Abstract 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 14C datings and stratigraphic correlations of foraminiferal δ18O 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°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 ∼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.

中文翻译：

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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

摘要 提供给赤道太平洋的铁 (Fe) 被认为在海洋生物地球化学循环和相关的海气 CO2 通量中起关键作用。先前的研究表明，巴布亚新几内亚 (PNG) 是西赤道太平洋的主要铁贡献者。然而，包括确切来源、运输过程和分布范围在内的这种铁供应的关键问题仍不清楚，尤其是其与水文气候和古海洋变化相关的长期变化。使用从 PNG 北部近海和 Ontong-Java 高原 (OJP) 收集的一组岩心，这些岩心显示位于暗流输送 Fe 的路径上，在这里我们编译高分辨率记录，以探索与 Fe 相关的沉积物供应如何变化并分布在过去 400 ka 的轨道时间尺度上。这些岩心的年代框架是通过使用 14C 年代测定和有孔虫 δ18O 记录和碳酸盐含量的地层相关性建立的。离岸 PNG 地点的沉积铁和粘土矿物蒙脱石显示出明显的进动循环，与 5°S 的 3 月日照变化同相。这种岁差优势表明当地降水和河流径流对铁相关沉积物的离岸沉积的控制。对于 OJP 站点，来自陆源碎屑成分的代理给出了光谱模式，然而，以 100-ka 周期为主，具有二次进动高点。显着的 100 ka 周期最好归因于海洋运输的冰期-间冰期变化，可能是由海平面调节的强度和/或巴布亚新几内亚沿岸暗流路线的可变性造成的。这种可变性可能影响了富铁颗粒从 PNG 到 OJP 的长距离传输，并通过赤道暗流进一步向东传输。