Multistage fluorite mineralization in the southern Black Forest, Germany: evidence from rare earth element (REE) geochemistry

Abstract. The Black Forest hosts a wide range of hydrothermal mineralization, including fluorite–barite vein deposits. In detailed investigation the Finstergrund and Tannenboden deposits in Wieden mining district (southern Forest), diversity, geochemical evolution relative chronology multistage fluorite precipitation is tracked on basis rare earth element (REE) geochemistry, geologic field relationships crystal zoning. Geochemical discrimination mathematical λ coefficients suggest total seven REE groups, at least three distinguishable post-Variscan fluid mobilization events independent formation histories for despite their spatial proximity. Fluorite mineralization deposit evolved over generations, was derived from gneissic source aquifers comprises five distinct groups: first generation characterized by above 200 ∘C (“group III”), below I”) after fractional crystallization IV”); second remobilized II”); third revealed meteoric water mixing V”). associated with two patterns same generation: VII”) cooling VI”). Its aquifer lithology best matches migmatites contrary to previous models that either or granitic rocks Forest. decoupled history between tectonically controlled as suggested new genetic model district. argues change local percolation network termination activity event. exemplified combination other mineralizations Forest, provides unique insights into lithospheric origin behaviour various fluid–rock interaction processes occurring large systems. diversity emphasizes need investigations individual