Mineralogical and geochemical investigations on lamprophyric intrusions of the Gottesberg Sn-(W) greisen deposit, Vogtland, Germany

The Erzgebirge-Vogtland metallogenic province covers a wide variety of tin mineralization (greisen-, vein- and skarn-type) and represents one of the classic Sn regions in the world. The Gottesberg Sn(-W) greisen deposit is located on the western rim of the Eibenstock granite pluton. The multistage Sn mineralization of Gottesberg is closely spatial and temporal related to multiphase intrusions of subvolcanics and brecciation, controlled by a crosscutting area of major deep fault zones. For this work, lamprophyric dikes from latest drill core of Saxore Bergbau GmbH were sampled. Microscopic investigations were supplemented by the method of MLA (Mineral Liberation Analysis). Geochemical analyses of major and trace elements were performed. Previous work focused primarily on the Gottesberg Subvolcanic Suite (rhyolites and microgranites) whereby this work provides the first modern study of lamprophyres from the deposit and their age relationship to other magmatic events and the Sn(-W) mineralization. The porphyritic lamprophyres occur in dikes up to 3.5 m thick, carry xenocrysts of the granite, microgranite and rhyolite, and are partly strongly altered. Amphiboles were replaced by biotite. In the contact with the granite, the dikes form a chilled margin consisting mainly of biotite. Alteration phenomena on the groundmass and xenocrysts were studied. Cassiterite-quartz-sulfide veinlets and enclaves of granite and rhyolite in lamprophyric dikes provide information on the age position of the rocks. Overprinted lamprophyres show Sn and Rb contents >1,000 ppm and F contents up to 1.10 wt.%. Lamprophyre samples with high Zn contents (2.090-3640 ppm) show relatively high In contents (5-15 ppm).