Sediment Provenance of the West Philippine Basin and Its Paleoclimatic Response Over the Past 2 Million Years

To reveal the sediment provenances and its paleoenvironmental implications in the West Philippine Basin since 2 Ma, a systematic analysis was conducted on grain size and clay minerals of sediments in Core PB-23, Core PB-23 was originated from the central part of West Philippine Basin (20°14′51″ N, 131°55′38″ E). On this basis, a high-resolution sedimentary record was established, and alternative indicators that reflecting aridification and eolian dust input in Asia were extracted. The results show that the sediments of Core PB-23 are mainly composed of clay (61%~62.8%) and silt. And the sand content is extremely low, indicating the characteristics of fine-grained terrigenous sedimention, namely eolian dust from the Asian continent and volcanic materials from adjacent island arcs, and the first end-member is dominant. In addition, the coupling fluctuations of grain size with clay minerals. The clay minerals are mainly illite (32%~98%, averaging 85%), followed by kaolinite (1%~52%, averaging 9%), chlorite (1%~22%, averaging 3%), and smectite (1%~29%, averaging 3%). The crystallinity and chemical index of illite show little change, while the content of clay minerals varies significantly between different layers. The illite content reaches its peak in the 244~350 cm layer (averaging 93.9%), while the contents of kaolinite, smectite, and chlorite are the lowest. The grain size and clay mineral content of the 0~244 cm layer are the highest, demonstrating that during this stage, the sedimentary environment responds most sensitively to climate change. The results also indicate that the sediment provenances of core PB-23 in the West Philippine Basin are mainly composed of two end-members, reveal that the intensification of the East Asian winter monsoon during glacial-interglacial cycles since 0.7 Ma lead to a significant increase in continental eolian dust input, and simultaneously corroborate that the Mid-Pleistocene Climate Transition(MPT) during 1.2~0.8 Ma causes the intensification of Asian aridification.