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Development of igneous layering during growth of pluton: The Tarçouate Laccolith (Morocco)

Authors :
Jean-Pierre Burg
J. Pons
Pierre Barbey
H. Nachit
Institut des Sciences de la Terre d'Orléans (ISTO)
Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
Centre de Recherches Pétrographiques et Géochimiques (CRPG)
Institut national des sciences de l'Univers (INSU - CNRS)-Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
Département des Sciences de la Terre (DéPARTEMENT DES SCIENCES DE LA TERRE)
Université Ibnou Zohr
Departement Erdwissenschaften [ETH Zürich] (D-ERDW)
Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)
Université de Lorraine (UL)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Source :
Tectonophysics, Tectonophysics, Elsevier, 2006, 413, pp.3-4, 271-286. ⟨10.1016/j.tecto.2005.11.005⟩
Publication Year :
2006
Publisher :
HAL CCSD, 2006.

Abstract

We discuss the significance of igneous layering with respect to pluton growth processes. The case study is the Tarcouate Laccolith (Morocco), whose core consists of modally layered hornblende granodiorites with high amount of monzodioritic enclaves, contrasting with peripheral, non-layered biotite granodiorites with low amount of enclaves. Rhythmic layering, with modal grading, cross-stratification and trough layering is associated with monzodioritic layers and wraps around mafic enclaves. Its steep dips ≥ 45° result from tilting that occurred above solidus conditions, as indicated by sub-vertical and synmagmatic granite, aplite and monzodiorite dykes cutting across the layering. The systematic association of igneous layering with mafic enclaves in calc-alkaline plutons suggests that layering originates from recurrent injection of mafic magma. Viscosity calculations suggest that the physicochemical properties of magma alone cannot account for the presence of layering in the central hornblende granodiorite and its coeval absence in the peripheral biotite granodiorite of the Tarcouate Laccolith. Intermittent pulses of hot mafic magma into crystallizing granodiorite likely produced thermal perturbations able to trigger local convection, formation of mafic enclaves and development of igneous layering through protracted crystallization.

Details

Language :
English
ISSN :
00401951 and 18793266
Database :
OpenAIRE
Journal :
Tectonophysics, Tectonophysics, Elsevier, 2006, 413, pp.3-4, 271-286. ⟨10.1016/j.tecto.2005.11.005⟩
Accession number :
edsair.doi.dedup.....9bbb5f77687a0b269de58228972ea304
Full Text :
https://doi.org/10.1016/j.tecto.2005.11.005⟩