危凯, 刘安, 李海, 李继涛. 鄂西长阳ZK04钻孔埃迪卡拉系陡山沱组C同位素组成特征及其地层对比意义[J]. 地质通报, 2017, 36(5): 800-810.
    引用本文: 危凯, 刘安, 李海, 李继涛. 鄂西长阳ZK04钻孔埃迪卡拉系陡山沱组C同位素组成特征及其地层对比意义[J]. 地质通报, 2017, 36(5): 800-810.
    WEI Kai, LIU An, LI Hai, LI Jitao. Carbon isotopic composition of the Ediacaran Doushantuo Formation from ZK04 drill hole in Changyang of west Hubei Province and its significance for stratigraphic correlation[J]. Geological Bulletin of China, 2017, 36(5): 800-810.
    Citation: WEI Kai, LIU An, LI Hai, LI Jitao. Carbon isotopic composition of the Ediacaran Doushantuo Formation from ZK04 drill hole in Changyang of west Hubei Province and its significance for stratigraphic correlation[J]. Geological Bulletin of China, 2017, 36(5): 800-810.

    鄂西长阳ZK04钻孔埃迪卡拉系陡山沱组C同位素组成特征及其地层对比意义

    Carbon isotopic composition of the Ediacaran Doushantuo Formation from ZK04 drill hole in Changyang of west Hubei Province and its significance for stratigraphic correlation

    • 摘要: 对湖北长阳两河口ZK04钻孔岩心进行了详细的碳酸盐岩C、O同位素分析,识别了埃迪卡拉系陡山沱组4次明显的δ13C负偏离,分别位于陡山沱组一段、二段中上部、二段上部和三段上部至四段。其中第1、2和4次δ13C负偏离与黄陵背斜周缘的剖面能够很好地对应,具有重要的区域和全球地层对比意义。在第1次δ13C正偏离区域内并未发现明显的δ13C负偏,分析认为WANCE事件可能仅代表了峡东部分地区一次短暂的δ13C降低事件。第3次δ13C负偏离表现最显著,然而在秭归泗溪和青林口以外的其他地区未见报道,可能是由于水体较浅的区域发生了地层缺失,未能保存此次δ13C负偏离。长阳ZK04孔陡山沱组顶部的第4次δ13C负偏离表现较弱,考虑到陡山沱组四段的黑色页岩较少发育,推测长阳两河口地区在陡山沱晚期处于浅水台地或台地边缘。DOUNCE可能是地史时期最大的一次全球性C同位素负偏离事件,其与大型具刺疑源类化石群和埃迪卡拉生物群的发展演化有紧密的联系,对于全球埃迪卡拉纪统级地层对比具有重要的意义。

       

      Abstract: The authors analyzed carbon and oxygen isotopes of Ediacaran Doushantuo Formation from ZK04 drilling core, Lianghek-ou of Changyang, Hubei Province.The carbon isotope trends show 4 negative excursions which exist in Member 1, the medium-up-per part of Member 2, the upper part of Member 2 and the Upper Member 3 to Member 4 of Doushantuo Formation, respectively.The first, second and the fouth negative δ13C excursions can be well correlated to those from other sections of the Yangtze Gorges, and are of great significance for the regional and global Ediacaran stratigraphic correlation.Since the notable negative excursion in the first positive δ13C excursion is not observed in the ZK04 drilling core, the authors hold that the WANCE event could merely repre-sent a short-term δ13C decrease in partial area of Yangtze Gorges.The third, which was the strongest negative δ13C excursion, has not been reported in other regions, except for Sixi and Qinglinkou of Zigui County.A probable explanation is that there occurred stratigraphic gap in the relatively shallow water.The relatively weak negative δ13C excursion at the top of Doushantuo Formation, as-sociated with the less developed black shales, suggests that the Lianghekou area of Changyang might have been located at the shallowwater platform or platform margin during the late Doushantuo period.DOUNCE was probably the most negative event of δ13C in the geological time, and it is believed to have been closely linked to the evolution of the large acanthomorphic acritarchs and the Edia-caran biota, accordingly it may be of great importance for global Eidacaran stratigraphic subdivision.

       

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