Constraining past West Antarctic Ice Sheet (WAIS) change helps validate numerical models simulating future ice sheet dynamics. Following rapid deglaciation during the mid-Holocene, ice near Thwaites Glacier was ∼35 m thinner than present; however, the timing of ice regrowth to its present configuration remains unknown. To fill this knowledge gap, we present cosmogenic nuclide exposure ages of cobbles from the surface of a moraine situated between Thwaites and Pope glaciers. We infer that the moraine formed and stabilized in the Late Holocene (∼1.4 ka) when a small glacier thickened. We also present a novel reconstruction of WAIS volume constrained by sea-level data, which demonstrates that moraine formation coincided with a large-scale WAIS readvance. Our new geologic constraints will help inform models of the solid Earth response to surface mass loading, improving our understanding of ice sheet dynamics in a vulnerable part of WAIS.

中文翻译：

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南极洲阿蒙森海海湾全新世晚期冰层增厚时间的直接地质制约因素


约束过去的南极西部冰盖 （WAIS） 变化有助于验证模拟未来冰盖动力学的数值模型。在全新世中期快速消融之后，斯韦茨冰川附近的冰比现在薄了 ∼35 m;然而，冰再生到目前配置的时间仍然未知。为了填补这一知识空白，我们提出了位于 Thwaites 和 Pope 冰川之间的冰碛表面鹅卵石的宇宙成因核素暴露年龄。我们推断，冰碛形成并稳定在全新世晚期 （∼1.4 ka），当时一个小冰川变厚。我们还提出了一种受海平面数据限制的 WAIS 体积的新重建，这表明冰碛的形成与大规模 WAIS 重新前进相吻合。我们新的地质约束将有助于为固体地球对表面质量载荷的响应模型提供信息，从而提高我们对 WAIS 脆弱部分冰盖动力学的理解。