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Late glacial to holocene sedimentary facies of the Eirik Drift, southern Greenland margin: Spatial and temporal variability and paleoceanographic implications
Marine Geology ( IF 2.6 ) Pub Date : 2021-07-17 , DOI: 10.1016/j.margeo.2021.106568
Sally Davies 1 , Dorrik Stow 2 , Uisdean Nicholson 2
Affiliation  

The Eirik Drift, off southern Greenland, is one of a series of contourite deposits in the northern North Atlantic that record changes in the strength and location of western boundary currents in the region. To date however, the sedimentary facies, and particularly the variation in facies across this drift, have received relatively little investigation. Here, we present an analysis of the sedimentary facies observed within a transect of cores from the crest to toe of the Eirik Drift from late Pleistocene to Holocene. The Holocene sequence consists of muddy contourites with high sedimentation rates at the drift toe, and a condensed sequence of sandy contourites on the upper drift flanks, consistent with winnowing under strong bottom currents on the upper drift and deposition under a low velocity, sediment-laden current at the drift toe. We interpret this to be a combined result of episodic, high-energy benthic storm events associated with the East Greenland Current (EGC) on the upper drift and more continuous, lower velocity Deep Western Boundary Current (DWBC) on the drift flanks. The deglacial interval is represented by muddy contourites across the drift, with evidence for decreasing current activity (both EGC and DWBC) and more widespread ice-rafted deposition from the Bolling-Allerod into the Younger Dryas. Palaeocurrent data from this interval show two separate current directions at the crest of the drift, suggesting temporary, local detachment of the DWBC or EGC, linked to temporal variation in current strength. The late glacial interval consists of glaciomarine hemipelagites and muddy contourites, with evidence for a higher degree of current influence at shallower depths, consistent with a moderate EGC and weak DWBC. This is the first time that the EGC is recognised as having a significant role in sedimentation on the Eirik Drift.



中文翻译:

格陵兰岛南部边缘 Eirik Drift 的晚冰期至全新世沉积相:时空变异性和古海洋学意义

Eirik Drift 位于格陵兰岛南部,是北大西洋北部的一系列等高岩矿床之一,记录了该地区西部边界流强度和位置的变化。然而,迄今为止,沉积相,特别是整个漂移过程中的相变化,得到的研究相对较少。在这里,我们对从晚更新世到全新世的 Eirik Drift 的波峰到波尖的岩心横断面中观察到的沉积相进行了分析。全新世层序由在漂流趾处具有高沉积速率的泥质等高岩和在上漂流侧翼的砂质等高岩的凝聚层序组成,这与上漂流在强底流下的风选和低速、载沙下的沉积相一致。流趾处的电流。我们将此解释为与上部漂移的东格陵兰海流 (EGC) 和漂移侧翼上更连续、速度更低的深西部边界流 (DWBC) 相关的偶发性高能量底栖风暴事件的综合结果。冰消期间隔由漂移的泥泞等高岩代表,有证据表明当前活动(EGC 和 DWBC)正在减少,并且从 Bolling-Allerod 到 Younger Dryas 的更广泛的冰筏沉积。该区间的古海流数据显示在漂移的顶部有两个独立的海流方向,表明 DWBC 或 EGC 的临时局部脱离,与海流强度的时间变化有关。晚冰期间隔由冰川半长发岩和泥质等高岩组成,有证据表明在较浅的深度受到较高程度的电流影响,与中等 EGC 和弱 DWBC 一致。这是第一次认识到 EGC 在 Eirik Drift 上的沉积作用中具有重要作用。

更新日期:2021-07-27
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