塔里木北部周缘前陆盆地早二叠世快速迁移与沉积相突变:俯冲板片拆沉的响应

塔里木北部周缘前陆盆地发育于泥盆纪末至早三叠世期间,完整地记录了南天山造山带的发育过程。该盆地在早二叠世由复理石盆地转化为磨拉石盆地,同时发生快速南移。同期幔源物质加入,有山根地壳熔融的岩浆活动、南天山造山带的整体隆升、热液成矿作用集中发育和变形、变质作用的激化使俯冲岩片的拆沉成为盆地转化与迁移的最佳机制。相同的转化过程及深部机制在其他造山带中也明显存在,表明俯冲岩片拆沉是造山作用一个不可或缺的环节。

Early Permian Flysch to Molasse Transition and a Quick Migration of North Tarim Peripheral Foreland Basin:Response to Subducted Slab Breakoff

North Tarim peripheral foreland basin, developed from early Carboniferous to early Triassic, recorded the development course of South Tian shan orogenic belt. This basin transited from flysch to molasse, and migrated southward for a long distance at the end of early Permian. Moreover, at the same time, magmatic activity forming the igneous rock with no Eu-anormaly and mantle materials, whole uplift ofSouth Tian shan orogenic belt, hydrothermal deposits, and intensive metamorphism. and deformation took place simultaneously. The coincidence of these geologic events suggests they are all related to a same geologic mechanism; subducted slab breakoff. So, it is thought that the flysch to molasse transition of North Tarim foreland basin may be one response to slab breakoff. Many other orogens, such as Qinghai and Tibet orogen, all exhibited those characteristics, suggesting that slab breakoff may be an integral part in orogenic movement.