The interplay between hydrothermal mineralizations and element redistribution processes related to young tectonic activity - case studies from SW Germany

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Crustal-scale fluid flow related to the extensional rift system of the Upper Rhine Graben, located in southwest Germany and France, has resulted in the formation of a number of very young hydrothermal mineralization styles. Complementary to hydrological and hydrochemical data and models available for active thermal spring systems, which characterize the recent state of rift-related fluid circulation, geochemical and isotopic studies of mineralizations provide an exciting window into the evolutionary history. Preliminary studies of barite-sulphide mineralization of the Wiesbaden thermal spring system point to a prolonged duration of hydrothermal activity on the order of at least 500 kyr. It has also been noted that post-Variscan hydrothermal fluorite-barite-calcite veins located on the shoulders of the Upper Rhine Graben show evidence of a pronounced remobilization, which can be related to very young tectonic and hydrothermal activity. It is proposed to expand the investigation to include different mineralized areas in the surroundings of the Upper Rhine Graben. The study will address the following objectives: (1) mineralogical and geochemical characterization of the young mineralization styles, (2) correlation of stable and radiogenic isotope trends with processes such as fluid mixing or fluid-rock interaction, (3) assessment of the relative role of fluid input and dispersion versus inheritance for element redistribution, (4) reconstruction of the physicochemical conditions prevalent during formation of the mineralization, and (5) development of a consistent geological-geochemical model of young hydrothermal activity.