青藏高原东北缘酒泉盆地的演化特征与宽台山-黑山断裂的性质
Evolutionary char-acteristics of the Jiuquan basin and character of the Kuantaishan-Heishan fault on the northeastern margin of the Qinghai-Tibet Plateau
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摘要: 宽台山-黑山断裂位于酒泉盆地的北侧,向西与阿尔金走滑断裂相交,其北部为花海-金塔盆地。对酒泉地区白垩纪沉积盆地的研究和对比发现,虽然当时盆地多为断陷盆地,均受东西向伸展构造控制,但宽台山-黑山断裂两侧的盆地具有不同的基底性质和沉积岩石学特征。酒泉盆地、昌马盆地和北祁连褶皱带内的白垩系具有相同的早古生代褶皱基底,并发育有热水喷流沉积和玄武岩夹层,北祁连北缘断裂在白垩纪时尚未开始活动;花海-金塔盆地为前长城系深变质基底,盆地内不发育热水喷流沉积。宽台山-黑山断裂是青藏高原东北缘重要的岩石圈剪切断裂,控制了其南北两侧白垩纪盆地的沉积-构造演化。Abstract: The Kuantaishan- Heishan fault, located on the north side of the Jiuquan basin and to the south of Huahai- Jinta basin, intersects with the Altyn Tagh strike- slip fault at the western end. Comparative study of the Cretaceous basins in the Jiuquan basin shows that the basins on either side of the Kuantaishan- Heishan fault have different basement natures and sedi- mentary characteristics though the basins then were mostly downfaulted ones and all controlled by E- W extensional tectonics. The Cretaceous strata in the Jiuquan basin, Changma basin and the North Qilian fold belt have the same Early Paleozoic basement and exhalative sediments and basalt interbeds are developed. The North Qilian marginal fault was not active in the Cretaceous. The Huahai- Jinta basin has the high- grade metamorphic pre- Changchengian basement,and in the basin exhalative sediments are not developed. The Kuantaishan- Heishan fault is an important lithospheric shear fault, which controlled the sedimentary and tectonic evolution of the Cretaceous basins on its both sides.