Relations between basalts and adakitic-felsic intrusive bodies in a soft-substrate environment: the South Ouessant Visean basin in the Variscan belt, Armorican Massif, France

Type Article
Date 2016-04
Language English
Author(s) Caroff MartialORCID1, Le Gall Bernard1, Authemayou Christine1, Grosjean Denise Bussien1, Labry Cyrill1, Guillong MarcelORCID2
Affiliation(s) 1 : Univ Brest, UMR CNRS Domaines Ocean 6538, Inst Univ Europeen Mer, Pl Nicolas Copernic, F-29280 Plouzane, France.
2 : ETH, Inst Geochem & Petr, Dept Earth Sci, Clausiusstr 25, CH-8092 Zurich, Switzerland.
Source Canadian Journal Of Earth Sciences (0008-4077) (Canadian Science Publishing), 2016-04 , Vol. 53 , N. 4 , P. 441-456
DOI 10.1139/cjes-2015-0230
WOS© Times Cited 4
Abstract The metasedimentary and magmatic terranes in the southern part of the Ouessant Island (Western Brittany, France) are the offshore prolongation of the Leon Variscan metamorphic domain. They mainly consist of micaschists and subordinate amphibolitic lenses (meta-pillow lavas and volcaniclastic successions) cut by a swarm of trondhjemite sills, together with a large porphyritic monzogranite body, newly dated at 336 Ma, and later syeno-leucogranitic intrusions. A large spectrum of fluidal peperites, including spectacular "fiamme"-bearing breccias, is observable at the contact between metasediments and most of the intrusives. The coexistence of amphibolitized basalts, adakitic trondhjemites, and peraluminous granites in the inferred South Ouessant basin is assigned to a variety of deep subcontemporaneous processes, including asthenospheric partial melting, high-pressure fractionation in lithospheric reservoirs (or partial remelting of deep crystallized mafic intrusions), and continental crust melting. Implications of these new results are discussed in the Visean basinal framework of the Armorican Massif, formed at an early stage of the Variscan orogeny.
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Caroff Martial, Le Gall Bernard, Authemayou Christine, Grosjean Denise Bussien, Labry Cyrill, Guillong Marcel (2016). Relations between basalts and adakitic-felsic intrusive bodies in a soft-substrate environment: the South Ouessant Visean basin in the Variscan belt, Armorican Massif, France. Canadian Journal Of Earth Sciences, 53(4), 441-456. Publisher's official version : https://doi.org/10.1139/cjes-2015-0230 , Open Access version : https://archimer.ifremer.fr/doc/00639/75091/