Major middle Miocene global climate change: Evidence from East Antarctica and the Transantarctic Mountains

Abstract

Research Article| November 01, 2007 Major middle Miocene global climate change: Evidence from East Antarctica and the Transantarctic Mountains A.R. Lewis; A.R. Lewis 1Department of Earth Sciences, Boston University, Boston, Massachusetts 02215, USA Search for other works by this author on: GSW Google Scholar D.R. Marchant; D.R. Marchant 1Department of Earth Sciences, Boston University, Boston, Massachusetts 02215, USA Search for other works by this author on: GSW Google Scholar A.C. Ashworth; A.C. Ashworth 2Department of Geosciences, North Dakota State University, Fargo, North Dakota 58105, USA Search for other works by this author on: GSW Google Scholar S.R. Hemming; S.R. Hemming 3Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA Search for other works by this author on: GSW Google Scholar M.L. Machlus M.L. Machlus 3Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York 10964, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2007) 119 (11-12): 1449–1461. https://doi.org/10.1130/0016-7606(2007)119[1449:MMMGCC]2.0.CO;2 Article history received: 26 Oct 2006 rev-recd: 26 Mar 2007 accepted: 08 May 2007 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation A.R. Lewis, D.R. Marchant, A.C. Ashworth, S.R. Hemming, M.L. Machlus; Major middle Miocene global climate change: Evidence from East Antarctica and the Transantarctic Mountains. GSA Bulletin 2007;; 119 (11-12): 1449–1461. doi: https://doi.org/10.1130/0016-7606(2007)119[1449:MMMGCC]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract We present a glacial record from the western Olympus Range, East Antarctica, that documents a permanent shift in the thermal regime of local glaciers, from wet- to cold-based regimes, more than 13.94 m.y. ago. This glacial record provides the first terrestrial evidence linking middle Miocene global climate cooling to a permanent reorganization of the Antarctic cryosphere and to subsequent growth of the polar East Antarctic Ice Sheet. The composite stratigraphic record constructed from field mapping and analyses of 281 soil excavations shows a classic wet-based till (Circe till, including an extensive melt-out facies), overlain by a weathered colluvial deposit (Electra colluvium), and then a series of stacked tills deposited from cold-based ice (Dido drift). Chronologic control comes from 40Ar/39Ar analyses of concentrated ash-fall deposits interbedded within glacial deposits. The shift from wet- to cold-based glaciation reflects a drop in mean annual temperature of 25–30 °C and is shown to precede one or more major episodes of ice-sheet expansion across the region, the youngest of which occurred between 13.62 and 12.44 Ma. One implication is that atmospheric cooling, following a relatively warm mid-Miocene climatic optimum ca. 17 to 15 Ma, may have led to, and thus triggered, maximum ice-sheet overriding. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.