Character and formation of the Barth Island Intrusive Complex, Nain Plutonic Suite, Labrador

• Main Authors: Gaskill, O., Leitch, A.M., Poujol, Marc
• Other Authors: Terre, Temps, Traçage, Géosciences Rennes (GR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)-Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2008
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Barth Island; Canada; Nain
• Online Access: https://insu.hal.science/insu-01083549

ISBN : 978-1-897095-35-5 International audience The Barth Island Intrusive Complex (BIC) comprises spatially associated, concentric ovals of leucotroctolite, monzonite, and ferrodiorite, three members of the ‘anorthosite suite’. Concordance of contact orientations with structures in adjacent rock types, in all the rocks of the BIC, have resulted in previous interpretations of the BIC as either the result of differentiation of a single pulse of basic magma, or the result of pulses of different, broadly contemporaneous magmas. New mapping and ID-TIMS U-Pb zircon geochronology indicate that ferrodiorite and monzonite in the outer part of the BIC are closely contemporaneous, with emplacement ages of ca. 1318, while the central leucotroctolite unit is older, emplaced at ca. 1332 Ma. Spatial and geometric considerations suggest the magmas of the BIC were emplaced through the same conduit, as a cone structure. The difference in age between the inner and outer units of the BIC indicates that they were not part of the same melting event, suggesting that rock types of the anorthosite suite are not simply related by differentiation or AFC processes at any depth. Rock densities indicate the ferrodiorite and monzonite magmas could have been stably stratified together at depth; whole rock chemical results do not preclude their being products of conjugate immiscible liquids.