Clast rind-paleosol record of the Antarctic early Alpine glaciation

• Published in: Polar Science
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2021
• Subjects: Rind microenvironment; Polar weathering; Rind-paleosol record; Cold-humid to cold-dry Antarctic transition; Antarctic; The Antarctic; East Antarctica; Antarc*; Antarctica; Ice Sheet; Polar Science; Tundra
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=16484; http://id.nii.ac.jp/1291/00016355/

The early Alpine glaciation is known from few sources detailing initial growth of ice either during the late Oligocene or early Miocene, localities limited to high summits of East Antarctica. The Ant-831 paleosol, developed in moraine emplaced during the Alpine event, has been studied with respect to its pedogenesis and to rinds recovered from its pebble pavement. This pedostratigraphic section is assigned a late Oligocene/early Miocene age on the basis of its fossil Coleoptera fauna and tundra vegetation, Fe/Al relative-age-dating parameters, and extensive pebble clast weathering. SEM, XRD and XRF analyses of rind specimens from the pebble pavement yield new information on the weathering history of the Beacon sandstone and its link to a juxtaposed paleosol. The paleosol provides a mirror image to weathering zones in pavement clasts, the salt-rich zones interpreted to have formed during the cold-dry paleoclimate of the post-Middle Miocene Climatic Optimum (MMCO ~15 Ma) following a stronger oxidizing paleoclimate of the earlier cold-wet phase of the Alpine glaciation. Essentially this database provides a 30-Myr window into the weathering progression from inception of the Alpine glaciation, through the warmer MMCO dated to ~15 Ma, to the onset of cold-dry conditions that brought on the later development of the Inland Ice Sheet.