Reconstructed ocean plate stratigraphy sequences from the Permian subduction-accretionary complex in the Qinghai-Tibet Plateau

Abstract

The Permian Tethys subduction-accretionary complex (SAC) in the Qinghai-Tibet Plateau (QTP) is distributed in six geotectonic provinces, which are known as the Zongwulong-Ganjia, the Western Kunlun, the Eastern Kunlun, the Ganzi-Litang, the Xijinwulan-Jinshajiang-Ailaoshan and the Longmucuo-Shuanghu-Nujiang from north to south. The SAC is a set of mélange generated by subduction of oceanic crust at trenches, which consists of relics from mid-ocean ridge, abyssal plains, oceanic island-seamounts, intra-oceanic arcs and trench turbidites. In this paper, we apply the ocean plate stratigraphy (OPS) theory to reconstruct the OPS sequence of the Permian SAC in the QTP. We divided the Permian SAC in the QTP into two types, i.e., convergent zone and accretionary zone according to their tectonic environments. Six relics from mid-ocean ridge, five relics from abyssal plain, five relics from seamount, two relics from intra-oceanic arc, two relics from fore-arc trench, and seven relics from continental fore-arc trench were recognized and then the OPS sequences from different tectonic environments were reconstructed. The spatial-temporal distributions and evolution of ocean basins during the Permian represented by six SACs are discussed.