Cenozoic vegetation history and climate, Ross Sea Region, Antarctica - Palynological results

Category Other
Group GSI.IR
Location International Geological Congress,oslo 2008
Author Raine, James Ian۱; Ashworth, A.C.۲; Askin, R.A.۳; Mildenhall, D.C.۱; Prebble, J.G.۴
Holding Date 07 October 2008

Spores and pollen from ANDRILL-1B, Cape Roberts Project and CIROS-1 drillholes, McMurdo Sound glacial erratics, and Sirius Group outcrop at Beardmore Glacier and McMurdo Dry Valleys provide a picture of the vegetation of coastal Victoria Land from mid-Eocene to Middle Miocene. Progressive loss of mesothermal and appearance of microthermal taxa are consistent with increasing intensity of glaciation recorded in the sediments. Middle to Late Eocene spore-pollen assemblages are characterized by diverse and common pollen of Nothofagus, along with podocarps, diverse Proteaceae and other angiosperms, and rare cryptogam spores, and reflect a temperate Nothofagus-broadleaf-podocarp forest. The Early Oligocene saw a reduction in diversity, with loss of most ferns, some podocarpaceous conifers, Nothofagus (Brassospora), Casuarina, and many Proteaceae,. Early Oligocene vegetation likely resembled present-day Magellanic Nothofagus woodland, with cold temperate to periglacial climatic conditions. Late Oligocene and Early Miocene assemblages from drillholes are typified by Nothofagus and podocarp conifers, with distinctive angiosperms and bryophytes comprising a new and increasing component. Similar mid-Miocene Sirius Group palynofloras and plant macrofossils represent mossy tundra vegetation, with woodland in more protected locations, and a more severe climate than that of the Early Oligocene. Tundra apparently disappeared with onset of more severe glaciation c.14 Ma.