左景勋,彭善池,祁玉平,林焕令,朱学剑,杨显峰

• 1:河南省地质调查院
• 2:中国科学院南京地质古生物研究所
• 3:中国科学院南京地质古生物研究所
• 4:中国科学院南京地质古生物研究所

摘要(Abstract)：

湘西罗依溪剖面包含有被国际地层委员会寒武系分会表决通过的、确定全球寒武系第三统第七阶底界的球接子三叶虫Lejopygelaevigata的首现点位,是全球寒武系第三统第七阶GSSP的候选剖面。野外按0.25—0.5m的样品间距,对该点位附近的碳酸盐岩采取了264件碳、氧同位素样品,分析结果表明全球寒武系第三统Drumian阶上部δ13C值呈恒幅波状演化、波动范围较小,δ18O波动强烈、幅度较大;而第七阶下部δ13C值跳跃强烈、幅度较大,总体表现为高值,δ18O值波动减弱、趋向低值;全球寒武系第三统第七阶底部的候选GSSP正好处于δ13C值由恒幅波动向剧烈跳跃的转折处。第七阶早期δ13C值、δ18O值及海平面三者之间存在较好的耦合关系,表现为海平面上升到最高位置、δ13C值较高、δ18O值较低,造成耦合的原因可能为全球气候变暖,大量淡水流向海洋、海域扩大,初始生产率提高,较多12C为生物所摄取,导致海水中13C的浓度相对升高,沉积的碳酸盐岩具有较高的δ13C值。同时,由于最大海泛期洋流活动频繁,对江南斜坡带沉积作用有一定影响,致使碳酸盐岩沉积物的碳、氧同位素组成变化较大。

关键词(KeyWords)： 碳、氧同位素地层;寒武系第七阶;寒武系;罗依溪剖面;湖南;中国南方

Abstract:

Keywords:

基金项目(Foundation): 国家自然科学基金项目(No40672023,40332018)

作者(Author): 左景勋,彭善池,祁玉平,林焕令,朱学剑,杨显峰

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