Sample records for basin south china

  1. Tectonics and Sedimentary Basins of the South China Sea: Challenges and Progresses

    Zhou Di; Yao Bochu


    @@ The special issue "Tectonics and Sedimentary Basins of the South China Sea" consists of 19 articles arranged in the order of deep structure,general tectonics,tectonic modeling,and sedimentary basins especially the deepwater sedimentary basins.

  2. Profiler-sonobuoy measurements in the South China Sea basin

    Ludwig, W.J.; Kumar, N.; Houtz, R.E.


    Analyses of single-channel seismic reflection profiles, and wide-angle reflection and refraction data from sonobuoys, indicate that the deep part of the South China Sea basin is typically oceanic in structure, except that layer 2 is about 1 km thicker than usual and layer 3 is only about half the usual thickness. The top of layer 2 has a rough upper surface and becomes deeper in the northern part of the basin, where it is overlain by sediments of velocity 1.7--3.8 km/s up to 3 km thick. A 6-km-thick sequence of sediments fills a basement depression just north of the outer subsurface (peripheral) ridge of the Sunda shelf. Thick sediments were measured at the outer parts of the Sunda shelf, Palawan shelf, Northeast Borneo shelf, and in the Taiwan straits south of the Penghu-Peikang basement high. The Manila trench is divided into two sections, a sediment-filled trench between southernmost Taiwan and Stewart bank off central northern Luzon and a topographic trench between Stewart bank southward into the Mindoro straits. Burial of part of the trench by sediments that thicken to the north and the thick sediment cover of the northern South China Sea basin indicate provenance from the north. The northern margin of the South China Sea basin is predominantly a zone of tension the southern margin is predominantly a zone of compression, the western margin may be a zone of shear, and the eastern margin is a subduction zone. It seems probable that the southern margin of the basin, called the Reed bank crustal block, was formerly attached to mainland Asia. Sometime during the Paleogene the Reed bank crustal block broke away from the continent, and new sea floor was created between the southeastward migrating block and the Asian mainland. Old ocean crust in front of the advancing block was subducted along the northwestern sides of Borneo and Palawan. Subduction ceased in the early Miocene with the collision of the crustal block and the Borneo-Palawan isthmian ridge.

  3. Understanding sedimentation in the Song Hong-Yinggehai Basin, South China Sea

    Yan, Y.; Carter, A; Palk, C.; S. Brichau; Hu, X


    The Cenozoic Song Hong–Yinggehai Basin in the South China Sea contains a large volume of sediment that has been used in previous studies, together with regional geomorphology, to argue for the existence of a large palaeodrainage system that connected eastern Tibet with the South China Sea. To test this and to understand the significance of sediment volumes deposited in the Song Hong–Yinggehai Basin, this study compared erosion histories of source regions with sediment volumes deposited during...

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

    Yao, Wei-Hua; Li, Zheng-Xiang


    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.

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

    Xu, Xianbing; Tang, Shuai; Lin, Shoufa


    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.

  6. Exploration of drought evolution using numerical simulations over the Xijiang (West River) basin in South China

    Niu, Jun; Chen, Ji; Sun, Liqun


    The knowledge of drought evolution characteristics may aid the decision making process in mitigating drought impacts. This study uses a macro-scale hydrological model, Variable Infiltration Capacity (VIC) model, to simulate terrestrial hydrological processes over the Xijiang (West River) basin in South China. Three drought indices, namely standardized precipitation index (SPI), standardized runoff index (SRI), and soil moisture anomaly index (SMAI), are employed to examine the spatio-temporal and evolution features of drought events. SPI, SRI and SMAI represent meteorological drought, hydrological drought and agricultural drought, respectively. The results reveal that the drought severity depicted by SPI and SRI is similar with increasing timescales; SRI is close to that of SPI in the wet season for the Liu River basin as the high-frequency precipitation is conserved more by runoff; the time lags appear between SPI and SRI due to the delay response of runoff to precipitation variability for the You River basin. The case study in 2010 spring drought further shows that the spatio-temporal evolutions are modulated by the basin-scale topography. There is more consistency between meteorological and hydrological droughts for the fan-like basin with a converged river network. For the west area of the Xijiang basin with the high elevation, the hydrological drought severity is less than meteorological drought during the developing stage. The recovery of hydrological and agricultural droughts is slower than that of meteorological drought for basins with a longer mainstream.

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

    Yan, Pin; Wang, Yanlin


    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

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

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


    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.

  9. Hydrological long-term dry and wet periods in the Xijiang River basin, South China

    T. Fischer


    Full Text Available In this study, hydrological long-term dry and wet periods are analyzed for the Xijiang River basin in South China. Daily precipitation data of 118 stations and data on daily discharge at Gaoyao hydrological station at the mouth of the Xijiang River for the period 1961–2007 are used. At a 24-month timescale, the standardized precipitation index (SPI-24 for the six sub-basins of the Xijiang River and the standardized discharge index (SDI-24 for Gaoyao station are applied. The monthly values of the SPI-24 averaged for the Xijiang River basin correlate highly with the monthly values of the SDI-24. Distinct long-term dry and wet sequences can be detected.

    The principal component analysis is applied and shows spatial disparities in dry and wet periods for the six sub-basins. The correlation between the SPI-24 of the six sub-basins and the first principal component score shows that 67% of the variability within the sub-basins can be explained by dry and wet periods in the east of the Xijiang River basin. The spatial dipole conditions (second and third principal component explain spatiotemporal disparities in the variability of dry and wet periods. All sub-basins contribute to hydrological dry periods, while mainly the northeastern sub-basins cause wet periods in the Xijiang River. We can also conclude that long-term dry events are larger in spatial extent and cover all sub-basins while long-term wet events are regional phenomena.

    A spectral analysis is applied for the SPI-24 and the SDI-24. The results show significant peaks in periodicities of 11–14.7 yr, 2.8 yr, 3.4–3.7 yr, and 6.3–7.3 yr. The same periodic cycles can be found in the SPI-24 of the six sub-basins but with some variability in the mean magnitude. A wavelet analysis shows that significant periodicities have been stable over time since the 1980s. Extrapolations of the reconstructed SPI-24 and SDI-24 represent the continuation of observed significant periodicities

  10. A continental slope stability evaluation in the Zhujiang River Mouth Basin in the South China Sea

    LIU Ke; WANG Jianhua


    In nature, a slope stability is determined by the ratio of a sliding resistance to a slide force. The slide force of a marine deep-water continental slope is mainly affected by sediment mechanics properties, a topography, and a marine seismic. However, the sliding resistance is mainly affected by sedimentary patterns and a sedi-mentary stress history. Both of these are different from case to case, and their impact can be addressed when the data are organized in a geographic information system (GIS). The study area on the continental slope in Zhujiang River Mouth Basin in South China Sea provides an excellent opportunity to apply GIS spatial analysis technology for the evaluation of the slope stability. In this area, a continental slope topography and a three-dimension (3-D) topography mapping show a sea-floor morphology and the distribution of a slope steepness in good detail, and the sediment analysis of seabed samples and an indoor appraisal reveals the variability of a sediment density near the sea-floor surface. On the basis of the results of nine geotechnical studies of submarine study areas, it has worked out that an equivalent cyclic shear stress ratio is roughly between 0.158 and 0.933, which is mainly depending on the initial water content of sediment. A regional density, slope and level of anticipated seismic shaking information are combined in a GIS framework to yield a map that illustrates a continental slope stability zoning under the influencing factors in Zhujiang River Mouth Basin in the South China Sea. The continental slope stability evaluation can contribute to north resources development in the South China Sea, the marine functional zoning, the marine engineering con-struction and adjust measures to local conditions, at the same time also can provide references for other deep-water slope stability analysis.

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

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


    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.

  12. The mechanics of continental extension in Qiongdongnan Basin, northern South China Sea

    Zhao, Zhongxian; Sun, Zhen; Wang, Zhenfeng; Sun, Zhipeng


    Located in the intersection of NE-trended rifted margin of South China Sea (SCS) and NW-oriented Ailao Shan-Red River Shear Zone (RRSZ), Qiongdongnan Basin shows significant differences in geological features from west to east, indicating different mechanics of continental extension. Based on the dense and updated multichannel seismic profiles, we disclose the characteristics of the remnant crystalline crust. Besides, we analyze the basin structures, calculate the stretching factors of upper and whole crust, and compute the syn-rift and post-rift unloaded tectonic subsidence along three selected transects in the west, middle and east of Qiongdongnan Basin. The crust thickness is 22 km on the northern and southern parts of Qiongdongnan Basin and thins gradually towards the central depression with two extremely thinned domains (factors of crust are 1.5-2 on both sides and increase remarkably towards the central depression (β > 2) with two extremely stretched domains (β > 9), of which one is in Ledong Sag in the west and another is in Baodao and Changchang Sags in the east. However, the mechanics of continental extension vary significantly from west to east. The simple shear dominates in the west, the pure shear dominates in the east, and it is intermediate between the two end members of simple shear and pure shear in the middle of Qiongdongnan Basin. The simple shear in the west of Qiongdongnan Basin is probably controlled by the left-lateral movement of RRSZ. The pure shear in the east is probably related to the Cenozoic rifting along the northern continental margin of SCS. The transitional zone in the middle of Qiongdongnan Basin is possibly the combined results of the left-lateral movement of RRSZ and the Cenozoic rifting along the northern continental margin of SCS.

  13. Water geochemistry of the Xijiang basin rivers, South China: Chemical weathering and CO2 consumption

    Research highlights: → The Xijiang River is the second largest river in China and flows through a large carbonate rock region in South China. → Sulfuric acid, which emanate from acid precipitation and the oxidation of sulfide minerals, is involved as a proton donor in weathering reactions in the Xijiang basin. → Calculated results show that the contribution of cations from rock weathering induced by sulfuric acid accounts for approximately 11.2%. → The flux of CO2 released into the atmosphere is approximately 0.41 x 1012 gC yr-1 produced by sulfuric acid-induced carbonate weathering in the Xijiang basin. → Sulfuric acid-induced carbonate weathering could counterbalance a significant part of the CO2 consumed by silicate weathering. - Abstract: The Xijiang River, the mainstream of the Zhujiang (Pearl) River, which is the second largest river in China in terms of discharge, flows through a large carbonate rock region in South China. The chemical and Sr isotopic compositions of the Xijiang waters were determined during the high-flow season in order to understand the chemical weathering processes, associated CO2 consumption and anthropogenic influences within the carbonate-dominated basin. The major ion compositions of the river waters are characterized by the dominance of Ca2+, Mg2+, HCO3- and are significantly rich in SO42-. The SO42- is mainly derived from the oxidation of sulfide minerals and acid precipitation caused by coal combustion. Chemical and Sr isotopic compositions of the river waters indicate that four reservoirs (carbonates, silicates, evaporites and anthropogenic inputs) contribute to the total dissolved loads. The chemical weathering rates of carbonates and silicates for the Xijiang basin are estimated to be approximately 78.5 and 7.45 ton km-2 a-1, respectively. The total chemical weathering rate of rocks for the Xijiang basin is approximately 86.1 ton km-2 a-1 or 42 mm ka-1, which is much higher than global mean values. The budgets of CO2

  14. Relationship between Formation of Zhongyebei Basin and Spreading of Southwest Subbasin, South China Sea

    Gao Hongfang; Zhou Di; Qiu Yan


    The Zhongyebei (中业北) basin (ZYBB) is an NE-striking,narrow and small sedimentary basin superimposing the southern 1/2 segment of the proposed spreading axes of the SW subbasin of the South China Sea (SCS).More than 4 500 m strata were identified in the Zhongyebei basin,including the Paleogene lower structure layer and the Neogene upper structure layer.The SW subbasin of the South China Sea has been regarded as an oceanic basin opened by seafloor spreading,as evidenced by the fiat and deep (> 4 000 m mostly) seafloor with linear magnetic anomalies,and by the shallow Moho depth of < 12 km as estimated from gravity modeling.The classic model of seafloor spreading predicts that sediments on the oceanic crust are younger and thinner towards the spreading axes.But in the southwestern segment of the SW subbasin,contradictions appear.Firstly,the thick sedimentation in the ZYBB is along the proposed spreading axes.Secondly,the sediments are thinner (500-1 500 m) and younger away from the proposed spreading axes.Thirdly,geological elements of the two sides of spreading axes develop asymmetrically in the southwestern SW subbasin.Two models,the early opening model and the limited modeling model,are suggested for resolving this paradox.The former suggests that the opening of the SW subbasin was in Late Eocene and earlier than the oldest sediment in the ZYBB.The latter proposes that the opening of the SW subbasin was limited to its northeastern portion,and did not extend to the southwest portion.The ZYBB is a rift basin survived from the spreading but subjected to severe syn-spreading magmatic disturbance.The SW subbasin and the ZYBB of the SCS provide a unique opportunity for studying the structural evolution and dynamic mechanism at the tip of a propagating seafloor spreading.Both models have unresolved questions,and further studies are needed.

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

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


    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.

  16. Structural style and Basin Formation in Deep-water Area of Northern South China Sea

    di, Z.; Zhen, S.; Xiong, P.; Min, C. C.


    In the deep-water area of northern South China Sea (SCS) developed a series of sedimentary basins. Active exploration for deep-water hydrocarbon has begun in these areas since this century. The well LW3-1-1 at water depth of 1480m in the BaiYun Sag (BYS) of the Pearl River Mouth Basin in 2006 discovered 56m layer of pure gas, demonstrated the good hydrocarbon potential of the area. Wide-angle seismic profiling has verified the transitional type of crust in the slope areas. The Moho surface shoals step-by-step from 30-29km under the shelf, ~15 km under the slope, and ~12km under the abyssal plain. Moho also rises beneath depocenters, mirroring the shape of sedimentary basement. The crustal thickness at the center of the BYS is Pacific Ocean towards the East Eurasian margin. The stress field in the East Eurasian margin changed abruptly in Late Cretaceous. Rifting started in the entire margin and eventually led to the opening of the SCS in late Early Oligocene. Large sedimentary basins developed in the margins of the SCS. Paleogene lacustrine sediments contain hydrocarbon sources, while traps are mostly found in Neogene marine strata. The structure of the northern SCS shows clear W-E variation, divided into NE-, NEE-, and NE-trending segments by two major NW-SE transfer faults. The Southern Depression of the Qiongdongnan Basin to the west is characterized by NE-trending half grabens. The BYS at the central segment is characterized by NEE-trending composite grabens and down warps with relatively small offset of boundary faults. To the east the Chaoshan Depression is composed of Mesozoic strata under very thin (deep-water basins is different from that of shallow-water basins. A study is ongoing to explore the basin formation mechanism, taking into account of the factors of abnormal lithosphere rheology, active mantle underplating and magmatic heating, lower crust flow, as well as the superposition of later extensional events. The study is supported by NSFC grants

  17. Clay minerals in surface sediments of the Pearl River drainage basin and their contribution to the South China Sea

    LIU ZhiFei; Christophe COLIN; HUANG Wei; CHEN Zhong; Alain TRENTESAUX; CHEN JianFang


    Clay minerals have played a significant role in the study of the East Asian monsoon evolution in the South China Sea by being able to track oceanic current variations and to reveal contemporaneous paleoclimatic changes prevailing in continental source areas. As one of the most important rivers inputting terrigenous matters to the northern South China Sea, the Pearl River was not previously paid attention to from the viewpoint of clay mineralogy. This paper presents a detailed study on clay minerals in surface sediments collected from the Pearl River drainage basin (including all three main channels,various branches, and the Lingdingyang in the estuary) by using the X-ray diffraction (XRD) method.The results indicate that the clay mineral assemblage consists dominantly of kaolinite (35%-65%),lesser abundance of chlorite (20%-35%) and illite (12%-42%), and very scare smectite occurrences (generally <5%). Their respective distribution does not present any obvious difference throughout the Pearl River drainage basin. However, downstream the Pearl River to the northern South China Sea, the clay mineral assemblage varies significantly: kaolinite decreases gradually, smectite and illite increase gradually. Additionally, illite chemistry index steps down and illite crystallinity steps up. These variations indicate the contribution of major kaolinite, lesser illite and chlorite, and very scarce smectite to the northern South China Sea from the Pearl River drainage basin. The maximum contribution of clay minerals from the Pearl River is 72% to the northern margin and only 15% to the northern slope of the South China Sea. In both glacials and interglacials, kaolinite indicates that the ability of mechanical erosion occurred in the Pearl River drainage basin.

  18. Occurrence and origin of carbon dioxide in the Fushan Depression, Beibuwan Basin, South China Sea

    Li, Meijun; Wang, Tieguan [Key Laboratory for Hydrocarbon Accumulation Mechanism of the Chinese Ministry of Education, Earth Sciences and Geoinformatics School, China University of Petroleum, Beijing 102200 (China); Liu, Ju; Wu, Weiqiang; Gao, Lihui [Petro China Southern Oil Exploration and Development Company, Guangzhou 510640 (China); Lu, Hong [Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)


    Natural gases produced from the Fushan Depression, Beibuwan Basin, South China Sea are generally rich in carbon dioxide. The {delta}{sup 13}C values of methane in these gases are within the range of -41.18 permille to -47.00 permille. This, together with the linearity of the {delta}{sup 13}C values of methane to butane in the ''natural gas plots,'' indicates that the hydrocarbon gases are of organic origin. The {delta}{sup 13}C{sub CO2} values of these gases are in the range of -5.1 permille to -7.5 permille, suggesting an inorganic origin. A dominant mantle source for the CO{sub 2} in these gases was determined on the basis of a simple binary mixing model using the {delta}{sup 13}C{sub CO2} values and {sup 3}He/{sup 4}He ratios of associated helium in these gases. The primary geological controls on the occurrence of CO{sub 2} rich gas accumulations in the Fushan Depression are discussed following a comparison with other sedimentary basins in the region. (author)

  19. Observation of Catastrophic Degassing from Mantle-Crust in Yinggehai Basin, South China Sea

    Chen Honghan; John Parnell; Gong Zaisheng; Li Sitian


    To lower the CO2 risk for hydrocarbon exploration in the west continental shelf of Yinggehai basin, South China Sea, we do attempt not only to know the CO2 origins, but also to make an understanding of the degassing processes from the mantle and crust. Based on the stable carbon isotope ratios of CO2 alone, the organic and inorganic CO2 can be successively distinguished, but the formation conditions and mixing processes for inorganic CO2 are still not clear. The relationships between lg[R(=3He/4He)/Ra(=1.386×10-6)] and CO2 content (%), CO2/3He and δ13CCO2 have been employed, respectively, to obtain that the CO2 gases in the reservoirs can be classified into three categories: (1) organic CO2 with very low contents but contaminated by mantle-derived helium; (2) inorganic CO2 gases with lower to higher contents being mixtures of crustal CO2 with mantle-derived CO2, the mantle-contributed percentage being in the range of 0 %-27 %, and (3) mainly crust-derived inorganic CO2 gases being characterized by high contents (more than 50 %) and indicating the crustal addition by metamorphism of rich-in carbon rocks in basement. Nevertheless, some CO2/3He ratios of organic CO2 fall into the range 108-1010, which made us inquire whether the CO2/3He=(1-10)×109 can be the unique signature of magmatic CO2 or not. All the observation of plutonic activities, fluid inclusion measurements in gas reservoirs, pre-stack depth/time seismic sections and the satellite infrared remote photography taken from Yinggehai basin, South China Sea, during Chichi earthquake in Taiwan on September 21, 1999, supports that the degassing processes are in a discontinuous mode, which may be triggered by igneous intrusion or extrusion, or earthquakes. In the central diapir zone of the basin, at least 3 to 4 orders of discharge of across-formational thermal fluid flows through fractures can be determined in different scales. The mantle degassing process may have a strong effect on overpressured system

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

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


    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

  1. Early Diagenesis Records and Pore Water Composition of Methane-Seep Sediments from the Southeast Hainan Basin, South China Sea

    Daidai Wu; Nengyou Wu; Ying Ye; Mei Zhang; Lihua Liu; Hongxiang Guan; Xiaorong Cong


    Several authigenic minerals were identified by XRD and SEM analyses in shallow sediments from the Southeast Hainan Basin, on the northern slope of South China Sea. These minerals include miscellaneous carbonates, sulphates, and framboidal pyrite, and this mineral assemblage indicates the existence of gas hydrates and a methane seep. The assemblage and fabric features of the minerals are similar to those identified in cold-seep sediments, which are thought to be related to microorganisms foste...

  2. Spatial heterogeneity and transboundary pollution: a contingent valuation study on the Xijiang River drainage basin in south China

    Jie He; Anping Huang; Luodan Xu


    This article examines whether and how transboundary river water pollution spillover may affect resident’s Willingness to Pay (WTP) for a river water quality improvement project. Based on a CVM survey conducted in 20 cities located in the Xijiang river basin located in south China, our study demonstrates that the downstream city respondents report lower WTP when the water quality in the immediate upstream city is more polluted. This negative externality decreases with distance and relative b...

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

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


    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.

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

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


    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.

  5. The Paleo-Orientations of Northwestern Borneo and Adjacent South China Sea Basins

    H. D. Tjia


    Full Text Available DOI: 10.17014/ijog.v7i2.136Limited paleomagnetic data from West Kalimantan and southwestern Sarawak appear to indicate counter-clockwise (CCW rotation of over 50 degrees during Cenozoic. On the other hand, similar studies from Sabah show conflicting results in terms of paleo-positions. This CCW information and other plate tectonic considerations have formed the base of Southeast Asia’s plate reconstructions that have seen print in a number of updated versions. The existing publications on extensive field and exploration data, including geological stress fields from wellbore breakouts, on northwestern Borneo and basins of South China Sea have not been taken into account. The latter wealth of information already established that the region under discussion consists of a mosaic-like assemblage of diverse tectono-stratigraphic terranes, each with separate tectonic development. Stress fields changed in different ways in the different terranes indicating definitively that regional, progressive CCW rotation of Borneo is not possible.

  6. The distribution of dimethylcarbazoles in oils from the Pearl River Mouth Basin, South China Sea

    ZHANG Chunming; ZHAO Hongjing; GAO Kunshun; YANG Shaokun


    C2-carbazole isomers have been investigated in crude oils from the Hui-Liu Structure Ridge (HLSR) in the Pearl River Mouth Basin (PRMB), South China Sea. The NH shielded isomer, as well as the NH partially shielded isomers, was detected in high abundance and the NH exposed isomers in lower abundance. A small-enrichment trend of 1,8-dimethylcarbazole (DMC) was observed in crude oils along the western part of HLSR (WPHLSR), which may indicate little effect of migration on the C2-carbazole distributions. Two strikingly different distribution patterns of NH partially shielded isomers were observed in the reservoirs along the WPHLSR: one with a preference of 1,3- and 1,6-DMCs and the other with a preference of 1,4- and 1,5-DMCs. All of the oils occurring in the Upper reservoirs have a preference of 1,3- and 1,6-DMCs, whereas those trapped in the Lower reservoirs show a preference of 1,4- and 1,5-DMCs, which may indicate there are two petroleum migration systems in the WPHLSR.

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

    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

  8. Moho structure of the South China Sea basin and the surrounding from constrained 3-D gravity inversion

    Zhaocai, W.; Jinyao, G.


    We have obtained the Moho depth of the South China Sea basin using gravity data with the 191 control points from seismic data and sonobuoys. To obtain the residual mantle Bouguer anomaly (RMBA), we deducted the anomaly from lateral changes in bathymetry or topography, the gravity anomaly due to changes in sediment thickness and density from the free air anomaly firstly, and then corrected the lithosphere thermal gravity anomaly from the rifted margin to the spread ridge. According to the relationship between the control points and RMBA, we calculated the initial Moho depth, from which, we done an iterative cycle of gravity inversion to predict the final Moho depth and crustal thickness. To calculate the lithosphere thermal gravity anomaly, we defined a critical thinning factor for the initiation of oceanic crust production, and a maximum oceanic crustal thickness; for this study area, values of 0.5 and 9 km were used respectively, consistent with the Moho depth of 20km and 14km respectively, with the initial thickness of continental crust of 32km. The RMS(root mean square) difference with the control points is 1.54km. Over most of the South China Sea basin, the Moho depth is 11 and 13km, the crustal thickness is 5-8km. The Moho depth of the Northwest sub basin has values between 12 and 13km, the crustal thickness is mostly ~7km. The NW trending fault divides obviously the extinct spreading centers of the East and southwest sub basin. Meanwhile, on the north side of the two sub basin extinct spreading centers, the crustal thickness is slightly thicker 1km than the south. The ocean-continent transition (OCT) is enclosed by the 14km and 20km Moho depth contour. At the East sub basin, the OCT shows asymmetry, and is broader and longer on the northern margin than the southern margin. One of the most noticeable characteristics in the northeastern margin of the OCT is that the crustal thickness is 10-16km. However, at the southwest sub basin, the OCT is symmetrical.

  9. Evidence for episodic expulsion of hot fluids along faults near diapiric structures of the Yinggehai Basin, South China Sea

    Xinong Xie; Sitian Li [China University of Geosciences, Wuhan (China). College of Earth Resources; Weiliang Dong; Zhongliang Hu [China Offshore Oil Nanhai West Corp., Zhanjiang (China)


    Diapiric structures are well developed and occur in most of the central part of the Yinggehai Basin, on the western side of the South China margin. A strong thermal anomaly due to hot fluid flows occurs in the diapiric zone, as evidenced from vitrinite reflectance (R{sub o}), clay mineral transformation, and fluid inclusion homogenization temperatures. This anomaly results from hydrothermal fluid flow along vertical faults from overpressured compartments into the overlying Late Miocene and Quaternary sand-rich layers. The magnitude of thermal anomaly is related not only to the distance to which the vertical fault is hydraulically open, but the permeability of rocks interconnected with the faults. Intense heat transfer for convection of fluids occurs in the sand-rich intervals adjacent to vertical faults. Abnormal organic-matter maturation, together with rapid transformation of clay minerals, which occurs at certain intervals within the present-day normally pressured system and normal conductive temperatures in a diapir, can be used to identify palaeo high pressure zones. Abnormal high temperatures measured from a drill-stem test in a diapir can be inferred to be the results of recent expulsion of hydrothermal fluid flow. The results of this study suggest that thermal fluid expulsion along faults plays an important role in the modification of thermal regimes, the enhancement of organic-matter maturation, and rapid transformation of clay minerals, as well as the accumulation of hydrocarbons in diapiric structures of the Yinggehai Basin, South China Sea. (author)

  10. South China Sea Challenge


    China's attempts to solve disputes with ASEAN over the South China Sea help regional peace China's marine economy and security are currently faced with new challenges, requiring careful handling, especially in disputes with ASEAN countries and in promoting common development of the South China Sea. The outcome of how this is dealt with could undoubtedly pave the way for solutions to other oceanic disputes. The South China Sea is located south of

  11. Seismic sequence and depositional evolution of slope basins in mid-northern margin of the South China Sea

    LI Mingbi; JIN Xianglong; LI Jiabiao; DING Weiwei; FANG Yinxia; LIU Jianhua; TANG Yong


    As one of the biggest marginal seas in the western Pacific margin,the South China Sea (SCS) experienced continental riffing and seafloor spreading during the Cenozoic.The northern continental margin of the SCS is classified as a passive continental margin.However,its depositional and structural evolution remains controversial,especially in the deep slope area.The lack of data hindered the correlation between continental shelf and oceanic basin,and prevented the establishment of sequence stratigraphic frame of the whole margin.The slope basins in the mid-northern margin of SCS developed in the Cenozoic;the sediments and basin infill recorded the geological history of the continental margin and the SCS spreading.Using multi-channel seismic dataset acquired in three survey cruises during 1987 to 2004,combined with the data of ODP Leg 184 core and industrial wells,we carried out the sequence stratigraphic division and correlation of the Cenozoic in the middle-northern margin of SCS with seismic profiles and sedimentary facies.We interpreted the seismic reflection properties including continuity,amplitude,frequency,reflection terminals,and 15 sequence boundaries of the Cenozoic in the study area,and correlated the well data in geological age.The depositional environment changed from river and lake,shallow bay to open-deep sea,in correspondence to tectonic events of syn-rifting,early drifting,and late drifting stages of basin evolution.

  12. Early Pleistocene hominid teeth recovered in Mohui cave in Bubing Basin, Guangxi, South China

    WANG Wei; Richard Potts; HOU Yamei; CHEN Yunfa; WU Huaying; YUAN Baoyin; HUANG Weiwen


    Two hominid teeth recovered in Mohui cave are morphologically distinguished from Australopithecus in Africa, but close to Homo erectus in China. These teeth are therefore provisionally assigned to Homo erectus. The associated mammalian fauna include Gigantopithecus blacki, Nestoritherium sp., Sus xiaozhu, Sus peii and Ailuropoda microta, which are typical early Pleistocene taxa in South China. The general characteristics of the Mohui faunal assemblage are similar to the Longgupo site, which is dated to 2 Ma, implying a contemporaneity for the two sites. To date, compared with the discoveries in Africa, far fewer early Pleistocene hominid fossils have been recovered in Asia, and there are intensive controversies concerning their stratigraphic provenience and typological and temporal positions. The hominid fossils from Mohui cave, with their reliable biostratigraphic positions and distinct typological features, provide important evidence regarding the issue of early human origins and evolution.

  13. Thermal and cementation histories of Permian shelf-edge carbonate rocks in the Nanpanjiang Basin, South China

    Halley, Robert B.; Parrish, Judith T.; Zahn, Xie; Wenhai, Hu; Scholle, Peter A.; Zhongrui, Su; Yirong, Zhang; Yunming, Huang; Guangxuan, Li


    As of 1984, the Nanpanjiang Basin of South China has had almost no exploration by drilling although oil seeps exist among its margins and producing wells occur in adjacent basins.  however, cooperative studies by petroleum geologists and geochemists of the United States and the People's Republic of China (1982-1984) show that calcite-cemented reef and fore-reef carbonate rocks near Ziyun contain bitumen in Upper Permian shelf-edge sediment.  the cementation history consists of three episodes: (1)precipitation of syndepositional marine cement (formerly botryoidal aragonnite and fibrous magnesian calcite); (2)precipitation of post-depositional early cement (radiaxial calcite); and (3)precipitation of late burial cement (white calcite spar).  Hydrocarbons were introduced into the rocks between cementation episodes 2 and 3.  Fluid inclusion analysis of secondary inclusions in the burial cement indicates that the rocks were heated to nearly 200 C after hydrocarbon migration and cementation episode 3.  Bitumen remains in the rocks as evidence of the earlier presence of liquid hydrocarbons.

  14. 40Ar/39Ar ages of seamount trachytes from the South China Sea and implications for the evolution of the northwestern sub-basin

    Xiaohu Li; Jiabiao Li; Xing Yu; Chunsheng Wang; Fred Jourdan


    A chronological study of seamount rocks in the South China Sea basin provides a great opportunity to understand the expansion and evolution history of the sea basin. In this paper, we analyzed the 40Ar/39Ar age of trachytic samples collected from the Shuangfeng seamounts in the northwestern sub-basin of the South China Sea. The two samples yielded plateau ages of 23.80 ? 0.18 and 23.29 ? 0.22 Ma, respectively, which indicate magmatic activity in late Oligocene which helpful constraints the expansion time of the northwest sub-basin. Previous studies suggested that the northwestern sub-basin and southwestern sub-basin have experienced a relatively consistent expansion in the NWeSE direction followed by a late expansion of the eastern sub-basin. We concluded that the expansion of the northwestern sub-basin began prior to ca. 24 Ma, which also implicated magmatic events of a late or stop expansion of the northwestern sub-basin combined with our results of 40Ar/39Ar age data and previous geophysical data.

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

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


    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.

  16. Early Diagenesis Records and Pore Water Composition of Methane-Seep Sediments from the Southeast Hainan Basin, South China Sea

    Daidai Wu


    Full Text Available Several authigenic minerals were identified by XRD and SEM analyses in shallow sediments from the Southeast Hainan Basin, on the northern slope of South China Sea. These minerals include miscellaneous carbonates, sulphates, and framboidal pyrite, and this mineral assemblage indicates the existence of gas hydrates and a methane seep. The assemblage and fabric features of the minerals are similar to those identified in cold-seep sediments, which are thought to be related to microorganisms fostered by dissolved methane. Chemical composition of pore water shows that the concentrations of SO42-, Ca2+, Mg2+, and Sr2+ decrease clearly, and the ratios of Mg2+ to Ca2+ and Sr2+ to Ca2+ increase sharply with depth. These geochemical properties are similar to those where gas hydrates occur in the world. All results seem to indicate clearly the presence of gas hydrates or deep water oil (gas reservoirs underneath the seafloor.

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

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


    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.

  18. South China Sea


    Chinese Foreign Minister Yang Jiechi warned against attempts to "in-ternationalize" the issue of the South China Sea, where China has territorial disputes with some ASEAN member states, including Viet Nam and the

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

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


    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.

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

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


    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

  1. Characteristics and Origin of Yacheng Gas Field in Qiongdongnan Basin, South China Sea


    The Yacheng gas field lies in the foot wall of the No. 1 fault, the boundary fault between the Yinggehai and Qiongdongnan basins. An overpressured system developed in the Meishan Formation near the No. 1 fault in the gas field and in the adjacent Yinggehai basin. Away from this fault into the Qiongdongnan basin, the overpressure diminishes. Below 3 600 m in the gas field, an obvious thermal anomaly occurs. The gases show obvious compositional heterogeneities which reflect reservoir-filling process and origin of the gas field. The gas field was charged from both the Qiongdongnan and the Yinggehai basins but mainly from the former. Hydrocarbons sourced from the Qiongdongnan basin have relatively low maturities while hydrocarbons from the Yinggehai basin have relatively high maturities.

  2. Formation mechanism of the Qiongdongnan basin northwest of the South China Sea-dating the sinistral slip of the Red River Fault Zone

    Sun, Z.; Jiang, J.; Xie, W.


    Locating on the northwestern margin of the South China Sea, the Qiongdongnan basin is a NE-trending rift zone in general. Bounding with the NW-trending Yinggehai basin and the Red River- East Vietnam Fault Zone to the west, the evolution of the Qiongdongnan basin bears large amounts of information about the slip of the Red River Fault zone. Combined the geological analysis with analogue modeling experiments, we suggest that the evolution of the Qiongdongnan is controlled not only by the southeastward to south southeastward extension, but also by the sinistral slip of the Red River Fault zone. The central depression of the Qiongdongnan basin is controlled mainly by the southeastward to south southeastward extension, while the southern depression developed under the combined stress filed of southeastward extension and the dextral slip along the NNW-trending Red River fault zone. The northern depression was formed by the combined effect of the sinistral slip along the Red River Fault Zone and the southeastward extension. According to the age of the shear fault starting to develop in the southwest of the Qiongdongnan basin, as well as the age for the northwestern part to develop, the sinistral slip of the Red River Fault zone began around early oligocene, later than the rifting of the Qiongdongnan basin. The sinistral slip rate of the Red River Fault zone during early Oligocene may be smaller than the displacement rate of the Qiongdongnan basin, but become reversed thereafter, which in turn caused tectonic inversion and folding along the western segment of the Qiongdongnan basin, and NW- to NNW-trending Rediel faults from late Oligocene to middle Miocene. Through the deformation history of the Qiongdongnan basin, we defined the sinistral slip stage Indochina along the Red River Fault zone from about 36Ma to 16Ma, and further a rapid slip occurring after 30Ma.

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

    Niu, Jun; Sivakumar, Bellie; Chen, Ji


    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.

  4. Study on Basin-Filling and Reservoir Sedimentology of Zhu Ⅲ Depression of Pearl River Mouth Basin, South China Sea


    Through basin-filling analysis, one coarsening-upward and two fining-upward sequences have been identified in Zhu Ⅲ depression. In accondance with the general model proposed by Ravnas and Steel (1998), the basin-filling has two large cycles-rift (sediment-balanced and -overfilied)and postrift (sediment-underfilled and -starved). During the rifting process, the rifted lake developed through three stages: early, climax and late. The sedimentary characteristics of reservoir rocks show that barrier bar, lagoon and tidal channel facies well developed in Zhuhai Formation;offshore, tidal and barrier bar well developed in Zhujiang Formation. Neighborly, Shenhu , Wenchang and Enping formations deposited in rifted lakes during Paleogene time ; Zhujiang Formation deposited in bay, lagoon and shorefnce in late Paleogene. Zhujiang and other formations deposited in offshore and open shallow sea to shelf.

  5. Preferential Petroleum Migration Pathways in Eastern Pearl River Mouth Basin,Offshore South China Sea

    Yu Jianning; Zou Huayao; Gong Zaisheng


    Secondary petroleum migration in the eastern Pearl River Mouth basin was modeled using the three-dimensional PATHWAYSTM model,which assumes that the positions of petroleum migration pathways are controlled by the morphology of the sealing surfaces.The modeling results have accurately predicted the petroleum occurrences.Most commercial petroleum accumulations are along the predicted preferential petroleum migration pathways (PPMP),and most large fields (petroleum reserves greater than 1×108 t) have more than one preferential petroleum migration pathways to convey petroleum to the traps.The lateral migration distance for oil in the LH11-1 field,the largest oilfield so far discovered in the Pearl River Mouth basin,was more than 80 km.The case study suggests that in lacustrine fault basins,petroleum can migrate over a long distance to form large oilfields without driving force from groundwater flow.The focusing of petroleum originating from a large area of the generative kitchens into restricted channels seems to be essential not only for long-range petroleum migration in hydrostatic conditions,but also for the formation of large oil or gas fields.The strong porosity and permeability heterogeneities of the carrier beds and the relatively high prediction accuracy by a model that does not take into consideration of the effect of heterogeneity suggest that the positions of petroleum migration pathways in heterogeneous carrier beds with relatively large dipping angles are determined primarily by the morphology of the sealing surfaces at regional scales.

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

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


    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

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

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


    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.

  8. South China Sea

    Morton, Brian [Hong Kong Univ., Swire Inst. of Marine Science, Hong Kong (China); Hong Kong Univ., Dept. of Ecology and Biodiversity, Hong Kong (China); Blackmore, Graham [Hong Kong Univ. of Science and Technology, Dept. of Biology, Hong Kong (China)


    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 workshops and conference documents that are not available to the wider scientific community. The South China Sea has an area of some 3.3 million km{sup 2} and depths range from the shallowest coastal fringe to 5377m 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 economics 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

  9. The South China Sea Deep: Introduction

    Wang, Pinxian; Li, Qianyu; Dai, Minhan


    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).

  10. Post-rift tectonic reactivation and its effect on deep-water deposits in the Qiongdongnan Basin, northwestern South China Sea

    Mao, Kainan; Xie, Xinong; Xie, Yuhong; Ren, Jianye; Chen, Hui


    The post-rift evolution of extensional basins is traditionally thought to be dominated by thermal subsidence due to cessation of the major fault activity during the post-rift stage. The Qiongdongnan Basin, which is located in the northwestern continental margins of the South China Sea, has exhibited significant deviations from typical post-rift characteristics. In the basin, a distinct tectonic reactivation occurred since the Late Miocene (11.6 Ma). Three notable aspects of the observed tectonic reactivation during the post-rift stage include, (1) pre-existing fault reactivation, (2) multiple large-scale magmatic intrusions, and (3) rapid post-rift subsidence. During this period the basin infill significantly changed in depositional environments shifting rapidly from littoral-neritic to bathyal-abyssal environments since Late Miocene. The pre-existing fault activity along the No. 2 fault of the basin resulted in the formation of initial shelf breaks and led to the development of continental slope. In addition, the pre-existing faults along the Central Depression zone created a small sub-basin with distinctive axial negative topography characteristics formed between structural highs. These geomorphological changes led to the formation of the Central Canyon. Large-scale magmatic intrusions occurred along the fault zone in the Central Depression of the basin during the post-rift stage. Those deviations, as evidenced from pre-existing fault reactivation, magmatic intrusions, and rapid post-rift subsidence in the Qiongdongnan Basin is believed to be related to the Hainan Plume event.

  11. Petroleum Exploration Prospects in Erlian Basin,China

    Fei Baosheng


    @@ Erlian Basin is located in the middle prairie,Inner Mongolia Autonomous Region, the north border of China. Teetonieally, Erlian Basin is to the south of Bayinbaoligel Uplift and the north is the Wendouer Temple Uplift. In the east of the basin, there is Daxinganling Uplift and the west is Soulunshan Uplift. The basin covered an area of 100 000 km2, is a Mesozoic Cenozoic graben (rift)basin that evolved on the folded basement of Heveynian geosyncline.

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

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


    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.

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

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


    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.

  14. Types, Evolution and Pool-Controlling Significance of Pool Fluid Sources in Superimposed Basins: A Case Study from Paleozoic and Mesozoic in South China

    Xu Sihuang; Mei Lianfu; Yuan Caiping; Ma Yongsheng; Guo Tonglou


    Having multiple tectonic evolution stages, South China belongs to a superimposed basin in nature. Most marine gas pools became secondary pools. The pool fluid sources serve as the principal pool-controlling factors. On the basis of eight typical petroleum pools, the type, evolution in time-space,and the controlling of petroleum distribution of pool fluid sources are comprehensively analyzed. The main types of pool fluid sources include hydrocarbon, generated primarily and secondly from source rocks, gas cracked from crude oil, gas dissolved in water, inorganic gas, and mixed gases. In terms of evolution, the primary hydrocarbon was predominant prior to Indosinian; during Indosinian to Yenshanian the secondary gas includes gas cracked from crude oil, gas generated secondarily, gas dissolved in water, and inorganic gas dominated; during Yenshanian to Himalayan the most fluid sources were mixed gases. Controlled by pool fluid sources, the pools with mixed gas sources distributed mainly in Upper Yangtze block, especially Sichuan (四川) basin; the pools with primary hydrocarbon sources distributed in paleo-uplifts such as Jiangnan (江南), but most of these pools became fossil pools; the pools with secondary hydrocarbon source distributed in the areas covered by Cretaceous and Eogene in Middle-Lower Yangtze blocks, and Chuxiong (楚雄), Shiwandashan (十万大山), and Nanpanjiang (南盘江) basins; the pools with inorganic gas source mainly formed and distributed in tensional structure areas.

  15. South Bohemian basins

    Spudil, J.; Brož, B.; Dašková, Jiřina; Holcová, K.; Kvaček, Z.; Pešek, J.; Svobodová, Marcela; Sýkorová, Ivana; Teodoridis, V.

    Prague: Czech Geological Survey, 2014, s. 190-206 ISBN 978-80-7075-862-5 R&D Projects: GA ČR GA105/06/0653 Institutional support: RVO:67985891 ; RVO:67985831 Keywords : Tertiary basins * Czech Republic * Cenomanian and Tertiary lignite * geology * stratigraphy Subject RIV: DB - Geology ; Mineralogy

  16. Sequence Stratigraphy and Sedimentary Facies of Lower Oligocene Yacheng Formation in Deepwater Area of Qiongdongnan Basin, Northern South China Sea:Implications for Coal-Bearing Source Rocks

    Jinfeng Ren; Hua Wang; Ming Sun; Huajun Gan; Guangzeng Song; Zhipeng Sun


    -bearing characteristics in the lower exploration deepwater area of South China Sea.

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

    Pubellier, Manuel; Sautter, Benjamin


    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

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

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


    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.

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

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


    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.

  20. A preliminary biogeochemistry-based quantification of primary productivity of end-Permian deep-water basin in Dongpan Section ,Guangxi ,South China

    ZHANG Yang; HE Weihong; FENG Qinglai


    In this Paper,the mean primary productivity of the Talung Formation in the deep-water basin(50-500 m depth)of Dongpan,Guangxi,South China,was calculated,of the content of the trace element Cu.Results showed that the primary productivity obtained was comparable with the previously-reported data for the black shale of the Phosphoria Formation,a Permian phosphate deposit in the northwest United States,and also similar to that of the modern deposit in the Cariaco basin,Venezuela.It was observed that the primary productivity increased with the enhanced abundance of algae and photosynthetic bacteria,and with the decrease in both the radiolarian individuals and the body size of brachiopods during the faunal mass extinction.This ecological coupling indicates that the changes of primary productivity are closely related to the propagation and the decline of producers(algae and bacteria),and that consumers(radiolarians and brachiopods)probably have little influence on the changes of primary productivity.

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

    Ding, Weiwei; Li, Jiabiao; Clift, Peter


    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.

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

    Wu, Yiping; Chen, Ji


    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.

  3. A comparison study of summer-time synoptic-scale waves in South China and the Yangtze River basin using the TRMM Multi-Satellite Precipitation Analysis daily product


    Summer-time synoptic-scale waves in South China and the Yangtze River basin are quantified and compared by means of analyzing the 6-year (1998―2004) TRMM Multi-Satellite Precipitation Analysis (TMPA) daily product. An innovative 3-dimensional spectrum analysis method is applied. The results indicate that synoptic-scale waves appearing in South China prominently propagate westward within a zonal wavenumber range of 9―21 and a frequency range of-0.12―-0.22 cycles day-1, while those in the Yangtze River basin primarily move eastward with the same characteristic wavenumbers of 9―21, but within a frequency range of 0.2―0.29 cycles day?1. Zonal and meridional distributions, and seasonal variations of these waves are further explored and compared. It shows that summer-time synoptic-scale waves in the South China result from the northward migration and oscillation of the Intertropical Convergence Zone (ITCZ) in the western Pacific, whereas the ones in the Yangtze River basin are generally related to the synoptic troughs within the westerly flow, originating from the Qinghai-Tibet Plateau.

  4. A comparison study of summer-time synoptic-scale waves in South China and the Yangtze River basin using the TRMM Multi-Satellite Precipitation Analysis daily product


    Summer-time synoptic-scale waves in South China and the Yangtze River basin are quantified and compared by means of analyzing the 6-year (1998-2004) TRMM Multi-Satellite Precipitation Analysis (TMPA) daily product. An innovative 3-dimensional spectrum analysis method is applied. The results indicate that synoptic-scale waves appearing in South China prominently propagate westward within a zonal wavenumber range of 9-21 and a frequency range of -0.12--0.22 cycles day?1, while those in the Yangtze River basin primarily move eastward with the same characteristic wavenumbers of 9-21, but within a frequency range of 0.2-0.29 cycles day-1. Zonal and meridional distributions, and seasonal variations of these waves are further explored and compared. It shows that summer-time synoptic-scale waves in the South China result from the northward migration and oscillation of the Intertropical Convergence Zone (ITCZ) in the western Pacific, whereas the ones in the Yangtze River basin are generally related to the synoptic troughs within the westerly flow, originating from the Qinghai-Tibet Plateau.

  5. 3D seismic structure of the Zhenbei-Huangyan seamount chain in the East sub-basin of the South China Sea and its mechanism of formation

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


    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

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

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


    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

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

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


    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.

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

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


    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.

  9. Tectonic Evolution of China and Its Control over Oil Basins

    Wang Hongzhen; Li Sitian


    This paper is a brief review of the tectonic frame and crustal evolution of China and their control over the oil basins. China is subdivided into three regions by the Hercynian Ertix-Almantai (EACZ) and Hegenshan (HGCZ) convergent zones in the north, and the Indosinian Muztagh-Maqen (MMCZ) and the Fengxiang-Shucheng (FSCZ) convergent zones in the south. The northern region represents the southern marginal tract of the Siberian platform. The middle region comprises the Sino-Korea (SKP), Tarim (TAP) platforms and surrounding Paleozoic orogenic belts. The southern region includes the Yangtze platform (YZP), the Cathaysia (CTA) paleocontinent and the Caledonides between them in the eastern part, and the Qinghai-Tibet plateau composed of the Gondwana-affiliated massifs and Meso- and Cenozoic orogenic belts in the western part. The tectonic evolutions of China are described in three stages: Jinningian and pre-Jinningian, Caledonian to Indosinian, and post-Indosinian. Profound changes occurred at the end of Jinningian (ca. 830 Ma) and the Indosinian (ca. 210 Ma) tectonic epochs, which had exerted important influence on the formation of different types of basins. The oil basins distribute in four belts in China, the large superimposed basins ranging from Paleozoic to Cenozoic (Tarim and Junggar) in the western belt, the large superimposed basins ranging from Paleozoic to Mesozoic (Ordos and Sichuan) in the central belt, the extensional rift basins including the Cretaceous rift basins (Songliao) and the Cenozoic basin (Bohaiwan) in the eastern belt, and the Cenozoic marginal basins in the easternmost belt in offshore region. The tectonic control over the oil basins consists mainly in three aspects: the nature of the basin basement, the coupling processes of basin and orogen due to the plates interaction, and the mantle dynamics, notably the mantle upwelling resulting in crustal and lithospheric thinning beneath the oil basins.

  10. 南沙海域礼乐盆地沉积过程和演化%Depositional Process and Evolution of Liyue Basin in Southern South China Sea

    李鹏春; 赵中贤; 张翠梅; 谢辉; 陈广浩


    The evolution of rift-drift-subsidence can usually be illuminated by sedimental style, subsidence history and structural style, so it's possible to understand basin evolution through analysis of depositional process and coupling tectonic-sedimentary. In this paper, infill stratigraphy, subsidence history and structural characteristics are analyzed. The results show that Liyue basin is characterized by typical "tow-layer" structural pattern, which is separated by a regional breakup unconformity (T60). The horsts and grabens are in low basin overlain by upper depressions of the Neogene. And the half-grabens characterized by asymmetric wedge-shape are bounded by both normal faults and large-scale listric faults, which controlled the sedimentary cy cles. The subsidence method is mainly tectonic subsidence before 23. 8 Ma but is thermal subsidence after Late Oligocene. There were three regional subsidence episodes, and each subsidence rate was from slow to fast. Liyue basin is primarily composed of three regressive cycles of rift infilling influenced by regional tectonic, which correspond to three stages of basin development. The first stage, characterized by extensional stress, is related to early rift development from approximately 45 Ma until Early Oligocene. Featured by both extension and strike-slip stress, the second is associated with rift-drift development from initiation of sea floor spreading in South China Sea at 30 Ma until the end of sea floor spreading at Middle Miocene. And the third is late post-rift subsidence from approximately 16 Ma until 5. 5 Ma, which is controlled by transpressive stress field.%礼乐盆地所经历的张裂-漂移-碰撞沉降构造历史,在沉积物沉积样式、沉降历史及断裂构造样式中均有反映,因此,分析盆地沉积过程及其与构造的耦合关系可揭示其演化过程.通过对礼乐盆地沉积充填过程、沉降方式及构造特征的分析,认为礼乐盆地具双层结构模式特征,以T60

  11. Evaluation of abundant hydrocarbon-generation depressions in the deepwater area of Qiongdongnan Basin, South China Sea

    LIU Zhen; SUN Zhipeng; WANG Zisong; ZHANG Wei; LI Tingan; HE Weijun; LI Fengxia


    It has been confirmed that the key source rocks of Qiongdongnan Basin are associated with the Yacheng Formation, which was deposited in a transitional marine-continental environment. Because the distribution and evolution patterns of the source rocks in the major depressions are different, it is important to determine the most abundant hydrocarbon-generation depressions in terms of exploration effectiveness. Based on an analysis of organic matter characteristics of the source rocks, in combination with drilling data and seismic data, this paper establishes a model to evaluate the hydrocarbon-generation depressions in the deepwater area of Qiongdongnan Basin. First of all, by using the method of seismic-facies model analysis, the distribution of sedimentary facies was determined. Then, the sedimentary facies were correlated with the organic facies, and the distribution of organic facies was predicted. Meanwhile, the thickness of source rocks for all the depressions was calculated on the basis of a quantitative analysis of seismic velocity and lithology. The relationship between mudstone porosity and vitrinite reflectance (Ro) was used to predict the maturity of source rocks. Second, using the parameters such as thickness and maturity of source rocks, the quantity and intensity of gas generation for Yacheng and Lingshui Formations were calculated. Finally, in combination with the identified hydrocarbon resources, the quantity and intensity of gas generation were used as a guide to establish an evaluation standard for hydrocarbon-generation depressions, which was optimized for the main depressions in the Central Depression Belt. It is proposed that Lingshui, Ledong, Baodao and Changchang Depressions are the most abundant hydrocarbon depressions, whilst Songnan and Beijiao Depressions are rich hydrocarbon depressions. Such an evaluation procedure is beneficial to the next stage of exploration in the deep-water area of Qiongdongnan Basin.

  12. CFD simulation on the generation of turbidites in deepwater areas:a case study of turbidity current processes in Qiongdongnan Basin, northern South China Sea

    JIANG Tao; ZHANG Yingzhao; TANG Sulin; ZHANG Daojun; ZUO Qianmei; LIN Weiren; WANG Yahui; SUN Hui; WANG Bo


    Turbidity currents represent a major agent for sediment transport in lakes, seas and oceans. In particu-lar, they formulate the most significant clastic accumulations in the deep sea, which become many of the world’s most important hydrocarbon reservoirs. Several boreholes in the Qiongdongnan Basin, the north-western South China Sea, have recently revealed turbidity current deposits as significant hydrocarbon res-ervoirs. However, there are some arguments for the potential provenances. To solve this problem, it is es-sential to delineate their sedimentary processes as well as to evaluate their qualities as reservoir. Numerical simulations have been developed rapidly over the last several years, offering insights into turbidity current behaviors, as geologically significant turbidity currents are difficult to directly investigate due to their large scale and often destructive nature. Combined with the interpretation of the turbidity system based on high-resolution 3D seismic data, the paleotophography is acquired via a back-stripping seismic profile integrated with a borehole, i.e., Well A, in the western Qiongdongnan Basin; then a numerical model is built on the basis of this back-stripped profile. After defining the various turbidity current initial boundary conditions, includ-ing grain size, velocity and sediment concentration, the structures and behaviors of turbidity currents are investigated via numerical simulation software ANSYS FLUENT. Finally, the simulated turbidity deposits are compared with the interpreted sedimentary bodies based on 3D seismic data and the potential provenances of the revealed turbidites by Well A are discussed in details. The simulation results indicate that a sedimen-tary body develops far away from its source with an average grain size of 0.1 mm, i.e., sand-size sediment. Taking into account the location and orientation of the simulated seismic line, the consistence between normal forward simulation results and the revealed cores

  13. Implementing Integrated River Basin Management in China

    Lifeng Li


    Full Text Available This paper examines the role of the World Wildlife Fund for Nature China as policy entrepreneur in China. It illustrates the ways in which the World Wildlife Fund for Nature is active in promoting integrated river basin management in the Yangtze River basin and how the efforts at basin level are matched with the advice of the China Council for International Cooperation on Environment and Development task force on integrated river basin management to the national government of China. This article demonstrates that the World Wildlife Fund for Nature uses various strategies of different types to support a transition process towards integrated river basin management. Successful deployment of these strategies for change in environmental policy requires special skills, actions, and attitudes on the part of the policy entrepreneur, especially in China, where the government has a dominant role regarding water management and the position of policy entrepeneurs is delicate.

  14. Sustainable Building in South China



    In view of sustainable building prioritized as a strategic sector by local government in South China, and the strong Dutch expertise and wide market recognition in this field especially the substantive presence of the Shanghai-based Dutch Sustainable Building Platform, the market in the South could be very potential and interesting to Dutch companies though strong competitors as well. An overview is given of the developments in the Chinese province Guangdong, Shenzhen city, Guangzhou City, Fujian Province, Guangxi Zhuang Autonomous Region, Hainan Province. Also information is given about important potential counterparts: China Merchant Group, Guangdong Energy Conservation Association, and potential areas for cooperation.

  15. Cretaceous Phytoplankton Assemblages from Songke Core-1, North and South (SK-1, N and S) of Songliao Basin, Northeast China

    ZHANG Yiyi; BAO Lina


    Cretaceous phytoplankton from the newly completed core hole (SK-1, N&S) in the central Songliao Basin was studied. The target interval is from the upper Quantou Formation of Upper Cretaceous to Mingshui Formation. Twelve genera of dinoflagellates, six of acritarcha and three of chlorophyta were identified in 588 samples from the 2300-m deep core. Ten phytoplankton assemblages have been classified: Tetranguladinium-Subtilisphaera.Botryococcus,Botryococcus-Pediastrum,Pediastrum,Dinogymniopsis-Chlamydophrella-Vesperopsis bifurcate, Dinogymniopsis minor-Balmula,Pediastrum-Botryococcus,Schizosporis-Campenia,Kiokansium-Dinogymniopsis.Botryococcus,Dinogymniopsis.Granodiscus.Filisphaeridium and Granodiscus. According to the findings mentioned above, the age of the upper Qantou Formation is Cenomanian, the Qingshankou Formation belongs to upper Cenomanian-Turonian, the Yaojia Formation to Coniancian-Santonian age, the Nenjiang Formation is of Campanian age, and Sifangtai-Mingshui formations are referred to Maastrichtian stage. The ecology of phytoplankton is closely related to water salinity. Each type of phytoplankton is within a certain living water mass whose evolution type reflects salinity change of the Songliao Lake. The assemblages from the SK-1 indicate that water salinity changes with the cycle of freshwater-slight brackish water-brackish water-slight brackish water-freshwater in the lake.

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

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


    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

  17. Dynamics Analysis of the Baiyun Sag in the Pearl River Mouth Basin,North of the South China Sea

    SUN Zhen; ZHONG Zhihong; ZHOU Di; PANG Xiong; HUANG Chunju; CHEN Changmin; HE Min; XU Hehua


    The Baiyun sag is a deep one developing on the slope of the Pearl River Mouth Basin.It occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift.Vertically, the sedimentary architecture could be divided into three layers, i.e.the faulted layer on the bottom, the faulted-ductile stretching layer in the middle and the draping layer on the top. The main rifting stage of the sag is supposed to be characterized by ductile extension and thinning of the crust. The special deformation pattern is probably attributed to the fact that the Baiyun sag is located in the transfer zone of the pre-existing weak zone, which made the sag a strongly deformed area,characterized by the greatly thinned lithosphere and active magmatism. The highly rising mantle under the Baiyun sag should be an important mechanism responsible for the ductile deformation, which caused partial melting of the upper mantle. Upwelling to the upper crust and the sedimentary layers, the partial melting materials accommodated extensional strain and caused non.faulted vertical subsidence. Magma was collected under the transfer zone after the first stage of rifting, and transferred laterally in a direction perpendicular to the extension to the ENE and WSW parts of the sag and upwelled along the NW-trending basal faults, where WNW-trending shear faults developed in swarms. The faulting activity and sedimentation history of the Baiyun sag may have been affected by the ocean ridge jump around 24 Ma and the cessation of sea floor spreading around 16 Ma.

  18. South China Flooded


    Vehicles traverse a flooded street in Liuzhou, guangxi zhuang Autonomous Region, on May 19.heavy rainstorms repeatedly struck China this month, triggering floods, mudflows and landslides. hunan, guangdong and Jiangxi provinces and Chongqing Municipality were the worst hit.

  19. Petroleum in the South China Sea : a Chinese national interest


    The thesis analyses the relationship between China's petroleum policies and China's involvement in the South China Sea conflict. The aim of the thesis is to determine what China's national interest are in the South China Sea, and to detect who forms, and how, China's South China Sea policy. The thesis discusses whether China's assumed interest in the South China Sea of exploiting the petroleum reserves of the territorially disputed areas of the South China Sea is a short-term national interes...

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

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


    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

  1. Ordovician Cephalopod Biofacies of South China and Its Provincialization

    Xiao Chuantao; Chen Zhiyong; Liu Li; He Youbin


    The research on biofacies and its provincialization is of important significance not only for the increasing of precision of stratigraphic subdivision and correlation in South China, the reconstruction of ancient environment and paleogeography and even the guiding of oil and gas exploration, but also for the study of paleobiogeogrphy and sea level changes of southern China in Ordovician. On the basis of the studies of the ecological characteristics of Ordovician cephalopods from South China, eighteen cephalopod biofacies are recognized and described:(1)Open platform Proterocameroceras biofacies;(2) Restricted platform Pseudoectenolites-Xiadongoceras biofacies;(3)Open platform Retroclitend oceras Pararetroclitendoceras biofacies;(4) Open platform Pronajaceras-Mamagouceras biofacies; (5) Shelf slope-basin Cyclostomiceras biofacies; (6) Open platform Cameroceras-Cyrtovaginoceras biofacies;(7) Open platform Coreanoceras-Manchuroceras biofacies; (8) Shelf slope-basin KaipingocerasKyminoceras biofacies; (9) Inner shelf Bathmoceras-Protocycloceras biofacies; (10) Middle shelf Dideroceras-Ancistroceras biofacies; ( 11 ) Deep-water shelf Lituites-Cyclolituites biofacies; (12) Stagnant basin Lituites-Trilacinoceras biofacies; (13) Deep-water basin Paraendoceras-Sactorthoceras biofacies; (14) Deep-water shelf Sinoceras-Michelinoceras-Disoceras biofacies; (15) Deep-water shelf Beloitoceras-Jiangshanoceras biofacies; (16) Deep-water shelf-basin Eurasiaticoceras biofacies; (17)Shelf-slope Jiangxiceras-Yushanoceras biofacies; (18) Deep-water basin Michelinoceras biofacies. The cephalopods of these biofacies, their ecological characteristics, and living conditions are elucidated in this article. The association law of cephalopod biofacies in time and space shows that there were three cephalopod biofacies provinces in South China during the Ordovician, I.e. , Yangtze biofacies province, East Guizhou (贵州)-West Hunan (湖南) biofacies province (mixed-type biofacies province

  2. South China Sea: Controversies And Solutions


    Disputes have recently broken out between China and some Southeast Asian countries and the United States in the South China Sea. The Beijing-based Economic Information Daily spoke to Liu Nanlai, a research fellow at the Institute of International Law under the Chinese Academy of Social Sciences, on the origin of the South China Sea issue and China’s position on it. Excerpts follow:

  3. China's Qaidam Basin Sensitive to Global Warming


    @@ Chinese meteorologists recently pointed out that the temperatures in northwest China's resource-rich Qaidam Basin are rising faster than the rest of the country as a result of climate change.The rapid rise in temperatures is likely to increase the long-term frequency of droughts and farming pests in the basin to the northeast of the Qinghai-Tibet Plateau.Qaidam Basin covers 250,000 km2 in Qinghai Province and is known as resource-rich with salt lakes,petroleum,natural gas and other abundant mineral resources.

  4. Petroleum prospects of marine sequences in South China

    Liqiao MA; Yong DONG; Xiaolong TU; Fengxia SUN; Jiufeng XIA; Lanying YANG


    The comprehensive study of the tectonicssequence stratigraphic-petroleum system shows that five sets of major regional and some local source rocks were developed in the tectonic evolution of South China,including the Lower Cambrian and Lower Silurian in the Caledonian cycle,the Middle Permian and Upper Permian in the Hercynian cycle,and the Lower Triassic in the Indo-Sinian cycle.Due to the inhomogeneous maturity of source rocks in this area,gas exploration would mainly be carried out in the Lower Paleozoic areas,while oil and gas exploration would be in the Upper Paleozoic ones.The reformation from the Indo-Sinian cycle to the Himalayan cycle exerted decisive influence on the hydrocarbon accumulation in the MesozoicCenozoic basin and marine sequences in southern China.The petroleum systems formed in the medium-late period of the superimposed basins are of the greatest potential.The distribution of primary and secondary oil-gas pools was mainly affected by favorable sedimentary facies,ancient uplift and slope.The comprehensive evaluation concluded that the focuses for petroleum exploration in the marine sequences of southern China will be in the superimposed basins along the margin of Yangtze landmass,the Subei-southern South Yellow Sea basin and the marine sequences preserved under the over-thrust nappe along the northern margin of the Jiangnan uplift.

  5. Palinspastic reconstruction and geological evolution of Permian residual marine basins bordering China and Mongolia

    Gen-Yao Wu


    One main feature of the tectono-paleogeographic evolution of the southern branch of the Paleo-Asian Ocean was that there developed residual marine basins in former backarc/forearc regions after the disappearance of oceanic crust. The paper illustrates the viewpoint taking the evolution of Dalandzadgad and Solonker oceanic basins as examples. The Dalandzadgad ocean subducted southwards during the Silurian-Devonian, created an intra-oceanic arc and a backarc basin in southern Mongolia. In addition, a continent marginal arc formed along the national boundary between China and Mongolia, the south of which was a backarc basin. The oceanic basin closed and arc-arc (continent) collision occurred dur-ing the early Early Permian, followed by two residual marine basins developing in the former backarc regions, named the South Gobi Basin in southern Mongolia and the Guaizihu Basin in western Inner Mongolia. The Solonker ocean subducted southwards and ifnally disappeared during the early Middle Permian. Afterwards, two residual marine basins occurred in northern China, the Zhesi Basin being situated in the former backarc region and the Wujiatun Basin in the former forearc region. The late Middle Permian was the most optimum period for the de-veloping residual marine basins, when they covered a vast area. The basin evolution differenti-ated during the early Late Permian, with a general trend of uplift in the east and of subsidence in the west. The Upper Permian in the South Gobi Basin was characterized by coal-bearing strata hosting economically valuable coal ifelds. A transgression invaded westwards and the Chandmani-Bayanleg Basin was created in southwest Mongolia during the middle-late stage of the Late Permian. Correspondingly, the coal formation entered a lfourishing time, with thick coal beds and sedimentary interbeds. All of these basins, namely, both the marine and non-marine residual basins, reversed and closed by the end of Permian.

  6. Palinspastic reconstruction and geological evolution of Permian residual marine basins bordering China and Mongolia

    Gen-Yao; Wu


    One main feature of the tectono-paleogeographic evolution of the southern branch of the Paleo-Asian Ocean was that there developed residual marine basins in former backarc/forearc regions after the disappearance of oceanic crust.The paper illustrates the viewpoint taking the evolution of Dalandzadgad and Solonker oceanic basins as examples.The Dalandzadgad ocean subducted southwards during the Silurian-Devonian,created an intra-oceanic arc and a backarc basin in southern Mongolia.In addition,a continent marginal arc formed along the national boundary between China and Mongolia,the south of which was a backarc basin.The oceanic basin closed and arc-arc(continent) collision occurred during the early Early Permian,followed by two residual marine basins developing in the former backarc regions,named the South Gobi Basin in southern Mongolia and the Guaizihu Basin in western Inner Mongolia.The Solonker ocean subducted southwards and finally disappeared during the early Middle Permian.Afterwards,two residual marine basins occurred in northern China,the Zhesi Basin being situated in the former backarc region and the Wujiatun Basin in the former forearc region.The late Middle Permian was the most optimum period for the developing residual marine basins,when they covered a vast area.The basin evolution differentiated during the early Late Permian,with a general trend of uplift in the east and of subsidence in the west.The Upper Permian in the South Gobi Basin was characterized by coal-bearing strata hosting economically valuable coal fields.A transgression invaded westwards and the Chandmani-Bayanleg Basin was created in southwest Mongolia during the middle-late stage of the Late Permian.Correspondingly,the coal formation entered a flourishing time,with thick coal beds and sedimentary interbeds.All of these basins,namely,both the marine and nonmarine residual basins,reversed and closed by the end of Permian.

  7. South China Sea: Disputes and Great Powers

    Li Jinming


    In the South China Sea disputes, China has ample proof to claim sovereignty over the Xisha Islands (the Paracel Islands) and Nansha Islands (the Spratly Islands) while the claims of certain southeast Asian countries do not hold any water. The South China Sea disputes have their origins in the San Francisco Peace Treaty signed in 1951, the result of intervention by the United States and Great Britain in regional affairs. Even today, the United States has not discarded its Cold War mentality and continues to intervene in the South China Sea disputes. The only change in the United States' attitude is that it has changed its pretext for intervention from "containing Communist expansion" in the past to "preserving freedom of navigation in the South China Sea" in the present.

  8. Distribution of major hydrocarbon source rocks in the major oil-gas-bearing basins in China

    LIU Luofu; ZHAO Suping; CHEN Lixin; HUO Hong


    The distribution characteristics of major hydrocarbon source rocks in the major oil-gas-bearing basins in China were discussed in this paper, and differences between the East and the West basins in tectonic setting, age, lithology, sedimentary environment, and hydrocarbon generation feature and potential were also studied. Considering the Lüliang Mountains-Dalou Mountains as the boundary, source rocks in the East basins are distributed mainly in three NNE-trend subsiding belts, and those in the West basins are distributed in the north and south of the Tianshan Mountains and Qilian Mountains. They are mainly NWW trending and can be divided into four basin groups.

  9. Sustainable Energy in South China



    Eyeing on China's recent developments in its energy sector which result in increasing market opportunities, the Netherlands is willing to further strengthen bilateral cooperation in particular in the field of sustainable energy supply, not only on conventional energy but also new energy and renewable energy. This led to the signing of a MoU on energy cooperation between Minister Zhang Guo bao and his Dutch counterpart Minister Maria van der Hoeven on 9 September 2009, aiming at further deepening all-sided cooperation in energy-related areas. Not only the Dutch government, but also academic and research institutes, universities, branch organizations and companies in the Netherlands are aware of this potential market. Some of them are already active in China's domestic market with successful projects and impressive track records. In order to reinforce the competitiveness of Dutch companies and stimulate cooperation, the Consulate General of the Netherlands in Guangzhou is carrying out an investigation on sustainable energy in its resort, covering Guangdong, Guangxi, Fujian and Hainan Province. By investigating local market needs, the Consulate General has realized a number of interesting areas which the Dutch sector can offer its expertise and share experiences, such as energy comprehensive planning and management, eco-city projects, operation and maintenance of offshore wind power farms, deep-water engineering technologies and so on. The Consulate General is eager to pinpoint potential opportunities for the Dutch supply chain and promote Dutch expertise in South China. It is anticipated that the findings mentioned in this report can facilitate Dutch companies with market recognition, orientation and entry.

  10. Preferential mantle lithospheric extension under the South China margin

    Continental rifting in the South China Sea culminated in seafloor spreading at ∼ 30Ma (Late Oligocene). The basin and associated margins form a classic example of break-up in a relatively juvenile arc crust environment. In this study, we documented the timing, distribution and amount of extension in the crust and mantle lithosphere on the South China Margin during this process. Applying a one-dimensional backstripping modeling technique to drilling data from the Pearl River Mouth Basin (PRMB) and Beibu Gulf Basin, we calculated subsidence rates of the wells and examined the timing and amount of extension. Our results show that extension of the crust exceeded that in the mantle lithosphere under the South China Shelf, but that the two varied in phase, suggesting depth-dependent extension rather than a lithospheric-scale detachment. Estimates of total crustal extension derived in this way are similar to those measured by seismic refraction, indicating that isostatic compensation is close to being local. Extension in the Beibu Gulf appears to be more uniform with depth, a difference that we attribute to the different style of strain accommodation during continental break-up compared to intra-continental rifting. Extension in PRMB and South China slope continues for ∼ 5m.y. after the onset of seafloor spreading due to the weakness of the continental lithosphere. The timing of major extension is broadly mid-late Eocene to late Oligocene (∼ 45-25Ma), but is impossible to correlate in detail with poorly dated strike-slip deformation in the Red River Fault Zone. (author)

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

    Qingqing eXu


    Full Text Available 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 growing 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.

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

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


    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

  13. The complexity of South China Sea kinematics

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


    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

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

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


    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 (South China.

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

    Xie, Xiangyang


    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. Petroleum Exploration of Craton Basins in China


    Craton basins are a significant petroliferous provenance. Having undergone multiple openclose tectonic cycles and strong reworking of the late Cenozoic tectonic movement, the craton basins in China are highly broken. This has resulted in multi-source and multiphase hydrocarbon generation and later hydrocarbon accumulation so that a complicated spatial assemblage of primary, paraprimary and secondary oil-gas pools has been formed. The primary factors controlling hydrocarbon accumulation include hydrocarbon-generating depressions, paleouplifts, paleoslopes, unconformity surfaces, paleo-karst, faults and fissure systems as well as the later conservation conditions. In consequence, the strategy of exploration for China's craton basins is to identify the effective source rocks, pay attention to the different effects of paleohighs and late reworking, enhance studies of the secondary storage space, attach importance to the exploration of lithologic oil-gas reservoirs and natural gas pools, and approach consciously from the secondary oil pools to the targets near the source rocks. At the same time, a complete system of technologies and techniques must be built up.

  17. A Survey of Coral Reefs in South China Sea Completed


    @@ An investigation of coral reefs in South China Sea has recently completed by CAS scientists at South China Sea Institute of Oceanography (SCSIO) in Guangzhou. The compilation and analysis of the obtained data is now under way.

  18. Research on the dynamics of the South China Sea opening: Evidence from analogue modeling

    SUN; Zhen; ZHOU; Di; ZHONG; Zhihong; XIA; Bin; QIU; Xuelin; ZENG; Zuoxun


    Independent of Indochina extrusion, the South China Sea experienced a process from passive continental rifting to marginal sea drifting. According to the fault patterns in the Beibu Gulf basin and the Pearl River Mouth basin, the continental rifting and early spreading stage from 32 to 26 Ma were controlled by extensional stress field, which shifted clockwise from southeastward to south southeastward. From 24 Ma on, the sea spread in NW-SE direction and ceased spreading at around 15.5 Ma. Integrated geological information with the assumption that the South China Sea developed along a pre-Cenozoic weakness zone, we did analogue experiments on the South China Sea evolution. Experiments revealed that the pre-existing weakness zone goes roughly along the uplift zone between the present Zhu-1 and Zhu-2 depression. The pre-existing weakness zone is composed of three segments trending NNE, roughly EW and NEE, respectively. The early opening of the South China Sea is accompanied with roughly 15° clockwise rotation, while the SE sub-sea basin opened with SE extension. Tinjar fault was the western boundary of the Nansha block (Dangerous Ground),while Lupar fault was the eastern boundary of the Indochina, NW-trending rift belt known as Zengmu basin developed between above two faults due to block divergent of Indochina from Nansha. In the experiment, transtensional flower structures along NW-trending faults are seen, and slight inversion occurs along some NE-dipping faults. The existence of rigid massifs changed the orientations of some faults and rift belt, and also led to deformation concentrate around the massifs. The rifting and drifting of the South China Sea might be caused by slab pull from the proto South China Sea subducting toward Borneo and/or mantle flow caused by India-Asia collision.

  19. Syn-Rift Subsidence Deficit of the Qiongdongnan Basin and the Synchronous Rapid Uplift of South Hainan Island: Some Clues on Surface Response to the Hainan Plume, NW South China Sea

    Shi, X.


    Based on tomography, geochemical and petrological evidences, a mantle plume called Hainan Plume has been suggested lying under Hainan Island. Our recent studies on basin subsidence and surface topography indicated that there existed surface vertical motion response to the suggested mantle plume. Post-rift rapid subsidence in the Qiongdongnan basin, which lies south of Hainan Island, is well known and accepted phenomenon. A particular feature is that the rapid subsidence did not just follow the end of syn-rift phase at ~ 21 Ma, but began after a ~10 my relatively tectonic quiescence. Different tectonic processes have been proposed to account for this rapid subsidence event. However, all these proposed mechanisms just focus on the rapid subsidence episode since Late Miocene. Our details subsidence analyses show that its tectonic subsidence is of a two-stage anomalous character: the deficit subsidence at the end of the syn-rift phase and the well known post-rift rapid subsidence after 10.5 Ma. Numerical analyses show that the stretching factor βs based on syn-rift sequences is much less than the observed crustal stretching factor βc, and the present basement depth can be almost predictable if assuming that the lithosphere was thinned with stretching factor βc; The crustal thinning happened during the syn-rift phase (before 21 Ma), and a new rifting and lower crustal flow after 21 Ma were not supported, proposing further that the syn-rift subsidence is deficit. Our further analyses proposed that the syn-rift subsidence deficit might be caused by the dynamic support of the secondary plume, and the post-rift rapid subsidence might result from the losing support of the thermal source decaying, therefore occurred to compensate the subsidence deficit of the syn-rift phase. The cooling history of the southern Hainan deduced by low temperature chronometry data, also indicated there exist an uplift event in the Late Oligocene (Shi et al., 2011). All the samples show that

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

    XU Sihuang; W.Lynn Watney


    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.

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

    Xu, S.; Watney, W.L.


    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.

  2. Petroleum exploration potential in abyssal zone of Qiongdongnan Basin, South China Sea%南海琼东南盆地深水区油气勘探潜力

    朱廷祥; 段铁军


    南海琼东南盆地经历了始新世的陆内断陷、渐新世的裂谷和中新世以来的被动陆缘坳陷等3个演化阶段,特别是在深水区形成了断陷期湖相、裂谷期海陆过渡相到海相及被动陆缘坳陷期海相等多套生烃物质;3期构造沉降作用伴随了3次高热流事件,利于烃源岩的成熟;多储集体类型、多套储盖组合,为油气富集提供了广阔的空间;多期构造运动,形成多种圈闭类型,利于油气聚集成藏.%The evolution of the Qiongdongnan Basin in the South China Sea can be divided into three stages including intracontinental rift during Eocene, rift during Oligocene, and passive continental margin depression ever since Miocene. Multiple sets of petroleum generating materials of different facies were deposited in abyssal zone. For example, lacustrine facies in the first stage, marine-continental and continental facies in the second stage, and marine facies in the third stage. Three high thermal fluid events took place during the three evolution stages, contributing to the maturation of source rocks. Multiple types of reservoir and multiple sets of reservoir - cap assemblage provided abundant room for the enrichment of petroleum. Various types of trap formed during stages of tectonic movements were favorable for accumulation.

  3. From Basin Black Shales to Platform Carbonate Rocks: A Study on Sequence Stratigraphy for the Lower Cambrian of the Upper-Yangtze Region in South China


    In the Upper-Yangtze region, especially in Guizhou Province and its adjacent areas, the Lower Cambrian is well developed and is marked by a succession from black shales of the basin facies to carbonate rocks of the platform facies. The drowning event of the platform occurring at the turn from Sinian to Cambrian resulted in a set of black shales, i.e. the Niutitang Formation, which makes up the bottom part of the Lower Cambrian. With the shoaling of the sedimentary environment, a set of carbonate rocks, i.e. the Qingxudong Formation, was formed in the top part of the Lower Cambrian. Thus, the Lower Cambrian in the study area makes up one second-order sequence that can be further subdivided into five third-order sequences, and forms a regularly cyclic succession of transgression-regression. There is a regularly vertical stacking pattern for the third-order sequences in the second-order sequence. From bottom to top, the succession of the "CS (condensed section)+HST (high-stand system tract)" of the third-order sequences is changed into the succession of the "TST (transgressive system tract)+CS+HST". Correspondingly, the drowning-type sequence boundary is changed into the exposure-type one. Therefore, both the second-order and the third-order sequences have similar sedimentary-facies architectures. A concomitant with these temporal changes,the Lower Cambrian with a thickness of 1000 m that contains five third-order sequences is changed into a condensed succession that cannot identify third-order sequences toward the southeast with the deepening of the sedimentary environment. According to the elementary features of the third-order sequences, i.e. the regularity o sedimentary-facies successions in space and the synchronism of sedimentary-environment changes in time, the detailed division of the third-order sequences at main logged sections in different paleogeographical background becomes the basis to establish the sequence-stratigraphic framework that can demonstrate

  4. Estimation of potential distribution of gas hydrate in the northern South China Sea

    Wang, Chunjuan; Du, Dewen; Zhu, Zhiwei; Liu, Yonggang; Yan, Shijuan; Yang, Gang


    Gas hydrate research has significant importance for securing world energy resources, and has the potential to produce considerable economic benefits. Previous studies have shown that the South China Sea is an area that harbors gas hydrates. However, there is a lack of systematic investigations and understanding on the distribution of gas hydrate throughout the region. In this paper, we applied mineral resource quantitative assessment techniques to forecast and estimate the potential distribution of gas hydrate resources in the northern South China Sea. However, current hydrate samples from the South China Sea are too few to produce models of occurrences. Thus, according to similarity and contrast principles of mineral outputs, we can use a similar hydrate-mining environment with sufficient gas hydrate data as a testing ground for modeling northern South China Sea gas hydrate conditions. We selected the Gulf of Mexico, which has extensively studied gas hydrates, to develop predictive models of gas hydrate distributions, and to test errors in the model. Then, we compared the existing northern South China Sea hydrate-mining data with the Gulf of Mexico characteristics, and collated the relevant data into the model. Subsequently, we applied the model to the northern South China Sea to obtain the potential gas hydrate distribution of the area, and to identify significant exploration targets. Finally, we evaluated the reliability of the predicted results. The south seabed area of Taiwan Bank is recommended as a priority exploration target. The Zhujiang Mouth, Southeast Hainan, and Southwest Taiwan Basins, including the South Bijia Basin, also are recommended as exploration target areas. In addition, the method in this paper can provide a useful predictive approach for gas hydrate resource assessment, which gives a scientific basis for construction and implementation of long-term planning for gas hydrate exploration and general exploitation of the seabed of China.

  5. 沙海槽前陆盆地热流变结构%Lithospheric Thermal-Rheological Structure of Nansha Trough Foreland Basin in South China Sea

    马辉; 许鹤华; 施小斌; 陈爱华; 刘唐伟


    为了研究南沙海槽前陆盆地深部岩石圈的热力学性质,在前人所做的地质与地球物理研究工作的基础上,结合各种岩石热力学流变参数,采用有限元分析方法,计算了现今构造逆冲之后和中中新世一全新世逆冲过程活跃时两种状态下的深部岩石圈二维温度场和流变结构.模拟计算表明,南沙海槽前陆盆地地幔热流贡献达60%~70%,大地热流受深部地幔控制.逆冲推覆构造作用使盆地逆冲推覆带地表热流显著升高了 15%~25%,达到70~75 mW/m2.盆地沉积层温度在200℃以内,莫霍面温度420~500℃,地壳地温梯度25~30℃/km.盆地热岩石圈厚度为80 km左右,横向上变化幅度不大.南沙海槽前陆盆地深部岩石圈流变性质具有明显的分层特性,为典型的“三明治”结构.盆地岩石圈综合强度南南沙海槽向逆冲推覆带方向呈下降趋势,盆地力学岩石圈厚度50 km左右,有效弹性厚度为30~32 kn.通过模拟盆地深部岩石圈热流变结构,揭示了盆地深部岩石圈具有强地幔、弱地壳的流变学特征,表现为高强度块体.同时南沙海域地震活动与深部岩石圈热结构、热活动和岩石圈综合强度密切相关.地壳内热构造活动弱、岩石圈强度大可能是区域地震很少发生的重要原因.%In order to study the lithospheric thermodynamic properties of Nansha trough foreland basin, we simulate the deep lithosphere temperature field and rheological structure during the thrust faults tectonic activities from Middle Miocene to Hol-ocene and after thrusting (static) in the basin using the finite element method, based on previous studies of geological and geophysical data together with a variety of rock thermodynamic parameters. Simulation results indicate that heat flow contribution from mantle reaches 60% - 70% of surface heat flow which is controlled by deep mantle in Nansha trough foreland basin. Thrusting movements increase

  6. 14C as a tool for evaluating riverine POC sources and erosion of the Zhujiang (Pearl River) drainage basin, South China

    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 Δ14C values of -425 per mille to -65 per mille 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.

  7. On the Origin of One Basin-Multiple Mountain Couplings in the Mesozoic-Cenozoic Basin-Range Area in Eastern North China

    NIU Shuyin; SHAO Ji'an; HOU Quanlin; WANG Baode; XU Chuanshi


    The basin-range coupling relation is a leading subject of the modern geology. In geometry, relations of this type include couplings between stretched orogenic belt and down-faulted basin, compressional orogenic belt and foreland basin, strike-slip orogenic belt and strike-slip basin and so on. Fault chains are the key for these couplings and there are typical examples for all these cases. The North China down-faulted basin is coupled west with the Tathang uplift, east with the Jiao-Liao Mountains, north with the Yanshan orogenic belt and south with the Dabie orogenic belt,that is to say, the central down-faulted basin and the surrounding orogenic belts bear a coupling relation within a uniform dynamistic system. Study shows that the central down-faulted basin and the North China mantle sub-plume structure have a close relation during their formation. Owing to intensive mantle sub-plume uplifting, the bottom of the lithosphere suffered from resistance, which caused the lithosphere of the eastern North China to be heated, thinned and fault-depressed. Meanwhile, mantle rocks that were detached outwards in the shape of mushroom was dissected by surrounding ductile shearing zones, which lead to decompression and unloading to generate hypomagmas, and a series of mantle-branch structures were formed around the down-faulted basin. There is an obvious comparability among these mantle branch structures (orogenic belts), and they have basin-range coupling relations with the central down-faulted basins.

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

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


    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

  9. Organic geochemistry and coal petrology of Tertiary brown coal in the Zhoujing mine, Baise Basin, South China -4. Biomarker sources inferred from stable isotope compositions of individual compounds

    Schoell, M.; Simoneit, B.R.T.; Wang, T.-G. (Chevron Petroleum Technology Co., La Habra, CA (United States))

    Carbon isotopic compositions of extractable compounds derived from higher land plants are with [+-]2[per thousand] of the bulk coal ([delta][sup 13]C -27.0[per thousand]) from Baise Basin. This data suggests that either similar species contributed these compounds or that the plants from which this coal was formed imposed similar biosynthetic fractionations. The terpenoid hydrocarbons form two isotopically distinct groups: the diterpenoids ([delta][sup 13]C 2.50 [+-] 1.4[per thousand]) and the sesquiterpenoids ([delta][sup 13]C 25.9 [+-] 1.5[per thousand]) are on average 1-2[per thousand] enriched in [sup 13]C compared to the bulk coal, whereas the oleanane-ursane-lupane derivatives ([delta][sup 13]C 29.0 [+-] 0.8[per thousand]) are on average 1-2[per thousand] depleted in [sup 13]C compared to the bulk coal. The n-alkanes, ranging from C[sub 15] to C[sub 35], have a mean [delta][sup 13]C value of -32.4 [+-] 0.6[per thousand], whereby averages for the C[sub 17]-C[sub 22] and C[sub 23]-C[sub 33] n-alkanes do not significantly differ from the overall average. Hopane derivatives in this coal extract are depleted in [sup 13]C compared to the bulk coal by 8-34[per thousand] suggesting that bacterial cycling of methane played a role during formation of this coal. 19 refs., 4 figs., 1 tab.

  10. North-south Differentiation of the Hydrocarbon Accumulation Pattern of Carbonate Reservoirs in the Yingmaili Low Uplift, Tarim Basin,Northwest China

    L(U) Xiuxiang; LI Jianjiao; ZHAO Fengyun; YANG Ning; ZHANG Qiucha


    By analyzing the characteristics of development, structural evolution and reservoir beds of the residual carbonate strata, this study shows that the residual carbonate strata in the Yingmaili low uplift are favorable oil and gas accumulation series in the Tabei (northern Tarim uplift) uplift. There are different patterns of hydrocarbon accumulation on the northern and southern slopes of the Yingmaili low uplift. The north-south differentiation of oil reservoirs were caused by different lithologies of the residual carbonate strata and the key constraints on the development of the reservoir beds. The Mesozoic terrestrial organic matter in the Kuqa depression and the Palaeozoic marine organic matter in the Manjiaer sag of the Northern depression are the major hydrocarbon source rocks for the northern slope and southern slope respectively. The hydrocarbon accumulation on the northern and southern slopes is controlled by differences in maturity and thermal evolution history of these two kinds of organic matter. On the southern slope, the oil accumulation formed in the early stage was destroyed completely, and the period from the late Hercynian to the Himalayian is the most important time for hydrocarbon accumulation. However, the time of hydrocarbon accumulation on the northern slope began 5 Ma B.P. Carbonate inner buried anticlines reservoirs are present on the southern slope, while weathered crust and paleo-buried hill karst carbonate reservoirs are present on the northern slope. The northern and southern slopes had different controlling factors of hydrocarbon accumulation respectively. Fracture growth in the reservoir beds is the most important controlling factor on the southern slope; while hydrocarbon accumulation on the northern slope is controlled by weathered crust and cap rock.

  11. China, South Africa and the Lewis Model

    John B. Knight


    The paper uses the Lewis model as a framework for examining the labour market progress of two labour-abundant countries, China and South Africa, towards labour shortage and generally rising labour real incomes. In the acuteness of their rural-urban divides, forms of migrant labour, rapid rural-urban migration, and high and rising real wages in the formal sector, the two economies are surprisingly similar. They differ, however, in the dynamism of their formal sector growth of output and employ...

  12. The Gramscatho Basin, south Cornwall, UK : Devonian active margin successions

    Leveridge, B.E.; Shail, R.K.


    Deep marine deposits of the Gramscatho Basin of south Cornwall reflect two tectonic regimes; Early to Middle Devonian rifting of continental lithosphere with formation of oceanic lithosphere to the south, and Middle Devonian to earliest Carboniferous convergence along its southern margin. Sediments on thinned continental crust to the north and oceanic lithosphere to the south were juxtaposed in the Late Devonian when nappes of deep water flysch and olistostrome were thrust up on to the northe...

  13. Mesozoic basins and associated palaeogeographic evolution in North China

    Yong-Qing Liu; Hong-Wei Kuang; Nan Peng; Huan Xu; Peng Zhang; Neng-Sheng Wang; Wei An


    In North China, the Mesozoic terrestrial basins, sedimentary palaeogeography and tectonic settings involved ifve evolutionary stages:(1) the Early-Middle Triassic, (2) the Late Triassic to Early-Middle Jurassic, (3) the Late Jurassic to early Early Cretaceous, (4) the middle-late Early Cretaceous and (5) the Late Cretaceous. The regional punctuated tectonic events occurred during these evolutionary stages. During the Early-Middle Triassic (stage 1), the Xingmeng Orogenic Belt (XMOB, i.e., east-ern part of Central Asia Orogenic Belt, CAOB) of the northern North China was settled in the transition of tectonic environment from syn-orogenic compression to post-orogenic extension with intensive uplifting. It is a main provenance in the uniifed Ordos-North China Basin.The united continental plate of China and the Qinling-Dabie-Sulu Orogenic Belt formed due to convergence and collision between the North China Plate and the Yangtze Plate along two suture zones of the Mianlue and the Shangdan in the terminal Middle Triassic. During the Late Triassic to the Early-Middle Jurassic (stage 2), the Late Triassic maifc or alkaline rocks and intrusions occurred on the northern and southern margins of North China Craton (NCC) and XMOB, implying that intensiifed extension happened all over the North China (early phase of stage 2). Additionally, in the late phase of stage 2, the basic volcanic-iflling faulted basins were widely distributed in the northeastern North China during the Early-Middle Jurassic, including a series of small-to medium-sized basins with coal-bearing strata and some volcanic rocks in other areas of North China, which was the result of subduction of the Palaeo-Paciifc Plate during the Early-Middle Jurassic. An active continental margin with accretionary complex developed in the eastern Heilongjiang of China, Japan and the Far East of Russia at that time. However, in the end of the Early-Middle Jurassic, because of the Yan-shanian orogeny characterized by

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

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


    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

  15. Quantitative Modelling of Multiphase Lithospheric Stretching and Deep Thermal History of Some Tertiary Rift Basins in Eastern China

    林畅松; 张燕梅; 李思田; 刘景彦; 仝志刚; 丁孝忠; 李喜臣


    The stretching process of some Tertiary rift basins in eastern China is characterized by multiphase rifting. A multiple instantaneous uniform stretching model is proposed in this paper to simulate the formation of the basins as the rifting process cannot be accurately described by a simple (one episode) stretching model. The study shows that the multiphase stretching model, combined with the back-stripping technique, can be used to reconstruct the subsidence history and the stretching process of the lithosphere, and to evaluate the depth to the top of the asthenosphere and the deep thermal evolution of the basins. The calculated results obtained by applying the quantitative model to the episodic rifting process of the Tertiary Qiongdongnan and Yinggehai basins in the South China Sea are in agreement with geophysical data and geological observations. This provides a new method for quantitative evaluation of the geodynamic process of multiphase rifting occurring during the Tertiary in eastern China.

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

    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


    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

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

    Chen, Yu-Huang; Su, Chih-Chieh


    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.

  18. Silurian to Devonian foreland basin in the south edge of Tarim Basin


    Based on the theory of plate tectonics, combining with the isotopic dating of ophiolite, igneous and volcanics, geochemical test, rare earth element analyze and seismic interpretation, this paper studies the pre-Carboniferous tectonics and sedimentary formation of the south edge of the Tarim Basin and proves that there exists the Kunlun Ocean under tensional tectonics during the Sinian and Cambrian in the south edge of the Tarim Plate. After that, due to the collision orogenesis, there formed the peripheral foreland basin in the south edge of Tarim. The Upper Silurian and Devonian molasses sedimentary system superposed on the Sinian and Middle Silurian passive margin flysch sedimentary system and formed the bivariate structure of the foreland basin. And at the same time, based on the field geology and seismic interpretation, we have identified that the formation of the Silurian and Devonian have the character of half deposit which shows thick in the south area and thin in the north, and the pre-Carboniferous thrust compression tectonics remained in the foreland thrust belt, which further demonstrates that there existed the Silurian and Devonian peripheral foreland basin on the south edge of the Tarim Basin.

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

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


    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. Drought analysis using multi-scale standardized precipitation index in the Han River Basin, China

    Yue-ping XU; Sheng-ji LIN; Yan HUANG; Qin-qing ZHANG; Qi-hua RAN


    Regional drought analysis provides useful information for sustainable water resources management. In this paper, a standardized precipitation index (SPI) at multiple time scales was used to investigate the spatial patterns and trends of drought in the Han River Basin, one of the largest tributaries of Yangtze River, China. It was found that, in terms of drought severity, the upper basin of the Hart River is the least, while the growing trend is the most conspicuous; a less conspicuous growing trend can be observed in the middle basin; and there is an insignificant decreasing trend in the lower basin. Meanwhile, the impact of drought on the Middle Route of the South-to-North Water Transfer Project was investigated, and it is suggested that water intake must be reduced in times of drought, particularly when successive or simultaneous droughts in the upper and middle basins of the Han River Basin occur. The results can provide substantial information for future water allocation schemes of the South-to-North Water Transfer Project.

  1. Classification of Complex Reservoirs in Superimposed Basins of Western China

    PANG Xiongqi; ZHOU Xinyuan; LIN Changsong; HUO Zhipeng; LUO Xiaorong; PANG Hong


    Many of the sedimentary basins in western China were formed through the superposition and compounding of at least two previously developed sedimentary basins and in general they can be termed as complex superimposed basins.The distinct differences between these basins and monotype basins are their discontinuous stratigraphic sedimentation,stratigraphic structure and stratigraphic stress-strain action over geological history.Based on the correlation of chronological age on structural sections,superimposed basins can be divided into five types in this study:(1)continuous sedimentation type superimposed basins,(2)middle and late stratigraphic superimposed basins,(3)early and late stratigraphic superimposed basins,(4)early and middle stratigraphic superimposed basins,and(5)long-term exposed superimposed basins.Multiple source-reservoir-caprock assemblages have developed in such basins.In addition,multi-stage hydrocarbon generation and expulsion,multiple sources,polycyclic hydrocarbon accumulation and multiple-type hydrocarbon reservoirs adjustment,reformation and destruction have occurred in these basins.The complex reservoirs that have been discovered widely in the superimposed basins to date have remarkably different geologic features from primary reservoirs,and the root causes of this are folding,denudation and the fracture effect caused by multiphase tectonic events in the superimposed basins as well as associated seepage,diffusion,spilling,oxidation,degradation and cracking.Based on their genesis characteristics,complex reservoirs are divided into five categories:(1)primary reservoirs,(2)trap adjustment type reservoirs,(3)component variant reservoirs,(4)phase conversion type reservoirs and(5)scale-reformed reservoirs.

  2. Modern movement and deformation in the South China Sea shown by GPS measurements and numerical simulation

    WANG Jing; LUAN Xiwu; YU Roger Z.


    To better understand the crustal deformation of the South China Sea Basin,we produce a mechanically consistent 2-dimensional model for observing regional velocity field in the South China Sea (SCS).We studied the dominating regional tectonic stress field by geodetic measurements and finite element analysis,the spatial variations of velocity field and strain field,and relative movements among different blocks,using a 2-dimensional model describing crustal deformation of the South China Sea Basin.Strain results show that the SCS is extending at present.The western part of SCS is opening gradually in NW-SE direction from its northern margin to the south,but the eastern part of SCS is opening gradually from its central part to the north and south.In addition,we analyzed the plate kinematics to the deformation of the SCS,using a two-dimensional finite element model.Our simulations results are well explained by available geodetic data.The movement of SCS is resulted from interactions among Indian Plate,Pacific Plate,Philippine Sea Plate,and Eurasian Plate.

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

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


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

    Tongtiegang ZHAO; Jianshi ZHAO; Hongchang HU; Guangheng NI


    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.

  5. Coccolithophore responses to environmental variability in the South China Sea: species composition and calcite content

    Jin, X. B.; C. L. Liu; Poulton, A. J.; M. H. Dai; X.H. Guo


    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. 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 ...

  6. Stratigraphy and Tectonics of the Sengkang Basin, South Sulawesi

    Suyono Suyono


    Full Text Available DOI: 10.17014/ijog.v5i1.89Sulawesi was formed during the Oligocene - Miocene collision between the Eurasian Plate and micro-continental fragments detached from the Indian-Australian Plate. The Sengkang Basin situated on the South Sulawesi Province, was formed by a major north northwest - south southeast trending fault system of the Walanae Fault Zone, which was followed by the formation of Late Neogene foreland basin and syn-orogenic deposition. The fault system separated the eastern and western parts of South Sulawesi and influenced the deposition during the Late Miocene to Quaternary. The lower part of the deposition unit consists of small carbonate reefs of the Tacipi Member occupying the East Sengkang Basin, where this shallow marine facies is intercalated within or overlies marine claystones representing the base of the Walanae Formation. The middle sequence is interpreted as a delta foreset consisting of the Samaoling and Beru Members. During the deposition of these two members, the northern part of the Sengkang Basin gradually changed from a tidal and deltaic to fluvial environments. Furthermore, the upper sequence of this sedimentary unit is dominated by fluvial deposits.

  7. Main Controlling Factors on Hydrocarbon Accumulation and Distribution in Marine Sedimentary Sequences in South China

    Cai Liguo; Zhou Yan; Bai Zhenrui


    Multiple source rock assemblages were deposited in the sedimentary provinces in South China in geologic history,and some of them were destructed by and some survived against multiple tectonic movements.Therefore,multiple sources,mixed sources,and uneven distribution of sources occurred in the marine sedimentary basins in South China during the late stage of hydrocarbon pooling.Epidiagenesis of the marine carbonate reservoirs and its modification to reservoir poroperm characteristics determined the formation and the scale of natural gas pools.The exploration practices show that the large to medium gas fields mainly occur in areas with high-quality reservoirs.Detailed study of the paleo-oil accumulations and typical oil and gas reservoirs reveals that the basins experienced multiphase superimposition and modification,leading to the distribution of the Paleozoic paleo-oil accumulations and bitumen in the peripheral areas.The phenomenon that oil and gas production concentrates in the Sichuan basin indicates that the overall sealing conditions of a basin determine the oil/gas potentials and the scale of oil and gas production.This is a critical factor controlling the accumulation and distribution of gas in the marine sequences in South China.The early oil and gas pools in the Yangtze platform left billions of bitumen in the peripheral areas due to the destruction of seals.Since the Himalayan,"late-generation and late-accumulation" gas pools represented by the gas pools in the Sichuan (四川) basin were formed in the marine sedimentary sequences in South China as a result of the change of the sealing conditions.Current gas discoveries appear to be "paleo-generation and paleo-accumulation" gas pools but actually are "late-generation and late-accumulation" gas pools.These patterns of hydrocarbon pooling clearly depict themselves in western Sichuan basin and Weiyuan (威远)gas field.It is revealed that the gas pools in the Sichuan basin were mainly formed as a result of

  8. Groundwater Systems and Resources in the Ordos Basin, China

    HOU Guangcai; LIANG Yongping; SU Xiaosi; ZHAO Zhenghong; TAO Zhengping; YIN Lihe; YANG Yuncheng; WANG Xiaoyong


    The Ordos Basin is.a large-scalesedimentary basin in northwestern China. The hydrostratigraphic units from bottom to top are pre-Cambrian metamorphic rocks, Lower Paleozoic carbonate rocks, Upper Paleozoic to Mesozoic clastic rocks and Cenozoic deposits. The total thickness is up to 6000 m. Three groundwater systems are present in the Ordos Basin, based on the geological settings, I.e. The karst groundwater system, the Cretaceous dastic groundwater system and the Quaternary groundwater system. This paper describes systematically the groundwater flow patterns of each system and overall assessment of groundwater resources.

  9. International business negotiation in the South and North China

    Lin, Xiaofeng; Yan, Ran; Christakopoulos, Argiris


    AbstractData: 2008 –09 – 29Level: Bachelor Thesis in Business Administration, 15 hp,Title: International business negotiation in the South and North ChinaAuthors: Xiaofeng Lin, Ran Yan, Argiris Christakopoulos,Supervisor: Leif SannerProblem: Concurred with China's economic development, the commercial activitiesamong China and different countries have become more frequent. Manyscholars have come to realize that China's different cultural background hasbeen a great extent influenced by the inte...

  10. Cenozoic Volcanism in South China Sea and Its Vicinity and South China Sea Spreading


    The rock series, rock types and Sr-Nd isotopic dating of the Cenozoic volcanic rocks in the South China Sea are similar to those in its vicinity. On the basis of the spreading age of the South China Sea, the Cenozoic volcanic rocks are divided into three stages: the pre-spreading stage, the spreading stage and the post-spreading stage. The deep process characteristics of the asthenosphere and lithosphere may be inferred from the study on primary basaltic magma. The top layers of the asthenosphere both in the spreading stage and in the pre-spreading stage are closer to the earth surface than that in the post-spreading stage. From the pre-spreading stage to the spreading stage, the top layer of the asthenosphere decreased in depth, while the amount of interstitial partial melts increased. The evolution of the primary basaltic magma shows a progressive evolution sequence of the rifting volcanism and a faster lithospheric spreading velocity. From the spreading stage to the post-spreading stage, the top layer of the asthenosphere gradually increased in depth, but the amount of interstitial partial melts decreased. The evolution of primary basaltic magma shows a retrogressive evolution sequence of the rifting volcanism and a gradual decrease in the lithospheric spreading velocity. The depth recognized by the study on the Cenozoic volcanism demonstrates the deep environment for the formation and evolution of the South China Sea.

  11. A Note on the South China Sea Shallow Interocean Circulation


    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 Luz6n 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.

  12. Mesozoic basin evolution and tectonic mechanism in Yanshan, China

    LIU; Shaofeng; LI; Zhong; ZHANG; Jinfang


    The Mesozoic basins in Yanshan, China underwent several important tectonic transformations, including changes from a pre-Late Triassic marginal cratonic basin to a Late Triassic-Late Jurassic flexural basin and then to a late Late Jurassic-Early Cretaceous rift basin. In response to two violent intraplate deformation at Late Triassic and Late Jurassic, coarse fluvial depositional systems in Xingshikou and Tuchengzi Formations were deposited in front of thrust belts. Controlled by transform and extension faulting, fan deltas and lacustrine systems were deposited in Early Cretaceous basins. The composition of clastic debris in Late Triassic and Late Jurassic flexural basins respectively represents unroofing processes from Proterozoic to Archean and from early deposited, overlying pyroclastic rocks to basement rocks in provenance areas. Restored protobasins were gradually migrated toward nearly NEE to EW-trending from Early Jurassic to early Late Jurassic. The Early Cretaceous basins with a NNE-trending crossed over early-formed basins. The Early-Late Jurassic and Early Cretaceous basins were respectively controlled by different tectonic mechanisms.

  13. Abnormal overpressure distribution and natural gas accumulation in foreland basins, Western China


    Abnormal overpressure occurs in the foreland basins of Kuqa, South Junggar and West Sichuan in China. The pressure coefficients are high. Overpressure exists in wide areas and various strata. The layers of overpressure have a very close relationship with lithology, and the area of overpressure is controlled by the piedmont depression. The mechanisms of overpressure formation in the Kuqa and South Junggar Depression include disequilibrium compaction and tectonic compression; the importance of these two factors varies in different basins and in different stages of the same basin. Different models of gas accumulation are established to explain the relationship between overpressure distribution and gas pool formation, and the influence of overpressure on the gas pools. These models include: (ⅰ) the violent tectonic movement leads to the pool formation in overpressure belt (Kela-2 gas field in Kuqa); (ⅱ) the pressure releases at shallow part and the gas pool forms in late time (Hutubi gas field in southern Junggar Basin); (ⅲ) through the pressure transfer the gas migrates and accumulates (Xinchang gas field in Western Sichuan Basin).

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

    Wu, Xiaozhi; He, Dengfa; Qi, Xuefeng


    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

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

    Amrakhov, Rashad; Shiraliyeva, Sevinj; Kerimova, Nailya


    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

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

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


    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

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

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


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

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


    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

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

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


    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

  20. Central Coast Region South District Basin Planning & Habitat Mapping Project

    Watson, Jessica; Casagrande, Julie; Watson, Fred


    This is a report to the California Department of Fish and Game. Between 2003 and 2008, the Foundation of CSUMB produced fish habitat maps and GIS layers for CDFG based on CDFG field data. This report describes the data entry, mapping, and website construction procedures associated with the project. Included are the maps that have been constructed. This report marks the completion of the Central Coast region South District Basin Planning and Habitat Mapping Project. (Document contains 40 pages)

  1. Cenozoic bottom current sedimentation in the Cape Basin, South Atlantic

    Wildeboer Schut, E.; Uenzelmann-Neben, Gabriele


    The Cape Basin is located at a central location with respect to variouswater masses. The coldest and densest of these water masses is theLower Circumpolar Deep Water.The location and topography of the Agulhas Ridge effectively blocks itsnorthward flowing branches and deflects them into a south-westerndirection to follow the bathymetric contours of the Agulhas Ridge wheresuspended sediments accumulate in contourite drifts.Several hundred metres of sediments have accumulated since the onsetof A...

  2. Winter Cold tongue in the South China Sea

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


    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.

  3. Tendency in power development of India, China and South Korea

    Basic directions for the development of the energetics in India, China and South Korea are outlined. Data on supply and demand, growth of deficit of electric energy, plan for the development of the energetics and input of new powers in India are discussed. State of the economy and plans of the economic development including the construction of NPP in China are considered. Maximum part of common power in the energetic structure of South Korea is noted to be due to the nuclear power

  4. Complete Nucleotide Sequence of Encephalomyocarditis Virus Isolated from South China Tigers in China

    Liu, Huimin; Yan, Qi; He, Hongxuan


    A strain of encephalomyocarditis virus (EMCV), strain FJ13, has been isolated from South China tigers in China, and its complete genome has been sequenced and analyzed. Phylogenetic analysis suggests that FJ13 belongs to the EMCV-1 serotype, and it is highly prevalent in China.

  5. Tectonics and sedimentation in the Curitiba Basin, south of Brazil

    Salamuni, Eduardo; Ebert, Hans Dirk; da Silva Borges, Mauricio; Hasui, Yociteru; Costa, João Batista Sena; Salamuni, Riad


    The Curitiba Basin, Paraná, lies parallel to the west side of the Serra do Mar range and is part of a continental rift near the Atlantic coast of southeastern Brazil. It bears unconsolidated and poorly consolidated sediments divided in two formations: the lower Guabirotuba Formation and the overlying Tinguis Formation, both developed over Precambrian basement. Field observations, water well drill cores, and interpretations of satellite images lead to the inference that regional tectonic processes were responsible for the origin of the Basin in the continental rift context and for morphotecatonic evolution through block tilting, dissection, and erosion. The structural framework of the sediments and the basement is characterized by NE-SW-trending normal faults (extensional tectonic D 1 event) reactivated by NE-SW-trending strike-slip and reverse oblique faults (younger transtensional tectonic D 2' to transpressional tectonic D 2″ event). This tectonic event, which started in the Paleogene and controlled the basin geometry, began as a halfgraben and was later reactivated as a pull-apart basin. D 2 is a neotectonic event that controls the current morphostructures. The Basin is connected to the structural rearrangement of the South American platform, which underwent a generalized extensional or trantensional process and, in late Oligocene, changed to a compressional to transpressional regime.

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

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


    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.

  7. Effects of Integrated Exploration in Hydrocarbon-Prospective Areas of South China

    KongFanshu; Zhengli; LiZhiming


    The complicated topography, morphology and geology are characteristic of South China, where the frequently covered waters and igneous bodies and widely exposed carbonates are difficult to seismic survey. This paper describes the effect of combining exploration of gravitational, magnetic and electric methods in the complicated hydrocarbon areas in South China by some case histories. Many year''s exploration practices in the exploring areas of more than 20 show that the non-seismic integrated (gravity/magnetic/electric) geophysical prospecting can play an important role not only in regional assessment, basin optimization and early basin evaluation,but also in finding objective of low resistance in areas of exposed carbonate with high resistance, contouring local structure, outlining igneous body and reef, and differentiating rock facies of basement. The results of the non-seismic integrated geophysical survey have pointed out the direction for deploying next prospecting in the specific areas of South China and the valuable experiences have been accumulated to carry out hydrocarbon-hunting in the future.

  8. Diversity and paleobiogeographic distribution patterns of Early and Middle Ordovician graptolites in distinct depositional environments of South China

    Dan; GOLDMAN


    An analysis of Ordovician graptolite diversity across several distinct lithofacies belts in South China,which represent nearshore,inner-shelf,outer-shelf,slope,and basin environments,indicates that diversity increases progressively from nearshore toward the outer-shelf,acquiring its maximum in the slope facies and thereafter decreases slightly in basinal facies.When scaled against graptolite zones and more equal duration ’Time Units’,the graptolite diversity patterns of the Early and Middle Ordovician are broadly similar among the distinct environments of South China but exhibit some important differences.A synthesized graptolite diversity curve from the Early Ordovician to the Sandbian Stage of the Late Ordovician in South China displays a step-wise increase with three peaks:1) middle Floian(Early Ordovician),2) late Dapingian-early Darriwilian(Middle Ordovician),and 3) latest Darriwilian(Middle Ordovician),which closely coincide with transgressive events in South China,implying a likely correlation.The biogeographic distribution of four graptolites with different ecological preferences,Pseudisograptus,Isograptus-Parisograptus,Undulograptus austrodentatus,and Corymbograptus turgidus,displays a significant parallelism with the coast or shelf margin,suggesting that their distributions may be controlled by water depth,basin morphology,and the distance from the coast.

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

    Halik, N. (Pertamina EP R D, Jakarta (Indonesia)); Wu, C. (ARCO International Oil and Gas Co., Plano, TX (United States))


    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.

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

    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

  11. Crustal P-wave velocity structure and layering beneath Zhujiangkou-Qiongdongnan basins, the northern continental margin of South China Sea%南海北部珠江口-琼东南盆地地壳速度结构与几何分层

    张中杰; 刘一峰; 张素芳; 张功成; 范蔚茗


    基于南海北部大陆边缘珠江口-琼东南盆地深水区实施的14条近垂直深反射地震探测叠加速度谱,利用Dix公式将叠加速度剖面转换为地壳层速度剖面,并利用时深转换方法构建了深度域地壳层速度模型,综合各地壳速度剖面分析了南海北部大陆边缘珠江口与琼东南盆地不同深度层次的P波速度变化趋势以及地壳几何分层特征.结果表明,琼东南盆地区可分为4~8 km沉积层(V_P为1.7~4.7 km/s)、4~10 km厚的上地壳层(V_P为5.2~6.3 km/s)、5 km左右的下地壳层(V_P为6.4~7.0 km/s)以及2~6 km厚的高速下地壳底层(V_P>7.0 km/s).V_P>7.0 km/s下地壳高速层的存在被认为是岩石圈伸展、下地壳底部底辟构造或者是残存的原始华夏下地壳基性层的地震学指示;综合研究区地球物理探测成果构建了跨越华南大陆与南海北部陆坡区剖面莫霍和岩石圈底界图像,揭示出岩石圈上地幔在华南大陆与南海北部大陆边缘的减薄特征.%Base on stack velocity spectrum dataset of 14 near-vertical deep reflection profiles in the Zhujiang River estuary-Qiongdongnan basin in the continental margin of northern South China Sea, we use Dix formula to transform the corresponding stack velocities into the crustal-layer-velocities (in TWT domain) and convert the layer velocities into the depth domain by time-depth transformation scheme. Integrating all the crustal velocity models, we analyze the spatial variation of P wave velocity in different depths and the stratified geometry of crust in the Yinggehai and Qiongdongnan basin area in the continent margin of northern South China Sea. The results demonstrate that the kinematic structure of Qiongdongnan basin can be divided into 4 ~8km thick sediment layer (V_p is 1. 7~4. 7 km/s), 4~10 km thick upper crust (V_p is 5. 2~6. 3 km/s), about 5 km thick normal lower crust (V_p is 6. 4~7. 0 km/s) and about 2~6 km thick anomalous lower crust with high

  12. Relationship between Crustal Structure and Tin Mineralization in South China


    A close relationship between tin metallogenic and crustal structure in South China is demonstrated, which is based on a careful study on crustal structure and a detailed comparison between typical deposits in different tectonic units. Types, locations, emplacement of ore bodies and ore genesis of tin deposits are relative to crustal structure. Tin mineralization zones of South China can be divided into three tin metallogenic units including the west part corresponding to Youjiang fold belt, middle part corresponding to fold belt of Hunan-Guangdong-Jiangxi provinces and the east part corresponding to Southeast China coastal volcanic faulting depression. From the above, it is concluded that crustal compositions and structures are the main facts of Sn concentration in South China.

  13. The deep thermal characteristic of continental margin of the northern South China Sea


    Heat flow plays an important role in the study of thermal structure and thermal evolution of continental margin of the northern South China Sea. The analysis of heat flow value shows that margin heat flow in the northern South China Sea is relatively high setting, but the percentage of crustal heat flow is lower than 35% in terrestrial heat flow. The terrestrial heat flow exhibited a current of rise from the Northern Continental Margin to the Southern Central Basin. However, the proportion of crustal heat flow in terrestrial heat flow slowly dropped down in the same direction. It is suggested that the main factor causing high heat flow setting is the moving up of hot material from asthenosphere.

  14. Lithologic Hydrocarbon Deposits in Rift Lake Basins in Eastern China

    ZHENG Herong; HE Zongquan


    The rift lake basins in the eastern China have abundant hydrocarbon resources of lithologic deposits, which resulted from excellent source rocks and multi-type sandbodies developed during strong rifting. Vertically, the lithologic deposits are mainly distributed in the lowstand, lacustrine invasion and early highstand systems of third-order sequence corresponding to a secondary tectonic episode of strong rifting, and laterally they are closely related to various fans and turbidite sandbodies controlled by syn-sedimentary faults. A variety of lithologic traps have been developed in the rift lake basins, and they generally have favorable conditions of source-reservoir-seal assemblage and hydrocarbon accumulation dynamics, indicating that there is a great exploration potential of lithologic deposits in the rift lake basins.In order to obtain satisfactory effects of lithologic deposit exploration, it is required to combine new theories with advanced technical methods.

  15. Territorial disputes simmer in areas of South China Sea

    This paper reports that China's award of an exploration cooperation contact in the Nansha area of the South China Sea has revived territorial disputes in the area centering ton the Spratly and Paracel islands. The key dispute is between China and Viet Nam, which earlier engaged in military action over ownership of the islands, believed to have world class potential for hydrocarbon discoveries. Those two nations, as well as Brunei, Malaysia, Philippines, and Taiwan, lay claim to overlapping boundaries of the Spratly Islands. Separately, China and Viet Nam dispute territorial claims in the Paracels. Tensions continue to mount, and regional governments are trying to negotiate compromises to avoid a repeat of warfare

  16. A numerical study of the South China Sea deep circulation and its relation to the Luzon Strait transport



    A fine-resolution MOM code is used to study the South China Sea basin-scale circulation and its relation to the mass transport through the Luzon Strait. The modal domain includes the South China Sea, part of the East China Sea, and part of the Philippine Sea so that the currents in the vicinity of the Luzon Strait are free to evolve. In addition, all channels between the South China ,Sea and the Indonesian seas are closed so that the focus is on the Luzon Strait transport. The model is driven by specified Philippine Sea currents and by surface heat and salt flux conditions. For simplicity, no windstress is applied at the surface.The simulated Luzon Strait transport and the South China Sea circulation feature a sandwich vertical structure from the surface to the bottom. The Philippine Sea water is simulated to enter the South China Sea at the surface and in the deep ocean and is carried to the southern basin by western boundary currents. At the intermediate depth, the net Luzon Strait transport is out of the South China Sea and is fed by a western boundary current flowing to the north at the base of the thermocline. Corresponding to the western boundary currents, the basin circulation of the South China Sea is cyclonic gyres at the surface and in the abyss but an anti-cyclonic gyre at the intermediate depth. The vorticity balance of the gyre circulation is between the vortex stretching and the meridional change of the planetary vorticity.Based on these facts, it is hypothesized that the Luzon Strait transports are determined by the diapycnal mixing inside the entire South China Sea. The South China Sea plays the role of a "mixing mill" that mixes the surface and deep waters to return them to the Luzon Strait at the intermediate depth. The gyre structures are consistent with the Stommel and Arons theory (1960), which suggests that the mixlng-induced circulation inside the South China Sea should be cyclonic gyres at the surface and at the bottom but an anti

  17. New progresses on geothermal history of Turpan-Hami Basin, Xinjiang, China


    A comprehensive study on geothermal history of the Turpan-HamiBasin by vitrinite reflectance, fluid inclusion geothermometry, apatite fission track and 40Ar-39Ar dating displays that the main effects influencing geotemperature distribution are burial depth of the basement, heat flow, magmatic activities, as well as tectonic movement, having a rugulation to be higher in the east and north, lower in the west and south, as well as higher in the past and lower at the present. The heat of the mantle source and the Indo-China tectonic thermal event have extremely influenced matura-tion of source rocks of the upper Lower Permian and the Middle and Upper Triassic in the lndo-China epoch. While, the geothermal gradient and the weak tectonic geothermal event of the Early Yanshan Movement provided necessary heat for the maturation of source rock in coal-bearing strata of the Middle and Lower Jurassic.

  18. Records of Toba eruptions in the South China Sea

    LlANG; Xirong


    [1]Rose,W. I., Chesner, C. A., Dispersal of ash in the great Toba eruption, 75 ka, Geology, 1987, 15: 913-917.[2]Acharyya, S. K., Basu, P. K. ,Toba ash on the Indian subcontinent and its implications for correlation of late Pleistocene alluvium, Quaternary Research, 1993, 40: 10-19.[3]Shane, P., Westgate, J., Williams, M. et al., New geochemical evidence for the youngest Toba Tuff in India, Quaternary Research, 1995, 44: 200-204.[4]Westgate, J. A., Sha ne, P. A. R., Pearce, N. J. G. et al., All Toba occurrences across Peninsular India belong to the 75000yr B. P. eruption, Quaternary Research, 1998, 50:107-112.[5]Pattan, J. N., Shane, P., Banakar, V. K., New occurrences of youngest Toba Tuff in abyssal sediments of the Central Indian Basin, Marine Geology, 1999, 155: 243-248.[6]Gasparotto, G., Spadafora, E,, Summa, V. et al., Contribution of grain size and compositional data from the Bengal Fan sediment to the understanding of Toba volcanic event, Marine Geology, 2000, 162: 561-572.[7]Dehn, J., Farrell, J. W., Schmincke, H. U., Neogene tephrochronology from Site 758 on northern Ninetyeast Ridge: Indon isian arc volcanism of the Past 5 Ma, Proceedings of the Ocean Drilling Program, Scientific Results (eds. Weissel, J. P.,Taylor, E., Alt, J. et al.), College Station, Texas, Ocean Drilling Program, 1991, 121: 273-295.[8]Lee M. Y., Wet, K. Y., Chen, Y. G., High-resolution oxygen isotope stratigraphy for the last 150000 years in the southern South China Sea, Terrestrial, Atmospheric and Oceanic Sciences TAO, 1999, 10: 239-254.[9]Biihring, C., Sarnthein, Toba ash layers in the South China Sea: Evidence of contrasting wind directions during eruption ca.74 ka, Geology, 2000, 28: 275-278.[10]Chesner, C. A., Petrogenesis of the Toba tuffs, Sumatra, Indonesia, Journal of Petrology, 1998, 39: 397-438.[11]Rampino, M. R., Self. S., Volcanic winter and accelerated glaciation follow ing the Toba super-eruption, Nature, 1992, 359:50-52.

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

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


    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.

  20. Characteristics of high arsenic groundwater in Hetao Basin, Inner Mongolia, northern China

    YangChun Zhu; XueYong Zhao; Min Chen; YongQing Luo; Xin Zhou


    It is well known that the Hetao Basin is one of the most seriously arsenic-affected groundwater areas in China. In order to understand the characteristics of high arsenic (As) groundwater in the Basin, a brief overview of arsenic in groundwater follows. High arsenic in the Basin commonly occurs in shallow groundwater and the total arsenic concentrations range from 0.58 to 572 µg/L (average 99.73 µg/L), exceeding the maximum mandated value of 10 µg/L for drinking water in China;As(Ш) is the predominant species. The regional distribution pattern of arsenic in the groundwater increases from south/southeast to north/northwest. Hangjinhouqi and Wuyuan counties are considered as the most seriously affected areas, with high incidences of endemic arsenicosic diseases in the Hetao Basin. High groundwater arsenic correlates with the increase of well depth. Previous studies proposed that groundwater arsenic in the Basin is mainly originated from desorption of some natural solid materials in the sediments, under reducing condition. Generally, reducing condition is believed to be the primary factor for arsenic releasing from the sediment to groundwater in the region. Under inorganic or bacterial processes, Fe2O3 changes to FeS and arsenic adsorbed to Fe(OH)3 dissolves into groundwater, and As(V) is re-duced to As(Ш). Besides, reducing environments, groundwater hydraulic gradients, organic matter, pH, evapotranspiration, and soil texture are presumed to be the predominant factors that control arsenic mobilization.

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

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


    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.

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

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


    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.

  3. Sedimentary basin analysis using airborne gravity data: a case study from the Bohai Bay Basin, China

    Li, Wenyong; Liu, Yanxu; Zhou, Jianxin; Zhou, Xihua; Li, Bing


    In this paper, we discuss the application of an airborne gravity survey to sedimentary basin analysis. Using high-precision airborne gravity data constrained by drilling and seismic data from the Bohai Bay Basin in eastern China, we interpreted faults, structural elements, sedimentary thickness, structural styles and local structures (belts) in the central area of the Basin by the wavelet transform method. Subsequently, these data were subtracted from the Bouguer gravity to calculate the residual gravity anomalies. On this basis, the faults were interpreted mainly by linear zones of high gravity gradients and contour distortion, while the sedimentary thicknesses were computed by the Euler deconvolution. The structural styles were identified by the combination of gravity anomalies and the local structures interpreted by the first vertical derivative of the residual gravity. The results showed evidence for seven faults, one sag and ten new local structure belts.

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

    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

  5. Water Pricing Policy in Tarim Basin of China

    施祖麟; 许丽芬


    China ranks the thirteenth among countries with serious water shortage problems in the world. The average amount of water owned per person is only 2400 m3/year, which is about 1/4 of the world average. But unfortunately, the efficiency of water use, especially in agriculture in some arid areas, is very low, only 20% -30% in some areas. The main reason is that water prices are too iow to protect the water resources. In this paper, the Tarim Basin of southern Xinjiang is selected to study the water supply costs and farmer's tolerance of water expenses based on a great amount of data collected in the four prefectures in the Tarim Basin. Then, three steps are suggested for water pricing reform in the Tarim Basin. Finally, several possible water pricing patterns are presented, such as water coupons, seasonal floating prices, and water price counting in kind but paying in currency. The conclusion is that the present water price system should be reformed and the water price can be increased to some extent for agricultural use even in Xinjiang, a developing area in China.

  6. Using Google Trends for Influenza Surveillance in South China

    Kang, Min; Zhong, Haojie; He, Jianfeng; Rutherford, Shannon; Yang, Fen


    Background Google Flu Trends was developed to estimate influenza activity in many countries; however there is currently no Google Flu Trends or other Internet search data used for influenza surveillance in China. Methods and Findings Influenza surveillance data from 2008 through 2011 were obtained from provincial CDC influenza-like illness and virological surveillance systems of Guangdong, a province in south China. Internet search data were downloaded from the website of Google Trends. Pears...

  7. Crust and upper mantle structure and its tectonic implications in the South China Sea and adjacent regions

    Tang, Qunshu; Zheng, Chan


    We present a 3D S-velocity model for the crust and upper mantle of the South China Sea and the surrounding regions, constrained from the analysis of over 12,000 of fundamental Rayleigh wave dispersion curves between 10 s and 150 s periods. The lateral resolution was found to vary from 2° to 4° with the increasing period over the study region. A robust scheme of Debayle and Sambridge allowed us to conduct the tomographic inversion efficiently for massive datasets. Group velocity maps varying with period show lateral heterogeneities, well related to the geological and tectonic features in the study region. The 3D S-velocity model was constructed from the 1D structure inversion of the tomographic group velocity dispersion curves at each node. The obtained average crustal structure is similar to the PREM model, while the average mantle velocity is typically lower than the global average. The complicated 3D structures reveal three prominent features correlated with geological divisions: sea basin regions, island and arc regions, and continental regions. The derived crustal and lithospheric thicknesses range from ˜15 to >50 km and from ˜60 to >140 km, respectively, with the thinnest in the South China Sea, the thickest in eastern Tibet and the Yangtze Block, and the medium in the South China Fold Belt, Indochina, and island arc regions. Our results further confirm that (1) a Mesozoic subduction zone, which is interpreted as the tectonic weak zone during the Paleogene, exists along the South China margin; (2) the influence of the Indochina extrusion along the Red River Fault is limited for the South China Sea region; (3) there is a slab remnant of the proto-South China Sea beneath Borneo. New findings suggest that the Mesozoic subduction zone should be built into any evolution model for the region, as well as the other two major tectonic boundaries of the Red River Fault and proto-South China Sea subduction zone.

  8. South Africa Keen to Tap China's Tourism Market

    Li Zhen


    @@ On August 23,South African president Jacob Zuma arrived in Beijing,starting a four-day to China.The visit is set to strengthen business ties and broaden political and cultural relationship between the two countries.President Zuma was accompanied by a group of senior ministers and a delegation of more than 200 leading South African businessmen and entrepreneurs.A business seminar between the two countries was also held.

  9. China’s Legal Enforcement on Anti-Piracy in South China Sea

    Yingying Deng


    The South China Sea is considered the most dangerous area for piracy in the world.China has a strong economic interest in South China Sea and Strait of Malacaa maritime security. In recent year, China has taken effective measures in combating piracy in the South China Sea. In order to build the legislation and law-enforcement on anti-piracy, the author put forward some suggestion.

  10. China’s Legal Enforcement on Anti-Piracy in South China Sea

    Yingying Deng


    Full Text Available The South China Sea is considered the most dangerous area for piracy in the world.China has a strong economic interest in South China Sea and Strait of Malacaa maritime security. In recent year, China has taken effective measures in combating piracy in the South China Sea. In order to build the legislation and law-enforcement on anti-piracy, the author put forward some suggestion.

  11. Bumper harvest of super rice in south and north China


    @@Recently. a great progress was made in breeding and cultivation of super rice in China. The South Demonstration Acceptance Meeting of China Super Rice was held in Oct 17. 2000 in Xinchang County, Zhejiang Province. Yield monitoring group organized by the Department of Science,Technology and Education, Ministry of Agriculture, China, was consisting of famous rice research scientists, agricultural technology extension experts, and government officials. In the demonstration meeting, the group investigated the rice growth of the demonstration field of the improved integrated cultivation technology of super hybrid rice, Xieyou 9308. Four representative demonstration fields from 6.87 ha of the demonstration were harvested after the current investigation of the group.

  12. Trends of sea level rise in the South China Sea during the 1990s: An altimetry result


    Using 7 years of TOPEX/POSEIDON satellite altimetry data, we have identified a general trend of sea level rising in the South China Sea between January 1993 and December 1999. The estimated bulk rising rate of the entire basin is ~1 cm/a. The rise of sea level appears to be spatially non-homogeneous, which shows a highest rate of 2.7 cm/a in the deep basin west of Luzon and generally Iow (even negafive) rates over the shallow continental shelves. It is believed that the observed rapid rising of sea level is a regional phenomenon and is mainly caused by warming of the upper layer of the South China Sea, which showed a bulk warming rate of 0.15℃/a in the same period. It is also suggested that the observed rising trend is mainly a decadal signal, which is possibly associated with decadal variation of the Pacific warm pool region.

  13. New production in the South China Sea

    CAI; Pinghe


    estuary, Acta Oceanologica Sinica (in Chinese), 1993, 15(4): 50-55.[12]Okubo, T., Furuyama, K., Sakanoue, M., Distribution of 228Ra in surface sea water of the east Indian Ocean, Geochimica Journal, 1979, 13: 201-206.[13]Moore, W. S., Oceanic concentrations of 228Ra, Earth and Planetary Science Letters, 1969, 17: 437-446.[14]Sakanoue, M., Okubo, T., Furuyama, K., 228Ra in sea water, in Isotope Marine Chemistry (eds. Goldberg, E. D., Horibe, Y., Saruhashi, K.), Tokyo: Uchida Rokakuho Publishing Co. Ltd, 1980.[15]Dunne, J. P., Murray, J. M., Rodier, M. et al., Export flux in the western and central equatorial Pacific: Zonal and temporal variability, Deep-Sea ResearchⅠ, 2000, 47: 901-936.[16]Diego-McGlone, M. L. S., Jacinto, G. S., Dupra, V. C. et al., A comparison of nutrient characteristic and primary produc-tivity in the Sulu Sea and South China Sea, Acta Oceanographica Taiwanica, 1999, 37(3): 219-229.[17]Emerson, S., Quay, P., Karl, D. et al., Experimental determination of organic carbon flux from open-ocean waters, Nature, 1997, 389: 951-954.

  14. Records of Toba eruptions in the South China Sea

    LlANG; Xirong


    [1]Rose,W. I., Chesner, C. A., Dispersal of ash in the great Toba eruption, 75 ka, Geology, 1987, 15: 913-917.[2]Acharyya, S. K., Basu, P. K. ,Toba ash on the Indian subcontinent and its implications for correlation of late Pleistocene alluvium, Quaternary Research, 1993, 40: 10-19.[3]Shane, P., Westgate, J., Williams, M. et al., New geochemical evidence for the youngest Toba Tuff in India, Quaternary Research, 1995, 44: 200-204.[4]Westgate, J. A., Sha ne, P. A. R., Pearce, N. J. G. et al., All Toba occurrences across Peninsular India belong to the 75000yr B. P. eruption, Quaternary Research, 1998, 50:107-112.[5]Pattan, J. N., Shane, P., Banakar, V. K., New occurrences of youngest Toba Tuff in abyssal sediments of the Central Indian Basin, Marine Geology, 1999, 155: 243-248.[6]Gasparotto, G., Spadafora, E,, Summa, V. et al., Contribution of grain size and compositional data from the Bengal Fan sediment to the understanding of Toba volcanic event, Marine Geology, 2000, 162: 561-572.[7]Dehn, J., Farrell, J. W., Schmincke, H. U., Neogene tephrochronology from Site 758 on northern Ninetyeast Ridge: Indon isian arc volcanism of the Past 5 Ma, Proceedings of the Ocean Drilling Program, Scientific Results (eds. Weissel, J. P.,Taylor, E., Alt, J. et al.), College Station, Texas, Ocean Drilling Program, 1991, 121: 273-295.[8]Lee M. Y., Wet, K. Y., Chen, Y. G., High-resolution oxygen isotope stratigraphy for the last 150000 years in the southern South China Sea, Terrestrial, Atmospheric and Oceanic Sciences TAO, 1999, 10: 239-254.[9]Biihring, C., Sarnthein, Toba ash layers in the South China Sea: Evidence of contrasting wind directions during eruption ca.74 ka, Geology, 2000, 28: 275-278.[10]Chesner, C. A., Petrogenesis of the Toba tuffs, Sumatra, Indonesia, Journal of Petrology, 1998, 39: 397-438.[11]Rampino, M. R., Self. S., Volcanic winter and accelerated glaciation follow ing the Toba super-eruption, Nature, 1992, 359:50-52.

  15. Clay Mineral Distribution Patterns of Tertiary Continental Oil-bearing Basins in China

    Zhao Xingyuan


    @@ Induction This paper studies the clay mineral distribution patterns of Tertiary continental oil-bearing basins in China. More than 9 000 shale samples from Paleogene (E) to Neogene (N) Series distributed in Bohai Gulf, Subei, Jianghan,Nanxiang, Zhoukou, Sanshui, Beibu Bay, East China Sea,Hetao, Juiquan, Qaidam and Tarim basins, and so on.

  16. Field experiment on transgenic cassava proves successful in South China


    @@ A pioneer study on field tests of transgenic cassava (Manihot esculenta Crantz) by a Sino-Swiss research consortium has proved successful. The experiment was carried out in 2006 at an experimental station in Haikou, capital of south China's Hainan Province.

  17. Antecedents of Medical Workplace Violence in South China

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


    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…

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

    Niu, Y.


    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

  19. Suggestion of a dynamic model of North China basin-range system


    It is found from preliminary studies that previous basin-range models have difficulties in explaining the formation of the Mesozoic North-China basin-range system. This work suggests a new model-"tectonic thermal erosion" model, which considers the North China basin of Late Mesozoic and its peripheral ranges as a unified system, identifies relationship between upwelling and lateral spreading of the asthenolith with horizontal movement and deformation of the upper crust in the system, clarifies the effects of underplating erosion on the crustal evolution, and tries to establish an earth-dynamic model of the North China Mesozoic basin-range supported by numerical simulation.

  20. Numerical assessment of factors affecting nonlinear internal waves in the South China Sea

    Li, Qiang


    Nonlinear internal waves in the South China Sea exhibit diverse characteristics, which are associated with the complex conditions in Luzon Strait, such as the double ridge topography, the Earth’s rotation, variations in stratification and the background current induced by the Kuroshio. These effects are individually assessed using the MITgcm. The performance of the model is first validated through comparison with field observations. Because of in-phased ray interaction, the western ridge in Luzon Strait intensifies the semidiurnal internal tides generated from the eastern ridge, thus reinforcing the formation of nonlinear internal waves. However, the ray interaction for K1 forcing becomes anti-phased so that the K1 internal tide generation is reduced by the western ridge. Not only does the rotational dispersion suppress internal tide generation, it also inhibits nonlinear steepening and consequent internal solitary wave formation. As a joint effect, the double ridges and the rotational dispersion result in a paradoxical phenomenon: diurnal barotropic tidal forcing is dominant in Luzon Strait, but semidiurnal internal tides prevail in the deep basin of the South China Sea. The seasonal variation of the Kuroshio is consistent with the seasonal appearance of nonlinear internal waves in the South China Sea. The model results show that the westward inflow due to the Kuroshio intrusion reduces the amplitude of internal tides in the South China Sea, causing the weakening or absence of internal solitary waves. Winter stratification cannot account for the significant reduction of nonlinear internal waves, because the amplitude growth of internal tides due to increased thermocline tilting counteracts the reduced nonlinearity caused by thermocline deepening.

  1. 中国太湖流域(江苏南部)人群复合污染经口途径暴露风险评估%Oral exposure risk assessment of combined pollution in Taihu Lake Basin of South Jiangsu Province, China

    杨彦; 王宗庆; 李定龙; 于云江


    The pollution of Cu, Pb, Cd and other heavy metals and organic contaminants (DDTs) in oral media (groundwater, soil, crops, 389) from Wuxi, Changzhou and Zhenjiang in the Taihu Lake Basin (south China) were analyzed by laboratory testing. The exposure risk assessment model recommended by U. S. EPA was used. The residents' oral route of exposure risk in Taihu Lake Basin was assessed with the measured exposure parameters and the dietary habits in China were considered. The results showed that the pollution of heavy metals and organic pollutants were serious in Taihu Lake Basin. The population risk of exposure by oral estimated by the traditional way in Taihu Lake Basin showed that the total exposure risk was 9. 07 × 10 to male and 1.00 × 10-2 to female. Considering the oral exposure risk in basin by the factors of the integrated treatment, the total exposure risk was 3.94 × 10-3 to male and 4. 35 × 10 -2 to female. The exposure risks food source by oral media from traditional methods and from post - integrated treatment were both higher than the acceptable level of risk. Carcinogenic risk was significantly higher than non-cancer risk, and the carcinogenic risk of Cd played an important role to the total risk of exposure. The carcinogenic risk of Pb was lower than that of Cd.%对太湖流域(江苏南部)无锡、常州、镇江3市经口介质(地下水、土壤、农作物共389个样品)中Cu、Pb、Cd等8种重金属和有机污染物DDTs的污染状况进行实验室分析,运用US EPA推荐的暴露风险评估模型,对研究区人群进行了暴露参数实测,考虑中国居民膳食习惯,对太湖流域居民经口途径的暴露风险进行评估.研究结果表明:太湖流域重金属、有机污染物污染较严重;传统方式估算的太湖流域人群经口暴露风险,男性总暴露风险为9.07 × 10-3,女性为1.00×10-2;考虑综合处理因素的流域人群经口暴露风险,男性为3.94×10-3,女性为4.35×10-3.食物源经口介质

  2. Tectonics and Petroleum Potential of the East China Sea Shelf Rift Basin


    There are two Cenozoic sedimentary basins in the East China Sea. They are the East China Sea shelf basin and the Okinawa Trough basin. The former can be divided into a western and an eastern rift region. The development of the shelf basin underwent continental-margin fault depression, post-rift and then tectonic inversion stages. Available exploration results show that the distribution of source rocks is controlled by the basin architecture and its tectonic evolution. In the Xihu depression, mudstones and coals are the main source rocks. The eastern rift region has good geological conditions for the formation of large oil and gas fields.

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

    Yan, Luobin; Hua, Peng; Simonson, Scott


    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

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

    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.


    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).

  5. Karst Aquifer Recharge: A Case History of over Simplification from the Uley South Basin, South Australia

    Nara Somaratne


    Full Text Available The article “Karst aquifer recharge: Comments on ‘Characteristics of Point Recharge in Karst Aquifers’, by Adrian D. Werner, 2014, Water 6, doi:10.3390/w6123727” provides misrepresentation in some parts of Somaratne [1]. The description of Uley South Quaternary Limestone (QL as unconsolidated or poorly consolidated aeolianite sediments with the presence of well-mixed groundwater in Uley South [2] appears unsubstantiated. Examination of 98 lithological descriptions with corresponding drillers’ logs show only two wells containing bands of unconsolidated sediments. In Uley South basin, about 70% of salinity profiles obtained by electrical conductivity (EC logging from monitoring wells show stratification. The central and north central areas of the basin receive leakage from the Tertiary Sand (TS aquifer thereby influencing QL groundwater characteristics, such as chemistry, age and isotope composition. The presence of conduit pathways is evident in salinity profiles taken away from TS water affected areas. Pumping tests derived aquifer parameters show strong heterogeneity, a typical characteristic of karst aquifers. Uley South QL aquifer recharge is derived from three sources; diffuse recharge, point recharge from sinkholes and continuous leakage of TS water. This limits application of recharge estimation methods, such as the conventional chloride mass balance (CMB as the basic premise of the CMB is violated. The conventional CMB is not suitable for accounting chloride mass balance in groundwater systems displaying extreme range of chloride concentrations and complex mixing [3]. Over simplification of karst aquifer systems to suit application of the conventional CMB or 1-D unsaturated modelling as described in Werner [2], is not suitable use of these recharge estimation methods.

  6. Numerical Analysis and Simulation Experiment of Lithospheric Thermal Structures in the South China Sea and the Western Pacific

    Lin Ge; Peng Meili; Zhao Chongbin; Zhang Lu; Zhang Desheng; Liu Shilin


    The asthenosphere upwelled on a large scale in the western Pacific and South China Sea during the Cenozoic,which formed strong upward throughflow and caused the thermal structure to be changed obviously.The mathematical analysis has demonstrated that the upward throughflow velocity may have varied from 3×1011 to 6×1012 m/s.From the relationship between the lithospheric thickness and the conductive heat flux,the Hthospherie heat flux in the western Pacific should be above 30 mW/m2,which is consistent with the observed data.The huge low-speed zone within the upper mantle of the marginal sea in the western Pacific reflects that the upper mantle melts partially,flows regionally in the regional stress field,forms the upward heat flux at its bottom,and causes the change of the lithospheric thermal structure in the region.The numerical simulation result of the expansion and evolution in the South China Sea has demonstrated that in the early expansion,the upward throughflow velocity was relatively fast,and the effect that it had on the thickness of the lithosphere was relatively great,resulting in the mid-ocean basin expanding rapidly.After the formation of the ocean basin in the South China Sea,the upward throughflow velocity decreased,but the conductive heat flux was relatively high,which is close to the actual situation.Therefore,from the heat transfer point of view,this article discusses how the upward heat flux affects the lithospheric thermal structure in the western Pacific and South China Sea.The conclusions show that the upward heat throughflow at the bottom of the llthospheric mantle resulted in the tectonic deformation at the shallow crust.The intensive uplifts and rifts at the crust led to the continent cracks and the expansion in the South China Sea.

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

    Briais, Anne


    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.

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

    Strozyk, Frank; Back, Stefan; Kukla, Peter


    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

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

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


    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.

  10. Fractal dynamics of uranium mineralization in south China

    South China is the most important uranium producing area in China, including four types of uranium deposits: granitic type, volcanic type, carbonaceous-siliceous-pelitic type and sandstone type. The fractal characters and fractal dynamic mechanism of ore-forming of uranium deposits in this region were analyzed using fractal theory. The U deposits in South China behave fractal distribution with fractal dimension of 1.0468, 1.4774, 0.2883, and 0.48 for uranium deposits space distribution, grade distribution, tonnage distribution and grade- tonnage relation, respectively. The fractal dynamic evolution of fracturing and ore-forming were modeled with percolation theory of cellular automation model. The results show that the fractal dimension of fracture and mineralization increases with evolution time. The fractal dimension was small and only scattered mineralization occurred at early stage. Evolving to mid-late stage, the fractal dimension of fracture increased to exceeding threshold; a large mineralization occurred and the fractal dimension of mineralization increased markedly. The fractal evolution of fracture system resulted in the fractal distribution of uranium deposits in South China. (authors)

  11. Accumulation and exploration of gas hydrate in deep-sea sediments of northern South China Sea

    ZHANG Guangxue; CHEN Fang; YANG Shengxiong; SU Xin; SHA Zhibin; WANG Hongbin; LIANG Jinqiang; ZHOU Yang


    The large deep-sea area from the southwestern Qiongdongnan Basin to the eastern Dongsha Islands,within the continental margin of northern South China Sea,is a frontier of natural gas hydrate exploration in China.Multiform of deep-sea sedimentations have been occurred since late Miocene,and sediment waves as a potential quality reservoir of natural gas hydrate is an most important style of them.Based on abundant available data of seismic,gravity sampling and drilling core,we analyzed the characteristics of seismic reflection and sedimentation of sediment waves and the occurrence of naturat gas hydrate hosted in it,and discussed the control factors on natural gas hydrate accumulation.The former findings revealed the deep sea of the northern South China Sea have superior geological conditions on natural gas hydrate accumulation.Therefore,it will be of great significance in deep-sea natural gas hydrate exploration with the study on the relationship between deep-sea sedimentation and natural gas hydrate accumulation.

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

    J. R. Miller


    Full Text Available 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

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

    YUAN Shengqiang; L(U) Fuliang; WU Shiguo; YAO Genshun; MA Yubo; FU Yanhui


    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 Piiocene, 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.

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

    Qin, Peihua; Xie, Zhenghui


    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.

  15. Geological conditions of coal and gas(oil)-bearing basins in China

    WANG; Tingbin


    There are various types of coal basins in China. Indosinian movement can be regarded as their evolutionary limit, and the basins can be divided into two developmental stages, three structural patterns and two sedimentary environments. However, only those coal measure strata that have been deeply buried in the earth are possible to be converted into coal and gas (oil)-bearing basins. Among which, only part of the coal measures possess the essential geological conditions to the formation of commercial humic oil. However, humic gas will be the major exploration target for natural gas in China. Among various coal basins, foreland basins have the best prospect for humic gas. Rift (faulted) basins accumulate the most abundance of humic gas, and are most favorable to generate humic oil. Craton basins have relatively low abundance of humic gas, but the evolution is rather great. The three kinds of coal basins mentioned above constitute China's three primary accumulation areas of humic gas: western, central and offshore areas. The major basins for humic gas field exploration include Tarim, Ordos, Sichuan, East China Sea and Yingqiong basins.

  16. Modern pollen rain in the Lake Qinghai basin, China


    Lake Qinghai is the largest inland brackish lake in China and lies within the NE Tibetan Plateau. Our study shows that pollen assemblages in each vegetation belt are significantly correlated with the vegetation types of this area. Among the herbaceous and shrubby pollen assemblages, Artemisia is over-represented, while Poaceae, Cyperaceae and Polygonaceae are under-represented. Artemisia/ Chenopodiaceae (A/C) ratios with the regional vegetation characteristic can be used as a proper index to reconstruct the history of vegetation and climate in Lake Qinghai basin. Modern pollen in the lake mainly comes from the nearby vegetation, controlled by the directions and velocity of the wind. The distribution of modern pollen in Lake Qinghai tends to be similar in most part of the lake. The difference of pollen sedimentation process in the lake can be potentially influenced by the focusing function of the lake, river streams, and lake current.

  17. Climate analysis of evaporation ducts in the South China Sea

    McKeon, Brian D.


    Approved for public release; distribution is unlimited. Evaporation ducts have important implications for U.S. Naval activities involving electromagnetic propagation. The presence of an evaporation duct can affect naval operations involving communications, surveillance, electronic warfare, and detection of low-flying missiles, surface ships, or submarine periscopes. We conducted a climate scale analysis of evaporation duct heights (EDH) in the northern South China Sea (SCS), including how ...

  18. Pork Preference for Consumers in China, Japan and South Korea

    Oh, S.-H.; See, M. T.


    Competition in global pork markets has increased as trade barriers have opened as a result of free trade agreements. Japanese prefer both loin and Boston butt, while Chinese prefer pork offal. Frozen pork has increased in terms of imports into China. Japanese consumers consider pork meat origin along with pork price when making purchase decisions. While the Chinese prefer a strong tasting pork product, South Korean consumers show very strong preferences to pork that is higher in fat. Therefor...

  19. Summary of The 3 South China Cardiovascular Scientific Sessions

    刘伊丽; 曾冲


    @@The 3rd South China Cardiovascular Scientific Sessions was held on August 4th ~ 6th, 2001 in Guangzhou.There were a total of 119 papers published, 13 lectures given by well- known cardiologists from inland and other parts of the world and 13 satellite conferences.These sessions were characterized by abundant updated information and advance in research on cardiovascular diseases in basic and clinical sciences. They are summarized as follows:

  20. Uranium rich granite and uranium productive granite in south China

    The paper briefly introduces the differences between uranium rich granite and uranium productive granite in the 5 provinces of South China, and discusses their main characteristics in 4 aspects, the uranium productive granite is highly developed in fracture, very strong in alteration, often occurred as two-mica granite and regularly developed with intermediate-basic and acid dikes. The above characteristics distinguish the uranium productive granite from the uranium rich granite. (authors)

  1. A reanalysis dataset of the South China Sea

    Zeng, Xuezhi; Peng, Shiqiu; Li, Zhijin; Qi, Yiquan; Chen, Rongyu


    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 ...

  2. Fourth China-South Asia International Cultural Forum


    <正>The Fourth China-South Asia International Cultural Forum on "revitalizing people-to-people cultural exchanges for peace and prosperity",co-sponsored by the CPAFFC and Shenzhen University,was held in Shenzhen from November 14 to 17,2012. More than 60 experts and scholars from over 40 Chinese research institutes and their colleagues from India,the United States and Singapore engaged in in-depth discussions on economic cooperation and cultural development,the present condi-

  3. Sustainable development of agriculture in karst areas, South China

    Linhua Song


    The exposed carbonate rocks aged from Sinian to Mid-Triassic Periods cover an area of 500,000 Km2 in south-west China. In karst areas with spectacular landscapes characterized by magnificent tower karst and conical karst, rare surface drainage systems and prevalent subsurface drainage systems, the environment is ecologically very fragile. The rapid increase of population, over deforested and cultivated lands, worsted the ecological system, causing a higher frequency of draught, flood and vari...

  4. Scientific questions about South China Sea ocean dynamics

    HUANG Rui Xin; DU Yan


    South China Sea, its circulation and connection with other parts of the world oceans, poses important scientific questions. From the prospective view, we postulate ten key research directions to be pursued in the coming future, including ventilation of a monsoon dominated sea, water mass formation/transformation, heat/salt and water mass balance, energetics and mixing, mesoscale eddies, the role of typhoon, deep circulation and paleoclimate records, interaction with adjacent oceans, upwelling and ecology system, and response to climate changes.

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

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


    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

  6. Hydrological Characteristics of the Heihe River Basin in the Arid Inland Area of Northwest China


    The hydrological characteristics of the Heihe River Basin in the arid inland area of northwest China were investigated.The spatial distribution of annual precipitation in the basin indicates that it decreases from east to west and from south to north,and increases with elevation by a gradient of 24.4 mm per hundred meters below 2,810 m a.s.l.,but decreases with elevation by that of 37.0 mm per hundred meters above 2,810 m a.s.l.For the last 50 years,the mountain runoff of the ba-sin has a tendency of increase.Except in the mountain area,the aridity is very high in the basin,and the aridity index ranges from 1.6 to 7.0 at the piedmont,to 9.0~20.0 in the midstream area and up to 40.0 in the downstream Ejin region.It is estimated for the last 50 years that a 1oC increment of annual temperature causes a 21.5 mm increase of evaporation in the mountain area,and the equivalent reduction of mountain runoff is 0.215×109 m3/yr at the Yingluoxia Hydrometric Sta-tion.The estimation shows also that a 1oC increment of annual temperature causes 1,842 mm increase of farmland evapotranspiration in the midstream area,an equivalent of 0.298×109 m3/yr more water consumption.The anthropogenic influence on the hydrological processes and water resources is then discussed.

  7. 78 FR 65706 - Ferrovanadium From China and South Africa; Institution of Five-Year Reviews


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

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

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


    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.

  9. Does China and Africa South-South cooperation lead to economic development in Africa?

    Nonfodji, P.


    Full Text Available Since a few decades now Chinese enterprises’ investments abroad have seen a continuous and steady ascension. At first cautious and just across the Chinese national borders, these investments, slowly but surely, spread like a sheet of water that seeps into the heart of each continent on the globe. This global infiltration of Chinese companies coincides with the popularity in the use of the expression “South-South Cooperation” to characterize a type of relations between countries categorized as being “developing”. Accordingly this paper seeks to examine the role of the use of this concept as a “channel to achieve common development” in the context of Chinese enterprises’ outward direct investments in Africa adopting insights from international business production theories combined with an historical analysis of the notion of South-South Cooperation. Drawing on primary data gathered during my fieldwork in China in the period stretching from December 2011 to February 2012 and secondary data sources, it is argued that these Chinese investments supported by the Chinese government rhetoric on South-South cooperation, cannot lead to significant economic development in Africa like it has happened in China in the eighties. Rather and at most Chinese investments in Africa show some “trickle-down” effects characterised by very limited economic development in scattered localities throughout the African continent.

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

    J. R. Miller


    Full Text Available 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

  11. Typical basin-fill sequences and basin migration in Yanshan, North China--Response to Mesozoic tectonic transition

    LI; Zhong; LIU; Shaofeng; ZHANG; Jinfang; WANG; Qingchen


    Basin-fill sequences of Mesozoic typical basins in the Yanshan area, North China may be divided into four phases, reflecting lithosphere tectonic evolution from flexure (T3), flexure with weak rifting (J1+2), tectonic transition (J3), and rifting (K). Except the first phase, the other three phases all start with lava and volcaniclastic rocks, and end with thick coarse clastic rocks and/or conglomerates, showing cyclic basin development rather than simple cyclic rift mechanism and disciplinary basin-stress change from extension to compression in each phase. Prototype basin analysis, based on basin-fill sequences, paleocurrent distribution and depositional systems, shows that single basin-strike and structural-line direction controlling basin development had evidently changed from east-west to northeast in Late Jurassic in the Yanshan area, although basin group still occurred in east-west zonal distribution. Till Early Cretaceous, main structural-line strike controlling basins just turned to northeast by north in the studied area.

  12. The coral grayness in northern South China Sea and its description of interdecadal variation of precipitation in south China

    GU Dejun; WANG Dongxiao; SUN Donghuai; GAO Rongzhen; JI Zhongping


    The interdecadal variation of coral grayness in northern South China Sea (SCS) is studied using the annual mean coral grayness in northern SCS from 1789 to 1992 and annual precipitation at Guangzhou from 1908 to 1992 by Singular Spectrum Analysis (SSA), correlation analysis, Mann-Kendall's abrupt change analysis and composite analysis. The interdecadal variation of south China precipitation as reflected by the series of Guangzhou precipitation rebuilt with the coral grayness is discussed. The results show that the variation of coral grayness in SCS has significant terms of tendency, much-weighted interdecadal variation and weak interannual variation.There was a century-scale abrupt change of coral grayness at the end of the 1880s that changed from positive anomalies to negative anomalies. The global field of SST difference corresponding to the point of abrupt change was negative anomalies over the SCS and neighboring northern Indian Ocean, most of central and western Pacific Ocean and coastal areas of the northern Atlantic Ocean. The large-scale distribution of SST anomalies is concomitant with the century-scale abrupt change of coral grayness in SCS. Negative correlation exists between the coral grayness in SCS and precipitation in Guangzhou on the interdecadal scale and the interdecadal precipitation in Guangzhou as reflected by the interdecadal data of SCS coral grayness shows that the interdecadal variation of south China precipitation changes significantly from phase to phase. The current study aims at contributing in the effort of identifying alternative indexes for climate change in south China on the interdecadal scale and beyond.

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

    D. Wu


    Full Text Available 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.

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

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


    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.

  15. Paleoenvironmental reconstruction of the late Cenozoic Qaidam Basin, China

    Zhang, C.; Wang, Y.; Li, Q.; Wang, X.; Deng, T.; Tseng, Z. J.; Takeuchi, G.; Xie, G.; Xu, Y.


    Reconstruction of paleoenvironments in the Tibetan region is important to understanding the linkage between tectonic force and climate change. Here we report new isotope data from the Qaidam Basin, China, which is located on the northeastern Tibetan Plateau, including stable C and O isotope analyses of a wide variety of late Cenozoic mammalian tooth enamel samples (including deer, giraffe, horse, rhino, and elephant), and O isotope compositions of phosphate (δ18Op) in fish bone samples. Mammalian tooth enamel δ13C values, when combined with fossil assemblage and other geological evidence, indicate that the Qaidam Basin was warmer and more humid during the late Miocene and early Pliocene, and that there was lush C3 vegetation with significant C4 components at that time, although the C4 plants were not consistently utilized. In contrast, the modern Qaidam Basin is dominated by C3 plants. Fish bone δ18Op values showed statistically significant enrichment from the Tuxi-Shengou-Naoge interval (late Miocene) to the Yahu interval (early Pliocene) and from the Yahu interval to the present day. This most likely reflects increases in the δ18O of lake water over time, as a result of increased aridification of the Qaidam Basin. Assuming that mammals drank exclusively from the lake, temperatures were calculated from average δ18Op values and average δ18Ow derived from large mammal tooth enamel δ18O. Temperatures were also estimated from δ18Op and δ18Ow estimated from co-ocurring large mammal tooth enamel δ18O. The temperature estimates were all lower than the average temperature of the modern Qinghai Lake surface water during the summer, and mostly too low to be reasonable, indicating that the fish and the large mammals were not in equilibrium with the same water. Assuming the relationship between salinity and δ18Ow observed for the modern Qinghai Lake and its surrounding lakes and ponds applied in the past, we calculated the paleosalinities of lake waters to be ~0 to

  16. Chlorine isotopic geochemistry of salt lakes in the Qaidam Basin, China

    Liu, W.G.; Xiao, Y.K.; Wang, Q.Z.; Qi, H.P.; Wang, Y.H.; Zhou, Y.M.; Shirodkar, P.V.

    The isotopic compositions of chlorine in salt lake brine coexisting with halite, oil-field water and river water from the Qaidam Basin (Qinghai, China) have been examined using high-precision measurement of chlorine isotopes based on thermal...

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

    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.


    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.

  18. The Oceanic Crustal Structure of the Southwestern Subbasin in the South China Sea

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


    Located at the southwestern part of the South China Sea (SCS) among the Zhongsha Islands(Macclesfield Bank), the east subbasin, the Nansha Islands(Dangerous Ground), the V type southwest subbasin (SWSB) is an unique ocean basin in all the three subbasins of SCS. The crustal structure is one of the key problems to study the formation and evolution of SWSB. During December 2010 to March 2011, Ocean Bottom Seismometers (OBSs) experiment has been carried out in the SWSB to get the deep crustal structure information, especially under the fossil spreading center. Three types of OBS, Sedis IV type, I-4C type and MicrOBS type have been used in the experiment, and the energy source was supplied by 6000 inch3 large volume air-gun. High quality seismic data of four 2D profiles which covered the fossil spreading center of SWSB have been acquired. The data of the experiment can supply evidence for the study of oceanic crustal structure of the SWSB and seafloor spreading course, etc. The profile 1 extended 130 km in length. A total of 8 OBSs were deployed at intervals of 10 or 15 km and 7 OBSs were recovered. The data of the 7 stations of profile 1 have been processed, which shows that the seismic records are clear and seismic phases are abundance, and the air-guns have enough energy supply. The velocity model was obtained by using an interactive trial-and-error 2D ray-tracing method. The crustal structure indicates that the crustal thickness under the SWSB is about 6 km, and the moho depth is about 10km. The results reveal that the crust of SWSB is normal oceanic crust with a thin sedimentary layer on the seamount and shallow moho surface. The crustal velocity under the spreading center is extremely low, which shows the characteristic of the deep crustal structure of the fossil spreading center. Acknowledgements This study was supported by the National Natural Science Foundation of China (Grant No. 91028006, 41106053, 41176046), Scientific Research Fund of the Second Institute

  19. The effects of China entering the World Trade Organization on the South Korean telecommunication industry

    Conner, William J.


    This thesis investigates the effects of China entering the World Trade Organization on the South Korean wireless telecommunication industry. Of particular interest, this thesis explores whether the South Korean wireless telecom industry will benefit from China's accession into the WTO. The working hypothesis of the thesis is that South Korean wireless telecom companies will receive far-reaching economic benefit from China's entry into the WTO. Additionally, this thesis explores the effec...

  20. Effects of Kuroshio intrusions on nonlinear internal waves in the South China Sea during winter

    Park, Jae-Hun; Farmer, David


    During winter the Kuroshio tends to cross Luzon Strait, penetrating the northeastern South China Sea where it forms energetic mesoscale structures. Luzon Strait is also a site where westward-propagating large-amplitude internal waves are generated. We describe observations of these waves acquired in the deep basin of the South China Sea during the winter of 2010-2011, with the goal of assessing the influence of mesoscale variability on their properties. Combining tidal current simulations with an internal wave generation and evolution model, we obtain time series of deviations between our observations and the model simulations. These deviations are analyzed in terms of mesoscale variability based on the data-assimilated HYbrid Coordinate Ocean Model (HYCOM) simulations. We find that simplified models of nonlinear internal wave response to changes in horizontal stratification gradients and vertical shear provide at best weak simulations of amplitude modulation. In contrast to these results, deviations of internal wave arrival time, occurring up to 2 h early during Kuroshio inflows, are quite well simulated when derived from integration of the first internal mode phase speed along two-dimensional ray-traced paths using HYCOM simulations of velocity and density fields together with bathymetry. Refraction of the internal waves by Kuroshio intrusions can lead to substantial distortion of the paths, sufficient to provide a potential explanation for the apparent suppression of waves during previous winter measurements. Our results suggest that the internal wave field can be a sensitive indicator of mesoscale variability in Luzon Strait and the northeastern South China Sea.

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

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


    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.

  2. Distribution of the East China Sea continental shelf basins and depths of magnetic sources

    Lin, Jing-yi; Sibuet, Jean-claude; Hsu, S.


    The acoustic basement map of the East China Sea, established by the Shanghai Offshore Petroleum Bureau with all available industry seismic data, shows the existence of a 30-km-wide, 10-km-deep basin, that we named the Ho Basin. The Ho Basin belongs to a series of elongated deep basins extending over 600 km east of the Taiwan-Sinzi Ridge and flanked to the East by a ridge named the Longwan Ridge in its northern part. This new system of basin and ridge was probably formed during middle Miocene,...

  3. Chinese assertiveness in the South China Sea and Southeast Asian responses

    Thayer, Carlyle A.


    This article reviews Chinese assertive behaviour towards the Philippines and Vietnam over South China Sea issues in 2011. The article compares and contrasts Chinese diplomatic behaviour in the period before and after the adoption by ASEAN member states and China of Guidelines for the Implementation the Declaration on Conduct of Parties in the South China Sea in July. In the first period China aggressively asserted its claims to sovereignty by interfering with commercial fishing and oil explor...

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

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


    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.

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

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


    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.

  6. Characteristics of the Geotectonics in South China and Their Constraints on Primary Diamond


    The Asian continent is one of the best places in the world to study continental dynamics. In this region the tectonic framework of the South China plate is related to the activity of the Pacific plate and Indian plate since the Mesozoic. In the South China plate, as the ophiolitic mélange of the middle Proterozoic in the Shaoxing-Yingtan-Tengxian-Beihai faulted zone was confirmed to be a subducting ocean, the evolution of the Yangtze block and Cathaysian block, which are located on both sides of the fault zone, becomes clearer and clearer. A primary diamond deposit, which was first found by Bao Chaomin and his colleagues in Longyou County of Zhejiang Province in 1998, originated from kimberlitoid pipes. The pipes are located in the Cretaceous basin beside this deep fault and the diamond-bearing pipe was formed deep within a favourable geological structure. Diamond there occurs as octahedral crystals without visual impurities. There are more than 100 similar pipes in the area, which have been poorly studied so far, so this area should have great prospects for diamond exploration.

  7. Position of South China in configuration of Neoproterozoic supercontinent

    ZHENG Yongfei


    @@ Configuration and evolution of Neoproterozoic supercontinent and the position of South China within it have been very important targets in earth sciences concerningmany forefront topics of general interest. In the commonreconstruction of the supercontinent Rodinia, South Chinawas located between Australia and Laurentia, and thus liesin the center of the supercontinent and southeast of Aus-tralia[1]. According to the new paleomagnetic and geo-chronological data for the ~800 Ma Xiaofeng dyke in Yichang as well as existing data, Li et al.[2] suggest that Rodinia would probably spread from the equator to the polar region at about 800 Ma, followed by a rapid ca. 90( rotation around an axis near Greenland that brought the entire supercontinent to a low-latitude position by ca. 750 Ma. As a result, South China is reinterpreted to be placed adjacent to both Australia and India, with a rapid shift of rotation from a position northeast of Australia and southeast of India at about 800 Ma (Fig. 1(a)) to a position northwest of Australia and northeast of India at about 750 Ma (Fig. 1(b)).

  8. Continental tectonics and uranium province of South China

    The pre-Sinian metamorphic basement of South China consists of 4 blocks, namely the Jiangnan, the Wuyi, the Yunkai-South Sea and the Mintai which belong to the same lithospheric plate from late Proterozoic on. The plate is enriched in U and Th revealed by Pb-isotopic study, which plays an role of essential prerequisite for the formation of U province. The amalgamation of the 4 blocks and their final attachment to Yangtze craton were resulted from Proterozoic, Caledonian, Indonesia and Yangshanian orogenic events, driven by Moho-rheologic stratification so that uraniferous black rock sequences and U-hosting granites and volcanics in age from late Sinian to Jurassic were produced in the fore lands of corresponding major orogenic uplifts. The change of tectonic regime from compression-relaxed to lateral tension happened after significant crust's thickening and large-scale emplacement of granitic batholiths during late Triassic and early Jurassic though local compression occurred from middle Eocene to Oligocene. Most of U deposits were just formed in association with this para-cratonization process from late Jurassic to Eogene. South China GGT shows that there exist the thinning and the break-up of undercrustal lithosphere at the Datian and the Quanzhou and funnel-shaped seg at middle Hunan. The former two are considered to be the product of up-migration of hot mantle plume and the latter to be the place of down-migration of cold mantle plume

  9. 一南海问题与中国南部地缘安全%The South China Sea Issue and Geo-security in the South China



    冷战后,南海的地缘位置与地缘环境决定了南海的价值。然而,南海问题的存在深刻地影响着南海地区的和平与发展,特别是对中国南部的地缘安全的制约作用日益明显。南海问题使中国不能有效地维护中国在南海的海域安全,不能有力地保证中国的战略航道安全,并且阻碍中国南部地缘环境的持续改善。中国应采取必要的对策消除南海问题对中国南部地缘安全的制约作用。%After the Cold War, the geopolitical location and geopolitical environment of the South China Sea determines the value of the South China Sea. However, the existence of the South China Sea dispute has a profound impact on peace and development in the South China Sea region, especially on China’s south geo-security. The South China Sea dispute makes China not effectively protect maritime security in the South China Sea, not effectually ensure the security of China’s strategic waterways and impede the geopolitical environment in southern China to improve continuously. China should take necessary measures to eliminate the negative effect that the South China Sea dispute has on China’s geo-security.

  10. Modeling Ecohydrological Processes and Spatial Patterns in the Upper Heihe Basin in China

    Bing Gao; Yue Qin; Yuhan Wang; Dawen Yang; Yuanrun Zheng


    The Heihe River is the second largest inland basin in China; runoff in the upper reach greatly affects the socio-economic development in the downstream area. The relationship between spatial vegetation patterns and catchment hydrological processes in the upper Heihe basin has remained unclear to date. In this study, a distributed ecohydrological model is developed to simulate the hydrological processes with vegetation dynamics in the upper Heihe basin. The model is validated by hydrological o...

  11. Assessment of Climate Change Effects on Water Resources in the Yellow River Basin, China

    Zhiyong Wu; Heng Xiao; Guihua Lu; Jinming Chen


    The water resources in the Yellow River basin (YRB) are vital to social and economic development in North and Northwest China. The basin has a marked continental monsoon climate and its water resources are especially vulnerable to climate change. Projected runoff in the basin for the period from 2001 to 2030 was simulated using the variable infiltration capacity (VIC) macroscale hydrology model. VIC was first calibrated using observations and then was driven by the precipitation and temperat...

  12. Navigating the Security Dilemma: China, Vietnam, and the South China Sea

    Jason J. Blazevic


    Full Text Available Competition and conflict in the South China Sea involves many nations due to its resources and vital sea lanes. However, it is China which increasingly serves as a common denominator of intensifying anxiety for its South China Sea maritime neighbours due to the aggressive scope of its claims to the sea and its islands. Among those states, Vietnam is most affected as it is first in the path of Chinese ambitions – ambitions which authorities fear would give China significant tactical military and economic advantage. For China, there are similar fears over threats to the sea lanes and sea bed resources. Leaders of both states also perceive their diplomatic and martial actions in the sea in historical terms as well. However, enforcement actions taken by either state may lead to a worsening security dilemma in which reactive security strategies could dangerously destabilise relations. This article discusses the motivations and strategies of both states as well as the consequences of such and applies realism, its tenets of defensive and offensive realism, and neoliberalism to examine their security concerns and perceptions. The article further proposes that the most valuable insights can be provided by defensive realism and neoliberalism, which together can encourage security, cooperation and conciliation in order to best promote the improvement of relations.

  13. Responses of thermal structure and vertical dynamic structure of South China Sea to Typhoon Chanchu

    陈宜展; 詹杰民; 罗莹莹; 唐灵; 韦永康


    The response of the South China Sea (SCS) to Typhoon Chanchu (2006) was examined using the MM5 and POM model. In the POM model, sea surface boundary conditions were forced by the simulation wind field from MM5, the velocity forcing was introduced in the eastern boundary and the computational schemes of heat fluxes at the surface were introduced. Comparison with the observation data shows that the simulated results are reliable. In the response process of the SCS to Typhoon Chanchu, the influence of the heat fluxes on thermal structure of the SCS was regionally different. Strong wind forcing would lead to upwelling phenomenon in the lateral boundary of deep water basin. Furthermore, the Ekman pumping theory was used to discuss subsurface upwelling and downwelling phenomenon in typhoon forced stage.

  14. Image of a subsurface current core in the southern South China Sea

    Q. S. Tang


    Full Text Available A legacy seismic transect acquired on 30 and 31 May 2009 in the southern South China Sea (SCS was reprocessed to reveal the thermohaline structure of the water column. In the study region, a mesoscale subsurface lens with extraordinary features was detected at 113.5° E, 11.5° N. It is centred at 450 m depth, occupies both the subsurface and intermediate water from 250 to 600 m, and has an intersection diameter of around 60 km. The simulated results from Hybrid Coordinate Ocean Model reveal an eddy-induced subsurface current running southwestward along the deep basin edge and suggest that the imaged lens is a snapshot of the subsurface current core rather than a subsurface eddy.

  15. Abiogenic hydrocarbons in commercial gases from the Songliao Basin, China

    WANG XianBin; WANG LianSheng; LIU ChunXue; YAN Hong; LI LiWu; ZHOU XiaoFeng; WANG YongLi; YANG Hui; WANG Guang; GUO ZhanQian; TUO JinCai; GUO HongYan; LI ZhenXi; ZHUO ShengGuang; JIANG HongLiang; ZENG LongWei; ZHANG MingJie


    This paper discusses the kinetic fractionation, composition and distribution characteristics of carbon and hydrogen isotopes for various alkane gases formed in different environments, by different mecha-nisms and from different sources in nature. It is demonstrated that the biodegradation or thermode-gradation of complex high-molecule sedimentary organic material can form microbial gas or ther-mogenic gas. The δ13C1 value ranges from -110‰ to -50‰ for microbial gases but from -51‰ to -35‰ (even heavier) for thermogenic gases. Controlled by the kinetic isotope fractionation, both microbial and thermogenic gases have δ13C and δD values characterized by normal distribution, i.e. δ13C1 δ13C2> δ13C3> δ13C4 and δDCH4<δDC2H6< δDC3H8< δDC4H10. The δ13C values and δD values are negatively correlated. Natural gases from 26 commercial gas wells distributed in the Xujiaweizi and Yingshan-Miaotaizi faulted de-pressions in the Songliao Basin, China, show δ13C1 values ranging from -30.5‰. to -16.7‰, with a very narrow δD range between -203‰--196‰. These gases are characterized by a reverse distribution of δ13C values but a normal distribution of δD values, and a negative correlation between their δ13C and δD values, indicating an abiological origin. The present study has revealed that abiogenic hydrocar-bons not only exist in nature but also can make significant contribution to commercial gas reserviors. It is estimated that the reserve volume of alkane gases with abiogenic characteristics in these 26 gas wells in the Songliao Basin is over 500×108 m3, The prospecting practice in the Songliao Basin has demonstrated that abiogenic alkane gases are of a promising resource, and it provides an example for the investigation of and search for abiogenic commercial natural gases worldwide.

  16. Abiogenic hydrocarbons in commercial gases from the Songliao Basin, China


    This paper discusses the kinetic fractionation, composition and distribution characteristics of carbon and hydrogen isotopes for various alkane gases formed in different environments, by different mecha- nisms and from different sources in nature. It is demonstrated that the biodegradation or thermode- gradation of complex high-molecule sedimentary organic material can form microbial gas or thermogenic gas. The δ 13C1 value ranges from -110‰ to -50‰ for microbial gases but from -50‰ to -35‰ (even heavier) for thermogenic gases. Controlled by the kinetic isotope fractionation, both microbial and thermogenic gases have δ 13C and δ D values characterized by normal distribution, i.e. δ 13C1< δ 13C2< δ 13C3< δ 13C4 and δ DCH4< δ DC2H6< δ DC3H8<δ DC4H10, and by a positive correlation between the δ 13C and δ D values. Simple carbonbearing molecules (CH4, CO and CO2) can form abiogenic alkane gases via polymerization in the abiological chemical process in nature, with δ 13C1 heavier than -30‰. Moreover, controlled by the kinetic isotope fractionation, abiogenic alkane gases are characterized by a reverse distribution of δ 13C values and a normal trend of δ D values, namely δ 13C1> δ 13C2> δ 13C3> δ 13C4 and δ DCH4<δ DC2H6< δ DC3H8< δ DC4H10. The δ 13C values and δ D values are negatively correlated. Natural gases from 26 commercial gas wells distributed in the Xujiaweizi and Yingshan-Miaotaizi faulted depressions in the Songliao Basin, China, show δ13C1 values ranging from -30.5‰ to -16.7‰ with a very narrow δ D range between -203‰―-196‰. These gases are characterized by a reverse distribution of δ 13C values but a normal distribution of δ D values, and a negative correlation between their δ 13C and δ D values, indicating an abiological origin. The present study has revealed that abiogenic hydrocarbons not only exist in nature but also can make significant contribution to commercial gas reserviors. It is estimated that

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

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


    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.

  18. Sample Return Mission to the South Pole Aitken Basin

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


    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

  19. Management pattern of ecological public welfare forests in South China

    Chong LOU; Anxing LIU; Guomin ZHU


    The characteristics and actualities of ecologi-cal public welfare forests in South China are studied in this paper, including common and special management patterns. The restoration and reconstruction pattern of subtropical evergreen broad-leaved forests, zonal vegeta-tion in the key eco-zone, and the transformation pattern of coniferous and broad-leaved mixed forests in the general eco-zone with multi-forms are discussed in detail. The authors also point out, based on ecological transformation and utilization, that ecological public welfare forests should be oriented to multiple benefit utilization to maintain sustainable management.

  20. Octoradiate Spiral Organisms in the Ediacaran of South China

    TANG Feng; YIN Chongyu; Stefan BENGTSON; LIU Pengju; WANG Ziqiang; GAO Linzhi


    Shales of the Ediacaran Doushantuo Formation of South China contain a new disc-shaped macrofossil, Eoandromeda octobrachiata, characterized by eight spiral arms that were probably housed within an outer membrane. Although the presence of eight radiating structures entails a resemblance to cnidarian octocorais as well as to ctenophores, direct homologies with these extant groups are unlikely. Instead we bring attention to the helicospiral morphology of newly reported embryos from the Doushantuo Formation, suggesting that the long-sought adults of the Ediacaran embryonic metazoans have fmaily been found.



    There exists a warm pool in the South China Sea (SCS). The temporal and spatial distribution and evolution of SCS warm pool is investigated using water temperatures at a depth of 20 m in the sea. The formation of the warm pool is discussed by combining water temperatures with geostrophic currents and simulated oceanic circulation. It is found that there are significant seasonal and interannual changes in the warm pool and in association with the general circulation of the atmosphere. The development of SCS warm pool is also closely related to the gyre activities in the sea and imported warm water from Indian Ocean (Java Sea) besides radiative warming.

  2. Satellite based wind resource assessment over the South China Sea

    Badger, Merete; Astrup, Poul; Hasager, Charlotte Bay;


    modeling to develop procedures and best practices for satellite based wind resource assessment offshore. All existing satellite images from the Envisat Advanced SAR sensor by the European Space Agency (2002-12) have been collected over a domain in the South China Sea. Wind speed is first retrieved from...... description in order to calculate the mean wind climate at different levels up to 100 m. Time series from coarser-resolution satellite wind products i.e. the Special Sensor Microwave Imager (SSM/I) data are used to calculate the long-term temporal variability of the wind climate. This can be used...

  3. Origin and Distribution of Hydrogen Sulfide in Oil-Bearing Basins, China

    ZHU Guangyou; ZHANG Shuichang; LIANG Yingbo


    The concentration of hydrogen sulfide gas (H_2S) varies greatly in the oil-bearing basins of China, from zero to 90%. At present, oil and gas reservoirs with high H_2S concentration have been discovered in three basins, viz. the Bohai Bay Basin, Sichuan Basin and the Tarim Basin, whereas natural gas with low H_2S concentration has been found in the Ordos Basin, the Songiiao Basin and the Junggar Basin. Studies suggest that in China H_2S origin types are very complex. In the carbonate reservoir of the Sichuan Basin, the Ordos Basin and the Tarim Basin, as well as the carbonate-dominated reservoir in the Luojia area of the Jiyang depression in the Bohai Bay Basin, Wumaying areas of the Huanghua depression, and Zhaolanzhuang areas of the Jizhong depression, the H_2S is of Thermochemical Sulfate Reduction (TSR) origin. The H_2S is of Bacterial Sulphate Reduction (BSR) origin deduced from the waterflooding operation in the Changheng Oiifieid (placanticline oil fields) in the Songliao Basin. H_2S originates from thermal decomposition of sulfur-bearing crude oil in the heavy oil area in the Junggar Basin and in the Liaohe heavy oil steam pilot area in the western depression of the Bohai Bay Basin. The origin types are most complex, including TSR and thermal decomposition of sulfcompounds among other combinations of causes. Various methods have been tried to identify the origin mechanism and to predict the distribution of H_2S. The origin identification methods for H_2S mainly comprise sulfur and carbon isotopes, reservoir petrology, particular biomarkers, and petroleum geology integrated technologies; using a combination of these applications can allow the accurate identification of the origins of H_2S. The prediction technologies for primary and secondary origin of H_2S have been set up separately.

  4. Origin of Natural Gas in Kekeya Field, Tarim Basin, China

    Hou Dujie; Xiao Zhongyao; Tang Youjun; Zhu Junzhang; Li Xianqing


    This paper is mainly concentrated on the geochemical characteristics and origin of gas of Kekeya field in the Tarim basin, NW China. This study shows that Permian mudstone is the main source rock of oil and gas. Based on the carbon isotopes of C1-C4, the carbon isotope of gas in Kekeya field is a little heavier than that in the typical marine-derived gas. The relationship between carbon isotopes of methane and ethane is coincident with Faber equation of gas derived from organic matter Ⅰ/Ⅱ. The majority of gas maturity is estimated, based on the formula, at 1.8 %-2.2 % besides K2 and K18 wells. In addition, the gas derived from 0.9 %-1.2 % Ro source rocks may also be mixture. 40Ar/36Ar and 3He/4He ratios from the gas samples also support the mixing process. Moreover, the gas in this region is mainly generated from more mature source rocks although the low mature gas exists.

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

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


    Variability in precipitation is critical for the management of water resources. In this study, the researchentropy base concept was applied to investigate spatial and temporal variability of the precipitationduring 1964–2013 in the Songhua River basin of Heilongjiang Province in China. Sample entropy wasapplied on precipitation data on a monthly, seasonally, annually, decade scale and the number of rainydays for each selected station. Intensity entropy and apportionment entropy were used to calculate thevariability 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 sampledisorder 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) contributedsignificantly higher than those of other months. Overall, the contribution of the winter season wasconsiderably high with a standard deviation of 0.10. The precipitation variability on decade basis wasobserved to increase from decade 1964–1973 and 1994–2003 with a mean value of decadal apportionmentdisorder index 0.023 and 0.053, respectively. In addition, the Mann–Kendall test value (1.90) showed asignificant positive trend only at the Shangzhi station.

  6. Application of isotope techniques to groundwater investigation in the Erdos Basin, China

    Full text: The Erdos Basin is located in the eastern part of Northwestern China and extends over parts of 5 provinces: Shaanxi, Gansu, Ningxia, Inner Mongolia and Shanxi. The basin is surrounded by the Yellow River to the west, north and east and the Weihe River, the largest tributary of the Yellow River, flows through the southern basin from west to east. The Erdos Basin covers an area of about 400 000 km2 and is a plateau depression basin caused by structural uplift. The early Cretaceous sediments which form the artesian basin consist of six primary hydrostratigraphic units with a total thickness of 1000m. Generally, Ordovcian carbonate rock formations form karstic aquifers that flank the east, south and west of the basin distributed in a U-shape forming the peripheral mountains and hills with an area covering about 100 000 km2. The groundwater resources of the basin are strategically important and this ongoing IAEA TC-project (CPR/08/12) was undertaken in 2001-2002, with the major tasks being to evaluate the availability of groundwater resources, especially the recharge process and recharge rate, to understand the inter-relationship between groundwater system and surface water and between different groundwater aquifers, to determine the age of groundwater, and explore the possibility of utilizing deep groundwater. The objective is to improve groundwater investigation and management in arid and semi-arid regions in China through integrating isotope techniques. This paper reports upon work in progress through collection, collation and analysis of climatic, geological, hydrogeological hydrochemical data, water sampling and laboratory analysis, isotope technique training. A double-packer sampling system is being used to collect discreet-level water samples from target hydro-stratigraphic units via uncased boreholes up to 1000m in depth. Four rainfall stations for rain collection have been set up in the Erdos Basin and 50 water samples for D, 18O, T were collected

  7. A new net primary production estimating model using NOAA-AVHRR applied to the Haihe Basin, China

    Xu, Xingang; Wu, Bingfang; Li, Qiangzi; Meng, Jihua; Zhang, Fengli


    Terrestrial net primary production (NPP), as an important component of carbon cycle on land, not only indicates directly the production level of vegetation community on land, but also shows the status of terrestrial ecosystem. What's more, NPP is also a determinant of carbon sinks on land and a key regulator of ecological processes, including interactions among tropic levels. In the study, three existing models are combined with each other to assess net primary production in Haihe Basin, China. The photosynthetically active radiation (PAR) model of Monteith is used for the calculation of absorbed photosynthetically active radiation (APAR), the light utilization efficiency model of Potter et al. is used for determining the light utilization efficiency, and the surface energy balance system (SEBS) of Su is used into Potter's model to describe water stress in land wetness conditions. To assess NPP, We use NOAA-AVHRR data from November 2003 to September 2004 and the corresponding daily data of temperature and hours of sunshine obtained from meteorological stations in Haihe Basin, China. After atmospheric, geometrical and radiant corrections, every ten days NOAA data are processed to become an image of NDVI by means of the maximal value composition method (MVC) in order to eliminate some noises. Using these data, we compute NPP in spring season and spring season of 2004 in Haihe Basin, China. The result shows, in Haihe Basin, NPP for spring season is averaged to 336.10gC•m -2, and 709.16 gC•m -2 for autumn season. In spatial distribution, NPP is greater in both ends than in middle for spring season, and decrease increasingly from north to south for autumn season. Future work should rely on the integration of high and low resolution images to assess net primary production, which will probably have more accurately estimation.

  8. Relating petroleum system and play development to basin evolution: West African South Atlantic basins

    Beglinger, S.E.; Doust, H.; Cloetingh, S.A.P.L.


    Sedimentary basins can be classified according to their structural genesis and evolutionary history and the latter can be linked to petroleumsystem and playdevelopment. We propose an approach in which we use the established concepts in a new way: breaking basins down into their natural basin cycle d

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

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


    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.

  10. 137Cs inventory in semi-isolated basins of the western South Pacific

    Yamada, M.; Wang, Z.


    The main introduction routes of 137Cs into the Pacific Ocean are worldwide global fallout from atmospheric nuclear weapons testing and close-in fallout from U. S. tests conducted on the Bikini and Enewetak Atolls. The objectives of this study are to measure the 137Cs activities in water columns of the western South Pacific Ocean and to discuss the processes controlling the 137Cs inventory. The 137Cs activities were determined for seawater samples from the East Caroline, Coral Sea, New Hebrides, South Fiji and Tasman Sea Basins of the western South Pacific Ocean. The 137Cs activities in surface waters ranged from 1.7 Bq m- 3 in the Tasman Sea Basin to 2.3 Bq m-3 in the East Caroline Basin. The latitudinal 137Cs distributions in surface waters showed the opposite trend to the expected deposition density from global fallout. The distribution profiles of 137Cs activity at these six western South Pacific Ocean stations did not differ from each other significantly. The total 137Cs inventories in the western South Pacific Ocean ranged from 850 Bq m-2 in the Coral Sea Basin to 1270 Bq m-2 in the South Fiji Basin. Higher 137Cs inventories were observed at middle latitude stations in the subtropical gyre than at low latitude stations. The 137Cs inventories were 1.9 - 4.5 times higher than that of the expected deposition density of atmospheric global fallout at the same latitude. The possible sources of excess 137Cs inventories in the western South Pacific Ocean might be attributable to both the inter-hemisphere dispersion of the atmospheric nuclear weapons testing 137Cs from the northern stratosphere to the southern one and its subsequent deposition, and water- bearing transport of 137Cs from the North Pacific Ocean to the South Pacific.