NERC GW4+ DTP PhD studentship Phosphate in belemnite fossils: A new palaeo-nutrient proxy?

University of Exeter - College of Life and Environmental Science

Main supervisor: Prof. Stephen Hesselbo (Camborne School of Mines, University of Exeter)

Understanding biological productivity of marine palaeoenvironments is severely complicated by the lack of a direct proxy for nutrient availability. Such a proxy, however, would significantly improve our understanding of how the Earth system operates, both at steady state and during transient events of severe environmental change. Currently available tools for approximating this parameter require work-intensive laboratory routines and expensive analytical equipment, making the generation of large, robust datasets difficult. The fossil remains of belemnites are ubiquitous in Jurassic and Cretaceous shelf sediments and provide a potential target for revolutionizing the understanding of nutrient availability in marine environments throughout this time interval. A considerable amount of phosphate (ca. 0.4 to 1 atom P per 1000 atoms Ca, Fig. 1) is present in the calcite rostra of belemnites (Fig. 2) which can be readily measured by spectrophotometry. The amount of phosphate in the rostra is expected to be dominantly controlled by the amount of phosphorus present in ambient water. The P concentration is likely to carry an additional, species-specific signature that may aid in species determination by way of chemical characterization.

The main aim of the project is to assemble comprehensive records of belemnite P concentration from key regions throughout important intervals of Mesozoic environmental change. Candidate study targets are the Pliensbachian-Toarcian (Early Jurassic) strata from the Yorkshire coast (Cleveland Basin; NE England), the Mochras drill core (Cardigan Bay Basin; NW Wales) and Peniche (Fig. 3; Lusitanian Basin; Portugal). Work on other time intervals in Jurassic and Cretaceous as appropriate can be included according to the interest of the candidate. A further aim of the project is to develop a method for extracting phosphate from the belemnite rostra for the determination of the oxygen isotopic composition of the phosphate molecule' a proxy that can give further insights into the dynamics of nutrient cycling in the water column. The findings of the project will tie in with ongoing collaborative research at the Universities of Exeter, Leeds, Oxford, the BGS and international partner organizations advancing the understanding of Early Jurassic palaeoenvironment (JET project for understanding Early Jurassic environments and time scale; NERC large grant and ICDP support to PI Prof. Stephen Hesselbo). The candidate will thus be able to experience a variety of academic working environments, and be associated with a prestigious research project bringing together leading experts in their field.

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP). The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus six Research Organisation partners: British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology, the Met Office, the Natural History Museum and Plymouth Marine Laboratory. The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science. For further details about the programme please see http://nercgw4plus.ac.uk/

See please http://www.exeter.ac.uk/studying/funding/award/?id=2258 for more details on how to apply.

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Type / Role:

PhD

Location(s):

South West England