Spatial and temporal provenance variations of the Chinese Loess Plateau over the late Miocene to early Pleistocene: a window into the reorganization of the Yellow River and monsoon activity

The Miocene–Holocene Red Clay, paleosol, and loess sequences composing the Chinese Loess Plateau (CLP) are one of the most complete terrestrial eolian sediment archives on Earth. We present the first large-n detrital zircon U-Pb geochronology dataset for the Miocene–Pliocene sequence from the northeastern CLP. The depositional ages of these samples are like those of other data sets from the central CLP, allowing comparison of spatial-temporal differences. These data show that the CLP had spatially varied provenance over the late Miocene–Pliocene, similar to the Quaternary strata. The data from the northeastern CLP indicate two shifts in dust sourcing around the Miocene-Pliocene and Pliocene-Quaternary boundaries. The shift around the Miocene-Pliocene boundary is consistent with elongation of the proto-Yellow River to incorporate the present-day ‘big bend’—allowing sediment transport to and ultimately through the Yinchuan-Hetao graben. The provenance shift around the Pliocene-Quaternary boundary is consistent with increased sediment contributions from the Lüliang Shan and the Cretaceous strata overlying the North China Craton. These interpretations challenge assertions linking eolian sediment accumulation on the CLP over the late Miocene–Pliocene primarily to aridification within the continental interior of eastern Asia, but rather point to the importance of riverine transport, catchment reorganization, sediment storage, and increased climatic fluctuations.