Aridification of northwest Australia and nutrient decline in the Timor Sea during the 40 kyr world

Abstract

Studying tropical hydroclimate and productivity change in the past is critical for understanding global climate dynamics. Northwest Australia is an ideal location for investigating Australian monsoon dynamics, the variability of the Indonesian Throughflow (ITF), and their impact on past productivity and warm pool evolution, which remain poorly understood during the 40 kyr world in the mid-early Pleistocene. In this study, we present multi-proxy records from International Ocean Discovery Program (IODP) Site U1483 in the Timor Sea spanning the last 2000 ka, including orbitally-resolved records from the 40 kyr world between 2000 and 1300 ka. Our results suggest that northwest Australia underwent a step of increased aridification and that productivity in the Timor Sea declined during the transition from ~ 1700 to ~ 1400 ka. We attribute this aridification to the reduced moisture supply to this region caused by the ITF restriction and warm pool contraction. We ascribe the declined productivity to a decrease in the nutrient supply of the Pacific source water associated with global nutrient redistribution. At orbital timescale, multiple mechanisms, including sea level changes, monsoon, and the Intertropical Convergence Zone (ITCZ) dynamics, and variations in the ITF and Walker circulation could control variations of productivity and terrigenous input in the Timor Sea during the 40 kyr world. Our bulk nitrogen and benthic carbon isotope records suggest a strong coupling to biogeochemical changes in the Pacific during this period. This research contributes to a better understanding of tropical hydroclimate and productivity changes during the 40 kyr world.

Aridification of Northwest Australia and Nutrient Decline in the Timor Sea During the 40 Kyr World

“…wuellerstorfi and C . mundulus were rare or absent (Zhang et al., 2023). The external standard error is better than ±0.08‰ for δ 18 O and ±0.05‰ for δ 13 C based on international standards.…”

“…The Prahl and Wakeham (1987) calibration was applied to the $${\mathrm{U}}_{37}^{{\mathrm{K}}^{\prime }}$$—based SST, which exhibits same features and trend as using Müller et al. (1998) calibration (Zhang et al., 2023). The Schouten et al.…”

“…Data associated with this study are archived at National Oceanic and Atmospheric Administration (NOAA) (Zhang et al., 2023).…”