Origin of lithium in deep brines of SW-Germany – first results

Abstract

We focus on the origin of the commonly high lithium (Li) concentrations in continental brines that are characterized by high total dissolved solids (TDS). Our approach comprises geochemical bulk rock analyses to constrain available Li contents and simple leaching experiments on pulverized granitoids and rhyolites of the Schwarzwald. Hydrochemical analyses of the leachates are used to constrain leached Li concentrations. The granitoids indicate a correlation between leached Li and the anorthite content and modal abundance of feldspars, whereas leaching of Li from post-Variscan rhyolites additionally suggests a dependence on grain size and abundance of fluid inclusions. The next steps require a refinement of our experimental approaches and a focus on specific parameters such as alteration, grain size, temperature, and fluid inclusions. Additionally, Li-isotope analyses will be carried out on key samples.