A highly productive Subarctic Atlantic during the Last Interglacial and the role of diatoms
A highly productive Subarctic Atlantic during the Last Interglacial and the role of diatoms
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DOI：
10.1130/g32454.1
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发表时间：
2011-11
期刊：
影响因子：
5.8
通讯作者：
O. Romero;George E. A. Swann;D. Hodell;P. Helmke;D. Rey;B. Rubio
中科院分区：
文献类型：
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作者：
O. Romero;George E. A. Swann;D. Hodell;P. Helmke;D. Rey;B. Rubio
末次间冰期（LIG）对应于海洋同位素阶段（MIS） 5e，提供了在没有人为强迫的情况下间冰期气候变率的参考。利用亚北极大西洋U1304综合海洋钻井计划站点获得的LIG扩展部分，我们证明了MIS 5e早期的海洋条件有利于硅藻的高生产和积累。大约125 ka时，在MIS 5e开始后约3 ky，硅藻主导的层状软泥的出现与向更高的δ 30 Si值的转变以及最长海喉的优势相吻合，表明地表水中营养物质的有效性和硅酸的利用增加。虽然亚北极锋为硅藻的高产量和沉积提供了物理条件，但这些过程本身不足以解释硅藻的高生产率和硅藻沉积物的形成。相反，亚南极模态水提供的营养池的增加在启动和维持硅藻生产方面发挥了决定性作用。晚第四纪硅藻高产和硅藻质沉积物的出现，挑战了目前关于北大西洋在LIG期间硅藻枯竭的假设。
The Last Interglacial (LIG), corresponding to Marine Isotope Stage (MIS) 5e, provides a reference of interglacial climate variability in the absence of anthropogenic forcing. Using an expanded section of the LIG gained at Integrated Ocean Drilling Program Site U1304 in the Subarctic Atlantic, we demonstrate that the early MIS 5e was marked by oceanographic conditions conducive for high diatom production and accumulation. The appearance of diatom-dominated laminated oozes ∼3 k.y. after the beginning of MIS 5e at ca. 125 ka coincides with a shift to higher δ 30 Si diat values together with the dominance of Thalassiothrix longissima , indicative of increased nutrient availability and silicic acid utilization in surface waters. Though the Subarctic Front provided the physical conditions for high diatom production and deposition, these processes alone are insufficient to explain the high rates of siliceous productivity and the formation of diatomaceous sediments. Instead, the additional presence of an increased nutrient pool provided by Subantarctic Mode Water played the decisive role in initiating and sustaining diatom production. The high diatom productivity and the occurrence of diatomaceous sediments in the late Quaternary challenge the current hypothesis of a silica-depleted North Atlantic during the LIG.