Long eccentricity forcing Asian dust input into the northwestern Pacific during the early Pleistocene

Asian dust deposition in the northwestern Pacific is generally linked to high-latitude paleoclimate evolution during the Quaternary. However, whether low-latitude tropical Pacific processes, such as El Nino-Southern Oscillation (ENSO), influence Asian dust input into the northwestern Pacific remains uncertain. Here, we present clear periodic variations in potassium content (K (wt%)) and gamma-ray attenuation (GRA) bulk density, which are closely linked to the variations in Asian dust, in a sediment core recovered at Site U1438 in the Amami Sankaku Basin (ASB), northwestern Philippine Sea. Based on the shipboard age-depth model, we tuned the GRA to the mass accumulation rate curve on the Chinese Loess Plateau and the 8-kyr-lagged obliquity curve, and established the astronomical timescale. The K (wt%) content and GRA were higher during glacials and lower during interglacials, as driven by the variability in the Northern Hemisphere ice sheet (NHIS) during the Quaternary. In addition, strong long eccentricity 405-kyr cycles were observed in the dust records (K (wt%) content and GRA) during the early Pleistocene. The 405-kyr filter results showed that increased (decreased) Asian dust corresponded to the La Nina-like (El Nino-like) state, suggesting that Asian dust input into the northwestern Pacific was modulated by ENSO on 405-kyr cycles in the early Pleistocene. Our study illustrated the possible link between long eccentricity 405-kyr cycles in the Asian interior and low-latitude forcing, including potential modulation by ENSO.

Automated summary

This study presents periodic variations in sediment core from the northwestern Philippine Sea, which are linked to Asian dust variations. The study suggests that low-latitude tropical Pacific processes, such as ENSO, may influence Asian dust input into the northwestern Pacific on a 405-kyr cycle during the early Pleistocene.