A Variscan slow-spreading ridge (MOR-LHOT) in Limousin (French Massif Central); magmatic evolution and tectonic setting inferred from mineral chemistry

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doi: 10.1180/0026461067020322
Authors:Berger, Julien; Féménias, O.; Mercier, J. C. C.; Demaiffe, D.
Author Affiliations:Primary:
Africa Museum, Section de Géologie Isotopique, Tervuren, Belgium
Université Libre de Bruxelles, Belgium
Université de La Rochelle, France
Volume Title:Mineralogical Magazine
Source:Mineralogical Magazine, 70(2), p.175-185. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026-461X
Publication Date:2006
Note:In English. 50 refs.; illus., incl. sketch map
Summary:The Limousin ophiolite (French Massif Central) occurs as elongate bodies forming a (nearly) continuous suture zone between two major lithotectonic units of the French Variscan belt. The mantle section of the ophiolite is made of diopside-bearing harzburgite, harzburgite and dunite characteristic of a lherzolite-harzburgite ophiolite type (LHOT). The plutonic section is essentially composed of troctolites, wehrlites and gabbros locally intruded by ilmenite-rich mafic dykes. All the rocks were strongly affected by an ocean-floor hydrothermal metamorphism. The composition and evolution of primary magmatic phases (olivine, clinopyroxene, plagioclase and spinel) throughout the lowermost magmatic sequence correspond to those described in oceanic cumulates (ODP data). The Limousin ophiolite is thus of MOR type instead of SSZ type. The whole lithological section, the mineral chemistry, the extensive hydrothermal oceanic alteration and the relatively thin crustal section are typical of a slow-spreading ridge ocean (i.e. Mid-Atlantic ridge). Comparison of the Limousin ophiolite with other ophiolites from European Variscides suggests that the oceanic domain was actively spreading during the Late Palaeozoic and extended from the Armorican massif to the Polish Sudetes.
Subsections:General; Igneous rocks; Oceanic petrology
Subjects:Chain silicates; Clinopyroxene; Dikes; Diopside; Feldspar group; Framework silicates; Gabbros; Harzburgite; Hydrothermal conditions; Igneous rocks; Ilmenite; Intrusions; Lherzolite; Mid-ocean ridges; Mineral assemblages; Nesosilicates; Ocean Drilling Program; Ocean floors; Olivine; Olivine group; Ophiolite; Ophiolite complexes; Orthosilicates; Oxides; Paleozoic; Peridotites; Plagioclase; Plutonic rocks; Pyroxene group; Sea-floor spreading; Silicates; Spinel; Troctolite; Ultramafics; Upper Paleozoic; Armorican Massif; Central Europe; Central Massif; Europe; France; Limousin; Poland; Polish Sudeten Mountains; Sudeten Mountains; Variscides; Western Europe
Coordinates:N450000 N461000 E0030000 E0003000
Abstract Numbers:06M/2424
Record ID:2006055296
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland, Reference includes data from GeoScienceWorld, Alexandria, VA, United States
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