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1

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

Microsoft Academic Search

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

Banabehari Mishra; Krishna Lal Pandya; Wataru Maejima

2004-01-01

2

Kinematics of the Gondwana basins of peninsular India  

Microsoft Academic Search

The Gondwana successions (1–4 km thick) of peninsular India accumulated in a number of discrete basins during Permo-Triassic period. The basins are typically bounded by faults that developed along Precambrian lineaments during deposition, as well as affected by intrabasinal faults indicating fault-controlled synsedimentary subsidence. The patterns of the intrabasinal faults and their relationships with the respective basin-bounding faults represent both

Chandan Chakraborty; Nibir Mandal; Sanjoy Kumar Ghosh

2003-01-01

3

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

4

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

NASA Astrophysics Data System (ADS)

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 arc signatures in the lavas, suggesting a well-developed Late Cretaceous volcanic arc system active in the New Caledonia sector of the eastern Gondwana margin, possibly extending as far south as New Zealand. There are two distinct suites of lavas in the Nouméa Basin. The older lavas are predominately mafic, low to high-K, and have a calc-alkaline fractionation trend. Chondrite normalised trace element plots show patterns that are light rare earth element (LREE) enriched, and mid-ocean ridge basalt (MORB) normalised trace element plots show enrichment of most incompatible trace elements with discernable negative Nb, Ta and Ti anomalies. Trace element ratios identify a continental arc signature in these lavas which were generated from an N-MORB-like source. Overlying the mafic lavas is a sequence of younger voluminous siliceous, generally subalkaline lavas (+/-88 Ma). These lavas are LREE enriched with slight positive Nb-Ta anomalies and negative Eu and Ti anomalies. The geochemical data indicates these lavas have within plate characteristics with minor continental affinities and an enriched source. We propose that the older mafic lavas were generated during large scale subduction under the eastern Gondwana margin during the Late Cretaceous. Whereas the younger lavas may have been generated during extension; caused by slab roll-back of the subduction system along the Southwest Pacific plate boundary. The presence of fragments of a detached slab in this process would result in lavas chemically similar to those found in the Nouméa Basin, with minor continental characteristics, and generated from an enriched mantle source. What is of fundamental importance is the evidence that the arc system extended from New Caledonia southwards to New Zealand and was likely contemporaneous.

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

2011-07-01

5

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

NASA Astrophysics Data System (ADS)

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

Richiano, Sebastián

2014-10-01

6

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

E-print Network

for the Cretaceous seafloor-spreading history of East Gondwana result in unlikely tectonic scenarios for at least one northwest of Australia, and reached the southern tip of India at ~126 Ma. Seafloor spreading in the Enderby that seafloor spreading between them progressed from south to north from 94 to 84 Ma. This timing is essential

Müller, Dietmar

7

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

8

Gondwana to Asia: Preface  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

9

Gondwana sedimentation in the Pranhita Godavari Valley: a review  

NASA Astrophysics Data System (ADS)

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

Sengupta, Supriya

2003-03-01

10

A model of plate kinematics in Gondwana breakup  

NASA Astrophysics Data System (ADS)

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

Eagles, Graeme; König, Matthias

2008-05-01

11

PLANT CONSERVATION IN TEMPLE YARDS OF ORISSA  

PubMed Central

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

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

1997-01-01

12

Trace element geochemistry of river sediment, Orissa State, India  

E-print Network

Trace element geochemistry of river sediment, Orissa State, India K.O. Konhausera , M.A. Powellb analyses of bottom sediment from rivers flowing through Orissa State, India indi- cated that trace element% of the allochthonous sediments (Subramanian, 1979). In contrast, the major southern Peninsular rivers (i.e. Krishna

Konhauser, Kurt

13

Principal stresses flipping during the East- West-Gondwana collision  

NASA Astrophysics Data System (ADS)

During the Precambrian-Cambrian transition, the Arabian-Nubian Shield underwent final assembly and accretion to the Saharan Metacraton concurrent with the assembly of eastern and western Gondwana. The Arabian-Nubian Shield consisted of volcanic island-arc terranes, equivalent intrusions and the connecting oceanic crust. During the eastern and western Gondwana collision, the oceanic crust was thrust over the arc terranes and several shear zones were activated. Najd Fault System - the largest pre-Mesozoic shear zone on Earth - is one of these shear zones. Exhumation of mid-crustal level rocks (high-grade gneisses) as metamorphic complexes is closely connected to the activity of the Najd Fault System. In Eastern Desert of Egypt, high-grade rocks were exhumed in extension setting as classical metamorphic core complexes. In contrast, in Sinai, they were exhumed in an oblique transpression regime. In order to investigate reasons for this difference, a current project deals with the exhumation mechanism of the mid-crustal rocks in other parts of the Najd Fault System, namely in the Arabian part of the shield (Saudi Arabia). First results of fieldwork show that the geographic position of molasse basins, typically spatially associated with the gneiss domes, is different in the Eastern Desert than in Saudi Arabia. In Eastern Desert, these basins are located to the northwest and the southeast of the metamorphic complexes. In Saudi Arabia the basins are to the east and the west of the complexes. The geographic position of the molasse basins with respect to the metamorphic complexes and the overall geometry of the Najd Fault System may indicate that the principal stresses (?2 and ?3) of the system were flipped from the east to the west of the Arabian-Nubian Shield. Petrological and age dating work are currently in progress to check the field observations.

Abu-Alam, T.; Stüwe, K.

2012-04-01

14

Some observational aspects and modeling results of the Orissa super cyclone, October 1999  

NASA Astrophysics Data System (ADS)

The super cyclone that crossed the Orissa coast near Paradeep port (20.3 N, 86.7 E) around 0600 UTC on 29 October 1999, caused enormous damage - death of 10,000 people and 400,000 cattle, property damage worth Ind. Rs. 10,000 crores ( about USD 2 billion), salinization of about 1.8 million hectares of agricultural land, destruction of paddy crop paddy crop worth Ind. Rs.1,500 crores (USD 300 million), and severe damage to transmission lines, power supply, roads and buildings sustained severe damages. This cyclone was identified as a low pressure in the Gulf of Thailand on 24th October 1999. It moved westwards and gradually intensified reaching the intensity of a severe cyclonic storm on 27 October. The cyclone further intensified reaching very high intensity to be called as a super cyclone when it crossed the Orissa coast near Paradeep around 0600 UTC of 29 October. The observational installations on the Orissa coast were severely damaged and failed to record. However rough estimates have been made using the satellite and radar pictures. Average speed of the storm was about 20 km/hour and increased to 30 km/hour while intensifying, but reduced before and after crossing the coast. The central surface pressure is estimated as 912 hPa on 29 October with the T-number as T7; correspondingly the maximum wind speed is estimated as 260 km/hour with the radius of the eye at 15 km. Heavy rainfall was reported on 29, 30 and 31 October with maximum amounts of 955 mm in Bhadrak district of Orissa and 600-800 mm in Mahanadi river basin. A storm surge of 5 to 6m above the astronomical tide is reported at Paradeep on 29 October. All the above parameters, namely, strong winds with gale, torrential rains with heavy rainfall rate and high storm surge, caused the devastation. An attempt has been made to simulate the intensification and movement of the cyclone using a high resolution mesoscale model. The simulation study indicated that the models are capable of predicting the intensification of the storm as well as the movement. However the model errors range below 50 km with respect to the track.

Rao, N. J.; Rao, D. B.

2001-05-01

15

Evaporitic constraints on the southward drifting of the western Gondwana margin during Early Cambrian times  

Microsoft Academic Search

Lower Cambrian evaporites and carbonates are reported from nearly all the platforms of the western Gondwana margin, which comprises the Souss, Ossa–Morena, Cantabro-Iberian, Armorican and Montagne Noire–Sardinian Basins. Both lithologies were deposited in climatically restricted belts and their changing palaeogeographic distributions, according to recent biostratigraphic correlations, are used to infer the latitudinal motion of this margin. As a result, the

J. J. Álvaro; J. M. Rouchy; T. Bechstädt; A. Boucot; F. Boyer; F. Debrenne; E. Moreno-Eiris; A. Perejón; E. Vennin

2000-01-01

16

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

17

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

18

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

NASA Astrophysics Data System (ADS)

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

Metcalfe, I.

2013-04-01

19

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

20

A unified Lower - Middle Cambrian chronostratigraphy for West Gondwana  

Microsoft Academic Search

Similarities in biotic successions support a unified, composite chronostratigraphy for the Lower-Middle Cambrian of the Iberian and Moroccan margins of West Gondwana. The Cordubian Series (emended from an Iberian stage-level unit) com- prises the sub-trilobitic Lower Cambrian of West Gondwana. This series represents ca. half of the Cambrian (ca. 25 m.y.), has a base defined at the lowest occurrence of

GERD GEYER; ED LANDING

2004-01-01

21

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

22

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

USGS Publications Warehouse

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

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

1998-01-01

23

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

SciTech Connect

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

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

1993-03-01

24

East Antarctic Rift Systems - key to understanding of Gondwana break-up  

NASA Astrophysics Data System (ADS)

The results of analysis of radio-echo sounding surveys, the RADARSAT satellite data, magnetic and gravity information give evidence that East Antarctica contains 13 riftogenic systems and/or large linear tectonic structures. Among known and suggested rifts of East Antarctica the Lambert rift has a pivotal position and it manifests oneself as symmetry axis. Six additional systems are revealed on both sides of it and any one of them possesses special features in geologic and geomorphologic aspects. In most cases they inherited the anisotropy of long-lived cratonic blocks. Riftogenic and/or large linear tectonic structures along the East Antarctica coastal regions are distributed with a steady regularity with average distance between them about 650 km. For six (7) structures from 13 (Lambert, Jutulstraumen-Pencksökket, Vestfjella, Mellor-Slessor (Bailey), Wilkes Basin, Gaussberg (?) and Rennick) there is a distinct spatial coupling with trough complexes of the Beacon Supergroup and their subsequent reactivation in Late Jurassic - Permian time when the East Gondwana started break-up. Rift system of the Lambert-Amery Glaciers and Prydz Bay is related to Mesozoic extension events and it inherited structures of Paleozoic grabens. The total length of the rift system exceeds 4000 km of the same scale as largest the World rift belts. The length of the western branch of the Lambert rift that includes the Mellor rift and graben-like structures of the Bailey and Slessor glaciers exceeds 2300 km. Results of radio-echo sounding investigation of the subglacial Aurora Basin allow to suggest that this large basin of sub-meridian extension is underlain by an extensive (> 1000 km) riftogenic structure that is running towards the Transantarctic Mountains where it forms a triple junction with the eastern branch of the Lambert rift and structures of the Wilkes Basin. It is hereby proposed that Aurora-Scott rift is formed by complex system of sub-parallel depressions divided by fragmentary horsts. The spatial correlation of the Aurora-Scott rift system, Permian basins of the Western Australia margin and coal-bearing basins in Rajmahal Hills allows suggesting that this East Antarctic structure was also formed during Permian time and about the existence of triple junction rift systems (Aurora-Scott, Perth, Rajmahal) in the pre-breakup Gondwana.

Golynsky, D. A.; Golynsky, A. V.

2012-04-01

25

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

PubMed

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

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

2013-07-01

26

Revealing the continental margin of Gondwana: the Ordovician arc of the Cordón de Lila (northern Chile)  

NASA Astrophysics Data System (ADS)

The tectonic evolution of the proto-Andean margin of western Gondwana has been commonly seen in terms of terrane accretion processes, requiring the existence of early Palaeozoic terrane boundaries and associated sutures. A new study of the Cordón de Lila Ordovician volcano-sedimentary successions in northern Chile reveals for the first time an arc assemblage deposited on thin crust within a continental arc system, having regional implications. Primitive basalts, rhyolites, volcanogenic wackes and siltstones are associated, bearing not only debris from mainly arc sources but also basement rocks; the latter is only accessory in the form of metamorphic lithoclasts and detrital zircons with ages around 1.0 Ga. Magmatic zircons in rhyolites reveal an eruptive age of ca. 478 Ma, concordant with Upper Arenigian to Lower Llanvirnian ages of brachiopods in overlying conglomerates. Bimodal volcanic associations, including low-K tholeiites, characterize the magmatic rocks, with evolved rhyolitic rocks showing pronounced arc-like geochemical signatures (negative anomalies in Ti, Nb and Ta). Some of the basaltic rocks are tholeiitic and display Ce/Y ratios below 1 and might point to a Moho depth of less than 10 km, hence a thin continental crust, coinciding with depletions in Zr and Hf concentrations. Associated volcaniclastic rocks display generally low Th/Sc (0.4-1), La/Sc (mostly <3.5), Zr/Sc (6-20) and high Ti/Zr (~10-60) ratios. The rock succession resembles the same geochemical and lithostratigraphical trends as retro-arc basin deposits further east in the Argentinean Puna of similar age. However, in the Cordón de Lila, the intercalated mafic rocks are less evolved, and the percentage of arc debris is higher, while the percentage of metamorphic lithoclasts and rounded quartz grains is much lower, indicating the existence of a thinned continental margin underpinning. We propose a transition in the Ordovician of the Central Andes from trench-ward fore-arc deposits to a dominantly intra-arc basin (Cordón de Lila), transitioning further eastwards towards a retro-arc basin (Puna) and foreland basin deposits of the Cordillera Oriental of northwestern Argentina. The Cordón de Lila intra-arc assemblage and associated fore-arc basin deposits therefore defined the western margin of Gondwana during the Ordovician. The absence of any terrane boundaries and sutures across strike is consistent with an evolving continental margin arc constructed on attenuated crust of the proto-Andean margin.

Zimmermann, Udo; Niemeyer, Hans; Meffre, Sebastien

2010-10-01

27

The basins on the Argentine continental margin  

SciTech Connect

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

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

1996-08-01

28

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

29

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

30

Panjal Paleomagnetism: Implications for Early Permian Gondwana break-up  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

31

Impact of Joint Forest Management (JFM) on Environmental Stress MigrationEvidence from Orissa  

Microsoft Academic Search

In this study, an attempt has been made to unravel the impact of forest protection committees (FPCs) under JFM on stress migration in four forest divisions of Orissa. In order to undertake this study, field investigations have been carried out in 12 villages of four forest divisions of the state. Our study has covered 318 households comprising of landless and

Naresh Chandra Sahu; Binayak Rath

2010-01-01

32

Population status of mangrove species in estuarine regions of Orissa coast, India  

Microsoft Academic Search

The mangrove ecosystems are store-house of economically important resources like trees, fishes and prawns and other marine organisms. The present study highlights the effect of natural and man induced stresses on regeneration and population status of mangroves of Bhitarkanika National Park, Orissa. The species such as Cynometra ramiflora , Rhizophora mucronata and Sonneratia apetala had lesser number of juveniles compared

V. P. UPADHYAY; P. K. MISHRA

33

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

34

Traditional Phytotherapy for Diarroeal Diseases in Dhenkanal district of Orissa, India  

PubMed Central

Medico- etnobotanical exploration carried out in Dhenkanal district of Orissa during 1996-98 reveal that, people use 21 plant species belonging o 20 genera and 17 families on 10 different combinations for the treatment of diarrehoeal diseases. The method of preparation of medicine and details of application care recorded. PMID:22557011

Mohant, R.B; Rout, M.K.

2001-01-01

35

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

ERIC Educational Resources Information Center

Examined the relationship between a host of family characteristics and indicators of adolescent competence in 107 eighth and ninth graders in Orissa state, India. Families of more socially competent students tended to be verbally and emotionally expressive, and democratic with respect to discipline, input, and decision making. (SLD)

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

1999-01-01

36

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

PubMed Central

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

Dash, Sudhansu S.; Misra, Malaya K

1996-01-01

37

Neoproterozoic geodynamic evolution of SW-Gondwana: a southern African perspective  

NASA Astrophysics Data System (ADS)

Our current understanding of the tectonic history of the principal Pan-African orogenic belts in southwestern Africa, reaching from the West Congo Belt in the north to the Lufilian/Zambezi, Kaoko, Damara, Gariep and finally the Saldania Belt in the south, is briefly summarized. On that basis, possible links with tectono-stratigraphic units and major structures on the eastern side of the Río de la Plata Craton are suggested, and a revised geodynamic model for the amalgamation of SW-Gondwana is proposed. The Río de la Plata and Kalahari Cratons are considered to have become juxtaposed already by the end of the Mesoproterozoic. Early Neoproterozoic rifting led to the fragmentation of the northwestern (in today's coordinates) Kalahari Craton and the splitting off of several small cratonic blocks. The largest of these ex-Kalahari cratonic fragments is probably the Angola Block. Smaller fragments include the Luis Alves and Curitiba microplates in eastern Brazil, several basement inliers within the Damara Belt, and an elongate fragment off the western margin, named Arachania. The main suture between the Kalahari and the Congo-São Francisco Cratons is suspected to be hidden beneath younger cover between the West Congo Belt and the Lufilian/Zambezi Belts and probably continues westwards via the Cabo Frío Terrane into the Goiás magmatic arc along the Brasilia Belt. Many of the rift grabens that separated the various former Kalahari cratonic fragments did not evolve into oceanic basins, such as the Northern Nosib Rift in the Damara Belt and the Gariep rift basin. Following latest Cryogenian/early Ediacaran closure of the Brazilides Ocean between the Río de la Plata Craton and the westernmost fragment of the Kalahari Craton, the latter, Arachania, became the locus of a more than 1,000-km-long continental magmatic arc, the Cuchilla Dionisio-Pelotas Arc. A correspondingly long back-arc basin (Marmora Basin) on the eastern flank of that arc is recognized, remnants of which are found in the Marmora Terrane—the largest accumulation of oceanic crustal material known from any of the Pan-African orogenic belts in the region. Corresponding foredeep deposits that emerged from the late Ediacaran closure of this back-arc basin are well preserved in the southern areas, i.e. the Punta del Este Terrane, the Marmora Terrane and the Tygerberg Terrane. Further to the north, present erosion levels correspond with much deeper crustal sections and comparable deposits are not preserved anymore. Closure of the Brazilides Ocean, and in consequence of the Marmora back-arc basin, resulted from a change in the Río de la Plata plate motion when the Iapetus Ocean opened between the latter and Laurentia towards the end of the Ediacaran. Later break-up of Gondwana and opening of the modern South Atlantic would have followed largely along the axis of the Marmora back-arc basin and not along major continental sutures.

Frimmel, H. E.; Basei, M. S.; Gaucher, C.

2011-04-01

38

Taphonomic analysis in lacustrine environments: Two different contexts for Triassic lake paleofloras from Western Gondwana (Argentina)  

NASA Astrophysics Data System (ADS)

During the earliest Triassic several rift basins developed along the western margin of Gondwana associated with the pre-breakup of Pangea. They were filled by exclusively non-marine sediments including alluvial, fluvial, and lacustrine deposits. In the Ischigualasto-Villa Unión Basin, the lacustrine-deltaic succession is placed in the Los Rastros Formation and consists of several coarsening-upward cycles of black shale, siltstone, and sandstone. The paleontologic content of the succession includes abundant floral remains (related to the Dicroidium-type flora), invertebrates (conchostracans, insects), and vertebrates (fishes, a temnospondyl amphibian, ichnites). At the Cerro Puntudo area in the Cuyana Basin, the lacustrine succession forms the upper part of the Cerro Puntudo Formation and consists of limestone, stromatolitic limestone, mudstone, sandstone, and tuff. The paleontologic content includes scarce floral remains and rhizoliths; invertebrates are represented exclusively by traces (associated with ichnofacies of Skolithos and Scoyenia), and vertebrates by a fragment of the pelvic girdle of a basal arcosaur. The taphonomic analysis performed in the two Triassic lacustrine successions allows recognition of two different taphonomic histories for the plant remains. The Los Rastros lake preserved both autochthonous (originated in the littoral zone) and allochthonous (originated in the upstream fluvial system) elements. The offshore lacustrine area was dominated by autochthonous well-preserved elements and allochthonous plant debris and wood, which formed time-averaged accumulations. The delta deposits are characterized by allochthonous elements with varied preservational conditions, usually showing evidence of mechanical degradation and accumulation within a short time. Autochthonous and allochthonous material were preserved in the Los Rastros Lake by means of anoxic conditions in the offshore lacustrine area and high sedimentation rates in the delta. In contrast, the Cerro Puntudo Lake preserved only autochthonous elements (originated in the littoral zone), including rhizoliths and foliar material, which formed autochthonous and parautochthonous accumulations at the littoral zone in spite of aerobic conditions. This was the result of tuffaceous material that enhanced preservation. Thus, these very different lacustrine environmental contexts are showing different preservational modes. The fossil assemblages allowed the reconstruction of the original communities from this part of Gondwana. Thus, the Los Rastros lake margins were characterized by shrubs and small trees of Ginkgoales and Corystospermales, and herbaceous members of the Sphenophyta. The sphenophytes were also the dominant floral component along the river margins whereas the Corystospermales, Cycadales, Pteridophyta, and conifers formed the woodland upstream probably related to the floodplains of a trunk fluvial system. The littoral zone of the Cerro Puntudo Lake was dominated mainly by herbaceous sphenophytes and lycopsids. These fossil assemblages characterize the paleoflora associated with lacustrine systems. A fuller understanding of the processes that generate these assemblages is essential for comparisons with other continental paleobotanical records in the Middle Triassic of Gondwana (e.g., Australia, South Africa).

Mancuso, Adriana Cecilia

2009-12-01

39

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

NASA Astrophysics Data System (ADS)

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

Davy, Bryan

2014-08-01

40

Impact of alphacypermethrin treated bed nets on malaria in villages of Malkangiri district, Orissa, India  

Microsoft Academic Search

The impact of use of bed-nets treated with alphacypermethrin, at 20mg (ai)\\/m2, in comparison to untreated nets or no nets on malaria vectors and malaria incidence was studied in tribal villages of Malkangiri district, Orissa state, India, which are highly endemic for falciparum malaria. Treated or untreated nets were supplied to the villagers in June 1999 and the nets were

S. S Sahu; P Jambulingam; T Vijayakumar; S Subramanian; M Kalyanasundaram

2003-01-01

41

Natural radioactivity measurements in beach sand along southern coast of Orissa, eastern India  

Microsoft Academic Search

The beach placer deposits in the southern coastal Orissa, India may have significant levels of radiation due to the presence\\u000a of Th and U bearing minerals such as monazite and zircon. In this study, Gopalpur and Rushikulya beach regions were selected\\u000a to study the ambient radiation environment. The average activity concentrations of radioactive elements such as 232Th, 238U and 40K

N. Sulekha Rao; D. Sengupta; R. Guin; S. K. Saha

2009-01-01

42

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

PubMed

Fossil crocodyliforms discovered in recent years have revealed a level of morphological and ecological diversity not exhibited by extant members of the group. This diversity is particularly notable among taxa of the Cretaceous Period (144-65 million years ago) recovered from former Gondwanan landmasses. Here we report the discovery of a new species of Cretaceous notosuchian crocodyliform from the Rukwa Rift Basin of southwestern Tanzania. This small-bodied form deviates significantly from more typical crocodyliform craniodental morphologies, having a short, broad skull, robust lower jaw, and a dentition with relatively few teeth that nonetheless show marked heterodonty. The presence of morphologically complex, complementary upper and lower molariform teeth suggests a degree of crown-crown contact during jaw adduction that is unmatched among known crocodyliforms, paralleling the level of occlusal complexity seen in mammals and their extinct relatives. The presence of another small-bodied mammal-like crocodyliform in the Cretaceous of Gondwana indicates that notosuchians probably filled niches and inhabited ecomorphospace that were otherwise occupied by mammals on northern continents. PMID:20686573

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

2010-08-01

43

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

44

Body form and nutritional status among adult males of different social groups in Orissa and Bihar States in India.  

PubMed

This paper aims to carry out a biological investigation of the body form and nutritional status of the major social groups of Orissa and Bihar States in India. For this, Cormic Index (CI) and Body Mass Index (BMI) have been computed using data on height, sitting height and weight, taken from adult males of age 18-62 years of various ethnic groups in these two states. The subjects have been classified on the basis of chronic energy deficiency (CED). It is found that a substantial proportion of the people with CED are in the grade II and grade III categories. ANOVA, t-tests, correlation and regression were carried out separately. The results reveal that in Orissa, Scheduled Tribes are shorter, lighter and have lowest mean values of BMI and Cormic Index compared to other groups, but in Bihar, though the Scheduled Tribes are shorter, Scheduled Castes are lower in weight and have the lowest mean values of BMI. There are significant differences in BMI as well as in CI between Scheduled Tribes of Orissa and Bihar. Scheduled Castes and Tribes of Bihar have the highest percentage of CED with 64.71% and 57.45%, respectively. Muslims of Bihar are also affected (52.95%), but overall prevalence of CED is lower in Orissa (49.11%) than in Bihar (54.62%). BMI and CI are highly correlated for each of the social groups in Bihar and Orissa. PMID:18501357

Chakrabarty, S; Pal, M; Bharati, S; Bharati, P

2008-01-01

45

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

46

Conservation genetics of a Gondwana relict rainforest tree, Nothofagus moorei (F. Muell.) Krasser.  

E-print Network

??Nothofagus moorei is a long-lived, Gondwana relict cool temperate rainforest tree. Nothofagus-dominated rainforests were widespread across much of eastern Australia during the mid-Tertiary but today,… (more)

Schultz, Lee

2008-01-01

47

Noise pollution in residential areas of Jharsuguda Town, Orissa (India) and its impact.  

PubMed

In this paper, an attempt has been made to study noise levels in different residential areas of Jharsuguda town in western Orissa (India). Minimum, maximum, L10, L50 and L90 noise levels have been computed. It was found that noise levels in the residential areas exceed the standards set by the Central Pollution Control Board, India. Vehicular traffic, with air horns of loud noise, was found to be the main reason for these high noise levels. Strict measures need to be taken to reduce and control the noise pollution. PMID:17915786

Patel, Rita; Tiwari, T N; Patel, T

2006-07-01

48

A monozygotic twin pair with ?-thalassemia carrier status in a Dudh Kharia tribal family of Orissa  

PubMed Central

BACKGROUND: The ?-thalassemia syndrome is a genetically inherited commonly encountered hematological disorder in the state of Orissa. It causes high degree of morbidity, mortality and fetal wastage in the poor vulnerable people. AIMS AND OBJECTIVES: There is an equal probability (50% chance) in every singleton pregnancy that a carrier parent of ?-thalassemia major would either bear normal or carrier offspring, but not two offspring with carrier of ?-thalassemia major genotype together. For the first time, a carrier parent of ?-thalassemia major gene has born progeny (three daughters and a twin male offspring) with a carrier status of ?-thalassemia major in Dudh Kharia tribal family studied from Sundargarh district of Orissa. MATERIALS AND METHODS: We screened randomly selected population of Dudh Kharia tribe from Sundargarh district of Orissa for hemoglobinopathies to assess the extent of the problem, design possible interventions and provide genetic counseling to them. A family with twin children was identified during screening in Lata Gaon in Bargaon block of Sundargarh district of Orissa for the above-mentioned study. Background information for this family such as name, age, sex, tribe, native place, reproductive history, family pedigree and clinical signs and symptoms were also recorded. Standardized genetic and hematological procedures and techniques were followed for analysis. RESULTS: Laboratory investigations for alkaline electrophoresis of blood lysate on cellulose acetate membrane showed raised hemoglobin A2 level in mother (Hb A2 = 5.3%), in three daughters (Hb A2 =6.5, 5.9, 5.5% in chronological and birth order), in two twin sons (Hb A2 =5.9% and 6.0%) and normal (Hb A2 = 3.3%) for father. Hence, all the children i.e., three daughters and two twin sons, including the mother were ?-thalassemia carriers. Since all the hematological parameters i.e., red cell indices, G-6-PD enzyme activity, ABO and Rhesus blood groups and identical ?-thalassemia (trait) genotypes with identical clinical manifestations and hematological profile of the twin sons under similar environmental conditions, hence they were labeled as identical monozygotic twins. CONCLUSIONS: It is a rare occasion when a single pregnancy carries either one or two abnormal genotypes at a time in a womb in human beings. Monozygotic twins are genetically alike and provide appraisal of the expression of identical genotype under the different environmental conditions. PMID:21957337

Balgir, R. S.

2007-01-01

49

Arabian Shield magmatic cycles and their relationship with Gondwana assembly: Insights from zircon U-Pb and Hf isotopes  

NASA Astrophysics Data System (ADS)

The Arabian Shield preserves a protracted magmatic record of amalgamated juvenile terranes that host a diverse range of early Neoproterozoic to Cambrian granitoids intruding volcanosedimentary basin assemblages that have corollaries in other parts of the East African Orogen. New zircon U-Pb geochronology of 19 granitoids intruding eight Arabian Shield terranes, define four discrete magmatic events: island arc (?845 Ma), syncollisional (?710 Ma), post-tectonic (?620 Ma) and anorogenic (?525 Ma). Zircon Lu-Hf isotopic analyses indicate that all studied granitoids are juvenile with typical ?Hf values of >+5 to +10 and Stenian-Tonian (?1100-900 Ma) model ages, regardless of their precise intrusive ages or spatial relationship. Subtle changes in isotopic signatures between ?850 and 600 Ma, suggest the result from changes in granite source materials brought about by; basaltic underplating, limited crustal interaction with Palaeoproterozoic basement and a change to lithospheric delamination/subduction roll-back processes driving juvenile ANS crustal growth. The cycle of granite intrusion reflects accretionary cycles initiated during Mozambique Ocean closure and during Gondwana amalgamation and final assembly. Post-tectonic magmatism is divided into a ?636-600 Ma phase and post 600 Ma event that reflects first subduction and then within-plate related processes. The identification of magmatism at ?525 Ma is now the youngest granitoid identified so far in the Saudi Arabian Shield and may change the identified age of the regional, basal Palaeozoic unconformity. This late magmatism may be generated by the Najd Fault reactivation correlating with the Malagasy/Kunnga Orogeny that marked the final stages of Gondwana assembly.

Robinson, F. A.; Foden, J. D.; Collins, A. S.; Payne, J. L.

2014-12-01

50

Shame or subsidy revisited: social mobilization for sanitation in Orissa, India  

PubMed Central

Abstract Objective To determine the effectiveness of a sanitation campaign that combines “shaming” (i.e. emotional motivators) with subsidies for poor households in rural Orissa, an Indian state with a disproportionately high share of India’s child mortality. Methods Using a cluster-randomized design, we selected 20 treatment and 20 control villages in the coastal district of Bhadrak, rural Orissa, for a total sample of 1050 households. We collected sanitation and health data before and after a community-led sanitation project, and we used a difference-in-difference estimator to determine the extent to which the campaign influenced the number of households building and using a latrine. Findings Latrine ownership did not increase in control villages, but in treatment villages it rose from 6% to 32% in the overall sample, from 5% to 36% in households below the poverty line (eligible for a government subsidy) and from 7% to 26% in households above the poverty line (not eligible for a government subsidy). Conclusion Subsidies can overcome serious budget constraints but are not necessary to spur action, for shaming can be very effective by harnessing the power of social pressure and peer monitoring. Through a combination of shaming and subsidies, social marketing can improve sanitation worldwide. PMID:19705007

Yang, Jui-Chen; Dickinson, Katherine L; Poulos, Christine; Patil, Sumeet R; Mallick, Ranjan K; Blitstein, Jonathan L; Praharaj, Purujit

2009-01-01

51

The delivery of veterinary services to poorer communities: the case of rural Orissa, India.  

PubMed

This paper presents the results of a field survey on use patterns and demand for clinical veterinary services in one of the poorest states of India, namely, Orissa. A demand function was estimated using Poisson regression and demand elasticities were obtained for various income groups. The survey shows that large numbers of households, including the poor, pay prices that are significantly higher than those prescribed. There is no targeting of cheaper services towards the poor. The analysis also suggests that for a given service and place of service, the poor actually paid more on a per veterinary visit basis. As a result, the rate of service utilisation was significantly lower for poor households. Demand analysis confirmed that the demand for veterinary services is not determined by subsidised service delivery, but by access to output markets and general awareness levels. In the light of these findings, the paper makes a number of recommendations for redefining the role of the Government in veterinary service delivery in Orissa. PMID:15005551

Ahuja, V; Morrenhof, J; Sen, A

2003-12-01

52

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

PubMed Central

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

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

2014-01-01

53

Gondwana Tales: an inquiry approach to plate tectonics  

NASA Astrophysics Data System (ADS)

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

Domènech Casal, Jordi

2014-05-01

54

Neoproterozoic to Lower Palaeozoic successions of the Tandilia System in Argentina: implication for the palaeotectonic framework of southwest Gondwana  

NASA Astrophysics Data System (ADS)

The Cryogenian to Uppermost Ediacaran successions of the Tandilia System (Sierras Bayas Group and Cerro Negro Formation) in central-eastern Argentina is exceptional because of its unmetamorphosed and nearly undeformed character, its sediment provenance trend and the absence of any identified glacial deposit and the deposition of warm water carbonates. We decipher a dramatic change in the basin evolution from small-scale depositional areas during the Neoproterozoic to a larger basin related to an active continental margin throughout the Uppermost Ediacaran. The base of the succession is represented by immature detritus of alkaline composition (Villa Mónica Formation), but towards the top of this formation, the material is sorted and reworked, nonetheless still reflecting in its detritus the local rocks. The clastic deposition is interrupted by diagenetic overprinted dolomites. The unconformable overlying quartz-arenitic Ediacaran Cerro Largo Formation reworked the Cryogenian Villa Mónica Formation and contains mainly felsic granitic and metamorphic basement material of slightly wider variety, while the dominant alkaline geochemical signature in rocks of the Villa Mónica Formation disappears. Based on diagenetic, petrographic and sedimentological data, we can interpret the unconformity representing a longer time of erosion. The Cerro Largo Formation shows a transition to mudstones and the heterolithic facies of the Olavarría Formation. The top of the Sierras Bayas Group is represented by limestones (Loma Negra Formation), which are discordantly overlain by the Uppermost Ediacaran Cerro Negro Formation. The latter displays detrital material derived from a continental arc, mafic and felsic sources. Several arc-related geochemical proxies (Th/Sc < 0.8; Zr/Sc < 10; La/Sc < 2; Ti/Zr > 20) are recorded in the sediment detritus, as are syn-depositional pyroclastites. The absence of volcanic material in the underlying rocks allows proposing that the Cerro Negro Formation is related to an active continental margin fringing Gondwana ("Terra Australis Orogen") as a retro-arc or retro-arc foreland basin.

Zimmermann, Udo; Poiré, Daniel G.; Peral, Lucía Gómez

2011-04-01

55

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

PubMed

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

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

2005-02-01

56

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

57

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

NASA Astrophysics Data System (ADS)

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

Ghazi, Shahid; Mountney, Nigel P.

2012-10-01

58

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

PubMed Central

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

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

2011-01-01

59

Gondwana Research, V. 7, No. 2, pp. 407-424. 2004 International Association for Gondwana Research, Japan.  

E-print Network

in the seafloor spreading segments, major faults, basins, seamounts and other manifestations of magmatism. The collision of the Indian subcontinent with the Eurasian plate in the northwest, back-arc spreading features of the area. A map of Bouguer gravity anomaly is derived in conjunction with available seafloor

60

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

61

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

Microsoft Academic Search

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

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

2007-01-01

62

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

63

Triassic synthems of southern South America (southwestern Gondwana) and the Western Caucasus (the northern Neotethys), and global tracing of their boundaries  

NASA Astrophysics Data System (ADS)

Global tracing of the key surfaces of Triassic deposits may contribute significantly to the understanding of the common patterns in their accumulation. We attempt to define synthems - disconformity-bounded sedimentary complexes - in the Triassic successions of southern South America (southwestern Gondwana, Brazil and Argentina) and the Western Caucasus (the northern Neotethys, Russia), and then to trace their boundaries in the adjacent regions and globally. In southern South America, a number of synthems have been recognized - the Cuyo Basin: the Río Mendoza-Cerro de las Cabras Synthem (Olenekian-Ladinian) and the Potrerillos-Cacheuta-Río Blanco Synthem (Carnian-Rhaetian); the Ischigualasto Basin: the Ischichuca-Los Rastros Synthem (Anisian-Ladinian) and the Ischigualasto-Los Colorados Synthem (Carnian-Rhaetian); the Chaco-Paraná Basin: the Sanga do Cabral Synthem (Induan), the Santa Maria 1 Synthem (Ladinian), the Santa Maria 2 Synthem (Carnian), and the Caturrita Synthem (Norian); western Argentina: the Talampaya Synthem (Lower Triassic) and the Tarjados Synthem (Olenekian?). In the Western Caucasus, three common synthems have been distinguished: WC-1 (Induan-Anisian), WC-2 (uppermost Anisian-Carnian), and WC-3 (Norian-lower Rhaetian). The lower boundary of WC-1 corresponds to a hiatus whose duration seems to be shorter than that previously postulated. The synthem boundaries that are common to southwestern Gondwana and the Western Caucasus lie close to the base and top of the Triassic. The Lower Triassic, Ladinian, and Upper Triassic disconformities are traced within the studied basins of southern South America, and the first two are also established in South Africa. The Upper Triassic disconformity is only traced within the entire Caucasus, whereas all synthem boundaries established in the Western Caucasus are traced partly within Europe. In general, the synthem boundaries recognized in southern South America and the Western Caucasus are correlated to the global Triassic sequence boundaries and sea-level falls. Although regional peculiarities are superimposed on the appearance of global events in the Triassic synthem architecture, the successful global tracing suggests that planetary-scale mechanisms of synthem formation existed and that they were active in regions dominated by both marine and non-marine sedimentation.

Ruban, Dmitry A.; Zerfass, Henrique; Pugatchev, Vladimir I.

2009-08-01

64

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

65

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

PubMed

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

Nayak, Prateep K; Berkes, Fikret

2008-05-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

67

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

68

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

69

Production and consumption of wild date palm sap and country liquor in two tribal village ecosystems of eastern Ghats of Orissa, India  

Microsoft Academic Search

Wild date palm sap and traditional liquor production and consumption in Bidyadharpur and Arakhapada tribal village ecosystems on Eastern Ghats of Orissa, India were intensively studied. Daily palm sap productivity was 656 and 92 ml tree?1 while the total annual production was 22902 and 106 l in Arakhapada and Bidyadharpur, respectively. Country liquor was mainly prepared from molasses and mohua

S. Jammi Naidu; Malaya K. Misra

1998-01-01

70

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

Microsoft Academic Search

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

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

2007-01-01

71

Emissions Of Greenhouse Gas And Biochemical Properties Of Soil From Bhitarkanika Mangrove,Orissa  

NASA Astrophysics Data System (ADS)

Coastal areas have been recognized as one of the major contributors to the atmospheric flux of greenhouse gases at local, regional and global scales. Mangrove forests are constantly affected from the anthropogenic activities mainly intensive cultivation. In a study in the tropical mangrove areas of Bhitarkanika sancturary, NE Orissa and adjoining paddy fields, a comparative estimation of emission rates of two climatologically important greenhouse gases, viz. CH4 and N2O were measured for monsoon and post-monsoon seasons. Methane emission was higher in paddy fields and varied from 2.22 to 6.0 mg.m-2.h-1 as compared to flux rates of 0.08 to 3.23 mg.m-2.h-1 from mangrove areas for the monsoon season. For the post-monsoon season, CH4 flux was higher although it maintained almost similar trend for the two ecosystems. In contrast, N2O emission flux was higher for mangrove sediments than the rice fields. Readily mineralizable carbon (RMC) and microbial biomass-C (MBC) contents were higher in the paddy soils than the native mangrove sediments so also dehydrogenase and FDA hydrolase activities, suggesting higher microbial activity in the paddy soils. Overall CH4 and N2O yields varied depending upon both the magnitude and chemical nature of the sediment C and N sources and microbial activity that were in turn affected by the salinity. Results indicate that paddy fields (anthropogenic intrusion) are bigger emitters of greenhouse gases than the mangrove sediments and together constitute a significant contributor to the global GHG budget.

Chauhan, R.; Adhya, T. K.; Ramanathan, A.

2008-12-01

72

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

PubMed Central

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

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

2014-01-01

73

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

74

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

NASA Astrophysics Data System (ADS)

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

Magendran, T.; Sanjeevi, S.

2014-12-01

75

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

76

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; Le Métour, Joël; Sergeev, Sergey; Tegyey, Monique

2013-02-01

77

Post-Gondwana geomorphic evolution of southwestern Africa: Implications for hte controls on landscape development from observations and numerical experiments  

NASA Technical Reports Server (NTRS)

The relationship between morphology and surficial geology is used to quantify the denudation that has occurred across southwestern Africa sicne the fragmentation of Gondwana during the Early Mesozoic. Two main points emerge. Signficant denudation, of the order of kilometers, is widespread except in the Kalahari region of the continental interior. The denudation is systematically distributed so that the continental exterior catchment, draining directly to the Cape basin, is denuded to a greater depth than the interior catchment inland of the Great Escarpment. The analysis also implies tha the majority of the denudation occurred before the beginning of the Cenozoic for both teh exerior and interior catchments. Existing models of landscape development are reviewed, and implications of the denudation chronology are incorporated into a revised conceptual model. This revision implies tha thte primary effect of rifting on the subsequent landscape evolution is that it generates two distinct drainage regimes. A marginal upwarp, or rift flank uplift, separates rejuvenated rivers that drain into the subsiding rift from rivers in the continetal interior that are deflected but not rejuvenated. The two catchments evolve independently unless they are integrated by breaching of hte marginal upwarp. If this occurs, the exterior baselevel is communicated to the interior catchment that is denuded accordingly. Denudation rates generally decrease as the margin evolves, and this decrease is reinforced by the exposure of substrate that is resistant to denudation and/or a change to a more arid climate. The observations do not reveal a particular style of smaller-scale landscape evolution, sucha s escarpment retreat, that is responsible for the differential denudation across the region. It is proposed that numerical model experiments, which reflect the observational insights at the large scale, may identify the smaller-scale controls on escarpment development if the model and natural systems are analogous. Four numerical experiments are presented in which the roles of antecedent topography, resistant substrate, climte change, and lowering the baselevel of the interior catchment are investigated for an initially high elevation margin bordered by an escarpment. The model results suggest several styles of landscape evolution that are compatible with the observations. Escarpments may retreat in a regular manner, but they also degrade and are destroyed, only to reform at the drainage divide between exterior and interior catchments.

Gilchrist, Alan R.; Kooi, Henk; Beaumont, Christopher

1994-01-01

78

Post-Gondwana geomorphic evolution of southwestern Africa: Implications for hte controls on landscape development from observations and numerical experiments  

NASA Astrophysics Data System (ADS)

The relationship between morphology and surficial geology is used to quantify the denudation that has occurred across southwestern Africa sicne the fragmentation of Gondwana during the Early Mesozoic. Two main points emerge. Signficant denudation, of the order of kilometers, is widespread except in the Kalahari region of the continental interior. The denudation is systematically distributed so that the continental exterior catchment, draining directly to the Cape basin, is denuded to a greater depth than the interior catchment inland of the Great Escarpment. The analysis also implies tha the majority of the denudation occurred before the beginning of the Cenozoic for both teh exerior and interior catchments. Existing models of landscape development are reviewed, and implications of the denudation chronology are incorporated into a revised conceptual model. This revision implies tha thte primary effect of rifting on the subsequent landscape evolution is that it generates two distinct drainage regimes. A marginal upwarp, or rift flank uplift, separates rejuvenated rivers that drain into the subsiding rift from rivers in the continetal interior that are deflected but not rejuvenated. The two catchments evolve independently unless they are integrated by breaching of hte marginal upwarp. If this occurs, the exterior baselevel is communicated to the interior catchment that is denuded accordingly. Denudation rates generally decrease as the margin evolves, and this decrease is reinforced by the exposure of substrate that is resistant to denudation and/or a change to a more arid climate. The observations do not reveal a particular style of smaller-scale landscape evolution, sucha s escarpment retreat, that is responsible for the differential denudation across the region. It is proposed that numerical model experiments, which reflect the observational insights at the large scale, may identify the smaller-scale controls on escarpment development if the model and natural systems are analogous. Four numerical experiments are presented in which the roles of antecedent topography, resistant substrate, climte change, and lowering the baselevel of the interior catchment are investigated for an initially high elevation margin bordered by an escarpment. The model results suggest several styles of landscape evolution that are compatible with the observations. Escarpments may retreat in a regular manner, but they also degrade and are destroyed, only to reform at the drainage divide between exterior and interior catchments.

Gilchrist, Alan R.; Kooi, Henk; Beaumont, Christopher

1994-06-01

79

Impact of Community-Based Lymphedema Management on Perceived Disability among Patients with Lymphatic Filariasis in Orissa State, India  

PubMed Central

Background Lymphatic filariasis (LF) infects approximately 120 million people worldwide. As many as 40 million have symptoms of LF disease, including lymphedema, elephantiasis, and hydrocele. India constitutes approximately 45% of the world's burden of LF. The Indian NGO Church's Auxiliary for Social Action (CASA) has been conducting a community-based lymphedema management program in Orissa State since 2007 that aims to reduce the morbidity associated with lymphedema and elephantiasis. The objective of this analysis is to evaluate the effects of this program on lymphedema patients' perceived disability. Methodology/Principal Findings For this prospective cohort study, 370 patients ?14 years of age, who reported lymphedema lasting more than three months in one or both legs, were recruited from villages in the Bolagarh sub-district, Khurda District, Orissa, India. The World Health Organization Disability Assessment Schedule II was administered to participants at baseline (July, 2009), and then at regular intervals through 24 months (July, 2011), to assess patients' perceived disability. Disability scores decreased significantly (p<0.0001) from baseline to 24 months. Multivariable analysis using mixed effects modeling found that employment and time in the program were significantly associated with lower disability scores after two years of program involvement. Older age, female gender, the presence of other chronic health conditions, moderate (Stage 3) or advanced (Stage 4–7) lymphedema, reporting an adenolymphangitis (ADL) episode during the previous 30 days, and the presence of inter-digital lesions were associated with higher disability scores. Patients with moderate or advanced lymphedema experienced greater improvements in perceived disability over time. Patients participating in the program for at least 12 months also reported losing 2.5 fewer work days per month (p<0.001) due to their lymphedema, compared to baseline. Significance These results indicate that community-based lymphedema management programs can reduce disability and prevent days of work lost. These effects were sustained over a 24 month period. PMID:23516648

Mues, Katherine E.; Kennedy, Erin D.; Prakash, Aiysha; Rout, Jonathan; Fox, LeAnne M.

2013-01-01

80

A Quantitative structural study of late pan-african compressional deformation in the central eastern desert (Egypt) during Gondwana assembly  

Microsoft Academic Search

The Arabian-Nubian-Shield (ANS) is composed of a number of island arcs together with fragments of oceanic lithospere and minor continental terranes. The terranes collided with each other until c. 600 Ma ago. Subsequently, they were accreted onto West Gondwana, west of the present River Nile. Apart from widespread ophiolite nappe emplacement, collisional deformation and related lithospheric thickening appear to be

M. M. Abdeen; R. O. Greiling

2005-01-01

81

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

NASA Astrophysics Data System (ADS)

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

Leslie, Graham; Schofield, David; Wilby, Phil

2014-05-01

82

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

PubMed Central

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

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

2013-01-01

83

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

84

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

PubMed Central

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

Cracraft, J.

2001-01-01

85

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

86

Tectonically controlled sedimentation in the Mesozoic basins of the Antarctic Peninsula  

SciTech Connect

The Antarctica Peninsula (AP) lies on a medium-size block of continental crust and is one of a mosaic of west Antarctica coastal block that underwent a complex tectonic evolution during Gondwana breakup. The peninsula represents the eroded roots of a microcontinental volcanic arc; this arc lay above the easterly subducting proto-Pacific plate, and was active throughout the Mesozoic. The exposed Mesozoic basins display a complex stratigraphy, reflecting local tectonic and volcanic events. There are a few general trends. Almost all basins are post-late Oxfordian, their fill is entirely clastic, and is largely derived from the Antarctica peninsula volcanic arc. Most basins were affected by a period of arc expansion in the latest Jurassic or earliest Cretaceous, which manifests itself as inputs of lava or coarse volcaniclastic sediment overlying mudstones with an open marine fauna. Barriasian and older mudstones are generally finer grained and darker than mudstones from post-Berriasian strata. However, it must be emphasized that these are only general trends. Deformation is variable, commonly progressive. No lithostratigraphic units can be correlated between any two basins, nor are there any interregional unconformities. No matching is possible with basins of equivalent age in formerly contiguous areas of Gondwana. There is evidence that some global eustatic events are recorded in the sedimentary records of at least two of the AP Mesozoic basins, but these have effect only in periods of local tectonic quiescence. The dominant control on sedimentation in this large segment of the Pacific rim was arc tectonics.

MacDonald, D.I.M.; Butterworth, P.J. (British Antarctic Survey, Cambridge (England))

1990-05-01

87

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

88

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

NASA Astrophysics Data System (ADS)

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

Abu-Alam, Tamer; Grosch, Eugene

2013-04-01

89

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

Microsoft Academic Search

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

Andreas Schmidt-Rhaesa; Malcom S. Bryant

2004-01-01

90

Seasonal appearance of Chlorophyceae phytoplankton bloom by river discharge off Paradeep at Orissa Coast in the Bay of Bengal.  

PubMed

Characteristics of the monsoonal bloom of phytoplankton at Orissa Coast in the Bay of Bengal were studied through bimonthly observation from April 2001 to December 2002. Three photosynthetic pigments chlorophyll-a (Chl a), chlorophyll-b (Chl b) and carotenoid (Car) were analyzed by absorption spectroscopic method. The seasonal variation of Chl a included phytoplankton bloom in the coastal area during monsoon period. The water column integrated Chl a reached to 68 mg m(-2) at the station-1(St1), and amounted to 20 mg m(-2) at 30 km off the river mouth during August 2001. In contrast the same amount was found at 15 km off the Mahanadi river mouth during August 2002. Salinity during this period varied from 5 psu at the St1 to 27 psu at the edge of the bloom area. The total amount of river discharge in the monsoon period calculated from daily river discharge data reported by Water Resources Department in India was 84 x 10(9) m(3) during 2001 and 20 x 10(9) m(3) during 2002. Both nitrate and phosphate concentrations showed negative quadratic relationship with salinity throughout the observation period. Extrapolated nitrate and phosphate concentration discharge from the Mahanadi river were 10.8 and 4 microg-at l(-1), respectively. Microscopic identification revealed dominance of fluvial Chlorophyceae and diatoms during the monsoon period showing influence of the freshwater discharge. PMID:18302000

Mishra, R K; Shaw, B P; Sahu, B K; Mishra, S; Senga, Y

2009-02-01

91

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

92

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

93

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

PubMed

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

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

2014-01-01

94

Metamorphic Evolution of Selected Pan-African Terrains across central Gondwana  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

95

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

96

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

NASA Astrophysics Data System (ADS)

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

Coiffard, Clément; Mohr, Barbara

2014-05-01

97

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

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

98

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

PubMed

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

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

2012-01-01

99

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

USGS Publications Warehouse

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

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

2007-01-01

100

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

101

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

102

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.

103

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

104

Structural framework, stratigraphy, and evolution of Brazilian marginal basins  

SciTech Connect

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

Ojeda, H.A.O.

1982-06-01

105

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

106

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

107

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

USGS Publications Warehouse

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

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

1991-01-01

108

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

109

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

Microsoft Academic Search

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

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

2010-01-01

110

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

PubMed

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

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

2013-03-01

111

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

112

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

SciTech Connect

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

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

1994-09-01

113

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

NASA Astrophysics Data System (ADS)

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

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

1995-12-01

114

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

115

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

Microsoft Academic Search

A field trial was conducted on the efficacy of Interceptor nets—a long-lasting insecticidal net (LLN) factory treated with alphacypermethrin 0.667% (w\\/w) corresponding to 200mg\\/m2, against malaria vectors Anopheles culicifacies and Anopheles fluviatilis in one of the highly endemic areas of Orissa. The study area comprised 19 villages which were randomized into three clusters and designated as Interceptor net cluster, untreated

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

2010-01-01

116

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

117

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

118

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

119

Evidence of pre-Gondwana tectono-thermal event from the Bhilwara Supracrustal units of Rajasthan, north-west India  

NASA Astrophysics Data System (ADS)

In the Indian subcontinent, two pre- Gondwana (pre- Pan African) orogenies are mostly recorded and well-studied from the Eastern Ghat Mobile Belt: (i) >1.1 Ga and (ii) ~950 Ma. During the ~950Ma orogeny, the pre-existing granulites have been re-melted under granulite facies conditions at ~8 kbar, 800-850ºC in the sillimanite stability field with formation of garnet-orthopyroxene in the restites. In this study we report garnet-sillimanite bearing and garnet-staurolite-kyanite bearing supracrustal rocks from the Bhilwara Supergroup in Rajasthan, N-W India. Peak assemblage in the garnet-sillimanite bearing metapelite is: garnet-sillimanite-biotite-plagioclase-quartz. Garnet porphyroblasts contain sillimanite-biotite bearing inclusion trails. Matrix foliations consist of biotite, sillimanite, quartz. Peak pressure-temperature calculated for garnet formation are ~7-8 kbar, 800ºC. Garnet is replaced along the margins by biotite during retrogression. Within garnet-staurolite-kyanite schist, peak assemblage is formed of garnet-staurolite-biotite-kyanite quartz, where garnet and staurolite occur as porphyroclasts and the matrix foliations are formed of kyanite-biotite-quartz. Mineral assemblages and compositions in the rock indicate peak pressure-temperature >8 kbar, 600ºC. The ages of the metamorphic events at sillimanite and kyanite facies are not well-constrained. However since the Bhilwara supracrustal units occur close to the Grenvillian orogenic belt at Sandmata Complex, the timing of the peak metamorphism can be constrained at ~1.0 Ga. Garnet-sillimanite-bearing assemblages noted in the Bhilwara Supracrustal Belt, has also been noted from the Grenvillian belts in the Eastern Ghat Mobile Belt. So the question that needs to be addressed is whether the Grenvillian orogenic belt recorded form the Sandmata Complex in Rajasthan and that of the Eastern Ghat Belt had been a continuous orogenic belt? Such possibilities can be addressed by establishing detailed structural analyses from the two domains. Such study can provide well-constrained facts about the position of Indian sub-continent in the reconstruction of Rodinia and Gondwana.

Saha, Lopamudra; Sarkar, Saheli; Rakshit, Nibedita; Nasipuri, Pritam

2014-05-01

120

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

PubMed Central

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

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

2012-01-01

121

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

NASA Astrophysics Data System (ADS)

The Karoo Basin of South Africa was one of several contemporaneous intracratonic basins in southwestern Gondwana that became active in the Permo-Carboniferous (280 Ma) and continued to accumulate sediments until the earliest Jurassic, 100 million years later. At their maximum areal extent, during the early Permian, these basins covered some 4.5 million km 2. The present outcrop area of Karoo rocks in southern Africa is about 300 000 km 2 with a maximum thickness of some 8000 m. The economic importance of these sediments lies in the vast reserves of coal within the Ecca Group rocks of northern and eastern Transvaal and Natal, South Africa. Large reserves of sandstone-hosted uranium and molybdenum have been proven within the Beaufort Group rocks of the southern Karoo trough, although they are not mineable in the present market conditions. Palaeoenvironmental analysis of the major stratigraphic units of the Karoo succession in South Africa demonstrates the changes in depositional style caused by regional and localized tectonism within the basin. These depocentres were influenced by a progressive aridification of climate which was primarily caused by the northward drift of southwestern Gondwana out of a polar climate and accentuated by the meteoric drying effect of the surrounding land masses. Changing palaeoenvironments clearly influenced the rate and direction of vertebrate evolution in southern Gondwana as evidenced by the numerous reptile fossils, including dinosaurs, which are found in the Karoo strata of South Africa, Lesotho, Namibia and Zimbabwe. During the Late Carboniferous the southern part of Gondwana migrated over the South Pole resulting in a major ice sheet over the early Karoo basin and surrounding highlands. Glacial sedimentation in upland valleys and on the lowland shelf resulted in the Dwyka Formation at the base of the Karoo Sequence. After glaciation, an extensive shallow sea covered the gently subsiding shelf, fed by large volumes of meltwater. Marine clays and muds accumulated under cool climatic conditions (Lower Ecca Group) including the distinctive Mesosaurus-bearing carbonaceous shales of the Whitehill Formation. Subduction of the palaeo-Pacific plate reslted in an extensive chain of mountains which deformed and later truncated the southern rim of the main Karoo Basin. Material derived from these "Gondwanide" mountains as well as from the granitic uplands to the north-east, accumulated in large deltas that prograded into the Ecca sea (Upper Ecca Group). The relatively cool and humid climate promoted thick accumulations of peat on the fluvial and delta plains which now constitute the major coal reserves of southern Africa. As the prograding deltas coalesced, fluvio-lacustrine sediments of the Beaufort Group were laid down on broad gently subsiding alluvial plains. The climate by this time (Late Permian) had warmed to become semi-arid with highly seasonal rainfall. Vegetation alongside the meander belts and semi-permanent lakes supported a diverse reptilian fauna dominated by therapsids or "mammal-like reptiles". Pulses of uplift in the southern source areas combined with possible orographic effects resulted in the progadation of two coarse-grained alluvial fans into the central parts of the basin (Katberg Sandstone Member and Molteno Formation). In the upper Karoo Sequence, progressive aridification and tectonic deformation of the basin through the late Triassic and early Jurassic led to the accumulation, in four separate depositories, of "redbeds" which are interpreted as fluvial and flood-fan, playa and dune complexes (Elliot Formation). This eventually gave way to westerly wind-dominated sedimentation that choked the remaining depositories with fine-grained dune sand. The interdune areas were damp and occasionally flooded and provided a habitat for small dinosaurs and the earliest mammals. During this time (Early Jurassic), basinwide volcanic activity began as a precursor to the break-up of Gondwana in the late Jurassic and continued until the early Cretaceous. This

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

1993-02-01

122

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

123

Thermotectonic history of the Bassian Rise, Australia: implications for the breakup of eastern Gondwana along Australia's southeastern margins  

NASA Astrophysics Data System (ADS)

During the Mesozoic breakup of eastern Gondwana, rifting occurred along both the Southern Ocean Rift (SOR) between Australia and Antarctica, and the Tasman Sea Rift (TSR) between Australia and the Lord Howe Rise. As a consequence of breakup, Tasmania, located at the southeastern tip of Australia, is now surrounded by rifted margins, including a failed branch of the SOR within Bass Strait to the north. Apatite fission track (AFT) results from the Furneaux Islands, located along the Bassian Rise at the eastern edge of Bass Strait, record two major episodes of rapid cooling/denudation since breakup began. The first occurred during the middle Cretaceous at ˜94±2 Ma and documents the timing of formation of the Bassian Rise. This was followed during the Early Tertiary by the second episode at some time between ˜65-45 Ma, possibly related to Pacific plate rearrangement and north Australian collision in New Guinea. Importantly, the AFT results indicate that formation of the Bassian Rise occurred during the middle Cretaceous at the same time as: (1) rifting along the TSR began, and (2) rifting along the SOR within Bass Strait ceased. This suggests a link between the timing of formation of the Bassian Rise and the initiation and cessation of major rifting events along the adjacent margins.

O'Sullivan, P. B.; Mitchell, M. M.; O'Sullivan, A. J.; Kohn, B. P.; Gleadow, A. J. W.

2000-10-01

124

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

NASA Astrophysics Data System (ADS)

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

Götz, Annette E.

2014-05-01

125

Hydrocarbon potential of the Lamu basin of south-east Kenya  

SciTech Connect

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

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

1996-01-01

126

Hydrocarbon potential of the Lamu basin of south-east Kenya  

SciTech Connect

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

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

1996-12-31

127

Sundaland basins  

NASA Astrophysics Data System (ADS)

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

Hall, Robert; Morley, Christopher K.

128

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

129

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

130

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

131

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

NASA Astrophysics Data System (ADS)

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

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

2000-10-01

132

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

133

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

134

Model a Catchment Basin  

NSDL National Science Digital Library

The purpose of this resource is to introduce what a catchment basin is and how it works. Students will make a 3-dimensional model of a catchment basin to understand how water moves through the basin and explore how water is affected when there are changes in the basin.

The GLOBE Program, UCAR (University Corporation for Atmospheric Research)

2003-08-01

135

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.

136

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

PubMed Central

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

2014-01-01

137

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

USGS Publications Warehouse

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

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

2007-01-01

138

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

NASA Astrophysics Data System (ADS)

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

Singara, S.

2006-05-01

139

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

NASA Astrophysics Data System (ADS)

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

Dawit, Enkurie L.

2014-11-01

140

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

141

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

142

Kinematic evolution of the Morondava rift basin of SW Madagascar--from wrench tectonics to normal extension  

NASA Astrophysics Data System (ADS)

The evolution of the Karoo Basin system in SW Madagascar (Morondava Basin) may be considered to be an initial break-up attempt between East- and West-Gondwana in East Africa. The early rift evolution in the Morondava extensional basin in Madagascar was previously described in terms of orthogonal crustal extension with either E-W or NW-SE directed extensional strain. Detailed field investigations in three areas of the Morondava Basin, subsequent to LANDSAT TM 5 and SPOT 4 satellite image interpretations, revealed, that crustal extension in the Morondava Basin and associated sedimentation of the Karoo Supergroup sequences occurred in three different periods under three different stress and kinematic regimes (referred to the actual position of Madagascar): Sinistral strike-slip movement (Early-?Late Permian), post-dating lower Sakoa Group deposition, and syn-depositional with middle Sakoa Group sedimentation. Formation of N-trending pull-apart basins. Sinistral strike-slip movement (post-latest Permian), post-dating lower Sakamena Group sediments and syn-depositional normal faulting (latest Permian). Formation of transtensional basins. NW-directed normal extension (Early-Middle Triassic) post-dating the middle Sakamena to lower Isalo Group I and pre-dating lower Isalo Group II deposition. Formation of half-grabens. Throughout the Permian period, strike-slip deformation, triggered by approximately N-S oriented compressive intraplate stresses, resulted in the formation of relatively limited pull-apart basins. At around the Permian-Triassic transition, the stress system gradually developed towards transtension with the consequence of significant widening of the depositional system. From the Early Triassic onwards, the stress system was purely tensional with widespread normal faulting prevailing, resulting in the increasing formation of half-graben systems, characterised by orthogonal extensional strain.

Schandelmeier, H.; Bremer, F.; Holl, H.-G.

2004-03-01

143

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

144

Water Basins Civil Engineering  

E-print Network

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

Provancher, William

145

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

PubMed Central

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

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

2013-01-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

147

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

148

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

NASA Astrophysics Data System (ADS)

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

Langhi, L.; Borel, G. D.

2003-04-01

149

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

150

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

NASA Astrophysics Data System (ADS)

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

K, Pauline Sabina; Jha, Neerja

2014-10-01

151

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

152

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

153

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.

154

Community mobilisation with women's groups facilitated by Accredited Social Health Activists (ASHAs) to improve maternal and newborn health in underserved areas of Jharkhand and Orissa: study protocol for a cluster-randomised controlled trial  

PubMed Central

Background Around a quarter of the world's neonatal and maternal deaths occur in India. Morbidity and mortality are highest in rural areas and among the poorest wealth quintiles. Few interventions to improve maternal and newborn health outcomes with government-mandated community health workers have been rigorously evaluated at scale in this setting. The study aims to assess the impact of a community mobilisation intervention with women's groups facilitated by ASHAs to improve maternal and newborn health outcomes among rural tribal communities of Jharkhand and Orissa. Methods/design The study is a cluster-randomised controlled trial and will be implemented in five districts, three in Jharkhand and two in Orissa. The unit of randomisation is a rural cluster of approximately 5000 population. We identified villages within rural, tribal areas of five districts, approached them for participation in the study and enrolled them into 30 clusters, with approximately 10 ASHAs per cluster. Within each district, 6 clusters were randomly allocated to receive the community intervention or to the control group, resulting in 15 intervention and 15 control clusters. Randomisation was carried out in the presence of local stakeholders who selected the cluster numbers and allocated them to intervention or control using a pre-generated random number sequence. The intervention is a participatory learning and action cycle where ASHAs support community women's groups through a four-phase process in which they identify and prioritise local maternal and newborn health problems, implement strategies to address these and evaluate the result. The cycle is designed to fit with the ASHAs' mandate to mobilise communities for health and to complement their other tasks, including increasing institutional delivery rates and providing home visits to mothers and newborns. The trial's primary endpoint is neonatal mortality during 24 months of intervention. Additional endpoints include home care practices and health care-seeking in the antenatal, delivery and postnatal period. The impact of the intervention will be measured through a prospective surveillance system implemented by the project team, through which mothers will be interviewed around six weeks after delivery. Cost data and qualitative data are collected for cost-effectiveness and process evaluations. Study registration ISRCTN: ISRCTN31567106 PMID:21787392

2011-01-01

155

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

156

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

NASA Astrophysics Data System (ADS)

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

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

1995-04-01

157

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.

Yellowstone National Park

158

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)...

159

K Basin safety analysis  

SciTech Connect

The purpose of this accident safety analysis is to document in detail, analyses whose results were reported in summary form in the K Basins Safety Analysis Report WHC-SD-SNF-SAR-001. The safety analysis addressed the potential for release of radioactive and non-radioactive hazardous material located in the K Basins and their supporting facilities. The safety analysis covers the hazards associated with normal K Basin fuel storage and handling operations, fuel encapsulation, sludge encapsulation, and canister clean-up and disposal. After a review of the Criticality Safety Evaluation of the K Basin activities, the following postulated events were evaluated: Crane failure and casks dropped into loadout pit; Design basis earthquake; Hypothetical loss of basin water accident analysis; Combustion of uranium fuel following dryout; Crane failure and cask dropped onto floor of transfer area; Spent ion exchange shipment for burial; Hydrogen deflagration in ion exchange modules and filters; Release of Chlorine; Power availability and reliability; and Ashfall.

Porten, D.R.; Crowe, R.D.

1994-12-16

160

Structure of the Millen Schist Belt (Antarctica): Clues for the tectonics of northern Victoria Land along the paleo-Pacific margin of Gondwana  

NASA Astrophysics Data System (ADS)

Victoria Land (Antarctica) belonged to the active proto-Pacific margin of Gondwana, which was the site of convergence during the Paleozoic. This study provides new insights into the structural architecture of northern Victoria Land, focusing on the boundary area between the Bowers and Robertson Bay terranes, i.e., in the Millen Schist Belt. It is a high-strain equivalent of the adjoining terranes, presently delimited by the Leap Year and the Handler faults. Our study reveals that these two faults overprint a preexisting transitional deformational boundary and are associated with a significant syntectonic circulation of fluids and mineralization. The Millen Schist Belt consists of two lithotectonic packages, juxtaposed along the Crosscut-Aorangi duplex thrust system, related to late Ross deformation. As there is increasing evidence of a post-Ross contractional event in northern Victoria Land, we suggest that the structural architecture of the Bowers-Robertson Bay terrane boundary results from a long-lasting SW-NE contractional regime, during the Ross-Delamerian Orogeny and still active afterward. This points to an extension of the Australian Lachlan Orogeny in Antarctica. The similarity of the structural architecture, the gold mineralization, the rock type, and the age supports the correlation of the Bowers and the Robertson Bay terranes with the Stawell Zone of the Lachlan Fold Belt. In our new tectonic scenario the Lanterman Fault (northern Victoria Land) plays the same role as the Moyston Fault (southeastern Australia), and the Leap Year and Handler faults correlate with the "intra-zone faults" of the Stawell Zone (e.g., the Ararat-Stawell Fault Zone).

Crispini, Laura; Federico, Laura; Capponi, Giovanni

2014-04-01

161

Operational Performance of Sedimentation Basins  

E-print Network

bobcat or front end loader into the built up sediment and hauling it to a dump truck. The design called for a 40’ x 10’ basin. This would be too small for a bobcat or small front-end loader to operate when cleaning out the basin so the basin... sediment buildup occurs in the basins. The basins needed to be accessed with bobcats for clean out. The bottom elevation of the basin is 10’ below the ground elevation where the trucks would be loaded by the bobcats. To access the basins the 17...

Bleything, Matthew D.

2012-12-14

162

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

163

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

164

Tharsis Basin Aquifer System  

NSDL National Science Digital Library

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

Arizona, University O.; Spaceref.com

165

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

166

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

167

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

168

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

PubMed

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

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

2010-10-01

169

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

170

Post-Gondwana pedogenic ferromanganese deposits, ancient soil profiles, African land surfaces and palaeoclimatic change on the Highveld of South Africa  

NASA Astrophysics Data System (ADS)

Several ferromanganese wad deposits are developed on the Archæan Malmani dolomite succession of the Transvaal Supergroup along the plateau forming the watershed between rivers draining to the Indian and Atlantic Oceans from the Highveld area between Johannesburg and Lichtenburg. The deposits were studied at the Wes Wits Gold Mine and the Ryedale, Houtkoppies and Klipkuil ferromanganese mines. The ferromanganese wad deposits are located in the Waterval saprolite, which formed by deep chemical weathering along the post-Gondwana African surface. The parent rocks for the wad are the Fe- and Mn-rich dolomites of the Malmani Subgroup of the Transvaal Supergroup at Wes Wits Mine and at Klipkuil, and Fe- and Mn-rich blackband Fe ores of the Ecca Group of the Karoo Supergroup at Ryedale and Houtkoppies. This saprolite is unconformably overlain by a ferruginous alluvial succession, informally defined as the Weswits formation. Diamondiferous gravel bars occur in the lower part of the fluvial succession. The unconformity at the base of the succession with incised valleys is thought to correspond to the post-African I event of uplift and erosion. Manganiferous soil nodules, derived from a lateritic weathering profile that originally covered the Waterval saprolite, are concentrated in the lower part of the Weswits formation. Climatic conditions became drier during the deposition of the Weswits formation, and plants with deep taproots vegetated the surface of the alluvium, giving rise to the formation of a ferric poclzol. Further aridification took place and eventually the plants with deep taproots died and a pediment developed along which a stone lag was concentrated. This pediment is thought to represent the post-African II surface of erosion. The pediment is overlain by the Hutton soil, representing Kalahari sand and dust that have been reworked by fluvial and peclogenic processes. Massive ferruginous soil nodules grew in situ in the Hutton soil, indicating more pluvial climatic conditions at times, most probably corresponding to the Quaternary ice age events in the Northern Hemisphere. A thin, modern orthic soil developed on top of the Hutton soil in the present day mild, subhumid climatic conditions.

Van Niekerk, H. S.; Beukes, N. J.; Gutzmer, J.

1999-12-01

171

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

NASA Astrophysics Data System (ADS)

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

Buckman, S.; Nutman, A.

2013-12-01

172

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...

173

SALINA BASIN PROVINCE (054) AND SEDGWICK BASIN PROVINCE (059)  

Microsoft Academic Search

Most of the Salina Basin is nonproductive. Maturity of potential source rocks (Simpson, Chattanooga) decreases in a northwest direction from the Forest City Basin. Although large areas of the Salina Basin remain untested, 600 wildcat wells have been drilled in the nonproductive portion, and despite numerous oil shows, there has been no commercial discovery in over 60 years of exploration.

Stephen E. Prensky

174

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...

175

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

NASA Astrophysics Data System (ADS)

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 Middle to Late Jurassic. The sediments filling the basin are divided into: Syrnift in the Oxfordian to Aptian (152 my to 113 my); Canyon fill in the Aptian to Albian (113 my to 103 my); and Thermal subsidence in the Albian (post 103 my). Using seismic data, well data, (including cuttings, cores, and log character), and Soekor (Pty) Ltd. completion reports, 24 unconformities and associated depositional sequences were recognized and correlated across the basin. The rift to drift transition in the offshore Algoa Basin was punctuated by the Aptian 13At1 (113 my) and the Albian 14At1 (103 my) unconformities. The Algoa canyon is incised into the 13At1 surface and filled from four feeder entry points by fluvial dominated deltas controlled by the tectonic fabric of the horsts and grabens. Higher amplitude/continuous reflectors at the base of prograding clinoforms correspond to the basinward turbidity systems. The 14At1 unconformity surface truncates the canyon fill and is a ubiquitous surface in the Outeniqua basin marking the boundary between pronounced changes in tectonic and sedimentary style that separate the rift to drift phases of extension. Future exploration of the basal canyon slope fans and/or prograding wedges sands should focus on the near west side of the Uitenhage fault and along the axis of the canyon fairways in the locally unfaulted Algoa canyon area. Structural analysis indicates the basin is dissected by a series of NW-SE trending faults. The faults may have induced hydrocarbon migration in the area. Rock-Eval pyrolysis analysis suggests that the Algoa Source rocks are less than 100 meters thick, and are mostly gas prone, with a potential for oil prone source rock downdip from the study area. Most of the source rocks seem to be either in the immature or in the early maturation stages.

Al-Raisi, Muatasam Hassan

176

Denver Basin Project  

NSDL National Science Digital Library

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

177

Crinoids columnals (Echinodermata) of the Ererê Formation (late Eifelian-early Givetian, Amazon Basin), State of Pará, Brazil  

NASA Astrophysics Data System (ADS)

The faunal composition of stalked echinoderms in the Brazilian Devonian is still largely unknown despite the great abundance of crinoids in the shallow epicontinental seas of the Paleozoic. The first Devonian crinoids of Brazil, recorded in the literature in 1875 and 1903, were from the sedimentary rocks of the Ererê Formation in the Amazon Basin. Since then, the echinoderms of this formation have not been studied. This study, based on isolated pluricolumnals and columnals, described and identified Botryocrinus meloi n. sp., the first record for this genus in Brazil. In addition to this species, two other morphological patterns were identified: Tjeecrinus sp. and Morphotype AM/Er-01. The form of occurrence of the crinoid material and the paleoautoecology of B. meloi allow preliminary characterization of the habitat as a moderately deep water with weak to moderate currents and soft substrate. The similarity between B. meloi and Botryocrinus montguyonensis and of Tjeecrinus? sp. and T. crassijugatus, from the Devonian of the Armorican and Rhenan Massif, represents new evidence for the existence of contact between the faunas of the Amazon Basin with those of northern Gondwana and Armorica during the Middle Devonian.

Scheffler, S. M.; Fernandes, A. C. S. F.; da Fonseca, V. M. M.

2014-01-01

178

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

179

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

NASA Astrophysics Data System (ADS)

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

Carto, Shannon L.; Eyles, Nick

2012-08-01

180

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

181

Design of settling basins  

Microsoft Academic Search

Experiments have been carried out in the laboratory concerning the efficiency of settling basins. The data indicate that the existing methods of their design are not satisfactory. Analysis of all the available data has led to a new relationship for the efficiency. The parameters L\\/D and w\\/u, are found to govern the efficiency.

R. J. Garde; K. G. Ranga Raju; A. W. R. Sujudi

1990-01-01

182

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

SciTech Connect

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

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

1994-03-01

183

Cenozoic basin development in Hispaniola  

SciTech Connect

Four distinct generations of Cenozoic basins have developed in Hispaniola (Haiti and Dominican Republic) as a result of collisional or strike-slip interactions between the North America and Caribbean plates. First generation basins formed when the north-facing Hispaniola arc collided with the Bahama platform in the middle Eocene; because of large post-Eocene vertical movements, these basins are preserved locally in widely separated areas but contain several kilometers of arc and ophiolite-derived clastic marine sediments, probably deposited in thrust-loaded, flexure-type basins. Second generation basins, of which only one is exposed at the surface, formed during west-northwesterly strike-slip displacement of southern Cuba and northern Hispaniola relative to central Hispaniola during the middle to late Oligocene; deposition occurred along a 5-km (3-mi) wide fault-angle depression and consisted of about 2 km (1 mi) of submarine fan deposits. Third generation basins developed during post-Oligocene convergent strike-slip displacement across a restraining bend formed in central Hispaniola; the southern 2 basins are fairly symmetrical, thrust-bounded ramp valleys, and the third is an asymmetrical fault-angle basin. Fourth generation basins are pull-aparts formed during post-Miocene divergent strike-slip motion along a fault zone across southern Hispaniola. As in other Caribbean areas, good source rocks are present in all generations of basins, but suitable reservoir rocks are scarce. Proven reservoirs are late Neogene shallow marine and fluvial sandstones in third generation basins.

Mann, P.; Burke, K.

1984-04-01

184

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

185

Natural frequency of regular basins  

NASA Astrophysics Data System (ADS)

Similar to the vibration of a guitar string or an elastic membrane, water waves in an enclosed basin undergo standing oscillatory waves, also known as seiches. The resonant (eigen) periods of seiches are determined by water depth and geometry of the basin. For regular basins, explicit formulas are available. Resonance occurs when the dominant frequency of external force matches the eigen frequency of the basin. In this paper, we implement the conservative finite volume scheme to 2D shallow water equation to simulate resonance in closed basins. Further, we would like to use this scheme and utilizing energy spectra of the recorded signal to extract resonant periods of arbitrary basins. But here we first test the procedure for getting resonant periods of a square closed basin. The numerical resonant periods that we obtain are comparable with those from analytical formulas.

Tjandra, Sugih S.; Pudjaprasetya, S. R.

2014-03-01

186

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

NASA Astrophysics Data System (ADS)

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

Smith, R. M. H.

187

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

188

Albuquerque Basin seismic network  

USGS Publications Warehouse

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

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

1977-01-01

189

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

190

Drainage Basin Morphometry  

NSDL National Science Digital Library

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

Ford, Rick

191

SONOMA-LIVERMORE BASIN PROVINCE (008)  

Microsoft Academic Search

The Sonoma-Livermore Province, located west of the Sacramento Basin Province (9) and east of the Central Coastal Province (11), is composed of a series of northwest-trending Neogene successor basins: the Sonoma, Orinda, and Livermore Basins. These Neogene basins lie east and north of the San Francisco Bay area; San Pablo Bay separates the Sonoma Basin to the north from the

Leslie B. Magoon

192

Seismic exploration in Raton basin  

SciTech Connect

Exploration in the Raton basin has delineated complex mountain-front structure in the asymmetric basin, and defined possible basin-centered gas. Exploration has included subsurface and surface geology, remote sensing, and seismic reflection. The Raton basin is a north-south-trending structural basin straddling the Colorado-New Mexico boundary. It is bounded on the west by the Sangre de Cristo Mountains, on the north and northeast by the Wet Mountains and Apishapa arch, and the Sierra Grande uplift on the south and southeast. The basin is asymmetric with transcurrent faulting and thrusting associated with the steeper western flank of the basin. Rocks range from Devonian-Mississippian overlying Precambrian basement to Miocene volcanics associated with the Spanish Peaks. Principal targets include the Entrada, Dakota, Codell, and Trinidad Sandstones and the Purgatoire and Raton Formations. Seismic data include explosive and Vibroseis data. Data quality is good in the basin center and is fair in the thrusted areas. Correlations are difficult from line to line. However, a strike line in the disturbed area would probably be more disrupted by out-of-the-plane reflections than the dip lines would be. Significant stratigraphic changes are seen in both the Trinidad and Dakota intervals. Integrated seismic and geological studies are keys to exploration in the basin. Subsequent work will rely heavily on improved seismic information.

Applegate, J.K.; Rose, P.R.

1985-05-01

193

67 FR 79557 - Martin Basin Rangeland Project  

Federal Register 2010, 2011, 2012, 2013, 2014

...and the Humboldt River Basin. [sbull] Continued...Quinn River/Blackrock Basin and the Humboldt Basin. [sbull] Continued...Federal Register. The Forest Service believes, at...dismissed by the courts. City of Angoon v....

2002-12-30

194

Hydrocarbon associations in evaporite basins  

SciTech Connect

Evaporite deposition today is not representative of the diversity of scale of evaporites of the past. Ancient evaporites were deposited in two main settings: platform wide or basin wide. Platform evaporites were composed of relatively thin stratiform units (usually <5-10 m thick) deposited on either ramps or behind rimmed shelves. Basinal evaporites were deposited as thick bedded units 10s to 100s of m thick, and laid down in 4 main tectonic settings--rift, collision, transform, and intracratonic. Basins could be further subdivided into three main depositional settings: deep basin-shallow water, deep basin-deep water, and shallow basin-shallow water. Thick basinal salts were remobilized into salt structures in all tectonic settings except intracratonic. Salt flow was due to inherent instability and differential loading in tectonically active settings. Hydrocarbon accumulations associated with these various platforms and basins followed a predictable, but not mutually exclusive, pattern related to the classification of evaporite settings presented in this paper. Reservoirs in platform and ramp settings tended to be of two types--depositional and diagenetic--with most of the diagenesis following patterns predicted by the porosity and plumbing established at or soon after evaporite emplacement. Ramp reservoirs were almost always found in Zone Y, while shelf reservoirs were most common in the grainstone shoals associated with rim or island-crest facies, or their dolomitized equivalents. Reservoirs associated with basinal evaporites were also depositional or diagenetic. Depositional reservoirs were almost all related to topography present during deposition of the carbonates in the basin, often immediately preceding or just beginning evaporitic conditions in the basin.

Warren, J.

1988-01-01

195

CCS project in Recôncavo Basin  

Microsoft Academic Search

In August 2007, Petrobras and IFP have initiated a common research project on Carbon Capture Storage to determine the feasibility of CO2 injection and underground storage in an oil field located in Recôncavo Basin, a mature basin of northeastern Brazil. Petrobras has a strong experience of more than 15 years in the management of CO2 for EOR and aims to

Rodolfo Dino; Yann Le Gallo

2009-01-01

196

Atlantic marginal basins of Africa  

SciTech Connect

The over 10,000-km long Atlantic margin of Africa is divisible into thirty basins or segments of the margin that collectively contain over 18.6 x 10/sup 6/ km/sup 3/ of syn-breakup and post-breakup sediments. Twenty of these basins contain a sufficiently thick volume of sediments to be considered prospects. These basins lie, at least partially, within the 200 m isobath. The distribution of source rocks is broad enough to give potential to each of these basins. The sedimentation patterns, tectonics, and timing of events differ from basin to basin and are related directly to the margin's complex history. Two spreading modes exist: rift and transform. Rifting dates from Late Triassic-Early Jurassic in the northwest to Early Cretaceous south of the Niger Delta. A complex transform fault system separated these two margins. Deep-water communication between the two basins became established in the middle Cretaceous. This Mesozoic-Cenozoic cycle of rifting and seafloor spreading has segmented the margin and where observable, basins tend to be bounded by these segments.

Moore, G.T.

1988-02-01

197

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...

198

Hydrocarbon associations in evaporite basins  

SciTech Connect

Evaporite deposition today is not representative of the diversity or scale of evaporites of the past. Ancient evaporites were deposited in two main settings: platform wide or basin wide. Platform evaporites were composed of relatively thin stratiform units (usually <5-10 m thick) deposited on either ramps or behind rimmed shelves. Basinal evaporites were deposited as thick bedded units 10s to 100s of m thick, and laid down in 4 main tectonic settings - rift, collision, transform, and intracratonic. Basins could be further subdivided into three main depositional settings: deep basin-shallow water, deep basin-deep water, and shallow basin-shallow water. Thick basinal salts were remobilized into salt structures in all tectonic settings except intracratonic. Salt flow was due to inherent instability and differential loading in tectonically active settings. Hydrocarbon accumulations associated with these various platforms and basins followed a predictable, but not mutually exclusive, pattern related to the classification of evaporite settings presented in this paper. Reservoirs in platform and ramp settings tended to be of two types - depositional and diagenetic - with most of the diagenesis following patterns predicted by the porosity and plumbing established at or soon after evaporite emplacement.

Warren, J.

1988-02-01

199

Foreland basins and fold belts  

SciTech Connect

The papers in this book describe six foreland basins and fold belts in terms of their regional setting, stratigraphy, tectonics, and structure, and their oil and gas systems. All of the basins show general similarities, but each differs significantly in detail from the others, posing something of a problem in terms of arriving at a 'typical' foreland basin and fold belt. Some are major hydrocarbon producers; others are not. The major characteristics of the six foreland basins and fold belts are summarized in Tables 1 through 5, which provide a convenient means of comparing and contrasting these basins and their hydrocarbon resources. The Western Canada foreland basin and fold belt serves as the type example for several reasons. These include: its setting and clear relationship to a major orogene of Mesozoic-Cenozoic age; the fact that it is uncomplicated by later overprinting, segmentation, or cover rocks unlike the Ouachita, Eastern Venezuela, and U.S. Rocky Mountain foreland basins and fold belts); the fact that there is a large volume of publicly available data on the basin and an active exploration and research community; and the fact that it has reasonable oil and gas reserves in a well-defined stratigraphic framework.

Macqueen, R.W.; Leckie, D.A. (Geological Survey of Canada, Inst. of Sedimentary and Petroleum Geology, Calgary, Alberta (Canada))

1992-01-01

200

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

201

Stratigraphic modeling of sedimentary basins  

SciTech Connect

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

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

1990-11-01

202

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

203

Dimension of Fractal Basin Boundaries.  

NASA Astrophysics Data System (ADS)

In many dynamical systems, multiple attractors coexist for certain parameter ranges. The set of initial conditions that asymptotically approach each attractor is its basin of attraction. These basins can be intertwined on arbitrary small scales. Basin boundary can be either smooth or fractal. Dynamical systems that have fractal basin boundary show "final state sensitivity" of the initial conditions. A measure of this sensitivity (uncertainty exponent alpha) is related to the dimension of the basin boundary d = D - alpha , where D is the dimension of the phase space and d is the dimension of the basin boundary. At metamorphosis values of the parameter, there might happen a conversion from smooth to fractal basin boundary (smooth-fractal metamorphosis) or a conversion from fractal to another fractal basin boundary characteristically different from the previous fractal one (fractal-fractal metamorphosis). The dimension changes continuously with the parameter except at the metamorphosis values where the dimension of the basin boundary jumps discontinuously. We chose the Henon map and the forced damped pendulum to investigate this. Scaling of the basin volumes near the metamorphosis values of the parameter is also being studied for the Henon map. Observations are explained analytically by using low dimensional model map. We look for universal scalings of the dimension of fractal basin boundaries near type I and type III intermittency transitions to chaos. Type I intermittency can occur as the system experiences a saddle-node (tangent) bifurcation and type III intermittency can occur as the system experiences an inverted period doubling bifurcation. At these bifurcations, multiple attractors with fractal basin boundaries can be created. It is found the dimension scales, with the parameter, according to the power law d = d_{o } - k| p - p_{c}| ^{beta} with beta = 1/2, where p is the system parameter, p _{c} is the bifurcation value, k is a scaling constant, and d_{o} is the dimension of the basin boundaries at p _{c}. For type I intermittency d_{o} < D and d _{o} = D for type III intermittency. This scaling was confirmed in numerical experiments near the type I and type III intermittency creating bifurcations values for the forced damped pendulum and the type I intermittency creating bifurcation value of period-3 window for the logistic map. (Abstract shortened with permission of author.).

Park, Bae-Sig

204

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

NASA Astrophysics Data System (ADS)

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

Raje, Deepashree; Mujumdar, P. P.

2009-10-01

205

The Amazon basin in transition.  

PubMed

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

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

2012-01-19

206

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

207

SOME ETHNOMEDICINAL PLANTS OF KORAPUT DISTRICT ORISSA  

PubMed Central

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

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

1988-01-01

208

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

209

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

210

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

211

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

212

Crustal structure of the southeastern Brazilian margin, Campos Basin, from aeromagnetic data: New kinematic constraints  

NASA Astrophysics Data System (ADS)

The continental and adjacent marginal features along southeast Brazil were investigated, focusing on the basement structural relationships between onshore and offshore provinces. Lateral and vertical variations in the magnetic anomalies provided a good correlation with the regional tectonic features. The sin-rift dykes and faults are associated with the magnetic lineaments and lie sub parallel to the Precambrian N45E-S45W basement structure of the Ribeira Belt, but orthogonally to the Cabo Frio Tectonic Domain (CFTD) basement, implying that: (1) the upper portion of the continental crust was widely affected by Mesozoic extensional deformation; and (2) tectonic features related to the process of break up of the Gondwana at the CFTD were form regardless of the preexisting structural basement orientation being controlled by the stress orientation during the rift phase. The deep crustal structure (5 km depth) is characterized by NE-SW magnetic "provinces" related to the Ribeira Belt tectonic units, while deep suture zones are defined by magnetic lows. The offshore Campos structural framework is N30E-S30W oriented and resulted from a main WNW-ESE direction of extension in Early Cretaceous. Transfer zones are represented by NW-SE and E-W oriented discontinuities. A slight difference in orientation between onshore (N45E) and offshore (N30E) structural systems seems to reflect a re-orientation of stress during rifting. We proposed a kinematical model to explain the structural evolution of this portion of the margin, characterized by polyphase rifting, associated with the rotation of the South American plate. The Campos Magnetic High (CMH), an important tectonic feature of the Campos Basin corresponds to a wide area of high crustal magnetization. The CMH wass interpreted as a magmatic feature, mafic to ultramafic in composition that extends down to 14 km depth and constitutes an evidence of intense crustal extension at 60 km from the coast.

Stanton, N.; Schmitt, R.; Galdeano, A.; Maia, M.; Mane, M.

2010-07-01

213

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

214

Stratigraphy of the southern Norfolk Ridge and the Reinga Basin: a record of initiation of Tonga-Kermadec-Northland subduction in the southwest Pacific  

NASA Astrophysics Data System (ADS)

Seismic-stratigraphic interpretations of a large new 2D seismic-reflection dataset from the Reinga Basin region northwest of New Zealand constrain the history of Cretaceous fragmentation of Gondwana and Cenozoic initiation of Tonga-Kermadec-Northland subduction. The southern Norfolk Ridge system lay in a proximal location to plate boundaries that were active during both Cretaceous and Cenozoic events, and persistent marine conditions led to a relatively complete record of sedimentation. Cretaceous extension was followed by regional subsidence and transgression. Two Cenozoic contractional events are separated by substantial (>1 km) subsidence. Late Eocene contraction led to reverse faulting and folding between New Caledonia and the southern Norfolk Ridge system, and topographic highs created in the north-western sector were locally eroded by wave abrasion. Reinga Basin was located at the southern tip of this event, which had only limited impact in adjacent northern New Zealand. Regional Oligocene and Miocene subsidence was contemporaneous with Late Oligocene and Early Miocene emplacement of nappes in northern New Zealand, and the onset of arc volcanism. Early Miocene contraction in the Reinga Basin led to formation of the Wanganella Ridge. These events can be related to calculated plate motions, and are shown to be consistent with models of induced subduction nucleation that require c. 150 km of convergence. The first contraction is associated with regional inception of Tonga-Kermadec subduction, whereas Oligocene to Miocene events and the onset of Hikurangi-Northland subduction were in response to a local change in plate boundary displacement rate and consequent linkage between subduction north of New Zealand with Alpine Fault formation farther south.

Bache, Francois; Sutherland, Rupert; Stagpoole, Vaughan; Herzer, Richard; Collot, Julien; Rouillard, Pierrick

2013-04-01

215

Stratigraphy of the southern Norfolk Ridge and the Reinga Basin: A record of initiation of Tonga-Kermadec-Northland subduction in the southwest Pacific  

NASA Astrophysics Data System (ADS)

Seismic-stratigraphic interpretations of a large new 2D seismic-reflection dataset from the Reinga Basin region northwest of New Zealand constrain the history of Cretaceous fragmentation of Gondwana and Cenozoic initiation of Tonga-Kermadec-Northland subduction. The southern Norfolk Ridge system lay in a proximal location to plate boundaries that were active during both Cretaceous and Cenozoic events, and persistent marine conditions led to a relatively complete record of sedimentation. Cretaceous extension was followed by regional subsidence and transgression. Two Cenozoic contractional events are separated by substantial (> 1 km) subsidence. Late Eocene contraction led to reverse faulting and folding between New Caledonia and the southern Norfolk Ridge system, and topographic highs created in the north-western sector were locally eroded by wave abrasion. Reinga Basin was located at the southern tip of this event, which had only limited impact in adjacent northern New Zealand. Regional Oligocene and Miocene subsidence was contemporaneous with Late Oligocene and Early Miocene emplacement of nappes in northern New Zealand, and the onset of arc volcanism. Early Miocene contraction in the Reinga Basin led to formation of the Wanganella Ridge. These events can be related to calculated plate motions, and are shown to be consistent with models of induced subduction nucleation that require c. 150 km of convergence. The first contraction is associated with regional inception of Tonga-Kermadec subduction, whereas Oligocene to Miocene events and the onset of Hikurangi-Northland subduction were in response to a local change in plate boundary displacement rate and consequent linkage between subduction north of New Zealand with Alpine Fault formation farther south.

Bache, François; Sutherland, Rupert; Stagpoole, Vaughan; Herzer, Rick; Collot, Julien; Rouillard, Pierrick

2012-03-01

216

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

NASA Astrophysics Data System (ADS)

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

Langhi, Laurent; Borel, Gilles D.

2005-03-01

217

Rainbow Basin, CA mapping project  

NSDL National Science Digital Library

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

Joan Fryxell

218

Exploration potential of offshore northern California basins  

SciTech Connect

A series of exploratory wells was drilled in the northern California offshore basins in the 1960s following leasing of federal tracts off northern California, Oregon, and Washington. The drilling, although encountering numerous oil shows, was considered at the time to indicate low prospectivity in an area that extended as far south as the offshore Santa Maria basin. However, subsequent major discoveries in this decade in the offshore Santa Maria basin, such as the Point Arguello field, indicate that these offshore basins may be highly prospective exploration targets. Many of the key features of Monterey production in central and southern California are also present in the offshore basins of northern California. A new 5-year leasing plan has scheduled leasing in the northern California OCS starting in early 1989. The first basins on the schedule, the Point Arena and Eel River basins, differ in some respects. The Point Arena basin is more typical of a Monterey basin, with the potential for fractured chert reservoirs and organic-rich sections, deep burial of basinal sections to enhance the generation of higher gravity oils, and complex folding and faulting. The Eel River basin is more clastic-rich in its gas-producing, onshore extension. Key questions in the Eel River basin include whether the offshore, more distal stratigraphy will include Monterey-like biogenic sediments, and whether the basin has oil potential in addition to its proven gas potential. The Outer Santa Cruz basin shares a similar stratigraphy, structure, and hydrocarbon potential with the Point Arena basin. The Santa Cruz-Bodega basin, also with a similar stratigraphy, may have less exploration potential because erosion has thinned the Monterey section in parts of the basin.

Bachman, S.B.; Crouch, J.K.

1988-01-01

219

Dynamic reorganization of river basins.  

PubMed

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

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

2014-03-01

220

Origin of the earth's ocean basins  

NASA Technical Reports Server (NTRS)

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

Frex, H.

1977-01-01

221

Origin of the earth's ocean basins  

Microsoft Academic Search

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

H. Frey

1977-01-01

222

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

223

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...

224

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...

225

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

226

KE BASIN SLUDGE CONSOLIDATION PROCESS DESCRIPTION  

Microsoft Academic Search

Spent nuclear fuel in canisters has been stored under water in the K-reactor fuel storage basins (K Basins) for more than 40 years. Over time, corrosion products from the degrading fuel rods, storage rack rust, concrete from pool walls, and environmental particulates have accumulated as sludge in fuel canisters, on the floors, and in the pits of the K Basins.

2004-01-01

227

BASIN: Beowulf Analysis Symbolic INterface  

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

228

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

229

Environmental control on concretion-forming processes: Examples from Paleozoic terrigenous sediments of the North Gondwana margin, Armorican Massif (Middle Ordovician and Middle Devonian) and SW Sardinia (Late Ordovician)  

NASA Astrophysics Data System (ADS)

Concretions of various compositions are common in the Paleozoic terrigenous successions of the north Gondwana margin. This study focuses on phosphatic (P) and siliceous (Si) concretions present in some successions of the Armorican Massif (NW France) and SW Sardinia (W Italy). It shows that they consist of mudstones, fine- to very fine-grained sandstones or shellbeds with a more or less abundant P-cement and form a continuum between a phosphatic end-member and a siliceous biogenic end-member. The P2O5 contents are ranging from 0.26% to 21.5% and are related to apatite. The SiO2 contents vary from 25% to 82% and are linked both to a terrigenous phase and to a biogenic silica phase. Concretions showing the lower P-contents (P2O5 < 1.5%) are often enriched in biogenic silica (SiO2/Al2O3 > 5). Comparison with the surrounding sediments shows that all the concretions are enriched in chlorite and in Middle Rare Earth Elements (Las/Gds: 0.12-0.72) and some of them in Y (up to 974 ppm), Rare Earth Elements (more than 300 ppm) and Sr (260-880 ppm). The concretions with highest biogenic silica concentrations are contained in the outer shelf sediments whereas the other concretions are present from the proximal part of the inner shelf to the outer shelf. A genetic model in two stages is proposed. During early diagenesis, the dissolution of shells and degradation of organic matter progressively enrich the pore water in dissolved Si, Ca and P. When the suboxic zone is reached, P-precipitation begins, leading to the formation of protoconcretions. In shallow environments, the relative permeability of sediments and the winnowing or reworking of the upper few centimetres by bottom currents allow for suboxic conditions to be maintained, leading to P-rich concretion formation. In deeper environments, the anoxic zone is reached more rapidly, thereby preventing extensive phosphogenesis. Nevertheless in the protoconcretions the early P-cement preserves pore spaces from compaction. In the presence of biogenic siliceous particles, the fluids are enriched in dissolved silica and diffuse towards the protoconcretions. Silica precipitation can thus occur later in the intergranular spaces.

Dabard, Marie-Pierre; Loi, Alfredo

2012-08-01

230

The Central European Permian Basins; Rheological and structural controls on basin history and on inter-basin connectivity  

NASA Astrophysics Data System (ADS)

We analyse the relative importance of the major crustal-scale fault zones and crustal architecture in controlling basin formation, deformation and the structural connections between basins. The North and South Permian Basins of Central Europe are usually defined by the extend of Rotliegend sedimentary and volcanic units and not by a common tectonic origin or development. Instead, the sub-basins that together form the Permian Basins are each controlled by different structural and/or rheological controls that are inherited from Early Paleozoïc and older geodynamic processes, they are even located in different crustal/lithospheric domains. The North Permian basin is located on Baltic crust that was thinned during Late Proterozoïc - Early Paleozoïc times. South of the Thor suture, the South Permian basin and its sub-basins are located on Avalonian crust (Southern North Sea and North German Basins) and on the transition of East European cratonic and Avalonian crust (Polish Through). The size of crustal domains and of the faults that govern basin formation requires a regional-scale to assess their impact on basins and sub-basins. In the case of the Permian Basins this encompasses East Avalonia and surroundings, roughly speaking the area north of the Variscan Rheïc suture, east of the Atlantic and southwest of the Teisseyre-Tornquist line. This approach sheds light on the effects of long lived differences in crustal fabric which are responsible for spatial heterogeneity in stress and strain magnitudes and zonations of fracturing, burial history and temperature history. The focus on understanding the geomechanical control of large crustal-scale fault structures will provide the constraints and geometrical and compositional input for local models of stress and strain. Considering their fundamentally different structural and rheological controls, the Permian (sub)basins have a remarkably common history of subsidence and inversion, suggesting a more or less continuous link between them. Post-Variscan, Late Carboniferous-Early Permian wrench tectonics is the oldest and main identified cause for regional basin formation in Central Europe. This relatively short-lived tectonic regime cannot explain the observed common history of subsidence of the Permian Basins during the 200 My that followed. Our analysis demonstrates that transfer faults that both follow and cross rheological transitions and inherited fault zones continued to be active after the early Permian. We therefore suggests that crustal-scale transfer faults may be the missing link that explains the common subsidence history of basins with a fundamentally different crustal architecture and structural history.

Smit, Jeroen; Van Wees, Jan-Diederik; Cloetingh, Sierd

2014-05-01

231

Large Double-ringed Basin  

NASA Technical Reports Server (NTRS)

Taken about 40 minutes before Mariner 10 made its close approach to Mercury on September 21, this picture (FDS 166684) shows a large (230 kilometers, 142 miles) double-ringed basin (center of picture) located in the planet's south polar region - 75 degrees S. Lat. 120 degrees W. Long. Mercury saw the basin from a different viewing angle on Mariner 10's first sweep last March. This picture was taken from about 55,000 kilometers (44,000 miles). North is toward upper left.

The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

Image Credit: NASA/JPL/Northwestern University

1974-01-01

232

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

233

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

234

Great Basin geoscience data base  

USGS Publications Warehouse

This CD-ROM serves as the archive for 73 digital GIS data set for the Great Basin. The data sets cover Nevada, eastern California, southeastern Oregon, southern Idaho, and western Utah. Some of the data sets are incomplete for the total area. On the CD-ROM, the data are provided in three formats, a prototype Federal Data Exchange standard format, the ESRI PC ARCVIEW1 format for viewing the data, and the ESRI ARC/INFO export format. Extensive documentation is provided to describe the data, the sources, and data enhancements. The following data are provided. One group of coverages comes primarily from 1:2,000,000-scale National Atlas data and can be assembled for use as base maps. These various forms of topographic information. In addition, public land system data sets are provided from the 1:2,500,000-scale Geologic Map of the United States and 1:500,000-scale geologic maps of Nevada, Oregon, and Utah. Geochemical data from the National Uranium Resource Evaluation (NURE) program are provided for most of the Great Basin. Geophysical data are provided for most of the Great Basin, typically gridded data with a spacing of 1 km. The geophysical data sets include aeromagnetics, gravity, radiometric data, and several derivative products. The thematic data sets include geochronology, calderas, pluvial lakes, tectonic extension domains, distribution of pre-Cenozoic terranes, limonite anomalies, Landsat linear features, mineral sites, and Bureau of Land Management exploration and mining permits.

Raines, Gary L.; Sawatzky, Don L.; Connors, Katherine A.

1996-01-01

235

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

236

Basement rocks of the main interior basins of the midcontinent  

NASA Astrophysics Data System (ADS)

The Precambrian framework of the Michigan, Illinois, Williston, Salina-Forest City, and Arkoma basins are discussed. The basins were categorized according to types that occur in the midcontinent and adjacent areas. Intracratonic basins were contrasted to foreland basins and aulacogens. The possible origins of intracratonic basins of the midcontinent are discussed.

Lidiak, E. G.

237

Basement rocks of the main interior basins of the midcontinent  

Microsoft Academic Search

The Precambrian framework of the Michigan, Illinois, Williston, Salina-Forest City, and Arkoma basins are discussed. The basins were categorized according to types that occur in the midcontinent and adjacent areas. Intracratonic basins were contrasted to foreland basins and aulacogens. The possible origins of intracratonic basins of the midcontinent are discussed.

E. G. Lidiak

1981-01-01

238

Basin-average data: Cloud Albedo and the Diurnal Cycle  

E-print Network

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

Hurrell, James

239

UPPER SNAKE RIVER PRIORITY BASIN ACCOMPLISHMENT PLAN, APRIL 1973  

EPA Science Inventory

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

240

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

241

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

242

The IntraCONtinental basinS (ICONS) atlas - applications in eastern Australia  

Microsoft Academic Search

We have used a combination of openly available regional and global crustal and lithosphere datasets to create a framework for intracontinental basin evaluation. In this paper, we focus on the intracontinental Murray and Eromanga basins in eastern Australia. We assess the total sediment thickness versus crustal thinning observed underneath a given basin to evaluate alternative total tectonic subsi dence estimates,

C. Heine; R. D. Müller

2008-01-01

243

A seismic experiment in the Ulleung basin (Tsuhima basin), Southwestern Japan sea (East sea of Korea)  

Microsoft Academic Search

Understanding the crustal structure of the Ulleung basin (Tsushima basin) in the southwestern Japan sea (East sea of Korea) is important for reconstructing the opening tectonics of the Japan sea. A Korea and Russia collaborative seismic experiment was carried out in 1991 to investigate the crustal structure of this basin using ocean bottom seismometers (OBSs) and large capacity air guns.

Han Joon Kim; Chan Hong Park; Jong Kuk Hong; Hyeong Tae Jou; Tae Woong Chung; V. Zhigulef; G. I. Anosov

1994-01-01

244

A seismic experiment in the Ulleung Basin (Tsushima Basin), southwestern Japan Sea (East Sea of Korea)  

Microsoft Academic Search

Understanding the crustal structure of the Ulleung basin (Tsushima basin) in the southwestern Japan sea (East sea of Korea) is important for reconstructing the opening tectonics of the Japan sea. A Korea and Russia collaborative seismic experiment was carried out in 1991 to investigate the crustal structure of this basin using ocean bottom seismometers (OBSs) and large capacity air guns.

Han Joon Kim; Chan Hong Park; Jong Kuk Hong; Hyeong Tae Jou; Tae Woong Chung; V. Zhigulef; G. I. Anosov

1994-01-01

245

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

SciTech Connect

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

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

1986-08-01

246

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

USGS Publications Warehouse

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

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

1997-01-01

247

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

248

64 FR 2876 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013, 2014

...SUMMARY: The Lake Tahoe Basin Federal Advisory Committee...Hazelhurst, Lake Tahoe Basin Management Unit, Forest Service, 870 Emerald...established the Lake Tahoe Basin Advisory Committee to...board member of the Tahoe City Public Utilities...

1999-01-19

249

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2013 CFR

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

2013-10-01

250

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

251

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

252

48 CFR 25.405 - Caribbean Basin Trade Initiative.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

253

Improved Basin Analog System to Characterize Unconventional Gas Resource  

E-print Network

by both BASIN and PRISE (Petroleum Resources Investigation and Summary Evaluation) software, results of the improved BASIN closely matched the PRISE results, which provides important support for using BASIN and PRISE together to quantitatively estimate...

Wu, Wenyan 1983-

2012-10-02

254

77 FR 61784 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2012-10-11

255

78 FR 70574 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-11-26

256

76 FR 61382 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2011-10-04

257

76 FR 24515 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2011-05-02

258

75 FR 25877 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-05-10

259

75 FR 27360 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-05-14

260

75 FR 66389 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-10-28

261

77 FR 23508 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2012-04-19

262

78 FR 23784 - Colorado River Basin Salinity Control Advisory Council  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-04-22

263

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. We found the average crustal thickness beneath the Khartoum basin is 35 km. We found the average crustal Vp/Vs ratio is 1.78. We obtained the average shear wave velocities of 3.7 km/s for the crust. We found small amount of thinning beneath the Khartoum basin. Insufficient topography beneath the basin to channel plume material from Ethiopia.

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

2013-05-01

264

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

265

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

266

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

NASA Astrophysics Data System (ADS)

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

Ghosh, Sampa; Sarkar, Soumen; Ghosh, Parthasarathi

2012-01-01

267

72 FR 9302 - Medicine Bow-Routt National Forest and Thunder Basin National Grassland; Wyoming; Thunder Basin...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Bow-Routt National Forest and Thunder Basin National Grassland; Wyoming; Thunder Basin Analysis Area Vegetation...Management AGENCY: Forest Service, USDA...on the National Forest Service (NSF) lands within the Thunder Basin National...

2007-03-01

268

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-11-01

269

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

NASA Astrophysics Data System (ADS)

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

Raposo, M. B.

2013-05-01

270

The role of inherited structures in a foreland basin evolution. The Metán Basin in NW Argentina  

NASA Astrophysics Data System (ADS)

The foreland basin of the Central Andes in NW Argentina is formed by partially unconnected basins limited by uneven high ranges. The Metán Basin is located in the foothills of the Central Andes in NW Argentina between the Eastern Cordillera, the Sierras Pampeanas and the Santa Bárbara System. This basin resulted from a Cretaceous to Paleogene rifting event and from two Neogene to Quaternary foreland basin stages. For this study field data, log well, seismic reflection and satellite images have been interpreted. The propagation of deformation in this sector of the Andes is influenced by inherited structures (e.g. Cretaceous extensional faults), which have been reactivated during Andean compression as high angle and oblique reverse faults. Deformation does not advance regularly throughout the foreland in a normal forward sequence but jumps across inherited faults. Fault reactivation has resulted in uplift of basement cored ranges and hanging wall anticlines that divided the foreland into small basins (e.g. the Metán Basin).

Iaffa, Diego Nicolas; Sàbat, F.; Muñoz, J. A.; Mon, R.; Gutierrez, A. A.

2011-12-01

271

Petroleum systems of the Southwest Caspian Basin  

Microsoft Academic Search

The Southwest Caspian Basin, located in offshore Azerbaijan, contains significant accumulations of oil and gas in Upper Tertiary siliciclastic sediments. The central basin contains up to 25 km of sediments. The relatively low geothermal gradients and low degree of compaction from rapid burial provide favorable conditions or the retention of hydrocarbons at relatively great depths. A variety of structural styles

M. A. Abrams; A. A. Narimanov

1995-01-01

272

BASINS/HSPF WATERSHED MODEL TRAINING  

EPA Science Inventory

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

273

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

274

6, 839877, 2006 Mexico City basin  

E-print Network

towards the Gulf15 of Mexico. Regional accumulation was found to take place for some days howeverACPD 6, 839­877, 2006 Mexico City basin ventilation and urban plume B. de Foy et al. Title Page Discussions Rapid ventilation of the Mexico City basin and regional fate of the urban plume B. de Foy 1 , J. R

Boyer, Edmond

275

Water Atlas of the Volta Basin  

E-print Network

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

Boyer, Edmond

276

Upper San Juan Basin Biological Assessment  

E-print Network

and organizations, including the Colorado Division of Wildlife (CDOW), regional and local herbaria, local experts for the first time in the CNHP database for the Basin. This is truly a unique area Citizens of the Upper San Juan Basin are concerned about rapid growth, resulting in loss of open space, wildlife habitat

277

A brief history of Great Basin pikas  

Microsoft Academic Search

ABSTRACT Aim Within the past few decades, seven of the 25 historically described populations of American pikas (Ochotona princeps) in the Great Basin of arid western North America appear to have become extinct. In this paper, the prehistoric record for pikas in the Great Basin is used to place these losses in deeper historical context.

Donald K. Grayson

2005-01-01

278

The structure of Nansen and Amundsen Basin  

NASA Astrophysics Data System (ADS)

During the AMORE expedition in August/September 2001, a US-German joint project, the Gakkel Ridge and the adjoining basins were investigated. In this contribution we report on the results of the seismic investigations in the Nansen Basin as well as in the Amundsen Basin. We obtained two almost parallel profiles through the Nansen Basin from the northeastern continental margin of Svalbard (29°E and 32°E) to the Gakkel Ridge at 17°E and 21°E. To investigate the Amundsen Basin, we left Gakkel Ridge at about 70°E towards Lomonossov Ridge for another transect. In total 1360 km of seismic reflection data with very good data quality were recorded. Parallel to the seismic reflection transects up to 30 sonobuoys were deployed. The data from both basins shows striking differences in the basement topography. While in the Nansen Basin the oceanic crust is more or less continuously shallowing, this is not the case in the Amundsen Basin. This points to some asymmetric spreading history of the Gakkel Ridge in northern and southern directions. Some of the Sonobuoys recorded also weak arrivals from the Moho discontinuity. The analysis of the wide angle and gravity data shows, that there are areas with a significant thinning of the oceanic crust. Results of the reflection and refraktion seismic as well as the gravity interpretation will be presented.

Micksch, U.; Jokat, W.

2003-04-01

279

Devonian shale gas resource assessment, Illinois basin  

Microsoft Academic Search

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

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

1996-01-01

280

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

281

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

282

Mackenzie - Liard Valley Hydrocarbon Basins, NWT  

Microsoft Academic Search

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

James R. Taylor

283

An alternative basin characteristic for use in estimating impervious area in urban Missouri basins  

USGS Publications Warehouse

A previous regression analysis of flood peaks on urban basins in St. Louis County, Missouri, indicated that the basin characteristics of percentage of impervious area and drainage area were statistically significant for estimating the 2-, 5-, 10-, 25-, 50-. and 100-yr peak discharges at ungaged urban basins. In this statewide regression analysis of the urban basins for Missouri, an alternative basin characteristic called the percentage of developed area was evaluated. A regression analysis of the percentage of developed area (independent variable), resulted in a simple equation for computing percentage of impervious area. The percentage of developed area also was evaluated using flood-frequency data for 23 streamflow gaging stations, and the use of this variable was determined to be valid. Using nationwide data, an urban basin characteristic known as the basin development factor was determined to be valid for inclusion in urban regression equations for estimating flood flows. The basin development factor and the percentage of developed area were compared for use in regression equations to estimate peak flows of streams in Missouri. The equations with the basin development factor produced peak flow estimates with slightly smaller average standard errors of estimate than the equation with the percentage of developed area; however, this study indicates that there was not enough statistical or numerical difference to warrant using the basin development factor instead of the percentage of developed area in Missouri. The selection of a basin characteristic to describe the physical conditions of a drainage basin will depend not only on its contribution to accuracy of regression equations, but also on the ease of determining the characteristics; the percentage of developed area has this advantage. A correlation analysis was made by correlating drainage area to percentage of impervious area, the percentage of developed area, and the basin development factor. The results of the analysis indicate that the three basin characteristics are independent of drainage area and appropriate to use in multiple-regression analysis. (Author 's abstract)

Southard, R.E.

1986-01-01

284

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.

285

Petroleum geochemistry of the Zala Basin, Hungary  

USGS Publications Warehouse

The Zala basin is a subbasin within the Pannonian basin. Geochemical study of oils and rocks in the basin indicate that two, and possibly three, genetic oil types are present in the basin. Miocene source rocks, previously believed to be the predominant source rock, have expelled minor amounts of hydrocarbons. The main source rock is the Upper Triassic (Rhaetian) Kossen Marl Formation or its stratigraphic equivalent. Knowledge of the geochemical characteristics of oils derived from these Upper Triassic source rocks and understanding of the source rock distribution and maturation history are important for recognizing Triassic oil-source bed relationships and for further exploration in other basins in Hungary and other parts of Europe where Triassic source rocks are present. -from Authors

Clayton, J.L.; Koncz, I.

1994-01-01

286

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

NASA Astrophysics Data System (ADS)

Prior to the breakup of western Gondwana, ca. 130 Ma, the Tristan da Cuhna mantle plume produced the eastern South American Parana, and western African Etendeka, flood basalts. As the South Atlantic basin opened, the ridge-centered plume produced seaward extending hotspot tracks: Rio Grande Rise on the South American Plate, and Walvis Ridge on the African Plate. Several ocean floor edifices on the hotspot trends appear to produce lower than expected amplitude free air gravity anomalies, suggesting that they are composed of lower density material. We have constructed a 3D gravity model of the South Atlantic basin to examine variations in crustal density associated with the hot spot trends. The model, which encompasses a region that extends from 46°S to 10 °S and from 20°E to 60°W, comprises the following layers: water, sediment, crust, and upper mantle. Variable density sediment and upper mantle layers are incorporated to estimate density changes related to sediment thickness and compaction, and upper mantle temperatures, respectively. The initial Moho horizon is estimated from isostatic equilibrium calculations; however the isostatic effect is scaled away from the seafloor spreading center to simulate the active spreading center. Three open-file grids were used to generate the model: satellite-derived free air gravity, global topography, and sediment thickness of the world. Inverting the model for crustal density reveals a distribution of low-density areas: along the coasts, the seafloor spreading axis, and along the Rio Grande Rise and Walvis Ridge hotspot trends. Coastal and spreading axis low density areas are thought to be related to continental crust and high temperature upper mantle. Hotspot track low density areas might be related to variable densities within the volcanic edifices, variations in their crustal thickness, or upper mantle densities beneath them. Detailed 2D models approximate reasonable density and geometry limits along select transects. Holding the African Plate fixed, we have rotated the South American Plate for 16 times corresponding to Chrons C5, C6, C13, C18, C21, C25, C31, C34, five interpolated times (ca. 89, 93, 100, 105, and 112 Ma), and Chrons M0, M2 and M4. Reconstructions, displaying inversion results illustrate the development of the hotspot tracks as the South Atlantic opened, suggest that Tristan da Cuhna was a ridge-centered plume until about 30 Ma.

Bird, D. E.; Hall, S. A.

2009-12-01

287

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

288

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...

289

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

290

Bedrock geology and chemistry of rivers basins  

NASA Astrophysics Data System (ADS)

The lack of modern quantitative estimates of the Earth’s surface geology, one of the key parameters influencing river and ocean chemistry, is striking. While some attempts have been made to quantify the lithologic composition of bedrock in individual river basins (e.g., Reeder et al., 1972; Amiotte-Suchet et al., 2002), the geologic age distribution of bedrock in river basins has not been investigated. We have therefore initiated a project aimed at generating a worldwide dataset on the bedrock lithology and age distribution of river basins, using the latest digital geologic maps and modern geographic information system technology. To date we have completed analysis of the digital geologic maps North America. These data have been used in conjunction with digital river basin polygons (Revenga et al., 1998, World Resources Institute) to compute the lithologic composition and geologic age structure of major river basins in North America. The lithologic composition of 14 large river basins range from predominantly igneous rocks dominated (Frazer, Columbia), to those dominated by sedimentary rocks (Brazos, Susquehanna, Mississippi), to basins with an equal mix of igneous, metamorphic and sedimentary bedrock (Thelon). Subdividing sedimentary rocks into marine and continental rocks reveals that continental sediments account for no more than 25% of sedimentary rocks in these river basins (e.g., Nelson, Colorado, Mississippi). A further subdivision of igneous rocks into intrusive and volcanic rocks reveals the entire range of igneous composition, from basins dominated by intrusive rocks (Hudson, Mackenzie, Nelson) to those dominated by volcanic rocks (Susquehanna, Colorado, Frazer, Columbia). We are currently analyzing the age distribution of major lithologic units in each river basin. In cases where detailed hydrochemical data is available for major tributaries we will expand the analysis to sub-basins (e.g., Frazer, Mississippi). Basins smaller than about 40,000 km^2 will require analysis of higher-resolution digital geologic bedrock maps. In the next project phase we will combine bedrock data for major river basins with hydrochemical data to investigate the influence bedrock exerts on river chemistry, specifically radiogenic isotopes and macronutrients. Combining digital information on bedrock geology with digital maps of precipitation will allow us to use precipitation-weighted bedrock area rather than simple area-lithology relationships. Extending this analysis to pre-Quaternary periods is beyond the current focus of the project, but will be necessary to fully utilize reconstructions of ocean paleochemistry in models of global biogeochemical cycles (e.g., Bluth and Kump, 1991).

Peucker-Ehrenbrink, B.; Miller, M. W.

2003-04-01

291

Metabolic principles of river basin organization.  

PubMed

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

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

2011-07-19

292

Metabolic principles of river basin organization  

PubMed Central

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

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

2011-01-01

293

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

294

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

295

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

296

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

297

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

298

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

299

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

300

Geology and hydrocarbon potential of the Oued Mya basin, Algeria  

Microsoft Academic Search

The Oued Mya hydrocarbon system is located in the Sahara basin. It is one of the best producing basins in Algeria, along with the Ghadames and Illizi basins. The stratigraphic section consists of Paleozoic and Mesozoic, and is about 5000 m thick. This intracratonic basin is limited to the north by the Toughourt saddle, and to the west and east

O. Benamrane; M. Messaoudi; H. Messelles

1993-01-01

301

An entropy-based morphological analysis of river basin networks  

E-print Network

according to the Horton-Strahler ordering scheme, a linear relation is found between the drainage basin entropy and the basin order. This relation can be characterized as a measure of the basin network complexity. The basin entropy is found to be linearly...

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

302

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

303

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

304

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

305

Preparing T Plant for Storing Sludge from the K Basins  

Microsoft Academic Search

For a number of years, the spent nuclear fuel (SNF) from the N Reactor has been stored underwater in the basins at the 100 K Area complex of the Hanford Site (K Basins). Fluor Hanford is managing a significant effort to remove the fuel from the K Basins and place it in dry storage. Removing accumulated sludges from the basins

W. S. Ayers; E. G. Erpenbeck; D. E. McKenney; T. A. Shrader

2003-01-01

306

COAL QUALITY AND GEOCHEMISTRY, HANNA AND CARBON BASINS, WYOMING  

E-print Network

quality data distribution in the Hanna and Carbon Basins. HQ-3. Ash yield in the Ferris 25 coal zone, Ferris coalfield, Hanna Basin. HQ-4. Ash yield in the Ferris 50 coal zone, Ferris coalfield, Hanna Basin. HQ-5. Ash yield in the Hanna 77 coal zone, Hanna coalfield, Hanna Basin. HQ-6. Ash yield in the Hanna

307

Saharan dust in the Amazon Basin  

NASA Technical Reports Server (NTRS)

It is shown that Saharan dust enters the Central Amazon Basin in bursts that accompany major wet season rain systems. Low-level horizontal convergence feeding these rain systems draws dust from plumes that have crossed the tropical Atlantic under the large-scale circulation fields. Mass exchange of air between the surface and four kilometers over the eastern Amazon basin is calculated utilizing rawinsonde data collected during storm events. Mean concentrations of dust observed by aircraft over the western tropical Atlantic are employed to calculate the amount of dust injected into the basin.

Swap, R.; Garstang, M.; Greco, S.; Talbot, R.; Kallberg, P.

1992-01-01

308

Evolution of sedimentary basin in the southwestern Ulleung Basin margin: Sequence stratigraphy and geologic structures  

Microsoft Academic Search

This study presents an evolutionary history of the southwestern Ulleung Basin margin on the basis of sequence stratigraphic\\u000a and structural analyses of multi-channel seismic reflection profiles. Ten sequences and geologic structures identified in\\u000a the late Tertiary strate suggest three distinct stages of basin development in the early Miocene to Pliocene. In the early\\u000a Miocene, the basin, bordered on the west

S. H. Yoon; S. J. Park; S. K. Chough

2002-01-01

309

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

SciTech Connect

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

David J. Taylor

2003-08-01

310

Death of a carbonate basin: The Niagara-Salina transition in the Michigan basin  

SciTech Connect

The A-O Carbonate in the Michigan basin comprises a sequence of laminated calcite/anhydrite layers intercalated with bedded halite at the transition between normal marine Niagaran carbonates and lower Salina Group evaporites. The carbonate/anhydrite interbeds represent freshing events during initial evaporative concentration of the Michigan basin. Recent drilling in the Michigan basin delineates two distinct regions of A-O Carbonate development: a 5 to 10 m thick sequence of six 'laminites' found throughout most of the western and northern basin and a 10 to 25 m thick sequence in the southeastern basin containing both thicker 'laminates' and thicker salt interbeds. Additionally, potash deposits of the overlying A-1 evaporite unit are restricted to the northern and western basin regions. The distribution of evaporite facies in these two regions is adequately explained by a source of basin recharge in the southeast-perhaps the 'Clinton Inlet' of earlier workers. This situation suggest either that: (1) the source of basin recharge is alternately supplying preconcentrated brine and more normal marine water, or (2) that the basin received at least two distinct sources of water during A-O deposition.

Leibold, A.W.; Howell, P.D. (Univ. of Michigan, Ann Arbor (United States))

1991-03-01

311

Tidal frequency estimation for closed basins  

NASA Technical Reports Server (NTRS)

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

Eades, J. B., Jr.

1978-01-01

312

KE Basin water dispositioning engineering study  

SciTech Connect

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

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

1994-09-23

313

Future Climate Scenarios for the Indus Basin  

E-print Network

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

Yu, Winston

314

K-Basins S/RIDS  

SciTech Connect

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

Watson, D.J.

1997-08-01

315

Overflow of Radioactive Water from K Basins  

SciTech Connect

This report documents the dose calculations for the postulated K Basin overflow accident using current methods to model the environmental doses for radioactive releases into the Columbia River and the air.

RITTMANN, P.D.

1999-10-06

316

Pacific Basin Communication Study, volume 2  

NASA Astrophysics Data System (ADS)

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

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

1981-10-01

317

The Uinta Basin Case Robert J. Bayer  

E-print Network

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

Utah, University of

318

September 2012 BASIN RESEARCH AND ENERGY GEOLOGY  

E-print Network

September 2012 BASIN RESEARCH AND ENERGY GEOLOGY STATE UNIVERSITY OF NEW YORK at BINGHAMTON research programs in geochemistry, sedimentary geology, or Earth surface processes with the potential the position, visit the Geological Sciences and Environmental Studies website (www.geology

Suzuki, Masatsugu

319

Interpretation of magnetic anomalies over the Grenada Basin  

NASA Astrophysics Data System (ADS)

The Grenada Basin is a back arc basin located near the eastern border of the Caribbean Plate. The basin is bounded on the west by the north-south trending Aves Ridge (a remnant island arc) and on the east by the active Lesser Antilles island arc. Although this physiography suggests that east-west extension formed the basin, magnetic anomalies over the basin exhibit predominantly east-west trends. If the observed magnetic anomalies over the basin are produced by seafloor spreading, then the orientation of extension is complex. Extension in back arc basins is roughly normal to the trench, although some basins exhibit oblique extension. Present models for the formation of the Grenada Basin vary from north-south extension through northeast-southwest extension to east-west extension. An interpretation of magnetic anomalies over the Grenada Basin supports basin development by nearly east-west extension. Low amplitude magnetic anomaly trends subparallel to the island arc magnetic anomaly trends over the southern part of the basin and the results of forward three-dimensional (3-D) magnetic modeling are consistent with this conclusion. Late Cenozoic tectonic movements may have been responsible for disrupting the magnetic signature over the northern part of the basin. On the basis of our 3-D analysis, we attribute the prominent east-west trending anomalies of the Grenada Basin to fracture zones formed during seafloor spreading at low latitude. This east-west trend is not interpreted as indicating north-south extension of the basin.

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

1993-10-01

320

Critically safety evaluation for K Basins sandfilters  

SciTech Connect

Criticality safety for K Basins sandfilters was considered. No credible normal or off-normal scenarios were determined which could compromise criticality safety and result in a K{sub eff} {>=} 0.98. The conclusion is that, due to the physical form and isotopic distribution of the fissionable material, there is no possibility of a nuclear criticality in the sandfilter. For this reason, there is no need for a criticality alarm system for the K Basins sandfilters.

Wittekind, W.D.

1994-10-01

321

Streamflow changes over Siberian Yenisei River Basin  

Microsoft Academic Search

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

Daqing Yang; Baisheng Ye; Douglas L. Kane

2004-01-01

322

Ordovician chitinozoan zones of Great Basin  

SciTech Connect

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

Hutter, T.J.

1987-08-01

323

Saharan dust in the Amazon Basin  

Microsoft Academic Search

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

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

1992-01-01

324

Induced Seismicity of Kuznetsk Basin  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

325

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

USGS Publications Warehouse

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

Jayko, Angela S.; Bursik, Marcus

2012-01-01

326

Mesozoic evolution of the Amu Darya basin  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

327

Latest Carboniferous-earliest Permian transgressive deposits in the Paganzo Basin of western Argentina: Lithofacies and sequence stratigraphy of a coastal-plain to bay succession  

NASA Astrophysics Data System (ADS)

The upper Paleozoic rocks of Gondwana record a complex paleoclimatic history related to the migration of the supercontinent over high latitudes. Changes in climate and relative sea level can be traced through detailed sedimentologic and sequence-stratigraphic analysis. Our study focuses on transgressive deposits of Stephanian-Early Permian age in the lower member of the Tupe Formation with the objective of characterizing lithofacies and sedimentary environments within a sequence-stratigraphic framework in order to achieve a better understanding of the sedimentary history of the Paganzo Basin and the nature of transgressive deposits. Sixteen lithofacies grouped in eight assemblages were defined and arranged in two complete sequences. A sequence boundary (SB) is identified at the base of the Tupe Formation. Coastal-plain deposits capped by marine embayment lithofacies are included within sequence 1. A relative sea-level fall (SB) is recorded by an abrupt change into braided alluvial-plaine deposits (LST). The beginning of the TST is characterized by the appearance of coal and deltaic lithofacies. Late TST deposits occur above a ravinement surface and comprise bay-margin to distal-bay deposits forming a retrogradational stacking package. These lithofacies are replaced upwards by HST deposits. A relative sea-level fall (SB) is recorded by the presence of fluvial deposits overlying marine lithofacies. The Tupe Formation illustrates the transition of a coastal-plain to a marine embayment. The detection of a transgressive surface within the coastal-plain deposits of sequence 1 expanded significantly the volume of deposits now included as part of the latest Carboniferous-earliest Permian transgression, and underscores the importance of searching for transgressive signatures in non-marine environments. The presence of two sequences supports a punctuated shoreline trajectory with an overall retrogradational stacking pattern. An abrupt relative sea-level fall and increased aridity is recorded at the end of the transgressive event.

Desjardins, Patricio R.; Buatois, Luis A.; Limarino, Carlos O.; Cisterna, Gabriela A.

2009-07-01

328

Hydrological extreme events with Mike Basin  

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

329

The long wavelength topography of Beethoven and Tolstoj basins, Mercury  

NASA Astrophysics Data System (ADS)

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

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

2005-11-01

330

Structural styles of the paradox basin: Something to consider in a basin dominated by stratigraphic traps  

Microsoft Academic Search

The Paradox basin has produced a considerable amount of oil and gas from Pennsylvanian and Mississippian reservoirs. Most of the production has been from stratigraphic traps associated with subtle rejuvenated basement structures. Only the Blanding sub-basin and west flank of the salt anticlines (Lisbon Valley to Salt Wash fields) have been explored in sufficient quantity to classify as the mature

1993-01-01

331

Direct flows from the Ulleung Basin into the Yamato Basin in the East\\/Japan Sea  

Microsoft Academic Search

Using the trajectories of ARGO floats, we report direct flows from the Ulleung Basin into the Yamato Basin through a gap between the Oki Spur and the Yamato Rise over the southern part of the East\\/Japan Sea. The gap is subdivided into two narrow (northern and southern) passages by a seamount located in the middle. The flows, therefore, are narrow

Young-Gyu Park; Ara Choi; Young Ho Kim; Hong Sik Min; Jin Hwan Hwang; Sang-Hwa Choi

2010-01-01

332

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

SciTech Connect

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

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

1993-09-01

333

Detention basins, also known as dry ponds, or dry detention basins, are  

E-print Network

permanent standing pools of water. The pur- pose is to provide basic flood protec- tion and potentially decrease ero- sion. Detention basins provide flood control measures during storm events by capturing has only moderate pollutant removal. Modern stormwater detention ba- Detention Basin Retrofits By Mike

Goodman, Robert M.

334

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

SciTech Connect

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

Hines, R.A.

1986-05-01

335

Paleoproterozoic intracratonic basin processes, from breakup of Kenorland to assembly of Laurentia: Hurwitz Basin, Nunavut, Canada  

Microsoft Academic Search

The evolution of Hurwitz Basin records discontinuous tectonic processes in the Hearne domain (northern Canada) resulting from changing distant boundary conditions. Magmatic, eustatic and paleoclimatic influences, although significant, are considered to have been of secondary importance. In agreement with recent models, lower Hurwitz Group units record intracratonic basin formation during initial breakup stages of a speculative Neoarchean supercontinent (Kenorland). In

Lawrence B Aspler; Ira E Wisotzek; Jeffrey R Chiarenzelli; Miklos F Losonczy; Brian L Cousens; Vicki J McNicoll; William J Davis

2001-01-01

336

The Middle Jurassic basinal deposits of the Surmeh Formation in the Central Zagros Mountains, southwest Iran: Facies, sequence stratigraphy, and controls  

USGS Publications Warehouse

The lower part of the Lower to Upper Jurassic Surmeh Formation consists of a succession of shallow marine carbonates (Toarcian-Aalenian) overlain by a deep marine basinal succession (Aalenian-Bajocian) that grades upward to Middle to Upper Jurassic platform carbonates. The termination of shallow marine carbonate deposition of the lower part of the Surmeh Formation and the establishment of deep marine sedimentation indicate a change in the style of sedimentation in the Neotethys passive margin of southwest Iran during the Middle Jurassic. To evaluate the reasons for this change and to assess the basin configuration during the Middle Jurassic, this study focuses on facies analysis and sequence stratigraphy of the basinal deposits (pelagic and calciturbidite facies) of the Surmeh Formation, referred here as 'lower shaley unit' in the Central Zagros region. The upper Aalenian-Bajocian 'lower shaley unit' overlies, with an abrupt contact, the Toarcian-lower Aalenian platform carbonates. It consists of pelagic (calcareous shale and limestone) and calciturbidite facies grading to upper Bajocian-Bathonian platform carbonates. Calciturbidite deposits in the 'lower shaley unit' consist of various graded grainstone to lime mudstone facies containing mixed deep marine fauna and platform-derived material. These facies include quartz-bearing lithoclast/intraclast grainstone to lime mudstone, bioclast/ooid/peloid intraclast grainstone, ooid grainstone to packstone, and lime wackestone to mudstone. The calciturbidite layers are erosive-based and commonly exhibit graded bedding, incomplete Bouma turbidite sequence, flute casts, and load casts. They consist chiefly of platform-derived materials including ooids, intraclasts/lithoclasts, peloids, echinoderms, brachiopods, bivalves, and open-ocean biota, such as planktonic bivalves, crinoids, coccoliths, foraminifers, and sponge spicules. The 'lower shaley unit' constitutes the late transgressive and the main part of the highstand systems tract of a depositional sequence and grades upward to platform margin and platform interior facies as a result of late highstand basinward progradation. The sedimentary record of the 'lower shaley unit' in the Central Zagros region reveals the existence of a northwest-southeast trending platform margin during the Middle Jurassic that faced a deep basin, the 'Pars intrashelf basin' in the northeast. The thinning of calciturbidite layers towards the northeast and the widespread Middle Jurassic platform carbonates in the southern Persian Gulf states and in the Persian Gulf area support the existence of a southwest platform margin and platform interior source area. The platform margin was formed as a result of tectonic activity along the preexisting Mountain Front fault associated with Cimmerian continental rifting in northeast Gondwana. Flooding of the southwest platform margin during early to middle Bajocian resulted in the reestablishment of the carbonate sediment factory and overproduction of shallow marine carbonates associated with sea-level highstand, which led to vertical and lateral expansion of the platform and gradual infilling of the Pars intrashelf basin by late Bajocian time. ?? 2010 Springer-Verlag.

Lasemi, Y.; Jalilian, A.H.

2010-01-01

337

Propagating rift during the opening of a small oceanic basin: The Protector Basin (Scotia Arc, Antarctica)  

NASA Astrophysics Data System (ADS)

The opening of oceanic basins constitutes one of the key features of Plate Tectonics because it determines the rifting and displacement of the continental crustal blocks. Although the mechanisms of development of large oceans are well known, the opening and evolution of small and middle size oceanic basins have not been studied in detail. The Protector Basin, located in the southern Scotia Sea, is a good example of a small oceanic basin developed between two thinned continental blocks, the Pirie Bank and the Terror Rise, poorly studied up to now. A new set of multibeam bathymetry, multichannel seismic reflection, and gravity and magnetic anomaly profiles obtained on the SCAN 2001 cruise led us to determine that the Protector Basin probably opened during the period comprised between C5Dn (17.4 Ma) and C5ACn-C5ABr chrons (13.8 Ma), forming a N-S oriented spreading axis. The end of spreading is slightly younger to the north. The start of spreading is clearly diachronous, with the most complete set of chrons up to C5Dn in the southern profile, C5Cn in the middle section and only up to C5ADn in the northern part of the basin. The spreading axis propagated northwards during the basin development, producing the wedge shape of the basin. In addition, at the NE part of the basin, a reverse fault developed in the border of the Pirie Bank after basin opening accentuates the sharp northern end. Moreover, the northwestern part of the Pirie Bank margin is an extremely stretched continental crust with N-S elongated magnetic anomalies related to incipient oceanic southward propagating spreading axes. The Protector Basin shows the oldest evidence of E-W continental stretching and subsequent oceanic spreading during Middle Miocene, related with the eastward development of the Scotia Arc that continues up to Present. The relative rotation of continental blocks during the development of small sized oceanic basins by continental block drifting favoured the opening of wedge shape basins like the Protector Basin and conjugate propagating rifts.

Galindo-Zaldívar, Jesús; Bohoyo, Fernando; Maldonado, Andrés; Schreider, Anatoly; Suriñach, Emma; Vázquez, Juan Tomas

2006-01-01

338

Streamflow changes over Siberian Yenisei River Basin  

NASA Astrophysics Data System (ADS)

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

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

2004-08-01

339

Kandik basin stratigraphy, sedimentology, and structure  

SciTech Connect

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

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

1987-05-01

340

Potential for deep basin-centered gas accumulation in Hanna Basin, Wyoming  

USGS Publications Warehouse

The potential for a continuous-type basin-centered gas accumulation in the Hanna Basin in Carbon County, Wyoming, is evaluated using geologic and production data including mud-weight, hydrocarbon-show, formation-test, bottom-hole-temperature, and vitrinite reflectance data from 29 exploratory wells. This limited data set supports the presence of a hypothetical basin-centered gas play in the Hanna Basin. Two generalized structural cross sections illustrate our interpretations of possible abnormally pressured compartments. Data indicate that a gas-charged, overpressured interval may occur within the Cretaceous Mowry, Frontier, and Niobrara Formations at depths below 10,000 ft along the southern and western margins of the basin. Overpressuring may also occur near the basin center within the Steele Shale and lower Mesaverde Group section at depths below 18,000 to 20,000 ft. However, the deepest wells drilled to date (12,000 to 15,300 ft) have not encountered over-pressure in the basin center. This overpressured zone is likely to be relatively small (probably 20 to 25 miles in diameter) and is probably depleted of gas near major basement reverse faults and outcrops where gas may have escaped. Water may have invaded reservoirs through outcrops and fracture zones along the basin margins, creating an extensive normally pressured zone. A zone of subnormal pressure also may exist below the water-saturated, normal-pressure zone and above the central zone of overpressure. Subnormal pressures have been interpreted in the center of the Hanna Basin at depths ranging from 10,000 to 25,000 ft based on indirect evidence including lost-circulation zones. Three wells on the south side of the basin, where the top of the subnormally pressured zone is interpreted to cut across stratigraphic boundaries, tested the Niobrara Formation and recovered gas and oil shows with very low shut-in pressures.

Wilson, Michael S.; Dyman, Thaddeus S.; Nuccio, Vito F.

2001-01-01

341

Desert basins of the Southwest  

USGS Publications Warehouse

Ground water is among the Nation’s most important natural resources. It provides drinking water to urban and rural communities, supports irrigation and industry, sustains the flow of streams and rivers, and maintains riparian and wetland ecosystems. In many areas of the Nation, the future sustainability of ground-water resources is at risk from overuse and contamination. Because ground-water systems typically respond slowly to human actions, a long-term perspective is needed to manage this valuable resource. This publication is one in a series of fact sheets that describe ground-water-resource issues across the United States, as well as some of the activities of the U.S. Geological Survey that provide information to help others develop, manage, and protect ground-water resources in a sustainable manner. Ground-water resources in the Southwest are among the most overused in the United States. Natural recharge to aquifers is low and pumping in many areas has resulted in lowering of water tables. The consequences of large-scale removal of water from storage are becoming increasingly evident. These consequences include land subsidence; loss of springs, streams, wetlands and associated habitat; and degradation of water quality. Water managers are now seeking better ways of managing ground-water resources while looking for supplemental sources of water. This fact sheet reviews basic information on ground water in the desert basins of the Southwest. Also described are some activities of the U.S. Geological Survey (USGS) that are providing scientific information for sustainable management of ground-water resources in the Southwest. Ground-water sustainability is defined as developing and using ground water in a way that can be maintained for an indefinite time without causing unacceptable environmental, economic, or social consequences.

Leake, Stanley A.; Konieczki, Alice D.; Rees, Julie A.H.

2000-01-01

342

Hydrocarbon potential of lower Magdalena basin  

SciTech Connect

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

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

1989-03-01

343

Large Circular Basin Flooded and then Cratered  

NASA Technical Reports Server (NTRS)

As Mariner 10 passed by Mercury on its second encounter with the planet on September 21, 1974, this picture (FDS 166850) of a large circular (350 kilometer, 220 mile diameter) basin was obtained near the morning terminator. The basin appears to have been flooded with the plain material and then subsequently cratered by numerous large events. Filling of the basin, presumably by lava flows analogous to those of the lunar maria, partially inundated small craters which had formed along the basin rim (lower left) and in some places overflowed the basin rim and spilled onto the surrounding terrain (top).

The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

Image Credit: NASA/JPL/Northwestern University

1974-01-01

344

Tectonisation of basin edges on Mercury  

NASA Astrophysics Data System (ADS)

Lobate scarps on Mercury are generally accepted to be surface expressions of thrust faulting. This is taken as evidence of lithospheric contraction on a global scale, reflecting either global cooling, leading to thermal contraction and internal phase changes; or tidal despinning, leading to collapse of an equatorial bulge; or a combination of both. It has been further suggested that the orientations of lobate scarps could reflect a pattern of mantle convection. Here we review compressional tectonics localized along the interface between basin-fill and the inner walls of >200 km diameter mercurian impact basins. This occurs as outward-directed thrust faults following the inside of basin rims, and sometimes completely over-thrusting the rim location. Thrusting at the edges of low-latitude basins tends to be most strongly developed at eastern and western rims, suggesting tidal despinning as a driving force. Cross-cutting relationships show examples of thrusting that must considerably post-date the volcanic infilling of the associated basin, suggesting despinning occurring (or continuing) well after the end of the late heavy bombardment, contrary to previous expectations.

Rothery, David; Massironi, Matteo

2013-04-01

345

Petroleum geology of Solimoes Basin, Brazil  

SciTech Connect

Solimoes basin is located at the northwestern portion of the South American continent, adjacent to a subandean pericratonic belt. It constitutes a Paleozoic intracratonic basin covering an area of about 600,000 km[sup 2] and displaying a maximum sedimentary thickness of 3400 m. The tectono-sedimentary evolution can be largely related with important events that occurred at the western border of the continent. The regional flexural subsidence and tectonic deformation observed are correlated to two major phases: Pre-Andean (Paleozoic) and Andean (Mesozoic and Cenozoic). In the Andean phase, compression with shear components, of Triassic age, known as the Jurua Tectonism, became very important for oil exploration of the basin. The stratigraphic conditions considered of greatest interest for petroleum exploration comprise Devonian gas and oil sourcing shales and Carboniferous sandstones reservoirs with an evaporitic seal. The main traps are anticlines related to reverse faults. In this context, Petrobras discovered Jurua gas field in 1978 and the Rio Urucu gas and oil field in 1986. These were the first fields discovered in Brazilian Paleozoic basins. Total petroleum fields discovered in Brazilian Paleozoic basins. Total petroleum reserves discovered represent 400 million bbl of equivalent oil. Present migration and accumulation call for previous accumulation in intrabasinal Paleozoic highs and related stratigraphic traps. Late tectonism seems to have resulted in redistribution and/or escape of fluids into new traps. Less disturbed areas are expected to contain original accumulations.

Campos, J.N.P.; Meister, E.M.; Pereira, C.A.G.; Murakami, C.Y. (Petrobras, Rio de Janeiro (Brazil))

1993-02-01

346

Offshore Essaouira basin: Geology and hydrocarbon potential  

SciTech Connect

The study area lies in the offshore extension of the onshore Essaouria basin. The Mesozoic development of the Essaouira margin was largely controlled by Late Triassic to Mid-Jurassic rifting and subsequent opening of the Central Atlantic, with the evolution of a typical passive, opening of the Central Atlantic, with the evolution of a typical passive, continental margin. Diapiric salt structure recognized on seismic defines a Late Triassic-Early Jurassic salt basin in the offshore area initiated during early rifting. Subsidence and sea-level rise during Jurassic resulted in carbonate platform development. This was followed during Cretaceous and Tertiary time by the deposition of a prograding siliciclastic system. Only three wells have been drilled in this basin. Although drilled on poorly defined prospects, these wells encountered gas and oil shows. Fairly extensive seismic coverage of good quality data is now available. A study based on an integrated approach involving seismic facies definition and mapping, correlation with well data, identification of the principal control on sedimentation, and basin modeling in conjunction with source rock prediction and maturity modeling has been carried out. Results have shown that hydrocarbon potential in the offshore Essaouira basin has not yet been substantiated by drilling. Attractive structural and stratigraphic prospects exist in the shelf, shelf edge, and the slope, and await confirmation by drilling.

Jabour, H.; Ait Salem, A. (ONAREP, Rabat (Morocco))

1991-03-01

347

Corrosion in ICPP fuel storage basins  

SciTech Connect

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 cause increased corrosion of aluminum and carbon steel, but has had little effect on the stainless steel in the basin. Corrosion measurements of select aluminum fuel storage cans, aluminum fuel storage buckets, and operational support equipment have been completed. Aluminum has exhibited good general corrosion rates, but has shown accelerated preferential attack in the form of pitting. Hot dipped zinc coated carbon steel, which has been in the basin for approximately 40 years, has shown a general corrosion rate of 4 mpy, and there is evidence of large shallow pits on the surface. A welded Type 304 stainless steel corrosion coupon has shown no attack after 13 years exposure. Galvanic couples between carbon steel welded to Type 304 stainless steel occur in fuel storage yokes exposed to the basin water. These welded couples have shown galvanic attack as well as hot weld cracking and intergranular cracking. The intergranular stress corrosion cracking is attributed to crevices formed during fabrication which allowed chlorides to concentrate.

Dirk, W.J.

1993-09-01

348

Deep Mediterranean basins and their oil potential  

SciTech Connect

Mediterranean deep basins are surrounded by oil and gas producing areas, either onshore or beneath the continental shelf. In general, the Mediterranean basins have relatively flat and uniform bottoms with water depths of the order of 2,800-3,000 m (9,200-9,850 ft). In terms of the crust, the problem can be approached with the aid of geophysical studies (gravimetry, magnetism, and seismic) and variations in heat flow. The superposition of these varied data thus enables us to schematize the nature of crust of the Mediterranean basins. The main potential oil and gas objectives are the Oligocene and Miocene Series, deposited after and during the main orogenic phases, and covered by thick Messinian evaporites and Pliocene-Pleistocene marine sediments. Underlying the Ionian Sea, the Mediterranean ridge, and the eastern basins, Mesozoic and Paleogene rocks may be possible targets. In conclusion, the deep Mediterranean basins could hide large targets. The exploration effort will require various improvements (excluding that of the price o

Burollet, P.F.

1984-09-01

349

Maturation modeling in Otway basin, Australia  

SciTech Connect

The Otway basin is a Jurassic to Pliocene sedimentary basin formed on the southern Australian continental margin. Its formation is associated with rifting and breakup of the Australian and Antarctic plates. Lithospheric cooling and contraction have probably produced post-breakup subsidence. Either lithospheric stretching or deep crustal metamorphism may have produced pre-breakup subsidence. These mechanisms have identifiable thermal histories. Organic diagenesis (specifically the reflectance of vitrinite in oil) is empirically determined by the thermal and depositional history of an organic sediment. Thus, the stages of hydrocarbon maturity of Otway basin sediments can be modeled. Depositional history is determined from ''geo-history analysis'' and thermal history depends on the subsidence mechanism applied to the basin. A paleo-heat-flow history derived from the deep crustal metamorphism model of subsidence produces a maturation profile with depth that is consistent with observed vitrinite reflectance data, although organic diagenesis modeling is relatively insensitive to precise details of thermal history. Depositional and maturation history modeling for the present day, 20 Ma ago, 40 Ma ago, and 60 Ma ago is applied to a seismic profile across the southern Australian continental shelf in the Otway basin as a demonstration of the projection backward in time of sedimentation and organic diagenesis.

Middleton, M.F. (CSIRO Division of Fossil Fuels, North Ryde, NSW, Australia); Falvey, D.A.

1983-02-01

350

A geological history of the Turkana Basin.  

PubMed

The Turkana Basin preserves a long and detailed record of biotic evolution, cultural development, and rift valley geology in its sedimentary strata. Before the formation of the modern basin, Cretaceous fluvial systems, Paleogene lakes, and Oligo-Miocene volcano-sedimentary sequences left fossil-bearing strata in the region. These deposits were in part related to an early system of rift basins that stretched from Sudan to the Indian Ocean. The present-day basin has its origins in Pliocene tectonic developments of the modern rift, with subsidence making room for more than one kilometer of Plio-Pleistocene strata. Much of this sequence belongs to the Omo Group, richly fossiliferous sediments associated with the ancestral Omo River and its tributaries. Modern Lake Turkana has a record stretching back more than 200 thousand years, with earlier lake phases throughout the Plio-Pleistocene. The geologic history of the basin is one of dynamic landscapes responding to environmental influences, including tectonics, volcanic activity and climate. PMID:22170690

Feibel, Craig S

2011-01-01

351

Modified Streamflows 1990 Level of Irrigation : Missouri, Colorado, Peace and Slave River Basin, 1928-1989.  

SciTech Connect

This report presents data for monthly mean streamflows adjusted for storage change, evaporation, and irrigation, for the years 1928-1990, for the Colorado River Basin, the Missouri River Basin, the Peace River Basin, and the Slave River Basin.

A.G. Crook Company; United States. Bonneville Power Administration

1993-07-01

352

Tectonics and Quaternary sequence development of basins along the active Vienna Basin strike-slip fault  

NASA Astrophysics Data System (ADS)

The Vienna Basin strike-slip fault is a continent scale active fault extending over a distance of some 300 km from the Eastern Alps through the Vienna Basin into the Western Carpathians. Sinistral movement causes the formation of several tight Pleistocene strike-slip basins within the older Miocene Vienna Basin. These sub-basins not only have a high relevance for groundwater exploitation but their fault activities depict serious seismic hazards. Basins are filled with fluvial sediments from the Danube and, closer to the Alpine front, with thick alluvial fan deposits. However, knowledge on the stratigraphy and tectonics is sparse and rather limited to the Miocene part of the Vienna Basin as it hosts giant hydrocarbon fields. This study tackles two major questions: (i) What is the effect of Quaternary climatic oscillations and subsidence on the sequence development of the alluvial fans and (ii) what is the deformation style of these basins? To answer (i) we present a series of new OSL ages and biotic data from both, surface and cores, to better constrain the timing of fan activity, fan abandonment but also to constrain the onset of Pleistocene basin formation. For (ii) we utilize information from unparalleled geophysical and geological data. Specifically we utilize industrial Bouguer gravity's derivatives to highlight shallow structures and to compensate for the lag of fault trace information. The integration of geological and geophysical data highlights textbook-like models of strike-slip basins, with typical features like Riedel shears with intervening relay ramps, en-echelon sidewall faults and a cross-basin fault zone delimiting opposite depocenters. The infill reflects a distinct cyclicity with thick sequences of coarse sediments deposited during colder periods and thin sequences of paleosol and flood sediments deposited during warmer periods. Ages indicate main activity around the short peak glacial periods and basin formation starting c. 300 ka ago. The distinct sequence development and the strong contrast to the underlying marine deposits is a very suitable setting to apply geophysical methods constraining basins' deformation style.

Salcher, B.; Lomax, J.; Meurers, B.; Smit, J.; Preusser, F.; Decker, K.

2012-04-01

353

Morphometric analysis of Suketi river basin, Himachal Himalaya, India  

NASA Astrophysics Data System (ADS)

Suketi river basin is located in the Mandi district of Himachal Pradesh, India. It encompasses a central inter-montane valley and surrounding mountainous terrain in the Lower Himachal Himalaya. Morphometric analysis of the Suketi river basin was carried out to study its drainage characteristics and overall groundwater resource potential. The entire Suketi river basin has been divided into five sub-basins based on the catchment areas of Suketi trunk stream and its major tributaries. Quantitative assessment of each sub-basin was carried out for its linear, areal, and relief aspects. The analysis reveals that the drainage network of the entire Suketi river basin constitutes a 7th order basin. Out of five sub-basins, Kansa khad sub-basin (KKSB), Gangli khad sub-basin (GKSB) and Ratti khad sub-basin (RKSB) are 5th order sub-basins. The Dadour khad sub-basin (DKSB) is 6th order sub-basin, while Suketi trunk stream sub-basin (STSSB) is a 7th order sub-basin. The entire drainage basin area reflects late youth to early mature stage of development of the fluvial geomorphic cycle, which is dominated by rain and snow fed lower order streams. It has low stream frequency (Fs) and moderate drainage density (Dd) of 2.69 km/km 2. Bifurcation ratios (Rb) of various stream orders indicate that streams up to 3rd order are surging through highly dissected mountainous terrain, which facilitates high overland flow and less recharge into the sub-surface resulting in low groundwater potential in the zones of 1st, 2nd, and 3rd order streams of the Suketi river basin. The circulatory ratio (Rc) of 0.65 and elongation ratio (Re) of 0.80 show elongated nature of the Suketi river basin, while infiltration number (If) of 10.66 indicates dominance of relief features and low groundwater potential in the high altitude mountainous terrain. The asymmetry factor (Af) of Suketi river basin indicates that the palaeo-tectonic tilting, at drainage basin scale, was towards the downstream right side of the drainage basin. The slope map of Suketi river basin has been classified into three main zones, which delineate the runoff zone in the mountains, recharge zone in the transition zone between mountains and valley plane, and discharge zone in the plane areas of Balh valley.

Pophare, Anil M.; Balpande, Umesh S.

2014-10-01

354

72 FR 24267 - Gunnison Basin Federal Lands Travel Management Plan  

Federal Register 2010, 2011, 2012, 2013, 2014

...DEPARTMENT OF AGRICULTURE Forest Service DEPARTMENT OF...Land Management Gunnison Basin Federal Lands Travel Management Plan AGENCIES: Forest Service, USDA, Bureau...by BLM. Both National Forest System lands and public lands in the Gunnison Basin will be addressed...

2007-05-02

355

65 FR 59820 - Lake Tahoe Basin Federal Advisory Committee; Meeting  

Federal Register 2010, 2011, 2012, 2013, 2014

...Meeting AGENCY: Forest Service, USDA...The Lake Tahoe Basin Federal Advisory...at the Tahoe City Public Utility...at the Tahoe City Public Utility...Drive, Tahoe City, California...Lake Tahoe Basin Management Unit, Forest Service,...

2000-10-06

356

75 FR 6348 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013, 2014

...Nevada 89451-9500. FOR FURTHER INFORMATION CONTACT: Arla Hams, Lake Tahoe Basin Management Unit (LTBMU), Forest Service...the meeting. Please refer any written comments attention Arla Hams, Lake Tahoe Basin Management Unit at the contact address...

2010-02-09

357

75 FR 38833 - Walker River Basin Acquisition Program  

Federal Register 2010, 2011, 2012, 2013, 2014

...OF THE INTERIOR Bureau of Reclamation Walker River Basin Acquisition Program AGENCY...Environmental Impact Statement (EIS) for the Walker River Basin Acquisition Program (Acquisition...INFORMATION: Since 1882, diversions from the Walker River, primarily for irrigated...

2010-07-06

358

76 FR 7809 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013, 2014

...DEPARTMENT OF AGRICULTURE Forest Service Lake Tahoe Basin Federal Advisory Committee...SUMMARY: The Lake Tahoe Basin Federal Advisory Committee...a meeting on February 28, 2011 at the Lake Tahoe Community College, Aspen...

2011-02-11

359

77 FR 42696 - Lake Tahoe Basin Federal Advisory Committee (LTFAC)  

Federal Register 2010, 2011, 2012, 2013, 2014

...DEPARTMENT OF AGRICULTURE Forest Service Lake Tahoe Basin Federal Advisory Committee...SUMMARY: The Lake Tahoe Federal Advisory Committee will hold a meeting on August 9, 2012 at the Lake Tahoe Basin Management Unit, 35...

2012-07-20

360

Independent External Evaluation of The Columbia Basin Water Transactions Program  

E-print Network

Independent External Evaluation of The Columbia Basin Water Transactions Program (2003 of Water Transactions...............................................32 Program Administration......................................................................................................45 Annex 1: Evaluation Matrix Annex 2: Limiting Factors to Water Transactions in the Columbia Basin

361

View westsouthwest of marine railway at reserve basin of Philadelphia ...  

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

View west-southwest of marine railway at reserve basin of Philadelphia Naval Shipyard. - Naval Base Philadelphia-Philadelphia Naval Shipyard, Reserve Basin & Marine Railway, League Island, Philadelphia, Philadelphia County, PA

362

Integrated Peri-Tethyan Basins studies (Peri-Tethys Programme)  

NASA Astrophysics Data System (ADS)

This issue brings together 12 papers presenting results of geodynamic/subsidence studies performed in the frame of the Peri-Tethys Programme (PTP). The areas in question are for the northern Peri-Tethyan Platform: the Dniepr-Donets, Precaspian, Polish Basin, southern Carpathians, North Fore-Caucasus, South Caspian and Black Sea basins. For the southern Peri-Tethyan Platform, the basins studied include basins of Morocco, North Algerian Atlas' basins, Tunisia and Arabia basins. Some features of these basins' evolution are given for each area. The tectonic evolution and driving mechanism of these basins' subsidence are placed in the general context of the break-up of Pangea, opening of the Tethys ocean, followed by its closure before the general collisional regime.

Brunet, Marie-Françoise; Cloetingh, Sierd

2003-02-01

363

Geology of the Caloris basin, Mercury: a view from MESSENGER.  

PubMed

The Caloris basin, the youngest known large impact basin on Mercury, is revealed in MESSENGER images to be modified by volcanism and deformation in a manner distinct from that of lunar impact basins. The morphology and spatial distribution of basin materials themselves closely match lunar counterparts. Evidence for a volcanic origin of the basin's interior plains includes embayed craters on the basin floor and diffuse deposits surrounding rimless depressions interpreted to be of pyroclastic origin. Unlike lunar maria, the volcanic plains in Caloris are higher in albedo than surrounding basin materials and lack spectral evidence for ferrous iron-bearing silicates. Tectonic landforms, contractional wrinkle ridges and extensional troughs, have distributions and age relations different from their counterparts in and around lunar basins, indicating a different stress history. PMID:18599772

Murchie, Scott L; Watters, Thomas R; Robinson, Mark S; Head, James W; Strom, Robert G; Chapman, Clark R; Solomon, Sean C; McClintock, William E; Prockter, Louise M; Domingue, Deborah L; Blewett, David T

2008-07-01

364

Unseen Colorado Mountain Aquifers Throw Water on "Teflon Basin" Myth  

NSF Publications Database

... Mountain Aquifers Throw Water on "Teflon Basin" Myth A researcher investigates the snowpack at the ... myth that high mountain valleys act as "Teflon basins" to rush water downstream. Scientist Mark ...

365

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

366

Simulation of Seismic Wave Propagation Through Geometrically Complex Basins - The Dead Sea Basin  

NASA Astrophysics Data System (ADS)

The Dead Sea Transform (DST) is the source for some of the largest earthquakes in the Eastern Mediterranean, including the 1927 Mw 6.2 Jericho earthquake and the 1995 Mw 7.2 Gulf of Aqaba earthquake. The seismic hazard presented by the DST threatens the Israeli, Palestinian and Jordanian populations alike. In Israel, several deep and structurally complex sedimentary basins are associated with the DST. These basins are up to 10 km deep and typically bounded by active fault zones. The low seismicity rate of the DST combined with a sparse seismic network in Israel that provides poor coverage of sedimentary basins, results in a critical knowledge gap. It is therefore necessary to complement the limited instrumental data with synthetic data based on computational modeling, in order to study the effects of earthquake ground motion in these sedimentary basins. In this research we performed a ground motion analysis in the Dead Sea Basin (DSB) using a finite-difference code capable of simulating seismic wave propagation in a 3-D heterogeneous earth. Two cross-sections transecting the DSB were compiled based on currently available geological and geophysical data and were used for wave propagation simulations. Results indicate a complex pattern of ground motion amplification affected by the geometric features in the basin. To distinguish between the individual contributions of each geometrical feature in the basin, we developed a semi-quantitative decomposition approach. This approach enabled us to interpret the DSB results as follows: (a) Ground motion amplification as a result of resonance and anelastic effects, occurs basin-wide due to a high impedance contrast at the base of the uppermost layer. (b) Steep faults generate a strong edge-effect that further amplifies ground motions. (c) Sub-basins cause geometrical focusing that under certain circumstances significantly amplifies ground motions. (d) Salt diapirs diverge seismic energy and cause a decrease in ground motion amplitude.

Shani-Kadmiel, S.; Tsesarsky, M.; Gvirtzman, Z.; Louie, J. N.

2011-12-01

367

Evolution of the San Jorge basin, Argentina  

SciTech Connect

The San Jorge basin, although small, is the most important hydrocarbon-producing basin in Argentina. Remaining untested potential is high because of the presence of good source rock, favorable structural complexity, and multiple reservoirs. Reservoir quality is commonly low because of the highly tuffaceous sandstones. The sedimentary fill of the basin is closely related to its tectonic history. Northwest-southeast-trending grabens formed and filled during a Triassic and Early Jurassic early rift phase, climaxing with a pervasive Middle Jurassic volcanic episode; continued growth and filling of the basin occurred during a Late Jurassic-earliest Cretaceous late rift phase and Cretaceous early and late sag phases. Late Cretaceous-early Tertiary extension set up many of the present-day structural traps along normal faults. Middle Tertiary Andean compression produced the narrow, north-south San Bernardo structural belt, which exhibits reversed movement on older, normal, graben-bounding faults and on local, low-angle thrust faults. Marked early to middle Tertiary erosion produced a significant unconformity within Cretaceous beds around basin margins. Origin of Upper Jurassic and lowermost Cretaceous sedimentary fill is primarily lacustrine or fluvial in origin. Lacustrine, organic-rich black shales are fringed by oolitic and other limestones and fluvial-deltaic sandstones derived mostly from the north. A significant southern source of sand existed during the Valanginian. Interbedded marine shales occur mostly to the west toward a presumed marine seaway connection to the northern Magallanes basin. Middle to Upper Cretaceous sedimentary rocks, sourced mostly from the north, are mainly fluvial sandstone-shale successions with some minor lacustrine influence. Reservoir quality glauconitic sands were deposited during a Late Cretaceous-early Tertiary marine incursion from the Atlantic.

Fitzgerald, M.G. (Exxon Production Research Co., Houston, TX (USA)); Uliana, M.A. (ASTRA C.A.P.S.A., Buenos Aires (Argentina)); Biddle, K.T. (Exxon Co., International, Houston, TX (USA)); Mitchum, R.M. Jr.

1990-06-01

368

Sedimentation in Canada Basin, Western Arctic  

NASA Astrophysics Data System (ADS)

The Canada Basin of the western Arctic Ocean is the least studied ocean basin on Earth. Marine seismic field programs were conducted during the past 5 years in order to study the geology, sedimentary history and geomorphology of the region. As part of this program, five annual icebreaker expeditions acquired bathymetric, seismic reflection and seismic refraction data on a regional scale. More than 12,000 km of multi-channel seismic reflection data and 120 sonobuoy seismic refraction records over abyssal plain and continental rise regions of Canada Basin, Northwind Ridge and Alpha Ridge were acquired. The success of these programs was achieved through novel technical modifications to equipment to permit towing in heavy ice conditions and through collaboration between multiple Canadian and US agencies and institutions, enabling utilization of two ice breakers during seismic and multibeam data acquisition in heavy ice. The seafloor of the Canada Basin is remarkably flat-lying in its central region, with little bathymetric change over most of its extent. The sedimentary succession is generally flat lying with reflections extending over hundreds of km. These reflections onlap bathymetric highs, such as Alpha and Northwind ridges. The sedimentary succession is thickest in the Beaufort Sea region, reaching more than 6.5 km, and generally thins to the north and west. Reflection characteristics suggest that sediment volume input to the Arctic Ocean has been high and dominated by turbidity current deposition, similar to Amundsen and Nansen Basins of the eastern Arctic. These turbidites originate from the eastern and southern continental margins. There is no evidence of contemporaneous or post-depositional reworking by bottom currents. Additionally, there is little evidence of tectonic deformation after primary basin-forming events except in the NE quadrant, nearer Alpha Ridge. In this area, there is significant normal faulting propagating from basement through much of the sedimentary succession. Basement graben stuctures in combination with these faults imply possible crustal extension contemporaneous with deposition.

Mosher, D. C.; Shimeld, J.; Jackson, R.; Hutchinson, D. R.; Chapman, B.; Chian, D.; Childs, J. R.; Mayer, L. A.; Edwards, B. D.; Verhoef, J.

2010-12-01

369

The "normal" elongation of river basins  

NASA Astrophysics Data System (ADS)

The spacing between major transverse rivers at the front of Earth's linear mountain belts consistently scales with about half of the mountain half-width [1], despite strong differences in climate and rock uplift rates. Like other empirical measures describing drainage network geometry this result seems to indicate that the form of river basins, among other properties of landscapes, is invariant. Paradoxically, in many current landscape evolution models, the patterns of drainage network organization, as seen for example in drainage density and channel spacing, seem to depend on both climate [2-4] and tectonics [5]. Hovius' observation [1] is one of several unexplained "laws" in geomorphology that still sheds mystery on how water, and rivers in particular, shape the Earth's landscapes. This narrow range of drainage network shapes found in the Earth's orogens is classicaly regarded as an optimal catchment geometry that embodies a "most probable state" in the uplift-erosion system of a linear mountain belt. River basins currently having an aspect away from this geometry are usually considered unstable and expected to re-equilibrate over geological time-scales. Here I show that the Length/Width~2 aspect ratio of drainage basins in linear mountain belts is the natural expectation of sampling a uniform or normal distribution of basin shapes, and bears no information on the geomorphic processes responsible for landscape development. This finding also applies to Hack's [6] law of river basins areas and lengths, a close parent of Hovius' law. [1]Hovius, N. Basin Res. 8, 29-44 (1996) [2]Simpson, G. & Schlunegger, F. J. Geophys. Res. 108, 2300 (2003) [3]Tucker, G. & Bras, R. Water Resour. Res. 34, 2751-2764 (1998) [4]Tucker, G. & Slingerland, R. Water Resour. Res. 33, 2031-2047 (1997) [5]Tucker, G. E. & Whipple, K. X. J. Geophys. Res. 107, 1-1 (2002) [6]Hack, J. US Geol. Surv. Prof. Pap. 294-B (1957)

Castelltort, Sebastien

2013-04-01

370

Atlantic Mesozoic marginal basins: an Iberian view  

SciTech Connect

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

Wilson, R.C.L.

1987-05-01

371

Avian cholera in Nebraska's Rainwater Basin  

USGS Publications Warehouse

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

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

1984-01-01

372

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

373

Science for the Changing Great Basin  

USGS Publications Warehouse

The U.S. Geological Survey (USGS), with its multidisciplinary structure and role as a federal science organization, is well suited to provide integrated science in the Great Basin of the western United States. A research strategy developed by the USGS and collaborating partners addresses critical management issues in the basin, including invasive species, status and trends of wildlife populations and communities, wildfire, global climate change, and riparian and wetland habitats. Information obtained through implementation of this strategy will be important for decision-making by natural-resource managers.

Beever, Erik; Pyke, David A.

2004-01-01

374

The Lake Tahoe basin bird species  

E-print Network

We compiled a list of all vertebrate species that have ever been recorded in the Lake Tahoe basin (Table G-1). We determined that the basin has been at least visited by a total of 262 birds, 66 mammals, 8 reptiles, 6 amphibians, and 27 fish, not including domesticated species. In general, information on vertebrates was relatively comprehensive, and the species lists we compiled are fairly accurate and complete. We discuss the data sources consulted, and the criteria used to determine the status of each species below. Table G-1 provides scientific names for all species discussed in the text. Birds

Matthew D. Schlesinger; J. Shane Romsos

375

Drainage basin characteristics from ERTS data  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. ERTS-derived measurements of forests, riparian vegetation, open water, and combined agricultural and urban land use were added to an available matrix of map-derived basin characteristics. The matrix of basin characteristics was correlated with 40 stream flow characteristics by multiple regression techniques. Fifteen out of the 40 equations were improved. If the technique can be transferred to other physiographic regions in the nation, the opportunity exists for a potential annual savings in operations of about $250,000.

Hollyday, E. F. (principal investigator)

1975-01-01

376

Conservation in the Delaware River Basin  

SciTech Connect

The Delaware River Basin Commission (DRBC) has embarked on an ambitious water conservation program to reduce the demand for water. Conservation has become an integral component of the commission`s strategy to manage water supplies in the four-state Delaware River Basin. The program includes both regulatory and educational initiatives. DRBC has adopted five conservation regulations, which pertain to source metering, service metering, leak detection and repair, water conservation performance standards for plumbing fixtures and fittings, and requirements for water conservation plans and rate structures. DRBC also sponsors information and education events, such as symposiums on selected topics and water conservation technology transfer sessions with major industrial and commercial groups.

Featherstone, J. [Delaware River Basin Commission, Trenton, NJ (United States)

1996-01-01

377

A new survey of multiring impact basins on Mars  

SciTech Connect

Multiring impact basins have profoundly influenced the geologic evolution of Mars. The authors compile and summarize the evidence for Martian impact basins and suggest eight new examples. Multiring basins on Mars define three morphologic subclasses with increasing basin size. Basins having diameters 300 < D < 1,850 km are morphologically comparable to the classic lunar Orientale basin. Argyre type basins (1,850 < D < 3,600 km) are characterized by a rugged annulus and concentric grabens. The largest, Chryse type basins (D > 3,600 km) have extremely shallow topographic profiles and numerous concentric structures expressed as scarps, massifs, and channels. Radial and concentric structures analogous to those associated with Orientale are not apparent for basins of Argyre size or larger. These variations in basin morphology and structure may be associated with mechanical interactions between basin-forming impacts, relatively thin, weak lithosphere, and, for the largest impacts, spherical target geometry. Multiring basins are recognized on all parts of Mars, including Tharsis, Elysium, and the northern lowlands. Much of the subsequent resurfacing of cratered terrain such as Lunae Planum ridged plains is associated spatially with multiring basins. Nucleation of long-lived volcanic complexes in Tharsis and Elysium was probably aided by early impact basins. The planetary terrain dichotomy was probably established during the period of heavy meteoritic bombardment, and subsequent processes in the northern plains region were not sufficiently vigorous to destroy or completely obscure the underlying multiring basin fabric. The revised population of multiring basins is consistent with the size frequency distribution of craters < 500 km in diameter on Mars.

Schultz, R.A.; Frey, H.V. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

1990-08-30

378

72 FR 11323 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...  

Federal Register 2010, 2011, 2012, 2013, 2014

...DEPARTMENT OF AGRICULTURE Forest Service Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder...Supervisor, Medicine Bow-Routt National Forests and Thunder Basin National Grassland, 2468...

2007-03-13

379

Tobacco vs. helminths in Congo basin hunter-gatherers Tobacco use vs. helminths in Congo basin hunter-gatherers  

E-print Network

Tobacco vs. helminths in Congo basin hunter-gatherers 1 Tobacco use vs-546-9257 #12;Tobacco vs. helminths in Congo basin hunter-gatherers 2 Summary population use tobacco, and approximately one billion people are infected with one

380

book reviews Climate Changeon the Great Lakes Basin. 1992.  

E-print Network

book reviews Climate Changeon the Great Lakes Basin. 1992. 45 pp. $--free. Paperbound is a compilation of five papers presented at the Symposium of Climate Change on the Great Lakes Basin held as part. The resultsgivenprovideanoverviewofvariousaspectsof climaticchangerelativetotheGreatLakesBasin.The usual caveats regarding use and interpretation

381

64 FR 54617 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013, 2014

...Service Lake Tahoe Basin Federal Advisory...Committee AGENCY: Forest Service, USDA...The Lake Tahoe Basin Federal Advisory...1999, at the City of South Lake...held at the City of South Lake...Lake Tahoe Basin Management Unit, Forest Service,...

1999-10-07

382

64 FR 35986 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013, 2014

...Service Lake Tahoe Basin Federal Advisory...Committee AGENCY: Forest Service, USDA...The Lake Tahoe Basin Federal Advisory...1999, at the City of South Lake...held at the City of South Lake...Lake Tahoe Basin Management Unit, Forest Service,...

1999-07-02

383

67 FR 54 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013, 2014

...Service Lake Tahoe Basin Federal Advisory Committee AGENCY: Forest Service, USDA...The Lake Tahoe Basin Federal Advisory...South Lake Tahoe City Council Chambers...South Lake Tahoe City Council Chambers...Stafford, Lake Tahoe Basin Management Unit, [[Page 55

2002-01-02

384

64 FR 45505 - Lake Tahoe Basin Federal Advisory Committee  

Federal Register 2010, 2011, 2012, 2013, 2014

...Service Lake Tahoe Basin Federal Advisory...Committee AGENCY: Forest Service, USDA...The Lake Tahoe Basin Federal Advisory...Road, Tahoe City, CA. This...held at the City of South Lake...Lake Tahoe Basin Management Unit, Forest Service,...

1999-08-20

385

Evolution and hydrocarbon prospectivity of the Douala Basin, Cameroon  

Microsoft Academic Search

The Douala Basin is a stable Atlantic-type, predominantly offshore basin and forms the northern terminal of a series of divergent passive margin basins located on the Southwest coast of Africa that resulted from the rifting of Africa from South America. An integration of new studies including detailed well, biostratigraphic, sedimentological, geochemical and seismic data has confirmed that the tectonostratigraphic evolution

M. Batupe; S. Tampu; R. S. Aboma

1995-01-01

386

Geology and hydrocarbon potential of the Oued Mya Basin, Algeria  

Microsoft Academic Search

The hydrocarbon System Ourd Mya is located in the Sahara Basin. It is one of the producing basin in Algeria. The stratigraphic section consists of Paleozoic and Mesosoic, it is about 5000m thick. In the eastern part, the basin is limited by the Hassi-Messaoud high zone which is a giant oil field producing from the Cambrian sands. The western part

O. Benamrane; M. Messaoudi; H. Messelles

1992-01-01

387

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. Shown here is an aerial view of...

2009-11-30

388

Lynnhaven River Basin Ecosystem Restoration Project Virginia Beach, Virginia  

E-print Network

Lynnhaven River Basin Ecosystem Restoration Project Virginia Beach, Virginia 24 September 2013 the Lynnhaven River Basin. The watershed is located within the City of Virginia Beach in Southeastern Virginia is the City of Virginia Beach. The study area consists of the entire Lynnhaven River Basin, a 64-square- mile

US Army Corps of Engineers

389

HISTORY OF EARLY CENOZOIC VERTEBRATE PALEONTOLOGY IN THE BIGHORN BASIN  

Microsoft Academic Search

The first fossil mammals from the Bighorn Basin were found by Wortman and described by Cope in 1880. These are early Wasatchian in age, and probably came from the southern part of the basin. During Wortman's 1881 expedition he collected mammalian faunas of both middle and late Wasatchian age in the central Bighorn Basin. The Clarkforkian fauna was first documented

Philip D. Gingerich