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（ice sheets）百万年级的演化行为尚未得到充分认知，这是因为较新的冰期（glaciations）会抹去较古老冰进事件的陆地沉积记录。然而，大陆剥蚀的碎屑物质会被保存为海洋沉积物（marine sediment），通过对其分析可推断冰川作用过程与演化历史。本研究通过对海洋沉积物岩芯（marine sediment cores）中原位生成的宇宙成因10铍（cosmogenic 10Be）与26铝（cosmogenic 26Al）进行测量，以解析格陵兰东部冰盖（eastern Greenland Ice Sheet）的长期演化行为。我们发现，在过去750万年中，10Be的浓度呈现出渐进式的数量级衰减，这与冰室期前格陵兰地貌持续受到冰盖深层侵蚀的特征相符。26Al/10Be比值表明，更新世（Pleistocene）的大部分时段内，格陵兰东部的大片区域均被冰盖覆盖。在重大气候转型期，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一致。碎屑宇宙成因演化记录反映了海洋底栖δ18O记录（marine benthic δ18O record）中所记载的重大气候事件，证实格陵兰冰盖始终响应全球气候强迫（global climate forcing）作用。