10Be and 26Al isotopic data in ODP marine sediment cores near eastern Greenland

The million-year behavior of ice sheets is poorly understood because younger glaciations remove the terrestrial record of older advances. However, material shed from continents is preserved as marine sediment that can be analyzed to infer glacial process and history. Here, we use measurements of in situ produced cosmogenic 10Be and 26Al in marine sediment cores to understand the long-term behavior of the eastern Greenland Ice Sheet. We find a progressive, order-of-magnitude decline in 10Be over the past 7.5 Myr, consistent with deep, ongoing erosion by ice of the pre-icehouse Greenlandic landscape. 26Al/10Be indicates that much of East Greenland was covered by ice for most of the Pleistocene. At major climate transitions, isotope concentrations and 26Al/10Be change, consistent with ice sheet expansion into previously ice-free terrain. The detrital cosmogenic history reflects major events recorded in the marine benthic δ18O record, confirming that the Greenland Ice Sheet consistently responded to global climate forcing.

冰盖百万年级别的演化行为迄今仍未得到充分认知，这是因为较年轻的冰期会抹去早期冰进事件的陆地沉积记录。不过，大陆剥蚀的碎屑物质会以海洋沉积物的形式被保存下来，通过对其开展分析可反推冰川作用过程与演化历史。本研究通过对海洋沉积物岩芯中原位生成的宇宙成因10Be与26Al（cosmogenic 10Be and 26Al）进行定量测量，以解析格陵兰冰盖东部的长期演化行为。研究发现，在过去750万年中，10Be的含量呈现出渐进式的数量级下降，这与冰室期前格陵兰地表持续受到冰层的深层侵蚀作用相吻合。26Al/10Be比值分析表明，更新世的大部分时段内，格陵兰东部的大片区域均被冰层覆盖。在重大气候转型事件中，同位素浓度与26Al/10Be比值均发生变化，这与冰盖向此前无冰区域扩张的特征相一致。碎屑态宇宙成因核素记录反映了海洋底栖δ18O记录中所保存的重大气候事件，证实格陵兰冰盖始终响应全球气候强迫作用。