The effect of Emeishan supper mantle plume to the thermal evolution of source rocks in the Sichuan basin

Both the structural evolution and thermal history of the Sichuan Basin are closely related to the Emeishan Supper Mantle Plume (ESMP). The ESMP played an important role on the thermal evolution of the source rocks in the Sichuan basin. On this basis of the thermal history of the Sichuan basin, reconstructed based on vitrinite reflectance (R-o) from boreholes in the basin using a paleo-heat flow method, the effect of the ESMP to the evolution of the Paleozoic source rocks is studied. The results show that in the southwestern Sichuan Basin (the central of the ESMP) the evolution of organic matter of the Paleozoic source rocks, which became mature in middle I-ate Permian, was strongly affected by the ESMP. In more detail, in the region close to the ESMP (southwestern Sichuan Basin), the source rocks of lower Permian was heated to peak maturity (maximum R-o>3%) at around 260 Ma (from the beginning of the Late Paleozoic to the end of the early Permian) and later there was no secondary hydrocarbon generation. However, in the regions (northeastern Sichuan Basin) far away from the ESMP, secondary hydrocarbon generation of the source rocks existed. The thermal evolution of the Mesozoic source rocks was related with Mesozoic foreland basin evolution-regional denudation and burial history of the basin, rather than the ESMP. Therefore expect the regions far away from the ESMP; the prospect of oil and gas sourced from Paleozoic source rocks is unfavorable in the regions close to the ESMP.