Differential erosion of a Mesozoic rift flank: Establishing the source of topography across Karrat, central West Greenland

Jess, S., Stephenson, R., Roberts, D. H. and Brown, R. (2019) Differential erosion of a Mesozoic rift flank: Establishing the source of topography across Karrat, central West Greenland. Geomorphology, 334, pp. 138-150. (doi: 10.1016/j.geomorph.2019.02.026)

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The landscape of the Karrat region, central West Greenland, contrasts between high elevation low relief topography, steep sided fjords and deep bathymetric troughs. The mechanisms controlling its formation are highly debated, with initial work suggesting it to be the result of episodic tectonic uplift throughout the late Cenozoic and alternative models implying it is the product of more recent isostatic uplift in response to differential glacial erosion. Here the results of a comprehensive low temperature thermochronological study (apatite fission track and apatite (UTh)/He) and landscape evolution model are presented that helps establish the source of the modern elevated landscape and the region's complex geomorphology. Joint modelling of the apatite fission track and apatite (UTh)/He data outlines two significant periods of cooling, in the Mesozoic and Cenozoic respectively. The first (150 Ma – 110 Ma) correlates to the onset of extension between West Greenland and eastern Canada, suggesting uplift of the region during active rifting, while the second period (50 Ma - 0 Ma) is coeval to the cessation of volcanism in the region and likely represents widespread erosion. These results suggest the basement escarpment likely remained at height during extrusive volcanism and was later uncovered following exhumation of the volcanic succession. Moreover, this latter phase of exhumation is outlined in the results of landscape evolution modelling, implying it likely encompassed localised differential erosion of the volcanic pile, producing a pre-glacial landscape that later aided ice stream onset and the advance of the Uummannaq Ice Stream. Glacial exhumation of the region was likely characterised by differential erosion, shaping the modern geomorphology through preferential ice stream development and isostatic rebound. These results highlight the complex interaction between rift tectonics and surface processes across the Karrat region and adds to a wider understanding of the post-rift evolution of passive continental margins.

Item Type:Articles
Additional Information:The work contained in this publication contains work conducted during a PhD study undertaken as part of the Natural Environment Research Council (NERC) Centre for Doctoral Training (CDT) in Oil and Gas [grant number NEM00578X/1] and is sponsored by the University of Aberdeen.
Glasgow Author(s) Enlighten ID:Brown, Professor Roderick and Jess, Scott
Authors: Jess, S., Stephenson, R., Roberts, D. H., and Brown, R.
College/School:College of Science and Engineering
College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Geomorphology
ISSN (Online):1872-695X
Published Online:04 March 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Geomorphology 334:138-150
Publisher Policy:Reproduced under a Creative Commons License

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