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首页> 外文期刊>Paleoceanography >Intermediate water links to Deep Western Boundary Current variability in the subtropical NW Atlantic during marine isotope stages 5 and 4
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Intermediate water links to Deep Western Boundary Current variability in the subtropical NW Atlantic during marine isotope stages 5 and 4

机译：在海洋同位素第5和第4阶段，中间水与亚热带西北大西洋深西部边界流的变化有关

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Records from Ocean Drilling Program Sites 1057 and 1059 (2584 m and 2985 m water depth, respectively) have been used to reconstruct the behavior of the Deep Western Boundary Current (DWBC) on the Blake Outer Ridge (BOR) from 130 to 60 kyr B. P. (marine isotope stage (MIS) 5 and the 5/4 transition). Site 1057 lies within Labrador Sea Water (LSW) but close to the present-day boundary with Lower North Atlantic Deep Water (LNADW), while Site 1059 lies within LNADW. High-resolution sortable silt mean ((SS) over bar) grain size and benthic delta C-13 records were obtained, and changes in the DWBC intensity and spatial variability were inferred. Comparisons are made with similar proxy records generated for the Holocene from equivalent depth cores on the BOR. During MIS 5e, (SS) over bar evidence at Site 1057 suggests slower relative flow speeds consistent with a weakening and a possible shoaling of the LSW-sourced shallower limb of the DWBC that occupies these depths today. In contrast, the paleocurrent record from the deeper site suggests that the fast flowing deep core of the DWBC was located close to its modern depth below 3500 m. During this interval the benthic delta C-13 suggests little chemical stratification of the water column and the presence of a near-uniform LNADW-dominated water mass. After similar to 111 kyr B. P. the (SS) over bar record at Site 1057 increases to reach values similar to Site 1059 for the rest of MIS 5. The strengthening of flow speeds at the shallow site may correspond to the initiation of Glacial North Atlantic Intermediate Water formation also suggested by a divergence in the benthic delta C-13 records with Site 1057 values increasing to similar to 1.2 parts per thousand. Coupled suborbital oscillations in DWBC flow variability and paleohydrography persisted throughout MIS 5. Comparison of these data with planktonic delta O-18 records from the sites and alkenone-derived sea surface temperature (SST) estimates from the nearby Bermuda Rise suggest a hitherto unrecognized degree of linkage between oscillations in subtropical North Atlantic SST and DWBC flow.
机译：已使用海洋钻探计划站点1057和1059（分别为2584 m和2985 m的水深）的记录来重建布莱克外山脊（BOR）从130至60 BP的深西部边界流（DWBC）的行为。 （海洋同位素阶段（MIS）5和5/4过渡）。站点1057位于拉布拉多海水（LSW）内，但靠近当今与北大西洋深水（LNADW）的边界，而站点1059位于LNADW内。获得了高分辨率的可分类淤泥平均值（（bar）之上的SS）粒度和底栖三角洲C-13记录，并推断了DWBC强度和空间变异性的变化。比较了从BOR上等效深度岩心为全新世生成的相似代理记录。在MIS 5e中，（SS）在站点1057上的柱状证据表明，相对流速较慢，这与DWBC的LSW浅肢（现今占据这些深度）的减弱和可能的挖浅是一致的。相反，来自更深地点的古流记录表明，DWBC的快速流动深部岩心位于3500 m以下的现代深度附近。在此间隔期间，底栖三角洲C-13提示水柱几乎没有化学分层，并且存在几乎均匀的LNADW为主的水团。在类似于111 kyr BP之后，站点1057的（SS）过柱记录增加，达到与MIS 5其余部分类似的站点1059的值。浅层站点流速的增强可能对应于北冰洋中期冰川的开始底栖三角洲C-13记录的发散也暗示了水的形成，Site 1057值增加到接近千分之1.2。在MIS 5中，DWBC流量变化和古水文记录中的耦合亚轨道振荡一直持续。这些数据与该地点浮游三角洲O-18记录的比较以及附近百慕大群岛Rise的烯酮衍生海表温度（SST）估计表明，迄今尚未认识到亚热带北大西洋海温与DWBC流量之间的联系。

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