Ore genesis and hydrothermal evolution of the Gülkonak Fe (Cu) skarn deposit, Central Anatolia, Türkiye: Insights from fluid inclusions, stable isotopes (C–O–S), and geochronology
Journal of Geochemical Exploration, cilt.292, 2027 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 292
- Basım Tarihi: 2027
- Doi Numarası: 10.1016/j.gexplo.2026.108229
- Dergi Adı: Journal of Geochemical Exploration
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Artic & Antarctic Regions, Chemical Abstracts Core, Compendex, Geobase, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Central Anatolia, C–O–S isotopes, Fluid inclusions, Gülkonak Fe (Cu) deposit, Pyrite ReOs age
- Ankara Üniversitesi Adresli: Evet
Özet
The Central Anatolian Crystalline Complex (CACC), one of the continental fragments in the Alpine–Himalayan orogenic belt, hosts numerous granitoids and their associated temporally and spatially related concealed porphyry Mo (Cu) and Fe, Fe (W), Pb-Zn skarn deposits. Within this complex, the late Cretaceous Behrekdağ granitoid is home to the Gülkonak Fe (Cu) skarn deposit. Four paragenetic stages were identified for skarn formation in the iron deposit: (1) prograde skarn (garnet + clinopyroxene), (2) retrograde skarn (magnetite + epidote ± calcite ± quartz ± chlorite ± pyrite ± chalcopyrite), (3) carbonate (calcite + quartz), and (4) supergene stages (hematite + goethite ± siderite ± chalcocite ± bornite ± covellite). During the prograde stage, the coexistence of vapor-rich (V-type), liquid-rich (L-type), and halite-bearing (S-type) inclusions in garnet—characterized by high salinities (11.2–46.4 wt% NaCl eq.) and similar homogenization temperatures (410–473 °C)—suggests fluid immiscibility derived from the crystallizing granitic magma. Coexisting L- and V-type inclusions in epidote (L-type: 414–429 °C; V-type: 401–434 °C) indicate that boiling occurred during the main mineralization stage. The retrograde stage developed as pressure decreased from lithostatic to hydrostatic conditions, with the main magnetite and copper mineralization forming as a result of boiling at 90–229 bar and depths of 0.9–2.3 km under hydrostatic conditions. The δ18O and δ13C values of calcite from this stage range from 9.70 to 15.90‰ and − 6.81 to −3.49‰, respectively. High fluid–rock ratios inferred from C-O isotope data show that the fluids responsible for magnetite deposition were predominantly magmatic, whereas meteoric water input increased during the sulfide deposition. The δ34S values of sulfides (4.5–5.5‰), Ni contents (103–2840 ppm), and Re-Os compositions (Re = 7.93–16.67 ppb; Os = 6.65–18.80 ppt) of pyrite demonstrate that the ore-forming solutions were derived from a mixture of lower crustal and mantle components. Re-Os dating of pyrite yielded a mineralization age of 74–73 ± 1.0 Ma. The carbonate stage is characterized by low-temperature fluids (121–186 °C). The δ18O and δ13C values of calcite and siderite range from 16.26 to 22.53‰ and − 5.85 to −10.04‰, respectively, indicating the involvement of low-temperature fluids with a possible contribution from organic matter. Our results imply that the Gülkonak is a typical skarn deposit that formed within a porphyry system, and a combination of factors such as two episodes of boiling, cooling, fluid mixing, fluid–rock interaction, and pH variation exerted a significant role in the precipitation of ore minerals.