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The Finnefjeld domain, Maniitsoq structure, West Greenland: Differential rheological features and mechanical homogenisation in response to impacting?

Author:
  • Adam A. Garde
  • Brendan Dyck
  • Kim H. Esbensen
  • Leif Johansson
  • Charlotte Möller
Publishing year: 2014
Language: English
Pages: 791-808
Publication/Series: Precambrian Research
Volume: 255
Document type: Journal article
Publisher: Elsevier

Abstract english

The 35 by 50 km large, Mesoarchaean Finnefjeld domain near Maniitsoq in the North Atlantic craton of southern West Greenland constitutes the central part of the previously proposed, deeply eroded Maniitsoq impact structure with an age of 3.0 Ga. The Finnefjeld domain is an exceedingly homogeneous, quartzo-feldspathic rock mass which superficially appears to be a late-orogenic, deep-crustal, intrusive granitoid pluton, and which was described as such for decades. However, new observations confirm and qualify the first observations from 1962 of these rocks as 'cataclastic'. The Finnefjeld domain is characterised by a highly unusual, mixed rheological behaviour. Plagioclase displays brittle behaviour with cataclasis, quartz was ductilely deformed, and K-feldspar was melted. The deformation and homogenisation of the Finnefjeld domain was caused by an intense event of heating and deformation, which was coseismic in nature and comprised numerous increments of pure shear strain. This type of intense, brittle, regional deformation and concomitant direct mineral melting in the deep crust is unknown from endogenic orogenic events and is ascribed to deep-crustal effects of impacting. (C) 2014 Elsevier B.V. All rights reserved.

Keywords

  • Geology
  • Mixed theological behaviour
  • Maniitsoq impact structure
  • Cataclasis
  • Direct mineral melting

Other

Published
  • ISSN: 0301-9268
Leif Johansson
E-mail: leif [dot] johansson [at] geol [dot] lu [dot] se

Professor

Lithosphere and Biosphere Science

+46 46 222 98 87

+46 70 530 76 73

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