| Organic Carbon Isotope Geochemistry of the Neoproterozoic Doushantuo Formation, South China |
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| 作者姓名： | GUO Qingjun LIU Congqiang Harald STRAUSS Tatiana GOLDBERG ZHU Maoyan PI Daohui WANG Jian |
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| 作者单位： | [1]State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550002, China [2]Geologisch-Palaontologisches Institut, Universitat Miinster, Corrensstrasse 24, 48149 Miinster, Germany [3]Sc |
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| 基金项目： | 国家自然科学基金;国家自然科学基金 |
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| 摘 要： | The Neoproterozoic Doushantuo Formation on the Yangtze Platform, South China, documents a sedimentary succession with different sedimentary facies from carbonate platform to slope and to deep sea basin, and hosts one of the world-class phosphorite deposits. In these strata, exquisitely preserved fossils have been discovered： the Weng＇an biota. This study presents carbon isotope geochemistry which is associated paired carbonate and organic matter from the Weng＇an section of a carbonate platform （shelf of the Yangtze Platform, Guizhou Province） from the Songtao section and Nanming section of a transition belt （slope of the Yangtze Platform, Guizhou Province） and from the Yanwutan section （basin area of the Yangtze Platform, Hunan Province）. Environmental variations and bio-events on the Yangtze Platform during the Late Neoproterozoic and their causal relationship are discussed. Negative carbon isotope values for carbonate and organic carbon （mean δ^13Corg = -35.0‰） from the uppermost Nantuo Formation are followed by an overall increase in δ^13C up-section. Carbon isotope values vary between -9.9‰ and 3.6‰ for carbonate and between -35.6‰ and -21.5‰ for organic carbon, respectively. Heavier δ^13Ccarb values suggest an increase in organic carbon burial, possibly related to increasing productivity （such as the Weng＇an biota）. The δ^13C values of the sediments from the Doushantuo Formation decreased from the platform via the slope to basin, reflecting a reduced environment with minor dissolved inorganic carbon possibly due to a lower primary productivity. It is deduced that the classical upwelling process, the stratification structure and the hydrothermal eruption are principally important mechanisms to interpret the carbon isotopic compositions of the sediments from the Doushantuo Formation.
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| 关 键 词： | 有机碳 同位素 地球化学 地台 |
| 收稿时间： | 8/2/2005 12:00:00 AM |
| 修稿时间： | 2005-11-18 |
Organic Carbon Isotope Geochemistry of the Neoproterozoic Doushantuo Formation, South China |
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| Authors: | GUO Qingjun LIU Congqiang Harald STRAUSS Tatiana GOLDBERG ZHU Maoyan PI Daohui WANG Jian |
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| Abstract: | Abstract: The Neoproterozoic Doushantuo Formation on the Yangtze Platform, South China, documents a sedimentary succession with different sedimentary facies from carbonate platform to slope and to deep sea basin, and hosts one of the world‐class phosphorite deposits. In these strata, exquisitely preserved fossils have been discovered: the Weng'an biota. This study presents carbon isotope geochemistry which is associated paired carbonate and organic matter from the Weng'an section of a carbonate platform (shelf of the Yangtze Platform, Guizhou Province) from the Songtao section and Nanming section of a transition belt (slope of the Yangtze Platform, Guizhou Province) and from the Yanwutan section (basin area of the Yangtze Platform, Hunan Province). Environmental variations and bio‐events on the Yangtze Platform during the Late Neoproterozoic and their causal relationship are discussed. Negative carbon isotope values for carbonate and organic carbon (mean δ13Corg = ?35.0%) from the uppermost Nantuo Formation are followed by an overall increase in δ13C up‐section. Carbon isotope values vary between ?9.9% and 3.6% for carbonate and between ?35.6% and ?21.5% for organic carbon, respectively. Heavier δ13Ccarb values suggest an increase in organic carbon burial, possibly related to increasing productivity (such as the Weng'an biota). The δ13C values of the sediments from the Doushantuo Formation decreased from the platform via the slope to basin, reflecting a reduced environment with minor dissolved inorganic carbon possibly due to a lower primary productivity. It is deduced that the classical upwelling process, the stratification structure and the hydrothermal eruption are principally important mechanisms to interpret the carbon isotopic compositions of the sediments from the Doushantuo Formation. |
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| Keywords: | Late Neoproterozoic Doushantuo Formation organic carbon isotopic composition the Yangtze Platform |
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