First Cenozoic glaciers in West Antarctica

• Main Authors: Krzysztof Birkenmajer, Andrzej Gaździcki, Krzysztof P. Krajewski, Instytut Nauk Geologicznych, Uniwersytet Wrocławski, Pl. Maksa Borna, Centrum Badań Ekologicznych, Polska Akademia Nauk, Ul. Konopnickiej
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: Key words; Antarctica; King George Island; Eocene; mountain glaciers; Admiralty Bay; Antarctic; Antarctic Peninsula; Breccia Crag; Hervé Cove; Point Thomas; South Shetland Islands; The Antarctic; West Antarctica; Antarc*; Ice Sheet
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.630.7803; http://www.polar.pan.pl/ppr26/ppr26-003.pdf

Abstract: One of the most significant global climatic events in the Cenozoic was the transi− tion from greenhouse to icehouse conditions in Antarctica. Tectonic evolution of the region and gradual cooling at the end of Eocene led to the first appearance of ice sheets at the Eocene/Oligocene boundary (ca. 34 Ma). Here we report geological record of mountain gla− ciers that preceded major ice sheet formation in Antarctica. A terrestrial, valley−type tillite up to 65 metres thick was revealed between two basaltic lava sequences in the Eocene– Oligocene Point Thomas Formation at Hervé Cove – Breccia Crag in Admiralty Bay, King George Island, South Shetland Islands. K−Ar dating of the lavas suggests the age of the gla− ciation at 45–41 Ma (Middle Eocene). It is the oldest Cenozoic record of alpine glaciers in West Antarctica, providing insight into the onset of glaciation of the Antarctic Peninsula and South Shetland Islands.