related mineralisation

Abstract. The Rosia Poieni porphyry Cu-Au and Rosia Montana epithermal Au-Ag deposits are the largest operating mines in the South Apuseni mineral district, Romania. Rosia Montana is a breccia-hosted low- to intermediate-sulfidation epithermal system, related to strong phreatomagmatic activity due to shallow emplacement of a dacitic dome structure. The Rosia Poieni deposit, situated about 4 km NE of Rosia Montana, is a porphyry copper system with a high-sulfidation epithermal overprint. This study provides the first high-precision U-Pb dating of Miocene magmatic and hydrothermal events in the South Apuseni Mountains. Together with the existing 40Ar-39Ar data, the new results show clearly that the two deposits belong to two separate magmatic-hydrothermal systems, the porphyry copper system of Rosia Poieni being about 3 Ma younger than the neighbouring Rosia Montana epithermal deposit. The timing of the porphyry mineralization at Rosia Poieni has been bracketed by dating the main Poieni diorite intrusion (9.42 ± 0.14 Ma) and a later intra-mineralization dike (9.16 ± 0.10 Ma), cutting a mineralized porphyry stockwork and cut by later porphyry veins. Whereas the magmatism at Rosia Montana is dated at 13.15-13.61 Ma by U-Pb dating on zircons and the epithermal mineralization there – at 12.71-12.85 Ma by 40Ar-39Ar dating o