Late Quaternary Deep Water Circulation in the South Atlantic: Reconstruction from Carbonate Dissolution and Benthic Stable Isotopes
Late Quaternary Deep Water Circulation in the South Atlantic: Reconstruction from Carbonate Dissolution and Benthic Stable Isotopes
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南大西洋晚第四纪深水环流：碳酸盐溶解和底栖稳定同位素重建
DOI：
10.1007/978-3-642-80353-6_30
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发表时间：
1996
期刊：
影响因子：
4.9
通讯作者：
G. Wefer
中科院分区：
文献类型：
--
作者：
T. Bickert;G. Wefer
利用12个重力岩心的底栖有孔虫Cibicides wellerstorfi的碳酸盐溶蚀数据（含砂量）和δ13C记录，重建了近36万年来南大西洋深水环流的历史。这些岩心是从四个盆地（巴西、几内亚、安哥拉和开普盆地）的水深2900米至4600米的深度剖面中选择的。深度样带方法可以从古属性记录中去除平均全球变化以及局部生产力影响，并提取由南大西洋深水化学和/或环流变化引起的变化。由于末次盛冰期NADW的减少，南分量水在水柱中的位置比现在更高，向北延伸更远。该冰川水团可分为δ13C值在0.2% ~ 0.7%之间的上部（USCW）和δ13C值在-0.2% ~ 0.2%之间的下部（LSCW）。这界线，也以方解石溶斜为标志，在赤道附近，水深3800米，向南大洋略微上升。现今底水环流的不对称性（西部盆地和开普盆地为LCDW， 4000 m以下东部盆地为NADW）不存在。通过与西太平洋深处岩心的比较（ODP 806B; Bickert et al. 1993），有证据表明，营养丰富但缺氧的LSCW类似于冰川太平洋深水。4、6、8和10个更老的冰期也是如此。
Carbonate dissolution data (sand contents) and δ13C records of the epibenthic foraminifer Cibicides wuellerstorfi from 12 gravity cores are used to reconstruct the history of deep water circulation in the South Atlantic for the last 360,000 years. The cores were selected from depth-sections in four basins (Brasil-, Guinea-, Angola- and Cape Basins) in water depths between 2900 m and 4600 m. The depth-transect approach allows removal of mean global shifts as well as local productivity effects from the paleo-property records and extraction of variations which are due to changes in deep water chemistry and/or circulation in the South Atlantic. As a result of the reduction of NADW during the last glacial maximum the Southern Component Water was higher in the water column and extended farther north than it does today. This glacial water mass can be divided into an upper part (USCW) with δ13C values between 0.2%o and 0.7%o and a lower part (LSCW) characterized by values of -0.2%o to 0.2%o. The boundary, marked also by the calcite lysocline, was at 3800 m water depth near the equator and rose slightly toward the Southern Ocean. The asymmetry observed in bottom water circulation today (LCDW in western basins and in the Cape Basin, NADW in eastern basins below 4000 m) was not present. From comparison to a deep western Pacific core (ODP 806B; Bickert et al. 1993) there is evidence that the nutrient-enriched but oxygen-depleted LSCW resembles the glacial Pacific Deep Water. This is also true for the older glacial stages 4, 6, 8 and 10.