21-EPN-FT1-010: Tracking the Thermal Evolution of the Miocene Ries Crater Lake as a Potential Analogue for Microbial Habitats on Early Mars
Visit by Duncan Mifsud, University of Kent (UK), to TA2 Facility 17 – Isotoptech Stable/Clumped Isotopes Laboratory (Hungary).
Dates of visit: 21 March – 01 April 2022.
Report Summary: We have measured the clumped carbonate (13C18O16O) isotope ratios, as well as the stable isotope ratios δ18O and δ13C, of a number of bioherm, travertine, and crater fill marl samples from a drill core taken from the Nördlinger Ries Crater (NRC) in Bavaria, Germany. The aim of the project was to make use of the clumped carbonate isotope ratios so as to re-construct a palaeotemperature record of the lake environment, which could be used to assess its habitability in the time since its formation. Such information would be useful for assessing the past habitability of similar crater lake environments on Mars, which are presently of great interest.
At first glance, our results demonstrate that the analysed carbonate samples were formed at temperatures well below what would be expected in the NRC lake environment. On closer inspection, however, it was hypothesised that our carbonate samples were either collected from too high up in the stratigraphy, or they were formed under non-equilibrium conditions and thus suffered from kinetic fractionation effects. The result of the latter is a depression of the precipitation temperature as calculated by palaeothermometric scales.
Future studies are planned to investigate samples from suevite (i.e. the oldest crater infill) and to quantify the extent and causes of these kinetic fractionation effects. Future studies on other crater fill marls may thus also be worthwhile.