Dust supply to the West Philippine Sea since the Middle Pleistocene and distinct influences of the Westerlies after the Mid-Brunhes Event

Abstract

One of the long-standing debates focuses on whether iron (Fe) fertilization enhanced ocean productivity and fueled the biological carbon pump, contributing to glacial CO₂ drawdown. To date, dust flux has been a primary focus, while two other factors, namely dust source and transportation, are generally ignored. In this study, we report high-resolution dust records retrieved from rare earth element variabilities of a sediment core in the West Philippine Sea and discuss the potential linkage between our dust records and driving forces over the last 900 ka. We find an anti-phase relationship between the Ce-based dust record and the Ba-based productivity, both of which are characterized by three astronomical rhythms. By comparing our dust records with various wind proxies, we find that dust input in the study area is closely related to changes in the Westerlies and the East Asian Winter Monsoon, and the Westerlies became the dominant factor after the Mid-Brunhes Event (MBE). Along with the local minimum of obliquity, changes in dust input and ocean productivity are synchronously intensified during the post-MEB glacial periods. Together with comparisons to dust source changes in the inner Asia, we speculate that the strengthening and southward migration of the Westerlies may strengthen the influence of dust sources on marine productivity.