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

R.L.R.O. thanks the Natural Environmental Research Council (NERC) for supporting her PhD studentship (NE/K500847/1) and BGS for CASE support. R.I. was supported by a NERC Independent Fellowship (NE/K008536/1). F.L.G was supported by a Royal Society Dorothy Hodgkin Fellowship. Fossil-bearing deposits...

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Bibliographic Details
Published in:Organic Geochemistry
Main Authors: Rees-Owen, Rhian L., Gill, Fiona L., Newton, Robert J., Ivanovic, Ruza F., Francis, Jane E., Riding, James B., Vane, Christopher H., Lopes dos Santos, Raquel A.
Other Authors: University of St Andrews. School of Earth & Environmental Sciences
Format: Article in Journal/Newspaper
Language:English
Published: 2018
Subjects:
Antarctica
Neogene
Sirius Group
Terpenoid
GDGT
Palaeovegetation
Palaeotemperature
Palaeoenvironment
GE Environmental Sciences
QE Geology
QD Chemistry
NDAS
SDG 15 - Life on Land
GE
QE
QD
Antarctic
Austral
East Antarctic Ice Sheet
Sirius
South Pole
The Antarctic
Transantarctic Mountains
Antarc*
Ice Sheet
South pole
Tundra
Online Access:http://hdl.handle.net/10023/12701
https://doi.org/10.1016/j.orggeochem.2018.01.001
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Summary:R.L.R.O. thanks the Natural Environmental Research Council (NERC) for supporting her PhD studentship (NE/K500847/1) and BGS for CASE support. R.I. was supported by a NERC Independent Fellowship (NE/K008536/1). F.L.G was supported by a Royal Society Dorothy Hodgkin Fellowship. 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. Publisher PDF Peer reviewed

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