Reconstructing seawater chemistry during the Jurassic and Cretaceous

Applications are invited for a three-year PhD studentship. The studentship will start 1 October 2021

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To apply please use the online application form. Simply search for PhD Geological Sciences, then clearly state that you are applying for a PhD studentship and name the project at the top of your personal statement.

Online application

Before applying, please ensure you have read the Doctoral College’s general information on applying for a research degree.

For more information on the admissions process please contact doctoralcollege@plymouth.ac.uk.

Project description 

Seawater Mg/Ca and Sr/Ca ratios are biogeochemical parameters that reflect the Earth–ocean–atmosphere dynamic exchange of elements and has varied with global climate throughout Earth’s history. Variations are thought to reflect supply to and removal from the oceans e.g. via long-term changes in oceanic crustal production, continental weathering and carbonate deposition. Reconstruction of past seawater chemistry has been based modelling, the geochemical analysis of biogenic carbonate, carbonate veins precipitated in mid-oceanic ridge basalts and evaporites. Some studies based on calcium carbonate veins have suggested seawater Mg/Ca and Sr/Ca ratios were much lower than previous biogenic estimates for the Cretaceous. This discrepancy arises from uncertainties in biogenic carbonate-element partitioning and preservation. Sr and Mg distribution coefficients for oysters and seawater are particularly well established. Surprisingly this palaeo-archive for this key interval of Earth history has yet to be fully exploited. This archive can also provide test of the links of how seawater chemistry has varied with global climate. This project will examine the geochemistry of Late Jurassic-Early Cretaceous oysters from a range of locations where oysters are abundant and well constrained in terms of age and test the fidelity of existing records of biogeochemical cycling. 

This is an exciting opportunity that will involve:

1. Sampling of oysters from a range of biostratigraphically well-constrained marine sections

2. Construct and develop geochemical and oxygen and carbon isotope stratigraphies through the Late Jurassic- Early Cretaceous.

3. Testing of the different proxies used to reconstruct changes in biogeochemical cycling as well as provide inferences regarding rates of oceanic crustal production and continental weathering and observed shifts from aragonite to calcite as the favoured marine biogenic carbonate polymorph.

Eligibility 

Applicants should have a first or upper second class honours degree in an appropriate subject and preferably a relevant masters qualification. 

The studentship is supported for three years and includes full home tuition fees plus a stipend of £15,609 per annum (2021/22 rate). The studentship will only fully fund those applicants who are eligible for home fees with relevant qualifications. Applicants normally required to cover international fees will have to cover the difference between the home and the international tuition fee rates (approximately £12,697 per annum).

If you wish to discuss this project further informally, please contact Professor Gregory Price (g.price@plymouth.ac.uk). 

Please see a list of supporting documents to upload with your application. 

For more information on the admissions process contact doctoralcollege@plymouth.ac.uk.

The closing date for applications is 12 noon on 26 May 2021. Shortlisted candidates will be invited for interview in early June. We regret that we may not be able to respond to all applications. Applicants who have not received an offer of a place by 9 June should consider their application has been unsuccessful on this occasion.