PhD: Using novel techniques to investigate foraminifera biomineralisation and geochemistry

Project Summary

Planktonic foraminifera are single-celled marine protists that build a calcium carbonate (calcite) shell, which is readily preservable in deep sea marine sediments. They have existed for ~150 million years, are found in all our global oceans, and have one of the best species-level fossil records known to science. Consequently, they are widely employed for palaeoenvironmental and biostratigraphic research and are increasingly becoming a model system for macroevolutionary analysis.

Despite decades of research effort, the mechanisms by which planktonic foraminifera build their calcite shells are still elusive. This project will utilize a technique common to material and physical sciences, Electron Back Scatter Diffraction (EBSD) along with a variety of in-situ chemical analyses techniques to investigate the shell wall at the microstructural level. Our aim is to better understand how foraminifera biomineralization takes place, how the details of the biomineral structures may vary between species (i.e. twinning frequency and type) and how these structures can change once the foraminifera shells settle on the seafloor after death. Critically, microstructural changes in the calcite wall may also reflect changes in the chemistry of the shell which can have implications for their use in palaeoenvironmental reconstructions which typically rely on the preservation of primary biogenic calcite.

Objectives
1. Investigate microstructural differences in the biomineralisation processes of planktonic foraminifera with differing wall textures.
Quantify changes microstructure of planktonic foraminifera with differing preservation histories and investigate the implications for alteration of trace metal geochemistry.
2. Investigate the prevalence of calcite twinning throughout the evolutionary history of planktonic foraminifera and the implications for shell strength.

Methods
The student will mine the geological archive of planktonic foraminifera to select specimens from a range of wall textures, ecologies, genera, and preservation histories. These specimens will be subject to a range of microscopy and microanalytical geochemical techniques. The student will become an expert in foraminifera taxonomy and ecology and gain experience in various analytical techniques, such as Light Microscopy Z-stack image capture, Electron Back Scatter Diffraction, Scanning Electron Microscopy, Fore Scatter Microscopy, and Electron Microprobe Analysis of trace element geochemistry.

Impact and publications
This project will use cutting-edge methodologies to investigate foraminifera biomineralisation, preservation, and evolutionary strategies. The work is of broad interest to a wide variety of Earth and biological scientists and is easily divisible into publications that form consecutive chapters of the PhD thesis.

A nurturing training and research environment
The student will be based within the lab of Dr Aze within the Earth System Science Institute (ESSI) at the University of Leeds. The Aze Lab puts work-life balance and student-led development at the forefront. The welcoming and collegiate atmosphere fostered within ESSI and the Palaeo@Leeds Research Group allows students to explore a wide range of research activities as well as being an in encouraging and nurturing workplace environment. The student will also have direct supervision from other world-leading experts on the supervisory team, such as Prof Sandra Piazolo , Dr Eleanor John (Cardiff University) and Prof Paul Pearson (UCL) and will have opportunities to present their findings at a host of major conferences, attend international summer schools, and engage with a wide range of training opportunities.