末次冰消期以来冲绳海槽深水氧化性与通风演化研究进展与展望

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

过去二十年,末次冰消期以来冲绳海槽深层水沉积氧化性与通风演化、碳埋藏与释放等研究一直备受关注。尽管目前该研究方向已开展了大量的工作,但由于多种替代指标的复杂性和局限性,与冲绳海槽黑潮动力学相关的深水环流和沉积氧化还原研究目前仍然存在较大争议。本文系统总结了末次冰消期以来冲绳海槽深层水沉积氧化性与通风演化的研究进展,发现高有机质沉降通量和高古生产力是末次盛冰期(LGM)至冰消期期间冲绳海槽深层水缺氧的主要原因;Younger Drays(YD)和Heinrich Stadial 1(HS1)事件期间深水通风增强、含氧量增加与北太平洋中层水(NPIW)强化和侵入有关;早全新世以来黑潮加强引发的深水通风抵消了上升流驱动的生产力提高的影响,使得冲绳海槽深层水处于氧化状态。最后提出未来冲绳海槽古海洋学研究应加强对轨道-千年尺度深层水水源识别与演化示踪、不同气候状态下古生产力与沉积氧化还原耦合关系,以及深层水演化的环境与气候效应等方面的研究。

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.