Deepwater circulation on Blake Outer Ridge (western North Atlantic) during the Holocene, Younger Dryas, and Last Glacial Maximum
Deepwater circulation on Blake Outer Ridge (western North Atlantic) during the Holocene, Younger Dryas, and Last Glacial Maximum
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DOI：
10.1029/2007gc001771
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发表时间：
2008-03-26
影响因子：
3.5
通讯作者：
Hall, Ian R.
中科院分区：
文献类型：
--
作者：
Evans, Helena K.;Hall, Ian R.
沿着西亚热带北大西洋的布莱克外脊，对三个深度样带共33个沉积物芯样进行了调查。可排序的粉砂平均（（SS）酒吧）粒度和稳定同位素记录被用来评估的位置和相对强度的西部边界暗流（WBUC）在全新世，末次冰期最大期（LGM），和新仙女木（YD）的间隔。全新世重建与该地区现代物理和化学水文测量结果一致，表明WBUC快速流动核心的深度位置（3000-4000 m，在山脊侧翼加深至4500 m水深）和以北大西洋深水（NADW）为主的水柱。LGM和YD重建表明，在这两个时间间隔，一个可比的水文制度，提出了类似的模式，是明显不同的全新世重建的流通。WBUC的最大流速区在这些间隔建议已转移到2500米以上的水深，与营养耗尽的冰川北大西洋中层水的形成与南方水源水（SSW）的影响越来越大。低于4000米的水深，（SS）酒吧的结果暗示在增加SSW流活力在LGM和YD更高的流速比在全新世。这项研究提供了一个框架，以帮助解释的时间序列记录的古水流速度变化的WBUC区域。
Three depth transects containing a total of 33 sediment cores were investigated along the Blake Outer Ridge in the western subtropical North Atlantic. Sortable silt mean ((SS) over bar) grain size and stable isotope records were used to assess the position and relative intensity of the Western Boundary Undercurrent (WBUC) during the Holocene, the Last Glacial Maximum (LGM), and the Younger Dryas (YD) intervals. The Holocene reconstruction is consistent with modern physical and chemical hydrographic measurements in the area, suggesting a deep position for the fast flowing core of the WBUC (3000-4000 m, deepening to similar to 4500 m water depth on the ridge flanks) and a water column dominated by North Atlantic Deep Water (NADW). The LGM and YD reconstructions show that a comparable hydrographic regime was present during both these intervals, suggesting a similar mode of circulation that was appreciably different from the Holocene reconstruction. The WBUC's zone of maximum flow speed during these intervals is suggested to have shifted above 2500 m water depth, consistent with nutrient depleted Glacial North Atlantic Intermediate Water formation with an increasing influence of Southern Source Water (SSW) beneath. Below 4000 m water depth, (SS) over bar results hint at increased SSW flow vigor during both the LGM and YD with higher flow speeds than during the Holocene. This study provides a framework for aiding the interpretation of time series records of paleocurrent flow speed changes in the region of the WBUC.