Petrological and geochronological characterization of the porphyry-epithermal system of Čukaru Peki, Bor Metallogenic Zone, East Serbia

• Čukaru Peki is a high-sulfidation epithermal-porphyry deposit, Bor zone. • ČP is composed of V1A (90–85 Ma) fertile and V1B (<85 Ma) barren andesites. • V1A1 (∼89 Ma) extrusive andesites host porphyry mineralization (Re/Os ∼ 88–87 Ma). • V1A2 (88–86 Ma) andesite/diorite shallow intrusions are early to late porphyries. • V1A3 (∼85 Ma) extrusive/volcaniclastic andesites host epithermal mineralization. The study focuses on the formation of the newly discovered high sulfidation epithermal and porphyry deposit of Čukaru Peki (ČP) that belongs the Bor Metallogenetic Zone(Apuseni-Banat-Timok-Srednogorie belt). New data on petrography and U/Pb (zircon), Re-Os (molybdenite), and 40 Ar/ 39 Ar (alunite) ages, suggest that the ČP is composed of older (V1A; 90–85 Ma) and fertile plagioclase-hornblende andesite and younger (V1B; <85 Ma) and barren hornblende-plagioclase andesite. The V1A subphase consists of three pulses. V1A1 (89.5 ± 0.4 Ma and 89.2 ± 0.4 Ma) is represented by extrusive andesite with poor relicts of potassic alteration strongly overprinted by argillic/phyllic alteration; the porphyry mineralization is confined to deeper levels and occurs as impregnations of chalcopyrite, covellite, bornite, digenite and enargite (pyrite is ubiquitous). V1A2 (88.4 ± 0.5–86.0 ± 0.1 Ma) are andesite/diorite porphyries distinguished into P1, P4 and P9; they are affected by potassic alteration with the proportion of phenocrysts and the abundance of quartz(±sulfide) veins decreasing from P1 through P4 and P9 and with chalcopyrite and bornite (±pyrite) as the main ore minerals. V1A3 (87.5 ± 0.5–85.2 ± 0.2 Ma) are coarsely porphyritic plagioclase-hornblende(±biotite) extrusive/ volcaniclastic andesites that host epithermal massive sulfide mineralization and are affected by advanced argillic alteration. The age of the ČP porphyry mineralization is constrained by Re-Os age on molybdenite of 88–87.3 Ma ± 0.4 Ma, which is very close to the age of porphyry mineralization at Veliki Krivelj and is around 3 m.y. older than those of Bor. The obtained 40 Ar/ 39 Ar alunite ages of around 81 Ma most likely record the time of the formation of supergene alunite.