论下扬子地区多期构造格局叠加及其油气地质意义

The multi stage structure frame of Lower Yangtze basin evolution and its significance in petroleum geology.

下扬子地区在长期演化过程中形成了多期构造格局叠加，决定了海相古生界、中生界及其烃源岩的复杂保存情况及成藏条件。该地区早期受秦岭洋和华南洋（ 两大缝合带） 演化控制，构造格局表现为“一台两盆”和“南台北盆”；印支期至早燕山期受华北、华南两大板块之间北西南东向挤压对冲作用控制， 大致以沿长江的中央台地为对冲向斜带，形成北东向成带分布的推覆构造带，伴随近东西向左旋走滑活动，发育火山沉积盆地；燕山晚期，构造应力场转换，北东向、近东西向构造控制了晚白垩世—早第三纪的断陷沉积，形成高、中、低台阶古地貌，区内北西分带、南北成块的构造格局定型。综合分析不同时期构造格局的特点，对下扬子地区构造区划、区带评价和勘探部署有重要指导意义。认为：中、低断块油气地质条件较好，其中推覆前缘山带、后缘凹陷可寻找多种类型油气藏，而对冲向斜带（无为、句容等地） 是海相中生界、古生界油气勘探的优选地区。

There have formed multi stage structure frames in the course of the evolution of Lower Yangtze basin. Like “one platform with two basins” and “southern platform with northern basin”, the primary sedimentary structure of Lower Yangtze basin was controlled by Qinling ocean and Huanan ocean; the compressive ramp of South and North China plates during Dosinian Early Isoplatine period by SE NW direction, almost taking the centre bench terrace along Yangtze river as ramp syncline zone, formed nappe structure system of NE direction with left slip of EW direction and the development of volcanic sedimentary basin; Tectonic stress field transformed in late period of Isoplatine, the fault basins of Late Cretaceous Early Tertiary period were controlled by the structures of NE and EW directions, the higher, medium and lower terraces formed, and also the structure frame belted in EW direction, lumping in SN direction at last, being preserved and strengthened in general extension background later. The basin's structure evolution and structure congruent determines the conditions of preservation and pool formation of marine Meso Paleozoic Group and the resource rock, it is greatly significant to structure regional, evolution, exploiting arrangement of Lower Yangtze by the comprehensive analysis the Characteristic of different periods' frame. The conditions of petroleum geology of medium and lower blocks are comparatively advantageous, particularly the frontal mountain belt and postmarginal depression, the best areas of ramp syncline for petroleum exploration are Wuwei, Zhuyong, etc..