Mineralogical Constraints on the Potassic and Sodic-Calcic Hydrothermal Alteration and Vein-Type Mineralization of the Maronia Porphyry Cu-Mo ± Re ± Au Deposit in NE Greece

Abstract

The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/oligoclase/andesine) + titanite + magnetite + chlorite + quartz ± calcite ± epidote-allanite. The high-oxidation state of the magmas and the hydrothermal fluid circulation were responsible for the metal and sulfur enrichments of the aqueous fluid phase, an increase in O2 gas content, the breakdown of the magmatic silicates and the production of the extensive potassic and sodic-calcic alterations. Brittle deformation also promoted the rapid upward fluid flow and caused interactions with the surrounding host rocks along the high temperature M-, EB-, A- and B-type veins.

Multi-Stage Introduction of Precious and Critical Metals in Pyrite: A Case Study from the Konos Hill and Pagoni Rachi Porphyry/Epithermal Prospects, NE Greece

“…(e.g., [55]). Porphyry-style mineralization in Western Thrace include the Aisymi-Leptokaria porphyry Mo [57], and a number of Cu-Mo-Re-Au systems, namely the Maronia [58,59], Konos Hill (e.g., [49,[60][61][62]), and Pagoni Rachi prospects (e.g., [63][64][65][66][67]). Important examples of epithermal-style mineralization in West Thrace (Figures 1 and 2) include the Viper (e.g., [68][69][70]) and Perama Hill [71] Au-Ag-Cu deposits, as well as the Achla Tarla, St. Philippos, and Pefka [55,72] polymetallic deposits.…”

Rare and Critical Metals in Pyrite, Chalcopyrite, Magnetite, and Titanite from the Vathi Porphyry Cu-Au±Mo Deposit, Northern Greece

“…fluid. Epithermal (E-type) veins related to the porphyryepithermal transition environment have been previously described in Greece (e.g., Pagoni-Rach, Stypsi, Maronia, Skouries) [33,38]. At Vathi, the E-type veins host base metal sulfides only (Table 1).…”

“…Tungsten, Ce, Th, Nd, and La are the most enriched rare metals at concentrations <75 ppm and are significantly correlated with each other (Supplementary Table S4). In Greece, M-type veins have been previously described from the Pagoni-Rachi, the Maronia, and the Stypsi porphyry deposits [33,49,66]. The M-type veins at Vathi are different in terms of the contained metallic and alteration assemblages and are not associated with the introduction of any hypogene mineralization, as is the case at Pagoni-Rachi [33,49,66].…”

A Fluid Inclusion and Critical/Rare Metal Study of Epithermal Quartz-Stibnite Veins Associated with the Gerakario Porphyry Deposit, Northern Greece

“…Epithermal, high to low sulfidation veins are commonly found peripheral to porphyry systems and porphyritic intrusions [19,63]. Epithermal veins are associated with several porphyry deposits in Greece (e.g., Pagoni Rachi, Maronia, Vathi) [24,33,64]. However, the veins in these deposits do not host massive stibnite [24].…”