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

This paper is the result of oil−gas geological survey engineering.

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 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 Xiushui Basin reached its maximum burial depth in the late Early Cretaceous, and then uplift continued and denudated about 2000 m. 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 ~120 Ma, 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 Well LFD1 indicate that the hydrocarbon source rocks of the third member of the Yixian Formation entered the oil generation window at ~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.