Silurian–Devonian magmatism, mineralization, regional exhumation and brittle strike-slip deformation along the Loch Shin Line, NW Scotland

Holdsworth, R. E.; Dempsey, E.; Selby, D.; Darling, J. R.; Feely, M.; Costanzo, A.; Strachan, R. A.; Waters, P.; Finlay, A. J.; Porter, S. J.

Abstract

The Loch Shin Line is a geological–geophysical lineament associated with a zone of mantle-derived appinites, granites and strike-slip faulting that runs NW–SE across the Moine Nappe, northern Scotland. U–Pb zircon and Re–Os molybdenite dating of the Loch Shin and Grudie plutons, which lie immediately SW of the NW–SE Loch Shin–Strath Fleet fault system, yield c. 427–430 Ma ages that overlap within error. They also coincide with previously obtained U–Pb zircon ages for the Rogart pluton, which lies along-strike to the SE. Field and microstructural observations confirm the similarity and contemporaneous nature of the plutons and associated sulphide mineralization. Fluid inclusion analyses place further constraints on the P–T–X conditions during regional late Caledonian exhumation of the Moine Nappe. Synchronous to slightly younger brittle dextral strike-slip faulting along the WNW–ESE Loch Shin–Strath Fleet Fault System was probably antithetic to sinistral movements along the nearby Great Glen Fault Zone. Our findings support the hypothesis that the Loch Shin Line acted as a deep crustal channelway controlling the ascent and emplacement of Silurian magmas into the overlying Moine Nappe. We propose that this deep structure corresponds to the southeastern continuation of the Precambrian-age Laxford Front shear zone in the buried Lewisian autochthon.

Citation

Holdsworth, R. E., Dempsey, E., Selby, D., Darling, J. R., Feely, M., Costanzo, A., Strachan, R. A., Waters, P., Finlay, A. J., & Porter, S. J. (2015). Silurian–Devonian magmatism, mineralization, regional exhumation and brittle strike-slip deformation along the Loch Shin Line, NW Scotland. Journal of the Geological Society, 172(6), 748-762. https://doi.org/10.1144/jgs2015-058

• Journal Article Type: Article
• Acceptance Date: Jun 29, 2015
• Online Publication Date: Aug 20, 2015
• Publication Date: Aug 20, 2015
• Deposit Date: Nov 19, 2018
• Journal: Journal of the Geological Society
• Print ISSN: 0016-7649
• Publisher: Geological Society
• Peer Reviewed: Peer Reviewed
• Volume: 172
• Issue: 6
• Pages: 748-762
• DOI: https://doi.org/10.1144/jgs2015-058
• Keywords: Geology
• Public URL: https://hull-repository.worktribe.com/output/1154962
• Publisher URL: http://jgs.lyellcollection.org/content/172/6/748