Ice-free valleys in the Neptune Range of the Pensacola Mountains, Antarctica: glacial geomorphology, geochronology and potential as palaeoenvironmental archives

Small, David; Bentley, Michael J.; Evans, David J.A.; Hein, Andrew S.; Freeman, Stewart P.H.T.

Abstract

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.

Citation

Small, D., Bentley, M. J., Evans, D. J., Hein, A. S., & Freeman, S. P. (2021). Ice-free valleys in the Neptune Range of the Pensacola Mountains, Antarctica: glacial geomorphology, geochronology and potential as palaeoenvironmental archives. Antarctic Science, 33(4), 428-455. https://doi.org/10.1017/s0954102021000237

• Journal Article Type: Article
• Online Publication Date: Jul 5, 2021
• Publication Date: 2021-08
• Deposit Date: Aug 24, 2021
• Publicly Available Date: Aug 24, 2021
• Journal: Antarctic Science
• Print ISSN: 0954-1020
• Electronic ISSN: 1365-2079
• Publisher: Cambridge University Press
• Peer Reviewed: Peer Reviewed
• Volume: 33
• Issue: 4
• Pages: 428-455
• DOI: https://doi.org/10.1017/s0954102021000237
• Public URL: https://durham-repository.worktribe.com/output/1266170