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October 10, 2017

Fracking magma: field and experimental investigation of hydrofracture in volcanic systems

Fracking magma: field and experimental investigation of hydrofracture in volcanic systems

Tuffisite veins are particle-filled hydraulic fractures formed around and within volcanic conduits, which are opened by and provide transient pathways for flow of pressurised magmatic fluids. Tuffisites become sealed by welding of pyroclasts, and their evolving permeability is thought to influence shallow conduit pressurisation and the behaviour of silicic eruptions. Poor constraints on the longevity of fluid flow within veins and the associated fluid pressures currently hampers modelling of eruption dynamics, and the influence of heterogeneous country rock on vein opening is unknown. Indeed, in general, hydraulic fracture in volcanic systems remains little understood. However, hydraulic fracturing is far better studied in other geological environments. Clastic dykes formed by injection of pressurised meltwater into subglacial sediments display remarkably similar sedimentary structures to tuffisites, and detailed study of microstructures reveals complex histories of pulsatory fluid flow. Meanwhile, experimental approaches are revealing how different lithologies influence hydraulic fracture propagation in hydrocarbon reservoirs. In this PhD you will work alongside experts in volcanology, glacial geology and experimental fracture mechanics at Lancaster University and BGS to reappraise hydraulic fracture in volcanic systems. You will apply a novel combination of the latest techniques from three different research fields to provide new constraints on hydraulic fracture propagation and evolution. The research will be underpinned by a substantial field component, with characterisation of fossil hydraulic fracture systems in Iceland and the UK, complimented by microstructural analysis and measurement of dissolved magmatic volatile concentrations. You will also complete an internship at the BGS Fracture Physics Lab, using natural and analogue samples to investigate the opening and sealing of hydraulic fracture networks. There is strong potential for wider collaboration with other European research groups. Full training in all techniques will be provided; there are additional excellent training and networking opportunities through Lancaster’s new Graduate School for the Environment.

Applicants should hold a minimum of a UK Honours Degree at 2:1 level or equivalent in a relevant subject such as Geology, Geophysics, Physical Geography or Environmental Science, and have preferably either started or completed a relevant Masters-level degree. Experience in detailed geological fieldwork, textural analysis or experimentation is highly desirable but not essential. We are looking for highly-motivated, numerate individuals with a proven track record of independent research, but who have also been enriched by their interests outside of academic life.

For further details please contact Emrys Phillips (erp@bgs.ac.uk).