No major temporal provenance variation on the Chinese Loess Plateau since the late Miocene — insight from stable heavy mineral ratios

Abstract

Heavy mineral assemblages have been demonstrated effective in tracking the dust provenance younger than 500 ka on the Chinese Loess Plateau (CLP). However, prior to 500 ka, diagenetic alternation has proven to affect the validity of heavy mineral assemblage in indicating loess provenance. In order to circumvent this caveat, here we use several previously-proposed ratios of stable heavy minerals to study the dust provenance on the CLP since the late Miocene. These provenance tracers reveal that dust on the CLP is dominantly sourced from the Northeastern Tibetan Plateau with some input from the North China Craton, without significant changes across the late Miocene-Pliocene to Pliocene-Quaternary boundaries. This result is different from previous results based on Sr, Pb isotopes, and transparent heavy mineral composition, but is consistent with Nd and Hf isotopes and detrital zircon U-Pb age results. We argue that the changes based on Sr, Pb isotopes, and heavy mineral assemblages are caused by factors other than provenance changes. We conclude that the CLP has been sourcing dominantly from the Northeastern Tibetan Plateau since the late Miocene and formation of the CLP is genetically linked with existence of a high plateau near its western margin.