Universität zu Köln

Froitzheim, Nikolaus, Miladinova, Irena ORCID: 0000-0002-2808-0378, Janak, Marian, Kullerud, Kare ORCID: 0000-0003-0260-8872, Ravna, Erling Krogh, Majka, Jaroslaw ORCID: 0000-0002-6792-6866, Fonseca, Raul O. C. ORCID: 0000-0002-0897-4884, Muenker, Carsten and Nagel, Thorsten J. (2016). Devonian subduction and syncollisional exhumation of continental crust in Lofoten, Norway. Geology, 44 (3). S. 223 - 227. BOULDER: GEOLOGICAL SOC AMER, INC. ISSN 1943-2682

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Abstract

When continents collide, continental crust of the lower plate may be subducted to mantle depth and return to the surface to form eclogite facies metamorphic terranes, as typified by the Western Gneiss Complex of the Scandinavian Caledonides. Proterozoic basement of the Lofoten Islands, located northeast and along strike of the Western Gneiss Complex, contains Caledonian eclogite, although Caledonian deformation is only minor. Previous dating suggested that Lofoten eclogites formed at ca. 480 Ma, i.e., similar to 50 Ma before the collision between the major continents Baltica and Laurentia, and that the Lofoten basement may not originate from Baltica but rather represents a stranded microcontinent. Newly discovered kyanite eclogites from the Lofoten Islands record deep subduction of continental crust during the main (Scandian) stage of Baltica-Laurentia collision ca. 400 Ma. Thermobarometry and thermodynamic modeling yield metamorphic conditions of 2.5-2.8 GPa and similar to 650 degrees C. Lu-Hf geochronology yields 399 +/- 10 Ma, corresponding to the time of garnet growth during subduction. Our results demonstrate that the Lofoten basement belonged to Baltica, was subducted to similar to 90 km depth during the collision with Laurentia, and was exhumed at an intermediate to high rate (>6 mm/yr) while thrusting of a Caledonian allochthon (Leknes Group) was still ongoing. This supports the challenging conclusions that (1) subducted continental crust may stay rigid down to a depth of similar to 90 km, and (2) it may be exhumed during ongoing collision and crustal shortening.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Froitzheim, Nikolaus UNSPECIFIED UNSPECIFIED UNSPECIFIED Miladinova, Irena UNSPECIFIED orcid.org/0000-0002-2808-0378 UNSPECIFIED Janak, Marian UNSPECIFIED UNSPECIFIED UNSPECIFIED Kullerud, Kare UNSPECIFIED orcid.org/0000-0003-0260-8872 UNSPECIFIED Ravna, Erling Krogh UNSPECIFIED UNSPECIFIED UNSPECIFIED Majka, Jaroslaw UNSPECIFIED orcid.org/0000-0002-6792-6866 UNSPECIFIED Fonseca, Raul O. C. UNSPECIFIED orcid.org/0000-0002-0897-4884 UNSPECIFIED Muenker, Carsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Nagel, Thorsten J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-283325
DOI:	10.1130/G37545.1
Journal or Publication Title:	Geology
Volume:	44
Number:	3
Page Range:	S. 223 - 227
Date:	2016
Publisher:	GEOLOGICAL SOC AMER, INC
Place of Publication:	BOULDER
ISSN:	1943-2682
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language NORTH NORWAY; BASEMENT; CALEDONIDES; ECLOGITES; EXTENSION; GEOCHRONOLOGY; COLLISION; DUCTILE; COMPLEX; MARGIN Multiple languages Geology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/28332