宁镇山脉的盖帽碳酸盐岩  

THE BASAL EDIACARAN CAP CARBONATE IN THE NINGZHEN MOUNTAIN AREA, SOUTH CHINA

作　　者：胡春林 赵方臣[1] 纪秋梅 朱茂炎[1] HU Chun-lin;ZHAO Fang-chen;JI Qiu-mei;and ZHU Mao-yan(State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008;College of Earth Sciences,University of Chinese Academy ofSciences,Beijing 100049)

机构地区：[1]中国科学院南京地质古生物研究所和生物演化与环境卓越中心现代古生物学和地层学国家重点实验室,江苏南京210008 [2]中国科学院大学地球科学学院,北京100049

出　　处：《地层学杂志》2018年第4期381-392,共12页Journal of Stratigraphy

基　　金：中国科学院战略性先导科技专项(B类)资助(XDB18000000)

摘　　要：埃迪卡拉系底部发育一套覆盖在成冰纪冰碛杂砾岩之上的碳酸盐岩地层,被称为"盖帽碳酸盐岩",它是超级温室气候事件的沉积标志层,代表了新元古代"雪球"冰期的结束。通过对宁镇山脉地区新元古代地层的野外调查,在镇江丹阳帽山剖面南沱冰碛杂砾岩层顶部发现厚约4 m的含锰碳酸盐岩。沉积岩石学和稳定碳、氧同位素研究表明,这层碳酸盐岩具有盖帽碳酸盐岩的典型特征,可以与扬子板块其他地区的盖帽碳酸盐岩进行对比。这是宁镇山脉地区存在盖帽碳酸盐岩的首次报道。A suite of basal Edicaran carbonate which directly overlies Cryogenian diamictites worldwide is called the ＂cap carbonate＂. It marks the termination of the Cryogenian glaciation, representing the record of a su- per-greenhouse event. Characteristic cap carbonate has been well studied in most areas of the Yangtze platform. However, it has not yet been known in the Ningzhen Mountain area around Nanjing. Here we report for the first time the occurrence of cap carbonate in the area. The cap carbonate （〉4 m in thickness） in the base of the Dousahntuo Formation directly overlies the glacial diamictite of the Nantuo Formation. It exhibits characteristic sedimentary structures of the cap carbonate, such as well-developed irregular cavities filled with multiple genera- tions of fringing cements, giant tepee-like structures, and sheet cracks. The carbon isotopes show a upward decreasing trend from -3.6%0 to -5.1%o, suggesting its correlation with thoer basal Ediacaran cap carbonates worldwide.

关 键 词：岩石地层 盖帽碳酸盐岩 “雪球地球” 碳同位素 埃迪卡拉系 宁镇山脉 江苏 

分 类 号：P534.3[天文地球—古生物学与地层学]