近日，日本富山大学Keiji Horikawa团队研究了上新世时期西南极思韦茨冰川与松岛冰川的多次大规模内陆退缩。这一研究成果发表在2025年12月22日出版的《美国科学院院刊》杂志上。

西南极冰盖（WAIS）的稳定性对预测未来海平面上升至关重要，但目前正受到南太平洋海域海洋热力融化作用的威胁。尽管部分地质记录与冰盖模型显示，WAIS在过去的温暖期曾发生退缩，但仍缺乏可靠数据来界定其退缩范围。最近，在国际大洋发现计划（IODP）阿蒙森海陆隆的U1532站点钻取的沉积物中，碎屑Nd、Sr和Pb同位素数据揭示了上新世（533万至258万年前，该时期气候较现今温暖）冰期-间冰期旋回中沉积物物源的多次交替变化。这些变化反映了西南极冰盖在南极大陆上的大规模波动范围。

在冰期起始阶段（388万、360万和333万年前）沉积物中发现的独特高Pb/低εNd特征，被认为来源于西南极内陆深成岩的碎屑供给。其在U1532站点的同位素特征表明，在之前的间冰期，WAIS曾发生大规模的内陆退缩。在间冰期鼎盛阶段，冰缘向内陆退缩，冰山携带内陆来源的碎屑跨越阿蒙森海陆架超过500公里，进行漂运和沉积。随后，接地冰的再度前进将这些内陆来源的细粒沉积物从陆架“推挤”至大陆坡和陆隆区，导致陆隆沉积物中出现高Pb/低εNd峰值。研究组连续的上新世记录为WAIS至少五次主要的内陆退缩事件提供了决定性证据，凸显了WAIS对当前气候变暖的显著脆弱性。

附：英文原文

Title: Repeated major inland retreat of Thwaites and Pine Island glaciers (West Antarctica) during the Pliocene

Author: Horikawa, Keiji, Iwai, Masao, Hillenbrand, Claus-Dieter, Siddoway, Christine S., Halberstadt, Anna Ruth, Cowan, Ellen A., Penkrot, Michelle L., Gohl, Karsten, Wellner, Julia S., Asahara, Yoshihiro, Shin, Ki-Cheol, Noda, Masahiro, Fujimoto, Miyu, null, null, Gohl, Karsten, Wellner, Julia S., Klaus, Adam, Kulhanek, Denise, Bauersachs, Thorsten, Bohaty, Steven M., Courtillat, Margot, Cowan, Ellen A., De Lira Mota, Marcelo A., Esteves, Mariana S.R., Fegyveresi, John M., Frederichs, Thomas, Gao, Liang, Halberstadt, Anna Ruth, Hillenbrand, Claus-Dieter, Iwai, Masao, Kim, Ji-Hoon, King, Theresa M., Klages, Johann P., Passchier, Sandra, Penkrot, Michelle L., Prebble, Joseph G., Rahaman, Waliur, Reinardy, Benedict T.I., Renaudie, Johan, Robinson, Delaney E., Scherer, Reed P., Siddoway, Christine S., Wu, Li, Yamane, Masako

Issue&Volume: 2025-12-22

Abstract: The stability of the West Antarctic Ice Sheet (WAIS), crucial for predicting future sea-level rise, is threatened by ocean-forced melting in the Pacific sector of the Southern Ocean. While some geological records and ice-sheet models suggest WAIS retreat during past warm periods, reliable data constraining the extent of retreat are lacking. Detrital Nd, Sr, and Pb isotope data of sediments recently drilled at International Ocean Discovery Program (IODP) Site U1532 on the Amundsen Sea continental rise manifest repeated alternations in sediment provenance during glacial–interglacial cycles of the Pliocene (5.33 to 2.58 Mya), a time warmer than present. The variations reflect large fluctuations in WAIS extent on the Antarctic continent. A unique high Pb/low εNd signature of sediments found at the onset of glacial intervals (3.88, 3.6, and 3.33 Ma) is attributed to the supply of detritus sourced from plutonic rocks located in the West Antarctic interior. Its isotopic signature at Site U1532 indicates major inland retreat of the WAIS during the preceding interglacials. During peak interglacials, the ice margin had retreated inland, and icebergs rafted and deposited inland-sourced detritus over 500 km across the Amundsen Sea shelf. Subsequent readvance of grounded ice then “bulldozed” these inland-derived fine-grained sediments from the shelf down to the continental slope and rise, resulting in a high Pb/low εNd peak in the rise sediments. Our continuous Pliocene records provide conclusive evidence for at least five major inland retreat events of the WAIS, highlighting the significant vulnerability of the WAIS to ongoing warming.

DOI: 10.1073/pnas.2508341122

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2508341122