Early evolution of the Palaeogene Mull volcano: An integrated volcanological, geochemical and geochronological approach

Project Background
Volcanological and petrogenetic research in the various eroded volcanic centres of the North Atlantic Palaeogene Igneous Province (NAPIP) have greatly informed our understanding of processes in both caldera volcanoes and flood basalt magmatism (e.g., Gooday et al., 2018).

This project focusses on the early evolution of centres 1 and 2 of the ~60 Ma Mull volcano (or central complex) which represents one of the UK’s classic geological locations. Despite this, very little has been published on the early part of the Mull Central Complex since the publication of the Geological Survey Memoir almost 100 years ago (Bailey, et al. 1924). The Mull Central Complex contains evidence for major explosive eruptions in the form of basaltic to rhyolitic ignimbrites that appear to be associated with caldera subsidence. Possible pillow basalts within the caldera indicate a relatively shallow level of exposure and so relationships between the surface products, the caldera floor, the bounding faults and the sub-surface magma conduits will be clearer than if deeper erosion had occurred. A sequence of major intrusions, cone sheets and ring dykes with a range of compositions from mafic to felsic pre- and post-date the extrusive volcanic events.

Project Aims
The project will undertake an integrated study of Centres 1 and 2 of the Mull volcano that includes i) volcanological and structural analysis through detailed field mapping, sampling and volcanological analysis in Mull; ii) major and trace element and radiogenic isotope analysis at Cardiff; and iii) radiometric dating (U-Pb and Ar-Ar) at NIGL, Keyworth and SUERC, East Kilbride (subject to NIGFSC bid). Key issues that will be addressed are:

The stratigraphy and eruption/emplacement history of the complex. Modern physical volcanology techniques (e.g., lithofacies mapping and logging) will be undertaken to understand the field relationships, stratigraphy and history of the caldera.

Structural and magmatic controls on eruption and collapse. Detailed geological mapping of the caldera-bounding and internal faults, the associated sub-surface magma conduits, will be used to assess their field relationships to the eruptive products.

The source and petrogenesis of the magmas within the complex and linking eruptive products to sub-surface magma conduits. Geochemistry will be used to assess the source of the magmas and the influence of crustal contamination and magma mixing. Geochemical fingerprinting will facilitate links to be made between eruptive products and feeder magmas and further constrain the evolution of the complex.

The rates and timescales of caldera collapse. Volcanological, structural and magmatic data will be integrated with high precision radiometric dating to better constrain the rates and timescales of formation of the complex.

These results will allow the development of an integrated volcanological-petrogenetic model for the complex. Such an integrated approach has recently been utilised for the Arran Central Complex (Gooday et al. 2018), and has the potential to yield significant new insights into present-day explosive volcanism.


Candidate Requirements
This project would suit a student who is interested in volcanology and magmatic processes. Students who have an interest in field volcanology and in using geochemistry and geochronology to decipher petrogenetic processes and timescales in an ancient magmatic centre are particularly encouraged to apply.

Training
The project will provide training in field geology, volcanology, petrology, geochemistry, geochronology and analytical techniques (ICP-MS & ICP-OES and isotope analyses in Cardiff), together with radiometric dating at the NERC Isotope Geosciences Laboratories and the Scottish Universities Environmental Research Centre. In Cardiff the student will be part of a cross-School group of staff, post-doctoral scientists and students working on global magmatic processes. The links with the Camborne School of Mines and Glasgow department will also enhance the student’s training.

How to apply:

You should apply to the Doctor of Philosophy in Earth and Ocean Sciences with a start date of October 2020, including:

Your CV
a personal statement
two references (applicants should have a third academic referee, if the two academic referees are within the same department)
current academic transcripts.

In the research proposal section of your application, please specify the project title and supervisors. Copy the project description in the text box. In the funding section, please select ’I will be applying for a scholarship/grant’ and specify that you are applying for advertised funding from NERC GW4+ DTP.

If you wish to apply for more than one project please contact us.

The deadline for applications is 16:00 on 6 January 2020.

Shortlisting for interview will be conducted by 31 January 2020.

Shortlisted candidates will then be invited to an institutional interview. Interviews will be held in Cardiff University between 10 February and 21 February 2020.