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首页> 外文期刊>Paleoceanography >Glacial-interglacial variability in diatom abundance and valve size: Implications for Southern Ocean paleoceanography
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Glacial-interglacial variability in diatom abundance and valve size: Implications for Southern Ocean paleoceanography

机译：硅藻丰度和瓣膜大小的冰川间变化：对南大洋古海洋学的影响

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摘要

Antarctic sea ice extent along with Southern Ocean biological productivity varied considerably during glacial-interglacial periods, and both are known to have played a considerable role in regulating atmospheric CO2 variations in the past. Here we present data on diatom absolute abundance (valves/g of sediment) and size over the past 42ka B.P. and how they link to glacial-interglacial changes in Antarctic sea ice extent, Southern Ocean frontal systems, and aeolian dust flux. Our records of sea ice and permanent open ocean zone diatom abundances suggest a shift in the Antarctic winter sea ice limit and Polar Front respectively up to the modern-day Polar Frontal Zone during marine isotopic stages (MIS) 2 and late MIS 3. In addition to glacial shifts in the Polar Front, diatom assemblages also recorded a plausible northward shifts in Polar Front during few intervals of MIS 1. Glacial periods north of the Polar Front in the Indian sector of the Southern Ocean were characterized by higher total diatom abundance, larger Fragilariopsis kerguelensis apical length, and Thalassiosira lentiginosa radius. This is probably a consequence of (1) a northward expansion of the opal belt, a region characterized by high production and export of biogenic silica; (2) an increase in terrigenous input, via erosion of Crozet Islands; and (3) the alleviation of iron deficit by high input of Fe-bearing dust. The larger and highly silicified diatoms such as F. kerguelensis and T. lentiginosa may have mainly contributed in transporting biogenic silica and organic carbon to the seabed for the last 42ka, in the northern Polar Frontal Zone of the Indian sector of the Southern Ocean.
机译：在冰冰间期，南极海冰范围和南大洋的生物生产力变化很大，并且过去两者都在调节大气中的二氧化碳变化方面发挥了重要作用。在这里，我们介绍了过去42ka B.P.的硅藻绝对丰度（阀门/克沉积物）和大小的数据。以及它们如何与南极海冰范围，南大洋额叶系统和风尘通量的冰川间变化联系在一起。我们的海冰和永久性开放海域硅藻丰度的记录表明，在海洋同位素阶段（MIS）2和后期MIS 3中，南极冬季海冰极限和极地锋分别转移到了现代的极地锋带。由于极地锋的冰川移动，硅藻组合也记录了在MIS 1的几个间隔期间极地锋的向北移动的可能性。南印度洋印度洋极地带以北的冰川期的特征是总硅藻丰度更高，更大。剑兰（Fragilariopsis kerguelensis）的顶端长度，和长鞭草（Thalasiosira lentiginosa）半径。这可能是由于以下原因造成的：（1）蛋白石带向北扩张，该地区的特征是高产生物硅的生产和出口; （2）通过克罗泽群岛的侵蚀增加陆上投入; （3）通过高含量的含铁粉尘缓解铁缺乏症。较大的高度硅化的硅藻，例如kerguelensis和T. lentiginosa，可能主要是将生物硅和有机碳运输到南洋印度洋北部极地锋区的最后42ka到海床。

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