Microbes, mud, mucus and minerals: deep-time record of microbial environments and processes (ANDREWSUENV17EE)

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.

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.

Research Environment
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.

For further information, please visit www.enveast.ac.uk/apply.