Reconstruction of main types for oceanic plate strata in the subduction-accretionary complex and feature of sequence for each type: an example from the Qinghai-Tibet Tethyan Permian strata

The oceanic plate stratigraphy is a branch of stratigraphy and focuses on the reconstruction of igneous-sedimentary primary sequences in oceanic basins (including oceanic basin, back-arc basin and inter-arc basin).The oceanic plate strata(OPS)are defined as strata including the basement sequence of volcanic rocks formed in between mid-oceanic ridge and trench subduction zone, and the sedimentary cover of sedimentary and volcanic rocks on the oceanic floor. The OPS were transported into a trench system during the closure of an oceanic basin. In the trench system, the OPS were partly subducted into themantle, or partly accumulated between the trench and fore-arc basin by the scraping or bottom-splitting collage, and tectonic reentry, forming a subduction-accretionary complex(SAC) belt or wedge. Therefore, how to reconstruct the sequence of OPS ina SAC belt is now a hot topic in the world. The key for the sequence reconstruction of OPS is to recognize and divide different tectonic settings from the SAC, and to reconstruct the strata sequence for each setting. This paper proposes the scheme of OPS subdivisions in the SAC, taking the Permian Tethyan strata of the Qinghai-Tibet Plateau as an example, and discusses the OPS sequence model.