A geomorphology based reconstruction of ice volume distribution at the Last Glacial Maximum across the Southern Alps of New ZealandS

QUATERNARY SCIENCE REVIEWS

卷:219

Article

James, William H. M.^1,2  Carrivick, Jonathan L.^1,3  Quincey, Duncan J.^1,3  Glasser, Neil F.⁴ 

[1] Univ Leeds, Sch Geog, Leeds LS2 9JT, W Yorkshire, England

[2] Univ Leeds, Leeds Inst Data Analyt, Leeds LS2 9JT, W Yorkshire, England

[3] Univ Leeds, Water Leeds, Leeds LS2 9JT, W Yorkshire, England

[4] Aberystwyth Univ, Dept Geog & Earth Sci, Aberystwyth SY23 3DB, Dyfed, Wales

关键词: Geomorphology;    Glacial;    Glaciation;    Glaciology;    Quaternary;    Southern pacific;   

DOI  :  10.1016/j.quascirev.2019.06.035

来源: Elsevier

【 摘 要 】

We present a 3D reconstruction of ice thickness distribution across the New Zealand Southern Alps at the Last Glacial Maximum (LGM, c. 30-18 ka). To achieve this, we used a perfect plasticity model which could easily be applied to other regions, hereafter termed REVOLTA (Reconstruction of Volume and Topography Automation). REVOLTA is driven by a Digital Elevation Model (DEM), which was modified to best represent LGM bed topography. Specifically, we removed contemporary ice, integrated offshore bathymetry and removed contemporary lakes. A review of valley in-fill sediments, uplift and denudation was also undertaken. Down-valley ice extents were constrained to an updated geo-database of LGM ice limits, whilst the model was tuned to best-fit known vertical limits from geomorphological and geochronological dating studies. We estimate a total LGM ice volume of 6,800 km(3), characterised predominantly by valley style glaciation but with an ice cap across Fiordland. With a contemporary ice volume of approximately 50 km(3), this represents a loss of 99.25% since the LGM. Using the newly created ice surface, equilibrium line altitudes (ELAs) for each glacier were reconstructed, revealing an average ELA depression of approximately 950 m from present. Analysis of the spatial variation of glacier-specific ELAs and their depression relative to today shows that whilst an east-west ELA gradient existed during the LGM it was less pronounced than at present. The reduced ELA gradient is attributed to an overall weakening of westerlies, a conclusion consistent with those derived from the latest independent climate models. (C) 2019 The Authors. Published by Elsevier Ltd.

【 授权许可】

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