Orbital and sea-level changes regulate the iron-associated sediment supplies from Papua New Guinea to the equatorial Pacific
Orbital and sea-level changes regulate the iron-associated sediment supplies from Papua New Guinea to the equatorial Pacific
复制标题
轨道和海平面变化调节从巴布亚新几内亚到赤道太平洋的铁相关沉积物供应
DOI：
10.1016/j.quascirev.2020.106361
复制
发表时间：
2020-07-01
影响因子：
4
通讯作者：
Jian, Zhimin
中科院分区：
文献类型：
--
作者：
Dang, Haowen;Wu, Jiawang;Jian, Zhimin
赤道太平洋的铁（Fe）被认为在海洋地球化学循环和相关的海气CO2通量中起着关键作用。以往的研究表明，巴布亚新几内亚（PNG）是西赤道太平洋的主要贡献者。然而，这铁供应的关键问题，包括确切的来源，运输过程和分布范围仍然不清楚，特别是其长期变化与水文气候和古海洋变化。使用一组核心收集离岸的北方巴布亚新几内亚和从Ontong-Java高原（OJP），示出了隐藏沿着的路径的铁交付的暗流，在这里，我们编译高分辨率的记录，探讨如何铁相关的沉积物供应变化和分布在轨道时间尺度在过去的400万年。利用C-14定年、有孔虫三角洲O-18记录和碳酸盐含量的地层对比，建立了这些岩心的年代学格架。巴布亚新几内亚近海地区的沉积铁和粘土矿物蒙皂石显示出显著的岁差周期，与3月S 5度的日射变化相一致。这种岁差优势表明当地降水和河流径流对近海沉积的铁相关的沉积物的控制。对于OJP站点的代理来自陆源碎屑成分给出了一个频谱模式，但是，类似于100万年的周期与次级岁差高点占主导地位。显着的100 ka的周期可以最好地归因于冰川间冰期的变化，海洋运输，可能是由海平面调节的变化的强度和/或路线的沿海暗流关闭巴布亚新几内亚。这种变化可能影响了富铁颗粒从巴布亚新几内亚到OJP的长距离运输，并通过赤道暗流进一步向东。(C)2020爱思唯尔有限公司保留所有权利。
Iron (Fe) supplied to the equatorial Pacific are thought to play a critical role in marine biogeochemical cycle and the related air-sea CO2 flux. Previous studies have shown that Papua New Guinea (PNG) is a major Fe contributor for the western equatorial Pacific. However, key issues of this Fe supply including the exact sources, transport processes and distribution range remain unclear, especially its long-term variability associated with hydroclimatic and paleoceanographic changes. Using a set of cores collected offshore the northern PNG and from the Ontong-Java Plateau (OJP), shown to situate along the pathway of Fe delivery by undercurrents, here we compile high-resolution records to explore how the Fe-associated sediment supplies varied and distributed on orbital time-scale during the past 400 ka. The chronologic frameworks of these cores are established by using C-14 datings and stratigraphic correlations of foraminiferal delta O-18 records and carbonate contents. The sedimentary Fe and clay-mineral smectite in the offshore-PNG sites show a prominent precession cycle, in phase with the March insolation change at 5 degrees S. Such precessional predominance suggests the control of local precipitation and river runoff on the offshore deposition of the Fe-associated sediment. For the OJP sites the proxies derived from terrigenous detrital component give a spectral pattern, however, prevailed by similar to 100-ka cycle with secondary precessional highs. The significant 100-ka cycle can best be attributed to glacial-interglacial changes in oceanic transports, likely caused by sea-level regulated variability in the strength and/or route of the coastal undercurrents off PNG. This variability may have influenced the long-distance transport of Fe-rich particulates from the PNG to the OJP, and further eastwards via the Equatorial Undercurrent. (C) 2020 Elsevier Ltd. All rights reserved.