苏北盆地构造特征及箕状断陷形成机理  

Tectonic features of the Subei Basin and the forming mechanism of its dustpan-shaped fault depression

作　　者：陈安定[1] 

机构地区：[1]中国石油化工股份有限公司江苏油田分公司地质科学研究院,江苏扬州225009

出　　处：《石油与天然气地质》2010年第2期140-150,共11页Oil & Gas Geology

摘　　要：苏北盆地是典型的箕状断陷,具"坳(K2t—E1f)-断(E2d—E2s)-坳(N1-2y)"3层结构,分"裂陷、断-坳、断-翘"3种类型,历经3次抬升改造,是古近纪晚期的"残留盆地"。苏北盆地发育不同类型的断裂组合,北东、北西方向构造。文章探讨了箕状断陷形成机理,指出地层掀斜不可能通过"旋转"产生,大量的张性断层主要产生于先期逆断的盆地基底和力偶反向,箕状盆地是凹陷在同一方向上遭受拉张、裂陷和挤压、基底拱升交替作用时接受沉积或抬升削蚀的结果。而拉张和挤压的动力主要来自印度板块、太平洋-菲律宾板块对欧亚大陆的俯冲、碰撞,两者的交替作用使中国东部在北西方向上形成张-压交替的"手风琴式"力学环境,从而造就了基底拱升式断-坳结合型箕状盆地。The Subei Basin is a typical dustpan-shaped fault depression composed vertically of three layers, i. e. ,a downwarped basin deposit（ K2t- ELf）, a fault depression basin deposit（ E2d- E2s） and a tilt-block basin deposit（ N1-2Y）. The basin had gone through three episodes of uplifting and is a relic basin formed in the late Early Tertiary. It also developed some fault combinations of different types and NE- and NW-trending structures. This paper documents a discussion on the forming mechanism of the dust-shaped fault depression, and comes to the conclusion that the tilting in the depression is the least likely to be caused by ＂rotation＂, and that the numerous extensional faults were resulted from the early reverse faulting of the basement and the reversing of force couple. The present dustpan-shaped basin is the result of deposition or uplifting and erosion when experiencing extension, faulted depression and compression at the same direction, alternating with basement uplifting. The dynamic of the extension and compression mainly came from the subduction and collision of the India Plate and the Pacific-Philippine plate to the Eurasia. With the two forces alternatively working on the eastern China, an ＂accordion-like＂ stress field （with extension and compression alternated） was formed in the NW direction, in the dustpan-shaped basin. resulting

关 键 词：成盆动力学 右行剪切 左行剪切 复杂小断块 残留盆地 断陷盆地 箕状凹陷 苏北盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]