Ice-rafted detritus events in the Arctic during the last glacial interval, and the timing of the Innuitian and Laurentide ice sheet calving events
Ice-rafted detritus events in the Arctic during the last glacial interval, and the timing of the Innuitian and Laurentide ice sheet calving events
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DOI：
10.1111/j.1751-8369.2008.00057.x
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发表时间：
2008-01
期刊：
影响因子：
1.9
通讯作者：
D. Darby;Paula Zimmerman
中科院分区：
文献类型：
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作者：
D. Darby;Paula Zimmerman
北冰洋的浮冰碎屑（IRD）层不仅表明了这些碎屑沉积物的来源，而且对冰漂和冰盖的历史也有了深入的了解。碎屑砂大小的氧化铁矿物颗粒与精确的来源相匹配，使用每个颗粒的微探针化学指纹，以及升高的粗IRD丰度和放射性碳年龄，用于定义来自因纽伊特和劳伦泰德冰盖北极部分的IRD峰值。由于这两个地区的颗粒可能会被产冰区近海冰架上的海冰带走，因此这些颗粒的峰值必须与粗IRD相关联，以识别冰山崩解事件，并将其与海冰漂流区分开来。这两个冰原的冰山所沉积的IRD峰序列表明，在11至36 Kya期间，这两个冰原的冰山崩解速度都加快了6至7倍。这些IRD事件之间相对较短的时间表明，除了最后一次事件外，冰盖并没有在每次IRD事件中完全崩溃。尽管有一些迹象表明，一个冰盖可能在另一个冰盖之前开始崩解冰山，但北极冰芯的分辨率并不能确定这一点。这强调了对来自北极中部以及靠近更新世大冰原末端的高分辨率岩心的需求。海冰漂流发生在末次冰期，甚至在一些冰川IRD事件期间，如来自非冰川来源的铁颗粒所表明的那样。
Ice-rafted detritus (IRD) layers in the Arctic Ocean not only indicate the source of this detrital sediment, but give insights into the ice drift and ice sheet history. Detrital sand-sized Fe oxide mineral grains that are matched to precise sources using the microprobe chemical fingerprint of each grain, along with elevated coarse IRD abundance and radiocarbon ages, are used to define IRD peaks from the Innuitian and Arctic portions of the Laurentide ice sheets. Because grains from these two areas can be entrained by sea ice from the shelves just offshore of the calving areas, peaks in these grains must be correlated to coarse IRD to identify iceberg calving events, and to distinguish them from sea-ice rafting. The sequence of IRD peaks deposited by icebergs from these two ice sheets indicate that both ice sheets calved bergs at accelerated numbers, six or seven times, from 11 to 36 Kya. The relatively short times between most of these IRD events suggest that the ice sheets did not completely collapse with each IRD event, except the last event. Although there is some indication that one ice sheet may have begun calving bergs before the other, the resolution of the Arctic cores does not allow definitive determination of this. This emphasizes the need for higher resolution cores from the central Arctic, as well as from near the terminus of large Pleistocene ice sheets. Sea-ice rafting occurs throughout the last glacial stage, even during some glacial IRD events, as indicated by Fe grains from non-glacial sources.