Geophysical surveys around Mull, Western Scotland

Wilson, Mavis (1979) Geophysical surveys around Mull, Western Scotland. PhD thesis, University of Glasgow.

Abstract

Geophysical surveys have been carried out in the sea area around Mull on twD cruises aboard NERC research vessels; RRS Challenger (May 1977) and RRS John Murray (February 1979). The aim of the surveys was twofold;- (a) to obtain seismic refraction data using an anchored sono- buoy with a seabed hydrophone, a method which proved to be an improvement on previous attempts using free-floating sono- buoys with neutrally-bouyant near-surface hydrophones. The results from 13 surveys are presented with geological interpretations . (b) to locate the SW continuation of the Great Glen Fault by preparing a geological map of the area using geophysical data. This is clearly located on the depth to rockhead map where a deep trough in rockhead is observed trending 030°S from Loch Buie. The trend changes abruptly to 060° 14 km S of Loch Buie. The course of the Moine Thrust through the area is also traced and its offset used to demonstrate a 55 km sinistral shift on the Great Glen Fault. Other faults of NE-SW and NNE-SSW trend believed to be related to the Great Glen Fault are observed in the Firth of Lome producing a faulted sequence of L.OP .lavas and sediments. Faults of similar trend are also observed between Colonsay and Jura, the most easterly is believed to be the northern extension of the Loch Gruinart Fault. The relationship of the Great Glen Fault to other similarly trending faults in Scotland is discussed. It is believed that all these faults which are similarly orientated are the result of the same stress system produced by terminal events of the Caledonian orogeny. Two relatively young active strlke-sllp fault systems are described and compared. The San Andreas Fault and The Alpine Fault. By comparison with these faults it is believed that the Great Glen Fault formed close to a plate margin; the segment north of the bend south of Loch Buie was oblique to the regional slip vector and the other segment was parallel to the regional slip vector.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QE Geology
• Colleges/Schools: College of Science and Engineering
• Supervisor's Name: Hall, Dr. J.
• Date of Award: 1979
• Depositing User: Enlighten Team
• Unique ID: glathesis:1979-83068
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 02 Aug 2022 15:31
• Last Modified: 02 Aug 2022 15:38
• Thesis DOI: 10.5525/gla.thesis.83068
• URI: https://theses.gla.ac.uk/id/eprint/83068