The tectonic uplift since the Late Cretaceous and its impact on the preservation of hydrocarbon in southeastern Sichuan Basin, China

Abstract

Tectonic uplift is the most direct manifestation of tectonic activity, and tectonic deformation strength can be quantitatively shown through uplift height and speed. In this study, balanced rebound and oxygen isotope method are adopted to calculate maximum paleoelevation of stratum uplift of southeastern area of Sichuan Basin since Late Cretaceous due to tectonic activities. And based on current surface elevation of the target area, stratum erosion thickness of southeastern Sichuan during this period is calculated, thereby providing technical support for evaluation of the regional oil and gas exploration. Studies have shown that maximum paleoelevation of southeastern Sichuan uplift is gradually increased from NW to SE, which can maximally achieve 3813 m. Denudation quantity from Sichuan Basin to Qiyushang is gradually increased, and region with greater erosion thickness is above 2800 m. Since the Late Cretaceous, southeastern Sichuan stratum uplift makes oil and gas in Dingshan block gradually dissipate. Also, overlying rock unloading results in fault development, early fault activation, and expansion, which further exacerbates destroy of oil and gas reservoir in Dingshan block of southeastern Sichuan, China.