贵州寒武系底部碳同位素负异常的地层学和生物学意义  

Negative Carbon Isotope Excursion in the Base Cambrian of Guizhou Province,China: Implication for Biological and Stratigraphical Significance

作　　者：杨瑞东[1] 朱立军[1] 王世杰[2] 姜立君[1] 张位华[1] 高慧[1] 

机构地区：[1]贵州工业大学,贵阳550003 [2]中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550002

出　　处：《地质学报》2005年第2期157-164,共8页Acta Geologica Sinica

基　　金：国家重大基础研究预研项目 (编号 2 0 0 2 CCC0 2 60 0 );贵州省优秀科技人才基金;国家自然科学基金 (编号 40 0 62 0 0 1);中国博士后科学基金资助

摘　　要：贵州境内早寒武世早期几乎都是黑色页岩沉积。最近在贵州福泉英坪寒武系底部却发现了一套泥岩夹薄层灰岩,它为研究早寒武世早期海洋地球化学特征提供了条件。贵州福泉英坪前寒武系—寒武系界线附近的碳同位素强烈的负异常特征可与全球同期碳同位素进行对比,它对应于中国云南会泽小歪头山段底部、蒙古Tsagaan Oloom组顶部、西伯利亚Salarrny Gol组顶部、美国西南、伊朗、安曼、波兰、纽芬兰、英国、加拿大等地新元古代—寒武纪界线附近的强烈碳同位素负异常,它可作为划分前寒武系—寒武系界线重要依据。该剖面上碳同位素强烈负异常之下有8m厚的黑色页岩和硅质岩,在黑色页岩中发现有大量高肌虫和虫管化石,说明缺氧的黑色页岩沉积期间海洋中有大量的生物生活,但到了灰绿色泥岩和灰岩互层的碳同位素强烈负异常层段,则几乎没有生物化石。可以说缺氧事件对前寒武系—寒武系界线附近生物绝灭事件似乎没有很大的影响,而碳同位素强烈的负异常事件与前寒武系—寒武系界线附近生物大绝灭关系更为密切。The black shale is widely and mostly in the base Cambrian of Guizhou Province. Therefore, to study the carbon isotope excursions on Neoproterozoic—Cambrian boundary in Guizhou Province for geologist is difficult. Then, the 60 m thick base Cambrian consisting of mudstone interbedded thin limestone was discovered recently in Yingping, Fuquan County, Guizhou Province. This discovery is beneficial to study the ocean environment of the early Cambrian. The notable negative C isotope excursion on Neoproterozoic—Cambrian boundary in Yingping, Fuquan County, Guizhou Province compares with the most continuous C isotope chemostratigraphy from the Xiaowaitoushan Member of the Laolin section in Lunaqian village, Huize County, northern Yunnan Province, southwest China, and that from the upper Tsagaan Oloom Formation of southwest Mongolia, and that from the upper Salarrny Gol of northern Siberia, and that from Mackenzie Mt. Canada, and that from Iran, Oman, Poland and Britain. The notable negative carbon isotope excursion has been shown to be a powerful tool for the global division and correlation of Neoproterozoic—Cambrian boundary. The notable negative C isotope excursion in Yingping section, Fuquan County, Guizhou Province, which is located at 20 m thick succession over the Dengying dolostone, then, between this notable negative C isotope excursion and the Dengying dolostone has 8 m thick black shale and siliceous rocks bearing abundant Bradorida and Priapulida fossils, it is shown that ocean animals ware thriving while the black shale and siliceous rocks deposited, but the grey-green mudstone interbedded thin limestone with notable negative C isotope upon the black shale and siliceous rocks is deficient in fossils, and it is shown that mass extinct event at the Neoproterozoic—Cambrian closely relate to this global negative C isotope excursion, but not oxygen-deficient event.

关 键 词：贵州 寒武系 碳同位素 负异常现象 地层学 生物学 

分 类 号：P539.7[天文地球—古生物学与地层学]