We describe the glacial geomorphology and initial geochronology of two ice-free valley systems within the Neptune Range of the Pensacola Mountains, Antarctica. These valleys are characterized by landforms associated with formerly more expanded ice sheet(s) that were at least 200 m thicker than at present. The most conspicuous features are areas of supraglacial debris, discrete debris accumulations separated from modern-day ice and curvilinear ridges and mounds. The landsystem bears similarities to debris-rich cold-based glacial landsystems described elsewhere in Antarctica and the Arctic where buried ice is prevalent. Geochronological data demonstrate multiple phases of ice expansion. The oldest, occurring > 3 Ma, overtopped much of the landscape. Subsequent, less expansive advances into the valleys occurred > 2 Ma and > ~1 Ma. An expansion of some local glaciers occurred < 250 ka. This sequence of glacial stages is similar to that described from the northernmost massif of the Pensacola Mountains (Dufek Massif), suggesting that it represents a regional signal of ice-sheet evolution over the Plio-Pleistocene. The geomorphological record and its evolution over millions of years makes the Neptune Range valleys an area worthy of future research and we highlight potential avenues for this.

中文翻译：

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南极洲彭萨科拉山脉海王星山脉的无冰山谷：冰川地貌、地质年代学和作为古环境档案的潜力

我们描述了南极洲彭萨科拉山脉海王星范围内两个无冰山谷系统的冰川地貌和初始年代学。这些山谷的特征是与以前更膨胀的冰盖相关的地形，这些冰盖比现在厚至少 200 m。最显着的特征是冰上碎片区域、与现代冰分离的离散碎片堆积以及曲线脊和土丘。该陆地系统与南极洲和北极其他地方描述的富含碎片的寒冷冰川陆地系统具有相似之处，那里普遍存在埋冰。年代学数据显示了冰膨胀的多个阶段。最古老的，发生 > 3 Ma，超过了大部分景观。随后，在 > 2 Ma 和 > ~1 Ma 时，向山谷中进行了较小的扩张。一些当地冰川的扩张发生 < 250 ka。这一冰川阶段序列与彭萨科拉山脉最北端地块（Dufek Massif）所描述的相似，这表明它代表了上上更新世冰盖演化的区域信号。数百万年的地貌记录及其演变使海王星山脉山谷成为值得未来研究的区域，我们强调了这方面的潜在途径。