Permian to Triassic provenance record of Paleo-Tethys closure and Paleo-Pacific subduction beneath South China

A number of studies have highlighted how sedimentology and detrital records of sedimentary basins can inform paleogeographic reconstructions by constraining the position, age, temporal and spatial trends, and tectonic setting of the sediment source. A series of Permo-Triassic foreland basins is inferred to have developed along the southern margin of the South China Block, include Youjiang, Shiwandashan and Yong’an basins, from southwest to southeast, respectively. Based on whole rock modal, geochemical data and detrital zircon data, along with paleocurrent data and sedimentary facies indicate that: Triassic sandstones in the Youjiang Basin are mainly derived from southwest Jinshajiang-Ailaoshan suture zone；Yunkai Massif and Hainan Island in the south of the Shiwandashan Basin provide detritus for the Shiwandashan Basin in Permo-Triassic; Permo-Triassic rocks of the Yong’an Basin were derivation from multicomponent, nearby sources with input from both the interior of the South China Block to the northwest and from an inferred arc accretionary complex to the southeast. Integration provenance data of the three basins and combined regional geological data suggest a termination of subduction of the Paleo-Tethys beneath southwest margin of the South China Block and record of continuous subduction of the Paleo-Pacific Ocean along its southeast margin in Permo-Triassic. The Yong’an Basin was a retro-arc foreland basin setting in Permo-Triassic which related to the subduction of the Paleo-Pacific Ocean on southestern margin of the South China Block. The closure of Jinshajiang-Ailaoshan Ocean and subsequence collision of outboard blocks results in that Youjiang and Shiwandashan basins transformed as foreland basin in Late Permian and Middle Triassic, respectively, inferred a diachronous closure of the Paleo-Tethys Ocean and oblique collision of outboard blocks, decreasing from southeast to northwest.