| 峡东青林口地区新元古代地层序列及沉积演变 |
| |
| 引用本文： | 安志辉,童金南,叶琴,田力,宋虎跃,赵小明.峡东青林口地区新元古代地层序列及沉积演变[J].地球科学,2014,39(7):795-806. |
| |
| 作者姓名： | 安志辉 童金南 叶琴 田力 宋虎跃 赵小明 |
| |
| 作者单位： | 1.中国地质大学生物地质与环境地质国家重点实验室，湖北武汉 430074 |
| |
| 基金项目： | 中国地质调查局地质调查工作项目(No.1212011120787);国家自然科学基金项目(No.41240016) |
| |
| 摘 要： | 峡东地区的新元古界由于保存良好的“雪球地球”沉积记录及其崩解后的“盖帽碳酸盐岩”和“庙河生物群”等关键地质记录，因而成为国际新元古界研究的热点地区之一.此次报道的青林口剖面是目前在峡东地区发现的出露最为完整的新元古代地层序列，对于揭示这一关键地质时期的重大生物演变和地球环境发展历程具有重要研究价值.重点介绍该剖面的地层序列并简要分析其沉积演变特点.该剖面出露新元古代地层自下而上依次包括莲沱组、南沱组、陡山沱组和灯影组.其中，莲沱组以紫红色砂岩夹页岩为主，由两个沉积旋回组成；南沱组角度不整合在莲沱组之上，以灰绿色杂砾岩为特征，划分为3个岩性段；陡山沱组以“盖帽白云岩”的出现为底界，以黑色硅质页岩的结束为顶界，划分为4个明显的岩性段；灯影组整体具有“两白夹一黑”的特征，自下而上划分为蛤蟆井段、石板滩段和白马沱段.青林口剖面地层出露完整，各组段岩性特征明显，清晰地反映了该区域的沉积环境演变历程.沉积记录显示，本区新元古代中期开始接受沉积，最先沉积陆相莲沱组，经历成冰纪晚期南沱组代表的“雪球”事件后转为海相沉积，埃迪卡拉纪沉积的陡山沱组和灯影组均为浅海开阔碳酸盐相或局限页岩相，成为后生动物起源和宏观藻类分异发展的创新基地.
|
| 关 键 词： | 新元古代 地层序列 沉积环境 三峡青林口剖面 |
| 收稿时间： | 2013-10-01 |
Neoproterozoic Stratigraphic Sequence and Sedimentary Evolution at Qinglinkou Section,East Yangtze Gorges Area |
| |
| Abstract: | The Yangtze Gorges area is one of the hot spots for the investigation of the Neoproterozoic in the world because of its well-preserved stratigraphic sequences recording the "Snowball Earth", "Cap Carbonate", and the "Miaohe Biota". The Qinglinkou section presented in this paper is one of the typical best-outcropped Neoproterozoic sequences in the area, providing good condition for the study of the significant biotic evolution and environmental changes during the critical time. The sequence is in lithostratigraphy composed of the Liantuo, Nantuo, Doushantuo and Dengying formations. The Liantuo Formation includes two sedimentary cycles of purple sandstones intercalated by some thin-bedded shale beds. The Nantuo Formation, uncomfortably overlying on the Liantuo Fm., is characteristic of grayish green diamictites but a member of shale with a few "drop stones" intercalated in the middle part of the formation. The Doushantuo Formation can be well subdivided into four members, among which the first one is "Cap Carbonate", the second dark dolomite interbedded with black shale, the third grey dolomite, and the last member black siliceous shale. The Dengying Formation is featured by the "two white clipping one dark unit" and they correspond with the Hamajing, Shibantan and Baimatuo members respectively. The study of the sedimentary sequence and environmental markers at the Qinglinkou section indicates that the sedimentation in the area started in the Middle Neoproterozoic time and the early sediments were terrestrial facies while the marine facies did not occur until the end of the glaciation of the "Snowball Earth" represented by the Nantuo diamictites. The Ediacaran Doushantuo and Dengying formations are either shallow-sea carbonate or districted shale facies, which became the innovation base for the origin of metazoans and the diversification of macroalgae. |
| |
| Keywords: | |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《地球科学》浏览原始摘要信息 |
|
点击此处可从《地球科学》下载全文 |
|
