaceous body and trace fossils in Victoria, Australia, establish the oldest known presence of parastacid crayfish (Decapoda: Astacidea, Parastacoidea) in freshwater environments of Australia, and the oldest known crayfish in Gondwana. Parastacid body fossils, comprised of a partial abdomen (Palaeoechinastacus australianus, gen. et sp. nov.) and two chelae, are from a fluvial deposit in the Otway Group (Albian). Trace

Anthony J. Martin; Thomas H. Rich; Gary C. B. Poore; Mark B. Schultz; Christopher M. Austin; Lesley Kool; Patricia Vickers-Rich

2008-01-01

88

Early to Middle Toarcian (Jurassic) palaeoenvironmental perturbations and their repercussions on the Northern Gondwana margin carbonate platform (High Atlas, Morocco)  

NASA Astrophysics Data System (ADS)

The Early Toarcian is marked by a global perturbation of the carbon cycle and major marine biological changes, which coincide with a general decrease of calcium carbonate production and an increase of organic carbon burial, culminating in the so-called Toarcian Oceanic Anoxic Event. It is believed that the environmental crisis was triggered by the activity of the Karoo-Ferrar large igneous province. In order to further document the Early Toarcian palaeoenvironmental perturbations, we have investigated carbon isotope, total organic matter, calcareous nannofossils and phosphorus content of the Amellago section in the High Atlas rift basin of Morocco. This section offers the advantage to be extremely expanded compared to the well-studied European sections. Its position along the northern margin of the Gondwana continent is of critical importance to assess the change of continental river nutrient input into the western Tethyan realm. The carbon isotope curve shows two negative excursions of equal thickness and amplitude, at the Pliensbachian - Toarcian boundary and the Polymorphum - Levisoni ammonite Zone transition. This confirms the supra-regional nature of these shifts and highlights the possible condensation of the first "boundary" shift in European sections. Phosphorus content is used to trace palaeonutrient changes and shows that the two negative carbon isotope shifts are associated with increased nutrient level, confirming that these episodes are related to enhanced continental weathering, probably due to elevated greenhouse gases in the atmosphere. In the High Atlas Basin, the rise of nutrient level at the Pliensbachian - Toarcian boundary is moreover likely to be the main factor responsible for the coeval demise of the carbonate platform. Nutrient levels are thereafter decreasing during the Late Early Toarcian, permitting the reinstallation of carbonate platform growth. A Middle Toarcian event, centered on the Bifrons - Gradata Zones transition, characterized by a positive excursion of carbon isotope and nutrient level rise, is moreover documented in the Amellago section, and most likely accompanied by a second carbonate platform drowning event.

Bodin, Stephane; Mattioli, Emanuela; Fröhlich, Sebastian; Marshall, Jim; Boutib, Lahcen; Lahsini, Salim; Redfern, Jonathan

2010-05-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

90

Isotopic constraints on the deep crustal structure of Gondwana: case studies from Yemen and Saudi Arabia  

Microsoft Academic Search

The late Precambrian assembly of east and west Gondwana created a tectonic collage of oceanic arcs and micro-continental fragments over most of the exposed Arabian Shield. Sutures within this collage may be identified by ophiolitic remnants or elsewhere inferred by lithological packages such as characteristic arc volcanics. However, the significance of individual sutures, for example as intra-oceanic or oceanic-continental boundaries

M. Whitehouse

2003-01-01

91

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.

2013-01-01

92

A Cambrian Arc Built on the Neoproterozoic Rifted Margin of Gondwana  

NASA Astrophysics Data System (ADS)

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

Musgrave, R. J.

2009-12-01

93

A Fatal Waterborne Outbreak of Pesticide Poisoning Caused by Damaged Pipelines, Sindhikela, Bolangir, Orissa, India, 2008  

PubMed Central

Introduction. We investigated a cluster of pesticide poisoning in Orissa. Methods. We searched the village for cases of vomiting and sweating on 2 February 2008. We described the outbreak by time, place, and person. We compared cases with controls. Results. We identified 65 cases (two deaths; attack rate: 12 per 1000; case fatality: 3%). The epidemic curve suggested a point source outbreak, and cases clustered close to a roadside eatery. Consumption of water from a specific source (odds ratio [OR]: 35, confidence interval [CI]: 13–93) and eating in the eatery (OR: 2.3, CI: 1.1–4.7) was associated with illness. On 31 January 2008, villagers had used pesticides to kill street dogs and had discarded leftovers in the drains. Damaged pipelines located beneath and supplying water may have aspirated the pesticide during the nocturnal negative pressure phase and rinsed it off the next morning in the water supply. Conclusions. Innapropriate use of pesticides contaminated the water supply and caused this outbreak. Education programs and regulations need to be combined to ensure a safer use of pesticides in India.

Panda, Manjubala; Hutin, Yvan J.; Ramachandran, Vidya; Murhekar, Manoj

2009-01-01

94

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

SciTech Connect

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

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

1988-11-01

95

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

96

Malaria outbreak in a non endemic tribal block of Balasore district, Orissa, India during summer season.  

PubMed

A focal outbreak of malaria at Sialimal sub-centre of Balasore district of Orissa was reported during the month of March, 2010. Three villages of the above block were affected. Regional Medical Research Centre, Bhubaneswar has conducted an entomological survey and a central clinic simultaneously, with door to door household survey to identify the fever cases. Within a span of 18 days around 172 fever cases were reported with Slide Positivity Rate (SPR) of 24.4% and Pf % of 81%. The malaria epidemiological data of the sub-centre area for last three years indicates that the area is non endemic for malaria (API was 0.81). Entomological survey revealed the presence of three known vectors of malaria i.e. Anopheles culicifacies, Anopheles annularis and Anopheles subpictus (local vector). Per Man Hour Density (PMHD) of these three species were 4.2, 2.8 and 10.8 respectively. Plasmodium falciparum sporozoites were detected in two An. culicifacies, in one An. annularis and in one An. subpictus. Larval density of Anopheline mosquitoes per dip ranged between 12 to 20. The vectors were found to be resistant to DDT but susceptible to synthetic pyrethroid. With this finding necessary remedial measures were taken by the government to curtail the transmission. PMID:22735850

Mahapatra, N; Marai, N; Dhal, K; Nayak, R N; Panigrahi, B K; Mallick, G; Ranjit, M; Kar, S K; Kerketta, A S

2012-06-01

97

Disaster management for Nandira watershed district Angul (Orissa) India, using temporal Remote Sensing data and GIS.  

PubMed

NALCO--the largest exporter of aluminium in India has a power plant of 720 MW capacity in Nandira watershed in Angul district of Orissa. The power plant utilises local coal to generate thermal power and disposes of large amount of ash which accumulates in slurry form at nearby two ash ponds. These ash ponds were breached on 31 December 2000, causing ash accumulation for entire regime of the Nandira river. An attempt has been made towards preparation of recovery and rehabilitation plan for NALCO using temporal Remote Sensing data and GIS. Indian remote sensing satellite data for pre-breach condition 12 December 2000, during breach event 31 December 2000 and post-breach condition 4 and 6 January 2001 has been digitally analysed for Nandira watershed. The satellite data of coarse spatial resolution provides the absence and presence of fresh sediment deposition along Nandira watershed and Brahmani river pertaining to pre-breach and post-breach conditions respectively on regional scales. The temporal comparison of fine resolution has clearly highlighted the aerial extent of damage caused by the disaster for entire watershed on local scales. The GIS has helped in demarcation of freshly accumulated ash at interval of 500 m along the river length as well as in delineation of maximum ash accumulation across the river width. The study has clearly demonstrated the use of temporal Remote Sensing data in conjunction with GIS for disaster management in terms of recovery and rehabilitation plan preparation of the Nandira watershed. PMID:15932001

Gupta, P K; Singh, A P

2005-05-01

98

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

99

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

100

Attitude of unmarried girls towards family planning: a study in an Orissa City.  

PubMed

In 1987-88, 281 females from the Government Women's College in Berhampur, Ganfam District, Orissa State in India were surveyed to determine their knowledge and attitude toward family planning (FP). 80% came from urban areas. Educated fathers (72%) had considerable influence over the education of their daughters (p.001). Higher income families (70%) were more able to educate their children than lower income families (30%; p.001). 50% of the students had discussed FP and family ties with their parents. 91% recognized the need for FP. 95% did not favor early marriage (p.02). 66% knew the legal marriage age for females to be 18 years, but only 47% knew it to be 21 for males. In fact, 46% believed the age for males to be 25 years. 24% k new of only 1 FP method, 23% of 2 methods, and 14% of 3 methods. The leading method to be used after marriage according to the students was condoms (16%) followed by IUDs and oral contraceptives (OCs) (6%). The predominant method to use after childbirth was sterilization (13%) followed by IUDs (8%) and condoms and OCs (5%). Most students did not advocate using any method after marriage or after childbirth. 45% mentioned the best time to start FP was after 2 children and 26% after 1 child. Most, (83%) preferred 2 children (p.001) because of better child care and education (37%). 71% felt couples should wait 3 years before having another child. No one believed 1 or 4 years to be adequate birth spacing. Birth spacing was needed in the interest of the mother's health (30%) and for better health of the next child (29%). The mass media provided 50% of the students with FP knowledge. Most (70%) felt that insufficient FP education and basic education were the reasons for unplanned families. 82% believed the FP program would be successful in the future. 68% considered population control important to national development. PMID:1749726

Rout, S; Sahani, S; Sahu, G

1991-03-01

101

Shoreline and seabed level changes along the central Orissa coast, India  

NASA Astrophysics Data System (ADS)

Shoreline and the sea bed level change analysis have become very important at the vulnerable places of natural disasters and to estimate the impacts of coastal development. A coastal geomorphologic analysis using the recent techniques such as remote sensing, numerical modeling with measurements using RTK-GPS help to infer the extent of changes and its contributing forces. This study was carried out along the Orissa coast which lies in the east coast of India. Extent of seafloor changes occurred in the last 30 years using the historic and latest bathymetric data is fused with the inter-annual shoreline changes prepared from the latest remote sensing images. Changes in the shoreline position and development of spits were anlaysed for 14 years and results show the dynamic nature of the study region. The year-wise length of the Ekakula spit estimated from satellite data for the period 1999-2008 showed that the Ekakula spit length increased from 1999 by 2712 m up to 2008 towards northeast. Near shore bathymetry data of 1975, 2002 and 2010 has been collaboratively fused to detect the changes. The results confirm the marked changes in the seabed levels. It has been estimated that from the study area, only 3% of the ocean floor has not shown changes while 97% has been modified. The overview of physical forces responsible for these changes and the corresponding year's shoreline changes supports that this region is continuously evolving. The changes of these coasts and seabed are attributed to the natural and anthropogenic activities which are modifying the nearshore coastal geomorphology. This study highlights the areas that have changed with great precision. This kinds of study helps for calculating the net movement of sediments, pathways, volumetric estimates of sediment in general and also to quantify the temporal changes.

Mani Murali, R.; Vethamony, P.; Singh, A. K.

2012-04-01

102

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

ERIC Educational Resources Information Center

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

Svensson, Anna

103

On Redefining the Urban Informal Manufacturing Sector: A Study of Micro Businesses, Petty Producer Units and Small Capitalist Producer Firms in Sambalpur, Orissa  

Microsoft Academic Search

In this paper the author has tried to redefine the concept of the informal manufacturing sector (IMS) based on two surveys done in 1985 and 1994 in Sambalpur, Orissa. In the benchmark study (1985), size of the unit was used as the first-order condition for demarcating the informal sector, while all the other characteristics were taken as second-order conditions. In

Kishor C. Samal

1997-01-01

104

The impact of 1995--1996 health sector reforms in the effectiveness of malaria control program in the state of Orissa, India  

Microsoft Academic Search

Malaria poses a significant public health problem worldwide. The World Health Organization indicates that approximately 40% of the world's population and almost 85% of the population from the South–East Asian region is at risk of contracting malaria. India being the most populous country in the region, contributes the highest number of malaria cases and deaths attributed to malaria. Orissa is

Alakananda Mohanty

2008-01-01

105

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

Microsoft Academic Search

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

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

2008-01-01

106

Amalgamation and initial break-up of Gondwana along the East African - Antarctic Orogen  

NASA Astrophysics Data System (ADS)

East- and West-Gondwana, or parts thereof, amalgamated along the East African - Antarctic Orogen at c. 550 Ma. The initial Gondwana break-up roughly followed the length of the orogen and reactivated Pan-African suture and shear zones 350 Ma after amalgamation. In Antarctica, the collision of E- and W-Gondwana overprinted wide continental margins but the location of the principle suture zone(s) is a matter of ongoing debate. Both, the northern and southern part of the East African - Antarctic Orogen are characterised by tectonic escape. In the southern part of the orogen, escape tectonics was associated with large-scale shear zones, that were reactivated during the break-up, resulting in a number of microplates. In Antarctica, the western orogenic front of the orogen is well exposed as the Heimefront Shear Zone in western Dronning Maud Land. This shear zones was reactivated during Mesozoic rifting and separates strongly thinned crust to the W from little affected crust to the E. It also coincides with a deep graben that reaches 800 mbsl, totalling the present relief in Heimefrontjella to more than 3500 m. Apatite fission-track data from this area indicate that the main geomorphic evolution does not coincide with the initial break-up and the formation of a margin, but was contemporaneous with the opening of the South Atlantic. During initial rifting at c. 180 Ma, the area was affected by the Bouvet mantle plume, that caused reheating of the basement to T > 120°C, followed by erosional unroofing in the Cretaceous. In the central portion of the East African - Antarctic Orogen, the break-up followed structures in the eastern part of the orogen. In Madagascar, rifting and break-up followed again Pan-African shear zones, such as the Ejeda and Ranotsara shear zones. In contrast to western Dronning Maud Land, fission-track data from Madagascar indicate that some of the main geomorphic features formed early during the break-up history. For example, combined titanite and apatite fission-track analyses indicate that the Ranotsara valley is an old rift zone, that developed early in the Gondwana rift history and underwent only little geomorphic modification thereafter.

Jacobs, J.; Emmel, B.

2003-04-01

107

Silurian magmatism in eastern Senegal and its significance for the Paleozoic evolution of NW-Gondwana  

NASA Astrophysics Data System (ADS)

Submarine basalt and trachyte of the Nandoumba group occur in eastern Senegal within the Bassarides branch of the Mauritanides orogen. The unit forms part of the parautochthonous domain which is stacked between underlying Neoproterozoic to Paleozoic foreland and overlying Variscan nappes. The crystallisation age of the volcanic to subvolcanic rocks has been determined by U–Pb single zircon SHRIMP method at 428 ± 5.2 Ma whereas zircon xenocryst ages vary from 500 to 2200 Ma. The shape of the xenocryst grains document proximal Neo- and Paleoproterozoic and distal Mesoproterozoic provenance areas for assimilated sediments. This is compatible with the Paleoproterozoic Birimian basement and Neoproterozoic cover rocks nearby whereas an origin from the Amazonian craton could be assumed for distal Mesoproterozoic zircons.Geochemical and Sm–Nd isotope whole rock analysis show that basalts of the Nandoumba group are similar to modern transitional to alkaline volcanic lavas in intraplate settings. Those basalts have a deep mantle source with a great contribution of a recycled mantle component such as EM1 and/or EM2. The basalts resemble in their composition those from the Meguma terrane of Nova Scotia which are of similar age suggesting a common source and therefore connection of Meguma with Gondwana during this period. Review of circum-Atlantic Silurian magmatism indicates ongoing fragmentation of NW-Gondwana that started in Cambro/Ordovician times.

Fullgraf, Thomas; Ndiaye, Papa Moussa; Blein, Olivier; Buscail, François; Lahondère, Didier; Métour, Joël Le; Sergeev, Sergey; Tegyey, Monique

2013-02-01

108

40Ar/ 39Ar dating of the Jurassic volcanic province of Patagonia: migrating magmatism related to Gondwana break-up and subduction  

NASA Astrophysics Data System (ADS)

The Mesozoic large igneous province (LIP) of Patagonia (southern South America), which is one of the largest silicic provinces on Earth has been investigated by the 40Ar/ 39Ar method. Twenty-seven ages considered as valid, including twenty plateau ages, show that the volcanic activity, ranging from 187 to 144 Ma, occurred between and contemporaneously with the initial break-up of Gondwana (starting with the Karoo-Antarctic-Tasmanian (KAT) flood basalt province) in the east, and a subduction in the west. The data display a regular decreasing of ages from the ENE (187 Ma) to the WSW (144 Ma) along about 650 km, apparently related to the tectonic structure in half-grabens oriented NNW-SSE. The good fitting of this trend with the opening of the Rocas Verdes-Sarmiento marginal basin favors a space time evolution of this continental volcanism culminating towards the SSW in a continental disruption behind the magmatic arc. The observed age progression of volcanism may be the result of the variations of the physical characteristics of the subduction. The spreading and thermal effect of the KAT plume may have an additional effect and also could account for the unusually large volume of magma.

Féraud, G.; Alric, V.; Fornari, M.; Bertrand, H.; Haller, M.

1999-10-01

109

Ichnology of a Late Paleozoic (Permo-Carboniferous) Glaciomarine Deltaic Environment, Talchir Formation, Saharjuri Basin, India  

Microsoft Academic Search

The storm-influenced prodeltaic offshore succession of the Saharjuri Basin sits in a glaciomarine deltaic setting of the Permo-Carboniferous, Talchir Formation, Gondwana Supergroup, India. It offers the opportunity for study of relationships between sedimentation and ichnocoenoses in a glacial sequence. Sandstone\\/ siltstone-mudstone couplets deposited by storm ebb surges of varying energy levels contain distinct bioturbation patterns formed by suspension-feeders and sediment-eaters.

Abhijit Chakraborty; H N Bhattacharya

2005-01-01

110

ISOTOPIC COMPOSITION OF COALBED METHANE DESORBED FROM BARAKAR COALS OF DAMODAR VALLEY GONDWANA COALFIELDS AND ITS IMPLICATION  

Microsoft Academic Search

Stable Carbon Isotopic composition is long been used as a very important tool for finding out the genesis of natural gas. In this paper this tool is used to find out the genesis of CBM of Barakar Coals of Damodar Valley Gondwana Coalfields and its implication. The factors those control the Stable Carbon Isotopic composition of coalbed methane are: i)

Malay Rudra; P N Hajr

111

Cambrian palaeomagnetic data confirm a Natal Embayment location for the Ellsworth-Whitmore Mountains, Antarctica, in Gondwana reconstructions  

NASA Astrophysics Data System (ADS)

The Ellsworth-Whitmore Mountains (EWM) are one of five terranes that form West Antarctica. Constraining the positions of these terranes in pre-break up Gondwana is crucial to understanding the history of the palaeo-Pacific Gondwana margin. We report the results of a detailed palaeomagnetic investigation of the EWM, which comprises some 150 sites in six formations, ranging in age from Cambrian to Permian. Five of the studied units yield only viscous remnant magnetizations of recent age, or unstable natural remanent magnetizations. The remaining unit, the mid-late Cambrian Frazier Ridge Formation, yielded stable magnetizations at 16 of 35 sites. This component passes a fold test at the 95 per cent confidence level, indicating that it pre-dates Permian deformation, and we argue that it is of primary origin. The resulting palaeopole (9°N 293°E A95= 5.1°) is in good agreement with two previously published palaeopoles from similarly aged rocks in the EWM. Collectively these data indicate that the EWM were located in the Natal Embayment prior to Gondwana break-up, and underwent 90° of anticlockwise rotation during break-up. All three studies, however, yield inclinations that are slightly too shallow when compared with coeval Gondwana reference poles.

Randall, Darren E.; Mac Niocaill, Conall

2004-04-01

112

Early Paleozoic orogenic belt of the Andes in southwestern South America: Result of Laurentia-Gondwana collision?  

Microsoft Academic Search

The late Precambrian to early Paleozoic age rock units of the Pampean ranges, the Puna, and the North Patagonian massif of southwestern South America constitute the Famatinian orogenic belt. They are interpreted as an Ordovician collisional belt between the Occidentalia terrane and the Gondwana craton. They include mafic and ultramafic belts of Neoproterozoic to early Paleozoic age. An intense tectonothermal

Luis Dalla Salda; Carlos Cingolani; Ricardo Varela

1992-01-01

113

Impact assessment of chromite mining on groundwater through simulation modeling study in Sukinda chromite mining area, Orissa, India.  

PubMed

The pre-Cambrian chromites ore deposits in Sukinda valley, Jajpur District, Orissa, India, are well known for chromite ore deposits. The exploitation of the ore is carried out through open cast mining method since the last few decades. In the process, the overburden and ore dumps are stored on ground surface, where leaching of chromite and other toxic element takes place particularly during monsoon seasons. This leachate may cause threat to groundwater in the vicinity. An integrated approach has been adopted to evaluate possibility of pollution due to mine seepage and leachate migration on groundwater regime. The approach involves geophysical, hydrogeological, hydro-chemical and aquifer modeling studies. The investigation has the significance as many habitats surround the mining area facing groundwater problems. PMID:18450374

Dhakate, Ratnakar; Singh, V S; Hodlur, G K

2008-03-20

114

High prevalence of bacterial spore-formers active against mosquito larvae in temporary monsoon flooded sites in Orissa, India.  

PubMed

Different ecosystems were probed in the vicinity of the city of Bhubaneswar in the Indian state of Orissa for the presence of bacterial spore-formers with activity against mosquito larvae. The most productive sites were places that were flooded during the monsoon season, including roadside ditches and shorelines of ponds. Among 630 isolates screened, 44 (7%) showed larvicidal activity against larvae of Aedes aegypti. The specific activity of the bacterial spore-formers varied greatly. Isolates were found with specific activities superior to the Bacillus thuringiensis israelensis reference strain of the Pasteur Institute. All mosquitocidal strains produced crystal proteins, and based on the biochemical analyses could be classified into the species B. thuringiensis. Such strains possess the potential for the development of new microbial products for mosquito control in India. PMID:21805851

Rout, Regalin; Raina, Vishakha; Suar, Mrutyunjay; Luethy, Peter

2011-06-01

115

Incidence and molecular analysis of Vibrio cholerae associated with cholera outbreak subsequent to the super cyclone in Orissa, India.  

PubMed

An epidemiological study was carried out to find out the aetiological agent for diarrhoeal disorders in the cyclone and flood affected areas of Orissa, India. Rectal swabs collected from 107 hospitalized diarrhoea patients were bacteriologically analysed to isolate and identify the various enteropathogens. Detection of toxic genes among E. coli and V. cholerae was carried out by polymerase chain reaction (PCR) assay. Of the 107 rectal swabs analysed, 72.3% were positive for V. cholerae O1 Ogawa, 7.2% for V. cholerae O139, 1.2% for E. coli (EAggEC) and 1.2% for Shigella flexneri type 6. Using multiplex PCR assay it was found that all V. cholerae isolates were ctxA positive and El Tor biotype. Strains of V. cholerae O1 were observed to be resistant to nalidixic acid, furazolidone, streptomycin, co-trimoxazole and ampicillin. Except for nalidixic acid, the resistance pattern for O139 was identical to that of O1 strains. Representative strains of V. cholerae were further characterized by randomly amplified polymorphic DNA (RAPD) analysis and ribotyping. Both O1 and O139 V. cholerae strains exhibited the R3 pattern of ribotype and belonged to a similar pattern of RAPD compared with that of Calcutta strains. Early bacteriological and epidemiological investigations have revealed the dominance of V. cholerae O1 among the hospitalized patients in cyclone affected areas of Orissa. Drinking water scarcity and poor sanitation were thought to be responsible for these diarrhoeal outbreaks. Timely reporting and implementation of appropriate control measures could contain a vital epidemic in this area. PMID:12002529

Chhotray, G P; Pal, B B; Khuntia, H K; Chowdhury, N R; Chakraborty, S; Yamasaki, S; Ramamurthy, T; Takeda, Y; Bhattacharya, S K; Nair, G Balakrish

2002-04-01

116

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

PubMed

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

Cracraft, J

2001-03-01

117

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

PubMed Central

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

Cracraft, J

2001-01-01

118

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

119

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

120

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

121

The timing and duration of the Karoo igneous event, southern Gondwana  

NASA Astrophysics Data System (ADS)

A volcanic event of immense scale occurred within a relatively short period in early Jurassic time over large regions of the contiguous Gondwana supercontinent. In southern Africa, associated remnants of thick volcanic successions of lava flows and extensive dike and sill complexes of similar composition have been grouped together as the Karoo Igneous Province. Correlative volcanic and plutonic rocks occur in Antarctica and Australia as the Ferrar Province. Thirty-two new 40Ar-39Ar incremental heating experiments on feldspars and whole rocks from Namibia, South Africa and East Antarctica produce highly resolved ages with a vast majority at 183±1 Ma and a total range of 184 to 179 Ma. These are indistinguishable from recent, high-resolution 40Ar-39Ar and U-Pb age determinations reported from the Antarctic portion of the province. Initial Karoo volcanism (Lesotho-type compositions) occurred across the entire South African craton. The ubiquitous distribution of a plexus of generally nonoriented feeder dikes and sills intruding Precambrian crystalline rocks and Phanerozoic sediments indicates that these magmas penetrated the craton over a broad region. Lithosphere thinning of the continent followed the main pulse of igneous activity, with volcanism focused in the Lebombo-Nuanetsi region, near the eventual split between Africa and Antarctica. Seafloor spreading and dispersion of east and west Gondwana followed some 10-20 m.y. afterward. The volume of the combined Karoo-Ferrar province (˜2.5×106 km3) makes it one of the largest continental flood basalt events. The timing of this event correlates with a moderate mass extinction (Toarcian-Aalenian), affecting largely marine invertebrates. This extinction event was not as severe as those recorded at the Permian-Triassic or Cretaceous-Tertiary boundaries associated with the Siberian and Deccan flood basalts events, respectively. The difference may be due to the high southerly latitude and somewhat lower eruption rates of the Karoo event.

Duncan, R. A.; Hooper, P. R.; Rehacek, J.; Marsh, J. S.; Duncan, A. R.

1997-08-01

122

Neoliberalism and Class Reproduction in India: The Political Economy of Privatisation in the Mineral Sector in the Indian State of Orissa  

Microsoft Academic Search

Recent years have witnessed a process of integration of the Indian Union within the new international economic order, characterised\\u000a by the ascendance of neoliberalism. Orissa, historically one of the Indian states mostly affected by severe poverty and economic\\u000a stagnation though richly endowed with natural resources, has enthusiastically endorsed the neo-liberal project, implementing\\u000a all the relevant national policies related to it.

Matilde Adduci

2012-01-01

123

An Assessment of Solitary and Arribada Nesting of Olive Ridley Sea Turtles (Lepidochelys olivacea) at the Rushikulya Rookery of Orissa, India  

Microsoft Academic Search

The solitary and arribada population of Olive Ridley Sea Turtles at the Rushikulya rookery of Orissa of India was monitored for two nesting seasons (2003-04 and 2004-05). Mass nesting population census of turtles was carried out using standard IUCN\\/SSC Marine Turtle Specialist Group recommended statistical technique (number of turtles counted: n = 11024). Curved carapace measurements of egg laying females

BASUDEV TRIPATHY

2008-01-01

124

European Sedimentary Basins: Deciphering Palaeozoic intra-Pangea Wrench Faulting  

NASA Astrophysics Data System (ADS)

Thick sections of sedimentary deposits act as tape recorders of the geomagnetic field over time and allow high resolution paleogeographic reconstructions. Over the past years, we were able to put together a considerable paleomagnetic data set collected from Early Permian and Mesozoic deposits in numerous sedimentary basins throughout Southwest Europe. This data set monitors relative block rotations about vertical axis in this area and thus provides convincing evidence for intra-Pangean wrench faulting in the Early Permian (~ 285-265 Ma). Here, we present previously processed data from Permian sedimentary sections from Southwest France and Sardinia together with data from the Saar-Nahe basin in West Germany. New data from the Permian/Triassic boundary from Sardinian sedimentary basins and data from Permian dyke swarms add further information to draw a more complete picture of the paleogeographic evolution of the Gondwana/Laurasia plate boundary and help to describe controversial intra-Pangean mobility and wrench faulting in the Early Permian.

Aubele, K.; Bachtadse, V.; Muttoni, G.; Ronchi, A.; Durand, M.

2012-04-01

125

Late Paleozoic paleolatitude and paleogeography of the Midland basin, Texas  

SciTech Connect

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

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

1992-04-01

126

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

127

The influence of inherited structures on dyke emplacement during Gondwana break-up in southwestern Africa  

NASA Astrophysics Data System (ADS)

A kinematic analysis of Cretaceous and pre-Cretaceous faulting and fracturing was carried out along the west coast of Southern Africa extending from the greater Cape Town area to the Orange River and beyond into southern Namibia. This study was augmented by the geometric analysis of mainly Cretaceous mafic dykes exposed from SW Angola to the southern tip of Africa. The kinematic analysis shows that the Cretaceous rifting event that led to the opening of the modern South Atlantic was largely controlled by NW-SE and NE-SW-striking structures. In the coastal areas of South Africa the Cretaceous deformation was dominated by NE-SW extension, whereas a general E-W-oriented extension prevailed further north. Analysis of reverse and strike-slip faulting in the Gariep and western Saldania Belts shows that the Pan-African constrictional deformation in South Africa was mainly controlled by ENE-WSW- to ESE-WNW-oriented shortening. Further north, the geometry of the Odgen Rock Mylonites in Namibia is controlled by N-S-striking strike-slip faults. The geometric analysis of the orientation of the mafic dykes also points to an E-W-oriented extension direction in the coastal areas extending from southern Angola to Meob and Conception Bay in west-central Namiba and changes to a generally NE-SW-oriented extension along the west coast of South Africa. Further inland in the Damara Belt sensu strictu, the geometric analysis of dykes belonging to the Hentjes Bay-Outjo Dyke Swarm also indicates NE-SW-oriented extension but, in addition, also a strong component of NW-SE-directed extension controlled dyke emplacement. The results of this study suggest that Pan-African (or older) structural discontinuities were re-utilised during the opening of the South Atlantic in the Early Cretaceous. The extension directions associated with Cretaceous Gondwana break-up structures are subparallel to the Pan-African shortening orientations. The inherited structural anisotropies are generally parallel to major lineaments and/or shear zones that, in turn, follow the trend of older mobile belts and/or are parallel to Archaean and/or Proterozoic craton boundaries. Consequently, the inherited Pan-African and/or older structures provided lithospheric anisotropies that controlled the Cretaceous rifting of SW Gondwana and the opening of the modern South Atlantic.

Will, Thomas; Frimmel, Hartwig

2013-04-01

128

New Cambrian paleomagnetic data reaffirm a Natal Embayment position for the Ellsworth-Whitmore Mountains in Gondwana reconstructions.  

NASA Astrophysics Data System (ADS)

The Ellsworth-Whitmore Mountains (EWM) are one of five allochtonous terranes that form West Antarctica. Constraining the positions of these terranes in pre-break up Gondwana is crucial to understanding the history of the Paleo-Pacific Gonwana margin. We report the results of a detailed paleomagnetic investigation of the EWM, which comprises some 150 sites in six Formations, ranging in age from Cambrian to Permian. Five of the studied units yield only viscous remnant magnetisations of recent age, or unstable NRMs. The remaining unit, the mid-late Cambrian Frazier Ridge Formation, yielded stable magnetisations at 16 of 35 sites. This component passes a fold test at 95% confidence, indicating that it pre-dates Permian deformation, and we argue that it is of primary origin. The resulting paleople (9°N 293°E A95=5.1°) is in good agreement with two previously published paleopoles from similarly aged rocks in the EWM, and collectively they indicate that the EWM were located in the Natal Embayment rpior to Gondwana break up, and underwent 90° of anticlockwise rotation during break-up. All three studies, however, yield inclinations that are slightly too shallow when compared with coeval Gondwana reference poles.

Mac Niocaill, C.; Randall, D.; Curtis, M.

2003-04-01

129

The Triassic of the Thakkhola (Nepal). II: Paleolatitudes and comparison with other Eastern Tethyan Margins of Gondwana  

NASA Astrophysics Data System (ADS)

During the Triassic, the Thakkhola region of the Nepal Himalaya was part of the broad continental shelf of Gondwana facing a wide Eastern Tethys ocean. This margin was continuous from Arabia to Northwest Australia and spanned tropical and temperate latitudes. A compilation of Permian, Triassic and early Jurassic paleomagnetic data from the reconstructed Gondwana blocks indicates that the margin was progressively shifting northward into more tropical latitudes. The Thakkhola region was approximately 55° S during Late Permian, 40° S during Early Triassic, 30° S during Middle Triassic and 25° S during Late Triassic. This paleolatitude change produced a general increase in the relative importance of carbonate deposition through the Triassic on the Himalaya and Australian margins. Regional tectonics were important in governing local subsidence rates and influx of terrigenous clastics to these Gondwana margins; but eustatic sea-level changes provide a regional and global correlation of major marine transgressions, prograding margin deposits and shallowing-upward successions. A general mega-cycle characterizes the Triassic beginning with a major transgression at the base of the Triassic, followed by a general shallowing-upward of facies during Middle and Late Triassic, and climaxing with a regression in the latest Triassic.

Ogg, J. G.; von Rad, U.

1994-03-01

130

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

Microsoft Academic Search

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

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

2008-01-01

131

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

132

150 m.y. of Tectonism along the Western Gondwana as Revealed by the Peruvian Cordillera Oriental Batholiths  

NASA Astrophysics Data System (ADS)

A striking geochemical relationship exists between the three principal plutonic belts of the Eastern Cordillera of Peru: 1) Mississippian to Pennsylvanian, I-type, metaluminous, hornblende and magnetite dominated granitoids are restricted to the segment north of 11S, and display calc-alkaline evolutionary trends with elevated LILE/HFSE ratios characteristic of continental subduction zones; 2) Permian to Early Triassic, peraluminous, I to S-type, mica and ilmenite rich granitoids of the east-central Peru, are comagmatic with the bimodal tholeiitic lavas of the Mitu Group, and characterized by restricted bimodal compositional range, moderate Fe enrichments, low LILE/HFSE values, and higher Ga/Al ratios, all of which are associated with transitional, post-orogenic (within-plate) suites; 3) Late Triassic, initially A-type monzogranitoids of the southern Cordillera de Carabaya terminate as peralkaline, SiO2-undersaturated intrusives (Ne-syenites) of the Allincapac complex emplaced in the Mitu Gr. shoshonites. The latter exhibit mineralogy characteristic of a shallow and dry source (< 1 kbar H2O-saturated conditions), display extreme Fe enrichments, steep REE profiles, and overall low LILE/HFSE ratios. Combined Sr-Nd-Pb isotope systematics from all three intrusive provinces however, lack variation, and suggest uniformly large degrees of assimilation of the Proterozoic Amazonian basement. In addition to the systematic change in the plutonic chemistry, the U/Pb and 39Ar/40Ar chronometries reveal a general younging-southward trend. The 20 m.y. long magmatism associated with the Mississippian arc in the north-central Cordillera Oriental culminated between 336-325 Ma (Pataz batholith). It was followed by c.a. 40 m.y. hiatus briefly punctuated during a 314-312 Ma episode of orogenic Au-Ag mineralization associated with a period of tectonic uplift. Resumption of the Permo-Triassic magmatism (279- 230 Ma) saw deposition of the bimodal Mitu Group volcanics contemporaneously with the intrusion of the post- collisional plutons in the central Eastern Cordillera (Carrizal, San Ramon batholiths). Sporadic magmatic activity throughout Triassic was marked by eruption of progressively more alkalic Mitu lavas and initiation of the A-type plutonism, which peaked between 216-205 Ma in the southernmost Carabaya Batholith. The 188 Ma old alkaline magmas of the Allincapac complex in the SE Peru mark the latest and most enriched pulse of rift magmatism. Our preliminary geodynamic model envisions an originally orthogonal eastward subduction of the paleo-Pacific crust below the Western Gondwana during the Late Devonian which became strongly oblique towards southeast in the Late Carboniferous, thus imposing a sinistral strike-slip stress regime on the western Amazonian margin. Accretion of a buoyant segment of oceanic crust eventually plugged the subduction zone. This scenario explains both the "craton- free" basement underlying the present Western Cordillera of northern Peru and the sudden termination of arc-related magmatism along the northern Cordillera Oriental in Pennsylvanian. Subsequent uplift and eventual relaxation of the cratonic margin facilitated emplacement of the central S-type granitoids in mid-to-late Permian. The progressive strike-slip duplexing, development of trans- tensional basins capturing the Mitu Gr. molasses, and subsequent back-arc extension in Permian occurred along the inherited suture between the Gondwanan craton and the Arequipa-Antofalla terrane. This model however, precludes the existence of an Arequipa terrane north of its presently delineated isotopic and structural boundaries and its wholesale detachment in Triassic.

Miskovic, A.; Schaltegger, U.

2006-05-01

133

Cambrian arc evolution along the SE Gondwana active margin: A synthesis from Tasmania-New Zealand-Australia-Antarctica correlations  

NASA Astrophysics Data System (ADS)

Belts of Cambrian rocks with arc affinities in eastern Australia, Tasmania, New Zealand, and Antarctica are part of a single convergent margin, active over 30-40 Ma from the latest Early Cambrian to the Late Cambrian. Two of the most complete sequences are exposed in western Tasmania and the northern South Island of New Zealand (Takaka Terrane). Throughout the Middle Cambrian, magmatism in these two regions, in the Lachlan Fold Belt (SE Australia) and the Bowers Terrane (Antarctica) is represented by intra-oceanic arc and back arc sequences. In the mid-Middle Cambrian, collision of these arc segments with the proto-Gondwana continent is recorded by obducted boninite-bearing ophiolites in Tasmania and SE Australia. Postcollisional magmatism of latest Middle to early Late Cambrian age (e.g., Mount Read Volcanics of Tasmania and Stavely Volcanic Complex of Victoria) terminates convergent tectonics in SE Australia and Tasmania. In contrast, no postcollisional volcanism is known from the Bowers Terrane in Antarctica and from New Zealand. In Antarctica, Cambrian igneous activity in the Wilson Terrane and Transantarctic Mountains formed in an active continental margin setting and lasted through the Middle and Late Cambrian. This suggests that the Wilson Terrane is the lateral continuation on continental basement of the Bowers and Takaka Terrane arcs. The differences between the Australian - Tasmanian and New Zealand - Antarctic arc segments may result from a change in subduction polarity along the arc chain, suggested by structural features, sedimentation patterns, and isotope systematics. In the SE Australian and Tasmanian arc segments the proto-Gondwana plate subducted beneath the Pacific plate whereas subduction in the Antarctic and New Zealand segments was of opposite polarity. Common to most Cambrian fragments in SE proto Gondwana is the tectonic overprint by the Ross-Delamerian orogeny from the Middle Cambrian to Early Ordovician, thus paleogeographically linking all the fragments by the end of the Cambrian. The presence of Early Cambrian intra-oceanic rocks at the SE proto-Gondwana margin suggests separation of Laurentia from Gondwana prior to the Early Cambrian.

Münker, Carsten; Crawford, Anthony J.

2000-06-01

134

New Late Permian paleomagnetic data from Argentina: Refinement of the apparent polar wander path of Gondwana  

NASA Astrophysics Data System (ADS)

The Late Paleozoic-Early Mesozoic apparent polar wander path of Gondwana is largely constructed from relatively old paleomagnetic results, many of which are considered unreliable by modern standards. Paleomagnetic results derived from sedimentary sequences, which are generally poorly dated and prone to inclination shallowing, are especially common. Here we report the results of a joint paleomagnetic-geochronologic study of a volcanic complex in central Argentina. U-Pb dating of zircons has yielded a robust age estimate of 263.0 +1.6/-2.0 Ma for the complex. Paleomagnetic analysis has revealed a pretilting (primary Permian) magnetization with dual polarities. Rock magnetic experiments have identified pseudo-single domain (titano)magnetite and hematite as the mineralogic carriers of the magnetization. Lightning-induced isothermal remagnetizations are widespread in the low-coercivity magnetic carriers. The resulting paleomagnetic pole is 80.1°S, 349.0°E, A95 = 3.3°, N = 35, and it improves a Late Permian mean pole calculated from a filtered South American paleomagnetic data set. More broadly, this new, high-quality, igneous-based paleomagnetic pole falls between the previously distinct Late Permian segments of the Laurussian and Gondwanan apparent polar wander paths, suggesting that the long-recognized disparity between these large paleomagnetic data sets may be primarily due to the inclusion of low-quality or systemically biased data.

Domeier, Mathew; van der Voo, Rob; Tohver, Eric; Tomezzoli, Renata N.; Vizan, Haroldo; Torsvik, Trond H.; Kirshner, Jordan

2011-07-01

135

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

136

Evolution of the late Paleozoic accretionary complex and overlying forearc-magmatic arc, south central Chile (38°-41°S): Constraints for the tectonic setting along the southwestern margin of Gondwana  

NASA Astrophysics Data System (ADS)

Stratigraphic, structural, metamorphic, and geochronologic studies of basement rocks in the Andean foothills and Coast Ranges of south central Chile (39°-41°S) suggest a protracted late Paleozoic to middle Mesozoic deformational and metamorphic history that imposes important constraints on the tectonic development of the southwestern Gondwana margin. In the study area the late Paleozoic paired metamorphic belt, coeval magmatic arc, and overlying Triassic sedimentary units preserve a record of Late Carboniferous to Early Permian subduction and arc magmatism, subsequent deep exhumation of the Western Series subduction complex, and diminished uplift and erosion of the Eastern Series arc-forearc region by the Late Triassic. Late Paleozoic structural elements and metamorphic assemblages formed during early subduction and arc magmatism, collectively referred to as Dl, are largely erased in the Western Series by the dominant D2 schistosity and lower greenschist grade metamorphism. D1 structural features, as well as original sedimentary textures, are relatively well preserved in the less penetratively deformed Eastern Series. The regional distribution of late Paleozoic arc magmatism suggests that the late Paleozoic convergent margin deviated from a N-S trend north of this area to a NW-SE trend near this latitude and faced an open marine environment to the southwest. A transition from F2 isoclinal folding to more open, larger-scale F3 folds, interpreted as change in ductility during differential uplift of the Western Series, is not apparent in the Eastern Series. Despite a lesser degree of uplift during the main exhumational D2 event, delineation of unconformities and U-Pb dating of detrital zircons and intrusions into the Eastern Series allow tighter constraints to be placed on timing of uplift and denudation of the Eastern Series than on that in the Western Series. A regional unconformity exposed in the Lake District that separates more highly deformed Eastern Series lithologies from Late Triassic shallow marine to continental deposits suggests that substantial uplift also affected the inner forearc and magmatic arc region during the D2 event. We propose that dextral-oblique convergence, initiated during the middle Permian along this segment of the Gondwana margin, resulted in the transpressional uplift and juxtaposition of high pressure/temperature (P/T) Western Series against low P/T Eastern Series lithologies and culminated with deposition of Late Triassic, continental to shallow marine, coarse clastic sedimentary rocks in fault-bounded strike-slip basins adjacent to the exhumed Western Series. Large-scale dextral transpression and northward displacement of the accretionary complex during Late Permian to Late Triassic time along the Chilean margin of Gondwana are synchronous and kinematically compatible with widespread regional transpression, extension, and silicic magmatism inboard of the southern Gondwana margin at this time. We thank C. Mpodozis, M. Gardeweg, and J. Muñoz of the Servicio de Geología y Minería de Chile (SERNAGEOMIN) for their support of this work. Fruitful discussions with N. Blanco, F. Hervé, H. Moreno, C. Mpodozis, and F. Munizaga have aided in our understanding of the geology of the region. The hard work by the staff of SERNAGEOMIN's Puerto Varas office is graciously appreciated. We thank J.D. Walker and W.R. Van Schmus at the University of Kansas for allowing MWM use of their U-Pb and mass spectrometer facilities and J. Vargas and the staff of SERNAGEOMIN's geochemistry laboratory for their assistance in this project. F. Munizaga allowed us to cite an unpublished 40Ar-39Ar date. We thank G. Ya˜nez for access to aeromagnetic data. T. Kato wishes to thank W. G. Ernst. Comments by I. Dalziel, S. Kay, and V. Ramos helped clarify ideas presented in this paper and are greatly appreciated. This work is dedicated to our friend and colleague Alberto Campos C., who died in a climbing accident on Calbuco Volcano, 1996.

Martin, Mark W.; Kato, Terence T.; Rodriguez, Carolina; Godoy, Estanislao; Duhart, Paul; McDonough, Michael; Campos, Alberto

1999-08-01

137

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

PubMed

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

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

2006-02-01

138

Origin of northern Gondwana Cambrian sandstone revealed by detrital zircon SHRIMP dating  

USGS Publications Warehouse

Voluminous Paleozoic sandstone sequences were deposited in northern Africa and Arabia following an extended Neoproterozoic orogenic cycle that culminated in the assembly of Gondwana. We measured sensitive high-resolution ion microprobe (SHRIMP) U-Pb ages of detrital zircons separated from several Cambrian units in the Elat area of southern Israel in order to unravel their provenance. This sandstone forms the base of the wide-spread siliciclastic section now exposed on the periphery of the Arabian-Nubian shield in northeastern Africa and Arabia. Most of the detrital zircons we analyzed yielded Neoproterozoic concordant ages with a marked concentration at 0.55-0.65 Ga. The most likely provenance of the Neoproterozoic detritus is the Arabian-Nubian shield; 0.55-0.65 Ga was a time of posttectonic igneous activity, rift-related volcanism, and strike-slip faulting there. Of the zircons, 30% yielded pre-Neoproterozoic ages grouped at 0.9-1.1 Ga (Kibaran), 1.65-1.85 Ga, and 2.45-2.7 Ga. The majority of the pre-Neoproterozoic zircons underwent Pb loss, possibly as a consequence of the Pan-African orogeny resetting their provenance. Rocks of the Saharan metacraton and the southern Afif terrane in Saudi Arabia (???000 km south of Elat) are plausible sources of these zircons. Kibaran basement rocks are currently exposed more than 3000 km south of Elat (flanking the Mozambique belt), but the shape of the detrital zircons of that age and the presence of feldspar in the host sandstone are not fully consistent with such a long-distance transport. Reworking of Neoproterozoic glacial detritus may explain the presence of Kibaran detrital zircons in the Cambrian of Elat, but the possibility that the Arabian-Nubian shield contains Kibaran rocks (hitherto not recognized) should also be explored.

Avigad, D.; Kolodner, K.; McWilliams, M.; Persing, H.; Weissbrod, T.

2003-01-01

139

Tectonic history of the Illinois basin  

SciTech Connect

The Illinois basin began as a failed rift that developed during breakup of a supercontinent approximately 550 Ma. A rift basin in the southernmost part of the present Illinois basin subsided rapidly and filled with about 3,000 m of probable Early and Middle Cambrian sediments. By the Late Cambrian, the rift-bounding faults became inactive and a broad relatively slowly subsiding embayment, extending well beyond the rift and open to the Iapetus Ocean, persisted through most of the Paleozoic Era. Widespread deformation swept through the proto-Illinois basin beginning in the latest Mississippian, continuing to the end of the Paleozoic Era. Uplift of basement fault blocks resulted in the formation of many major folds and faults. The timing of deformation and location of these structures in the forelands of the Ouachita and Alleghanian orogenic belts suggest that much of the deformation resulted from continental collision between North America and Gondwana. The associated compressional stress reactivated the ancient rift-bounding faults, upthrusting the northern edge of a crustal block approximately 1,000 m within the rift. Concurrently, dikes (radiometrically dated as Early Permian), sills, and explosion breccias formed in or adjacent to the reactivated rift. Subsequent extensional stress, probably associated with breakup of Pangea, caused the crustal block within the rift to sink back to near its original position. High-angle, northeast- to east-west-trending normal faults, with as much as 1,000 m of displacement, formed in the southern part of the basin. These faults displace some of the northwest trending Early Permian dikes. Structural closure of the southern end of the Illinois basin was caused by uplift of the Pascola arch sometime between the Late Pennsylvanian and Late Cretaceous.

Kolata, D.R.; Nelson, J.W. (Illinois Geological Survey, Champaign (USA))

1990-05-01

140

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

141

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

USGS Publications Warehouse

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

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

2006-01-01

142

Serological evidence of foot-and-mouth disease virus infection in randomly surveyed goat population of Orissa, India.  

PubMed

India is endemic for foot-and-mouth disease (FMD), and goats constitute the second largest susceptible population of domestic livestock. FMD surveillance and control strategies in the country largely ignore small ruminants, known to be critical in the epidemiology of the disease. Here, serological investigations were carried out to generate estimates of antibody prevalence in goats of Orissa state to both non-structural (NSP-Ab) and structural proteins (SP-Ab) of FMD. The apparent overall NSP-Ab and SP-Ab seroprevalences were 38% and 20.7%, respectively, which signifies a very high level of FMD virus circulation in the goat population despite the lack of clinical signs in this species. The apparent prevalence of NSP-Ab and SP-Ab was positively correlated in the sampling areas. Interestingly, the values found for NSP-Ab prevalence were almost consistently higher than those found for SP-Ab prevalence. This could have been attributable to either issues related to sensitivity and specificity of the test systems employed or differences in the post-infection kinetics of NSP- and SP-Ab. The pattern that emerged from SP-Ab analysis indicated goats being infected with all three prevalent serotypes (O, A and Asia 1) and reinforces the concept that non-vaccinated goats can be exploited as tracer animals for detecting serotypes involved in outbreaks. The results underscore the requirement to bring caprine species under comprehensive surveillance and vaccination campaigns to check silent amplification, excretion and transmission of the virus. PMID:20723161

Ranabijuli, S; Mohapatra, J K; Pandey, L K; Rout, M; Sanyal, A; Dash, B B; Sarangi, L N; Panda, H K; Pattnaik, B

2010-12-01

143

Stratigraphic Record of the Early Mesozoic Breakup of Pangea in the Laurasia-Gondwana Rift System  

NASA Astrophysics Data System (ADS)

Rift basins of the Central Atlantic Margins (CAM) of North America and Morocco preserve largely continental sequences of sedimentary strata and less important minor basalt flows spanning much of the early Mesozoic. The best known is the Newark basin of New Jersey, New York, and Pennsylvania where an astronomically calibrated magnetic polarity time scale is developed. Lacustrine cycles of Milankovitch origin are commonly present in CAM basins, with the period changing from 10 ky (paleoequator with coals), to 20 ky (4 deg--10 deg N), to perhaps 40 ky northward with evaporites. Cycles of {approximately}100 ky, 413 ky, and {approximately}2 my are also important. Four mostly unconformity-bounded tectonostratigraphic sequences are present. The Anisian TS I is fluvial and eolian. TS II--TS IV (Late Triassic to Early Jurassic), consist of "tripartite" lacustrine sequences caused by extension pulses. The Newark basin accumulation rate history allows comparison with quantitative rift basin models. The North American plate's slow northward drift resulted in a relative shift of climate, although the rapid humidification during the latest Triassic and Early Jurassic is associated with a sea-level rise. The Triassic-Jurassic mass extinction is of independent origin, plausibly impact related.

Olsen, Paul E.

144

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

145

Magma sources during Gondwana breakup: chemistry and chronology of Cretaceous magmatism in Westland, New Zealand  

NASA Astrophysics Data System (ADS)

Cretaceous-Paleogene rifting of the Eastern Gondwana margin thinned the continental crust of Zealandia and culminated in the opening of the Tasman Sea between Australia and New Zealand and the Southern Ocean, separating both from Antarctica. The Western Province of New Zealand consists of a succession of metasedimentary rocks intruded by Palaeozoic and Mesozoic granitoids that formed in an active margin setting through the Phanerozoic. Upon cessation of subduction, the earliest stages of extension (~110-100 Ma) were expressed in the formation of metamorphic core complexes, followed by emplacement of granitoid plutons, the deposition of terrestrial Pororari Group sediments in extensional half-grabens across on- and offshore Westland, and the intrusion of mafic dikes from ~90 Ma. These dikes are concentrated in the swarms of the Paparoa and Hohonu Ranges and were intruded prior to and simultaneous with volumetrically minor A-type plutonism at 82 Ma. The emplacement of mafic dikes and A-type plutonism at ~82 Ma is significant as it coincides with the age of the oldest seafloor in the Tasman Sea, therefore it represents magmatism coincident with the initiation of seafloor spreading which continued until ~53 Ma. New 40Ar-39Ar ages indicate that the intrusion of mafic dikes in basement lithologies both preceded and continued after the initial opening of the Tasman Sea, including an additional population of ages at ~70 Ma. This indicates either a prolonged period of extension-related magmatism that continued >10 Ma after initial breakup, or two discrete episodes of magmatism during Tasman Sea spreading. Volumetrically minor Cenozoic within-plate magmatism continued sporadically throughout the South Island and bears a characteristic HIMU (high time integrated U/Pb) signature. A detailed geochemistry and chronological study of Cretaceous mafic and felsic magmatism is currently in progress and aims to better understand the transition of magma sources from a long lived active continental margin through breakup to a passive setting, and to constrain the onset and evolution of the chemical characteristics of the magmas and their sources, including the origin of the distinctive HIMU signature.

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

2013-04-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2007-07-01

147

Paleozoic Orogens of Mexico and the Laurentia-Gondwana Connections: an Update  

NASA Astrophysics Data System (ADS)

The present position of Mexico in North America and the fixist tectonic models that prevailed prior to the seventies of the past century, have considered the main Paleozoic tectonic systems of Mexico as natural extensions of the orogens that fringed the eastern and southern sides of the Laurentian craton. Well known examples of pre-Mesozoic orogens in Mexico are the Oaxacan, Acatlan, and Chiapas polymetamorphic terranes, which have been correlated respectively with the Grenville and Appalachian-Ouachitan orogens of eastern North America. Nonetheless, several studies conducted during the last decade in these Mexican orogenic belts, have questioned their Laurentian connections, regarding northwestern Gondwana instead as the most plausible place for their birth and further tectonic evolution. This work pretends to approach the problem by briefly integrating the massive amount of new geological information, commonly generated through powerful dating methods such as LA-ICPM-MS on detrital zircon of sedimentary and metasedimentary units in the Paleozoic crustal blocks, which are widely exposed in southern and southeastern Mexico. The Acatlan Complex bears the closest relationships to the Appalachian orogenic system because it shows thermotectonic evidence for opening and closure of the two main oceans involved in building the Appalachian mountains in eastern Laurentia, whereas two other Paleozoic terranes in NW and SE Mexico, until recently rather geologically unknown, may constitute fundamental links between the Americas for the last-stage suturing and consolidation of western Pangea. The buried basement of the Yucatan platform (400,000 squared km) on the other hand, remains as one of the most relevant problems of tectonostratigraphic correlations across the Americas, because basement clasts from the Chicxulub impact ejecta reveal absolute and Nd-model ages that suggest close Gondwanan affinities. Major changes in the comprehension of the Paleozoic orogens in Mexico include the swift of the Acatlan Complex from Iapetus to Rheic scenarios, and the apparent continuation of the Ouachita belt across northern Mexico into south central Sonora, rather than displaced eastwards along the legendary Mojave-Sonora megashear. And yet, poorly known suture-related lithotectonic associations of Paleozoic metamorphic rocks and arc granitoids that underlie the eastern margin of Mexico, have not been explained by existing models dealing with the Appalachian-Mexico-Gondwanan connections.

Ortega-Gutierrez, F.

2009-05-01

148

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

NASA Astrophysics Data System (ADS)

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

Abu-Alam, Tamer; Stüwe, kurt

2013-04-01

149

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

NASA Astrophysics Data System (ADS)

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

Leslie, Graham; Schofield, David; Wilby, Philip

2013-04-01

150

Triassic vertebrates of gondwanan aspect from the richmond basin of virginia.  

PubMed

A new locality of early Late Triassic age in the Richmond basin of east-central Virginia has yielded abundant remains of a diversified assemblage of small to medium-sized tetrapods that closely resembles Southern Hemisphere (Gondwanan) assemblages in the predominance of certain synapsids. Associated palynomorphs indicate an early middle Carnian age for the fossiliferous strata. The discovery suggests that previously recognized differences between tetrapod assemblages of early Late Triassic age from Gondwana and Laurasia at least in part reflect differences in stratigraphic age, rather than geographic separation. PMID:17789610

Sues, H D; Olsen, P E

1990-08-31

151

Paleoclimate studies for controversial continental paleogeographies: The application of spherical geodesic grids and climate models to Gondwana's Devonian apparent polar wander path  

NASA Astrophysics Data System (ADS)

Paleomagnetic data acquired in the last 10 to 15 years have failed to clearly delineate the Devonian apparent polar wander (APW) path for Gondwana. Consequently, many paleogeographers and paleomagnetists have turned to paleoclimate data to assist in locating Gondwana. Paleoclimate data have been used to either support proposed paleomagnetic-based positions for Gondwana or to independently position the continent. Both of these approaches have problems, including how paleoclimate data are handled and the assumption of a zonal climate system. Several improvements of these approaches are proposed in this study. First, paleoclimate data were grouped into occurrences using a spherical geodesic grid system when statistical manipulations were to be performed. The use of occurrences reduces errors caused by variations in sampling resolution and post-depositional processes. Grid cells in the spherical geodesic grid systems are near-equal area and shape. A comparison between spherical geodesic grid systems with other grid systems showed that the spherical geodesic grids were the most stable grid system if used in combination with a technique called rotational minimization, which finds the fewest possible occurrences for a given data set. Second, two techniques commonly used in paleogeographic studies were modified and a third technique was introduced. The first two techniques, called the palepole zonality method and the modified pole-finder method, were designed to rate proposed pole positions for Gondwana using latitude-distribution models for paleoclimate data. The final method, the parametric climate-model method, uses a conceptual climate model to predict the climate of the continent, which was compared to regional climate inference models. The results of these techniques when applied to Gondwana suggested that the continent moved little during the Devonian: the pole moved from west-central Gondwana in the Early Devonian to the northwest or to the east by the Carboniferous. The results also show, however, that all of these techniques are limited in their ability to pick a single position for Gondwana. Consequently, the best path identified by these methods cannot be assumed to be correct and confirming paleomagnetic data are still required.

Moore, Thomas Leonard, Jr.

1999-11-01

152

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

153

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

154

3D crustal-scale heat-flow regimes at a developing active margin (Taranaki Basin, New Zealand)  

NASA Astrophysics Data System (ADS)

The Taranaki Basin in the west of New Zealand's North Island has evolved from a rifted Mesozoic Gondwana margin to a basin straddling the Neogene convergent Australian-Pacific plate margin. However, given its proximity to the modern subduction front, Taranaki Basin is surprisingly cold when compared to other convergent margins. To investigate the effects of active margin evolution on the thermal regime of the Taranaki Basin we developed a 3D crustal-scale forward model using the petroleum industry-standard basin-modelling software Petromod™.The crustal structure inherited from Mesozoic Gondwana margin breakup and processes related to modern Hikurangi convergent margin initiation are identified to be the main controls on the thermal regime of the Taranaki Basin. Present-day surface heat flow across Taranaki on average is 59 mW/m2, but varies by as much as 30 mW/m2 due to the difference in crustal heat generation between mafic and felsic basement terranes alone. In addition, changes in mantle heat advection, tectonic subsidence, crustal thickening and basin inversion, together with related sedimentary processes result in variability of up to 10 mW/m2. Modelling suggests that increased heating of the upper crust due to additional mantle heat advection following the onset of subduction is an ongoing process and heating has only recently begun to reach the surface, explaining the relatively low surface heat flow. We propose that the depth of the subducted slab and related mantle convection processes control the thermal and structural regimes in the Taranaki Basin. The thermal effects of the subduction initiation process are modified and overprinted by the thickness, structure and composition of the lithosphere.

Kroeger, K. F.; Funnell, R. H.; Nicol, A.; Fohrmann, M.; Bland, K. J.; King, P. R.

2013-04-01

155

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

156

Development of the early Paleozoic Pacific margin of Gondwana from detrital-zircon ages across the Delamerian orogen  

NASA Astrophysics Data System (ADS)

Detrital-zircon age spectra have been determined for sedimentary rocks from the Delamerian orogen, southern Australia. In Neoproterozoic sedimentary rocks, patterns progressively change from Mesoproterozoic- to Neoproterozoic-dominated detritus and there are few zircons that are close to the depositional age. The base of the Cambrian Kanmantoo Group marks an abrupt change in provenance to detrital patterns dominated by Ross and Delamerian (600 500 Ma) and Grenvillean ages (1200 1000 Ma). These patterns are strikingly similar to those obtained from Lachlan fold belt sedimentary rocks, indicating that the sedimentation recorded in the Kanmantoo Group marks a change from deposition of sediments derived from the Australian cratons to those representative of the early Paleozoic Gondwana mudpile. If sedimentary rocks with zircon-provenance characteristics such as those of the Kanmantoo rocks extend under elements of the Lachlan fold belt, they would provide suitable protoliths for the S-type granites of southeastern Australia.

Ireland, T. R.; Flöttmann, T.; Fanning, C. M.; Gibson, G. M.; Preiss, W. V.

1998-03-01

157

From northern Gondwana passive margin to arc dismantling: a geochemical discrimination of Ordovician volcanisms (Sardinia, Italy)  

NASA Astrophysics Data System (ADS)

In Sardinia, one of the southernmost remain of the European Variscan belt, a crustal section through northern Gondwanan paleodomains is largely preserved. It bears significant evidence of igneous activity, recently detailed in field relationships and radiometric dating (Oggiano et al., submitted). A Cambro - Ordovician (491.7 ± 3.5 Ma ÷ 479.9 ± 2.1 Ma, LA-ICP-MS U-Pb zircon age) bimodal volcanic suite occurs with continuity in external and inner Variscan nappes of Sardinia below the so-called Sardic unconformity. The igneous suite represents an intraplate volcanic activity developed through subsequent episodes: i) an intermediate explosive and effusive volcanism, i.e. pyroclastic fall deposits and lava flows, embedded into epicontinental clastic sediments, culminating in silicic ignimbrite eruptions, and ii) mafic effusives. Geochemical data document a transitional, within-plate signature, e.g. the average Th/Ta (4.5) and La/Nb (2.7) overlap the upper continental crust values. The volcanites are characterized by slight fractionation of LREEs, nearly flat HREE abundance. The negative Eu anomaly increases towards evolved compositions. Some prominent HREE depletion (GdCN/YbCN = 13.8), and the high Nb/Y suggest a garnet-bearing source. The high 87Sr radiogenic content (87Sr/86Sr 490 Ma = 0.71169) and the epsilon Nd 490 Ma value of -6.54 for one dacite sample, imply a time integrated LREE-enriched source with a high Rb/Sr, such as a metasedimentary source. The stratigraphy of the succession and the geochemical composition of igneous members suggest a volcanic passive margin along the northern Gondwana at the early Ordovician. The bimodal Mid-Ordovician arc volcanism (465.4 ± 1.4 Ma, U-Pb zircon age; Oggiano et al., submitted) is developed in the external nappes (e.g. in Sarrabus and Sarcidano) and in the foreland occurs as clasts at the base of the Hirnantian succession (Leone et al. 1991). The Mid Ordovician sub-alkalic volcanic suite has reliable stratigraphic and palaeontological constraints, as it post-dates the Sarrabese (i.e. Sardic) unconformity and pre-dates the Upper Ordovician transgression. It consists of basaltic - andesites and abundant andesites and rhyolites. The negative Ta-, Nb-, Sr-, P-, Yb- and Ti-anomalies in mantle-normalized spiderdiagrams and Th/Ta compare with volcanic rocks from active continental margins. Andesite and dacite samples reveal Sr and Nd isotopic compositions consistent with a less depleted mantle source than rhyolites (epsilon Nd 465 Ma = -3.03 to -5.75; 87Sr/86Sr 465 Ma = 0.70931-0.71071). The positive epsilon Nd 465 Ma values of rhyolites (+1.15 to +2.42) suggest that their precursors, with a crustal residence age of ~1 Ga (TDM), were derived from a long-term depleted mantle source. On the whole, the isotopic data for Mid Ordovician volcanites suggest partial melting of an isotopically heterogeneous mantle. The bimodal suite has been unanimously interpreted as a marker of the Rheic ocean subduction. An Upper Ordovician transitional to alkalic volcanic activity is documented both in the foreland, and in the external and internal nappes (Di Pisa et al. 1992). The Late Ordovician alkalic mafic suite (440 ± 1.7 Ma) i.e. the Ordovician-Silurian boundary, occurs as sills, epiclastites and lava flows within the post-Caradocian transgressive sequence. The volcanic rocks are characterized by fractionation of REEs (LaCN/YbCN ~ 4.4-13), variable LILE abundances and significant Ta, Nb and LREE enrichments. Th/Ta in the range 1-2 and La/Nb < 1 evidence an anorogenic intraplate setting. The epsilon Nd 440 Ma values are positive (+1.60 to +4.14), reflecting an origin in a depleted mantle source, while the 87Sr/86Sr vary from 0.70518 to 0.71321. Negative epsilon Nd 440 Ma values (-4.76 and -4.62) in trachy-andesites suggest a less depleted mantle source, while the 87Sr/86Sr 440 Ma (0.70511 to 0.70694) and the Sm/Nd up to 0.36 align along the mantle array. The Late Ordovician alkalic suite suggest a continental rift geodynamic setting, and likely represent an early phase of the major rifting e

Gaggero, L.; Oggiano, G.; Buzzi, L.; Funedda, A.

2009-04-01

158

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

159

Geodynamic basin classification  

SciTech Connect

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

Klein, G.

1987-05-01

160

Parana basin  

Microsoft Academic Search

The Parana basin is a large intracratonic basin in South America, developed entirely on continental crust and filled with sedimentary and volcanic rocks ranging in age from Silurian to Cretaceous. It occupies the southern portion of Brazil (1,100,000 km² or 425,000 mi²) and the eastern half of Paraguay (100,000 km² or 39,000 mi²); its extension into Argentina and Uruguay is

P. V. Zalan; S. Wolff; J. C. J. Conceicao; I. S. Vieira; M. A. Astolfi; V. T. Appi; O. Zanotto; E. V. S. Neto; J. R. Cerqueira

1987-01-01

161

The role of the Variscan eastern Gondwana-Laurussia/Laurasia boundary in the evolution of the central Mediterranean area  

NASA Astrophysics Data System (ADS)

The geodynamic evolution of the central Mediterranean area is linked to the interaction between Gondwana and Laurussia/Laurasia plates. The interaction between these plates led to the development of Variscan, Alpine and Apennine Orogenic belts. In spite of the different ages of the orogenic systems, it is possible to hypothesize that their geodynamic evolution was linked to the complex interactions between the eastern boundary of Gondwana and the western boundary of Laurussia/Laurasia. This irregular boundary could have played the role of a pre-existing tectonic barrier which started to develop during the Upper Carboniferous. The kinematic along the boundary was related to a transpressive regime which evolved through a shear zones system (“snake” strike-slip and oblique shear zones). The transpressive environment led to the formation of restraining/releasing bends along the boundary between the two plates. The exhumation of middle/deep crustal rocks by telescoping processes, coeval with the transcurrent movement, occurred in the core of this narrow shear zone. The first occurrences of restraining/releasing bends are related to the Early Visean-Bashkirian (Variscan orogeny). The Variscan eastern boundary between the two colliding plates is characterized by a long-narrow band of HT rocks (East Variscan Shear Zone, EVSZ). From South to North they are: Calabria-Peloritani Terrane (Calabria and Sicily), deep basement of northern Apennines, Sardinia, Corsica, Maures-Tanneron Massif and Alpine Massifs. The same boundary was later reworked by the opening of the Alpine Tethys, dated at the Middle-Upper Jurassic. The opening of the Alpine Tethys led to the separation of the Variscan crust which will represent the future Alpine Massifs (External and Internal Massifs). The closure of the Alpine Tethys and the beginning of the Alpine Orogeny (Late Cretaceous to Eocene) re-assembled the system. The roto-translation of the Sardinia-Corsica and Calabrian-Peloritan blocks during the Upper Eocene-Early Miocene partially shifted the EVSZ, as well as the southern sector of the Alpine Belt, to the East and led to the beginning of the Apenninic orogenic events. The shifted portion has been again reworked by the opening of the northern Tyrrhenian Sea in the Late Miocene simoultaneously to the migration toward SE of the Calabrian-Peloritan sector. The evolution of the northern Apennines orogenic sector developed through transpressive and transtensive structures such as restraining and releasing bends which were active during the Upper Oligocene-Pliocene time interval. The aim of this work, in spite of the well knowledge of the geodynamic frame of the central Mediterranean area, is to emphasize the role played by the eastern boundary between Gondwana and Laurussia/Laurasia plates (EVSZ) as a persistent tectonic barrier from the Late Carboniferous to Late Miocene.

Padovano, M.; Elter, F. M.; Pandeli, E.

2010-12-01

162

Crustal architecture beneath Madurai Block, southern India deduced from magnetotelluric studies: Implications for subduction–accretion tectonics associated with Gondwana assembly  

Microsoft Academic Search

The Madurai Block in southern India is considered to represent the eroded roots of an arc-accretionary complex that developed during the subduction–collision tectonics associated with the closure of the Mozambique Ocean and final suturing of the crustal fragments within the Gondwana supercontinent in the Late Neoproterozoic–Cambrian. Here we present a magnetotelluric (MT) model covering the main collisional suture (Palghat–Cauvery Suture

K. Naganjaneyulu; M. Santosh

2011-01-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

164

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

PubMed Central

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

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

2012-01-01

165

GREAT BASIN  

Technology Transfer Automated Retrieval System (TEKTRAN)

It seems clear that population growth in the Great Basin will continue into the future. Major population centers will continue to grow, which will cause outflow to surrounding small and medium-sized towns. An increasing number of retirees will also seek places with a favorable climate and recreati...

166

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

PubMed

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

Bisht, Satpal S; Panda, Amrita K

2011-04-14

167

Production of poly-3-hydroxyalkanoic acids by a moderately halophilic bacterium, Halomonas marina HMA 103 isolated from solar saltern of Orissa, India.  

PubMed

Halomonas marina HMA 103 (MTCC 8968), the moderately halophilic bacterium isolated and characterized from the solar saltern of Orissa, India, grows optimally at 10% (w/v) NaCl in culture medium and is able to synthesize poly(3-hydroxybutyrate) [P(3HB)] during growth. This study is an attempt to optimize the cultural conditions for efficient production of P(3HB) by H. marina in batch cultivation. Growth of the organism under shake-flask culture using 2% (w/v) glucose resulted in P(3HB) accumulation accounting for more than 59% of cell dry weight after 50 h of incubation. The optimum P(3HB) production was attained with a combined supply of NH4Cl and yeast extract as N-source, 0.01% (w/v) phosphate, 1.5% (w/v) sulphate and 10% (w/v) NaCl. Qualitative and quantitative 1HNMR and FT-IR analysis of cells grown in alkanoic acids (C3-C6) as sole source of carbon and co-substrates revealed synthesis of PHA co-polymers composed of 3-hydroxybutyric acid and 3-hydroxyvaleric acid [P(3HB-co-3HV)]. In two-step cultivation, accumulation of the co-polymer was significantly improved (80% CDW) in glucose medium supplemented with valerate (0.1%, w/v) as co-substrate and the polymer contained 88.1 and 12.8 mol% 3HB and 3HV monomers, respectively. PMID:19621765

Biswas, Amrita; Patra, A; Paul, A K

2009-06-01

168

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

169

Permian basin gas production  

Microsoft Academic Search

Of the 242 major gas fields in the Permian basin, 67 are on the Central Basin Platform, 59 are in the Delaware basin, 44 are in the Midland basin, 28 are in the Val Verde basin, 24 are on the Eastern Shelf, 12 are in the Horshoe Atoll and eight are on the Northwest Shelf. Eleven fields have produced over

Haeberle

1995-01-01

170

The Pannonian Basin  

SciTech Connect

This book contains chapters on basin evolution. Included are the following chapters: late Cenezoic tectonics of the Pannonian Basin System, some aspects of Neogene biostratigraphy in the Pannonian Basin, lithosphere and evolution of the Pannonian Basin, variations in extensional styles at depth across the Pannonian Basin System.

Royden, L.H.

1988-01-01

171

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

NASA Astrophysics Data System (ADS)

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

Armendáriz, Maider; Quesada, Cecilio; Rosales, Idoia

2013-04-01

172

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

NASA Astrophysics Data System (ADS)

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

2008-06-01

173

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 times.

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

2011-04-01

174

The first stages of evolution of the Western Somali Basin  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

175

Impact of Indian Total Sanitation Campaign on Latrine Coverage and Use: A Cross-Sectional Study in Orissa Three Years following Programme Implementation  

PubMed Central

Background Faced with a massive shortfall in meeting sanitation targets, some governments have implemented campaigns that use subsidies focused on latrine construction to overcome income constraints and rapidly expand coverage. In settings like rural India where open defecation is common, this may result in sub-optimal compliance (use), thereby continuing to leave the population exposed to human excreta. Methods We conducted a cross-sectional study to investigate latrine coverage and use among 20 villages (447 households, 1933 individuals) in Orissa, India where the Government of India’s Total Sanitation Campaign had been implemented at least three years previously. We defined coverage as the proportion of households that had a latrine; for use we identified the proportion of households with at least one reported user and among those, the extent of reported use by each member of the household. Results Mean latrine coverage among the villages was 72% (compared to <10% in comparable villages in the same district where the Total Sanitation Campaign had not yet been implemented), though three of the villages had less than 50% coverage. Among these households with latrines, more than a third (39%) were not being used by any member of the household. Well over a third (37%) of the members of households with latrines reported never defecating in their latrines. Less than half (47%) of the members of such households reported using their latrines at all times for defecation. Combined with the 28% of households that did not have latrines, it appears that most defecation events in these communities are still practiced in the open. Conclusion A large-scale campaign to implement sanitation has achieved substantial gains in latrine coverage in this population. Nevertheless, gaps in coverage and widespread continuation of open defecation will result in continued exposure to human excreta, reducing the potential for health gains.

Barnard, Sharmani; Routray, Parimita; Majorin, Fiona; Peletz, Rachel; Boisson, Sophie; Sinha, Antara; Clasen, Thomas

2013-01-01

176

Cadomian (Ediacaran-Cambrian) arc magmatism in the Bitlis Massif, SE Turkey: Magmatism along the developing northern margin of Gondwana  

NASA Astrophysics Data System (ADS)

Small granitic plutons and associated granitic dykes that intrude the pre-Devonian basement of the Bitlis Massif were previously inferred to have a broadly Late Palaeozoic crystallisation age related to the Hercynian orogeny; this was tested during this work. The brittle-ductile-deformed Mutki granite pluton and nearby granitic dykes comprise mainly quartz, alkali feldspar, plagioclase, subordinate biotite, muscovite and rare amphibole. Based on the results of whole-rock major-element and trace-element analysis, the Mutki pluton and associated dykes are inferred to have crystallised from metaluminous, to peraluminous subduction influenced I-type melts. Sm-Nd isotope systematics indicate melting of a mantle source (of notional 1.3 Ga age), with increasing amounts of crustal contamination through time. U/Pb zircon dating of the Mutki granite and a nearby granitic dyke by laser inductively coupled plasma mass spectrometry (LA-ICP-MS) yielded 238U/206Pb crystallisation ages of 545.5 ± 6.1 Ma and 531.4 ± 3.6 Ma, respectively (Ediacaran-Early Cambrian). This shows for the first time that the regionally extensive Bitlis Massif was affected by Cadomian arc-type magmatism. The Ediacaran-Early Cambrian granitic rocks of the Bitlis Massif can be compared with similar-aged metagranitic and metavolcanic rocks within basement units exposed in the Tauride-Anatolide Platform (Menderes-Taurus Block) in western Anatolia and also in NW Turkey. Similar-aged rocks are also exposed in the basement of Iran. All of these magmatic units and their host rocks are interpreted as fragments of a Cadomian active margin bordering the northern margin of Gondwana after its final amalgamation. Formation of the Bitlis Massif granites and contemporaneous granitic units elsewhere in Turkey as fragments of an Andean-type margin adjacent to the Arabian-Nubian Shield is favoured over an alternative explanation as exotic terranes transported > 2000 km eastwards from a Cadomian active margin near West Africa-Amazonia (now NW Africa).

Ustaömer, P. Ayda; Ustaömer, Timur; Collins, Alan S.; Robertson, Alastair H. F.

2009-07-01

177

Ordovician continental margin terranes in the Lachlan Orogen, Australia: Implications for tectonics in an accretionary orogen along the east Gondwana margin  

NASA Astrophysics Data System (ADS)

Four continental margin turbidite ± black shale terranes of the Lachlan Orogen in the southern Tasmanides of eastern Australia formed in two major systems along the east Gondwana margin and constrain the Ordovician assembly of this accretionary orogen. Key features are the dissimilar stratigraphies of the adjacent Bendigo and Melbourne terranes in the western system; the dissimilar stratigraphies of the adjacent Melbourne and Albury-Bega terranes that reflect juxtaposition of the two systems during the Middle Devonian, and the presence of the Albury-Bega Terrane both west and east of the Macquarie Arc in the eastern system that also includes the ocean floor Narooma Terrane and igneous ocean crust terrane(s). Repetition of the Albury-Bega Terrane either side of the arc requires either rifting or orogen-parallel, strike-slip duplication of a once contiguous package. Terrane interactions began in the earliest Gisbornian with early docking, uplift, deformation, and exchange of detritus. Amalgamation occurred in the earliest Silurian Benambran Orogeny with accretion in the Middle Devonian. Over 40 Myr, discrete turbidite terranes aligned along the Gondwana margin in two systems were converted into a very wide orogen characterized by the along-strike juxtaposition of superficially similar terranes.

Glen, R. A.; Percival, I. G.; Quinn, C. D.

2009-12-01

178

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

179

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.

180

Crustal thickening along the West Antarctic Gondwana margin during mid-Cretaceous deformation of the Triassic intra-oceanic Dyer Arc  

NASA Astrophysics Data System (ADS)

Subduction-related Mesozoic mafic dykes in eastern Palmer Land, Antarctic Peninsula, record the development of an intra-oceanic arc terrane, the Dyer Arc, probably of late Permian-Triassic age, represented by a tholeiitic dyke group. Arc rocks were deformed in late Triassic-early Jurassic and mid-Cretaceous times on the Gondwana margin. Eruption of syn- to post-mid-Cretaceous orogenesis magmatism is represented by a calc-alkaline group of dykes. The tholeiitic dykes intruded immature granitic crust of the Eastern Zone sub-terrane of the Central Domain, one of the magmatic terranes of the Pacific margin of Gondwana. The calc-alkaline dykes straddle the major tectonic boundary between the Central Domain and the continental margin Eastern Domain. 132 dykes were studied, 82 of which are calc-alkaline, 48 tholeiitic and two shoshonitic, across an area of approximately 4000 km2. Tholeiitic dykes strike broadly NNW-SSE, transposed into parallelism with the strike of the tectonic boundary during Cretaceous orogenesis whereas calc-alkaline dykes strike tightly ESE-WNW at a high angle to the boundary. The tholeiites pre-date late Triassic deformation and metamorphism, and are interpreted as dominantly Triassic in age, whereas Ar-Ar dated calc-alkaline dykes are younger (~ 100 Ma and ~ 97 Ma) and field relations indicate that they overlap with the waning phase of the mid-Cretaceous Palmer Land Event. The tholeiites have trace element abundances similar to, but more depleted than, those of modern intra-oceanic arcs, as recorded by Zr/Hf ratios. Nb/Yb versus TiO2*/Yb and Sm/Yb versus La/Sm plots are used to model depths of partial melting. The tholeiites were mostly generated at shallow depths corresponding to 2.5 and certainly less than 3.0 GPa in largely garnet-free mantle. The calc-alkaline magmas were generated at pressures greater than 3.0 to possibly > 3.5 GPa, in the garnet zone. The deepening of the mantle source, and onset of calc-alkaline magmatism are interpreted to have been caused by deformation of the intra-oceanic arc terrane on the Gondwana margin, and lithospheric thickening during the Palmer Land Event.

Vaughan, Alan P. M.; Leat, Philip T.; Dean, Alison A.; Millar, Ian L.

2012-06-01

181

Fluid characteristics of retrogressed eclogites and mafic granulites from the Cambrian Gondwana suture zone in southern India  

NASA Astrophysics Data System (ADS)

Eclogite-facies rocks and high-pressure granulites provide windows to the deeper parts of subduction zones and the root of mountain chains, carrying potential records of fluids associated with subduction-accretion-collision tectonics. Here, we report petrological and fluid inclusion data on retrogressed eclogite and high-pressure granulite samples from Sittampundi, Kanji Malai and Perundarai in southern India. These rocks occur within the trace of the Cambrian collisional suture which marks the final phase of amalgamation of the Gondwana supercontinent. The garnet-clinopyroxene assemblage in the eclogites preserves relict omphacite, whereas the high-pressure granulites are characterized by an assemblage of garnet and clinopyroxene in the absence of omphacite and with minor plagioclase, orthopyroxene, and quartz. Phase relations computed for the eclogite assemblage yield peak P- T conditions of 19 kbar and 1,010°C. The mafic granulites also preserve the memory of high to ultrahigh-temperature metamorphism followed by an isothermal decompression. Systematic fluid inclusion optical, microthermometric and laser Raman spectroscopic studies were conducted in garnet and plagioclase from the eclogite-high pressure granulite suite. The results suggest that the early fluids were a mixture of CO2, CH4 and N2 probably derived from decarbonation and devolatilization reactions in a subduction setting during the prograde stage. The later generation inclusions, which constitute the dominant category in all the samples studied, are characterized by a near-pure CO2 composition with moderate to high densities (up to 1.154 g/cm3). The highest density fluid inclusions recorded in this study occur within the mafic granulites from Sittampundi (0.968-1.154 g/cm3) and Kanji Malai (1.092-1.116 g/cm3). In some cases, carbonate minerals such as dolomite and calcite are associated with the CO2-rich fluid inclusions. The composition and densities of the later generation fluids closely match with those of the CO2-bearing fluid inclusions reported from ultrahigh-temperature granulites occurring proximal to the eclogite-high pressure granulite suite within this suture zone, and suggest a common tectonic link for the fluid regime. We evaluate the fluid characteristics associated with convergent plate margin processes and propose that the early aqueous fluids probably associated with the eclogites were consumed during the formation of the retrograde hydrous mineral assemblages, whereas the fluid regime of the high-pressure and ultrahigh-temperature granulites was mostly CO2-dominated. The tectonic setting of the rocks along a collisional suture marking the trace along which crustal blocks were welded through subduction-collision process is in favor of a model involving the derivation of CO2 from sub-lithospheric sources such as a carbonated tectosphere invaded by hot asthenosphere, or underplated mafic magmas.

Santosh, M.; Tsunogae, Toshiaki; Shimizu, Hisako; Dubessy, Jean

2010-03-01

182

Cambrian volcanism in the Lhasa terrane, southern Tibet: Record of an early Paleozoic Andean-type magmatic arc along the Gondwana proto-Tethyan margin  

NASA Astrophysics Data System (ADS)

The present study reports new zircon LA–ICP–MS U–Pb ages, trace element and Hf isotope data, and whole-rock major and trace element data from Cambrian metarhyolites from Zhaqian and Zhakang in the central Lhasa subterrane of southern Tibet. One sample from Zhakang provides a weighted mean 206Pb/238U age of 510.4 ± 4.0 Ma and two samples from Zhaqian yield weighted mean 206Pb/238U ages of 510.6 ± 2.6 Ma and 524.8 ± 2.9 Ma, indicating that the Zhaqian and Zhakang metarhyolites were contemporaneous. Both are characterized by high SiO2 and K2O and low Na2O. They are also primarily high-K calc-alkaline, are enriched in Th, U, and light rare earth elements (LREEs), and are depleted in Nb, Ta, Ti, and P. Thus, they are geochemically similar to typical arc volcanic rocks. Moreover, the Zhaqian metarhyolites exhibit varying zircon ?Hf(t) values (?3.8 to +0.3) that are comparable to those of the Zhakang metarhyolites (?4.9 to ?1.0). Both metarhyolites are interpreted as resulting from partial melting of Proterozoic metasedimentary rocks with mantle-derived magma contributions. Contemporaneous magmatism in the early Paleozoic has also been recognized in other microcontinents along the Gondwana proto-Tethyan margin. The emplacement of these magmatic rocks and the development of a Cambro–Ordovician angular unconformity in the central Lhasa subterrane can be attributed to subduction of proto-Tethys Ocean lithosphere in a Andean-type magmatic arc setting following the assembly of various continental components within the Gondwana supercontinent.

Hu, Peiyuan; Li, Cai; Wang, Ming; Xie, Chaoming; Wu, Yanwang

2013-11-01

183

Evaporite cycles and cycle boundaries in the upper part of the Paradox Member, Hermosa Formation of Pennsylvanian age in the Paradox basin, Utah and Colorado  

SciTech Connect

The evaporites of the Paradox Member of the Hermosa Formation of Pennsylvanian age in southeastern Utah and southwestern Colorado are direct precipitates from marine brines and have been changed only slightly by subsequent events. Geophysical logs of deep wells indicate that the Paradox Member is composed of at least 30 evaporite cycles. Lithologies that make up the cycles, in order of increasing salinity, are organic carbon-rich carbonate shale (black shale), dolomite, anhydrite, and halite (with or without potash). Studies of core from two wells in the central part of the basin show that some of the cycles in the upper part of the Paradox Member are remarkably symmetrical, indicating regular changes in salinity. Detailed petrologic studies have revealed newly recognized lithologic textures and cycle boundaries in 11 evaporite cycles, indicating very regular cyclicity of subaqueous sedimentation in a basin in which salinity was probably controlled by Gondwana glaciation.

Raup, O.B.; Hite, R.J. (U.S. Geological Survey, Denver, CO (United States))

1991-03-01

184

K-Ar evidence from illitic clays of a Late Devonian age for the 120 km diameter Woodleigh impact structure, Southern Carnarvon Basin, Western Australia  

NASA Astrophysics Data System (ADS)

Woodleigh is a recently discovered impact structure with a diameter of 120 km, and thereby represents the third largest proven Phanerozoic impact structure known after Morocweng and Chicxulub. K-Ar isotopic studies of fine-grained authigenic illitic clay minerals (<2 ?m), considered to be impact-induced hydrothermal alteration products, indicate a Late Devonian (359±4 Ma) age for the impact. Other evidence reported for Late Devonian extraterrestrial impacts include the strong iridium anomaly in the Canning Basin, Western Australia, and microtektites and elemental anomalies (including iridium) in South China. Given the large diameter of the Woodleigh impact structure and its relative proximity to iridium anomalies also of Late Devonian age in eastern Gondwana basins, environmental effects of the Woodleigh impact event are a likely contributor to a biotic crisis in the Late Devonian.

Uysal, I. Tonguç; Golding, Suzanne D.; Glikson, Andrew Y.; Mory, Arthur J.; Glikson, Miryam

2001-10-01

185

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

186

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

NASA Astrophysics Data System (ADS)

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

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

2006-08-01

187

The Fairway-Aotea Basin and the New Caledonia Trough, witnesses of the Pacific-Australian plate boundary evolution : from mid-Cretaceous cessation of subduction to Eocene subduction renewal  

NASA Astrophysics Data System (ADS)

The geodynamical history of the SW Pacific is controlled since the Mesozoic by the evolution of peri-Pacific subduction zones, in a trench retreat by slab roll-back process, which successively occurred along the Eastern Gondwana margin. In this context, most basins which formed after 45 Ma reached a stage of seafloor spreading, have recorded the inversions of the earth's magnetic field and present typical oceanic crust morphologies. By contrast, the New Caledonia and Fairway basins, which are narrower and present thick sedimentary covers have a less known and more controversial origin. Based on a regional geological synthesis and on interpretation of multichannel seismic reflection and refraction data, combined with drill hole data off New Zealand and a compilation of regional potential data, we distinguish 2 phases of the evolution of the Fairway-Aotea Basin (FAB) and the New Caledonia Trough (NCT), which reflect the evolution of the Gondwana-Pacific plate boundary: Phase 1: Mid Cretaceous formation of the FAB in a continental intra- or back- arc position of the Pacific-Gondwana subduction system. The formation of this shallow basin reflects the onset of continental breakup of the Eastern Gondwana margin during Cenomanian which was most probably caused by a dynamic change of the subduction zone through a « verticalization » of the slab. This event may be the result of the 99 Ma kinematic plate reorganization which probably led to subduction cessation along the Gondwana-Pacific plate boundary. A tectonic escape mechanism, in relation with the locking of the subduction zone by the Hikurangi Plateau, could also be responsible of the trench retreat leading to backarc extension. Phase 2: Regional Eocene-Oligocene uplift followed by rapid subsidence (3-4 km) of the system « Lord Howe Rise - FAB - Norfolk Ridge ». The structural style of this deformation leads us to suggest that detachment of the lower crust is the cause of subsidence. We therefore propose a model in which the system, initially shallow during Cretaceous (phase 1), would have greatly subsided during Eocene-Oligocene, giving birth to the NCT, as the renewal of the Australia-Pacific convergent plate boundary took place. This renewal of convergence at 45 Ma would have driven the lithosphere of the system to thicken (uplift), leading to a root instability and to its detachment in the mantle (subsidence). Superposed on these two main phases, some local effects, controlled by the geometry of the plate boundary, also appear. Particularly, latest late Eocene local deformation of the Northern NCB is documented, synchronously with the New Caledonian obduction. This asymmetrical deformation which lasted less than a few million years led to the uplift of the Fairway Ridge and the subsidence of the Eastern margin of the basin along NC’s western coast (10 km vertical amplitude). We suggest that as the oceanic crust of the South Loyalty Basin was being obducted onto the Norfolk Ridge at 37 Ma, the NCB subsided under the effect of the overloading and underthrusted to accommodate the compressional deformation as a foreland flexural basin.

Collot, J.; Geli, L. B.; Lafoy, Y.; Sutherland, R.; Herzer, R. H.; Roest, W. R.

2009-12-01

188

Reserves in Western Basins  

SciTech Connect

The objective of this project is to investigate the reserves potential of overpressured tight (OPT) gas reservoirs in three Rocky Mountain basins. These are the Greater Green River Basin (GGRB), Uinta Basin and Piceance Basin. By documenting productive characteristics in these basins and characterizing the nature of the vast gas resources in place, the reserves potential may be understood and quantified. Through this understanding, it is hoped that the oil and gas industry will be encouraged to pursue exploitation of this resource. At this point in time, the GGRB work has been completed and the final report submitted for publication. Work on the Uinta basin has just commenced and work on the Piceance basin will commence next year. Since the GGRB portion of this project has been completed, further discussion centers upon this Basin.

Caldwell, R.H.; Cotton, B.W.

1993-12-31

189

Nam Con Son Basin  

Microsoft Academic Search

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

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

1994-01-01

190

Long Hair Shampoo Basin.  

National Technical Information Service (NTIS)

The present invention relates to a long hair shampoo basin for use at barber shops and beauty salons. More specifically, the present invention is directed to shampoo basins which are adapted for shampooing longer hair than is accommodated by present basin...

K. Schulken

2005-01-01

191

Mechanics of forearc basins  

Microsoft Academic Search

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

Teodoro Cassola; Sean D. Willett; Heidrun Kopp

2010-01-01

192

Palynodating of subsurface sediments, Raniganj Coalfield, Damodar Basin, West Bengal  

NASA Astrophysics Data System (ADS)

The Gondwana sediments comprising fine-grained shales, carbonaceous shales, sandstones and the coal horizon in borecore RT-4 (approximately 547.00m thick) from Tamra block, Raniganj Coalfield, Damodar Basin, are analyzed palynologically. Based on the distribution pattern of marker palynotaxa, two assemblage zones are identified. In the Barren Measures Formation, dominance of enveloping monosaccate ( Densipollenites) along with striate bisaccate ( Striatopodocarpites, Faunipollenites) pollen taxa, and the FAD's of Kamthisaccites and Arcuatipollenites observed at 30.75, have equated this strata (30.75-227.80 m thick) with the Raniganj Formation of Late Permian in age. Downwards in the Barakar Formation, between 423.80-577.70 m depths, an abundance of non-striate ( Scheuringipollenites) and striate ( Faunipollenites and Striatopodocarpites) bisaccate pollen taxa is observed, that dates late Early Permian in age. Fair occurrences of hyaline, distorted and blackish-brown plant matter is observed within 231.00-408.40 m depths. Present study infers the existence of the Raniganj Formation in the lithologically delimited Barren Measures Formation in the study area, and the underlying unproductive strata (approx. 177.40m) might represent the part of the Barren Measures Formation.

Murthy, Srikanta; Chakraborti, B.; Roy, M. D.

2010-10-01

193

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

194

Reserves in western basins  

SciTech Connect

This project requires generation of producible tight gas sand reserve estimates for three western basins. The requirement is to perform such reserve estimates using industry accepted practices so that results will have high credibility and acceptance by the oil and gas industry. The ultimate goal of the project is to encourage development of the tight gas formation by industry through reduction of the technical and economic risks of locating, drilling and completing commercial gas wells. The three geological basins selected for study are the Greater Green River Basin, Uinta Basin and Piceance Basin, located in the Colorado, Utah and Wyoming Rocky Mountain region.

Caldwell, R.H.; Cotton, B.W.

1992-06-01

195

Reserves in western basins  

SciTech Connect

This project requires generation of producible tight gas sand reserve estimates for three western basins. The requirement is to perform such reserve estimates using industry accepted practices so that results will have high credibility and acceptance by the oil and gas industry. The ultimate goal of the project is to encourage development of the tight gas formation by industry through reduction of the technical and economic risks of locating, drilling and completing commercial gas wells. The three geological basins selected for study are the Greater Green River Basin, Uinta Basin and Piceance Basin, located in the Colorado, Utah and Wyoming Rocky Mountain region.

Caldwell, R.H.; Cotton, B.W.

1992-01-01

196

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

197

Divergent/passive margin basins  

SciTech Connect

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

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

1989-01-01

198

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

NASA Astrophysics Data System (ADS)

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

Vecoli, Marco; Le Hérissé, Alain

2004-10-01

199

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

200

Major shear zones of southern Brazil and Uruguay: escape tectonics in the eastern border of Rio de La plata and Paranapanema cratons during the Western Gondwana amalgamation  

NASA Astrophysics Data System (ADS)

The Mantiqueira Province represents a series of supracrustal segments of the South-American counterpart formed during the Gondwana Supercontinent agglutination. In this crustal domain, the process of escape tectonics played a conspicuous role, generating important NE-N-S-trending lineaments. The oblique component of the motions of the colliding tectonic blocks defined the transpressional character of the main suture zones: Lancinha-Itariri, Cubatão-Arcádia-Areal, Serrinha-Rio Palmital in the Ribeira Belt and Sierra Ballena-Major Gercino in the Dom Feliciano Belt. The process as a whole lasted for ca. 60 Ma, since the initial collision phase until the lateral escape phase predominantly marked by dextral and subordinate sinistral transpressional shear zones. In the Dom Feliciano Belt, southern Brazil and Uruguay, transpressional event at 630-600 Ma is recognized and in the Ribeira Belt, despite less coevally, the transpressional event occurred between 590 and 560 Ma in its northern-central portion and between ca. 625 and 595 Ma in its central-southern portion. The kinematics of several shear zones with simultaneous movement in opposite directions at their terminations is explained by the sinuosity of these lineaments in relation to a predominantly continuous westward compression.

Passarelli, C. R.; Basei, M. A. S.; Wemmer, K.; Siga, O.; Oyhantçabal, P.

2011-04-01

201

BASINS 2.0  

NSDL National Science Digital Library

The Environmental Protection Agency (EPA) first created BASINS (Better Assessment Science Integrating Point and Nonpoint Sources) in 1996 as an aid to water resource planners concerned with water quality and watershed analyses. The strength of BASINS is its integration of \\"a geographic information system (GIS), national watershed data, and state-of-the-art environmental assessment and modeling tools.\\" The updated version of the program, BASINS 2, can be downloaded from this site.

2005-11-01

202

BASINS 2.0  

NSDL National Science Digital Library

The Environmental Protection Agency (EPA) first created BASINS (Better Assessment Science Integrating Point and Nonpoint Sources) in 1996 as an aid to water resource planners concerned with water quality and watershed analyses. The strength of BASINS is its integration of "a geographic information system (GIS), national watershed data, and state-of-the-art environmental assessment and modeling tools." The updated version of the program, BASINS 2, can be downloaded from this site.

1998-01-01

203

Devonian shelf basin, Michigan basin, Alpena region  

SciTech Connect

This biostratigraphic study involves the Devonian paleogeography-paleoecology-paleobathymetry of the transition from carbonate platform shelf margin to basinal sedimentation for the northern part of the Michigan basin in the Alpena region. Shelf-basin analysis is based on lithofacies, rock colors, concretion, biostratigraphy, paleoecology of faunas - especially microfaunas and trace fossils - stratified water column, eustasy, and application of Walther's Law. Field observations were made on Partridge Point along Lake Huron, where type sections of the Middle Devonian Thunder Bay Limestone and Late Devonian Squaw Bay Limestone are exposed; and the Antrim black shale at Paxton quarry. The Thunder Bay Limestone evolved as a carbonate platform, subtidal shelf-margin aerobic environment dominated by sessile benthic coralline organisms and shelly fauna, but not reef framework. The Squaw Bay Limestone is transitional shelf to basin, with aspects of slope environment and deeper water off-platform, pelagic organic biostromal molluscan-conodont carbonate deposited during the onset of a stratified water column (dysaerobic benthos-polychaete. agglutinated tubes, sulfides) and pycnocline. The Antrim Shale, in an exceptional black shale exposure in the Paxton quarry, represents deep-water basinal deposition whose bottom waters lacked oxygen. Faunas (conodonts, styliolines, radiolarians) and floras (tasmanitids, calamitids, palynomorphs) are from the aerobic pelagic realm, as indicated from concretions and shale fossil evidence. A benthos is lacking, except for bioturbation from organisms introduced by entrained oxygenated distal turbidite dispersion into the barren bottom black muds. Basinal hydrocarbon source rocks are abundant and updip carbonate reservoirs rim the basin. The Antrim Shale sequence contains the interval of Frasnian-Famennian faunal extinction.

Gutschick, R.C.

1986-08-01

204

The Heidelberg Basin Drilling Project — basin analysis  

NASA Astrophysics Data System (ADS)

Within the context of the Heidelberg Basin Project (Gabriel et al. 2008), we present the first results of three-dimensional structural modelling of the basin, based on interpretation of reflection seismics and decompaction using porosity data measured from core material. Firstly, we interpreted six horizons (Base Quaternary, Internal and Base Pliocene, Base Upper Miocene, Internal and Base Mid Miocene Hydrobien beds) from all available industrial (ca. 100 km) and our own reflection seismic sections (ca. 15 km), which lie within a 8 km radius around the Heidelberg UniNord 1/2 boreholes. This data was used to construct a three-dimensional geometrical model of the Heidelberg Basin. Using 300 core samples, we determined the porosity of the Quaternary sediments and constructed an exponential porosity/depth relationship for these rocks, which were then attributed to the model. Lower strata were given values from the literature. The model shows that the Heidelberg basin has a N-S and E-W areal extent of only 10 × 6 km, directly abutting the eastern fault boundary of the Upper Rhine Graben. The strongest synsedimentary tectonic subsidence occurred during the Upper Miocene, Upper Pliocene, and Quarternary. Faults are not seen within the basin at this level, but a NW-SE striking strike-slip structure is recorded to the west of the basin. Furthermore, the sedimentary depocentre shifted 2 km northwards over time to the present location, directly below the city of Heidelberg. We determined that Quaternary sediments have porosities of over 60% at the surface, but at the Base Quaternary porosity is less than 35%. This strong decrease means that 740 m of sediments were compacted to produce the present ca. 500 m thickness of Quaternary strata. Gabriel, G., Ellwanger, D., Hoselmann, C. & Weidenfeller, M. (2008): The Heidelberg Basin Drilling Project. -- Quaternary Science Journal, 57, 3-4, 253-260.

Tanner, David C.; Martini, Nicole; Buness, Hermann; Gabriel, Gerald; Krawczyk, Charlotte M.

2010-05-01

205

K-Basins design guidelines.  

National Technical Information Service (NTIS)

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), remot...

N. R. Roe W. C. Mills

1995-01-01

206

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

207

Geysers: Lower Geyser Basin  

NSDL National Science Digital Library

This Yellowstone National Park web site is dedicated to Lower Geyser Basin. It includes images and descriptions of Queen's Laundry and Sentinel Meadows, Sentinel Cone, Ojo Caliente, Pocket Basin Mud Pots, Imperial Geyser, Spray Geyser, Octopus Spring, Great Fountain Geyser, White Dome Geyser, Pink Cone Geyser, Bead Geyser, Narcissus Geyser, Steady Geyser, Silex Spring, Fountain Paint Pot, Fountain Geyser, Clepsydra Geyser, and Jelly Geyser.

Park, Yellowstone N.

208

The Oquirrh basin revisited  

SciTech Connect

The upper Paleozoic succession in the Oquirrh basin in unusually thick, up to 9300 m, and consists mainly of a Pennsylvanian-middle Permian miogeocline of northwestern Utah. Previous workers have suggested a tectonic origin for the Oquirrh basin that is incompatible with the basin location in both time and space. There is no evidence for Pennsylvanian and Lower Permian tectonism in the middle of the miogeocline. Thermal evidence from the Mississippian Mission Canyon shale does no support the implied deep burial of the crustal sag models of basin formation. Stratigraphic and facies evidence indicates a growth fault origin for the basin. Regional isopach maps and facies maps are powerful tools in interpreting depositional environments and in reconstructing fold-and-thrust belts. However, the location of measured sections relative to the location of the growth fault basin. The Charleston-Nebo thrust may have essentially reversed the movement on a growth fault. Thick Oquirrh basin sedimentary rocks may not be required to balance structural sections across this thrust fault. A thin-skinned, extensional growth fault origin for the Oquirrh basin implies that the Cordilleran miogeocline did not participate in the Pennsylvanian north-vergent uplifts of the Ancestral Rocky Mountains.

Erskine, M.C.

1997-04-01

209

Characteristics of European basins  

Microsoft Academic Search

Hydrocarbon characteristics of some sedimentary basins in Europe are displayed by a series of transparent overlays. Combinations of these overlays provide rapid information on existing relationships among basin type, tectonic framework, exploratory effort, source and reservoir rocks, cumulative production, remaining recoverable reserves, and licensed areas as of January 1, 1988. Data were processed from Petroconsultants' data base and plotted on

B. M. Popescu; T. Orasianu

1988-01-01

210

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)...

211

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, Jeffrey S.

212

K Basin Hazard Analysis  

SciTech Connect

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

MCCALL, T.B.

2002-03-21

213

K Basins hazard analysis  

SciTech Connect

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

MCCALL, T.B.

2002-10-09

214

Moa's Ark or volant ghosts of Gondwana? Insights from nineteen years of ancient DNA research on the extinct moa (Aves: Dinornithiformes) of New Zealand.  

PubMed

The moa (Aves: Dinornithiformes) of New Zealand represent one of the extinct iconic taxa that define the field of ancient DNA (aDNA), and after almost two decades of genetic scrutiny of bones, feathers, coprolites, mummified tissue, eggshell, and sediments, our knowledge of these prehistoric giants has increased significantly. Thanks to molecular and morphological-based research, the insights that have been obtained into moa phylogenetics, phylogeography, and palaeobiology exceeds that of any other extinct taxon. This review documents the strengths of applying a multidisciplinary approach when studying extinct taxa but also shows that cross-disciplinary controversies still remain at the most fundamental levels, with highly conflicting interpretations derived from aDNA and morphology. Moa species diversity, for example, is still heavily debated, as well as their relationship with other ratites and the mode of radiation. In addition to increasing our knowledge on a lineage of extinct birds, further insights into these aspects can clarify some of the basal splits in avian evolution, and the evolutionary implications of the breakup of the prehistoric supercontinent Gondwana. Did a flightless moa ancestor drift away on proto New Zealand (Moa's Ark) or did a volant ancestor arrive by flight? Here we provide an overview of 19 years of aDNA research on moa, critically assess the attempts and controversies in placing the moa lineage among palaeognath birds, and discuss the factors that facilitated the extensive radiation of moa. Finally, we identify the most obvious gaps in the current knowledge to address the future potential research areas in moa genetics. PMID:21596537

Allentoft, Morten E; Rawlence, Nicolas J

2011-04-28

215

SAN JUAN BASIN PROVINCE (022)  

Microsoft Academic Search

Almost all hydrocarbon production and available subsurface data are restricted to the topographic San Juan Basin. Also included in the province, but separated from the structural and topographic San Juan Basin by the Hogback monocline and Archuleta arch, respectively, are the San Juan dome and Chama Basin, which contain sedimentary sequences similar to those of the San Juan Basin. In

A. Curtis Huffman

216

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

217

The Dahomey Basin  

Microsoft Academic Search

\\u000a The Dahomey Basin is a combination of inland \\/ coastal \\/ offshore basin that stretches from southeastern Ghana through Togo\\u000a and the Republic of Benin to southwestern Nigeria. It is separated from the Niger Delta by a subsurface basement high referred\\u000a to as the Okitipupa Ridge. Its offshore extent is poorly defined. Sediment deposition follows an east-west trend. In the

Nuhu Obaje

218

K Basin Hazard Analysis  

SciTech Connect

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

PECH, S.H.

2000-08-23

219

Permian basin gas production  

SciTech Connect

Of the 242 major gas fields in the Permian basin, 67 are on the Central Basin Platform, 59 are in the Delaware basin, 44 are in the Midland basin, 28 are in the Val Verde basin, 24 are on the Eastern Shelf, 12 are in the Horshoe Atoll and eight are on the Northwest Shelf. Eleven fields have produced over one trillion cubic feet of gas, 61 have produced between 100 billion and one trillion cubic feet of gas and 170 have produced less than 100 billion cubic feet. Highlights of the study show 11% of the gas comes from reservoirs with temperatures over 300 degrees F. and 11% comes from depths between 19,000 and 20,000 feet. Twenty percent of the gas comes from reservoirs with pressures between 1000 and 2000 psi, 22% comes from reservoirs with 20-24% water saturation and 24% comes from reservoirs between 125 and 150 feet thick. Fifty-three reservoirs in the Ellenburger formation have produced 30% of the gas, 33% comes from 88 reservoirs in the Delaware basin and 33% comes from reservoirs with porosities of less than five percent. Forty percent is solution gas and 46% comes from combination traps. Over 50% of the production comes from reservoirs with five millidarcys or less permeability, and 60% of the gas comes from reservoirs in which dolomite is the dominant lithology. Over 50% of the gas production comes from fields discovered before 1957 although 50% of the producing fields were not discovered until 1958.

Haeberle, F.R. [Consulting Geologist, Dallas, TX (United States)

1995-06-01

220

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

221

Geochemistry and zircon geochronology of the Permian A-type Hasanrobat granite, Sanandaj-Sirjan belt: A new record of the Gondwana break-up in Iran  

NASA Astrophysics Data System (ADS)

The Sanandaj-Sirjan metamorphic-plutonic Belt (SSB) in west central Iran is a polyphase metamorphic terrain composed of dominantly greenschist-grade metasedimentary and metavolcanic rocks, and felsic to mafic plutons, of Neoproterozoic-Phanerozoic ages. The Hasanrobat granite in central SSB occurs as a single pluton, ~ 20 km2 surface area, with relatively consistent mineralogy and chemistry. Quartz, alkali feldspars (microcline and perthite), sodic plagioclases and biotite are the main constituents, commonly associated with minor amphibole. Accessory phases include zircon, allanite, apatite, and magnetite.The country rocks are Upper Carboniferous-Lower Permian sandstones and dolomitic limestones. Scattered patches of skarn-type assemblages dominated by tremolite and talc occur in the dolomitic limestones, and sandstones are recrystallized to a coarse-grained quartzite at contact with the granite. The granite is metaluminous to slightly peraluminous, and is distinguished by high FeOt/MgO ratios, typical of ferroan (A-type) granites. The A-type affinity is also reflected by high Na2O + K2O, high Ga/Al ratios, high contents of large ion lithophile elements (LILE), high field strength elements (HFSE) and rare earth elements (REE), as well as low contents of Sr, and distinct negative Eu anomalies. The biotites are aluminous, Fe-rich, and plot near the siderophyllite corner in the quadrilateral biotite diagram. They are further distinguished by high fluorine contents (0.61 to 1.33 wt.%). Amphibole is ferrohastingsite in composition. Ion microprobe analyses of zircon grains separated from a representative granite sample yielded concordant U-Pb ages with weighted mean 206Pb/238U age of 288.3 ± 3.6 Ma.The granite and the country rocks are cut by a set of mafic dykes with asthenosphere-like geochemical signatures. Such association suggests anorogenic intraplate magmatism in Lower Permian in the region. This provides further evidence for, and significantly constrains timing of, a major extension in Upper Paleozoic in Iran, previously inferred from the rock record. The extension led to the Gondwana break-up and the opening of Neotethys Ocean between Sanandaj-Sirjan and Zagros in Permian.

Alirezaei, Saeed; Hassanzadeh, Jamshid

2012-10-01

222

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

223

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

EPA Science Inventory

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

224

Geology, exploration status of Uruguay's sedimentary basins  

SciTech Connect

This article attempts to present the geological characteristics and tectonic and sedimentary evolution of Uruguayan basins and the extent to which they have been explored. Uruguay is on the Atlantic coast of South America. The country covers about 318,000 sq km, including offshore and onshore territories corresponding to more than 65% of the various sedimentary basins. Four basins underlie the country: the Norte basin, the Santa Lucia basin, the offshore Punta del Este basin, and the offshore-onshore Pelotas-Merin basin. The Norte basin is a Paleozoic basin while the others are Mesozoic basins. Each basin has been explored to a different extent, as this paper explains.

Goso, C.; Santa Ana, H. de (Administracion Nacional de Combustibles, Alcohol y Portland (Uruguay))

1994-02-07

225

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

226

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

NASA Astrophysics Data System (ADS)

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

Bhattacharya, Biplab

2013-06-01

227

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

PubMed

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

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

2009-08-06

228

Provenance and basin evolution, Zhada basin, southwestern Tibet  

Microsoft Academic Search

The Zhada basin is a late Miocene - Pliocene intermontane basin situated at high elevations in the Himalayan hinterland. The fluvial and lacustrine sediments of the Zhada formation are undeformed and sit in angular unconformity above the deformed Tethyan Sedimentary Sequence (TSS). The basin sits just south of the Indus suture in a structural position occupied elsewhere in the Himalayan

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

2007-01-01

229

UNCOMPAHGRE RIVER BASIN SELENIUM PHYTOREMEDIATION  

EPA Science Inventory

The Uncompahgre River Basin Selenium Phytoremediation Project will evaluate the ability of selected agricultural crops and trees to accumulate and volatilize selenium from contaminated soils in the basin. Three different species of plants (two types will be campanion planted) an...

230

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

231

Oil in the Malvinas Basin  

Microsoft Academic Search

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

Galeazzi

1996-01-01

232

KE Basin Sludge Flocculant Testing  

Microsoft Academic Search

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

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

2004-01-01

233

Pacific basin energy  

SciTech Connect

Testimony is presented concerning pending legislation which provides for the assessment and development of the potential for renewable energy sources in the U.S. insular areas, including the trust territories. Options for self-sufficiency throughout the Pacific basin are considered in light of rapidly escalating fuel costs.

Not Available

1980-01-01

234

Williston basin Seislog study  

Microsoft Academic Search

This paper describes the results of Seislog (trade name) processing and interpretation of an east-west line in the North Dakota region of the Williston basin. Seislog processing involves inversion of the seismic trace data to produce a set of synthetic sonic logs. These resulting traces, which incorporate low-frequency velocity information, are displayed in terms of depth and isotransit times. These

Mummery

1985-01-01

235

ADVANCED CHEMISTRY BASINS MODEL  

Microsoft Academic Search

The advanced Chemistry Basin Model project has been operative for 48 months. During this period, about half the project tasks are on projected schedule. On average the project is somewhat behind schedule (90%). Unanticipated issues are causing model integration to take longer then scheduled, delaying final debugging and manual development. It is anticipated that a short extension will be required

William Goddard; Lawrence Cathles; Mario Blanco; Paul Manhardt; Peter Meulbroek; Yongchun Tang

2004-01-01

236

Global analysis of intraplate basins  

NASA Astrophysics Data System (ADS)

Broad intraplate sedimentary basins often show a mismatch of lithospheric extension factors compared to those inferred from sediment thickness and subsidence modelling, not conforming to the current understanding of rift basin evolution. Mostly, these basins are underlain by a very heterogeneous and structurally complex basement which has been formed as a product of Phanerozoic continent-continent or terrane/arc-continent collision and is usually referred to as being accretionary. Most likely, the basin-underlying substrate is one of the key factors controlling the style of extension. In order to investigate and model the geodynamic framework and mechanics controlling formation and evolution of these long-term depositional regions, we have been analysing a global set of more than 200 basins using various remotely sensed geophysical data sets and relational geospatial databases. We have compared elevation, crustal and sediment thickness, heatflow, crustal structure, basin ages and -geometries with computed differential beta, anomalous tectonic subsidence, and differential extension factor grids for these basins. The crust/mantle interactions in the basin regions are investigated using plate tectonic reconstructions in a mantle convection framework for the last 160 Ma. Characteristic parameters and patterns derived from this global analysis are then used to generate a classification scheme, to estimate the misfit between models derived from either crustal thinning or sediment thickness, and as input for extension models using particle-in-cell finite element codes. Basins with high differential extension values include the ``classical'' intraplate-basins, like the Michigan Basin in North America, the Zaire Basin in Africa, basins of the Arabian Penisula, and the West Siberian Basin. According to our global analysis so far, these basins show, that with increasing basin age, the amount of crustal extension vs. the extension values estimated from sediment thickness decreases decreased. This could be used as a indicator for ``basin maturity''. Furthermore, basins with higher differential beta values show generally slightly lower heatflux values. We have attempted to integrate the results from the observations with numerical modelling of different crustal extension scenarios involving a varying heterogeneous basement architecture and attempting to connect the ``pure'' numerical models with real world data as tightly as possible. In the scope of the project we have tried to build a numerical model library linked to the large scale observations, which offers a new powerful way to investigate the complex lithosphere dynamics and geological processes that account for the evolution of intraplate basins, and the influence of the basement architecture on successful or failed rifts.

Heine, C.; Mueller, D. R.; Dyksterhuis, S.

2005-12-01

237

Genetic diversity of hemoglobinopathies, G6PD deficiency, and ABO and Rhesus blood groups in two isolates of a primitive Kharia Tribe in Sundargarh District of Northwestern Orissa, India.  

PubMed

Tribal communities constitute about 8.2% of the total population of India. Their health needs are even larger than elsewhere in India; this study investigates the genetic diversity in relation to hemoglobinopathies, G6PD deficiency and, ABO and Rhesus (D) blood groups in two sects, i.e. Dudh (converted Christian) and Dhelki (Hinduised) Kharia, a primitive tribe in Sundargarh district of Orissa in Central-Eastern India. A randomized screening of 767 Kharia tribals (377 males and 390 females) belonging to all age groups and both sexes was done. Laboratory analysis was carried out following the standard methodology and techniques. Contrasting differences were observed in the frequency of hematological genetic disorders such as ?-thalassemia, sickle cell, hemoglobin E, G6PD deficiency, ABO and Rhesus (D) blood groups between the two subgroups. Dudh Kharia had no hemoglobin variant allele other than the high prevalence of ?-thalassemia trait (8.1%), whereas, their counterpart Dhelki Kharia had the high prevalence of sickle cell allele (12.4%), hemoglobin E allele (3.2%), and ?-thalassemia allele (4.0%). Frequency distribution of hemoglobin variants between Dudh and Dhelki Kharia tribe was statistically highly significant (p?

Balgir, R S

2010-09-01

238

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

239

ADVANCED CHEMISTRY BASINS MODEL  

SciTech Connect

The advanced Chemistry Basin Model project has been operative for 48 months. During this period, about half the project tasks are on projected schedule. On average the project is somewhat behind schedule (90%). Unanticipated issues are causing model integration to take longer then scheduled, delaying final debugging and manual development. It is anticipated that a short extension will be required to fulfill all contract obligations.

William Goddard III; Lawrence Cathles III; Mario Blanco; Paul Manhardt; Peter Meulbroek; Yongchun Tang

2004-05-01

240

Quantitative basin analysis methods and applications  

Microsoft Academic Search

Quantitative basin analysis has become increasingly important in petroleum exploration. Chapter 1 presents a quantitative basin analysis study from the Georges Bank Basin, East Coast of the USA. By applying a one-dimensional fluid flow\\/compaction model to the well data of the basin, the author obtains a quantitative understanding of the basin's geohistory, geothermal history, and hydrocarbon generation history so that

Jianchang

1990-01-01

241

Advanced Chemistry Basins Model  

SciTech Connect

The DOE-funded Advanced Chemistry Basin model project is intended to develop a public domain, user-friendly basin modeling software under PC or low end workstation environment that predicts hydrocarbon generation, expulsion, migration and chemistry. The main features of the software are that it will: (1) afford users the most flexible way to choose or enter kinetic parameters for different maturity indicators; (2) afford users the most flexible way to choose or enter compositional kinetic parameters to predict hydrocarbon composition (e.g., gas/oil ratio (GOR), wax content, API gravity, etc.) at different kerogen maturities; (3) calculate the chemistry, fluxes and physical properties of all hydrocarbon phases (gas, liquid and solid) along the primary and secondary migration pathways of the basin and predict the location and intensity of phase fractionation, mixing, gas washing, etc.; and (4) predict the location and intensity of de-asphaltene processes. The project has be operative for 36 months, and is on schedule for a successful completion at the end of FY 2003.

William Goddard; Mario Blanco; Lawrence Cathles; Paul Manhardt; Peter Meulbroek; Yongchun Tang

2002-11-10

242

Great Basin Paleontological Bibliography  

USGS Publications Warehouse

Introduction This work was conceived as a derivative product for 'The Metallogeny of the Great Basin' project of the Mineral Resources Program of the U.S. Geological Survey. In the course of preparing a fossil database for the Great Basin that could be accessed from the Internet, it was determined that a comprehensive paleontological bibliography must first be compiled, something that had not previously been done. This bibliography includes published papers and abstracts as well as unpublished theses and dissertations on fossils and stratigraphy in Nevada and adjoining portions of California and Utah. This bibliography is broken into first-order headings by geologic age, secondary headings by taxonomic group, followed by ancillary topics of interest to both paleontologists and stratigraphers; paleoecology, stratigraphy, sedimentary petrology, paleogeography, tectonics, and petroleum potential. References were derived from usage of Georef, consultation with numerous paleontologists and geologists working in the Great Basin, and literature currently on hand with the authors. As this is a Web-accessible bibliography, we hope to periodically update it with new citations or older references that we have missed during this compilation. Hence, the authors would be grateful to receive notice of any new or old papers that the readers think should be added. As a final note, we gratefully acknowledge the helpful reviews provided by A. Elizabeth J. Crafford (Anchorage, Alaska) and William R. Page (USGS, Denver, Colorado).

Blodgett, Robert B.; Zhang, Ning; Hofstra, Albert H.; Morrow, Jared R.

2007-01-01

243

New insights into the tectono-stratigraphic evolution of the Malvinas Basin, offshore of the southernmost Argentinean continental margin  

NASA Astrophysics Data System (ADS)

A detailed tectono-stratigraphic analysis of the Malvinas Basin was achieved by the interpretation of around 65,000 km of 2D seismic reflection profiles. Five main seismo-stratigraphic units and their sub-units, informally named units U1 to U5 a/b, bound by major unconformities were identified and correlated with the Mesozoic to Cenozoic main tectonic phases of the basin. Unit U1 (Pre-168 Ma) represents the seismic basement. Unit U2 (168-150.5 Ma, syn rift phase) thickens and deepens southwards. Units U1 and U2 are affected by several syn-rift normal faults that exhibit a main NE-SW strike direction in the south of the basin and a NW-SE strike direction in the centre of the basin. This suggests that the Malvinas Basin may have developed initially as a rift basin with two different extensional directions: (1) a NW-SE directed extension probably linked with the opening of the Weddell Sea (Early Mid-Jurassic), and (2) a NE-SW directed extension most likely linked with the Jurassic back-arc extension of Gondwana and probably later with the onset of the opening of the South Atlantic during Late Jurassic to Early Cretaceous time. Unit U3 (150.5-68 Ma, sag phase) is mainly an aggradational wedge-shaped unit. Unit U4 (68-42.5 Ma, transtensional foredeep phase) overlies unconformable unit U3. It deepens in the south because of an N-S/NW-SE directed extensional regime. Accumulation rates decrease during units U2, U3, and U4 from 4.84, to 1.23 to 0.8 km3/Ma × 103. Units U5a and U5b (42.5-5.5 and 5.5-0 Ma, transpressional foredeep phase) finally represent a change from aggradation to progradation sedimentary pattern and to a left-lateral transpressional regime in the south. The sediment supply was considerably higher than before and a thick sedimentary wedge has been deposited until today. Accumulations rates increased in units U5a and U5b from 2.28 to 8.91 km3/Ma × 103.

Baristeas, N.; Anka, Z.; di Primio, R.; Rodriguez, J. F.; Marchal, D.; Dominguez, F.

2013-09-01

244

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

245

Experimental Drainage Basins in Israel  

Microsoft Academic Search

Within the hyper-arid to semiarid areas of Israel are three experimental drainage basins. They are the Nahal (stream in Hebrew) Yael, subdivided into five sub-basins, Rahaf-Qanna'im (main and tributary, respectively) and Eshtemoa. These basins vary in drainage area and climate, and in monitoring duration and type. All are drained by gravel-bed channels. As the size of monitored drainage area is

J. B. Laronne; J. Lekach; H. Cohen; J. Gray

2002-01-01

246

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

247

Depositional environments of the lower Permian Dwyka diamictite and Prince Albert shale inferred from the geochemistry of early diagenetic concretions, southwest Karoo Basin, South Africa  

NASA Astrophysics Data System (ADS)

The upper Dwyka and lower Ecca Groups in the Karoo Basin of South Africa document the climatic and palaeoenvironmental changes associated with the final Permo-Carboniferous deglaciation of the Gondwana supercontinent. The depositional environments of these groups have, until recently, been interpreted on the basis of sedimentological and palaeontological evidence. Here we use the geochemistry of early diagenetic concretions septarian calcite concretions from the upper Dwyka Group and phosphatic chert concretions and beds from the lower Ecca Group to infer the depositional environment of these rocks in the southwestern Karoo Basin. ?18O values (7.8 to 8.9‰ SMOW) suggest that the calcite concretions precipitated from a mixture of meteoric and glacial melt waters rather than Permian seawater. ?13C values (- 15 to - 3‰ PDB) indicate that the carbon was derived from a mixture of craton-derived calcareous material and organic matter, bacterially degraded in the lower sulphate-reduction to upper methanogenesis zones during early burial diagenesis. The rare-earth element (REE) patterns, Sr concentrations and 87Sr/86Sr ratios (0.716 0.737) significantly greater than Permian seawater (0.708), together also support the interpretation that calcite and phosphatic concretions formed in glacial, fresh water sediments.

Herbert, C. T.; Compton, J. S.

2007-02-01

248

Great Basin paleontological database  

USGS Publications Warehouse

The U.S. Geological Survey has constructed a paleontological database for the Great Basin physiographic province that can be served over the World Wide Web for data entry, queries, displays, and retrievals. It is similar to the web-database solution that we constructed for Alaskan paleontological data (www.alaskafossil.org). The first phase of this effort was to compile a paleontological bibliography for Nevada and portions of adjacent states in the Great Basin that has recently been completed. In addition, we are also compiling paleontological reports (Known as E&R reports) of the U.S. Geological Survey, which are another extensive source of l,egacy data for this region. Initial population of the database benefited from a recently published conodont data set and is otherwise focused on Devonian and Mississippian localities because strata of this age host important sedimentary exhalative (sedex) Au, Zn, and barite resources and enormons Carlin-type An deposits. In addition, these strata are the most important petroleum source rocks in the region, and record the transition from extension to contraction associated with the Antler orogeny, the Alamo meteorite impact, and biotic crises associated with global oceanic anoxic events. The finished product will provide an invaluable tool for future geologic mapping, paleontological research, and mineral resource investigations in the Great Basin, making paleontological data acquired over nearly the past 150 yr readily available over the World Wide Web. A description of the structure of the database and the web interface developed for this effort are provided herein. This database is being used ws a model for a National Paleontological Database (which we am currently developing for the U.S. Geological Survey) as well as for other paleontological databases now being developed in other parts of the globe. ?? 2008 Geological Society of America.

Zhang, N.; Blodgett, R. B.; Hofstra, A. H.

2008-01-01

249

MASSACHUSETTS DRAINAGE SUB-BASINS  

EPA Science Inventory

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

250

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

251

Estancia Basin dynamic water budget.  

SciTech Connect

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

Thomas, Richard P.

2004-09-01

252

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

253

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

254

Flexural Origin of the Puget Basins: Implications for the Seattle Fault and Puget Basin Tectonics  

Microsoft Academic Search

At least five distinct basins of varying depth, including the Seattle basin, form a semi-circular ring around the eastern Olympic Mts. Although the Seattle basin has been postulated to result from a northward vergent thrust on the Seattle fault, other basins have a less clear relationship to faulting. A purely thrust origin for the Seattle basin requires uplift, which is

R. S. Crosson; N. P. Symons

2001-01-01

255

Island Biogeography of Native Fish Faunas among Great Plains Drainage Basins: Basin Scale Features Influence Composition  

Microsoft Academic Search

We reviewed native fish zoogeography in 22 major tributary basins of the Missouri River basin in the Great Plains geomorphic province and used island biogeographical ap- proaches to study the influence of basin area and isolation on faunal composition. Basin area was correlated with elevation range and basin isolation was negatively correlated with annual freeze-free days. Ninety-six species were native

Christopher W. Hoagstrom; Charles R. Berry

2006-01-01

256

The Western Irish Namurian Basin reassessed  

Microsoft Academic Search

Current basin models for the Western Irish Namurian Basin (WINB) envisage an elongate trough along the line of the present-day Shannon Estuary that was infilled with clastic sediments derived from a hinterland that lay to the W or NW. This paper argues for an alternative basin configuration with source areas to the SW supplying sediment to a basin where deepest

P. B. Wignall; J. L. Best

2000-01-01

257

The crustal structure of lunar impact basins  

Microsoft Academic Search

The topography and crustal structure of the Moon are dominated by the signatures of impact basins, yet the process of basin formation and modification remains poorly understood. The subsurface structure of the basins provides an important constraint on the basin formation process. Models of the relief along the crust-mantle interface, or Moho, and the resulting crustal thickness can be generated

J. C. Andrews-Hanna; R. A. Krahenbuhl

2010-01-01

258

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

259

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

2012-01-18

260

Geology of promising Holbrook Basin  

SciTech Connect

Lying across east central Arizona and west central New Mexico, the 200-mile-long, 100-mile-wide Holbrook basin is truly sedimentary, expressed in subsurface Permian rocks. Triassic redbeds and Permian limestones and sandstones form much of the basin's surface, with the Permian system holding the most promise of commercial hydrocarbon reserves. The Permian's Supai formation contains gypsum, anhydrite, and salt, along with interbedded limestone and dolomite and thick zones of red sandstone, siltstone, and shale. The Fort Apache dolomite member of the Supai is one of the prime target zones for hydrocarbon development, though the entire basin offers some excellent wildcatting opportunities.

Heylmun, E.B.

1980-01-05

261

Basin development and petroleum potential of offshore Otway basin, Australia  

SciTech Connect

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

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

1987-05-01

262

Basin bifurcation in quasiperiodically forced systems  

NASA Astrophysics Data System (ADS)

In this paper we study quasiperiodically forced systems exhibiting fractal and Wada basin boundaries. Specifically, by utilizing a class of representative systems, we analyze the dynamical origin of such basin boundaries and we characterize them. Furthermore, we find that basin boundaries in a quasiperiodically driven system can undergo a unique type of bifurcation in which isolated ``islands'' of basins of attraction are created as a system parameter changes. The mechanism for this type of basin boundary bifurcation is elucidated.

Feudel, Ulrike; Witt, Annette; Lai, Ying-Cheng; Grebogi, Celso

1998-09-01

263

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

264

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.

2013-07-01

265

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

266

Principles of Sedimentary Basin Analysis  

NASA Astrophysics Data System (ADS)

Basin analysis is the ultimate act of synthesis in stratigraphy. Its objective is to weave together the diverse strands of information in order to portray the tectonic evolution of a basin, its filling with sediments in a broad range of depositional environments, the subsequent diagenesis and lithification of these sediments, and the localization therein of mineral and petroleum resources. Thus, although the primary emphasis in basin analysis is stratigraphic and sedimentologic in nature, paleontologic, tectonic, and geophysical data, among others, are also integral components of the effort. It is scientifically challenging and, in practical terms, forms the foundation for the exploration for strata-bound resources. The wide range of topics that must be incorporated into a basin analysis requires that it be a group project of specialists and means that it is a difficult subject to teach or to present in a book.

Stanton, Robert J., Jr.

267

Geology of promising Holbrook Basin  

Microsoft Academic Search

Lying across east central Arizona and west central New Mexico, the 200-mile-long, 100-mile-wide Holbrook basin is truly sedimentary, expressed in subsurface Permian rocks. Triassic redbeds and Permian limestones and sandstones form much of the basin's surface, with the Permian system holding the most promise of commercial hydrocarbon reserves. The Permian's Supai formation contains gypsum, anhydrite, and salt, along with interbedded

Heylmun

1980-01-01

268

Provenance and basin evolution, Zhada basin, southwestern Tibet  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

269

Paleothermometry of the Sydney Basin  

SciTech Connect

Evidence from overprinting of magnetizations of Late Permian and Mesozoic rocks and from the rank of Permian coals and Mesozoic phytoclasts (coal particles) suggests that surface rocks in the Sydney Basin, eastern Australia, have been raised to temperatures of the order of 200 /sup 0/C or higher. As vitrinite reflectance, an index of coal rank or coalification, is postulated to vary predictably with temperature and time, estimates of the paleotemperatures in the Sydney Basin based on observed vitrinite reflectance measurements can be made in conjunction with reasonable assumptions about the tectonic and thermal histories of the basin. These estimates give maximum paleotemperatures of present day surface rocks in the range 60--249 /sup 0/C, depending on factors such as location in the basin, the thickness of the sediment eroded, and the maximum paleogeothermal gradient. Higher coal rank and, consequently, larger eroded thicknesses and paleogeothermal gradients occur along the eastern edge of the basin and may be related to seafloor spreading in the Tasman Sea on the basin's eastern margin. A theory of thermal activation of magnetization entailing the dependence of magnetic viscosity on the size distribution of the magnetic grains is used to obtain an independent estimate of the maximum paleotemperatures in the Sydney Basin. This estimate places the maximum paleotemperature in the range 250--300 /sup 0/C along the coastal region. Both coalification and thermal activation of magnetization models provide strong evidence of elevated paleotemperatures, which in places exceed 200 /sup 0/C, and the loss of sediment thicknesses in excess of 1 km due to erosion.

Middleton, M.F.; Schmidt, P.W.

1982-07-10

270

Exploratory Shaft Facility Preliminary Designs - Permian Basin.  

National Technical Information Service (NTIS)

The purpose of the Preliminary Design Report, Permian Basin, is to provide a description of the preliminary design for an Exploratory Shaft Facility in the Permian Basin, Texas. This issue of the report describes the preliminary design for constructing th...

1983-01-01

271

Climatic Atlas of the Delaware River Basin.  

National Technical Information Service (NTIS)

The Delaware River basin is a diverse physiographic, hydrologic, and climatic region. The Delaware River serves as a major source of water for nearly 20 million people both in and outside the basin. Questions associated outside the variability of climate,...

C. B. Jenner H. F. Lins

1991-01-01

272

Muskingum River Basin Comprehensive Coordinated Joint Plan.  

National Technical Information Service (NTIS)

The plan includes recommended studies, projects, and non-structural programs which the Ohio River Basin Commission has agreed are required to meet the economic, environmental and social needs of the sub-basin, the Muskingum River.

1976-01-01

273

Structure of the Western Somali Basin.  

National Technical Information Service (NTIS)

The western Somali Basin in the northwestern Indian Ocean is covered by thick deposits of terrigenous sediments. Seismic reflection profiles show, however, the northern and southern parts to be very different. The northern sections is a deep basin filled ...

E. T. Bunce M. G. Langseth R. L. Chase M. Ewing

1966-01-01

274

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

Microsoft Academic Search

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

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

1990-01-01

275

Tectonic loading and subsidence of intermontane basins: Wyoming foreland province  

Microsoft Academic Search

Results of two-dimensional flexural modeling of the northern Bighorn and northern Green River basins in the Wyoming foreland province suggest that these basins formed as flexures in response to loading by basin-margin uplifts and basin sedimentary sequences. The northern Bighorn Basin subsided due to loading by the Beartooth uplift along its western margin. The northern Green River Basin developed as

E. Sven Hagen; Mark W. Shuster; Kevin P. Furlong

1985-01-01

276

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

277

Waste oil basins: Environmental information document  

Microsoft Academic Search

The Motor Shop Oil Basin, located in A Area at the Savannah River Plant (SRP), was constructed and placed in service in 1977 to receive liquid waste from the 716-A Motor Shop oil\\/water separator. The liquid wastes seeped naturally into the soil beneath the basin. In August 1983, all discharges to the oil basin were terminated. The D-Area Oil Basin

L. A. Huber; W. F. Johnson; H. W. Bledsoe

1987-01-01

278

The Jordan Basin: Evolution of the Rules  

Microsoft Academic Search

The Jordan River basin extends from the slopes of Mount Hermon to the Dead Sea. Israel, Jordan, Lebanon, the Palestinians,\\u000a and Syria are riparian to the Jordan River or its tributaries. Most plans for the basin waters were based on treating the\\u000a basin as an integral whole, although no basin-wide agreement has been reached. The determination of political borders sometimes

Robbie Sabel

279

Stochastic Basin for Comprehensive River Basin Planning. Phase I.  

National Technical Information Service (NTIS)

Results are given from Phase I of a study of the application of stochastic systems analysis to water resources problems. An extensive digital computer program was written to simulate the dissolved oxygen-biochemical demand dynamics in a river basin. The u...

F. G. Haag K. W. Bedford J. W. Fischetti J. D. Lloyd

1969-01-01

280

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

281

The Anadarko: Two basins, not one  

SciTech Connect

Located at the core of the Sooner Trend on the northeast shelf of the Anadarko Basin is the Enid Embayment. Using regional mapping and production trends it is possible to expand the idea of an Enid Embayment to a concept of two basins, a northern shallow basin and the main basin to the south. From a terminology point of view, it would also be appropriate to map a single basin with a northwest trending arch cutting across the shelf of that basin. The evidence for this concept is most pronounced in the Pennsylvanian producing trends by can also be inferred as early as Siluro-Devonian Hunton time. There also clearly exists the presence of a through going linear on the Landsat interpreted data suggesting the existence of a deep seated, basement fault system underlying the arch which separates the two basin axes. Shoreline trends in the northern basin are very pronounced because the basin was very shallow, and the shelf edges were very low dip. Therefore, small changes in sea level caused large movements in shoreline locations. The mapping of shoreline locations through time in the shallow basin can produce a better understanding of shoreline deposits in the deep basin and assist in the understanding of producing fairways and their potential extensions. Although the concept is not new, the recognition and interpretation of two basin concept can be of assistance in exploring for, and finding, the more elusive fields that remain in this mature area.

Evans, J.L. [Ward Petroleum Corp., Enid, OK (United States)

1995-09-01

282

Geology of the Wiso Basin Northern Territory.  

National Technical Information Service (NTIS)

The Wiso Basin contains a sequence of near-horizontal Middle Cambrain to upper Palaeozoic sedimentary rocks. It is continuous with the Daly River Basin to the north, and with the Georgina Basin to the northeast and possibly the southeast. Most of the basi...

P. J. Kennewell M. B. Huleatt G. M. Bladon

1980-01-01

283

GUNNISON RIVER (COLORADO) BASIN SELENIUM TARGETING  

EPA Science Inventory

The Gunnison and Uncompahgre River Basins Targeting Project will gather water quality data necessary to characterize the selenium loads that are being contributed from within the basins. Evaluation of the variabiliy of selenium loading in the basins will guide the implementation...

284

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...

285

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...

286

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

287

New bifurcations of basin boundaries involving Wada and a smooth Wada basin boundary  

NASA Astrophysics Data System (ADS)

This paper demonstrates and analyses double heteroclinic tangency in a three-well potential model, which can produce three new types of bifurcations of basin boundaries including from smooth to Wada basin boundaries, from fractal to Wada basin boundaries in which no changes of accessible periodic orbits happen, and from Wada to Wada basin boundaries. In a model of mechanical oscillator, it shows that a Wada basin boundary can be smooth.

Zou, Hai-Lin; Xu, Jian-Xue; Jiang, Jun

2008-01-01

288

A Plume Head and Tail in the Bengal Basin and Bay of Bengal: Rajmahal and Sylhet Traps with Surrounding Alkalic Volcanism and the Ninetyeast Ridge  

NASA Astrophysics Data System (ADS)

Although the 116-113 Ma-old Rajmahal-Sylhet Traps of the Bengal basin, potentially covering an area > 2x105 km2, can be directly linked via Ninetyeast Ridge to the Kerguelen Plume, more than 5,000 kms away, it is generally believed that this flood basalt volcanism originated from a normal MORB-type mantle at the boundary of a mantle plume. This model, primarily based on geochemical analysis of a limited number of Rajmahal basalts, requires initiation of rifting of the eastern Indian margin by a smaller thermal flux than necessary for creating a large igneous province. Here we show that the extent of volcanism associated with the Rajmahal-Sylhet Traps is far greater than usually assumed, thus requiring a direct involvement of the Kerguelen Plume. In addition to the surface exposures of the flood basalts in Rajmahal-Sylhet, the basaltic rocks have been encountered in many parts of the Bengal Basin in bore holes reaching a maximum thickness of 600 m in the western margin of the Basin (Sengupta, Bull. AAPG, 1966) Most importantly, several suites of ultrapotassic and alkalic intrusive complexes, similar to those associated with the Deccan and Siberia Traps, occur over wide areas within and outside the Basin: i) southwest of the surface exposures of Rajmahal basalts, distance 200km, intrusive in Lower Gondwana coalbeds, Ar-Ar age 114 Ma (P.R. Renne, personal communication), ii) 400 km north of Rajmahal, exposed in Sikkim, intrusive into metamorphic crystalline nappes of the Himalayas; distance here is not real and must be a minimum as the nappes have been transported from the north, iii) northeast of Rajmahal in Meghalaya State, distance 550 km, intrusive into metamorphic Precambrian basement rocks. Nd-Sr isotopic ratios and trace element characteristics of these above ultrapotassic and alkaline rocks are consistent with their origin associated with the Kerguelen Plume. The wide range in Nd-Sr array for these rocks, including the Sylhet and Rajmahal basalts, shows initial \\epsilonNd(T) values of +4 to -8 and 87Sr/86Sr of 0.7045 to 0.7100, which are similar to Kerguelen transitional and alkaline basalts, Bunburry Gosselin lavas and Naturaliste plateau basalts. Therefore, the zone of influence of the plume head with Rajmahal at the center would be at least 700 km in diameter, and such a large area would require direct involvement of the Kerguelen Plume head for magma genesis in the Bengal basin. Recognition of associated volcanism in the northeast of Sylhet Traps allows Nintyeast Ridge to be the appropriate hotspot track in the Bay of Bengal.

Basu, A. R.; Weaver, K. L.; Sengupta, S.

2001-12-01

289

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

290

{Hydrological Trend in Different Basins in China}  

NASA Astrophysics Data System (ADS)

Hydrological cycle has been highly influenced by climate change and human activities and it is significant for analyzing the hydrological trends that occurred in past decades in order to understand past changes and predict future trends. Precipitation, runoff and evaporation are the three main processes in the hydrological cycle. The trends of precipitation and runoff in a basin can be analyzed with observation data and the actual evaporation can be simulated with water balance if the water storage change is known. Lots of observations show that the rate of evaporation from open pans of water has been steadily decreasing all over the world over the past 50 years but the trend of actual evaporation is not clear. The relations between actual evaporation and potential evaporation can be described by the Budyko curve with a complementary relation. The whole China are divided into ten basins, including Songhua River Basin, Liaohe River Basin, Haihe River Basin, Yellow River Basin, Huaihe River Basin, Yangtze River Basin, Pearl River Basin, Southeast Basin, Southwest Basin and Northwest Basin. With the weather data and hydrological data from 1956 to 2005, the hydrological trends and the Budyko curve are discussed in different basins. For the Yellow River Basin, we found that the actual evaporation decreased and the runoff decreased with the decreasing in precipitation and the decreasing in potential evaporation in the past 50 years. For the Yangtze River Basin, we found that the actual evaporation decreased and the runoff increased with the increasing in precipitation and the decreasing in potential evaporation in the past 50 years. The different hydrological trends are explained with the Budyko curve.

Cong, Z.; Zhao, J.; Yang, D.

2009-04-01

291

Umatilla Basin Habitat Improvement Project  

Microsoft Academic Search

This annual report is in fulfillment of contract obligations with Bonneville Power Administration which is the funding source for the Oregon Department of Fish and Wildlife's Umatilla Basin Habitat Improvement Project. The major activities undertaken during this report period were: procurement of 17 cooperative lease agreements with private landowners, design and layout of 8.6 miles of riparian exclosure fence and

Bailey; Timothy D

1990-01-01

292

Brownsville, Washington. Small Boat Basin.  

National Technical Information Service (NTIS)

The project involves construction of 1,530 feet of breakwaters, an entrance channel, an access channel and a turning basin for small boats on Puget Sound at Brownsville, Kitsap County, Washington. Shellfish production on the 2-1/2 acres under the breakwat...

1971-01-01

293

Meeteetse field, Bighorn basin, Wyoming  

Microsoft Academic Search

Lower Cretaceous Muddy and Upper Cretaceous Frontier sandstone reservoirs remain popular objectives for new energy reserves in the Bighorn basin of northwestern Wyoming. Predominantly structural reserves approximate 1 million bbl of oil and 20 bcf of gas from six Muddy fields, and 210 million bbl of oil and 100 bcf of gas from 16 Frontier fields. Newly established structural-stratigraphic gas

R. Wolff; R. Roy

1984-01-01

294

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

295

Reactivation of tectonics, crustal underplating, and uplift after 60 Myr of passive subsidence, Raukumara Basin, Hikurangi-Kermadec fore arc, New Zealand: Implications for global growth and recycling of continents  

NASA Astrophysics Data System (ADS)

We use seismic reflection and refraction data to determine crustal structure, to map a fore-arc basin containing 12 km of sediment, and to image the subduction thrust at 35 km depth. Seismic reflection megasequences within the basin are correlated with onshore geology: megasequence X, Late Cretaceous and Paleogene marine passive margin sediments; megasequence Y, a ˜10,000 km3 submarine landslide emplaced during subduction initiation at 22 Ma; and megasequence Z, a Neogene subduction margin megasequence. The Moho lies at 17 km beneath the basin center and at 35 km at the southern margin. Beneath the western basin margin, we interpret reflective units as deformed Gondwana fore-arc sediment that was thrust in Cretaceous time over oceanic crust 7 km thick. Raukumara Basin has normal faults at its western margin and is uplifted along its eastern and southern margins. Raukumara Basin represents a rigid fore-arc block >150 km long, which contrasts with widespread faulting and large Neogene vertical axis rotations farther south. Taper of the western edge of allochthonous unit Y and westward thickening and downlap of immediately overlying strata suggest westward or northwestward paleoslope and emplacement direction rather than southwestward, as proposed for the correlative onshore allochthon. Spatial correlation between rock uplift of the eastern and southern basin margins with the intersection between Moho and subduction thrust leads us to suggest that crustal underplating is modulated by fore-arc crustal thickness. The trench slope has many small extensional faults and lacks coherent internal reflections, suggesting collapse of indurated rock, rather than accretion of >1 km of sediment from the downgoing plate. The lack of volcanic intrusion east of the active arc, and stratigraphic evidence for the broadening of East Cape Ridge with time, suggests net fore-arc accretion since 22 Ma. We propose a cyclical fore-arc kinematic: rock moves down a subduction channel to near the base of the crust, where underplating drives rock uplift, oversteepens the trench slope, and causes collapse toward the trench and subduction channel. Cyclical rock particle paths led to persistent trench slope subsidence during net accretion. Existing global estimates of fore-arc loss are systematically too high because they assume vertical particle paths.

Sutherland, Rupert; Stagpoole, Vaughan; Uruski, Christopher; Kennedy, Callum; Bassett, Daniel; Henrys, Stuart; Scherwath, Martin; Kopp, Heidrun; Field, Brad; Toulmin, Suzannah; Barker, Daniel; Bannister, Stephen; Davey, Fred; Stern, Timothy; Flueh, Ernst R.

2009-10-01

296

Provenance of eastern Magallanes foreland basin sediments: Mineralogical and geochemical analyses reveal Paleogene tectonic unroofing of the Fuegian Andes  

NASA Astrophysics Data System (ADS)

Though southern South America and the Antarctic Peninsula were previously connected through a Paleozoic-Mesozoic subduction system on the western margin of Gondwana, this connection was tectonically disrupted in the Cenozoic by forming the Drake Passage in the Scotia Sea. Heavy mineral composition data from the eastern Magallanes basin of southernmost South America indicate that Campanian to middle Eocene sediments had a mafic/ophiolitic provenance which is interpreted as being derived from the Patagonian-Fuegian magmatic arc and the mafic floor of the preceding Rocas Verdes marginal basin. Upper middle Eocene to lower Miocene heavy minerals, on the other hand, indicate a metamorphic/metasedimentary provenance, which suggest being derived from the Cordillera Darwin metamorphic complex. While the rare earth element patterns of all of these samples are typical to those of average post-Archean upper continental crustal types, the younger middle-upper Eocene and lower Oligocene samples contain a higher concentration of the light REEs (LaN/SmN) ratio compared to the older upper Cretaceous to middle Eocene samples suggesting an eastern Andean metamorphic complex provenance for younger sediments. Trace elements plot of stratigraphically older samples exhibit a lower Th/Sc ratio compared to the younger samples suggesting a mafic origin. Nd isotope data show a shift in epsilonNd values from a less negative to a more negative value also during the middle to late Eocene. Together, these data indicate an abrupt shift in sediment provenance in middle to late Eocene time, thereby corroborating recent interpretations of the basin's detrital-zircon geochrononology and thermochronology, and providing further support for temporal and possibly genetic relationships between development of the Patagonian orocline, the opening of Drake Passage and the Oi-1 glaciation of Antarctica. Quantifying the relative abundance of different framework mineral components of sandstone is a common practice in the determination of sedimentary provenance. This study describes a Microsoft Excel-based method of constructing sandstone provenance and classification related ternary diagrams. The technique demonstrated in this chapter stores sandstone point-count data, generate ternary diagrams with provenance and classification related internal fields, and generate publication-quality scientific diagrams, all in a single step only requiring widely available programs such as Microsoft Excel.

Zahid, Khandaker

297

Mississippian facies relationships, eastern Anadarko basin, Oklahoma  

SciTech Connect

Mississippian strata in the eastern Anadarko basin record a gradual deepening of the basin. Late and post-Mississippian tectonism (Wichita and Arbuckle orogenies) fragmented the single large basin into the series of paired basins and uplifts recognized in the southern half of Oklahoma today. Lower Mississippian isopach and facies trends (Sycamore and Caney Formations) indicate that basinal strike in the study area (southeastern Anadarko basin) was predominantly east-west. Depositional environment interpretations made for Lower Mississippian strata suggest that the basin was partially sediment starved and exhibited a low shelf-to-basin gradient. Upper Mississippian isopach and facies trends suggest that basinal strike within the study area shifted from dominantly east-west to dominantly northwest-southeast due to Late Mississippian and Early Pennsylvanian uplift along the Nemaha ridge. Within the study area, the Chester Formation, composed of gray to dove-gray shales with interbedded limestones deposited on a carbonate shelf, thins depositionally into the basin and is thinnest at its facies boundary with the Springer Group and the upper portion of the Caney Formation. As basin subsidence rates accelerated, the southern edge of the Chester carbonate shelf was progressively drowned, causing a backstepping of the Chester Formation calcareous shale and carbonate facies. Springer Group sands and black shales transgressed northward over the drowned Chester Formation shelf.

Peace, H.W. (Oryx Energy, Inc., Midland, TX (United States)); Forgotson, J.M. (Univ. of Oklahoma, Norman (United States))

1991-08-01

298

Hydrocarbon accumulations in the Tarim basin, China  

SciTech Connect

The Tarim basin is the largest and least explored inland basin in China. The areal extent of the basin reaches 560,000 km{sup 2}. The interior of the basin is mostly covered by the Takla Mekan Desert, which is about 330,000 km{sup 2} in areal extent. The basin has become the object of special attention since China set aside first- and third-round onshore bidding blocks in the Tarim basin for foreign oil firms to explore. The Tarim basin is a polyhistory superimposed basin that has experienced seven evolutionary stages: (1) Sinian-Cambrian-Ordovician aulacogen stage, (2) Silurian-Devonian intracratonic depression stage, (3) Carboniferous marginal sea stage, (4) Permian rift basin stage, (5) Triassic-Jurassic foreland basin stage, (6) Cretaceous-Paleogene NeoTethys bay stage, and (7) Neogene-Pleistocene foreland and inland basin stage. Both the basin`s Paleozoic marine platform sequences and the Mesozoic-Cenozoic terrestrial fills are believed to contain substantial volumes of hydrocarbons. After recent years of exploration, nine oil and gas fields have been proven and 23 discoveries have been made in the Tabei, Tazhong, and Southwest areas. Kekeya, Lunnan, Sangtamu, Jiefangqudong, Donghetang, and Tazhong 4 oil fields have been put into production. Output of crude oil was 2.6 million t (metric tons) (52,000 BOPD) in 1995. The production will increase to 5 million t (100,000 BOPD) in 1997. Giant oil and gas traps probably will be discovered in the Tarim basin. The prospect is promising.

Li Desheng [Research Institute of Petroleum Exploration and Development, Beijing (China); Liang Digang; Jia Chengzao; Wang Gang [Tarim Petroleum Exploration and Development Bureau, Korle (China)] [and others

1996-10-01

299

Petroleum geology and exploration potential of Oriente-Maranon Basin  

Microsoft Academic Search

Oriente-Maranon Basin is one of the Sub-Andean foreland basins developed and formed on the basis of Margin of Craton. Oriente-Maranon Basin went through three evolution phases: marginal basin of craton, rift basin and foreland basin. The phase of rift basin formed the primary source rocks and reservoir and seal. Triassic-Jurassic Pucara Group and Cretaceous Chonta Formation generated a mass of

Xie Yinfu; Jihancheng; Su Yongdi; Hu Ying

2010-01-01

300

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

301

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

302

Life span and fate of basins  

NASA Astrophysics Data System (ADS)

The life span of each main class of sedimentary basin is estimated from published data. Life spans vary over at least three orders of magnitude, from <1 m.y. for trench basins to >100 m.y. for passive-margin and intracratonic basins. The life-span estimates are used to calibrate a chart of basin groups that focuses on the likely basin fates; i.e., depositional, deformational, or thermal. Consequent fates, predetermined by the tectonic setting of a particular basin class, are distinguished from contingent fates, which are independent of basin type. Accretion of trench-basin fill is, for example, a consequent fate, whereas inversion (far-field shortening) of a rift basin is a contingent fate. Life-span data are also used to calibrate the Wilson Cycle and indicate that it has an average duration of ˜260 m.y. This is certainly an underestimate, because basin life spans are an imperfect proxy for the duration of subduction and collision zones.

Woodcock, Nigel H.

2004-08-01

303

Environmental change in the Mississippi River Basin  

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

304

Geology of interior cratonic sag basins  

SciTech Connect

Interior cratonic sag basins are thick accumulations of sediment, generally more or less oval in shape, located entirely in the interiors of continental masses. Some are single-cycle basins and others are characterized by repeated sag cycles or are complex polyhistory basins. Many appear to have developed over ancient rift systems. Interior cratonic sag basins are typified by a dominance of flexural over fault-controlled subsidence, and a low ratio of sediment volume to surface area of the basin. The Baltic, Carpentaria, Illinois, Michigan, Parana, Paris, and Williston basins are examples of interior cratonic sag basins. Tectonics played a dominant role in controlling the shapes and the geometries of the juxtaposed packets of sedimentary sequences. While the mechanics of tectonic control are not clear, evidence suggests that the movements are apparently related to convergence of lithospheric plates and collision and breakup of continents. Whatever the cause, tectonic movements controlled the freeboard of continents, altering base level and initiating new tectono-sedimentologic regimes. Sag basins situated in low latitudes during their development commonly were sites of thick carbonates (e.g., Illinois, Michigan, Williston, and Paris basins). In contrast, siliciclastic sedimentation characterized basins that formed in higher latitudes (e.g., Parana and Carpentaria basins). Highly productive sag basins are characterized by widespread, mature, organic-rich source rocks, large structures, and good seals. Nonproductive basins have one or more of the following characteristics: immature source rocks, leaky plumbing, freshwater flushing, and/or complex geology due to numerous intrusions that inhibit mapping of plays.

Leighton, M.W.; Eidel, J.J.; Kolata, D.R.; Oltz, D.F. (Illinois Geological Survey, Champaign (USA))

1990-05-01

305

Experimental Drainage Basins in Israel  

NASA Astrophysics Data System (ADS)

Within the hyper-arid to semiarid areas of Israel are three experimental drainage basins. They are the Nahal (stream in Hebrew) Yael, subdivided into five sub-basins, Rahaf-Qanna'im (main and tributary, respectively) and Eshtemoa. These basins vary in drainage area and climate, and in monitoring duration and type. All are drained by gravel-bed channels. As the size of monitored drainage area is limited, 3-4 additional representative basins covering areas of 300, 1000, 2000 and 8000 square kilometers will likely be implemented in the next decade. The basins have precipitation, runoff, sediment and fluviomorphological records. Each was conceived for differing purposes, but all share the common two objectives for the continuous monitoring: 1. Many hydrological issues may be approached if, and only if, there are prototype databases on a wide spectrum of hydrological processes; and 2. There is a need for long-term records to assess large floods and subsequent hydrologic and geomorphic recovery. Lessons derived from a large number of research projects on these experimental basins focus on characteristics of runoff in arid climates. For example, the effect of the spatial distribution of rainfall on runoff generation becomes increasingly important with aridity. Rainfall angle on hillslopes and storm intensity and direction derived from rainfall recorders and radar backscatter are crucial for explanation of runoff response. Runoff hydrographs tend to have more bores, shorter-duration peaks, briefer recessions, longer dry periods, and are more variable in terms of flood volume and peaks with increased aridity. Suspended-sediment fluxes, yields and concentrations are relatively large in the semiarid realm, reaching maxima at the beginning of a flood season and after long dry spells. Bedload fluxes are exceptionally high from dryland basins in which hillslopes are minimally vegetated and where bedload transport takes place in channels lacking an armor layer. Bedload/suspended-sediment load ratios increase with aridity. Bedload yield may represent up to 70% of the total load. Hillslope to channel connectivity is high in drylands. In the hyperarid region suspended-sediment sources are hillslopes and the coarser, sandy fraction of the channel bedmaterial. The depth of channel bed activity is indicated by a fluvio-pedogenic unit beneath the channel surface. National and regional hydrological research needs will dictate future global monitoring in experimental basins. International collaboration may bring about considerable cost reduction by exclusion of monitoring aspects that can be evaluated based on the monitoring in other, similar conditions. Advanced international collaboration on validation and calibration of and consistency in monitoring means, as well as syntheses of lessons derived from international collaboration, such as from an International Watershed Research Network, are required for maximizing our understanding of water and sediment responses in varied global regions.

Laronne, J. B.; Lekach, J.; Cohen, H.; Gray, J.

2002-12-01

306

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.

307

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

308

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

309

Origin of Cuyama Basin oils  

SciTech Connect

Geochemical and geological data suggest that there are two possible source rocks for the oil produced in the Cuyama basin: the Soda Lake Shale Member of the Vaqueros Formation and the Monterey Formation. The Soda Lake is the more likely of the two, but the Monterey cannot be ruled out. Nine oils from the three largest Cuyama basin fields were studied. Geochemical data suggest that the oils originated from the same source rock, and they are similar to Miocene-sourced oils in other southern California basins. Source-rock analyses indicate that, at least locally, both the Monterey and the Soda Lake have good oil-source potential. For both units, total organic carbon values range up to about 5%, Rock-Eval S2 values range up to near 30 mg HC/g TOC, and hydrogen index values range up to near 600. However, although the Monterey is rich and oil-prone almost everywhere, the Soda Lake is in some places lean and gas prone. Even so, carbon isotopic data from rock extracts suggest that the Soda Lake shale is the more likely source of the oils. The oils in the fields were probably not generated indigenously. T/sub max/ data and burial-history analysis indicate that near the oil fields both formations are too immature to have generated significant amounts of light sweet oil. Instead, it is more likely that the oils were generated in the deep, extensional basin in the footwall of the Morales-Big Spring thrust system.

Lundell, L.; Gordon, S.

1988-03-01

310

Petroleum potential and stratigraphy of Holitna basin, Alaska  

Microsoft Academic Search

The Holitna basin, an interior Alaskan basin, is flanked by Cambrian to cretaceous sedimentary rocks that have been highly folded and faulted. Gravity mapping and modeling indicate up to 15,000 ft of sedimentary section is present within the basin. Cambrian rocks consist of trilobite-hash lime mudstone, red siltstone, and basinal chert. Ordovician through Devonian basinal facies rocks consist of platy

T. N. Smith; J. G. Clough; J. F. Meyer; R. B. Blodgett

1985-01-01

311

Regional salt movement effects in the English Southern Zechstein Basin  

Microsoft Academic Search

The halok inetic model of basinal salt movement described by Trusheim (1960) for the North German Zechstein Basin, with large salt-wall diapirs occurring in the basin centre, and diapirs, pillows, and swells of decreasing size evolving towards the basin margins, has been used to explain salt movements in many other basins. The concept of halokinesis implies vertically upward salt movements

Malcolm K. Jenyon

312

Biogeochemistry of a Suburban Basin  

NASA Astrophysics Data System (ADS)

A long-term research effort was recently established in the Lamprey River basin in southeastern New Hampshire. The watershed is largely forested, and has significant amounts of wetlands due to the relatively low topographic relief. Human population growth is rapid, resulting in conversion of forest and agricultural land to housing tracts. The primary focus of the project will be to examine the relationships between land use, land cover and water quality as the watershed continues to increase in population density. A secondary emphasis will be to examine the interactions between hydrologic flow paths, climatic variability, and biogeochemical processes that drive groundwater and surface water quality in the basin. Our initial work has quantified landscape attributes and related them to water quality. Results to date show that small tributary streams are relatively high in nitrogen relative to the main stem of the Lamprey; that human population density drives nitrate concentrations in the basin; and that DOC flux is predicted well by the model of Aitkenhead and McDowell that links DOC flux to watershed C:N ratio.

McDowell, W. H.; Daley, M. L.; Blumberg, J.

2002-12-01

313

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 TiO2 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

314

Namibe basin: geology and hydrocarbon potential, Angola  

SciTech Connect

Namibe basin is located in the south-central Atlantic off southern Angola. Its occurrence in Late Jurassic-Early Cretaceous continental rifting is coeval to the Santos of eastern Brazil. In this frontier-type, marginal sag basin, a 420-km sediment depocenter is estimated along a north-south elongation axis. Walvis Ridge bounds the basin's southern flank offshore, and desert sand covers the onshore strata. Regional unconformities are drawn from contiguous Kwanza and Congo basins. A potentially large reservoir is a 100-mi linear shelf-edge Albian carbonate inferred to be a buildup or bank. Other potential reservoirs are lacustrine sands/carbonates found near basement horst blocks and deep-basin Tertiary turbidites sourced from the shelf due to rapid sand deposition on a steep shelf-slope. The basin's excellent hydrocarbon potential is emphasized by marine and lacustrine source-rich shale deposition in optimal mature zones.

Abilio, S.; Inkollu, S.N.M.

1989-03-01

315

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

316

Toward a Reconceptualisation of Caribbean Basin Security  

Microsoft Academic Search

This paper analyses the changing concept of security in the Caribbean Basin. A range of non-traditional concerns have emerged as existential threats to Caribbean Basin nations. Even as state-directed actions contribute to the severity of the challenges, non-state actors are major sources of security dangers. The paper proposes that the concept of Caribbean Basin security, traditionally viewed through narrow military\\/geopolitical

Gail D. Verasammy

2009-01-01

317

Chapter 9 The Western Interior Basin  

Microsoft Academic Search

The Western Interior Basin extends north–south over about 35° of latitude, from Texas to the Northwest Territories, a distance of more than 3,000km. The basin developed as a result of crustal loading during the western migration of the North American Plate and the subduction of Panthalassa. Initiation of the Western Interior Basin as a distinctive geodynamic and stratigraphic province is

Andrew D. Miall; Octavian Catuneanu; Boyan K. Vakarelov; Ryan Post

2008-01-01

318

Reorientation of icy satellites by impact basins  

Microsoft Academic Search

Large impact basins are present on many of the icy satellites of the outer solar system. Assuming that their present-day topography is uncompensated, such basins can cause significant poleward reorientations for slow-rotating satellites. This reorientation may have been accompanied by transient large-amplitude wobble. The largest basins on Tethys, Rhea and Titania are predicted to have caused reorientations of roughly 4°,

F. Nimmo; I. Matsuyama

2007-01-01

319

Marfa basin of West Texas: foreland basin subsidence and depocenter migration  

Microsoft Academic Search

The Marfa basin, encompassing approximately 6,000 mi² (15,539 km²) of Presidio and Brewster Counties in west Texas, is a foreland basin that formed in the late Paleozoic in response to the encroaching Ouachita-Marathon thrust belt. The authors present a model of the formation of the Marfa basin in which basin subsidence is effected by compression from plate convergence and by

J. J. Mauch; R. H. Wetterauer; J. L. Walper; K. M. Morgan

1984-01-01

320

Ring spacing of Mercurian multi-ring basins and basin ring formation  

NASA Astrophysics Data System (ADS)

Recent systematic mapping of Mercury has revealed many ancient and previously unrecognized multi-ring basins. The population of these basins now stands at 20, possibly is as large as 25, and includes at least 76 measurable rings. From the new data base, the authors present some systematics of basin ring spacing on Mercury, compare them with similar data for the Moon, and draw some preliminary conclusions on conditions of ring formation for basins on the terrestrial planets.

Pike, R. J.; Spudis, P. D.

1984-04-01

321

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

322

Integrated data on key river basins  

NASA Astrophysics Data System (ADS)

A new reference tool provides the most comprehensive data base of 154 of the world's river basins and sub-basins; representing those that cover most of Earth's land surface. It lists indicators and variables for each of these basins and, where appropriate, provides links and references to additional, relevant information.The "Watersheds of the World" compact disk and Web site was released on 18 March by the World Conservation Union (IUCN). The resource provides information on land cover and land use; population density; basin indicators, including degree of river fragmentation and number of dams; and biodiversity information. It also contains 20 global maps portraying critical water resources issues.

Showstack, Randy

323

The first pterosaur tracks from Gondwana  

Microsoft Academic Search

Pterosaur tracks from the Candeleros Member of the Rio Limay Formation (Albian–Cenomanian) at Lake Ezequiel Ramos Mex??a, Neuquén Province, Argentina, are the first pterosaurian tracks reported from South America and from the Southern Hemisphere. Although the individual footprints are not well preserved, some trackway segments and manus-pes sets are preserved, suggesting that the tracks can be assigned to cf. Pteraichnus

Jorge O. Calvo; Martin G. Lockley

2001-01-01

324

Geophysical basin structure of the Cotonou (Dahomey\\/Benin) basin, West African Gulf of Guinea  

Microsoft Academic Search

The frontier Cotonou basin (or Dahomey\\/Benin embayment), situated west of the prolific Niger Delta basin, appears from seismic, gravity, and aeromagnetic interpretation, as a series of grabens and troughs confined on the west and east by the Romanche and the Chain fracture zones, respectively. The Keta trough of the western basin rim was formed by a 2700-m southeasterly downthrow of

Olufemi O. Babalola

1990-01-01

325

Vertical movement in mare basins: relation to mare emplacement, basin tectonics, and lunar thermal history  

Microsoft Academic Search

The spatial and temporal relationships of linear rilles and mare ridges in the Serenitatis basin region of the moon are explained by a combination of lithospheric flexure in response to basin loading by basalt fill and a time-dependent global stress due to the thermal evolution of the lunar interior. The pertinent tectonic observations are the radial distance of basin concentric

Sean C. Solomon; James W. Head

1979-01-01

326

Magnetic Mineralogy of Continental Deposits, San Juan Basin, New Mexico, and Clark's Fork Basin, Wyoming  

Microsoft Academic Search

Magnetic concentrates were obtained from nine bulk samples from the Late Cretaceous through middle Paleocene continental sedimentary section in the San Juan Basin, New Mexico, and from two bulk samples from the late Paleocene and early Eocene section in the Clark's Fork Basin, Wyoming. Strong-field thermomagnetic (Js-T) curves of almost all the San Juan Basin concentrates show only a single

Robert F. Butler

1982-01-01

327

Institutional and policy analysis of river basin management: the tarcoles river basin, Costa Rica  

Microsoft Academic Search

This paper describes and analyzes the effort to institute river basin management in the Tárcoles basin of Costa Rica. Located in west-central Costa Rica, the Tárcoles basin represents 4.2 percent of the nation's total land area, but is home to half the nation's population and the metropolitan area of San José, the nation's capital and largest city. Water management issues

William Blomquist; Maureen Ballestero; Anjali Bhat; Karin Kemper

2005-01-01

328

Reserve estimates in western basins. Part 2: Piceance Basin  

SciTech Connect

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

NONE

1995-10-01

329

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

SciTech Connect

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

Not Available

1993-10-01

330

Petroleum Geology of the Palo Duro Basin, Texas Panhandle.  

National Technical Information Service (NTIS)

The Palo Duro Basin, Permian Basin, Texas is an asymmetric, relatively shallow, intracratonic basin in the southern Texas Panhandle filled mostly by Mississippian, Pennsylvanian, and Permian sedimentary rocks. Although deeper and prolific prolific petrole...

P. R. Rose

1986-01-01

331

The Crustal Structure of Orientale and Implications for Basin Formation  

Microsoft Academic Search

High-resolution crustal structure models of the Orientale Basin, CTH numerical simulations of the basin forming impacts, and flexural models are used to investigate the basin forming process and the origin of super-isostatic mantle uplifts.

J. C. Andrews-Hanna; S. T. Stewart

2011-01-01

332

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

333

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

334

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

335

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

336

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

337

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

338

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

339

Consequences of foreland basin development on thinned continental lithosphere: Application to the Aquitaine basin (SW France)  

NASA Astrophysics Data System (ADS)

We present an analysis of the consequences of foreland basin development on thinned continental lithosphere, inherited from pre-orogenic phases of extension. Bathymetry at the transition from pre-orogenic extensional basin to foreland basin and compaction of pre-orogenic sediments contribute to the accommodation space for foreland basin sediments and thrust loads. In addition, the extension-induced transient thermal state of the lithosphere, results in ongoing thermal subsidence, and a flexural rigidity which changes through time. Quantitative modelling of the phase of extension and the foreland basin stage of the Aquitaine basin (southern France) shows that the inherited transient thermal state of the lithosphere contributes significantly to (1) the total foreland basin depth and width, (2) the post-compressional subsidence history, and (3) the cratonward onlap pattern. Accounting for the thermo-mechanical effects of pre-orogenic extension significantly reduces the estimates of both the flexural rigidity (30-43% for the Aquitaine basin) and the required topographic or thrust load (40% for the Aquitaine basin) at foreland basins. Emplacement of thrust loads below sea level, as expected in a pre-orogenic extensional basin setting, further reduces the required topographic load. This sheds light on the wide range of flexural rigidity values reported for continental lithosphere from foreland basin modelling studies, and explains, in many instances, the inferred `hidden load' or subsurface load in flexural modelling studies at foreland basins. The present study has shown that pre-orogenic extension phases significantly affect the record of vertical motion and the stratigraphy of the Aquitaine basin and is probably important for foreland basin evolution in general.

Desegaulx, Pascal; Kooi, Henk; Cloetingh, Sierd

1991-09-01

340

Morphometric Analysis of Martian Valley Network Basins  

NASA Astrophysics Data System (ADS)

Whether the Martian valley networks were formed predominantly by groundwater sapping or surface fluvial runoff continues to be debated and has profoundly different implications for the climatic history of Mars and the possible evolution of life there. This paper attempts to evaluate the relative role of groundwater sapping vs. surface runoff in valley networks generation through quantitative morphometic analysis at watershed basin scale using the highest resolution MOLA DEM data. Treating the hypsometric curve of each basin as a cumulative probability distribution, its integral, skewness, kurtosis, density skewness, and density kurtosis (collectively called hypsometric attributes) can serve as quantitative measures of the basin's morphology. The hypsometric attributes are sensitive to variations in overall basin characteristics and thus are diagnostic of possible processes. These attributes of typical terrestrial sapping basins, typical terrestrial fluvial basins, and typical lunar impact cratering basins were used as endmembers to establish discriminant functions to classify Martian basins. The posteriori probability of each class membership for each Martian basin then serves as the measure of the relative role of sapping, fluvial or cratering process in forming that basin. Initial results in Margaritifer Sinus area show that groundwater sapping played a more dominant role than surface runoff, generally consistent with previous findings based on lower resolution data and supporting a precipitation-recharged groundwater sapping origin for valley networks. Using a circularity function (a ratio of area and perimeter as a function of elevation) as the measure for basin morphology in the discriminant analysis produced similar results. Other traditional morphometric parameters such as drainage density, width function, cumulative area distribution, and slope-area relationship will also be derived for Margaritifer and other areas. The overall spatial pattern of the distribution will be examined to shed more light on past climatic conditions for generating the Martian valley networks.

Luo, W.; Arvidson, R. E.; Howard, A. D.

2005-05-01

341

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

342

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

SciTech Connect

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

Peterson, Robert E.

2007-03-22

343

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

344

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

345

Modelling conservation in the Amazon basin  

Microsoft Academic Search

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

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

2006-01-01

346

Corrosion in ICPP fuel storage basins  

Microsoft Academic Search

The Idaho Chemical Processing Plant currently stores irradiated nuclear fuel in fuel storage basins. Historically, fuel has been stored for over 30 years. During the 1970`s, an algae problem occurred which required higher levels of chemical treatment of the basin water to maintain visibility for fuel storage operations. This treatment led to higher levels of chlorides than seen previously which

1993-01-01

347

Water Productivity from Integrated Basin Modeling  

Microsoft Academic Search

It is obvious that real water saving measures are only possible if the current water resources are clearly understood. For a basin in western Turkey, simulation modeling at three different scales, field, irrigation scheme and basin level was performed to obtain all terms of the water balance. These water balance numbers were used to calculate the Productivity of Water (PW)

Peter Droogers; Geoff Kite

1999-01-01

348

Stratigraphy of Pennsylvanian detrital reservoirs, Permian basin  

Microsoft Academic Search

Significant oil reserves have been found to date in stratigraphic traps in Pennsylvanian detrital reservoirs on the Central Basin platform and Reagan uplift of the Permian basin. The 32 MMBOEG Arenoso field area, discovered in 1966, is the largest producing field. Along a 75 mi northwest-southeast trend, 23 other smaller fields will produce an average 850 MBOEG each, for a

Van Der Loop

1992-01-01

349

African sedimentary basins - Tectonic controls on prospectivity  

SciTech Connect

An important prerequisite for the evaluation of any sedimentary basin is the understanding of its regional tectonic setting. This is especially so in the underexplored regions of Africa. The majority of African sedimentary basins developed in an extensional setting although some have undergone subsequent compressional or transpressional deformation. The geometry and evolution of these basins is often influenced by basement structure. The extensional phase of basin development controls not only the distribution of syn-rift sediments but also the magnitude of post-rift regional subsidence and the preservation or removal of pre-rift sediments. This has important consequences for exploration models of syn-rift and pre-rift source rocks and reservoirs. Post-rift basin inversion and uplift provide crucial controls on the preservation of mature source rocks and quality of reservoirs. The distribution, nature, timing, and possible mechanisms of this uplift in Africa will be addressed. The hydrocarbon prospectivity of African basis appears to be highly variable although the limited exploration of some regions makes the exact extent of this variability unclear. Basins considered potentially prospective range from late Precambrian to Tertiary in age. The various tectonic controls outlined above, and criteria for the evaluation of underexplored areas, will be demonstrated by reference to basins studied by The Robertson Group. Examples described include basins from Bagon, Angola, Namibia, East Africa, Tertiary Rift and Karoo Rifts, and North Africa (Sudan, Egypt, Algeria, and Morocco).

Bunter, M.A.G.; Crossley, R.; Hammill, M.; Jones, P.W.; Morgan, R.K.; Needham, D.T.; Spaargaren, F.A. (Robertson Group plc, Gwynedd (England))

1991-03-01

350

Archeological Overview of Great Basin National Park.  

National Technical Information Service (NTIS)

The overview provides a discussion and summary of the archeology and cultural resources of the newly formed Great Basin National Park in east-central Nevada. Although a great deal is known of the culture history of the Great Basin, very little research ha...

K. Deal

1988-01-01

351

Basin wildrye: the forgotten grass revisited  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

352

Parabolic density function in sedimentary basin modelling  

Microsoft Academic Search

For modelling sedimentary basins of large thickness from their gravity anomalies, the concept of parabolic density function which explains the variation of true density contrast of the sediments with depth in such basins is introduced inBott's (1960) procedure. The analytical expression the gravity anomaly of a two-dimensional vertical prism with parabolic density contrast needed to estimate the gravity effect of

C. Visweswara Rao; V. Chakravarthi; M. L. Raju

1993-01-01

353

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.

354

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

355

Scientific Review of Great Basin Wildfire Issues  

Technology Transfer Automated Retrieval System (TEKTRAN)

The University Nevada Reno, College of Agriculture and Resource Concepts Inc., co-sponsored a Great Basin Wildfire Forum in September 2007 to address a “Scientific Review of the Ecological and Management History of Great Basin Natural Resources and Recommendations to Achieve Ecosystem Restoration”. ...

356

NEES Multidirectional Wave Basin for Tsunami Research  

Microsoft Academic Search

Oregon State is upgrading its multidirectional wave basin under the National Science Foundation Network for Earthquake Engineering Simulation (NEES) program to create a next-generation experimental testing facility for research and practicing engineers. The new facility addresses the unique requirements posed by tsunami researchers, with basin dimensions and wave generation capabilities closely matching the community's vision of the \\

Solomon C. Yim; Harry H. Yeh; Daniel T. Cox; Cherri M. Pancake

2003-01-01

357

Synchronous compressional pulses in extensional basins  

Microsoft Academic Search

Such paradoxes as synchronous compression and tension in extensional sedimentary basins, and synchronous deformation of intractonic basins and eustatic sea-level falls, can each be related to pulsed changes in curvature of the Earth's surface. Australia is everywhere in a state of significant, relatively uniform, upper crustal horizontal compression, approximately perpendicular to the continental margins and generally directed towards its centre.

John K. Davidson

1997-01-01

358

Groundwater management for Lower Indus Basin  

Microsoft Academic Search

The present study aims to find out an optimum policy for pumping out the optimized volume of groundwater obtained from the authors' earlier Two Level Optimization Model [N.K. Garg, A. Ali, 1998. Two level optimization model for Lower Indus Basin. Agric. Water Manage. 36, 1–21] for the Dadu Canal Command of the Lower Indus Basin. It is shown that the

N. K. Garg; A. Ali

2000-01-01

359

Geology and exploration in Takutu basin, Guyana  

Microsoft Academic Search

The Takutu basin is an intracratonic graben 280 km (174 mi) long and 40 km (25 mi) wide in northern Brazil and adjoining Guyana, lying entirely within the center of the early Precambrian Guyana shield. Acidic metavolcanic rocks and thick Proterozoic quartzite lie to the north of the basin. Granulite, gneiss, and granite border the graben to the south and

F. D. Crawford; C. E. Szelewski; G. C. Alvey

1983-01-01

360

Crustal structure of the Khartoum Basin, Sudan  

NASA Astrophysics Data System (ADS)

The crustal structure of the northern part of the Khartoum Basin has been investigated using data from 3 permanent seismic stations within 40 km of Khartoum and two modeling methods, H–k stacking of receiver functions and a joint inversion of receiver functions and Rayleigh wave group velocities. The Khartoum Basin is one of several Mesozoic rift basins in Sudan associated with the Central African Rift System. Results from the H–k-stacking indicate that crustal thickness beneath the Khartoum Basin ranges between 33 and 37 km, with an average of 35 km, and that the crustal Vp/Vs ratio ranges from 1.74 to 1.81, with an average of 1.78. From the joint inversion of receiver functions and Rayleigh wave group velocities, we obtained similar results for Moho depth, as well as an average shear wave velocity of 3.7 km/s for the crust. These results provide the first seismic estimates of Moho depth for a basin in Sudan. When compared to average crustal thickness for unrifted Proterozoic crust in eastern Africa, our results indicate that at most only a few km of crustal thinning may have occurred beneath the Khartoum Basin. This finding is consistent with estimates of effective elastic plate thickness, which indicate little modification of the Proterozoic lithosphere beneath the basin, and suggests that there may be insufficient topography on the lithosphere–asthenosphere boundary beneath the Sudanese basins to channel plume material westward from Ethiopia.

El Tahir, Nada; Nyblade, Andrew; Julià, Jordi; Durrheim, Raymond

2013-05-01

361

Higher gas prices boost Arkoma basin drilling  

Microsoft Academic Search

Drilling for gas in the Arkoma basin in Oklahoms has risen. Contractors ; are working on 8,000 to 15,000-foot jobs seeking gas production in Lower ; Pennsylvanian Atokan series of Pottsville age, especially the Spiro sand. ; Lenticular, fine-grained sandstones in the Atokan sequence furnish most gas ; reserves in the basin. A great increase in intrastate prices, multiple gas

Kornfeld

1974-01-01

362

Hellas: A double-impact basin  

Microsoft Academic Search

With the major axis to minor axis ratio of about 1.3, Hellas is probably the most elliptical giant impact basin on Mars, even more elliptical than the basin fits to the northern lowland [1]. Because less than 4% of the impacts in the solar system have occurred at impact angles greater than 80o relative to the planet surface [2] Hellas

J. Arkani-Hamed

2010-01-01

363

Lunar Multiring Basins and the Cratering Process  

Microsoft Academic Search

Numerous studies of the lunar gravity field have concluded that the lunar Moho is substantially uplifted beneath the young multiring basins. This uplift is presumably due to the excavation of large quantities of crustal material during the cratering process and subsequent rebound of the impact basin floor. Using a new dual-layered crustal thickness model of the Moon, the excavation cavities

Mark A. Wieczorek; Roger J. Phillips

1999-01-01

364

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

365

INFORMATION INTEROPERABILITY FOR RIVER BASIN MANAGEMENT  

Microsoft Academic Search

Many countries are adopting water policies and legislative instruments for water management in conformance to the agenda 21. According to this agenda, the use and protection of surface water and groundwater are coordinated at a river basin level. The success of river basin management systems relies upon coordinated actions, including provision of and access to information as well as the

Jackson Roehrig

366

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

367

Structure of the Western Somali Basin  

Microsoft Academic Search

The western Somali Basin in the northwestern Indian Ocean is covered by thick deposits of terrigenous sediments. Seismic reflection profiles show, however, the northern and southern parts to be very different. The northern sections is a deep basin filled with thick uniformly stratified sediments. It is enclosed by the continental margin to the west and north, Chain ridge to the

Elizabeth T. Bunce; M. G. Langseth; R. L. Chase; M. Ewing

1967-01-01

368

Abyssal circulation in the Somali Basin  

Microsoft Academic Search

The bottom and deep circulation in the Somali Basin are investigated on the basis of hydrographic and direct velocity profiles from three shipboard surveys carried out during the southwest monsoon in 1995 and of velocity time series from the WOCE mooring array ICM7. The inflow of bottom water into the Somali Basin through the Amirante Passage drives a thermohaline circulation,

M. Dengler; D. Quadfasel; F. Schott; J. Fischer

2002-01-01

369

Petroleum prospects of Southern Nigeria's Anambra Basin  

Microsoft Academic Search

Surrounded by the Benue trough, the Middle Niger River depression, the Niger River delta, and the Abakaliki anticlinorium, Nigeria's Anambra basin probably holds a thick, unexplored sequence with significant hydrocarbon potential. The basin's sediment could be 16,000 ft thick; a Bouguer gravity survey indicates two parallel northeast-southwest trending gravity lows (the Anambra low and the Awka depression) separated by the

A. A. Avbovbo; O. Ayoola

1981-01-01

370

Upper Paleozoic petroleum system, Ordos Basin, China  

Microsoft Academic Search

The Ordos Basin is a typical lapped basin, including three sequences of strata: early Paleozoic, late Paleozoic and Mesozoic, with a total thickness of 4000–6000m. Impermeable sealing beds are well developed at the top and base of the upper Paleozoic sequence, separating it from the Mesozoic and the lower Paleozoic strata to form an independent petroleum system. In this petroleum

X. M. Xiao; B. Q. Zhao; Z. L. Thu; Z. G. Song; R. W. T. Wilkins

2005-01-01

371

Sedimentary basins on the connugate margins of South America and Africa  

Microsoft Academic Search

An Early Cretaceous spreading system formed the South Atlantic by separating South America from Africa along two subparallel major transform fault systems. The distribution of major sedimentary depocenters is controlled by the complex interplay of two factors: the late Mesozoic-Cenozoic cycle of sea-floor spreading and the legacy of a Precambrian collage of ancient cores that comprised western Gondwana. Three spreading

1990-01-01

372

Preliminary evaluation of nominal drainage basin volume as a potentially useful morphometric parameter for small mountain basins  

SciTech Connect

Morphometric basin parameters have been used in quantitative geomorphic assessments since Horton's Hydrophysical Approach in 1945. A relationship between basin form and dominant process in small mountain basins in the western United States would be valuable for use in differentiating basins which produce deep-seated landslides from those which produce debris flows from debris slides. Drainage basin volume seems like it should be a parameter directly related to the dominant process operating in a basin. Consequently, it may be a potentially useful morphometric parameter. Nominal drainage basin volume is herein defined as the volume creates by the basin topography and linear projection of topographic contours across the basin. Incremental volume is computed from area encompassed by topographic contours and projections and the contour interval using the formula for the volume of the frustrum of a cone. Seven basins in the Wasatch Range and five in the Wasatch Plateau of Utah show strong relationship of log Basin Area to log Basin Volume (r/sup 2/ = 0.97). The relationship between average Basin Slope and log Basin Volume was poorer (r/sup 2/ = 0.78) than between Basin Slope and log Basin Area (r/sup 2/ = 0.87). This suggests that basin area may be a more useful parameter than basin volume, especially since area is more easily measured.

Keaton, J.R.

1985-01-01

373

Seismic stratigraphic investigation of west Florida basin  

SciTech Connect

An Upper Jurassic (.)-Lower Cretaceous basin in the eastern deep Gulf of Mexico, referred to as the West Florida basin, has been described from University of Texas Institute for Geophysics multichannel seismic profiles, DSDP wells, and some gravity and magnetic data. The basin extends beyond the limits of Middle Jurassic salt deposition, and is possibly a westward extension of the Tampa embayment, implying a relatively continuous westward-dipping basement below the central portion of the Florida escarpment. The Lower Cretaceous sequence within the basin is though to be the Valanginian section missing from the Gulf Coast shelf stratigraphy. The early geologic history of the West Florida basin, inferred from this study, favors the evolutionary models for the Gulf of Mexico that rotate the Yucatan peninsula counter-clockwise from a close Gulf position to its present location.

Lord, J.P.

1987-09-01

374

Hydrological research basins and the environment  

NASA Astrophysics Data System (ADS)

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

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

375

Meeteetse field, Bighorn basin, Wyoming  

SciTech Connect

Lower Cretaceous Muddy and Upper Cretaceous Frontier sandstone reservoirs remain popular objectives for new energy reserves in the Bighorn basin of northwestern Wyoming. Predominantly structural reserves approximate 1 million bbl of oil and 20 bcf of gas from six Muddy fields, and 210 million bbl of oil and 100 bcf of gas from 16 Frontier fields. Newly established structural-stratigraphic gas production from these reservoirs is at Meeteetse field (T48-49N, R99W) on the west flank of the basin where Muddy Frontier bar sandstones trend across a long, narrow, horst-associated anticline. Terra Resources 1-33 Federal (Sec. 33, T49N, R99W) established the shallower pool discovery in 1979. Ten wells are now drilled along or near the axis of the structure. Production history is only now beginning because wells were shut in during field development due to absence of a gas line. The Frontier is productive in the middle two of its four units. Most initial production rates are between 1 and 2 MMCFGD; small amounts of oil, condensate, and water have been produced from some wells. The Muddy is a discrete sandstone unit with thin shale interbeds. Most initial production rates are between 1 and 3 MMCFGD; small amounts of oil, condensate, and water are also produced. Some production is from commingled Frontier zones and from commingled Frontier and Muddy.

Wolff, R.; Roy, R.

1984-07-01

376

Crustal Structure of the Khartoum Basin, Sudan  

NASA Astrophysics Data System (ADS)

The Khartoum basin is one of several Mesozoic rift basins in Sudan associated with the Central Africa Rift System. Little is known about the deep crustal structure of this basin, and this limited knowledge hampers the development of a more detailed understanding of its origin and evolution. Constraints on crustal structure in Sudan are only available through regional gravity studies and continental-scale tomography models, but these studies have poor resolution in the Khartoum basin. Here, we investigate the crustal structure of the northern part of the Khartoum basin beneath 3 permanent seismic stations in Khartoum, Sudan through the H-k stacking of receiver functions and the joint inversion of receiver functions and Rayleigh-wave group velocities. Our H-k-stacking results indicate that crustal thickness beneath the Khartoum basin ranges between 33 and 37 km, with an average of 35 km and that crustal Vp/Vs ratio ranges from 1.74 to 1.81, with an average of 1.78. These results are consistent with 1D velocity models developed from the joint inversion of receiver functions and Rayleigh-wave group velocities, which display similar estimates for crustal thickness and an average shear-wave velocity of 3.7 km/s for the basin's crust. Our results provide the first seismic estimate of Moho depth for a basin in Sudan and, when compared to average crustal thickness for the unrifted Proterozoic crust in eastern Africa, reveal that at most a few kilometers of crustal thinning has occurred beneath the Khartoum basin. Keywords: Teleseismic P-waveforms; Moho depth; Shear wave velocity; Khartoum Basin.

El Tahir, Nada; Nyblade, Andrew; Julia, Jordi; Durrheim, Raymond

2013-04-01

377

BASINS  

EPA Science Inventory

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

378

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

2011-06-13

379

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.

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

2011-01-01

380

Reconstruction of deformed North Pyrenean basin  

SciTech Connect

The North Pyrenean basin in southern France was initiated in middle Cretaceous time along the North Pyrenean fault zone. An understanding of the middle Cretaceous is critical because it corresponds in time to opening in the Bay of Biscay, to postulated strike-slip along the North Pyrenean fault, to a controversially dated episode of metamorphism, and to emplacement of lherzolite. A field study of the Albian and Cenomanian fill of the North Pyrenean basin has been undertaken in order to provide constraints on postulated regional relationships during this time. Two steps are required for the study. The first is to reconstruct the structure of the basin that was deformed during the Late Cretaceous to Oligocene Pyrenean orogeny. The orogeny is here summarized as a north-south shortening that reactivated the North Pyrenean fault zone as a north-vergent reverse fault. Dominantly south-directed thrusting followed, and detachment along incompetent Triassic shale and evaporite layers was important in both phases. The second step is a sedimentologic analysis. The basin fill is dominantly marine, clastic mud, up to 4 km thick. Abrupt lateral thickness and facies variations demonstrate that the basin was bounded by active faults. Excepting the absence of high organic productivity, reconstruction suggests that the North Pyrenean basin is a partial analog in terms of geometry, facies arrangement, and regional setting to Cenozoic marine basins in California, particularly to those in which Monterey Formation lithologies were deposited.

Johnson, J.A.

1985-02-01

381

Undiscovered Petroleum of the Brazilian Interior Sag Basins  

Microsoft Academic Search

This paper, the second in a series dealing with undiscovered petroleum in South American basins (exclusive of Venezuela and Colombia), focuses on the four large intracratonic (or interior) sag basins of Brazil: the Solimoes, Amazonas, Parnaiba, and Parana. The smaller Chaco basin also is discussed, although in less detail. Preliminary estimates of undiscovered hydrocarbons in the five basins are 0.228

John Kingston; John R. Matzko

1995-01-01

382

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

383

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

384

Structural evolution of Val Verde basin, west Texas  

Microsoft Academic Search

The Val Verde basin is a northwest-southeast trending foreland basin contained within the southern portion of the Permian basin. The Val Verde basin has several large fields, e.g., Brown Bassett and JM, which have a combined ultimate recovery of over 1 tcf of gas. Structurally, the major fields are complexly faulted features related to differential uplift of basement blocks. Middle

D. E. Sanders; N. Petersen

1984-01-01

385

The Evolution of Impact Basins: Viscous Relaxation of Topographic Relief  

Microsoft Academic Search

We evaluate the hypothesis that viscous relaxation has been an important process for modifying the topographic profiles of ancient large impact basins on the moon. We adopt a representative topographic profile of the Orientale basin, the youngest large impact basin on the moon, as an estimate of th e initial topography of older basins of similar horizontal dimensions, and we

Sean C. Solomon; Robert P. Comer; James W. Head

1982-01-01

386

Shared Water Resources in the Jordan River Basin  

Microsoft Academic Search

The purpose of this article is to chronicle the history of river basin development plans of the Jordan River basin riparians (Israel, Jordan, Lebanon, the Palestinian Authority, and Syria) and to analyze the agreements among the Jordan River basin riparians in light of international law principles. The relationship among the Jordan River basin riparians is complicated by the fact that

Karen Hudes

387

Report card--Murray-Darling Basin--2001.  

PubMed

Ongoing deterioration of the riverine environments of the Murray-Darling Basin led the Murray-Darling Basin Ministerial Council to introduce a Cap in 1995 to halt the growth in diversions of water for consumptive use. This initiative recognised the finite nature of water resources in the Basin and sought to introduce a balance between off-stream use of water and protection of the riverine environment. But the cap is only one step, albeit a fundamental one, in restoring the Basin's rivers--it is a "stake in the ground". Parties to the Murray-Darling Basin Initiative recognise the need to reverse decades of creeping decline if the Basin's rivers and riverine environments are to return to a more ecologically sustainable condition. In the last 12 months, Council and Commission have taken far-reaching decisions designed to restore the Basin's Rivers. Many of these decisions, even 10 years ago, would have been unimaginable. The Report Card will explain the need for a number of recent decisions that will impact on the future of the Basin's rivers. For example, Council's decision to establish an Environmental Manager function in the Office of the Commission was made in the context of the recently agreed Integrated Catchment Management (ICM) Policy, and supporting Sustainable Rivers Audit. The role of targets and accountabilities under the ICM Policy will also be discussed. The Report Card will also present a snapshot of the state of the Basin's rivers and the actions being taken at a range of scales and locations in response to identified problems. Because some of the key initiatives are still in development, this Report Card will set the scene by describing where our attention is being focused and why. PMID:12171345

Goss, K

2002-01-01

388

Umatilla Basin Habitat Improvement Project.  

SciTech Connect

This annual report is in fulfillment of contract obligations with Bonneville Power Administration which is the funding source for the Oregon Department of Fish and Wildlife's Umatilla Basin Habitat Improvement Project. The major activities undertaken during this report period were: procurement of 17 cooperative lease agreements with private landowners, design and layout of 8.6 miles of riparian exclosure fence and 3.0 miles of instream structures, development of five fencing contracts and six instream work contracts. Results include implementation of 10 miles of fencing and 3 miles of instream work. Other activities undertaken during this report period are: data collection from 90 habitat monitoring transects, collection and summarization of temperature data, photopoint establishment, coordination with numerous agencies and tribes and education of all age groups on habitat improvement and protection. 4 refs., 4 figs., 6 tabs.

Bailey, Timothy D.

1990-01-01

389

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

390

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

391

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

392

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

393

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

394

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

395

Aqueous Sedimentary Basins on Mars  

NASA Astrophysics Data System (ADS)

Planetary Geomorphology is a relatively new field of scientific investigation which began in earnest with the dawn of the Space Age (1957). However, the roots of this endeavor can be traced back to the first hominid who gazed upon the Moon's face and noted that it consisted of light and dark regions. The invention of the telescope, in 1610, naturally induced a revolution in this realm of study and literally opened new vistas of exploration. The first true geomorphic study of the lunar surface was conducted by G. K. Gilbert in the 1890s. President Kennedy's goal of landing a man on the Moon intensified lunar studies and marked the second revolution in planetary geomorphic studies. This revolution was brought forth under the auspices of both unmanned and manned missions. Within our solar system it appears that the Earth is the only planetary body capable of maintaining liquid water today. But has this always been the case? Is there any possibility that in the past liquid water existed on other planets? Based upon observational evidence it does appear that liquid water was abundant in the past on Mars. Indeed, there may have been enough water on Mars to maintain large lakes and possibly even oceans. Current understanding of the geological and hydrological history of Mars is based primarily on the images returned from the Mariner and Viking spacecraft missions. It should be noted that at this point in time (November 1997); the Mars Pathfinder Mission which landed on Mars July 4, 1997 has just been successfully completed and Mars Global Surveyor has just entered orbit and is starting to collect remotely sensed data on Mars. These missions will provide a wealth of data to be analyzed in the coming years and should answer some of the questions raised in this dissertation. Geologic, morphologic, and topographic evidence is collected and studied to develop a global perspective on the locations, amounts, and times of accumulation of water that may once have been present on the surface of Mars. This work had two related objectives: (1) to examine large topographic basins whose locations appeared favorable for the accumulation of water and (2) to map and reassess the time-stratigraphic positions of small highland and lowland channels by using the latest geologic maps and morphologic criteria. paleolacustrine environments existed during intermediate and later periods of Martian history. Locations of possible paleolakes on Mars are determined by tracing fossil shoreline indicators along the margins of large topographic basins. The relatively young age (Amazonian) of basin-floor deposits and the wider range in age (Hesperian-Amazonian) of the small and large channels that supplied the basins with water suggest that the former lakes existed intermittently, possibly for sufficiently long periods to promote and sustain life.

Rice, James William, Jr.

396

Stratigraphy of the Caloris basin, Mercury  

USGS Publications Warehouse

The 1300-km-diameter Caloris impact basin is surrounded by well-defined ejecta units that can be recognized from more than 1000 km, radially outward from the basin edge. A formal rock stratigraphic nomenclature is proposed for the Caloris ejecta units, which are collectively called the Caloris Group. Each of the individual formations within the Group are described and compared to similar rock units associated with the lunar Imbrium and Orientale basins. A crater degradation chronology, linked the the Caloris event, is also proposed to assist in stratigraphic correlation on a Mercury-wide basis. ?? 1981.

Mccauley, J. F.; Guest, J. E.; Schaber, G. G.; Trask, N. J.; Greeley, R.

1981-01-01

397

K Basins Groundwater Monitoring Task, K Basins Closure Project: Report for April, May, and June 2007  

SciTech Connect

This report provides information on groundwater monitoring near the K Basins during April, May, and June 2007. Conditions remained similar to those reported in the previous quarter’s report, with no evidence in monitoring results to suggest groundwater impact from current loss of shielding water from either basin to the ground. During the current quarter, the first results from two new wells installed between KE Basin and the river became available. Groundwater conditions at each new well are reasonably consistent with adjacent wells and expectations, with the exception of anomalously high chromium concentrations at one of the new wells. The K Basins monitoring network will be modified for FY 2008 to take advantage of new wells recently installed near KW Basin as part of a pump-and-treat system for chromium contamination, and also the new wells recently installed between the KE Basin and the river, which augment long-term monitoring capability in that area.

Peterson, Robert E.

2007-08-08

398

Deep seismic expression of a foreland basin: Taranaki basin, New Zealand  

NASA Astrophysics Data System (ADS)

A deep seismic-reflection profile shot across the South Taranaki basin, New Zealand, indicates up to 10 km of crustal thickening beneath the Taranaki boundary fault at the eastern margin of the basin. The seismic data also show a broad flexure of the entire crust, the locus of the flexure-producing load appearing to be in the vicinity of the Taranaki boundary fault. Such crustal thickening and flexure suggest a compressional, foreland-basin style of late Cenozoic development rather than the rift-graben origin previously assumed. This change in interpretation for the South Taranaki basin has implications for evaluating the thermal history of the basin and its possibilities for hydrocarbon prospects. The study therefore demonstrates the value of deep seismic exploration of a hydrocarbon-bearing basin in its early stage of exploration.

Stern, T. A.; Davey, F. J.

1990-10-01

399

Mineralogical variability of Callovo-Oxfordian clays from the Paris Basin and the Subalpine Basin  

NASA Astrophysics Data System (ADS)

High-resolution clay mineralogical data at the Middle/Upper Jurassic boundary from the French Subalpine Basin, the Jura Mountains and the Paris Basin (ANDRA boreholes) from Callovo-Oxfordian clayey deposits allow spatial and temporal terrigenous flux evolution to be considered over a period of 6 to 7 Myr. Recorded diachronisms of major mineralogical changes and complex clays distribution at the Paris Basin scale result to combined palaeogeographic/eustatic variations and climate input. In the French Subalpine Basin, mineralogical homogeneity confirms the burial diagenesis influence, but other terrigenous supplies must be involved in contrast to the Paris Basin domains. Volcanogenic clays (bentonites) recorded in the two basins reflect paroxysmal explosive volcanic events allowing high resolution correlations to be made and to define active volcanic sources for the Jurassic. To cite this article: P. Pellenard, J.-F. Deconinck, C. R. Geoscience 338 (2006).

Pellenard, Pierre; Deconinck, Jean-François

2006-10-01

400

Ground-water hydraulics of the deep-basin brine aquifer, Palo Duro Basin, Texas panhandle  

Microsoft Academic Search

The Deep-Basin Brine aquifer of the Palo Duro Basin (Texas Panhandle) underlies thick Permian bedded evaporites that are being evaluated as a potential high-level nuclear waste isolation repository. Potentiometric surface maps of 5 units of the Deep-Basin Brine aquifer were drawn using drill-stem test (DST) pressure data, which were analyzed by a geostatistical technique (kriging) to smooth the large variation

1985-01-01

401

Institutional and policy analysis of river basin management: the Warta River Basin, Poland  

Microsoft Academic Search

The authors describe and analyze the emergence of river basin management in the Warta River Basin of Poland. The Warta basin's 55,193 km2 cover approximately one-sixth of Poland, and the Warta is a principal tributary to the Oder. Water management issues include pollution of the Warta and its main tributaries, prompting cities to rely on groundwater supplies that are beginning

William Blomquist; Andrzej Tonderski; Ariel Dinar

2005-01-01

402

The Donets Basin (Ukraine\\/Russia): coalification and thermal history  

Microsoft Academic Search

The Donets Basin (Donbas) is one of the major late Paleozoic coal basins in the world. The Donbas Foldbelt is an inverted part of the Donets Basin characterized by WNW–ESE-trending folds and faults. The age of basin inversion is under discussion. Large parts of the Donets Basin host anthracite and meta-anthracite. Low-rank coals are restricted to the western and northern

R. F. Sachsenhofer; V. A. Privalov; M. V. Zhykalyak; C. Bueker; E. A. Panova; T. Rainer; V. A. Shymanovskyy; R. A. Stephenson

2002-01-01

403

Basin development and petroleum prospects of central New Hebrides arc  

SciTech Connect

Two extensive intra-arc basins, the Central basin of Vanuatu and the Vanikolo basin, have recently been mapped in detail and appear to have developed in the last 3 m.y. primarily from subduction and arc-polarity reversal. The Central basin of Vanuatu is being modified by the ridge-arc collision and is still accumulating sediment, whereas the Vanikolo basin has no physiographic expression and is completely filled with sediment. Quaternary volcanism has separated the Central basin of Vanuatu into two physiographic basins (North Aoba and South Aoba basins). The Central basin is flanked on the west by five smaller insular basins associated with the islands of Malakula and Espiritu Santo. Although North and South Aoba basins lie in water depths as great as 3 km, migration paths into the shallower water basins appear to be present, and structures that could trap hydrocarbons occur. More than 5 km of sediment of Miocene and younger age were deposited in the deeper basins, whereas 2-km thick sediments of late Miocene and younger age occur near the islands. The most promising hydrocarbon basin is Malakula basin, which lies on the eastern shelf of Malakula Island, where onshore source rock analyses indicated potential gas concentrations. North of the Central basin of Vanuatu lies the largest basin in the region, the Vanikolo basin, covering more than 14,000 km/sup 2/ and containing more than 6 km of probablen Miocene and younger sediment. Water depths are more than 2 km in the deepest part of this basin, but much of the margins lie in water less than 1 km deep. Structures along the margins could trap hydrocarbons, especially along the western side, and are accessible to drilling. More work must be done in Vanikolo basin to assess hydrocarbon source rocks, migration, and heat flow before a comprehensive hydrocarbon evaluation can be made.

Greene, H.G.; Wong, F.L.; Falvey, D.A.; MacFarlan