Analysis of Variations in Basin Tectonic Subsidence and Construction of Alternative Models of Basin Thermal Evolution

Abstract—Numerical reconstructions of thermal history of the sedimentary cover in the region of the Dorado North well in the Mannar basin (Sri Lanka) and of the sedimentary blanket of the Ostaninskaya-438 well in the West Siberia Basin (Russia, Tomsk region), which were presented in (Premarathne et al., 2016; Isaev et al., 2021) are compared to the corresponding reconstructions for these areas using the GALO system for basin modeling. These examples show that using basin modeling systems with a given heat flow at the base of the sedimentary cover can produce an unrealistic thermal history of the basin, despite the fact that the calculated vitrinite reflectance matches the measured ones. The analysis of variations in basin tectonic subsidence incorporated in the GALO basin modeling system allows for an assessment of the amplitude and duration of thermal activation or stretching (crustal thinning) of the basin lithosphere. This approach avoids the challenge of setting the heat flow at relatively shallow basin depths. The constrained alternative model of basin thermal evolution, constructed in this way, is based on the same initial modeling database that is used in the basin modeling system with given heat flow at the base of sedimentary blanket; the only difference is the addition of the present Moho depth.