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首页> 外文期刊>Journal of nannoplankton research: A publication of the International Nannoplankton Association >Paleoenvironmental changes in the North Atlantic (ODP Site 984) during Marine Isotope Stage 5 as deduced from coccolith reconstruction
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Paleoenvironmental changes in the North Atlantic (ODP Site 984) during Marine Isotope Stage 5 as deduced from coccolith reconstruction

机译：从球藻重建中推断出的海洋同位素第5期期间北大西洋（ODP 984号站点）的古环境变化

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摘要

Ocean Drilling Program (ODP) Site 984, located on the North Atlantic Bj?rn sediment drift close to the modern locations of the Arctic and Polar hydrographic fronts, provides high-resolution records for the late Pleistocene. The last interglacial, Marine Isotope Stage (MIS) 5, was the last extended warm period before the Holocene and gives insight into natural climate variability during interglacials. In order to reconstruct regional changes in productivity and hydrography of the North Atlantic during MIS 5,coccolith assemblages in ODP Site 984 sediments were investigated. For this purpose, changes in coccolith abundances, coccolith accumulation rates, assemblage composition, and diversity, as well as morphotypes and calcification stages of Emiliania huxleyi, were analyzed. Using coccolith data, progressive southward advances of the Arctic and Polar fronts into the subpolar North Atlantic Ocean were documented. The observed coccolith assemblages were generally dominated by Gephyrocapsa muellerae and are characterized by an average of only six species. Limited coccolith numbers and lowered species diversity point to the influence of progressive cold-water mass expansions into subpolar latitudes, in particular during the last glacial and stadial stages (MIS stages/stadials 6,5d, 5b,and 4). Three intervals (MIS interstadials 5e,5c,and 5a) of warm surface-water expansion were identified by increased coccolith numbers and elevated diversities. Differences in the composition of the coccolith assemblages.also indicate that the main northward expansions of the warm surface currents occurred during MIS 5e and 5a, with highest coccolith production observed in stage 5a, which is contrary to observations at other locations in the North Atlantic (Stolz & Baumann, 2010).
机译：海洋钻探计划（ODP）站点984位于北大西洋比约恩沉积物漂移附近，靠近北极和极地水文前沿的现代位置，提供了晚更新世的高分辨率记录。最后一个间冰期是海洋同位素阶段（MIS）5，这是全新世之前的最后一个延长的暖期，可以深入了解间冰期的自然气候变异性。为了重建MIS 5期间北大西洋生产力和水文学的区域变化，对ODP站点984沉积物中的可可石组合进行了研究。为此，分析了草的球藻丰度，球藻积累速率，组合物组成和多样性以及形态型和钙化阶段的变化。利用球藻数据，记录了北极和极地锋向南极亚大西洋北极的渐进式南进。观察到的球藻群通常被粘藻（Gephyrocapsa muellerae）所支配，其特征是平均只有六个物种。有限的球藻数量和较低的物种多样性表明，渐进的冷水物质扩展到亚极纬度的影响，特别是在最后的冰川和恒河阶段（MIS阶段/恒星6,5d，5b和4）。通过增加可可石块数和增加的多样性确定了三个温暖地表水膨胀的间隔（MIS中间5e，5c和5a）。可可砾岩组合的组成差异也表明，暖水面洋流的主要向北扩展发生在MIS 5e和5a期间，在阶段5a观测到最高可可砾石产量，这与北大西洋其他地区的观测结果相反（ Stolz＆Baumann，2010年）。

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