Project highlights

  • Geochemical transect through a little known continental arc
  • Builds on the legacy collections of the British Antarctic Survey
  • Develop a wide range of analytical geochemical skills
  • Link geochemical variability to plate reorganisations and magmatic flare-ups using 3D mantle modelling.

Overview

The poorly understood Antarctic Peninsula volcanic arc was an active continental margin between the Early Late Jurassic and the Early Miocene. 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 either no geochronological constraints or geochemical investigations of the arc development. A recent study of the available data (Leat and Riley, 2018) found four chemically distinct volcanic groups within the arc: calc-alkaline, high-Mg andesites, adakites and a peralkaline high-Zr group. However, few constraints between the groups are known, including their timing within arc development and their relation to each other, and what their significance was to the changing margin dynamics of the time. The Leat and Riley (2018) study has highlighted the perhaps unusual feature of numerous high-Mg andesites within the arc, but the significance of this is uncertain due to a lack of geochronological controls. A migration of the arc toward the trench is indicated to have occurred during the Cretaceous, but is also very poorly constrained due to the lack of age data. New isotopic ages will constrain the changing melt conditions along and across the arc and will be linked into the development of geodynamic models for the area.

This project will take advantage of the exceptional collection of samples held by the British Antarctic Survey and access to it through BAS scientist Dr Riley. Furthermore, the link between UoL and BAS will be 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 this project will be to learn how the high-Mg andesites and adakites fit into the development of the Antarctic Peninsula arc, what the controls their genesis, and what this tells us about the changing conditions of melt production along the Antarctic Peninsula arc during its life cycle of development and demise.

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.

Image of columnar jointed Cretaceous arc volcanic rocks

Figure 1. Columnar jointed Cretaceous arc volcanic rocks from Central Palmer Land.

Case funding

This project is suitable for CASE funding

Host

University of Leicester

Theme

  • Dynamic Earth

Supervisors

Project investigator

Dr Tiffany Barry, University of Leicester ([email protected])

Co-investigators

  • Drs Catherine Greenfield, University of Leicester ([email protected])
  • Dan Smith, University of Leicester ([email protected])
  • Dr Phil Leat, Honorary Fellow – University of Leicester
  • Dr John Smellie, Honorary Fellow – University of Leicester
  • Dr Teal Riley, British Antarctic Survey.

How to apply

Methodology

The student will work with Drs Leat, Smellie and Riley to assess the legacy sample archive. This will involve sample characterisation and compilation of their current data. With selected samples, the student will: (1) date the samples using the technique best suited for the rock (either U/Pb or Ar-Ar dating); and (2) geochemically characterise the samples using whole rock XRF, ICP-MS, and radiogenic isotopes (Sr-Nd-Pb-Hf). The student will receive full training in these techniques and be taught how to run the samples for themselves, where possible. The data will be used to build up a geodynamic model of the development and demise of the arc which previously has not been possible due to the lack of age constraints. Constraints will then be used to build 3D numerical models to look at the links between plate dynamics and melt genesis. This will be the first study to examine the arc evolution, and the student will be expected to compare the arc development with other well-characterised arcs such as the Trans-Mexican volcanic belt and the Chilean arc. Although there is no fieldwork to Antarctica planned, fieldtrips will be arranged to other global arcs, for example to Chile, to examine analogous settings.

The student will join a well established research group in the University of Leicester in geochemistry and petrogenesis.

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.

In addition to the geochemical techniques and 3D modelling described above, there will be opportunities to present within lab groups and seminars at Leicester and to national and international meetings (e.g. VMSG). Training will be provided on science writing for international publications, and for research proposals.

Partners and collaboration

A strength of the project is that the student will benefit from working closely with experts from the British Antarctic Survey who have worked in Antarctica for many years and been involved in the collection of the sample suites.  Two of the scientists are expert geochemists and the other a highly experienced volcanologist. This project is made possible only by their involvement.

Further details

We would very strongly encourage anyone considering an application to get in touch with us in advance for an informal chat about the project at an early stage of any application. We would expect this to significantly help the candidate with the preparation of their application and increase their chances of success.

Please contact us at: Dr Tiffany Barry – University of Leicester – [email protected]

If you wish to apply to the project, applications should include:

  • A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)

Applications to be received by the end of the day on Wednesday 11th January 2023. 

Possible timeline

Year 1

Bring together the available information for the Antarctic Peninsula arc. Examine the rock collections together with staff from BAS and assemble a representative range of rock types from across and along the arc. Assess what geochemical techniques will be best employed to characterise the rocks. Using the rock crushing, XRF and ICPMS facilities at Leicester, begin characterising the samples. Develop specific questions for a cross section of rock types. Give a presentation within the School.

Year 2

Having selected a sub-set of samples for geochronology, prepare samples for U/Pb and/or Ar/Ar dating. Using the chemical data, determine the petrogenesis of the rocks by undertaking chemical modelling. Focusing on detailed questions of source for the melts, select a subset of samples for a radiogenic isotope study. Give a presentation at a national meeting.

Year 3

Interpret the isotope, geochronological and wholerock data to draw together an evolutionary model of the development of the volcanic arc. Work this up as a 3D geodynamic model. Contrast this with the development of other continental arcs and assess the implications for regional dynamics. Give presentation at international meeting. Thesis writing.

Further reading

  • Leat, P.T. and Riley, T.R. Antarctic Peninsula & South Shetland Islands: volcanology, 2021. 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, Memoirs, 55, 185 – 212.
  • Leat, P.T. and Riley, T.R. Antarctic Peninsula & South Shetland Islands: petrology, 2021. 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, Memoirs, 55, 213 – 226.

COVID-19

The project builds on legacy samples that have been collected over many years. No fieldwork is essential, though fieldtrips to analogous areas will be planned throughout the project to facilitate greater understanding and comparisons with the development of the Antarctic arc.