History of Asian eolian input to the West Philippine Sea over the last one million years

The eolian component in Pacific Ocean sediments has been recognized as providing a direct link between the continental loess and marine δ18O climate records over orbital timescales since 500 ka. Here we extend this eolian record over the past one million years. We constructed high-resolution clay mineral stratigraphies based on δ18O chronology in sediments from the International Marine Past Global Change (IMAGES) Core MD06-3050 from the West Philippine Sea in order to trace the sources of clay minerals and reconstruct proxy records of past changes in the Asian eolian input to the basin since 1.0 Ma. The clay mineral assemblage in Core MD06-3050 mainly consists of smectite (~ 65%) and illite (~ 25%), with minor kaolinite (~ 5%) and chlorite (~ 5%). Provenance analysis suggests that smectite was derived mainly from the weathering of volcanic rocks on Luzon island, whereas illite, chlorite and kaolinite were mainly transported as eolian dust by the East Asian winter monsoon from central Asia. Illite/smectite values in Core MD06-3050 are generally higher and more variable during glacial periods and lower during interglacials, suggesting that higher eolian input to the West Philippine Sea generally co-varied with East Asian winter monsoon intensity and more aridity in continental Asia since 1.0 Ma. Spectral analysis further reveals the close link between the extent of high-latitude glaciation, East Asian winter monsoon intensity and eolian input to the West Philippine Sea at eccentricity (100 ka), obliquity (41 ka) and precession (23 ka) bands since 1.0 Ma.