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 ( 87 Sr/ 86 Sr and ε Nd ), together with the clay mineral composition, of eolian dust preserved in a sediment core obtained from the Philippine Sea (12°30′N, 134°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.

Quantitative estimates of Asian dust input to the western Philippine Sea in the mid‐late Quaternary and its potential significance for paleoenvironment

“…[]; PC 631 from Seo et al . []; ODP Site 806 from Winckler et al . []; ODP Site 807 from Zhang et al .…”

“…Sr‐Nd isotopes, rare earth element, and clay mineralogy have been proven to be powerful proxies for characterizing Asian dust input to the Pacific, especially at semiquantitative [e.g., Wan et al ., ; Xu et al ., ] or even quantitative levels [ Jiang et al ., ; Seo et al ., ; Serno et al ., ; Xu et al ., ]. Of these proxies, Sr‐Nd isotopes give the best resolution on sediment provenance [ Jiang et al ., ; Seo et al ., ; Serno et al ., ].…”

“…[] and Seo et al . [] have quantified Asian dust contributions to the western and central Philippine Sea but either had no age control or only 16 samples spanning the past 600 ka, respectively. Xu et al .…”

“…Because eolian dust is a substantial source of iron, changes in dust input have the potential to affect the ecosystem structure and carbon cycle in this iron and silicon‐limited region [ Winckler et al ., ; Murray et al ., ; Xiong et al ., ]. As the second largest dust source area on Earth, Asia contributes abundant eolian dust southeastward to the Chinese Loess Plateau [e.g., Porter and An , ], northwestern Pacific [e.g., Rea and Leinen , ; Nagashima et al ., ], and tropical western Pacific [ Winckler et al ., ], including the western Philippine Sea [ Wan et al ., ; Xu et al ., ; Jiang et al ., ], through the East Asian winter monsoon winds [ Clift and Plumb , ; Shao et al ., ] and/or the Westerlies [ Seo et al ., ]. Therefore, eolian dust originating from Asia may have a significant influence on continental and marine sedimentation, as well as climate at a global scale [e.g., Rea and Leinen , ; Porter and An , ; Jickells et al ., ; Tanaka and Chiba , ; Winckler et al ., ; Shao et al ., ].…”

“…Sr‐Nd isotopes, rare earth element, and clay mineralogy have been proven to be powerful proxies for characterizing Asian dust input to the Pacific, especially at semiquantitative [e.g., Wan et al ., ; Xu et al ., ] or even quantitative levels [ Jiang et al ., ; Seo et al ., ; Serno et al ., ; Xu et al ., ]. Of these proxies, Sr‐Nd isotopes give the best resolution on sediment provenance [ Jiang et al ., ; Seo et al ., ; Serno et al ., ]. The differences between benthic and planktonic foraminiferal carbon isotope values and total organic carbon (TOC) content, as well as planktonic foraminiferal assemblages, are commonly used to quantitatively reconstruct marine export productivity and the DOT in the tropical Pacific, respectively [ Andreasen and Ravelo , ; Kawahata et al ., ; Zhang et al ., ; Xiong et al ., ; Tang et al ., ].…”