Structural setting and U–Pb zircon geochronology of the Glen Scaddle Metagabbro: evidence for polyphase Scandian ductile deformation in the Caledonides of northern Scotland

2008/03/06 by R. A. STRACHAN, R. A. Strachan, Jane Evans +1 · 7 citations
Earth and Planetary Sciences · #Geological and Geochemical Analysis #earthquake and tectonic studies #High-pressure geophysics and materials

paper · doi:10.1017/s0016756808004500

Abstract

Abstract Within the Scottish Caledonides, the Glen Scaddle Metagabbro was intruded into the Moine Supergroup of the Northern Highland Terrane after Grampian D 2 folding and prior to regional D 3 and D 4 upright folding and amphibolite-facies metamorphism. A U–Pb zircon age of 426 ± 3 Ma obtained from the metagabbro is interpreted to date emplacement. D 3 –D 4 folding is constrained to have occurred during the Scandian orogenic event. In contrast, polyphase folding and regional metamorphism of the Dalradian Supergroup southeast of the Great Glen Fault is entirely Grampian. These differences are consistent with published tectonic models that invoke a minimum of 700 km of post-Scandian sinistral displacements across the Great Glen Fault to juxtapose the Grampian and Northern Highland terranes.

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• Thermobarometry of the Moine and Sgurr Beag thrust sheets, northern Scotland
• Lu–Hf and Sm–Nd dating of metamorphic garnet: evidence for multiple accretion events during the Caledonian orogeny in Scotland
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