Apatite fission track analysis of tectono-thermal history in the Xiushui area, southern Songliao Basin

[Objective] The tectono-thermal history of the Cretaceous fault basins in the Songliao peripheral area had not been well explored. The Xiushui basin is a new exploration area with high hydrocarbon potential in the southern part of the Songliao peripheral area. The reconstruction of the burial and thermal history of the Xiushui basin has become an important issue for hydrocarbon exploration in this area.[Methods] Based on five samples from the well LFD1 in the Xiushui Basin, burial and thermal history as well as hydrocarbon source rock evolution history of the Xiushui basin were studied using apatite fission track methods.[Results] The results show that the Xiushui basin reached its maximum burial depth in the late Early Cretaceous, and then uplift continued and denudated about 2000m. The terrestrial heat flow value increased linearly with time during the initial subsidence period, reaching the maximum value of about 100.5 mW/m² at about 120Ma, and then experienced a three-stage cooling process, i.e., rapid cooling, then slow cooling, and finally rapid cooling. The heat flow pattern is similar to and comparable with the adjacent Zhangqiang Depression and the Songliao Basin.[Conclusions] The reconstruction results of the burial and thermal history of the well LFD1 indicate that the hydrocarbon source rocks of the third member of the Yixian Formation entered the oil generation window around 90 Ma, and thereafter, due to the uplift and cooling of the formation, the thermal evolution of the source rock ceased, thus remain unchanged to date.