Flux and provenance of ice-rafted debris in the earliest Pleistocene sub-polar North Atlantic Ocean comparable to the last glacial maximum
Flux and provenance of ice-rafted debris in the earliest Pleistocene sub-polar North Atlantic Ocean comparable to the last glacial maximum
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DOI：
10.1016/j.epsl.2012.05.034
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发表时间：
2012-08-01
影响因子：
5.3
通讯作者：
Becker, Julia
中科院分区：
文献类型：
--
作者：
Bailey, Ian;Foster, Gavin L.;Becker, Julia
在北方半球冰川作用（iNHG）加剧期间，负责冰筏碎片（IRD）输入到亚极地北大西洋的早更新世冰盖的位置的详细信息相对知之甚少。为了揭示这个问题的新的光，我们提出了第一个结合的IRD通量和地球化学来源的个人砂大小的IRD沉积在亚极地北大西洋在最早的大幅度更新世冰期，海洋同位素阶段（MIS）100（类似于2.52马），可以说是关键的冰川在iNHG。IRD的来源进行了评估，使用激光烧蚀铅（Pb）同位素分析的单一长石颗粒。结果表明，该地区的Pb同位素组成（Pb-206/Pb-204. Pb-207/Pb-204和Pb-208/Pb-204（> 150 μ m）沉积在DSDP 611 A站点的斜晶石，在MIS 100期间，ODP站点981和IODP站点U1308记录了从早期冰川漂流事件期间主要为太古代的环北大西洋大陆来源到主要为古生代和元古代的转变。在完整的冰川条件下老化的来源。完整的冰川MIS 100的铅-铅空间中的长石分布更接近于MIS 2（类似于23.8 ka）的环境（非Heinrich事件）冰漂流事件期间记录的在末次冰期IRD带中心（IODP/DSDP站点U1308/609）沉积的长石，而不是MIS 5d（类似于106 ka）。我们的早期更新世和末次冰期循环数据集的比较表明，MIS 100的特点是丰富的冰山崩解从大冰盖在多个大陆的高北方纬度（不只是在格陵兰岛）。(C)2012爱思唯尔有限公司版权所有。
Relatively little is known in detail about the locations of the early Pleistocene ice-sheets responsible for ice-rafted debris (IRD) inputs to the sub-polar North Atlantic Ocean during intensification of northern hemisphere glaciation (iNHG). To shed new light on this problem, we present the first combined in-depth analysis of IRD flux and geochemical provenance of individual sand-sized IRD deposited in the sub-polar North Atlantic Ocean during the earliest large amplitude Pleistocene glacial, marine isotope stage (MIS) 100 (similar to 2.52 Ma), arguably the key glacial during iNHG. IRD provenance is assessed using laser ablation lead (Pb) isotope analyses of single feldspar grains. We find that the Pb-isotope composition (Pb-206/Pb-204. Pb-207/Pb-204 and Pb-208/Pb-204) of individual ice-rafted (> 150 mu m) feldspars deposited at DSDP Site 611A, ODP Site 981 and IODP Site U1308 during MIS 100 records a shift from predominantly Archaean-aged circum-North Atlantic Ocean continental sources during early glacial ice-rafting events to dominantly Palaeozoic and Proterozoic-aged sources during full glacial conditions. The distribution of feldspars in Pb-Pb space for full glacial MIS 100 more closely resembles that documented for feldspars deposited at the centre of the last glacial IRD belt (at IODP/DSDP Site U1308/609) during ambient (non-Heinrich-event) ice-rafting episodes of MIS 2 (similar to 23.8 ka) than that documented for MIS 5d (similar to 106 ka). Comparison of our early Pleistocene and last glacial cycle datasets suggests that MIS 100 was characterised by abundant iceberg calving from large ice-sheets on multiple continents in the high northern latitudes (not just on Greenland). (C) 2012 Elsevier B.V. All rights reserved.