Sedimentology and sequence stratigraphy of strike-slip fault-controlled continental lakes: Insights from the SW Qaidam Basin, NE Tibetan Plateau

Abstract

Cenozoic sedimentary archives are of great importance for understanding the tectono-climatic evolution of the northeastern Tibetan Plateau. Here, we integrate a detailed field investigation, microscopic observations, unmanned aerial vehicle 3D models, seismic profiles, and transgressive-regressive sequence (T-R sequence) stratigraphy to elucidate the sedimentary and sequence stratigraphy evolution of the SW Qaidam Basin. Three second-order sequences (SS1, SS2, and SS3) were identified based on the unmanned aerial vehicle 3D models and seismic profiles, along with their corresponding underfilled, balanced-filled, and overfilled lake basins. The infilling processes of SS1 and SS2 were significantly influenced by the uplift and strike-slip of the Altyn Tagh Range, paleoclimate variations, and fluctuations of the proto-Paratethys Sea, whereas SS3 was primarily controlled by the intensified uplift and strike-slip of the Altyn Tagh Range. The Altyn Tagh Range experienced multiple stages of uplift, with the incipient strike-slip motion occurring before the Oligocene epoch. Microbialites that formed during periods of relatively high lake level within regressive systems tract act as markers for the maximum regressive surface. Additionally, we propose that these microbialites demonstrate paleoclimate transitions, particularly the climatic shift towards wetter conditions in the Oligocene following their deposition. Newly identified Miocene eolian deposits in the SW Qaidam Basin not only indicate an increasing aridification but also present potential as lithological reservoirs for hydrocarbons.