The study on the modern sedimentary system of Buha River Delta in Qinghai Lake

摘要

Qinghai Lake forming in the Miocene is the largest faulted brackish lake in China. Different researchers conducted comprehensive study via multidisciplinary methods between 1960 and 1970, but modern sedimentary researchers mostly focus on a single facies instead of trying to systemically understand the sedimentary systems of Qinghai Lake and its surrounding areas. Based on observation of outcrop and bathymetry, remote sensing imagery, and meteorological data, the combined research of the modern sedimentary systems in Buha River of Qinghai Lake is conducted, assisted by mechanical analysis and geochemical test. The theory of "source-to-sink" system is presented in this study. Based on sedimentary facies analysis in single sites and linear "source-to-sink" sedimentary system are well built. The delta of Buha River develops underwater distributary, underwater natural levee, mouth bar, sheet sand, and delta front slope. The control factors of Buha River Delta sedimentary systems include provenance lithology, topography, drainage, vegetational species, plant coverage, wave, coastal current, and lake level fluctuation.