Leif Johansson
Professor emeritus
The Finnefjeld domain, Maniitsoq structure, West Greenland: Differential rheological features and mechanical homogenisation in response to impacting?
Author
Summary, in 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.
Department/s
- Lithosphere and Biosphere Science
Publishing year
2014
Language
English
Pages
791-808
Publication/Series
Precambrian Research
Volume
255
Links
Document type
Journal article
Publisher
Elsevier
Topic
- Geology
Keywords
- Mixed theological behaviour
- Maniitsoq impact structure
- Cataclasis
- Direct mineral melting
Status
Published
ISBN/ISSN/Other
- ISSN: 0301-9268