| 云南永善肖滩早寒武世早期碳氧同位素记录 |
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| 引用本文： | 周传明,张俊明.云南永善肖滩早寒武世早期碳氧同位素记录[J].地质科学,1997,32(2):201-211. |
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| 作者姓名： | 周传明 张俊明 |
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| 作者单位： | 中国科学院南京地质古生物研究所, 南京 210008 |
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| 摘 要： | 本文对采自云南永善肖滩剖面下寒武统100余件碳酸盐岩样品的碳氧同位素进行了分析研究。在从灯影组白岩哨段上部至筇竹寺组玉案山段碳酸盐岩碳同位素变化曲线上,梅树村组小歪头山段底部δ13C值表现出显着负飘移。早寒武世梅树村期,碳同位素值缓慢增大,至大海段达到最大值。在筇竹寺组石岩头段底部,δ13C值表现为明显负飘移。在玉案山段,碳同位素又开始一个新的正飘移旋回。根据同位素资料,肖滩剖面下寒武统梅树村组小歪头山段至大海段地层相当于前托莫特阶地层,筇竹寺组石岩头段与托莫特阶地层对应,玉案山段与呵特达班阶下部地层对比。小歪头山段底部标志着寒武纪沉积已经开始。
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| 关 键 词： | 碳氧同位素 早寒武世早期 地层对比 云南永善肖滩 |
| 收稿时间： | 1995-12-21 |
| 修稿时间： | 1995-12-21; |
CABBON AND OXYGEN ISOTOPIC RECORD OF THE EARLY CAMBR IAN FR OM THE XIAOTAN SECTION , YUNNAN , SOUTH CHINA |
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| Zhou Chuamdng Zhaog Junming Li Guoxiang Yu Ziye.CABBON AND OXYGEN ISOTOPIC RECORD OF THE EARLY CAMBR IAN FR OM THE XIAOTAN SECTION , YUNNAN , SOUTH CHINA[J].Chinese Journal of Geology,1997,32(2):201-211. |
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| Authors: | Zhou Chuamdng Zhaog Junming Li Guoxiang Yu Ziye |
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| Institution: | Nanjing Institute of Geology, and palaeotology, Chinese Academy of Sciences, Nanjing 210008 |
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| Abstract: | The carbonate rock plesanalyzed herein were taken from the Xiaotan.section on the bank of the Jinshajiaag River,northeastern Yunaan,Soutb China.The early Cambdan cropping out at this section disonformably overlies the dolonuita of the Baiyanshao Member of the Precambrian Dengying Formadon.lts stratigraphical succession ondsb of the Xiaowaitoushan Member,the Zhongyicun Member and the Dember Member.of tbe Mdshucun Formation,the Shiyantou Member and the Yu’anshan Member of the Qiongzhusi Fonmadon.Inmajor features the profile shows and 8‰,sharp drop in δ13C through the boundary of the Baiyanshao Member and the Xiaowaitousban Member,followed by a slow rise in.values from about -l2‰,to nearlyz +6‰,throughout the early Cambrian Meishucun Formation,The δ13C valuse show a pronounced decrease to about -5.4‰ through the boundary between the Dahai and Shiyantou Members,and then are.characterized by generally negative valus raning betwem -11.32‰ and -0.06‰in the overlying Qiongzhusi Formation,Obviously,this curve presents four four carboaisotope cycles includtiagthe δ13C rise throughthe Xiaowaitoushan Membeand.lower andrmtddle parts of the Zhongyicun member,the δ13C proaounod positive excursion theough the upper Zhongyicun Member and the Dahai Member,the δ13C negadve excunion through the Shiyantou member and δ13C rising trend through the Yu,anshan Member.The δ13C pattern in the Meishucun Formation is believed to be prnadly an origbal oceanic signal,while the δ13C values in the Qiongzhusi Formationa were pardally afected by diagenesis.This isotopic patternmay be conelaed with that of the adjacent Meishucun δ13C profile and many others around the we prder to equate the lower δ13C rise with in the Meishucun Formation from the Xiaotan section to the pre-Yomrmotian rise,and the upper reladvely deplekd values of δ13C within the Shiyantou Member to that of Tormmotian and relatively rising valuse of δ13C within the overlying the overlying yu’anshan Member to the lower Atdbanian δ13C profile in Siberia.The coneladoas also suggest that the Pnxambdan/Cambrian bound.exist betwam the Xiaowaitoushan and Bdyaoshao Memtbers. |
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| Keywords: | Carbon -and Oxygea-isotopes Early Cambrian Stndgnphic correlation Xiaotan section |
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