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Sample records for basin south china

  1. Can the South China Sea tell us anything about Canada Basin?

    NASA Astrophysics Data System (ADS)

    Stephenson, Randell; Li, Lu

    2016-04-01

    The Canada Basin (a sub-basin within the Amerasia Basin) and the South China Sea both preserve oceanic spreading centres and adjacent passive continental margins characterised by broad continent-ocean transition zones with hyper-extended continental crust. There are indications that hyper-extension in the South China Sea occurred mainly as a result of flow within a weak lower crustal layer and that it occurred both before and after plate break-up and the onset of ocean lithosphere formation at the sea-floor spreading axis. Available geophysical data from Canada Basin permit similar inferences. Both basins are about the same size and the oceanic segment in both is about the same size. Seafloor spreading in the South China Sea took place in the Cenozoic whereas in Canada Basin it is widely believed to have occurred during the Cretaceous. Widespread magmatism expressed as the High Arctic Large Igneous Province (HALIP) may or may not have played an intrinsic, linked, role in Canada Basin formation. No similar LIP is associated with the South China Sea although one mechanism proposed to have driven its formation is ascribed to mantle plume activity in its northernmost part. More conventionally the mechanism of opening of the South China Sea is considered to be "passive" rather than "active", related to plate reconfigurations in the southeast Asia region linked or not linked to the nearby collision of India and Eurasia and/or subduction of a "proto-South China Sea". The driving mechanism for opening of Canada Basin is poorly discussed in the literature but is generally ascribed to paleo-tectonic plate reconfigurations and subduction in the northern Pacific (Eurasia-North America plates) region in the Mesozoic. Can the South China Sea tell us anything about Canada Basin in terms of the pre-existing lithosphere of each and the geodynamic processes leading to its hyper-extension and eventual break-up?

  2. South China connected to north India in Gondwana: sedimentary basin and detrital provenance analyses

    NASA Astrophysics Data System (ADS)

    Yao, W.; Li, Z. X.; Li, W. X.; Li, X. H.; Yang, J. H.

    2015-12-01

    The paleoposition of South China during the Ediacaran-Silurian is important for understanding the assembly of Gondwana. We report here the tectonostratigraphic evolution of the Ediacaran-Silurian Nanhua foreland basin in South China, and discuss South China's connection with Gondwana and potential tectonic triggers for both the Wuyi-Yunkai orogeny in South China and the Bhimphedian orogeny in north India. The Nanhua basin was involved in a three-stage evolution, which are: Stage 1 (the Ediacaran-Cambrian) recording the start of tectonic subsidence with turbiditic marine clastic deposition, fed by exotic orogens outboard South China; Stage 2 (the Ordovician to earliest-Silurian) featured by migrating depocentres with dominant shallow marine to deltaic clastic deposition, fed by the local Wuyi-Yunkai orogen; and Stage 3 (the Silurian) showing the arrival of depocentre in the Yangtze Block during the waning stage of the Wuyi-Yunkai orogeny with deltaic deposition in the remanent foreland basin. Detrital zircon analyses of the Ediacaran-Silurian sandstones across the Nanhua basin reveal a prominent age population of 1100-900 Ma (with a peak age at ~980 Ma) and moderate populations of Archean-Paleozoic ages, grossly matching that of crystalline and sedimentary rocks in northern India. Zircon isotopes of the Stage 1 samples suggest three Precambrian episodes of juvenile crustal growth at 3.0 Ga, 2.5 Ga and 1.0 Ga, and a major crustal reworking at 580-500 Ma for the source areas, which are constraint to be northwestern India and its surrounding orogens. Together with other evidence, we propose that South China likely collided with northwestern India during the Gondwana assembly, generated the Bhimphedian orogeny in north India and formed two foreland basins on both the north India and South China sides. Far-field stress of the collision triggered the Ordovician-Silurian Wuyi-Yunkai orogeny in South China. The Stage 2-3 samples in the Nanhua basin of South China were shed

  3. Tectonostratigraphic history of the Ediacaran-Silurian Nanhua foreland basin in South China

    NASA Astrophysics Data System (ADS)

    Yao, Wei-Hua; Li, Zheng-Xiang

    2016-04-01

    This paper presents the tectonostratigraphic evolution of the Ediacaran-Silurian Nanhua Basin in South China and explores the relationship between clastic sedimentation in the basin and evolution of the adjacent Wuyi-Yunkai orogen. Sedimentary facies in the basin comprises, in an ascending order, turbiditic marine, shallow marine, and fluvial-dominated deltaic facies, featuring a lateral migration from southeast to northwest. We interpret the Ediacaran-Silurian Nanhua Basin as a foreland basin with a three-stage evolution history. Stage 1: the Ediacaran-Cambrian stage, recording the start of tectonic subsidence with turbiditic marine siliciclastic deposition, fed by exotic orogens outboard South China; Stage 2: the Ordovician to earliest-Silurian stage, characterized by a migrating depocenter with dominant shallow marine and deltaic siliciclastic deposition, fed by the local and northwestward propagating Wuyi-Yunkai orogen; Stage 3: the Silurian stage, showing the arrival of depocenter in the Yangtze Block during the waning stage of the orogeny with deltaic deposition in the remanent foreland basin. The Wuyi-Yunkai orogen remained the dominant sedimentary source region during Stage 3. Stage 1 was likely related to the collision of the South China Block toward northern India during the assembly of Gondwana, whereas Stages 2 and 3 recorded sedimentation during the northwestward propagation and subsequent orogenic root delamination/collapse of the Wuyi-Yunkai orogen, respectively. The Wuyi-Yunkai orogeny in South China is interpreted to have resulted from the far-field stress of the collision between South China and Indian Gondwana.

  4. Mid-Pleistocene Acheulean-like stone technology of the Bose basin, South China.

    PubMed

    Yamei, H; Potts, R; Baoyin, Y; Zhengtang, G; Deino, A; Wei, W; Clark, J; Guangmao, X; Weiwen, H

    2000-03-01

    Stone artifacts from the Bose basin, South China, are associated with tektites dated to 803,000 +/- 3000 years ago and represent the oldest known large cutting tools (LCTs) in East Asia. Bose toolmaking is compatible with Mode 2 (Acheulean) technologies in Africa in its targeted manufacture and biased spatial distribution of LCTs, large-scale flaking, and high flake scar counts. Acheulean-like tools in the mid-Pleistocene of South China imply that Mode 2 technical advances were manifested in East Asia contemporaneously with handaxe technology in Africa and western Eurasia. Bose lithic technology is associated with a tektite airfall and forest burning.

  5. Mid-Pleistocene Acheulean-like stone technology of the Bose basin, South China.

    PubMed

    Yamei, H; Potts, R; Baoyin, Y; Zhengtang, G; Deino, A; Wei, W; Clark, J; Guangmao, X; Weiwen, H

    2000-03-01

    Stone artifacts from the Bose basin, South China, are associated with tektites dated to 803,000 +/- 3000 years ago and represent the oldest known large cutting tools (LCTs) in East Asia. Bose toolmaking is compatible with Mode 2 (Acheulean) technologies in Africa in its targeted manufacture and biased spatial distribution of LCTs, large-scale flaking, and high flake scar counts. Acheulean-like tools in the mid-Pleistocene of South China imply that Mode 2 technical advances were manifested in East Asia contemporaneously with handaxe technology in Africa and western Eurasia. Bose lithic technology is associated with a tektite airfall and forest burning. PMID:10698732

  6. Detrital provenance of Early Mesozoic basins in the Jiangnan domain, South China: Paleogeographic and geodynamic implications

    NASA Astrophysics Data System (ADS)

    Xu, Xianbing; Tang, Shuai; Lin, Shoufa

    2016-04-01

    Detrital provenance analysis is an effective way to understand paleogeographic change and geodynamics. In this paper, we present petrological, whole-rock geochemical and detrital zircon U-Pb geochronological analysis of Early and Middle Jurassic terrestrial clastic rocks in the Jingdezhen Basin and the Huangshan Basin in the Jiangnan domain, South China. Petrology and whole-rock geochemistry show that the source rocks are dominated by intermediate to acid component. The Chemical Index of Alteration ranges from 69 to 86, suggesting a moderate weathering history for the source rocks. The Early-Middle Jurassic sediments in the Jingdezhen and Huangshan basins were mostly sourced from magmatogenic greywackes and felsic magmatic rocks, respectively. Detrital zircons have seven age peaks at ~ 240 Ma, ~ 430 Ma, ~ 1390 Ma, ~ 1880 Ma, ~ 2500 Ma, -3200 Ma and 788-999 Ma (a wide peak). Provenance analysis indicates that the source rocks are in the Jiangnan domain, the Northwest Zhejiang Basin and the Wuyishan domain. Combining these with previous results and paleocurrent directions, we infer that the NE-trending Wuyishan and Xuefengshan domains and the nearly E-W-Jiangnan domain and Nanling tectonic belt were orogenic uplifts and watersheds during the Late Triassic to Middle Jurassic. The Early Mesozoic geodynamics in the South China Block was related to the westward subduction of the Paleo-Pacific Plate and the northward continent-continent collision following the closure of the Paleo-Tethys Ocean.

  7. Cenozoic tectonic evolution and petroleum exploration in Perl River Mouth basin, South China Sea

    SciTech Connect

    Chi Yukun; Xu Shice )

    1990-06-01

    The Pearl River Mouth basin is a large Cenozoic continental margin basin that is rich in hydrocarbon potential. Fluvial-lake sequences were deposited before Oligocene, but all were covered by Miocene marine clastic and carbonate rocks. Both paleo-Pearl River delta system and reef/bank carbonate system were widely developed. At the early stage of the evolution, two subsidence belts and one uplift between them distributed in NE regional direction; grabens occurred in the north belt and depressions in the south belt. Tectonic movement was stronger in the east than the west. The main production zones have been drilled both in Miocene sandstone and carbonate rocks. As the exploration activities are developing, the basin will be one of the most significant China offshore oil production areas.

  8. Recognition of relict Mesozoic Dongsha Basin in the northern margin, South China Sea and its implication

    NASA Astrophysics Data System (ADS)

    Yan, Pin; Wang, Yanlin

    2015-04-01

    The Pearl River Mouth Basin (PRMB) is dominated by NE-trending rift architecture produced mainly during Cenozoic Era. It comprises a series of grabens built up with thick Paleogene and thick Neogene sediments, up to 12000 m, and dividing basement highs composing Yanshanian granitic rocks. Though previously considered as one constituent part of PRMB in the southeast, Dongsha Basin displays major differences in sedimentary architecture and tectonic framework. Firstly, Dongsha Basin is characterized by a prominent angular unconformity, interpreted as a spectacular planation or rough erosion surface which separates the sediment column into two distinct parts. It is interpreted with accumulating seismic and drill data that the underlying strata comprise Early Cretaceous terrestrial, Jurassic marine and possibly Triassic sedimentary rocks totaling to 4~9 km thick, whereas the overlying strata are very thin (usually 0.5~1 km in whole) composing mainly Neogene sediments. The major sedimentary hiatus between them corresponds to the Late Cretaceous to mid-Miocene Epoch, well during the rifting to spreading process when the PRMB developed. Secondly, unlike the PRMB, the Dongsha Basin has suffered considerably less extension except its boundary areas, and actually remained as a relatively stable block though Cenozoic Era. Moreover, there are a few compressive open fold structures within the buried Mesozoic strata over the central Dongsha Basin. These folds trend in NNE and are characterized mostly by few minor growing upthrust faults with offsets in the order of few tens to hundreds meter. The upthrust faults dipped mostly southeastward against the northwestward subduction of paleo-Pacific plate as postulated in other previous study. The blind folds featured more like back-thrust growth tectonics, formed a broad NNE-SSW trending belt, obviously oblique to the trend of northern margin of the South China Sea and the PRMB as well. In a few recent models, the most prominent

  9. Cenozoic magmatism in the South China Basin: Decompression melting and implications of an enriched mantle source

    SciTech Connect

    Flower, M.F.J.; Kan Tu; Ming Zhang ); Guanghong Xie )

    1990-06-01

    A widespread eposide of interplate volcanism followed the cessation of seafloor spreading in the South China Basin (SCB), affecting the South China Sea, and fringing areas of southern China and Indochina. Geochemical data for basalts from South China Sea islands and seamounts, Hainan Island, and Taiwan define an enriched (Dupal-like) mantle domain yielding oceanic island basalt (OIB) suites with {Delta}7/4Pb = 2-13, {Delta}8/4Pb = 45-73, {sup 87}Sr/{sup 86}Sr > {approximately}0.70325, Th/Ta > 2, and Th/Ba > 0.02. Opening of the SCB resulted from disaggregation of the South China block in response to the Indo-Eurasian collision, a process involving at least one seafloor spreading episode, terminated by collision of microcontinents with the Philippines and Borneo. The lack of precursive flood basalt suggests that active mantle upwelling was not involved and that melting was a passive effect of lithosphere stretching. However, while mantle decompression at ambient stretching factors ({approximately}1.7-2.5) appears to permit melting on the observed scale, the enriched source may preclude such a simple mantle dynamic. Three alternatives are considered: (1) passive melting of a mature metasomatised boundary layer, (2) active melting of thermally eroded subcontinental lithosphere (deep enrichment) or metasomatised boundary layer (shallow enrichment), and (3) relict diapirs of pre-SCB and/or Java trench subduction slabs (intermediate/deep enrichment). These models are evaluated in terms of chemical and isotopic mass balances associated with the generation and movement of small melt fractions in depleted, nondepleted, and enriched mantle.

  10. Mesozoic tectonically driven climatic partitioning of the south Junggar and north Tarim basins, northwest China

    SciTech Connect

    Hendrix, M.S.; Graham, S.A.; Brassell, S.C. )

    1991-03-01

    Detailed basin analysis of Mesozoic strata exposed in the south Junggar and north Tarim foreland basin Mesozoic depocenters, northwest China, has documented periodic structural reactivation of the intervening Tian Shan during that era. Coarse alluvial pulses, contained in an otherwise relatively fine-grained section of fluvial lacustrine sediments, were shed off both the north and south flanks of the Tian Shan during the Late Triassic, Latest Jurassic, and late Cretaceous. The lofty modern Tian Shan and associated rain shadow cast over the Tarim basin to the south reflect deformation associated with the early Cenozoic Himalayan collision; so too were the two basins climatically partitioned during the Mesozoic in response to relief produced by orogenesis. During prolonged episodes of relative tectonic quiescence, it appears that Tian Shan relief was too low to confine moisture to the windward side of the range. Most notable is the Middle Jurassic section that is dominated in both basins by a relatively fine-grained series of organic-rich, meandering fluvial, and lacustrine sediments. Pyrolytic analyses of organic-rich mudstones associated with these sediments document high H.I. kerogens, suggesting algal-dominated organic matter typical of anoxic lacustrine settings. However, detailed GC-MS biomarker analysis of the alipaphatic fraction also suggests substantial input from higher land plants in addition to algal sources. Not only are n-alkane distributions typically dominated by high molecular weight compounds with an odd-over-even preference typical of higher land plants, but the abundance of specific diterpenoid biomarker compounds strongly suggests the development of widespread coniferous forests on either side of the range during the Middle Jurassic.

  11. Eddy-entrained Pearl River plume into the oligotrophic basin of the South China Sea

    NASA Astrophysics Data System (ADS)

    He, Xianqiang; Xu, Dongfeng; Bai, Yan; Pan, Delu; Chen, Chen-Tung Arthur; Chen, Xiaoyan; Gong, Fang

    2016-08-01

    The South China Sea (SCS) is the world's largest tropical marginal sea with an oligotrophic basin. In June 2015, a rare large phytoplankton bloom, which is ~500 km long, 100 km wide and lasting more than 19 days, was captured in the northern SCS basin by satellite daily chlorophyll images. Water within the bloom area had a feature of low salinity and high temperature measured by an accidental-passing cruise. Meanwhile, satellite sea level anomaly images and drifter trajectory proved there was a cyclonic eddy nearby. No typhoon and heavy rain happened in this period, so we believed the bloom was triggered by the injection of nutrient-rich Pearl River plume driven by eddy. This is the first report on eddy-entrained Pearl River plume into the SCS, which would raise a new view on irregular transportation of nutrient and carbon and its related biogeochemical influence on the oligotrophic ocean.

  12. Distortion and broadening of internal solitary wavefront in the northeastern South China Sea deep basin

    NASA Astrophysics Data System (ADS)

    Xie, Jieshuo; He, Yinghui; Lü, Haibin; Chen, Zhiwu; Xu, Jiexin; Cai, Shuqun

    2016-07-01

    Internal solitary waves (ISWs) with peculiar fronts are frequently observed in the world ocean by satellite images, though with quite few explanations. In this study a distorted and broadening ISW front across the northeastern South China Sea deep basin is presented by using synthetic aperture radar (SAR) image. To illustrate this peculiar front, a nonlinear refraction model is developed to simulate and evaluate the effects of realistic bottom topography, current, and stratification on its transformation. Simulated results in realistic oceanic environments show good agreements with this SAR-observed front. Based on separate and comparative results in different background environments, we demonstrate that the distortion is actually caused by the strong mesoscale currents at periphery of an anticyclonic eddy. Moreover, the broadening is due to the difference in change of wave half width at different rays, which is associated with the different transformation of ISWs across variable bottom topography in the deep basin.

  13. Late Permian to Late Triassic basin evolution of North Vietnam: geodynamic implications for the South China and Indochina blocks

    NASA Astrophysics Data System (ADS)

    Rossignol, Camille; Bourquin, Sylvie; Hallot, Erwan; Poujol, Marc; Roger, Françoise

    2015-04-01

    The core of South East Asia is composed of a mosaic of continental blocks, among which the Indochina and the South China blocks (present day northern Vietnam), amalgamated during the Permian and/or the Triassic. Late Permian to Late Triassic geodynamic evolution of these two blocks remains controversial. The main discussion points concern the existence and the closure of an oceanic domain separating the Indochina and the South China blocks during this period. Especially, the polarity and the timing of the subduction zone that led to the collision between the blocks as well as the present location of the suture delimiting them are a matter of debate. Despite the valuable information they can provide, the sedimentary basins from northern Vietnam have been neglected in the previous studies dealing with the geodynamic evolution of South East Asia. To determine the geodynamic evolution of the area, the basins of Sam Nua and Song Da, presently located in North Vietnam, have been investigated using a combined approach involving sedimentology, geochronology (U-Pb/zircon) and geochemistry (whole-rock major and trace elements composition of both volcanic and volcaniclastic rocks). The palaeoenvironment evolution, the main unconformities, their age and the tectonic affinities of the interbedded volcanic and volcaniclastics series have been characterized for these two basins. Our results demonstrate (i) that the Song Da Basin exhibits a palaeogeographic affinity with the South China block, (ii) the occurrence of extensive calk-alkaline volcanism and associated volcaniclastic deposits in the Sam Nua Basin, related to the existence of an active magmatic arc during the Early and the lower Middle Triassic, (iii) a South dipping (present day coordinate) oceanic lithosphere beneath the Indochina block, deduced from the location of the magmatic arc south of the potential suture zones, (iv) that an angular unconformity postdates the lower Middle Triassic volcaniclastic deposits in the

  14. Tectonic Subsidence Analysis of the Pearl River Mouth Basin, Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Tang, X.; Huang, S. S. X. E. C.; Zhuang, W.; LIU, Z.; Duan, W.; Hu, S.

    2015-12-01

    The Pearl River Mouth Basin (PRMB hereafter) in the northern margin of the South China Sea has attracted great attention not only because of its special tectonic location but also for its abundant hydrocarbon resources. Tectonic evolution controls the petroleum geological condition of hydrocarbon-bearing basins. Efforts have been made to understand the tectonic evolution of this basin. However, many issues about the tectonic features and the evolution process of this basin, such as the age of the breakup unconformities and the anomalously accelerated subsidence during the post-rifting stage, remain controversial. Here we employ tectonic subsidence analysis of sedimentary basins, a technique of removing isostatic loading and compaction effects by back-stripping, to investigate the tectonic controls on the basin formation of the PRMB. We performed the analysis on 4 drill wells and 43 synthetic wells constructed based on recently acquired seismic profiles. The result shows that tectonic subsidence in the eastern sags of the PRMB began to decrease at ~30Ma while in the western sags the onset was ~23.8Ma. This suggests that the break-up time i.e. the end of rifting in the PRMB is earlier in the eastern sags than in the western sags. Abnormally accelerated tectonic subsidence occurred between 17.5-16.4Ma during the post-rifting stage, at an average subsidence rate as high as 301.9m/Ma. This phenomenon discriminates the PRMB from the category of classical Atlantic passive continental marginal basins, of which the tectonic subsidence during the post-rifting stage decays exponentially. The main objective of this paper is to provide insights into the geological and geodynamic evolution of the PRMB. The result bears significance to hydrocarbon exploration in this region.

  15. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H.; Watkins, J.S.

    1996-12-31

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  16. Sequence stratigraphy and hydrocarbon potential of the Phu Khanh Basin offshore central Vietnam, South China Sea

    SciTech Connect

    Lee, G.H. ); Watkins, J.S. )

    1996-01-01

    The Phu Khanh Basin offshore central Vietnam is one of the few untested basins on the Vietnam margin of the South China Sea. Analysis of over 1,600 km of multi-channel seismic reflection data indicates that the Phu Khanh Basin follows a typical rift-margin order: faulted basement, synrift sedimentation, a breakup unconformity, and postrift sedimentation. Postrift sedimentation consists of a transgressive phase characterized by ramp-like depositional geometries followed by a regressive phase characterized by prograding sequences. An early middle Miocene unconformity separates these two phases. During the transgressive phase rising sea level provided favorable conditions for carbonate buildup development. The regressive interval contains a number of third-order depositional sequences composed of seismically resolvable lowstand, highstand, and rarely, transgressive systems tracts. Lacustrine sediments deposited in graben and half-graben lakes during the rifting stage are probably the principal source rocks. Fractured and/or weathered basement, carbonate complexes, basinfloor fans, and shallows water sands may have good reservoir quality. Potential traps include basement hills, carbonate complexes, fault taps, and stratigraphic traps within lowstand systems tracts. Hydrocarbon indicators such as flat spots, bright spots, gas chimneys with gas mounds on the seafloor occur at a number of locations.

  17. Propagated rifting in the Southwest Sub-basin, South China Sea: Insights from analogue modelling

    NASA Astrophysics Data System (ADS)

    Ding, Weiwei; Li, Jiabiao

    2016-10-01

    How the South China Sea rifted has long been a puzzling question that is still debated, particularly with reference to the Southwest Sub-basin (SWSB). Analogue modelling remains one of the most useful tools for testing rift models and processes. Here, we present and discuss a series of analogue modelling experiments designed to investigate the rifting process of the SWSB. Convincing geophysical results were compiled to provide realistic constraints to test the experimental results and interpretations. A heterogeneous lithosphere model with a varied lithospheric structure showed tectono-morphological features similar to the natural case of the SWSB, indicating that the initial thermal condition and rheological stratification of the lithosphere should have a dominant effect on the rifting process of the SWSB. Rigid tectonic blocks existed in the continental margin, such as the Macclesfield Bank and the Reed Bank, and they played important roles in both the shaping of the continent-ocean boundary and the coupling between the crust and mantle. The initial thermal condition and rheological stratification of the lithosphere under the South China Sea controlled the propagated rifting process of the SWSB. Extension was centred on the deep troughs between the rigid blocks, and the break-up occurred in these areas between them. The westward rifting propagation is best explained with a heterogeneous lithosphere model characterized by varied lithospheric structure, and it was responsible for producing the V-shaped configuration of the SWSB.

  18. Structural control on lithofacies in the Zhu 1 depression, Pearl River Mouth Basin, South China Sea

    SciTech Connect

    Carnes, J.B.; Novitsky-Evans, J.C.; Schunk, D.J. )

    1994-07-01

    The structural framework of the Zhu 1 depression, Pearl River Mouth Basin, South China Sea, is expressed in terms of a half-graben rifting model, providing foundation for a predictive model of synrift lacustrine source rock distribution. The Zhu 1 depression includes a northern series of linked half grabens, a southern series of linked half grabens, and a central chain of intrabasinal ridges. The central ridge chain includes both horst blocks (termed high-relief accommodation zones or isolation ridges in the model) and antiforms (termed low-relief accommodation zones or interference ridges in the model). Major fluvial input was from the north, funneled into Zhu 1 through gaps (termed platforms in the model) created by offsets in the border faults of the northern series of half grabens. The central ridge chain is interpreted to have controlled sediment distribution within Zhu 1, periodically confining coarse terrigenous clastics within northern half grabens while lacustrine shales accumulated in southern half grabens.

  19. Development of a model-based flood emergency management system in Yujiang River Basin, South China

    NASA Astrophysics Data System (ADS)

    Zeng, Yong; Cai, Yanpeng; Jia, Peng; Mao, Jiansu

    2014-06-01

    Flooding is the most frequent disaster in China. It affects people's lives and properties, causing considerable economic loss. Flood forecast and operation of reservoirs are important in flood emergency management. Although great progress has been achieved in flood forecast and reservoir operation through using computer, network technology, and geographic information system technology in China, the prediction accuracy of models are not satisfactory due to the unavailability of real-time monitoring data. Also, real-time flood control scenario analysis is not effective in many regions and can seldom provide online decision support function. In this research, a decision support system for real-time flood forecasting in Yujiang River Basin, South China (DSS-YRB) is introduced in this paper. This system is based on hydrological and hydraulic mathematical models. The conceptual framework and detailed components of the proposed DSS-YRB is illustrated, which employs real-time rainfall data conversion, model-driven hydrologic forecasting, model calibration, data assimilation methods, and reservoir operational scenario analysis. Multi-tiered architecture offers great flexibility, portability, reusability, and reliability. The applied case study results show the development and application of a decision support system for real-time flood forecasting and operation is beneficial for flood control.

  20. Deltaic Depositional Systems, Evolution Characteristics, and Petroleum Potential, Palaeogene Sub-Basin, South China Sea

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Wang, Hua; Zhang, Guotao

    2015-04-01

    Deltaic depositional systems are detailed characterized by morphology and facies in a Palaeogene continental sub-basin of Beibuwan Basin, South China Sea. Based on examination of 435 m of conventional cores from 30 wells, three major types of deltaic facies have been recognized: delta, beach and shoreface. Morphology and facies asymmetry between the down-drift and the up-drift sides present a typical asymmetric delta system:1) the down-rift, sourced primarily by the feeding river, are influenced by mixed river and wave processes. Deposits on this side are muddy and consist of barrier, bar, bay-fill, and bayhead delta facies with variable bioturbation intensity; 2)the up-rift, in contrast, is sourced by a second sediment source and typically consists of laterally continuous sandy beach and shoreface facies. Finally, two fundamentally different depositional models are established and reflect a different style of sequence stratigraphic patterns: 1) Multiple-stage faults slopes developed in the down-rift side feed fine grained sediment into two stages channelized front deltaic system; 2) Flexure slope break of the up-rift side, combining with deeper gradual slopes, conversely, feed coarser grained sediment from larger drainages into sandy beach and shoreface systems. Such a distinction has well explained the differentiation of the proven hydrocarbon reserves because the up-rift consists of well-sorted, mature, and laterally continuous homogeneous beach-shoreface reservoirs, whereas the down-rift, in contrast, is muddier and consists of less continuous, less mature, heterolithic reservoirs. The Delta asymmetry concepts and models don't only challenge the traditional definition of deltas in Fushan sub-basin, but also provides strong theoretical support for the future exploration. This process-based model may be applicable to many deep-water settings and provides a framework within which to interpret the stratigraphic and spatial distribution of these complex deposits.

  1. Oxygenation of a Cryogenian ocean (Nanhua Basin, South China) revealed by pyrite Fe isotope compositions

    NASA Astrophysics Data System (ADS)

    Zhang, Feifei; Zhu, Xiangkun; Yan, Bin; Kendall, Brian; Peng, Xi; Li, Jin; Algeo, Thomas J.; Romaniello, Stephen

    2015-11-01

    The nature of ocean redox chemistry between the Cryogenian Sturtian and Marinoan glaciations (ca. 663-654 Ma) is important for understanding the relationship between environmental conditions and the subsequent emergence and expansion of early animals. The Cryogenian-to-Ediacaran stratigraphic succession of the Nanhua Basin in South China provides a nearly complete sedimentary record of the Cryogenian, including a continuous record of interglacial sedimentation. Here, we present a high-resolution pyrite Fe isotope record for a ∼120-m-long drill-core (ZK105) through Sturtian glacial diamictites and the overlying interglacial sediments in the Nanhua Basin to explore changes in marine chemistry during the late Cryogenian. Our pyrite Fe isotope profile exhibits significant stratigraphic variation: Interval I, comprising middle to upper Tiesi'ao diamictites (correlative with the Sturtian glaciation), is characterized by light, modern seawater-like Fe isotope compositions; Interval II, comprising uppermost Tiesi'ao diamictites and the basal organic-rich Datangpo Formation, is characterized by an abrupt shift to heavier Fe isotope compositions; and Interval III, comprising organic-poor grey shales in the middle Datangpo Formation, is characterized by the return of lighter, seawater-like Fe isotope compositions. We infer that Interval I pyrite was deposited in a predominantly anoxic glacial Nanhua Basin through reaction of dissolved Fe2+ and H2S mediated by microbial sulfate reduction (MSR). The shift to heavier pyrite Fe isotope values in Interval II is interpreted as partial oxidation of ferrous iron to ferric iron and subsequent near-quantitative reduction and transformation of Fe-oxyhydroxides to pyrite through coupling with oxidation of organic matter in the local diagenetic environment. In Interval III, near-quantitative oxidation of ferrous iron to Fe-oxyhydroxides followed by near-quantitative reduction and conversion to pyrite in the local diagenetic environment

  2. Mixed volcanogenic-lithogenic sources for Permian bauxite deposits in southwestern Youjiang Basin, South China, and their metallogenic significance

    NASA Astrophysics Data System (ADS)

    Yu, Wenchao; Algeo, Thomas J.; Du, Yuansheng; Zhang, Qilian; Liang, Yuping

    2016-07-01

    Bauxite deposits at the base of the Upper Permian Heshan Formation in the Youjiang Basin, South China, contain zircons with dominant age peaks at 263-262 Ma. During the Middle to Late Permian, the Youjiang Basin consisted of a number of isolated and attached carbonate platforms separated by inter-platform troughs. The bauxite deposits are limited to the isolated carbonate platform facies and are not present on attached carbonate platforms and inter-platform troughs. Discriminant plots based on the trace element composition of the zircons indicate a combination of within-plate/anorogenic and arc-related/orogenic sources. Geochemical and isotopic data suggest that the metallogenic materials of the bauxite deposit came from felsic volcanic rocks of the Emeishan Large Igneous Provence (ELIP) in South China and from the Truong Son volcanic arc located between the South China and Indochina cratons. The northwestern and southeastern parts of the Youjiang Basin received larger amounts of ELIP detritus and volcanic arc detritus, respectively. Coarser siliciclastic material in proximal attached carbonate platform and inter-platform trough settings was delivered by rivers, but finer siliciclastics that accumulated on distally located carbonate platforms in isolated deep-water areas was probably transported by wind.

  3. Salt-related tectonics in the eastern Sichuan Basin, South China

    NASA Astrophysics Data System (ADS)

    Gu, Zhidong; Yin, Jifeng; Yuan, Miao; Zhai, Xiufen

    2015-04-01

    Sichuan Basin is located in the northwest of Upper Yangtze platform of South China, and East Sichuan is situated between Huaying Mountain fault and Qiyue Mountain fault. The surface Jura type folds are very famous with barrier parallel folds, but the cause of folds formation have not been completely understood. Stratigraphic units are composed of thick competent flexural layers separately by relatively thin incompetent ductile layers that can act as detachments.Multiple detachment layers are developed in the eastern Sichuan and result in distinct structural domains. In addition to the basal, Triassic and Silurian system detachment layers, we recognize a regionally extensive salt layer in the Middle and Lower Cambrian. The recognition of salt layer is by the synthetical studies of outcrop, drilling well, and chaotic seismic reflection configuration. The Middle and Lower Cambrian salt forms a tectonic domain boundary that can be observed by seismic reflection profile in subsurface. The stratigraphic intervals above and below the salt develop characteristic salt-related tectonics. And the folds formation is by flow in and flow out of salt movement of the Middle and Lower Cambrian and flexural slip and grouding of the overlying units. Above the salt, the thrust fault-related folds were generated by the contractional action from southeast to northwest, including the fault-bend fold, fault-propagation fold, and thrust wedge fold, and so on. Below the salt, the broad anticlines were formed due to the basal detachment. Hydrocarbon traps are formed above and below the salt, and they are potential gas exploration domains in the eastern Sichuan Basin.

  4. A geochemical investigation of crude oils from Eastern Pearl River Mouth Basin, South China Sea

    NASA Astrophysics Data System (ADS)

    Jiamo, Fu; Cunmin, Pei; Guoying, Sheng; Dehan, Liu; Sizhong, Chen

    A thorough petroleum exploration of the Pearl River Mouth Basin (PRMB), South China Sea, began in 1983. At present, several oilfields have been found in the PRMB, mainly distributed in Dongsha Massif, Huizhou and Xijiang Depressions as well as Huilu Lowhigh, and one of them has been developed recently. The crude oils found in the basin can be classified into two types. One is normal waxy type, and the other is cyclic type, which may be caused by minor biodegration and is restricted to the Liuhua District of Dongsha Massif. However, on the basis of geochemical characteristics, all the crude oils are thermally mature, indicating that they are derived from source rocks which have entered the main oil generation period but their maturity is not high enough to reach the overmature stage. Moreover, in the biomarker distribution, the oils also share many similarities. Almost all the oils contain abundant C 30 4-methylsteranes with 24-ethyl side chain, ubiquitous oleanane and lower concentration of gammacerane, and possess high ratios of Ni/V, pristane to phytane and C 30 hopane over total C 29 steranes as well as high paraffin wax and low sulphur content, indicating that they originated from terrestrial organic matter deposited in lacustrine and marsh coal-forming environments. However, some characteristics resemble Brazilian offshore oils of salinewater lacustrine environment. The oils found in the PRMB can also be classified into three main genetic types based on the relative values of pristane over phytane ratio, C 29 sterane preference and the composition of the carbon isotope. Type I oils occurred in the Huizhou and the Xijiang Depressions and their adjacent Dongsha Massif. It has higher ratios of pristane to phytane (1.80-5.54 and 3.21 on the average scale) and heavier carbon isotopic composition, indicating that their source rocks contain much more abundant terrestrial higher plant input. Type II, encountered in Huilu Lowhigh and its bounding area of Dongsha Massif

  5. Characteristics of hydrothermal sedimentation process in the Yanchang Formation, south Ordos Basin, China: Evidence from element geochemistry

    NASA Astrophysics Data System (ADS)

    He, Cong; Ji, Liming; Wu, Yuandong; Su, Ao; Zhang, Mingzhen

    2016-11-01

    Hydrothermal sedimentation occurred in the Triassic Yanchang Formation, Ordos Basin, China. However, their macroscopic features at the scale of the stratum and hydrothermal sources still lack correlational research. This paper performed element geochemical study on a large number of core samples collected from the Yanchang Formation of a new drilling well located in the south Ordos Basin. The SiO2/(K2O + Na2O) vs. MnO/TiO2 crossplot and Fe vs. Mn vs. (Cu + Co + Ni) × 10 ternary diagram demonstrate that the Yanchang stratum in the study area has, in general, hydrothermal components. The Al/(Al + Fe + Mn) and (Fe + Mn)/Ti ratios of the core samples range from 0.34 to 0.84 and 4.81 to 50.54, averaging 0.66 and 10.67, respectively, indicating that the stratum is a set of atypical hydrothermal sedimentation with much terrigenous input. Data analysis shows that the hydrothermal source in the study area was from the deep North Qinling Orogen around the south margin of the basin, where some active tectonic and volcanic activities took place, rather than from the relatively stable internal basin. Early Indosinian movement and volcanic activities activated basement faults around the southern margin of the basin, providing vents for the deep hydrothermal fluid upwelling. The hydrothermal indicators suggest that the study area experienced 4 episodes of relatively stronger hydrothermal activity, namely during the Chang 10, Chang 9-1, Chang 7-3 and Chang 6-2 periods. We also propose a new hydrothermal sedimentation model of hydrothermal fluids overflowing from basin margin faults, for the Yanchang Formation, which is reported here for the first time.

  6. Palaeoenvironment and its control on the formation of Miocene marine source rocks in the Qiongdongnan Basin, northern South China Sea.

    PubMed

    Li, Wenhao; Zhang, Zhihuan; Wang, Weiming; Lu, Shuangfang; Li, Youchuan; Fu, Ning

    2014-01-01

    The main factors of the developmental environment of marine source rocks in continental margin basins have their specificality. This realization, in return, has led to the recognition that the developmental environment and pattern of marine source rocks, especially for the source rocks in continental margin basins, are still controversial or poorly understood. Through the analysis of the trace elements and maceral data, the developmental environment of Miocene marine source rocks in the Qiongdongnan Basin is reconstructed, and the developmental patterns of the Miocene marine source rocks are established. This paper attempts to reveal the hydrocarbon potential of the Miocene marine source rocks in different environment and speculate the quality of source rocks in bathyal region of the continental slope without exploratory well. Our results highlight the palaeoenvironment and its control on the formation of Miocene marine source rocks in the Qiongdongnan Basin of the northern South China Sea and speculate the hydrocarbon potential of the source rocks in the bathyal region. This study provides a window for better understanding the main factors influencing the marine source rocks in the continental margin basins, including productivity, preservation conditions, and the input of terrestrial organic matter.

  7. Palaeoenvironment and Its Control on the Formation of Miocene Marine Source Rocks in the Qiongdongnan Basin, Northern South China Sea

    PubMed Central

    Li, Wenhao; Zhang, Zhihuan; Wang, Weiming; Lu, Shuangfang; Li, Youchuan; Fu, Ning

    2014-01-01

    The main factors of the developmental environment of marine source rocks in continental margin basins have their specificality. This realization, in return, has led to the recognition that the developmental environment and pattern of marine source rocks, especially for the source rocks in continental margin basins, are still controversial or poorly understood. Through the analysis of the trace elements and maceral data, the developmental environment of Miocene marine source rocks in the Qiongdongnan Basin is reconstructed, and the developmental patterns of the Miocene marine source rocks are established. This paper attempts to reveal the hydrocarbon potential of the Miocene marine source rocks in different environment and speculate the quality of source rocks in bathyal region of the continental slope without exploratory well. Our results highlight the palaeoenvironment and its control on the formation of Miocene marine source rocks in the Qiongdongnan Basin of the northern South China Sea and speculate the hydrocarbon potential of the source rocks in the bathyal region. This study provides a window for better understanding the main factors influencing the marine source rocks in the continental margin basins, including productivity, preservation conditions, and the input of terrestrial organic matter. PMID:25401132

  8. The geochemistry characteristic and dating of cold seepage carbonates of the Pearl River Mouth Basin, eastern of South China Sea

    NASA Astrophysics Data System (ADS)

    Fang, Yunxin; Fu, Shaoying

    2015-04-01

    Cold seepage carbonates are usually formed by the interaction of methane oxidizing archaea, sulfate reducing bacteria and cold seepage which contain abundant venting hydrocarbon gases. The presence of cold seepage carbonates on the seabed is one of the evidences that the area exist venting hydrocarbon gases, which are usually result by the dissociation of gas hydrate. The cold seepage property and fluid flow rate can influence the oxidation-deoxidation environment of the bottom water and sediment. Many previous studies focused on the mineral composition, microstructure, elemental composition, isotope composition of the cold seepage carbonates and isotopic dating for the cold seepage carbonates. The isotopic dating for the cold seepage carbonates can provide the information of the gas hydrate formation and dissociation in some area of the South China Sea. High precision TIMS-U dating and 14C dating are used as routine method for the dating of the Quaternary carbonates and fossils. The cold seepage carbonates in the study include the samples collected by ROV on the seabed and the drilling for gas hydrate in the Pearl River Mouth Basin, eastern of the South China Sea. The authigenic carbonate occurred in different depth in the A, B and C drilling site. They may be represent different events of gas hydrate formation and dissociation in the Quaternary. The dating study for all the cold seepage carbonates can provide the relative accurate eras of the gas hydrate dissociation events in certain area of the South China Sea.

  9. Sediment supply, tectonic subsidence, and basin-filling patterns across the southwestern South China Sea during Pliocene to recent time

    NASA Astrophysics Data System (ADS)

    Murray, Mychal R.; Dorobek, Steven L.

    Sediment flux to southwestern parts of the South China Sea (SCS) during late Cenozoic time reflects contributions from eastern Tibet, western Borneo, and smaller drainages of central Indochina, Vietnam, the Malay Peninsula, and western Indonesia, although little work has been done to evaluate the significance of each source. Regional seismic-reflection data and well logs from the southwestern SCS were used in this study to evaluate sediment flux and dispersal across the area. Regional seismic-stratigraphic patterns across the southwestern SCS, however, show that Pliocene to Recent sediment accumulation within individual basins was also strongly influenced by long-term changes in tectonic subsidence. More updip basins (e.g., Malay, Cuu Long, and West Natuna basins) became filled after Miocene inversion and an abrupt slowing of tectonic subsidence. Once they became filled, sediment could bypass the updip basins. In contrast, the eastern part of the Nam Con Son Basin (NCSB) has experienced much greater subsidence since early Miocene time and continues to receive sediment that bypasses the updip basins. The paleo-Mekong River and a second depositional system with probable headwaters on the Malay Peninsula began supplying large volumes of sediment to the NCSB during late Miocene and Pliocene time, respectively. Filling of updip basins allowed Pliocene to Recent fluvial and shelf facies to shift progressively eastward across the southwestern SCS. This study shows that Pliocene to Recent sediment dispersal and paleogeographic evolution of the southwestern SCS are as strongly influenced by subsidence patterns as they are by sediment supply from continental drainage systems.

  10. Mesozoic hydrocarbon source rock studies of north Tarim, south Junggar, and Turpan basins, Xinjiang Uygur autonomous region, northwestern China

    SciTech Connect

    Hendrix, M.S.; Xiao, Z.; Liang, Y.; Graham, S.A.; Carroll, A.R.; Chu, J.; McKnight, C.

    1989-03-01

    Ongoing outcrop and accompanying pyrolysis studies of Mesozoic strata of the north Tarim, south Junggar, and Turpan retroarc foreland basins, northwestern China, have demonstrated the existence of potential oil-prone and gas-prone petroleum source rocks. Lithologies include Jurassic coals from all three basins and Triassic coals from Tarim. Jurassic coals collected from the Mesozoic depocenters of the Junggar and Tarim basins are oil prone, yielding S/sub 2//S/sub 2+3/ values that range from 0.80 to 0.99 and average 0.96, hydrogen index (HI) values that range from 117.9 to 213.4 and average 150.8, and oxygen index (OI) values that range from 1.1 to 31.6 and average 7.67. In contrast, Triassic coals of Tarim and Jurassic coals of Turpan contain more conventional type III gas-prone kerogens and yield S/sub 2//S/sub 2+3/ values ranging from 0.04 to 0.52 and averaging 0.22, HI values ranging from 3.2 to 130.2 with a mean of 33.6, and OI values ranging from 30.9 to 223.7 and averaging 115.9. Coals of all three basins are slightly immature to mature with respect to oil generation, as indicated by T/sub max/ values ranging from 425/degrees/ to 449/degrees/C (average = 343/degrees/C) and vitrinite reflectance values ranging from 0.51 to 0.64 (average = 0.57). Thus, given the widespread abundance and significant thicknesses of Mesozoic and especially Jurassic coals in all three basins, it is very likely that Mesozoic contributions to Xinjiang's oil and gas reserves are significant. This is particularly important in the north Tarim basin, where recent Chinese oil and gas discoveries have been made and the existence of significant pre-Mesozoic source beds remains unproven.

  11. The geology of Northern Sabah, Malaysia: Its relationship to the opening of the South China Sea Basin

    NASA Astrophysics Data System (ADS)

    Tongkul, F.

    1994-07-01

    The northern part of Sabah, consisting of sedimentary and igneous rocks of Early Cretaceous to Pliocene age, has experienced three major episodes of deformation associated with NW-SE and N-S oriented compressions. The earliest episode deformed and uplifted an oceanic basement (Chert-Spilite Formation) to form an elongate basin, trending approximately NE-SW, during the Late Cretaceous to Early Eocene. This elongate basin became the site for the deposition of middle Eocene to Early Miocene quartzose sediments of the Crocker and Kudat formations, sourced from continental basement towards the southwest and north, respectively. These sediments were subsequently deformed by a second episode of deformation associated with NW-SE and N-S oriented compressions, during the latter part of the late Oligocene and the early Middle Miocene, to form a series of imbricate thrust slices. The N-S trending compressive direction controlled the development of approximately E-W trending basins during the deposition of the Upper Miocene sediments of the South Banggi and Bongaya formations. The continuation of N-S compression, which represents the third episode of deformation, gently deformed these sediments. The three episodes of deformation were related to the differential southward movements of continental blocks separated from the southern margin of China during the intermittent opening of the South China Sea subbasins. The first episode was related to the opening of the Southwest Subbasin, while the second episode was related to both the opening of the Southwest and East subbasins. The third episode was related to continued opening in the East Subbasins.

  12. Winged Fruits of Deviacer in the Oligocene from the Ningming Basin in Guangxi, South China

    PubMed Central

    Chen, Yunfa; Manchester, Steven R.

    2015-01-01

    Deviacer guangxiensis Chen & Manchester sp. nov. is described based on asymmetric samaras from the Oligocene Ningming Formation in Guangxi, South China, representing the first documentation of Deviacer fossils in Asia. The Oligocene species, with relatively large fruits, represents the youngest record of the genus so far known; all other records are from the Paleocene and Eocene, or late Eocene—early Oligocene in western North America and Europe. It indicates that the extinct genus, Deviacer, was widely distributed in the northern hemisphere during the Paleogene. PMID:26624897

  13. Winged Fruits of Deviacer in the Oligocene from the Ningming Basin in Guangxi, South China.

    PubMed

    Chen, Yunfa; Manchester, Steven R

    2015-01-01

    Deviacer guangxiensis Chen & Manchester sp. nov. is described based on asymmetric samaras from the Oligocene Ningming Formation in Guangxi, South China, representing the first documentation of Deviacer fossils in Asia. The Oligocene species, with relatively large fruits, represents the youngest record of the genus so far known; all other records are from the Paleocene and Eocene, or late Eocene-early Oligocene in western North America and Europe. It indicates that the extinct genus, Deviacer, was widely distributed in the northern hemisphere during the Paleogene. PMID:26624897

  14. Origin of andesitic rocks: Geochemical constraints from Mesozoic volcanics in the Luzong basin, South China

    NASA Astrophysics Data System (ADS)

    Chen, Long; Zhao, Zi-Fu; Zheng, Yong-Fei

    2014-03-01

    A combined study of whole-rock major-trace elements and Sr-Nd-Pb-Hf isotopes as well as zircon U-Pb ages and Hf-O isotopes was carried out for Mesozoic andesitic-basaltic volcanics from the Luzong basin in the Middle-Lower Yangtze River Belt, South China. The results provide insights into the origin of mantle sources above fossil Andes-type oceanic subduction zone and thus into the petrogenesis of andesitic rocks on fossil and modern continental margins. These volcanics are primarily composed of basaltic trachyandesite and trachyandesite, with small amounts of trachybasalt and trachyte. They exhibit variable contents of SiO2 (48.66-63.43 wt.%), MgO (0.39-4.85 wt.%), Na2O (1.22-6.07 wt.%) and K2O (2.53-10.10 wt.%), with highly variable K2O/Na2O ratios from 0.45 to 7.39. They are characterized by arc-like trace element distribution patterns, with significant enrichment of LILE, Pb and LREE but depletion of HFSE. They exhibit relatively enriched Sr-Nd-Pb-Hf isotope compositions, with initial 87Sr/86Sr ratios of 0.7050 to 0.7066, negative ɛNd(t) values of - 8.0 to - 3.1, negative ɛHf(t) values of - 11.1 to - 1.1, and elevated 207Pb/204Pb and 208Pb/204Pb ratios at given 206Pb/204Pb ratios. Zircon U-Pb dating yields consistent ages of 127 ± 2 to 137 ± 1 Ma for magma emplacement through volcanic eruption. The zircon exhibits slightly high δ18O values of 5.3 to 7.6‰ and variable ɛHf(t) values of - 13.1 to 2.6. An integrated interpretation of all these geochemical data leads to the conclusion that the Luzong andesitic-basaltic volcanics were primarily derived from partial melting of fertile and enriched, mafic-ultramafic mantle sources that are similar to those of continental arc andesites. Such mantle sources are hypothesized to form by reaction of the mantle wedge peridotite not only with hydrous felsic melts derived from partial melting of seafloor sediment but also with aqueous fluid derived from metamorphic dehydration of altered oceanic basalt during

  15. Seismic Reflection Moho Structure of Southwest Sub-basin of South China Sea and Implications for Continental Break-up and Seafloor Spreading Mechanisms

    NASA Astrophysics Data System (ADS)

    Zhang, Jinchang; Yan, Pin

    2016-04-01

    Across-basin Moho structure of South China Sea is important for understanding crustal evolution mechanisms of both continental break-up and seafloor spreading processes. Among all the basins in South China Sea, southwest sub-basin opened up the latest and has the closest continental margins, making it the best to study the across-basin structure. Multichannel seismic (MCS) reflection data of NH973-1 line that crosses southwest sub-basin in NW-SE direction were reprocessed in order to image Moho structure. In MCS data Moho reflectors are observed in places, which were not revealed in prior researches. The Moho generally shows symmetric structure on the both sides of the central rift valley. Beneath the oceanic crust in the middle of the basin, the Moho is ~2 seconds depth in two-way travel time (TWTT), which corresponds to ~7 km depth, showing normal oceanic crustal accretion during the seafloor spreading process. When getting close to continent-ocean boundary (COB), the Moho becomes shallow to <1 second depth in TWTT (~3.5 km), implying strongly crustal thinning. At south COB, the Moho depth almost reaches zero, which implies nearly no crust exists and probably the upper mantle could be exhumed. In addition, two low-angle, deep-penetrating normal faults are observed at south COB. The faults cut across the Moho into the upper mantle, which may have been caused by lithospheric hyper-stretching at COB during the continental break-up process.

  16. Diversity and distribution of diazotrophic communities in the South China Sea deep basin with mesoscale cyclonic eddy perturbations.

    PubMed

    Zhang, Yao; Zhao, Zihao; Sun, Jun; Jiao, Nianzhi

    2011-12-01

    The South China Sea (SCS) is an oligotrophic subtropical marginal ocean with a deep basin and a permanently stratified central gyre. Upwelling and nitrogen fixation provide new nitrogen for primary production in the SCS. This study was aimed at an investigation of phylogenetic diversity and quantification of the diazotroph community in the SCS deep basin, which is characterized by frequent mesoscale eddies. The diazotroph community had a relatively low diversity but a distinct spatial heterogeneity of diversity in the SCS deep basin. The potential for nitrogen fixation consistently occurred during cyclonic eddies, although upwelling of nutrient-replete deep water might have alleviated nitrogen limitation in the SCS. However, diazotrophic proteobacteria were dominant, but neither Trichodesmium nor heterocystous cyanobacterial diatom symbionts. Quantitative PCR analysis using probe-primer sets developed in this study revealed that the nif H gene of the two dominant alpha- and gammaproteobacterial groups was at the highest abundance (up to 10(4) to 10(5)  copies L(-1) ). Trichodesmium thiebautii was detected with an average density of 10(2)  trichomes L(-1) in the euphotic waters, while Richelia intracellularis was observed sporadically under the microscope. The unicellular cyanobacterial groups A and B were not detected in our libraries. Our results suggested that diazotrophic proteobacteria were significant components potentially contributing to nitrogen fixation in this oligotrophic marginal ocean ecosystem.

  17. The structure and sedimentary sequence of intracratonic rift from Late Sinian to Early Cambrian in the Sichuan Basin, South China

    NASA Astrophysics Data System (ADS)

    Gu, Zhidong; Zhang, Baomin; Lu, Weihu; Zhai, Xiufen; Jiang, Hua

    2016-04-01

    Sichuan Basin is located in the northwest of Upper Yangtze craton of South China, and there is developed an intracratonic rift from Late Sinian to Early Cambrian in the middle of Sichuan Basin, and the paper systematically discusses the structure and sedimentary sequence of the intracratonic rift based on the fields, drilling and seismic data, and so on. Detailed structural interpretation of 2D and 3D seismic profiles displays the development of two stages of intracratonic rift due to regional extension with the depth of 2000m, and plane distribution of intracratonic rift presents the V-pattern from the northwest to the southeast in the middle of Sichuan Basin with the width from 100km to 20km. The drilling data from the intracratonic rift shows the obvious thinning of Upper Sinian and thickening of Lower Cambrian. And field outcrops situated in the intracratonic rift reveal that the Upper Sinian is mainly composed of siliceous rock, shale and carbonate, with the thickness of less than 100m, but the thickness of Upper Sinian on the platform reaches 1000m by contrast; They also reveals that Lower Cambrian is mainly composed of shale, mudstone, and siltstone with the development of gravity current, and the thickness of Lower Cambrian reaches 2000m. The formation of intracratonic rift may be initiated by pre-existing basement weakness zone and deep mantle dynamics.

  18. Sedimentary record and climatic implications of recurrent deformation in the Tian Shan: Evidence from Mesozoic strata of the north Tarim, south Junggar, and Turpan basins, northwest China

    SciTech Connect

    Hendrix, M.S.; Graham, S.A.; Sobel, E.R.

    1992-01-01

    Detailed stratigraphic, sedimentologic, paleocurrent, and subsidence analyses were conducted on Mesozoic nonmarine sedimentary sections of the south Junggar, north Tarim, and Turpan basins, Xinjang Uygur Autonomous Region, northwest China. These three basins have been foreland basins throughout the Mesozoic and Cenozoic eras, as demonstrated by asymmetrically distributed basinwide sediment accumulations, foreland-style subsidence profiles, and a variety of outcrop and subsurface facies data. Mesozoic paleocurrent indicators measured in the south Junggar and north Tarim basins, as well as Mesozoic sandstone compositions from both basins, indicate that the intervening Tian Shan has existed as a positive physiographic feature partitioning the two basins throughout Mesozoic and Cenozoic time. Paleocurrent, facies, and subsurface isopach data suggest that the Turpan basin was established as a discrete feature by the Early Jurassic period. The timing and style of depositional systems within the north Tarim Mesozoic depocenter, the south Junggar Mesozoic depocenter, and the central Turpan basin are remarkably similar. Upper Triassic strata of each basin consist of alluvial conglomerate and associated braided-fluvial sandstone and siltstone which fine upward into lower through Middle Jurassic, locally organic-rich, meandering-fluvial, and lacustrine strata. Upper Jurassic braided-fluvial red beds in each basin are overlain by a distinct pulse of uppermost Jurassic alluvial conglomerate. Lower Cretaceous exposures consist of fine-grained red beds in north Tarim and Turpan and interbedded red and gray shale with local silty carbonates in south Junggar. Upper Cretaceous strata of the north Tarim and south Junggar basins are composed of alluvial conglomerate with associated braided-fluvial sandstone and siltstone. 94 refs., 17 figs.

  19. New insight on the opening of the South China Sea basin

    NASA Astrophysics Data System (ADS)

    Hsu, Shu-Kun; Armada, Leo; Doo, Wen-Bin; Yeh, Yi-Ching

    2016-04-01

    The tectonic evolution of the South China Sea (SCS) plays an important role on the geodynamics of Southeast Asia. Recent results from the International Ocean Discovery Program (IODP) Expedition 349 confirmed that the SCS seafloor spreading stopped in the middle Miocene. However, the definite mechanism for the SCS opening is still enigmatic. Using multi-beam bathymetric data, seismic reflection profiles and geomagnetic modeling, we have analyzed the seafloor-spreading pattern and geomagnetic stripes of the SCS. Our results show that an excessive magma supply affecting the SCS occurred at the Early Miocene Climatic Optimum (EMCO). Consequently, four major tectonic events ensued. Firstly, the East Subbasin of the SCS dramatically changed its seafloor spreading direction from north-south to northwest-southeast. Secondly, a northeastward propagating rift occurred in the East Subbasin but stopped in the middle Miocene, just before the cessation of the SCS seafloor spreading. Thirdly, the opening of the SCS extended southwestward and created the Southwest Subbasin. Fourthly, the initiation of the southeastward subduction of the SCS lithosphere occurred and the Manila Trench was formed.

  20. Identifying potential gas accumulation sites from Oligocene overpressure data in the Qiongdongnan basin, offshore South China

    SciTech Connect

    Liu Funing )

    1993-05-01

    Overpressure in Oligocene formations in southern Qiongdongnan basin, offshore China, can be determined either by actual measurements in wells or by calculations using data derived from well logs and seismic surveys. The overpressure is mainly the result of undercompaction of Oligocene rocks during rapid loading by Pliocene and Quaternary sedimentation and of the subsequent thermal expansion of fluids in the Oligocene strata. Every formation possesses its own normal compaction trend (plot of shale-interval acoustic transit times vs. depth). The actual fluid pressures and potential pressures can be computed by the equilibrium-depth method. This method must be corrected for the thermal expansion of fluid. The pressure corrections are based on shale-interval transit times from well logs, interval velocities interpreted from vertical seismic profile (VSP) surveys, and stacking velocity from sonic log data of nearby wells. Gas generated from source rocks is assumed to have moved vertically from strata of higher hydraulic pressure potential to those of lower potentials and to have moved laterally and accumulated within areas where the contour closures of a gas equipotential hydraulic-pressure surface (U curves) have lower values. In the study area, the vicinity of the Yacheng gas field, the potential maps (U, gas, and V, water, maps) and hydraulic head profiles can be plotted from values derived either from actual pressure measurements or from calculations. These maps and profiles show prospective areas of gas accumulation. 5 refs., 10 figs., 1 tab.

  1. Structural characteristic and origin of intra-continental fold belt in the eastern Sichuan basin, South China Block

    NASA Astrophysics Data System (ADS)

    Li, Chuanxin; He, Dengfa; Sun, Yanpeng; He, Jinyou; Jiang, Zaixing

    2015-11-01

    The fold-and-thrust belt in the eastern Sichuan basin is represented by a series of subparallel chevron anticlines. Under the orogenic tectonic setting within the South China Block in Meso-Cenozoic period and the influence of the multi-layer detachment fault, the deformation of the thrust belt exhibits remarkably layered and large-scale intracontinental thrusting structural characteristics. In this paper, we focus on the structural geometry and deformational mechanisms using the latest two-dimensional (2D) and three-dimensional (3D) seismic reflection data in combination with well and outcrop data. The multi-layer detachment faults, especially the upper gypsum-bearing detachment in the Middle Triassic Jialingjiang Formation and lower detachment with gypsum or shale in the Lower-Middle Cambrian system, directly control the deformational styles of the study area. Interpretation of seismic sections indicates that the fold-and-thrust belt has various deformational styles during folding, including fault-propagation fold, fault-bend fold, and detachment fold with box-fold or pop-up structural geometry. Regional location and structural boundaries play significant roles in controlling the deformational styles, and distinct differences exist among the different anticlines. The Huayingshan anticline located at the front of the thrust belt shows intense structural deformation with northwestward thrusting direction and a relatively weak opposite southeastward thrusting. In addition, the anticlines exhibit structural differences along strike and the fold-and-thrust belt in the northern segment is influenced by the North China Block.

  2. Remagnetization of lower Silurian black shale and insights into shale gas in the Sichuan Basin, south China

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Jia, Dong; Yin, Hongwei; Liu, Mancang; Xie, Wuren; Wei, Guoqi; Li, Yongxiang

    2016-02-01

    The organic-rich lower Silurian shale of the Longmaxi Formation in the Sichuan Basin is the most important target for shale-gas exploration in China. Most Paleozoic rocks of the Sichuan Basin have experienced extraordinarily pervasive remagnetizations. To test a hypothesized connection between hydrocarbon generation and remagnetization and contribute to shale-gas exploration in the region, we undertook an integrated magnetic, geochemical, and petrographic study of 160 specimens from the shale. The results suggest that the shale contains a reliable remanent magnetization (Dec = 41.4°, Inc = 40.8°, and α95 = 6.8°). The magnetization predates tilting, and the paleopole plots close to the Late Triassic segment of the south China apparent polar wander path. The rock magnetic data and scanning electron microscope (SEM) observations confirm that framboidal magnetites carry the bulk of the magnetization, which suggest a Late Triassic chemical remanent magnetization in the shale. 87Sr/86Sr and magnetic analyses indicate that the amount of magnetite was unaffected by fluid alterations around the veins but is strongly covariant with the amount of total organic matter. Moreover, SEM observations reveal possible evidence of the replacement of pyrite framboids by magnetite, probably in the presence of organic acids. These analyses, therefore, suggest that the remagnetization was caused by organic maturation rather than orogenic fluids and that the maturation occurred in the Late Triassic. This timing of organic maturation has been validated by independent modeling studies and provides important constraints on the complex thermal history of the Longmaxi Shale as well as contributing to shale-gas exploration efforts.

  3. Characterization of gas hydrate distribution using conventional 3D seismic data in the Pearl River Mouth Basin, South China Sea

    USGS Publications Warehouse

    Wang, Xiujuan; Qiang, Jin; Collett, Timothy S.; Shi, Hesheng; Yang, Shengxiong; Yan, Chengzhi; Li, Yuanping; Wang, Zhenzhen; Chen, Duanxin

    2016-01-01

    A new 3D seismic reflection data volume acquired in 2012 has allowed for the detailed mapping and characterization of gas hydrate distribution in the Pearl River Mouth Basin in the South China Sea. Previous studies of core and logging data showed that gas hydrate occurrence at high concentrations is controlled by the presence of relatively coarse-grained sediment and the upward migration of thermogenic gas from the deeper sediment section into the overlying gas hydrate stability zone (BGHSZ); however, the spatial distribution of the gas hydrate remains poorly defined. We used a constrained sparse spike inversion technique to generate acoustic-impedance images of the hydrate-bearing sedimentary section from the newly acquired 3D seismic data volume. High-amplitude reflections just above the bottom-simulating reflectors (BSRs) were interpreted to be associated with the accumulation of gas hydrate with elevated saturations. Enhanced seismic reflections below the BSRs were interpreted to indicate the presence of free gas. The base of the BGHSZ was established using the occurrence of BSRs. In areas absent of well-developed BSRs, the BGHSZ was calculated from a model using the inverted P-wave velocity and subsurface temperature data. Seismic attributes were also extracted along the BGHSZ that indicate variations reservoir properties and inferred hydrocarbon accumulations at each site. Gas hydrate saturations estimated from the inversion of acoustic impedance of conventional 3D seismic data, along with well-log-derived rock-physics models were also used to estimate gas hydrate saturations. Our analysis determined that the gas hydrate petroleum system varies significantly across the Pearl River Mouth Basin and that variability in sedimentary properties as a product of depositional processes and the upward migration of gas from deeper thermogenic sources control the distribution of gas hydrates in this basin.

  4. The linkage between longitudinal sediment routing systems and basin types in the northern South China Sea in perspective of source-to-sink

    NASA Astrophysics Data System (ADS)

    Su, Ming; Hsiung, Kan-Hsi; Zhang, Cuimei; Xie, Xinong; Yu, Ho-Shing; Wang, Zhenfeng

    2015-11-01

    Using bathymetric and seismic data, this study describes the morpho-sedimentary features in Qiongdongnan basin and southwest Taiwan collision basin, northern South China Sea and reveals the linkages between sediment routing system and basin types. The modern Central Canyon in the Qiongdongnan basin is located along the rift margin, and subparallel to the shelf-break southeast of Hainan Island. The modern Central Canyon develops along the basin axis (i.e., Xisha Trough) and longitudinally transports sediments eastward which are mainly supplied by northern continental slope. The Penghu Canyon in the southwest Taiwan collision basin is located along the collision boundary parallel to the strike of the adjacent uplifted Taiwan orogen. The Penghu Canyon develops along the tilting basin axis transporting sediments longitudinally southward to the deep-sea basin and Manila Trench. The Penghu Canyon is supplied with sediments from both flank Kaoping and South China Sea slopes where tributary canyons and channels transport sediments down-slope and feed the axial canyon. The certain basin types may be occupied by particular styles of sediment routing system. By comparing the morpho-sedimentary features and basin characteristics associated with the modern Central Canyon to that of the Valencia Channel in NW Mediterranean Sea, the longitudinal sediment routing system in rift basin type can be determined. In contrast, the longitudinal sediment routing systems in collision setting can be represented by the comparable examples of Penghu Canyon in southwest Taiwan collision basin and Markham Canyon in western Solomon Sea. The rift type sediment routing system is characterized by an axial canyon with a single sediment supply from land drainage margin. In contrast, sediment routing system in collision type basins consists of an axial canyon and dual sediment supplies from flank adjacent slopes. The axial canyons in collision basins are more active than that of the rift basin due to

  5. Early Triassic conodonts of Jiarong, Nanpanjiang Basin, southern Guizhou Province, South China

    NASA Astrophysics Data System (ADS)

    Chen, Yanlong; Jiang, Haishui; Lai, Xulong; Yan, Chunbo; Richoz, Sylvain; Liu, Xiaodan; Wang, Lina

    2015-06-01

    Jiarong (Huishui County, Guizhou Province, South China) is a key locality for the study of the Early Triassic recovery after the end-Permian mass extinction. The size reduction of conodonts at the Smithian/Spathian transition was first documented in Jiarong, and it is also a locality that contributes to the documentation of the Early Triassic paleo-seawater temperatures. In the Jiarong sections, thirteen conodont zones were identified for the Early Triassic; in ascending order, they are Hindeodus parvus Zone, Hindeodus sosioensis Zone, Clarkina krystyni Zone, Neoclarkina discreta Zone, Neospathodus cristagalli-Eurygnathodus costatus assemblage zone, Novispathodus waageni eowaageni Zone, Novispathodus waageni waageni Zone, Discretella discreta Zone, Pachycladina-Parachirognathus assemblage zone, Novispathodus pingdingshanensis Zone, Icriospathodus collinsoni Zone, Triassospathodus homeri Zone, Triassospathodus triangularis Zone. These conodont zones in the Jiarong sections improve the global correlation of Early Triassic sections and also provide better regional age constraints in an area that is important for studies of recovery from the extinction. Based on the first appearance of Nv. waageni eowaageni, the Induan/Olenekian boundary is recognized at 3.6 m above the base of the Jiarong III Section. The dominance of blade-shaped (segminate) conodonts was replaced by gondola-shaped (segminiplanate) conodonts twice; the first time was in the late Griesbachian, and the second time was in the early Spathian. The dominance of segminiplanate conodonts probably indicates that the deeper seawater environment became more oxygenated during the late Griesbachian and early Spathian for short time intervals, as it is believed that the Griesbachian segminiplanate conodonts favored deeper oxygenated water habitats. A new genus, Spathogondolella gen. nov., and a new species, Spathogondolella jiarongensis sp. nov., have been recognized.

  6. Development of Paleogene depressions and deposition of Lacustrine source rocks in the Pearl River Mouth basin, northern margin of the South China Sea

    SciTech Connect

    Wang, Chunxiu; Sun, Yuxiao

    1994-11-01

    A more accurate, integrated chronostratigraphic framework is applied to the analysis of the development of Paleogene depressions in the Pearl River Mouth basin. The results of our study show that the development of these depressions was characterized by at least three rifting or basin-forming phases occurring during these periods: late Paleocene (Late Cretaceous?)-middle Eocene, late Eocene-early Oligocene, and middle-Oligocene-late Oligocene. The transition from rifting stage to postrifting stage in the basin is about 10 m.y. later than the initial spreading of the South China Sea. The prologue of the spreading of the South China Sea began as early as the end of the middle Eocene. Lacustrine source rocks deposited during the basin`s first rifting phase are thick and of good quality; source rocks deposited during the last two phases, which had a sharp increase in sedimentation rate, are of lesser quality, with the exception being those areas where deposits were out of reach of sediment from the northern mainland.

  7. Construction and preliminary analysis of a deep-sea sediment metagenomic fosmid library from Qiongdongnan Basin, South China Sea.

    PubMed

    Hu, Yongfei; Fu, Chengzhang; Yin, Yeshi; Cheng, Gong; Lei, Fang; Yang, Xi; Li, Jing; Ashforth, Elizabeth Jane; Zhang, Lixin; Zhu, Baoli

    2010-11-01

    Preliminary characterization of the microbial phylogeny and metabolic potential of a deep-sea sediment sample from the Qiongdongnan Basin, South China Sea, was carried out using a metagenomic library approach. An effective and rapid method of DNA isolation, purification, and library construction was used resulting in approximately 200,000 clones with an average insert size of about 36 kb. End sequencing of 600 individual clones from the fosmid library generated 1,051 sequences with an average sequence length of 619 bp. Phylogenetic ascription indicated that this library was dominated by Bacteria, predominantly Proteobacteria, though Planctomycetes were also relatively abundant. Sulfate-reducing and anaerobic ammonium-oxidizing bacteria, which play important roles in the cycling of sedimentary nutrients, were abundant in the library. Cluster of orthologous groups category analysis showed that most of the genes contained in the end sequences were related to metabolism, and with cellular processes and signaling. Functional groups assigned by SEED (subsystems-based annotations) highlighted the existence of 'one-carbon' metabolism within this community as well as identifying functional genes involved in methanogenesis. Furthermore, diverse genes involved in the biodegradation of xenobiotics were found using Kyoto Encyclopedia of Genes and Genomes metabolic pathway analysis. PMID:20514504

  8. Impacts of increased CO2 on the hydrologic response over the Xijiang (West River) basin, South China

    NASA Astrophysics Data System (ADS)

    Niu, Jun; Sivakumar, Bellie; Chen, Ji

    2013-11-01

    Increases in atmospheric carbon dioxide (CO2) concentration levels may affect terrestrial hydrologic processes through changes in evapotranspiration. This study assesses the hydrologic response to the elevated CO2 levels for the Xijiang (West River) basin in South China by applying the Variable Infiltration Capacity (VIC) model. The standard VIC model is modified by incorporating a mechanistic description of vegetation-type specific responses of both stomatal resistance and leaf area increase based on plant physiological studies. The dynamic (monthly) rises of CO2 concentration are introduced to estimate the historical impacts of increased CO2 over the past two decades (1991-2010). The cropland is identified as the most important contributor in the response of streamflow increase for the region. For a doubled atmospheric CO2 concentration scenario (660 ppm), the streamflow might rise about 3% (i.e. 21.8 mm/yr) under the baseline climatic conditions. Decreases in evapotranspiration and associated streamflow increases in response to ambient CO2 exposures are expected to episodically increase the frequency and severity of flood and affect flow-dependent aquatic biota in forested watersheds.

  9. Construction and preliminary analysis of a deep-sea sediment metagenomic fosmid library from Qiongdongnan Basin, South China Sea.

    PubMed

    Hu, Yongfei; Fu, Chengzhang; Yin, Yeshi; Cheng, Gong; Lei, Fang; Yang, Xi; Li, Jing; Ashforth, Elizabeth Jane; Zhang, Lixin; Zhu, Baoli

    2010-11-01

    Preliminary characterization of the microbial phylogeny and metabolic potential of a deep-sea sediment sample from the Qiongdongnan Basin, South China Sea, was carried out using a metagenomic library approach. An effective and rapid method of DNA isolation, purification, and library construction was used resulting in approximately 200,000 clones with an average insert size of about 36 kb. End sequencing of 600 individual clones from the fosmid library generated 1,051 sequences with an average sequence length of 619 bp. Phylogenetic ascription indicated that this library was dominated by Bacteria, predominantly Proteobacteria, though Planctomycetes were also relatively abundant. Sulfate-reducing and anaerobic ammonium-oxidizing bacteria, which play important roles in the cycling of sedimentary nutrients, were abundant in the library. Cluster of orthologous groups category analysis showed that most of the genes contained in the end sequences were related to metabolism, and with cellular processes and signaling. Functional groups assigned by SEED (subsystems-based annotations) highlighted the existence of 'one-carbon' metabolism within this community as well as identifying functional genes involved in methanogenesis. Furthermore, diverse genes involved in the biodegradation of xenobiotics were found using Kyoto Encyclopedia of Genes and Genomes metabolic pathway analysis.

  10. GIS/RS-based Integrated Eco-hydrologic Modeling in the East River Basin, South China

    NASA Astrophysics Data System (ADS)

    Wang, Kai

    Land use/cover change (LUCC) has significantly altered the hydrologic system in the East River (Dongjiang) Basin. Quantitative modeling of hydrologic impacts of LUCC is of great importance for water supply, drought monitoring and integrated water resources management. An integrated eco-hydrologic modeling system of Distributed Monthly Water Balance Model (DMWBM), Surface Energy Balance System (SEBS) was developed with aid of GIS/RS to quantify LUCC, to conduct physically-based ET (evapotranspiration) mapping and to predict hydrologic impacts of LUCC. To begin with, in order to evaluate LUCC, understand implications of LUCC and provide boundary condition for the integrated eco-hydrologic modeling, firstly the long-term vegetation dynamics was investigated based on Normalized Difference Vegetation Index (NDVI) data, and then LUCC was analyzed with post-classification methods and finally LUCC prediction was conducted based on Markov chain model. The results demonstrate that the vegetation activities decreased significantly in summer over the years. Moreover, there were significant changes in land use/cover over the past two decades. Particularly there was a sharp increase of urban and built-up area and a significant decrease of grassland and cropland. All these indicate that human activities are intensive in the East River Basin and provide valuable information for constructing scenarios for studying hydrologic impacts of LUCC. The physically-remote-sensing-based Surface Energy Balance System (SEBS) was employed to estimate areal actual ET for a large area rather than traditional point measurements . The SEBS was enhanced for application in complex vegetated area. Then the inter-comparison with complimentary ET model and distributed monthly water balance model was made to validate the enhanced SEBS (ESEBS). The application and test of ESEBS show that it has a good accuracy both monthly and annually and can be effectively applied in the East River Basin. The results of

  11. Sediment flux history of Pearl River mouth basin, North margin of South China Sea

    NASA Astrophysics Data System (ADS)

    Wu, S.

    2004-12-01

    This work estimates the solid sediment flux in Pearl River mouth basin from Cenozoic (42Ma). The estimates were derived from isopach maps, seismic reflection profiles and drill holes. Average solid sediment fluxes were calculated for six epochs approximately corresponding to geological periods: Eocene-Lower Oligocene (42-29.3), Upper Oligocene (29.3-23.8), Lower Miocene (23.8-16.4), Middle Miocene (16.4-11.2), Upper Miocene (11.2-5.32), and Pliocene-Pleistocene (5.32-0). The total sediment flux from 42 Ma is 392071.3 km3 and 0.89 km of erosion formed from the onshore drainage basin area. The average erosion rate is 22 m/ Ma. The sediment flux curve shows 3 episodes massive increase in sediment supply, i.e. Upper Oligocene, Middle Miocene and Pliocene-Pleistocene. The first increase related to the break up activity and is the product of elevated rift shoulder. The other two increase peak link to the changing of climate.

  12. Daily anomalous high flow (DAHF) of a headwater catchment over the East River basin in South China

    NASA Astrophysics Data System (ADS)

    Chen, Ji; Niu, Jun; Sivakumar, Bellie

    2014-11-01

    This study develops a new method for analyzing the terrestrial hydrologic responses to precipitation through using level-based daily anomalous high flow (DAHF) occurrence in a catchment. The objectives of this study are twofold: (1) to explore the DAHF features over a headwater catchment; and (2) to evaluate the performance of a hydrologic model for DAHF simulation. In this study, DAHF is defined as the daily streamflow on a given day, whose deseasonalised daily streamflow is larger than a given multiplier of the standard deviation (STD) of the long-term deseasonalised streamflow series. Streamflow observations of a headwater catchment over the period of 1952-1972 (i.e., before reservoir operation) at the Longchuan station in the East River basin in South China are studied. The macro-scale Variable Infiltration Capacity (VIC) model is used for streamflow simulation in the catchment, and wavelet analysis is performed to explore the DAHF variability. The study reveals that the percentages of the number of days with the first and second levels of DAHFs are 4.2% and 1%, respectively, for the observed streamflows, while the corresponding percentages for the VIC model-simulated streamflow are 5% and 1.3%, respectively. Application of the Kolmogorov-Smirnov goodness-of-fit test indicates that these two levels of DAHFs can be described by two probability distribution functions, namely the Lognormal distribution and Generalized Extreme Value Type II distribution, respectively. The variability spectrum of the first level DAHF is basically consistent with that of antecedent precipitation, but not for the second level DAHF, as revealed by the wavelet analysis. The VIC model has better performance on the variability simulation of the first level of DAHF.

  13. Seismic Characteristics and Evolution of Intrusion in Qiongdongnan Basin: Implications for the Rifting of South China Sea

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Ren, J.; Yang, L.; Huang, C.

    2014-12-01

    The South China Sea (SCS) formed by magma-poor rifting in the Paleogene. The Qiongdongnan basin (QDNB) located at the north margin was thought to completely lack magma activities. Due to the limited amount of deepwater drills, magmas in deepwater area had been ignored in petroleum exploration, and thus our knowledge of basin analysis is far from complete. Based on a comprehensive study on seismic profiles and P wave velocity data, 12 intrusion-related seismic reflection anomalies in QDNB have been recognized. In the southwest of QDNB, gas chimneys and gas clouds have been found with a low velocity (<3.4 km/s). In the center area, the intensively deformed strata passing towards the diapir flanks suggest the existence of magma diapirs. However, the velocity within diapirs is neither too high nor too low (3.7-4.6 km/s), and there has been no obvious magnetic anomaly or gravity anomaly be found. Previous researches prove that the temperatures of the crustal melt layers at the time that the basalt solidifies are high (900-950 °C) so that the process can produce magmas representing large degrees of partial fusion of the crust. To judge from the evidence, in the center area these could be mixed magmas. Further east, the diapirs possess typical features of basaltic magma intrusions with a high seismic velocity (>6 km/s), a positive magnetic anomaly and a high gravity anomaly. In addition, according to different dips of marginal facies, three phases of diapirism can be identified (32 Ma, 15.5 Ma and 10.5 Ma). Along a narrow area with hyper-extended crust, those intrusions document the opening of SCS at 32 Ma and the volcanic activities afterwards. The results are corresponding to the fact that all of the intrusions in QDNB occurred during the extreme crustal thinning process and after the cessation of seafloor spreading, and thus the intrusion evolved with time would have major implications for post-rift emplacement.

  14. Fast Deposition of Small River Particles on the NE South China Sea Slope Basin Since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Lin, S.; Cheng, W. Y.; Hsieh, I. C.

    2015-12-01

    Huge quantities of small rivers derived suspended particles are exporting to the ocean from oceanic islands at the present time. Depending on location and proportion of shelf/slope area, a major fraction of small river particles may by-pass the shelf region, transport and deposit on the deep ocean basin. Major mechanisms driving those huge quantities of small river derived particles to the ocean are quantity of precipitation from monsoon and those from short period of tropical cyclone. Although data demonstrate that deeper part of the South China Sea, SCS, is the major final burial location of the river derived particles from the island of Taiwan, it is not sure if this was the same during the glaciation when monsoon and climatic conditions were drastic different from the present time. The purpose of this study is to understand history of small river derived sediment export and deposition during climatic change. A long piston core with length of ~35 meter was taken on r/v Marion DuFresne on a slope basin offshore SW Taiwan. We have measured density, magnetic susceptibility with multi-sensor core logger, MSCL, and organic, inorganic carbon, C/N ratio, biogenic silica as well as grain sizes. Foraminifera (Orbulina universa, Globigerinoides sacculifer and Globigerinoides conglobatus) were picked and measured carbon 14 for age determination. Two different types of processes control sediment deposition in our study site, steady state and event driven sedimentation. Our results demonstrated that sedimentation rates were consistent during each major periods, the Holocene (present to 10k year) and the transition (10-20 k year) period, but, difference existed in between the two. Sedimentation rate was about twice faster during the transition period (20-10k year) than that at the Holocene (10-present time) at our study site. A number of spikes existed in our study site, probably a result of turbidite overflow from the adjacent canyon. Frequency and total thickness of event

  15. Chemical weathering inferred from riverine water chemistry in the lower Xijiang basin, South China.

    PubMed

    Sun, Huiguo; Han, Jingtai; Li, Dong; Zhang, Shurong; Lu, Xixi

    2010-09-15

    Seasonal sampling was conducted on 13 sites involving the lower stem of the Xijiang river and its three tributaries to determine the spatial patterns of the riverine water chemistry and to quantify the chemical weathering rates of carbonate and silicate of the bedrock. Results indicate that the major ions in the Xijiang river system are dominated by Ca(2+) and HCO(3)(-) with a higher concentration of total dissolved solids, characteristic of the drainages developed on typical carbonate regions. Obvious spatial variations of major ion concentrations are found at various spatial scales, which are dominantly controlled by the lithology particularly carbonate distribution in the region. The four selected rivers show similar seasonal variations in major ions, with lower concentrations during the rainy season. Runoff is the first important factor for controlling the weathering rate in the basin, although increasing temperature and duration of water-rock interaction could make positive contributions to the enhancement of chemical weathering. The chemical weathering rates range from 52.6 to 73.7 t/km(2)/yr within the lower Xijiang basin and carbonate weathering is over one order of magnitude higher than that of silicates. CO(2) consumption rate by rock weathering is 2.0 x 10(11) mol/yr, of which more than 60% is contributed by carbonate weathering. The flux of CO(2) released to the atmosphere-ocean system by sulfuric acid-induced carbonate weathering is 1.1 x 10(5) mol/km(2)/yr, comparable with the CO(2) flux consumed by silicate weathering.

  16. Early Triassic calcimicrobial mounds and biostromes of the Nanpanjiang basin, south China

    NASA Astrophysics Data System (ADS)

    Lehrmann, Daniel J.

    1999-04-01

    Early Triassic framestones were discovered in the interior of an isolated, marine carbonate platform in the Nanpanjiang basin. The framestones occur in two horizons: (1) the lowermost Triassic (Griesbachian), as biostromes as much as 15 m thick, and (2) the upper part of the Lower Triassic (Smithian or Spathian) as isolated domal or inverted conical mounds as much as 1.5 m thick. The mounds and biostromes consist of a rigid calcimicrobial framework enclosing a network of internal cavities, 1 to 3 cm across, filled with peloidal-skeletal sediment. The framework is made of irregular-to-tufted masses of chambered-to-clotted micrite structures referable to Renalcis, a calcified coccoid cyanobacteria. The framework is reinforced by microbial induced micritic crusts as well as marine cement. Metazoan fossils within the framework include gastropods, bivalves, ostracodes, spirorbids, and brachiopods. The Early Triassic is widely considered to have been a global gap in reef and reef mound development. The global reef gap concept has formed the foundation of models of reef evolution and of the reorganization of reef ecosystems after the end-Permian extinction. These models should be revised to account for the existence of Early Triassic calcimicrobial mounds and biostromes discussed herein.

  17. Mesozoic deformation in the Chaoshan Depression of the Pearl River Mouth Basin, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Zhang, Jiangyang; Sun, Zhen; Zhang, Yunfan; Li, Fucheng

    2016-05-01

    Newly collected, high resolution multi-beam sonar data are combined with previous bathymetry data to produce an improved bathymetric map of Shatsky Rise oceanic plateau. Bathymetry data show that two massifs within Shatsky Rise are immense central volcanoes with gentle flank slopes declining from a central summit. Tamu Massif is a slightly elongated, dome-like volcanic edifice; Ori Massif is square shaped and smaller in area. Several down-to-basin normal faults are observed on the western flank of the massifs but they do not parallel the magnetic lineations, indicating that these faults are probably not related to spreading ridge faulting. Moreover, the faults are observed only on one side of the massifs, which is contrary to expectations from a mechanism of differential subsidence around the massif center. Multi-beam data show many small secondary cones with different shapes and sizes that are widely-distributed on Shatsky Rise massifs, which imply small late-stage magma sources scattered across the surface of the volcanoes in the form of lava flows or explosive volcanism. Erosional channels occur on the flanks of Shatsky Rise volcanoes due to mass wasting and display evidence of down-slope sediment movement. These channels are likely formed by sediments spalling off the edges of summit sediment cap.

  18. Geophysical Investigations of Crustal Structure of Cenozoic Rifting Basin in Passive Continental Margin: The Pearl River Mouth Basin, South China Sea

    NASA Astrophysics Data System (ADS)

    Qiu, N.

    2015-12-01

    The Pearl River Mouth Basin (PRMB) initiated in the Cenozoic with rifting, and became a part of the South China Sea (SCS) rifted passive continental margin. Decades of industrial exploration in this proliferous region have produced lots of geological and geophysical data. In order to get the first order crustal scale structure, we integrate well data, multi channel seismic reflection, and the observed gravity field for a joint inversion. The Cenozoic sediment of PRMB comprises of several stratigraphic sequences, including the terrestrial facies, the marine facies and the transitional facies. The sedimentary model takes into account of two main parts that refer to the Paleogene to Neogene unit and the Neogene to Quaternary unit, which were respectively formed during the intercontinental rifting stage and the passive continental margin post-rifting stage. By integrating long cable seismic profiles, interval velocity and performing gravity modelling, we have modelled the sub-sedimentary basement. There are some high-density bodies in the lower part of crust (ρ> 2.8 g/cm3), most of which were probably made up by emplacement from the upper mantle into the lower crust. The crystalline continental crust spans from unstretched domains (as thick as about 25 km) near the continental shelf to extremely thinned domains (of less than 6 km thickness) in the sag center. The presented crust-scale structural model shows that the crystalline crust of the Liwan Sag (LWS) and Baiyun sag (BYS) are thinner than other parts of PRMB, especially, the crystalline crust thickness in BYS is even less than 6 km. we could preliminary infer that the crystalline crust may be more easily stretched and be thinned by the existence of hot and soft substances at the lower crust.

  19. Petroleum systems of Zhu III depression in Pearl River Mouth Basin, South China Sea

    SciTech Connect

    Weilin, Zhu; Li Mingbi; Wu Peikang

    1996-12-31

    Zhu III depression is located in the west part of Pearl River Mouth Basin, and covers an area of 11,000 sq km. Until now more than twenty wells have been drilled in the depression and its surrounding area, and all oil-gas fields and oil-gas discoveries are concentrated inside the depression. Integrated study indicates that there are two petroleum systems in Zhu III depression. One is Wenchang - Zhuhai, Zhujiang oil system which is mainly distributed in Wenchang B sag in the southwest part of the depression. Its source rock, the Wenchang formation is mainly composed of dark mudstone of lacustrine facies, with thicknesses up to more than 1000 m. Its reservoir includes tidal sandstone of transitional facies of Zhuhai formation and neritic sandstone of the lower part of Zhujiang formation. Through bounding faults and margin coarse sediment zone, oil generated from the Wenchang formation migrated into overlying sandstone of Zhuhai formation, which was overlaid by mudstone beds of bay facies of Zhuhai formation or neritic facies of Zhujiang formation, and formed oil accumulations. The other system is Enping - Zhuhai gas system, distributed in Wenchang A sag in the northeast part of the depression, whose source rock in the Enping formation deposited in the contracting stage of the lake, dominated by swamp coal measure in lithology and terrestrial plant clastics in kerogen components. The gas generated from Enping formation directly migrated into overlying tidal sandstone of Zhuhai formation and formed gas accumulations. Therefore, exploration in Wenchang A sag in the northeast part of the depression is for gas accumulations, and oil accumulations in Wenchang B sag in the southwest part of the depression, while oil-gas mixed accumulations are likely to be found in the transitional area of two systems.

  20. Petroleum systems of Zhu III depression in Pearl River Mouth Basin, South China Sea

    SciTech Connect

    Weilin, Zhu; Li Mingbi; Wu Peikang )

    1996-01-01

    Zhu III depression is located in the west part of Pearl River Mouth Basin, and covers an area of 11,000 sq km. Until now more than twenty wells have been drilled in the depression and its surrounding area, and all oil-gas fields and oil-gas discoveries are concentrated inside the depression. Integrated study indicates that there are two petroleum systems in Zhu III depression. One is Wenchang - Zhuhai, Zhujiang oil system which is mainly distributed in Wenchang B sag in the southwest part of the depression. Its source rock, the Wenchang formation is mainly composed of dark mudstone of lacustrine facies, with thicknesses up to more than 1000 m. Its reservoir includes tidal sandstone of transitional facies of Zhuhai formation and neritic sandstone of the lower part of Zhujiang formation. Through bounding faults and margin coarse sediment zone, oil generated from the Wenchang formation migrated into overlying sandstone of Zhuhai formation, which was overlaid by mudstone beds of bay facies of Zhuhai formation or neritic facies of Zhujiang formation, and formed oil accumulations. The other system is Enping - Zhuhai gas system, distributed in Wenchang A sag in the northeast part of the depression, whose source rock in the Enping formation deposited in the contracting stage of the lake, dominated by swamp coal measure in lithology and terrestrial plant clastics in kerogen components. The gas generated from Enping formation directly migrated into overlying tidal sandstone of Zhuhai formation and formed gas accumulations. Therefore, exploration in Wenchang A sag in the northeast part of the depression is for gas accumulations, and oil accumulations in Wenchang B sag in the southwest part of the depression, while oil-gas mixed accumulations are likely to be found in the transitional area of two systems.

  1. Hydrocarbon- and ore-bearing basinal fluids: a possible link between gold mineralization and hydrocarbon accumulation in the Youjiang basin, South China

    NASA Astrophysics Data System (ADS)

    Gu, X. X.; Zhang, Y. M.; Li, B. H.; Dong, S. Y.; Xue, C. J.; Fu, S. H.

    2012-08-01

    The Youjiang basin, which flanks the southwest edge of the Yangtze craton in South China, contains many Carlin-type gold deposits and abundant paleo-oil reservoirs. The gold deposits and paleo-oil reservoirs are restricted to the same tectonic units, commonly at the basinal margins and within the intrabasinal isolated platforms and/or bioherms. The gold deposits are hosted by Permian to Triassic carbonate and siliciclastic rocks that typically contain high contents of organic carbon. Paragenetic relationships indicate that most of the deposits exhibit an early stage of barren quartz ± pyrite (stage I), a main stage of auriferous quartz + arsenian pyrite + arsenopyrite + marcasite (stage II), and a late stage of quartz + calcite + realgar ± orpiment ± native arsenic ± stibnite ± cinnabar ± dolomite (stage III). Bitumen in the gold deposits is commonly present as a migrated hydrocarbon product in mineralized host rocks, particularly close to high grade ores, but is absent in barren sedimentary rocks. Bitumen dispersed in the mineralized rocks is closely associated and/or intergrown with the main stage jasperoidal quartz, arsenian pyrite, and arsenopyrite. Bitumen occurring in hydrothermal veins and veinlets is paragenetically associated with stages II and III mineral assemblages. These observations suggest an intimate relationship between bitumen precipitation and gold mineralization. In the paleo-petroleum reservoirs that typically occur in Permian reef limestones, bitumen is most commonly observed in open spaces, either alone or associated with calcite. Where bitumen occurs with calcite, it is typically concentrated along pore/vein centers as well as along the wall of pores and fractures, indicating approximately coeval precipitation. In the gold deposits, aqueous fluid inclusions are dominant in the early stage barren quartz veins (stage I), with a homogenization temperature range typically of 230°C to 270°C and a salinity range of 2.6 to 7.2 wt% NaCl eq

  2. Low Angle Normal Fault System Controls the Structure Evolution of Baiyun Deepwater Basin and Its Lithosphere Thinning, Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Ren, J.; Yang, L.

    2015-12-01

    The discovery of the transition area from ~30 km to weakly thinned continental crust (<12 km) in Baiyun deepwater basin, Northern South China Sea leads to two questions: What controls extreme crustal thinning and what is the nature of Baiyun basin. The 3D seismic data newly acquired show that Baiyun basin is an asymmetric half graben mainly controlled by a set of north-dipping normal faults converging in deep. By employing the principle of back-stripping, we estimate the fault dips and slip amount would be in the absence of post-rift sediments and seawater loading. Results show these Middle Eocene faults were extremely active, with a high accumulation horizontal displacement (> 10 km) and an initial very low angle (<7°), followed by a rotated into sub-horizontal. A general scenario for extension of the uppermost continental crust probably includes simultaneous operation of low angle normal fault (F1) as well as parallel arrays of step-faults (domino-faults, f2-f9). Under such a scenario, it shows no obvious extension discrepancy in Baiyun basin. Our results indicate that Baiyun sag preserves information recording the continent thinning before the seafloor spreading, and it could be an abandoned inner rifted basin.

  3. South China Sea.

    PubMed

    Morton, B; Blackmore, G

    2001-12-01

    The South China Sea is poorly understood in terms of its marine biota, ecology and the human impacts upon it. What is known is most often contained in reports and workshop and conference documents that are not available to the wider scientific community. The South China Sea has an area of some 3.3 million km2 and depths range from the shallowest coastal fringe to 5377 m in the Manila Trench. It is also studded with numerous islets, atolls and reefs many of which are just awash at low tide. It is largely confined within the Tropic of Cancer and, therefore, experiences a monsoonal climate being influenced by the Southwest Monsoon in summer and the Northeast Monsoon in winter. The South China Sea is a marginal sea and, therefore, largely surrounded by land. Countries that have a major influence on and claims to the sea include China, Malaysia, the Philippines and Vietnam, although Thailand, Indonesia and Taiwan have some too. The coastal fringes of the South China Sea are home to about 270 million people that have had some of the fastest developing and most vibrant economies on the globe. Consequently, anthropogenic impacts, such as over-exploitation of resources and pollution, are anticipated to be huge although, in reality, relatively little is known about them. The Indo-West Pacific biogeographic province, at the centre of which the South China Sea lies, is probably the world's most diverse shallow-water marine area. Of three major nearshore habitat types, i.e., coral reefs, mangroves and seagrasses, 45 mangrove species out of a global total of 51, most of the currently recognised 70 coral genera and 20 of 50 known seagrass species have been recorded from the South China Sea. The island groups of the South China Sea are all disputed and sovereignty is claimed over them by a number of countries. Conflicts have in recent decades arisen over them because of perceived national rights. It is perhaps because of this that so little research has been undertaken on the

  4. South China Sea.

    PubMed

    Morton, B; Blackmore, G

    2001-12-01

    The South China Sea is poorly understood in terms of its marine biota, ecology and the human impacts upon it. What is known is most often contained in reports and workshop and conference documents that are not available to the wider scientific community. The South China Sea has an area of some 3.3 million km2 and depths range from the shallowest coastal fringe to 5377 m in the Manila Trench. It is also studded with numerous islets, atolls and reefs many of which are just awash at low tide. It is largely confined within the Tropic of Cancer and, therefore, experiences a monsoonal climate being influenced by the Southwest Monsoon in summer and the Northeast Monsoon in winter. The South China Sea is a marginal sea and, therefore, largely surrounded by land. Countries that have a major influence on and claims to the sea include China, Malaysia, the Philippines and Vietnam, although Thailand, Indonesia and Taiwan have some too. The coastal fringes of the South China Sea are home to about 270 million people that have had some of the fastest developing and most vibrant economies on the globe. Consequently, anthropogenic impacts, such as over-exploitation of resources and pollution, are anticipated to be huge although, in reality, relatively little is known about them. The Indo-West Pacific biogeographic province, at the centre of which the South China Sea lies, is probably the world's most diverse shallow-water marine area. Of three major nearshore habitat types, i.e., coral reefs, mangroves and seagrasses, 45 mangrove species out of a global total of 51, most of the currently recognised 70 coral genera and 20 of 50 known seagrass species have been recorded from the South China Sea. The island groups of the South China Sea are all disputed and sovereignty is claimed over them by a number of countries. Conflicts have in recent decades arisen over them because of perceived national rights. It is perhaps because of this that so little research has been undertaken on the

  5. The South China Sea Deep: Introduction

    NASA Astrophysics Data System (ADS)

    Wang, Pinxian; Li, Qianyu; Dai, Minhan

    2015-12-01

    The South China Sea (SCS) has increasingly become a global focus in ocean research and hydrocarbon explorations. Over the last two decades, at least 17 international cruises including two ODP/IODP expeditions were conducted in the SCS, and more than 2000 exploratory wells were drilled (Wang et al., 2014a). While its sedimentary basins on the continental shelf and slope are explored for offshore resources, the deep basin below 3500 m in depth that overlies the basaltic oceanic crust preserves the key to understanding their formation and development. In order to better understand the life history and functional system of the marginal sea, a major research program "Deep Sea Processes and Evolution of the South China Sea", or "The South China Sea Deep" for short, was launched in January 2011 by the National Natural Science Foundation (NSFC) of China. This venture represents the first ever large-scale basic-research program in ocean science in the country (Wang, 2012).

  6. Strain partitioning of the Red River fault system explains the initiation of the Yinggehai Basin in the northwest region of South China Sea

    NASA Astrophysics Data System (ADS)

    Wang, X.; He, J.; Ding, L.; Gao, R.; Ai, C.; Wang, X.; Pan, Z.

    2012-12-01

    The NW-trending Yinggehai Basin (YGHB), located around the Red River fault system (RRFS) in the northwest area of South China Sea (SCS), is an important petroleum-bearing province and characterized by a maximum sedimentation thickness of up to 17 km, a strong upwelling of Moho at 22-23 km depth, an average heat flow of 86 mW/m2, and diapirs structure. The YGHB is suggested to be closely related to the crustal deformation associated with displacements of the RRFS and the formation of the SCS, but the basin differs in its formation from the NE-trending Pearl River Mouth Basin and Qingdongnan Basin on the northern continental margin of SCS and the Yuanjiang Basin and Midu Basin along the RRFS. Based on a first-order estimate of the rheology and boundary condition of the YGHB, we developed a 2.5 dimensional finite element model to investigate the origin of the YGHB and the relationships between motions on the RRFS and the spreading of the SCS. The crustal rheology is simplified as an elasto-plastic upper crust and a visco-elastic lower crust. Possible lateral variations of viscosity in the lower crust are tested according to the tectonic setting of the basin region. Results show that associated with the regional crustal movements, deformation of the RRFS could be responsible for upper crustal extension on both its sides. Further, the style of extensional faulting around the RRFS is largely controlled by the rheology of the lower crust. This means that strain partitioning induced both by the transtensional loading of strike-slip fault system and by the lateral changes in rheology of the lower crust can result in normal faulting on both sides near the RRFS, and may be involved in the formation of the YGHB.

  7. Improving Seasonal Precipitation Predictions over the East River Basin, South China by Using Bias-corrected CFSv2 Forecasts

    NASA Astrophysics Data System (ADS)

    Wang, D.; Zhu, C.; Wu, Y.; Lin, K.; Liu, B.; Chen, Z.; Xinjun, T.; Huang, M.

    2015-12-01

    East River is one the major tributaries of Peal River, the third largest river over China. It is the most important water resource for agriculture, industry, and commerce in the Pearl River Delta. The water demand has dramatically increased with rapid population growth and booming economic development in this region. To meet the demand of water supply, the East River basin administration has conducted the water quantity operation over the basin since 2008. However, the operation target has been hardly achieved largely due to poor precipitation predictions. We try to improve seasonal precipitation predictions by correcting the bias of the NCEP CFSv2 forecasts. A variety of bias correction methods are applied to correct CFSv2 forecasts based on a long term datasets of gauge observations and CFSv2 reforecasts. The proper bias methods are selected for the flood and the dry season respectively based on evaluation results. The CFSv2 based predictions would help in making a reasonable water quantity operation plan and improving operational performance over the East River basin.

  8. Insights from heavy minerals and zircon U-Pb ages into the middle Miocene-Pliocene provenance evolution of the Yinggehai Basin, northwestern South China Sea

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; Cao, Licheng; Xie, Xinong; Wang, Zhenfeng; Li, Xushen; Zhang, Yingzhao; Zhang, Daojun; Sun, Hui

    2015-08-01

    The well-preserved Cenozoic sedimentary record in the Yinggehai Basin, South China Sea, is suitable to explore the tectonic and climatic evolution of SE Asia. Red River, a large-scale fluvial system in this region, was previously regarded as the major sediment source for the basin. Here we combine heavy mineral analysis and detrital zircon U-Pb dating to shed new light on the middle Miocene-Pliocene provenance evolution at a basin scale. The results clearly reveal potential source areas additional to the Red River. Sediments have been delivered to the proximal areas from Hainan Island, as indicated by the high zircon content and the Yanshanian U-Pb ages in the southern segment of the Yingdong Slope. A provenance from Central Vietnam is explicitly discerned in the upper Miocene of the Central Depression, where sediments are characterized by few metamorphic heavy minerals and the U-Pb age pattern peaking at around 250 Ma and 440 Ma. Coeval large-scale relative sea-level fall and rapid exhumation along the Vietnamese margin together may have facilitated this long-distance sediment transport. Provenance of sediments from the Red River seems to change over time. Song Lo River, on the north side of the main stream, probably flowed from the NE and carried Neoproterozoic-early Paleozoic zircons to the Yinggehai Basin during the middle Miocene. Since the late Miocene, rocks along the Red River Fault Zone have become the dominant source. Subsequently, widespread metamorphic minerals in the Central Depression of the Yinggehai Basin, combined with the strong river incision and high offshore sedimentation rates, indicate an increased sediment supply from the Red River in the Pliocene.

  9. Development of Tertiary Basins of SE Asia from the South China Sea to the Andaman Sea region ; a comparative view on structure and timing

    NASA Astrophysics Data System (ADS)

    Pubellier, Manuel; Sautter, Benjamin

    2016-04-01

    Basins of SE Asia have developed since the end of Cretaceous times to the detriment of a Mesozoic andean arc which surrounded Sundaland. The arc was broader in the Eastern part along the Pacific Subduction Zone including theSouth China Sea (SCS), than in the Western part along the Sumatra Subduction Zone (Myanmar, Andaman Sea (AS), Malay Peninsula). By the end of the Upper Cretaceous, this arc died out and a widespread rifting with astonishing resemblances started in the whole Sundaland. We compare and discuss the basins similarities and differences in structure and timing between the two sides. A relaxation stage is evidenced in Western Sunda, represented by poorly exposed Late Cretaceous red beds filling the pre-existing morphostructures without clear fault-controlled basins. These deposits are also observed on seismic data offshore in the Gulf of Thailand and AS). On the opposite side along the Chinese margin, thick molasse-type deposits of Late Cretaceous age are on the contrary well expressed offshore and restricted to narrow valleys, indicating that stretching had already begun. There, the Paleogene is marked by strong extension with large crustal blocks rotated by often counter-regional normal faults creating half grabens. Crust was extended and extremely thinned particularly around the SCS. Basins reached the spreading stage in the Celebes Sea, the North Makassar basin and the SCS. On the western side, this period corresponds to narrow deep grabens (e.g. Mergui basins and part of western Malacca) with continental deposits, meaning that the stretching was localized. There, thinning of the crust took place during the Oligocene up to the Middle Miocene where large basins develop mostly to the outer edges of the Yenshanian Arc. Extension resumed in the Pliocene with the opening of the Andaman basin in an even more external position. To the eastern side the uppermost Miocene and the Pliocene were marked mostly by a deepening of the margins and the SCS ocean

  10. Seismic features and evolution of a late Miocene submarine channel system in the Yinggehai basin, northwestern South China Sea

    NASA Astrophysics Data System (ADS)

    Sun, H.; Jiang, T.; Wang, Z.; Zhang, Y.

    2014-12-01

    Submarine channel is one of key conduits for coarse terrigenous clastic sediments to abyssal plain, which provides the possibility for deepwater hydrocarbon exploration. Recently, a new high-quality 3D seismic data is acquired in south Yinggehai basin (YGHB) and the detailed interpretations on those seismic profiles as well as RMS amplitude attributes and variance slices reveal a submarine channel system developed in late Miocene, which could be supplied from Hainan Island via turbidity currents so that it would be filled with sand-rich turbidites as good hydrocarbon reservoir. Based on the integration between regional seismic survey and some boreholes, the investigations on its infilling architectures and depositional processes are carried out. The results show that it composes two converged submarine channels with two channelized submarine fans to their west and the main submarine channel (MSC) is characterized by a downstream increasing width and is infilled by sediments with high amplitude seismic facies, which could be originated from channelized submarine fans. Furthermore, the complicated depositional processes around the confluence region of these two channels are pointed out and the interactions between the submarine channel system and nearby channelized submarine fans are discussed. The detailed illustration on the seismic features and depositional processes of the subsurface submarine system provides us better understanding deepwater sedimentary dynamics and would be more benefit for the hydrocarbon exploration in similar deepwater area around the world.

  11. Overpressure retardation of organic-matter maturation and petroleum generation: A case study from the Yinggehai and Qiongdongnan Basins, South China Sea

    SciTech Connect

    Hao Fang; Sun Yongchuan; Li Sitian; Zhang Qiming

    1995-04-01

    Three superimposed pressure systems developed in the Yinggehai Basin, South China Sea, as indicated by seismic data, well logs, and direct pressure measurements. The organic maturation profile is nonlinear, with three nonparallel segments that correspond to the shallow, normal-pressured system; the intermediate, overpressured system; and the deep, strongly overpressured system respectively. The intermediate and deep overpressured systems have abnormally low R{sub 0} gradients. The organic maturity of these overpressured rocks is significantly lower than the maturity of normal-pressured source rocks in nearby wells with similar thermal histories and does not math the thermal histories of the rocks. Such an organic maturity anomaly is distinctly different from those caused by variation in activation energies, conductivity contrasts, and hydrologic effects, and is confirmed to be the result of overpressure retardation. The degree to which the organi-matter maturation is retarded, expressed as the difference between predicted and measured vitrinite reflectance, increases exponentially with increasing fluid pressure, confirming that pressure increases the activation energies of organi-matter maturation reactions. Overpressure retardation has been proven to be conditional and quite important for clearly understanding petroleum generation, migration, and accumulation in overpressured sedimentary basins.

  12. Spreading dynamics and sedimentary process of the Southwest Sub-basin, South China Sea: Constraints from multi-channel seismic data and IODP Expedition 349

    NASA Astrophysics Data System (ADS)

    Ding, Weiwei; Li, Jiabiao; Clift, Peter D.

    2016-01-01

    Neotectonic and sedimentary processes in the South China Sea abyssal basin are still debated because of the lack of drilling evidence to test competing models. In this study, we interpreted four multi-channel seismic profiles across the Southwest Sub-basin (SWSB) and achieved stratigraphic correlation with new drilling data from Integrated Ocean Discovery Program (IODP) Expedition 349. Neogene sediments are divided into four stratigraphic units, each with distinctive seismic character. Sedimentation rate and lithology variations suggest climate-controlled sedimentation. In the late Miocene winter monsoon strength and increased aridity in the limited accumulation rates in the SWSB. Since the Pliocene summer monsoons and a variable glacial-interglacial climate since have enhanced accumulation rates. Terrigeneous sediments in the SWSB are most likely derived from the southwest. Three basement domains are classified with different sedimentary architectures and basement structures, including hyper-stretched crust, exhumed subcontinental mantle, and steady state oceanic crust. The SWSB has an asymmetric geometry and experienced detachment faulting in the final stage of continental rifting and exhumation of continental mantle lithosphere. Mantle lithospheric breakup post-dates crustal separation, delaying the establishment of oceanic spreading and steady state crust production.

  13. Spreading Dynamics and Sedimentary Process of the Southwest Sub-basin, South China Sea: Constraints from multi-channel seismic data and IODP Expedition 349

    NASA Astrophysics Data System (ADS)

    Ding, Weiwei; Li, Jiabiao; Clift, Peter

    2016-04-01

    Neotectonic and sedimentary processes in the South China Sea abyssal basin are still debated because of the lack of drilling evidence to test competing models. In this study, we interpreted four multi-channel seismic profiles across the Southwest Sub-basin (SWSB) and achieved stratigraphic correlation with new drilling data from Integrated Ocean Discovery Program (IODP) Expedition 349. Neogene sediments are divided into four stratigraphic units, each with distinctive seismic character. Sedimentation rate and lithology variations suggest climate-controlled sedimentation. In the late Miocene winter monsoon strength and increased aridity in the limited accumulation rates in the SWSB. Since the Pliocene summer monsoons and a variable glacial-interglacial climate since have enhanced accumulation rates. Terrigeneous sediments in the SWSB are most likely derived from the southwest. Three basement domains are classified with different sedimentary architectures and basement structures, including hyper-stretched crust, exhumed subcontinental mantle, and steady state oceanic crust. The SWSB has an asymmetric geometry and experienced detachment faulting in the final stage of continental rifting and exhumation of continental mantle lithosphere. Mantle lithospheric breakup post-dates crustal separation, delaying the establishment of oceanic spreading and steady state crust production.

  14. Analyzing the water budget and hydrological characteristics and responses to land use in a monsoonal climate river basin in South China.

    PubMed

    Wu, Yiping; Chen, Ji

    2013-06-01

    Hydrological models have been increasingly used by hydrologists and water resource managers to understand natural processes and human activities that affect watersheds. In this study, we use the physically based model, Soil and Water Assessment Tool (SWAT), to investigate the hydrological processes in the East River Basin in South China, a coastal area dominated by monsoonal climate. The SWAT model was calibrated using 8-year (1973-1980) record of the daily streamflow at the basin outlet (Boluo station), and then validated using data collected during the subsequent 8 years (1981-1988). Statistical evaluation shows that SWAT can consistently simulate the streamflow of the East River with monthly Nash-Sutcliffe efficiencies of 0.93 for calibration and 0.90 for validation at the Boluo station. We analyzed the model simulations with calibrated parameters, presented the spatiotemporal distribution of the key hydrological components, and quantified their responses to different land uses. Watershed managers can use the results of this study to understand hydrological features and evaluate water resources of the East River in terms of sustainable development and effective management.

  15. Analyzing the water budget and hydrological characteristics and responses to land use in a monsoonal climate river basin in South China

    USGS Publications Warehouse

    Wu, Yiping; Chen, Ji

    2013-01-01

    Hydrological models have been increasingly used by hydrologists and water resource managers to understand natural processes and human activities that affect watersheds. In this study, we use the physically based model, Soil and Water Assessment Tool (SWAT), to investigate the hydrological processes in the East River Basin in South China, a coastal area dominated by monsoonal climate. The SWAT model was calibrated using 8-year (1973–1980) record of the daily streamflow at the basin outlet (Boluo station), and then validated using data collected during the subsequent 8 years (1981–1988). Statistical evaluation shows that SWAT can consistently simulate the streamflow of the East River with monthly Nash–Sutcliffe efficiencies of 0.93 for calibration and 0.90 for validation at the Boluo station. We analyzed the model simulations with calibrated parameters, presented the spatiotemporal distribution of the key hydrological components, and quantified their responses to different land uses. Watershed managers can use the results of this study to understand hydrological features and evaluate water resources of the East River in terms of sustainable development and effective management.

  16. The appearance of an oxygen-depleted condition on the Capitanian disphotic slope/basin in South China: Middle-Upper Permian stratigraphy at Chaotian in northern Sichuan

    NASA Astrophysics Data System (ADS)

    Saitoh, Masafumi; Isozaki, Yukio; Yao, Jianxin; Ji, Zhansheng; Ueno, Yuichiro; Yoshida, Naohiro

    2013-06-01

    The global environmental changes related to the end-Guadalupian (Permian) extinction have been recently studied in various shallow-marine sections in the world; however, no previous stratigraphic research focused on the sequence deposited in a relatively deep disphotic zone. In order to investigate the environmental changes in the disphotic zone during that interval, lithostratigraphy and secular changes in the sedimentary environment were analyzed for the ca. 150 m thick Guadalupian-Lopingian (Middle-Upper Permian) carbonates at Chaotian in northern Sichuan, South China. The upper Guadalupian Maokou Formation and the Lower Lopingian Wujiaping Formation are mostly composed of bioclastic limestone of a euphotic shelf facies and contain abundant shallow marine fossils, such as algae, corals, and fusulines. The topmost Maokou Formation (ca. 11 m thick) is unique in this section because it is composed of thinly bedded black mudstone/chert of a disphotic slope/basin facies with abundant radiolarians and ammonoids. The stratigraphic changes in litho- and bio-facies suggest a two-stepped transgression in the Capitanian followed by a great regression around the Guadalupian-Lopingian boundary (G-LB). Moreover, the stratigraphic changes in bioturbation, total organic carbon (TOC) content, and occurrence of framboidal pyrite suggest that the redox of the sedimentary environment at Chaotian changed drastically in accordance with newly clarified rapid sea-level fluctuations. In association with the Capitanian sea-level rise, the sedimentary environment shifted from an oxic shelf to an oxygen-depleted slope/basin, and again returned to an oxic shelf during the following great regression. The appearance of the oxygen-depleted condition on the Capitanian disphotic slope/basin in northern Sichuan is particularly important because it occurred clearly before the end-Guadalupian extinction event. It is also noteworthy that the oxygen-depleted seawater appeared for the first time on a

  17. The origin and evolution of a near-axis seamount in marginal basin: case study in the South China Sea

    NASA Astrophysics Data System (ADS)

    Yan, Q.; Shi, X.; Wang, L.; Liao, L.; Ren, J.

    2013-12-01

    Volcaniclastic rock on seamount is the product of subaqueous explosive volcanism. The finding of volcaniclastic rocks from the Daimao seamounts and some other seamounts suggests that the top of most seamounts in the South China Sea (SCS) once exceeded the pressure compensation level (PCL), and these rocks are products of subaqueous explosive volcanism. The major element compositional features of these volcaniclastic rocks reflect low-temperature seawater alteration have a significant role on whole rock compositions (by means of secondary altered minerals), but there shows a consistence in trace element compositions between whole rock samples and basaltic lava samples separated from whole rock samples. Trace element compositions, combined with Sr, Nd and Pb isotopic compositions, suggested that similar to alkali basalts from other seamounts in the SCS, all samples are of OIB-like features and Dupal Pb anomaly (an endogenous mantle component). The estimated mean subsidence rate for the Daimao seamount, combined with previous results for other two seamounts, suggested earlier subsidence rate of seamounts is obviously higher than calculated mean subsidence rate. This paper proposed a simplified model for the formation and evolution of the Daimao seamounts as follows. At about 14Ma, basic volcanic edifice framework of the Daimao seamount was formed by subaqueous explosive volcanism whose materials are originated from Hainan mantle plume. Subsequently under shallow-water environment, the seamount received coral-bearing carbonate deposits. Then, due to gravity isostatic compensation, the seamount begins to subside to the site more than 400m water depth at the velocity of 5-30mm/y after receiving a few amounts of carbonate deposits. Finally, the seamount subside to the present site at a slower rate and commences to receive Fe-Mn crust deposits.

  18. 3D seismic structure of the Zhenbei-Huangyan seamount chain in the East sub-basin of the South China Sea and its mechanism of formation

    NASA Astrophysics Data System (ADS)

    Zhao, M.; Wang, J.; Qiu, X.; Sibuet, J. C.; He, E.; Zhang, J.

    2015-12-01

    The post-spreading volcanic ridge (PSVR) is oriented approximately E-W in its western part called the Zhenbei-Huangyan seamount chain. Where is the extinct spreading ridge (ESR) of the East Sub-basin located? beneath the PSVR (Li et al., 2014)? Or intersecting with the PSVR by N055° orientation (Sibuet et al., submitted)? A three-dimensional Ocean Bottom Seismometer (OBS) survey covered both the central extinct spreading ridge and the Zhenbei-Huangyan seamount chain, the IODP Site U1431 (Li et al., 2014) being located just north of the chain. The results of this experiment will provide the essential information to understand the emplacement of the PSVR within the previously formed oceanic crust. The comprehensive seismic record sections of 39 OBSs are of high quality and show clear and reliable P-wave seismic phases, such as Pg, Pn and PmP. These seismic arrivals provide strong constrains for modeling the detailed three-dimensional velocity structure. We will show that the crust is oceanic on each side of the Zhenbei-Huangyan seamount chain, where is the location of the ESR and what is the genetic relationship between the magma chambers and the overlying Zhenbei-Huangyan seamount chain. We suggest that the large thickness of the upper crust is possibly due to volcanic extrusions and the thickened lower crust to magmatic underplating. Combining previous geochemical study of PSVR outcropping samples, the formation mechanism of the seamount chain might be explained by a buoyancy decompression melting mechanism (Castillo et al., 2010). This research was granted by the Natural Science Foundation of China (91028002, 91428204, 41176053). ReferencesSibuet J.-C., Yeh Y.-C. and Lee C.-S., 2015 submitted. Geodynamics of the South China Sea: A review with emphasis on solved and unsolved questions. Tectonophysics. Li, C. F., et al. 2014. Ages and magnetic structures of the South China Sea constrained by deep tow magnetic surveys and IODP Expedition 349. Geochemistry

  19. The eddy-mean flow interaction and the intrusion of western boundary current into the South China Sea type basin in an idealized model

    NASA Astrophysics Data System (ADS)

    Zhong, Linhao

    2016-04-01

    In this paper, an ideal model on the role of mesoscale eddies in the Kuroshio intruding into the South China Sea (SCS) is developed, which represents the northwestern Pacific and the SCS by two rectangle basins connected by a gap. In the case of only considering intrinsic ocean variability, a time-dependent western boundary current (WBC) driven by steady wind is modeled under both eddy-resolving and non-eddy-resolving resolutions. Almost all simulated WBC intrudes into the adjacent sea in the form of loop current with multiple-state transitions and eddy-shedding process, which has aperiodic variations on intraseasonal or interannual scales, determined by the eddy-induced WBC variation. For the parameters considered in this paper, the WBC intrusion exhibits a 30~90-day cycle in the presence of the subgrid-scale eddy forcing (SSEF), but a 300~500-day cycle in the absence of SSEF. Moreover, the roles of the resolved (grid-scale) and unresolved (subgrid-scale) eddies in the WBC intrusion are studied. It is found that the unresolved eddy-flow interaction strongly regulates the WBC intrusion through the PV forcing induced by shear flows and baroclinic processes. But the resolved eddy forcing, which is dominated by the eddy-eddy interaction solely through baroclinic processes, shows weak correlation to the WBC intrusion. The associated eddy-induced PV exchange between the two basins is mainly accomplished by isopycnal-thickness eddy fluxes, particularly by the cross-front PV fluxes due to the unresolved eddy. And the unresolved eddy-flow interaction, as well as resolved and unresolved eddy-eddy interactions, mainly governs the PV transport for the WBC intrusion.

  20. The Dependency of Probabilistic Tsunami Hazard Assessment on Magnitude Limits of Seismic Sources in the South China Sea and Adjoining Basins

    NASA Astrophysics Data System (ADS)

    Li, Hongwei; Yuan, Ye; Xu, Zhiguo; Wang, Zongchen; Wang, Juncheng; Wang, Peitao; Gao, Yi; Hou, Jingming; Shan, Di

    2016-08-01

    The South China Sea (SCS) and its adjacent small basins including Sulu Sea and Celebes Sea are commonly identified as tsunami-prone region by its historical records on seismicity and tsunamis. However, quantification of tsunami hazard in the SCS region remained an intractable issue due to highly complex tectonic setting and multiple seismic sources within and surrounding this area. Probabilistic Tsunami Hazard Assessment (PTHA) is performed in the present study to evaluate tsunami hazard in the SCS region based on a brief review on seismological and tsunami records. 5 regional and local potential tsunami sources are tentatively identified, and earthquake catalogs are generated using Monte Carlo simulation following the Tapered Gutenberg-Richter relationship for each zone. Considering a lack of consensus on magnitude upper bound on each seismic source, as well as its critical role in PTHA, the major concern of the present study is to define the upper and lower limits of tsunami hazard in the SCS region comprehensively by adopting different corner magnitudes that could be derived by multiple principles and approaches, including TGR regression of historical catalog, fault-length scaling, tectonic and seismic moment balance, and repetition of historical largest event. The results show that tsunami hazard in the SCS and adjoining basins is subject to large variations when adopting different corner magnitudes, with the upper bounds 2-6 times of the lower. The probabilistic tsunami hazard maps for specified return periods reveal much higher threat from Cotabato Trench and Sulawesi Trench in the Celebes Sea, whereas tsunami hazard received by the coasts of the SCS and Sulu Sea is relatively moderate, yet non-negligible. By combining empirical method with numerical study of historical tsunami events, the present PTHA results are tentatively validated. The correspondence lends confidence to our study. Considering the proximity of major sources to population-laden cities

  1. Basin-wide distribution of phytoplankton lipids in the South China Sea during intermonsoon seasons: Influence by nutrient and physical dynamics

    NASA Astrophysics Data System (ADS)

    Dong, Liang; Li, Li; Li, Qianyu; Liu, Jie; Chen, Yuxing; He, Juan; Wang, Hui

    2015-12-01

    Four algal biomarkers, brassicasterol, C30-diol/keto-ol, dinosterol and C37-alkenone, representing diatoms, estigmatophytes, dinoflagellates and coccolithophorids, respectively, were detected in samples collected during two South China Sea cruises to study the modern phytoplankton community structure in the region. For the first time, the basin-wide distribution of these phytoplankton algal biomarkers in the sea surface water during two intermonsoon seasons (spring 2010 and autumn 2011) is documented and charted. Generally, the abundance of the biomass is higher in spring than autumn, with high productivity mostly in the regions of Pearl River estuary, off Palawan and around the Luzon Strait, showing the abundance order: diatoms>estigmatophytes>dinoflagellates>coccolithophorids. We run both redundancy analysis (RDA) and SPSS correlation analysis to interpret the relationship between individual groups and environmental variables. The results indicate that temperature and salinity play a dominant role in controlling the distribution of phytoplankton in these intermonsoon seasons, followed by nitrate playing a secondary role. Our biomarker survey provides important reference data for interpreting paleo-productivity in the geological records in the SCS.

  2. Driving factors for runoff decline in the Upper Hanjiang basin, a major water source for the South-to-North Water Diversion Project in China

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Yang, D.; Xu, X.

    2015-05-01

    With dramatic changes in climate and land-cover patterns around the world, it is of great significance to evaluate the corresponding influence on runoff change as water resources have become a strategic resource. We analysed the runoff change driven by landscape change and climate variation in Hanjiang River basin, which is the water source area of the central route of the South-to-North Water Diversion Project in China. Results show that the runoff decreased greatly from 1960 to 2012 in all the six selected sub-catchments. Attribution analysis results show that reduction of precipitation contributed to the catchment runoff decrease by 39.5-64.9% and landscape change, represented by increase of the parameter in the mathematical Budyko function contributed to the runoff decrease by 34.4-63.3%, while potential evapotranspiration change had a slightly negative contribution. In addition, the contribution is spatially variable from downstream to upstream. We conclude with a qualitative description about how water availability changes under changing landscape and climate conditions, and focus on the impact of vegetation cover change.

  3. Abnormal organic-matter maturation in the Yinggehai Basin, South China Sea: Implications for hydrocarbon expulsion and fluid migration from overpressured systems

    USGS Publications Warehouse

    Hao, F.; Li, S.; Dong, W.; Hu, Z.; Huang, B.

    1998-01-01

    Three superimposed pressure systems are present in the Yinggehai Basin, South China Sea. A number of commercial, thermogenic gas accumulations have been found in an area in which shale diapirs occur. Because the reservoir intervals are shallow and very young, they must have filled with gas rapidly. The thick (up to 17 km) Tertiary and Quaternary sedimentary succession is dominated by shales, and is not disrupted by major faulting in the study area, a factor which seems to have had an important effect on both hydrocarbon generation and fluid migration. Organic-matter maturation in the deepest, most overpressured compartment has been significantly retarded as a result of the combined effects of excess pressure, the presence of large volumes of water, and the retention of generated hydrocarbons. This retardation is indicated by both kerogen-related parameters (vitrinite reflectance and Rock-Eval T(max)); and also by parameters based on the analysis of soluble organic matter (such as the C15+ hydrocarbon content, and the concentration of isoprenoid hydrocarbons relative to adjacent normal alkanes). In contrast to this, organic-matter maturation in shallow, normally-pressured strata in the diapiric area has been enhanced by hydrothermal fluid flow, which is clearly not topography-driven in origin. As a result, the hydrocarbon generation 'window' in the basin is considerably wider than could be expected from traditional geochemical modelling. These two unusual and contrasting anomalies in organic-matter maturation, together with other lines of evidence, suggest that there was a closed fluid system in the overpressured compartment until shale diapirs developed. The diapirs developed as a result of the intense overpressuring, and their growth was triggered by regional extensional stresses. They served as conduits through which fluids (both water and hydrocarbons) retained in the closed system could rapidly migrate. Fluid migration led to the modification of the thermal

  4. Structure and sediment budget of Yinggehai-Song Hong basin, South China Sea: Implications for Cenozoic tectonics and river basin reorganization in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Lei, Chao; Ren, Jianye; Sternai, Pietro; Fox, Matthew; Willett, Sean; Xie, Xinong; Clift, Peter D.; Liao, Jihua; Wang, Zhengfeng

    2015-08-01

    The temporal link between offshore stratigraphy and onshore topography is of key importance for understanding the long-term surface evolution of continental margins. Here we present a grid of regional, high-quality reflection seismic and well data to characterize the basin structure. We identify fast subsidence of the basin basement and a lack of brittle faulting of the offshore Red River fault in the Yinggehai-Song Hong basin since 5.5 Ma, despite dextral strike-slip movement on the onshore Red River fault. We calculate the upper-crustal, whole-crustal, and whole-lithospheric stretching factors for the Yinggehai-Song Hong basin, which show that the overall extension observed in the upper crust is substantially less than that observed for the whole crust or whole lithosphere. We suggest that fast basement subsidence after 5.5 Ma may arise from crustal to lithospheric stretching by the regional dynamic lower crustal/mantle flow originated by collision between India-Eurasia and Indian oceanic subduction below the Eurasian margin. In addition, we present a basin wide sediment budget in the Yinggehai-Song Hong basin to reconstruct the sedimentary flux from the Red River drainage constrained by high-resolution age and seismic stratigraphic data. The sediment accumulation rates show a sharp increase at 5.5 Ma, which suggests enhanced onshore erosion rates despite a slowing of tectonic processes. This high sediment supply filled the accommodation space produced by the fast subsidence since 5.5 Ma. Our data further highlight two prominent sharp decreases of the sediment accumulation at 23.3 Ma and 12.5 Ma, which could reflect a loss of drainage area following headwater capture from the Paleo-Red River. However, the low accumulation rate at 12.5 Ma also correlates with drier and therefore less erosive climatic conditions.

  5. Crustal structure across the post-spreading magmatic ridge of the East Sub-basin in the South China Sea: Tectonic significance

    NASA Astrophysics Data System (ADS)

    He, Enyuan; Zhao, Minghui; Qiu, Xuelin; Sibuet, Jean-Claude; Wang, Jian; Zhang, Jiazheng

    2016-05-01

    The 140-km wide last phase of opening of the South China Sea (SCS) corresponds to a N145° direction of spreading with rift features identified on swath bathymetric data trending N055° (Sibuet et al., 2016). These N055° seafloor spreading features of the East Sub-basin are cut across by a post-spreading volcanic ridge oriented approximately E-W in its western part (Zhenbei-Huangyan seamounts chain). The knowledge of the deep crustal structure beneath this volcanic ridge is essential to elucidate not only the formation and tectonic evolution of the SCS, but also the mechanism of emplacement of the post-spreading magmatism. We use air-gun shots recorded by ocean bottom seismometers to image the deep crustal structure along the N-S oriented G8G0 seismic profile, which is perpendicular to the Zhenbei-Huangyan seamounts chain but located in between the Zhenbei and Huangyan seamounts, where topographic changes are minimum. The velocity structure presents obvious lateral variations. The crust north and south of the Zhenbei-Huangyan seamounts chain is ca. 4-6 km in thickness and velocities are largely comparable with those of normal oceanic crust of Atlantic type. To the south, the Jixiang seamount with a 7.2-km thick crust, seems to be a tiny post-spreading volcanic seamount intruded along the former extinct spreading ridge axis. In the central part, a 1.5-km thick low velocity zone (3.3-3.7 km/s) in the uppermost crust is explained by the presence of extrusive rocks intercalated with thin sedimentary layers as those drilled at IODP Site U1431. Both the Jixiang seamount and the Zhenbei-Huangyan seamounts chain started to form by the intrusion of decompressive melt resulting from the N-S post-spreading phase of extension and intruded through the already formed oceanic crust. The Jixiang seamount probably formed before the emplacement of the E-W post-spreading seamounts chain.

  6. Unusual distribution of triterpane and sterane terrestrial biomarkers in yacheng condensates from Ying-Qiong basins, South China sea

    NASA Astrophysics Data System (ADS)

    Zhou, Yi; Sheng, Guo-Ying; Fu, Jia-Mo; Geng, An-Song; Chen, Jun-Heng; Zhang, Qi-Ming; Pan, Xian-Zhuang; Huang, Bao-Jia

    2002-06-01

    The condensates from the Yacheng Gas Field, Ying-Qiong Basins, have unusual chemical characteristics, with distribution dominated by terpanes and steranes derived from higher-plants. Pr/Ph ratios (6 11) are very high. Drimane, cadinanes and homocadinanes exist in high concentration. Anomalously abundant 18α(H)-oleanane and remarkably abundant bicadinanes are present in Yacheng condensates, while 17α(H)-hopanes are in extremely low concentration. Taraxastane and significantly abundant 17α(H)-diahopanes occur in the condensates. In addition, a number of C29 and C30 unknown pentacyclic triterpanes were monitored in the condensates, some of which are abundant. The unknown compounds may be terrestrial biomarkers or their occurrence may suggest a sub-oxic (dyacrobic) clay-rich depositional environment. C29 homologues are relatively predominant in regular and rearranged steranes. The concentration of diasteranes is markedly higher than that of regular steranes. The characteristics of Yacheng condensates are indicative of terrestrial source input. Based on condensate-condensate and condensate-rock correlations, combined with results of studies on sedimentary facies. Yacheng condensates may be sourced from Yacheng and Lingshui Formations in the Qiongdongnan Basin. The maturity of Yacheng condensate is relatively high, at late oil window stage (corresponding to 0.9% 1.3% R0), based on sterane and terpane maturity parameters.

  7. A comprehensive assessment of agricultural intensification scenarios for the Dongting Lake basin in south-central China in 2030.

    PubMed

    Yin, Guanyi; Liu, Liming; Chang, Xiao; Sun, Jin

    2016-07-01

    To explore the future of the material demand, pollutant emission, production, and arable land area surrounding the Dongting Lake basin, and to find a potential solution for agricultural development, this study assumes the following four agriculture intensification scenarios: the natural development scenario (ND), the production development scenario (PD), the moderate intensification scenario (MI), and the local resilience scenario (LR). The scenarios focus on different developmental patterns (natural development, short-term production growth, long-term sustainability, or self-sufficiency).The result shows to satisfy the food demand in 2030, and the production of crop and meat will be 26.96, 30.25, 28.05, and 16.27 × 10(6) t in ND, PD, MI, and LR, respectively; more than 1.78 × 10(6) ha of arable land is needed. Compared with the year 2012, the material input and pollutant output will increase by a maximum of 18.32 and 122.31 %, respectively. By classifying the environmental risk into four categories-greenhouse gas emission, air pollution, eutrophication, and ecotoxicity-the composite environmental risk index (CER) is calculated. The CER in PD was the highest, followed by that in ND, LR, and MI. Due to the production allocation within the 35 cities and counties, the spatial distribution of CER is more homogenous in PD and MI than in ND. The analysis of the scenarios reveals that through technological improvement and spatial allocation of agricultural production, scenario MI could be a potential direction for the government to design a sustainable agricultural-environmental system. PMID:27040549

  8. New U/Pb ages from Nanpanjiang Basin (South China): implications for the age and definition of the Early-Middle Triassic boundary

    NASA Astrophysics Data System (ADS)

    Ovtcharova, Maria; Bucher, Hugo; Goudemand, Nicolas; Schaltegger, Urs; Brayard, Armand; Galfetti, Thomas

    2010-05-01

    Understanding the patterns and rates of the biotic recovery following the end-Permian extinction requires detailed calibration of both biotic and environmental fluctuations by precise and accurate U-Pb age determinations on zircon from volcanic ash beds within biostratigraphically well dated marine sedimentary sections. Recent analytical developments in U-Pb dating include chemical abrasion pre-treatment of zircon as well as the use of the well calibrated 202Pb-205Pb-233U-235U EARTHTIME tracer solution, leading to <0.1% analytical uncertainties and external reproducibilities. Utilizing these analytical techniques we report new data from the Jinya area in the Nanpanjiang Basin (South China) and compare them to radioisotopic and biochronologic data from Guandao in the same basin (Lehrmann et al. 2006, 2007) The so-called "green-bean rock" (GBR) is an interval rich in volcanic ash beds which is customarily used as a mapping unit to separate Lower from Middle Triassic marine rocks in the Nanpanjiang Basin (Lehrmann et al. 2006). In Guandao, the first occurrence (FO) of the conodont Chiosella timorensis is used to define the base of the middle Triassic. The position of this FO in Guandao is somewhat unstable and underwent a downward shift of 2.6 m between the two consecutive reports of Lehrmann et al. (2006, 2007). The new position of the FO, still bracketed by the same ash layers PGD2 and PGD3 led to a minor readjustment of its linearly interpolated age to 247.24 Ma (Lehrmann et al. 2007). In the basinal Luolou Fm., the GBR amounts to a ca. 3m thick series of composite, laterally transported ashes as indicated by internal sedimentary structures. Ammonoids bracketing the GBR in the Luolou Fm. invariably indicate a late Early Triassic age (Haugi Zone of the Spathian substage). A 13 m thick section straddling the transition between the Luolou Fm. and the overlying Baifeng Fm. was sampled along a new road cut at Monggan (3 km NNW of Jinya). In this section, the 3 m thick

  9. China, JNOC start exploration in Tarim basin

    SciTech Connect

    Not Available

    1992-06-15

    This paper reports that a joint venture of China National Oil and Natural Gas Corp and Japan National Oil Corp (JNOC) has begun exploration in Northwest China's remote Tarim basin in Xinjiang Uygur Autonomous Region. That marks the first time China has allowed a foreign oil company to participate in exploration of the highly prospective basin. China pins much of its hope for the future on the Tarim basin as production declines from its older, mainstay fields in the east and offshore results have proved largely disappointing. The Chinese-Japanese combine began operations in the southwest part of the 560,000 sq km basin. The 200 member exploration team plans to complete a seismic survey covering 3,500 line km in the Kashi and Yecheng areas during the next 4 1/2 years. The survey follows a feasibility study that began last October covering 30,000 sq km in the basin.

  10. Geochemical constraints on the origin of Late Mesozoic andesites from the Ningwu basin in the Middle-Lower Yangtze Valley, South China

    NASA Astrophysics Data System (ADS)

    Chen, Long; Zheng, Yong-Fei; Zhao, Zi-Fu

    2016-06-01

    An integrated study of zircon U-Pb ages, Hf-O isotopes, whole-rock major-trace elements and Sr-Nd-Hf isotopes was carried out for Mesozoic andesites from the Ningwu basin in the Middle-Lower Yangtze Valley, South China. The results not only provide insights into the origin of anorogenic magmatism in the Middle-Lower Yangtze Valley but also shed light on the petrogenesis of continental arc andesites in general. The Ningwu andesites are mainly composed of trachyandesite and trachyte, with subordinate of basaltic trachy-andesites. They exhibit variable and low MgO contents of 0.1-3.7 wt.% and low Mg# values of 1.6-51.2, high K2O contents of 2.0-9.9 wt.%. They are characterized by arc-like trace element distribution patterns, with significant enrichment in LILE and LREE but depletion in HFSE. Furthermore, these rocks exhibit relatively enriched whole-rock Sr-Nd-Hf-Pb isotope compositions, with initial 87Sr/86Sr ratios of 0.7050-0.7082, negative εNd(t) values of - 8.1 to - 1.8, and negative εHf(t) values of - 6.7 to 0.4. Zircon U-Pb dating yields consistent ages of 128 ± 2 to 133 ± 2 Ma for magma emplacement through volcanic eruption. The zircon exhibits slightly high δ18O values of 5.7-7.8‰ and variable εHf(t) values of - 5.8 to 0.7. All andesites can be categorized into two groups in view of their distinct geochemical compositions, an integrated interpretation of which allows deciphering of their petrogenesis. Group I andesite was produced by a relatively larger extent of partial melting of a more fertile and enriched mantle source that contains a greater amount of phlogopite, whereas Group II andesite was generated by a relatively smaller extent of partial melting of a less fertile and enriched mantle source that contains a less amount of phlogopite. In either case, these two mantle sources are less ultramafic in lithochemistry than normal mantle peridotite due to its reaction with metasediment-derived hydrous felsic melts. This metasomatism would take place

  11. Climatic impacts of the Middle Route of the South-to-North Water Transfer Project over the Haihe River basin in North China simulated by a regional climate model

    NASA Astrophysics Data System (ADS)

    Zou, Jing; Zhan, Chesheng; Xie, Zhenghui; Qin, Peihua; Jiang, Shanshan

    2016-08-01

    The Middle Route of the South-to-North Water Transfer Project (MSWTP) was constructed to ease the water crisis over the North China Plain. In this study, we incorporated a water transfer scheme into the regional climate model RegCM4 and investigated the climatic impacts of the MSWTP over the Haihe River Basin in North China. Four 10 year simulation tests were conducted from 2001 to 2010 where different volumes of water were transferred. The results demonstrated that before the MSWTP was conducted the original groundwater exploitation and consumption over the Haihe River Basin led to wetting and cooling at the land surface with rapidly falling groundwater depth. The extra water input from the MSWTP slightly enhanced the wetting and cooling effects over the basin, as well as reduced the falling rate in the groundwater depth along the conveyance line. However, the weak climatic effects of the MSWTP were limited at a local scale and had no obvious interannual trends, because the transfer volume of the MSWTP was far lower than the total demand which has been conventionally satisfied through local water exploitation. In terms of seasonal variations, the greatest changes due to the MSWTP occurred in the summer for precipitation and soil moisture and in the spring for energy-related variables (heat fluxes and 2 m air temperature).

  12. South Fork Holston River basin 1988 biomonitoring

    SciTech Connect

    Saylor, C.F.; Ahlstedt, S.A.

    1990-06-01

    There is concern over the effects of shifts in land use use practices on the aquatic fauna of streams in the South Fork Holston River basin in northwestern North Carolina and southwestern Virginia. Trout reproduction has noticeably declined in the Watauga River subbasin. The Watauga River and Elk River subbasins have been subjected to commercial and resort development. The Middle fork Holston River and the upper South Fork Holston River subbasins have been affected by agricultural and mining activities, respectively (Cox, 1986). To aid reclamation and management of the South Fork Holston basin, Tennessee Valley Authority (TVA) biologists conducted biomonitoring--including index of biotic integrity and macroinvertebrate sampling--on the Middle Fork Holston, South Fork Holston, Watauga, and Elk Rivers to assess cumulative impairment related to changes in habitat and pollutant loading in these subbasins. Biomonitoring can detect environmental degradation, help document problem areas, and assist in development of strategies for managing water quality. This report discusses the methods and materials and results of the biomonitoring of South Fork Holston River Basin. 13 refs., 5 figs., 12 tabs.

  13. Hydrocarbon accumulations in the Tarim basin, China

    SciTech Connect

    Li Desheng; Liang Digang; Jia Chengzao; Wang Gang

    1996-10-01

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

  14. Fluxes of clay minerals in the South China Sea

    NASA Astrophysics Data System (ADS)

    Schroeder, Annette; Wiesner, Martin G.; Liu, Zhifei

    2015-11-01

    In order to assess dominant settling processes that change the composition of the detrital clay fraction during transport from neighboring estuaries to a deep sea basin, we studied relative clay mineral abundances and absolute clay mineral fluxes of clay-sized sinking particulate matter collected by eight sediment trap systems deployed from shallow to deep water depth in the South China Sea. This is the first basin-wide study on recent sedimentation processes in the western Pacific marginal seas. Annual averages of relative clay mineral abundances at the shallow traps are temporally more variable and regionally more diverse, resembling those of surrounding drainage basins. In contrast, higher fluxes of material reach the deeper traps. Their characteristics trend temporally and spatially towards uniformity and are enriched with smectite in the entire deep basin. Sinking particulate matter that reaches the shallow traps spends less time in pelagic transport and is affected by monsoonal current reversals. The enrichment in smectite in the deeper traps is a result of longer duration in transport at low velocities, which may increase the effect of differential settling during transport. The trend is caused by lateral advection driven by the cyclonic deep circulation, and this is considered as the main transport process in the northern and central deep basin. The high fluxes in the south-western deep basin could be the result of laterally advected re-suspended sediments from the neighboring shelves. The effects on the composition of the detrital clay fraction caused by oceanographic control, which indirectly include those by differential settling, mask the climatic signal from surrounding drainage basins in the deep basin sediments. This strongly affects the interpretation of the clay mineralogical record in sediments deposited under recent conditions in the South China Sea deep basin.

  15. Geotectonic regionalization and evolution of East China Sea and northern South China Sea

    SciTech Connect

    Li, Y.

    1986-07-01

    An analysis of geologic, geophysical, aeromagnetic, and drilling data suggests the marine basins on both sides of the fault along the western border of the East China Sea and the Beiwei-Shenhu fault in the South China Sea are different geotectonically, with respect to the nature of basement and the evolution of the Cenozoic sedimentary basins. Northwest of the faults, basement underlying these marine basins is formed of an extension to the Caledonian South China tectonic belt, where the Late Cretaceous to early Tertiary sedimentary basins is characterized by continental rifting. During the Neogene, the sedimentary basins evolved through continued bulk subsidence. In the shelf basin of the East China Sea, southeast of the faults, the Paleogene to lower Miocene sequence is characterized by geosynclinal sedimentation. During the Neogene to early Pleistocene orogeny, upper Miocene to Pilocene deposits were compressed into a series of bar-shaped folds, accompanied by reverse faulting. This series is apparently a marine northeastern extension of the Himalayan tectonic foldbelt west of the meridional valley of Taiwan. The tectonic foldbelt extends northeast to the Goshimg Islands in the southwest Sea of Japan, and Tsushima Island in the Korea Strait. Coastal mountains in eastern Taiwan are an independent tectonic element adjacent to the western Pacific basin. Geologic and geophysical data suggest this tectonic element consists of remnant Neogene crustal fragments of oceanic type. The meridional valley in eastern Taiwan, which separates this element from the Himalayan Taiwan tectonic foldbelt of continental crust, is an A-shaped subduction belt, downthrust beneath the Pacific plate during the Neogene. This belt extends to the south, and may connect to the presently easterly downthrusting Manila Trench. The buoyancy of the continental crust in Taiwan is obstructing the process of subduction downthrusting in the north.

  16. Geological evolution history of petroliferous basins on continental shelf of China

    SciTech Connect

    Lidesheng

    1983-03-01

    Coastlines of China are about 18,000 km (11,118 mi) in length, and their aggregate continental shelf area within 200 m (656 ft) seawater depth is more than one million km/sup 2/ (386,102 mi/sup 2/). Recent geophysical exploration work and numerous petroleum drilling records are available and give a general understanding of the geological evolution history of these petroliferous basins. There are two tectonic types of basins distributed on the continental shelf areas: the tectonic types of Bohai Gulf, South Yellow Sea, and Beibu Gulf basins are the intraplate polyphase rifting-depression basins; the East China Sea, Pearl River mouth, and Yingge Sea basin are the epicontinental rifting-depression basins. They are believed to be extensional in origin. Because of the severe convergence of Indian plate with Eurasia plate, there has been produced NNE-spreading movement of the South China Sea basin, which permits two triple junctions on its northern margins. The extension mechanism could be derived from the rising of an upper mantle plume to produce two NNE weak fracturing zones, resulting in a series of intraplate and epicontinental rifting-depression basins. The depositional models and sea-level variations of these basins are interpreted from the drilling records and seismic profiles. They can be explained by the tectono-eustatic changes in sea level and Cenozoic climate changes of China.

  17. Basin analysis of South Mozambique graben

    SciTech Connect

    Iliffe, J.; Lerche, I.; De Buyl, M.

    1987-05-01

    Basin analysis of the South Mozambique graben between latitudes 25/sup 0/ and 26/sup 0/ and longitudes 34/sup 0/ and 35/sup 0/ demonstrates how modeling techniques may help to assess the oil potential of a speculative basin with only minimal seismic data. Two-dimensional restoration of the seismic profiles, using a backstripping and decompaction program on pseudowells linked with structural reconstruction, assesses the rift's two-phase extensional history. Since no well or thermal indicator data exist within the basin, the thermal history had to be derived from extensional models. The best fit of observed subsidence curves and those predicted by the models results in values of lithospheric extension (gamma). The disagreement in observed and theoretical basement subsidence curves was minimized by taking a range of gamma for each model for each well. These extension factors were then used in each model's equations for paleoheat flux to derive the heat-flow histories. (It is noted that a systematic basinwide variance of gamma occurs.) The heat-flux histories were then used with a one-dimensional fluid flow/compaction model to calculate TTI values and oil windows. A Tissot generation model was applied to each formation in every well for kerogen Types I, II, and III. The results were contoured across the basin to assess possible oil- and gas-prone formations. The extensional, burial, and thermal histories are integrated into an overall basin development picture and provide an oil and gas provenance model. Thus they estimate the basinwide hydrocarbon potential and also gain insight into the additional data necessary to significantly decrease the uncertainty.

  18. Stable Continental Region Earthquakes in South China

    NASA Astrophysics Data System (ADS)

    Liu, L.

    This paper reviews some remarkable characteristics of earthquakes in a Stable Continental Region (SCR) of the South China Block (SCB). The kernel of the SCB is the Yangtze platform solidified in late Proterozoic time, with continental growth to the southeast by a series of fold belts in Paleozoic time. The facts that the deviatoric stress is low, the orientations of the major tectonic features in the SCB are substantially normal to the maximum horizontal principal stress, and a relatively uniform crust, seem to be the major reasons for lack of significant seismicity in most regions of the SCB. Earthquakes in this region are mainly associated with three seismic zones: (1) the Southeast China Coast seismic zone related to Guangdong-Fujian coastal folding belt (associated with Eurasia-Philippine Sea plate collision); (2) the Southern Yellow Sea seismic zone associated with continental shelf rifts and basins; and (3) the Downstream Yangtze River seismic zone spatially coinciding with Tertiary rifts and basin development. All three seismic zones are close to one or two major economic and population centers in the SCB so that they pose significant seismic hazards. Earthquake focal mechanisms in the SCB are consistent with strike-slip to normal faulting stress regimes. Because of the global and national economic significance of the SCB and its dense population, the seismic hazard of the region is of outstanding importance. Comparing the SCB with another less developed region, a pending earthquake with the same size and tectonic setting would cause substantially more severe social and economic losses in the SCB. This paper also compiles an inventory of historic moderate to great earthquakes in the SCB; most of the data are not widely available in English literature.

  19. Plate evolution and petroliferous basins of China

    SciTech Connect

    Wu Shou Cheng; Zhang Wen Zhao

    1989-03-01

    The writers have compiled a group of paleogeographic and paleostructural maps of tectonic plates and sedimentary basins of China based on paleomagnetic, paleoclimatic, and paleoecologic data. The paleoenvironments and regional conditions that instigated the origin of petroleum in the superbasins have been reconstructed.

  20. Lithospheric structure of South China Sea from surface wave tomography

    NASA Astrophysics Data System (ADS)

    Chen, L.; Xue, M.; Le, K.; Yang, T.

    2011-12-01

    The South China Sea is one of the marginal seas of the West Pacific where the Eurasian Plate, Philippine Sea Plate, Pacific Plate and Indo-Australian Plate interact. In this study we give a 3D shear wave velocity structure of South China Sea using surface wave tomographic methods. We use earthquakes distributed on the periphery of the South China Sea and collect the earthquake data from 48 stations (IRIS stations, CDSN stations and four stations deployed in Vietnam by Tongji University) with rays up to ~ 3000. We first calculate the group velocity dispersion curves of fundamental mode for Rayleigh waves with periods from 14 sec to 130 sec using the multiple filter technique. After getting the dispersion curve between each station-to-source pair, we conduct an inversion to get group velocity at each grid point in the rectangular region of 14° s - 34° N and 86° E - 134° E with different grid spacing of 2° × 2° and 1° × 1°. This process is done by the fast marching method as the forward step and then subspace inversion step followed. When we get the group velocity of each grid point for corresponding periods, we can extract a dispersion curve for that point. Through the surface wave inversion which uses Knopoff's calculation method for layered medium as the forward step and the damped least square method as the inversion step followed, we can get an iterative model which carries the information of shear wave velocity and layer depth for each grid point. Finally we put all the shear wave velocity structures of all points together to obtain the three-dimensional shear wave structures. With checkboard tests indicating good resolution, we find that higher group velocities persistently show up in South China Sea Basin, West Philippine Sea Basin, and Celebes Sea Basin from periods of 20 sec to 60 sec, which reflect structures down to 20 - 60 km deep. Similar high shear velocity features also show up in depth slices from 30 km to 60 km. These high shear velocity

  1. Improved correction method for using passive air samplers to assess the distribution of PCNs in the Dongjiang River basin of the Pearl River Delta, South China

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, Qilu; Xu, Yue; Luo, Chunling; Liu, Xiang; Li, Jun; Zhang, Gan

    2012-07-01

    An improved correction method was established using passive air samplers to assess the distributions of polychlorinated naphthalenes (PCNs) in the eastern Pearl River Delta, South China. This method was based on a joint correction that used the active air sampling rate and the addition of depuration compounds. As a correction factor, the depuration compounds' properties do not need to be similar to the target compounds. The total PCN air concentrations ranged from 6.4 to 832, with an average of 148 ± 201 pg m-3 in the study area, while the TEQ of the PCNs ranged from 1.2 × 10-4 to 2.6 × 10-2 pg m-3. High concentrations of PCNs were mostly observed in the highly industrialized areas. The PCN air levels were remarkably increased in winter compared with summer. Tri-CNs was the most dominant homologue group, while CN 24 was the most dominant congener. The high proportion of combustion-related PCNs suggests that the contribution of combustion sources to the PCN air burden has been significant recently in comparison with historical emissions.

  2. Assessing environmental risks for high intensity agriculture using the material flow analysis method--a case study of the Dongting Lake basin in South Central China.

    PubMed

    Yin, Guanyi; Liu, Liming; Yuan, Chengcheng

    2015-07-01

    This study primarily examined the assessment of environmental risk in high intensity agricultural areas. Dongting Lake basin was taken as a case study, which is one of the major grain producing areas in China. Using data obtained from 1989 to 2012, we applied Material Flow Analysis (MFA) to show the material consumption, pollutant output and production storage in the agricultural-environmental system and assessed the environmental risk index on the basis of the MFA results. The results predicted that the status of the environmental quality of the Dongting Lake area is unsatisfactory for the foreseeable future. The direct material input (DMI) declined by 13.9%, the domestic processed output (DPO) increased by 28.21%, the intensity of material consumption (IMC) decreased by 36.7%, the intensity of material discharge (IMD) increased by 10%, the material productivity (MP) increased by 27 times, the environmental efficiency (EE) increased by 15.31 times, and the material storage (PAS) increased by 0.23%. The DMI and DPO was higher at rural places on the edge of cities, whereas the risk of urban agriculture has arisen due to the higher increasing rate of DMI and DPO in cities compared with the counties. The composite environmental risk index increased from 0.33 to 0.96, indicating that the total environmental risk changed gradually but seriously during the 24 years assessed. The driving factors that affect environmental risk in high intensity agriculture can be divided into five classes: social, economic, human, natural and disruptive incidents. This study discussed a number of effective measures for protecting the environment while ensuring food production yields. Additional research in other areas and certain improvements of this method in future studies may be necessary to develop a more effective method of managing and controlling agricultural-environmental interactions.

  3. Geology, prospects in Orange basin offshore western South Africa

    SciTech Connect

    Muntingh, A. Ltd., Parow )

    1993-01-25

    With the fast changing political situation in South Africa it has become possible for Soekor (Pty.) Ltd. To invite international companies to participate in oil and gas exploration in the South African part of the Orange basin. This paper reports on the Orange basin, which comprises a 130,000 sq km area off western South Africa that extends northwards into Namibia, represents a large frontier basin with known hydrocarbon accumulations and the potential for giant fields. Comprehensive seismic coverage and a recent deep-water seismic survey in the Orange basin indicate exciting opportunities in the form of shallow and deep-water plays.

  4. Late compressional features, East China Sea Shelf Basin

    SciTech Connect

    Cunningham, A.E.; Prebish, M.R.; Eisenstadt, G. ); Norris, J.W.; Letsch, D.K. )

    1994-07-01

    Many anticlinal folds observed in the East China Sea Shelf Basin are interpreted to result from a change in regional stress from tensional to compressional. This compression is interpreted to have occurred during the late Eocene to Oligocene Yuquan movement. These features were observed most frequently south of the Mingyuefeng 1 well within China's recently offered Fourth Round Acreage. Many of these structures are interpreted to be related to reverse and strike-slip motion along reactivated, Late Cretaceous to late Eocene, synrift, normal faults. An early to middle Miocene regional unconformity truncates the crest of most anticlinal features, and does not appear to be involved in the folding episode. Late Eocene to Oligocene compressional highs present attractive structural targets in the East China Sea Shelf Basin. The deformed sedimentary section thickens toward the rift-basin boundary faults, suggesting synrift sedimentation. Consequently, there is no thinning of the synrift section across the crest of the structural highs formed by postrift compression. The timing of these compressional structural highs, however, must be compared with the hydrocarbon generation and migration history from source rocks in adjacent half grabens to properly assess accumulation potential.

  5. South Platte River Basin - Colorado, Nebraska, and Wyoming

    USGS Publications Warehouse

    Dennehy, Keuin F.; Litke, David W.; Tate, Cathy M.; Heiny, Janet S.

    1993-01-01

    The South Platte River Basin was one of 20 study units selected in 1991 for investigation under the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) program. One of the initial tasks undertaken by the study unit team was to review the environmental setting of the basin and assemble ancillary data on natural and anthropogenic factors in the basin. The physical, chemical, and biological quality of the water in the South Platte River Basin is explicitly tied to its environmental setting. The resulting water quality is the product of the natural conditions and human factors that make up the environmental setting of the basin.

  6. Tectonic History and Modelling of South Caspian Basin

    NASA Astrophysics Data System (ADS)

    Korotaev, M.; Nikishin, A.; Ershov, A.; Brunet, M.-F.

    South Caspian Basin is situated to the east from Caucasus mountains, to the north from Alborz mountain and to the west from Turkmenia. Basin is underlyed by oceanic crust and has extremely high thickness of sediments - up to 22 km. Generally, sedi- ments of South Caspian are divided in 9 complexes (by seismic data): from Jurassic to Quaternary, mostly terrigenous sediments. Modern stress fields obtained from struc- tural data, earthquakes data and GPS data shows compressional environments in South Caspian Region. We propose that the South Caspian Basin was opened in Callovian- Late Jurassic. Callovian-Late Jurassic rapid subsidence event is well documented for the Pre-Caucasus area. We can conclude that a large back-arc deep water basin with very thinned to local oceanic crust originated during Callovian-Late Jurassic which in- cluded Great Caucasus Trough, South Caspian Basin and Kopet-Dagh Basin. It could be recognised the following main stages of the basin history: Callovian-Late Jurassic - that main rifting and crustal extension epoch; Cretaceous-Eocene - gentle thermal sub- sidence affected by stress events; Oligocene-Miocene - rapid subsidence with domi- nant clay deposition within the basin; Pliocene-Quaternary - unusual rapid subsidence of the South Caspian Basin coincided with mountain uplift of the Great Caucasus, Kopet-Dagh and Alborz. We made a backstripping reconstruction along the seismic profile in the central part of the south Caspian Basin. We obtained main peak of the tectonic subsidence for the South Caspian Basin in the Pliocene time - 2 km of the tectonic subsidence and tectonic subsidence rate up to 1200 m/Ma. Rapid subsidence of the basin was contemporaneous with increase of compression and orogenesis on the borders of the basin. We examine the hypothesis, explaining this rapid syncompres- sional subsidence by flexural response of the basin lithosphere to increase of imposed compressional force Lithosphere of the investigated South Caspian

  7. Depositional architecture and evolution of inner shelf to shelf edge delta systems since the Late Oliocene and their respone to the tectonic and sea level change, Pear River Mouth Basin, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Lin, Changsong; Zhang, Zhongtao; liu, Jingyan; Jiang, Jing

    2016-04-01

    The Pear River Mouth Basin is located in the northern continent margin of the South China Sea. Since the Late Oligocene, the long-term active fluvial systems (Paleo-Zhujiang) from the western basin margin bebouched into the northern continental margin of the South China Sea and formed widespread deltaic deposits in various depositional geomorphologies and tectonic settings. Based of integral analysys of abundant seismic, well logging and drilling core data, Depositional architecture and evolution of these delta systems and their respone to the tectonic and sea level change are documented in the study. There are two basic types of the delta systems which have been recognized: inner shelf delta deposited in shallow water enviroments and the outer shelf or shelf-edge delta systems occurred in deep water settings. The paleowater depths of these delta systems are around 30 to 80m (inner shelf delta) and 400-1000m (shelf-edge delta) estimated from the thickness (decompaction) of the delta front sequences. The study shows that the inner shelf delta systems are characterized by relatively thin delta forests (20-40m), numereous stacked distributary channel fills, relative coarse river mouth bar deposits and thin distal delta front or distal bar and prodelta deposits. In contrast, the outer shelf or shelf edge delta systems are characteristic of thick (300-800m) and steep (4-60) of deltaic clinoforms, which commonly display in 3D seismic profiles as "S" shape reflection. Large scale soft-sediment deformation structures, slump or debris flow deposits consisting mainly of soft-sediment deformed beds, blocks of sandstones and siltstones or mudstones widely developed in the delta front deposits. The shelf edge delta systems are typically associated with sandy turbidite fan deposits along the prodelta slopes, which may shift basinwards as the progradation of the delta systems. The delta systems underwent several regional cycles of evolution from inner shelf deltas to shelf edge

  8. Eocene Podocarpium (Leguminosae) from South China and its biogeographic implications.

    PubMed

    Xu, Qingqing; Qiu, Jue; Zhou, Zhekun; Jin, Jianhua

    2015-01-01

    Podocarpium A. Braun ex Stizenberger is one of the most common legumes in the Neogene of Eurasia, including fossil fruits, seeds, leaves, and possible flower and pollen grains. This genus is not completely consistent with any extant genera according to gross morphological characters and poorly preserved cuticular structures reported in previous studies. The fossil pods collected from the coal-bearing series of the Changchang Basin of Hainan Island and Maoming Basin of Guangdong, South China, are examined by morphologically comparative work, with special reference to venation patterns and placental position. These distinctive features, as well as the ovule development of pods from different developmental stages and the epidermal structure of the pods, as distinguished from previous records lead to the conclusion that these fossils can be recognized as a new species of Podocarpium, P. eocenicum sp. nov. This new discovery indicates that Podocarpium had arrived in South China by the Eocene. Investigation on the fossil records of this extinct genus shows that P. eocenicum is the earliest and lowest latitude fossil data. The possible occurrence pattern of this genus is revealed as follows: Podocarpium had distributed in the South China at least in the middle Eocene, and then migrated to Europe during the Oligocene; in the Miocene this genus reached its peak in Eurasia, spreading extensively across subtropical areas to warm temperate areas; finally, Podocarpium shrank rapidly and became extinct in Eurasia during the Pliocene. PMID:26579179

  9. Eocene Podocarpium (Leguminosae) from South China and its biogeographic implications

    PubMed Central

    Xu, Qingqing; Qiu, Jue; Zhou, Zhekun; Jin, Jianhua

    2015-01-01

    Podocarpium A. Braun ex Stizenberger is one of the most common legumes in the Neogene of Eurasia, including fossil fruits, seeds, leaves, and possible flower and pollen grains. This genus is not completely consistent with any extant genera according to gross morphological characters and poorly preserved cuticular structures reported in previous studies. The fossil pods collected from the coal-bearing series of the Changchang Basin of Hainan Island and Maoming Basin of Guangdong, South China, are examined by morphologically comparative work, with special reference to venation patterns and placental position. These distinctive features, as well as the ovule development of pods from different developmental stages and the epidermal structure of the pods, as distinguished from previous records lead to the conclusion that these fossils can be recognized as a new species of Podocarpium, P. eocenicum sp. nov. This new discovery indicates that Podocarpium had arrived in South China by the Eocene. Investigation on the fossil records of this extinct genus shows that P. eocenicum is the earliest and lowest latitude fossil data. The possible occurrence pattern of this genus is revealed as follows: Podocarpium had distributed in the South China at least in the middle Eocene, and then migrated to Europe during the Oligocene; in the Miocene this genus reached its peak in Eurasia, spreading extensively across subtropical areas to warm temperate areas; finally, Podocarpium shrank rapidly and became extinct in Eurasia during the Pliocene. PMID:26579179

  10. The South China sea margins: Implications for rifting contrasts

    USGS Publications Warehouse

    Hayes, D.E.; Nissen, S.S.

    2005-01-01

    Implications regarding spatially complex continental rifting, crustal extension, and the subsequent evolution to seafloor spreading are re-examined for the northern and southern-rifted margins of the South China Sea. Previous seismic studies have shown dramatic differences in the present-day crustal thicknesses as the manifestations of the strain experienced during the rifting of the margin of south China. Although the total crustal extension is presumed to be the same along the margin and adjacent ocean basin, the amount of continental crustal extension that occurred is much less along the east and central segments of the margin than along the western segment. This difference was accommodated by the early formation of oceanic crust (creating the present-day South China Sea basin) adjacent to the eastern margin segment while continued extension of continental crust was sustained to the west. Using the observed cross-sectional areas of extended continental crust derived from deep penetration seismics, two end-member models of varying rift zone widths and varying initial crustal thicknesses are qualitatively examined for three transects. Each model implies a time difference in the initiation of seafloor spreading inferred for different segments along the margin. The two models examined predict that the oceanic crust of the South China Sea basin toward the west did not begin forming until sometime between 6-12 my after its initial formation (???32 Ma) toward the east. These results are compatible with crustal age interpretations of marine magnetic anomalies. Assuming rifting symmetry with conjugate margin segments now residing along the southern portions of the South China Sea basin implies that the total width of the zone of rifting in the west was greater than in the east by about a factor of two. We suggest the most likely causes of the rifting differences were east-west variations in the rheology of the pre-rift crust and associated east-west variations in the

  11. The complexity of South China Sea kinematics

    NASA Astrophysics Data System (ADS)

    Sibuet, Jean-Claude; Gao, Jinyao; Zhao, Minghui; Wu, Jonny; Ding, Weiwei; Yeh, Yi-Ching; Lee, Chao-Shing

    2016-04-01

    Magnetic modeling shows that the age of the youngest South China Sea (SCS) oceanic crust is controversial (e.g. 15.5 Ma, Briais et al., JGR 1993 and 20.5 Ma, Barckhausen et al., MPG 2014). Close to the rift axis of the East sub-basin, Ar-Ar age dating of oceanic crustal rocks collected during IODP Leg 349 gives ages of 15 and 15.2 +/- 0.2 Ma (Koppers, Fall AGU meeting, 2014), which seems to favor the 15.5 Ma age given by Briais et al. modeling. However, basaltic samples might belong to a sill and not to the typical oceanic crust. As post-spreading magmatic activity (~8-13 Ma) largely masks the spreading fabric, in particular near the previously identified E-W portion of the extinct ridge axis of the East sub-basin, the published locations of the axial magnetic anomaly and spreading rates are incorrect. The compilation of available swath bathymetric data shows that if post-spreading volcanics hide the seafloor spreading magnetic fabric mostly along and near the extinct spreading axis, the whole SCS is globally characterized by rift directions following three directions: N055°in the youngest portion of the SCS, N065° and N085° in the oldest portions of the SCS (Sibuet et al., Tectonophysics 2016) suggesting the extinct ridge axis is N055° trending instead of E-W. We present an updated version of the whole SCS structural sketch based on previously published swath bathymetric trends and new detailed magnetic lineations trends compiled from an extremely dense set of magnetic data. The new structural sketch shows: - The distribution of conjugate kinematic domains, - The early opening of the NW and East sub-basins, before a jump of the rift axis, - A second ridge jump in the East basin, - The different expressions of the post-spreading magmatism in the East and SW sub-basins. In the East sub-basin, crustal magmatic intrusions led to the formation of extrusive basalts associated with the presence of numerous volcanoes (Wang et al., Geological Journal 2016). In the SW

  12. The interannual oscillation of sea surface temperature in the South China Sea

    SciTech Connect

    Zhou Faxiu; Yu Shenyu; Fu Gang; Wang Dongxiao

    1994-12-31

    The South China Sea (SCS) is located in the area of the Asia monsoons and is a quasi-closed deep basin near the tropical western Pacific. The sea surface temperature anomalies (SSTA) in the South China Sea have an influence on the precipitation in flood season in the South China. The anomalies of the Asia monsoons have great effect on SST in the SCS. This paper aims at finding the features of the interannual oscillation of SST and discussing the mechanism of the SST oscillation in the SCS.

  13. Deep Circulation in the South China Sea

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaolong; Zhao, Wei; Xu, Xiaobiao; Tian, Jiwei; Zhou, Chun

    2016-04-01

    The South China Sea (SCS) is the largest marginal sea of the northwest Pacific. The deep circulation in the SCS is investigated on the basis of the Hybrid Coordinate Ocean Model (HYCOM). All the experiments show reasonable agreement with observation from mooring arrays. Analysis of these results provides a detailed spatial structure and temporal variability of the deep circulation in the SCS. The major features of the SCS deep circulation are basin-scale cyclonic gyre and concentrated deep western boundary current (DWBC). The transport of the DWBC is ~2 Sv at 16.5°N with a width of ~53 km. As flowing southwestward, the DWBC becomes weaker with a wider range. Deep upwelling in the SCS is estimated of 0.19 to 1.15 m d-1 with the strongest area around the DWBC. The model results reveal the existence of 80 to 120 days oscillation in the deep northeastern circulation and the DWBC, which are also the areas with large eddy kinetic energy. This seasonal oscillation is northwestward with a velocity amplitude of ~1.0~1.5 cm s-1. The distribution of mixing parameters in the deep SCS plays a role in both spatial structure and volume transport of the deep circulation. Compared with the north shelf of the SCS with the Luzon Strait, deep circulation in the SCS is more sensitive to the large vertical mixing parameters of the Zhongsha Island Chain area.

  14. Prototypical solitons in the South China Sea

    NASA Astrophysics Data System (ADS)

    Klymak, Jody M.; Pinkel, Robert; Liu, Cho-Teng; Liu, Antony K.; David, Laura

    2006-06-01

    Surface signatures associated with non-linear internal waves are often seen in satellite images of the western South China Sea (SCS) slope and shelf. Observation in the deep sea, to the east, are rare. Here we report on the evolution of an energetic packet as it propagated through the deep central basin of the SCS, toward the western slope and shelf. The waves have amplitudes estimated at 170 m, half widths of 3 km, and phase speeds of 2.9 +/- 0.1 m/s, faster than the mode-1 linear phase speed of 2.6 m/s. The shape and observed phase speed were consistent with the Korteweg-deVries (KdV) model over the 65-km path that they were tracked. The intrinsic velocity shear of the waves is small compared to pre-existing shears, and the waves exhibit weak turbulence. The KdV fit and a satellite-derived estimate of horizontal wave extent imply a westward energy flux of 4.5 GW for each crest.

  15. Provenance and sediment dispersal of the Triassic Yanchang Formation, southwest Ordos Basin, China, and its implications

    NASA Astrophysics Data System (ADS)

    Xie, Xiangyang

    2016-04-01

    The Ordos Basin in north central China records a transition from marine to non-marine deposition during the late Paleozoic to early Mesozoic. As a result, the northern and southern regions of the Ordos Basin show different tectonic histories and very distinctive sedimentation styles. Two deformation belts, the Qinling orogenic belt to the south and the Liupanshan thrust and fold belt to the west, controlled the structural evolution of the southern Ordos Basin during the early Mesozoic. Paleocurrent analysis, net-sand ratio maps, sandstone modal analysis, and U-Pb detrital zircon geochronology were used to document sediment sources and dispersal patterns of the Triassic Yanchang Formation in the southwest Ordos Basin. Paleocurrent measurements suggest that the sediments were mainly derived from the Liupanshan and the Qinling orogenic belts. Net-sand ratio maps show that several fan delta systems controlled sediment delivery in the south Ordos Basin. Both sandstone modal analysis and U-Pb detrital zircon geochronology suggest that the Yanchang Formation is locally sourced from both of the basin marginal deformation belts; the lower and middle sections are recycled Paleozoic sedimentary rocks mainly derived from the north Qinling orogenic belt, whereas for the upper section, the Qilian-Qaidam terranes and possibly the west Qinling orogenic belt began to shed sediments into the southwest Ordos Basin. Results have important implications for basin marginal tectonics and its controls on sedimentation of intracratonic basins in China and similar settings.

  16. Hydropower Ambitions of South Asian Nations: Ganges and Brahmaputra River basins

    NASA Astrophysics Data System (ADS)

    Mizanur Rahaman, Muhammad

    2010-05-01

    This paper analyses the current status of hydropower development in two major river basins in South Asia, the Ganges and the Brahmaputra. The total drainage area of the basins is about 1660,000 km2 shared by China, Nepal, India, Bhutan, and Bangladesh. The basins are blessed with ample water resources and huge hydropower potential. Hydropower development is strongly linked with the overall development framework of the region. The abundant hydropower potential of the Ganges and the Brahmaputra can help give riparian countries a safer energy future that is the key driving force behind the prospect of potential cooperation in the field of water. Based on four years research studies (2005-2009), this paper analyse the hydropower development plans and ambitions of riparian nations with special focus on China and India. The finding suggests that it is essential to develop an integrated hydropower development approach involving all riparian nations intended to foster regional development and overcome the prospect of severe conflict because of unilateral hydropower ambitions of China and India. The hydropower development cooperation between China and India could also become the positive turning point in the integration of South and South-East Asia.

  17. Seismic investigation of an ocean-continent transition zone in the northern South China Sea

    NASA Astrophysics Data System (ADS)

    Zhu, J.; Qiu, X.; Xu, H.; Zhan, W.; Sun, Z.

    2011-12-01

    Rifted continental margins and basins are mainly formed by the lithospheric extension. Thined lithosphere of passive continental margins results in decompression melt of magma and created oceanic crust and thined ocean-continent transition (OCT) zone. Two refraction profiles used ocean bottom seismometers deployed in the broad continental shelf and three multi-channel seismic reflection lines in the northern South China Sea, acquired by the ship "Shiyan 2" of the South China Sea Institute of Oceanology, Chinese Academy of Sciences in 2010, are processed and interpreted in this study. Seismic reflection lines cut through the Dongsha rise, Zhu-1 and Zhu-2 depression within a Tertiary basin, Pear River Mouth basin (called as Zhujiangkou basin). These tectonic features are clear imaged in the seismic reflection records. Numerous normal faults, cutted through the basement and related to the stretch of the northern South China Sea margin, are imaged and interpreted. Reflection characteristics of the ocean-continent transition (OCT) zone are summaried and outlined. The COT zone is mainly divided into the northern syn-rift subsidence zone, central volcano or buried volcano uplift zone and tilt faulted block near the South Chia Sea basin. Compared to the previous seismic reflection data and refraction velocity models, the segmentation range of the OCT zone is outlined, from width of about 225 km in the northeastern South China Sea , of 160 km in the central to of 110 km in the north-central South China Sea. Based on the epicenter distribution of sporadic and large than 6 magnitude earthquakes, it suggests the OCT zone in the northern South China Sea at present is still an active seismic zone.

  18. View of former preliminary sedimentation basin, looking east from south ...

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

    View of former preliminary sedimentation basin, looking east from south side of low-lift pumping station. - Robert B. Morse Water Filtration Plant, 10700 and 10701 Columbia Pike, Silver Spring, Montgomery County, MD

  19. GRACE captures basin mass dynamic changes in China based on a multi-basin inversion method

    NASA Astrophysics Data System (ADS)

    Yi, Shuang; Wang, Qiuyu; Sun, Wenke

    2016-04-01

    Complex landform, miscellaneous climate and enormous population have enriched China with geophysical phenomena ranging from water depletion in the underground to glaciers retreat on the high mountains and have aroused large scientific interests. This paper, utilizing gravity observations 2003-2014 from the Gravity Recovery and Climate Experiment (GRACE), intends to make a comprehensive estimation of mass status in 16 drainage basins in the whole region. We proposed a multi-basin inversion method, which is featured by resistance to the stripe noise and ability to alleviate signal attenuation due to truncation and smoothing of GRACE data. The results show both positive and negative trends: there is a tremendous mass accumulation spreading from the Tibetan plateau (12.2 ± 0.6 Gt/yr) to the Yangtze River (7.6 ± 1.3 Gt/yr), and further to the southeast coastal areas, which is suggested to involve an increase in the ground water storage, lake and reservoir water volume and likely materials flowed in by tectonic process; a mass loss is occurring in Huang-Huai-Hai-Liao River Basin (-10.5 ± 0.8 Gt/yr), as well as the Brahmaputra-Nujiang-Lancang River Basin (-15.0 ± 0.9 Gt/yr) and Tienshan Mountain (-4.1 ± 0.3 Gt/yr), which is a result of groundwater pumping and glacier melting. The groundwater depletion area is well consistent with the distribution of land subsidence in North China. In the end, we find intensified precipitation can alter the local water supply and GRACE is proficient to capture this dynamics, which could be instructive for the South-to-North Water Diversion - one China's giant hydrologic project.

  20. The tectonic evolution of the greater South China Sea

    SciTech Connect

    Hayes, D.E. )

    1990-06-01

    The South China Sea (SCS) basin is composed of two major subbasins. The eastern subbasin was formed by seafloor spreading in the middle Tertiary and is associated with roughly E-W-trending magnetic lineations. The southwestern subbasin of the South China Sea is characterized by NE-SW tectonic and magnetic trends and is considerably narrower than the eastern subbasin. There is no obvious structural discontinuity between the two subbasins; hence the initial opening of the eastern subbasin was likely accommodated to the west by a prolonged period of extension of the continental crust that was not accompanied by the formation of normal oceanic crust. The southwest subbasin was eventually also formed by seafloor spreading processes. Although the sequence of magnetic lineations recorded there is relatively short, these data coupled with heatflow and crustal depth data strongly suggest that the southwestern subbasin was not formed until the early-middle Miocene, coincident with the last phase of spreading in the adjacent eastern subbasin. It is still unclear whether or not a significant change in spreading direction occurred within the SCS basin during the early Miocene. The geometry of the deep SCS basin as defined by the seaward limit of the continent-ocean boundary zone provides important constraints on the east-to-west variations in the total crustal extension manifested in the rifted margins of the South China Sea. The amount of new oceanic crust created by seafloor spreading plus the amount of crustal extension accommodated within the continental crust must be nearly the same for all points along the rifted margins. Because the amount of oceanic crust present is quite variable, it follows that the amount of crustal extension must be similarly variable and in a predictable way.

  1. Early Continental Rifting of the South China Sea

    NASA Astrophysics Data System (ADS)

    Lee, C.; Chiu, M.; Chan, C.

    2010-12-01

    Combined two years (2007 and 2008) of OBS and MCS studies in the northern slope of the South China Sea, we suggest that the early rifting, probably during 60 - 30 mabp, is an asymmetrical Atlantic-type continental rifting. The crust thin out from 35-40 km of possible continental crust to about 10-15 km of typical oceanic crust. Along the continent-ocean boundary, we observe an intrusion of the high P-wave velocity (about 7.5-8.0 km/sec). This is possible of mantle exhumation as comparable to other Atlantic-type continental margins. The OBS result is revealed by the gravity data. Along the upper layers of the continental crust as well as the oceanic crust, the MCS and multi-beam bathymetry data show that they are covered by numerous submarine seamounts. This probably relate to a volcanic origin of the Cenozoic sea-floor spreading during 30-15 mabp as mapped by previous magnetic anomalies in this region. The sea-floor spreading spread apart in the central, NW and SW sub-basins with several different episodes. Lack of the deep crustal data in the southern slope of the South China Sea, particularly around the Sprately area, the interpretation is speculative. However, several very large-size atolls (150 - 200 km in diameter), such as the Chen-Ho, Shun-Zu, Chung-Yeh and Chiu-Cheng fringing reefs, are sub-parallel located along the south margins. We interpret that these are the upper portions of the continental rifting. Combined the two tectonic stories in the northern and southern slope of the South China Sea, we believe that it is in consistent with the complicate nature of the South China Sea crust.

  2. Anomalous wave propagation across the South Caspian Basin

    SciTech Connect

    Priestly, K.; Patton, H.J.; Schultz, C.

    1997-10-01

    The Caspian basin blocks the propagation of the regional seismic phase Lg and this has importance consequences for seismic discrimination in the Middle East. Intermediate period surface waves propagating across the basin are also severely affected. In a separate study we have developed a crustal model of the south Caspian basin and the surrounding region. The crust of the basin consists of 15-25 km of low velocity, highly attenuating sediments lying on high velocity crystalline crust. The Moho beneath the basin is at a depth of about 30 km as compared to about 50 km in the surrounding region. In this study we used an idealized rendition of this crustal model to compute hybrid normal mode finite difference synthetic seismograms to identify the features of the Caspian basin which lead to the seismic blockage. Of the various features of the basin, the thickness and attenuation of the sediments appear to be the dominant blocking mechanism.

  3. 33 CFR 117.149 - China Basin, Mission Creek.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false China Basin, Mission Creek. 117.149 Section 117.149 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements California § 117.149 China Basin,...

  4. 33 CFR 117.149 - China Basin, Mission Creek.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false China Basin, Mission Creek. 117.149 Section 117.149 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements California § 117.149 China Basin,...

  5. 33 CFR 117.149 - China Basin, Mission Creek.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false China Basin, Mission Creek. 117.149 Section 117.149 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements California § 117.149 China Basin,...

  6. 33 CFR 117.149 - China Basin, Mission Creek.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false China Basin, Mission Creek. 117.149 Section 117.149 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements California § 117.149 China Basin,...

  7. 33 CFR 117.149 - China Basin, Mission Creek.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false China Basin, Mission Creek. 117.149 Section 117.149 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements California § 117.149 China Basin,...

  8. The Changing Faces of the South China Sea

    NASA Astrophysics Data System (ADS)

    Pubellier, M. F.; Savva, D.; Franke, D.; Meresse, F.; Steuer, S.; Auxietre, J. L.; Aurelio, M.; Chamot-Rooke, N. R. A.; Chan, L. S.

    2014-12-01

    The South China Sea (SCS) region was situated during Mesozoic on the upper plate of a subduction zone. It later evolved as a collapsed continental basin on the edge of the Yenshanian Andean-type orogeny which has been since then considerably eroded, exposing only granites and relicts of Cretaceous molasse basins. The continental crust rifted from the Paleocene to the Mid Oligocene in the eastern part, and the rifting continued until the Middle Miocene in the SW, in an environment of marginal basin opened in the midst of the lower plate. Both spreading and rifting ceased when the subduction of the Proto South China Sea (PSCS) was blocked. Finally the SCS basin which was previously always open to the NE, became isolated by the docking of the northern Philippine Mobile Belt in Luzon, Mindoro and Taiwan islands, during the Late Miocene. Since then the basin subsided whereas the margins observed various amount of uplift, and subsequent gravity tectonics. We illustrate how these event are interdependent, the Cretaceous active margin opening the PSCS by rifting and oceanic crust developed from magma-poor rifting to subsequent seafloor spreading in the Paleogene. It is not clear how the inherited sub continental mantle played a role in the unusual rifting style of the SCS, whose upper crust was extremely stretched for a large time span and was sustained near sea level during the entire duration of the rifting process. The large Jurassic and Cretaceous granitic bodies conditioned the location of the extension via large detachments and normal faults; so that the present day morphology of the sea floor still reflects the location of the granites on which large reefal platforms developed. The mid Miocene cessation of subduction in the PSCS created shortening which jammed its sediments on the NE margin of Borneo, thus generating sub-aerial conditions for the NW Borneo wedge. The resulting erosion created the large deltas starting from the end of the Early Miocene. Excess of

  9. Archean foreland basin tectonics from the Witwatersrand, South Africa

    SciTech Connect

    Burke, K.; Kidd, W.S.F.; Kusky, T.M.

    1985-01-01

    The Witwatersrand Basin of South Africa is the best-known of Archean sedimentary basins and contains some of the largest gold reserves in the world. Sediments in the basin include a lower flysch-type sequence and an upper molassic facies, both of which contain abundant silicic volcanic detritus. The strata are thicker and more proximal on the northwestern side of the basin which is, at least locally, bound by thrust faults. These and other features indicate that the Witwatersrand strata were deposited in a foreland basin. A regional geologic synthesis suggests that his basin developed initially on the cratonward side of an Andean-type arc. Remarkably similar Phanerozoic basins may be found in the southern Andes above zones of shallow subduction. We suggest that the continental collision between the Kaapvaal and Zimbabwe Cratons at about 2.7 Ga caused further subsidence and deposition in the Witwatersrand Basin. Regional uplift during this later phase of development placed the basin on the cratonward edge of a collision-related plateau, now represented by the Limpopo Province. Striking similarities are seen between this phase of Witwatersrand Basin evolution and active basins located north of the Tibetan Plateau. The geologic evidence is not so compatible with earlier suggestions that the Witwatersrand strata were deposited in a rift or half-graben.

  10. Archean foreland basin tectonics in the Witwatersrand, South Africa

    SciTech Connect

    Burke, K.; Kidd, W.S.F.; Kusky, T.M.

    1986-06-01

    The Witwatersrand Basin of South Africa is the best-known of Archean sedimentary basins and contains some of the largest gold reserves in the world. Sediments in the basin include a lower flysch-type sequence and an upper molassic facies, both of which contain abundant silicic volcanic detritus. The strata are thicker and more proximal on the northwestern side of the basin which is, at least locally, bound by thrust faults. These features indicate that the Witwatersrand strata may have been deposited in a foreland basin and a regional geologic synthesis suggests that this basin developed initially on the cratonward side of an Andean-type arc. Remarkably similar Phanerozoic basins may be found in the southern Andes above zones of shallow subduction. It is suggested that the continental collision between the Kaapvaal and Zimbabwe Cratons at about 2.7 Ga caused further subsidence and deposition in the Witwatersrand Basin. Regional uplift during this later phase of development placed the basin on the cratonward edge of a collision-related plateau, now represented by the Limpopo Province. Similarities are seen between this Phase of Witywatersrand Basin evolution and that of active basins north of the Tibetan Plateau. The geologic evidence does not agree with earlier suggestions that the Witwatersrand strata were deposited in a rift or half-graben. 64 references.

  11. Archean foreland basin tectonics in the Witwatersrand, South Africa

    NASA Technical Reports Server (NTRS)

    Burke, K.; Kidd, W. S. F.; Kusky, T. M.

    1986-01-01

    The Witwatersrand Basin of South Africa is the best-known of Archean sedimentary basins and contains some of the largest gold reserves in the world. Sediments in the basin include a lower flysch-type sequence and an upper molassic facies, both of which contain abundant silicic volcanic detritus. The strata are thicker and more proximal on the northwestern side of the basin which is, at least locally, bound by thrust faults. These features indicate that the Witwatersrand strata may have been deposited in a foreland basin and a regional geologic synthesis suggests that this basin developed initially on the cratonward side of an Andean-type arc. Remarkably similar Phanerozoic basins may be found in the southern Andes above zones of shallow subduction. It is suggested that the continental collision between the Kaapvaal and Zimbabwe Cratons at about 2.7 Ga caused further subsidence and deposition in the Witwatersrand Basin. Regional uplift during this later phase of development placed the basin on the cratonward edge of a collision-related plateau, now represented by the Limpopo Province. Similarities are seen between this Phase of Witywatersrand Basin evolution and that of active basins north of the Tibetan Plateau. The geologic evidence does not agree with earlier suggestions that the Witwatersrand strata were deposited in a rift or half-graben.

  12. Archean foreland basin tectonics in the Witwatersrand, South Africa

    NASA Technical Reports Server (NTRS)

    Burke, K.; Kidd, W. S. F.; Kusky, T. M.

    1986-01-01

    The Witwatersrand Basin of South Africa is the best-known of Archean sedimentary basins and contains some of the largest gold reserves in the world. Sediments in the basin include a lower flysch-type sequence and an upper molassic facies, both of which contain abundant silicic volcanic detritus. The strata are thicker and more proximal on the northwestern side of the basin which is, at least locally, bound by thrust faults. These features indicate that the Witwatersrand strata may have been deposited in a foreland basin and a regional geologic synthesis suggests that this basin developed initially on the cratonward side of an Andean-type arc. Remarkably similar Phanerozoic basins may be found in the southern Andes above zones of shallow subduction. It is suggested that the continental collision between the Kaapvaal and Zimbabwe Cratons at about 2.7 Ga caused further subsidence and deposition in the Witwatersrand Basin. Regional uplift during this later phase of development placed the basin on the cratonward edge of a collision-related plateau, now represented by the Limpopo Province. Similarities are seen between this phase of Witwatersrand Basin evolution and that of active basins north of the Tibetan Plateau. The geologic evidence does not agree with earlier suggestions that the Witwatersrand strata were deposited in a rift or half-graben.

  13. Dominant factors in controlling marine gas pools in South China

    USGS Publications Warehouse

    Xu, S.; Watney, W.L.

    2007-01-01

    In marine strata from Sinian to Middle Triassic in South China, there develop four sets of regional and six sets of local source rocks, and ten sets of reservoir rocks. The occurrence of four main formation periods in association with five main reconstruction periods, results in a secondary origin for the most marine gas pools in South China. To improve the understanding of marine gas pools in South China with severely deformed geological background, the dominant control factors are discussed in this paper. The fluid sources, including the gas cracked from crude oil, the gas dissolved in water, the gas of inorganic origin, hydrocarbons generated during the second phase, and the mixed pool fluid source, were the most significant control factors of the types and the development stage of pools. The period of the pool formation and the reconstruction controlled the pool evolution and the distribution on a regional scale. Owing to the multiple periods of the pool formation and the reconstruction, the distribution of marine gas pools was complex both in space and in time, and the gas in the pools is heterogeneous. Pool elements, such as preservation conditions, traps and migration paths, and reservoir rocks and facies, also served as important control factors to marine gas pools in South China. Especially, the preservation conditions played a key role in maintaining marine oil and gas accumulations on a regional or local scale. According to several dominant control factors of a pool, the pool-controlling model can be constructed. As an example, the pool-controlling model of Sinian gas pool in Weiyuan gas field in Sichuan basin was summed up. ?? Higher Education Press and Springer-Verlag 2007.

  14. Structure, stratigraphy and petroleum geology of the south east Nam Con Son Basin, offshore Vietnam

    SciTech Connect

    Fraser, A.J.; Matthews, S.J.; Lowe, S.; Todd, S.P.; Simon, P. Peel, F.J.

    1996-12-31

    Recent exploration of the south east Nam Con Son Basin, offshore Vietnam, by BP in alliance with Statoil has involved acquisition of new seismic and well data. These new data have allowed re-evaluation of the tectono-stratigraphic development and petroleum geology, and have provided additional constraints on the regional tectonic evolution. The offshore Vietnamese basins have evolved in response to the complex relative motions of Indochina, Peninsular Malaysia, Borneo and the South China Sea during the Cenozoic. On the regional scale these motions have been accommodated by strike-slip fault development, rifting and contraction. In the Nam Con Son Basin these motions have interacted in different ways from the Palaeogene to recent. Two rifting episodes are recognized; a Palaeogene phase dominated by E-W trending extensional faults, and a Miocene phase dominated by N-S to NE-SW trending faults. The structural evolution is complicated by a pulse of mild contraction during the Middle Miocene. The sedimentary fill of the basin evolves from continental fluvio-lacustrine in the Palaeogene through to fully marine following the second phase of rifting in the Miocene. This pulsed structural and stratigraphic evolution has resulted in basinwide deposition of source, reservoir and seal facies, and produced a variety of potential trapping styles. This paper describes the hydrocarbon habitat of the south east Nam Con Son Basin within the context of the regional tectono-stratigraphic model.

  15. Structure, stratigraphy and petroleum geology of the south east Nam Con Son Basin, offshore Vietnam

    SciTech Connect

    Fraser, A.J.; Matthews, S.J.; Lowe, S.; Todd, S.P.; Simon, P. Peel, F.J. )

    1996-01-01

    Recent exploration of the south east Nam Con Son Basin, offshore Vietnam, by BP in alliance with Statoil has involved acquisition of new seismic and well data. These new data have allowed re-evaluation of the tectono-stratigraphic development and petroleum geology, and have provided additional constraints on the regional tectonic evolution. The offshore Vietnamese basins have evolved in response to the complex relative motions of Indochina, Peninsular Malaysia, Borneo and the South China Sea during the Cenozoic. On the regional scale these motions have been accommodated by strike-slip fault development, rifting and contraction. In the Nam Con Son Basin these motions have interacted in different ways from the Palaeogene to recent. Two rifting episodes are recognized; a Palaeogene phase dominated by E-W trending extensional faults, and a Miocene phase dominated by N-S to NE-SW trending faults. The structural evolution is complicated by a pulse of mild contraction during the Middle Miocene. The sedimentary fill of the basin evolves from continental fluvio-lacustrine in the Palaeogene through to fully marine following the second phase of rifting in the Miocene. This pulsed structural and stratigraphic evolution has resulted in basinwide deposition of source, reservoir and seal facies, and produced a variety of potential trapping styles. This paper describes the hydrocarbon habitat of the south east Nam Con Son Basin within the context of the regional tectono-stratigraphic model.

  16. 14C as a tool for evaluating riverine POC sources and erosion of the Zhujiang (Pearl River) drainage basin, South China

    NASA Astrophysics Data System (ADS)

    Wei, Xiuguo; Yi, Weixi; Shen, Chengde; Yechieli, Yoseph; Li, Ningli; Ding, Ping; Wang, Ning; Liu, Kexin

    2010-04-01

    Radiocarbon can serve as a powerful tool for identifying sources of organic carbon and evaluating the erosion intensity in river drainage basins. In this paper we present 14C-AMS measurements of particulate organic carbon (POC) collected from the three major tributaries of the Zhujiang (Pearl River) system: the Xijiang (Western River), Beijiang (Northern River) and Dongjiang (Eastern River) rivers. Furthermore, we discuss the distribution of POC 14C apparent ages and the related watersheds erosion of these rivers. Results yield Δ 14C values of -425‰ to -65‰ which indicate that the 14C apparent ages of suspended POC in the entire area are in the range of 540-4445 years. The POC apparent ages from Xijiang are mostly between 2000 and 4000 years, while in Dongjiang they mostly range from 540 to 1010 years. These 14C apparent ages indicate that the watershed erosion of the Xijiang is more severe than that of the Dongjiang. This is in agreement with other data showing deeper erosion in Xijiang due to human activities.

  17. Middle Miocene reworked turbidites in the Baiyun Sag of the Pearl River Mouth Basin, northern South China Sea margin: Processes, genesis, and implications

    NASA Astrophysics Data System (ADS)

    Gong, Chenglin; Wang, Yingmin; Zheng, Rongcai; Hernández-Molina, F. Javier; Li, Yun; Stow, Dorrik; Xu, Qiang; Brackenridge, Rachel E.

    2016-10-01

    Our understanding of reworked turbidites is still in its infancy, and their flow processes and genesis still remain understudied. Core data from the middle Miocene Zhujiang Formation in the Pearl River Mouth Basin allow us to differentiate reworked turbidites, yielding two main contributions. Firstly, reworked turbidites are distinguished from turbidites by the association of traction structures and tidal signatures, which occur in discrete units rather than forming a classic "Bouma Sequence" for turbidites. Sedimentological characteristics of reworked turbidites proposed here will help to obtain a robust set of diagnostic criteria for the recognition of deep-water non-turbidite deepwater units as reservoirs. Secondly, our results suggest that, in the down-slope direction, classic detritus carried in turbidity flows would synchronously be bidirectionally reworked by internal tides and waves, resulting in tidal signatures seen in the interpreted reworked turbidites. In the along-slope direction, upper parts of dilute turbidity currents would mix vertically with seawater, and muddy fines would be winnowed away by contour currents, whereas lower parts of dilute turbidity currents would probably drop their coarse particles, resulting in traction structures recognized in the documented reworked turbidites. Our work highlights the influence of bottom currents on the development and modification of turbidites and suggests that reworked turbidites were created by the combined action of down-slope transport and reworking and along-slope winnowing and sorting, helping to better understand flow processes and genesis of non-turbidite reservoirs with a great economic interest.

  18. Morphologies, classification and genesis of pockmarks, mud volcanoes and associated fluid escape features in the northern Zhongjiannan Basin, South China Sea

    NASA Astrophysics Data System (ADS)

    Chen, Jiangxin; Song, Haibin; Guan, Yongxian; Yang, Shengxiong; Pinheiro, Luis M.; Bai, Yang; Liu, Boran; Geng, Minghui

    2015-12-01

    Based on new high-resolution multi-beam bathymetry and multichannel seismic reflection data, two new groups of numerous pockmarks and mud volcanoes were discovered in the northern Zhongjiannan Basin at water depths between 600 and 1400 m. Individual pockmarks are circular, elliptical, crescent-shaped or elongated, with diameters ranging from several hundreds to thousands of meters and tens or hundreds of meters in depth, and they often form groups or strings. Crescent pockmarks, approximately 500-1500 m wide in cross-section and 50-150 m deep, occur widely in the southern study area, both as individual features and in groups or curvilinear chains, and they are more widespread and unique in this area than anywhere else in the world. Conical mud volcanoes, mostly with kilometer-wide diameters and ca. 100 m high, mainly develop in the northern study area as individual features or in groups. Seismic data show that the observed pockmarks are associated with different kinds of fluid escape structures and conduits, such as gas chimneys, diapirs, zones of acoustic blanking, acoustic turbidity and enhanced reflections, inclined faults, small fractures and polygonal faults. The mapped mud volcanoes appear to be fed from deep diapirs along two main conduit types: the conventional conduits with downward tapering cones and another other conduit type with a narrow conduit in the lower half and emanative leakage passages in the upper half. Various types of pockmarks are found and a comprehensive pockmark classification scheme is proposed, according to: (a) their shape in plan view, which includes circular, elliptical, crescent, comet-shape, elongated and irregular; (b) their magnitude, which includes small, normal, giant and mega-pockmarks; and (c) their composite pattern, which includes composite pockmarks, pockmark strings and pockmark groups. For the genesis of the crescent pockmark (strings), a 5-stage speculative formation model is proposed, implying possible controlling

  19. Late tectonic uplift of an inverted oceanic basin in South East Asia: the case of Palawan Island (western Philippines)

    NASA Astrophysics Data System (ADS)

    Meresse, F.; Savva, D.; Pubellier, M.; Steuer, S.; Franke, D.; Cordey, F.; Muller, C.; Sapin, F.; Mouly, B.; Auxiètre, J.-L.

    2012-04-01

    The elongated island of Palawan, bounded by two marginal basins, the South China Sea to the North and the Sulu Sea to the South is composed of remnants of an inverted basin (Proto-South China Sea) thrusted onto the margin of a continental terrane which rifted away from the Chinese-Vietnamese margin. Based on field observations coupled with seismic and drill-holes data, our study focuses on the structural architecture of the island in order to decipher the geodynamic evolution of the southern margin of the South China Sea. Structurally, the Palawan Island consists of: (i) the Palawan wedge, which extends towards the South China Sea is composed of deformed slope to deep ocean deposits of Cretaceous (north Palawan) to Tertiary (central and south Palawan) ages. This accretionnary wedge is characterized by small wavelength folds of mainly NE-SW trend. Offshore, the unconformable Middle-Late Miocene Tabon limestones unit postdates the last stages of the Palawan wedge growth/setting; (ii) On top of this wedge lie thrust slices of ophiolite bodies comprising ribbon cherts of Albian age as indicated by radiolarians.; these bodies are likely to be relicts of the now-subducted Proto South China Sea; (iii) The central and southern parts of the Palawan island are characterized by a large wavelength antiform of NE-SW trend. This structure is sealed by the slightly tilted Early Pliocene marls unit; (iv) The island also presents necking zones bordered by N-S trending transform faults. This area witnessed the geodynamic evolution of the South East Asia which consists of a succession of opening/closure of oceanic basins and block accretions. The Palawan Island therefore results of the closing of the Proto-South China Sea which once formed both the Palawan accretionary wedge and the overlying ophiolite tectonic slices. During a later compressive event, the rifted continental margin which composes the basement of the Island was inverted, inducing the uplift and the large scale folding

  20. Stratigraphic architecture of the Cryogenian successions of South China

    NASA Astrophysics Data System (ADS)

    Zhu, M.; Yin, Z.; Zhang, J.; Condon, D. J.; Macdonald, F. A.; Liu, P.

    2014-12-01

    Stratigraphy and sedimentology of the Cryogenian glacial successions provide primary data for elucidating climatic change of this critical interval. The Cryogenian strata of South China were deposited in a rift basin, and exhibit dramatic facies change from the basin center to margin, which complicates stratigtraphic correlations. Here we present new sedimentological, geochemical and stratigraphic data based on the detailed analyses of more than ten well exposed sections along a basinward transect from north-south. In the basin center, Cryogenian strata are about 4000 m thick and characterized by two glaciogenic diamictite units separated by a diamictite-free siliciclastic interval. Initiation of the Chang'an glaciation (Sturtian equivalent) is conformable and gradational with dropstones appearing in siltstone at the basal part of the Chang'an Formation followed by a shoaling-up sequence that is interpreted to represent a glacio-eustatic sea-level fall. In the basin center, >600 m of graded beds of siliciclastic rocks and debrites of the Fulu Formation overlie the Chang'an Formation. The Fulu Formation is succeeded by a thin (<10 m) fine-grained siliciclasitic unit with black shale and manganese carbonate at the base, which is assigned to the Datangpo Formation, and massive glacigenic diamitictite of the Marinoan-age Nantuo Formation. On the basin margin, the Datangpo Formation is up to 300 m thick and is underlain by a glaciogentic diamictite (Tiesi'ao/Dongshanfeng/Gucheng Formations). Taking factors of glacial dynamics and active tectonism into account, we develop a facies model to interpret the sedimentology and stratigraphic architecture of these successions. Combined with new geochronological data, our data will provide tests for Cryogenian climatic models.

  1. Groundwater quality in the South Coast Interior Basins, California

    USGS Publications Warehouse

    Parsons, Mary C.; Belitz, Kenneth

    2014-01-01

    Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s untreated groundwater quality and increases public access to groundwater-quality information. The South Coast Interior Basins constitute one of the study units being evaluated.

  2. Water Balance Change in Xia Ying River Basin, Qinghai Province, China

    NASA Astrophysics Data System (ADS)

    Cuo, L.; Zhou, B.; Li, J.

    2010-12-01

    Yellow River, Yangtze River and Lan Cang River are major river systems supporting billions of people in South East Asia and China. Source region of Yellow River, Yangtze River and Lan Cang River (Three Rivers) is located in Qinghai Province, China. Recently, Chinese government started a conservation project in the source region of the Three Rivers called “Convert Agricultural Field to Forest and Grassland”. Xia Ying River Basin is a sub-basin located in the source region of the Three River Basin. The upper Xia Ying River Basin has experienced dramatic land cover change since 2006. Before 2006, upper Xia Ying River Basin hill slope was agricultural field. Coniferous trees and bush vegetation were planted on the slope greater than 70 degree in the upper Xia Ying River Basin in 2006. The objective of the study is to investigate the water balance term change in the Xia Ying River Basin because of the conservation project. This study will use Landsat and MODIS imagery to classify and quantify land cover classes before and after land cover conversion. Water balance terms including runoff and evaportranspiration will be simulated using a land surface model to investigate water balance term change due to land cover change. The study serves as a pilot study for the investigation of hydrological change in the entire source region of the Three River Basin during the past 50 years.

  3. The geologically recent giant impact basins at Vesta's south pole.

    PubMed

    Schenk, Paul; O'Brien, David P; Marchi, Simone; Gaskell, Robert; Preusker, Frank; Roatsch, Thomas; Jaumann, Ralf; Buczkowski, Debra; McCord, Thomas; McSween, Harry Y; Williams, David; Yingst, Aileen; Raymond, Carol; Russell, Chris

    2012-05-11

    Dawn's global mapping of Vesta reveals that its observed south polar depression is composed of two overlapping giant impact features. These large basins provide exceptional windows into impact processes at planetary scales. The youngest, Rheasilvia, is 500 kilometers wide and 19 kilometers deep and finds its nearest morphologic analog among large basins on low-gravity icy satellites. Extensive ejecta deposits occur, but impact melt volume is low, exposing an unusual spiral fracture pattern that is likely related to faulting during uplift and convergence of the basin floor. Rheasilvia obliterated half of another 400-kilometer-wide impact basin, Veneneia. Both basins are unexpectedly young, roughly 1 to 2 billion years, and their formation substantially reset Vestan geology and excavated sufficient volumes of older compositionally heterogeneous crustal material to have created the Vestoids and howardite-eucrite-diogenite meteorites.

  4. The geologically recent giant impact basins at Vesta's south pole.

    PubMed

    Schenk, Paul; O'Brien, David P; Marchi, Simone; Gaskell, Robert; Preusker, Frank; Roatsch, Thomas; Jaumann, Ralf; Buczkowski, Debra; McCord, Thomas; McSween, Harry Y; Williams, David; Yingst, Aileen; Raymond, Carol; Russell, Chris

    2012-05-11

    Dawn's global mapping of Vesta reveals that its observed south polar depression is composed of two overlapping giant impact features. These large basins provide exceptional windows into impact processes at planetary scales. The youngest, Rheasilvia, is 500 kilometers wide and 19 kilometers deep and finds its nearest morphologic analog among large basins on low-gravity icy satellites. Extensive ejecta deposits occur, but impact melt volume is low, exposing an unusual spiral fracture pattern that is likely related to faulting during uplift and convergence of the basin floor. Rheasilvia obliterated half of another 400-kilometer-wide impact basin, Veneneia. Both basins are unexpectedly young, roughly 1 to 2 billion years, and their formation substantially reset Vestan geology and excavated sufficient volumes of older compositionally heterogeneous crustal material to have created the Vestoids and howardite-eucrite-diogenite meteorites. PMID:22582256

  5. Basin-mountain structures and hydrocarbon exploration potential of west Junggar orogen in China

    NASA Astrophysics Data System (ADS)

    Wu, X.; Qi, X.; Zheng, M.

    2015-12-01

    Situated in northern Xinjiang, China, in NE-SW trend, West Junggar Orogen is adjacent to Altai fold belt on the north with the Ertix Fault as the boundary, North Tianshan fold belt on the south with the Ebinur Lake Strike-slip Fault as the boundary, and the Junggar Basin on the southeast with Zaire-Genghis Khan-Hala'alat fold belt as the boundary. Covering an area of about 10×104 km2 in China, there are medium and small intermontane basins, Burqin-Fuhai, Tacheng, Hefeng and Hoxtolgay, distributing inside the orogen. Tectonically West Junggar Orogen lies in the middle section of the Palaeo-Asian tectonic domain where the Siberia, Kazakhstan and Tarim Plates converge, and is the only orogen trending NE-SW in the Palaeo-Asian tectonic domain. Since the Paleozoic, the orogen experienced pre-Permian plate tectonic evolution and post-Permian intra-plate basin evolution. Complex tectonic evolution and multi-stage structural superimposition not only give rise to long term controversial over the basin basement property but also complex basin-mountain coupling relations, structures and basin superimposition modes. According to analysis of several kinds of geological and geophysical data, the orogen was dominated by compressive folding and thrust napping from the Siberia plate in the north since the Late Paleozoic. Compressive stress weakened from north to south, corresponding to subdued vertical movement and enhanced horizontal movement of crustal surface from north to south, and finally faded in the overthrust-nappe belt at the northwest margin of the Junggar Basin. The variation in compressive stress is consistent with the surface relief of the orogen, which is high in the north and low in the south. There are two kinds of basin-mountain coupling relationships, i.e. high angle thrusting and overthrusting and napping, and two kinds of basin superimposition modes, i.e. inherited and progressive, and migrating and convulsionary modes. West Junggar orogen has rich oil and gas

  6. VIEW OF SOUTH STORAGE BASIN NUMBER 1 OF FUEL STORAGE ...

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

    VIEW OF SOUTH STORAGE BASIN NUMBER 1 OF FUEL STORAGE BUILDING (CPP-603). PHOTO TAKEN LOOKING NORTHEAST. INL PHOTO NUMBER HD-54-18-4. Mike Crane, Photographer, 8/2005 - Idaho National Engineering Laboratory, Idaho Chemical Processing Plant, Fuel Reprocessing Complex, Scoville, Butte County, ID

  7. RAINFALL-RUNOFF MECHANICS FOR DEVELOPED URBAN BASINS, SOUTH FLORIDA.

    USGS Publications Warehouse

    Miller, Robert A.

    1984-01-01

    Rainfall-runoff data, collected by the US Geological Survey as part of an urban hydrology study in south Florida, were analyzed to find relations between depths of rainfall and basin runoff. Data were collected for about 300 runoff events on four different urban land-use basins - commercial, highway, single-family residential, and apartment. These data were collected from sewers that carried only stormwater runoff. In analyzing the rainfall-runoff data, three types of relations were found. A one-curve, linear relation occurred for the commercial basin that has 98 percent of the basin as hydraulically effective impervious area. A two-curve, intercepted relation occurred for the highway basin - a linear curve for the low and medium events observed and a second-degree curve for high events observed. A two-curve, disjointed relation occurred for the remaining two basins - the residential basin and the apartment basin. This relation also contained a linear curve for low and medium events and a second-degree curve for the high events. However, the two curves do not intersect, but are disjointed.

  8. Opportunities, problems seen in China's remote Tarim basin

    SciTech Connect

    Not Available

    1993-04-12

    China's offering of onshore blocks in the vast Tarim basin for competitive bidding by foreign firms has created significant opportunities for international oil companies. This article describes the Tarim basin potential and the planned pipeline, and gives details about key exploration contract issues and elements. Reserve estimates range from 10 to 30 billion bbl of oil.

  9. First record of Podocarpoid fossil wood in South China

    PubMed Central

    Li, Long; Jin, Jian-Hua; Quan, Cheng; Oskolski, Alexei A.

    2016-01-01

    A new species of fossil conifer wood, Podocarpoxylon donghuaiense sp. nov., is described from the late Eocene of Nadu Formation in Baise Basin of the Guangxi Province, South China. This fossil wood is characterized by distinct growth rings, circular to oval tracheids in cross section, 1–2-seriate opposite pits on radial tracheid walls, uniseriate (rarely biseriate) rays, smooth end walls of ray parenchyma cells, and the absence of resin ducts, suggesting its affinity to Podocarpaceae. The new species is distinctive from other Cenozoic woods ascribed to this family by the combination of distinctive growth rings, the absence of axial parenchyma, the occurrence of bordered pits on tangential tracheid walls, and the occurrence of 3–4 cuppressoid or taxodioid pits on cross-fields. This represents the first record of podocarpoid fossil wood in South China and provides fossil evidence for the early dispersal and diversification of Podocarpaceae in eastern Asia as well as for mild temperate seasonal climate in this region during the late Eocene. PMID:27571780

  10. First record of Podocarpoid fossil wood in South China.

    PubMed

    Li, Long; Jin, Jian-Hua; Quan, Cheng; Oskolski, Alexei A

    2016-01-01

    A new species of fossil conifer wood, Podocarpoxylon donghuaiense sp. nov., is described from the late Eocene of Nadu Formation in Baise Basin of the Guangxi Province, South China. This fossil wood is characterized by distinct growth rings, circular to oval tracheids in cross section, 1-2-seriate opposite pits on radial tracheid walls, uniseriate (rarely biseriate) rays, smooth end walls of ray parenchyma cells, and the absence of resin ducts, suggesting its affinity to Podocarpaceae. The new species is distinctive from other Cenozoic woods ascribed to this family by the combination of distinctive growth rings, the absence of axial parenchyma, the occurrence of bordered pits on tangential tracheid walls, and the occurrence of 3-4 cuppressoid or taxodioid pits on cross-fields. This represents the first record of podocarpoid fossil wood in South China and provides fossil evidence for the early dispersal and diversification of Podocarpaceae in eastern Asia as well as for mild temperate seasonal climate in this region during the late Eocene. PMID:27571780

  11. Sample return from the lunar South Pole-Aitken Basin

    NASA Astrophysics Data System (ADS)

    Duke, M. B.

    2003-06-01

    Automated sample return missions to the South Pole — Aitken Basin on the lunar far side are proposed as the best means of addressing major problems concerning the early impact history of the inner solar system, the nature of very large impact events, and the early differentiation of rocky planets. The opportunity to propose such missions has been opened by the recommendations of the U. S. National Research Council's Decadal Study of Solar System Exploration and the creation by NASA of the New Frontiers Program, which will support missions of intermediate cost, between the Discovery Program and large missions. A proposal for a South Pole — Aitken Basin Sample Return Mission was submitted to the Discovery Program in 2000, but not fimded. The New Frontiers Program, with a somewhat less stringent budget constraint, should allow several of the potential risks associated with the Discovery proposal to be addressed, including scientific and programmatic risks. A principal goal of current mission studies is to determine whether, within the New Frontiers Program's cost constraints, two separate samples could be collected from areas of different post-Basin geological history. If accepted by the New Frontiers Program, a South Pole — Aitken Basin sample return mission could be flown as early as 2008-2009.

  12. Genetic type of natural gas in Ya13-1 gas field, South China Sea

    SciTech Connect

    Zhang Gang

    1995-08-01

    Ya13-1 is one of the largest gas field ever found in China in recent years. Studying on the genetic type of natural gas in the field is one of the key factors to determine the regional hydrocarbon potential--Qiongdongnan Basin and Yinggerhaii Basin, northwest part of South China Sea. Series of geochemical methods have been undertook including the analysis of the chemical composition of the natural gas and their isotopic ratio discussed in this paper. Other related studied including geological settings, gas-source correlations, geochemistry of the condensates and extractable compounds of source rocks, and thermal simulation and evaluation of the marine shales provides further informations. It is noticeable that the higher content of mercury (44000 ng/cubic meter) and aromatics such as benzene and toluene may be related to the joint of condensates, which derived from coal-bearing Oligocene shales in the adjacent Qingdingnan Basin. Studies show that the natural gas in Ya13-1 gas field belong to high to post mature non-associated gas derived in marine source rocks, and mainly come from Oligocene to Pliocene marine shales in Yinggerhai Basin. This is quite different with the former studies, which believe the gas derived from Oligocene coal-bearing strata of Yacheng formation, Qiongdongnan Basin. The new results of the studies make sure further a pretty good potential of gas resources in the northwest part ofSouth China Sea.

  13. South Atlantic sag basins: new petroleum system components

    SciTech Connect

    Henry, S.G. Mohriak, W.U.; Mello, M.R.

    1996-08-01

    Newly discovered pre-salt source rocks, reservoirs and seals need to be included as components to the petroleum systems of both sides of the South Atlantic. These new components lie between the pre-salt rift strata and the Aptian salt layers, forming large, post-rift, thermal subsidence sag basins. These are differentiated from the older rift basins by the lack of syn-rift faulting and a reflector geometry that is parallel to the base salt regional unconformity rather than to the Precambrian basement. These basins are observed in deep water regions overlying areas where both the mantle and the crust have been involved in the extension. This mantle involvement creates post-rift subsiding depocenters in which deposition is continuous while proximal rift-phase troughs with little or no mantle involvement are bypassed and failed to accumulate potential source rocks during anoxic times. These features have been recognized in both West African Kwanza Basin and in the East Brasil Rift systems. The pre-salt source rocks that are in the West African sag basins were deposited in lacustrine brackish to saline water environment and are geochemically distinct from the older, syn-rift fresh to brackish water lakes, as well as from younger, post-salt marine anoxic environments of the drift phase. Geochemical analyses of the source rocks and their oils have shown a developing source rock system evolving from isolated deep rift lakes to shallow saline lakes, and culminating with the infill of the sag basin by large saline lakes to a marginally marine restricted gulf. Sag basin source rocks may be important in the South Atlantic petroleum system by charging deep-water prospects where syn-rift source rocks are overmature and the post-salt sequences are immature.

  14. South Caspian Pliocene-Anthropogenic basin (summary of existing views)

    NASA Astrophysics Data System (ADS)

    Amrakhov, Rashad; Shiraliyeva, Sevinj; Kerimova, Nailya

    2016-04-01

    On the basis of long-time integrated sedimentology, paleogeographic and structural - formation studies covering Pliocene-Anthropogenic sediments of South Caspian Basin (SCB) and design of structural - formation, paleogeographic and catagenetic models applying geophysical studies in the region, the author has interred rift nature on this basin during Pliocene-Anthropogenic stage of its evolution. It is assumed that SCB is intercontinental with absence of continental crust. Evolution of SCR started from Miocene, continental stage of development Lesser and Great Caucasus and Kopetdag. At initial stage of South Caspian rift-graben evolution the crystal uplift of Caucasus, Kopetdag and Talysh organic system took place. Extension forces within their borders caused collapse of central part of South Caspian block. We assumed that at later stage folded blocks of Lesser Caucasus and Talysh on the other hand Alborz and Kopetdagh on the other were moving apart. As a result of these riftogene processes the contemporary structure of SCB Antropogene was formed. Starting from Miocene, subsidence of central part of SCB and later movements of folded blocks of Great and Lesser Caucasus, Talysh and Elbrus occurred along Western Caspian, Sangachal - Ogurcghy deep faults and Turkmenistan thrust. During rift generation within SCB, magmatic troughs emerged in the rift zone - South Absheron, Lower Kura. Enzaly and Western Turkmenistan. Structural-formation studies with application of geophysical data acquired in the region, allow assuming that massive Godina can be considered as interrift horst with large gravity anomaly. Its generation relates to Miocene-Pliocene ages and was formed due to South Caspian riftogenesis. The following are sedimentologic evidences of South Caspian rift basin: a) Avalanche sedimentation and development of large thickness (2.5-3 km/106 years) even within border of Lower Pliocene (Productive Series); b) Morphology of Lower Pliocene molasses formation covering 600

  15. Modern sedimentation and extreme event in the South China Sea

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Huang; Su, Chih-Chieh

    2016-04-01

    The South China Sea is the largest marginal sea of the northwest Pacific. It is situated at the plate boundary of the Eurasian, Philippine Sea, and Indian plates and also on the North Western Pacific corridor of typhoons. The unique tectonic and climatic environment makes it has to face the potential of seafloor destructions, like submarine landslides and slumps, and high sediment discharges which induced by typhoon from Philippine. In this study, we analysis the sediment properties of modern extreme event records in cores and attempt to evaluate the history of extreme events in the South China Sea. Twelve gravity cores were collected in the central South China Sea basin and around Taiping island by using R/V Ocean Research 1 from 2014 to 2015 and a series of analysis including multi-sensor core logger, XRF core scanner (Itrax), core surface images, X-radiographs, bulk density, grain size, Pb-210 chronology and X-ray diffractometer were conducted in this study. On core surface images, an obvious brownish oxidized layer exist in core top with higher Pb-210 activity beneath this oxidized layer, and we speculate this layer is caused by nature hazard. According to the sampling time, we conjecture the oxidized layer might formed by typhoon Haiyan in 2013. In addition, the Itrax data shows high manganese content only exist in this layer which might related to the modern industrial pollution delivered by typhoon induced flooding from Philippine. The sedimentation rate of the non-event years in these cores which derived from Pb-210 chronology method is about 0.02 ~0.03 cm/yr. On contrary, the event layer caused by Haiyan with a recorded maximum 87cm deposits in the South China Sea. This study aims to characterize the typhoon induced deposits in the turbidite layer and use it to identify whether the other event layers recorded in these cores were related to typhoon activities and to reconstruct the strong tropical cyclone history in the western Pacific.

  16. Open Ocean Internal Waves, South China Sea

    NASA Technical Reports Server (NTRS)

    1989-01-01

    These open ocean internal waves were seen in the south China Sea (19.5N, 114.5E). These sets of internal waves most likely coincide with tidal periods about 12 hours apart. The wave length (distance from crest to crest) varies between 1.5 and 5.0 miles and the crest lengths stretch across and beyond this photo for over 75 miles. At lower right, the surface waves are moving at a 30% angle to the internal waves, with parallel low level clouds.

  17. Implication of drainage basin parameters of a tropical river basin of South India

    NASA Astrophysics Data System (ADS)

    Babu, K. J.; Sreekumar, S.; Aslam, Arish

    2016-03-01

    Drainage morphometry provides quantitative description of the drainage system which is an important aspect of the characterisation of watersheds. Chalakudi River is one of the important rivers of the South India which has attracted attention of many environmental scientists recently because of the proposed Athirapally Hydel Project across the river. SRTM (Shuttle Radar Topographic Mission) data were used for preparing DEM (Digital Elevation Model), Aspect Map and Slope Map. Geographical Information System (GIS) was used for the evaluation of linear, areal and relief aspects of morphometric parameters. The study reveals that the terrain exhibits dentritic and trellis pattern of drainage. The Chalakudi River Basin has a total area of 1,448.73 km2 and is designated as seventh-order basin. The drainage density of the basin is estimated as 2.54 and the lower-order streams mostly dominate the basin. The high basin relief indicates high runoff and sediment transport. The elongation ratio of the Chalakudi Basin is estimated as 0.48 and indicates that the shape of the basin is elongated. The development of stream segments in the basin area is more or less effected by rainfall. Relief ratio indicates that the discharge capability of watershed is very high and the groundwater potential is meagre. The low value of drainage density in spite of mountainous relief indicates that the area is covered by dense vegetation and resistant rocks permeated by fractures and joints. These studies are helpful in watershed development planning and wise utilization of natural resources.

  18. Geodynamic Evolution of the Northeastern South China Sea

    NASA Astrophysics Data System (ADS)

    Yeh, Y.; Sibuet, J.; Hsu, S.; Liu, C.

    2008-12-01

    We present a geodynamic evolution model of the northeastern South China Sea (SCS) updated the kinematic context based on a re-interpretation and analysis of all available magnetic data. Using the latest available multi-channel seismic data, two significant tectonic phases T1 and T2 were identified in the northeastern SCS. T1 is a slight tensional tectonic event and T2 is a major compressive event. In the absence of the drilling data in the deep basin, the identification of the magnetic anomalies, the age of major unconformities at ODP Sites 1146 and 1148 drilled on the northeastern SCS margin as well as a re- interpretation of the tectonic subsidence curve based on drilled holes in the west Taiwan basins provided age constraints for dating these two tectonic events. Tensional phase T1 is characterized by tilted blocks and fan-shaped deposits developed shortly (8-10 Ma) after the onset of SCS oceanic domain (37.8 Ma). It corresponds to the first ENE-WSW to E-W change in spreading directions, which occurred around chron C10 (~28.7 Ma). Tectonic phase T2 is characterized by the uplift of ENE-WSW rift features and NE-SW transverse features associated with the major plate reorganization in East Asia and a northeast shift of the Ryukyu subduction zone from the Luzon-Ryukyu transform plate boundary (LRTPB) to east of the present- day position of Taiwan, which occurred 17-18 Ma ago. As the T2 intra-plate compressive deformation only occurred south of the LRTPB, we suggest that the slab pull effect of the dead slab might have been transmitted to the oceanic crust south of the already inactive LRTPB.

  19. Detrital zircon provenance of the Paleogene syn-rift sediments in the northern South China Sea

    NASA Astrophysics Data System (ADS)

    Shao, Lei; Cao, Licheng; Pang, Xiong; Jiang, Tao; Qiao, Peijun; Zhao, Meng

    2016-02-01

    The early rift sedimentation history of the South China Sea is still not well understood due to restricted borehole coverage of the Paleogene strata and lack of reliable stratigraphic dating. We use detrital zircon U-Pb geochronology to explore the source-to-sink characteristics of syn-rift sequences in the northern South China Sea. The results reveal significant intrabasinal provenances in addition to the well-perceived terrigenous supply from the north. The Dongsha Uplift is considered to account for the dominance of the Early Cretaceous zircons in the Eocene samples. The Lower Oligocene sediments in the Qiongdongnan Basin could have been sourced from Hainan Island and local uplifts, but their distinction cannot be confirmed by the U-Pb age spectra. Contemporary sediments in the northern Pearl River Mouth Basin were most likely transported from southeastern South China with well-rounded zircon grains showing U-Pb age similarity to those from the northeastern tributaries of the Pearl River. By contrast, intrabasinal sources from the west and east are suggested to have contributed the infill of the southern part of the Pearl River Mouth Basin based on generally euhedral zircon shapes. These sedimentary source patterns appear to change very little in the Oligocene northern South China Sea. However, the newly detected Neoproterozoic zircons in the Upper Oligocene sediments from borehole L21 tend to indicate a southern source. The episodic and diachronic nature of rifting and erosion processes in the early South China Sea is the cause of complex patterns in the Paleogene provenance history.

  20. Mapping structures of the South China Sea; a synthesis

    NASA Astrophysics Data System (ADS)

    Pubellier, Manuel; Savva, Dimitri; Aurelio, Mario; Yan, Qiu; Phach Phung, Van; Franke, Dieter; Rahman, Hadi A.; Mansor, Yazid M.; Auxiètre, Jean Luc; Meresse, Florian; Delescluse, Matthias; Pichot, Thibaud; Chan, Lung Sang; Le Gal, Virginie; Xin, Nie

    2015-04-01

    The South China Sea margin has been the focus of scientific interest in the past decade including ODP and IODP drilling, oil and gas exploration, and projects from several international teams onshore and offshore. The South China Sea, because of its narrow V shape oceanic crust, the wide extension of its rifted continental crust, and the various styles of rifting is an interesting playground to study the formation of passive margins. We present a synthesis of the main characteristics of the SCS on a structural map focused on the Late Mesozoic and Cenozoic features. The basement, similar in China, Vietnam and part of the western Philippines is undifferentiated. The Mesozoic location of the area was on the upper plate of a subduction zone, resulting in an impressive coverage of Cretaceous granites sometimes separated by narrow Cretaceous molasse basins. These granitic bodies, widespread offshore in the extended crust conditioned the location of the extension via large detachments and normal faults; later cut by steeper faults. The geometries of the faults vary from E-W to NE-SW indicating that the rifting underwent several stages with different stretching directions and a varying degree of extension which ultimately exhumed the mantle. Some faults are low angle detachments and therefore surround the granitic/metamorphic basement structures with an E-W general trend. Platform and reef carbonates occupy some of the bathymetric highs and developed mainly during Late Oligocene to Mid Miocene times and during Late Miocene times. The map also illustrates the coverage of the different units of the NW Borneo wedge, which actually develops offshore in the SE SCS and shifts to the NW of the Sulu Sea. Onshore Borneo, the sub-aerial conditions for the NW Borneo wedge resulted in intense erosion and deltas formation.

  1. Sampling South Pole-Aitken Basin: The Moonrise Approach

    NASA Technical Reports Server (NTRS)

    Jolliff, B. L.; Shearer, C. K.; Cohen, B. A.

    2012-01-01

    The South Pole-Aitken basin (SPA) is the largest of the giant impact basins in the inner Solar System, and its location on Earth s Moon makes it the most accessible. Exploration of SPA through direct collection and analysis of representative materials addresses issues as fundamental as the characteristics of the chemical reservoir from which the Moon originated, early differentiation and production of crust and development of global asymmetry, relationships between magmatic activity and internal thermal evolution, and effects of giant impact events on the terrestrial planets. Owing to its great size and superposition relationships with other lunar impact basins, SPA is the oldest and as such anchors the lunar chronology. Moreover, numerous large impact craters and basins are contained within it such that materials (rocks) of the SPA basin contain a record of the early impact chronology, one less likely to have been affected by the large, late nearside basins (e.g., Imbrium). Understanding the early basin chronology is key to deciphering the sequence and effects of early giant impact bombardment of the inner Solar System. That record exists on the Moon, and materials of the SPA basin will allow us to read that record. Knowledge of the early bombardment history will test - and may reshape - a key paradigm relating to early Solar System evolution. Did the planets form with the alignment of today, or was there a major reorientation of the giant planets that led to destabilization of asteroid orbits, and a cataclysmic bombardment of the inner Solar System hundreds of millions of years after accretion of the planets? Implications include understanding environments for early life-supporting habitats on Earth and Mars, and relationships to new observations of extra-solar planetary systems.

  2. Early Cambrian ocean anoxia in South China.

    PubMed

    Jiang, Shao-Yong; Pi, Dao-Hui; Heubeck, Christoph; Frimmel, Hartwig; Liu, Yu-Ping; Deng, Hai-Lin; Ling, Hong-Fei; Yang, Jing-Hong

    2009-06-11

    The cause of the most marked changes in the evolution of life, which define the first-order stratigraphic boundary between the Precambrian and the Phanerozoic eon, remains enigmatic and a highly topical subject of debate. A global ocean anoxic event, triggered by large-scale hydrogen sulphide (H(2)S) release to surface waters, has been suggested by Wille et al., on the basis of two data sets from South China and Oman, to explain the fundamental biological changes across the Precambrian/Cambrian (PC/C) boundary. Here we report a new precise SHRIMP U-Pb zircon age of 532.3 +/- 0.7 million years (Myr) ago (Fig. 1) for a volcanic ash bed in the critical unit that reflects the ocean anoxic event, the lowermost black shale sequence of the Niutitang Formation in the Guizhou Province, South China. This age is significantly younger than the precise PC/C boundary age of 542.0 +/- 0.3 Myr ago, approximately 10 Myr younger than the extinction of the Ediacaran fauna, and thus challenging the view of a major ocean anoxic event having been responsible for the major changes in the direction of evolution at the PC/C boundary. PMID:19516284

  3. Source of atmospheric moisture and precipitation over China's major river basins

    NASA Astrophysics Data System (ADS)

    Zhao, Tongtiegang; Zhao, Jianshi; Hu, Hongchang; Ni, Guangheng

    2016-03-01

    Oceanic evaporation via the East Asian Monsoon (EAM) has been regarded as the major source of precipitation over China, but a recent study estimated that terrestrial evaporation might contribute up to 80% of the precipitation in the country. To explain the contradiction, this study presents a comprehensive analysis of the contribution of oceanic and terrestrial evaporation to atmospheric moisture and precipitation in China's major river basins. The results show that from 1980 to 2010, the mean annual atmospheric moisture (precipitable water) over China was 13.7 mm, 39% of which originates from oceanic evaporation and 61% from terrestrial evaporation. The mean annual precipitation was 737 mm, 43% of which originates from oceanic evaporation and 57% from terrestrial evaporation. Oceanic evaporation makes a greater contribution to atmospheric moisture and precipitation in the East Asian Monsoon Region in South and East China than terrestrial evaporation does. Particularly, for the Pearl River and southeastern rivers, oceanic evaporation contributes approximately 65% of annual precipitation and more than 70% of summer precipitation. Meanwhile, terrestrial evaporation contributes more precipitation in northwest China due to the westerly wind. For the northwestern rivers, terrestrial evaporation from the Eurasian continents contributes more than 70% of precipitation. There is a linear relation between mean annual precipitation and the contribution of oceanic evaporation to precipitation, with a correlation coefficient of 0.92, among the ten major river basins in China.

  4. Winter precipitation change in South China in recent decades

    NASA Astrophysics Data System (ADS)

    Cai, Jingning

    2013-04-01

    Precipitation change is one of important climate researches in China, but winter precipitation variation in South China has not been studied so frequently. In China, it is rainy when hot; so summer precipitation is usually one focus in research, esp. in South China. However, winter precipitation and its change influence people profoundly in South China, also. The most recent example is what happened over South China in winter 2008. In this winter, millions of people suffered from the unusual cold and snowy winter. It led to huge loss in economy and traffic as well. Roads closed and railway stations were jammed and crowded with people; many planes were grounded for heavy snow and bad weather. Transmission lines faulted in the mountains. The ommunication signals were affected. Everyday food supply including vegetables and meats had to be delayed or interrupted. In some city even water supply was interrupted. And garbage in the city was piled up. Just in this winter the snow depth and coverage area in many places in South China broke or equaled the historical records. In fact, it isn't the only one unusual winter precipitation event in South China. Since 1950s, several freezing and snowy winters struck the South in China. In this research, winter precipitation change in recent years in South China has been discussed based on the precipitation observations. The associated large scale atmospheric circulation change is also analyzed. It is found that snowy winter in South China hardly comes in most periods of 2000s, but in recent decades this heavy snow in winter has appeared several times as observations shows. This phenomenon could be related to the large scale atmospheric circulation change.

  5. Anomalous subsidence at South China Sea rifted margin: Sediments digging their own hole

    NASA Astrophysics Data System (ADS)

    Brune, Sascha; Clift, Peter; Quinteros, Javier

    2015-04-01

    Rifted continental margins subside as a consequence of combined crustal thinning and mantle lithosphere cooling. While standard models predict a slowing of subsidence after the end of rifting, the deep basins on the northern margin of the South China Sea, notably the Baiyun Sag exhibit subsidence that accelerated several million years after the end of active extension. Additionally, backstripping analysis at the South China margin has shown that the amount of subsidence is much greater than that predicted from the degree of brittle upper crustal extension seen in seismic profiles. Here we explain these observations by linking climate change onshore and deformation of the crystalline crust offshore: Early Miocene monsoon intensification increased erosion and thus the sediment flux to offshore basins after the cessation of active extension. When the sediment load encountered the weak crust of the South China Sea margin, it induced lower crustal flow away from the basin axis so that the deep Baiyun basin was formed nearly without brittle extension. We corroborate this concept using seismic observations and backstripping techniques, as well as thermo-mechanical forward modeling. The numerical forward model is a 2D version of the finite element code SLIM3D. The code includes nonlinear temperature- and stress-dependent elasto-visco-plastic rheology and is able to reproduces a wide range of rift-related deformation processes such as flexure, lower crustal flow, and faulting. We find that two factors allow to satisfy the observational constraints: (1) Post-rift increase of sediment load: The East Asian Summer Monsoon strengthened around the start of the Miocene (~23 Ma), several million years after continental rupture. Changes in the flora of continental China date from around this time and sedimentation rates across continental margins and deltas in South and Southeast Asia increased, as might be expected under the influence of heavier precipitation driving faster erosion

  6. Sequence stratigraphy and continental margin development of the northwestern shelf of the South China Sea

    SciTech Connect

    Chen, P.P.H. ); Zhi Yuong Chen; Qi Min Zhang )

    1993-05-01

    Based on the sequence stratigraphic analyses of the Tertiary in the northwestern continental margin of the South China Sea, this paper summarizes the regional tectonics and their influences on the basin developments and discusses the systems tract distributions through the continental margin growth. The study area is underlain by two Tertiary basins separated by a major basin boundary fault across which two distinctly different basin structural styles developed. The Qiongdongnan basin shows characteristic rift structures and is closely related to the opening of the South China Sea. The Yinggehai basin is filled with thick Neogene monoclines overlying basement without apparent rift structures. The Yinggehai's genesis has been linked to the tectonism along the Red River suture zone. The margin development is characterized by depositional environments of sediment influx constantly exceeding accommodation space. Under these environments, the highstand deltas frequently developed near shelf edges, where vertically stacked shallow water sands of both highstand deltas and lowstand wedges/deltas could produce favorable exploration targets. High rates of sedimentation in the study area allow the identification of fourth-order cyclicity in the Quaternary. Regional sequence stratigraphic correlations suggest that many sequence boundaries appear to be synchronous, but not all boundaries exist in all basins along the eastern and southern continental margins of mainland China. The margin evolved through the repeated development of lowstand fans, lowstand wedges, transgressive systems tracts, and highstand deltas. Prior to the Pliocene, the shelf was sourced both from Vietnam and Hainan Island and, as a result, two shelf margins developed. The southwestern margin stopped growing in the late Miocene, and the northern margin continued to prograde with possible additional sediment inputs through the Red River system in the Quaternary. 29 refs., 22 figs.

  7. Basin-mountain structures and hydrocarbon exploration potential of west Junggar orogen in China

    NASA Astrophysics Data System (ADS)

    Wu, Xiaozhi; He, Dengfa; Qi, Xuefeng

    2016-04-01

    Situated in northern Xinjiang, China, in NE-SW trend, West Junggar Orogen is adjacent to Altai fold belt on the north with the Ertix Fault as the boundary, North Tianshan fold belt on the south with the Ebinur Lake Strike-slip Fault as the boundary, and the Junggar Basin on the southeast with Zaire-Genghis Khan-Hala'alat fold belt as the boundary. Covering an area of about 10×104 km2 in China, there are medium and small intermontane basins, Burqin-Fuhai, Tacheng, Hefeng and Hoxtolgay, distributing inside the orogen. Tectonically West Junggar Orogen lies in the middle section of the Palaeo-Asian tectonic domain where the Siberia, Kazakhstan and Tarim Plates converge, and is the only orogen trending NE-SW in the Palaeo-Asian tectonic domain. Since the Paleozoic, the orogen experienced pre-Permian plate tectonic evolution and post-Permian intra-plate basin evolution. Complex tectonic evolution and multi-stage structural superimposition not only give rise to long term controversial over the basin basement property but also complex basin-mountain coupling relations, structures and basin superimposition modes. According to analysis of several kinds of geological and geophysical data, the orogen was dominated by compressive folding and thrust napping from the Siberia plate in the north since the Late Paleozoic. Compressive stress weakened from north to south, corresponding to subdued vertical movement and enhanced horizontal movement of crustal surface from north to south, and finally faded in the overthrust-nappe belt at the northwest margin of the Junggar Basin. The variation in compressive stress is consistent with the surface relief of the orogen, which is high in the north and low in the south. There are two kinds of basin-mountain coupling relationships, i.e. high angle thrusting and overthrusting and napping, and two kinds of basin superimposition modes, i.e. inherited and progressive, and migrating and convulsionary modes. West Junggar orogen has rich oil and gas

  8. Changes and Relationships of Climatic and Hydrological Droughts in the Jialing River Basin, China.

    PubMed

    Zeng, Xiaofan; Zhao, Na; Sun, Huaiwei; Ye, Lei; Zhai, Jianqing

    2015-01-01

    The comprehensive assessment of climatic and hydrological droughts in terms of their temporal and spatial evolutions is very important for water resources management and social development in the basin scale. To study the spatial and temporal changes of climatic and hydrological droughts and the relationships between them, the SPEI and SDI are adopted to assess the changes and the correlations of climatic and hydrological droughts by selecting the Jialing River basin, China as the research area. The SPEI and SDI at different time scales are assessed both at the entire Jialing River basin and at the regional levels of the three sub basins. The results show that the SPEI and SDI are very suitable for assessing the changes and relationships of climatic and hydrological droughts in large basins. Based on the assessment, for the Jialing River basin, climatic and hydrological droughts have the increasing tendency during recent several decades, and the increasing trend of climatic droughts is significant or extremely significant in the western and northern basin, while hydrological drought has a less significant increasing trend. Additionally, climatic and hydrological droughts tend to increase in the next few years. The results also show that on short time scales, climatic droughts have one or two months lag impact on hydrological droughts in the north-west area of the basin, and have one month lag impact in south-east area of the basin. The assessment of climatic and hydrological droughts based on the SPEI and SDI could be very useful for water resources management and climate change adaptation at large basin scale. PMID:26544070

  9. Changes and Relationships of Climatic and Hydrological Droughts in the Jialing River Basin, China

    PubMed Central

    Zeng, Xiaofan; Zhao, Na; Sun, Huaiwei; Ye, Lei; Zhai, Jianqing

    2015-01-01

    The comprehensive assessment of climatic and hydrological droughts in terms of their temporal and spatial evolutions is very important for water resources management and social development in the basin scale. To study the spatial and temporal changes of climatic and hydrological droughts and the relationships between them, the SPEI and SDI are adopted to assess the changes and the correlations of climatic and hydrological droughts by selecting the Jialing River basin, China as the research area. The SPEI and SDI at different time scales are assessed both at the entire Jialing River basin and at the regional levels of the three sub basins. The results show that the SPEI and SDI are very suitable for assessing the changes and relationships of climatic and hydrological droughts in large basins. Based on the assessment, for the Jialing River basin, climatic and hydrological droughts have the increasing tendency during recent several decades, and the increasing trend of climatic droughts is significant or extremely significant in the western and northern basin, while hydrological drought has a less significant increasing trend. Additionally, climatic and hydrological droughts tend to increase in the next few years. The results also show that on short time scales, climatic droughts have one or two months lag impact on hydrological droughts in the north-west area of the basin, and have one month lag impact in south-east area of the basin. The assessment of climatic and hydrological droughts based on the SPEI and SDI could be very useful for water resources management and climate change adaptation at large basin scale. PMID:26544070

  10. Changes and Relationships of Climatic and Hydrological Droughts in the Jialing River Basin, China.

    PubMed

    Zeng, Xiaofan; Zhao, Na; Sun, Huaiwei; Ye, Lei; Zhai, Jianqing

    2015-01-01

    The comprehensive assessment of climatic and hydrological droughts in terms of their temporal and spatial evolutions is very important for water resources management and social development in the basin scale. To study the spatial and temporal changes of climatic and hydrological droughts and the relationships between them, the SPEI and SDI are adopted to assess the changes and the correlations of climatic and hydrological droughts by selecting the Jialing River basin, China as the research area. The SPEI and SDI at different time scales are assessed both at the entire Jialing River basin and at the regional levels of the three sub basins. The results show that the SPEI and SDI are very suitable for assessing the changes and relationships of climatic and hydrological droughts in large basins. Based on the assessment, for the Jialing River basin, climatic and hydrological droughts have the increasing tendency during recent several decades, and the increasing trend of climatic droughts is significant or extremely significant in the western and northern basin, while hydrological drought has a less significant increasing trend. Additionally, climatic and hydrological droughts tend to increase in the next few years. The results also show that on short time scales, climatic droughts have one or two months lag impact on hydrological droughts in the north-west area of the basin, and have one month lag impact in south-east area of the basin. The assessment of climatic and hydrological droughts based on the SPEI and SDI could be very useful for water resources management and climate change adaptation at large basin scale.

  11. Basin modeling of Jambi Subbasin, South Sumatra, Indonesia

    SciTech Connect

    Halik, N. ); Wu, C. )

    1994-07-01

    The Jambi Subbasin is part of the South Sumatra Basin, a Tertiary back-arc basin formed by the collision between the Sundaland and Indian Plate. The Oligocene synrift Lahat Formation, and the Miocene postrift Talang Akar, Batu Raja, Gumai, and Air Benakat formations are stratigraphic intervals for potential hydrocarbon exploration. Most of the hydrocarbons have been produced from the Talang Akar and Air Benakat formations. Detailed age-depth relationship, paleobathymetry, and eustatic sea level were studied for 11 wells. Degrees of transgression and regression, and relative movement of fault blocks were predicted from rates of total and tectonic subsidence. The structural evolution of the Jambi Subbasin was reconstructed using the backstripping method. Results from the burial history modeling have helped in predicting thermal maturity, hydrocarbon generation, and structural development of the Jambi Subbasin. The timing of basement uplifting started from middle-late Miocene and reached the maximum in Pliocene-Pleistocene. Two hydrocarbon migration and accumulation mechanisms were proposed. In the depocenter, hydrocarbons were generated, migrated upward along faults, and trapped in the middle Miocene Air Benakat Formation, whereas in the basin flanks, hydrocarbons were migrated laterally from the depocenter and trapped in the Oligocene Talang Akar Formation. The methodology of this study can be applied to other subbasins in South Sumatra.

  12. Zooplankton Distribution in Tropical Reservoirs, South China

    NASA Astrophysics Data System (ADS)

    Lin, Qiu-Qi; Duan, Shun-Shan; Hu, Ren; Han, Bo-Ping

    2003-11-01

    The zooplankton of 18 reservoirs of South China was investigated in 2000. 61 Rotifera species, 23 Cladoceras and 14 Copepodas were identified. The most frequent Rotifera genera were Keratella, Brachionus, Trichocerca, Diurella, Ascomorpha, Polyarthra, Ploesoma, Asplanchna, Pompholyx and Conochilus. Bosmina longirostris, Bosminopsis deitersi, Diaphanosoma birgei, D. brachyurum and Moina micrura were typical of Cladocera in the reservoirs. Phyllodiaptomus tunguidus, Neodiaptomus schmackeri and Mesocyclops leuckarti were the most frequent Copepoda and M. leuckarti dominated Copepoda in most reservoirs. High zooplankton species richness with low abundance was characteristic of the throughflowing reservoir, whereas low species richness with low abundance was found in the reservoir with the longest retention time. Relative high abundance and medium species diversity were the distinction of intermediate retention time reservoirs.

  13. DNA barcoding South China Sea fishes.

    PubMed

    Wang, Zhong-Duo; Guo, Yu-Song; Liu, Xue-Mei; Fan, Yan-Bo; Liu, Chu-Wu

    2012-10-01

    We have determined 222 DNA barcode sequences of 95 fish species in 86 genera of 69 families from 15 orders. Fish were captured by trawl from two important fisheries regions in South China Sea: Spratly Islands (Nansha Islands) and Beibu Gulf. The average genetic distances between intraspecies were about 60-fold less than those of interspecies within different taxonomic levels, as Kimura two-parameter genetic distances averaged 17.260% among congeners, 20.097% among genus, and only 0.317% for intraspecific individuals. There were a few examples of deep divergence within species, suggesting the need for further taxonomic work, and a few examples of closely allied species, perhaps reflecting introgressive hybridization. The results provide further evidence for the reliability and accessibility of DNA barcodes for marine fish identification, and also highlight their effectiveness for flagging cases needing taxonomical reexamination.

  14. Rejuvenation of the Kuqa foreland basin, northern flank of the Tarim basin, northwest China

    SciTech Connect

    Lu Huafu; Jia Dong; Cai Dongsheng

    1994-12-01

    The Kuqa depression along the northern flank of the Tarim basin is filled with a thick sequence of Neogene and Quaternary coarse elastic continental sediments. This structural depression is part of a large foreland basin that leads south of the Tianshan - an orogenic belt of intracontinental convergence resulting from the northward propagation of stress following the collision of India with the southern margin of Eurasia. 11 refs., 6 figs., 1 tab.

  15. A note on the South China Sea shallow interocean circulation

    NASA Astrophysics Data System (ADS)

    Fang, Guohong; Dwi, Susanto; Soesilo, Indroyono; Zheng, Quan'an; Qiao, Fangli; Wei, Zexun

    2005-11-01

    The existing estimates of the volume transport from the Pacific Ocean to the South China Sea are summarized, showing an annual mean westward transport, with the Taiwan Strait outflow subtracted, of 3.5±2.0 Sv (1 Sv=106 m3 s-1). Results of a global ocean circulation model show an annual mean transport of 3.9 Sv from the Pacific to the Indian Ocean through the South China Sea. The boreal winter transport is larger and exhibits a South China Sea branch of the Pacific-to-Indian Ocean throughflow, which originates from the western Philippine Sea toward the Indonesian Seas through the South China Sea, as well as through the Karimata and Mindoro Straits. The southwestward current near the continental slope of the northern South China Sea is shown to be a combination of this branch and the interior circulation gyre. This winter branch can be confirmed by trajectories of satellite-tracked drifters, which clearly show a flow from the Luzón Strait to the Karimata Strait in winter. In summer, the flow in the Karimata Strait is reversed. Numerical model results indicate that the Pacific water can enter the South China Sea and exit toward the Sulu Sea, but no observational evidence is available. The roles of the throughflow branch in the circulation, water properties and air-sea exchange of the South China Sea, and in enhancing and regulating the volume transport and reducing the heat transport of the Indonesian Throughflow, are discussed.

  16. Topographic-Compositional Relationships within the South Pole Aitken Basin

    NASA Astrophysics Data System (ADS)

    Lucey, P. G.; Holtzmann, J.; Blewett, D. T.; Taylor, G. J.; Hawke, B. R.

    1999-01-01

    The South Pole Aitken (SPA) Basin is an immense structure that dominates the geology of much of the farside of the Moon. Its floor is composed mostly of impact deposits, though it also has numerous relatively small regions of mare basalt. The basin floor exhibits a lower albedo and higher mafic mineral abundance than the surrounding highlands [ I ]. The origin of this mafic anomaly is a major question in lunar geology. Hypotheses for the presence of the mafic anomaly were briefly reviewed in [2] and include mare deposits mixed and obscured by basin or crater ejecta (cryptomaria), a large impact melt sheet that may have differentiated, exposed lower crustal material, and a significant component of excavated mantle. A study of mineralogy as revealed in Clementine UV-VIS imagery for limited portions of the basin found a predominantly low-Capyroxene (noritic) character [2], ruling out cryptomaria as an important contributor to the mafic enhancement. A few small cryptomaria, revealed by dark-halo impact craters and light plains units with high-FeO contents, have been found in SPA; however, it appears that extensive cryptomaria are lacking in this basin. The uniformly noritic lithology within SPA led to favor exposed lower crust or a homogenized melt sheet as the explanation for the mafic anomaly. Models of basin formation predict that a basin the size of SPA should have excavated through the entire lunar crust (assuming nonoblique impact), potentially exposing or mixing a large component of material from the mantle. Comparison of SPA floor FeO and Ti02 (derived from Clementine UV-VIS observations) and also Th (from Lunar Prospector) with model-mantle chemistries appears to be consistent with a mixture of approximately equal proportions of lower-crust and mantle material. In the present study, we examine the relationship between the basin's topography and composition in order to provide further insight on the origin of the basin floor material. Data: Clementine UV

  17. Sustainable Agricultural Paradigm Of mountain-Oasis-Ecotone-Desert System in Inland Manasi River Basin, Xinjiang Province, Northwest China

    NASA Astrophysics Data System (ADS)

    Liu, Huiming; Chen, Weiming; Dong, Xiaobin; Zhang, Xinshi

    Manasi River basin is located in the north foot of Tianshan Mountain, south edge of Zhunger Basin, central-north Xinjiang province, with typical aridfeatures of northern China. As the pressure on water resources in Manasi river basin is mounting because of rapid economic development, its conservation becomes ever more important. Climate change is another major threat to the future of water resources of Manasi river basin. How the water resourcechanges in Manasi river basin caused by glacial ablation, will affect the typical mountain-basin terrestrial ecosystems and agricultural production in Manasi river basin? What can we cope with the ecological issues caused by glacial ablation? In this paper we show how the water-saving stratagem such asconstructing reservoir in the mountainous region, building water pipes and be used in combination with the potential of water-saving resources, and build up sustainable agricultural paradigm of mountain-oasis-ecotone-desert system to coping with the glacier retreat and ablation. The potential of water-saving instudy area were calculated which presumed that if mountainous reservoirs and water pipes were built and water-saving technology were adopted, optimized eco-productive paradigm for mountain-basin system in Manasi river basin is proposed in desertification controlling, constructing artificial grassland in the oasis is the measure to protect vegetation in the downstream desert in Manasi river basin, and stopping grazing or forbidding grazing in the downstream of serious degradation in Manasi river basin.

  18. Water Availability for Shale Gas Development in Sichuan Basin, China.

    PubMed

    Yu, Mengjun; Weinthal, Erika; Patiño-Echeverri, Dalia; Deshusses, Marc A; Zou, Caineng; Ni, Yunyan; Vengosh, Avner

    2016-03-15

    Unconventional shale gas development holds promise for reducing the predominant consumption of coal and increasing the utilization of natural gas in China. While China possesses some of the most abundant technically recoverable shale gas resources in the world, water availability could still be a limiting factor for hydraulic fracturing operations, in addition to geological, infrastructural, and technological barriers. Here, we project the baseline water availability for the next 15 years in Sichuan Basin, one of the most promising shale gas basins in China. Our projection shows that continued water demand for the domestic sector in Sichuan Basin could result in high to extremely high water stress in certain areas. By simulating shale gas development and using information from current water use for hydraulic fracturing in Sichuan Basin (20,000-30,000 m(3) per well), we project that during the next decade water use for shale gas development could reach 20-30 million m(3)/year, when shale gas well development is projected to be most active. While this volume is negligible relative to the projected overall domestic water use of ∼36 billion m(3)/year, we posit that intensification of hydraulic fracturing and water use might compete with other water utilization in local water-stress areas in Sichuan Basin.

  19. Water Availability for Shale Gas Development in Sichuan Basin, China.

    PubMed

    Yu, Mengjun; Weinthal, Erika; Patiño-Echeverri, Dalia; Deshusses, Marc A; Zou, Caineng; Ni, Yunyan; Vengosh, Avner

    2016-03-15

    Unconventional shale gas development holds promise for reducing the predominant consumption of coal and increasing the utilization of natural gas in China. While China possesses some of the most abundant technically recoverable shale gas resources in the world, water availability could still be a limiting factor for hydraulic fracturing operations, in addition to geological, infrastructural, and technological barriers. Here, we project the baseline water availability for the next 15 years in Sichuan Basin, one of the most promising shale gas basins in China. Our projection shows that continued water demand for the domestic sector in Sichuan Basin could result in high to extremely high water stress in certain areas. By simulating shale gas development and using information from current water use for hydraulic fracturing in Sichuan Basin (20,000-30,000 m(3) per well), we project that during the next decade water use for shale gas development could reach 20-30 million m(3)/year, when shale gas well development is projected to be most active. While this volume is negligible relative to the projected overall domestic water use of ∼36 billion m(3)/year, we posit that intensification of hydraulic fracturing and water use might compete with other water utilization in local water-stress areas in Sichuan Basin. PMID:26881457

  20. Petroleum geologic characteristics of east China Sea basin

    SciTech Connect

    Desheng, Li )

    1990-05-01

    The East China Sea is a major Cenozoic epicontinental rift-depression basin covering an area of 770,000 km{sup 2}. The basin is bounded by the Minzhe, uplift to the west and by the Ryukyu Island arc to the east. The thickness of sedimentary strata is greater than 10 km. Basin evolution has been dominated by taphrogenesis and orogenesis attributable to the westward subduction of the Pacific plate. The basin history of the East China Sea can be divided into four stages: (1) Late Cretaceous-Paleogene rifting stage, (2) Eocene-Oligocene rifting-depression stage, (3) Miocene depression stage, and (4) Pliocene-Quaternary draping stage. The Okinawa Trough is a new rifting zone related to the subduction of Ryukyu Island arc. Recent geophysical exploration and petroleum drilling activities in the East China Sea basin show that Paleogene lacustrine and Neogene marine facies strata include multiple suites of hydrocarbon source rocks. Eight structures have tested gas and oil. The Pinghu gas and oil field was discovered and delineated on the west slope of Xihu depression. Various types of traps, dome anticlines, rollover anticlines, fault blocks, buried hills, and reef carbonates, are good prospects.

  1. Advances in basinal-scale groundwater modeling in China

    NASA Astrophysics Data System (ADS)

    Eryong, Z.

    2010-12-01

    This paper attempts to introduce the main works and achievements about basinal-scale groundwater flow modeling in China. Since 1970s groundwater modeling has being in used in evaluating groundwater resource and relevant environmental issues in China. In the early stage, the application of groundwater model is with limited computer know-how, even though the theories and methods were correctly formulated, most of applications are on the groundwater within a small area. From year 1999, investigations of groundwater resources and related environmental issues have been performed and organized by China Geological Survey, and GIS-based databases and groundwater flow models have been developed in main basins and plains in the Northern China in order to evaluate and exploit the groundwater resources based on environmental geology constrains of the area. GMS, FEFLOW and Visual MODFLOW are used to construct the geological model and numerical models of groundwater system for these plains and basins. Having studied the theories and methodologies of groundwater modeling for the past 10 years, seepage-pipe flow model was proposed to simulate well flow and monitoring well, and groundwater flow in porous-fissured-caved media, and artesian well and spring flux. A PGMS (Polygon grid finite-difference groundwater modeling system) has been developed and used for basinal-scale groundwater modeling.

  2. Basin modeling of the Parang (Socotra) Basin, northern East China Sea shelf: Implications for hydrocarbon potential

    NASA Astrophysics Data System (ADS)

    Kim, H.; Moon, S.; Lee, G.; Yoon, Y.; Kim, H.

    2013-12-01

    The hydrocarbon potential of the Parang (Socotra) Basin in the northern East China Sea shelf has remained poorly understood. We performed one-dimensional basin modeling for a dummy well located in the depocenter of the northern part of the Parang Basin to investigate the timings of hydrocarbon generation and expulsion. First, a depth-converted seismic profile crossing the dummy well was restored by backstripping and decompaction for eight regional and subregional unconformities, including the top of the acoustic basement, to reconstruct the subsidence history and to determine the timing of trap formation. The basin modeling, assuming rifting heat-flow model and source rocks with type III kerogen, suggests that the main phase of hydrocarbon (mostly gas) expulsion peaked in the Late Eocene, predating the inversion that created traps in the early Middle to latest Middle Eocene. Thus, the potential for large hydrocarbon accumulations in the northern Parang Basin is probably limited.

  3. Nature, diversity of deposit types and metallogenic relations of South China

    USGS Publications Warehouse

    Zaw, K.; Peters, S.G.; Cromie, P.; Burrett, C.; Hou, Z.

    2007-01-01

    The South China Region is rich in mineral resources and has a wide diversity of deposit types. The region has undergone multiple tectonic and magmatic events and related metallogenic processes throughout the earth history. These tectonic and metallogenic processes were responsible for the formation of the diverse styles of base and precious metal deposits in South China making it one of the resource-rich regions in the world. During the Proterozoic, the South China Craton was characterised by rifting of continental margin before eruption of submarine volcanics and development of platform carbonate rocks, and the formation of VHMS, stratabound copper and MVT deposits. The Phanerozoic metallogeny of South China was related to opening and closing of the Tethyan Ocean involving multiple orogenies by subduction, back-arc rifting, arc-continent collision and post-collisional extension during the Indosinian (Triassic), Yanshanian (Jurassic to Cretaceous) and Himalayan (Tertiary) Orogenies. The Late Palaeozoic was a productive metallogenic period for South China resulting from break-up and rifting of Gondwana. Significant stratabound base and precious metal deposits were formed during the Devonian and Carboniferous (e.g., Fankou and Dabaoshan deposits). These Late Palaeozoic SEDEX-style deposits have been often overprinted by skarn systems associated with Yanshanian magmatism (e.g., Chengmenshan, Dongguashan and Qixiashan). A number of Late Palaeozoic to Early Mesozoic VHMS deposits also developed in the Sanjiang fold belt in the western part of South China (e.g., Laochang and Gacun). South China has significant sedimentary rock-hosted Carlin-like deposits, which occur in the Devonian- to Triassic-aged accretionary wedge or rift basins at the margin of the South China Craton. They are present in a region at the junction of Yunnan, Guizhou, and Guangxi Provinces called the 'Southern Golden Triangle', and are also present in NW Sichuan, Gansu and Shaanxi, in an area known as

  4. Winter Cold tongue in the South China Sea

    NASA Astrophysics Data System (ADS)

    Thompson, B.; Tkalich, P.; Rizzoli, P. M.

    2014-12-01

    The South China Sea (SCS) surface circulation is mainly forced by seasonally varying monsoon winds and flow through the Luzon Strait. In winter, positive wind curl (due to the northeasterly winds) in the southern half of SCS drives a cyclonic gyre. The strong western boundary current south off Vietnam on the continental slope separates the Sunda Shelf to the west and deep SCS basin to the east. The advection of cold water due to the slope current results in a unique cold tongue in Sea Surface Temperature (SST) from November to February. The inter-annual variability of this cold-tongue is investigated by analyzing the NCEP OISST version-2 dataset. Dynamics of the evolution, growth and decay of the cold tongue during the period 1982-2012 are addressed using the OISST and ERA-interim surface wind datasets. The role of water mass advection in the inter-annual variability of SCS cold-tongue is also investigated through the analysis of lateral heat fluxes estimated from NCEP-Climate Forecast System Re-analysis dataset. The vertically integrated Ekman transport (i.e., the Sverdrup transport) plays a vital role in the formation this cold tongue. The southward Sverdrup transport brings cold water from the northern parts of the SCS. Inter-annual variations in the cold tongue SST during the northeast monsoon (November to February) are strongly linked to the north-south Sverdrup and zonal Ekman transport anomalies. The positive SST anomalies over the cold-tongue region are associated with positive transport anomalies, reflecting the weakening of the southward and westward advection. The formation and termination of this cold tongue has significant correlation with the El Nino phenomenon in the Pacific Ocean.

  5. The influence of large-scale climate phenomena on precipitation in the Ordos Basin, China

    NASA Astrophysics Data System (ADS)

    Zhong, Yu; Lei, Liyuan; Liu, Youcun; Hao, Yonghong; Zou, Chris; Zhan, Hongbin

    2016-09-01

    Large-scale atmospheric circulations significantly affect regional precipitation patterns. However, it is not well known whether and how these phenomena affect regional precipitation distribution in northern China. This paper reported the individual and coupled effects of El Niño-Southern Oscillation (ENSO), Indian summer monsoon (ISM), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) on annual precipitation for the Ordos Basin, an arid and semi-arid basin, currently with major industries of coal, fossil oil, natural gas, and halite in north central China. Our results showed that ENSO and ISM exerted substantial impact on annual precipitation while the impact of PDO and AMO was relatively limited. There were 24 and 15 out of 33 stations showing significant differences (p < 0.1) in annual precipitation (from 1950 to 2013) for ENSO and ISM, respectively. The median precipitation across the basin during El Niño years was 21.49 % higher than that during La Niña years and 17.28 % higher during the positive phase of ISM years compared to the negative phase of the ISM years. The impacts of ENSO and ISM on precipitation were enhanced during a PDO cold phase but weakened in a PDO warm phase. The impact of ENSO was still enhanced by an AMO warm phase. The effects of climatic phenomena on precipitation showed a strong spatial difference in the Ordos Basin. The impact of ENSO was mostly evident around the edges of the basin while the impact of ISM decreases from south to north. The deserts (i.e., Hobq Desert and Mu Us Sandy Land) in the center of the basin were less affected by these large-scale climatic phenomena. An improved understanding of such relationships would be helpful in water resource planning and disaster management for the Ordos Basin.

  6. Petrogenesis of early Jurassic basalts in southern Jiangxi Province, South China: Implications for the thermal state of the Mesozoic mantle beneath South China

    NASA Astrophysics Data System (ADS)

    Cen, Tao; Li, Wu-xian; Wang, Xuan-ce; Pang, Chong-jin; Li, Zheng-xiang; Xing, Guang-fu; Zhao, Xi-lin; Tao, Jihua

    2016-07-01

    Early Jurassic bimodal volcanic and intrusive rocks in southern South China show distinct associations and distribution patterns in comparison with those of the Middle Jurassic and Cretaceous rocks in the area. It is widely accepted that these rocks formed in an extensional setting, although the timing of the onset and the tectonic driver for extension are debated. Here, we present systematic LA-ICP-MS zircon U-Pb ages, whole-rock geochemistry and Sr-Nd isotope data for bimodal volcanic rocks from the Changpu Formation in the Changpu-Baimianshi and Dongkeng-Linjiang basins in southern Jiangxi Province, South China. Zircon U-Pb ages indicate that the bimodal volcanic rocks erupted at ca. 190 Ma, contemporaneous with the Fankeng basalts (~ 183 Ma). A compilation of geochronological results demonstrates that basin-scale basaltic eruptions occurred during the Early Jurassic within a relatively short interval (< 5 Ma). These Early Jurassic basalts have tholeiitic compositions and OIB-like trace element distribution patterns. Geochemical analyses show that the basalts were derived from depleted asthenospheric mantle, dominated by a volatile-free peridotite source. The calculated primary melt compositions suggest that the basalts formed at 1.9-2.1 GPa, with melting temperatures of 1378 °C-1405 °C and a mantle potential temperature (TP) ranging from 1383 °C to 1407 °C. The temperature range is somewhat hotter than normal mid-ocean-basalt (MORB) mantle but similar to an intra-plate continental mantle setting, such as the Basin and Range Province in western North America. This study provides an important constraint on the Early Jurassic mantle thermal state beneath South China.

  7. Recent Seismic Experiments of OBS in the South China Sea

    NASA Astrophysics Data System (ADS)

    Ruan, A.; Li, J.; Wu, Z.

    2012-12-01

    Since 2006 some research institutions of China have carried out some important seismic experiments by using ocean bottom seismometer(OBS) in the South China Sea (SCS) and obtained many concrete progresses in modeling the crustal structure of SCS and also in understanding of its formation and evolution as well. In 2006 three wide-angle profiles were completed in the northern margin, named OBS2006-1 across the northwestern sub-basin, OBS2006-2 parallel to the sea basin boundary and OBS2006-3 across the Dongsha Rise and Chaoshan Depression respectively. In 2010 two wide- angle profiles were completed, named OBS2010-1 and OBS 2010-2 both perpendicular to the northern off-shore faulting system. During 2009-2011 four wide-angle profiles were completed in the southern margin, named OBS973-1 from southern margin to the southwestern sub-basin, OBS973-2 from Liyue Bank to the southwestern sub-basin and OBS973-3 from Xisha to the southwestern sub-basin, OBS2011-2 from Xisha to Hainan Island respectively. In 2011 two 3D seismic array of OBS were completed in the Zhongnan-Changlong sea mount chain and Huangyan-Zhenbei sea mount chain respectively. Here we present some primary but important results as follows. (1) The velocity model of OBS2006-1 indicates that the crust under the continental slope decreases from 21km to 11km, and to 7.7km in the northwestern sub-basin with Moho depth ascends from 21km to 11km. The tectonic geometry and velocity structure of the northwestern sub-basin and its margins on both sides shows symmetrical and conjugate and indicates pure shear mode of continental margin rifting mechanism. (2) The velocity model of OBS2006-3 reveals remarkable thickness with maximum 8 km of the Mesozoic sediment in Chaoshan Depression in which velocity increases downward from 4.4 km/s at top to 5.3 km/s at the bottom. The buried depth of Moho decreases from 24-25 km under Dongsha Rise to 17 km in the lower slope and an obviously velocity abnormal is detected in the upper

  8. Petroleum geology in Tarim basin, China

    SciTech Connect

    Zhou, Guojun )

    1994-08-01

    Tarim basin is a superimposed basin with two tectonic regimes and contains multisources, multireservoirs, and multiseals. Almost all major strata within the Paleozoic, Mesozoic, and Cenozoic exist in the basin, and they are grouped by six regional unconformities, which are related to hydrocarbon accumulation. Source rocks are Cambrian marl; Lower Ordovician black carbonaceous shales; Middle Ordovician dark gray limestone; Upper Ordovician brownish black carbonaceous shales and oil shales; grayish black carbonaceous shales, dark gray and grayish brown bituminous marl, and reef limestone in the Carboniferous and Permian; and gray to dark gray shales in the Triassic-Jurassic oil-bearing strata. Reservoir rocks in the Cambrian-Ordovician oil-bearing strata and the Carboniferous-Permian oil-bearing strata are mainly fractured limestones and sandstones. The fracture distribution is related to unconformities. Vugs and casts also exist in most limestones; intergranular porosity exists in sandstones. The reservoirs in the Triassic-Jurassic are fluvial-deltaic sandstones, and above are Cretaceous gypsum and halite seals. Ten types of traps are found in this basin: (1) fold-related anticline traps, (2) anticline-fault traps, (3) fault drag-related anticline traps, (4) traps underneath thrusting faults, (5) fault-block traps (6) traps made from cross or arc-like fault and monocline, (7) salt dome traps, (8) traps created by intrusion, (9) lenticular or pinchout traps, and (10) unconformity and overlap traps.

  9. U-Pb Detrital Zircon Geochronology and Implications: the Mesozoic southern Ordos Basin, North Central China

    NASA Astrophysics Data System (ADS)

    Xie, X.; Heller, P. L.; Chamberlain, K. R.

    2007-12-01

    Two deformation belts -- the Qinling orogenic belt (QOB) to the south and the Western Liupanshan thrust belt (WLTB) to the west, including the Qilian-Qaidam terrane (QQT) -- control the evolution of the southern Ordos Basin during early Mesozoic time. U-Pb detrital zircon geochronology is used to identify provenance, reconstruct paleogeography, and document the relative timing of basin margin deformation. Two correlated strata same age samples of the Middle to Late Triassic Yanchang Fm. were collected from the southern and southwestern basin margin respectively. In total 258 zircon grains were analyzed using LA-ICP-MS. Three major age populations -- 240-490 Ma, 1.8-2.0 Ga, and 2.2-2.8 Ga -- characterize the detrital zircon grains of the Yanchang Fm. Regional geochronology studies show that the two oldest age groups match ages of basement rocks found in the underlying North China block. The younger age group can be subdivided into three distinctive groups: 240-300 Ma, 300-400, and 400-490 Ma. The youngest age group matches ages exposed to the west in the QQT, whereas the other two match grains from southern QOB source. In all samples detrital zircon from the WLTB source area overwhelms the QOB source, regardless of its proximity to either basin margin. This result suggests that either the source rock with the youngest zircon grains (e.g. 240- 490 Ma) from the QOB to the south have been eroded away and no longer existed, or simply the QOB, even during deformation, was never the dominant source of detrital zircon to the southern Ordos Basin. Probably some drainage systems far from the west combine with some local tributary systems from the south control the sedimentation in the south Ordos Basin during the middle to Late Triassic time. This is surprising in that most studies suggest that the QOB was a longer lived and more dominant tectonic feature in this part of China during early Mesozoic time. Furthermore, it also indicates that: 1) deformation in the QOB and WLTB

  10. Streamflow Simulations for Major River Basins in China

    NASA Astrophysics Data System (ADS)

    Su, F.; Xie, Z.; Liang, X.

    2002-12-01

    In this study, the land surface scheme (LSS) of VIC (Variable Infiltration Capacity) model is used to simulate streamflows of major river basins in China where the new surface runoff parameterization of VIC that represents both Horton and Dunne runoff generation mechanisms with the framework of considering subgrid spatial scale soil heterogeneity is applied. The entire area of China is represented by 2604 cells with a resolution of 60km­A60km for each cell. The VIC model is applied to each grid cell over each basin. A routing scheme is run offline which takes daily VIC surface and subsurface runoff as input to obtain model simulated streamflows at the outlets of study basins. Preparation of the forcing data, and soil and vegetation parameters needed by the VIC model for the entire area of China will be described, and some of the data issues will be addressed and discussed. The VIC streamflow simulations over a few river basins will be presented and compared with the observations.

  11. Riparian vegetation assessment of Cauvery River Basin of South India.

    PubMed

    Sunil, C; Somashekar, R K; Nagaraja, B C

    2010-11-01

    The Cauvery river basin of South India has a large phyto-floristic wealth, rightfully enough to constitute a separate phyto-geographic unit. Increase in the anthropogenic pressures within the river basin and surrounding landscapes have persistently stressed the riparian ecosystem structure adversely, besides altering its composition. The objective of this study was to examine the present status of riparian vegetation along the Cauvery river basin, in response to anthropogenic pressures. For vegetation analysis, the riparian forest coming in the middle stretch of Cauvery river was categorized into two zones, viz., forest zone covering ~54 km stretch and agroecosystem zone covering ~80 km stretch. In each zone, tree species were quantified using transects at 8-km interval. Overall tree species accounting for both forest and agroecosystem were recorded and compared. The results indicate that the mean density and basal area of trees per plot were higher in the forest zone than agroecosystem zone. The Shannon-Weiner diversity of forest zone is 4.6, which is higher than agroecosystem. In addition, species composition indicated a relatively low or poor similarity between the two zones. The vegetation density and site disturbance scores for all the study sites reveals that sand mining and grazing areas have exerted negative impact on riparian forest. The results of the present study clearly brought out the need for preparing and implementing site-specific conservation plans for riparian ecosystem.

  12. Geology of petroleum and coal deposits in the North China Basin, eastern China

    SciTech Connect

    Lee, K.Y.

    1989-01-01

    The North China Basin evolved from a rifted intercratonic graben system on the east-central Sino-Korean Platform during the Jurassic through Paleogene tectonic movement, and contains significant petroleum and coal resources. Petroleum production in the North China Basin ranks second after the Songliao Basin in China. The ultimate recoverable oil and gas reserves are 11,251 million barrels of oil and 8,425 billion ft{sup 3} of gas. Of the six petroleum-producing depressions within the basin, The Jiyang Depression ranks first, and is followed by the Jizhong Depression, where the rich Tertiary lacustrine source beds and deltaic sandstone reservoirs are extensive in areal distribution. Late Carboniferous to Permian coal reserves in the basin are estimated to be about 30 percent of total reserves (411.3 billion tons in the North China region). Because of deep burial of the coal beds (1,800 m) coal-mining activities are confined to the basin border.

  13. Carbon uptake by karsts in the Houzhai Basin, southwest China

    NASA Astrophysics Data System (ADS)

    Yan, Junhua; Wang, Y. P.; Zhou, Guoyi; Li, Shenggong; Yu, Guirui; Li, Kun

    2011-12-01

    Using an estimated bicarbonate concentration ([HCO3-]) in water and discharge rates of surface water and underground water from the Houzhai Basin, southwest China, from 1986 to 2007, we estimate that the mean carbon uptake rate was 20.7 g C m-2 yr-1. The surface water and underground water contribute about equally to the total carbon uptake from 1986 to 2007. About 97% of the interannual variation of annual carbon uptake can be explained by the discharge rate. Within a year, the net carbon uptake rate by karst during the wet season (May-October) was found to be about 2.4 times that during the dry season (November-April). If the seasonal variations of discharge rate and bicarbonate concentrations are not accounted for, estimates of annual net carbon uptake by karst can be biased by >25%, but that bias becomes very small (<5%) when averaged from 1986 to 2007 for the Houzhai Basin. We also found that one of the empirical models as used in global modeling overestimated the net carbon uptake by karst at Houzhai Basin by 29%. Carbon uptake from chemical weathering of all karsts in China is estimated to be about 12 Tg C yr-1 at present (1 Tg = 1012 g), or about 57% of the rate of net carbon accumulated in the forest biomass from 1981 to 1998 in China; we therefore recommend the inclusion of carbon uptake from chemical weathering in the regional carbon budget of China.

  14. Black carbon over the South China Sea and in various continental locations in South China

    NASA Astrophysics Data System (ADS)

    Wu, D.; Wu, C.; Liao, B.; Chen, H.; Wu, M.; Li, F.; Tan, H.; Deng, T.; Li, H.; Jiang, D.; Yu, J. Z.

    2013-12-01

    Black carbon (BC) is an important atmospheric constituent as an air pollutant and as a climate forcer. To our knowledge, field measurements of BC have not been reported over the South China Sea. Observations of light-absorption coefficients (σabs) and BC concentrations by Aethalometer were conducted on Yongxing Island in the South China Sea and at five continental sites in the Pearl River delta (PRD) region, South China, in two periods: 16 May-20 June 2008 in the rainy season and 12 December 2008-8 January 2009 in the dry season. At the oceanic site, the daily average BC concentrations varied from 0.28 to 2.14 μg m-3 and variations of BC were small between the two periods (0.67 in the dry season sampling period and 0.54 μg m-3 in the rainy season sampling period). Similarly, little difference in BC level was found at a rural site in PRD between the two sampling periods (2.88 and 2.62 μg m-3). At the PRD urban sites, the daily average concentration of BC ranged from 1.56 to 37.9 μg m-3, higher in the dry season sampling period (12.31 μg m-3) and lower in the rainy season sampling period (6.17 μg m-3). The observed average σabs values in rainy vs. dry season sampling periods are 119 vs. 62 Mm-1 at the PRD urban sites, 29 vs. 26 Mm-1 at the PRD background site, and 8.4 vs. 7.2 Mm-1 at the marine site. At urban/suburban PRD sites, BC was observed to have a diurnal pattern of higher concentrations at night and at the urban sites a small peak in the early morning rush hour.

  15. Drought assessment using a multivariate drought index in the Huaihe River basin of Eastern China

    NASA Astrophysics Data System (ADS)

    Li, Q.; Zeng, M.; Wang, H.; Li, P.; Wang, K.; Yu, M.

    2015-06-01

    The Huaihe River Basin having China's highest population density (662 persons per km2) lies in a transition zone between the climates of North and South China, and is thus prone to drought. Therefore, the paper aims to develop an appropriate drought assessment approach for drought assessment in the Huaihe River basin, China. Based on the Principal Component Analysis of precipitation, evapotranspiration, soil moisture and runoff, the three latter variables of which were obtained by use of the Xin'anjiang model, a new multivariate drought index (MDI) was formulated, and its thresholds were determined by use of cumulative distribution function. The MDI, the Standardized Precipitation Index (SPI) and the self-calibrating Palmer Drought Severity Index (sc-PDSI) time series on a monthly scale were computed and compared during 1988, 1999/2000 and 2001 drought events. The results show that the MDI exhibited certain advantages over the sc-PDSI and the SPI in monitoring drought evolution. The MDI formulated by this paper could provide a scientific basis for drought mitigation and management, and references for drought assessment elsewhere in China.

  16. Potential Multi Canister Overpack (MCO) Cask Drop in the K West Basin South Loadout Pit

    SciTech Connect

    POWERS, T.B.

    1999-12-09

    This calculation note documents the probabilistic calculation of a potential drop of a multi-canister overpack (MCO) cask or MCO cask and immersion pail at the K West Basin south loadout pit. The calculations are in support of the cask loading system (CLS) subproject alignment of CLS equipment in the K West Basin south loadout pit.

  17. Floods of June 1965 in South Platte River basin, Colorado

    USGS Publications Warehouse

    Matthai, Howard Frederick

    1969-01-01

    Heavy, intense rains in three areas on three different days caused outstanding floods on many streams in the South Platte River basin from Plum Creek, just south of Denver, downstream to the Colorado-Nebraska State line. The flood-producing storms followed a relatively wet period, and rainfall of as much as 14 inches in a few hours was reported. The storms occurred over the Greeley-Sterling area on June 14-15, over the Plum Creek and Cherry Creek basins on June 16, and over the headwaters of Kiowa and Bijou Creeks on June 17 after heavy rains on June 15. The flood crest did not pass Julesburg, in the northeast corner of Colorado, until June 20. Previous record high discharges on many tributaries with drainage areas on the plains were exceeded, sometimes severalfold. The six principal tributaries carrying snowmelt runoff were contributing, but not significant, factors in the floods. The attenuation of the peak flow by channel storage as the flood passed through Denver was considerable; yet the peak discharge of 40,300 cfs (cubic feet per second) of the South Platte River at Denver was 1.8 times the previously recorded high of 22,000 cfs in a period of record starting in 1889. The 1965 peak would have been still higher except that all flow from Cherry Creek was stored in Cherry Creek Reservoir. Six persons were drowned, and two other deaths were attributed to the storms. The total damage amounted to $508.2 million, and about 75 percent of this occurred in the Denver metropolitan area. Descriptions of the storms and floods, detailed streamflow records, and information on damages, flood profiles, inundated areas, and flood frequency are included in this report. Several comparisons of the magnitude of the flood are made, and all indicate that an outstanding hydrologic event occurred.

  18. Prototypical Solitons in the South China Sea

    NASA Astrophysics Data System (ADS)

    Klymak, J. M.; Pinkel, R.

    2006-12-01

    When observed, so-called solitary waves are often found to evolve so rapidly that they cannot really be called solitary. Here we present detailed observations of waves in the deep South China Sea that we track for over 90 km, from ship and a satellite photo. The waves are mode-1, have amplitudes of 170 m, and move at 2.95 m/s. They have weak intrinsic shear, but are found to interact with pre-existing shear, perhaps triggering instabilities. However, on the whole, these waves appear to be non-dissipative and do not appreciably change amplitude, shape, or phase speed over 70 km. The shape and phase speed are well-fit by the Korteig-deVries equation, which allows us to estimate the kinetic energy (KE=1.1 GJ m-1) and available potential energy (APE=0.75 GJ m-1). Released over a tidal cycle, the lead two waves of this packet constitute 9 GW of energy heading towards Dongsha Island. Observations of other packets indicate that this was the peak in internal wave energy, with a spring-neap average closer to 2.5 GW.

  19. Geochemistry of oils from the Junggar basin, northwest China

    USGS Publications Warehouse

    Clayton, J.L.; Yang, J.; King, J.D.; Lillis, P.G.; Warden, A.

    1997-01-01

    The Junggar basin of northwestern China is a structural basin containing a thick sequence of Paleozoic-Pleistocene rocks with estimated oil reserves of as much as 5 billion bbl. Analyses of 19 oil samples from nine producing fields and two oil-stained cores in the Junggar basin revealed the presence of at least five genetic oil types. The geochemistry of the oils indicates source organic matter deposited in fresh to brackish lake and marine environments, including coaly organic matter sources. The volumetrically most important oil type discovered to date is produced from Late Carboniferous-Middle Triassic reservoirs in the giant Karamay field and nearby fields located along the northwestern margin of the Junggar basin. Oil produced from the Mahu field, located downdip in a depression east of the Karamay field, is from a different source than Karamay oils. Unique oil types are also produced from an upper Permian reservoir at Jimusar field in the southeastern part of the basin, and from Tertiary (Oligocene) rocks at Dushanzi field and Lower Jurassic rocks at Qigu field, both located along the southern margin of the basin. Previous studies have demonstrated the presence of Upper Permian source rocks, and the possibility of Mesozoic or Tertiary sources has been proposed, but not tested by geochemical analysis, although analyses of some possible Jurassic coal source rocks have been reported. Our findings indicate that several effective source rocks are present in the basin, including local sources of Mesozoic or younger age for oil accumulations along the southern and southeastern margins of the basin. Future exploration or assessment of petroleum potential of the basin can be improved by considering the geological relationships among oil types, possible oil source rocks, and reservoirs.

  20. South Africa offers exploratory potential in variety of basins

    SciTech Connect

    Broad, D.S.; Mills, S.R. )

    1993-12-06

    While the future suspension of the oil embargo against South Africa will no doubt help revitalize the region's most powerful economy, a move away from dependence on coal as the major local energy source is also likely. This could be accomplished through regional cooperation and development were it not for the ongoing conflict in Angola, the only producer of oil and gas in the Southern African Development Community. Even with world oil prices in the doldrums, massive foreign exchange savings would result from a domestic source, and in line with world trends the possibility of harnessing the gas resources of the region is increasingly seen as a possibility. For the present, those resources remain to be defined. But ENH of Mozambique is pursuing an appraisal program for Pande field with World Bank funding, while Shell and its partners are considering possibilities of Kudu field in Namiba. And while South Africa's own national oil company, Soekor, has had limited success with its search for oil during the apartheid years, offshore F-A gas field is in production, and the potential for hydrocarbons-gas in particular--requires a great deal more investigation. The colleagues have prepared a series of articles on basins off South Africa. These articles were prepared in anticipation of the completion of political reform and of the start of a licensing round, possibly during 1994. This article draws together summaries of aspects thought to be most pertinent to petroleum exploration.

  1. South China sea off Viet Nam to see more exploration

    SciTech Connect

    Not Available

    1992-06-15

    British and Japanese operators are posed for exploration campaigns off southern Viet Nam. This paper reports that a 50-50 partnership of Lasmo International Ltd., London, and C. Itoh Exploration Co. of Japan signed a heads of agreement covering Block 04-2, and AEDC Vietnam Oil Development Co. and Teikoku Oil Co. acquired Block 05-3 under a production sharing contract. AEDC is a unit of AOC Energy Development Co., a subsidiary of Arabian Oil Co. (AOC) of Japan. Both tracts are in the Con Son basin in the South China Sea. Site is 15 km north of 500 million bbl Dai Hung (Big Bear) oil field for which state owned Petrovietnam is evaluating bids to place on production. A unit of the Royal Dutch/shell Group acquired a west offset, Block 10, early this year. The Lasmo-C. Itoh acreage is among five blocks offered in Vietnam's second round of offshore licensing. All are in the area that once was reserved entirely for Vietsovpetro, a partnership of Petrovietnam and the former Soviet Union.

  2. Geology and petroleum resources of basins in western China

    SciTech Connect

    Ulmishek, G.

    1984-11-01

    Western China contains 11 recognized petroliferous or potentially petroliferous basins. Despite their great difference in size, these basins have important common features: (1) their Mesozoic-Cenozoic sedimentary sequences are composed of rocks of essentially terrestrial origin, and (2) they experienced predominantly compressional stress during the late stages of their geologic history. The report is structured on a regional basis. The topics discussed for each basin include the stratigraphic and lithologic composition of the sedimentary cover, the major stages of tectonic development and the present-day structural framework, known oil and gas fields, probable source rocks, reservoir rocks, traps and seals, and potentially important exploration plays. The basins occupy 800,000 km/sup 2/ of land and contain over 4,000,000 km/sup 3/ of prospective sedimentary rocks. The most probable amounts of undiscovered petroleum resources in all these basins are estimated at 19.5 billion barrels of oil and 78 trillion cubic feet of gas. The Tarim, Zhungaer, and Chaidamu basins possess the great majority of these resources. 111 refs., 48 figs., 9 tabs.

  3. Environmental settings of the South Fork Iowa River basin, Iowa, and the Bogue Phalia basin, Mississippi, 2006-10

    USGS Publications Warehouse

    McCarthy, Kathleen A.; Rose, Claire E.; Kalkhoff, Stephen J.

    2012-01-01

    Studies of the transport and fate of agricultural chemicals in different environmental settings were conducted by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program's Agricultural Chemicals Team (ACT) at seven sites across the Nation, including the South Fork Iowa River basin in central Iowa and the Bogue Phalia basin in northwestern Mississippi. The South Fork Iowa River basin is representative of midwestern agriculture, where corn and soybeans are the predominant crops and a large percentage of the cultivated land is underlain by artificial drainage. The Bogue Phalia basin is representative of corn, soybean, cotton, and rice cropping in the humid, subtropical southeastern United States. Details of the environmental settings of these basins and the data-collection activities conducted by the USGS ACT over the 2006-10 study period are described in this report.

  4. The rift to drift evolution of the South China Sea

    NASA Astrophysics Data System (ADS)

    Ranero, Cesar R.; Cameselle, Alejandra; Franke, Dieter; Barckhausen, Udo

    2016-04-01

    Re-processing with modern algorithms of multichannel seismic reflection records from the South China Sea provide novel images on the crustal structure of the continental margin and its boundary zone with the oceanic crust (COB). The selected re-processed seismic lines strike perpendicular to the margins' trend and cross the entire basin, providing complementary images of conjugated rift segments of the NW, SW, and E sub-basins. Re-processed sections image the post-rift and syn-rift sediment, and fault-bounded basement blocks, often also intra-crustal fault reflections that together provide detailed information of the tectonic structural style during rifting. Further, the largest imaging improvement has been obtained in the delineation of -very often- clear fairly continuous reflections from the crust-mantle boundary across the continental margin into the oceanic crust. The images show how crustal thickness and structure change in parallel to changes in the tectonic style of the deformation during the evolution of the rift. The interpreted COB occurs in regions where the tectonic style displays the most noticeable changes from segments where extension is dominated by normal faulting to segments where faulting is comparatively minor and the crust shows fairly gentle lateral thickness variations; these latter segments are interpreted as oceanic crust. The identification of the continental and oceanic tectonic domains permits to study the along-strike evolution in rifting processes and rift segmentation. Also, the comparison of the tectonic structure of the conjugated flanks of the continental rift across the ocean basins is used to understand the last stages of rifting and the relative importance of tectonic extension and magmatism in final break up and spreading initiation. Although there is ample evidence of important volcanism in the images, with some spectacular large conical volcanoes formed over continental crust and numerous sill-like reflections in the

  5. The Field Operations and Early Results of the South China Sea Monsoon Experiment (SCSMEX)

    NASA Technical Reports Server (NTRS)

    Lau, K. M.; Ding, Yihui; Wang, Jough-Tai; Johnson, Richard; Keenan, Tom; Cifelli, Robert; Gerlach, John; Thiele, Otto; Rickenbach, Tom; Tsay, Si-Chee

    1999-01-01

    The South China Sea Monsoon Experiment (SCSMEX) is an international field experiment with the objective to better understand the key physical processes for the onset and evolution of the Asian summer monsoon in relation to fluctuation of the regional hydrologic cycle over Southeast Asian, southern East Asia, aiming at improving monsoon prediction. In this article, we present a description of the major meteorological observation platforms during the Intensive Observing Periods (IOP) of SCSMEX. We also provide highlights of early results and discussions of the role of SCSMEX in providing valuable in-situ data for calibration of satellite rainfall estimate from the Tropical Rainfall Measuring Mission (TRMM). Preliminary results indicate that there are distinctive stages in the onset of the South China Sea monsoon including possibly strong influences from extratropical systems as well as from convection over the Indian Ocean and the Bay of Bengal. There are some tantalizing evidence of complex interactions between the supercloud cluster development over the Indian Ocean, advancing southwest monsoon flow over the South China Sea, midlatitude disturbances and the western Pacific subtropical high, possibly contributing to the disastrous flood over Yangtze River Basin in China during June 1998.

  6. Climate modulated erosion and sediment flux control offshore crustal structure at South China Sea continental margin

    NASA Astrophysics Data System (ADS)

    Clift, P. D.; Brune, S.; Quinteros, J.

    2015-12-01

    Rifted continental lithosphere subsides as a consequence of combined crustal thinning and mantle lithosphere cooling yet basins on some continental margins experience anomalous subsidence events that postdate active extension. Deep basins on the northern margin of the South China Sea, notably the Baiyun Sag, show basement subsidence accelerating after ~21 Ma, postdating extension by several million years. Similar subsidence events are seen after 5 Ma in the Song Hong Basin and after 11 Ma in the Qiongdongnan Basin. We combine geophysical observations and numerical forward modeling to show that loading of the offshore basins by increased sediment flux caused by faster onshore erosion following Early Miocene monsoon intensification is a viable trigger for ductile flow after the cessation of active extension. Loading works in conjunction with onshore uplift to drive flow of the lower crust away from the rift axis. As well as sediment supply rates distribution patterns and drainage capture can be significant in controlling crustal flow and thinning. This illustrates that offshore basin dynamics at continental margins with weak crust can be controlled by onshore surface processes in a newly recognized form of climate-tectonic coupling.

  7. Sequence stratigraphy of the Orange basin, western offshore South Africa

    SciTech Connect

    Muntingh, A. )

    1991-03-01

    A seismic/sequence-stratigraphic framework for the siliciclastic fluvial to deepwater Cretaceous strata of the Orange basin has been constructed. Sequence-stratigraphic concepts developed by Exxon were used to interpret 10,000 km of seismic data and logs from 31 exploration boreholes within an area of 90,000 km{sup 2}. The sequence stratigraphy of the western margin exhibits 34 cyclical depositional sequences interpreted to document the response of the passive margin to cyclical changes in relative sea-level from Mid-Aptian to Late Maastrichtian times. All but one of the sequence boundaries are type 1 unconformities displaying intense erosion on the shelf and interpreted to develop during periods of rapid fall in relative sea-level. Basin-wide sequence boundaries (type 1 and 2 unconformities) were correlated with the third-order cycles of Exxon's global cycle chart utilizing SOEKOR's paleontological dating of a limited number of marine condensed sections. Higher-order cycles are recognized and best developed along the flanks of the structural arches where lower subsidence rates permitted impact of higher frequency cycles. Component depositional systems tracts inferred to have resulted from changes in relative sea level were interpreted and paleogeographic maps were constructed outlining incised valley systems on the shelf, shelf edge canyons, prograding wedges, basin floor fan, and slope fan systems. Distal marine shales and marine condensed sections provide both seal and hydrocarbon source. The chronostratigraphic and depositional framework being used to predict prospective play areas for hydrocarbon exploration on the western offshore of South Africa is also applicable to the Namibian offshore.

  8. Near-surface circulation in the South China Sea during the winter monsoon

    NASA Astrophysics Data System (ADS)

    Centurioni, L. R.; Niiler, P. N.; Lee, D.-K.

    2009-03-01

    Original velocity measurements at 15 m depth from Surface Velocity Program drifters are used to calculate the circulation in the South China Sea during the Winter Monsoon. The Ekman currents are computed with a new method and subtracted from drifter's velocity to calculate the residual circulation, which is approximately in geostrophic balance. The Ekman flow is nearly zonal and comparable to the zonal geostrophic flow in the northern basin. The geostrophic flow is cyclonic and extends into the southern Luzon Strait. Strong jets occur south of Hainan, off Vietnam and, to the south, off peninsular Malaysia. The Vietnam jet is concentrated inshore of the 200 m isobath, with mean speeds in excess of 1 m s-1. The onshore Ekman transport and pumping velocity computed from the wind stress curl offer a qualitative explanation of the existence and behavior of such jets.

  9. Fluvial sedimentology of a Mesozoic petrified forest assemblage, Shishu Formation, Junggar foreland basin, Xinjiang, China

    SciTech Connect

    McKnight, C.L.; Gan, O.; Carroll, A.R.; Dilcher, D.; Zhao, M.; Liang, Y.H.; Graham, S.A.

    1988-02-01

    The Upper Jurassic(.) Shishu Formation of the eastern Junggar basin, Xinjiang, northwest China, is a fluvial sand unit containing an important assemblage of well-preserved, silicified tree trunks and rooted stumps. Numerous logs, up to 83 ft (25.5 m) long, occur at several levels within a 33.6-ft (10.3 m) stratigraphic section of fluvial sand, gravel, and mud and several paleosol horizons. The uppermost logbearing layer includes a number of rooted tree stumps in growth position, with diameters of up to 8 ft (2.5 m). The maximum root length observed is 40 ft (12.3 m). The trees have been identified by Chinese paleontologists as Cupressinoxylon. The petrified forest assemblage is preserved on the northeast margin of the Mesozoic Junggar foreland basin, a large continental basin subsiding under thrust loading from the south. Logs found within channel gravel units are oriented with their log axes parallel to the channel axis. Sedimentary structures, including epsilon and trough cross-stratification and imbricated channel gravels, indicate paleocurrent flow generally to the south, toward the basin center. The size of the logs suggests the presence of a major fluvial system. The epsilon cross-sets suggest a channel depth of 26 ft (8 m). The oriented silicified logs and their enclosing clastic sediments provide important information on the depositional systems active on the northeastern margin of the Junggar basin in the Late Jurassic(.) time. Hopefully, further detailed study of the fossil trees, including the spacing of the rooted stumps, will provide new information on the paleoecology of Mesozoic forests and the climatic conditions prevailing in the region at the time of deposition.

  10. Petroleum geology of the Zhu-1 depression, Pearl River Mouth Basin, People's Republic of China

    SciTech Connect

    Aguilera, C.L.; Huizinga, B.J.; Lomando, A.J. )

    1990-05-01

    The Pearl River Mouth basin, located in the South China Sea between Hainan Island and Taiwan has been the focus of an intense exploration effort during the l980s. In 1979 the international oil industry, acquired over 60,000 km of seismic, gravity, and magnetic data covering an area of approximately 240,000 km{sup 2}. Three major subbasins, Zhu-1, Zhu-2, and Zhu-3 were defined. Chevron in partnership with Texaco and AGIP (ACT group), concentrated their effort on the Zhu-1 depression which was interpreted to contain as much as 7,800 m of sedimentary section. This subbasin, bounded by the Wansha and Donsha massifs to the north and south, is the most inboard of the three depressions, thereby possibly prolonging anoxic lacustrine conditions prior to the Neogene marine incursion. Additionally, the Zhu- 1 depression should have directly received Miocene sediment potentially supplying the subbasin with high-quality reservoirs. Within the Zhu-1 depression, the ACT group focused in on Block 16/08, which covered the deepest part of the Zhu-1 depression. The block was awarded to the consortium in January 1983. Structuring within the block ranges from Paleogene tensional block faulting created during the early formation of the overall Pearl River Mouth basin to draping over basement highs and carbonate buildups during the Neogene. The Pearl River Mouth basin exhibits classic rift basin geometry with early nonmarine continental fluvial/lacustrine deposition (Zhuhai Formation) during the Oligocene and capped by a lower Miocene marine incursion (Zhu Jiang Formation). Integrated interpretations, exploration drilling, and constant refinement of the geological model led to the discovery of two oil fields, Huizhou/21-1 and Huizhou/26-1, both of which are currently under development and will represent the first commercial oil production from the entire Pearl River Mouth basin.

  11. Advances in the South China ffs heavy rain research

    NASA Astrophysics Data System (ADS)

    Bao, Chenglan

    1985-08-01

    Heavy rain (HR) or even exceptional heavy rain (EHR) usually takes place during the first flood season in South China in every April June. In spring, cold air coming from north often brings about a normal HR over a large area in South China. However, EHR is mainly caused by tropical weather systems, the warm moist SW current from the Bay of Bengal-southern/central parts of the South China Sea, as well as the warm moist SE current from the NW Pacific Ocean. Investigations show that the fields of flow and moisture in the lower troposphere play a more important role in HR rather than the potential height-temperature field. The ageostrophy and pulsation of SW jet stream in lower level have a distinct effect on the occurrence of HR and its non-uniform distribution in time-space. The sea/land breeze effect is obvious in South China. This is one of the important causes for very heavy rain to easily occur in South China and the different time of rain peak between coastal and interior regions.

  12. From orogenic collapse to rifting ; structures of the South China Sea

    NASA Astrophysics Data System (ADS)

    Pubellier, M.; Chan, L. S.; Chamot Rooke, N.; Shen, W.; Ringenbach, J. C.

    2009-04-01

    The opening of the South China Sea has been a matter of debate for many years because of its internal structure, the differences between the conjugate margins and the variations of rifting and spreading directions. Although it is considered as being a back-arc basin, it is not sitting directly above a subduction zone, and the rifting process lasted for an unusually long duration. Among the specific characteristics is the early phase of rifting which took place early in place of the former Yanshanian andean-type mountain range. This stage is marked by narrow basins filled with deformed conglomerate, and initiated around 70My ago within a framework where the oblique subduction marked by igneous activity and ductile wrench faults, was replaced by orogenic collapse. The rifting stage is marked by Eocene syntectonic normal faults and occasional volcanics centres and has proceeded from NW-SE to NS extension. The NW stretching created at least two aborted basins which remained at rift stage. Extension was followed by spreading from 33 to ~20 Ma in the South China Sea. The ocean floor spreading also changed direction to NW-SE with a propagator inside the Sunda shelf from 20 to 17My ago. However the propagator opening implies that deformation is also taken by rifting around a southern wedge which in turn created strain inside the thinned crust. Another extension parallel to the margin is also observed althought the spreading was in process. The southward motion of the southern conjugate margin was later accommodated by its subduction beneath the NW Borneo wedge until completion of the Proto South China Sea subduction. Variations of rifting spreading through time and variations of structural styles are discussed in terms of boundary forces acting to the SE.

  13. Crustal structure and extension mode in the northwestern margin of the South China Sea

    NASA Astrophysics Data System (ADS)

    Gao, Jinwei; Wu, Shiguo; McIntosh, Kirk; Mi, Lijun; Liu, Zheng; Spence, George

    2016-06-01

    Combining multi-channel seismic reflection and gravity modeling, this study has investigated the crustal structure of the northwestern South China Sea margin. These data constrain a hyper-extended crustal area bounded by basin-bounding faults corresponding to an aborted rift below the Xisha Trough with a subparallel fossil ridge in the adjacent Northwest Sub-basin. The thinnest crust is located in the Xisha Trough, where it is remnant lower crust with a thickness of less than 3 km. Gravity modeling also revealed a hyper-extended crust across the Xisha Trough. The postrift magmatism is well developed and more active in the Xisha Trough and farther southeast than on the northwestern continental margin of the South China Sea; and the magmatic intrusion/extrusion was relatively active during the rifting of Xisha Trough and the Northwest Sub-basin. A narrow continent-ocean transition zone with a width of ˜65 km bounded seaward by a volcanic buried seamount is characterized by crustal thinning, rift depression, low gravity anomaly and the termination of the break-up unconformity seismic reflection. The aborted rift near the continental margin means that there may be no obvious detachment fault like that in the Iberia-Newfoundland type margin. The symmetric rift, extreme hyper-extended continental crust and hotter mantle materials indicate that continental crust underwent stretching phase (pure-shear deformation), thinning phase and breakup followed by onset of seafloor spreading and the mantle-lithosphere may break up before crustal-necking in the northwestern South China Sea margin.

  14. Post-breakup Basin Evolution along the South-Atlantic Margins

    NASA Astrophysics Data System (ADS)

    Strozyk, Frank; Back, Stefan; Kukla, Peter

    2014-05-01

    The post-breakup tectono-stratigraphic evolution of large offshore basins along the South American and African continental margins record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. A regional comparison based on tectonic-stratigraphic analysis of selected seismic transects between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin) provides a comprehensive basin-to-basin documentation of the key geological parameters controlling ocean and continental margin development. This comparison includes the margin configuration, subsidence development through time, sediment influx and storage patterns, type of basin fill (e.g. salt vs. non-salt systems; carbonate-rich vs. clastics-dominated systems) and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development. The diversity in the stratigraphic architecture of the conjugate margins offshore southern Brazil, Namibia and Angola reflects variations in the interplay of a number of controlling factors, of which the most important are (a) the structural configuration of each margin segment at the time of break-up, (b) the post break-up subsidence history of the respective margin segment

  15. Groundwater recharge to a sedimentary aquifer in the topographically closed Uley South Basin, South Australia

    NASA Astrophysics Data System (ADS)

    Ordens, Carlos M.; Werner, Adrian D.; Post, Vincent E. A.; Hutson, John L.; Simmons, Craig T.; Irvine, Benjamin M.

    2012-02-01

    The chloride mass balance (CMB) and water-table fluctuation (WTF) analysis methods were used to estimate recharge rates in the Uley South Basin, South Australia. Groundwater hydrochemistry and isotope data were used to infer the nature of recharge pathways and evapotranspiration processes. These data indicate that some combination of two plausible processes is occurring: (1) complete evaporation of rainfall occurs, and the precipitated salts are washed down and redissolved when recharge occurs, and (2) transpiration dominates over evaporation. It is surmised that sinkholes predominantly serve to by-pass the shallow soil zone and redistribute infiltration into the deeper unsaturated zone, rather than transferring rainfall directly to the water table. Chlorofluorocarbon measurements were used in approximating recharge origins to account for coastal proximity effects in the CMB method and pumping seasonality was accounted for in the WTF-based recharge estimates. Best estimates of spatially and temporally averaged recharge rates for the basin are 52-63 and 47-129 mm/year from the CMB and WTF analyses, respectively. Adaptations of both the CMB and WTF analyses to account for nuances of the system were necessary, demonstrating the need for careful application of these methods.

  16. Petroleum geology and exploration of Tarim Basin, China

    SciTech Connect

    Liang Di-Gang; Jia Cheng-Zao

    1996-12-31

    Since 1989 CNPC has carried on large-scale oil and gas exploration and geological research in Tarim Basin of Xinjiang Province, China. Twelve thousand km 2D seismic, 4500 km{sup 2} 3D seismic, and 200 exploratory wells have been completed; ninety-five wells yield commercial oil or gas flows. At this time, eight oil/gas fields have been discovered; they include Lunnan, Yaha, and Tazhong No. 4, having proved 2.7x10{sup 8}t of oil and 109.2x10{sup 9}m{sup 3} of gas in place. Two million six hundred thousand tons of crude oil was yielded in 1995 and 5x10{sup 8}t crude oil will be produced in 1997. The facies of discovered oil-gas pools in Tarim Basin are complex: there are condensate gas pools, volatile oil pools, normal oil pools, and some heavy oil pools. Structural traps form 80% of oil-gas pools. Oil-gases are mainly reservoired in sandstone beds. The burial depths of oil-gas pools range mainly from 4000 to 5500m. Oil and condensate gas occupy 60% and 40% of proved reserves respectively. Oil-gas pools are mainly distributed in the Mesozoic-Cenozoic group, in which Tertiary occupies 50%, Triassic occupies 30% and Carboniferous occupies 20%. Tarim Basin is a large overlapped composite basin, composed of Paleozoic cratonic basins and Mesozoic-Cenozoic foreland basins. Paleozoic and Mesozoic-Cenozoic oil-gas pools have different distribution character. Paleozoic oil-gas accumulations are controlled by cratonic paleo-uplifts and slopes. Mesozoic-Cenozoic oil-gas accumulations are controlled by foredeep uplifts and imbricate thrust structures of foreland thrust belts.

  17. Petroleum geology and exploration of Tarim Basin, China

    SciTech Connect

    Liang Di-Gang; Jia Cheng-Zao )

    1996-01-01

    Since 1989 CNPC has carried on large-scale oil and gas exploration and geological research in Tarim Basin of Xinjiang Province, China. Twelve thousand km 2D seismic, 4500 km[sup 2] 3D seismic, and 200 exploratory wells have been completed; ninety-five wells yield commercial oil or gas flows. At this time, eight oil/gas fields have been discovered; they include Lunnan, Yaha, and Tazhong No. 4, having proved 2.7x10[sup 8]t of oil and 109.2x10[sup 9]m[sup 3] of gas in place. Two million six hundred thousand tons of crude oil was yielded in 1995 and 5x10[sup 8]t crude oil will be produced in 1997. The facies of discovered oil-gas pools in Tarim Basin are complex: there are condensate gas pools, volatile oil pools, normal oil pools, and some heavy oil pools. Structural traps form 80% of oil-gas pools. Oil-gases are mainly reservoired in sandstone beds. The burial depths of oil-gas pools range mainly from 4000 to 5500m. Oil and condensate gas occupy 60% and 40% of proved reserves respectively. Oil-gas pools are mainly distributed in the Mesozoic-Cenozoic group, in which Tertiary occupies 50%, Triassic occupies 30% and Carboniferous occupies 20%. Tarim Basin is a large overlapped composite basin, composed of Paleozoic cratonic basins and Mesozoic-Cenozoic foreland basins. Paleozoic and Mesozoic-Cenozoic oil-gas pools have different distribution character. Paleozoic oil-gas accumulations are controlled by cratonic paleo-uplifts and slopes. Mesozoic-Cenozoic oil-gas accumulations are controlled by foredeep uplifts and imbricate thrust structures of foreland thrust belts.

  18. Polybrominated diphenyl ethers in seafood products of south China.

    PubMed

    Guo, Jian-Yang; Wu, Feng-Chang; Mai, Bi-Xian; Luo, Xiao-Jun; Zeng, Eddy Y

    2007-10-31

    South China is probably one of the heaviest polybrominated diphenyl ether (PBDE) polluted regions in the world, thanks to the presence of huge and rapidly growing electronics manufacturing industries, as well as several of the world's largest e-waste recycling sites in the region. In the present work, a wide variety of nonfish seafood products collected from South China was analyzed for PBDE residues. The concentrations of PBDEs in seafood products were highly species-specific, and the magnitude of PBDE pollution was moderate in South China compared to the global levels. Congener patterns of PBDEs in seafood samples suggested that seafood products are prone to accumulating low-brominated congeners, and possible metabolic debromination of BDE-99 to BDE-47 could occur in certain organisms, such as crabs and mantis shrimp. Generally, the congener profile was dominated by BDE-209, and to a lesser extent by BDE-47 and BDE-99, which was consistent with the fact that Deca-BDE is mass-produced in China and with previous sediment results from the same area. The occurrence of BDE-209 in aquatic species from South China suggests that BDE-209 appears to be more bioavailable than previously thought, and the environmental fate and safety of BDE-209 require further investigation and call for a thorough reassessment. PMID:17927196

  19. Seismic facies interpretation of Mesozoic sequences, Shiwandashan basin, China

    SciTech Connect

    Leu, Leikuang; Armentrout, J.M.; Faz, J.J. )

    1991-03-01

    Integration of outcrop and subsurface geologic data with seismic facies analysis identified three exploration plays in Shiwandashan basin, southeastern China: Triassic Submarine Fan: Elongate-mounded packages of variable amplitude, discontinuous, nonparallel reflections occur basinward of the slope and are downlapped by prograding slope clinoforms. This facies is undrilled. Basin modeling suggests the mounded seismic facies correlates with outcrops of Triassic marine siliclastic turbidites which grade laterally into basinal mudstone/limestone couplets. Triassic Shelf Carbonates: Localized, high amplitude parallel reflections occur in a retrograde succession at the top of the Triassic prograding clinoform. These high amplitude seismic facies are calibrated with drilled carbonate facies and are correlated with outcrops of upper Triassic shelf and shelf-edge reefs that contain two generations of migrated hydrocarbons. Jurassic Fan Deltas: Thick northeast-southwest bidirectional downlapping hummocks of variable amplitude reflections and intersecting northwest downlapping clinoforms form large mounds and grade laterally to moderately continuous parallel reflections. The hummocky-clinoform mound facies is calibrated by drilled, poorly sorted conglomerates and correlates with outcrops of a Jurassic synrift basin-fill succession. These Jurassic rocks are interpreted as fan-deltas grading laterally to sandy fluvial and shaley lacustrine facies. The geochemical data suggest a potential gas-prone play for the Triassic submarine fans and potential oil-prone play for the stratigraphically shallower Triassic shelf and shelf-edge reefs. The Jurassic fan delta play drilled tight with no hydrocarbons.

  20. Influence of basin connectivity on sediment source, transport, and storage within the Mkabela Basin, South Africa

    NASA Astrophysics Data System (ADS)

    Miller, J. R.; Mackin, G.; Lechler, P.; Lord, M.; Lorentz, S.

    2012-09-01

    The management of sediment and other non-point source (NPS) pollution has proven difficult, and requires a sound understanding of particle movement through the drainage system. The primary objective of this investigation was to obtain an understanding of NPS sediment source(s), transport, and storage within the Mkabela basin, a representative agricultural catchment within the KwaZulu-Natal Midlands of southeastern South Africa, by combining geomorphic, hydrologic and geochemical fingerprinting analyses. The Mkabela Basin can be subdivided into three distinct subcatchments that differ in their ability to transport and store sediment along the axial valley. Headwater (upper catchment) areas are characterized by extensive wetlands that act as significant sediment sinks. Mid-catchment areas, characterized by higher relief and valley gradients, exhibit few wetlands, but rather are dominated by a combination of alluvial and bedrock channels that are conducive to sediment transport. The lower catchment exhibits a low-gradient alluvial channel that is boarded by extensive riparian wetlands that accumulate large quantities of sediment (and NPS pollutants). Fingerprinting studies suggest that silt- and clay-rich layers found within wetland and reservoir deposits are derived from the erosion of fine-grained, valley bottom soils frequently utilized as vegetable fields. Coarser-grained deposits within both wetlands and reservoirs result from the erosion of sandier hillslope soils extensively utilized for sugar cane, during relatively high magnitude runoff events that are capable of transporting sand-sized sediment off the slopes. Thus, the source of sediment to the axial valley varies as a function of sediment size and runoff magnitude. Sediment export from the basin was limited until the early 1990s, in part because the upper catchment wetlands were hydrologically disconnected from lower parts of the watershed during low- to moderate flood events. The construction of a

  1. Geologic framework and petroleum systems of Cook Inlet basin, south-central Alaska

    USGS Publications Warehouse

    LePain, D.L.; Stanley, R.G.; Helmold, K.P.; Shellenbaum, D.P.

    2013-01-01

    This report provides a comprehensive overview of the stratigraphy, structure, tectonics, and petroleum systems of the Cook Inlet basin, an important oil- and gas-producing region in south-central Alaska.

  2. Basin mass dynamic changes in China from GRACE based on a multibasin inversion method

    NASA Astrophysics Data System (ADS)

    Yi, Shuang; Wang, Qiuyu; Sun, Wenke

    2016-05-01

    Complex landforms, miscellaneous climates, and enormous populations have influenced various geophysical phenomena in China, which range from water depletion in the underground to retreating glaciers on high mountains and have attracted abundant scientific interest. This paper, which utilizes gravity observations during 2003-2014 from the Gravity Recovery and Climate Experiment (GRACE), intends to comprehensively estimate the mass status in 16 drainage basins in the region. We propose a multibasin inversion method that features resistance to stripe noise and an ability to alleviate signal attenuation from the truncation and smoothing of GRACE data. The results show both positive and negative trends. Tremendous mass accumulation has occurred from the Tibetan Plateau (12.1 ± 0.6 Gt/yr) to the Yangtze River (7.7 ± 1.3 Gt/yr) and southeastern coastal areas, which is suggested to involve an increase in the groundwater storage, lake and reservoir water volume, and the flow of materials from tectonic processes. Additionally, mass loss has occurred in the Huang-Huai-Hai-Liao River Basin (-10.2 ± 0.9 Gt/yr), the Brahmaputra-Nujiang-Lancang River Basin (-15.0 ± 1.1 Gt/yr), and Tienshan Mountain (-4.1 ± 0.3 Gt/yr), a result of groundwater pumping and glacier melting. Areas with groundwater depletion are consistent with the distribution of cities with land subsidence in North China. We find that intensified precipitation can alter the local water supply and that GRACE can adequately capture these dynamics, which could be instructive for China's South-to-North Water Diversion hydrologic project.

  3. Drainage areas in the Vermillion River basin in eastern South Dakota

    USGS Publications Warehouse

    Benson, Rick D.; Freese, M.D.; Amundson, Frank D.

    1988-01-01

    Above-normal precipitation in the northern portion of the Vermillion River basin from 1982 through 1987 caused substantial rises in lake levels in the Lake Thompson chain of lakes, resulting in discharge from Lake Thompson to the East Fork Vermillion River. Prior to 1986, the Lake Thompson chain of lakes was thought to be a noncontributing portion of the Vermillion River basin. To better understand surface drainage, the map delineates all named stream basins, and all unnamed basins larger than approximately 10 sq mi within the Vermillion River basin in South Dakota and lists by stream name the area of each basin. Stream drainage basins were delineated by visual interpretation of contour information of U.S. Geological Survey 7 1/2 minute topographic maps. Two tables list areas of drainage basins and reaches, as well as drainage areas above gaging stations. (USGS)

  4. [Chemical characteristics of precipitation in South China Sea].

    PubMed

    Xiao, Hong-Wei; Long, Ai-Min; Xie, Lu-Hua; Xiao, Hua-Yun; Liu, Cong-Qiang

    2014-02-01

    Rainwater samples were collected in the summer on "Shiyan 3" during the 2012 South China Sea Sectional Scientific Survey. The concentrations of anion and cation, and pH in precipitation were determined and backward trajectories of air mass were simulated to analyze the chemical characteristics of ions and examine the source of ions. The results indicated that the mean pH value of precipitation was 6.3, with 5.6 of minimal value in summer in South China Sea. The order of anion and cation abundance was Cl(-) > S04(2-) > NO3(-) and Na(+) > Mg(2+) > Ca(2+) > K(+). Cl(-) was the major anion and Na(+) was the major cation, with concentrations of 2 637.5 microeq x L(-1) and 2095.5 microeq x L(-1), respectively, showing that they were the characteristics of marine atmospheric precipitation. There was a good linear relationship between each pair of 7 ions, with correlation coefficient above 0.9, suggesting that they may have a common source. However, the correlation coefficients were lower between NO3(-) and other ions than the others, suggesting that NO3(-) had more complex sources. The concentrations of Ca(2+) and K(+) in precipitation may be related to coral environment in South China Sea. The backward trajectories in 6 stations showed that the air mass was from south and southwest of South China Sea, without passing through above the continent. These results suggested that precipitation affected by human ion source can be ignored in summer in South China Sea.

  5. National assessment of oil and gas project; petroleum systems and assessment of the South Florida Basin

    USGS Publications Warehouse

    Pollastro, R. M.; Schenk, C.J.

    2001-01-01

    This CD-ROM contains coverages that define and outline the geographic boundaries of petroleum systems and assessment units and text that describes the geology and reasoning to support the assessment of undiscovered oil and gas resources in the South Florida Basin for a forecast period of 30 years. This assessment was performed by using the best geological information and scientific theory available to the USGS; however, the USGS did not have access to seismic survey data for the South Florida Basin.

  6. Petroleum geology of Giant oil and gas fields in Turpan Basin Xinjiang China

    SciTech Connect

    Boliang, Hu; Jiajing, Yang,

    1995-08-01

    Turpan Basin is the smallest and the last development basin in three big basins of Xinjiang autonomous region, P.R. China. Since April, 1989, the Shanshan oilfield was discovered, the Oinling, Wenjisang, Midang, Baka, Qiudong and North Putaogou fields were discovered. In 1994, the crude oil productivity of Turpan Basin was a Million tons, with an estimated output of 3 million tons per year by 1995; obviously a key oil productive base in the west basins of China, Tarim, Jungar, Chaidam, Hexi, Erduos and Sichuan Basins. The Turpan Basin is an intermontane basin in a eugeosyncline foldbelt of the north Tianshan Mountains. The oil and gas was produced from the payzone of the Xishanyao, Sanjianfang and Qiketai Formatiosn of the Middle Jurassic series. The geochemical characteristics of the crude oil and gas indicate they derive from the Middle to Lower Jurassic coal series, in which contains the best oil-prone source rocks in the basin.

  7. The origin of gas seeps and shallow gas in northern part of South China Sea

    NASA Astrophysics Data System (ADS)

    Li, M.; Jin, X.

    2003-04-01

    The northern part of South China Sea is of passive continental margin, which geologic units include shelf, slope and deep sea basin. There are rifting basins forming during Paleogene (or Cretaceous ?) to Quaternary developed on shelf and slope, which sediments are dominated by fluvial and lake clastic rock of Paleogene, and marine clastic rock and carbonate of Neogene - Quaternary. The main basins include the Pearl River Mouth Basin, Beibu Gulf basin, Qiongdongnan Basin and Yinggehai basin. They contain rich oil and gas resources, and have become important industrial oil and gas producing region in South China Sea. With the increasing of petroleum exploration actives and marine petroleum engineering, it has been paid more attention to the investigation and research of gas seeps and shallow gas, for they become a potential threaten to the marine engineering while they are regarded as the indicators of industrial oil and gas. By study the distribution and geochemical characteristics of gas seeps in northeast part of Yinggehai basin and shallow gas in sediments on slope, combined with their regional geologic background, this paper deals with the origin, migration pathway and emission mechanism of gas seeps and shallow gas in northern part of South China Sea, for providing a base knowledge for the evaluation of marine engineering geology. In northeast part of Yinggehai basin gas seeps have been found and recorded for near 100 years. During 1990s, as a part of petroleum exploration, the gas seeps in the basin have been investigated and research by oil companies (Baojia Huang et al., 1992; Jiaqiong He et al., 2000). Gas seeps were found in shallow water area along southwest coast of Hainan Island, water depth usually less than 50 m. The occurrence of gas seeps can be divided into two types: (1) gas continuously emission, continuous gas bubbles groups can be detected by sonar underwater and observed on water surface. (2) gas intermittently emission, the time intervals

  8. Origin of back-arc basins and effects of western Pacific subduction systems on eastern China geology

    NASA Astrophysics Data System (ADS)

    Niu, Y.

    2013-12-01

    Assuming that subduction initiation is a consequence of lateral compositional buoyancy contrast within the lithosphere [1], and recognizing that subduction initiation within normal oceanic lithosphere is unlikely [1], we can assert that passive continental margins that are locations of the largest compositional buoyancy contrast within the lithosphere are the loci of future subduction zones [1]. We hypothesize that western Pacific back-arc basins were developed as and evolved from rifting at passive continental margins in response to initiation and continuation of subduction zones. This hypothesis can be tested by demonstrating that intra-oceanic island arcs must have basement of continental origin. The geology of the Islands of Japan supports this. The highly depleted forearc peridotites (sub-continental lithosphere material) from Tonga and Mariana offer independent lines of evidence for the hypothesis [1]. The origin and evolution of the Okinawa Trough (back-arc basin) and Ryukyu Arc/Trench systems represents the modern example of subduction initiation and back-arc basin formation along a (Chinese) continental margin. The observation why back-arc basins exit behind some subduction zones (e.g., western Pacific) but not others (e.g., in South America) depends on how the overlying plate responds to subduction, slab-rollback and trench retreat. In the western Pacific, trench retreat towards east results in the development of extension in the upper Eurasian plate and formation of back-arc basins. In the case of South America, where no back-arc basins form because trench retreat related extension is focused at the 'weakest' South Mid-Atlantic Ridge. It is thus conceptually correct that the South Atlantic is equivalent to a huge 'back-arc basin' although its origin may be different. Given the negative Clayperon slope of the Perovskite-ringwoodite phase transition at the 660 km mantle seismic discontinuity (660-D), slab penetration across the 660-D is difficult and

  9. Comparative analysis of post-breakup basin evolution along the South-American and South-African margins, southern Atlantic

    NASA Astrophysics Data System (ADS)

    Strozyk, F.; Back, S.; Kukla, P. A.

    2012-04-01

    Recently, considerable attempts have been made to compare the sedimentary basin evolution and the associated tectonic framework on both sides of the South-Atlantic. However, yet there are still unresolved questions concerning the tectono-sedimentary styles of margin basin evolution that markedly differ from north to south. Amongst the most striking observations is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic margin segment on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. Adding to the heterogeneity of the system, the northernmost segment of the South Atlantic rift and salt basins is also characterized by a pronounced asymmetry, with the Brazilian margin now comprising narrower and deeper rift basins with less salt than the Congo-Gabon conjugate margin. This project deals with a large-scale comparison of this very different post-breakup tectono-stratigraphic development of the southern and northern South American and African continental margins that both record thick post-rift sedimentary successions. To gain detail of the basin margin evolution, we focus on a regional comparison between the post-breakup records archived in the large offshore southern Brazil basins (Pelotas, Santos, Campos) and the post-breakup continental margin successions of offshore Namibia (e.g. Orange Basin) and southern Angola (e.g. Kwanza Basin). A tectonic-stratigraphic comparison of representative geological transects provides a comprehensive basin-to-basin documentation of key factors influencing margin development which include the subsidence development through time, the sediment (in-)flux and storage patterns and the respective type of basin fill (e.g. salt vs. non-salt systems; carbonate-rich vs. clastics-dominated systems). Data from the salt-prone areas offshore South America and southern

  10. Paleomagnetic Results From Triassic Rock Formations of Junggar Basin, NW China

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Li, J.; Guo, R.; Zhang, W.; Yuan, W.

    2015-12-01

    Our knowledge of the kinematics and duration of collisional events between the Chinese blocks and Siberia is still inadequate. Likewise, the accretionary history of the Central Asian fold belt itself is contentious. The primary goal for this study was to address key questions about the geographic positions of the Junggar Basin in Paleozoic and Mesozoic times and its tectonic relationship with other major Asian blocks by generating high-quality paleomagnetically inferred paleolatitudes and basin histories. Another objective is to see what it can tell us about intraplate motions within central Asia and to recognize vertical-axis tectonic rotations in the region. We collected 348 samples from 42 sites in Paleozoic and Mesozoic stratigraphic sections of east Junggar Basin. Useful results were obtained by progressive demagnetization for sandstone samples of Xiaoquan Formation dated paleontologically as mid to late Triassic. The ChRM direction for the Xiaoquan Formation is directed easterly with intermediate to steep downward inclination in geographic coordinates. After tectonic correction, the mean direction of the ChRM becomes northeasterly with intermediate to shallow inclination, which corresponds to a mean paleolatitude of 20.7° within a 95% confidence band of ± 12 degrees. It is obvious from the data that Junggar and other major parts of eastern Asia did not occupy the same relative positions in terms of paleolatitudes in Late Triassic. Paleomagnetic declinations indicate clockwise vertical-axis rotations of R = 98.3° +/- 16° for the Late Triassic rock unit relative to North China Block (NCB), and 12.4° +/- 16.2° relative to South China Block (SCB). The paleomagnetically inferred latitudinal displacements between Junggar and SCB are general statistically insignificant, as well as the rotational data. These data suggest that Junggar Basin may have been very close to SCB during the Triassic time. A plausible cause of the rotation is the westward rotational

  11. 76 FR 71260 - Drawbridge Operation Regulation; China Basin, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-17

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; China Basin, San Francisco, CA AGENCY... of the Third Street Drawbridge across China Basin, mile 0.0, at San Francisco, CA. The deviation is necessary to allow the City of San Francisco to inspect the bridge structure as required by the...

  12. 78 FR 31414 - Drawbridge Operation Regulation; China Basin, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-24

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; China Basin, San Francisco, CA AGENCY... the China Basin, mile 0.0, at San Francisco, CA. The deviation is necessary to allow the public to cross the bridge to participate in the scheduled San Francisco Marathon, a community event....

  13. 78 FR 43796 - Drawbridge Operation Regulation; China Basin, San Francisco, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-22

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; China Basin, San Francisco, CA AGENCY... the China Basin, mile 0.0 at San Francisco, CA. The deviation is necessary to allow the bridge to be... Building, 1200 New Jersey Avenue SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday...

  14. Mooring observations and numerical modeling of thermal structures in the South China Sea

    NASA Astrophysics Data System (ADS)

    Chang, Ya-Ting; Yung Tang, Tswen; Chao, Shenn-Yu; Chang, Ming-Huei; Ko, Dong S.; Jang Yang, Yiing; Liang, Wen-Der; McPhaden, Michael J.

    2010-10-01

    Three sets of Autonomous Temperature Line Acquisition Systems were deployed in the South China Sea. Gaps aside, the data covered nearly 3 years at the northern station and about 2 years farther south. Fluctuations ranged from episodic to interannual. Internal tides, more diurnal than semidiurnal, were active basinwide. Twelve typhoons passed during measurement periods. The most severe one, typhoon Babs in 1998, caused a temperature drop of over 7°C at 50 m. Despite strong monsoons, only near-surface temperature showed clear seasonal variations. Intraseasonal variations induced by mesoscale eddy stood out much better at subsurface depths. Propagating eddies aside, some eddies were seasonal and nearly stationary. From daily archives of an eddy-resolving, data-assimilating ocean model (East Asian Seas Nowcast/Forecast System), we identified two paradigms leading to the generation of a persistent spring-summer warm eddy in the central-western basin. In normal years, a complete cyclonic gyre was driven by a strong winter northeast monsoon. Water piled up along the periphery of the South China Sea. Afterward, a warm eddy could be generated from west of Luzon Island and propagated westward while intensifying. Under a weak northeast monsoon, such as in El Niño years, piled-up water tended to stay in the southern basin. When the wind relaxed in spring, warm water returned northward to form a warm eddy in the central-western basin. Transition from SW to NE monsoon also often led to a warm eddy generation in southern latitudes, when the summer eastward jet departing from central Vietnam broke up.

  15. Antecedents of Medical Workplace Violence in South China

    ERIC Educational Resources Information Center

    Cai, Wenzhi; Deng, Ling; Liu, Meng; Yu, Min

    2011-01-01

    It has been noted that workplace violence most frequently occurs in hospitals. The purpose of this study was to explore antecedents of workplace violence in south China. The authors conducted face-to-face, in-depth, semistructured interviews with 30 hospital staff who had experienced at least one incident of workplace violence from patients during…

  16. Influence of basin connectivity on sediment source, transport, and storage within the Mkabela Basin, South Africa

    NASA Astrophysics Data System (ADS)

    Miller, J. R.; Mackin, G.; Lechler, P.; Lord, M.; Lorentz, S.

    2013-02-01

    The management of sediment and other non-point source (NPS) pollution has proven difficult, and requires a sound understanding of particle movement through the drainage system. The primary objective of this investigation was to obtain an understanding of NPS sediment source(s), transport, and storage within the Mkabela Basin, a representative agricultural catchment within the KwaZulu-Natal Midlands of eastern South Africa, by combining geomorphic, hydrologic and geochemical fingerprinting analyses. The Mkabela Basin can be subdivided into three distinct subcatchments that differ in their ability to transport and store sediment along the axial valley. Headwater (upper catchment) areas are characterized by extensive wetlands that act as significant sediment sinks. Mid-catchment areas, characterized by higher relief and valley gradients, exhibit few wetlands, but rather are dominated by a combination of alluvial and bedrock channels that are conducive to sediment transport. The lower catchment exhibits a low-gradient alluvial channel that is boarded by extensive riparian wetlands that accumulate large quantities of sediment (and NPS pollutants). Fingerprinting studies suggest that silt- and clay-rich layers found within wetland and reservoir deposits of the upper and upper-mid subcatchments are derived from the erosion of fine-grained, valley bottom soils frequently utilized as vegetable fields. Coarser-grained deposits within these wetlands and reservoirs result from the erosion of sandier hillslope soils extensively utilized for sugar cane, during relatively high magnitude runoff events that are capable of transporting sand-sized sediment off the slopes. Thus, the source of sediment to the axial valley varies as a function of sediment size and runoff magnitude. Sediment export from upper to lower catchment areas was limited until the early 1990s, in part because the upper catchment wetlands were hydrologically disconnected from lower parts of the watershed during

  17. Upper Mantle Anisotropy Beneath the Ordos Basin in China and its geodynamic significance

    NASA Astrophysics Data System (ADS)

    Wang, Liangshu; Mi, Ning; Huang, Zhouchuan; Xu, Mingjie

    2016-04-01

    The Ordos basin is a stable block between the Eastern and Western China, and surrounded by active thrust belts and extensional graben systems. Investigations on the upper-mantle deformation and flowing pattern beneath the Ordos basin will help to illuminate how the different geodynamical processes affect the intra-continental deformation in China. From five portable seismic arrays in the southern Ordos block, SKS and SKKS phases are used to estimate the S-wave splitting parameters. The results show distinct anisotropy in the upper mantle beneath the Ordos area. To the southwest of the Ordos, the orientations of anisotropy are NNW-SSE, which are subparallel to the thrust belt and boundary faults between the Ordos and the Northeast Tibetan Plateau, mapping a clockwise mantle flow induced by the eastward extrusion of the Northeast Tibetan Plateau and deflected by the Ordos block. To the south of the Ordos, mantle flow direction is nearly E-W, parallel to the strike-slip direction of the Weihe graben, indicating an eastward mantle flow from the NE Tibetan plateau to the eastern part of China. To the east of the Ordos, the direction of fast S-wave is changing slowly from NWW-SSE to E-W, perpendicular to the main tectonic direction in Shanxi graben system, showing an extension feature similar to that of the North China. Above results illuminate much information on the mass deformation and migration in the upper mantle resulting from the interactions between the Ordos block and its surrounding dynamic systems. It can be seen that the thrust faults and extensional grabens around the Ordos block are the positions where the anisotropy shows obvious change. As the boundary area of different blocks, they are the key areas to adjust the transformation between different geodynamic systems.

  18. Climate warming, euxinia and carbon isotope perturbations during the Carnian (Triassic) Crisis in South China

    NASA Astrophysics Data System (ADS)

    Sun, Y. D.; Wignall, P. B.; Joachimski, M. M.; Bond, D. P. G.; Grasby, S. E.; Lai, X. L.; Wang, L. N.; Zhang, Z. T.; Sun, S.

    2016-06-01

    The Carnian Humid Episode (CHE), also known as the Carnian Pluvial Event, and associated biotic changes are major enigmas of the Mesozoic record in western Tethys. We show that the CHE also occurred in eastern Tethys (South China), suggestive of a much more widespread and probably global climate perturbation. Oxygen isotope records from conodont apatite indicate a double-pulse warming event. The CHE coincided with an initial warming of 4 °C. This was followed by a transient cooling period and then a prolonged ∼7 °C warming in the later Carnian (Tuvalian 2). Carbon isotope perturbations associated with the CHE of western Tethys occurred contemporaneously in South China, and mark the start of a prolonged period of carbon cycle instability that persisted until the late Carnian. The dry-wet transition during the CHE coincides with the negative carbon isotope excursion and the temperature rise, pointing to an intensification of hydrologic cycle activities due to climatic warming. While carbonate platform shutdown in western Tethys is associated with an influx of siliciclastic sediment, the eastern Tethyan carbonate platforms are overlain by deep-water anoxic facies. The transition from oxygenated to euxinic facies was via a condensed, manganiferous carbonate (MnO content up to 15.1 wt%), that records an intense Mn shuttle operating in the basin. Significant siliciclastic influx in South China only occurred after the CHE climatic changes and was probably due to foreland basin development at the onset of the Indosinian Orogeny. The mid-Carnian biotic crisis thus coincided with several phenomena associated with major extinction events: a carbonate production crisis, climate warming, δ13 C oscillations, marine anoxia, biotic turnover and flood basalt eruptions (of the Wrangellia Large Igneous Province).

  19. Geodynamic scenario and structural styles of Mesozoic and Cenozoic basins in China

    SciTech Connect

    Hefu, L.

    1986-04-01

    The continental lithosphere of China is situated at the junction of the Marginal-Pacific and Tethys-Himalayan tectonic domains. The most manifest tectonic movements responsible for the deformation of the continental lithosphere of China are taphrogenic, collisional, and shearing. These movements played an important role in the Mesozoic and Cenozoic tectonic evolution of China and formed various types of Mesozoic and Cenozoic basins in China. The Marginal-Pacific crust in eastern China was attenuated by rifting and developed north-northeast-trending Mesozoic and Cenozoic basins, e.g., the Songliao, Bohai Bay, and Jianghan basins. Rifting mainly followed preexisting lineaments or shear zones in the basement. Then basin-range (graben-horst) structures and large fault-bounded basins developed. Extensional structural styles have prevailed in Mesozoic and Cenozoic basins in eastern China, with listric faults and tilted blocks in the basement, and detached faults, growth faults, and rollover anticlines or drape folds in the cover rocks. These structures are favorable for hydrocarbon accumulation; thus, the famous Daqing and Zhongyuan oil fields formed in Songliao basin and Bohai Bay basin, respectively. In western China the continental crust thickened by collision and formed a series of Mesozoic and Cenozoic intermontane and foreland basins, such as the Junggar (Dzungaria), Tarim, and Qaidam basins. Contraction structural styles are predominant in Mesozoic and Cenozoic basins in western China, with shortened fault blocks and ramps in basement, and thrust faults and folds in the cover rocks. The Kelamayi and Laojunmiao oil fields formed in these compressional basins. 22 figures, 1 table.

  20. Water resources: the prerequisite for ecological restoration of rivers in the Hai River Basin, northern China.

    PubMed

    Tang, Wenzhong; Mao, Zhanpo; Zhang, Hong; Shan, Baoqing; Zhao, Yu; Ding, Yuekui

    2015-01-01

    The competition for water resources between humans and river ecosystems is becoming ever more intense worldwide, especially in developing countries. In China, with rapid socioeconomic development, water resources to maintain river ecosystems are progressively decreasing, especially in the Hai River Basin (HRB), which has attracted much attention from the Chinese government. In the past 56 years, water resources have continuously decreased in the basin, such that there is 54.2 % less surface water now compared with then. Water shortages, mainly due to local anthropogenic activities, have emerged as the main limiting factor to river ecological restoration in the HRB. However, the South-to-North Water Diversion Project, the largest such project in the world, presents a good opportunity for ecological restoration of rivers in this basin. Water diverted from the Danjiangkou Reservoir will restore surface water resources in the HRB to levels of 30 years ago and will amount to more than 20 billion m(3). Our findings highlight the fact that water resources are crucial for river ecological restoration.

  1. Badlands in humid regions - redbed desertification in Nanxiong Basin, China

    NASA Astrophysics Data System (ADS)

    Yan, Luobin; Hua, Peng; Simonson, Scott

    2016-04-01

    The redbed badlands in Nanxiong City, China, well represent badlands in humid regions. The erosion rate in humid regions is much higher than that in arid regions and can reach 1 cm per month during the summer. The purpose of this study is to introduce the research of badlands in China, which have not been extensively studied so far, and to compare the badlands between arid and humid regions. Furthermore, the aim is to study the impact of mineralogical and chemical composition on the disintegration of soft rock in Nanxiong Basin badlands. For the purpose of this study field observations, sampling, and digging profiles were done. The mineralogical and chemical compositions of the Nanxiong Basin badland lithologies were determined by XRD, XRF and thin sections. Weathering resistance, process of weathering, and disintegration features were studied by weathering experiments under natural conditions. Weathering profiles can be easily divided into four layers: regolith, a strongly weathered layer, a poorly weathered layer, and an unweathered sediment. The depth of the weathering profile is influenced by the weathering resistance of the soft rock. Weathering resistance affects the erosion rate and evolution of landforms in badlands by influencing the rate from unweathered rock to regolith. Analyzed sediments have high content of illite and illite-smectite interstratifications. This composition of clay minerals together with poor sediment consolidation jointly leads to weathering prone sediment. The weathering and disintegration of soft rock in Nanxiong Basin badlands has a close relationship with rainfall. Sheet erosion, a kind of solid-liquid phase flow, formed in the regolith of the badland during rainfall events and can be the most instrumental to erosion. The mineral composition and liquidity plasticity index were also analyzed, and the results show that the regolith are low liquid limit silts with liquid limit of 21%-25%, plastic limit of 13%-18% and plasticity index

  2. Oil-shale mining in Maoming basin of China

    SciTech Connect

    Mitchell-Tapping, H.J.

    1989-03-01

    The Maoming basin in Guangdong Province is one of the major oil-shale mining areas of China and is situated about 300 km southwest of Hong Kong. This Tertiary basin produces oil from shales mined from a 5-km long open-faced pit on the crest of an anticline in the center of an uplifted and tilted graben. The oil shale extends about 30 km in a northwest-southeast line, and the beds dip as much as 10/degree/ toward metamorphic mountains to the northeast. In the surrounding area are numerous oil seeps, especially in ponds, water wells, and at the foundations of buildings. Holes with oil shows, made to test the extent of the oil shale, have been drilled to a depth of 1000 m. At the base of the mine face is a limestone hardground on top of which is a coal seam about 0.5 m thick that can be traced throughout the basin. Atop this Paleocene coal bed are Eocene oil-shale and thin sandstone beds in five repeated sections, each about 15 m thick, called the Youganwou formation. All kinds of freshwater fossils - fish, insects, plants, turtles, and tree trunks - are found in a near-perfect state of preservation in these oil-rich shales and coal sections. The estimated oil content of the rock is about 8% of good-quality oil with plenty of light ends.

  3. Yardangs in the Qaidam Basin, northwestern China: Distribution and morphology

    NASA Astrophysics Data System (ADS)

    Li, Jiyan; Dong, Zhibao; Qian, Guangqiang; Zhang, Zhengcai; Luo, Wanyin; Lu, Junfeng; Wang, Meng

    2016-03-01

    The northwestern Qaidam Basin exposes one of the largest and highest elevation yardang fields on Earth. The aim of the present study was to describe the distribution and morphology of these yardangs, and analyze the factors responsible for the distribution pattern of these aeolian landforms. The yardang fields are bounded by piedmont alluvial-diluvial fans from the mountain ranges surrounding the basin, except in the south, where they are bounded by dune fields, dry salt flats, lakes, and rivers. This distribution pattern can be attributed to regional tectogenesis and its corresponding environmental impacts. The morphology of the yardangs varies considerably in response to the diverse factors that control their formation and evolution. Long-ridge yardangs are mainly located in the northernmost part of the yardang field, and the long ridges are gradually dissected into smaller ridges in the downwind direction. Further downwind, the convergence of northerly and northwesterly winds and the effects of temporary runoff cause the ridges to gradually transition into mesa yardangs. Saw-toothed crests, and conical and pyramidal yardangs, occur in groups on folded brachyanticlinal structures. Typical whaleback yardangs are found in the southeast, at the northern margin of Dabuxun Lake. Morphological parameters vary among the yardang types. The orientation of the yardangs in the northernmost area is nearly N-S, with a transition towards NW-SE in the southernmost area in response to a change in the dominant wind direction that results from the orientations and positions of the mountain ranges that surround the basin.

  4. 75 FR 61414 - Basin Electric Power Cooperative: South Dakota PrairieWinds Project

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... Rural Utilities Service Basin Electric Power Cooperative: South Dakota PrairieWinds Project AGENCY...) for the Environmental Impact Statement (EIS) for the proposed South Dakota PrairieWind Project...-megawatt wind-powered generation facility. ADDRESSES: To obtain copies of the ROD, or for...

  5. Transfer structures in the Northern Tarim Basin, Northwest China

    SciTech Connect

    Guang-Ya Zhang; Shi-Xia Gao

    1996-03-01

    The fold-thrust tectonics of the Northern Tarim Basin, oriented roughly parallel to the South Tianshan orogenic belt, consists of two large-scale tectonic regimes: (1) the foreland-basin, thin-skinned deformation belt; and (2) the foreland-craton, thick-skinned-dominated (i.e., basement-involved) deformation belt. Variations in the degree of deformation in these tectonic belts and style along the regional tectonic strike can be accounted for by longitudinal (progressive transfer or transverse (abrupt) transfer). Longitudinal transfer maintains the overall displacement or shortening within the fold-thrust belts as uniform or with gradual change along the tectonic strike. This includes the tectonic transfer between en echelon master thrusts and from the individual master thrust to terminal fold(s) or distributive thrusts. Transverse transfer resulted from an abrupt change in overall displacement or shortening along the tectonic strike. Within the transverse transfer zone, various tectonics-such as strike-slip faults, strike-slip thrusts, transverse anticlines, and en echelon folds-are developed. The development of longitudinal transfer zones can be attributed to the gradual variation of intrinsic and extrinsic and extrinsic deformational conditions along the tectonic strike. The initiation of transverse transfer may be related to variations in the thickness of sedimentary layers, detachment-layer distribution limits, and variation along strike of the degree and mode of the South Tianshan orogenic belt`s effect on the basin, as well as the variation of the boundary conditions of the deformation, such as in the geometry of plate margins. 15 refs., 8 figs.

  6. Implications of IODP Expedition 349 Age Results for the Spreading History of the South China Sea

    NASA Astrophysics Data System (ADS)

    Briais, Anne

    2016-04-01

    The International Ocean Discovery Program (IODP) Expedition 349 in the South China Sea drilled three sites (U1431, U1433, and U1434) into the basaltic crustal basement near the fossil spreading center in the East and Southwest Subbasins. These results provided age constraints on the termination of seafloor spreading in the South China Sea (SCS) basin. Shipboard biostratigraphic analysis of microfossils from the sediment immediately above or between flows in the basaltic basement indicates early Miocene ages: 16.7-17.6 Ma for Site U1431 in the East Subbasin, ~18-21 Ma for Site U1433 in the Southwest Subbasin. Since Expedition 349, Ar/Ar dating of basalt samples from these two sites have confirmed these ages in the east, and have provided an age of 17 Ma in the Southwest. The similarity in crustal age between sites suggests that the last stages of spreading have been coeaval in both the East and Southwest Subbasins, forming a single mid-ocean ridge system with a series of transform faults and discontinuities between the two subbasins. Expedition 349 also drilled Site U1435 on a bathymetric high along the northwestern continent-ocean boundary. Onboard core description, biostratigraphy and magnetostratigraphy revealed that sediment at this site shows a sharp discontinuity at about 33 Ma, interpreted to represent the breakup unconformity and date the beginning of seafloor spreading in the East Subbasin. The results of IODP Exp. 349, as well as results from deep-towed magnetic surveys, thus imply that oceanic seafloor spreading in the SCS, from 33 to ~16-18 Ma, is coeval with a large part of the left-lateral motion along the Ailao Shan-Red River Fault Zone (dated 34 to 17 Ma). This episode of the extension of the South China Sea basin is therefore more likely driven by the extrusion of the Indochina tectonic block resulting from the collision of India with Eurasia than by the subduction of a proto-South China Sea to the south.

  7. Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.

    PubMed

    Wu, Ya; Wang, Yanxin

    2014-05-01

    A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The δ(2)H, δ(18)O ratios in precipitation exhibited a local meteoric water line of δ(2)H = 6.4 δ(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime.

  8. Geochemical evolution of groundwater salinity at basin scale: a case study from Datong basin, Northern China.

    PubMed

    Wu, Ya; Wang, Yanxin

    2014-05-01

    A hydrogeochemical investigation using integrated methods of stable isotopes ((18)O, (2)H), (87)Sr/(86)Sr ratios, Cl/Br ratios, chloride-mass balance, mass balance and hydrogeochemical modeling was conducted to interpret the geochemical evolution of groundwater salinity in Datong basin, northern China. The δ(2)H, δ(18)O ratios in precipitation exhibited a local meteoric water line of δ(2)H = 6.4 δ(18)O -5 (R(2) = 0.94), while those in groundwater suggested their meteoric origin in a historically colder climatic regime with a speculated recharge rate of less than 20.5 mm overall per year, in addition to recharge from a component of deep residual ancient lake water enriched with Br. According to the Sr isotope binary mixing model, the mixing of recharges from the Shentou karst springs (24%), the western margins (11%) and the eastern margins (65%) accounts for the groundwater from the deep aquifers of the down-gradient parts in the central basin is a possible mixing mechanism. In Datong, hydrolysis of silicate minerals is the most important hydrogeochemical process responsible for groundwater chemistry, in addition to dissolution of carbonate and evaporites. In the recharge areas, silicate chemical weathering is typically at the bisiallitization stage, while that in the central basin is mostly at the monosiallitization stage with limited evidence of being in equilibrium with gibbsite. Na exchange with bound Ca, Mg prevails at basin scale, and intensifies with groundwater salinity, while Ca, Mg exchange with bound Na locally occurs in the east pluvial and alluvial plains. Although groundwater salinity increases with the progress of water-rock/sediment interactions along the flow path, as a result of carbonate solubility control and continuous evapotranspiration, Na-HCO3 and Na-Cl-SO4 types of water are usually characterized respectively in the deep and the shallow aquifers of an inland basin with a silicate terrain in an arid climatic regime. PMID:24737419

  9. Metamorphism of Triassic sediments from the Dunbarton Basin, South Carolina

    SciTech Connect

    Snipes, D.S.; Warner, R.D. . Earth Sciences Dept.); Price, V. Jr. ); Thayer, P. . Geology Dept.)

    1993-03-01

    Modal analyses and microprobe studies were performed on eight core samples obtained from the US Geological Survey Well A1 324. The well is situated in the southern part of the buried Triassic Dunbarton Basin, about 1 km south of the US Department of Energy's Westinghouse Savannah River Company Site. The samples came from an interval of 407.0--413.4 m beneath the land surface. At the well site, Triassic red beds are overlain by Late Cretaceous and Tertiary sediments which have an aggregate thickness of 408 m. The sample from a depth of 407 m is a weathered, poorly sorted, clayey sandstone from the basal portion of the Late Cretaceous Cape Fear Formation. This specimen is not metamorphosed; whereas, the Triassic specimens taken from an interval of 411.6--413.4 m exhibit evidence of thermal metamorphism as well as hydrothermal alteration. In hand specimen, three of the samples (412.8--413.4 m) resemble hornfelses. These samples exhibit decussate texture. Results of modal analyses of the two deepest specimens follow: plagioclase (43-52%), quartz (9-23%), chlorite (22-29%), epidote (1-6%), hematite (3-4%), and magnetite (2-3%). Relict detrital quartz grains, especially the finer ones, are mostly angular-to-subangular and the grain boundaries show little evidence of rounding. The authors feel that hydrothermal alteration was the principal metamorphic process. This belief is supported by the fact that most of the plagioclase has undergone extensive sericitization. In addition, the presence of abundant chlorite together with a minor amount of epidote supports this interpretation. The alteration halo extends upward for 1.8 m. This interpretation is based on the observation that two Triassic arkose sandstone specimens (411.6 m, 412.2 m) contain clouded, slightly sericitized K-feldspar and plagioclase grains in a matrix of red-colored smectite.

  10. Seismic stratigraphy of the Qiongdongnan deep sea channel system, northwest South China Sea

    NASA Astrophysics Data System (ADS)

    Yuan, Shengqiang; Lü, Fuliang; Wu, Shiguo; Yao, Genshun; Ma, Yubo; Fu, Yanhui

    2009-05-01

    Based on more than 4000 km 2D seismic data and seismic stratigraphic analysis, we discussed the extent and formation mechanism of the Qiongdongnan deep sea channel. The Qiongdongnan deep sea channel is a large incised channel which extends from the east boundary of the Yinggehai Basin, through the whole Qiongdongnan and the Xisha trough, and terminates in the western part of the northwest subbasin of South China Sea. It is more than 570 km long and 4-8 km wide. The chaotic (or continuous) middle (or high) amplitude, middle (or high) continuity seismic facies of the channel reflect the different lithological distribution of the channel. The channel formed as a complex result of global sea level drop during early Pliocene, large scale of sediment supply to the Yinggehai Basin, inversion event of the Red River strike-slip fault, and tilted direction of the Qiongdongnan Basin. The large scale of sediment supply from Red River caused the shelf break of the Yinggehai Basin to move torwards the S and SE direction and developed large scale of prograding wedge from the Miocene, and the inversion of the Red River strike-slip fault induced the sediment slump which formed the Qiongdongnan deep sea channel.

  11. Initiation of Extension in South China Continental Margin during the Active-Passive Margin Transition: Thermochronological and Kinematic Constraints

    NASA Astrophysics Data System (ADS)

    Zuo, X.; Chan, L. S.

    2015-12-01

    The South China continental margin is characterized by a widespread magmatic belt, prominent NE-striking faults and numerous rifted basins filled by Cretaceous-Eocene sediments. The geology denotes a transition from active to passive margin, which led to rapid modifications of crustal stress configuration and reactivation of older faults in this area. Our zircon fission-track data in this region show two episodes of exhumation: The first episode, occurring during 170-120Ma, affected local parts of the Nanling Range. The second episode, a more regional exhumation event, occurred during 115-70Ma, including the Yunkai Terrane and the Nanling Range. Numerical geodynamic modeling was conducted to simulate the subduction between the paleo-Pacific plate and the South China Block. The modeling results could explain the fact that exhumation of the granite-dominant Nanling Range occurred earlier than that of the gneiss-dominant Yunkai Terrane. In addition to the difference in rock types, the heat from Jurassic-Early Cretaceous magmatism in Nanling may have softened the upper crust, causing the area to exhume more readily than Yunkai. Numerical modeling results also indicate that (1) high lithospheric geothermal gradient, high slab dip angle and low convergence velocity favor the reversal of crustal stress state from compression to extension in the upper continental plate; (2) late Mesozoic magmatism in South China was probably caused by a slab roll-back; and (3) crustal extension could have occurred prior to the cessation of plate subduction. The inversion of stress regime in the continental crust from compression to crustal extension imply that the Late Cretaceous-early Paleogene red-bed basins in South China could have formed during the late stage of the subduction, accounting for the occurrence of volcanic events in some sedimentary basins. We propose that the rifting started as early as Late Cretaceous, probably before the cessation of subduction process.

  12. Comparative structural reconstruction of the post-breakup succession in conjugated salt and salt-free basins offshore South-America and South-Africa

    NASA Astrophysics Data System (ADS)

    Strozyk, Frank; Back, Stefan; Kukla, Peter

    2013-04-01

    This project focuses on the post-breakup tectono-stratigraphic development of large offshore basins along the South American and African continental margins that record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. In this study we show a regional comparison between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin, etc). A sequential reconstruction of tectonic and stratigraphic elements of representative geological transects provides a comprehensive basin-to-basin documentation of the influence of key geological parameters controlling ocean and continental margin development. These include the subsidence development through time, sediment input, flux and storage patterns, salt vs. non-salt systems, carbonate-rich vs. clastics-dominated successions and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development.

  13. Substratum transverse faults in Kuqa Foreland Basin, northwest China and their significance in petroleum geology

    NASA Astrophysics Data System (ADS)

    Cai, Jun; Lü, Xiuxiang

    2015-08-01

    The importance of transverse faults in basin evolution and petroleum geology has been often emphasized. However, the transverse faults in the Kuqa Foreland Basin, the most important gas producing area in China, have rarely been studied. Interpreted seismic sections and earthquake focal mechanism solutions, as well as other geological and geophysical data, allow us to identify a few widely-spaced, approximately NS trending, transverse strike-slip faults separating major structural units, and to clarify the geometry and kinematics of these transverse faults hidden below thrust faults. In the Kuqa Foreland Basin, two major structural domains can be distinguished. Transverse faults in the northern Kuqa Foreland Basin are mainly NNE trending sinistral, indicating clockwise-rotation of fault-bounded blocks. In contrast, the predominant NW trending dextral faults in the southern Kuqa Foreland Basin imply counterclockwise-rotation of fault-bounded blocks. We propose a tectonic model in which crustal blocks are bounded by strike-slip faults in a zone of simple shear rotation about vertical axis. The strike-slip faulting and thrust faulting in the Kuqa Foreland Basin suggest that some of the convergence between South Tianshan and Tarim blocks may have been accommodated not only by obvious crustal shortening and thickening along thrust faults, but also by rotation and possible lateral movement of the crust along transverse faults. Controlled by the remote collision of Indian block with Eurasian block since the Miocene, these reactivated substratum faults, which may inherit from Paleozoic deformation, control various elements relevant to gas accumulation in the Kuqa Foreland Basin which should expect to be paid more attention in the future. These elements include maturity of Tertiary and Jurassic source rocks, a difference in the regional cap of Kumugelimu salt beds from east to west, reservoir bed properties, gas migration channels, and traps formation. In addition, the

  14. Spatiotemporal Assessment of Groundwater Resources in the South Platte Basin, Colorado

    NASA Astrophysics Data System (ADS)

    Ruybal, C. J.; McCray, J. E.; Hogue, T. S.

    2015-12-01

    The South Platte Basin is one of the most economically diverse and fastest growing basins in Colorado. Strong competition for water resources in an over-appropriated system brings challenges to meeting future water demands. Balancing the conjunctive use of surface water and groundwater from the South Platte alluvial aquifer and the Denver Basin aquifer system is critical for meeting future demands. Over the past decade, energy development in the basin has added to the competition for water resources, highlighting the need to advance our understanding of the availability and sustainability of groundwater resources. Current work includes evaluating groundwater storage changes and recharge regimes throughout the South Platte Basin under competing uses, e.g. agriculture, oil and gas, urban, recreational, and environmental. The Gravity Recovery and Climate Experiment satellites in conjunction with existing groundwater data is used to evaluate spatiotemporal variability in groundwater storage and identify areas of high water stress. Spatiotemporal data will also be utilized to develop a high resolution groundwater model of the region. Results will ultimately help stakeholders in the South Platte Basin better understand groundwater resource challenges and contribute to Colorado's strategic future water planning.

  15. Detecting changes in future precipitation extremes over eight river basins in China using RegCM4 downscaling

    NASA Astrophysics Data System (ADS)

    Qin, Peihua; Xie, Zhenghui

    2016-06-01

    To detect the frequency and intensity of precipitation extremes in China for the middle 21st century, simulations were conducted with the regional climate model RegCM4 forced by the global climate model GFDL_ESM2M under the middle emission scenario (RCP4.5). Compared with observed precipitation extremes for the reference period from 1982 to 2001, RegCM4 generally performed better in most river basins of China relative to GFDL. In the future period 2032-2051, more wet extremes will occur relative to the present period in most study areas, especially in southeast China while significantly less dry extremes will occur in arid and semiarid areas in northwest China. In contrast, areas in northwest China showed an increase in the trend of dry extremes (CDD) and a decrease in the trend of wet extremes (R95p and Rx5day), which might result in more drought in the future. Finally, we discuss in detail the possible reason of these processes, such as zonal wind, vertical wind, and water vapor. In the Huaihe river basin (HU), reduced south winds in summer (June-August) and a decrease of the upward vertical p velocity cause less future precipitation and might lead to changes of extreme events. We also completed correlation analysis between the precipitation extreme indices and the climate factors and found that the precipitation extremes were more sensitive to the annual and seasonal mean precipitation, total water vapor, and upward vertical wind relative to the geopotential height and 2 m temperature over most river basins in China. Perhaps the changes of some wet extremes could be verified partly through changes of annual precipitation due to their high consistence.

  16. Sample Return Mission to the South Pole Aitken Basin

    NASA Astrophysics Data System (ADS)

    Duke, M. B.; Clark, B. C.; Gamber, T.; Lucey, P. G.; Ryder, G.; Taylor, G. J.

    1999-01-01

    The South Pole Aitken Basin (SPA) is the largest and oldest observed feature on the Moon. Compositional and topographic data from Galileo, Clementine, and Lunar Prospector have demonstrated that SPA represents a distinctive major lunar terrane, which has not been sampled either by sample return missions (Apollo, Luna) or by lunar meteorites. The floor of SPA is characterized by mafic compositions enriched in Fe, Ti, and Th in comparison to its surroundings. This composition may represent melt rocks from the SPA event, which would be mixtures of the preexisting crust and mantle rocks. However, the Fe content is higher than expected, and the large Apollo basin, within SPA, exposes deeper material with lower iron content. Some of the Fe enrichment may represent mare and cryptomare deposits. No model adequately accounts for all of the characteristics of the SPA and disagreements are fundamental. Is mantle material exposed or contained as fragments in melt rock and breccias? If impact melt is present, did the vast sheet differentiate? Was the initial mantle and crust compositionally different from other regions of the Moon? Was the impact event somehow peculiar, (e.g., a low-velocity impact)? The precise time of formation of the SPA is unknown, being limited only by the initial differentiation of the Moon and the age of the Imbrium event, believed to be 3.9 b.y. The questions raised by the SPA can be addressed only with detailed sample analysis. Analysis of the melt rocks, fragments in breccias, and basalts of SPA can address several highly significant problems for the Moon and the history of the solar system. The time of formation of SPA, based on analysis of melt rocks formed in the event. would put limits on the period of intense bombardment of the Moon, which has been inferred by some to include a "terminal cataclysm." If close to 3.9 Ga, the presumed age of the Imbrium Basin, the SPA date would confirm the lunar cataclysm. This episode, if it occurred, would have

  17. Numerical simulation of rifting controlled by magmatic underplating in the South China Sea

    NASA Astrophysics Data System (ADS)

    Xu, Hehua

    2016-04-01

    South China Sea is one of the largest basins in the western Pacific marginal sea, which is located in the intersection area of the Eurasia, the India-Australian and the Pacific-Philippines plate. Although the duration of seafloor spreading and the extension mechanism are still controversial.It is widely accepted that the South China Sea was opened by seafloor spreading in the Cenozoic. From the point of its structural development history, South China Sea has its own unique development model, which is formed by the continent rifting and expansion, while the tectonic evolution has close relationship with geological peripheral units. According to the seismic detection and magnetic integrated geophysics, the studies found that high-speed lower crust layers are widespread in the northern South China Sea and the northeast of continental margin, these layers are mainly located in continental slopes and some high-degree tensional continental shelves. Researches suggested that materials of high-speed in lower crustal layers are formed by the bottom magmatic underplating rather than serpentinized mantle peridotite. These layers are formed in Cenozoic and has close relationship with extension. However, in most kinematic and dynamic models of rift formation and evolution, the effects of magmatism have been neglected. This study established a two-dimensional thermal - mechanical coupled finite element model to simulate the role of underplated magmatic bodies in the localization of deformation. We examine the response of the lithosphere to an applied constant boundary velocity at the edge of the model. The mamatic underplating is introduced as a material with an anomalous high temperture and a magic upper mantle composition. The mechanical problem is coupled with the thermal problem through temperature-dependent viscosity. Since extension of lithosphere and underlying mantle is associated with intense and simultaneous viscous and brittle/plastic(faulting) deformations, we use

  18. Sustainability of Water Resources in Arid Ecosystems: A View from Hei River Basin, China (Invited)

    NASA Astrophysics Data System (ADS)

    Zheng, C.; Cheng, G.; Xiao, H.; Ma, R.

    2009-12-01

    The northwest of China is characterized by an arid climate and fragile ecosystems. With irrigated agriculture, the region is a prolific producer of cotton, wheat, and maize with some of the highest output per acre in the country. The region is also rich in ore deposits, with the reserves of numerous minerals ranked at or near the top in the country. However, the sustainability of irrigated agriculture and economic development in the region is threaten by severe eco-environmental problems resulting from both global changes and human activities, such as desertification, salinization, groundwater depletion, and dust storms. All these problems are a direct consequence of water scarcity. As global warming accelerates and rapid economic growth continues, the water shortage crisis is expected to worsen. To improve the bleak outlook for the health of ecosystem and environment in northwest China, the Chinese government has invested heavily in ecosystem restoration and watershed management in recent years. However, the effectiveness of such measures and actions depends on scientific understanding of the complex interplays among ecological, hydrological and socioeconomic factors. This presentation is intended to provide an overview of a major new research initiative supported by the National Natural Science Foundation of China to study the integration of ecological principles, hydrological processes and socioeconomic considerations toward more sustainable exploitation of surface water and groundwater resources in the Hei River Basin in northwest China. The Hei River Basin is an inland watershed located at the center of the arid region in East Asia, stretching from Qilianshan Mountains in the south to the desert in the north bordering China’s Inner Mongolia Autonomous Region and Mongolia. The total area of Hei River Basin is approximately 130,000 km2. The research initiative builds on existing research infrastructure and ecohydrological data and seeks to reveal complex

  19. Changes in precipitation and temperature in Xiangjiang River Basin, China

    NASA Astrophysics Data System (ADS)

    Ma, Chong; Pan, Suli; Wang, Guoqing; Liao, Yufang; Xu, Yue-Ping

    2016-02-01

    Global warming brings a huge challenge to society and human being. Understanding historic and future potential climate change will be beneficial to regional crop, forest, and water management. This study aims to analyze the precipitation and temperature changes in the historic period and future period 2021-2050 in the Xiangjiang River Basin, China. The Mann-Kendall rank test for trend and change point analysis was used to analyze the changes in trend and magnitude based on historic precipitation and temperature time series. Four global climate models (GCMs) and a statistical downscaling approach, LARS-WG, were used to estimate future precipitation and temperature under RCP4.5. The results show that annual precipitation in the basin is increasing, although not significant, and will probably continue to increase in the future on the basis of ensemble projections of four GCMs. Temperature is increasing in a significant way and all GCMs projected continuous temperature increase in the future. There will be more extreme events in the future, including both extreme precipitation and temperature.

  20. New briaranes from the South China Sea gorgonian Junceella juncea.

    PubMed

    Qi, Shu-Hua; Zhang, Si; Huang, Hui; Xiao, Zhi-Hui; Huang, Jian-She; Li, Qing-Xin

    2004-11-01

    Three new briarane diterpenes, juncins O-Q (1-3), along with five known briaranes, praelolide, junceellin A, gemmacolide A, gemmacolide B, and junceellolide D, were isolated from the EtOH/CH(2)Cl(2) extracts of the South China Sea gorgonian coral Junceella juncea. The structures of 1-3 were established by extensive spectroscopic analysis, including 1D and 2D NMR data.

  1. 78 FR 65706 - Ferrovanadium From China and South Africa; Institution of Five-Year Reviews

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-01

    ... and South Africa (68 FR 4168 and 4169). Following the first five-year reviews by Commerce and the... imports of ferrovanadium from China and South Africa (73 FR 77609). The Commission is now conducting... COMMISSION Ferrovanadium From China and South Africa; Institution of Five- Year Reviews AGENCY: United...

  2. Kuroshio intrusion and the circulation in the South China Sea

    NASA Astrophysics Data System (ADS)

    Xue, Huijie; Chai, Fei; Pettigrew, Neal; Xu, Danya; Shi, Maochong; Xu, Jianping

    2004-02-01

    The Princeton Ocean Model is used to study the circulation in the South China Sea (SCS) and its seasonal transition. Kuroshio enters (leaves) the SCS through the southern (northern) portion of the Luzon Strait. The annually averaged net volume flux through the Luzon Strait is ˜2 Sv into the SCS with seasonal reversals. The inflow season is from May to January with the maximum intrusion of Kuroshio water reaching the western SCS during fall in compensation of summertime surface offshore transport associated with coastal upwelling. From February to April the net transport reverses from the SCS to the Pacific. The intruded Kuroshio often forms an anticyclonic current loop west of the Luzon Strait. The current loop separates near the Dongsha Islands with the northward branch continuously feeding the South China Sea Warm Current (SCSWC) near the shelf break and the westward branch becoming the South China Sea Branch of Kuroshio on the slope, which is most apparent in the fall. The SCSWC appears from December to February on the seaward side of the shelf break, flowing eastward against the prevailing wind. Diagnosis shows that the onshore Ekman transport due to northeasterly monsoon generates upwelling when moving upslope, and the particular distributions of the density and sea level associated with the cross shelf motion supports the SCSWC.

  3. Joint Interpretation of Magnetotelluric and Gravimetric Data from the South American Paraná Basin

    NASA Astrophysics Data System (ADS)

    Santos, E. B.; Santos, H. B.; Vitorello, I.; Pádua, M. B.

    2013-05-01

    The Paraná Basin is a large sedimentary basin in central-eastern South America that extends through Brazil, Paraguay, Uruguay and Argentina. Evolved completely over the South American continental crust, this Paleozoic basin is filled with sedimentary and volcanic rocks deposited from the Silurian to the Cretaceous, when a significant basaltic effusion covered almost the entire area of the basin. A series of superposed sedimentary and volcanic rock layers were laid down under the influence of different tectonic settings, probably originated from distant collisional dynamics of continental boards that led to the amalgamation of Gondwanaland. The current boundaries of the basin can be the result of issuing erosional or of tectonic origin, such as the building up of large arches and faults. To evaluate the deep structural architecture of the lithosphere under a sedimentary basin is a great challenge, requiring the integration of different geophysical and geological studies. In this paper, we present the resulting Paraná Basin lithospheric model, obtained from processing and inversion of broadband and long-period magnetotelluric soundings along an E-W profile across the central part of the basin, complemented by a qualitative joint interpretation of gravimetric data, in order to obtain a more precise geoelectric model of the deep structure of the region.

  4. Basin fill evolution and paleotectonic patterns along the Samfrau geosyncline: the Sauce Grande basin-Ventana foldbelt (Argentina) and Karoo basin-Cape foldbelt (South Africa) revisited

    NASA Astrophysics Data System (ADS)

    López-Gamundí, O. R.; Rossello, E. A.

    As integral parts of du Toit's (1927) ``Samfrau Geosyncline'', the Sauce Grande basin-Ventana foldbelt (Argentina) and Karoo basin-Cape foldbelt (South Africa) share similar paleoclimatic, paleogeographic, and paleotectonic aspects related to the Late Paleozoic tectono-magmatic activity along the Panthalassan continental margin of Gondwanaland. Late Carboniferou-earliest Permian glacial deposits were deposited in the Sauce Grande (Sauce Grande Formation) and Karoo (Dwyka Formation) basins and Falkland-Malvinas Islands (Lafonia Formation) during an initial (sag) phase of extension. The pre-breakup position of the Falkland (Malvinas) Islands on the easternmost part of the Karoo basin (immediately east of the coast of South Africa) is supported by recent paleomagnetic data, lithofacies associations, paleoice flow directions and age similarities between the Dwyka and the Lafonia glacial sequences. The desintegration of the Gondwanan Ice Sheet (GIS) triggered widespread transgressions, reflected in the stratigraphic record by the presence of inter-basinally correlatable, open marine, fine-grained deposits (Piedra Azul Formation in the Sauce Grande basin, Prince Albert Formation in the Karoo basin and Port Sussex Formation in the Falkland Islands) capping glacial marine sediments. These early postglacial transgressive deposits, characterised by fossils of the Eurydesma fauna and Glossopteris flora, represent the maximum flooding of the basins. Cratonward foreland subsidence was triggered by the San Rafael orogeny (ca. 270 Ma) in Argentina and propogated along the Gondwanan margin. This subsidence phase generated sufficient space to accommodate thick synorogenic sequences derived from the orogenic flanks of the Sauce Grande and Karoo basins. Compositionally, the initial extensional phase of these basins was characterized by quartz-rich, craton-derived detritus and was followed by a compressional (foreland) phase characterized by a paleocurrent reversal and dominance of

  5. Major unconformities/termination of extension events and associated surfaces in the South China Seas: Review and implications for tectonic development

    NASA Astrophysics Data System (ADS)

    Morley, C. K.

    2016-04-01

    The distribution of unconformities and end of Cenozoic rifting events in the South China Seas (SCS) reflects both the modes of rift development, and the effects of driving mechanisms. Continental rifting began in the eastern basins during the Paleocene, and propagated westwards to the Vietnam basin margin in the Late Eocene. Continental breakup around 32-28 Ma caused a regional reduction or cessation in extensional activity, particularly affecting basins furthest from the spreading centre. Basins in the slope and deepwater area north of the spreading centre exhibit reduced fault activity until 21-20 Ma. Propagation of oceanic crust westwards between ∼25 and 23 Ma, and termination of seafloor spreading sometime between 20.5 and 16 Ma affected fault activity in the Qiongdongnan, and Nam Con Song basins. In the Phu Khanh Basin and South, in the Dangerous Grounds area, extension continued until about 16 Ma, ending at the Red Unconformity. The end of seafloor spreading around 20.5 Ma reflects loss of extensional driving force as thinned continental crust entered the NW Borneo subduction zone. Controversially, a key component of the driving force maybe attributed to slab-pull. A transitional period of about 5-7 my between the onset of subduction of continental crust, and final jamming of the subduction zone (Deep Regional Unconformity, DRU) is inferred. The last pulse of extension was focussed in the western SCS, and terminated around 10.5 Ma. Detailed understanding of proto South China Seas development remains uncertain and controversial.

  6. Geomagnetic Polarity Reversal Model of Deeptow Magnetic Survey in the Southwest Subbasin of South China Sea Ridge

    NASA Astrophysics Data System (ADS)

    Qiu, N.; Sun, Z.; Lin, J.; Li, C. F.; Xu, X.

    2014-12-01

    South China Sea basin, which evolved from Cenozoic continental margin rifting and subsequent seafloor spreading, is a classic example of a marginal sea in Western Pacific. Since the early 1980's, several models have been proposed for the formation of this sea basin. The previous studies were based mainly on the distribution of magnetic anomaly lineation obtained from aerial and shipboard measurements. However, large water depth (over 4.5km) and thick sediment cover (up to 1km or more) make the magnetic anoamaly information not so well displayed in aerial and shipboard data. To better understand the evolution of the sea basin, we increased anomaly amplitudes by collecting magnetic data along deep-tow profiles over the magnetic lineations in the South China Sea oceanic area. The one across the southwest subsea basin was analyzed first. The total field magnetic measurements were processed through filtering, resampling, diurnal variation removal, continuation to a level datum, regional field correction, projection to a common azimuth, and deskewing. A magnetic polarity reversal timescale was constructed by matching deep-tow anomalies with a simple, rectangular block magnetization model with the expansion rate for oceanic crust. We analyzed the spreading duration, rate, asymmetry, and reversal events of Southwest subbasin, in reference to the recent GTS2012 geomagnetic polarity representative data and concluded that the Southwest subbasin opened from around 21.767 Ma and stopped around C5C at about 15.974Ma. The full spreading rate varied from 8 to 40 cm/yr. Spreading is usually asymmetric by showing alternate faster spreading rate in one slab than the other in different time periods. From the comparison, several small reversal were revealed in addition to the standard geomagnetic polarity. These findings helped to understand the evolution of the Southwest subbasin of South China Sea and will also help to establish new reversal discrimination.

  7. Beyond water, beyond boundaries: spaces of water management in the Krishna river basin, South India.

    PubMed

    Venot, Jean-Philippe; Bharati, Luna; Giordano, Mark; Molle, François

    2011-01-01

    As demand and competition for water resources increase, the river basin has become the primary unit for water management and planning. While appealing in principle, practical implementation of river basin management and allocation has often been problematic. This paper examines the case of the Krishna basin in South India. It highlights that conflicts over basin water are embedded in a broad reality of planning and development where multiple scales of decisionmaking and non-water issues are at play. While this defines the river basin as a disputed "space of dependence", the river basin has yet to acquire a social reality. It is not yet a "space of engagement" in and for which multiple actors take actions. This explains the endurance of an interstate dispute over the sharing of the Krishna waters and sets limits to what can be achieved through further basin water allocation and adjudication mechanisms – tribunals – that are too narrowly defined. There is a need to extend the domain of negotiation from that of a single river basin to multiple scales and to non-water sectors. Institutional arrangements for basin management need to internalise the political spaces of the Indian polity: the states and the panchayats. This re-scaling process is more likely to shape the river basin as a space of engagement in which partial agreements can be iteratively renegotiated, and constitute a promising alternative to the current interstate stalemate.

  8. Paleogeography of the upper Paleozoic basins of southern South America: An overview

    NASA Astrophysics Data System (ADS)

    Limarino, Carlos O.; Spalletti, Luis A.

    2006-12-01

    The paleogeographic evolution of Late Paleozoic basins located in southern South America is addressed. Three major types of basins are recognized: infracratonic or intraplate, arc-related, and retroarc. Intraplate basins (i.e., Paraná, Chaco-Paraná, Sauce Grande-Colorado, and La Golondrina) are floored by continental or quasi-continental crust, with low or moderate subsidence rates and limited magmatic and tectonic activity. Arc-related basins (northern and central Chile, Navidad-Arizaro, Río Blanco, and Calingasta-Uspallata basins and depocenters along Chilean Patagonia) show a very complex tectonic history, widespread magmatic activity, high subsidence rates, and in some cases metamorphism of Late Paleozoic sediments. An intermediate situation corresponds to the retroarc basins (eastern Madre de Dios, Tarija, Paganzo, and Tepuel-Genoa), which lack extensive magmatism and metamorphism but in which coeval tectonism and sedimentation rates were likely more important than those in the intraplate region. According to the stratigraphic distribution of Late Paleozoic sediments, regional-scale discontinuities, and sedimentation pattern changes, five major paleogeographic stages are proposed. The lowermost is restricted to the proto-Pacific and retroarc basins, corresponds to the Mississippian (stage 1), and is characterized by shallow marine and transitional siliciclastic sediments. During stage 2 (Early Pennsylvanian), glacial-postglacial sequences dominated the infracratonic (or intraplate) and retroarc basins, and terrigenous shallow marine sediments prevailed in arc-related basins. Stage 3 (Late Pennsylvanian-Early Cisuralian) shows the maximum extension of glacial-postglacial sediments in the Paraná and Sauce Grande-Colorado basins (intraplate region), whereas fluvial deposits interfingering with thin intervals of shallow marine sediments prevailed in the retroarc basins. To the west, arc-related basins were dominated by coastal to deep marine conditions

  9. The Effectiveness of Cattlemans Detention Basin, South Lake Tahoe, California

    USGS Publications Warehouse

    Green, Jena M.

    2006-01-01

    Lake Tahoe (Nevada-California) has been designated as an 'outstanding national water resource' by the U.S. Environmental Protection Agency, in part, for its exceptional clarity. Water clarity in Lake Tahoe, however, has been declining at a rate of about one foot per year for more than 35 years. To decrease the amount of sediment and nutrients delivered to the lake by way of alpine streams, wetlands and stormwater detention basins have been installed at several locations around the lake. Although an improvement in stormwater and snowmelt runoff quality has been measured, the effectiveness of the detention basins for increasing the clarity of Lake Tahoe needs further study. It is possible that poor ground-water quality conditions exist beneath the detention basins and adjacent wetlands and that the presence of the basins has altered ground-water flow paths to nearby streams. A hydrogeochemical and ground-water flow modeling study was done at Cattlemans detention basin, situated adjacent to Cold Creek, a tributary to Lake Tahoe, to determine whether the focusing of storm and snowmelt runoff into a confined area has (1) modified the ground-water flow system beneath the detention basin and affected transport of sediment and nutrients to nearby streams and (2) provided an increased source of solutes which has changed the distribution of nutrients and affected nutrient transport rates beneath the basin. Results of slug tests and ground-water flow modeling suggest that ground water flows unrestricted northwest across the detention basin through the meadow. The modeling also indicates that seasonal flow patterns and flow direction remain similar from year to year under transient conditions. Model results imply that about 34 percent (0.004 ft3/s) of the total ground water within the model area originates from the detention basin. Of the 0.004 ft3/s, about 45 percent discharges to Cold Creek within the modeled area downstream of the detention basin. The remaining 55 percent

  10. Seasonal variation of black carbon over the South China Sea and in various continental locations in South China

    NASA Astrophysics Data System (ADS)

    Wu, D.; Wu, C.; Liao, B.; Li, F.; Tan, H.; Deng, T.; Li, H.; Chen, H.; Jiang, D.; Yu, J. Z.

    2013-07-01

    Black carbon (BC) is an important atmospheric constitute as an air pollutant and as a climate forcer. To our knowledge, field measurements of BC have not been reported over the South China Sea. Observation of light absorption coefficients (σabs) and BC concentrations by Aethalometer were conducted on Yongxing Island in the South China Sea and at five continental sites in the Pearl River Delta (PRD) region, South China during the South China Sea monsoon period (rainy season, 16 May-20 June 2008) and the northeast monsoon period (dry season, 12 December 2008-8 January 2009). At the oceanic site, the daily average BC concentrations vary from 0.28 to 2.14 μg m-3 and seasonal variations of BC were small (0.67 in dry season and 0.54 μg m-3 in rainy season). Similarly, little seasonal difference was found at a background site in PRD (2.88 in dry season and 2.62 μg m-3 in rainy season). At PRD urban sites, the daily average concentration of BC ranges from 1.56 to 37.9 μg m-3, higher in the dry season (12.6 μg m-3) and lower in the rainy season (6.4 μg m-3). The observed average σabs values in rainy vs. dry seasons are 119 vs. 62 Mm-1 at the PRD urban sites, 29 vs. 26 Mm-1 at the PRD background site, and 8.4 vs. 7.2 Mm-1 at the marine site. A bi-peak pattern in diurnal BC variation was observed at all sites while this pattern is the most prominent at the urban sites. The first peak appears in the early morning rush hour and the second peak in early evening, with the evening peak more pronounced in dry season.

  11. An integrated multiscale river basin observing system in the Heihe River Basin, northwest China

    NASA Astrophysics Data System (ADS)

    Li, X.; Liu, S.; Xiao, Q.; Ma, M.; Jin, R.; Che, T.

    2015-12-01

    Using the watershed as the unit to establish an integrated watershed observing system has been an important trend in integrated eco-hydrologic studies in the past ten years. Thus far, a relatively comprehensive watershed observing system has been established in the Heihe River Basin, northwest China. In addition, two comprehensive remote sensing hydrology experiments have been conducted sequentially in the Heihe River Basin, including the Watershed Allied Telemetry Experimental Research (WATER) (2007-2010) and the Heihe Watershed Allied Telemetry Experimental Research (HiWATER) (2012-2015). Among these two experiments, an important result of WATER has been the generation of some multi-scale, high-quality comprehensive datasets, which have greatly supported the development, improvement and validation of a series of ecological, hydrological and quantitative remote-sensing models. The goal of a breakthrough for solving the "data bottleneck" problem has been achieved. HiWATER was initiated in 2012. This project has established a world-class hydrological and meteorological observation network, a flux measurement matrix and an eco-hydrological wireless sensor network. A set of super high-resolution airborne remote-sensing data has also been obtained. In addition, there has been important progress with regard to the scaling research. Furthermore, the automatic acquisition, transmission, quality control and remote control of the observational data has been realized through the use of wireless sensor network technology. The observation and information systems have been highly integrated, which will provide a solid foundation for establishing a research platform that integrates observation, data management, model simulation, scenario analysis and decision-making support to foster 21st-century watershed science in China.

  12. Potential sample sites for South Pole-Aitken basin impact melt within the Schrödinger basin

    NASA Astrophysics Data System (ADS)

    Hurwitz, Debra; Kring, David A.

    2015-10-01

    Determining the age of the South Pole-Aitken (SPA) basin ranks among the highest priorities in lunar science. This datum would constrain the timing of the oldest and largest basin-forming event on the Moon, information that is essential to any evaluation of the collisional evolution of the early Solar System. To locate material that preserves the age of SPA, a geochemical model of SPA impact melt is integrated with chemical and mineralogical analyses of the lunar surface determined from orbit. Results suggest the southern wall of Schrödinger basin contains material with the mineralogical and geochemical signatures of SPA melt and, thus, represents a candidate destination for sampling material that can constrain the age of the SPA impact.

  13. Structure and Evolution of Northwest Corner of South China Sea: implications for Cenozoic tectonics in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Lei, C.; Ren, J.; Willett, S.; Clift, P. D.

    2012-12-01

    The Yinggehai-Song Hong Basin (YGHB) and Qiongdongnan Basin (QDNB) are in the northwest corner of the South China Sea, which positioned at a juncture between a strike-slipping zone and an extensional zone. The basins lie at the southern termination of the largest Tibetan strike-slip zones, the Red River Fault, and are the principal repository of materials eroded from the Red River drainage. The basins are flanked to the East by an oceanic ridge and border the Nansha area to the South, which is being subducted underneath the Borneo Block. Hainan Island, located between the YGHB and QGNB, is composed primarily of granites and basalts. A combination of regional, high-quality reflection seismic and well data was used to unravel the basin history in greater detail than previously possible, which will enrich our knowledge about structure and evolution in Southeast Asia. After ca. 55 Ma the basins started to subside and grabens bounded by small-scale and NE-SW trending faults developed across wide areas. However, the evolution of YGHB and QDNB was shown different after 32 Ma. Strike-slip deformation of the YGHB took place after 32 Ma in response to the left-lateral movement of the Red River Fault. After the Middle Miocene the YGHB was inverted and generated prominent folds in the Lingao Uplift and Hanoi Basin. Inversion ceased at different times in different parts of the basin, indicating that the transition from compression to extension moved northward during the period 15.5-5.5 Ma. In contrast, to the west of YGHB, the QDNB displays a very different basin structure and evolution since 32 Ma. Larger-scale, partly fault-controlled depressions are superimposed clearly over underlying, faulted-bounding grabens on seismic profiles. The evolution of QDNB was controlled by extension, which is strongly influenced by the initiation of ridge spreading in the South China Sea. We also reconstructed the sedimentary flux from the Red River drainage constrained by higher resolution

  14. Assessment of Paleozoic shale gas resources in the Sichuan Basin of China, 2015

    USGS Publications Warehouse

    Potter, Christopher J.; Schenk, Christopher J.; Charpentier, Ronald R.; Gaswirth, Stephanie B.; Klett, Timothy R.; Leathers, Heidi M.; Brownfield, Michael E.; Mercier, Tracey J.; Tennyson, Marilyn E.; Pitman, Janet K.

    2015-10-14

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 23.9 trillion cubic feet of technically recoverable shale gas resources in Paleozoic formations in the Sichuan Basin of China.

  15. Assessment of Paleozoic shale gas resources in the Sichuan Basin of China, 2015

    USGS Publications Warehouse

    Potter, Christopher J.; Schenk, Christopher J.; Charpentier, Ronald R.; Gaswirth, Stephanie B.; Klett, Timothy R.; Leathers, Heidi M.; Brownfield, Michael E.; Mercier, Tracey J.; Tennyson, Marilyn E.; Pitman, Janet K.

    2015-01-01

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 23.9 trillion cubic feet of technically recoverable shale gas resources in Paleozoic formations in the Sichuan Basin of China.

  16. Mesozoic-Cenozoic basins of Western China as example of partitioned retro-arc foreland basin system

    SciTech Connect

    Graham, S.A.; Zuchang, X.; Carroll, A.; McKnight, C.

    1988-01-01

    Mesozoic-Cenozoic sedimentary basins of Xinjiang Autonomous Region, western China, occupy a retro-arc foreland position with respect to the southern Eurasian convergent continental margin. Yet these basins differ in many ways from retro-arc foreland basins in other parts of the world. In North America, for instance, the Cretaceous Rocky Mountain foreland basin overlies basement that has been an integral part of cratonal North America since the Precambrian. The region had a long early Paleozoic history as a divergent continental margin and was later modified by relatively modest continental growth through accretionary tectonics. Once established in the Mesozoic, the Rocky Mountain foreland basin was a structurally simple, large, integrated basin, with the exception of the Laramide time-space segment of the foreland system. In contrast, the Mesozoic-Cenozoic foreland basins of Xinjiang are markedly partitioned, reflecting the process and architecture of major tectonic accretion from the Paleozoic through the collision of India in the Tertiary. The stage was set for a partitioned Mesozoic foreland with the Paleozoic suturing of the Siberia and Tarim cratons and intervening terranes. Although the margins of these blocks were deformed and uplifted during collision, their interiors persisted as depocenters into the foreland basin phase during the Mesozoic. The foreland basins of western China apparently represent poorly documented end members in the spectrum of retro-arc foreland basins. The Chinese examples occur in a region characterized by extreme continental growth through tectonic accretion. Reactivation of structural trends inherited from pre-foreland history were key factors in segmentation of the foreland.

  17. No Red River capture since the late Oligocene: Geochemical evidence from the Northwestern South China Sea

    NASA Astrophysics Data System (ADS)

    Zhao, Meng; Shao, Lei; Liang, Jianshe; Li, Qianyu

    2015-12-01

    Rare earth elements (REE) in the sediment samples of six industrial wells from the Yinggehai-Song Hong Basin in the Northwestern South China Sea were analyzed and compared with the detrital zircon U-Pb data from earlier studies to extrapolate sediment provenance. The results reveal that the Red River (Song Hong River), Hainan Island and Central Vietnam have been the main provenances of the Yinggehai-Song Hong Basin since the late Oligocene. The Red River has been supplying sediments with positive Eu anomalies from basic-ultrabasic metamorphic and volcanic parent rocks to most parts of the basin, while Hainan Island has delivered sediments with negative Eu anomalies from granitic and sedimentary parent rocks to the eastern slope area of the basin. The progradational downlap structures in the seismic profiles also support the finding that the sediment supply is mainly from the Red River and from Hainan Island. The metamorphic rocks, which are widespread within the Red River drainage, not only provided high volumes of sediments to the basin but also contributed to the positive Eu anomalies observed. Because their REE and U-Pb signatures are similar to those of the Red River source, the metamorphic and igneous rocks of the Song Ma Suture Zone, Kontum Massif, and Jinghong area were probably parts of a large basic provenance region before being separated by strike-slip movements along the Ailao Shan-Red River shear zone. Furthermore, our results indicate that the Red River drainage area has been relatively stable since the late Oligocene. Therefore, if a drainage capture from the Red River occurred, it is likely to have taken place before the late Oligocene.

  18. A New System of Marginal Arc in the North of the South China Sea of Today

    NASA Astrophysics Data System (ADS)

    Fang, N.; Dong, H.; Zhao, H.; Liu, H.; Shen, P.; Liang, X.

    2014-12-01

    SubFac, and (5) the Cretaceous volcano-sedimentary sequences representing back-arc rifting and outcropping in the Nanxiong and Hengyang basins, South China. The above pattern portrays an active margin characterized by subducting northward to the Asian land and disappearing at the end of the Mesozoic, which should be a part of the Tethyan archipelago.

  19. Inter-annual sea level variability in the southern South China Sea

    NASA Astrophysics Data System (ADS)

    Soumya, M.; Vethamony, P.; Tkalich, P.

    2015-10-01

    The South China Sea (SCS) is the largest marginal sea in the western Pacific Basin. Sea level anomalies (SLAs) in the southern South China Sea (SSCS) are assumed to be governed by various phenomena associated with the adjacent parts of the Indian Ocean and the Pacific Ocean. We have used monthly sea level anomalies obtained from 12 tide gauge stations of PSMSL and UHSLC and merged and gridded AVISO products of SLAs (sea level anomalies) derived from satellite altimeter. We find that IOD-influenced inter-annual variations are found only in the southwestern and southeastern coastal regions of SSCS. Our analysis reveals that inter-annual regional sea level drops are associated with positive phase of the IOD, and the rises with negative phase of the IOD. SLA variations at decadal scale in the southeastern and northern Gulf of Thailand correlate with Pacific Decadal Oscillations (PDO). Multiple linear regression analysis of inter-annual SLAs and climate indices shows that IOD induced inter-annual variations dominate in the southwestern SCS and it contributes to about ~ 40% of inter-annual sea level variation. Meanwhile, ENSO contributes to around ~ 30% variation in sea level in the southwestern and ~ 40% variation in the southeastern SSCS. The present study also suggests that inter-annual SLA variations in the SSCS can occur by ENSO and IOD induced changes in wind stress curl and volume transport variations.

  20. Tectonics, basin analysis and organic geochemical attributes of Permian through Mesozoic deposits and their derivative oils of the Turpan-Hami basin, northwestern China

    NASA Astrophysics Data System (ADS)

    Greene, Todd Jeremy

    The Turpan-Hami basin is a major physiographic and geologic feature of northwest China, yet considerable uncertainty exists as to the timing of its inception, its late Paleozoic and Mesozoic tectonic history, and the relationship of its petroleum systems to those of the nearby Junggar basin. Mesozoic sedimentary fades, regional unconformities, sediment dispersal patterns, and sediment compositions within the Turpan-Hami and southern Junggar basins suggest that these basins were initially separated between Early Triassic and Early Jurassic time. Prior to separation, Upper Permian profundal lacustrine and fan-delta fades and Triassic coarse-grained braided-fluvial/alluvial fades were deposited across a contiguous Junggar-Turpan-Hami basin. Permian through Triassic fades were derived mainly from the Tian Shan to the south as indicated by northward-directed paleocurrent directions and geochemical provenance of granitoid cobbles. Lower through Middle Jurassic strata begin to reflect ponded coal-forming, lake-plain environments within the Turpan-Hami basin. A sharp change in sedimentary-lithic-rich Lower Jurassic sandstone followed by a return to lithic volcanic-rich Middle Jurassic sandstone points to the initial uplift and unroofing of the largely andesitic Bogda Shan range, which first shed its sedimentary cover as it emerged to become the partition between the Turpan-Hami and southern Junggar basins. In Turpan-Hami, source rock age is one of three major statistically significant discriminators of effective source rocks in the basin. A newly developed biomarker parameter appears to track conifer evolution and can distinguish Permian rocks and their correlative oils from Jurassic coals and mudrocks, and their derivative oils. Source fades is a second key control on petroleum occurrence and character. By erecting rock-to-oil correlation models, the biomarker parameters separate oil families into end-member groups: Group 1 oils---Lower/Middle Jurassic peatland

  1. Temperature-Related Yield Constraints of Early-Rice in South China: A Cross-Location Analysis

    PubMed Central

    Xie, Xiaobing; Zhou, Xuefeng; Cao, Fangbo; Zou, Yingbin

    2016-01-01

    Warm temperature during post-heading is generally hypothesized to be the critical factor limiting grain yield of early-rice in South China. However, there is no direct evidence to confirm this hypothesis in the field. This study was conducted to determine the temperature-related yield constraints of early-rice in South China. Field experiments were carried out in Huaiji (a location in South China) and Changsha (a location in the Yangtze River basin) in 2011–2013. In each year, two rice cultivars were grown in early-rice growing season in Huaiji and in single-rice growing season in Changsha. Huaiji had higher average daily maximum temperature during post-heading than Changsha. The higher temperature during post-heading induced early plant senescence (slower crop growth rate and shorter grain filling duration), but grain weight did not reduce because it was compensated for by increased translocation of pre-heading biomass. The higher temperature during post-heading also did not cause a reduction in grain filling percentage. Huaiji had lower temperature during pre-heading than Changsha, which to some extent resulted in slower crop growth rate and consequently lower biomass production and smaller sink size in Huaiji than in Changsha. As a result, grain yield was about 30% lower in Huaiji than in Changsha. Our results indicate that grain yield of early-rice in South China is limited not by warm temperature during post-heading but partially by cool temperature during pre-heading, and suggest that enhancing sink size and meanwhile maintaining good translocation of pre-heading biomass may be an effective way to achieve high yield for early-rice in South China. PMID:27366908

  2. Sedimentary basins on the connugate margins of South America and Africa

    SciTech Connect

    Moore, G.T. )

    1990-05-01

    An Early Cretaceous spreading system formed the South Atlantic by separating South America from Africa along two subparallel major transform fault systems. The distribution of major sedimentary depocenters is controlled by the complex interplay of two factors: the late Mesozoic-Cenozoic cycle of sea-floor spreading and the legacy of a Precambrian collage of ancient cores that comprised western Gondwana. Three spreading modes created this configuration: rift, transform, and subduction. Each produces a different geometry and tectonic framework for the accumulation of sediment. Rifted margins (60%) contain basins that are elongate, form with their depocenter axes inboard of the ocean-continent transition, and rest on a tectonically complex, foundered basement. Transform margins have abrupt ocean-continent transitions. Such margins (30%) may be sediment starved or contain a thick sedimentary section controlled by the volcanic ridges of transform faults. Off Tierra del Fuego, Burdwood Bank is bounded on the north by a fossil (aseismic) subduction zone. The associated basin is an elongate, deformed accretionary prism of sediments on a gently dipping, faulted oceanic plate. The South Atlantic margins are divisible into 68 basins or segments that collectively contain over 33 {times} 106 km{sup 3} of syn- and postbreakup sediments. The South American margin contains 22 {times} 10{sup 6} km{sup 3} in 46 basins, and the African margin, 11 {times} 10{sup 6} km{sup 3} in 22 basins. Over 65% of the basins have a sediment column greater than 5 km with some depocenters that locally exceed 10 km. The source rock quality and character vary along both margins. The top of the oil generation window averages about 3.3 km; however, due to differing thermal histories, individual basins can depart significantly from this average.

  3. A basin on an unstable ground: Correlation of the Middle Archaean Moodies Basin, Barberton Greenstone Belt, South Africa

    NASA Astrophysics Data System (ADS)

    Ohnemueller, Frank; Heubeck, Christoph; Kirstein, Jens; Gamper, Antonia

    2010-05-01

    The 3.22 Ga-old Moodies Group, representing the uppermost part of the Barberton Supergroup of the Barberton Greenstone Belt (BGB), is the oldest well-exposed, relatively unmetamorphosed, quartz-rich sedimentary unit on Earth. Moodies facies (north of the Inyoka Fault) were thought to be largely of alluvial, fluvial, deltaic or shallow-marine origin (Anhaeusser, 1976; Eriksson, 1980; Heubeck and Lowe, 1994) and in its upper part syndeformational. However, units can only locally be correlated, and the understanding of the interplay between Moodies sedimentation and deformation is thus limited. We mapped and measured Moodies units in the northern BGB. They partly consist of extensive turbiditic deepwater deposits, including graded bedding, flame structures, and slumped beds, interbedded with jaspilites. These contrast with shallow-water environments, south-facing progressive unconformities and overlying alluvial-fan conglomerates along the northern margin of the Saddleback Syncline further south. The palaeogeographic setting in which late BGB deformation was initiated therefore appears complex and cannot be readily explained by a simple southward-directed shortening event. In order to constrain Moodies basin setting before and during late-Moodies basin collapse, we correlated ~15 measured sections in the northern and central BGB. Most units below the Moodies Lava (MdL, ca. 3230.6+-6 Ma) can be correlated throughout although facies variations are apparent. Above the Moodies Lava, coarse-grained units can only be correlated through the Eureka Syncline and the Moodies Hills Block but not with the Saddleback Syncline. Fine-grained and jaspilitic units can be correlated throughout the northern BGB. Moodies below-wavebase deposition occurred largely north of the Saddleback Fault. The observations are consistent with a pronounced basin compartmentalization event following the eruption of the MdL which appeared to have blanketed most of the Moodies basin(s) in middle Moodies

  4. A fall land bird migration across the South China Sea from Indo-China to the Greater Sunda Islands

    USGS Publications Warehouse

    Ellis, D.H.; Kepler, A.K.; Kepler, C.B.

    1994-01-01

    We encountered 150 land birds representing 14 families along the cruise track of the Soviet Oceanographic Research Vessel AKADEMlK KOROLEV in the South China Sea. We saw most of these birds during a 3 -day period in a small area c. 350 km southeast of the southern tip of the Indo-China peninsula. These observations suggest that a significant land bird migration corridor crosses the South China Sea from Viet Nam to Borneo.

  5. Deepwater circulation variation in the South China Sea since the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Zheng, Xufeng; Kao, ShuhJi; Chen, Zhong; Menviel, Laurie; Chen, Han; Du, Yan; Wan, Shiming; Yan, Hong; Liu, Zhonghui; Zheng, Liwei; Wang, Shuhong; Li, Dawei; Zhang, Xu

    2016-08-01

    Deepwater circulation plays a central role in global climate. Compared with the Atlantic, the Pacific deepwater circulation's history remains unclear. The Luzon overflow, a branch of the North Pacific deep water, determines the ventilation rate of the South China Sea (SCS) basin. Sedimentary magnetic properties in the SCS reflect millennial-scale fluctuations in deep current intensity and orientation. The data suggest a slightly stronger current at the Last Glacial Maximum compared to the Holocene. But, the most striking increase in deep current occurred during Heinrich stadial 1 (H1) and to a lesser extent during the Younger Dryas (YD). Results of a transient deglacial experiment suggest that the northeastern current strengthening at the entrance of the SCS during H1 and the YD, times of weak North Atlantic Deep Water formation, could be linked to enhanced formation of North Pacific Deep Water.

  6. [Aluminum mobilization models of forest yellow earth in South China].

    PubMed

    Xin, Yan; Zhao, Yu; Duan, Lei

    2009-07-15

    For the application of acidification models in predicting effects of acid deposition and formulating control strategy in China, it is important selecting regionally applicable models of soil aluminum mobilization and determining their parameters. Based on the long-term monitoring results of soil water chemistry from four forested watersheds in South China, the applicability of a range of equilibriums describing aluminum mobilization was evaluated. The tested equilibriums included those for gibbsite, jurbanite, kaolinite, imogolite, and SOM-Al: Results show that the gibbsite equilibrium commonly used in several acidification models is not suitable for the typical forest soil in South China, while the modified empirical gibbsite equation is applicable with pK = - 2.40, a = 1.65 (for upper layer) and pK = - 2.82, a = 1.66 (for lower layers) at only pH > or = 4. Comparing with the empirical gibbsite equation, the other equilibriums do not perform better. It can also be seen that pAl varies slightly with pH decreases at pH < 4, which is unexplainable by any of these suggested equilibriums.

  7. [Aluminum mobilization models of forest yellow earth in South China].

    PubMed

    Xin, Yan; Zhao, Yu; Duan, Lei

    2009-07-15

    For the application of acidification models in predicting effects of acid deposition and formulating control strategy in China, it is important selecting regionally applicable models of soil aluminum mobilization and determining their parameters. Based on the long-term monitoring results of soil water chemistry from four forested watersheds in South China, the applicability of a range of equilibriums describing aluminum mobilization was evaluated. The tested equilibriums included those for gibbsite, jurbanite, kaolinite, imogolite, and SOM-Al: Results show that the gibbsite equilibrium commonly used in several acidification models is not suitable for the typical forest soil in South China, while the modified empirical gibbsite equation is applicable with pK = - 2.40, a = 1.65 (for upper layer) and pK = - 2.82, a = 1.66 (for lower layers) at only pH > or = 4. Comparing with the empirical gibbsite equation, the other equilibriums do not perform better. It can also be seen that pAl varies slightly with pH decreases at pH < 4, which is unexplainable by any of these suggested equilibriums. PMID:19775005

  8. A potential submarine landslide tsunami in South China Sea

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Zhang, Y.; Switzer, A. D.

    2010-12-01

    Submarine earthquakes and submarine landslides are two main sources of tsunamis. Tsunami hazard modeling in the South China Sea has been primarily concerned with the potential large submarine earthquakes in the Manila trench. In contrast, evaluating the regional risk posed by tsunamis generated from submarine landslide is a new endeavor. At offshore south central Vietnam, bathymetric and seismic surveys show evidence of potentially tsunamigenic submarine landslides although their ages remain uncertain. We model two hypothetical submarine landslide events at a potential site on the heavily sediment laden, seismically active, steep continental slope offshore southeast Vietnam. Water level rises along the coast of Vietnam are presented for the potential scenarios, which indicate that the southeast coastal areas of Vietnam are at considerable risk of tsunami generated offshore submarine landslides. Key references: Kusnowidjaja Megawati, Felicia Shaw, Kerry Sieh, Zhenhua Huang, Tso-Ren Wu, Y. Lin, Soon Keat Tan and Tso-Chien Pan.(2009). Tsunami hazard from the subduction megathrust of the South China Sea, Part I, Source characterization and the resulting tsunami, Journal of Asian Earth Sciences, Vol. 36(1), pp. 13-20. Enet, F., Grilli, S.T. and Watts, P. (2003). Laboratory experiments for tsunami generated by underwater landslides: comparison with numerical modeling, In: Proceedings of 13th International Conference on Offshore and Polar Engineering, Honolulu, Hawaii, USA, pp. 372-379.

  9. Late Jurassic to Early Cretaceous sedimentary-tectonic development in the Chengde Basin, Yanshan fold-thrust belt, North China Craton

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Zhao, Yue; Liu, Ankun; Ye, Hao

    2015-12-01

    The Chengde Basin is located in the central part of the Yanshan fold-thrust belt in the northern North China Craton. The sediments in the Upper Jurassic to Lower Cretaceous Tuchengzi Formation in the Chengde Basin provide a detrital record of basin dynamics and uplift of the basin margins during that time. We analyzed the sedimentary facies, paleocurrents, and provenance of the Tuchengzi Formation in the Chengde Basin for the period of the Late Jurassic and Early Cretaceous shortening in the Yanshan fold-thrust belt. Four sedimentary facies associations have been identified in the Tuchengzi Formation, corresponding to proximal fan, mid-fan, distal alluvial fan, and fluvial facies. The transport and distribution of the Upper Jurassic to Lower Cretaceous sediments in the Chengde Basin was controlled by the faults bounding the basin. Paleocurrent indicators and provenance data of conglomerate clasts reveal that the sediments of the Tuchengzi Formation in the northern part of the Chengde Basin were delivered from source regions to the north of the basin. The early sediments of the Tuchengzi Formation in the southern part of the basin comprise a suite of fluvial deposits, similar to the fluvial sediments in the northern part of the basin, and their paleocurrent data and the compositions of conglomerate clasts also suggest a northern source. However, the subsequent sedimentation in the Tuchengzi Formation in the southern part of the basin changed markedly to proximal fan facies, with sediments being derived from the south of the basin, according to the paleocurrent data and conglomerate clast lithology. The Sandaohe sheet, which is located in the southeast limb of the Chengde syncline, is not a klippe formed as a result of long-distance northward thrusting, but an autochthonous pop-up tectonic wedge generated by N-S shortening during the Early Cretaceous sedimentation of the Tuchengzi Formation. The sedimentation ended before the onset of the Early Cretaceous volcanic

  10. Preliminary Paleomagnetic Results of Cores Collected during IODP Expedition 349 South China Sea Tectonics

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Liu, Q.

    2014-12-01

    International Ocean Discovery Program (IODP) Expedition 349 investigated the tectonic and oceanographic evolution of the South China Sea (SCS). The SCS is a marginal sea of the western Pacific and has undergone a near complete Wilson cycle from continental breakup to seafloor spreading to subduction along the Manila Trench. Two of the primary objectives of Expedition 349 are to determine the initiation and termination age of seafloor spreading through direct sampling of oceanic crust and to elucidate the cause of differences in seafloor magnetic anomalies between the East and Southwest Subbains. Expedition 349 drilled five sites in the deep basin of the SCS. Sites U1431, U1433, and U1434 recovered oceanic basement and overlying sediments near fossil spreading centers, and Sites U1432 and U1435 recovered materials near or at the northern continent/ocean boundary. Preliminary paleomagnetic results show that sediments and basement rocks from the sites drilled by Expedition 349 contain both reversely and normally magnetized samples. Our paleomagnetic study involves detailed alternating field and thermal demagnetization analysis of discrete samples. Stable characteristic remanent magnetization (ChRM) components are observed throughout the studied cores, following removal of a low stability drilling-induced remanence. Inclination values of ChRM are moderate downward or upward, consistent with the expected inclination for the sites. In order to examine the origin of the ChRM, supportive rock magnetic experiments on the same samples used for magnetostratigraphy of the drill sites were also conducted. Preliminary shipboard interpretations of biostratigraphic data from these sites indicate that the fossils needed to anchor the magnetostratigraphy are available. Preliminary magnetostratigraphy for Expedition 349 sites should help to refine the ages of sedimentation events and tectonic activities within and beyond the South China Sea basin.

  11. Crustal Rheology and Rifted Margin Architecture: Comparing Iberia-Newfoundland, Central South Atlantic, and South China Sea

    NASA Astrophysics Data System (ADS)

    Brune, Sascha

    2015-04-01

    migration of the rift centre, which generates sequential fault activity within the brittle crust. Rift migration results from two processes: (i) Strain hardening takes place in the rift centre due to cooling of upwelling mantle material. (ii) The formation of a low viscosity crustal pocket adjacent to the rift centre is caused by heat transfer from the mantle and viscous strain softening of the lower crust. These mechanisms generate a lateral strength contrast that promotes rift migration in a steady-state manner forming a wide sliver of hyper-extended crust on one margins side, while the conjugate margin becomes narrow. In contrast to these Atlantic examples where wide margins are formed diachronously, the South China Sea evolved in wide rift mode. Here, several hundred kilometres of highly attenuated continental crust are deformed simultaneously during ~40 My of extension. Numerical modelling suggests that the presence of weak, ductile crust enabled the formation of two wide and symmetric margins. Independent indicators for a weak crust come from super-deep basins on the northern margin. These basins appear to be created after the end of active extension and with a significant deficit in brittle faulting, which suggests that subsidence was controlled by sediment loading and accommodated by lower crustal flow, a style of basin formation that is only possible in the presence of low crustal viscosity.

  12. South Pole-Aitken Basin: Evidence for Post-Basin Resurfacing from Lunar Orbiter Laser Altimeter (LOLA) Data

    NASA Astrophysics Data System (ADS)

    Head, J. W.; Fassett, C.; Kadish, S.; Smith, D. E.; Zuber, M. T.; Neumann, G. A.; Mazarico, E.

    2010-12-01

    The lunar farside South Pole-Aitken Basin is the largest and oldest documented basin on the Moon and is thus of interest from the point of view of the scale of production of impact melt at large basin-event sizes and its ring structure and potential depth of sampling at such a large diameter. We used new LOLA data from the Lunar Reconnaissance Orbiter 1) to characterize the basin interior topography, 2) to assess the nature of the nearby and relatively pristine Orientale basin and compare it to the SPA interior, and 3) to compile a new global crater database of all lunar craters ≥20 km in diameter and to assess the population of impact craters superposed on the SPA interior and exterior. We find that impact crater size-frequency distribution plots show that the exterior of the SPA basin is similar to the most heavily cratered regions of the Moon, but that the interior of the basin has a deficiency of craters in the 20-64 km diameter crater range. One interpretation of these data is that some resurfacing process (or processes) has modified the superposed crater population. Among the candidates are 1) impact crater proximity weathering/degradation by adjacent (e.g., Apollo) and nearby (e.g., Orientale) impact basin ejecta, 2) volcanic resurfacing by early non-mare volcanism, cryptomaria and/or maria, and 3) viscous relaxation removing crater topography. We consider viscous relaxation of crater topography to be the least likely due to the wavelength dependence of the process (rim-crests should be preserved and thus detected in our crater counts). Careful analysis of the impact ejecta thickness radial decay suggests that it is an important resurfacing mechanism within a basin radius from the rim crest, but is unlikely to be sufficient to explain the observed deficiency. Morphometric analysis of impact craters, modeling, and simulations of volcanic flooding suggest that the deficiency may be related to the patchy distribution of cryptomaria, suspected from mineralogic

  13. Application of Basin Morphometry Laws in catchments of the south-western quadrangle of south-eastern Nigeria

    NASA Astrophysics Data System (ADS)

    Aisuebeogun, A. O.; Ezekwe, I. C.

    2013-09-01

    The relationship between process and form has been at the core of research in fluvial geomorphology. Form-process relationships of a natural river basin are strongly influenced by its hydrologic and sedimentologic processes as basin morphometric properties of length, shape, and relief, change in response to various hydrologic stimuli from the environment, but usually in line with well established laws. In the four river basins (Orashi, Otamiri, Sombreiro, New Calabar) examined in this study, however, empirical evidence does not conform neatly with theoretical postulates. Remarkable variations are noted in the morphometric properties of the catchments, when compared with established morphometric laws. The most varied in conformity are the Orashi and New Calabar basins, although the Sombreiro and Otamiri catchments also show some level of variation. Prime explanation for the morphometric and topographic non-conformity is caused by the nature of surficial material and the profoundly shallow relief of much of the study area, especially the alluvial flood and deltaic plains to the south and south-west of the study area.

  14. Hydrogeochemical and isotopic investigations of the Han River basin, South Korea

    NASA Astrophysics Data System (ADS)

    Ryu, Jong-Sik; Lee, Kwang-Sik; Chang, Ho-Wan

    2007-10-01

    SummaryThe Han River, the largest river in South Korea draining approximately 26,000 km 2, comprises two major tributaries: the North and the South Han Rivers. Seasonal and spatial variations in the major ion chemistry and isotope compositions of the Han River were monitored for one year at 14-23 locations, covering about 80% of the entire drainage basin. Compared to the South Han River (SHR), the North Han River (NHR) was much lower in total dissolved solids (TDS), Sr, and major ion concentrations, but higher in Si concentration, δ 34S SO 4 values, and 87Sr/ 86Sr ratios. These observations suggest strong influence of prevailing rock types in the drainage basins on the chemical and isotopic compositions of the river waters. These are silicate rocks in the NHR basin and carbonate rocks in the SHR basin. The headwaters of the NHR basin, where several flood control dams have been constructed, show enrichment in deuterium and oxygen-18, indicating evaporative loss. The δ 34S SO 4 data suggest dissolved sulfates in the NHR and SHR are mostly derived from atmospheric deposition, and variable mixtures of atmospheric deposition and sulfide oxidation, respectively. The 87Sr/ 86Sr ratios are much higher in the NHR (0.71793-0.72722) than in the SHR (0.71495-0.71785) with one exception, indicating weathering of Precambrian and Mesozoic granitic rocks and marine carbonates, respectively.

  15. Research on Meteorological Features of PBL during Heavy Haze Episodes in the City of Chengdu, Sichuan Basin, China

    NASA Astrophysics Data System (ADS)

    Lu, X.; Han, L.

    2014-12-01

    Sichuan basin is one of the areas that have the most serious haze in China. To understand how wind, temperature ,relative humidity and PHLH influence air pollution, WRF was used to simulate the meteorological condition of PBL during two heavy haze episodes in 2013. Combined with the local meteorological data and air pollution data, the analysis shows that cyclone is caused by the terrain of basin often. Air pollutants are limited in the basin and accumulate periodically. The concentration of O3 is significantly correlated with temperature while negatively correlated with relative humidity. There are significant negative correlations between the pollutants concentrations and the height of PBL. During the episode from 2nd to 23th March,the highest daily concentration of PM2.5 was 270ug/m3. The relativity between PM2.5 and O3 is lower than normal because of the dust storm. The correlation coefficients between O3 and temperature and relative humidity are 0.756 and -0.735, respectively. The dominant wind direction is south-west through the PBL. During the episode from 10th to 22nd April, the highest daily concentration of PM2.5 was 158ug/m3. The correlation coefficients between O3 and PM2.5, temperature, and relative humidity are 0.516, 0.825, -797, respectively. The dominant wind direction was south-west through PBL.

  16. 72. (Credit LSU) Aerator in settling basin south of McNeil ...

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

    72. (Credit LSU) Aerator in settling basin south of McNeil Pumping Station c1907. (Louisiana State University in Shreveport Archives, post card collection) - McNeil Street Pumping Station, McNeil Street & Cross Bayou, Shreveport, Caddo Parish, LA

  17. Archaeal Diversity in Marine Sediments in the South China Sea

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Wang, P.; Liu, Z.; Zhao, M.; Zhang, C.

    2010-12-01

    Archaea are widespread and play an important role in the global carbon and nitrogen cycles. However, we still have limited knowledge about archaeal diversity and their function in the natural environment. The purpose of this study was to examine the diversity, distribution and abundance of archaea associated with methane-rich sediments in the South China Sea. A gravity core (HQ08-48PC, 714 cm) was collected from the northern South China Sea and aseptically sliced into 20-cm sections. Samples from near the surface (0-20 cm), middle (350-370 cm) and bottom (630-650 cm) of the core were used for the construction of archaeal clone libraries. Chemical analysis indicated that the core was rich in methane (13.6-58.8 ppm) and had low TOC/TN ratios (< 8), which indicated a marine source of the organic matter. Total amino acids ranged between 2.72 µmol/g and 8.75 µmol/g. Phylogenetic analysis revealed that archaeal community structures were dramatically different and Crenarchaeaota dominates over Euryarchaeota among the surface, middle and bottom sediments of the core. The dominant archaeal groups were MGI (40%), MBGB (27%) and MCG (9%) in the surface sediment, MCG (35%), MBGD (20%) and MCG (20%) in the middle sediment, and MCG (52%) and MBGD (33%) in the bottom sediment. MCG and MBGD increased in phytotypes with increasing depth of the core, indicating their potential importance in deeper marine subsurface. The archaeal lipids (GDGTs) showed an increase in abundance with depth. Calculations of TEX86 based on certain types of GDGTs suggested a dramatic change in sea surface temperature (SST) that might correspond to the transition from the last glacial maximum (LGM) to post-glacial period. This study will enhance our understanding of archaeal diversity and function as well as their paleoclimate applications in the South China Sea.

  18. Precipitation variability assessment of northeast China: Songhua River basin

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Imran; Liu, Dong; Fu, Qiang; Azmat, Muhammad; Luo, Mingjie; Hu, Yuxiang; Zhang, Yongjia; Abrar, Faiz M.

    2016-07-01

    Variability in precipitation is critical for the management of water resources. In this study, the research entropy base concept was applied to investigate spatial and temporal variability of the precipitation during 1964-2013 in the Songhua River basin of Heilongjiang Province in China. Sample entropy was applied on precipitation data on a monthly, seasonally, annually, decade scale and the number of rainy days for each selected station. Intensity entropy and apportionment entropy were used to calculate the variability over individual year and decade, respectively. Subsequently, Spearman's Rho and Mann-Kendall tests were applied to observe for trends in the precipitation time series. The statistics of sample disorder index showed that the precipitation during February (mean 1.09, max. 1.26 and min. 0.80), April (mean 1.12, max. 1.29 and min. 0.99) and July (mean 1.10, max. 1.20 and min. 0.98) contributed significantly higher than those of other months. Overall, the contribution of the winter season was considerably high with a standard deviation of 0.10. The precipitation variability on decade basis was observed to increase from decade 1964-1973 and 1994-2003 with a mean value of decadal apportionment disorder index 0.023 and 0.053, respectively. In addition, the Mann-Kendall test value (1.90) showed a significant positive trend only at the Shangzhi station.

  19. Sphingomonas arantia sp. nov., isolated from Hoh Xil basin, China.

    PubMed

    Jia, Li; Zheng, Zhong; Feng, Xiaomin; Nogi, Yuichi; Yang, Aichen; Zhang, Yali; Han, Lu; Lu, Zhenquan; Lv, Jie

    2015-12-01

    A Gram-negative, rod-shaped, non-motile, non-spore forming, aerobic, orange-pigmented bacterium, designated strain 6P(T), was isolated from a soil sample collected from the Hoh Xil basin, China. Strain 6P(T) grew optimally at 25 °C, pH 7.0-7.5 and NaCl concentration of 0-1 % (w/v). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 6P(T) belongs to the genus Sphingomonas, with high sequence similarity (97.1 %) to Sphingomonas fennica. The DNA-DNA hybridization homology with S. fennica DSM 13665(T) was 45.3 %. The DNA G+C content of the novel strain is 65.3 mol%. The isolate contained Q-10 as the only respiratory quinone. The major polar lipids are diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylcholine (PC) and sphingoglycolipid (SGL). C18:1 ω7c and C16:1 ω7c are the major fatty acids. On the basis of the polyphasic evidence presented, strain 6P(T) represents a novel species of the genus Sphingomonas, for which the name Sphingomonas arantia sp. nov. is proposed. The type strain is 6P(T) (=CGMCC 1.12702(T) = JCM 19855(T)). PMID:26363912

  20. Platform cathodic protection design in the South China Sea

    SciTech Connect

    Rippon, I.

    1997-09-01

    The 1993 revision of one of the industry recommended practices on cathodic protection design offers the operator the opportunity to use his own experience and data to justify more or less conservative designs. Examples of the use of this option to achieve an economic South China Sea design are presented. The design approach on how to subdivide the object being cathodically protected can be applied in any operating area where there is good environmental data. An example of the cost savings achievable by using this approach is presented. The optimized design is 55% of the cost of the design following the 1993 code.

  1. Alkaloids from the South China Sea Black Coral Antipathes dichotoma.

    PubMed

    Qi, Shu-Hua; Su, Guo-Chen; Wang, Yi-Fei; Liu, Qiu-Ying; Gao, Cheng-Hai

    2009-01-01

    A new carbazole alkaloid, antipathine A (1), together with three known zoanthoxanthin alkaloids (2--4) was isolated from the EtOH/CH2Cl2 extracts of the South China Sea black coral Antipathes dichotoma. The structure of 1 was determined on the bases of extensive spectroscopic analysis, including 1D and 2D NMR data. Compounds 1 and 2 showed moderate cytotoxicity against human stomach carcinoma SGC-7901 cell line with IC50 of 67.38 and 86.40 microg/ml, respectively, and 1 and 2 also showed weak cytotoxicity toward human liver carcinoma Hep_G2 cell line.

  2. Steroids from the South China Sea gorgonian Subergorgia suberosa.

    PubMed

    Qi, Shu-Hua; Gao, Cheng-Hai; Qian, Pei-Yuan; Zhang, Si

    2010-02-01

    From the South China sea gorgonian Subergorgia suberosa, two new steroids, (22E)-14alpha-hydroxy-cholesta-1,4,22-trien-3-one (1) and 3-(1',2'-ethandiol)-cholest-3beta,5alpha,6alpha,11alpha-tetraol (2) were obtained, in addition to six known steroids. The structures of compounds 1 and 2 were determined by spectroscopic methods. Cytotoxicity of the six known steroids against human cancer cell lines A549, HONE1, and HeLa was evaluated by MTT methods, and their anti-larval activity was evaluated in settlement inhibition assays with laboratory-reared Balanus amphitrite and Bugular neritina larvae.

  3. Provenance and tectonic-paleogeographic evolution: Constraints from detrital zircon U-Pb ages of Late Triassic-Early Jurassic deposits in the northern Sichuan basin, central China

    NASA Astrophysics Data System (ADS)

    Shao, Tongbin; Cheng, Nanfei; Song, Maoshuang

    2016-09-01

    U-Pb ages of 290 new detrital zircons from five Late Triassic-Early Jurassic sandstone samples in the northern Sichuan basin, along with other geological data, are used to constrain the sediment provenance and evaluate tectonic-paleogeographic evolution for the adjacent orogens through/from which these sediments were potentially derived. The Upper Triassic depocenter was located at the front of the Longmen Shan belt, and sediments in the western, southern and eastern Sichuan basin shared the southern North China block (NCB) and Qinling belt with the eastern Songpan-Ganzi terrane of Middle-Upper Triassic via the Longmen Shan belt, whereas the northern part of the basin was fed by dominant South Qinling belt (SQB) and northern Yangtze block and possibly subordinate southern NCB. Also, the youngest population in the northern Sichuan basin has a slightly younger age peak (∼235 Ma) than those (∼270 Ma) in other parts of the basin. During the Early Jurassic, the depocenter was still at the front of the Longmen Shan belt but only northern regions (e.g., SQB and northern Yangtze block) fed the basin. The northern Sichuan basin received less sediments from the southern NCB and more from the SQB and northern Yangtze block during the Early Jurassic than during the Late Triassic. The middle Mesoproterozoic detrital zircons, which likely originated from the North Qinling belt and northern Yangtze block where rocks with these zircons may be unexposed, occur more widely in the Lower Jurassic than in the Upper Triassic. These facts suggest that from the Late Triassic to Early Jurassic, it was increasingly difficult for sediments to transport from the NCB into the northern Sichuan basin and the provenance transferred progressively from the southern NCB to both the SQB and northern Yangtze block, implying the continuous South China block-NCB collision during that time.

  4. Depositional features and source and reservoir rocks of Tertiary age in northern part of South China Sea

    SciTech Connect

    Wang, S.

    1986-07-01

    The northern part of the South China Sea covers an area of about 400,000 km/sup 2/. Tertiary deposits more than 10,000 m in thickness are widely distributed there. The area has sedimentary rocks more than 1000 m thick covers more than 300,000 km/sup 2/. Five sedimentary basins have been established in this area: Beibu Bay, Yinggehai, Southeastern Qiong, Pearl River Mouth, and Southwestern Taiwann basins. The primary source and reservoir rocks for oil and gas prospects are of Tertiary age. Tertiary rocks underwent three stages of development, each forming a specific sedimentation system: (1) a system of fluviolacustrine deposits in rift depressions from the Paleocene to early Oligocene; (2) a system of semiclosed-sea deposits from the late Oligocene to early Miocene; and (3) a system of deltaic open-sea deposits from the middle Miocene to Pliocene. These three sedimentation systems resulted in three suites of source rocks, three suites of reservoir rocks, and three groups of independent oil pools, complete with source, reservoir, and cap rocks. The three suites of source rocks are as follows: (1) the Eocene Liushagang Formation in the Beibu Bay basin, which is believed to be the best source rock discovered in the area; (2) the Oligocene Zhuhai Formation in the Pearl River Mouth basin; and (3) the lower Miocene series in the Pearl River Mouth basin. The Eocene formation is probably the principal source rock of regional scale in the northern part of the South China Sea. The three suites of reservoir rocks are as follows: (1) the fluviolacustrine sandstone bodies in the Liushagang Formation; (2) the fluviolacustrine sand bodies and shallow-sea sandstone bodies in the Zhuhai Formation and Lingshu Formation; (3) the deltaic, littoral, and shallow-sea sand bodies and bioherms of Neogene age, with the middle Miocene sandstone reservoirs having the best physical properties.

  5. Climatic and tectonic controls on Late Triassic to Middle Jurassic sedimentation in northeastern Guangdong Province, South China

    NASA Astrophysics Data System (ADS)

    Pang, Chong-Jin; Li, Zheng-Xiang; Xu, Yi-Gang; Wen, Shu-Nv; Krapež, Bryan

    2016-05-01

    Stratigraphic analyses document climatic and tectonic controls on the filling of a Late Triassic to early Middle Jurassic (T3-J2) basin that developed on top of a young orogenic belt in southeastern South China. About 2700 m of Carnian to Bajocian sedimentary rocks is documented in the Meizhou region, Guangdong Province. The Carnian to Rhaetian sequence is characterized by deltaic facies that are succeeded by Hettangian fluvial, shallow marine and volcaniclastic facies, and by Sinemurian to early Toarcian interdistributary bay and floodplain facies. The late Toarcian to Bajocian sequence comprises proximal alluvial to lacustrine facies that changed upwards to fluvial facies. Fossil assemblages indicate that climatic conditions changed from tropical/subtropical warm humid, to temperate humid, and then to hot arid through the Late Triassic to the Middle Jurassic. Climatically induced changes (e.g., in precipitation, vegetation and erosion) exerted a strong influence on sediment supply, whereas tectonics played a dominant role in stratigraphic evolution, accommodation generation, sedimentation pattern and volcanism. Tectonostratigraphic analysis shows that the T3-J2 basin was initiated on an orogenic belt during late-stage orogeny, and evolved into shallow-marine and volcanic environments and then back to terrestrial facies during the post-orogenic stage. This was followed by regional uplift and the development of a basin-and-range province. The order of these events is similar to that of the central Rocky Mountains, western North America during the Palaeogene. The Mesozoic basin of South China and the Eocene basins of the central Rocky Mountains highlight the importance of subduction-related subsidence above young and broad orogens.

  6. Tertiary carbonate development on the Shenhu Massif, South China Sea

    SciTech Connect

    Turner, N.L. ); Siemann-Gartmann, S. )

    1994-07-01

    The Shenhu Massif lies between the Zhu III Depression to the northwest, the Kaiping/Baiyun depressions to the northeast, and the Xisha Basin to the south. Major faulting began in the Paleocene, and initial basins formed on and around the Shenhu Massif during this time. Continental coarse clastics, derived from the massif area, filled the basins prior to the middle Oligocene though larger, deeper basins may have contained lacustrine environments. During the marine incursion from the middle Oligocene and until the early Miocene, coarse clastics were deposited adjacent to exposed basement areas, fine marine clastics were deposited on the massif, carbonate buildups formed along the massif rim, and carbonate platforms developed from the massif edge back into the shallow-water high-massif interior. In mid-lower Miocene, the carbonate areas were reduced in size and replaced by shales. Carbonate deposition as layers and mounds was reestablished over much of the Shenhu Massif in the early and middle Miocene. Prodelta shales in the east Shenhu Massif area and coarser clastics present in clinoforms in the Baiyun Depression are the distal components of a southerly prograding delta system located to the north. Carbonates continued to develop along the southeast side of the west Shenhu Massif during the latter part of the middle Miocene, but fine clastics dominated the rest of the area except in the Kaiping/Baiyun Depression where coarser clastics from the delta were deposited. Amoco and its partners, Nanhai West Oil Co. and Kerr-McGee Co., have begun evaluation of the Shenhu Massif area with the drilling of a Miocene carbonate buildup, the Amoco 23-1 Baodao prospect.

  7. Watershed scale response to climate change--South Fork Flathead River Basin, Montana

    USGS Publications Warehouse

    Chase, Katherine J.; Hay, Lauren E.; Markstrom, Steven L.

    2012-01-01

    Fourteen basins for which the Precipitation Runoff Modeling System has been calibrated and evaluated were selected as study sites. Precipitation Runoff Modeling System is a deterministic, distributed parameter watershed model developed to evaluate the effects of various combinations of precipitation, temperature, and land use on streamflow and general basin hydrology. Output from five General Circulation Model simulations and four emission scenarios were used to develop an ensemble of climate-change scenarios for each basin. These ensembles were simulated with the corresponding Precipitation Runoff Modeling System model. This fact sheet summarizes the hydrologic effect and sensitivity of the Precipitation Runoff Modeling System simulations to climate change for the South Fork Flathead River Basin, Montana.

  8. Paleostress inversion of fault-slip data from the Jurassic to Cretaceous Huangshan Basin and implications for the tectonic evolution of southeastern China

    NASA Astrophysics Data System (ADS)

    Xu, Xianbing; Tang, Shuai; Lin, Shoufa

    2016-08-01

    Eight paleostress stages are established in the Jurassic-Cretaceous Huangshan Basin based on fault-slip analysis and age estimation. The first six stages correspond to the subduction of the Paleo-Pacific Plate or the northward motion of the Philippine Block along the southeastern active margin of the South China Block: (1) the 169-162 Ma strike-slip regime was caused by westward low-angle subduction of the Paleo-Pacific Plate, which resulted in NNE-striking folds and top-to-the west thrusting along the southeastern margin of the Huangshan Basin; (2) the 156-125 Ma NW-SE extensional regime was triggered by slab break-off of the Paleo-Pacific Plate. This extension led to Early Cretaceous magmatism, deposition of Early Cretaceous sediments and development of normal faults along the northern boundary of the Huangshan Basin; (3) the 125-107 Ma strike-slip regime was induced by the N-S collision between the Philippine and South China blocks. This tectonic event caused the angular unconformity between the Upper and Lower Cretaceous and the inversion of the Early Cretaceous extensional basin; (4) the 105-86 Ma WNW-ESE extensional regime resulted from an off-shore arc jump of the subducted Paleo-Pacific Plate. This extension triggered the deposition of the Late Cretaceous Qiyunshan Formation; (5) the 86-80 Ma strike-slip regime was induced by high-angle subduction of the Pacific Plate after the off-shore arc jump. This event led to regional uplift and an unconformity at the base of the Late Cretaceous Xiaoyan Formation; (6) the 80-36 Ma N-S extensional regime was caused by the extension following the collision between the Philippine and South China blocks, corresponding to the deposition of the Late Cretaceous Xiaoyan Formation. The last two paleostress stages were the consequences of the far-field effect of the India-Asia continent-continent collision to the southwest of the South China Block: (7) the 36-30 Ma strike-slip regime was caused by the India-Asia collision. It

  9. Influence of small river derived sediment on the Northeastern South China Sea sedimentation processes in the last 40 K years

    NASA Astrophysics Data System (ADS)

    Cheng, Wan-Yen; Lin, Saulwood; Lou, Jiann-Yuh; Wei, Kuo-Yen; Liu, CharShine; Chen, Shing-Li; Wang, Yun-Shuen

    2015-04-01

    Small rivers derived particles are major source of sediment to the ocean in the present time. Small rivers in Taiwan are subjected to fast tectonic activity, high precipitation rate and erosion rate. The combined annual river particle load from small rivers on the Island of Taiwan is higher than that of the Mississippi River. A large fraction of those rivers particle may finding its way into the surrounding seas and ocean, e.g. South China Sea, East China Sea, and the Philippine Sea. Furthermore, due to the nature of particle transportation off rivers from Taiwan were connected by a number of canyon systems close by the river mouth, majority of those river particles were facilitated in delivering and deposited later further into the South China Sea deep basin. The objectives of this study are to understand spatial variations in sedimentation rates and to resolve the temporal differences in sedimentation in the Northeastern South China Sea region, and to evaluate influence of small river particles to the marginal sea. A set of cores was collected in overlying water depth within 1600 - 3300 m for mutilsensor core logging of magnetic susceptibility, density, and porosity. Foraminifera (G. sacculifer, G. conglobatus, O. universa) were picked and AMS C14 analyses for age determination. Grain size, organic carbon, carbonate and biogenic silica content were measured. The results show that large sedimentation rates difference existed in the study area. Earlier studies on sedimentation rate in the region west of our study area were in range of about 10 cm/kyr while our rates are about 20-40 cm/kyr and much higher near Taiwan. Bulk sedimentation rate were higher during the transition period between LGM and Holocene and lower during Holocene. Our results demonstrated that large quantity of particles from small rivers in Taiwan are and were major source of particle and are the dominating factor in controlling sediment deposition in the northeastern South China Sea.

  10. Andean Basins Morphometry: Assesing South American Large Rivers' Source Areas

    NASA Astrophysics Data System (ADS)

    Bean, R. A.; Latrubesse, E. M.

    2014-12-01

    Presently there are no regional-scale morphometric analyses of Andean fluvial basins. Therefore, we created a continental-scale database of these basins. Our data covers over an area 1,000,000 km2 of the Andes, from Venezuela to Argentina. These basins are the source of some of the largest rivers in the world including the Amazon, Orinoco, Parana, and Magdalena. Morphometric parameters including shape factor, relief ratio, longitudinal profiles and different indices of basin elevation were calculated based on the CGIAR SRTM 4.1 DEM (~90 m resolution). FAO Hydrosheds were used to segment the DEM by major catchment and then manually cut at the Andean zone. In the North and Central Andes, this produced over 500,000 subcatchments, which we reduced to 619 by setting minimum catchment area to 100 km2. We then integrate lithologic data from DNPM geologic data. Our results indicate that sedimentary lithologies dominate Central Andean catchments (n=268,k=4), which cover an area 767,00 km2, while the Northern Andean catchments (covering 350,000 km2) are more varied, dominated by volcanics in the Pacific (n=78), a sedimentary (48%) dominant mix in the Caribbean (n=138) and 60% sedimentary in the Amazon-Orinoco subregion catchments (n=138). Elevation averages are smallest in the north Andes and average maximum elevations (6,026 m) in the Argentinian catchments (n=65) of the Central Andes are the highest. Shape factors range from 0.49 to 0.58 in the North and 0.52 to 0.58 in the Central Andes. There are clear differences in all categories between region and subregion, but that difference does not hinge on a single morphometric or geologic parameter. Morphometric parameters at a watershed scale (listed in Table) are analyzed and hydrologic data from gauging stations throughout the Andes (n=100) are used to compare morphometric parameters with lithology and characteristics from the basin hydrograph (peak discharge timing, minimum and maximum discharge, and runoff).

  11. Lithospheric electrical structure of South China imaged by magnetotelluric data and its tectonic implications

    NASA Astrophysics Data System (ADS)

    Zhang, Letian; Jin, Sheng; Wei, Wenbo; Ye, Gaofeng; Jing, Jianen; Dong, Hao; Xie, Chengliang

    2015-02-01

    The region of South China mainly consists of the Yangtze block in the northwest, the Cathaysia block in the southeast and the Jiangnan orogen in between these two major Precambrian continental blocks. The Yangtze block borders the North China Craton in the north and the eastern margin of the Tibetan Plateau in the west. The Cathaysia block adjoins the Pacific tectonic domain in the east. The study of tectonics in this region is of great significance given its important role in understanding the formation of the Asia continent. Under the auspices of SinoProbe Project, new magnetotelluric (MT) data were collected along a ∼1200 km long profile starting from central Sichuan Basin near Suining, extending southeastward, passing through the Yangtze Block, Jiangnan Orogen, and terminating within the western Cathaysia Block near Ganzhou. Based on data analysis results, 2D inversions were conducted on the dataset. Resulting model shows that the lithospheric electrical structure of South China is generally resistive which is consistent with the basic feature of stable Precambrian tectonic setting. The resistive western Yangtze block represents the stable, Archean aged cratonic region of the Yangtze basement. While the electrically conductive eastern Yangtze block is characterized by lithospheric shearing of the strike-slip fault system and extensional process that is probably caused by slab roll-back of a flatly subducted plate. The Jiangshao fault performs as a northwestward dipping conductive layer, which indicates the lithospheric underthrusting of Cathaysia block beneath Yangtze block with its frontal edge reaching the area of Jishou in the upper mantle. To the west of Jiangshao fault, eastern flank of the Xuefengshan Mountain marks the overthrusting frontier of the Yangtze block, as well as its southeastern boundary. To the east of Jiangshao fault, the northwestern boundary of the Cathaysia block displays the pattern of wedging tectonics, which is characterized by a

  12. The rift architecture and extensional tectonics of the South China Sea

    NASA Astrophysics Data System (ADS)

    Cameselle, Alejandra L.; Ranero, César R.; Barckhausen, Udo; Franke, Dieter

    2016-04-01

    Non-volcanic rifted continental margins are classically described as the product of lithospheric stretching and breakup leading to mantle exhumation, and subsequent seafloor spreading. However, recent studies question this model and indicate a wider range of structural evolutions, that challenge the existing model (e.g. Australia-Antarctic Rift System (Direen et al. 2007, 2011); the Tyrrhenian basin (Prada et al., 2014) or the South China Sea (Cameselle et al. 2015)). Rifting in the South China Sea developed from a series of extensional events, from early Eocene to Late Oligocene, resulting in a V-shape oceanic basin affected by the occurrence of several spreading centers, ridges, transform faults and post-spreading volcanism. In recent years, this marginal basin - the largest in East Asia - has increasingly become one of the key sites for the study of rifting and continental break-up. Its relative small size - compared to many classic, Atlantic-type continental margin settings - allows to easily match conjugated rifted margins and its relative youth promotes the preservation of its original nature. To examine the rifting evolution of the South China Sea, we have reprocessed with modern algorithms multichannel seismic profiles acquired during Sonne49 and BGR84 cruises across the three major subbasins: NW, SW and East subbasins. State-of-the-art of processing techniques have been used to increase the signal to noise ratio, including Tau-P and Wiener predictive deconvolution, multiple attenuation by both radon filtering and wave-equation-based surface-related multiple elimination (SRME) and time migration. To complement seismic interpretation, available vintage multichannel seismic data have been reprocessed with a post-stack flow, including Wiener deconvolution, FK-filtering, space and time variant band-pass filter and time migration. The improving quality of the seismic images shows a range of features including post-rift and syn-rift sediments, the structure of

  13. Ozone trends in California`s South Coast Air Basin, 1976--1996

    SciTech Connect

    Cohanim, S.; Cassmassi, J.; Bassett, M.

    1998-12-31

    The South Coast Air Basin (Basin) of Southern California exhibits the worst air quality in the nation, as measured by the annual number of days exceeding the 1-hour National Ambient Air Quality Standard (NAAQS) for ozone. Hourly pollutant concentration data collected by the South Coast Air Quality Management District`s air monitoring network are compared to the existing 1-hour and new 8-hour federal ozone ambient air quality standards to depict ozone trends and compliance in the Basin. Results of trend analyses for the different areas of the Basin are presented for the 1-hour and 8-hour standards, and the relative stringency of the existing and new federal standards is examined. Based on an analysis of the effect of the recently adopted federal standard on ozone compliance in the Basin, ozone concentrations exceed the new federal 8-hour standard level more often than the existing 1-hour standard in most locations. However, examination of the trends in design values for the 1-hour and 8-hour ozone standards suggests that for most locations in the Basin the new standard probably should not be significantly more difficult to attain than the existing standard. The weather-adjusted ozone trend analysis in the Basin confirms the fact that the downtrends in ozone concentrations and number of days exceeding standards are real and independent of annual variation in weather. An analysis of weekday/weekend differences in exceedances for the existing 1-hour and new 8-hour ozone standards show a higher number of days exceeding both standards on weekends for most locations in the Basin, with differences being more evident in the 1990s than in the late 1970s and 1980s

  14. Climate extremes in Malaysia and the equatorial South China Sea

    NASA Astrophysics Data System (ADS)

    Salahuddin, Ahmed; Curtis, Scott

    2011-08-01

    The southern extent of the South China Sea (SCS) is an important natural resource epicenter for Malaysia which experiences climate extremes. This paper documents the variability of extremes in the equatorial SCS through selected ground-based observations of precipitation in Malaysia and ship-based observations of wind data in the Maritime Continent region, to elucidate the interrelationship between precipitation variability over Malaysia and wind variability over the ocean. The data have been carefully inspected and analyzed, and related to the real-time multivariate Madden-Julian Oscillation (MJO) time series. The analysis suggests that the northeast or boreal winter monsoon dominates extreme rainfall in eastern Malaysian cities. Further, the west coast of Peninsular Malaysia and Borneo Malaysia are affected by the MJO differently than the east coast of Peninsular Malaysia. From the wind analysis we found that average zonal wind is westerly from May to September and easterly from November to April. When the active (convective) phase of the MJO is centered over the Maritime Continent, the strong westerly wind bursts are more frequent in the South China Sea. While more investigation is needed, these results suggest that the status of the Madden-Julian Oscillation can be used to help forecast climate extremes in areas of Malaysia.

  15. Rock types of South Pole-Aitken basin and extent of basaltic volcanism

    USGS Publications Warehouse

    Pieters, C.M.; Head, J. W.; Gaddis, L.; Jolliff, B.; Duke, M.

    2001-01-01

    The enormous pre-Nectarian South Pole-Aitken (SPA) basin represents a geophysically and compositionally unique region on the Moon. We present and analyze the mineralogical diversity across this basin and discuss the implications for basin evolution. Rock types are derived from Clementine multispectral data based on diagnostic characteristics of ferrous absorptions in fresh materials. Individual areas are characterized as noritic (dominated by low-Ca pyroxene), gabbroic/basaltic (dominated by high-Ca pyroxene), feldspathic (<3-6% FeO), and olivine-gabbro (dominated by high-Ca pyroxene and olivine). The anorthositic crust has effectively been removed from the interior of the basin. The style of volcanism within the basin extends over several 100 Myr and includes mare basalt and pyroclastic deposits. Several areas of ancient (pre-Orientale) volcanism, or cryptomaria, have also been identified. The nonmare mafic lithology that occurs across the basin is shown to be noritic in composition and is pervasive laterally and vertically. We interpret this to represent impact melt/breccia deposits derived from the lower crust. A few localized areas are identified within the basin that contain more diverse lithologies (gabbro, olivine-gabbro), some of which may represent material from the deepest part of the lower crust and perhaps uppermost mantle involved in the SPA event. Copyright 2001 by the American Geophysical Union.

  16. Intensified Springtime Deep Convection over the South China Sea and the Philippine Sea Dries Southern China

    PubMed Central

    Li, Zhenning; Yang, Song; He, Bian; Hu, Chundi

    2016-01-01

    Springtime rainfall, accounting for 25–40% of the annual rainfall in southern China, exerts great agricultural and socioeconomic impacts on the region. In the recent decades, southern China has experienced a significant declining trend of precipitation in boreal spring. Meanwhile, precipitation has increased over the South China Sea and the Philippine Sea (SCS-PhS). This paper presents observational and modeling evidences suggesting that the intensified latent heating released by the convection over SCS-PhS leads to suppressed springtime rainfall over southern China. Moisture budget analysis indicates that the drying trend over southern China is due mainly to weakened convergence of moisture flux, which is controlled by a heat-induced anomalous overturning circulation reinforced by the convection over SCS-PhS. Further idealized simulations support the feature that the heat-induced overturning circulation and its corresponding anomalous cyclone can be well established in several days under the spring mean flow condition. Thus, this rapid dynamic process is associated with both the intraseasonal-to-interannual variations and the long-term change of the springtime rainfall over southern China. PMID:27461985

  17. Intensified Springtime Deep Convection over the South China Sea and the Philippine Sea Dries Southern China.

    PubMed

    Li, Zhenning; Yang, Song; He, Bian; Hu, Chundi

    2016-07-27

    Springtime rainfall, accounting for 25-40% of the annual rainfall in southern China, exerts great agricultural and socioeconomic impacts on the region. In the recent decades, southern China has experienced a significant declining trend of precipitation in boreal spring. Meanwhile, precipitation has increased over the South China Sea and the Philippine Sea (SCS-PhS). This paper presents observational and modeling evidences suggesting that the intensified latent heating released by the convection over SCS-PhS leads to suppressed springtime rainfall over southern China. Moisture budget analysis indicates that the drying trend over southern China is due mainly to weakened convergence of moisture flux, which is controlled by a heat-induced anomalous overturning circulation reinforced by the convection over SCS-PhS. Further idealized simulations support the feature that the heat-induced overturning circulation and its corresponding anomalous cyclone can be well established in several days under the spring mean flow condition. Thus, this rapid dynamic process is associated with both the intraseasonal-to-interannual variations and the long-term change of the springtime rainfall over southern China.

  18. Intensified Springtime Deep Convection over the South China Sea and the Philippine Sea Dries Southern China

    NASA Astrophysics Data System (ADS)

    Li, Zhenning; Yang, Song; He, Bian; Hu, Chundi

    2016-07-01

    Springtime rainfall, accounting for 25–40% of the annual rainfall in southern China, exerts great agricultural and socioeconomic impacts on the region. In the recent decades, southern China has experienced a significant declining trend of precipitation in boreal spring. Meanwhile, precipitation has increased over the South China Sea and the Philippine Sea (SCS-PhS). This paper presents observational and modeling evidences suggesting that the intensified latent heating released by the convection over SCS-PhS leads to suppressed springtime rainfall over southern China. Moisture budget analysis indicates that the drying trend over southern China is due mainly to weakened convergence of moisture flux, which is controlled by a heat-induced anomalous overturning circulation reinforced by the convection over SCS-PhS. Further idealized simulations support the feature that the heat-induced overturning circulation and its corresponding anomalous cyclone can be well established in several days under the spring mean flow condition. Thus, this rapid dynamic process is associated with both the intraseasonal-to-interannual variations and the long-term change of the springtime rainfall over southern China.

  19. Intensified Springtime Deep Convection over the South China Sea and the Philippine Sea Dries Southern China.

    PubMed

    Li, Zhenning; Yang, Song; He, Bian; Hu, Chundi

    2016-01-01

    Springtime rainfall, accounting for 25-40% of the annual rainfall in southern China, exerts great agricultural and socioeconomic impacts on the region. In the recent decades, southern China has experienced a significant declining trend of precipitation in boreal spring. Meanwhile, precipitation has increased over the South China Sea and the Philippine Sea (SCS-PhS). This paper presents observational and modeling evidences suggesting that the intensified latent heating released by the convection over SCS-PhS leads to suppressed springtime rainfall over southern China. Moisture budget analysis indicates that the drying trend over southern China is due mainly to weakened convergence of moisture flux, which is controlled by a heat-induced anomalous overturning circulation reinforced by the convection over SCS-PhS. Further idealized simulations support the feature that the heat-induced overturning circulation and its corresponding anomalous cyclone can be well established in several days under the spring mean flow condition. Thus, this rapid dynamic process is associated with both the intraseasonal-to-interannual variations and the long-term change of the springtime rainfall over southern China. PMID:27461985

  20. Preliminary interpretation of industry two-dimensional seismic data from Susitna Basin, south-central Alaska

    USGS Publications Warehouse

    Lewis, Kristen A.; Potter, Christopher J.; Shah, Anjana K.; Stanley, Richard G.; Haeussler, Peter J.; Saltus, Richard W.

    2015-07-30

    The eastern seismic lines show evidence of numerous short-wavelength antiforms that appear to correspond to a series of northeast-trending lineations observed in aeromagnetic data, which have been interpreted as being due to folding of Paleogene volcanic strata. The eastern side of the basin is also cut by a number of reverse faults and thrust faults, the majority of which strike north-south. The western side of the Susitna Basin is cut by a series of regional reverse faults and is characterized by synformal structures in two fault blocks between the Kahiltna River and Skwentna faults. These synforms are progressively deeper to the west in the footwalls of the east-vergent Skwentna and northeast-vergent Beluga Mountain reverse faults. Although the seismic data are limited to the south, we interpret a potential regional south-southeast-directed reverse fault striking east-northeast on the east side of the basin that may cross the entire southern portion of the basin.

  1. Internal Wave Study in the South China Sea Using SAR

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Hsu, Ming-Kuang; Zukor, Dorothy (Technical Monitor)

    2000-01-01

    Recently, the internal wave distribution maps in the China Seas have been compiled from hundreds of ERS-1/2, RADARSAT, and Space Shuttle SAR (Synthetic Aperture Radar) images from 1993 to 1999. Based on internal wave distribution map, most of internal waves in the northeast part of South China Sea were propagating westward. The wave crest can be as long as 200 km with amplitude of 100 m due to strong current from the Kuroshio branching out into the South China Sea. Based on the observations from drilling rigs near DongSha Island by Amoco Production Co., the solitons may be generated in a 4 km wide channel between Batan and Sabtang islands in Luzon Strait. The proposed generation mechanism is similar to the lee wave formation from a shallow topography. Both depression and elevation internal waves have been observed in the same RADARSAT ScanSAR image on May 4, 1998 near DongSha Island. Furthermore, depression and elevation internal waves have also been observed by SAR at the same location on the shelf in April and June, 1993 (in different seasons) respectively. Numerical models have been used to interpret their generation mechanism and evolution processes. Based on the SAR images, near DongSha Island, the westward propagating huge internal solitons are often encountered and diffracted/broken by the coral reefs on the shelf. After passing the island, the diffracted waves will re-merge or interact with each other. It has been observed that after the nonlinear wave-wave interaction, the phase of wave packet is shifted and wavelength is also changed. Examples of mesoscale features observed in SAR images, such as fronts, raincells, bathymetry, ship wakes, and oil spills will be presented. Recent mooring measurements in April 1999 near Dongsha Island, future field test ASIAEX (Asian Seas International Acoustics Experiment) planned for April 2001, and some pretest survey data will be discussed in this paper.

  2. Post-breakup Basin Evolution along the South-Atlantic Margins in Brazil and Angola/Namibia

    NASA Astrophysics Data System (ADS)

    Kukla, P. A.; Strozyk, F.; Back, S.

    2013-12-01

    The post-breakup tectono-stratigraphic evolution of large offshore basins along the South American and African continental margins record strongly varying post-rift sedimentary successions. The northernmost segment of the South Atlantic rift and salt basins is characterized by a pronounced asymmetry, with the Brazilian margin comprising narrower and deeper rift basins with less salt in comparison to the Congo-Gabon conjugate margin. Another important observation is that multiple phases of uplift and subsidence are recorded after the break-up of the southern South Atlantic on both sides of the Florianopolis-Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup margin successions. A regional comparison based on tectonic-stratigraphic analysis of selected seismic transects between the large basins offshore southern Brazil (Espirito Santo Basin, Campos Basin, Santos Basin, Pelotas Basin) and southwest Africa (Lower Congo Basin, Kwanza Basin, Namibe Basin, Walvis Basin) provides a comprehensive basin-to-basin documentation of the key geological parameters controlling ocean and continental margin development. This comparison includes the margin configuration, subsidence development through time, sediment influx and storage patterns, type of basin fill (e.g. salt vs. non-salt systems; carbonate-rich vs. clastics-dominated systems) and finally major tectonic and magmatic events. Data from the salt basins indicate that salt-related tectonic deformation is amongst the prime controls for the non-uniform post-rift margin development. The diversity in the stratigraphic architecture of the conjugate margins offshore southern Brazil, Namibia and Angola reflects variations in the interplay of a number of controlling factors, of which the most important are (a) the structural configuration of each margin segment at the time of break-up, (b) the post break-up subsidence history of the respective margin segment

  3. Petroleum source rocks of the Junggar, Tarim, and Turpan basins, northwest China

    SciTech Connect

    Graham, S.A.; Brassell, S.; Carroll, A.R.; McKnight, C.L.; Chu, J.; Hendrix, M.S. ); Xiao, X. ); Demaison, G. ); Liang, Y. )

    1990-05-01

    The sedimentary basins of Xinjiang Uygur Autonomous Region, China, are poorly explored for petroleum. Volumetric adequacy of petroleum source rocks is a critical exploration risk in these basins, particularly because source rock data are limited. However, recent studies provide new source rock data and permit speculative assessment of source rock potential of Xinjiang basins. The Junggar basin, best explored of Xinjiang basins and containing a giant oil field, is underlain over much of its extent by an Upper Permian lacustrine oil-shale sequence that is known for its organic richness and oil source quality. Depending on position in the basin, the Permian section ranges from immature to overmature and is inferred to be the principal source of oil in the basin. Upper Triassic-Middle Jurassic coal measures, including lacustrine rocks, constitute a secondary source rock sequence in the Junggar basin. The smaller intermontane Turpan basin contains a very similar Upper Triassic-Middle Jurassic sequence, which, where sufficiently deeply buried, probably comprises the only significant oil source sequence in the basin. The vast Tarim basin offers the greatest potential variety of petroleum source rocks of all Xinjiang basins, but remains the least well documented. From limited, but geologically planned and focused sampling, Cambrian, Carboniferous, and Permian strata are considered unlikely to be major oil source contributors in the dominantly shallow-marine Paleozoic section of the northern Tarim basin. Only Ordovician black shales appear to have significant oil source potential, and a lower Paleozoic source is confirmed for some Tarim oils by gas chromatography-mass spectrometry analysis. The Upper Triassic-Middle Jurassic sequence of northern Tarim basin, similar to that of the Junggar and Turpan basins in comprising a section rich in coal and lacustrine shale, constitutes another, potentially significant oil source.

  4. Imaging the South Pole-Aitken basin in backscattered neutral hydrogen atoms

    NASA Astrophysics Data System (ADS)

    Vorburger, A.; Wurz, P.; Barabash, S.; Wieser, M.; Futaana, Y.; Bhardwaj, A.; Asamura, K.

    2015-09-01

    The lunar surface is very efficient in reflecting impinging solar wind ions as energetic neutral atoms (ENAs). A global analysis of lunar hydrogen ENAs showed that on average 16% of the solar wind protons are reflected, and that the reflected fraction can range from less than 8% to more than 24%, depending on location. It is established that magnetic anomalies reduce the flux of backscattered hydrogen ENAs by screening-off a fraction of the impinging solar wind. The effects of the surface properties, such as porosity, roughness, chemical composition, and extent of weathering, were not known. In this paper, we conduct an in-depth analysis of ENA observations of the South Pole-Aitken basin to determine which of the surface properties might be responsible for the observed variation in the integral ENA flux. The South Pole-Aitken basin with its highly variable surface properties is an ideal object for such studies. It is very deep, possesses strikingly elevated concentrations in iron and thorium, has a low albedo and coincides with a cluster of strong magnetic anomalies located on the northern rim of the basin. Our analysis shows that whereas, as expected, the magnetic anomalies can account well for the observed ENA depletion at the South Pole-Aitken basin, none of the other surface properties seem to influence the ENA reflection efficiency. Therefore, the integral flux of backscattered hydrogen ENAs is mainly determined by the impinging plasma flux and ENA imaging of backscattered hydrogen captures the electrodynamics of the plasma at the surface. We cannot exclude minor effects by surface features. We create two maps of surface reflected ENAs at the South Pole-Aitken basin. We compare these ENA maps to elevation, albedo, composition and magnetic field maps. The ENA maps only significantly correlate with the magnetic field map. ENA imaging captures solely the electrodynamics of the plasma at the surface.

  5. Magnetic minerals in three Asian rivers draining into the South China Sea: Pearl, Red, and Mekong Rivers

    NASA Astrophysics Data System (ADS)

    Kissel, Catherine; Liu, Zhifei; Li, Jinhua; Wandres, Camille

    2016-05-01

    The use of the marine sedimentary magnetic properties, as tracers for changes in precipitation rate and in oceanic water masses transport and exchanges, implies to identify and to characterize the different sources of the detrital fraction. This is of particular importance in closed and/or marginal seas such as the South China Sea. We report on the magnetic properties of sedimentary samples collected in three main Asian rivers draining into the South China Sea: the Pearl, Red, and Mekong Rivers. The geological formations as well as the present climatic conditions are different from one catchment to another. The entire set of performed magnetic analyses (low-field magnetic susceptibility, ARM acquisition and decay, IRM acquisition and decay, back-field acquisition, thermal demagnetization of three-axes IRM, hysteresis parameters, FORC diagrams, and low-temperature magnetic measurements) allow us to identify the magnetic mineralogy and the grain-size distribution when magnetite is dominant. Some degree of variability is observed in each basin, illustrating different parent rocks and degree of weathering. On average it appears that the Pearl River is rich in magnetite along the main stream while the Mekong River is rich in hematite. The Red River is a mixture of the two. Compared to clay mineral assemblages and major element contents previously determined on the same samples, these new findings indicate that the magnetic fraction brings complementary information of great interest for environmental reconstructions based on marine sediments from the South China Sea.

  6. Modern nonmarine evaporite deposition, Quaidam basin, China: An overview

    SciTech Connect

    Lowenstien, T.K.; Casas, E.; Schubel, K.A. ); Spencer, R.J. ); Pengxi, Zhang )

    1991-03-01

    Dabusun Lake (200 km{sup 2}) is a shallow ({lt}1 m) perennial saline lake in the high altitude Qaidam basin (120,000 km{sup 2}) of western China. It is underlain by {gt}40 m of salt and siliciclastic sediments ({approximately}54,000 years old). Petrographic features in two 50 m cores (chevron halite, halite cumulates, rafts, and siliciclastic mud, minor solution and no subaerial exposure features except in the top meter) indicate continuous shallow perennial lake conditions. The chemical composition of fluid inclusions trapped in halite crystals show lakewaters have generally undergone progressive concentration to the present. Modern Dabusun Lake is chemically uniform (Na-Mg-Cl-rich), nonstratified, and at or near halite saturation. Evaporites accumulate in zones on the restricted lake margins as halite (cumulate and raft layers with rippled surfaces and chevron mounds), halite + carnallite (KCl{center dot}MgCl{sub 2}{center dot}6H{sub 2}O), and finally carnallite (ephemeral fine-grained crystal mush). The carnallite zone merges with a 25 m wide shoreline facies, highlighted by a 1 m wide zone of halite ooids/pisoids that border a 20-30 cm tall overhanging salt crust (1967 shoreline). Lower lake levels since that time have produced vadose diagenetic features in the shoreline halites including: pendant cements, meniscus cements, halite 'popcorn,' and solution voids with muddy geopetal fills. A large flood (July-September 1989) expanded Dabusun Lake to 800 km{sup 2}, and dissolved all surface carnallite deposits. Diagenetic carnallite cements, formed by downward migration and cooking of carnallite saturated surface brines, however, remain in the subsurface to depths of 13 m. These potash mineral cements are similar in texture to many ancient potash evaporites.

  7. Surveying the South Pole-Aitken basin magnetic anomaly for remnant impactor metallic iron

    USGS Publications Warehouse

    Cahill, Joshua T.S.; Hagerty, Justin J.; Lawrence, David M.; Klima, Rachel L.; Blewett, David T.

    2014-01-01

    The Moon has areas of magnetized crust ("magnetic anomalies"), the origins of which are poorly constrained. A magnetic anomaly near the northern rim of South Pole-Aitken (SPA) basin was recently postulated to originate from remnant metallic iron emplaced by the SPA basin-forming impactor. Here, we remotely examine the regolith of this SPA magnetic anomaly with a combination of Clementine and Lunar Prospector derived iron maps for any evidence of enhanced metallic iron content. We find that these data sets do not definitively detect the hypothesized remnant metallic iron within the upper tens of centimeters of the lunar regolith.

  8. Future acidification of marginal seas: A comparative study of the Japan/East Sea and the South China Sea

    NASA Astrophysics Data System (ADS)

    Luo, Yiming; Boudreau, Bernard P.

    2016-06-01

    The response of marginal (peripheral) seas to ocean acidification on short and long time scales is not well established. Through modeling, we examine the future acidification of two adjacent marginal seas, the South China Sea (SCS) and the Japan/East Sea (J/ES). Our results illustrate the importance of unique features in determining their acidification. The J/ES basin will become completely undersaturated with regard to calcite rapidly in the next few decades, while the SCS basin will experience relatively slower acidification. During its acidification, the J/ES will continually act as a sink for atmospheric CO2, whereas the SCS will temporarily switch from a source to a sink during the peak pCO2 interval, only to return slowly to being a source again. Marginal sea acidification will be determined by multiple factors, including their connections with the open ocean and their unique physical and biogeochemical dynamics, in addition to the level of atmospheric CO2.

  9. Sedimentology and depositional environment of the Oligocene-Miocene gas-bearing succession in the Yacheng 13-1 field, South China Sea, People's Republic of China

    SciTech Connect

    Atkinson, C.D.; Bloch, S.; Scheihing, M.H. )

    1990-05-01

    The giant Yacheng 13-1 gas field, discovered in 1982, is located in the South China Sea some 70 mi south of Hainan Island. The Oligocene-Miocene reservoir succession accumulated on the shallow-dipping flank of an extensional half-graben basin. The reservoir comprises an at least 800-ft (250-m) thick clastic interval that forms part of a transgressive basin fill. Basin sedimentation commenced with localized fan deltas sourced from the underlying Mesozoic granitic-metamorphic basement and fed directly into a lacustrine environment Paleosols (gleysols, planosols, and possible podzoluvisols) and palynomorphs, together with the textural characteristics of the sediments and the common occurrence of coal, suggest a prevailing humid, but seasonal, paleoclimate and abundant vegetation. Marine transgression into the basin occurred abruptly from the southwest. An elongate marine embayment was formed, the geometry of which served to amplify prevailing tidal currents. Marine processes had a pronounced effect upon the fan deltas, which continued to supply sediment to the basin. Tidal current and wave reworking winnowed and removed much of the unstable lithic components from the sediments, resulting in increased maturity. With continued transgression the basement topography was eventually drowned and the fan delta/shoreface sequences were sealed by shelfal muds and silts. Reservoir quality is controlled by burial diagenesis superimposed on the textural and mineralogical characteristics of the sediments. Poor reservoir quality typifies the immature, poorly sorted, lacustrine, fan-delta deposits, whereas good reservoir quality is characteristic of the texturally more mature, tidally reworked, marine, fan-delta, and shoreface sediments.

  10. The formation of post-spreading volcanic ridges in the South China Sea

    NASA Astrophysics Data System (ADS)

    Zhao, Minghui; Sibuet, Jean-Claude; He, Enyuan; Tan, Pingchuan; Wang, Jian; Qiu, Xuelin

    2016-04-01

    In the South China Sea (SCS), the post-spreading magmatism (˜8-13 Ma) largely masks the previous spreading fabric. The resulting post-spreading seamounts are more numerous in the northern part than in the southern part of the East sub-basin. In the eastern part of the East sub-basin, the post-spreading volcanic ridge (PSVR) is approximately N055° oriented and follows the extinct spreading ridge (ESR). In the western part of the East sub-basin, the PSVR, called the Zhenbei-Huangyan seamounts chain, is E-W oriented and hides the ESR. Based on swath bathymetric and magnetic data, the ESR in the eastern part of the East basin is also N055° oriented and thus is oblique the E-W Zhenbei-Huangyan seamounts chain (Sibuet et al., 2016). We conducted a seismic refraction survey covering both the Zhenbei-Huangyan seamounts chain and the adjacent ESR, providing new constraints for understanding the relationship between the PSVR and the ESR. The detailed velocity structure shows that the Zhenbei-Huangyan seamounts chain was emplaced through a typical oceanic crust. The thicknesses of Zhenbei (14 km) and Huangyan seamounts (8 km) are larger than the ones of the normal oceanic crust. The correlation between crustal thicknesses and mean lower-crustal seismic velocities suggest that an asymmetric generation of seamounts in the East sub-basin where active upwelling mantle (Holbrook et al., 2001), the presence of a fertile mantle component (Korenaga et al., 2002), or buoyancy-driven decompression melting may happened (Castillo et al., 2010). Below the seamounts, the thickened lower crust is probably due to secondary magmatic intrusions and the large thickness of upper crust is possibly due to volcanic extrusions. The crustal thicknesses as well as the mean lower-crustal velocities of the Zhenbei and Huangyan seamounts are different, suggesting an independent origin for magmatic feeding. This research was granted by the Natural Science Foundation of China (91028002, 91428204

  11. Detrital zircon provenance of Silurian-Devonian and Triassic sedimentary rocks of the western Yangtze Block: Constraint for the location of South China in Gondwana supercontinent

    NASA Astrophysics Data System (ADS)

    Chen, Qiong; Sun, Min; Zhao, Guochun

    2016-04-01

    During Paleozoic even to early Mesozoic, South China, along with a series of Asia continental blocks, dispersed from the northern margin of Gondwana, drifting across the Tethys Ocean and accreting to the final assembly of Asia in Triassic, which also accepted sediments sourced from the adjoining segments of east Gondwana and itself successively. However, the exact location of South China within the east Gondwana and other Asia blocks is arguing and confusing. Detrital zircon U-Pb geochronology and Hf isotope data from Paleozoic sedimentary rocks and massive Triassic flysch sequences kept in the western margin of South China (Danba-Longmenshan regions) provide a record of the source from which they were derived, and thus being applied to constraining the distribution of basement block in paleogeographic reconstructions and the tectonic setting of the basin. Two Longmenshan Devonian sediments exhibit dominant Grenvillian ages (0.9-1.1 Ga), with mid-Neoproterozoic (730-850 Ma), Pan-African (500-680 Ma) and Neoarchean (2.4-2.5 Ga) age populations, indicative of a typical Gondwana-derived affinity, which is also recorded by the Danba Silurian sample and other Paleozoic sediments (Devonian-Cambrian) in the resting South China block, including the east Yangtze block and the Cathaysia. However, the similar age patterns are not observed in the Devonian sample of Danba region, which exhibits a different age pattern with only two significant age groups of Pan-African (440-600 Ma) and Neoproterozoic (660-994 Ma) with an apparent lack of older zircon grains (>1.0 Ga). The Triassic sandstone from Songpan-Ganze covering sequences shows a distinguished zircon age distribution with prominant mid-Neoproterozoic (649-843 Ma), mid-Paleoproterozoic (1724-1951 Ma) and subordinated Permian-Triassic (236-298 Ma), Paleozoic (375-530 Ma) ages, mainly derived by melting of old crust with few input of juvenile material. Considering provenance changes along with the temporal and variation in

  12. Seismic stratigraphy and stratigraphic modelling of the South-eastern German Molasse Basin

    SciTech Connect

    Aigner, T.; Jin, J.; Luterbacher, P.

    1995-08-01

    Although the German Molasse Basin can be regarded as a mature hydrocarbon province, no regional sequence stratigraphic analysis has been carried out so far. We have studied seismic lines and well data from the region between the Isar and Inn rivers (SE Germany) that have been generously supplied by German oil companies (DEE, BEB, Mobil, RWE-DEA and Wintershall). Initial work indicates that five major seismic sequences within three main depositional cycles are developed. The Alpine thrust belt to the south serves as the primary sediment source in the foreland basin. However, sedimentary infill mainly took place parallel to the basin axis. Our analysis suggests that the stratigraphic development of the Molasse Basin was mainly controlled by eustatic sea-level changes which caused the shoreline to shift in the W-E direction. The shifting of the depocenter axis in a N-S direction was controlled by the tectonic evolution of the thrust belt. The sea-level curve determined by seismic stratigraphy and well-derived subsidence curves have been used as input parameters for stratigraphic modelling, using the programs GeoMOD and PHIL. Basin-fill simulations with PHIL are in good agreement with the main features of the sequence stratigraphy and the distribution of the systems tracts observed in the study area. The qualitative sea-level curve for the German Molasse Basin derived from the seismostratigraphic analysis could be quantified by the stratigraphic exercises.

  13. Geomorphic Terrains and Evidence for Ancient Volcanism within Northeastern South Pole-Aitken Basin

    NASA Technical Reports Server (NTRS)

    Petro, Noah; Mest, Scott C.; Teich, Yaron

    2010-01-01

    The interior of the enigmatic South Pole-Aitken Basin has long been recognized as being compositionally distinct from its exterior. However, the source of the compositional anomaly has been subject to some debate. Is the source of the iron-enhancement due to lower-crustal/upper-mantle material being exposed at the surface, or was there some volume of ancient volcanism that covered portions of the basin interior? While several obvious mare basalt units are found within the basin and regions that appear to represent the original basin interior, there are several regions that appear to have an uncertain origin. Using a combination of Clementine and Lunar Orbiter images, several morphologic units are defined based on albedo, crater density, and surface roughness. An extensive unit of ancient mare basalt (cryptomare) is defined and, based on the number of superimposed craters, potentially represents the oldest volcanic materials within the basin. Thus, the overall iron-rich interior of the basin is not solely due to deeply derived crustal material, but is, in part due to the presence of ancient volcanic units.

  14. Hydrocarbon potential of the Lamu basin of south-east Kenya

    SciTech Connect

    Nyagah, K.; Cloeter, J.J.; Maende, A.

    1996-12-31

    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.

  15. Hydrocarbon potential of the Lamu basin of south-east Kenya

    SciTech Connect

    Nyagah, K.; Cloeter, J.J.; Maende, A. )

    1996-01-01

    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.

  16. Inter-annual variability and dynamics of cold-tongue in the South China Sea

    NASA Astrophysics Data System (ADS)

    Thompson, Bijoy; Tkalich, Pavel; Malanotte-Rizzoli, Paola

    2014-05-01

    The South China Sea (SCS) surface circulation is mainly forced by seasonally varying monsoon winds and flow through the Luzon Strait. In winter, positive wind curl (due to the northeasterly winds) in the southern half of SCS drives a cyclonic gyre. The strong western boundary current south off Vietnam on the continental slope separates the Sunda Shelf to the west and deep SCS basin to the east. The advection of cold water due to the slope current results in a unique cold tongue in Sea Surface Temperature (SST) from November to February. The inter-annual variability of cold-tongue the in the SCS is investigated on the basis of daily NCEP OISST version-2 dataset from 1982 to 2012. The evolution, growth and decay of the cold tongue during the period are addressed using the OISST and ERA-interim surface wind datasets. The formation and termination of this cold tongue has significant correlation with the El Nino phenomenon in the Pacific Ocean.

  17. Mesoscale eddies cases study at Xisha waters in the South China Sea in 2009/2010

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Zeng, Lili; Zhou, Weidong; Xie, Qiang; Cai, Shuqun; Yao, Jinglong; Wang, Dongxiao

    2015-01-01

    the observed currents at Xisha (110.3899°E, 17.1038°N) during May 2009 to May 2010, it is found that the kinetic energy has significant mesoscale variability, and each peak responds to large positive/negative ocean surface current curl caused by mesoscale eddies. Compared the kinetic energy with the wind stress work and the pressure work, it is also found that the barotropic pressure work which is mainly contributed by the sea surface height (SSH) corresponding to the mesoscale eddies behaves like the kinetic energy. The contribution of the mesoscale eddies to the kinetic energy can be up to 90% sometimes and reach deep level every time. Using the satellite altimeter data, the paths of mesoscale eddies contributing to the kinetic energy variability are traced back. In the winter half of the year, the mesoscale eddies propagating along the northern South China Sea shelf or across the basin from the west of the Philippines toward Xisha arrive at Xisha, influencing the kinetic energy. In the summer half of the year, the mesoscale eddies are mainly from the south, which were shed from the Vietnam coast current. And the cause for eddy shedding may be related to the relaxation of the Ekman transport anomalies.

  18. Deep Imaging of large scale extensional structures in the SW South China Sea

    NASA Astrophysics Data System (ADS)

    Liang, Yao; Delescluse, Matthias; Wang, Jun; Pubellier, Manuel; Chamot-Rooke, Nicolas; Qiu, Yan; Savva, Dimitri; Meresse, Florian

    2016-04-01

    The South China Sea (SCS) is the largest marginal basin in SE Asia and exhibits hundreds of kilometres of extended continental crust on both conjugate margins. The structures and processes leading to the formation of the SCS are still debated at various levels (timing, mechanisms). A joint collaboration between French and Chinese scientists led to the acquisition of coincident refraction and reflection seismic data over the SW sub-basin. In 2011, a 1000-km-long refraction line was first shot using R/V Tan Bao and 50 Ocean Bottom Seismometers (OBS). Among the results was the homogeneous thickness (~12 km) of the thinned continental crust over hundreds of kilometres and the possible large scale normal faults rooting in a ductile lower crust which could explain the relatively flat Moho. The coincident multichannel seismic (MCS) profile is now available to us. The 1000-km-long MCS line was acquired using a ~7000 cu.in. tuned airgun array and 6 to 8 km long streamers. Here we focus on a 230-km-long section of the profile to the south of the V-shaped SW oceanic basin across Spratley Islands. Multiples attenuation and high density velocity analysis are performed to obtain a detailed imaging of the sediments and crust at depth. We apply pre-stack Kirchhoff time migration and superimpose the obtained reflectivity on the refraction velocity model. The processed section includes a basin bound by a large crustal normal fault already imaged in the refraction velocity model, although no information on the basement was used to model the refraction velocities. The results validate the interpretation of the refraction velocity lateral variations and emphasize the significant vertical offsets of the large scale normal faults. Deep crustal reflectivity may give additional hints at a lower crustal ductile flow. Future work will consist in using the geometry of the MCS profiles in the refraction velocity modelling and an attempt to use more advanced migration methods with the help of

  19. Physical characteristics of stream subbasins in the Blue Earth River Basin, south-central Minnesota and north-central Iowa

    USGS Publications Warehouse

    Lorenz, D.L.; Payne, G.A.

    1992-01-01

    This report presents data describing the physical characteristics of stream basins upstream from selected points on streams in the Blue Earth River basin, located in south-central Minnesota and north-central Iowa. The physical characteristics are the drainage area of the basin, the percentage area of the basin covered only by lakes, the percentage area of the basin covered by both lakes and wetlands, the main-channel length, and the mainchannel slope. The points on the stream include outlets of subbasins of at least five square miles, outfalls of sewage treatment plants, and locations of U.S. Geological Survey gaging stations.

  20. Regional elemental abundances within South Pole-Aitken basin as measured with lunar prospector gamma-ray spectrometer data.

    SciTech Connect

    Lawrence, David J. ,; Pieters, Carlé M.; Elphic, R. C.; Gasnault, O. M.; Prettyman, T. H.; Feldman, W. C.

    2003-01-01

    South Pole-Aitken (SPA) basin has been a target of intense study since it is one of the largest impact basins in the solar system. It is thought that SPA basin excavated deep into the lunar crust and possibly even the mantle. Such conclusions have been supported by the observed mafic and thorium composition anomalies seen across the entire basin. One of the major goals of lunar and planetary science has been to measure and understand the composition of the non-mare materials within SPA basin. It is expected that this information will help to increase our understanding of the formation and differentiation processes that occurred early on the Moon.

  1. Environmental inequality: Air pollution exposures in California's South Coast Air Basin

    NASA Astrophysics Data System (ADS)

    Marshall, Julian D.

    Environmental inequality is quantified here using linear regression, based on results from a recent mobility-based exposure model for 25,064 individuals in California's South Coast Air Basin [Marshall et al., 2006. Inhalation intake of ambient air pollution in California's South Coast Air Basin. Atmospheric Environment 40, 4381-4392]. For the four primary pollutants studied (benzene, butadiene, chromium particles, and diesel particles), mean exposures are higher than average for people who are nonwhite, are from lower-income households, and live in areas with high population density. For ozone (a secondary pollutant), the reverse holds. Holding constant attributes such as population density and daily travel distance, mean exposure differences between whites and nonwhites are 16-40% among the five pollutants. These findings offer a baseline to compare against future conditions or to evaluate the impact of proposed policies.

  2. Emission estimation and multimedia fate modeling of seven steroids at the river basin scale in China.

    PubMed

    Zhang, Qian Qian; Zhao, Jian-Liang; Ying, Guang-Guo; Liu, You-Sheng; Pan, Chang-Gui

    2014-07-15

    Steroids are excreted from humans and animals and discharged with wastewaters into the environment, resulting in potential adverse effects on organisms. Based on the excretion rates from different groups of humans and animals, the emissions of seven steroids (estrone (E1), 17β-estradiol (E2), estriol (E3), testosterone (T), androsterone (A), progesterone (P), and cortisol (C)) were comprehensively estimated in 58 river basins of whole China, and their multimedia fate was simulated by using a level III fugacity multimedia model. The results showed that higher emission densities for the steroids were found in the river basins of east China than in west China. This distribution was found to be generally similar to the distribution of Gross Domestic Product (GDP) across China. E3, A, and P displayed higher emission densities than the other steroids in most of the river basins. The total excretion of steroids by humans and animals in China was estimated to be 3069 t/yr. The excretion of steroids from animals was two times larger than that from humans. After various treatments, the total emission of steroids was reduced to 2486 t/yr, of which more than 80% was discharged into the water compartment. The predicted concentrations in water were within an order of magnitude of the measured concentrations available in the literature. Owing to wastewater irrigation, more steroid mass loadings in agricultural soil were found in the basins of Haihe River and Huaihe River in comparison with the other river basins. To the best of our knowledge, this is the first report on the emissions and multimedia fate of seven steroids in the river basins of China.

  3. Spatial and temporal characteristics of the phytoplankton biomarkers in the surface water in South China Sea

    NASA Astrophysics Data System (ADS)

    Li, L.; Liu, J.; Wang, H.; Dong, L.; He, J.

    2011-12-01

    Organic biomarkers were used to investigate the modern distribution of the phytoplanktons in the South China Sea: Brassicasterol, Dinosterol, C37-Alkenone, and 1,15-C30 alkyl-Diol, which correspond to diatoms, dinoflagellates, coccolithophores, and yellow green algae, respectively. The distribution for the phytoplankton biomarks exhibit typical spatial and temporal characteristic: in summer, high biomass was found in the Pearl River Estuary and east of Hainan Island, while in spring, besides Pearl River Estuary, higher biomass was found also in Luzon strait and western Luzon Island. The decreasing tendency for the offshore sites and deep basin sites was exhibited in both seasons. The results indicated that the distribution of phytoplankton biomarkers in surface water of SCS is impacted and constrained by the hydrology condition and nutrients supply. Seasonal upwelling caused by the seasonal reversal eastern Asian monsoon in the SCS and continental riverine supply is the dominant reason for the nutrient supply, which resulted the typical features of regional distribution and seasonal variation. The community structure revealed by the lipids biomarkers indicated that diatom is the dominant species of phytoplankton in the studied area, and exhibit a decreasing trend form the near shore to the deep basin, while coccoliphore show a reverse feature with high value in the deep basin and Luzon strait, illustrating the different nutrient requirement by different marine organisms. The similar distribution of the alga and the corresponding biomarkers enhanced the feasibility of biomarker lipids in reconstructing the phytoplanktons community structure, which can be used in both the modern and past ecology study to improve our knowledge in the relationship between the marine ecology with the climate and environment change.

  4. Depths to the magnetic layer bottom in the South China Sea area and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Li, Chun-Feng; Shi, Xiaobin; Zhou, Zuyi; Li, Jiabiao; Geng, Jianhua; Chen, Bing

    2010-09-01

    The depths to the magnetic layer bottom (Zb) in the South China Sea (SCS) area are estimated by computing radially averaged amplitude spectra of total field magnetic anomalies. We test different sizes of moving windows in which the spectra are calculated to better understand how window sizes affect the depth estimations. Apart from lowering the resolutions of estimated Zb, larger windows do not necessarily incur presumable increases in Zb in the SCS area. Although the centroid method is taken as our primary technique for estimating Zb, for cross check, the spectral peak and the non-linear inversion methods are also applied to those windows where spectral peaks do appear. In a single window we may find discrepancy in Zb estimated from different techniques, but for all windows showing spectral peaks, the estimated Zb from one technique are grossly correlated with those from another. Our results show that most parts of the central SCS ocean basin and the northern continent-ocean transition (COT) zone have significantly smaller Zb than the surrounding continental blocks. In the surrounding continental regions Zb are averaged at about 34 km, a depth close to the Moho depth. The average Zb is about 22 km in the central basin, but this value is much larger than the Moho depth, signifying that the uppermost 10 km or so of the mantle beneath the central basin is also magnetized. The strong faulting and recent magmatism within the COT zone can account for the small Zb near the northern continental margin. The estimated Zb are also found very correlative to surface heat flow. This observation verifies dominant contributions to surface heat flow from incoming mantle heat flow due to thermal conduction. The positive correlations observed among Zb from different techniques as well as the good correlation between surface heat flow and Zb support the reasoning that our estimated Zb are within an acceptable range of accuracy.

  5. Stable Isotopic Constraints of the Turpan Basin in Northwestern China

    NASA Astrophysics Data System (ADS)

    Schaen, A. J.

    2010-12-01

    Stable isotopic analysis of sedimentary rocks can be used to reconstruct past geologic changes in the elevation and climate of topographic features such as mountain ranges and plateaus. The Tibetan Plateau is an ideal field laboratory for conducting this type of study because of the Plateau’s extreme topographic relief and relatively recent geologic growth. Here we present oxygen and carbon isotope compositions from a suite of sedimentary rock samples taken from the western Turpan Basin in northwestern China. This area of the basin collects sediment from weathering and erosion of the Bogda Shan located to the north. The goal of this study is to analyze changes in the stable isotope composition as a function of stratigraphic position to reconstruct paleoelevations and paleoclimates in this part of the Tibetan Plateau. The sedimentary rock samples analyzed in this study are Late Jurassic to Neogene age and are primarily mudstone, siltstone, fine sandstone along with lesser limestone. Samples were powered and then dissolved with phosphoric acid at 72οC. The liberated CO2 gas was then analyzed using a Finnigan Delta Plus XL mass spectrometer with a gasbench inlet system. Oxygen isotope values range from -13.72 to -1.62‰ (PDB) and exhibit a large scale trend to more negative values toward the top of the stratigraphic sequence. Superimposed on this large scale trend are systematic variations in isotopic composition as a function of age. The most positive δ18O values occur at approximately 160, 115, 60, and 5 ma. Conversely, δ18O minima are observed at 150, 90, and 40 ma. δ13C values range from -10.69‰ to 1.40‰ (PDB). The most positive δ13C values (-4.3 to 1.4) occur from 120-160 ma. Younger samples display small scale variations with age with notable δ13C minima of -10.7, -14.7, and -7.6‰ at 108, 80, and 17 ma, respectively. The variable δ18O and positive δ13C values from the Jurassic (145-160 ma) are consistent with an arid climate and high atmospheric

  6. South China Sea throughflow impact on the Indonesian throughflow

    NASA Astrophysics Data System (ADS)

    Gordon, Arnold L.; Huber, Bruce A.; Metzger, E. Joseph; Susanto, R. Dwi; Hurlburt, Harley E.; Adi, T. Rameyo

    2012-06-01

    In 2008-2009 the Makassar throughflow profile changed dramatically: the characteristic thermocline velocity maximum increased from 0.7 to 0.9 m/sec and shifted from 140 m to 70 m, amounting to a 47% increase in the transport of warmer water between 50 and 150 m during the boreal summer. HYCOM output indicates that ENSO induced change of the South China Sea (SCS) throughflow into the Indonesian seas is the likely cause. Increased SCS throughflow during El Niño with a commensurate increase in the southward flow of buoyant surface water through the Sulu Sea into the northern Makassar Strait, inhibits tropical Pacific surface water injection into Makassar Strait; during La Niña SCS throughflow is near zero allowing tropical Pacific inflow. The resulting warmer ITF reaches into the Indian Ocean, potentially affecting regional sea surface temperature and climate.

  7. Levels of endocrine disrupting compounds in South China Sea.

    PubMed

    Zhang, Li-Peng; Wang, Xin-Hong; Ya, Miao-Lei; Wu, Yu-Ling; Li, Yong-Yu; Zhang, Zu-lin

    2014-08-30

    The occurrence of estrogens in the aquatic environment has become a major concern worldwide because of their strong endocrine disrupting potency. In this study, concentrations of four estrogenic compounds, estrone (E1), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), estriol (E3) were determined with liquid chromatography-tandem mass spectrometry analyses in surface water from South China Sea, and distributions and potential risks of their estrogenic activity were assessed. The estrogenic compounds E1, E2 and E3 were detected in most of the samples, with their concentrations up to 11.16, 3.71 and 21.63 ng L(-1). However, EE2 was only detected in 3 samples. Causality analysis, EEQ values from chemical analysis identified E2 as the main responsible compounds. Based on the EEQ values in the surface water, high estrogenic risks were in the coastal water, and low estrogenic risks in the open sea.

  8. Directional drill keys completion of South China Sea pipeline

    SciTech Connect

    Callnon, D.; Weeks, K.

    1996-04-08

    Directional drilling laid dual 12-in. natural gas pipelines beneath a critical sea wall on Lantau Island, Hong Kong New Territories, to complete a 30-mile gas-pipeline crossing of the South China Sea. The project was part of Towngas Lantau construction for Hong Kong`s new Chek Lap Kok International Airport on the island. To avoid disturbing a newly installed sea wall at Ta Pang Po beach, NKK subcontracted parallel beach approaches to Cherrington Corp., Sacramento. Between July 11 and Aug. 2, 1995, Cherrington Corp. drilled and forward-reamed two, 20 in., 1,294-ft holes to pull back the twin pipelines. The project was completed during typhoon weather, high seas, strong currents, and logistical problems associated with operating in a remote uninhabited area. This paper reviews the design of the beach approach entries; staging and site preparations; drilling equipment used; and overall project operations.

  9. Purine alkaloids from the South China Sea gorgonian Subergorgia suberosa.

    PubMed

    Qi, Shu-Hua; Zhang, Si; Huang, Hui

    2008-04-01

    Four new purine alkaloids, namely, 6-(1'-purine-6',8'-dionyl)suberosanone ( 1), 3,9-(2-imino-1-methyl-4-imidazolidinone-5-yl)isopropenylpurine-6,8-dione ( 2), 1-(3'-carbonylbutyl)purine-6,8-dione ( 3), and 9-(3'-carbonylbutyl)purine-6,8-dione ( 4), together with three known compounds, guanosine ( 5), thymidine ( 6), and adenosine ( 7), were isolated from the EtOH/CH 2Cl 2 extracts of the South China Sea gorgonian Subergorgia suberosa. The structures of 1- 4 were determined on the basis of extensive spectroscopic analysis, including 1D and 2D NMR data. Compounds 1- 4 all showed weak cytotoxicity toward human cancer cell lines MDA-MB-231 and A435.

  10. Molecular genetic assay of mucopolysaccharidosis IVA in South China.

    PubMed

    He, Dengmin; Huang, Yonglan; Ou, Zhiying; Sheng, Huiying; Li, Sheyong; Zhao, Xiaoyuan; Li, Ru; Zheng, Jipeng; Liu, Li

    2013-12-10

    Mucopolysaccharidosis IVA (MPS IVA) is an autosomal recessive lysosomal storage disorder caused by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS). Molecular mutational analysis was performed by PCR product sequencing for fourteen exons and exon-intron boundaries of GALNS gene in 21 patients from 19 unrelated families with severe MPS IVA in South China. We identified fifteen different mutations, including 10 reported mutations (p.P125L, p.G290S, p.M318R, p.G340D, p.L366P, p.R386C, p.A392V, c.1243-1G>C, p.L440RfsX54 and p.X523E) and five novel mutations (p.N177S, p.G290R, p.F306S, p.W403_T404delinsCS, p.W520X). All five novel mutations were inherited from parents of the patients and not found in 100 normal control alleles. Three mutations, p.M318R, p.L366P and p.R386C were common, accounting for 36.8% of mutant alleles investigated. One patient homozygous of p.A392V and the other two unrelated patients homozygous of p.L366P presented classical disease course. The results show that the GALNS gene has a different mutational spectrum in South China as compared to other regions. The p.A392V and p.L366P mutations were associated with severe phenotype of MPS IVA.

  11. Analysis of the geological structure and tectonic evolution of Xingning-Jinghai sag in deep water area, northern South China Sea

    NASA Astrophysics Data System (ADS)

    Han, Xiaoying; Ren, Jianye; Lin, Zi; Yang, Linlong

    2015-04-01

    Recent years, oil and gas exploration of the Pearl River Mouth Basin in the northern margin of South China Sea continuously achieved historic breakthroughs. The Xingning-Jinghai sag, which is located in southeast of the Pearl River Mouth Basin, is a deep-water sag with a great exploration potential. Its tectonic evolution is extremely complex. It experienced Mesozoic subduction to Cenozoic intra-continental rifting background, and finally evolved into a deep-water sag of the northern continental margin of South China Sea. The geological characteristics and the tectonic evolution of Xingning-Jinghai sag was closely related to the process of formation and evolution of the passive continental margin of the northern South China Sea. It is confirmed by many geophysical data that compared with adjacent Chaoshan depression, the crustal thickness of Xingning-Jinghai sag was rapidly thinning, and it developed detachment faults with later magmatic intrusion. The development of detachment faults have dynamic significance for the spreading of the South China Sea. Based on the seismic geological interpretation of 2D seismic data in the study area, the characteristics of detachment fault and supra-detachment basin have been proposed in this study. The characteristics of the detachment fault are low angle and high ratio between heave and throw. The geometry of the detachment fault is a typical lisric shape, with the dip of fault decreasing generally from the seismic profile. The detachment basin where sediments are not deposited over a tilting hanging-wall block but onto a tectonically exhumed footwall which is different from the typical half graben basin. Seismic profiles indicate two different structural styles in the east and west part of Xingning-Jinghai sag. In the west of the sag, there developed two large detachment faults, which control their detachment basin systems and the typical H block, and the two detachment faults are dipping landward and seaward, respectively. In

  12. Mitochondrial Genetic Differentiation of Spirlin (Actinopterigii: Cyprinidae) in the South Caspian Sea basin of Iran

    PubMed Central

    Seifali, Mahvash; Arshad, Aziz; Moghaddam, Faezeh Yazdani; Esmaeili, Hamid Reza; Kiabi, Bahram H.; Daud, Siti Khalijah; Aliabadian, Mansour

    2012-01-01

    Background Knowledge about Alburnoides remains lacking relative to many other species, resulting in a lack of a systematic position and taxonomic diagnosis. Basic biological information for Alburnoides has been constructed, and it is necessary to understand further and obtain more information about this species. Its phylogenetic relationships are still debated and no molecular data have been used to study this taxon in Iran. A holistic approach for genetic methods was adopted to analyze possible spirlin population differences at selected centers in the south Caspian Sea basin of Iran. Methods The phylogenetic relationships were determined based on 774 base pairs of the mitochondrial cytochrome b gene of 32 specimens of spirlin from nine locations in the south Caspian Sea drainage basin of Iran. The nucleotide sequences were subjected to phylogenetic analysis using the neighbor-joining, maximum parsimony, maximum likelihood, and Bayesian methods. Results The mitochondrial gene tree largely supports the existence of three major clades. The western populations (clade I) may be considered as Alburnoides eichwaldii, whereas the Talar river populations (clade II) are represented as Alburnoides sp.1 and the eastern populations (clade III) may be distinct taxa of Alburnoides sp.2. Conclusion This molecular evidence supports the hypothesis that A. bipunctatus does not exist in the south Caspian Sea basin of Iran, and that the western and eastern populations are distinct taxa. PMID:22654487

  13. Ra-226 and Pb-210/Ra-226 Activity Ratio in the Northern South China Sea

    NASA Astrophysics Data System (ADS)

    Chi-Ju, L.; Yu-Chia, C.; Tsung-En, W.

    2004-05-01

    The surface water distributions and vertical profiles of Ra-226 in the northern South China Sea (SCS) have been measured. Surface water Ra-226 varies between 10 and 16 dpm/100 kg with higher values at stations adjacent to the landmass. Each Ra-226 profile shows an increase from the surface toward the bottom. Above 1000m depth Ra-226 is systematically about 5 dpm/100kg higher in the northern South China Sea than in the western North Pacific. This difference may be attributed to a strong Ra-226 source from the shelf and slope area of the SCS. Below this depth Ra-226 displays large variation within some of the profiles with lower limits being comparable to the activities of the western North Pacific but higher limits being systematically about 5 dpm/100kg higher. These high Ra-226 activities may reflect effects of the longer isolation time for the deep water in the SCS basin and strong Ra input from the underlying sediments. The Pb-210/Ra-226 activity ratio ranges between 1.4 and 2.7 in the surface water with higher activity ratio at the station closer to the Luzon Strait. The Pb-210 in excess over Ra-226 in the surface water due to atmospheric input may penetrate to a depth of about 200 to 500m. Below this depth, Pb-210/Ra-226 activity ratio ranges between 0.5 and 0.7 because Pb-210 is scavenged by settling particulates. Box model calculations within a mixed layer of 50m in the area yield a mean residence time of about 1 yr for Pb-210 if an atmospheric Pb-210 flux of 1 dpm/cm2/y is adopted. The activity ratio of about 0.5 to 0.7 in the deep water corresponds to a Pb-210 mean residence time of about 30 to 70 yrs with respect to particulate scavenging.

  14. First high-resolution near-seafloor survey of magnetic anomalies of the South China Sea

    NASA Astrophysics Data System (ADS)

    Lin, J.; Xu, X.; Li, C.; Sun, Z.; Zhu, J.; Zhou, Z.; Qiu, N.

    2013-12-01

    We successfully conducted the first high-resolution near-seafloor magnetic survey of the Central, Southwest, and Northern Central Basins of the South China Sea (SCS) during two cruises on board Chinese R/V HaiYangLiuHao in October-November 2012 and March-April 2013, respectively. Measurements of magnetic field were made along four long survey lines, including (1) a NW-SE across-isochron profile transecting the Southwest Basin and covering all ages of the oceanic crust (Line CD); (2) a N-S across-isochron profile transecting the Central Basin (Line AB); and (3) two sub-parallel NE-SW across-isochron profiles transecting the Northern Central Basin of the SCS (Lines D and E). A three-axis magnetometer was mounted on a deep-tow vehicle, flying within 0.6 km above the seafloor. The position of the tow vehicle was provided by an ultra-short baseline navigation system along Lines D and E, while was estimated using shipboard GPS along Lines AB and CD. To investigate crustal magnetization, we first removed the International Geomagnetic Reference Field (IGRF) of 2010 from the measured magnetic data, and then downward continued the resultant magnetic field data to a horizontal plane at a water depth of 4.5 km to correct for variation due to the fishing depth of the deep-tow vehicle. Finally, we calculated magnetic anomalies at various water depths after reduction-to-the-pole corrections. We also constructed polarity reversal block (PRB) models of crustal magnetization by matching peaks and troughs of the observed magnetic field anomaly. Our analysis yielded the following results: (1) The near-bottom magnetic anomaly showed peak-to-trough amplitudes of more than 2,500 nT, which are several times of the anomaly amplitudes at the sea surface, illustrating that deep-tow measurements acquired much higher spatial resolutions. (2) The deep-tow data revealed several distinctive magnetic anomalies with wavelengths of 5-15 km and amplitudes of several hundred nT. These short

  15. [Bacterial and archaeal diversity in surface sediment from the south slope of the South China Sea].

    PubMed

    Li, Tao; Wang, Peng; Wang, Pinxian

    2008-03-01

    Diversity of bacteria and archaea was studied in deep marine sediments by PCR amplification and sequence analysis of 16S rDNA. Sample analysed was from IMAGES (International Marine Past Global Change Study) 147 at site of the south slope of the South China Sea. DNA was amplified from samples at the surface layer of core MD05-2896. Phylogenetic analysis of clone libraries showed a wide variety of uncultured bacteria and archeae. The most abundant bacterial sequences (phylotypes) corresponded to the Proteobacteria, followed by the Planctomycete, Acidobacteria and candidate division OP10. Phylotypes ascribing to Deferrobacteres, Verrucomicrobia, Spirochaetes and candidate division clades of OP3, OP11, OP8 and TM6 were also identified. Archaeal 16S rDNA sequences were within phylums of Crenarchaeota and Euryarchaeota, respectively. The majority of archaeal phylotypes were Marine Benthic Group B (MBGB), Marine Crenarchaeotic Group I (MG I), Marine Benthic Group D (MBGD) and South African Gold Mine Euryarchaeotic Group (SAGMEG). Additional sequences grouped with the C3, Methanobacteriales and Novel Euryarchaeotic Group (NEG). These results indicate that bacteria and archaea are abundant and diversified in surface environment of subseafloor sediments.

  16. Typhoon emergency response planning for the South China Sea

    SciTech Connect

    Corona, E.N.; Lynch, R.D.; Riffe, D.; Cardone, V.J.; Cox, A.; Chen, H.

    1996-12-31

    This paper describes the development, implementation and performance of a comprehensive typhoon emergency response plan (ERP) utilized during 1995 by Arco China Inc. (ACI) for their offshore Hainan Is. South China Sea development. An important component of the enhanced plan is a new system to forecast winds and sea states generated by tropical cyclones (TC) built around known uncertainties in forecasts of cyclones and well proven numerical models of the TC surface wind field and the spectral wave field. The forecast system provides specification of time histories of the winds and waves at the site for the nominally predicted track as well as the probabilities of exceedance of critical evacuation thresholds of wind speed and sea state. The ERP and forecast system were operated throughout the 1995 typhoon season and evaluated at the Yacheng development, which was seriously threatened by 15 tropical cyclones between June and November. The response to these threats in terms of interruption of operations, partial or total evacuation of offshore personnel and average downtime is described and compared to previous experience which used more conventional forecast services. The evaluation has shown the new system to provide significant benefits in terms of safety, efficiency and cost savings. The wind and sea state forecast histories provided year-round by the forecast system are also of significant benefit to the management of floating production systems.

  17. Late Pennsylvanian to Wuchiapingian palynostratigraphy of the Baode section in the Ordos Basin, North China

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Zhu, Huaicheng; Ouyang, Shu

    2015-11-01

    Well-preserved miospores are recorded and illustrated from the Penchi to the lower part of the Sunjiagou formations in the Baode section of the Ordos Basin, North China. Eight palynological biozones are proposed for the Late Pennsylvanian to Wuchiapingian interval. Among them, five biozones are refined from pre-existing biozones. The biozones are comparable throughout the North China Craton. In contrast, long distance palynological correlation between North China and Euramerica only extends to the end of the Bolsovian (early Moscovian). By reference of associated marine fossils and magnetostratigraphic data, approximate stratigraphic correlation with the international stages is possible in Ordos Basin. Quantitative abundances of spores and pollen from the Late Pennsylvanian to Wuchiapingian reflect a wet-hot palaeoclimate in the Ordos Basin but with an increasing tendency of palaeoclimatic drying from the Early Kungurian. This drying tendency can be recognized throughout the North China Craton and seems to be related to the suturing process between North China Craton with the combined northeastern China blocks. Reduviasporonites which occurs often in relatively high frequencies in many Permian-Triassic boundary sections was recorded for the first time from the early Kungurian Shansiensis Biozone.

  18. Genetic features of petroleum systems in rift basins of eastern China

    USGS Publications Warehouse

    Qiang, J.; McCabe, P.J.

    1998-01-01

    Most oil-bearing basins in eastern China are Mesozoic-Cenozoic continental rifts which have played a habitat for oil and gas in China. Investigation of the petroleum systems may give a better understanding of the oil and gas habitats in these basins. Of the essential elements of the petroleum system, the source rock is the most important in rift basins. However, rift tectonic evolution controls all the essential elements and processes nevessary for a petroleum system. A four stage evolution model is suggested for the controls in the rift basin. A rift basin may consist of sub-basins, depressions, sub-depressions, and major, moderate, and minor uplifts. A depression or sub-depression has its own depocentre (mainly occupied by source rock) and all kinds of lacustrine sediments, and thus has all the essential elements of a petroleum system. However, only those depressions or sub-depressions which are rich in organic matter and deeply buried to generate oil and gas form petroleum systems. Immature oil, another characteristic, complicates the petroleum system in the rift basins. Three types of oil and gas habitats are described as a result of this analysis of the petroleum systems of the 26 largest oil and gas fields discovered in eastern China rift basins: uplifts between oil source centres are the most prospective areas for oil and gas accumulations, slopes connecting oil source centres and uplifts are the second, and the third type is subtle traps in the soil source centre.Most oil-bearing basins in eastern China are Mesozoic-Cenozoic continental rifts which have played a habitat for oil and gas in China. Investigation of the petroleum systems may give a better understanding of the oil and gas habitats in these basins. Of the essential elements of the petroleum system, the source rock is the most important in rift basins. However, rift tectonic evolution controls all the essential elements and processes necessary for a petroleum system. A four stage evolution model

  19. The Han River watershed management initiative for the South-to-North Water Transfer project (Middle Route) of China.

    PubMed

    Zhang, Quanfa; Xu, Zhifang; Shen, Zehao; Li, Siyue; Wang, Shusen

    2009-01-01

    The South-to-North Water Transfer (SNWT) Project of China is the largest of its kind ever implemented. Of its three routes (i.e., East, Middle and West), the middle one will transfer 14 billion m(3) of water annually from the Han River, a tributary of the Yangtze and the water supplying area, to Beijing by 2030. Thus water quality in the 95,000 km(2) upper Han River basin is of great concern. A watershed management initiative has been implemented in the basin, and the ultimate objectives are to quantify basin's ecosystem functioning and to develop an integrated management system with respect to water resources conservation. Specifically, the program includes five activities: characterization of riparian ecosystems, detection of land use and land cover change, quantification of nutrient cycling of representative ecosystems, determination of spatial and temporal variations of water quality, and finally development of a watershed management system for water conservation. This article provides the justifications of the watershed management initiative and the initial results are comprehended with respect to the water conservation in the Han River basin.

  20. Volume of Impact Melt Generated by the Formation of the South Pole-Aitken Basin

    NASA Technical Reports Server (NTRS)

    Petro, Noah E.

    2011-01-01

    The South Pole-Aitken Basin (SPA) is the largest, deepest, and oldest identified basin on the Moon and as such contains surfaces that are unique due to their age, composition, and depth of origin in the lunar crust [1-5] (Figure 1). SPA has been a target of intense interest as an area for robotic sample return in order to determine the age of the basin and the composition and origin of its interior [6-8]. In response to this interest there have been several efforts to estimate the likely provenance of regolith material within central SPA [9-12]. These model estimates suggest that, despite the formation of basins and craters following SPA, the regolith within SPA is dominated by locally derived material. An assumption of these models has been that the locally derived material is primarily SPA impact-melt as opposed to local basement material (e.g. unmelted lower crust). However, the definitive identification of SPA derived impact melt on the basin floor, either by remote sensing [5, 13] or via photogeology [2, 14] is extremely difficult due to the number of subsequent impacts and volcanic activity [4].

  1. Benthic infaunal communities across the Weddell Sea Basin and South Sandwich Slope, Antarctica

    NASA Astrophysics Data System (ADS)

    Blake, James A.; Narayanaswamy, Bhavani E.

    2004-07-01

    The present study represents the first quantitative investigation of deep-sea benthic infauna in Antarctica. Box cores and multicores were used to collect sediment from 12 stations across the slope and abyssal basin of the Weddell Sea and the slope off the South Sandwich Islands, including sites in the South Sandwich Trench (6300 m). The multicore was a more efficient sampler than the box core. Nine phyla of invertebrates were found, dominated by annelids (67%), crustaceans (20%); other phyla (13%). A total of 117 taxa were identified to the species level: 72 were polychaetes; 45 were crustaceans. Many taxa are new to science. Highest densities were at the 1000 m depth on the western slope of the Weddell Sea (260 individuals per 0.1 m -2) and at ca. 2200 m on the South Sandwich Slope (132 individuals per 0.1 m -2); lowest densities were in the central Weddell Sea Basin (39 individuals per 0.1 m -2). Species richness and rarefaction analysis suggest that the fauna is undersampled. The 117 species identified in this study were represented by only 237 specimens, indicating that species were being added at a rate of one species for every two specimens collected. Rarefaction curves do not begin to reach an asymptote supporting high estimates of diversity. Some species appear to be limited to distinct zones in upper and middle slope depths, other species extend from the slope to the abyssal basin, and at least two species appear to be restricted to the abyssal basin. In general, the densities of infauna on the slopes surrounding the Weddell Sea Basin have lower densities than well-studied areas off North America. However, abyssal populations in Antarctica appear to have denser infaunal populations than those from off New England and the North Pacific Gyre. Productive surface waters of the Weddell Sea and subsequent sinking of phytoplankton to the seabed are probable reasons for the higher benthic productivity in Antarctic abyssal sediments. Similarity analyses were not

  2. Ground-water quality in alluvial basins that have minimal urban development, south-central Arizona

    USGS Publications Warehouse

    Gellenbeck, Dorinda J.; Coes, Alissa L.

    1999-01-01

    Ground-water quality data (1917-96) from 772 wells in 16 alluvial basins that have minimal urban development were used to determine the effect of nonurban factors on ground-water quality in south- central Arizona. Characterization of the spatial variability of ground-water quality within and among alluvial basins that have minimal urban development will provide a baseline to which water- quality problems associated with urbanization can be compared. Four water-type categories--calcium carbonate, calcium mixed anion, sodium carbonate, and sodium chloride--were used to classify the 13 alluvial basins for which adequate data were available. Ground-water quality was compared to U.S. Environmental Protaection Agency maximum contaminant levels for drinking water, depth of well, and depth to top of perforated interval for five alluvial basins that represented the four water-type categories. Exceedances of maximum contaminant levels for fluoride and nitrate occurred in three and four basins, respectively, of the five selected basins. Specific-conductance values for ground water in the five selected basins tend to increase in a northwesterly direction toward the central part of Arizona as the extent of evaporite deposits increases. The results of this study, which are part of the U.S. Geological Survey's National Water-Quality Assessment Program, can be used to determine the effects of urban land-use activities on ground-water quality in similar hydrogeologic conditions and may be the best indicator available for nonurban ground-water quality in the region.

  3. [Health assessment of river ecosystem in Haihe River Basin, China].

    PubMed

    Hao, Li-Xia; Sun, Ran-Hao; Chen, Li-Ding

    2014-10-01

    With the development of economy, the health of river ecosystem is severely threatened because of the increasing effects of human activities on river ecosystem. In this paper, the authors assessed the river ecosystem health in aspects of chemical integrity and biological integrity, using the criterion in water quality, nutrient, and benthic macroinvertebrates of 73 samples in Haihe River Basin. The research showed that the health condition of river ecosystem in Haihe River Basin was bad overall since the health situation of 72. 6% of the samples was "extremely bad". At the same time, the health situation in Haihe River Basin exhibited obvious regional gathering effect. We also found that the river water quality was closely related to human activities, and the eutrophication trend of water body was evident in Haihe River Basin. The biodiversity of the benthic animal was low and lack of clean species in the basin. The indicators such as ammonia nitrogen, total nitrogen and total phosphorus were the key factors that affected the river ecosystem health in Haihe River Basin, so the government should start to curb the deterioration of river ecosystem health by controlling these nutrients indicators. For river ecosystem health assessment, the multi-factors comprehensive evaluation method was superior to single-factor method.

  4. Seasonal variations in the barrier layer in the South China Sea: characteristics, mechanisms and impact of warming

    NASA Astrophysics Data System (ADS)

    Zeng, Lili; Wang, Dongxiao

    2016-06-01

    A new observational dataset, the South China Sea Physical Oceanographic Dataset 2014, is examined to investigate the seasonal characteristics, formation mechanisms, and warming effects of the barrier layer (BL) in the South China Sea (SCS). Statistical analysis reveals that the BL is thicker and occurs more frequently during summer and early autumn, while in winter it often coexists with temperature inversions. The formation mechanisms are discussed from the perspective of the controlling regime and the net turbulent energy required for BL evolution. In the initial stage (March-May), the BL is absent due to weak mixing, scarce rainfall and surface warming. In the formation and maintenance stage (June-September), the BL grows in summer and persists into the transition season. The BLs can be classified into three regimes: the flux regime (in the Luzon Strait), the combined regime (in the eastern basin) and the wind regime (southeast of Vietnam). In the attenuation stage (October-February), associated with the winter monsoon, the BL mainly occurs in the combined regime (along the path of western boundary current) and the flux regime (in the southeast corner). The characteristics and generation mechanisms of the temperature inversions near the south Chinese coast, east of Vietnam, and in the Gulf of Thailand are also discussed. Our analysis further demonstrates that the BL has a significant warming effect on upper ocean temperature and heat content in the SCS.

  5. A magnetostratigraphic time frame for Plio-Pleistocene transgressions in the South Caspian Basin, Azerbaijan

    NASA Astrophysics Data System (ADS)

    Van Baak, C. G. C.; Vasiliev, I.; Stoica, M.; Kuiper, K. F.; Forte, A. M.; Aliyeva, E.; Krijgsman, W.

    2013-04-01

    The isolation of the Caspian Sea took place in the latest Miocene coinciding with a significant lowering of sea level and the deposition of a massive lowstand deltaic system. This so-called Productive Series is the main reservoir unit of the South Caspian oil-province. The Productive Series is overlain by marine clays from the Akchagylian and Apsheronian regional stages. During the Plio-Pleistocene, the Caspian basin experienced several short periods of intermittent connectivity with other marine basins. This work aims to create integrated, high-resolution, bio-magnetostratigraphic dating of these regional transgressions in key sections of the South Caspian Basin in Azerbaijan. We sample two long sections, the Lokbatan section in the Palaeo-Volga delta and the Xocashen section in the Kura Basin. Palaeoenvironmental reconstructions are derived from characteristic ostracod species. Rock magnetic analyses combined with thermal demagnetisation data indicate that the magnetic signal is carried dominantly by the iron oxide magnetite in the Productive Series of Lokbatan section and in the Xocashen section. The marine Akchagylian and Apsheronian of Lokbatan are characterised by the iron sulphide greigite, which appears to be of (near-) primary origin. The most logical correlation of the magnetic polarity patterns to the Geomagnetic Polarity Time Scale dates the Akchagylian transgression at ~ 3.2 Ma, a major transgression during the Apsheronian at ~ 2.0 Ma and the Bakunian transgression at 0.85-0.89 Ma. Ostracod assemblages indicate increasing salinities during these transgressions, from fresh water lacustrine to brackish-marine species. This implies that marine connections have been created with an adjacent basin that has a higher salinity, most likely the Black Sea.

  6. Nutrient concentrations in wastewater treatment plant effluents, South Platte River Basin

    USGS Publications Warehouse

    Pocernich, M.; Litke, D.W.

    1997-01-01

    Accurate data about nutrient concentrations in wastewater treatment plant effluents are needed for river basin water-quality studies. As part of the U.S. Geological Survey's National Water-Quality Assessment Program in the South Platte River Basin, nutrient data were requested from 31 wastewater-treatment plants located in the basin. This article describes the types of nutrient data available from the plants, examines the variability of effluent nutrient concentrations, and discusses methods for estimation of nutrient concentrations where data are lacking. Ammonia was monitored at 88 percent of the plants, nitrite plus nitrate was monitored at 40 percent of the plants, and organic nitrogen and phosphorus were monitored at less than 25 percent of the plants. Median total nitrogen concentrations and median total phosphorus concentrations were small compared to typical literature estimates for wastewater-treatment plants with secondary treatment. Nutrient concentrations in effluent from wastewater-treatment plants varied widely between and within plants. For example, ammonia concentrations varied as much as 5 mg/L during a day, as much as 10 mg/L from day to day, and as much as 30 mg/L from summer to winter within a plant. In the South Platte River Basin, estimates of median annual ammonia and nitrite plus nitrate concentrations can be improved based on plant processes; and nitrite plus nitrate and organic nitrogen concentrations can be estimated based on ammonia concentrations. However, to avoid large estimation errors, mere complete nutrient data from wastewater-treatment plants are needed for integration into river basin water quality studies. The paucity of data hinders attempts to evaluate the relative importance of point source and nonpoint source nutrient loadings to rivers.

  7. Managing water resources for sustainable development: the case of integrated river basin management in China.

    PubMed

    Song, X; Ravesteijn, W; Frostell, B; Wennersten, R

    2010-01-01

    The emerging water crisis in China shows that the current institutional frameworks and policies with regard to water resources management are incapable of achieving an effective and satisfactory situation that includes Integrated River Basin Management (IRBM). This paper analyses this framework and related policies, examines their deficiencies in relation to all water stress problems and explores alternatives focusing on river basins. Water resources management reforms in modern China are reviewed and the main problems involved in transforming the current river management system into an IRBM-based system are analysed. The Huai River basin is used as an example of current river basin management, with quantitative data serving to show the scale and scope of the problems in the country as a whole. The institutional reforms required are discussed and a conceptual institutional framework is proposed to facilitate the implementation of IRBM in China. In particular, the roles, power and responsibilities of River Basin Commissions (RBCs) should be legally strengthened; the functions of supervising, decision-making and execution should be separated; and cross-sectoral legislation, institutional coordination and public participation at all levels should be promoted.

  8. East China plains: a "basin" of ozone pollution.

    PubMed

    Zhao, Chun; Wang, Yuhang; Zeng, Tao

    2009-03-15

    Economic growth and associated pollution emissions in China are concentrated over three connected plains to the east In this work, we analyze an episode of highly elevated ozone over East China on June 9-14, 2004, using a 3-D chemical transport model. During this episode, the East China plains were under a high-pressure system, which suppressed the ventilation of pollutants from the boundary layer. Simulated ozone concentrations over a major fraction of East China reached high levels, all the way down to the Pearl River Delta region in the southern border. The convergence of pollutant emissions and population over the vast stretch of the geographically flat plains of East China makes the region susceptible to high-ozone exposure. During this episode, the high-03 region extended over an area >1 million km2, which hosts a population of >800 million people. Model results indicate that controlling anthropogenic NOx emissions effectively reduces the area with high-ozone exposure.

  9. Assessment of undiscovered continuous gas resources of the Ordos Basin Province, China, 2015

    USGS Publications Warehouse

    Charpentier, Ronald R.; Klett, Timothy R.; Schenk, Christopher J.; Brownfield, Michael E.; Gaswirth, Stephanie B.; Le, Phuong A.; Leathers-Miller, Heidi M.; Marra, Kristen R.; Mercier, Tracey J.

    2016-01-11

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean resources of 28 trillion cubic feet of tight gas and 5.6 trillion cubic feet of coalbed gas in upper Paleozoic rocks in the Ordos Basin Province, China.

  10. Detrital zircon provenance of the Late Triassic Songpan-Ganzi complex: Sedimentary record of collision of the North and South China blocks

    USGS Publications Warehouse

    Weislogel, A.L.; Graham, S.A.; Chang, E.Z.; Wooden, J.L.; Gehrels, G.E.; Yang, H.

    2006-01-01

    Using detrital zircon geochronology, turbidite deposystems fed from distinct sediment sources can be distinguished within the Songpan-Ganzi complex, a collapsed Middle to Late Triassic turbidite basin of central China. A southern Songpan-Ganzi deposystem initially was sourced solely by erosion of the Qinling-Dabie orogen during early Late Triassic time, then by Qinling-Dabie orogen, North China block, and South China block sources during middle to late Late Triassic time. A northern Songpan-Ganzi system was sourced by erosion of the Qinling-Dabie orogen and the North China block throughout its deposition. These separate deposystems were later tectonically amalgamated to form one complex and then uplifted as the eastern Tibet Plateau. ?? 2006 Geological Society of America.

  11. Magnitude, frequency and timing of floods in the Tarim River basin, China: Changes, causes and implications

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Gu, Xihui; Singh, Vijay P.; Sun, Peng; Chen, Xiaohong; Kong, Dongdong

    2016-04-01

    The flood magnitude, frequency and timing were analyzed using daily flow data for a period of 1950-2007 from 8 stations in the Tarim River basin, a typical arid inland river basin in China. The causes for flood occurrences were investigated using daily meteorological data. Results indicated that precipitation and temperature were increasing persistently since the 1980s and significant increases in precipitation and temperature were observed after the 1990s. As a result, floods amplified at annual and seasonal time scales in most tributary basins after the 1980s. The floods in the basin are mainly attributed to rainstorms and melting of glaciers and snowpack, and rainstorm-induced floods and temperature-induced floods were dominant in the basin. Extreme floods, such as the three largest recorded floods and floods with return periods > 10 years occurred mainly after the 1990s, with significant increase in flood-induced crop and livestock losses. It was found that heavy floods in many tributary basins often occurred about the same time. The Tarim River basin is a typical arid inland river basin in a high altitude zone and amplifying floods in recent decades, particularly after 1990s, is arousing considerable concern for mitigation of flood hazards. Results of this study shed light on hydrological response of arid regions to warming climate at higher latitudes in the northern hemisphere.

  12. Seismic attribute analysis to enhance detection of thin gold-bearing reefs: South Deep gold mine, Witwatersrand basin, South Africa

    NASA Astrophysics Data System (ADS)

    Manzi, M. S. D.; Hein, K. A. A.; Durrheim, R.; King, N.

    2013-11-01

    The gold-bearing Upper Elsburg Reef clastic wedge (UER) in the South Deep gold mine in the Witwatersrand basin (South Africa) hosts the highly auriferous basal conglomerate known as the Elsburg Conglomerate (EC) reef. The reef is less than 20 m thick and together with quartzite and conglomerate beds in the UER (1-120 m thick) is below the seismic tuning thickness, or the dominant quarter wavelength. They are extremely difficult to identify on migrated seismic sections using traditional amplitude interpretations. In order to enhance the detection of the EC reef and its subcrop position against the overlying Ventersdorp Contact Reef (VCR), complex-trace seismic attributes, or instantaneous attributes and volume attribute analysis were applied on prestack time migrated (PSTM) seismic sections. In particular, the instantaneous phase and paraphase allowed the clear identification of the continuity of the EC reef, and overlapping and interfering wavelets produced by the convergence of VCR and the EC reef. In addition, these attributes increased confidence in the interpretation of the EC, in particular its offsets (faults), and its depth. A high correlation between the seismically determined depth of the EC reef and borehole intersections was observed, with several depth discrepancies below the vertical seismic resolution limit (~ 25 m). This information can now be incorporated into the current mine geological model, thus improving the resource evaluation of the Upper Elsburg Reef in the South Deep gold mine.

  13. Prime, poor quality seen for prospects in Tarim basin of China

    SciTech Connect

    Not Available

    1993-10-18

    China's first Tarim basin oil and gas tender includes an unusual mix of prime and poor prospects, a U.S. geological and engineering company has found. Of five Tarim basin blocks offered by China National Petroleum Co. (CNPC) in a bidding round that began last Mar. 1, (1992) Gustavson Associates Inc., Boulder, Colo., Rates the geological characteristics of the most prospective tract as variable but generally positive. Gustavson said another block is mediocre but probably will attract bidders, while the remaining three tracts should be considered very high risk. Those findings appear in a nonexclusive study of the basin by John Weiner, Gustavson's chief geologist, based mainly on public data. The paper discusses the reliability of the data, geologic indicators, and describes geologic traps and seals.

  14. Sediment dispersal system in the Taiwan-South China Sea collision zone along a convergent margin: A comparison with the Papua New Guinea collision zone of the western Solomon Sea

    NASA Astrophysics Data System (ADS)

    Hsiung, Kan-Hsi; Yu, Ho-Shing

    2013-01-01

    Through a large-scale examination of the morpho-sedimentary features on sea floors in the Taiwan-Luzon convergent margin, we determined the main sediment dispersal system which stretches from 23°N to 20°N and displays as an aligned linear sediment pathway, consisting of the Penghu Canyon, the deep-sea Penghu Channel and northern Manila Trench. The seafloor of South China Sea north of 21°N are underlain by a triangle-shaped collision marine basin, resulting from oblique collision between the Luzon Arc and Chinese margin, and are mainly occupied by two juxtaposed slopes, the South China Sea and Kaoping Slopes, and a southward tilting basin axis located along the Penghu Canyon. Two major tributary canyons of the Formosa and Kaoping and small channels and gullies on both slopes join into the axial Penghu Canyon and form a dendritic canyon drainage system in this collision marine basin. The canyon drainage system is characteristic of lateral sediment supply from flank slopes and axial sediment transport down-canyon following the tilting basin axis. The significance of the collision marine basin in term of source to sink is that sediments derived from nearby orogen and continental margins are transported to and accumulated in the collision basin, serving as a temporary sediment sink and major marine transport route along the basin axis. The comparison of the Taiwan-South China Sea collision zone with the Papua New Guinea collision zone of the western Solomon Sea reveals remarkable similarities in tectonic settings and sedimentary processes that have resulted in similar sediment dispersal systems consisting of (1) a canyon drainage network mainly in the collision basin and (2) a longitudinal sediment transport system comprising a linear connection of submarine canyon, deep-sea channel and oceanic trench beyond the collision marine basin.

  15. Crustal structure across the Xisha Trough, northwestern South China Sea

    NASA Astrophysics Data System (ADS)

    Qiu, Xuelin; Ye, Sanyu; Wu, Shimin; Shi, Xiaobin; Zhou, Di; Xia, Kanyuan; Flueh, Ernst R.

    2001-11-01

    Located at the northwestern part of the South China Sea (SCS) between the Hainan and Xisha (Paracel) Islands, the Xisha Trough represents a failed rift in conjunction with the opening of the SCS between 32 and 17 Ma. From west towards east within a scale of several hundred kilometers, it presents all major stages of the rifting process, and thus, provides an ideal place to study the rifting process in great details. In the autumn of 1996, a joint team of Sino-German scientists carried out a wide-angle seismic experiment across the Xisha Trough with 10 ocean bottom hydrophones (OBH) along a 237-km NNW-SSE-oriented profile, which was surveyed in 1987 with multi-channel seismic (MCS) method by BGR of Germany and SOA of China. Favorable weather conditions and the powerful 4×12-l air gun array rendered very good quality data with seismic signals observed at the offset of up to 110 km. A detailed velocity-depth model was obtained by using an interactive trial-and-error 2D ray-tracing method. Interpretation of the MCS data published by BGR provides very good geometrical constraints of the complex upper crustal structure, which is characterized by fault blocks, half-horsts and half-grabens filled with syn- and post-rift Cenozoic sediments. The velocity model in turn confirms the major structure outlined by the interpretation of the MCS data, showing a varying sedimentary layer between 1 and 4 km of thickness and velocities between 1.7 and 4.5 km/s. The P-wave velocity of 5.5 km/s on the top of the crystalline basement is relatively low, suggesting strong weathering. Within the crystalline crust, the velocity increases downward continuously to 6.8 km/s at the bottom of the crust without a clear differentiation in the middle crust, showing clearly its continental nature even beneath the Xisha Trough. The Moho is marked by a sharp first-order interface with a velocity of 8.0-8.1 km/s at the uppermost mantle. The Moho depth is 15 km beneath the center of the trough and

  16. Imaging lithospheric structure in northern Scotland and the South Caspian Basin

    NASA Astrophysics Data System (ADS)

    Asencio, Eugenio

    Passive- and active-source seismological studies of northern Scotland and the South Caspian Basin indicate: (1) pervasive and laterally heterogeneous velocity discontinuities within the upper mantle influenced by the localized tectonic and thermal history of northwest Scotland, and (2) growth fault-bend folds overriding a regional ductile detachment zone at a depth of about 13 to 16 km in response to a component of right-lateral simple shear of the underlying crust between the South Caspian Basin and the central and western Caucasus. Teleseismic earthquakes recorded by a small array of portable broadband stations and permanent short-period stations are used to ascertain the lateral extent of velocity discontinuities within the continental mantle lithosphere beneath Scotland. Radial receiver functions contain distinct P-to-S ( Ps) converted phases at about 3.1--3.2 s and at 4.5--5.2 s after the direct P-wave. These observations suggest that the upper mantle Ps phase originates from a high velocity and/or anisotropic layer within the upper mantle. At two stations, ORE and BACA, located along the northern shoreline of Scotland, these upper mantle phases can be correlated with the W-reflector, a bright, regionally extensive seismic reflector previously observed on marine deep seismic reflection and wide-angle refraction-reflection profiles. However, the variability in physical characteristics suggests the possibility that there may be multiple layered reflectors in the upper mantle beneath northern Scotland and revives debates on the regional and global significance of upper mantle layering. Deep seismic reflection profiles acquired in the deepwater of the South Caspian Sea, offshore Azerbaijan image a thick sequence of sediments (19--22 km thick) that structurally have been deformed into relatively symmetrical folds. These structures are interpreted as fault-bend growth folds overriding a regional ductile detachment zone at a depth of about 13 to 16 km. The analysis

  17. Basin-scale emission and multimedia fate of triclosan in whole China.

    PubMed

    Zhang, Qian-Qian; Ying, Guang-Guo; Chen, Zhi-Feng; Zhao, Jian-Liang; Liu, You-Sheng

    2015-07-01

    This study aimed to investigate the emission and multimedia fate as well as potential risks of triclosan (TCS) in all of 58 basins in China. The results showed that the total usage of TCS in whole China was 100 t/year, and the discharge to the receiving environment was estimated to be 66.1 t/year. The predicted TCS concentrations by the level III fugacity model were within an order of magnitude of the reported measured concentrations. TCS (90.8%) was discharged into the water compartment and 9.2% to the soil compartment. The TCS concentration levels in east China were found generally higher than in west China. In addition, the input flux for TCS to seawater was largely attributed to the seasonal variations in advection flows. Preliminary risk assessment showed that medium to high ecological risks for TCS would be expected in the eastern part of China due to the high population density.

  18. An observational analysis of a derecho in South China

    NASA Astrophysics Data System (ADS)

    Xia, Rudi; Wang, Donghai; Sun, Jianhua; Wang, Gaili; Xia, Guancong

    2012-12-01

    Derechos occur frequently in Europe and the United States, but reports of derechos in China are scarce. In this paper, radar, satellite, and surface observation data are used to analyze a derecho event in South China on 17 April 2011. A derecho-producing mesoscale convective system formed in an environment with medium convective available energy, strong vertical wind shear, and a dry layer in the middle troposphere, and progressed southward in tandem with a front and a surface wind convergence line. The windstorm can be divided into two stages according to differences in the characteristics of the radar echo and the causes of the gale. One stage was a supercell stage, in which the sinking rear inflow of a high-precipitation supercell with a bow-shaped radar echo induced a Fujita F0 class gale. The other stage was a non-supercell stage (the echo was sequentially kidney-shaped, foot-shaped, and an ordinary single cell), in which downbursts induced a gale in Fujita F1 class. This derecho event had many similarities with derechos observed in western countries. For example, the windstorm was perpendicular to the mean flow, the gale was located in the bulging portion of the bow echo, and the derecho moved southward along with the surface front. Some differences were observed as well. The synoptic-scale forcing was weak in the absence of an advancing high-amplitude midlevel trough and an accompanying strong surface cyclone; however, the vertical wind shear was very strong, a characteristic typical of derechos associated with strong synoptic-scale forcing. Extremely high values of convective available potential energy and downdraft convective available potential energy have previously been considered necessary to the formation of weak-forcing archetype and hybrid derechos; however, these values were much less than 2000 J during this derecho event.

  19. A classification of Meso-Cenozoic continental basins and their oil-gas potentials in China

    SciTech Connect

    Wu Changlin ); Xue Shuhao )

    1991-03-01

    Most of the oilfields in China are located in Mesozoic-Cenozoic continental basins. Characteristics of continental sediments are controlled by such factors as paleoclimatic zones, distance from oceans, paleogeomorphic features, and tectonic settings. Based on paleoclimatic zonation, the continental basins in China can be divided into humid, arid, and humid-arid transitional types. Furthermore, based on the distances from oceans, they can be classified into inland and onshore types, and based on regional geomorphic features, they can be classified into faulted and depressional types. According to three factors, the Mesozoic-Cenozoic continental petroliferous basins in China can be grouped under ten types as follows: (1) onshore humid faulted type such as Zhujiangkou (Pearl River Mouth; E); (2) onshore humid depressional type such as Songliao (K); (3) inland humid faulted type such as Baise (E); (4) inland humid depressional type such as Ordos (T); (5) onshore arid-humid faulted type such as Bohai Bay (E); (6) inland arid-humid faulted type such as Jiuxi (K); (7) inland arid-humid depressional type such as Junggar (E); (8) onshore arid depressional type such as Tarim (E); (9) inland arid faulted type such as Jianghan (E); and (10) inland arid depressional type such as Tsaidam (E-N). Sedimentary systems in different basins have different depositional characteristics and petroliferous potentials. Onshore basins in humid zone and arid-humid transitional zone have best petroleum prospects, and inland basins in humid and arid-humid transitional zones are second while the basins in arid zone are third.

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

    NASA Astrophysics Data System (ADS)

    Smith, R. M. H.

    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

  1. Techniques for estimating the magnitude and frequency of floods in rural basins of South Carolina, 1999

    USGS Publications Warehouse

    Feaster, Toby D.; Tasker, Gary D.

    2002-01-01

    Data from 167 streamflow-gaging stations in or near South Carolina with 10 or more years of record through September 30, 1999, were used to develop two methods for estimating the magnitude and frequency of floods in South Carolina for rural ungaged basins that are not significantly affected by regulation. Flood frequency estimates for 54 gaged sites in South Carolina were computed by fitting the water-year peak flows for each site to a log-Pearson Type III distribution. As part of the computation of flood-frequency estimates for gaged sites, new values for generalized skew coefficients were developed. Flood-frequency analyses also were made for gaging stations that drain basins from more than one physiographic province. The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, updated these data from previous flood-frequency reports to aid officials who are active in floodplain management as well as those who design bridges, culverts, and levees, or other structures near streams where flooding is likely to occur. Regional regression analysis, using generalized least squares regression, was used to develop a set of predictive equations that can be used to estimate the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence-interval flows for rural ungaged basins in the Blue Ridge, Piedmont, upper Coastal Plain, and lower Coastal Plain physiographic provinces of South Carolina. The predictive equations are all functions of drainage area. Average errors of prediction for these regression equations ranged from -16 to 19 percent for the 2-year recurrence-interval flow in the upper Coastal Plain to -34 to 52 percent for the 500-year recurrence interval flow in the lower Coastal Plain. A region-of-influence method also was developed that interactively estimates recurrence- interval flows for rural ungaged basins in the Blue Ridge of South Carolina. The region-of-influence method uses regression techniques to develop a unique

  2. Assessment of unconvential (tight) gas resources in Upper Cook Inlet Basin, South-central Alaska

    USGS Publications Warehouse

    Schenk, Christopher J.; Nelson, Philip H.; Klett, Timothy R.; Le, Phuong A.; Anderson, Christopher P.; Schenk, Christopher J.

    2015-01-01

    A geologic model was developed for the assessment of potential Mesozoic tight-gas resources in the deep, central part of upper Cook Inlet Basin, south-central Alaska. The basic premise of the geologic model is that organic-bearing marine shales of the Middle Jurassic Tuxedni Group achieved adequate thermal maturity for oil and gas generation in the central part of the basin largely due to several kilometers of Paleogene and Neogene burial. In this model, hydrocarbons generated in Tuxedni source rocks resulted in overpressure, causing fracturing and local migration of oil and possibly gas into low-permeability sandstone and siltstone reservoirs in the Jurassic Tuxedni Group and Chinitna and Naknek Formations. Oil that was generated either remained in the source rock and subsequently was cracked to gas which then migrated into low-permeability reservoirs, or oil initially migrated into adjacent low-permeability reservoirs, where it subsequently cracked to gas as adequate thermal maturation was reached in the central part of the basin. Geologic uncertainty exists on the (1) presence of adequate marine source rocks, (2) degree and timing of thermal maturation, generation, and expulsion, (3) migration of hydrocarbons into low-permeability reservoirs, and (4) preservation of this petroleum system. Given these uncertainties and using known U.S. tight gas reservoirs as geologic and production analogs, a mean volume of 0.64 trillion cubic feet of gas was assessed in the basin-center tight-gas system that is postulated to exist in Mesozoic rocks of the upper Cook Inlet Basin. This assessment of Mesozoic basin-center tight gas does not include potential gas accumulations in Cenozoic low-permeability reservoirs.

  3. Comparison of modern pollen distribution between northern and southern South China Sea

    NASA Astrophysics Data System (ADS)

    Luo, C.; Chen, M.; Xiang, R.; Liu, J.; Zhang, L.; Lu, J.

    2013-12-01

    To understand pollen transport mechanic and terrigenous area is the base to explain pollen data correctly in Southern South China Sea (Fig.1). Based on Palynology analyzing the following preliminary conclusions are listed. 1. Air pollen differences between northern and southern South China Sea 15 air pollen samples were collected from northern part of the South China Sea from August to September 2011. 13 air pollen samples were collected from southern South China Sea in December 2011. It was found that the air pollen are different between northern and southern part of South China Sea: the pollen types in the north are more abundant than in the south, Ulmaceae, Monolete spore, Cyperaceae, Euphorbiaceae, Rubiaceae, Artemisia, Chenopodiaceae, Rosaceae, Labiatae occur only in the north, they do not occur or is just sporadic in the south. The total pollen number and concentration in the north is 10 times of the south, one of the reasons may be that the sampling season in the north is autumn with more flowering plants, the sampling season in the south is winter, with fewer flowering plants; the second reason might be that pollen and spore in autumn and winter are mainly spread by the winter wind, thus they reduce from north to south. 2. Pollen differences of the surface sediments between northern and southern South China Sea 14 samples were collected from surface sediments in the northern part of the South China Sea from August to October, 2011. 12 samples were collected from surface sediments in the southern part of the South China Sea from year 1997 to 2002. The differences of pollen characteristics from the surface sediments between northern and southern part of South China Sea are: pollen types and quantities in the north are richer than in south. There are Trilete spores (35-100%), Pinus (3-65%) in northern of SCS, with pollen concentration of 33-1031grain/g. There are only a small amount of Trilete-spore and Pinus pollen in southern of SCS. Pollen concentration in

  4. Isolation, molecular characterization, and phylogenetic analysis of encephalomyocarditis virus from South China tigers in China.

    PubMed

    Liu, Huimin; Yan, Qi; Zhao, Bo; Luo, Jing; Wang, Chengmin; Du, Yingchun; Yan, Jing; He, Hongxuan

    2013-10-01

    Although encephalomyocarditis virus (EMCV) can infect many host species and cause myocarditis and sudden death in many species, little is known about EMCV infection in tigers. A virus was isolated from organs of dead South China tigers with sudden death in southern China. The production of cytopathic effect on BHK cells, and the results of PCR, electron microscopy (EM), and whole genome sequencing indicated that the pathogen was EMCV, the strain was named FJ13. Other pathogenic agents were excluded as possible pathogenic agents. Phylogenetic analyses of the whole genome, ORF (open reading frame) and CCR (capsid coding region) using the neighbour-joining method revealed that EMCV isolates cluster into two groups (group 1 and 2) with two sub-clusters within group 1 (group 1a and 1b), and FJ13 belongs to group 1a. Animal experiment showed that the isolated strain FJ13 could cause clinical symptoms and pathological changes. The results of this study indicated that FJ13 caused myocarditis of tigers and provided new epidemiologic data on EMCV in China.

  5. On the tidally driven circulation in the South China Sea: modeling and analysis

    NASA Astrophysics Data System (ADS)

    Nelko, Varjola; Saha, Abhishek; Chua, Vivien P.

    2014-03-01

    The South China Sea is a large marginal sea surrounded by land masses and island chains, and characterized by complex bathymetry and irregular coastlines. An unstructured-grid SUNTANS model is employed to perform depth-averaged simulations of the circulation in the South China Sea. The model is tidally forced at the open ocean boundaries using the eight main tidal constituents as derived from the OSU Tidal Prediction Software. The model simulations are performed for the year 2005 using a time step of 60 s. The model reproduces the spring-neap and diurnal and semidiurnal variability in the observed data. Skill assessment of the model is performed by comparing model-predicted surface elevations with observations. For stations located in the central region of the South China Sea, the root mean squared errors (RMSE) are less than 10 % and the Pearson's correlation coefficient ( r) is as high as 0.9. The simulations show that the quality of the model prediction is dependent on the horizontal grid resolution, coastline accuracy, and boundary locations. The maximum RMSE errors and minimum correlation coefficients occur at Kaohsiung (located in northern South China Sea off Taiwan coast) and Tioman (located in southern South China Sea off Malaysia coast). This may be explained with spectral analysis of sea level residuals and winds, which reveal dynamics at Kaohsiung and Tioman are strongly influenced by the seasonal monsoon winds. Our model demonstrates the importance of tidally driven circulation in the central region of the South China Sea.

  6. 78 FR 65711 - Uncovered Innerspring Units From China, South Africa, and Vietnam Institution of Five-Year Reviews

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-01

    ... orders on imports of uncovered innerspring units from South Africa and Vietnam (73 FR 75390 and 75391... COMMISSION Uncovered Innerspring Units From China, South Africa, and Vietnam Institution of Five-Year Reviews... innerspring units from China, South Africa, and Vietnam would be likely to lead to continuation or...

  7. An integrated geophysical study on the Mesozoic strata distribution and hydrocarbon potential in the South China Sea

    NASA Astrophysics Data System (ADS)

    Hu, Weijian; Hao, Tianyao; Jiang, Weiwei; Xu, Ya; Zhao, Baimin; Jiang, Didi

    2015-11-01

    A series of drilling, dredge, and seismic investigations indicate that Mesozoic sediments exist in the South China Sea (SCS) which shows a bright prospect for oil and gas exploration. In order to study the distribution of Mesozoic strata and their residual thicknesses in the SCS, we carried out an integrated geophysical study based mainly on gravity data, gravity basement depth and distribution of residual Mesozoic thickness in the SCS were obtained using gravity inversion constrained with high-precision drilling and seismic data. In addition, the fine deep crustal structures and distribution characteristics of Mesozoic thicknesses of three typical profiles were obtained by gravity fitting inversion. Mesozoic strata in the SCS are mainly distributed in the south and north continental margins, and have been reformed by the later tectonic activities. They extend in NE-trending stripes are macro-controlled by the deep and large NE-trending faults, and cut by the NW-trending faults which were active in later times. The offset in NW direction of Mesozoic strata in Nansha area of the southern margin are more obvious as compared to the north margin. In the Pearl River Mouth Basin and Southwest Taiwan Basin of the north continental margin the Mesozoic sediments are continuously distributed with a relatively large thickness. In the Nansha area of the south margin the Mesozoic strata are discontinuous and their thicknesses vary considerably. According to the characteristics of Mesozoic thickness distribution and hydrocarbon potential analyses from drilling and other data, Dongsha Uplift-Chaoshan Depression, Southwest Taiwan Basin-Peikang Uplift and Liyue Bank have large thickness of the Mesozoic residual strata, have good hydrocarbon genesis capability and complete source-reservoir-cap combinations, show a bright prospect of Mesozoic oil/gas resources.

  8. Thermal springs in the Boise River basin, south-central Idaho

    USGS Publications Warehouse

    Lewis, R.E.; Young, H.W.

    1982-01-01

    The Boise River Basin, characterized by steep, rugged mountains and narrow river valleys, drains an area of about 2,680 square miles in south-central Idaho. Granitic rocks of the Idaho batholith predominate in the basin. Temperature of waters from thermal springs in the basin range from 33 degrees to 87 degrees Celsius, are sodium carbonate type and are slightly alkaline. Dissolved-solids concentrations are less than 280 milligrams per liter. Estimated reservoir temperatures determined by the silica and sodium-potassium-calcium geothermometers range from 50 degrees to 98 degrees Celsius. Tritium concentrations in sampled thermal springs are near zero and indicate these waters were recharged prior to 1954. Stable-isotope data are not conclusive insofar as indicating a source area of recharge for the thermal springs in the basin. Thermal springs discharged at least 4,900 acre-feet of water in 1981, and the associated convective heat flux is 11,000,000 calories per second. (USGS)

  9. Morrowan sedimentation in the Orogrande basin, west Texas and south-central New Mexico

    SciTech Connect

    Connolly, W.M.; Stanton, R.J. Jr.

    1986-03-01

    Morrowan strata in the Hueco and Franklin Mountains reflect deposition within a shallow, gradually subsiding, carbonate shelf lagoon. Postulated environments fluctuated between open shelf lagoon with localized shoaling, restricted inner shelf lagoon, and peritidal settings. Variations in depth were slight, probably not exceeding several tens of meters within the photic zone. The La Tuna Formation (Franklin Mountains) was deposited near the axis (center) of the Orogrande basin; the lower division of the Magdalena limestone (Hueco Mountains), 30 mi east, was deposited 20-30 mi west of the paleoshoreline. Physiographically, the Orogrande sea was a small gulf, offering a certain degree of protection from the Morrowan seaway to the south. Sedimentologically, it was a wide expanse of predominantly quiet-water carbonate sedimentation with subordinate argillaceous influex and coarser peripheral clastics. The Orogrande basin, a stratigraphic feature, corresponds to a blanket deposit of shallow epeiric carbonates. Climatic and orographic effects are invoked to explain the contrasting style of clastic sedimentation in the Delaware and orogrande basins, east and west of the Pedernal uplift. Analysis of Morrowan carbonates reveals no evidence of cyclicity, major transgressions or regressions, or local tectonic activity. Deposition was stable and in equilibrium with a gradually subsiding shallow basin. Based on lithologic, faunal, biostratigraphic, and paleogeographic criteria, the lower division is both laterally and temporally equivalent with the La Tuna Formation. Accordingly, the latter term is advocated in favor of the former, which lacks both priority and formal status.

  10. Application of sequence stratigraphy to oil and gas exploration in Bredasdorp basin offshore South Africa

    SciTech Connect

    Van Wyk, N.J.S.

    1989-03-01

    For more than two decades, oil and gas exploration in offshore South African rift basins within structural synrift plays yielded limited success. After the first oil discovery in postrift sediments in the Bredasdorp basin in 1987, sequence-stratigraphic concepts were applied to the Lower Cretaceous postrift sequences to permit correlation of depositional systems tracts and related facies throughout the basin. Extensive high-resolution seismic coverage and borehole control supported the study. The interplay of diminishing rift tectonics, thermal cooling, and inferred eustatic variations in global sea level produced a distinctive series of repetitive cycle depositional sequences. As many as 10 cyclic sequences and megasequences, deposited between the mid-Valanginian and lower Santonian, can be recognized within resolution limits of regional seismic profiles. Various elements of lowstand systems tracts within these sequences appear to contain potential reservoirs. Highly erosional (type 1) unconformities, commonly exhibiting incised valleys and canyons, provide surfaces on which (1) mounded and sheetlike submarine/basin-floor fans, (2) submarine channel fill and associated mounds and fans, and (3) prograding deltaic/coastal lowstand wedges were deposited. These fans, channel fills, and wedges are top sealed and sourced by transgressive shales and marine condensed sections, deposited at a time of regional transgression of the shoreline. One discovery well and various reservoir-quality sandstones occurring at predicted stratigraphic levels in other wells support the application of the sequence-stratigraphic concepts to hydrocarbon exploration.

  11. Adaptive Fusion of Information for Seeing into Ordos Basin, China: A China-Germany-US Joint Venture.

    NASA Astrophysics Data System (ADS)

    Yeh, T. C. J.; Yin, L.; Sauter, M.; Hu, R.; Ptak, T.; Hou, G. C.

    2014-12-01

    Adaptive fusion of information for seeing into geological basins is the theme of this joint venture. The objective of this venture is to initiate possible collaborations between scientists from China, Germany, and US to develop innovative technologies, which can be utilized to characterize geological and hydrological structures and processes as well as other natural resources in regional scale geological basins of hundreds of thousands of kilometers (i.e., the Ordos Basin, China). This adaptive fusion of information aims to assimilate active (manmade) and passive (natural) hydrologic and geophysical tomography surveys to enhance our ability of seeing into hydrogeological basins at the resolutions of our interests. The active hydrogeophysical tomography refers to recently developed hydraulic tomgoraphic surveys by Chinese and German scientists, as well as well-established geophysical tomography surveys (such as electrical resistivity tomography, cross-borehole radars, electrical magnetic surveys). These active hydrogeophysical tomgoraphic surveys have been proven to be useful high-resolution surveys for geological media of tens and hundreds of meters wide and deep. For basin-scale (i.e., tens and hundreds of kilometers) problems, their applicabilities are however rather limited. The passive hydrogeophysical tomography refers to unexplored technologies that exploit natural stimuli as energy sources for tomographic surveys, which include direct lightning strikes, groundwater level fluctuations due to earthquakes, river stage fluctuations, precipitation storms, barometric pressure variations, and long term climate changes. These natural stimuli are spatially varying, recurrent, and powerful, influencing geological media over great distances and depths (e.g., tens and hundreds of kilometers). Monitoring hydrological and geophysical responses of geological media to these stimuli at different locations is tantamount to collecting data of naturally occurring tomographic

  12. Cenozoic magmatism in the northern continental margin of the South China Sea: evidence from seismic profiles

    NASA Astrophysics Data System (ADS)

    Zhang, Qiao; Wu, Shiguo; Dong, Dongdong

    2016-06-01

    Igneous rocks in the northern margin of the South China Sea (SCS) have been identified via high resolution multi-channel seismic data in addition to other geophysical and drilling well data. This study identified intrusive and extrusive structures including seamounts and buried volcanoes, and their seismic characteristics. Intrusive features consist of piercement and implicit-piercement type structures, indicating different energy input associated with diapir formation. Extrusive structures are divided into flat-topped and conical-topped seamounts. Three main criteria (the overlying strata, the contact relationship and sills) were used to distinguish between intrusive rocks and buried volcanos. Three criteria are also used to estimate the timing of igneous rock formation: the contact relationship, the overlying sedimentary thickness and seismic reflection characteristics. These criteria are applied to recognize and distinguish between three periods of Cenozoic magmatism in the northern margin of the SCS: before seafloor spreading (Paleocene and Eocene), during seafloor spreading (Early Oligocene-Mid Miocene) and after cessation of seafloor spreading (Mid Miocene-Recent). Among them, greater attention is given to the extensive magmatism since 5.5 Ma, which is present throughout nearly all of the study area, making it a significant event in the SCS. Almost all of the Cenozoic igneous rocks were located below the 1500 m bathymetric contour. In contrast with the wide distribution of igneous rocks in the volcanic rifted margin, igneous rocks in the syn-rift stage of the northern margin of the SCS are extremely sporadic, and they could only be found in the southern Pearl River Mouth basin and NW sub-sea basin. The ocean-continent transition of the northern SCS exhibits high-angle listric faults, concentrated on the seaward side of the magmatic zone, and a sharply decreased crust, with little influence from a mantle plume. These observations provide further evidence to

  13. EOF analysis of long-term reconstructed AVHRR Pathfinder SST in the South China Sea

    NASA Astrophysics Data System (ADS)

    Huynh, Hong-Ngu T.; Alvera-Azcárate, Aida; Barth, Alexander; Beckers, Jean-Marie

    2014-05-01

    Sea surface temperature (SST) is one of the key variables often used to investigate ocean dynamics, ocean-atmosphere interaction, and climate change. For recent decades, the AVHRR Pathfinder SST, measured by infrared sensors, has been widely used because of its high resolution and long time-series. The disadvantage of the AVHRR Pathfinder SST is high percentage of missing data due to cloud coverage. This becomes more serious in the South China Sea (SCS) because it is located in the tropical region, frequently covered by clouds. In this study, we used the Data INterpolating Empirical Orthogonal Functions (DINEOF) method to reconstruct daily night-time 4 km AVHRR Pathfinder SST spanning from 1989 to 2009 for the whole SCS. In order to better understand the spatial and temporal variability of the SCS SST, an EOF analysis of the reconstructed field is performed in association with surface wind. The first SST mode, accounting for 69% of the variance, presents the cooling (warming) of the basin due to the solar inclination through seasons, water exchange, topography, and monsoon-induced cyclonic circulation. The second SST mode, explaining 24.8% of the variance, shows the advection of cold and warm water from two opposite directions along the southwest-northeast diagonal of the basin. The second SST mode is affected by the atmospheric anticyclone (cyclone) located over the Philippine Sea. Comparing both SST modes with Nino3.0 index, it shows that the interannual variability of the SCS SST is influenced by the moderate and strong ENSO events with a lag of 5-6 months. Moreover, the analysis of the high-resolution reconstructed dataset reveals some oceanic features that could not be captured in the previous EOF analyses.

  14. Eddy heat and salt transports in the South China Sea and their seasonal modulations

    NASA Astrophysics Data System (ADS)

    Chen, Gengxin; Gan, Jianping; Xie, Qiang; Chu, Xiaoqing; Wang, Dongxiao; Hou, Yijun

    2012-05-01

    This study describes characteristics of eddy (turbulent) heat and salt transports, in the basin-scale circulation as well as in the embedded mesoscale eddy found in the South China Sea (SCS). We first showed the features of turbulent heat and salt transports in mesoscale eddies using sea level anomaly (SLA) data, in situ hydrographic data, and 375 Argo profiles. We found that the transports were horizontally variable due to asymmetric distributions of temperature and salinity anomalies and that they were vertically correlated with the thermocline and halocline depths in the eddies. An existing barrier layer caused the halocline and eddy salt transport to be relatively shallow. We then analyzed the transports in the basin-scale circulation using an eddy diffusivity method and the sea surface height data, the Argo profiles, and the climatological hydrographic data. We found that relatively large poleward eddy heat transports occurred to the east of Vietnam (EOV) in summer and to the west of the Luzon Islands (WOL) in winter, while a large equatorward heat transport was located to the west of the Luzon Strait (WLS) in winter. The eddy salt transports were mostly similar to the heat transports but in the equatorward direction due to the fact that the mean salinity in the upper layer in the SCS tended to decrease toward the equator. Using a 21/2-layer reduced-gravity model, we conducted a baroclinic instability study and showed that the baroclinic instability was critical to the seasonal variation of eddy kinetic energy (EKE) and thus the eddy transports. EOV, WLS, and WOL were regions with strong baroclinic instability, and, thus, with intensified eddy transports in the SCS. The combined effects of vertical velocity shear, latitude, and stratification determined the intensity of the baroclinic instability, which intensified the eddy transports EOV during summer and WLS and WOL during winter.

  15. Coccolithophore responses to environmental variability in the South China Sea: species composition and calcite content

    NASA Astrophysics Data System (ADS)

    Jin, Xiaobo; Liu, Chuanlian; Poulton, Alex J.; Dai, Minhan; Guo, Xianghui

    2016-08-01

    Coccolithophore contributions to the global marine carbon cycle are regulated by the calcite content of their scales (coccoliths) and the relative cellular levels of photosynthesis and calcification rates. All three of these factors vary between coccolithophore species and with response to the growth environment. Here, water samples were collected in the northern basin of the South China Sea (SCS) during summer 2014 in order to examine how environmental variability influenced species composition and cellular levels of calcite content. Average coccolithophore abundance and their calcite concentration in the water column were 11.82 cells mL-1 and 1508.3 pg C mL-1, respectively, during the cruise. Water samples can be divided into three floral groups according to their distinct coccolithophore communities. The vertical structure of the coccolithophore community in the water column was controlled by the trophic conditions, which were regulated by mesoscale eddies across the SCS basin. The evaluation of coccolithophore-based calcite in the surface ocean also showed that three key species in the SCS (Emiliania huxleyi, Gephyrocapsa oceanica, Florisphaera profunda) and other larger, numerically rare species made almost equal contributions to total coccolith-based calcite in the water column. For Emiliania huxleyi biometry measurements, coccolith size positively correlated with nutrients (nitrate, phosphate), and it is suggested that coccolith length is influenced by light and nutrients through the regulation of growth rates. Larger-sized coccoliths were also linked statistically to low pH and calcite saturation states; however, it is not a simple cause and effect relationship, as carbonate chemistry was strongly co-correlated with the other key environmental factors (nutrients, light).

  16. Regional Consortia for E-Resources: A Case Study of Deals in the South China Region

    ERIC Educational Resources Information Center

    Chunrong, Luo; Jingfen, Wang; Zhinong, Zhou

    2010-01-01

    Purpose: The purpose of this paper is to analyse the current situation and the social and economic benefits from the consortia acquisitions of electronic resources by the China Academic Library and Information System (CALIS) South China Regional Centre and to recommend improvements for consortia acquisitions. Design/methodology/approach: Analyses…

  17. 68 FR 47607 - Electrolytic Manganese Dioxide From Australia, China, Greece, Ireland, Japan, and South Africa

    Federal Register 2010, 2011, 2012, 2013, 2014

    2003-08-11

    ..., except to the extent permitted by section 201.8 of the Commission's rules, as amended, 67 FR 68036... COMMISSION Electrolytic Manganese Dioxide From Australia, China, Greece, Ireland, Japan, and South Africa... States is materially retarded, by reason of imports from Australia, China, Greece, Ireland, Japan,...

  18. Paleomagnetism and anisotropy of magnetic susceptibility of Eocene and Miocene sediments in the Qaidam Basin, Northwest China: Implication for the Cenozoic tectonic transition and development of the northern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Yu, X.; Guo, Z.; Huang, B.; Yin, A.; Guan, S.; Zhou, S.; Qiao, Q.; Cheng, F.; Cheng, X.; Zhang, T.

    2013-12-01

    Paleomagnetism and AMS (Anisotropy of Magnetic Susceptibility) results are reported from the middle to late Eocene Xiaganchaigou Formation and the early to middle Miocene Xiayoushashan Formation sediments at eight locations (Xichagou, Gansen, Eboliang, Heishiqiu, Luluohe, Kushuiquan, Hong Shan and Gahai), covering most outcrop regions of these two formations within the Qaidam Basin, Northwest China. These paleomagnetic data indicate that the Qaidam basin has not undergone wholesale tectonic vertical axis rotation relative to Eurasia and North China since at least middle and late Eocene. Local clockwise rotation only took place at some special locations such as Gahai. According to AMS results, 12 of 16 AMS ellipsoids belong to embryonic deformation magnetic fabric, which can be applied to reconstruct tectonic strain. Two epochs of compressive strain have been identified in the Qaidam basin during the Cenozoic: an early N-S strain no later than the Oligocene and a late NE-SW strain mainly after the early to middle Miocene. Further analysis shows that the early N-S compression in northern Qaidam basin is much more intense than that in western Qaidam basin, while the late NE-SW compression, which dominates the NW-SE-trending folds in the modern Qaidam basin, is more intense in western Qaidam basin than that in northern Qaidam basin. The stress concentration transition provides a reasonable explanation of the southeastwards migration of the deposition center in the Qaidam basin during the Cenozoic. The uniform paleomagnetic and AMS results at different localities reveal that the Qaidam basin is a relatively rigid plate, obviously different from the surrounding regions. Moreover, the appearance of E-component stress may be in close relationship with the beginning of the left-lateral Kunlun Fault or the eastwards channel flow south to the Kunlun Fault, implying that the south side of the Kunlun Fault is the active side.

  19. The epidemiology of tinea manuum in Nanchang area, South China.

    PubMed

    Zhan, Ping; Geng, Chengfang; Li, Zhihua; Jiang, Qing; Jin, Yun; Li, Caixia; Liu, Weida

    2013-08-01

    Tinea manuum is a common superficial fungal infection which is usually coexistent with tinea pedis; there are few studies available on the epidemiology of tinea manuum at present. This study aims to investigate the epidemiology of tinea manuum and its correlation with tinea pedis in south China. A total of 280 patients with tinea manuum were recruited. The epidemiological and clinical data were analyzed, and causative agents were isolated and identified mycologically. Totally, 84.3 % patients with tinea manuum had co-occurrence of tinea pedis, among which 88.4 % patients had experience of scratching their feet. There was a significant relationship between the touch habits and the hand infection (χ(2) = 65.451, P = 0.000). More than 90 % patients had quite the same species of isolates from multiple infected sites in one patient. Therefore, it seems that transmission of dermatophytes from the feet to hand by scratching might be a most common way. As for tinea manuum, whether "unilateral" or "bilateral" is just the result that pathogens spread from feet to hand(s), which is only a special clinical presentation of tinea.

  20. Mangrove succession enriches the sediment microbial community in South China.

    PubMed

    Chen, Quan; Zhao, Qian; Li, Jing; Jian, Shuguang; Ren, Hai

    2016-01-01

    Sediment microorganisms help create and maintain mangrove ecosystems. Although the changes in vegetation during mangrove forest succession have been well studied, the changes in the sediment microbial community during mangrove succession are poorly understood. To investigate the changes in the sediment microbial community during succession of mangroves at Zhanjiang, South China, we used phospholipid fatty acid (PLFA) analysis and the following chronosequence from primary to climax community: unvegetated shoal; Avicennia marina community; Aegiceras corniculatum community; and Bruguiera gymnorrhiza + Rhizophora stylosa community. The PLFA concentrations of all sediment microbial groups (total microorganisms, fungi, gram-positive bacteria, gram-negative bacteria, and actinomycetes) increased significantly with each stage of mangrove succession. Microbial PLFA concentrations in the sediment were significantly lower in the wet season than in the dry season. Regression and ordination analyses indicated that the changes in the microbial community with mangrove succession were mainly associated with properties of the aboveground vegetation (mainly plant height) and the sediment (mainly sediment organic matter and total nitrogen). The changes in the sediment microbial community can probably be explained by increases in nutrients and microhabitat heterogeneity during mangrove succession. PMID:27265262

  1. Mangrove succession enriches the sediment microbial community in South China

    PubMed Central

    Chen, Quan; Zhao, Qian; Li, Jing; Jian, Shuguang; Ren, Hai

    2016-01-01

    Sediment microorganisms help create and maintain mangrove ecosystems. Although the changes in vegetation during mangrove forest succession have been well studied, the changes in the sediment microbial community during mangrove succession are poorly understood. To investigate the changes in the sediment microbial community during succession of mangroves at Zhanjiang, South China, we used phospholipid fatty acid (PLFA) analysis and the following chronosequence from primary to climax community: unvegetated shoal; Avicennia marina community; Aegiceras corniculatum community; and Bruguiera gymnorrhiza + Rhizophora stylosa community. The PLFA concentrations of all sediment microbial groups (total microorganisms, fungi, gram-positive bacteria, gram-negative bacteria, and actinomycetes) increased significantly with each stage of mangrove succession. Microbial PLFA concentrations in the sediment were significantly lower in the wet season than in the dry season. Regression and ordination analyses indicated that the changes in the microbial community with mangrove succession were mainly associated with properties of the aboveground vegetation (mainly plant height) and the sediment (mainly sediment organic matter and total nitrogen). The changes in the sediment microbial community can probably be explained by increases in nutrients and microhabitat heterogeneity during mangrove succession. PMID:27265262

  2. Dissolved Black Carbon in the South China Sea

    NASA Astrophysics Data System (ADS)

    Fang, Z.; Yang, W.; Chen, M.; Ma, H.

    2015-12-01

    Dissolved black carbon (DBC) has been ubiquitously reported in dissolved organic matter (DOM). However, the abundance and provenance of DBC in the ocean are not well understood. Here, DBC in the South China Sea (SCS) was determined at molecular level using the benzenepolycarboxylic acids (BPCAs) method. DBC showed high concentrations in the upper 100 m seawater with the average of 1.13 μmol l-1 (n=55). In the intermediate seawater (200-1500 m), DBC ranged from 0.67 to 0.89 μmol l-1 with the average of 0.78 μmol l-1 (n=9), exhibiting nearly homogeneous distributions. The vertical distribution pattern indicated that DBC significantly degraded in the photic zone, corresponding to an attenuate constant of 12.5±4.9 km-1. The ratios of B6CA/B3CAs increased downward, implying that aromatic condensation degree of DBC increase during transport from surface to deep water. Using the standing crops of DBC in the upper 200 m and the residence time of seawater, atmospheric deposition of DBC was estimated to be 1.94 TgC yr-1, accounting for around 16% of the global BC deposition. Our study highlights that DBC could be an important component of ocean carbon cycling in Pacific Asia Marginal Seas.

  3. Regulation of South China Sea throughflow by pressure difference

    NASA Astrophysics Data System (ADS)

    Qin, Huiling; Huang, Rui Xin; Wang, Weiqiang; Xue, Huijie

    2016-06-01

    Sea Surface Height (SSH) data from the European Centre for Medium-Range Weather Forecasts-Ocean Reanalysis System 4 (ECMWF-ORAS4) are used to determine the pressure difference in connection with variability of the South China Sea ThroughFlow (SCSTF) from 1958 to 2007. Two branches of SCSTF, the Karimata-Sunda Strait ThroughFlow (KSSTF) and the Mindoro Strait ThroughFlow (MSTF), are examined. Using the ensemble empirical mode decomposition method (EEMD), time series of pressure difference and volume transport are decomposed into intrinsic mode functions and trend functions, with the corresponding variability on different time scales. Pressure difference agrees with the KSSTF volume transport on decadal time scale; while for the MSTF, pressure difference varies similarly with volume transport on interannual time scale. Separating the dynamic height difference into the thermal and haline terms, for the KSSTF more than half of the dynamic height difference (32 cm) is due to the thermal contributions; while the remaining dynamic height difference (23 cm) is due to the haline contributions. For the MSTF, the dynamic height difference (29 cm) is primarily due to the thermal contribution (26 cm).

  4. Mangrove succession enriches the sediment microbial community in South China.

    PubMed

    Chen, Quan; Zhao, Qian; Li, Jing; Jian, Shuguang; Ren, Hai

    2016-06-06

    Sediment microorganisms help create and maintain mangrove ecosystems. Although the changes in vegetation during mangrove forest succession have been well studied, the changes in the sediment microbial community during mangrove succession are poorly understood. To investigate the changes in the sediment microbial community during succession of mangroves at Zhanjiang, South China, we used phospholipid fatty acid (PLFA) analysis and the following chronosequence from primary to climax community: unvegetated shoal; Avicennia marina community; Aegiceras corniculatum community; and Bruguiera gymnorrhiza + Rhizophora stylosa community. The PLFA concentrations of all sediment microbial groups (total microorganisms, fungi, gram-positive bacteria, gram-negative bacteria, and actinomycetes) increased significantly with each stage of mangrove succession. Microbial PLFA concentrations in the sediment were significantly lower in the wet season than in the dry season. Regression and ordination analyses indicated that the changes in the microbial community with mangrove succession were mainly associated with properties of the aboveground vegetation (mainly plant height) and the sediment (mainly sediment organic matter and total nitrogen). The changes in the sediment microbial community can probably be explained by increases in nutrients and microhabitat heterogeneity during mangrove succession.

  5. The shallow meridional overturning circulation of the South China Sea

    NASA Astrophysics Data System (ADS)

    Zhang, N.; Lan, J.; Cui, F.

    2014-04-01

    In this paper, the structure and formation mechanism of the annual-mean shallow meridional overturning circulation of the South China Sea (SCS) are investigated. A distinct clockwise overturning circulation is present above 400 m in the SCS on the climatological annual mean scale. The shallow meridional overturning circulation consists of downwelling in the northern SCS, a southward subsurface branch supplying upwelling in the southern SCS and a northward return flow of surface water. The formation mechanism is explored by studying causes of the branches constituting the meridional overturning circulation. The surface branch is driven by the annual mean zonal component of the wind stress which is predominantly westward. Another effect of the wind is Ekman pumping related subduction in the north hence the main source of downwelling there. The mixed layer depth reaches its maximum in winter and shoals in spring, which causes the thermocline to outcrop and ventilate. Part of the water mass from the bottom of the mixed layer subducts into the thermocline and flows southward along the isopycnals. The upwelling region is mainly along the Vietnam coast and in the open-ocean off it. In summer, the alongshore component of wind stress off Vietnam can cause coastal upwelling and the increase of alongshore wind off the coast can also cause great upwelling in the open-ocean off the Vietnam coast.

  6. Wind-induced currents in the South China Sea

    NASA Astrophysics Data System (ADS)

    Luu, Quang-Hung; Tkalich, Pavel

    2016-04-01

    The South China Sea (SCS) is one of the Earth's largest marginal seas. Located in the transitional region between the Pacific Ocean and the Indian Ocean as well as in the convergent zone of various multi-scale atmospheric and climatic drivers, the wind-induced circulations in the SCS are highly complicated. In this study, we derive the high-resolution seasonal patterns of wind-induced circulations in the SCS using the Semi-implicit Eulerian-Lagrangian Finite-Element (SELFE) model. The complicated bathymetry is mainly resolved by the dataset of the Shuttle Radar Topography Mission (SMRT) with the resolution as fine as 15-arc second. We further improve the topography by merging it with very-fine bathymetry being digitized from satellite images for features and islands the in the middle of the SCS (the Spratly and the Paracels). The model is forced by climatological wind and atmospheric pressure from National Centers for Environmental Prediction (NCEP). High-resolution patterns of wind-induced circulations in the SCS during Northeast (NE) and Southwest (SW) monsoons are presented, zooming at small features in the middle of the SCS. We further discuss the distortions of wind-induced currents during NE and SW seasons by examining two cases: the presence and the absence of tides.

  7. Kuroshio intrusion into the South China Sea: A review

    NASA Astrophysics Data System (ADS)

    Nan, Feng; Xue, Huijie; Yu, Fei

    2015-09-01

    The Kuroshio carrying the northwestern Pacific water intrudes into the South China Sea (SCS) through the Luzon Strait, significantly affecting the temperature, salinity, circulation, and eddy generation in the SCS. Thus, the Kuroshio intrusion makes important contributions to the momentum, heat and salt budgets in the SCS. In the past decades, much work has been done on the Kuroshio intrusion. This paper reviews past efforts and summarizes our current understanding of the Kuroshio intruding processes from observational evidence, laboratory results, theoretical analyses, and a range of numerical model simulations. In addition, discrepancies between results simulated by models, as well as those between simulations and observations, are presented. Specifically, this paper addresses the following topics: (1) different types of the Kuroshio intrusion into the SCS and their identification, (2) vertical structure of the Kuroshio in the Luzon Strait, (3) an overview of the Luzon Strait transport resulting from observations and numerical model simulations, (4) seasonal and interannual variations of the Kuroshio intrusion, as well as eddy generation due to the Kuroshio path variation, and (5) dynamical mechanisms (e.g., wind forcing, interbasin pressure gradient, β effect and hysteresis, potential vorticity, eddy activity) controlling the Kuroshio intrusion into the SCS. Finally, several future research topics for gaining a better understanding of the Kuroshio intruding processes are suggested.

  8. Nonlinear Internal Waves in the South China Sea During ASIAEX

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Tang, David T.; Ramp, Steve R.

    2002-01-01

    Internal wave distribution maps have been compiled from more than one hundred ERS-1/2, RADARSAT and Space Shuttle SAR images in the South China Sea (SCS) from 1993 to 2000. Based on these distribution maps, most of internal waves in the northeast part of SCS were propagating westward. The wave crest can be as long as 200 km with amplitude of 100 m, due to strong current from the Kuroshio branching out into the SCS. In recent Asian Seas International Acoustics Experiment (ASIAEX), moorings have been deployed in April 2000 and May 2001. Simultaneous RADARSAT ScanSAR images have been collected during the field test to integrate with the model and the in-situ measurements in the SCS. During ASIAEX in May 2001, many large internal waves were observed at the test area and were the major features for acoustic volume interaction. The environmental parameters have been calculated based on extensive CTD castings and mooring data. Nonlinear internal wave models have been applied to simulate the wave evolution on the continental shelf and the results compare reasonably with mooring measurements. The evolution and dissipation of huge internal waves on the shelf break, mode-two waves, elevation waves, and wave-wave interaction are very important issues for acoustic propagation. The implication of internal wave effects on acoustic propagation will also be discussed.

  9. A reanalysis dataset of the South China Sea

    PubMed Central

    Zeng, Xuezhi; Peng, Shiqiu; Li, Zhijin; Qi, Yiquan; Chen, Rongyu

    2014-01-01

    Ocean reanalysis provides a temporally continuous and spatially gridded four-dimensional estimate of the ocean state for a better understanding of the ocean dynamics and its spatial/temporal variability. Here we present a 19-year (1992–2010) high-resolution ocean reanalysis dataset of the upper ocean in the South China Sea (SCS) produced from an ocean data assimilation system. A wide variety of observations, including in-situ temperature/salinity profiles, ship-measured and satellite-derived sea surface temperatures, and sea surface height anomalies from satellite altimetry, are assimilated into the outputs of an ocean general circulation model using a multi-scale incremental three-dimensional variational data assimilation scheme, yielding a daily high-resolution reanalysis dataset of the SCS. Comparisons between the reanalysis and independent observations support the reliability of the dataset. The presented dataset provides the research community of the SCS an important data source for studying the thermodynamic processes of the ocean circulation and meso-scale features in the SCS, including their spatial and temporal variability. PMID:25977803

  10. A reanalysis dataset of the South China Sea.

    PubMed

    Zeng, Xuezhi; Peng, Shiqiu; Li, Zhijin; Qi, Yiquan; Chen, Rongyu

    2014-01-01

    Ocean reanalysis provides a temporally continuous and spatially gridded four-dimensional estimate of the ocean state for a better understanding of the ocean dynamics and its spatial/temporal variability. Here we present a 19-year (1992-2010) high-resolution ocean reanalysis dataset of the upper ocean in the South China Sea (SCS) produced from an ocean data assimilation system. A wide variety of observations, including in-situ temperature/salinity profiles, ship-measured and satellite-derived sea surface temperatures, and sea surface height anomalies from satellite altimetry, are assimilated into the outputs of an ocean general circulation model using a multi-scale incremental three-dimensional variational data assimilation scheme, yielding a daily high-resolution reanalysis dataset of the SCS. Comparisons between the reanalysis and independent observations support the reliability of the dataset. The presented dataset provides the research community of the SCS an important data source for studying the thermodynamic processes of the ocean circulation and meso-scale features in the SCS, including their spatial and temporal variability.

  11. AIR QUALITY IMPACTS OF LIQUEFIED NATURAL GAS IN THE SOUTH COAST AIR BASIN OF CALIFORNIA

    SciTech Connect

    Carerras-Sospedra, Marc; Brouwer, Jack; Dabdub, Donald; Lunden, Melissa; Singer, Brett

    2011-07-01

    The effects of liquefied natural gas (LNG) on pollutant emission inventories and air quality in the South Coast Air Basin of California were evaluated using recent LNG emission measurements by Lawrence Berkeley National Laboratory and the Southern California Gas Company (SoCalGas), and with a state-of-the-art air quality model. Pollutant emissions can be affected by LNG owing to differences in composition and physical properties, including the Wobbe index, a measure of energy delivery rate. This analysis uses LNG distribution scenarios developed by modeling Southern California gas flows, including supplies from the LNG receiving terminal in Baja California, Mexico. Based on these scenarios, the projected penetratino of LNG in the South Coast Air Basin is expected to be limited. In addition, the increased Wobbe index of delivered gas (resulting from mixtures of LNG and conventional gas supplies) is expected to cause increases smaller than 0.05 percent in overall (area-wide) emissions of nitrogen oxides (NOx). BAsed on the photochemical state of the South Coast Air Basin, any increase in NOx is expected to cause an increase in the highest local ozone concentrations, and this is reflected in model results. However, the magnitude of the increase is well below the generally accepted accuracy of the model and would not be discernible with the existing monitoring network. Modeling of hypothetical scenarios indicates that discernible changes to ambient ozone and particulate matter concentrations would occur only at LNG distribution rates that are not achievable with current or planned infrastructure and with Wobbe index vlaues that exceed current gas quality tariffs. Results of these hypothetical scenarios are presented for consideration of any proposed substantial expansion of LNG supply infrastructure in Southern California.

  12. Quantifying climate and pumping contributions to aquifer depletion using a highly parameterised groundwater model: Uley South Basin (South Australia)

    NASA Astrophysics Data System (ADS)

    Knowling, Matthew J.; Werner, Adrian D.; Herckenrath, Daan

    2015-04-01

    The relative contributions of climate and human stresses to aquifer depletion in real-world settings are rarely quantified, particularly where complex patterns of depletion arise from the spatial and temporal variability in aquifer stresses. These impacts can be assessed using calibration-constrained model predictions of disturbed (i.e., subject to human activity) and undisturbed (i.e., natural) conditions. Prior investigations that adopt this approach employ lumped-parameter or one-dimensional models. Here, we extend previous studies by using a highly parameterised, spatially distributed groundwater model to investigate the relative impacts of climate variability and pumping on aquifer depletion. The Uley South Basin (USB), South Australia, where there is conjecture surrounding the cause of declining groundwater levels, serves as a case study. The relative contributions of climate variability and pumping to USB depletion are shown to be highly variable in time and space. Temporal trends reflect variability in rainfall and pumping, as expected. Spatial trends are primarily dependent on the proximity to both the coastal boundary and pumping wells, and to the distribution of recharge and hydraulic properties. Results show that pumping impacts exceed those of climate between 1978 and 2012, and over the majority of the spatial extent of USB. The contribution of pumping to aquifer depletion is shown to be 2.9 and 1.4 times that of climate in terms of the time-averaged and maximum-in-time basin-scale water budget, respectively. Confidence in model predictions is enhanced by the outcomes of a linear predictive uncertainty analysis, which indicates that predictive uncertainty is lower than climatic and pumping impacts. This study demonstrates the application of a relatively simple analysis that can be used in combination with highly parameterised, spatially distributed groundwater models to differentiate causal factors of aquifer depletion.

  13. Magmatism, structure and age of Dove Basin (Antarctica): A key to understanding South Scotia Arc development

    NASA Astrophysics Data System (ADS)

    Galindo-Zaldívar, Jesús; Puga, Encarnación; Bohoyo, Fernando; González, Francisco Javier; Maldonado, Andrés; Martos, Yasmina M.; Pérez, Lara F.; Ruano, Patricia; Schreider, Anatoly A.; Somoza, Luis; Suriñach, Emma; Antonio, Díaz de Federico

    2014-11-01

    Dove Basin is situated in the south-central Scotia Sea, between Pirie and Bruce banks, and was formed during the development of the Scotia Arc. The basin has a roughly sigmoidal shape, with a prominent NNE-SSW elongated ridge located in its central part, the Dove Ridge, which is considered as an extinct spreading axis. A NE-SW elongated tectonic high, the Dove Seamount, is located in the north-eastern region of the basin, bounded by a normal fault dipping to the southeast. Dredged rocks and geophysical data were collected during the SCAN2004 and SCAN2008 cruises. Dredged samples were recovered from three positive features in the center of the basin, two from Dove Ridge, and one from Dove Seamount. Igneous rocks along the Dove Ridge are mainly tholeiitic basalts, derived from asthenospheric upper mantle within an extensional supra-subduction back-arc tectonic setting, which evolved over time from back-arc basin basalts (BABB) toward Mid Oceanic Ridge Basalts (MORBs). Altered olivine-bearing fine- and medium-grained basaltic rocks were also dredged from Dove Ridge and the seamount, together with minor oceanic island arc basalts and basaltic andesites. The mantle source was affected, up to early Miocene times, by a subducted oceanic slab related to an arc to the east, with Dove Basin forming in a back-arc position. Minor alkaline oceanic island basalts dredged at the seamount might represent a final extensional stage, genetically related with the dying Dove Ridge volcanism or, less probably, to a later, late Miocene-Pliocene extensional stage, producing incipient volcanism deriving from a deeper mantle source. 40Ar/39Ar dating of MORB samples dredged from the Dove Ridge provided ages of 20.4 ± 2.6 to 22.8 ± 3.1 Ma. These outcrops were later coated by Fe-Mn crusts with Co-Chronometer ages ranging from at least 12.6 Ma and probably up to 18 Ma. Analysis of magnetic anomaly profiles shows the best fit in the central profile, corresponding to chrons C6B (21.7 Ma) to C7

  14. Reversal process of the South China Sea western boundary current in autumn 2011

    NASA Astrophysics Data System (ADS)

    Zhang, Zhixin; Guo, Jingsong; Guo, Binghuo

    2016-05-01

    Using merged sea level anomaly and absolute geostrophic velocity products from satellite altimetry and Argos drifter data, we analyzed the reversal process of the South China Sea (SCS) western boundary current (SCSwbc) from a summer to winter pattern in 2011 and important oceanic phenomena during this process. Results show that the outbreak time of the northeast monsoon over the southern SCS lagged that over the northern SCS by about 1 month. During the SCS monsoon reversal period, the SCSwbc reversed rapidly into the winter pattern at the Guangdong continental slope in late September. Subsequently, the southward Vietnam coastal boundary current strengthened. However, the northward Natuna Current maintained a summer state until mid-October. Thus, the balance between the southward and northward currents was lost when they met, their junction moved gradually southward. However, a loop current formed southeast of Vietnam because the main stream of the Vietnam Offshore Current (VOC) remained near its original latitude. Meanwhile, the VOC and associated dipole circulation system strengthened. After mid-October, the northward Natuna Current began to weaken, the loop current finally shed, becoming a cool ring. The VOC and its associated dipole sub-basin circulation system also weakened gradually until it disappeared.

  15. High resolution seismic imaging of complex structures: a case study of the South China Sea data

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Wang, Jun; Fu, Geping

    2016-03-01

    Seismic imaging is an effective way for marine geophysical investigation. Different types of imaging schemes, such as pre-stack time migration (PSTM) and pre-stack depth migration (PSDM), are often used to reveal subsurface structures. Theoretically, the PSDM method, which better honors the wave field propagation, can produce more accurate subsurface images compared with PSTM. However, it is challenging for PSDM to obtain a proper velocity model. In the South China Sea basin, the presence of complex structures such as carbonate pinnacles makes velocity model building more difficult due to the complex geometry and strong velocity variation. We have developed a seismic processing work flow which aims to circumvent these difficulties and can improve the PSDM velocity model via iterative updating. In order to improve the data quality and obtain optimal results, a proper pre-processing is required. In this workflow, we use the full waveform inversion to update the velocity model, followed by the application of the tomography inversion. In this way, a geologically plausible velocity model for PSDM is obtained. Afterwards, we use the Q-tomography approach to estimate the Earth quality factor (Q), which numerically quantifies the earth absorption and attenuation effect. Finally we use a de-absorption pre-stack depth migration scheme to compensate for the Earth absorption and attenuation effect in the process of imaging. The amplitudes are balanced and a high quality subsurface image is obtained.

  16. Geochemistry and petrogenesis of volcanic rocks from Daimao Seamount (South China Sea) and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Yan, Quanshu; Castillo, Paterno; Shi, Xuefa; Wang, Liaoliang; Liao, Lin; Ren, Jiangbo

    2015-03-01

    The South China Sea (SCS) experienced three episodes of seafloor spreading and left three fossil spreading centers presently located at 18°N, 17°N and 15.5°N. Spreading ceased at these three locations during magnetic anomaly 10, 8, and 5c, respectively. Daimao Seamount (16.6 Ma) was formed 10 my after the cessation of the 17°N spreading center. Volcaniclastic rocks and shallow-water carbonate facies near the summit of Daimao Seamount provide key information on the seamount's geologic history. New major and trace element and Sr-Nd-Pb isotopic compositions of basaltic breccia clasts in the volcaniclastics suggest that Daimao and other SCS seamounts have typical ocean island basalt-like composition and possess a 'Dupal' isotopic signature. Our new analyses, combined with available data, indicate that the basaltic foundation of Daimao Seamount was formed through subaqueous explosive volcanic eruptions at 16.6 Ma. The seamount subsided rapidly (> 0.12 mm/y) at first, allowing the deposition of shallow-water, coral-bearing carbonates around its summit and, then, at a slower rate (< 0.12 mm/y). We propose that the parental magmas of SCS seamount lavas originated from the Hainan mantle plume. In contrast, lavas from contemporaneous seamounts in other marginal basins in the western Pacific are subduction-related.

  17. 3D analogue modeling of the South China Sea: A discussion on breakup pattern

    NASA Astrophysics Data System (ADS)

    Sun, Zhen; Zhong, Zhihong; Keep, Myra; Zhou, Di; Cai, Dongsheng; Li, Xushen; Wu, Shimin; Jiang, Jianqun

    2009-04-01

    The opening of the South China Sea is one of the most important Cenozoic events in SE Asia. In order to investigate its tectonic evolution, three analogue modeling experiments were compared. The modeling results suggest that rifting pattern and orientation change of the rift zone were related to initial rheological stratification. Affected by the ductile flow of silicone (lower crust) and honey (asthenosphere), the faults became flattened, especially close to the breakup area. We conjecture that the slope area may bear relatively hotter and thinner lithosphere than the shelf area from the beginning of rifting due to stretching and mantle upwelling associated with this regional extension, which in turn lead to the change in initial rheological stratification and therefore the rifting pattern from shelf to slope. In the experiments, breakup developed first at isolated points, which grew and coalesced to become a single spreading area. The conjugate boundaries were either all concave or all convex. Where a rigid massif was located at the divergent boundary, stretching history was different. In this case, the northern and southern areas thinned rapidly and developed into two deep troughs, which may finally evolve into spreading centers. The shape of the massif controls the orientation and boundary shape of the spreading area. It is interpreted that crustal breakup was more viscous in style, and the NW sub sea basin developed along the northern trough of the Zhongsha-Xisha massif (Macclesfield Bank).

  18. Dynamics and anthropogenic impacts of multiple karst flow systems in a mountainous area of South China

    NASA Astrophysics Data System (ADS)

    Luo, Mingming; Chen, Zhihua; Criss, Robert E.; Zhou, Hong; Huang, He; Han, Zhaofeng; Shi, Tingting

    2016-08-01

    The Xiangxi River basin, South China, is a steep terrane with well-developed karst features and an important Cambrian-Ordovician aquifer. Meteoric water in this mountainous area features a mean δ18O elevation gradient of -2.4 ‰/km. This gradient was used to estimate mean recharge elevations of 760 m for Shuimoxi (SMX) spring, 1,060 m for Xiangshuidong (XSD) spring, and 1,430 m for drill hole ZK03, indicating multiple flow paths in the Cambrian-Ordovician karst aquifer. Mean residence times of 230 and 320 days and ˜2 years were estimated for these features, respectively, using the damped running average model that predicts the isotopic variations in groundwater from those in precipitation. Groundwater in the regional karst flow system has the longest residence time, the highest recharge elevation, the longest flow paths, the lowest addition of anthropogenic components, and the greatest amount of water-rock interaction as indicated by its higher dissolved solids, Mg2+ concentrations and Mg/Ca ratios than the springs. In contrast, the local and shallow karst flow systems respond rapidly to recharge events. Artificial tracer tests prove that these shallow karst systems can also quickly transmit anthropogenic contaminants, indicating that they are highly vulnerable to human impacts, which include the enrichment of NO3 -. The intensity of water-rock interaction and groundwater vulnerability are mainly determined by the structure and dynamics of the multiple karst flow systems.

  19. Interannual to decadal variation of spring sea level anomaly in the western South China Sea

    NASA Astrophysics Data System (ADS)

    Qiu, Fuwen; Fang, Wendong; Pan, Aijun; Cha, Jing; Zhang, Shanwu; Huang, Jiang

    2016-04-01

    Satellite observations of sea level anomalies (SLA) from January 1993 to December 2012 are used to investigate the interannual to decadal changes of the boreal spring high SLA in the western South China Sea (SCS) using the Empirical Orthogonal Function (EOF) method. We find that the SLA variability has two dominant modes. The Sea Level Changing Mode (SLCM) occurs mainly during La Niña years, with high SLA extension from west of Luzon to the eastern coast of Vietnam along the central basin of the SCS, and is likely induced by the increment of the ocean heat content. The Anticyclonic Eddy Mode (AEM) occurs mainly during El Niño years and appears to be triggered by the negative wind curl anomalies within the central SCS. In addition, the spring high SLA in the western SCS experienced a quasi-decadal change during 1993-2012; in other words, the AEM predominated during 1993-1998 and 2002-2005, while the La Niña-related SLCM prevailed during 1999-2001 and 2006-2012. Moreover, we suggest that the accelerated sea level rise in the SCS during 2005-2012 makes the SLCM the leading mode over the past two decades.

  20. Long term trend of sea surface temperature in the South China Sea

    NASA Astrophysics Data System (ADS)

    Choi, A.; Park, Y.

    2012-12-01

    Using HAdISST the long term trend in the South China Sea (SCS) sea surface temperature (SST) between 1950 and 2008 is investigated. In general SST has been increased since 1950, but the rate of increase is spatiotemporally uneven. Winter warming rate is greater than that of summer. In both seasons the rate of increase is greater during 1980s. Winter warming rate is greater over the deeper basin while summer warming rate is greater over the shallower southeastern part. In summer the weakening of southwesterly monsoon reduces upwelling along the east coast of Vietnam to warm the surface. On the other hand, the net surface heat flux, however, is reduced and cannot contribute to the warming. In winter the net heat flux into the sea increases and could contribute to the warming. The spatial pattern of the heat flux, however, is different from that of the warming. The heat flux is increased over the coastal area where warming is small, but decreased in deeper part where warming is greater. After 1980's the northeasterly monsoon winds weakens to reduce the southward western boundary currents, and subsequently cold advection and to warm the area.

  1. Locating South China in Rodinia and Gondwana: A fragment of Greater India Lithosphere? (Invited)

    NASA Astrophysics Data System (ADS)

    Cawood, P. A.; Zhao, G.; Wang, Y.; Xu, Y.

    2013-12-01

    From the formation of Rodinia at the end of the Mesoproterozoic through to the breakup of Pangea in the Mesozoic, the South China craton first formed and then occupied a position adjacent to Western Australia and northern India. Early Neoproterozoic supra-subduction zone magmatic arc-back arc assemblages in the craton range in age from ca. 1000 Ma to 820 Ma and display a sequential northwest decrease in age. These relations suggest formation and closure of arc systems through southeast-directed subduction and resulted in progressive northwestward accretion onto the periphery of an already assembled Rodinia. Siliciclastic units within an early Paleozoic succession that transgresses across the craton were derived from the southeast and include detritus from beyond the current limits of the craton. Detrital zircon age spectra require an East Gondwana source and are very similar to the Tethyan Himalaya and younger Paleozoic successions from Western Australia suggesting derivation from a common source and by inference accumulation in linked basins along the northern margin of Gondwana, a situation that continued until rifting and breakup of the craton in the late Paleozoic.

  2. Biogeographical distribution and diversity of bacterial communities in surface sediments of the South China Sea.

    PubMed

    Li, Tao; Wang, Peng

    2013-05-01

    This paper aims at an investigation of the features of bacterial communities in surface sediments of the South China Sea (SCS). In particular, biogeographical distribution patterns and the phylogenetic diversity of bacteria found in sediments collected from a coral reef platform, a continental slope, and a deep-sea basin were determined. Bacterial diversity was measured by an observation of 16S rRNA genes, and 18 phylogenetic groups were identified in the bacterial clone library. Planctomycetes, Deltaproteobacteria, candidate division OP11, and Alphaproteobacteria made up the majority of the bacteria in the samples, with their mean bacterial clones being 16%, 15%, 12%, and 9%, respectively. By comparison, the bacterial communities found in the SCS surface sediments were significantly different from other previously observed deep-sea bacterial communities. This research also emphasizes the fact that geographical factors have an impact on the biogeographical distribution patterns of bacterial communities. For instance, canonical correspondence analyses illustrated that the percentage of sand weight and water depth are important factors affecting the bacterial community composition. Therefore, this study highlights the importance of adequately determining the relationship between geographical factors and the distribution of bacteria in the world's seas and oceans.

  3. Physical characteristics of stream subbasins in the lower Minnesota River basin, south-central Minnesota

    USGS Publications Warehouse

    Sanocki, C.A.

    1997-01-01

    Data that describe the physical characteristics of stream subbasins upstream from selected sites on streams in the Lower Minnesota River Basin, located in south-central Minnesota are presented in this report. The physical characteristics are the drainage area of the subbasin, the percentage area of the subbasin covered only by lakes, the percentage area of the subbasin covered by both lakes and wetlands, the main-channel length, and the main-channel slope. Stream sites include outlets of subbasins of at least 5 square miles, outfalls of sewage treatment plants, and locations of U.S. Geological Survey low-flow, high-flow, and continuous-record gaging stations.

  4. Occurrence and distribution of hexabromocyclododecane in sediments from seven major river drainage basins in China.

    PubMed

    Li, Honghua; Shang, Hongtao; Wang, Pu; Wang, Yawei; Zhang, Haidong; Zhang, Qinghua; Jiang, Guibin

    2013-01-01

    The concentrations and geographical distribution of hexabromocyclododecane (HBCD) were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection (LOD) to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of HBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that gamma-HBCD dominated in most of the sediment samples, followed by alpha- and beta-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively. PMID:23586301

  5. Water risk assessment for river basins in China based on WWF water risk assessment tools

    NASA Astrophysics Data System (ADS)

    Wei, N.; Qiu, Y.; Gan, H.; Niu, C.; Liu, J.; Gan, Y.; Zhou, N.

    2014-09-01

    Water resource problems, one of the most important environmental and socio-economic issues, have been a common concern worldwide in recent years. Water resource risks are attracting more and more attention from the international community and national governments. Given the current situations of water resources and the water environment, and the characteristics of water resources management and information statistics of China, this paper establishes an index system for water risk assessment in river basins of China based on the index system of water risk assessment proposed by the World Wide Fund For Nature (WWF) and German Investment and Development Co., Ltd (DEG). The new system is more suitable for Chinese national conditions and endorses the international assessment index. A variety of factors are considered to determine the critical values of classification for each index, and the indexes are graded by means of 5-grade and 5-score scales; the weights and calculation methods of some indexes are adjusted, with the remaining indexes adopting the method of WWF. The Weighted Comprehensive Index Summation Process is adopted to calculate the integrated assessment score of the river basin. The method is applied to the Haihe River basin in China. The assessment shows that the method can accurately reflect the water risk level of different river basins. Finally, the paper discusses the continuing problems in water risk assessment and points out the research required to provide a reference for further study in this field.

  6. Occurrence and distribution of hexabromocyclododecane in sediments from seven major river drainage basins in China.

    PubMed

    Li, Honghua; Shang, Hongtao; Wang, Pu; Wang, Yawei; Zhang, Haidong; Zhang, Qinghua; Jiang, Guibin

    2013-01-01

    The concentrations and geographical distribution of hexabromocyclododecane (HBCD) were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection (LOD) to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of HBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that gamma-HBCD dominated in most of the sediment samples, followed by alpha- and beta-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively.

  7. The impacts of climate change on water resources in the Second Songhua River Basin, China

    NASA Astrophysics Data System (ADS)

    Yu, J. S.; Yao, X. L.; Sun, W. C.; Li, Z. J.

    2016-08-01

    The Northeast China Plain is one of the main grain growing regions in China. Due to the high latitude and black soil ecological system, the crop growth in there is vulnerable to climate change, which makes it important to evaluate the influences of climate change on water resources. In this study, the influences of climate change on water resources of a typical basin in northeast China, the Second Songhua River Basin were assessed using the SWAT model. Ensemble downscaled output from sixteen GCMs for A1B emission scenario in 2050s was adopted as the regional climate scenario and was used to drive SWAT model to predict hydrological changes. The prediction shows that mean evapotranspiration of whole basin increases in most time of a year. Stream flow of Fuyu gauging station downstream this basin exhibits a decrease trend from April to June, November and December, and increases in the remaining period of the year. It is indicated that water resources may not be sufficient in spring for irrigation and the possibility of flood in summer may increases, indicating countermeasures should be made to ensure agricultural water use and prevent possible damages of flood on crop.

  8. Status and understanding of groundwater quality in the South Coast Interior groundwater basins, 2008: California GAMA Priority Basin Project

    USGS Publications Warehouse

    Parsons, Mary C.; Kulongoski, Justin T.; Belitz, Kenneth

    2014-01-01

    Groundwater quality in the approximately 653-square-mile (1,691-square-kilometer) South Coast Interior Basins (SCI) study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The South Coast Interior Basins study unit contains eight priority groundwater basins grouped into three study areas, Livermore, Gilroy, and Cuyama, in the Southern Coast Ranges hydrogeologic province. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The GAMA South Coast Interior Basins study was designed to provide a spatially unbiased assessment of untreated (raw) groundwater quality within the primary aquifer system, as well as a statistically consistent basis for comparing water quality between basins. The assessment was based on water-quality and ancillary data collected by the USGS from 50 wells in 2008 and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system was defined by the depth intervals of the wells listed in the CDPH database for the SCI study unit. The quality of groundwater in the primary aquifer system may be different from that in the shallower or deeper water-bearing zones; shallow groundwater may be more vulnerable to surficial contamination. The first component of this study, the status of the current quality of the groundwater resource, was assessed by using data from samples analyzed for volatile organic compounds (VOCs), pesticides, and naturally occurring inorganic constituents, such as trace elements and minor ions. This status assessment is intended to characterize the quality of groundwater resources within the primary aquifer system of the SCI study unit, not the treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentration

  9. Status and understanding of groundwater quality in the South Coast Interior groundwater basins, 2008: California GAMA Priority Basin Project

    USGS Publications Warehouse

    Parsons, Mary C.; Kulongoski, Justin T.; Belitz, Kenneth

    2014-01-01

    Groundwater quality in the approximately 653-square-mile (1,691-square-kilometer) South Coast Interior Basins (SCI) study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The South Coast Interior Basins study unit contains eight priority groundwater basins grouped into three study areas, Livermore, Gilroy, and Cuyama, in the Southern Coast Ranges hydrogeologic province. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The GAMA South Coast Interior Basins study was designed to provide a spatially unbiased assessment of untreated (raw) groundwater quality within the primary aquifer system, as well as a statistically consistent basis for comparing water quality between basins. The assessment was based on water-quality and ancillary data collected by the USGS from 50 wells in 2008 and on water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system was defined by the depth intervals of the wells listed in the CDPH database for the SCI study unit. The quality of groundwater in the primary aquifer system may be different from that in the shallower or deeper water-bearing zones; shallow groundwater may be more vulnerable to surficial contamination. The first component of this study, the status of the current quality of the groundwater resource, was assessed by using data from samples analyzed for volatile organic compounds (VOCs), pesticides, and naturally occurring inorganic constituents, such as trace elements and minor ions. This status assessment is intended to characterize the quality of groundwater resources within the primary aquifer system of the SCI study unit, not the treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentration

  10. Analysis of dry/wet conditions in the Gan River Basin, China, and their association with large-scale atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Zhang, Yuqing; You, Qinglong; Lin, Houbo; Chen, Changchun

    2015-10-01

    Droughts and floods are natural phenomena that occur when water availability is significantly below or above normal levels over a specific period. In recent years, the Gan River Basin has frequently been threatened by droughts and floods, and it is important to evaluate the characteristics of dry/wet conditions for better water resource management and disaster mitigation in this region. On the basis of precipitation and temperature data for the period 1964-2013 from 40 meteorological stations across the basin, the variability of dry/wet conditions was analyzed using the standardized precipitation evapotranspiration index (SPEI). In addition, the standardized streamflow index (SSI) and large-scale atmospheric circulation patterns calculated from NCEP/NCAR reanalysis data were used to further explore and evaluate temporal variations, spatial patterns, and possible mechanism responsible for the formation of dry/wet conditions in the basin. The results indicated that robust coefficients between monthly SSI and SPEI exist at multiple timescales. The best correlation coefficients were found at timescales of 2-3 months, which better reflect the intensity and magnitude of seasonal dry/wet conditions. Application of a 3-month SPEI for the dry (July-September) and wet (April-June) seasons indicated that severe dry/wet episodes were easy to occur in the northern part of the basin. The difference between composites of anomalous dry/wet seasons shows that both a positive height anomaly at 500 hPa and a very little water vapor flux influence the basin during the dry season of anomalous years, which can lead to the occurrence of drought events in the basin. However, during the wet season of anomalous years, geopotential height anomalies caused by areas of high pressure in the south (South China Sea) and areas of low pressure in the north (Mongolia), are responsible for the transport of copious amounts of water vapor from both the Bay of Bengal and the South China Sea. Under these

  11. What happens to nutrients in offstream reservoirs in the lower South Platte River basin?

    USGS Publications Warehouse

    Sprague, Lori A.; Kimbrough, Robert A.; Ranalli, Anthony J.

    2002-01-01

    The practice of storing South Platte River water in offstream reservoirs reduces nutrient concentrations but also contributes to the growth of algae, which may adversely affect the recreational use of the reservoirs. Results of a study of five offstream reservoirs in the lower South Platte River Basin during the 1995 irrigation season showed that the reservoirs trapped 20 to 88 percent of incoming nitrogen and phosphorus, except for phosphorus in one reservoir. Total nitrogen concentrations in the reservoirs were highest in March and decreased through September, largely as a result of uptake by algae and other aquatic life for growth. Total phosphorus concentrations in the reservoirs were more variable because of the recycling of phosphorus by aquatic life. Chlorophyll-a concentrations indicated that the amount of algae in all reservoirs increased during the summer and that all reservoirs were eutrophic. This study was done by the U.S. Geological Survey as part of the National Water-Quality Assessment (NAWQA) Program.

  12. Thin-skinned shortening geometries of the South Fork fault: Bighorn basin, Park County, Wyoming

    SciTech Connect

    Clarey, T.L. )

    1990-01-01

    This paper presents a new interpretation of the South Fork fault in light of thin-skinned thrust theory. Cross sections and seismic data are presented which indicate that the South Fork fault is an allochthonous salient which was emplaced in the Bighorn basin during the early to middle Eocene. All observed structural geometries can be interpreted as developing under a compressional regime, similar to the Wyoming-Utah-Idaho thrust belt. Faults either follow bedding-plane surfaces, cut up section in the direction of tectonic transport or form backthrusts. A single decollement within the Jurassic Gypsum Spring Formation appears to dominate. Tectonic transport was approximately southeast, parallel to tear faults in the allochthonous plate.

  13. Effects of landcover, water redistribution, and temperature on ecosystem processes in the South Plate Basin

    USGS Publications Warehouse

    Baron, J. S.; Hartman, M.D.; Kittel, T. G. F.; Band, L.E.; Ojima, D. S.; Lammers, R.B.

    1998-01-01

    Over one-third of the land area in the South Platte Basin of Colorado, Nebraska, and Wyoming, has been converted to croplands. Irrigated cropland now comprises 8% of the basin, while dry croplands make up 31%. We used the RHESSys model to compare the changes in plant productivity and vegetation-related hydrological processes that occurred as a result of either land cover alteration or directional temperature changes (−2°C, +4°C). Land cover change exerted more control over annual plant productivity and water fluxes for converted grasslands, while the effect of temperature changes on productivity and water fluxes was stronger in the mountain vegetation. Throughout the basin, land cover change increased the annual loss of water to the atmosphere by 114 mm via evaporation and transpiration, an increase of 37%. Both irrigated and nonirrigated grains became active earlier in the year than shortgrass steppe, leading to a seasonal shift in water losses to the atmosphere. Basin-wide photosynthesis increased by 80% due to grain production. In contrast, a 4°C warming scenario caused annual transpiration to increase by only 3% and annual evaporation to increase by 28%, for a total increase of 71 mm. Warming decreased basin-wide photosynthesis by 16%. There is a large elevational range from east to west in the South Platte Basin, which encompasses the western edge of the Great Plains and the eastern front of the Rocky Mountains. This elevational gain is accompanied by great changes in topographic complexity, vegetation type, and climate. Shortgrass steppe and crops found at elevations between 850 and 1800 m give way to coniferous forests and tundra between 1800 and 4000 m. Climate is increasingly dominated by winter snow precipitation with increasing elevation, and the timing of snowmelt influences tundra and forest ecosystem productivity, soil moisture, and downstream discharge. Mean annual precipitation of <500 mm on the plains below 1800 m is far less than potential

  14. New marine data from Vietnam Margin limit the amount of extrusion of Indochina during the opening of the South China Sea

    SciTech Connect

    Huchon, P.; Le Pichon, X. ); Rangin, C. ); Thi, P.T.

    1994-07-01

    A total of 9300 km of high resolution, wide coverage multibeam (Simrad EM12) bathymetric data have been acquired offshore Vietnam during the Ponaga cruise of the R/V L'Atalante in May 1993. Gravity and magnetic measurements, 6-channel seismic data, as well as 6 dredges also have been obtained. East of central Vietnam, the margin displays northeast-southwest tectonic structures typical of a passive margin. The depth of the basement of the Nha Trang basin suggests that it could be of oceanic nature, with a 20 to 30 Ma age compatible with the age of the South China Sea oceanic crust located further east. Southeast of South Vietnam, the authors identified the western tip of the fossil axis of the South China Sea. It constitutes a propagating ridge into a highly stretched continental crust, partly intruded by volcanics. East of 110[degrees]30[prime]E, tilted blocks are symmetric with respect to the oceanic axis, whereas west of 110[degrees]30[prime]E they are mostly tilted toward the south, which suggests the occurrence a large listric normal fault associated with a large amount of extension. The normal faults bend progressively to a more northerly direction when approaching the north-south scarp that bounds the Conson basin. This geometry is compatible with a right-lateral motion, and the normal faults associated with the oceanic propagator suggest that the dextral motion is synchronous with at least the last phase of spreading in the South China Sea (23-16 Ma). Since recent offshore oil data have established that the prolongation of the Red River fault within the Gulf of Tonkin was affected by left-lateral motion from the Oligocene to the upper Miocene, the results suggest that the change from left-lateral motion in the Gulf of Tonkin to right-lateral motion along the Vietnam margin occurs because the South China Sea basin opens more rapidly than the extrusion of Indochina. Thus, the total amount of extrusion of Indochina probably does not exceed 100 or 200 km.

  15. Origin of ancient potash evaporites: clues from the modem nonmarine qaidam basin of Western china.

    PubMed

    Lowenstein, T K; Spencer, R J; Pengxi, Z

    1989-09-01

    Modern potash salt deposits and associated brines of the Qaidam Basin, western China, demonstrate that some anomalous marine evaporites may have formed from nonmarine brines instead of seawater. Qaidam Basin brines are derived from meteoric river inflow mixed with small amounts of CaCl spring inflow similar in composition to many saline formation waters and hydrothermal brines. Evaporation of springenriched inflow yields a predicted mineral sequence including carnallite, bischofite, and tachyhydrite that is identical to several anomalous marine evaporites. Other mixtures of river and spring inflow produce the salt assemblage expected from evaporation of seawater. PMID:17838808

  16. Origin of ancient potash evaporites: clues from the modem nonmarine qaidam basin of Western china.

    PubMed

    Lowenstein, T K; Spencer, R J; Pengxi, Z

    1989-09-01

    Modern potash salt deposits and associated brines of the Qaidam Basin, western China, demonstrate that some anomalous marine evaporites may have formed from nonmarine brines instead of seawater. Qaidam Basin brines are derived from meteoric river inflow mixed with small amounts of CaCl spring inflow similar in composition to many saline formation waters and hydrothermal brines. Evaporation of springenriched inflow yields a predicted mineral sequence including carnallite, bischofite, and tachyhydrite that is identical to several anomalous marine evaporites. Other mixtures of river and spring inflow produce the salt assemblage expected from evaporation of seawater.

  17. Education in Rural Areas of China and South Africa: Comparative Perspectives on Policy and Educational Management. Comparative Perspectives: Education in China & South Africa.

    ERIC Educational Resources Information Center

    Gordon, Adele; Wang, Qiang

    This report on the educational systems in China and South Africa compares the policies and processes of the two countries as they attempt to expand and improve rural education. Both countries experienced a major political upheaval, and even though there is a 50-year time lag between these events, political changes ushered in radical educational…

  18. Towards a South Asia Land Data Assimilation System: first results for transboundary basins

    NASA Astrophysics Data System (ADS)

    Zaitchik, B. F.; Ghatak, D.; Toll, D. L.; Searby, N. D.; Limaye, A. S.; Peters-Lidard, C. D.; Bajracharya, B.; Shrestha, B. R.; Iceland, C.; Narula, K.; Lee, S.; Mourad, B.; Doorn, B.

    2014-12-01

    South Asia faces a remarkably complex and diverse set of hydrologic stresses, including melting glaciers, variable snowpack, intensively utilized transboundary rivers, rapid groundwater depletion due to irrigation, flood and drought hazard, and rapidly changing land use/cover and climate conditions. The management and prediction challenges posed by these conditions are compounded by the sparseness of in situ monitoring sites, particularly in headwaters regions, and a lack of open sharing of hydrometeorological data across national boundaries. As a result, uncertainties in availability in a situation of rising demands are leading to increasing competing and exploitive use of a limited resource, being experienced at various scales. An open water information system for decision support is an absolute necessity. In order to provide an open and spatially complete water information system for decision support across the region, we are implementing a customized Land Data Assimilation System (LDAS) designed to provide best-available estimates of hydrologic states and fluxes across South Asia, both retrospectively and in near-real time. The LDAS merges advanced land surface models with satellite-derived and in situ observations. In the case of South Asia, multiple satellite-derived hydrological fields are relevant to complete water balance analysis, including precipitation from multiple sources (e.g., TRMM, CHIRPS, GPM), water storage anomalies from GRACE, thermal infrared evapotranspiration estimates, and snowpack characteristics from visible and microwave sensors. Each of these observation types can either be ingested to South Asia LDAS or used as an independent observation for comparison. Here we present the first results of this South Asian Land Data Assimilation System, with a focus on complete water balance analysis for selected river basins in South Asia.

  19. Typical synoptic situations and their impacts on the wintertime air pollution in the Guanzhong basin, China

    NASA Astrophysics Data System (ADS)

    Bei, Naifang; Li, Guohui; Huang, Ru-Jin; Cao, Junji; Meng, Ning; Feng, Tian; Liu, Suixin; Zhang, Ting; Zhang, Qiang; Molina, Luisa T.

    2016-06-01

    Rapid industrialization and urbanization have caused severe air pollution in the Guanzhong basin, northwestern China, with heavy haze events occurring frequently in recent winters. Using the NCEP reanalysis data, the large-scale synoptic situations influencing the Guanzhong basin during wintertime of 2013 are categorized into six types to evaluate the contribution of synoptic situations to the air pollution, including "north-low", "southwest-trough", "southeast-high", "transition", "southeast-trough", and "inland-high". The FLEXPART model has been utilized to demonstrate the corresponding pollutant transport patterns for the typical synoptic situations in the basin. Except for "southwest-trough" and "southeast-high" (defined as favorable synoptic situations), the other four synoptic conditions (defined as unfavorable synoptic situations) generally facilitate the accumulation of air pollutants, causing heavy air pollution in the basin. In association with the measurement of PM2.5 (particulate matter with aerodynamic diameter less than 2.5 µm) in the basin, the unfavorable synoptic situations correspond to high PM2.5 mass concentrations or poor air quality and vice versa. The same analysis has also been applied to winters of 2008-2012, which shows that the basin was mainly influenced by the unfavorable synoptic situations during wintertime leading to poor air quality. The WRF-CHEM model has further been applied to simulate the selected 6 days representing the typical synoptic situations during the wintertime of 2013, and the results generally show a good agreement between the modeled distributions and variations of PM2.5 and the corresponding synoptic situations, demonstrating reasonable classification for the synoptic situations in the basin. Detailed meteorological conditions, such as temperature inversion, low-level horizontal wind speed, and planetary boundary layer, all contribute to heavy air pollution events in the basin under unfavorable synoptic conditions

  20. Biomarker characteristics of crude oils from the Qaidam basin, NW China

    SciTech Connect

    Ritts, B.D.; Hanson, A.D.; Moldowan, J.M.; Ekuan, A.

    1996-12-31

    The Qaidam basin, northwest China, has producing oil fields in the northwestern and northeastern corners of the basin. However, the petroleum systems in the basin and molecular organic geochemistry of the oils are undocumented. Jurassic and Tertiary petroleum source rocks occur throughout the northern Gaidam basin, and in surrounding mountain belts. The nonmarine Tertiary section contains thick sections of carbonate and evaporite-rich, hypersaline lacustrine mudstones, interbedded with alluvial and fluvial sandstones and conglomerates. In contrast, nonmarine Jurassic source rocks consist of laminated, black, lacustrine shales and related coals that were deposited in humid fluvial environments. Oils from the northwestern Qaidam basin have consistent biomarker and non-biomarker molecular organic geochemistry parameters, including low pristane: phytane ratio high-levels of gammacerane and C{sub 34} and C{sub 35} homohopanes, and the presence of {Beta} and {gamma}-carotane. These parameters indicate the source rock was deposited in a hypersaline, anoxic, reducing lacustrine environment, and probably had a significant carbonate or evaporate component. Based on geologic and geochemical data, the source rocks for these oils were in the Tertiary lacustrine section. Some oils from the northeastern part of the basin are similar geochemically to those from the northwest Qaidam basin, and also are derived from Tertiary hypersaline lacustrine source rocks. Other oils from the northeastern part of the basin are distinct in geochemical character. These oils have high pristane: phytane ratios, and do not contain hypersaline lacustrine indicators, as do northwestern Qaidam oils. The high pristane: phytane ratio, low relative abundance of C{sub 34} and C{sub 35} homohopanes and high terpane: sterane ratio, suggest a nonmarine origin for the northeastern Qaidam oils. These data indicate that Jurassic lacustrine shales were source rocks for oils in the northeastern Qaidam basin.

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

    NASA Astrophysics Data System (ADS)

    Kukla, Peter; Back, Stefan

    2010-05-01

    Recently, considerable attempts have been made to compare the sedimentary basin evolution and the associated tectonic framework on both sides of the South-Atlantic (e.g. Mohriak et al., 2008, and references therein). Yet there are still unresolved questions. Amongst the most striking observations is that multiple phases of volcanism, uplift and subsidence are recorded after the break-up of the southern South Atlantic margin segment on both sides of the Florianopolis - Walvis Ridge volcanic complex, features that are regarded as atypical when compared to published examples of other post-breakup continental margin successions. However, the tectono-sedimentary and magmatic styles markedly differ from south to north across the volcanic complex. In seismic reflection data, voluminous extrusives are manifested by the occurrence of large wedges of seaward dipping reflector sequences south of the volcanic complex, whilst large volumes of Cretaceous mafic alkaline rocks only occur north of the Florianopolis - Walvis Ridge complex. It can be expected that these differences are of a broad importance for the understanding of both break-up and post-breakup processes. This presentation focuses on a comparison of the post-breakup stratigraphic development of the South American and South African continental margins that both record thick post-rift sedimentary successions. Basins along the southern African margin are much narrower in comparison to their South American counterparts, constituting a pronounced margin asymmetry across the Atlantic. Adding to the heterogeneity of the system, the northernmost segment of the South Atlantic rift and salt basins is also characterized by a pronounced asymmetry, with the Brazilian margin now comprising narrower and deeper rift basins with less salt than the Congo-Gabon conjugate margin. In general, it seems that in the salt-prone areas both offshore South America and southern Africa, salt-related tectonics are amongst the key parameters

  2. Probabilistic forecasting of seasonal drought behaviors in the Huai River basin, China

    NASA Astrophysics Data System (ADS)

    Xiao, Mingzhong; Zhang, Qiang; Singh, Vijay P.; Chen, Xiaohong

    2016-01-01

    The Huai River basin is one of the major supplier of agricultural products in China, and droughts have critical impacts on agricultural development. Good knowledge of drought behaviors is of great importance in the planning and management of agricultural activities in the Huai River basin. With the copula functions to model the persistence property of drought, the probabilistic seasonal drought forecasting models have been built in the Huai River basin. In this study, droughts were monitored by the Standardized Precipitation Evapotranspiration Index (SPEI) with the time scales of 3, 6, and 9 months, and their composite occurrence probability has been used to forecast the seasonal drought. Results indicated that the uncertainty related to the predicted seasonal drought is larger when more severe droughts occurred in the previous seasons, and the severe drought which occurs in summer and autumn will be more likely to be persistent in the next season while the severe drought in winter and spring will be more likely to be recovered in the subsequent season. Furthermore, given the different drought statuses in the previous season, spatial patterns of the predicted drought events with the largest occurrence probability have also been investigated, and results indicate that the Huai River basin is vulnerable to the extreme drought in most parts of the basin, e.g., the severe drought in winter will be more likely to be persistent in spring in the central part of the southern Huai River basin. Such persistent drought events pose serious challenges for planning and management of agricultural irrigation, then results of the study will be valuable for the planning of crop cultivation or mitigation of the losses caused by drought in the Huai River basin, China.

  3. Assessment of potential unconventional Carboniferous-Permian gas resources of the Liaohe Basin eastern uplift, Liaoning Province, China, 2011

    USGS Publications Warehouse

    Pollastro, Richard M.; Potter, Christopher J.; Schenk, Christopher J.; Charpentier, Ronald R.; Cook, Troy A.; Klett, Timothy R.; Kirschbaum, Mark A.

    2012-01-01

    The U.S. Geological Survey estimated a mean of 448 billion cubic feet of potential technically recoverable unconventional natural gas in Carboniferous and Permian coal-bearing strata in the eastern uplift of the Liaohe Basin, Liaoning Province, China.

  4. A Pleistocene Indian Monsoon record from Heqing Basin, SW China

    NASA Astrophysics Data System (ADS)

    Qiang, X.; An, Z.; Shen, J.; Jin, Z.; Sun, Y.; Tong, G.; Chang, H.; Liu, X.; Liu, W.; Wang, S.; Zhou, W.; Song, Y.; Xiao, X.; Xiao, H.

    2008-12-01

    Heqing Basin (100°06'-100°16'E, 26°28'-26°46'N) is situated in southeastern margin of Tibetan Plateau, a geological conjunction zone of three tectonic units separated by Jinshajiang, Honghe and Xiaojinhe-Lijiang fault belts. Modern climate in this region is mainly influenced by Indian monsoon circulation. In Year 2002, a 665.83 m long core was retrieved from the Heqing basin under the support of Chinese Environmental Scientific Drilling program, which permits a high-resolution reconstruction of the Indian monsoon evolution from a continental perspective. The core mainly consists of gray clay, silty clay and silt. Magnetostratographic result generated by both thermal and alternating-field demagnetization methods indicates that the bottom age of the Heqing core is about 2.78 Myr. Multiple proxies (magnetic susceptibility, grain size, CaCO3 content, loss of ignite, pollen concentrations, and major/trace elements) were generated to reconstruct regional climate change and its dynamical links to Indian summer monsoon and solar insolation forcing. The results suggest that during glacial periods, this region is characterized by reduced vegetation cover (e.g., low total pollen concentration) and enhanced physical weathering (e.g., high Rb/Sr ratio), whereas during interglacial times, vegetation cover was extensive and chemical weathering is relatively strong around Heqing basin. Good correlation between variations in proxy indicators from Heqing core and stacked Indian summer monsoon record from Arabian Sea (Clemens and Prell, 2003) indicates that over the last 0.35 Myr, Heqing basin is predominantly influenced by Indian summer monsoon. Unlike Indian monsoon records from the Arabian Sea and Indian Ocean which resolution is relatively low, our high-resolution proxy variations permit a robust understanding of the Indian summer monsoon variations over the last 2.6 Myr. Comparisons of monsoon proxies from land and ocean indicate that solar insolation is the dominant factor

  5. Investigating Effects of Monsoon Winds on Hydrodynamics in the South China Sea

    NASA Astrophysics Data System (ADS)

    Chua, V. P.

    2013-12-01

    The South China Sea is a large marginal sea surrounded by land masses and island chains, and characterized by complex bathymetry and irregular coastlines. The circulation in South China Sea is subjected to seasonal and inter-annual variations of tidal and meteorological conditions. The effects of monsoon winds on hydrodynamics is investigated by applying spectral and harmonic analysis on surface elevation and wind data at stations located in the South China Sea. The analysis indicates varying responses to the seasonal monsoon depending on the location of the station. At Kaohsiung (located in northern South China Sea off Taiwan coast), tides from the Pacific Ocean and the southwest monsoon winds are found to be dominant mechanisms. The Kota Kinabalu and Bintulu stations, located to the east of South China Sea off Borneo coast, are influenced by low energy complex winds, and the shallow bottom bathymetry at these locations leads to tidal energy damping compared to other stations. The tidal dynamics at Tioman, located in southern South China Sea off Malaysia coast, are most responsive to the effects of the northeast monsoon. The complexity of our problem together with the limited amount of available data in the region presents a challenging research topic. An unstructured-grid SUNTANS model is employed to perform three-dimensional simulations of the circulation in South China Sea. Skill assessment of the model is performed by comparing model predictions of the surface elevations and currents with observations. The results suggest that the quality of the model prediction is highly dependent on horizontal grid resolution and coastline accuracy. The model may be used in future applications to investigate seasonal and inter-annual variations in hydrodynamics.

  6. SCSPOD14, a South China Sea physical oceanographic dataset derived from in situ measurements during 1919–2014

    PubMed Central

    Zeng, Lili; Wang, Dongxiao; Chen, Ju; Wang, Weiqiang; Chen, Rongyu

    2016-01-01

    In addition to the oceanographic data available for the South China Sea (SCS) from the World Ocean Database (WOD) and Array for Real-time Geostrophic Oceanography (Argo) floats, a suite of observations has been made by the South China Sea Institute of Oceanology (SCSIO) starting from the 1970s. Here, we assemble a SCS Physical Oceanographic Dataset (SCSPOD14) based on 51,392 validated temperature and salinity profiles collected from these three datasets for the period 1919–2014. A gridded dataset of climatological monthly mean temperature, salinity, and mixed and isothermal layer depth derived from an objective analysis of profiles is also presented. Comparisons with the World Ocean Atlas (WOA) and IFREMER/LOS Mixed Layer Depth Climatology confirm the reliability of the new dataset. This unique dataset offers an invaluable baseline perspective on the thermodynamic processes, spatial and temporal variability of water masses, and basin-scale and mesoscale oceanic structures in the SCS. We anticipate improvements and regular updates to this product as more observations become available from existing and future in situ networks. PMID:27116565

  7. SCSPOD14, a South China Sea physical oceanographic dataset derived from in situ measurements during 1919-2014.

    PubMed

    Zeng, Lili; Wang, Dongxiao; Chen, Ju; Wang, Weiqiang; Chen, Rongyu

    2016-04-26

    In addition to the oceanographic data available for the South China Sea (SCS) from the World Ocean Database (WOD) and Array for Real-time Geostrophic Oceanography (Argo) floats, a suite of observations has been made by the South China Sea Institute of O