History of Asian eolian input to the Sea of Japan since 15 Ma: Links to Tibetan uplift or global cooling?

We present high-resolution analyses of clay mineral assemblages combined with analysis of Sr-Nd-Pb isotopic compositions of the <2 mu m silicate fraction of sediments from Integrated Ocean Drilling Program (IODP) Site U1430 in the southern Sea of Japan, in order to trace the sources of clay minerals and reconstruct proxy records of past changes in Asian eolian input to the basin since 15 Ma. The clay mineral assemblages at IODP Site U1430 mainly consist of smectite (similar to 51%) and illite (similar to 36%), with minor kaolinite (similar to 7%) and chlorite (similar to 6%). Provenance analysis suggests that the fine-grained sediment at the study site is a two end-member mixture of eolian dust from Central Asia and fluvial input from the Japanese islands. The Central Asian end member supplied illite-rich and high Sr-87/Sr-86 and low epsilon Nd(0) eolian dust to the study site by wind, while the Japanese end member, characterized by young volcanic rocks, contributed smectite-rich, low 87Sr/86Sr and high sNd(0) weathering products via rivers. The ratio of illite/smectite and epsilon Nd(0) values of clay-sized silicate sediments at Site U1430 were used as proxies for tracing the changing strength of central Asian eolian input to the Sea of Japan, and thus reconstruct the aridification history of its source region. Our study presents for the first time a continuous, high resolution record that highlights the four-step drying of Central Asia that occurred at similar to 11.8 Ma, 8 Ma, 3.5 Ma and 1.2 Ma. Considered the nature and timing of major climatic and tectonic events in Asia, we conclude that the strengthened aridification of Central Asia starting at similar to 11.8 Ma was possibly driven by the combined effect of Tibetan surface uplift and global cooling, whereas the rapid drying at similar to 8 Ma was caused primarily by the uplift of the northern Tibetan Plateau. In contrast, global cooling, overwhelming the influence of Tibetan Plateau uplift, has become the primary control on Central Asia aridification since similar to 3.5 Ma. (C) 2017 Elsevier B.V. All rights reserved.