Neodymium isotopic constraints on Cenozoic Asian dust provenance changes linked to the exhumation history of the northern Tibetan Plateau and the Central Asian Orogenic Belt

Abstract

The arid interior of Asia is the largest source of dust deposited in the North Pacific Ocean, and some dust is even transported to Greenland. Investigating the provenance history of Asian dust can provide strong constraints on the evolution of topography and climate in the Asian interior. Eolian dust Nd isotopic records preserved in North Pacific Ocean sediments since ∼40 Ma provide a spatially integrated first-order constraint on the provenance changes of Asian dust. However, a lack of similarly long dust Nd isotopic records from Asian dust source areas, namely, the northern Tibetan Plateau and the Central Asian Orogenic Belt, has hindered a full understanding of Asian dust provenance changes linked to the Cenozoic evolution of tectonics, climate and topography in inland Asia. Here, we have constructed the first fine-grained and whole-rock Nd isotopic records from sediments deposited on the northern Tibetan Plateau since ∼52 Ma. The results indicate two major changes, a gradual increase in εNd(0) values between ∼42 Ma and ∼25 Ma and a general decrease since ∼25 Ma, which were probably caused by the incremental northward growth of the Tibetan Plateau. Further mass balance estimates based on comparisons between the Nd isotopic characteristics of dust from the northern Tibetan Plateau and the North Pacific Ocean indicate that a rapid increase in the contribution of the Central Asian Orogenic Belt to Asian dust at ∼25 Ma can be closely linked to rapid exhumation caused by tectonic uplift and aridification in inland Asia. Our provenance analyses, together with the onset of eolian sediment in central and eastern Asia, suggest that a modern-like regime promoting Asian dust emissions and transport might have been in place since the late Oligocene.