柴达木盆地及其邻区早—中二叠世构造岩相古地理格局

通过大量野外观察、分析测试和综合研究,结合覆盖全区不同比例尺的区域地质调查资料,对柴达木盆地及其邻区早—中二叠世构造岩相古地理格局进行了研究,并探讨了其形成机制.结果表明:柴达木盆地及其邻区中、北部早—中二叠世为陆内盆山裂谷系统,主体处于伸展构造背景,总体表现为堑垒相间的构造古地理格局;南部为巴颜喀拉洋盆,早—中二叠世是巴颜喀拉洋盆扩张最为剧烈且规模最大的时期,巴颜喀拉洋盆中洋岛、海山遍布;早—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,巴颜喀拉洋盆大洋岩石圈板块向北强烈俯冲,形成东昆仑陆缘岩浆弧及其南部增生带,东昆仑陆缘岩浆弧岩浆活动十分强烈,宗务隆山—西秦岭陆源裂谷盆地进一步发育,形成十分复杂的构造岩相古地理格局.早—中二叠世是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等均具有重要意义.

Early-middle Permian Tectonic-lithofacies Palaeogeographic Characteristics in Qaidam Basin and Its Adjacent Areas

Through the field observation,the analysis of test data,the comprehensive regional geological survey and the previous research result,the forming mechanism and tectonic-lithofacies paleogeography during the Early-middle Permian in Qaidam Basin and its adjacent areas were discussed.The results showed that the Early-middle Permian in the central and northern parts of Qaidam Basin and its adjacent areas was intracontinental basin-and-range and rift valley system,and mainly located on extensional tectonic setting,and the tectonic paleogeography was graben and horst alternately;the Early-middle Permian in the southern part was the period with most violent expansion cosmically in Bayankala ocean basin,and ocean-island and seamount were all over the ocean basin;the strong Hualixi tectonic movement in the late of Early-middle Permian caused that the relative movement was intensified between the ancient plates,the ocean lithosphere plate of Bayankala ocean basin dived to the north,so that East Kunlun epicontinental magmatic arc and the accretion zone in south were formed,magmation in the arc was strong,Zongwulong Mountain-West Qinling Mountain terrigenous rift basin further developed,and the complicated tectonic-lithofacies paleogeography was formed subsequently.The Early-middle Permian was the turning point from violent expansion to violent convergence for geodynamics mechanism in Qaidam Basin and its adjacent areas;strengthening the study on the tectonic-lithofacies paleogeography was significant for building the stratum sequence,discussing the geological evolution history and mineral deposit prospecting.