塔里木地块与古亚洲/特提斯构造体系的对接

Paleo-Asian and Tethyan tectonic systems with docking the Tarim block

塔里木盆地为环形山链所环绕,北缘为古亚洲体系的天山弧形山链,南缘为特提斯体系的西昆仑-阿尔金弧形山链。自新元古代晚期以来,塔里木地块及周缘地区经历了古亚洲洋盆和特提斯洋盆的开启、俯冲、闭合以及微陆块多次碰撞造山,发生多期的构造、岩浆及成矿作用。特别是受印度/亚洲碰撞(60～50Ma)以来的近程效应和远程效应影响,使塔里木盆地周缘发生强烈的隆升、缩短及走滑变形,形成了现今复杂的环型造山系,完成了古亚洲体系和特提斯体系与塔里木地块的最终对接。塔里木地块与周缘两大构造体系的焊接是从早古生代开始的。研究表明,早古生代末期塔里木已与西昆仑-阿尔金始特提斯造山系链接一起。此时,塔里木地块东段与中天山增生弧地体碰撞,而西段在晚古生代与中天山增生弧地体碰撞。塔里木盆地周缘早古生代造山系中存在早古生代中期和早古生代晚期的两次造山事件,致使塔里木盆地内映现两个早古生代构造不整合面:晚奥陶世-志留纪之间的角度不整合和中晚泥盆世与早古生代之间的角度不整合。塔里木盆地早古生代的古地理、古环境和古构造研究表明,塔里木早古生代台地位于盆地的中西部,盆地东部为陆缘斜坡和深海/半深海沉积盆地,与南天山早古生代被动陆缘链接。印度/亚洲碰撞导致塔里木盆地西南缘的喜马拉雅西构造结的形成与不断推进,使特提斯构造体系与古亚洲构造体系在西构造结处靠拢及对接,终使塔里木盆地最后定型。

The Tarim basin is surrounded by the curved Tianshan Mountain of the Paleo-Asian system to the north and curved West Kunlun-Altun Mountains of the Tethys system to the south.Since the Late Neoproterozoic,the surrounding areas of the Tarim block have experienced opening,subduction and closure of the Tethys ocean basin to the south and the Paleo-Asian oceanic basin to the north,as well as multi-collision orogenies between different microterrains.In particular,the long-distance and short-distance effects of the India/Asia collision （since 60~50Ma） caused a strong uplift,shortening and strike-slip deformation in the surrounding areas of the Tarim basin,forming a ring orogenic system,and finally resulting in docking of the Tarim block to the Pale-Asian system and the Tethys system.The welding of the Pale-Asian system and the Tethys system to the Tarim block began in the Early Paleozoic.The Tarim block has been linked with the West Kunlun-Altun Tethyan orogenic system at the end of Early Paleozoic.During the Late Paleozoic,the eastern Tarim block was collided with the central Tianshan arc terrane to the north,while the western Tarim block was collided with the central Tianshan arc terrane in the Late Paleozoic.Two orogenic events,i.e.Early-Middle Paleozoic and Late Paleozoic events are recognized around the Tarim basin,which resulting in two tectonic unconformities in the Tarim basin during the Early Paleozoic time： One is between Late Ordovician/Silurian and another is between Late Devonian and Early Paleozoic.The palaeogeographic,palaeoenvironmental and palaeotectonic data indicate that the Tarim platform lied in the central and western parts in the Early Paleozoic,continental margin slope and deep or semi-deep sea facies sedimentary basin in the eastern part,which was linked with the Early Paleozoic passive continental margin in the south Tianshan.The India/Asia collision led to formation of the West Himalayan Syntaxis in the southwestern margin of the Tarim basin,and docking of the Tarim block to Tethyan and Paleo-Asian systems.