Dust correlation and oxygen isotope stratigraphy in the Southern Ocean over the last 450 kyrs: An Indian sector perspective
Dust correlation and oxygen isotope stratigraphy in the Southern Ocean over the last 450 kyrs: An Indian sector perspective
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过去 450 公里南大洋的尘埃相关性和氧同位素地层学：印度部门的视角
DOI：
10.1016/j.quascirev.2022.107508
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发表时间：
2022
影响因子：
4
通讯作者：
Kenji Kawamura
中科院分区：
文献类型：
--
作者：
Hiroki Matsui;Minoru Ikehara;Yusuke Suganuma;Osamu Seki;Ikumi Oyabu;Kenji Kawamura
南大洋 (SO) 海洋沉积物岩心的年代学构成了了解 SO 古海洋学的基础，对全球气候具有重大影响。由于钙质有孔虫普遍缺乏，在 SO 中将海洋沉积物核心的氧同位素 (δ18O) 记录调整为 δ18O 堆栈（δ18O 地层学）很困难，因此将海洋沉积物核心的尘埃代理信号调整为冰芯的尘埃记录（尘埃相关）是构建年龄-深度模型的一种有前途的方法。然而，尘埃关联的可靠性尚未确定，特别是在过去~300 kyrs之后，并且此类工作在SO的大西洋和太平洋区域比在印度区域进行得更多。在这里，我们使用岩石磁记录和连续 δ18O 地层学，对过去 ∼410 kyrs 中 SO 印度区的海洋沉积物核心提出了一种新的尘埃关联。 δ18O地层学与尘埃相关性在其年代不确定性内是一致的，支持了后者冰期-间冰期时间尺度年代学的可靠性。然而，尘埃对比产生的年龄通常比 δ18O 地层年龄高出 3 kyrs（410-126 ka 和 84-50 ka）。我们还根据灰尘相关性，编制了过去 450 公里内环南极 SO 的可用灰尘代理记录，以讨论印度区域内以及所有三个区域之间的灰尘代理记录的变化。对于印度区域，相对于海洋锋面的纬度位置明显不同的两个核心之间的海洋同位素阶段 (MIS) 6 尘埃代理信号存在显着差异。 MIS 6 期间亚南极地区因铁施肥而增加的生物磁铁矿产量可能部分解释了两个核心之间的差异。对于环南极 SO，计算了海洋沉积物核心尘埃代理信号与南极冰芯尘埃通量之间的移动相关系数。除 MIS 6 外，冰芯中的高尘埃通量区间具有很强的相关性。虽然较小，但印度扇区的相关性略低于其他扇区，表明当地尘埃源和火山物质的贡献，因此表明在 SO 的印度扇区进行尘埃关联时需要谨慎。
The chronology of Southern Ocean (SO) marine sediment cores forms the basis of understanding the SO paleoceanography, with significant implications for global climate. Because tuning of the oxygen isotope (δ18O) record of a marine sediment core to a δ18O stack (δ18O stratigraphy) is difficult in the SO because of a general paucity of calcareous foraminifera, tuning of the dust proxy signal of a marine sediment core to the dust record of an ice core (dust correlation) is a promising way to construct an age–depth model. However, the reliability of dust correlation has not been established, especially beyond the last ∼300 kyrs, and such work has been performed more in the Atlantic and Pacific sectors of the SO than in the Indian sector. Here we present a new dust correlation using the rock magnetic record, together with continuous δ18O stratigraphy, for a marine sediment core in the Indian sector of the SO over the last ∼410 kyrs. The δ18O stratigraphy is consistent with the dust correlation within their chronological uncertainties, supporting the reliability of the latter chronology for glacial–interglacial timescales. However, the dust correlation often produces older ages than the δ18O stratigraphy by up to 3 kyrs (410–126 ka and 84–50 ka). We additionally compiled, based on dust correlation, available dust proxy records in the circum-Antarctic SO for the last 450 kyrs to discuss variations in the dust proxy record within the Indian sector and between all three sectors. For the Indian sector, there is a marked difference in dust proxy signals for Marine Isotope Stage (MIS) 6 between two cores that have markedly different latitudinal positions relative to the oceanic fronts. Increased biogenic magnetite production by iron fertilization in the Subantarctic Zone during MIS 6 may partly explain the difference between the two cores. For the circum-Antarctic SO, moving correlation coefficients were computed between the marine sediment-core dust proxy signals and the dust flux of an Antarctic ice core. Strong correlation was recognized for intervals of high dust flux in the ice core, except for MIS 6. Although minor, the slightly lower correlation in the Indian sector than in the other sectors indicates a contribution from local dust source and volcanic materials and thus suggests the necessity for caution when performing dust correlation in the Indian sector of the SO.