Paleo-Heat Flow Anomaly at the End of Middle Permian in NE Sichuan Basin, SW China: Did an Ocean Trough Exist?

It is an issue whether the Kaijiang-Liangping area (in the northeastern Sichuan Basin, SW China) was a controversial ocean trough during Changxing age in the late Permian-early Triassic. Some vitrinite reflectance (Ro) profiles from wells in the northeastern Sichuan Basin show obvious breaks, and the breaks are coincident with the boundary between the middle Permian and late Permian. Based on the Ro data, the heat flow history in the northeastern Sichuan Basin was reconstructed. The result shows that the heat flow reached its peak value at the end of middle Permian (~260Ma). The spatiotemporal feature of the heat flow evolution is not in agreement with the fact that there was a Kaijiang-Liangping Trough existing in the late-Permian to early Triassic. The palaeo-heat flow anomaly was, in fact, a response to the igneous activity in late middle Permian.