Abstract

Abstract: Current tectonic models emphasize the role of crustal‐scale transcurrent faults in controlling the ascent and emplacement of plutons in orogenic belts. The Clunes Tonalite crops out adjacent to the transcurrent Great Glen Fault Zone within the Ordovician‐Silurian Caledonian orogenic belt of Scotland. The tonalite is characterized by a strong fabric defined by aligned plagioclase, hornblende and biotite that is interpreted to be a magmatic state deformation fabric formed during emplacement. Field and microstructural evidence derived from the tonalite and its Moine Supergroup country rocks supports an emplacement model that links intrusion directly to early sinistral displacements along the Great Glen Fault Zone. U–Pb zircon geochronology yields a crystallization age for the Clunes Tonalite of 427.8±1.9 Ma. The age is thus interpreted to date early sinistral displacements along the Great Glen Fault Zone and is identical within error to that of the Ratagain granite emplaced during sinistral displacement along the Strathconon Fault to the NW.

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