Pleistocene fluctuations in the western boundary undercurrent on the Blake Outer Ridge
Pleistocene fluctuations in the western boundary undercurrent on the Blake Outer Ridge
复制标题
布莱克外山脊西部边界暗流的更新世波动
DOI：
10.1029/pa003i002p00191
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
N. C. Palczuk
中科院分区：
文献类型：
--
作者：
T. Johnson;E. L. Lynch;W. Showers;N. C. Palczuk
使用电子粒子分析对布莱克外山脊顶部的两个活塞芯中的碎屑粉砂部分的平均粒度进行了分析。两个岩心的所得剖面具有高度相关性，并被解释为反映了过去 90 kyr 的西部边界暗流 (WBUC) 的古速度。记录可分为三个时期。第一个阶段涵盖了过去 12,000 年，并以突然加速开始，标志着从缓慢的冰川条件向更加剧烈的全新世条件的转变。全新世后期是一个强劲但多变的流动时期。第二个时期从 30 到 12 × 10^3 年，其特点是 WBUC 强度在最后一个冰河时期稳步下降。洋流继续减速，直到 12 × 10³ 年，极锋最终向北撤退，经过连接挪威海和北大西洋的通道。第三个时期，从 30 年到大约 90 × 10³ 年，是一个强且可变的流动时期，与氧同位素记录中看到的冰期/间冰期信号无关。在此期间，最大流量的核心似乎在布莱克外脊的侧翼上下移动，并且可能受到盐度和 WBUC 源区温度变化的影响。
The mean grain size of the detrital silt fraction was analyzed in two piston cores from the crest of the Blake Outer Ridge using electronic particle analysis. The resultant profiles in the two cores are highly correlatable and are interpreted to reflect the paleospeed of the Western Boundary Undercurrent (WBUC) for the past 90 kyr. The record can be divided into three periods. The first encompasses the past 12,000 years and begins with an abrupt acceleration marking the transition from slow, glacial to more vigorous, Holocene conditions. The later Holocene is a period of strong but variable flow. The second period extends from 30 to 12 × 10³ years and is characterized by a steady reduction of WBUC strength through the last ice age. The current continued to decelerate until 12 × 10³ years when the polar front finally retreated northward past the passages connecting the Norwegian Sea to the north Atlantic. The third period, from 30 to about 90 × 10³ years, was a time of strong and variable flow that was independent of the glacial/interglacial signal that is seen in the oxygen isotope record. During this time, the core of maximum flow appears to have shifted up and down the flank of the Blake Outer Ridge and may have been influenced as much by salinity as by temperature variations in the source areas of the WBUC.