Geochemical signatures and tectonic setting of the clastic rocks from the Triassic Xikang Group in western Sichuan

The clastic rocks widespread in the Triassic Xikang Group in western Sichuan consist dominantly of turbiditic flysch formations.The geochemical examination of the sandstones and mudstones from the Xikang Group has led us to conclude that the debris are derived mostly from the surficial rocks and their overlying deposits on the Xikang-Yunnan ancient land,and tectonic settings display the transition from the passive continental margin to active continental margin and finally to archipelago.