Abstract
The Konos Hill prospect in NE Greece represents a telescoped Mo–Cu–Re–Au porphyry occurrence overprinted by deep-level high-sulfidation mineralization. Porphyry-style mineralization is exposed in the deeper parts of the system and comprises quartz stockwork veins hosted in subvolcanic intrusions of granodioritic composition. Ore minerals include pyrite, molybdenite, chalcopyrite, and rheniite. In the upper part of the system, intense hydrothermal alteration resulted in the formation of a silicified zone and the development of various advanced argillic alteration assemblages, which are spatially related to N–S, NNW–SSE, and E–W trending faults. More distal and downwards, advanced argillic alteration gradually evolves into phyllic assemblages dominated by quartz and sericite. Zunyite, along with various amounts of quartz, alunite, aluminum phosphate–sulfate minerals (APS), diaspore, kaolinite, and minor pyrophyllite, are the main minerals in the advanced argillic alteration. Mineral-chemical analyses reveal 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 an almost stoichiometric composition. Mineralization in the lithocap consists of pyrite, enargite, tetrahedrite/tennantite, and colusite. Bulk ore analyses of mineralized samples show a relative enrichment in elements such as Se, Mo, and Bi, which supports a genetic link between the studied lithocap and the underlying Konos Hill porphyry-style mineralization. The occurrence of advanced argillic alteration assemblages along the N–S, NNW–SSE, and E–W trending faults suggests that highly acidic hydrothermal fluids were ascending into the lithocap environment. Zunyite, along with diaspore, pyrophyllite, and Sr- and Rare Earth Elements-bearing APS minerals, mark the proximity of the hypogene advanced argillic alteration zone to the porphyry environment.
Highlights
Porphyry deposits are characterized by a zonation of mineralization and associated types of hydrothermal alteration
Hydrothermal alteration and mineralization occurring in the Kassiteres–Sapes district have been well-studied
Advanced argillic-altered lithocaps have been recognized at a number
Summary
Porphyry deposits are characterized by a zonation of mineralization and associated types of hydrothermal alteration In most deposits, this zonation comprises an inner, strongly mineralized part hosted by potassic alteration, which is outwardly replaced by sericitic and more distally by propylitic assemblages, the latter being commonly dominated by epidote and chlorite [1]. The vapor condenses into near-surface fluids in a relatively shallow environment [7,8], where leaching of the host rock by the most acidic condensate leaves residual silica that recrystallizes to quartz and forms the core of the alteration [8] In cases where such fluids affect porphyritic magmatic rocks, commonly, the result is vuggy textures
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