Stepwise increased spatial provenance contrast on the Chinese Loess Plateau over late Miocene-Pleistocene

Abstract

AbstractThe Miocene–Holocene dust sequences composing the Chinese Loess Plateau are one of Earth’s most complete terrestrial eolian sediment archives. Here we present a zircon Uranium-Lead geochronology dataset for the eolian sequence from the northeastern plateau and compare the results with those from the central plateau. These data show a trend of increasing spatial provenance contrast from the late Miocene to the Pleistocene. This can be reasonably explained by the late Miocene uplift of the Qilian Shan, Pliocene intensification and increased variations of the Asian summer monsoons, Pleistocene intensification of Northern Hemisphere glaciations, and possible formation of the current Yellow River course. These events changed sediment supply, availability, and wind strength, causing the observed pattern. These interpretations challenge assertions linking dust accumulation on the Loess Plateau primarily to aridification within the Asian interior, but rather point to a confluence of surface processes involving exhumation, monsoon, ice ages, and river reorganization.