Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation
Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation
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末次冰期期间苏格兰西部和北爱尔兰近海巴拉扇冰流的范围和消退历史
DOI：
10.1016/j.quascirev.2018.10.002
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发表时间：
2018
影响因子：
4
通讯作者：
Callard S
中科院分区：
文献类型：
--
作者：
Callard S
在上一次冰川盛期(LGM)期间，终止海洋的巴拉扇冰流(BFIS)是不列颠爱尔兰冰盖(BITS)的主要管道，随着冰流到马林海的大陆架上，排干了苏格兰西部和爱尔兰西北部的大部分地区。到目前为止，这股横跨大陆架的冰流的范围和退缩历史还不是很清楚。特别是，到目前为止，对这一冰流历史的地质年代学限制仅限于深海岩心或陆地宇宙源核素在陆地上的测年，而大陆架上的年龄并不存在。为了了解在退缩过程中作用于这一海洋终端冰流的可能的外部强迫因素，有必要改进对其消融的地质年代学约束。在这里，我们介绍了新的地球物理数据、海洋沉积岩心和超过40个放射性碳测年数据，以提供对BFIS最大范围的重要限制，以及穿过马林陆架后退的时间和模式。海底次海底剖面中发现的日期较长的冰雹和接地带楔体(GZW)提供了BFI在LGM期间到达马林陆架边缘的证据，并在26.7ka BP左右达到其最大范围。两组gzw的存在表明，撤退的风格是断断续续的。新的放射性碳年代学显示，25.9 ka BP开始从陆架边缘撤退，23.2ka BP大部分大陆架没有冰，最晚20.2ka BP赫布里底海出现冰川条件。总而言之，这些结果表明，马林陆架的大部分没有地面冰，大约21.5-20ka BP，比以前重建的要早4000年。我们将这种早期冰川消融归因于冰川均衡凹陷达到最大程度时导致的高相对海平面，促进了冰架和接地线的不稳定。两个深槽，形成了反向的河床坡度，有助于继续[...]
during the last glacial maximum (lgm) the marine-terminating barra fan ice stream (bfis), a major conduit of the british irish ice sheet (bits), drained much of western scotland and northwest ireland with ice streaming onto the continental shelf of the malin sea. the extent and retreat history of this ice stream across the shelf, until now, is not well known. in particular, geochronological constraints on the history of this ice stream have thus far been restricted to deep-sea cores or terrestrial cosmogenic nuclide dating onshore, with ages across the shelf absent. to understand the possible external forcing factors acting on this marine terminating ice stream during retreat, improved geochronological constraint on its deglaciation is necessary. here, we present new geophysical data, marine sediment cores and over forty radiocarbon dates to provide important constraints on maximum extent of the bfis, as well as the timing and pattern of retreat back across the malin shelf. dated moraines and grounding-zone wedges (gzw) seen in seafloor sub-bottom profiles provide evidence that the bfis reached the malin shelf edge during the lgm and was at its maximum extent around 26.7 ka bp. the presence of two sets of gzws suggests that the style of retreat was episodic. the new radiocarbon chronology shows that retreat from the shelf edge was underway by 25.9 ka bp, with the majority of the continental shelf ice free by 23.2 ka bp, and that glacimarine conditions were present in the sea of hebrides by 20.2 ka bp at the latest. collectively, these results indicate that the majority of the malin shelf was free of grounded ice by similar to 21.5-20 ka bp, which is up to 4000 years earlier than previously reconstructed. we attribute this early deglaciation to high relative sea level caused by glacial isostatic depression when the biis reached its maximum extent promoting ice shelf and grounding line instability. two deep troughs, forming reverse bed slopes, aided the continued[...]
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影响因子：
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作者：
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通讯作者：
P. Coxon
DOI：
--
发表时间：
2007
期刊：
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影响因子：
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作者：
E. Cowan;Jinkui Cai;R. Powell;Jenifer Clark;Jeffrey N. Pitcher
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DOI：
--
发表时间：
2010
期刊：
影响因子：
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作者：
P. Dunlop;Rachel Shannon;M. McCabe;R. Quinn;E. Doyle
通讯作者：
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影响因子：
2.9
作者：
LABERG, JS;VORREN, TO
通讯作者：
VORREN, TO