Supervisors info:
Στέφανος Κίλιας, Καθηγητής, Γεωλογίας και Γεωπεριβάλλοντος, ΕΚΠΑ
Summary:
The Kassandra mining district belongs to the Serbo-Macedonian metallogenic province of the greater Tethyan mineral belt, forming a NW-trending zone of Oligo-Miocene porphyry. This zone extends from Serbia to Kassandra mining district on the eastern Chalkidiki peninsula in northern Greece (Siron et al, 2019). The Kassandra mining district belongs to the intrusion-related carbonate-hosted replacement deposit class and contains around 12 million ounces (1 ounce=28.35 grams) Au (Eldorado Gold Corp., 2016) in porphyry and carbonate-hosted replacement-style sulfide orebodies making this district one of the most economically significant mining camps in the Serbo-Macedonian metallogenic province (Siron et al, 2016).
The Stratoni fault crosscuts the Kassandra mining district from the east to the west and hosts the Madem Lakkos, Mavres Petres and the Piavitsa prospect and has diminishing Cu concentration with decreasing Pb/Zn and Ag/Au ratios from Madem Lakkos to Piavitsa (Siron et al, 2019).
Piavitsa is located in the western end of the Stratoni fault zone and hosts siliceous Mn-rich replacement bodies and contains an inferred resource of 6.613 Mt grading 4,82 g/t Au and 6.613 Mt with 54 g/t Ag (Eldorado Gold Corporation December 15, 2021).
To describe the mineral paragenesis and the mineralization style of the Piavitsa prospect as well as the reactions of the ore fluid that took place in relation with pre, main and post ore stage we used Optical Microscopy (transmitted and reflected light) and EDS-SEM analysis in order to analyze 13 samples, from seven different diamond drill holes intercepts provided by Eldorado Gold Corporation. These 13 samples are the same samples M. Tzani used in her MSc thesis in 2021, the results we found match the results of her study. Pre-ore stage is dominated by strong carbonate dissolution of primary wall-rock calcite, silicification that is accompanied by As-poor-pyrite, galena, sphalerite, chalcopyrite and Cu-Pb-Sb-sulfosalts and sulfidation. Main-ore stage is identified by the presence of presumable Au-bearing As-pyrite and arsenopyrite. Main ore stage minerals include arsenopyrite, As-pyrite, Fe-kutnohorite 1, rhodochrosite 1, kutnohorite 2, illite, rutile and apatite. Main-ore stage alterations are sulfidation, argillization, silicification, and carbonatization. Post-ore stage is characterized by rhodochrosite 2 which is the product of post-ore carbonatization.
Keywords:
Piavitsa, arsenopyrite, as-pyrite, carlin-type, sulfidation, argillization, decarbonatization, carbonatization, silicification, gold, au, Greek gold deposit, petrography, ore fluids, replacement,,
