Tracing sediment sources in the western Philippine Sea since 143 ka with Sr and Nd isotopes

Tracing the sources and transport pathways of marine sediments provides criticle insights into regional atmospheric and oceanic circulation patterns. Strontium (Sr) and neodymium (Nd) isotopes proxies, when applied to thick and well-dated marine sediment cores, offer a powerful tool for evaluating regional climate dynamics over glacial-interglacial cycles. In this study, we present 13 paired Sr and Nd isotope records for each of two size fractions of lithogenic sediments spanning the past 143 ka, collected from the Benham Rise in the western Philippine Sea. Our goal is to assess the contributions of Asian dust and Southeast Asian volcanogenic sediments under varying global climate conditions. Preliminary results indicate distinct isotopic signatures between size fractions. Volcanogenic Sr isotopic ratios (⁸⁷Sr/⁸⁶Sr = 0.705 to 0.707) were found in sediment grain size >20 μm, while more radiogenic strontium isotope signatures (⁸⁷Sr/⁸⁶Sr = 0.709 to 0.711) were found in sediments in the 2–20 μm fraction. The differences in Sr isotopic signatures between size fractions may partly result from the size effect. Coupled with ε_Nd values, although with some fluctuations, we found shifts in sediment sources over the past 134 ka, indicating decreased contributions of Asian dust source towards the Las Interglacial Highstand. These findings contribute to a deeper understanding of sedimentary processes and environmental shifts in the western Pacific region, offering new perspectives on regional climate.

 

Keywords: Strontium and neodymium isotopes; Marine sediments; source and transport pathways, Last glacial-interglacial cycle