Browsing by Author "Quigley, M"

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    Cosmogenic evidence for limited local LGM glacial expansion, Denton Hills, Antarctica
    (Elsevier, 2017-12-15) Joy, K; Fink, D; Storey, BC; De Pascale, GP; Quigley, M; Fujioka, T
    The geomorphology of the Denton Hills provides insight into the timing and magnitude of glacial retreats in a region of Antarctica isolated from the influence of the East Antarctic ice sheet. We present 26 Beryllium-10 surface exposure ages from a variety of glacial and lacustrine features in the Garwood and Miers valleys to document the glacial history of the area from 10 to 286 ka. Our data show that the cold-based Miers, Joyce and Garwood glaciers retreated little since their maximum positions at 37.2 ± 6.9 (1σ n = 4), 35.1 ± 1.5 (1σ, n = 3) and 35.6 ± 10.1 (1σ, n = 6) ka respectively. The similar timing of advance of all three glaciers and the lack of a significant glacial expansion during the global LGM suggests a local LGM for the Denton Hills between ca. 26 and 51 ka, with a mean age of 36.0 ± 7.5 (1σ, n = 13) ka. A second cohort of exposure ages provides constraints to the behaviour of Glacial Lake Trowbridge that formerly occupied Miers Valley in the late Pleistocene. These data show active modification of the landscape from ∼20 ka until the withdrawal of ice from the valley mouths, and deposition of Ross Sea Drift, at 10–14 ka. © 2017 Elsevier Ltd.
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    Quantifying the response of Australian landscapes to climatic and tectonic forcing using cosmogenic isotope analysis
    (18th INQUA Congress, 2011-07-21) Fink, D; Quigley, M; Kohn, BP
    Cosmogenic 10Be concentrations in earth surface materials offer novel information on the rate and spatial patterns of bedrock erosion and basin-wide sediment generation which together influence continental denudation. This opens an opportunity to address the vexing question of how continental landscapes respond to climate and tectonic forcing. One hypothesis is that for equivalent long-term climatic variables, variations in tectonic activity will be reflected in bedrock and sediment 10Be concentrations such that more tectonically active landscapes will yield mean lower 10Be concentrations. We test this hypothesis across the Australian continent by sampling non-glaciated bedrock outcrops and stream sediments from 4 selected ‘end-member’ regions of contrasting climatic (large precipitation, temperature gradients) and tectonic (fault deformation, paleo-earthquake activity) variables with similar granitic lithologies. Localities included tropical northern Queensland and west coast Tasmania (>3000 mm/y), contrasting with late Quaternary neo-tectonically modified regions of the Flinders Ranges, South Australia (<200 mm/y), and tectonically passive but arid Port Hedland and the Darling Scarp, WA. Preliminary cosmogenic-derived erosion rates in regions proximal to active faults with surface ruptures in the last 100 kyr are 1-2 orders of magnitude higher than erosion rates in tectonically inactive regions, implying co-seismic rock fracturing and mass movement exert first order control on bedrock erosion rates on the 100 kyr timescale. Erosion rates derived from subhorizontal bedrock surfaces (and associated stream sediments) spanning Australia's most diverse climates with respect to annual precipitation and temperature gradients are typically <5 m/Ma, implying minimal climatic control on weathering of non-soil mantled bedrock. Cosmogenic nuclide data from across the continent provide quantitative evidence for strong tectonic and weak climatic influence on bedrock erosion. Copyright (c) 2011 INQUA 18