论文部分内容阅读
青藏高原中东部分布着一系列中小型古近纪盆地,详细的野外地质调查、盆地构造-沉积学和生物地层学、地球化学和岩浆岩的40Ar/39Ar年代学结果表明,盆内充填了紫红色的陆源碎屑岩夹火山碎屑岩、碳酸盐岩和石膏层,并被晚期岩浆岩所切割,盆缘地层发生大规模掀斜而形成高陡地层和挤压向斜,盆内地层发生褶皱变形。地层内部细碎屑岩孢粉和古植物、火山碎屑岩和侵入岩的40Ar/39Ar年代学揭示盆地充填沉积物形成于38～28Ma(晚始新世—早渐新世)。古近纪紫红色沉积物、碳酸盐岩和石膏层的出现代表干旱-炎热的古气候环境。印度-欧亚板块碰撞过程中因陆壳变形和高原早期构造隆升产生的走滑拉分和逆冲挤压是导致高原中东部古近纪盆地裂解和封闭的主要原因。
A series of small and medium-sized Paleogene basins are distributed in the eastern part of the Qinghai-Tibet Plateau. Detailed field geologic survey, basin tectono-sedimentology and bio-stratigraphy, geochemistry and magmatic rock 40Ar / 39Ar chronological results show that the basin is filled with purple The red terrigenous clastic rocks trap volcaniclastic, carbonate and gypsum layers and are cut by late magmatic rocks. Large-scale tilting of basin margins results in the formation of high-steep strata and crustal synclines. Wrinkle deformation occurred. The 40Ar / 39Ar chronology of fine clastic palynospores and palaeo-phylalases, volcaniclastic rocks and intrusive rocks within the strata reveals that the basin-filling sediments formed during 38 ~ 28Ma (late Eocene-Oligocene). Paleogene mauve deposits, carbonate rocks and gypsum layers represent the arid-hot paleo-climate. During the collision between India and Eurasia, the strike-slip points and thrusting caused by crustal deformation and early tectonic uplift of the plateau are the main reasons for the cracking and closure of the Paleogene basins in the middle and eastern plateau.