Spatial distribution of Upper Cretaceous red beds in the West Qinling Mountains on the northeastern margin of the Tibetan Plateau uplift and its geological constraints

Based on the research on sedimentary characteristics of Upper Cretaceous red bed strata in the West Qinling Mountains and its spatial elevation distribution analysis, this paper discusses possible tectonic geomorphology of the West Qinling Mountains in Late Cretaceous and spatial variation of crustal uplift in the West Qinling Mountains since Cenozoic. The following opinions are sug-gested:①According to existence of middle-fine grained red sandstones with aeolian sandstone features on the bottom of alluvial-allu-vial gravel layers and appearance of upmost mudstone and muddy siltstone with lake facies sedimentation characteristics in the Upper Cretaceous red bed strata in the West Qinling Mountains, in combination with their present distribution on the different river water-shed summit surfaces and similar elevation distributions between two sides of Tanchang-Minxian-Lintan faulted zone and north mar-gin fault of West Qinling Mountains, it is believed that no matter how West Qinling Mountains experienced geological evolution his-tory before Late Cretaceous period, West Qinling Mountains had the overall stability characterized by ancient tectonic geomorpholo-