Abstract The marine-based West Antarctic Ice Sheet (WAIS) is considered the most unstable part of the Antarctic Ice Sheet, with particular vulnerability in the Amundsen Sea sector where glaciers are melting at an alarming rate. Far-field sea-level data and ice-sheet models have pointed towards at least one major WAIS disintegration during the Late Quaternary, but direct evidence for past collapse(s) from ice-proximal geological archives remains elusive. In order to facilitate geochemical and mineralogical tracing of the two most important glaciers draining into the Amundsen Sea, i.e. Pine Island Glacier (PIG) and Thwaites Glacier (TG), we here provide the first multi-proxy provenance analysis of 26 seafloor surface sediment samples from Pine Island Bay. Our data show that the fingerprints of detritus delivered by PIG and TG are clearly distinct near the ice-shelf fronts of both ice-stream systems for all grain sizes and proxies investigated. Glacial detritus delivered by PIG is characterised by low eNd values (~−9), high 87Sr/86Sr ratios (~0.728), low smectite content ( The geochemical and mineralogical fingerprints for PIG and TG reported here provide novel insights into sub-ice geology and allow us to trace both drainage systems in the geological past, under environmental conditions more similar to those envisioned in the next 50 to 100 years.

中文翻译：

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西南极洲薄弱下腹部的地球化学和矿物学指纹：松岛冰川和思韦茨冰川

摘要 以海洋为基础的南极西部冰盖 (WAIS) 被认为是南极冰盖中最不稳定的部分，在阿蒙森海地区尤其脆弱，那里的冰川正在以惊人的速度融化。远场海平面数据和冰盖模型表明，至少在第四纪晚期发生了一次主要的 WAIS 解体，但近冰地质档案中过去崩塌的直接证据仍然难以捉摸。为了便于对流入阿蒙森海的两个最重要的冰川，即松岛冰川 (PIG) 和思韦茨冰川 (TG) 进行地球化学和矿物学追踪，我们在此提供了对 26 个海底表层沉积物样本的首次多代理来源分析来自松岛湾。我们的数据表明，对于所研究的所有粒度和代理，PIG 和 TG 提供的碎屑指纹在两个冰流系统的冰架前沿附近明显不同。PIG 提供的冰川碎屑的特征是低 eNd 值 (~-9)、高 87Sr/86Sr 比率 (~0.728)、低蒙脱石含量（此处报告的 PIG 和 TG 的地球化学和矿物学指纹为亚冰地质提供了新的见解并允许我们在与未来 50 到 100 年所设想的环境条件更相似的环境条件下，追踪地质历史中的两个排水系统。