Tectono-thermal evolution and its relationship with petroleum generation in the Chuxiong Basin, southeastern Tibetan Plateau

The southeastern Tibetan Plateau is one of the most tectonically active and rapidly deforming regions of continental crust in the world. Chuxiong Basin is an important Mesozoic petroliferous superimposed basin in the southeastern Tibetan Plateau, which has experienced complex evolution history and strong later transformations. However, the tectono-thermal evolution has not been well evaluated. The reconstruction of the tectono-thermal evolution history in the Chuxiong Basin is of significant important for evaluating its potential for oil and gas exploration and understanding the tectonic deformation process of the southeastern Tibetan Plateau. In this study,we systemically collected the fission track samples from the entire Chuxiong Basin and studied the uplift process of the basin. Combined with the measurement of vitrinite reflectance and inclusion homogenization temperature, we systematically reconstructed the tectono-thermal evolution of the Chuxiong Basin. The results show that the fission track cooling ages close to the Ailaoshan-Red River Fault Zone range from 41.9 Ma to 72.7 Ma in the west of the Chuxiong Fault,mainly belong to Eocene with ages range from 41.9 Ma to 55.5 Ma. The fission track cooling ages in the east of the Chuxiong Fault range from 20.0 Ma to 38.4 Ma,mainly belong to Oligocene-Early Miocene. We suggest the western part of the basin was lifted in the Eocene followed by the uplift of the eastern part in the Oligocene-Early Miocene, which was characterized by early west and late east. The main part of the basin experienced a rapid uplift cooling process since 20-38.4 Ma. The Triassic strata experienced a high degree of thermal evolution,and their abnormal high vitrinite reflectance values are closely related to igneous rock activity. The modeled thermal evolution shows that the maximum paleotemperature for the Triassic strata was reached before the Pliocene, and the maximum paleotemperature gradient reached up to 30 degrees C center dot km(-1) The Triassic hydrocarbon source rocks began to generate hydrocarbons in the Jurassic, and the main hydrocarbon generation peaked in the Cretaceous. The hydrocarbon source rock reached over-mature dry gas generation stage during the Paleocene-Eocene period, and experienced reduced hydrocarbon generation since the Oligocene coupled with the uplift and cooling of the basin. The tectono-thermal evolution of the Chuxiong Basin is closely related to the igneous rock activity, the collision of the Indian and Eurasian plates and the activities of the Ailaoshan-Red River Fault Zone.