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The last forests on Antarctica: reconstructing flora and temperature from the Neogene Sirius Group, Transantarctic Mountains

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Author(s)

Rhian L. Rees-Owen, Fiona L. Gill, Robert J. Newton, Ruza F. Ivanovic, Jane E. Francis, James B. Riding, Christopher H. Vane, Raquel A. Lopes dos Santos

School/Research organisations

Abstract

Fossil-bearing deposits in the Transantarctic Mountains, Antarctica indicate that, despite the cold nature of the continent’s climate, a tundra ecosystem grew during periods of ice sheet retreat in the mid to late Neogene (17–2.5 Ma), 480 km from the South Pole. To date, palaeotemperature reconstruction has been based only on biological ranges, thereby calling for a geochemical approach to understanding continental climate and environment. There is contradictory evidence in the fossil record as to whether this flora was mixed angiosperm-conifer vegetation, or whether by this point conifers had disappeared from the continent. In order to address these questions, we have analysed, for the first time in sediments of this age, plant and bacterial biomarkers in terrestrial sediments from the Transantarctic Mountains to reconstruct past temperature and vegetation during a period of East Antarctic Ice Sheet retreat. From tetraether lipids (MBT’/CBT palaeothermometer), we conclude that the mean continental summer temperature was ca. 5 °C, in agreement with previous reconstructions. This was warm enough to have allowed woody vegetation to survive and reproduce even during the austral winter. Biomarkers from vascular plants indicate a low diversity and spatially variable flora consisting of higher plants, moss and algal mats growing in microenvironments in a glacial outwash system. Abietane-type compounds were abundant in some samples, indicating that conifers, most likely Podocarpaceae, grew on the Antarctic continent well into the Neogene. This is supported by the palynological record, but not the macrofossil record for the continent, and has implications for the evolution of vegetation on Antarctica.
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Details

Original languageEnglish
Pages (from-to)4-14
JournalOrganic Geochemistry
Volume118
Early online date12 Jan 2018
DOIs
Publication statusPublished - Apr 2018

    Research areas

  • Antarctica, Neogene, Sirius Group, Terpenoid, GDGT, Palaeovegetation, Palaeotemperature, Palaeoenvironment

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