丽水-椒江凹陷构造演化特征与油气聚集

通过对东海盆地丽水-椒江凹陷构造特征及其演化历史的分析,认为该凹陷基本构造特征为\"南北分区,东西分带\",并具有典型的东断西超的半地堑式的构造特征。凹陷经历了多期的构造活动,使得研究区内断裂非常发育,期间多次的抬升剥蚀,造成了多个构造层系之间的区域性不整合,并形成了多种类型的构造圈闭。其形成演化过程可分为裂谷盆地、断陷、坳陷和区域沉降4个阶段:早期在太平洋板块、欧亚板块和库拉板块的联合作用下,产生了凹陷的雏形――裂谷盆地;后期由于太平洋板块的持续俯冲所产生的弧后拉张效应,将凹陷改造成了断陷型盆地;始新世时太平洋板块的俯冲方向发生改变,形成坳陷;上新世时凹陷处于平稳补偿沉积状态,但随后多次的区域隆升,使部分先期沉积的地层遭受剥蚀,形成了区域性的不整合面。同时凹陷内主要断裂的长期活动控制了烃源岩的发育与分布,促进了油气的垂向运移,并且对油气的聚集也有一定的影响。

CHARACTERS OF TECTONIC EVOLUTION OF THE LISHUI-JIAOJIANG SAG AND OIL ACCUMULATION

The research on tectonics evolution and petroleum geology of Lishui-Jiaojiang sag in the East China Sea shelf basin shows that Lishui-Jiaojiang sag could be divided to be south area and north area by second-order transfer zones from south to north, and four belt s could be seen clearly from west to east. The central area is typical sag with fault in the east and overlap in the west. Affected by repetitious tectonic events, a mass of faults and kinds of structural trap emerged. The periods of tectonic form action and its evolution consist of four periods of time, the embryo mold of the sag-rift basin-emerged in the united effect of three plates (the Pacific plate, the Eurasia Plate and the Kula Plate), then as the change of direction of the Pacific plate and the back-arc extension resulted by the durative plate seduction of the Pacific plate, the sag was changed to a fault basin, while several territorial unabiding uplifts took place, as a result, some stratums which formed formerly were denudated, so territorial unconformity surface appeared. The tectonic evolution features of the basins resulted in dynamic conditions for the hydrocarbon accumulation, on the other hand, transformed or destroyed the space-time distribution of dynamic and static stage geological element s and their match relations. While the mail faults in the sag also controlled the development and distribution of source rock and accelerated the vertical migration of oil, at the same time, the accumulation of oil and gas was also effected by them.