Dr Clemens Vinzenz Ullmann
I am a geochemist with particular interest in the geochemistry of modern and ancient marine shells and am part of the Deep Time Global Change Group. My current role is Researcher Co-I on the NERC and ICDP funded JET project (Integrated Understanding of the Early Jurassic Earth System and Timescale).
The three main topics I am working on are carbonate diagenesis, vital effects related to the process of bio-mineralization and reconstruction of past environments using isotopic and element tracers. I have been involved in work from the Mesoproterozoic up to modern times, but my main focus has been the Jurassic.
Marine animals form carbonate shells which vary greatly in composition, but follow predictable trends, an observation that may help to eventually reconstruct the past composition of seawater with improved certainty. In order to increase the quality of these reconstructions I am actively working on characterising the geochemical patterns of biomineralisation in modern calcite secreting organisms, e.g., bivalves, brachiopods, and barnacles, and fossils of extinct organisms such as the rostra of belemnites.
In order to help understanding past environmental conditions using proxy data, post-depositional effects modifying or erasing the original environmental signatures in sedimentary strata have to be controlled. Through detailed work on fossil materials, and covering novel proxies, as well as studying diagenetic signatures down to species-specific effects, much improved environmental reconstructions become feasible.
The isotopic signatures of large, marine fossil shells have traditionally been used to reconstruct carbon cycle and seawater temperatures. However, the geochemistry of fossils can also help to guide interpretations of palaeoecology which otherwise is limited to the assessment of fossil morphology and comparison to modern relatives. Using innovative methodology for example on belemnite rostra and brachiopod shells, the understanding of their ecology can be improved.
2016- Researcher Co-I; University of Exeter, UK. Early Jurassic Earth System and Timescale (JET)
2014-2016 Leopoldina Fellow; University of Exeter, UK. Research on biomineralization of brachiopods, barnacles and belemnites.
2013-2014 Post Doc; University of Copenhagen, Denmark. Research on geochemical proxies in biogenic carbonates.
2012-2012 Academic visitor; University of Oxford, UK. Lithium isotopes in belemnite calcite and Jurassic chemostratigraphy.
2010-2013 PhD; University of Copenhagen, Denmark.
2008-2010 MSc; Freie Universität Berlin, Germany.
2005-2008 BSc; Freie Universität Berlin, Germany.