三江昌宁-孟连带原-古特提斯构造演化

昌宁-孟连特提斯洋的构造演化及其原特提斯与古特提斯的转换方式一直是青藏高原及邻区基础地质研究中最热门的科学问题之一.根据新的地质调查资料、研究成果并结合分析数据，系统总结了三江造山系不同构造单元地质特征，讨论了昌宁-孟连特提斯洋早古生代-晚古生代的构造演化历史.通过对不同构造单元时空结构的剖析和对相关岩浆、沉积及变质作用记录的分析，认为昌宁-孟连结合带内共存原特提斯与古特提斯洋壳残余，临沧-勐海一带发育一条早古生代岩浆弧带，前人所划基底岩系"澜沧岩群"应为昌宁-孟连特提斯洋东向俯冲消减形成的早古生代构造增生杂岩，滇西地区榴辉岩带很可能代表了俯冲增生杂岩带发生了深俯冲，由于弧-陆碰撞而迅速折返就位，这一系列新资料及新认识表明昌宁-孟连结合带所代表的特提斯洋在早古生代至晚古生代很可能是一个连续演化的大洋.在此基础上，结合区域地质资料，构建了三江造山系特提斯洋演化的时空格架及演化历史，认为其经历了早古生代原特提斯大洋扩张、早古生代中晚期-晚古生代特提斯俯冲消减与岛弧带形成、晚二叠世末-早三叠世主碰撞汇聚、晚三叠世晚碰撞造山与盆山转换等阶段. 

Tectonic Evolution of the Changning-Menglian Proto-Paleo Tethys Ocean in the Sanjiang Area,Southwestern China

The tectonic evolution of the Changning-Menglian Tethys, as well as the transformation from Proto-Tethys to Paleo-Tethys, is one of hottest research topics concerning the geology of Qinghai-Tibetan Plateau and adjacent regions. Based on the recent geological findings and our new data, we summarized the geological features of the tectonic units from the Sanjiang orogenic system. Then we investigated the evolution history of the Changning-Menglian Tethys during the Early Paleozoic to Late Paleozoic. In view of the spatio-temporal structure of the different tectonic units, and the associated magmatism, sedimentary and metamorphic records. It is suggested in this study that (1) both crustal remnants of Proto-and Paleo-Tethys retain in the Changning-Menglian suture zone, (2) a magmatic arc belt developed from Lincang to Menghai in the Early Paleozoic, (3) the 'Lancang rock Group' was not the basement rock series, but Early Paleozoic tectonic-accretionary complexes formed by the eastward subduction of the Changning-Menglian Tethys Ocean, (4) the eclogite belt in western Yunnan might be the production of rapid exhumation after the deep subduction process of the accretionary complex during the arc-continent collision process. All new lines of evidence suggest that the Changning-Menglian Tethys probably was a continuous ocean from Early Paleozoic to Late Paleozoic. Combined the new findings with the regional geological data, the preliminary temporal-spatial framework and evolution process of the Sanjiang Tethys orogenic system are established, which mainly includes the following four stages:(1) Longmucuo-Shuanghu-Changning-Menglian proto-Tethys seafloor spreading in the Early Paleozoic, (2) the Tethys subduction and formation of the island arc belt from middle-late Early Paleozoic to Late Paleozoic, (3) the convergence and main collision processes from the end of Late Permian to Early Triassic, and (4) the late-collision orogeny and basin-mountain transition in the Late Triassic.