川西前陆盆地南段薄皮冲断构造之下隐伏裂谷盆地及其油气地质意义

Buried rift basins under the Thin-skinned Fold-Thrust Belts in the South Segment of the western Sichuan Foreland Basin and their Geological Significance

陈竹新 贾东 魏国齐 李本亮 曾庆 杨光

Chen Zhuxin Jia Dong Wei Guoqi Li Benliang Zeng Qing Yang Guang

地震剖面构造解释发现,川西前陆盆地南段二叠纪之前发育伸展裂谷盆地,其中可能充填沉积了数千米厚的志留系—石炭系的古生代地层;晚期经历了新生代的构造挤压变形,最终在几何学上表现为一个双层构造,即浅层逆冲褶皱构造和深部裂谷构造。浅层构造表现为一些断坪-断坡式逆冲断层以及与其伴生的褶皱变形,构造样式主要表现为断层转折褶皱,局部褶皱发育突破断层;而深部裂谷构造则发育地堑盆地和半地堑盆地,遭受挤压变形后发育局部正反转变形,并使得上覆的二叠系、中生界和新生界发生同步褶皱变形。深部裂谷构造在一定程度上控制了浅层冲断构造的发育形成。川西前陆盆地南段深部的古生界以及由于构造反转形成的古生界和中生界背斜中具有巨大的油气潜力,是川西地区油气勘探的新领域。

Seismic interpretation reveals the rift basin in the south segment of the western Sichuan foreland basin,which had been developed before Permian,might be filled up with thousands of meters of Silurian-Carbo-(niferous) strata.The late stage of the area had gone through a tectonic compression in the Cenozoic,and as a result,the foreland basin exhibits a double-layer structure characterized by shallow fold-thrust structures and deep rift basins.The shallow structures consist of some flat-and ramp-related thrust faults and the associated fault bend folds,while the deep structures occur as graben-type basins and half-graben-type basins,which had experienced local positive inversion,resulting in the synchronous folding of the Permian,Mesozoic,and Cenozoic.The deep rift structures,to some extent,controlled the development of the shallow ones.It is suggested that the deep rift basins in the Paleozoic and the inverted anticlines in the Paleozoic and Mesozoic in the south segment in western Sichuan foreland basin may have large hydrocarbon potentials,thus are frontiers for exploration.

10.11743/ogg20060404