【摘要】 峡东地区埃迪卡拉系陡山沱组自下而上可分4个岩性段:第1段为1.5—5m具帐篷和板裂构造的"盖帽白云岩";第2段是90—120m白云质灰岩夹黑色页岩,富含燧石结核;第3段为40—70m的白云岩夹燧石层和燧石结核;第4段10—20m为黑色碳质页岩夹碳酸盐岩透镜体。根据对该区九龙湾、王丰岗、田家园子、九曲脑、晓峰河、樟村坪等多条陡山沱组剖面的重新调查,确认第2和第3段分别含有不同的疑源类组合,二者被之间出现的δ13C负漂移(EN2)所分隔。下组合以Tianzhushania和高分异的具刺疑源类出现为特征。上组合与下组合的区别是:(1)Tianzhushania绝迹;(2)出现大量表面光滑,介于90—150μm的球状膜壳;(3)高分异的具刺疑源类既包括下伏上延的种类,又含有首次出现的新类型;(4)还出现可能为单细胞原生动物的微化石;(5)管状化石震旦圆圆茎(Sinocyclocylicus guizhouensis)首现。更多还原

【Abstract】 The Ediacaran Doushantuo Formation in the Yangtze Gorges is subdivided into four lithostratigraphic members in ascending order. Member 1 is about 1.5-5m thick cap dolomite with tepee-like structures,sheet cracks. Member 2 consists of 90-120m thick organic-rich dolomitic limestones and interbedded black shales,with abundant black chert nodules. Member 3 is 40-70m thick and consists of grey dolostones with thin bedded chert and irregular chert nodules. Member 4 is about 10-20m thick and consists of black shale with large carbonate concretions. Based on investigations in Jiulongwan,Wangfenggang,Tianjiayuanzi,Jiuqunao,Xiaofenghe and Zhangcunping sections,we confirm the presence of two different assemblages separately appear in the second and third members,which were separated by a δ 13 C negative excursion (EN2). The lower assemblage is characterized by Tianzhu-shania and a diverse suite of large acanthomorphic acritarchs. The upper assemblage is distinguished from the lower assemblage by (1) extinction of Tianzhushania; (2) occurrence of abundant 100-150 μm,smooth walled spherical microfossils; (3) highly diverse canthomorphic acritarchs,including species extended from the lower member and new forms in this member; (4) occurrence of unnamed new forms of metazoan; (5) occurrence of Sinocyclocylicus guizhouensis.更多还原