Late Pleistocene glaciation of the Mt Giluwe volcano,Papua New Guinea |
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| Authors: | Timothy T Barrows Geoffrey S Hope Michael L Prentice L Keith Fifield Stephen G Tims |
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| Institution: | 1. UMR 7209, Archéozoologie, Archéobotanique: Sociétés, Pratiques et Environnements, CNRS, MNHN, Sorbonne-Universités, 55 Rue Buffon, 75005 Paris, France;2. School of Culture, History and Language, College of Asia & the Pacific, Australian National University, Canberra, ACT 2601, Australia;3. UMR 7041, ArScAn - Ethnologie Préhistorique, Maison de l''Archéologie et de l''Ethnologie René Ginouvès, CNRS, 21, Allée de l''Université, 92023 Nanterre Cedex, France;4. School of Archaeology and Anthropology, College of Arts and Social Sciences, Australian National University, Canberra, ACT 2601, Australia;5. UFR 03, Histoire de l''Art et Archéologie, Université Paris 1 Panthéon-Sorbonne, 3, Rue Michelet, 75006 Paris, France |
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| Abstract: | The Mt Giluwe shield volcano was the largest area glaciated in Papua New Guinea during the Pleistocene. Despite minimal cooling of the sea surface during the last glacial maximum, glaciers reached elevations as low as 3200 m. To investigate changes in the extent of ice through time we have re-mapped evidence for glaciation on the southwest flank of Mt Giluwe. We find that an ice cap has formed on the flanks of the mountain on at least three, and probably four, separate occasions. To constrain the ages of these glaciations we present 39 new cosmogenic 36Cl exposure ages complemented by new radiocarbon dates. Direct dating of the moraines identifies that the maximum extent of glaciation on the mountain was not during the last glacial maximum as previously thought. In conjunction with existing potassium/argon and radiocarbon dating, we recognise four distinct glacial periods between 293–306 ka (Gogon Glaciation), 136–158 ka (Mengane Glaciation), centred at 62 ka (Komia Glaciation) and from >20.3–11.5 ka (Tongo Glaciation). The temperature difference relative to the present during the Tongo Glaciation is likely to be of the order of at least 5 °C which is a minimum difference for the previous glaciations. During the Tongo Glaciation, ice was briefly at its maximum for less than 1000 years, but stayed near maximum levels for nearly 4000 years, until about 15.4 ka. Over the next 4000 years there was more rapid retreat with ice free conditions by the early Holocene. |
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