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Öğe Geological, mineralogical and fluid inclusion characteristics of auriferous quartz veins at Guneykoy (Usak, Esme), Western Turkey(E Schweizerbartsche Verlagsbuchhandlung, 2018) Kahya, Asuman; Kanaat, ÖznurAuriferous quartz veins of Guneykoy (Usak, Esme) are hosted in Precambrian greenschist facies granitic gneisses of the Menderes Massif, West Anatolia. The auriferous quartz veins occur as fissure fillings either discordant or parallel to the foliation of the gneiss. The ore mineralogy includes arsenoyprite, pyrite, ilmenite, hematite and rutile as well as trace amounts of limonite, chalcopyrite and covellite. Arsenopyrite is a main ore mineral and often transformed into scorodite along crystal boundaries and fractures. Pyrite occurs within fractures of arsenopyrite and /or between the arsenoyprite crystals. Some pyrite is transformed into marcasite. The grain size of Au is 30-100 mu m, it occurs as single crystal or as aggregates in arsenopyrite. The Au content of the ore sample lies between 7.3 and 10 ppm; Ag varies between 0.9 and 20 ppm; Ni between 20 and 156 ppm; Cu between 9.0 and 14.1 ppm; Pb between 16.4 and 364 ppm and Zn between 2 and 5 ppm. The delta S-34 values of scorodite vary from -3.7 to 10.6 parts per thousand CDT and these values indicate that sulfur in the hydrothermal solution was not mainly derived from a magmatic source or through dissolution and leaching of pre-existing sulfide bearing igneous sources. Fluid inclusion studies on quartz yield homogenization temperatures of the fluids between 270 and 440 degrees C and salinities between 3.4 and 16.6 wt.parts per thousand NaCl equivalent. The low NaCl values may indicate mixing of low salinity meteoric fluids and magmatic fluids. As a result, the Guneykoy gold deposit originated from a metamorphic fluid system related to the Pan-African orogeny characterized by low salinity and enrichment of CO2. Based on geological features, mineral paragenesis and fluid-inclusion studies, the Guneykoy gold mineralization can be classified as orogenic gold-type deposits.Öğe Geology and mineralogy of carbonate-hosted Au-Ag±Pb-Zn deposits in the Maden village (Ulukisla), Niğde, se Turkey(International Multidisciplinary Scientific Geoconference, 2014) Kahya, Asuman; Kuşcu, Ercan; Cengiz, Oya; Yıldız, MustafaThe study area is located in the Bolkar mountains which are part of the Tauride platform, includes lower Paleozoic to Upper Cretaceous recrystallized limestone, dolomite, marble, and calc-schist. The deposits hosted in the Upper Triassic Bolkar Mountains carbonate rock and structurally controlled by E-W/36-45 S faulted, younger fault and related karstification. Primary sulfide ores are observed between the contact of quartz porphyry and carbonate rocks and in the fault breccia. After the primary mineralization occured in the contact between carbonate and quartz porphyry, second mineralization which formed of the oxidation of the primary sufide minerals and settlement it in the fracture and karst cavity. Ore minerals which in occur as fractures and karst fills, observed two main groups as sulfide and oxide/hydroxide. Sulfide minerals are galena, sphalerite, tetrahedrite, pyrite, arsenopyrite, boulanjerit, pyrrhotite, linneit and millerite. Oxide and hydroxide minerals are pyrolusite, psilomelane, manganite, chalcophanite, cerusite, anglesite, covellite, goethite, lepidokrokit, hemimorphite, perovskite, mimetit and korkit, rutile, magnetite, chromite. These paragenesis indicate that origin of the deposit develeped in the oxidation-cementation zone as a result of supergene enrichment. © SGEM2014. All rights reserved.Öğe S and Pb Isotope Geochemistry of the carbonate-hosted Au-Ag-Zn ± Pb deposits in the Maden Village (Ulukışla-Niğde), Central Taurides, South Turkey(E. Schweizerbart'sche Verlagsbuchhandlung, 2019) Kahya, Asuman; Kuşçu, Ercan; Yıldız, MustafaThe Maden Village carbonate-hosted Au-Ag-Zn ± Pb deposits in the Bolkar Mountains that are part of the Tau- ride platform, south of Turkey, contain significant none- sulfide ore and relicts of sulfide bodies. The deposits hosted in the Upper Triassic carbonate rocks of the Bolkar Mountains are controlled by E-W trending and 36-45° S-dipping faults, and karst- related structures. The deposits is a formed by supergene oxidation of primary sulfide minerals during complex interaction of tectonic uplift, karst development, changes in the level of the water table and weathering. Zn (Pb) carbonates, Zn-hydrosilicates and associated hydrated phases directly replace the primary ore bodies or fill cavities and pods along fractures within marble are genetically related to the uplift of Tauride block during Oligo-Miocene period. The supergene deposits recharacterized by open space and karst-filling feature. Direct replacement of primary sulphide is accompanied by distal precipitation of non-sulphide minerals in cavities. The mineralogy of non-sulfide minerals consist of cerussite, anglesite, smithsonite, limonite, pyrolusite, psilomelane, manganite, chalcophanite, beudantite, goethite, lepidocrocite, hemimorphite, mimetite, corkite and native gold. In the sulfide ore bodies of Maden Village deposits, the ? 34 S isotope values of galena vary from 3.0 to 5.8 ‰ V-CDT and imply that sulphur originated from a mixture of different sources (me- teoric, magmatic hydrothermal fluids). The lead isotope data for galena showed mean values of 18.991, 15.701, and 39.056 for 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb, respectively. The distribution of the lead isotope ratios shows a cluster in the deposit that is related to the upper crust. The fluid inclusions in sphalerite show that the homogenization temperatures val- ues of up to 290 °C, at a salinity of 6.2 wt.% NaCl equiv. In this study, we propose that ore forming fluids were originally derived magmatic hydrothermal fluids, and that they were mixed with low salinity meteoric water. The re-modified sulfide Pb-Zn mineralization resembles a 'residual and karst fill' sub type of nonsulphide zinc deposits. Au and Ag bearing miner- als in the supergene environment consist of native gold hosted in limonite and Ag-bearing cerussite and anglesite.Öğe Source of the mineralizing fluids in ultramafic related magnesite in the Eskişehir area, northwest Turkey, along the İzmir–Ankara Suture: A stable isotope study(TÜBİTAK, 2014) Kahya, Asuman; Kuşcu, MustafaThe Eskişehir magnesite deposits (Süleymaniye, Margı, and Tutluca) are located in the western part of the İzmir–Ankara Suture Zone, northwestern Turkey. These vein and stockwork type magnesite deposits, which occur along major and minor fault systems, are hosted by Alpine-type ultramafic rocks. The purpose of this study was to understand the origin of the hydrothermal waters responsible and the source of carbon dioxide, and to compare these deposits with similar magnesite occurrences in Turkey and elsewhere. Petrographic and XRD analyses indicate that magnesite was the major carbonate mineral formed. Deposits are predominantly micritic and locally microsparitic, but some also contain secondary calcite and dolomite. The ?13C (V-PDB) values of the Süleymaniye magnesites (–2.7‰ to –7.7‰), the Margı magnesites (–7.6‰ to –11.2‰), and the Tutluca magnesites (–8.7‰ to –10.4‰) indicate that sources of carbon may include atmospheric carbon, dissolved inorganic carbon, freshwater carbonate, and mantle derived CO2 . The ?18O (SMOW) compositions of the magnesite range from 27.4‰ to 30.8‰ and show that the oxygen was derived from marine limestone and metamorphic rocks. The Süleymaniye magnesites have heavier carbon isotopic values than the others because of the greater contribution of mantle sourced CO2 , while oxygen isotopic values were similar to those of other altered ultramafic related magnesites in Europe (Former Yugoslavia, Greece). The Margı and the Tutluca magnesite deposits have carbon and oxygen isotopic values similar to those of other ultramafic-related magnesite deposits. Based on isotopic data, we argue that the magnesite deposits in the Eskişehir area formed in a near surface environment at low pressure and temperature. The estimated temperature, using average ?18O values, suggests that magnesite was precipitated from water at 37 °C.
