Research project at Maryland University
The major aim of my research at Maryland University is a detailed investigation of the lithium (Li) isotope compositions and concentrations in carbonatites, their phases and associated rocks in order to characterize and understand
1) the nature of their mantle source region today and through time,
2) mineral-melt and mineral-mineral fractionation of Li isotopes, and
3) the role of liquid immiscibility in stable isotope fractionation processes.
These questions will be addressed by studying carbonatite localities (e.g. Oldoinyo Lengai/Tanzania, Gronnedal-Ika/Greenland, Kaiserstuhl/Germany, Fuerteventura/Spain, ...) that include the major compositional types of carbonatites from different geotectonic settings (continental and oceanic) with different ages (Proterozoic to recent). Because carbonatites occur almost entirely on continents, carbonatites provide useful information about one of the major problems still outstanding in mantle geochemistry, namely the nature of the subcontinental mantle. Carbonatites and their associated rocks also offer an opportunity to study the fundamental processes controlling fractionation in the Li stable isotope system in the temperature range typical for carbonatite crystallization (400-900° C). For the formation of carbonatites, liquid immiscibility is often assumed to play an important role. Due to the considerable structural differences between carbonate and silicate melts, the Li isotope system has the potential to shed light on the role of liquid immiscibility in stable isotope fractionation processes.