晚震旦至中奥陶世下扬子被动大陆边缘原型盆地特征

Late Sinian-Middle Ordovician the Prototype Basin Characteristics of Passive Continental Margin in Lower Yangtze

随着油气二次创业的深入,海相地层已成为油气勘探领域的重点.下扬子沉积了巨厚的海相地层,其原型盆地经历了多期次的构造改造.通过对下扬子边界的讨论,对其进行系统的整体分析.在活动论构造历史观和盆地原型分析TSM工作程式的指导下,通过对下扬子晚震旦至中奥陶世残留地层分布状况以及该时期沉积充填过程的分析,确定了晚震旦至中奥陶世下扬子原型盆地的性质为被动大陆边缘,其特征主要表现在硅质碎屑沉积物、碳酸盐岩沉积物和同生断裂现象等方面.该时期碳酸盐岩台地发育成镶边台地,台地有侧向生长现象和向海盆输入沉积物的舌状凸起,以江南断裂为代表的同生断裂表明盆地沉积物的物源始终是从下扬子内部自西北向东南方向单向搬运,这些均表明晚震旦至中奥陶世为成熟的被动大陆边缘.

As the second oil and gas pioneering project progresses,marine strata has become the focus in the field of oil and gas exploration.Lower Yangtze has deposited thick marine strata,and its prototype basin has experienced structural transformation of multi-period times.This paper discusses the boundary under the Yangtze,aiming to conduct a systematic analysis of the entire system.Based on the＂TSM＂strategy of basin prototype analysis on the basin tectonics,deformation and sedimentary,the residual strata distribution from Late Sinian to Middle Ordovician in the Lower Yangtze and the sedimentary filling during the process are analyzed.The results indicate that the Lower Yangtze has evolved passive continental margin in the Late SinianMiddle Ordovician,which is characterized mainly by siliceous classic sediments,carbonate sediment and synsedimentary faults,etc..During this period,carbonate platform developed into trim platform.The platform had lateral growth phenomenon and the sediment of tongue protruding input to the sea basin.Jiangnan fault,a typical synsedimentary fault,shows that the source material of the sediment basin has always been transported from northwest to southeast by the internal one-way transportation in the Lower Yangtze.All these indicate that it was mature passive continental from the Late Sinian to Middle Ordovician.