The Coupling of Sedimentary Characteristics and Tectonic Development of Turpan-Hami Basin and Adjacent Areas in Early Permian

Abstract

Great changes took place in geological structure and geomorphology of Xinjiang area during the Late Permian. The Early Permian marks an important tectonic transition in the Tianshan region of northwestern China between Carboniferous continental amalgamation and recurrent Mesozoic-Cenozoic intracontinental orogenic reactivation. The Turpan-Hami Basin accommodated up to 3000m of sediments and is ideally positioned to provide constraints on this transition. It indiates the end of evolution history of the basin basement and the beginning of evolution history of the basin cover. Multi type Late Permian sedimentary sections are found which include marine sediments, continental sediments and alternative facies sediments of marine and continent. Based on the anlysis of different cross sections and wells we suggest that there are three sedimentary facies which are: 1.rift type marine volcanic eruption sedimeatary facies; 2.rift type continental volcanic eruption sedimentary facies; 3.orogenic belt molasse facies. The Lower Permian occurs in the southern Turpan-Hami Basin as continental molasse consisting of conglomerates, glutenite, greywacks, silicalite and bioclastic limestones. The conglomerates are composed of pebbles of volcanics, granite, limestone, marble, silicalite and metamorphic rocks. Lower Permian rocks in the northern and southeastern Turpan-Hami Basin unconformably overlie a Late Carboniferous volcanic arc sequence. These Lower Permian strata include shallow marine carbonate rocks and mafic to felsic volcanic rocks that are in turn overlain by littorol to profundal lacustrine facies. It is considered that there are two types of basins in Turpan-Hami Basin and adjacent area: the foreland basins and the rift basins according to different sedimentary characteristics and structural anlyses. The origin of these two types of basins in continent continent collision zone is also discussed in this paper.