Sr-Nd isotope composition and clay mineral assemblages in eolian dust from the central Philippine Sea over the last 600 kyr: Implications for the transport mechanism of Asian dust

Abstract

Dust transport to the tropical/subtropical northwestern Pacific over the past 600 kyr was investigated using radiogenic isotopes (Sr-87/Sr-86 and eNd), together with the clay mineral composition, of eolian dust preserved in a sediment core obtained from the Philippine Sea (12 degrees 30'N, 134 degrees 60'E). These data revealed the influence of two prevailing dust sources, namely, the Asian deserts and nearby volcanic arcs (e.g., the Luzon Arc), with average contributions of around 70% and 30%, respectively, from each. The clay mineral composition of the core resembled dust from the central Asian deserts (CADs; e. g., the Taklimakan Desert) as in the north-central Pacific, but published aerosol data collected near the study site during winter/spring have the mineralogical signature of dust originating from the East Asian deserts (EADs). These data indicate that the relative contribution of EAD dust increases with the northeasterly surface winds associated with the East Asian Winter Monsoon (EAWM) during winter/spring, but the Prevailing Westerlies and Trade Winds that carry dust from the CADs is the dominant transport agent in the overall dust budget of the study site. The results of this study contradict the prevailing view that direct dust transport by the EAWM winds in spring dominates the annual flux of eolian dust in the northwest Pacific.