Research progress and prospects on the evolution of deep water oxygenation and ventilation in the Okinawa Trough since the last Deglaciation

The sedimentary oxygenation and evolution of deepwater ventilation, as well as carbon burial and release in the Okinawa Trough have been highly concerned since the last glacial period over the past two decades. Although many researches have been carried out on this research regime, the coupling relationships between redox conditions and deepwater circulations, biological productivity evolutions are still controversial because of the complexity and limitations of multiple alternative proxies. This paper systematically summarizes the research progress on the oxidation and ventilation evolution of deepwater deposition in the Okinawa Trough since the last glacial period. It was found that the high paleoproductivity and organic matter flux were the main reasons for deep water hypoxia in the Okinawa Trough during the LGM to last deglaciation period. The increase in oxygen content and strengthened deepwater ventilation during the HS1 and YD periods may be related to the intrusion of stronger North Pacific Intermediate Water (NPIW). Since the early Holocene, the deepwater ventilation caused by the Kuroshio has offset the impact of the productivity increase driven by the upwelling, making the deepwater oxidized in the Okinawa Trough. We propose that future research on the paleoceanography of the Okinawa Trough should strengthen the identification and evolution tracing of deep water sources on the orbital millennium time scale, the coupling relationship between paleoproductivity and sedimentary redox under different climate states, and the environmental and climatic effects of deep water evolution.