摘要
本文将我国西北地区的印支运动划分为两期两幕。其早期包括早、中三叠世期间,印支运动第一幕发生在中,晚三叠世之间;晚期包括晚三叠世期间,印支运动第二幕发生在晚三叠世与早侏罗世之间。作者认为,西北地区的印支运动不仅使秦祁昆和巴颜喀拉海洋关闭,海槽内沉积物全部褶皱成山,并镶嵌于华北-塔里木地台的旁侧,而且使区内地壳运动的性质发生了根本的改变,即开始全部转为地台内部的造陆运动和断块差异升降运动,从而奠定了中新生代的构造格局。
This paper treats of the Indosinian Orogeny in northwestern China, which not only made the closure of Qin-Qi-Kun(Qinling-Qilian-Kunlun Mts.) and Bayan Har old ocean, and the folding of the sedimentary pile in the ocean into mountains that accrete to the flank of North China-Tarim platform, but also transformed the nature of earths crust in the investigated region. From that time, Structural movement turned over to epeirogeny within plat- form and differential lifting and sinking of fault blocks so that this move- ment may have epoch-making significance in the geoloical history. Two stages and two episodes concerning Indosinian Orogeny in the re- gion under study are sparated as follows: The early stage includes early-middle Triassic Period. Marine transgres- sion took place in the Qin-Qi-Kun and Bayan Har region, accepting huge thick sedimentary material of geosycllnal type. While Qin-Qi-Kun north to the region, there already got into the environment of continental sedimenta- tion. In the Ordos and some intermontane basins, accumulated continental facies clasolite in which piedmont and fluviolacustrine facies being dominant The first epi, sode of Indosinian Orogeny took place between Middle and Late Triassic Epoch, which let to the close of Qin-Qi-Kun trough and folding reversion, and enhancing the expansion of Bayan Har old ocean in coniunc- tion with the formation of some continental basins in Mesozoic Era. In late Indosinian stage, including Late Triassic Epoch, Qin-Qi-Kun Mts. had folded and rised at that time, and a topography of alternating ranges and basins was formed, and the expansion of Bayan Hat ocean had gone fur- ther. While terrigenous sediments, mainly in fluviolacu strine facies with coal, petroleum and oil shale deposits. had aceumulated in Ordos and some intermontane basins lying to the north of Qin-Qi-Kun Mts. The second epi- sode of Indosinian Orogeny came into being between Late Triassic Epoch and Early Jurassic Eopoch, resulting in foling reversin of Bayan Har ocean entire- ly, but Tethyan ocean contracted further and the Cathays ia continent ex- panded simultaneously. Thus founded the embryonic form of huge inland ba- sins in northwestern China. Faulting at the margion of intermontane basins has been strenthened further. All this Show that the differential vertical movement of the fault blocks within the continent has began to be drastic.
