The poorly understood Antarctic Peninsula continental volcanic arc was active between Late Jurassic and Early Miocene times. Although many expeditions have visited parts of the arc, and the northern end of the arc has been well-studied, there are vast tracts of the arc for which there are neither geochronological - stratigraphic constraints nor geochemical charcterisations . A recent review of the available data (Leat and Riley, in press) found four chemically distinct volcanic groups within the arc: calc-alkaline, high-Mg andesites, adakites and a peralkaline high-Zr group. Within the calc-alkaline group, compositions range from those generated from both depleted and enriched mantles, and variability in the importance of crustal contributions to the magmas is evident in previous studies of volcanic anf plutonic rocks of the arc.
However, few constraints between the magma groups are known, including their timing within arc development and their relation to each other. The Leat and Riley (in press) study highlighted for the first time the perhaps unusual feature of numerous high-Mg adakites within the arc, but the significance of this is uncertain due to a lack of geochronological controls, and the chemical relationship between the adakites and dominant calc-alkaline group. The origin of high-Mg adakites globally is still uncertain but likely to result from melting of mantle that has consumed partial melts of subducting slabs.
The study will test this hypothesis in a location where normal arc rocks (the calc-alkaline group) and adakites were erupted in close proximity. A migration of the arc toward the trench of 25-100 km is indicated to have occurred during the Cretaceous, but again, its timing is very poorly constrained due to lack of geochronological data. New isotopic ages will enable this to be confirmed, and tectonic explanations developed.
This project will take advantage of the exceptional collection of samples from the length of the arc held by the British Antarctic Survey collected over decades, with access to it through collaboration with BAS scientist Dr Riley. The link between UoL and BAS is enhanced by two honorary Leicester scientists Drs Leat and Smellie who have formerly been BAS-scientists and whom collected many of the legacy samples. The aim of the project is to establish how the high-Mg adakites fit into the development of the Antarctic Peninsula arc, what the controls on these rocks were, and what the interplay between the slab dynamics and the crustal controls was in the evolution this arc.
The project will suit a student interested in geochemistry and geochronology, taking apart a poorly explored region, and with a keen interest in petrogenesis and arc magmatism.
UK Bachelor Degree with at least 2:1 in a relevant subject or overseas equivalent.
Available for UK and EU applicants only.
Applicants must meet requirements for both academic qualifications and residential eligibility: http://www.nerc.ac.uk/skills/postgrad/
How to Apply:
Please follow refer to the How to Apply section at http://www2.le.ac.uk/study/research/funding/centa/how-to-apply-for-a-centa-project
and use the Geography Apply button to submit your PhD application.
Upload your CENTA Studentship Form in the proposal section of the application form.
In the funding section of the application please indicate you wish to be considered for NERC CENTA Studentship.
Under the proposal section please provide the name of the supervisor and project title/project code you want to apply for.
Leat, P.T. and Riley, T.R. Antarctic Peninsula & South Shetland Islands II. Petrology. In: Smellie, J., Panter, K. and Geyer, A (Eds.) Volcanism in Antarctica: 200 Million Years of Subduction, Rifting and Continental Break-Up. Geological Society, London, Memoir (in press).