Analyses of Sequence Stratigraphy and Environments across Permian-Triassic Boundary in Liaotian, Northwestern Jiangxi Province

摘要

Based on the study of lithology, sedimentology and paleontology at the Permian-Triassic boundary in Liaotian, Northwestern Jiangxi Province, the sequence stratigraphy and depositional environments across the boundary are reconstructed. The top part of the Upper Permian Changxing Formation is composed of very thick-bedded light-colored dolomitic limestone formed in high deposition rate on carbonate ramp, which indacates a transgression systems tract (TST). The Lower Triassic Qinglong Formation shows continuous deposition with the underlying Upper Permian. The lower member of Qinglong Formation consists of calcareous shale, shelly limestome and dolomitic limestone with abundant bivalves (Claraia sp.) and trace fossils (Chondrites). The calcareous shale at the bottom of Lower Triassic indicates a calm deep water environment to form the condensed section (CS). The shelly limestome and dolomitic limestone with shell fossils, intraclast, algal ooide show clean but turbulent environment of carbonate ramp, which produce the deposition of highstand systems tract (TST).