Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/C-34010, Sgonico (TS) Italy.
Department of Geosciences, Hamilton College, Clinton, NY 13323, USA. College of Marine Science, University of South Florida, 140 7th Avenue South, St. Petersburg, FL 33701-5016, USA.
Science. 2014 Sep 12;345(6202):1354-8. doi: 10.1126/science.1256697.
Grounding zones, where ice sheets transition between resting on bedrock to full floatation, help regulate ice flow. Exposure of the sea floor by the 2002 Larsen-B Ice Shelf collapse allowed detailed morphologic mapping and sampling of the embayment sea floor. Marine geophysical data collected in 2006 reveal a large, arcuate, complex grounding zone sediment system at the front of Crane Fjord. Radiocarbon-constrained chronologies from marine sediment cores indicate loss of ice contact with the bed at this site about 12,000 years ago. Previous studies and morphologic mapping of the fjord suggest that the Crane Glacier grounding zone was well within the fjord before 2002 and did not retreat further until after the ice shelf collapse. This implies that the 2002 Larsen-B Ice Shelf collapse likely was a response to surface warming rather than to grounding zone instability, strengthening the idea that surface processes controlled the disintegration of the Larsen Ice Shelf.
底质区是冰原在从基岩上的静止状态过渡到完全漂浮状态的地方，有助于调节冰流。2002 年拉森 B 冰架崩塌使海床暴露，从而能够对海湾海床进行详细的形态测绘和采样。2006 年收集的海洋地球物理数据显示，在 Crane 峡湾前缘有一个大型的、弧形的、复杂的底质区沉积系统。海洋沉积物岩芯中的放射性碳年代测定表明，大约在 12000 年前，该地点的冰层与床面失去了接触。先前对峡湾的研究和形态测绘表明，2002 年以前 Crane 冰川的底质区就在峡湾内，直到冰架崩塌后才进一步后退。这意味着 2002 年拉森 B 冰架的崩塌很可能是对地表变暖的反应，而不是底质区不稳定的反应，这进一步证实了表面过程控制了 Larsen 冰架的解体这一观点。
