盆地岩石圈结构与油气成藏及分布

本文综述了大陆岩石圈研究现状和克拉通盆地、裂谷盆地和前陆盆地的岩石圈结构特征,指出在古裂谷、褶皱带或区域性深断裂等陆壳构造薄弱带上发育起来的多期叠合盆地,具有很好的含油气前景。大型含油气盆地往往存在地幔上隆、地壳减薄和地壳内低速层,盆地基底沉降与盖层沉积厚度较大。适度的后期构造活动改造和岩浆活动有利于沉积盆地内油气生成与保存。

LITHOSPHERE STRUCTURES, PETROLEUM ACCUMULATION AND DISTRIBUTION IN PETROLIFEROUS BASIN

The lithospheric structures for cratonic, rift and foreland basins were summarized in the paper, from which an important relation between the continental crustal structure and oil/gas perspectivity could be found. These basins were often developed on the pre existing weak crustal structure zones, such as the ancient orogenic belt, failed rift (aulacogen) zone and crustal fracture zone, which were favorable for deposition of source, reservoir and seal rocks, so that the accumulation and preservation of oil and gas formed as the crust subsiding along the failed rift in a relatively steady tectonic setting. Due to the continuous subsidence of the continental crust along the same weak structure zone, the superimposed basins created by multi cyclic movements. As a result, the interior cratonic basin could be developed, overlying the failed rift or the basement fault belt. The rift basins, with a thick deposits of syn rifting and post rifting, were very rich in oil and gas resources, generally. The moderate tectonic movements and igneous activities of the continental crust was favorable for the generation, migration and preservation of oil and gas, which was evidenced by many giant and super giant fields found in the slightly to moderately inverted rift basins, ancient rifts, and interior cratonic basins with slightly active reacted basement faulting and steadily subsiding foredeep basins. The Riphean Palaeozoic basins with abundant oil and gas resources were generally developed in a stable tectonic setting. The major Mesozoic petroliferous basins had relatively weaker tectonic activities, and major Cenozoic ones experienced relatively stronger tectonic movements. The stronger interactivity between the crust and the mantle, the more abundant oil and gas resources in sedimentary basins.