Structure and U-Pb dating of the Saint-Arnac Pluton and the Ansignan Charnockite (Agly Massif); a cross-section from the upper to the middle crust of the Variscan eastern Pyrenees

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doi: 10.1144/0016-76492006-185
Authors:Olivier, Philippe; Gleizes, Gérard; Paquette, Jean-Louis; Muñoz Sáez, Carolina
Author Affiliations:Primary:
Université de Toulouse, Laboratoire des Mécanismes et Transferts en Géologie, Toulouse, France
Other:
Université Blaise Pascal, France
Universidad de Chile, Chile
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, 165(1), p.141-152. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:2008
Note:In English. 36 refs.; illus., incl. 2 tables, geol. sketch maps
Summary:In the Agly Massif (Pyrenees), two Variscan plutons, the Saint-Arnac pluton and the Ansignan charnockite, intrude different levels of a c. 10 km thick crustal section. The Saint-Arnac pluton intrudes through upper crustal rocks and the Ansignan charnockite cuts mid-crustal country-rocks. A structural study of these plutons based on the anisotropy of magnetic susceptibility technique, combined with a kinematic study of the country-rocks, shows that the structures and emplacement modes of the plutons are compatible with those of the other plutons of the Pyrenees emplaced during the D2 transpressive phase. U-Pb dating on zircons from the Saint-Arnac pluton yields a 308.3±1.2 Ma age for a diorite and a 303.6±4.7 Ma age for a granodiorite. The charnockite was previously dated at 315 Ma. The emplacement ages of these two intrusions are thus separated by at least 5 Ma. First, numerous sills and laccoliths, such as the Ansignan laccolith, were injected in the middle crust, and this induced heating and thickening. Subsequently, the large Saint-Arnac pluton was injected in the upper crust at the beginning of formation of a gneissic dome. [R.A.H.]
Sections:Age determination; Petrology
Subsections:General
Subjects:Absolute age; Carboniferous; Charnockite; Crust; Crustal thinning; Dates; Emplacement; Foliation; Gneisses; Granites; Igneous rocks; Intrusions; Lineation; Magnetic susceptibility; Metamorphic rocks; Nesosilicates; Orthosilicates; Paleozoic; Plutonic rocks; Plutons; Silicates; Sills; Structural analysis; Transpression; U/Pb; Upper Carboniferous; Upper crust; Zircon; Zircon group; Agly Massif; Europe; France; Pyrenees; Pyrenees-Orientales France; Western Europe; Ansignan Pluton; Eastern Pyrenees; Saint-Arnac Pluton
Coordinates:N424500 N424500 E0023500 E0023500
Abstract Numbers:08M/0485
Record ID:2008064184
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States, Reference includes data from The Geological Society, London
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