下扬子地区中-新生代的挤压变形与伸展改造及其油气勘探意义

以地表变形特征、地层厚度变化和地震剖面为约束,构建了贯穿下扬子地区主要构造单元的三条地质大剖面。剖面展示了研究区早期褶皱逆冲、晚期伸展断陷的构造格局,并揭示了变形的空间差异。通过对褶皱卷入的层位、断层与地层的切割关系及不整合类型和发育特征的梳理,得出研究区北侧的褶皱逆冲主要形成于中-晚三叠世,南侧的褶皱逆冲主要形成 于中-晚侏罗世。两侧的挤压构造在晚白垩世开始都经历了强烈的拉张作用,北侧的断陷一直持续到古近纪,新近纪以拗陷为主,而南侧古近纪断陷规模较小,新近纪拗陷不发育。苏州-无锡地区的下古生界受后期改造作用较弱,是油气勘探的有利地区。

The Mesozoic-Cenozoic compressional deformation, extensional modification and their significance for hydrocarbon exploration in Lower Yangtze region.

Constrained by structural styles in outcrops,thickness of strata and seismic sections, three regional cross sections were constructed across the main structural units in Lower Yangtze region. These cross sections display the superimposition of early compressional and late extensional tectonic features, and also reveal some spatial differences in the deformation styles. According to the strata involved in the deformation, cross-cutting relationships, the types and distribution of unconformities, we confirm the thrusts and folds in the north of the region were formed during Middle-Late Triassic,while in the Middle-Late Jurassic for those in the south; intensive rifting occurred in the whole region during Late Cretaceous and continued into Paleogene in the north; extensive depression has developed in the north since Neogene, while it took place only during Quaternary in the south. The Lower Paleozoic of Suzhou-Wuxi area is favorable for hydrocarbon exploration as it was not destructed by rifting.