Browsing by Author "Winkler, S"

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    A bright future for accelerator science at ANSTO
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2009-11-25) Hotchkis, MAC; Child, DP; Cohen, DD; Dodson, JR; Fink, D; Garton, D; Hua, Q; Ionescu, M; Jacobsen, GE; Levchenko, VA; Mifsud, C; Siegele, R; Smith, AM; Williams, AG; Winkler, S
    In the May 2009 budget, the Federal Government announced funding of $25m to ANSTO through the Education Investment Fund, to build state-of-the-art applied accelerator science facilities, by upgrading and replacing existing facilities and laboratories at ANSTO. Currently, ANSTO's researchers, jointly with researchers from all 37 Australian universities, plus other agencies such as CSIRO, government departments and local government bodies, and overseas collaborators and customers, use ANSTO's accelerator facilities for analysis of a wide range of materials, predominantly by Accelerator Mass Spectrometry (AMS) and Ion Beam Analysis (IBA). There are >100 external users of those facilities every year. © 2009 AINSE
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    Comment on Barrell et al. “Reconciling the onset of deglaciation in the Upper Rangitata valley, Southern Alps, New Zealand” (Quaternary Science Reviews 203 (2019), 141–150.)
    (Elsevier, 2019-09-01) Shulmeister, J; Fink, D; Winkler, S; Thackray, GD; Borsellino, R; Hemmingsen, M; Rittenour, TM
    Recently, Barrell et al. (2019) published an article that responded to our article (Shulmeister et al., 2018a) on gradual evacuation of ice from the Upper Rangitata Valley, South Island, New Zealand, during the last glaciation. They base their contrasting interpretation of substantial and rapid ice-lowering of Rangitata glacier shortly after 18 ka on a revision of our 10Be cosmogenic radionuclide (CRN) chronology and by reference to published sources (e.g. Mabin, 1980, 1987). Their interpretation relies on glacial landform features extracted from a geomorphology map of the central Southern Alps by Barrell et al. (2011). Barrell et al. (2019) highlight that rapid ice recession of the Rangitata glacier is compatible to their results from Mackenzie Basin and Rakaia Valley (Putnam et al., 2013a, b). We highlight four points in response to Barrell et al. (2019). © 2019 Elsevier Ltd.
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    Corrigendum to “Evidence for slow late-glacial ice retreat in the upper Rangitata Valley, South Island, New Zealand” [Quat. Sci. Rev. 185 (2018) 102–112]
    (Elsevier, 2019-09-01) Shulmeister, J; Fink, D; Winkler, S; Thackray, GD; Borsellino, R; Hemmingsen, M; Rittenour, TM
    It has been brought to our attention, following a recent publication by Barrell et al. (2019), that the elevations for 12 of 23 boulders reported in our publication, Shulmeister et al., v185, 102–112 (2018) are incorrect. For these 12 samples, the true elevations are higher and hence all exposure ages based on their respective 10Be concentration measurements require a downward correction of between 10 and 15%. This change in age does not alter our main conclusions but does have some implication for the initiation and pace of deglaciation. © 2019 Elsevier Ltd.
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    Evidence for slow late-glacial ice retreat in the upper Rangitata Valley, South Island, New Zealand
    (Elsevier, 2018-04-01) Shulmeister, J; Fink, D; Winkler, S; Thackray, GD; Borsellino, R; Hemmingsen, M; Rittenour, TM
    A suite of cosmogenic radionuclide ages taken from boulders on lateral and latero-terminal moraines in the Rangitata Valley, eastern South Island, New Zealand demonstrates that relatively thick ice occupied valley reaches inland of the Rangitata Gorge until c. 21 ka. Thereafter ice began to thin, and by c. 17 ka it had retreated 33 km up-valley of the Rangitata Gorge to the Butler-Brabazon Downs, a structurally created basin in the upper Rangitata Valley. Despite its magnitude, this retreat represents a minor ice volume reduction from 21 ka to 17 ka, and numerous lateral moraines preserved suggest a relatively gradual retreat over that 4 ka period. In contrast to records from adjacent valleys, there is no evidence for an ice-collapse at c. 18 ka. We argue that the Rangitata record constitutes a more direct record of glacial response to deglacial climate than other records where glacial dynamics were influenced by proglacial lake development, such as the Rakaia Valley to the North and the major valleys in the Mackenzie Basin to the south-west. Our data supports the concept of a gradual warming during the early deglaciation in the South Island New Zealand. © 2018 Elsevier Ltd.
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    GRACE satellite data and cosmogenic exposure ages in Enderby Land, Antarctica: ice mass increase or uncorrected post-glacial rebound?
    (Copernicus Publications, 2010-05-02) White, D; Fink, D; Winkler, S
    Measuring present day changes in the volume of the Antarctic ice sheet has traditionally been difficult, due to its remote nature and vast size. Over the past decade, the GRACE (Gravity Recovery and Climate Experiment) and ICEsat (Ice, Cloud and land Elevation) satellite systems have vastly improved these measurements by accurately measuring changes in the gravity exerted by the ice sheet, and the ice sheet surface height respectively. However, data sets from both these systems require various corrections related to an understanding of the rate of post-glacial rebound across the continent in order to make accurate measurements of ice loss or gain. GRACE measurements have consistently observed a substantial apparent gain in ice mass in the Enderby Land region of East Antarctica (e.g. Chen et al., 2006). This large region has until recently been given little attention and there is an absence of detailed geomorphic and geologic studies with no present-day assessment of uplift. This in turn places some doubt on the implications of the Enderby Land GRACE data and its relationship to modern day climate change. To address this problem, a reconnaissance survey to the Rayner Glacier region in Enderby Land was conducted during Polarstern Cruise ANT XXIII/9 in 2007. Observations of relatively unweathered erratics on Demidov Island and the Condon Hills provided strong evidence that the Rayner Glacier has lowered by at least 400 m, and retreated by at least 10 km during the late Quaternary. 10Be and 26Al dating of erratics and bedrock collected from three sites during this survey indicate that this deglaciation occurred early in the Holocene (~7 to 9 ka BP), and that ice retreat and lowering were effectively synchronous. The timing of this deglaciation is about the same as that used to model the post-glacial rebound in previous GRACE measurements (Ivins and James, 2005). However, these models assumed as little as 1-200 m of ice loss at this time, which is much less than that observed in the field. Thus, it is likely that the post-glacial rebound model underestimates the required correction in this area. This in turn, will mean that the overall rate of mass loss calculated by GRACE measurements that have been corrected using the Ivins and James post-glacial rebound model will underestimate the true rate of modern ice loss in East Antarctica.