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Emplacement of sub-volcanic cone sheet intrusions

Magee, Craig (2011)
Ph.D. thesis, University of Birmingham.

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Abstract

Sub-volcanic intrusive networks, of which cone sheets are recognised as a major constituent, control volcano growth and eruption style. The accepted cone sheet model is that these confocally dipping intrusions originate from an unexposed central magma chamber through dip-parallel magma flow. However, the emplacement mechanism of cone sheets has remained poorly understood. The classic ~58 Ma cone sheet swarm of Ardnamurchan, NW Scotland, offers an excellent opportunity to further resolve the emplacement dynamics of cone sheets through studying their magma flow. Structural measurements and anisotropy of magnetic susceptibility (AMS) analyses have constrained a lateral magma flow regime, consistently oriented NW-SE, in the majority of the Ardnamurchan cone sheets. This is not consistent with previous emplacement models. In this thesis, it is suggested that emplacement of the Ardnamurchan cone sheets occurred through the deflection of laterally propagating, NW-SE trending regional dykes, sourced from laterally adjacent magmatic systems (likely the Palaeogene Mull central complex). Field observations highlight the importance of host rock structure and interference between locally compressional and regional extensional stress fields in controlling intrusion geometry. Implicitly, edifice construction and potential eruption precursors observed at a volcano may instigate, or result from, magmatic activity in laterally adjacent volcanic systems.

Type of Work:Ph.D. thesis.
Supervisor(s):Stevenson, Carl and O'Driscoll, Brian and Reston, Tim
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:Department of Earth Sciences, School of Geography, Earth and Environmental Sciences
Subjects:QE Geology
Institution:University of Birmingham
ID Code:3042
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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