华南新元古代盆地开启年龄及沉积演化特征——以赣东北江南次级盆地为例  

The Onset and Sedimentary Evolution of the Neoproterozoic Basin in South China: A case study of the Jiangnan sub-basin,northeastern Jiangxi

作　　者：王剑[1,2] 周小琳[1,2] 郭秀梅[1,3] 付修根[1,2] 高永华[1] 

机构地区：[1]成都地质矿产研究所,成都610082 [2]国土资源部沉积盆地与油气资源重点实验室,成都610082 [3]成都理工大学,成都610059

出　　处：《沉积学报》2013年第5期834-844,共11页Acta Sedimentologica Sinica

基　　金：国家自然科学基金重点项目(批准号:41030315);中国地质调查局计划项目(项目编码:1212011121111)联合资助

摘　　要：最新地质调查与研究表明,赣东北江南次级盆地新元古界南华系是一套沉积超覆于基底变质岩系之上的裂谷系"楔状地层"。桃源组陆相火山岩及火山碎屑岩是该"楔状地层"的最低层位,代表了南华裂谷系江南次级盆地新一轮沉积旋回的起点。取自桃源组流纹岩样品的结晶锆石SHRIMP U-Pb同位素年龄为803±9 Ma,这一年龄值基本上代表了该次级盆地新元古代盆地的开启时间。沉积相研究表明,江南次级盆地沉积作用主要由四个沉积相组合构成:(1)陆相火山岩组合;(2)冲洪积相及河湖相组合;(3)滨浅海—次深海相组合;(4)冰碛岩相组合。与扬子东南缘其它次级盆地相比,江南次级盆地沉积作用以陆相为主,但两者的剖面沉积演化序列非常相似,都经历了一个由陆相至海相的沉积超覆演化过程,代表了新元古代南华期华南古大陆解体之后扬子地块东南缘典型的裂谷盆地演化特征。The northeastern Jiangxi region lies in the southeastern part of the Jiangnan sub-basin in the Nanhua rift systems. Recent results of research from the regional geological survey have disclosed that the Nanhua strata of the Neoproterozoic in the Jiangnan sub-basin consist of the rift wedge-shaped sedimentary strata which are overlapped upon the metamorphic basement. More precisely, the continental volcanic rocks and volcaniclastic rocks from the Taoyuan Formation occur in the lowermost horizons of the wedge-shaped strata, representing the onset of a new round sedimentary cycle in the Jiangnan sub-basin of the Nanhua rift systems. The rhyolite samples collected from the Taoyuan Formation give a SHRIMP U-Pb age of 8 039 Ma for the crystalline zircons, an initial age of the Neoproterozoic basin in northeastern Jiangxi. The sedimentary facies analysis indicates that the sedimentation of the wedgeshaped strata in the Jiangnan sub-basin is mainly composed of： （1） continental volcanic rocks association; （2） alluvial-diluvial facies and fluvial-lacustrine facies association; （3） littoral-neritic facies to the bathyal facies association, and （4） tillite facies association. Comparing with the other sub-basins in southeastern margin of Yangtze Block, the sedimentation of the Jiangnan sub-basin is predominated by continental facies other than marine facies, but both of them bears a striking resemblance in sedimentary succession, all went through a onlap process from continental facies to marine facies, representing the sedimentary evolution of the typical rift basin following the breakup of the South China palaeocontinent during the Nanhuan of the Neoproterozoic.

关 键 词：华南 江南次级盆地 锆石U-PB年龄 盆地开启 沉积相 裂谷盆地 

分 类 号：P542[天文地球—构造地质学] P512.2[天文地球—地质学]