摘要
震旦 寒武交变期是地史上一个重大转折期 ,亦是一个具有特殊意义的过渡时期。运用碳同位素地球化学方法 ,探讨扬子地台北缘四川南江地区晚震旦世 早寒武世交变期 ,碳同位素地球化学异常与环境变化和生物演化的相互联系。南江剖面沉积岩有机碳同位素组成在 - 35 .8‰～ - 30 .1‰间变化 ;碳酸盐碳同位素组成从 - 3.5‰～ +0 .5‰。在灯影组顶部、牛蹄塘组下部和上部 ,变化的碳、硫同位素组成和不同的黄铁矿与有机碳含量反映了有机碳埋藏量和环境的变化。下寒武统富有机碳和黄铁矿的黑色页岩沉积 ,暗示了早寒武世早期缺氧环境的存在。
The Precambrian-Cambrian transition is one of the critical time intervals in Earth history. Profound geotectonic climatic and biological changes occurred during late Neoproterozoic and the period of its transition into early Cambrian. This paper has studied paired carbonate and organic carbon isotope determinations of samples from Nanjiang of Sichuan Province on the northern Yangtze Platform, and provided a preliminary geochemical explanation for environmental changes in relation to bio-events on the northern Yangtze Platform during the Precambrian-Cambrian transitional interval. Organic carbon isotopic compositions of sediments vary from -35.8‰ to -30.1‰ and carbonate carbon isotopic compositions change between -3.5‰ and +0.5‰ along the Nanjiang section. Varied carbon and sulfur isotopic compositions and different contents of pyrite and organic materials reflect the changing environment and the burial of organic matter in the Dengying Formation and the lower and upper parts of Niutitang Formation. The anoxic conditions result in the widespread preservation of organic-rich sediments and pyrites in the black shale on the Yangtze Platform.
出处
《地球学报》
EI
CAS
CSCD
北大核心
2004年第2期151-156,共6页
Acta Geoscientica Sinica
基金
国家自然科学基金项目 (4 0 0 72 0 47
40 3 0 3 0 0 1)
德国基金项目 (Str 2 81/16 1)资助
关键词
晚震旦世
早寒武世
扬子地台
碳同位素
环境变化
Late Sinian to Early Cambrian carbon isotope composition environmental change Yangtze platform Nanjiang in Sichuan
