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

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 were for 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.

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.

 

Host

University of Leicester

Theme

  • Dynamic Earth

Supervisors

Project investigator

Co-investigators

  • Dr Dan Smith (University of Leicester)
  • Phil Leat (University of Leicester)
  • John Smellie (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 to put together a subset of samples for the research. This will involve characterisation of the samples, and compilation of their geographic localities and available data. With the 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. This will be the first study to examine the arc evolution, and the student will be expected to compare the arc development to other well-characterised arcs such as the Trans-Mexican volcanic belt. Although no fieldwork to Antarctica is required for the sample collection, fieldtrips will be arranged to other global arcs, to examine analogous rocks in situ.

The student will join a well established research group in geochemistry and petrogenesis.

Training and skills

In addition to the geochemical techniques described above, and geochemical modelling, 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 who have worked in Antarctica for many years and been involved in the collection of many of the sample suits.  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

Please contact Dr Tiffany Barry at the University of Leicester, on [email protected], for further details.

To apply to this project please visit: https://le.ac.uk/study/research-degrees/funded-opportunities/centa-phd-studentships

Possible timeline

Year 1

Bring together the available information for the Antarctic Peninsula arc. Examine the rock collections for the arc and together with staff from BAS bring together 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. Give a presentation within the School and attend a national/international conference.

Year 2

Select a sub-set of samples for geochronology and prepare samples for either U/Pb or Ar/Ar dating. Using the chemical data, determine the petrogenesis of the rocks by undertaking chemical modelling. Select a subset of samples for radiogenic isotope study, and collect data. 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. Contrast this with the development of other continental arcs and assess the implications for regional dynamics. Develop a geodynamic model which can be visualised in a 4D model. Present your results at a major international meeting. Complete thesis writing.

Further reading

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 (2018).

COVID-19

The project builds on legacy samples that have been collected over many years. No fieldwork is essential, though visits to analogous areas would be advantageous for the development of the student’s understanding.