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- MakaleYalnız künye2022Scopus SJRQ1Eocene magmatism and associated Fe-Cu mineralization in northeastern Turkey: a case study of the Karadağ skarn
Sipahi, Ferkan; Saydam Eker, Çiğdem; Akpınar, İbrahim; Gücer, Mehmet Ali; Vural, Alaaddin; Kaygusuz, Abdullah; Aydurmuş, Tanju
The metallogenic belt containing numerous skarn mineralized systems starting from Eastern Europe continues through Turkey and Iran. The study area in the Eastern Pontides is within this metallogenic belt. The 44.39 ± 0.53 Ma Karadağ Intrusion sourced skarn mineralization is located along the granitoid-to-limestone contact. The Karadağ Intrusion is an arc-like pluton with medium–high K calc-alkaline and peraluminous–metaluminous affinity. The Karadağ Fe–Cu skarn mineralization (Gümüşhane, Turkey), an exoskarn, is hosted by Late Cretaceous limestone and consists of early garnet, clinopyroxene, and orthoclase with late epidote and chlorite. Primary ore minerals are magnetite and haematite, accompanied by minor amounts of chalcopyrite and pyrite. Pyroxene comprises mostly diopside and less hedenbergitic diopside and johannsenite. Wollastonite is very rare. Garnet is andradite and grossular–andradite. Thus, all these results imply that the Karadağ Fe–Cu skarn mineralization formed under relatively oxidized and Fe-rich conditions. The homogenization temperatures of the fluid inclusions vary from 189°C to 405°C for quartz and 186°C to 430°C for calcite. The salinity contents in the fluid inclusions are within 0.2–9 wt% NaCl equivalent for quartz and 0.4–14.8 wt% NaCl equivalent for calcite. First melting temperatures between −36.5 and −47.4°C were attained with the presence of NaCl–FeCl2± CaCl2 in the initial phase of fluid inclusions. The first melting in the later stage of fluid inclusions is between −3.8 and −17.2°C, thereby, supporting the existence of NaHCO3-Na2CO3-KCl-type salt composition. The δ18O values of minerals are 1.7–10.3‰ for garnet, 11.1–14.6‰ for quartz, 6.4 to 6.8‰ for epidote, and 2.8–3.8‰ for magnetite in the Karadağ skarn mineralization. The δ18O value of epidote indicates magmatic fluid, whereas those of garnet, magnetite, and quartz suggest magmatic fluids together with less meteoric effect. The δ18O values in limestone (18.7 to 22.3‰), marble (8.7‰), and calcite (10.5 to 12.2‰) were depleted relative to typical δ18O contents of marine carbonates (20 to 30‰). Moreover, the C isotope values of calcite (−5.4 to −1.4‰), marble (−2.1‰), and limestone (1.0 to 1.2‰) reflect those of metamorphic rocks and skarns (−4.0 to 3‰ and −18 to 2‰). Mineral paragenesis, fluid inclusion, and stable isotopic signatures are consistent with ore mineralization caused by the interaction of magmatic fluids with carbonate host rocks. Karadağ Fe-Cu skarn mineralization, associated with Karadağ postcollisional magmatism, is an example of skarn mineralized system in the Eastern Pontides.
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İncele - MakaleYalnız künye2017Scopus SJRQ1Formation of the Eğrikar (Gümüşhane) Fe–Cu skarn type mineralization in NE Turkey: U–Pb zircon age, lithogeochemistry, mineral chemistry, fluid inclusion, and O-H-C-S isotopic compositions
Sipahi, Ferkan; Akpınar, İbrahim; Eker, Çiğdem Saydam; Kaygusuz, Abdullah; Vural, Alaaddin; Yılmaz, Meltem
The Eğrikar Fe–Cu skarn type mineralization is located approximately 100 km NW of Gümüşhane in NE Turkey. Geochemical analyses of diorite, which is thought to cause skarn, indicate medium K calc-alkaline (1.3 to ~ 2.3 wt% K2O), metaluminous to peraluminous (A/CNK = 0.76 to 1.13) and resembles a continental arc granite. The age of U–Pb zircon obtained from diorite is 42.3 ± 1.0 Ma, which reflects the age of skarn metasomatism after intrusion into Late Cretaceous sandy carbonates. Skarn formation zones are recognized as endo- and exoskarn. The endoskarn zone mainly consists of pyroxene with hedenbergite (Di4.31–28.14Hd59.29–80.82Jo5.0–35.55) at prograde stage. Mn content of pyroxene increases a slight from endo to exoskarn. Pyroxene is replaced by epidote and hornblende at the retrograde stage. The exoskarn zone comprises garnet with andradite (Ad91-99Gr01–07) and grossular-andradite (Ad44-95Gr05–54), epidote and quartz as silicate minerals, and magnetite and hematite as ore minerals. Magnetite is the abundant ore mineral and is accompanied by chalcopyrite and minor pyrite at retrograde stage. On the basis of fluid inclusion values of minerals, the temperature range for hedenbergite in endo-exoskarn is 350 °C–425 °C, for epidote in exoskarn is 365 °C–376 °C, and for quartz in exoskarn 200 °C–380 °C. NaCl equivalent salinity for hedenbergite 6.88–10.73 wt% and for quartz is 3.9–15.38 wt. The δ18O values of hedenbergite is 4.1 to 4.7‰ and for garnet 3.4‰ at prograde stage, for epidote 7.9–9.2‰, for magnetite 1 to 4.4‰, for hematite − 2.9 to − 1.6‰ and for quartz range between 8.5‰ and 15.2‰. The δ18O value of epidote suggests that oxygen is a magmatic fluid whereas hedenbergite, garnet, quartz and magnetite show the mixing of magmatic and meteoric fluids. In addition, the C isotope values (− 3.2 to 2.8‰) of calcite and marble in Eğrikar Fe–Cu skarn reflect those of metamorphic, and skarns. Based on oxygen isotope data from mineral pairs, the retrograde skarn formation is characterized by epidote–magnetite assemblage formed at 255 °C–438 °C. Fluid oxygen isotope compositions of magnetite and epidote pairs of the exoskarn skarn zone indicate a mixing of magmatic and meteoric fluids with narrow δ18O values between 7.17‰ and 8.9‰. The δ34S values of the pyrites exhibit a narrow range of 3‰ and 4.4‰, thereby indicating that sulfur were probably leached from magmatic rocks. Based on the field and laboratory observation, mineral chemistries, fluid inclusion studies and isotope composition analysis, it is suggested that the Eğrikar Fe–Cu skarn mineralization occurs in a magmatic origin fluids being initially under reduced conditions, subsequently under oxidized conditions, and at shallow depth.
AtıfScopus36WoS33OpenAlex43İncele - MakaleAçık Erişim2013Scopus SJRQ1The genesis of the slab window-related Arzular low-sulfidation epithermal gold mineralization (eastern Pontides, NE Turkey)
Akaryali, Enver; Tüysüz, Necati
The Arzular mineralization is one of the best examples of epithermal gold deposits in the eastern Pontides orogenic belt. The mineralization is hosted by the subduction-related basaltic andesites and is mainly controlled by E-W and NE-SW trending fracture zones. The main ore minerals are galena, sphalerite, pyrite, chalcopyrite, tetrahedrite and gold. Homogenization temperatures of fluid inclusions are between 130 and 295 C for quartz and between 90 and 133 C for sphalerite. Sulphur isotope values obtained from pyrite, galena and sphalerite vary between -1.2‰ and 3‰, indicating that sulphur belongs to magmatic origin and was derived from the Lutetian non-adakitic granitic intrusions in the region. Oxygen isotope values are between 15.0‰ and 16.7‰, and hydrogen isotope values are between -87‰ and -91‰. The sulphur isotope thermometer yielded temperatures in the range of 244-291 C for the ore formation. Our results support the hypothesis that the Arzular mineralization is a low-sulfidation epithermal gold deposit associated with non-adakitic subduction-related granitic magmas that were generated by slab window-related processes in a south-dipping subduction zone during the Lutetian.
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