| 海进体系域碳氧同位素地球化学响应——以黔西南地区三叠系为例 |
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| 引用本文： | 李荣西,;魏家庸,;肖家飞,;王兴理,;Lehrmann DJ.海进体系域碳氧同位素地球化学响应——以黔西南地区三叠系为例[J].西安地质学院学报,2007(1):1-5. |
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| 作者姓名： | 李荣西 ;魏家庸 ;肖家飞 ;王兴理 ;Lehrmann DJ |
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| 作者单位： | [1]长安大学地球科学与国土资源学院,陕西西安710054; [2]中国科学院地球化学研究所,贵州贵阳550002; [3]威斯康星大学奥什科什分校地质系,奥什科什,WI 54901,美国 |
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| 基金项目： | 国家自然科学基金项目（40173005）参加野外工作的有美国堪萨斯大学Paul Enos教授、中国科学院地球化学研究所杨卫东和郭庆军研究员等,谨此致谢. |
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| 摘 要： | 层序地层研究表明，位于扬子地块西南缘的黔西南地区在中三叠世末期（相当于Ladinian-Carnian期）出现了一次与全球同步的大规模海侵，形成了一个向上变深的碳酸盐岩台地淹没沉积层序。垄头组顶部和竹竿坡组分别是海进体系域（TST）的下、上部分。碳、氧同位素研究表明，垄头组顶部自下而上δ（^18O）持续增大，而δ（^13 C）先逐渐增大，后在顶部界面附近快速下降，反映了垄头组顶部在暴露环境下氧化作用的结果。竹竿坡组δ（^13 C）自下而上逐渐增大，δ（^13 C）总体呈现逐渐减小趋势，反映了海平面变化特征。研究认为，海进体系域的δ（^13 C）和δ（^18 O）演化不但反映了海平面和沉积环境变化，同时对密集段（CS）、层序界面和古暴露面等也有很好的识别作用，在层序地层研究中具有重要的意义。
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| 关 键 词： | 碳同位素 氧同位素 层序地层 三叠系 黔西南 |
Response of Carbon and Oxygen Isotopic Geochemistry to Transgressive Systems Tract： An Example From Triassic Stratigraphy in Southwestern Guizhou Province |
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| Institution: | LI Rong-xi , WEI Jia-yong , XIAO Jia-fei , WANG Xing-li , Lehrmann D J (1. School of Earth Sciences and Resources Management, Chang＇an University, Xi＇ an 710054, Shaanxi, China; 2. Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, Guizhou , China ; 3. Department of Geology, University of Wisconsin-Oshkosh, Oshkosh WI 54901, USA) |
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| Abstract: | There was a large regression of sea-level in the Later Middle Triassic in Yangtze Block （the famous Ladinia large regression in China）. But a large transgression of sea-level took place synchronously with the global sea-level changes in the southwest corner of Yangtze Block at the southwest region of Guizhou Province during the same period. The Yangtze carbonate platform was drawn and a transgressive sequence was formed during that time. The transgressive systems tract （TST） comprised the top section of Longtou Formation and Zhuganpo Formation. Studies to the variations of δ（^13 C） and δ（^18 O） of the TST show that the δ（^18 O） of Longtou Formation increased upward while the δ（^13 C）increased in lower part but decreased abruptly at the top, which reflects the diagenetic alteration to the top of Longtou Formation due to exposure under continental weathering environment. The δ（^13 C） increasing significantly while the δ（^18 O） decreasing gradually upward within Zhuganpo Formation indicates a major sea-level rise. The δ（^13 C） and δ（^18 O） values of TST reflect sea level fluctuation and paleoenvironment changes. The condensed section （CS） and the strata boundary can be reflected with carbon and oxygen isotopic composition. |
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| Keywords: | Carbon isotope Oxygen isotope transgressive systems tract （TST） Triassic Period Southwestarea of Guizhou Province |
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