Assessment of lake-level variations to decipher geological controlling factors and depositional architecture of Lake Fuxian, Yunnan Plateau: preliminary insights from geophysical data

Abstract

Lake Fuxian is one of the deepest tectonic plateau freshwater lakes in the southeastern Tibetan Plateau, China. However, questions such as how old the lake is, how deep the total sedimentary thickness sequences are, and what landscape of the lake basin settings and geological structures are unknown. Here, based on fifteen seismic reflection profiles, we applied seismic facies and seismic sequence stratigraphic analyses to interpret the lake sequences. The results of the seismic response reveal that the maximum thickness of the sedimentation is ca. 1238 m and lies toward the NNE region of the lake basin on the L10-2 survey line. Lake sediments can be categorized into five seismic sequences and six seismic horizons. The oldest clinoforms in the deepest sequence (Sq-5) show that the depositional center was shifted to ~ 19 km from the NNE region to the SSW modern location and was ~ 930 m lower than the current lake floor. Multiple and complex tectonic activities strongly impacted on the lake basin, and a series of normal faults created an overall crustal extensional regime, resulting in the formation of many horst and graben structures.