摘要
燕山运动导致喀拉昆仑-唐古拉侏罗纪特堤斯海封闭,形成巨大的燕山褶皱带;同时在大陆内部形成一系列北西西向或近东西向平行排列的山脉和内陆山间盆地,发育逆掩和推覆构造,以盖层为主的褶皱普遍,多期次的岩浆活动形成丰富的内生金属矿产及许多有工业价值的重要煤田。本区燕山运动可分为两期五幕,即早期燕山运动包括早、中侏罗世,中、晚侏罗世以及晚侏罗世至早白垩世之间的三个幕,晚期燕山运动包括早、晚白垩世,晚白垩世至早第三纪两个构造幕。最后对本区燕山期构造活动的机制进行了讨论。
Yenshan movement appears very disticntly in eastern China and even up to the western littoral area of circum-pacific belt. Extensive effect is shown in Northern China too, which not only made Karakorum-Tanggula trough form a huge belt of folded strata in Yenshan period, but also generated a series of huge linear upheaval and depression trending NWW or near E-W within Qin-Qi-Kun (Qinling-Qilian-Kunlun Mrs.) and Tianshan folded mountain system which led to the formation of a structural pattern of ridge basin alternating with upheaval and depression. Different elevation and subsidence movement of the fault block shows extreme intensity), over-thrust and nappe structure are common. Some previous belts of rift show various degree of tensile) compressine and strike-slip at this period. A number of newborn rifts were formed. Some of folds dominating in the over-lying strata form a well-knit linear struture within the engeosynclin, while structural deformation is rather weak in the craton basin. Polyphase and polycycle magmatism accompanied by Yenshan movement form abundant syngenetic deposit such as cupper, molybdenum and uranium and so on. Yenshan movement is divided by the authors into two periods and five episodes, that is, early Yenshan movement includes three episodes of Early, Middle Jurassic Epoch and Middle, Late Jurassic Epoch as well as Late Jurassic, Early Cretaceous Epoch) late Yenshan movement includes two episodes of Early, Late Cretaceous and between Late Cretaceous and Early Tertiary Period. They represent a structural alignment of the earth crust evolution at that time respectively. Among them the third and fifth episode are marked by relative intensive structural deformation and magmatism. They are of regional, structural episodes which can contrast with the conrresponding ones in eastern China. The mechanism of the formation of Yenshan movement is the result of combined action of multiple factors which can be explained by:1. the subduction together of the Tethyan ocean crust and pacific ocean into Eurasian continent led to the compressive function; 2.the formation of and transformation of the mantle upheval and depression resulted by the convection current and creeping action of the mantle material and; 3.the unbalanced movement resulted by the mutual pushing and sequeezing of the crust block as well as earth-self rotation and so on.
