A study on the sedimentary environment of the Denglouku Formation in the paleo-central uplift, Songliao Basin, China: constraints from clastic rock geochemistry

The Denglouku Formation in the paleo-central uplift of the Songliao Basin is a large thick clastic deposit that has important oil and gas exploration potential. However, the natural gas in the Denglouku Formation has not yet formed to the necessary scale. The paleo-sedimentary environment plays an important role in controlling the development of source rocks and the physical properties, development, and distribution of reservoirs. Therefore, studying the paleo-sedimentary environment has important guiding significance for the formation and accumulation of oil and gas. In addition, studying the paleo-sedimentary environment of the Denglouku Formation can effectively reconstruct the terrestrial climate change in the Cretaceous and provide basic terrestrial geological data for studying the global Cretaceous paleoclimate, paleoenvironmental changes, and greenhouse climate. This paper uses clastic rock geochemistry, especially V/Cr, V/(V + Ni), Sr/Cu, SiO2/Al2O3, and Sr/Ba ratios and DF1, DF2, as well as other characteristic values and discriminations, to confirm that the depositional environment gradually changed from an oxygen-poor or reducing environment in the center to an oxygen-rich environment on the north and south sides; the climate in the north was drier and hotter than that in the south, and the humid climate in the south led to strong chemical weathering. There was a tendency to gradually evolve from a marine to transitional to freshwater environment from north to south. The source area was an active continental margin and a continental arc. © 2021, Saudi Society for Geosciences.