First zunyite-bearing lithocap in Greece: The case of Konos Hill Mo-Re-Cu-Au porphyry system

Abstract

<p>The Konos Hill prospect, represents a telescoped Mo-Re-Cu-Au porphyry system overprinted by a high sulfidation event. Porphyry mineralization is exposed in the deeper parts of the study area and comprises quartz stockwork veins, hosted in subvolcanic bodies of granodioritic composition. In the upper topographic levels, a significant hydrothermal alteration overprint predominates, and consists of silicification and various advanced argillic alteration assemblages, related to N-S and E-W trending faults. Further outwards, advanced argillic alteration gradually evolves into phyllic assemblages dominated by sericite. Zunyite, described for the first time from a lithocap in Greece, along with various amounts of quartz, alunite, APS minerals, kaolinite, pyrophyllite and diaspore constitute the major advanced argillic alteration minerals in the area. Mineral-chemical analyses revealed significant variance in the SiO2, F and Cl content of zunyite. Alunite supergroup minerals display a wide compositional range corresponding to members of the alunite, beudantite and plumbogummite subgroups. Diaspore displays almost stoichiometric composition with traces of TiO2, BaO, Ce2O3 and Nd2O3. The presence of the above-mentioned minerals indicates that low pH hydrothermal fluids flowing through fault planes resulted in extensive advanced argillic alteration in the area. The discovery of zunyite points towards an enrichment of volatile elements like F and Cl in the hydrothermal fluid, and helps to set constrains on the physicochemical conditions and the evolution of the mineralization and associated alteration.</p>