Dziggel, A., Kokfelt, T. F., Kolb, J., Kisters, A. F. M. and Reifenrother, R. (2017). Tectonic switches and the exhumation of deep-crustal granulites during Neoarchean terrane accretion in the area around Graedefjord, SW Greenland. Precambrian Res., 300. S. 223 - 246. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1872-7433

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Abstract

Terrane accretion in the Nuuk region in the North Atlantic Craton in Greenland shares many characteristics with modern accretionary systems, including compelling evidence for regional-scale crustal thickening as well as the presence of terranes with distinct PT histories. The Nuuk region is therefore interpreted to contain a paired metamorphic belt, formed during the convergence and collision of the Faeringehavn terrane with the structurally overlying Tre Brodre and Tasiusarsuaq terranes between ca. 2720 and 2700 Ma. The Tasiusarsuaq terrane exposes a deeply eroded section through the upper plate of the orogen, dominated by granulite and amphibolite facies TTG gneiss and mafic supracrustal rocks. In its centre, nappes of deep crustal granulites (800-950 degrees C, 9-12 kbar) were exhumed to mid crustal levels at conditions of 660-810 degrees C and 7-8 kbar. Nappe emplacement occurred during NW-vergent thrusting and the steepening of fabrics between ca. 2760 and 2720 Ma, coeval with the underthrusting of the Faeringehavn beneath the Tasiusarsuaq terrane. Pervasive ductile fabrics and the presence of abundant leucosomes and syntectonic pegmatites suggest that mid-crustal nappe emplacement was melt-assisted. The final collisional event between 2720 and 2700 Ma was associated with a switch from convergence-related thrusting and non-coaxial shearing to co-axial shortening, leading to the development of the subvertical, linear Graedefjord gneiss belt that records the vertical extrusion of material. The Graedefjord gneiss belt is the most prominent of these late-stage ca. 2700 Ma extrusion zones that was previously interpreted to be located at or near a boundary between two tectonic blocks.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Dziggel, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kokfelt, T. F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kolb, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kisters, A. F. M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Reifenrother, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-215939
DOI: 10.1016/j.precamres.2017.07.027
Journal or Publication Title: Precambrian Res.
Volume: 300
Page Range: S. 223 - 246
Date: 2017
Publisher: ELSEVIER SCIENCE BV
Place of Publication: AMSTERDAM
ISSN: 1872-7433
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
SOUTHERN WEST-GREENLAND; ITSAQ GNEISS COMPLEX; NORTH-ATLANTIC CRATON; FISKENAESSET ANORTHOSITE COMPLEX; MINERAL EQUILIBRIA CALCULATIONS; NUUK REGION; BUKSEFJORDEN REGION; ARCHEAN TERRANE; SYSTEM K2O-FEO-MGO-AL2O3-SIO2-H2O-TIO2-FE2O3; SOUTHWESTERN GREENLANDMultiple languages
Geosciences, MultidisciplinaryMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/21593

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