The source of topography across the Cumberland Peninsula, Baffin Island, Arctic Canada: differential exhumation of a North Atlantic rift flank

Jess, S., Stephenson, R., Nielsen, S. and Brown, R. (2019) The source of topography across the Cumberland Peninsula, Baffin Island, Arctic Canada: differential exhumation of a North Atlantic rift flank. Journal of the Geological Society, 176(6), pp. 1093-1106. (doi: 10.1144/jgs2018-211)

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Elevated topography is evident across the continental margins of the Atlantic. The Cumberland Peninsula, Baffin Island, formed as the result of rifting along the Labrador–Baffin margins in the late Mesozoic and is dominated by low-relief high-elevation topography. Apatite fission-track (AFT) analysis of the landscape previously concluded that the area has experienced a differential protracted cooling regime since the Devonian; however, defined periods of cooling and the direct causes of exhumation were unresolved. This work combines the original AFT data with 98 apatite new (U–Th)/He (AHe) ages from 16 samples and applies the newly developed ‘broken crystals’ technique to provide a greater number of thermal constraints for thermal history modelling to better constrain the topographic evolution. The spatial distribution of AFT and AHe ages implies that exhumation has been significant toward the SE (Labrador) coastline, and results of thermal modelling outline three notable periods of cooling: in the pre-rift stage (460–200 Ma), from synrift stage to present (120–0 Ma) and within the post-rift stage (30–0 Ma). Pre-rift cooling is interpreted as the result of exhumation of Laurentia and synrift cooling as the result of rift-flank uplift to the SE and differential erosion of landscape, whereas the final post-rift period is probably an artefact of the modelling process. These results suggest that the source of the Cumberland Peninsula's modern-day elevated topography is uplift during rifting in the Cretaceous and the isostatic compensation following continuous Mesozoic and Cenozoic differential erosion. This work highlights how interaction of rift tectonics and isostasy can be the principal source for modern elevated continental margins, and also provides insight into the pre-rift exhumational history of central Laurentia.

Item Type:Articles
Additional Information:The work reported here was conducted during a PhD study undertaken as part of the Natural Environment Research Council (NERC) Centre Fig. 7. Results of 2D flexural model with Flex2D (Allmendinger et al. 2011) with initial model assumptions as given in the text. Filling of the fjords, deemed as a simple estimation of the erosion, pushes down the lithosphere and gives the pre-erosion topography (grey), which appears 90.7 m lower than the modern-day topography. These results suggest that differential unloading of the lithosphere does promote growth of the topography and that the topography of Cumberland Peninsula today is maintained by this isostatic response. Uplift on Baffin Island Downloaded from at University of Glasgow on August 23, 2019 for Doctoral Training (CDT) in Oil & Gas (grant number NEM00578X/1) and was sponsored by the University of Aberdeen.
Glasgow Author(s) Enlighten ID:Brown, Professor Roderick
Authors: Jess, S., Stephenson, R., Nielsen, S., and Brown, R.
College/School:College of Science and Engineering
College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Journal of the Geological Society
Publisher:Geological Society of London
ISSN (Online):2041-479X
Published Online:23 July 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Journal of the Geological Society 176(6): 1093-1106
Publisher Policy:Reproduced under a Creative Commons License

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