Deglaciation and weathering of Larsemann Hills, East Antarctica

Abstract

Abstract:In situ cosmogenic 10 Be exposure dating, radiocarbon determinations, salt and sediment geochemistry, and rock weathering observations indicate that parts of Larsemann Hills, East Antarctica have been subaerially exposed throughout much of the last glacial cycle, with the last glaciation occurring prior to 100 ka BP. Salt-enhanced subaerial weathering, coupled with a paucity of glacial erratics, made exposure age dating challenging. Rapid subaerial surface lowering in some places means that some exposure ages may underestimate the true age of deglaciation. Despite this uncertainty, the data are consistent with the absence of overriding by a thick ice sheet during the Last Glacial Maximum ,20-18 ka BP.

Late Quaternary glacial history constrains glacio-isostatic rebound in Enderby Land, East Antarctica

“…The surface of the clasts and bedrock had not been strongly oxidized but was instead weathered through granular disintegration and had significant tafoni development. Weathering characteristics of both bedrock and erratics were similar to that observed in areas affected by sea spray or downwind of hypersaline lakes in the coastal oases of Princess Elizabeth Land [ Gore et al ., ; Gore and Colhoun , ; Kiernan et al ., ]. Unlike at CHU and CHL, here, the two erratics (DDI‐1 at 9.1 ka and DDI‐2 at 8.8 ka) gave identical exposure ages as for the sampled adjacent bedrock (DDI‐3, 8.4 ka).…”

Evaluation of Mumiyo Deposits From East Antarctica as Archives for the Late Quaternary Environmental and Climatic History

“…The n-alcohols (FAlc) were LGM and MIS3 polynyas Figure 1. Modern distribution of snow petrel breeding colonies (Croxall et al, 1995;Goldsworthy & Thomson, 2000;Steele & Newton, 1995) and locations of 14 C-dated mumiyo deposits (Hiller et al, 1988;Kiernan et al, 2002;Kiernan et al, 2009;Mackintosh et al, 2011;Melles et al, 1997;Ryan et al, 1992;Steele & Hiller, 1997;Thor & Low, 2011;Verkulich & Hiller, 1994;Wand & Hermichen, 2005). SR = Shackleton Range; PMR = Petermann Range; PCM = Prince Charles Mountains.…”

“…The 14 C ages of mumiyo deposits provide age constraints on the timing of deglaciation or inundation of terrestrial sites, since mumiyo deposition at a given time implies subaerial exposure, that is, neither ice or snow coverage nor flooding by lake or ocean (e.g., Kiernan et al, ; Wand & Hermichen, ), and thereby can complement exposure dating of glacial erratics and landforms in Antarctica (Mackintosh et al, ). In currently unglaciated coastal areas of East Antarctica, like Bunger Hills, Vestfold Hills, and Larsemann Hills, as well as from more inland sites in the Prince Charles Mountains and Shackleton Range, mumiyo ages indicate a snow petrel colonization predominantly during the Holocene, following local deglaciation (e.g., Ainley et al, ; Hiller et al, ; Kiernan et al, , ; Mackintosh et al, ; Verkulich & Hiller, ; Figure ). Mumiyo ages of up to 37 thousand years before present (ka) were found in the mountain ranges of western and central Dronning Maud Land (DML), indicating snow petrel occupation and of ice‐free sites during the late Pleistocene (Hiller et al, , ; Steele & Hiller, ; Thor & Low, ; Figure ).…”

Soils of MacRobertson Land

“…5.1). These coastal areas are deeply dissected by short (up to 1 km) valleys that formed along structural lineaments, particularly joints, in response to erosion by ice and water (Adamson and Pickard 1986;Kiernan et al 2009). These "inter-hill valleys" are the major structural unit of the Vestfold and Larsemann Hills (Fig.…”

“…Both areas have hundreds of freshwater lakes. 10 Be exposure dating, radiocarbon determinations, salt and sediment geochemistry, and rock weathering observations indicate that parts of Larsemann Hills were subaerially exposed throughout much of the last glacial cycle, with the last glaciation occurring prior to 100 ka BP (Kiernan et al 2009). Periglacial thermokarst landforms are common in both areas, including thaw pits, thaw lakes, ground ice slumps, linear depressions, and small-scale beaded drainage features (Kiernan et al 1999).…”