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Zhang H.,Chinese Academy of science | Zhang H.,Norwegian Institute for Water Research | Feng X.,Chinese Academy of science | Jiang C.,Wuhan University | And 7 more authors.
Environmental Pollution | Year: 2014

Rice is an important source of Se for billions of people throughout the world. The Wanshan area can be categorized as a seleniferous region due to its high soil Se content, but the Se content in the rice in Wanshan is much lower than that from typical seleniferous regions with an equivalent soil Se level. To investigate why the Se bioaccumulation in Wanshan is low, we measured the soil Se speciation using a sequential partial dissolution technique. The results demonstrated that the bioavailable species only accounted for a small proportion of the total Se in the soils from Wanshan, a much lower quantity than that found in the seleniferous regions. The potential mechanisms may be associated with the existence of Hg contamination, which is likely related to the formation of an inert Hg-Se insoluble precipitate in soils in Wanshan. © 2014 Elsevier Ltd. All rights reserved. Source

Yang J.,Wuhan University | Cawood P.A.,University of St. Andrews | Cawood P.A.,University of Western Australia | Du Y.,Wuhan University | And 3 more authors.
Sedimentary Geology | Year: 2012

Whole-rock geochemistry and zircon trace element and U-Pb age data for Late Permian-early Middle Triassic volcanogenic sedimentary rocks in SW China show a change from Large Igneous Province to subduction-related sources immediately before the Permian-Triassic boundary. Zircons from Late Permian samples give identical within-error ages to the adjoining Emeishan Large Igneous Province (LIP). The bulk-rock geochemistry of these Late Permian units shows no depletion in high field strength elements and is similar to the high-titanium basalts of the Emeishan. Six samples of latest Permian-earliest Triassic tuff and two earliest Middle Triassic tuffs samples yield U-Pb zircon ages at of ~. 252. Ma and ~. 247. Ma, respectively. These tuffs and interstratified volcanogenic sedimentary rocks show significant depletion in high field strength elements, akin to magmatic arc-related rocks. Zircons from the tuffs have Nb/Hf, Th/Nb and Hf/Th ratios similar to those from arc/orogenic-related settings and distinct from the zircons from the Late Permian samples which display within-plate/anorogenic characteristics. Our data demonstrate that there is a compositional change of the volcanogenic sediments across the Permian-Triassic boundary in South China. © 2012 Elsevier B.V. Source

Tao P.,Hubei University | Tao P.,Guizhou Academy of Geological Survey | Xu Q.-S.,Guizhou University | Liu K.,Guizhou University
Geological Bulletin of China | Year: 2010

According to the technical requirements of national mineral resources potential evaluation, this article, taking the bauxite resource prediction in Guizhou Province as the example, this paper focuses on the prediction units division of the geological-unit and grid-unit method, the selection of essential factors for prediction, assigning value to essential factors as well as discussion of the influence of geological mapping scale, the characteristics of mineral deposit, geophysical and geochemical remote sensing information on mineral resource prediction, with the introduction of mineralizing types and its characteristics, prediction methods of sedimentary bauxite resource in China. This grid-unit method has considered the most essential prediction factors, and its accuracy has reaches to each single orebody or deposit. Source

Lan Z.,CAS Institute of Geology and Geophysics | Li X.,CAS Institute of Geology and Geophysics | Zhu M.,CAS Nanjing Institute of Geology and Palaeontology | Chen Z.-Q.,Wuhan University | And 5 more authors.
Precambrian Research | Year: 2014

The Neoproterozoic glaciations represent a remarkable milestone in Earth evolution due to their major influence on atmosphere, biosphere, and hydrosphere. The early Cryogenian, 'Sturtian' glaciations, evidence for which has been recorded worldwide, may have lasted for about 50 million years, but the precise timing and synchroneity of these glaciations have been disputed. Jiangkou glacigenic strata in South China can be attributed to the Sturtian glacial episode as they share sedimentological, stratigraphic and lithological similarities with Sturtian strata in South Australia. As such, dating the onset of the Jiangkou glaciation would contribute to testing the synchroneity of the worldwide Sturtian glaciation. In this paper, we demonstrate by means of SIMS U-Pb zircon dating that the Jiangkou glaciation in South China was initiated at 715.9. ±. 2.8. Ma. The new age is, within uncertainty, synchronous with dates obtained from the lower parts of glacigenic successions in Laurentia and Oman, thereby indicating thereby indicating a synchroneity and global extent to the Sturtian glaciation. The synchronous occurrence of the Sturtian glaciation in mid- to low-latitude regions implies rapid ice sheet advancement in response to ice-albedo feedback, as supported by numerical climatic modeling. © 2014 Elsevier B.V. Source

Qiao W.,Guizhou Academy of Geological Survey | Wang J.,CAS Institute of Geology and Geophysics | Chen W.,Guizhou Academy of Geological Survey
Scientia Geologica Sinica | Year: 2013

The Nanhuan is a key period of one of the most important intervals in Earth's history marked by dramatic climatic, environmental changes. Here we present the geochemical variations through the Nanhuan succession from Jiaokai on the Yangtze block, south China, in order to investigate changes of palaeoenvironment and palaeoclimate. Relatively, low values of chemical index of alteration(CIA), Ti/Al of Tiesiao Formation, suggest a cold, dry climate and thus low source supply and glaciation period. In contrast, high values of CIA, Ti/Al of Longli and Datangpo formations, indicate a warm, humid climate and thus low source supply and interglaciation period. Variation in values of CIA, Ti/Al of Nantuo Formation indicate a warming and cooling cycle and thus a interglaciation to glaciation cycle The relative temporal coincidence of low magnitude of positive Eu anomalies and transition from glaciation to interlgaciation suggests that greenhouse gases(CO2, CH4) from hydrothermal venting could be one of the main controls on the demise of glaciation. Source

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