新构造运动在南黄海盆地的表现及其对油气成藏的影响

Neotectonic evolution and its influence on oil and gas accumulation in the South Yellow Sea Basin

在精细地震资料构造解释基础上,认为上新世-第四纪是南黄海盆地新构造运动的主要活动期,对应南黄海盆地第二个阶段的断裂活动期。垂向上,新构造运动具有早晚构造响应差异:早期南北向弱挤压背景下以张性正断层为主,晚期东西向两幕挤压背景下以逆断层和褶皱为主;平面上,新构造运动影响亦具有差异:北部坳陷活动强烈、正断层发育、逆断层少量,而南部坳陷活动较弱。新构造运动与北部坳陷烃源岩的生排烃时期吻合,断裂带是重要输导体系,也是重要的潜在成藏区。

Two phases of faulting once occurred in the South Yellow Sea Basin: Late Cretaceous to the Palaeogene,and the Neogene to the Quaternary,of which the Pliocene to the Quaternary is the main periods when the neotectonic movements were accentuated in the South Yellow Sea Basin. Vertically, the early NS-trending compressional faulting lead to the development of the extensional normal faults whereas the late EW-trending compressional faulting lead to the development of the thrust faults and folds. Horizontally,the downwarped faulting is highly active and the normal faults are well developed in the northern part of the Basin whereas in the southern part of the Basin,the downwarped faulting is relatively inactive. The timing of the neotectonic movements cited above is thought to be in agreement with those of the generation and expulsion of the hydrocarbons in the source rocks from the northern depression. The faults generated by the neotectonic movements may serve as not only the vertical migration channels for the hydrocarbons but also the favourable areas for the oil and gas accumulation in the South Yellow Sea Basin.