The research group for Geomicrobiology at the Institute for Geosciences at the University of Tübingen is looking for a PhD student working for 3 years on
‘Microbial and diagenetic origins of Fe minerals in Precambrian Banded Iron Formations‘
Banded Iron Formations (BIFs) are Precambrian, sedimentary deposits consisting of iron minerals and silicates that were deposited during a time of major changes in Earth atmosphere and biosphere. Understanding the mechanisms of BIF deposition therefore allows a better understanding of the earliest evolution of life and geochemical conditions on our planet. The deposition of BIFs is traditionally explained by a chemical oxidation of Fe(II) by cyanobacterial O2 and precipitation of Fe(III) minerals. However, there is increasing evidence that for the formation of the oldest BIFs, O2-independent mechanisms are necessary and that photoautotrophic Fe(II)-oxidizing bacteria could have fulfilled this function. As a consequence, Fe minerals in association with cell organic matter would be deposited at the seafloor.
The long term diagenetic fate of such cell-mineral aggregates is unknown and is will be the primary question of the PhD candidate. Our approach involves cultivation of Fe(II)-oxidizing bacteria in the presence of high silicate concentrations simulating Precambrian oceans. The precipitates will be treated in high-pressure autoclaves and the mineralogy and trace metal distribution will be analyzed and compared to BIF samples collected in South Africa and Canada. The project will also quantify the partition coefficients for biologically essential trace elements in BIF minerals. The goals of the project are i) to elucidate the primary or diagenetic origin of BIF mineral assemblages based on experimentally-constrained textures and associations of diagenetic minerals and ii) to constrain biological activity at the time of BIF deposition by determining the trace metal concentration and distribution in Precambrian seawater and BIFs.
The candidate will work in collaboration with researchers from Canada and the US and will have the opportunity to present her/his results in international journals and at international conferences.
We are offering a PhD position in an interdisciplinary, international, young and dynamic team of microbiologists, geochemists and geoscientists. This position provides an opportunity for the candidate to work at where various fields of science converge, to be creative, and to challenge themselves. Ideal candidates have a solid background in geochemistry and/or geosciences and are interested in geomicrobiology. Applicants must have the ability to work in a team, have good management and communication skills and should be highly motivated and committed to pursuing interdisciplinary research. Good computer and language skills (English) are necessary.
The start date can be July 1st or as soon as possible thereafter. The employment (TVL E13, 50%) will be arranged by the administration of the University of Tübingen. Disabled persons will be preferred in case of equal qualification.
Applications should be sent by email before May 30th to:
Prof. Dr. Andreas Kappler, Geomicrobiology group, Center for Applied Geosciences, University of Tübingen Sigwartstrasse 10, D-72076 Tübingen, Germany, Phone: ++49-7071-2974992
Email: andreas.kappler@uni-tuebingen.
More information including recent publications on the advertised PhD topic can be found on our website: http://www.geo.uni-tuebingen.
