Clay Mineral Fluctuations in Late Quaternary Sediments of the Southeastern South Atlantic: Implications for Past Changes of Deep Water Advection
Clay Mineral Fluctuations in Late Quaternary Sediments of the Southeastern South Atlantic: Implications for Past Changes of Deep Water Advection
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DOI：
10.1007/978-3-642-80353-6_31
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发表时间：
1996
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影响因子：
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通讯作者：
B. Diekmann;R. Petsehick;F. Gingele;D. Fütterer;A. Abelmann;U. Brathauer;R. Gersonde;A. Mackensen
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文献类型：
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作者：
B. Diekmann;R. Petsehick;F. Gingele;D. Fütterer;A. Abelmann;U. Brathauer;R. Gersonde;A. Mackensen
南大西洋东南部和邻近的南大洋晚第四纪沉积岩芯中的粘土矿物波动幅度较低。在南极绕极流/威德尔环流边界以北，小尺度的变化，特别是粘土矿物比值的变化，基本上反映了深水平流响应气候振荡的周期性变化。绿泥石来源于南半球高纬度地区（南极半岛、巴塔哥尼亚），受南源深水向北平流作用搬运分布。北源深水将成土高岭石从热带地区带到南大洋。两个深水团的高岭石和高岭石的相反平流是由高岭石/高岭石比值的纬向地带性显示的，北高值。与冰川期相比，在温暖的气候阶段，岩芯高岭石/高岭土的变化表现出升高的比率。交叉光谱分析表明，高岭石/碳酸盐比是连贯的，并在相位与全球冰体积在41-kyr和100-kyr期间的结晶度和eccentricity.By现代深海沉积物中的高岭石/碳酸盐比与现今的深水分布，过去的深水平流模型可以推断从downcore变化的高岭石/碳酸盐比。因此，在冰川盛期，北方水源的水不会到达南纬40°以上。在间冰期的最佳时期，北源深层水注入南大洋至南纬55°左右。
Downcore clay mineral fluctuations in Late Quaternary sediment cores from the southeastern South Atlantic and adjoining Southern Ocean are of low amplitude. North of the Antarctic Circumpolar Current/Weddell Gyre boundary, small-scale variations, particularly of clay mineral ratios, essentially monitor cyclic changes of deep water advection in response to climatic oscillations.Kaolinite and chlorite are of most reliable palaeoceanographic significance. Chlorite originates from southern high-latitudes (Antarctic Peninsula, Patagonia) and is transported and distributed by northward advection of southern-source deep water. Northern-source deep water carries pedogenic kaolinite from the tropical regions to the Southern Ocean. The opposite advection of kaolinite and chlorite by both deep water masses is displayed by a latitudinal zonation of kaolinite/ chlorite ratios with higher values to the north. Downcore kaolinite/chlorite variations exhibit raised ratios during warm climatic stages compared to glacial periods. Cross spectral analyses reveal that kaolinite/chlorite ratios are coherent and in phase with global ice volume in the 41-kyr and 100-kyr periods of obliquity and eccentricity.By relating kaolinite/chlorite ratios in modern deep-sea sediments to the present-day deep water distribution, a model of past deep water advection may be inferred from downcore variations of kaolinite/chlorite ratios. Thus, northern-source water reaches not farther south than 40°S during glacial maxima. During interglacial optima northern-source deep water is injected into the Southern Ocean to latitudes around 55°S.