Overview:
Granite intrusions are key targets for deep geothermal energy and for key resources needed for mobile and renewable technologies (e.g., Li and U). The way these resources are concentrated geologically is related to both emplacement and crystallisation of the granite magma and subsequent exposure to hydrothermal systems. Hydrothermal fluids can originate from within the granite body from volatiles concentrated as the magma crystallises and from meteoric fluids that circulate through fault zones that intersect granite. The key exploration targets are hydrothermally altered zones where important minerals become concentrated by the activity of hydrothermal fluids.
Marginal pegmatite rich, aplitic and leucocratc zones in granite plutons often exhibit markedly lower magnetic susceptibility (e.g., Stevenson et al., 2007; Stevenson 2009). Unpublished data from the Tregonning Granite, Cornwall (Fig. 1) show negative magnetic susceptibilities. In these cases the accumulation of volatiles has altered the granite and reduced the amount of iron bearing minerals such as magnetite. In this project you will study the effect of hydrothermal alteration on the magnetic properties of granite. The aim is to assess the viability of magnetic susceptibility as an exploration tool. As part of this aim, your objectives are to carry out detailed rock magnetic analyses that will establish the magnetic mineralogy and along side this to study the mineralisation history and hydrothermal alteration.
Work will include field work involving structural and mineralogical mapping of key granite sections. This mapping will use digital mapping and drone survey techniques (e.g., Fig. 1). Field work will primarily aim to collect a suite of oriented block samples form a range of hydrothermal granite outcrops. Potential field areas include Cornwall, Scotland, Ireland and can make use of existing samples in house and in collaboration with other ongoing projects.
Training and skills:
Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.
Rock magnetic lab analyses: range of rock magnetic analyses and laboratory methods including oriented field sampling and lab preparation. Other laboratory skills involve demagnetisation steps, operation of spinner magnetometer and kappabridge apparatus. Low temperature thermomagnetic analyses require the handling of liquid nitrogen.
Structural mapping using FieldMOVE app, structural modelling using MOVE structural software.
Drone surveys will use DJI Mavic Pro 2 for field digital capture and Agisoft Metashape for photogrammetric 3D modelling
Further details:
If you wish to apply to the project, applications should include:
- A CENTA application form, downloadable from: CENTA application
- A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)
- The application should please completed via: https://sits.bham.ac.uk/lpages/LES068.htm. Please select Apply Now in the PhD Geography and Environmental Science (CENTA) section. Please quote CENTA23_B14 when completing the application form.
For further information on how to apply please visit https://centa.ac.uk/apply/how-to-apply/.
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