Miocene to Quaternary Paleoceanography in the Northern North Atlantic: Variability in Carbonate and Biogenic Opal Accumulation
Miocene to Quaternary Paleoceanography in the Northern North Atlantic: Variability in Carbonate and Biogenic Opal Accumulation
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北大西洋北部中新世至第四纪古海洋学：碳酸盐岩和生物蛋白石堆积的变化
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
J. Thiede
中科院分区：
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作者：
G. Bohrmann;R. Henrich;J. Thiede
根据大量沉积物和一些远洋成分（碳酸盐，总有机碳，生物蛋白石部分）的积累率的主要变化在北大西洋北方从中新世到最近的古海洋学进行了讨论。各种过程的相互作用可能造成了北方寒冷气候的逐步演变。突出的事件是开始的深水出口整个格陵兰-苏格兰海脊与第一个显着的溢出整个冰岛-苏格兰段发生最有可能在13 - 11马和大约7马之间的丹麦海峡。沉降早期阶段海平面在临界岩床深度附近的振荡可能影响了北大西洋以及挪威-格陵兰海的海洋环流。此外，挪威-格陵兰海形成和输出密集深水的潜力，增加了北方半球的海洋性。在10.2 - 9.3，8.7 - 8.2，5.8 - 5.4和4.8 - 3.2 Ma期间，代表了向北大西洋中部的水物质交换增加的时间，发生了碳酸盐沉积。另一方面，较高的蛋白石积累率和减少水质量交换（9.3 - 8.7和5.4 - 4.8马）可能与海平面振荡的格陵兰-苏格兰海脊的临界槛深度周围。北方半球冷却的建立可能可以追溯到晚中新世时期，有适度的冰筏碎片输入。北方半球在4 Ma左右出现了显著的逐步变冷，并最终导致了整个北大西洋海冰的第一次大规模扩张和冰筏漂流。2.6 MA.
Based on accumulation rates of the bulk sediment and some pelagic components (carbonate, total organic carbon, and biogenic opal fractions) major changes in the paleoceanography of the northern North Atlantic from Miocene to Recent are discussed. Interactions of various processes could have created a stepwise evolution of cold climates in the northern hemisphere. Prominent events were the onset of deep water export across the Greenland-Scotland Ridge with the first significant overflow across the Iceland-Scotland segment occurring most probably between 13 – 11 Ma and at about 7 Ma across the Denmark Strait. Oscillations of sea-level around the critical sill depth in the early phases of the subsidence may have influenced the oceanic circulation in the North Atlantic as well as in the Norwegian-Greenland Sea. Furthermore the potential of the Norwegian-Greenland Sea to form and export dense deep water, increased the meridionality in the northern hemisphere. During 10.2 – 9.3, 8.7 – 8.2, 5.8 – 5.4 and 4.8 – 3.2 Ma representing times of increased water mass exchange to the central North Atlantic, carbonate deposition occurred. On the other hand, higher opal accumulation rates and decreased water mass exchange (9.3 – 8.7 and 5.4 – 4.8 Ma) may be correlated with sea-level oscillations around the critical sill depth of the Greenland-Scotland Ridge. The build-up of northern hemisphere cooling can probably traced back to late Miocene times with modest ice-rafted debris input. A significant stepwise increase of northern hemisphere cooling occurred around 4 Ma and finally resulted in the first large extension of sea ice and ice-rafting in the entire North Atlantic at ca. 2.6 Ma.