Self-funded PhD opportunities

Development and growth of a Neoproterozoic active plate margin

  • Application end date: All year round
  • Funding Availability: Self-funded PhD students only
  • Department: School of Earth and Environmental Sciences
  • PhD Supervisor: Rob Strachan and Craig Storey

The late Neoproterozoic is marked globally by extensional tectonics following the break-up of Rodinia and formation of new oceans. Global compilations of crustal growth ages suggest little growth of continental crust during this period. Recent suggestions that continuous subduction and development of magmatic arcs may only result in net continental growth in a retreating subduction setting, such as eastern Australia in Cambrian-Devonian times, rather than advancing settings such as the modern Andean margin are intriguing and may relate to larger-scale tectonic processes. The formation of supercontinents may also bias the preservation potential of magmatic arc rocks. This project will test crustal growth models during periods of supercontinent dispersal, such as the late Neoproterozoic. The Channel Islands and northwest France contain abundant magmatic rocks formed in an arc setting ~620-570 Ma. Basement gneisses, dated at ~2.1 Ga, occur sporadically and Nd model ages of the arc rocks are ~1 Ga (and older?). This suggests that the arc was built onto either a continental margin or a microcontinental fragment. It is unclear how much juvenile crust was formed and the tectonic setting which allowed preservation of this crust during a major period of rifting and drifting. One approach is to track the U-Pb age and Hf isotopes within zircons from magmatic rocks spanning the development and growth of the arc and eroded remnants of the arc (overlying younger sediments). This approach potentially allows times of major crustal reworking (i.e. S-type granites formed during the onset of extension and slab rollback following accretion and thickening during flat subduction in a back-arc setting) to be distinguished from juvenile magmatism (i.e. I-type granites with large mantle input formed during increased extension and asthenospheric upwelling) and, therefore, an isotopic record of the tectonic development of the arc. Thus we can relate the tectonic setting, along with geological data, to the growth of continental crust in this important period and investigate whether the preservation potential is related to a unique tectonic setting (e.g. a retreating subduction zone) or simply a minor aberration in the overall history of global growth of continental crust.

The student would carry out fieldwork and be trained in in-situ Laser Ablation ICP-MS techniques. This would suit an analytically minded and numerate student with an interest in petrology, geochemistry, tectonics and fieldwork and a future career in academia. It would provide transferable skills for a career in analytical geochemistry and the oil/mineral extraction industries.

Funding Notes:

This PhD opportunity is available to self-funded students. Bench fees may apply. For more information please contact the project supervisor.

How to apply:

To apply or make an enquiry, please visit postgraduate research: Earth and Environmental Sciences

All applications should use our standard application forms and follow the instructions given under the ‘Research Degrees’ heading on the following webpages: http://www.port.ac.uk/application-fees-and-funding/applying-postgraduate/#rd.

When applying please note the project code - SEES3200217