西昆仑及邻区早-中二叠世构造—岩相古地理特征

The characteristic of tectonic-lithofacies paleogeography during Early-Middle Permian in the west Kunlun and adjacent areas

通过大量野外观察、分析测试和综合研究,结合覆盖全区1∶25万区域地质调查资料及其他前人工作成果,研究了西昆仑及邻区早-中二叠世构造-岩相古地理特征,并探讨了其形成机制。研究表明:西昆仑及邻区早-中二叠世发育典型的沟弧盆系统,自北向南依次发育塔里木陆块、西昆北弧后裂谷盆地、西昆中岩浆弧、西昆南增生楔、玉龙塔格-巴颜喀拉洋盆及甜水海地块。陆相、海陆过渡相、滨浅海相、半深-深海相均有发育,岩相反映的纵向序列表现为海进-海退的旋回性变化,岩浆活动强烈,构造-古地理环境复杂。早-中二叠世是玉龙塔格-巴颜喀拉洋盆扩张最为剧烈且规模为最大时期,主体处于伸展构造背景。中二叠世晚期强烈的华力西构造运动使古板块间的相对运动加剧,玉龙塔格-巴颜喀拉洋盆大洋岩石圈板块向北强烈俯冲,西昆北弧后裂谷盆地形成。早-中二叠世为研究区地球动力学机制从强烈扩张到强烈汇聚的转折时期,加强其构造-岩相古地理特征的研究对建立该区地层序列、探讨其地质演化历史以及指导找矿工作等均具有重要意义。

After much more field observe, analyse, experiment and integration research, thinking of the 1 ： 250 000 region geological survey data and the other researcher work results, study in the characteristic of tectonic-lithofacies Paleogeography during Early-Middle Permian in the west Kunlun and adjacent areas and discuss the mechanism of formation. The paper suggest that the normal ocean trench-arc-basin system developed in this areas and in this time, from north to south,that are Tarim continent plate, west Kunlun behind arc rift valley basin, west Kunlun middle magma arc, west Kunlun south accretionary wedge, Yulongtage-Bayankala ocean basin and Tianshuihai continent plate. Besides this, continental facies, continental-ocean facies, coastal-shallow sea,bathyal-deep sea facies were developed. Vertical direction was sea advance and regression cycles, magma strong activity, tectonic paleogeography eviroment complex. Yulongtage-Bayankala ocean basin developed strongly and be biggest in this time. In this later period,the Hualixi movment leading to the plates grew exacerbation and Yulongtage-Bayankala ocean basin plate subduction northward, subsequently, the west Kunlun behind arc rift valley basin had been formed, dynamics mechanism from strongly expanded to convergenced. It has much more significance for stratum, geological evolution and mineral deposit explore that research in this tectonic-lithofacies paleogeography in this area and this time.