Differential erosion of a Mesozoic rift flank

Establishing the source of topography across Karrat, central West Greenland

Scott Jess* (Corresponding Author), Randell Stephenson, David H. Roberts, Roderick Brown

*Corresponding author for this work

Research output: Contribution to journalArticle

3 Citations (Scopus)
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Abstract

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.
Original languageEnglish
Pages (from-to)138-150
Number of pages13
JournalGeomorphology
Volume334
Early online date4 Mar 2019
DOIs
Publication statusPublished - 1 Jun 2019

Fingerprint

topography
erosion
apatite
ice stream
exhumation
landscape evolution
uplift
geomorphology
volcanism
tectonics
glacial erosion
escarpment
fjord
modeling
rifting
continental margin
trough
pile
relief
cooling

Keywords

  • Thermochronology
  • Geomorphology
  • Rifting
  • Isostasy
  • Greenland

Cite this

Differential erosion of a Mesozoic rift flank : Establishing the source of topography across Karrat, central West Greenland . / Jess, Scott (Corresponding Author); Stephenson, Randell; Roberts, David H.; Brown, Roderick .

In: Geomorphology, Vol. 334, 01.06.2019, p. 138-150.

Research output: Contribution to journalArticle

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abstract = "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.",
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note = "Brice Rea and Tim Lane are sincerely thanked for the collection of samples, while Robert McDonald, Andy Carter and James Schwanethal are also thanked for their assistance in sample preparation and analysis. 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.",
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AB - 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.

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