苏皖北部下寒武统对前南华系的超覆  

OVERLAPPING OF THE LOWER CAMBRIAN HOUJIASHAN FORMATION OVER THE PRE-CRYOGENIAN SEQUENCES IN THE NORTHERN JIANGSU AND ANHUI PROVINCES

作　　者：厉建华[1] 钱迈平[2] 姜杨[2] 

机构地区：[1]江苏省地质调查研究院江苏南京210018 [2]南京地质矿产研究所江苏南京210016

出　　处：《地层学杂志》2013年第2期232-241,共10页Journal of Stratigraphy

基　　金：国家自然科学基金项目(No.40872006);国家自然科学青年基金项目(No.41002024);中国地质调查局基础地质综合研究项目(No.1212010610611);中国地质调查局基础地质调查项目(No.1212010981012);中国科学院知识创新工程项目(No.KZCX2-YW-Q05-01)资助

摘　　要：苏皖北部新元古代地层的区域划分对比、时代及其与上覆地层的接触关系长期存在争议,主要有二种意见:其中一种观点是刘老碑组上部以上的新元古界地层均为震旦系,与上覆寒武纪地层之间并无较大沉积间断,为假整合接触;另一种看法是该地区寒武纪地层超覆在新元古界不同层位的岩组之上,二者之间存在较长的沉积间断,并存在规模不等的构造运动。最近笔者对该区寒武系—新元古界各界线剖面进行了详测,在获得大量地层空间分布资料的基础上,证明下寒武统超覆在新元古界不同层位的岩组上,而且生物地层对比也表明其间存在较大的沉积间断,这里的新元古界为更古老的前南华系地层。The northern Jiangsu and Anhui provinces is at the south-eastern margin of the North China Plate and its Neoproterozoic sequences are up to about 5000 m thick, resting unconformably on the Fengy- ang Group schists and Wuhe Group gneiss （where the radiometric age 2650 Ma, zircon U-Pb technique） and unconformably covered by the Lower Cambrian Houjiashan Formation. The Neoproterozoic-Cambrian boundary is represented by the regional unconformity between the different horizontal formations in differ- ent locations and the overlapping Lower Cambrian Houjiashan Formation. According to the biostratigraph- ic correlations based on predominant assemblages of Charaia-Tawuia type macrofossils, Leiosphaeridia- Trachysphaeridium type microfossils and Conophyton-Acaciella-Baicalia-Jurusania type stromatolites, the Neoproterozoic sequence in this region can be correlated with that of the Jixian and eastern Liaoning re- gions, and suggest that the formations is Pre-Cryogenian. The biota in this region is considerably primary and simple, compared with the Sinian Doushantuo^s （post-Nantuo Glaciation） or Lantian^s （post-Leigongwu Glaciation）. Reasonably. This assemblage was possibly deposited preceding these Cryogenian Glaciations, and it is a Pre-Ediacaran biota. On the basis of integrated lithologic, biostratigraphic and structural data, we could reveal the geologic history of northern Jiangsu and Anhui provinces from Neoproterozoic to early Cambrian. During Qingbaikou period, Huainan district in southern part of the region was transgressed in the first instance, and then this region was whol- ly merged by warmly shallow sea, with the transgression expanded. The folds and uplifts by structural movements caused Huainan district emerged firstly, and sea water withdrew from Huanbei district in northern part of the region finally. This region was weathered until an early Cambrian transgression, and the sediments of Houjiashan Formation overlapped different horizontal Neoproterozoic formations in differ- ent locations.

关 键 词：岩石地层 前南华系 新元古界 下寒武统 江苏 安徽 

分 类 号：P534.3[天文地球—古生物学与地层学]