C, O, S and Sr isotope studies on the genesis of Fe-carbonate and barite mineralizations in the Attepe iron district (Adana, Southern Turkey)

The Attepe district consists of Precambrian, Lower–Middle Cambrian, Upper Cambrian–Lower Ordovician and Mesozoic formations. It contains several iron deposits and occurrences. Three types of iron-mineralizations can be distinguished in the area; (i) Sedimentary Fe-sulfide in Precambrian bituminous metapelitic rocks, and Fe-oxides in Precambrian metasandstones (SISO), (ii) vein-type Fe-carbonate and oxides composed of mainly siderite, ankerite and hematite including barite in Lower–Middle Cambrian metacarbonates of the Çaltepe Formation (HICO), (iii) karstic Fe-oxides and hydroxides essentially in the Lower–Middle Cambrian metacarbonates and the unweathered Fe-carbonates (KIO). The latter type is more widespread and located at the upper parts of the most important mineable iron deposits like Attepe deposit.

Oxygen-, carbon-, sulfur- and strontium-isotope studies have been performed on siderites and barites in the vein-type ores, and on calcites in the recrystallized Çaltepe Limestones to investigate the sources and formation mechanism of primary ore-forming constituents. The δ¹³C values of siderites and calcites in limestones of the Çaltepe Formation range from −10.10‰ to −8.20‰, and from −0.8‰ to 2.30‰. Both carbonate minerals show δ¹⁸O values between 17.50–18.30‰ and 16.20–23.00‰, respectively. The δ¹³C and δ¹⁸O isotopic variations do not indicate any direct or linear relations between siderites and limestones. However, it is possible that the carbon and oxygen isotopic compositions of carbonate minerals could be changed to some extent, when limestones were subjected to hydrothermal processes or thermal alterations during metamorphism.

The isotopic values of barites display 32.40–38.30‰ for δ³⁴S and 12.20–14.70‰ for δ¹⁸O. The strontium isotope ratios (0.717169–0.718601) of barites and the sulfur isotope compositions of barites and pyrites suggest that there are no direct linkages of ore-forming compounds neither with a magmatic source nor with sedimentary pyrite formations in the Precambrian bituminous shales of the Attepe formation.

According to the field observations and the stable isotope data, siderites and ankerites should be formed by interaction between iron-rich hydrothermal fluids and Çaltepe limestones, whereas isotope ratios of barites indicate that they were formed by mixing of sulfur-rich meteoric waters and deeply circulated hydrothermal solutions.     

Fluid inclusion and sulfur isotope thermometry of the Inkaya (Simav-Kütahya) Cu-Pb-Zn-(Ag) mineralization, NW TURKEY

The Inkaya Cu-Pb-Zn-(Ag) mineralization, located about 20 km west of the Simav (Kütahya-Turkey), is situated in the northern part of the Menderes Massif Metamorphics. The mineralization is located along an E-W trending fault in the Cambrian Simav metamorphics consisting of quartz-muscovite schist, quartz-biotite schist, muscovite schist, biotite schist and the Ar?kayas? formation composed of marbles. Mineralized veins are 30–35 cm in width. The primary mineralization is represented by abundant galena, sphalerite, chalcopyrite, pyrite, fahlore and minor amounts of cerussite, anglesite, digenite, enargite, chalcocite, covellite, bornite, limonite, hematite and goethite with gangue quartz. Fluid inclusion studies on the quartz samples collected from the mineralized veins indicate that the temperature range of the fluids is 235°C to 340°C and the salinities are 0.7 to 4.49 wt. % NaCl equivalent. The wide range of homogenization temperatures indicates that two different fluid generations were trapped in quartz. Sulfur isotope studies of the sulfide minerals showed that all of the δ ³⁴S values are between ?2.1 and 2.6 per mil. These values are a typical range for hydrothermal sulfide minerals that have sulfur derived from a magmatic source. Pyrite-galena and pyrite-chalcopyrite sulfur isotope fractionation is consistent with an approach to isotopic equilibrium, and calculated temperatures are 254.6 and 277.4°C for pyrite-galena and 274.7°C for pyrite-chalcopyrite. The microthermometric data and sulfur isotope thermometry indicate the existence of a hydrothermal fluid that circulated along the fault crossing the Simav metamorphics and Ar?kayas? formation. Fluid inclusion and sulfur isotope thermometry can be used in combination with ore petrographical and geological information to provide site-specific targets for meso-hypothermal metal concentrations.     

Genetic characteristics of the Gozecukuru As-Sb deposits near Kutahya, Turkey

Gözeçukuru As-Sb-Pb-Zn mine is located 1.2 km NW of Sahin village and 22 km west of Kütahya in NW Turkey. The aim of this study is to explain the genetic characteristics of the As-Sb deposits by using multivariate statistical analysis methods. Low-grade metamorphic rocks of the upper Paleozoic Sahin Formation occur as the basement of the study area. Cenozoic volcano-sedimentary units (Tavsanli volcanites and Emet Formation) overlie the Sahin Formation unconformably. The mineralization occurs mainly as veins and partly as disseminations and fillings of interstices in the rhyodacitic and rhyolitic tuffs of Tavsanli Volcanics. Common primary ore minerals are stibnite, realgar, galena, sphalerite, pyrite and arsenopyrite, and secondary minerals are orpiment, senarmontite and valentinite. Barite is the dominant gangue mineral, with a small amount of quartz, calcite and dolomite. Average As, Sb, Pb, Zn and Ba concentrations in the samples from the study area are 6.04%, 4938 ppm, 4589 ppm, 1.17% and 10.36 % respectively. Three significant groups appear in the cluster analysis of ore samples. First group consists of Pb-Ag and Zn-Cd. The second group consists of Sb-Tl-Hg and As. The last group is the Ba-Sr. There are three significant factors in the factor analysis. First factor reflects the formation of primary sulphide minerals, the second factor represents the formation of low temperature sulphide and sulphosalt minerals and the last factor depicts interstices-filling mineralization. Average homogenization temperature of the fluid inclusion in barites is 221 °C. Geological, petrographical and geochemical data suggest that the Gözeçukuru As-Sb deposit was formed under epithermal conditions.     

Geochemistry, Fluid Inclusions and Sulfur Isotopes of the Goshgarchay Cu-Au Deposit (Western Azerbaijan) in Lesser Caucasus: Implications for the Origins of Ore-forming Fluids

The Goshgarchay Cu-Au deposit is located in the central part of the northwest flank of the Murovdagh region in the Lesser Caucasus. The Goshgarchay Cu-Au deposit is associated with Middle Jurassic volcanic and Late Jurassic–Early Cretaceous high-K calc-alkaline intrusive rocks. The Cu-Au mineralization is commonly related to quartz-sericite-chlorite alteration dominantly composed of chalcopyrite, gold, sphalerite, pyrite, bornite, hematite, covellite, chalcocite, malachite, and azurite. The Goshgarchay copper-gold deposit, which is 600 m wide and approximately 1.2 km long, is seen as a fault-controlled and vein-, stockwork– and disseminated type deposit. The Goshgarchay Cu-Au deposit predominantly comprises Cu (max. 64500 ppm) and Au (max. 11.3 ppm), while it comprises relatively less amounts Zn (max. 437 ppm), Mo (max. 47.5 ppm), Pb (max. 134 ppm), and Ag (max. 21 ppm). The homogenization temperatures and salinities of fluid inclusions in quartz for stage I range from 380°C to 327°C, and 6.9 wt% to 2.6 wt% NaCl eq., respectively. Th and salinities in quartz for stage II range from 304°C to 253°C, and 7.6 wt% to 3.2 wt% NaCl eq., respectively. The calculated δ34Sh2s values (?1.5‰ to 5.5‰) of sulfides and especially the narrow range of δ34Sh2s values of chalcopyrite and bornite (between ?0.07‰ and +0.7‰) indicate that the source of the Goshgarchay Cu-Au mineralization is magmatic. Based on the mineralogical, geochemical, fluid inclusion, and sulfur isotopic data, the Goshgarchay Cu-Au deposit represents a late stage peripheral magmatic-hydrothermal mineralization probably underlain by a concealed porphyry deposit.