Microbes, mud, mucus and minerals: deep-time record of microbial environments and processes (ANDREWS_UENV17EE)
Reconstructions of palaeo-environmental conditions from geological proxies usually target fossil skeletons or carbonate mineral cements. Carbonate concretions are interpreted as mineralized by-products of in-sediment microbial activity; however, a lack of modern analogues limits understanding of formative biogeochemical processes. Detection of unambiguous microbial biomarkers in concretions remains elusive, and hypotheses regarding the role of microbial EPS (“mucus”) in initial growth phases remain untested. Moreover, newly-published clumped isotope (CI) temperatures from concretions suggest warmer conditions and deeper burial than indicated by geological context. Thus the value of concretions as deep-time environmental and microbiological repositories is under-explored, despite their potential to “lock-in” paleo-temperatures, -salinities and other environmental parameters.
Project Aims and Objectives
Jurassic concretions are the initial focus. These started forming shortly after deposition in waterlogged sediment, were buried, exposed to hydrogeological regimes, exhumed by erosion, and have captured a time-integrated record of temperature and pore fluid changes in their cements. Cementation environments will be established by novel CI techniques in a framework of detailed petrographic and geochemical data. New protocols will be developed for isolation of microbial biomarkers and entombed fossil microbial biomass. Parallel experiments using modern sediments and microbial cultures will replicate environmental conditions of the earliest stages of concretion genesis. The aim is to understand how concretion-bearing sediments were physically and biochemically modified by microbial consortia.
Work Plan and Training
In Year 1 material will be collected from classic sites in the UK, followed by training in petrography, stable isotopic and organic geochemical analyses. Culture experiments will be initiated. The main data-gathering phase will be in Year 2 and focus on CI thermochronology, biomarker extraction and characterization of microbial biomass. Data integration and interpretation will be concluded in Year 3.
Project Aims and Objectives
UEA has a vigorous geochemical research cluster led by 5 experts in sedimentary geology, palaeoclimatology and palaeooceanography with excellent facilities: mass spectrometers, GC-MS, laser ablation ICP-MS, SEM and XRD. Training in both organic and inorganic techniques and multi-disciplinary integration are key features of this project, which will suit Earth Science students with aptitude for soft-rock geochemistry. Resulting skills will be of key value to hydrocarbon and environmental industries.
This project has been shortlisted for funding by the EnvEast NERC Doctoral Training Partnership, comprising the Universities of East Anglia, Essex and Kent, with twenty other research partners.
Shortlisted applicants will be interviewed on 14/15 February 2017.
Successful candidates who meet RCUK’s eligibility criteria will be awarded a NERC studentship. In most cases, UK and EU nationals who have been resident in the UK for 3 years are eligible for a full award. In 2016/17, the stipend was £14,296.
For further information, please visit www.enveast.ac.uk/apply.
- Deflise, W.S and Lohmann, K.C. (2016) Evaluation of meteoric cements as a proxy material for mass-47 clumped isotope thermometry. Geochim Cosmochim Acta 173; 126-141
- Hendry et al. (2006) Jurassic septarian concretions from NW Scotland…marine mudrock diagenesis. Sedimentology 53; 537-565
- Lloyd, S.J et al. (2014) Clumped-isotope constraints on cement paragenesis in spetarian concretions. J Sed Research 84; 1170-1184
- Andrews, J.E et al. (2016) Exhumed hydrocarbon-seep authigenic carbonates from Zakynthos Island (Greece): concretions not archaeological remains. Marine Pet Geology, 76, 16-25
- Eley, Y, Pedentchouk, N., & Andrews, J.E. (2014) Understanding 2H/1H systematics of leaf wax n-alkanes in coastal plants at Stiffkey saltmarsh, Norfolk, UK. Geochim Cosmochim Acta, 128, 13-28. doi.org/10.1016/j.gca.2013.11.045
Co-SupervisorsDr Nikolai Pedentchouk, School of Environmental Sciences, University of East Anglia
- Start date 1 October 2017
- Programme PhD
- Mode of Study full time
- Studentship Length 3.5 years
- Acceptable First Degree Earth Sciences or a similar discipline
- Minimum Entry Standard 2:1 Honours degree