Volcanic iron fertilization of primary productivity at Kerguelen Plateau, Southern Ocean, through the Middle Miocene Climate Transition
Volcanic iron fertilization of primary productivity at Kerguelen Plateau, Southern Ocean, through the Middle Miocene Climate Transition
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DOI：
10.1016/j.palaeo.2014.05.028
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发表时间：
2014-09
期刊：
影响因子：
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通讯作者：
A. Abrajevitch;A. Abrajevitch;A. Roberts;K. Kodama
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文献类型：
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作者：
A. Abrajevitch;A. Abrajevitch;A. Roberts;K. Kodama
ODP站点747，中央Kerguelen高原，包含一个几乎完整的记录中中新世气候转变（MMCT）。其异常良好的保存和丰富的有孔虫组合，导致在站点747的MMCT间隔成为高分辨率的古气候研究的焦点，建立了这个序列作为南大洋的参考。我们结合联合收割机的X射线荧光（XRF）元素计数的铁，钛，铝和浓度依赖的磁性参数跟踪火山灰输入到沉积物在ODP孔747 A。我们观察到系统的变化，Al/Ti和Fe/Ti的比率，是一致的，在增加陆源输入的时候，初级生产力的增加，因此，增加养分供应。一个峰值的陆源物质，我们解释为火山灰，正好与物种丰度和稳定的氧和碳同位素变化的MMCT间隔内的重大变化。这种相关性表明，与火山铁施肥营养通量发挥了重要作用，在控制浮游植物群落在站点747。我们证明，快速获得的XRF和磁性参数可以提供有用的代理陆源输入，因此，在远洋海洋环境中的营养通量，可以帮助解决本地与全球的驱动程序的古环境和古海洋学的变化。
ODP Site 747, central Kerguelen Plateau, contains a nearly complete record of the Middle Miocene Climate Transition (MMCT). Its unusually well preserved and rich foraminiferal assemblages have resulted in the MMCT interval at Site 747 becoming a focus of high-resolution paleoclimatic studies that have established this sequence as a Southern Ocean reference. We combine X-ray fluorescence (XRF) elemental counts of Fe, Ti, and Al and concentration-dependent magnetic parameters to trace volcanic ash input to sediments at ODP Hole 747A. We observe systematic variations in Al/Ti and Fe/Ti ratios that are consistent with increased primary productivity at times of increased terrigenous input and, therefore, increased nutrient supply. A spike in terrigenous material, which we interpret as volcanic ash, coincides with major changes in species abundance and stable oxygen and carbon isotopic shifts within the MMCT interval. This correlation suggests that nutrient flux associated with volcanic iron fertilization played a significant role in controlling phytoplankton communities at Site 747. We demonstrate that rapidly obtained XRF and magnetic parameters can provide useful proxies for terrigenous input and, therefore, nutrient fluxes in pelagic marine settings that can help to resolve local versus global drivers of paleoenvironmental and paleoceanographic changes.