Gülcan Bozkaya

Sulphur- and lead-isotope geochemistry of the Arapuçandere lead–zinc–copper deposit, Biga Peninsula, northwest Turkey

The Arapuçandere Pb–Zn–Cu ore body is a typical vein-type lead–zinc deposit of the Biga Peninsula, and is currently being mined for lead and zinc. In the study area, Permian–Triassic metamorphic rocks, Triassic metaclastic and metabasic rocks, Oligocene–Miocene granitoids, Miocene volcanic rocks, and Quaternary terrigenous sediments crop out. The ore deposits developed as Pb–Zn–Cu-bearing veins along faults in Triassic metasandstone and metadiabase. Microscopic studies reveal that the veins contain galena, sphalerite, chalcopyrite, pyrite, marcasite, covellite, and specular hematite as ore minerals, and quartz, calcite, and barite as gangue minerals. Analysed sulphur-isotope compositions (δ34SVCDT) of galena, sphalerite, and chalcopyrite range from − 5.9 to − 1.9‰ (average − 3.4‰), from − 5.5 to − 1.7‰ (average − 4.2 ‰), and from − 3.5 to − 0.9‰ (average − 2.6‰), respectively; that of H2S in the hydrothermal fluid was in the calculated range of − 5.8 to +0.1‰ (average − 2.5‰). These isotopic values suggest that magmatic sulphur dominates in sulphides, mixed with minor, isotopically light sulphur. Because no contemporaneous magmatic activity is associated with mineralization, it may be assumed that sulphur was leached from the surrounding Triassic units, mainly from metabasic, partly from metaclastic rocks. Lead-isotope studies indicate a model age of 114–63 Ma for the lead reservoir, in accord with possible sulphur-bearing local source rocks. Thus, the sulphur and lead deposited in the studied ore veins were probably leached from Triassic metabasic and metaclastic rocks some time during the Early Cretaceous to the Palaeocene.

Fluid-Inclusion and Stable-Isotope Characteristics of the Inler Yaylasi Lead-Zinc Deposits, Northern Turkey

The Eastern Black Sea Region of Turkey contains over 400 massive (Kuroko-type) and vein-type Cu-Pb-Zn deposits. The Inler Yaylasi lead-zinc deposits are typical examples of the vein type and have been economically mined for 15 years. Three ore veins were identified along E-W-trending fault zones, hosted by extensively altered, Upper Cretaceous volcano-sedimentary rocks. A Tertiary granitoid intrusion occurs near the area of mineralization. The ore veins contain sphalerite, galena, and minor amounts of pyrite, chalcopyrite, fahlore, chalcocite, and covellite as ore minerals, with quartz and calcite as gangue minerals. Fluid-inclusion studies show that the salt composition, salinity, and temperature of the hydrothermal fluids changed during various mineralization episodes. The temperature and salinity of the fluid were high (average temperature of 312.9°C and average salinity of 7.0% NaCl equiv.), and the fluid contained CaCl2, MgCl2, and NaCl during an early episode of mineralization characterized by quartz crystallization. During the sulfide crystallization, temperature and salinity were lower (average temperature of 272.0°C and average salinity of 4.0% NaCl equiv.), and the salts were mainly MgCl2, NaCl, and FeCl2. During subsequent mineralization episodes, temperature and salinity were still lower (average temperature 138.5 °C and average salinity 2.6% NaCl equiv.), and the salt content was dominated by NaCl, Na2CO3, NaHCO3, Na2SO4, and KCl. Oxygen- and hydrogen-isotope results (δ18O; +4.2 to +6.7 ‰ VSMOW and δ D; -83.0 to -59.0 ‰ VSMOW) suggest that magmatic water dominated the ore fluid. It is possible, however, that small amounts of meteoric water and/or formation water of meteoric origin were also involved. This isotopic composition may also be the result of interaction of meteoric water with magmatic rocks, as has been suggested for other deposits in the eastern Black Sea region. The decrease in temperature and salinity of the fluid and the increase in σ18O values of the water from 1725 to 1803 m levels also supports the hypothesis that these deposits formed where upwelling hot fluids met cold surfical fluids.

METAMORPHIC-HOSTED PYROPHYLLITE AND DICKITE OCCURRENCES FROM THE HYDROUS Al-SILICATE DEPOSITS OF THE MALATYA-PÜTÜRGE REGION, CENTRAL EASTERN ANATOLIA, TURKEY

Hydrous Al-silicate deposits are found to the south of Pütürge in Malatya city, Turkey. The surrounding rocks consist of mylonitic granitic gneiss overlain by muscovite gneiss with kyanite-bearing metabasic schist lenses on top which are cut by silica veins containing prismatic tourmaline and speculante. Pyrophyllite is found within kyanite gneisses overlying the granitic gneisses. Fibrous, platy pyrophyllite is developed along the edges and cleavage planes of kyanite, whereas platy bunches of dickite occur as replacements of the relict kyanites as well as crack- and pore-fillings. Rocks forming the hydrous Al-silicate deposit contain 2M1 pyrophyllite, alunite, topaz, paragonite, dravite, dumortierite, chlorite and epidote as early hypogene minerals, and 2M1 dickite, diaspore, gibbsite, speculante, goethite and crandallite/goyazite as late hypogene minerals. On the basis of fluid inclusion and stable isotope data, it is estimated alterations to pyrophyllite and kaolinite occurred at temperatures are of 150 and 100°C, respectively, the minerals being formed by meteoric waters interacting with metamorphic rocks. Trace and REE variations are highly distinctive in terms of enrichment of most trace elements in pyrophyllite, whereas REEs are clearly abundant in dickite, indicating different conditions during formation such as early and late hypogene processes. The pyrophyllitic alteration took place in the late Cretaceous (69–71 Ma), whereas kaolinization occurred later.

Fluid processes in the Tesbihdere base-metal-Au deposit: Implications for epithermal mineralization in the Biga Peninsula, NW Turkey

Tesbihdere is one of a number of spatially close epithermal Cu-Pb-Zn-Ag-Au deposits hosted by andesites and rhyolites, typical of deposits in the Biga peninsula. Microthermometry of fluid inclusions shows a wide range of temperatures, ∼360–170°C, and salinities, ∼10-0.5 wt.% NaCl, in the different deposits studied. Dilution of a moderately saline magmatic? fluid with meteoric water occurred at constant temperature indicating, the temperature of both fluids was controlled by the geological environment. Boiling was not a major factor, but did occur in very minor amounts. The large range of temperatures within individual samples can only reasonably be explained by variations from near lithostatic to hydrostatic pressure during vein and fracture opening. That this pressure decrease did not produce extensive boiling suggests that vein opening was gradual rather than aggressive, allowing the pressure and temperature decrease to follow a path close to the L-V boiling curve. P-T reconstruction places emplacement of these ore veins at between 300–500 m beneath the surface. Similarities of LA-ICPMS of fluid inclusions from Tesbihdere, Azitepe and Basmakci, supports the conclusion that they were part of the same contemporaneous mineralizing system. The fluids are dominated by Na, with the concentrations of K>Ca>Mg combined equivalent to the concentration of Na. The range of K/Na ratios is not consistent with the fluid inclusion temperatures as the calculated temperatures are significantly higher indicating the fluids were not close to equilibrium with the enclosing rocks. Elevated K concentrations are consistent with acid-sulphate waters in shallow epithermal systems. Ore metals Cu, Zn and Pb are present in significant concentrations ∼500, 300 and 200 ppm respectively and the low Fe/Mn ratios are indicative of a relatively oxidising fluid. The negative δ34S values of sulphides are consistent with boiling and oxidising redox conditions.

Fluid Inclusion and Stable Isotope Characteristics of the Arapuçandere Pb-Zn-Cu Deposits, Northwest Turkey

The Arapuçandere Pb-Zn-Cu ores are typical examples of vein-type lead-zinc deposits in the Biga Peninsula. Permian—Triassic metamorphic, Triassic metaclastic and metabasic rocks, Oligocene—Miocene granitoids, Miocene volcanic rocks, and Quaternary terrestrial sediments crop out in the study area. The veins occupy fault zones in Triassic metasandstone (meta-arkose and subarkose) and metadiabase, and contain galena, sphalerite, chalcopyrite, pyrite, marcasite, covellite and specular hematite as ore minerals, with quartz, calcite, and barite as gangue minerals. Based on macro- and micro-petrographic investigations, sulfide minerals formed in the earliest stage of mineralization, and were followed by quartz and calcite crystallization. Fluid inclusion studies showed that salinity (avg. 18.3%) was low, but that temperature was relatively high (avg. 301.4°C) during stages of sulfide precipitation. In contrast, the salinity (avg. 27.1% NaCl equiv.) increased and the temperature (avg. 240.2°C) decreased during crystallization of the quartz. Finally, the salinity and temperature of the fluid gradually declined through the later episode of mineralization when the primary and secondary inclusions in calcite formed. Isotopic compositions of the aqueous fluid (δ18O = -7.5 to -1.7%, and δD = -90 to -55%) indicate the presence of meteoric water modified slightly by fluid-rock interaction. A geologic and genetic relation between ore veins and Oligo-Miocene granitoids and Miocene volcanic rocks appears to be lacking. The ore and host-rock relations suggest only a post-Triassic age for the mineralization. Pb-isotope model ages suggest a pre-Eocene age for the mineralization, which predated Oligo-Miocene granitoid emplacement and Miocene volcanic activity. We conclude that the Pb-Zn-Cu veins in the study area formed by deeply circulating meteoric water. The metals and sulfur were leached from the surrounding pre-Eocene units and deposited along fault zones.

Epithermal Base-metal-Au Deposits, NW Turkey: P-T-Composition of the Ore Fluids.

In recent years the Turkish mining sector has increased dramatically with a particular emphasis on Au and Ag, but also Pb, Zn and Cu. The deposits are located in primarily along the north of the country, close the Black Sea and in western Anatolia, with the Biga Peninsula. The Biga Peninsula contains diverse styles of mineralization, but the most importants are the epithermal Au-Ag deposits, porphyry Au-Cu-Mo deposits and epithermal Pb-Zn-CuAu such as Koru (0.5 Mt at 8% Pb, 2% Zn, 300 g/t Ag),Tesbihdere (2.778 Mt at 5.76 g/t Au), Arapuçandere (4.0 Mt at 16.4% Pb, 12.1% Zn, 2.23% Cu, Au average 4 g/tonne and Ag average 260 g/tonnne), Tepeoba (4.86 Mt at 0.32 % Cu, 0.046 % Mo), Kisladag (153.330 Mt at 1.12 g/t Au), Efemcukuru (4.087 Mt, 11.01 g/t Au), Ovacik (4.19 Mt, 7.6 g/t Au), Madendag (8 Mt at 1.25 g/t Au) (MTA, 1993a,b). Here we examined samples from Koru and Tesbihdere which hosted by Tertiary (Oligocene) volcanic and volcano-clastic rocks (28.3± 1.30.6 Ma ; Baysal, 2008) and Arapucandere is hosted by Permo-Triassic clastics. The paragenesis for mineralizations contains galena, sphalerite, chalcopyrite, pyrite, marcasite, covellite, bornite, fahlore and specular hematite as ore minerals, with quartz, calcite, and barite as gangue minerals (Bozkaya, et.al, 2008, Bozkaya, 2009, Bozkaya, 2011)

Fluid inclusion and LA-ICP-MS data on mineralising fluids of the Bizmisen Iron Deposit (Erzincan, Central Anatolia), Turkey

Current European manufacturing relies heavily on imports from China for unprocessed rare earth elements (REEs) and rare earth oxides (REOs). It has been suggested that the EU holds viable reserves of REEs that, with adequate research, could satisfy 10% of EU demand, by the recycling of mine waste from bauxite production (red muds) alone (Deady 2014). Focus has been turned to the potential for similar South China type laterite deposits being exploited in the EU, but limited exploration and understanding of EU laterite formations currently makes them unattractive to investment (Humphries 2013). Following early work by Bernard-Griffiths (BernardGriffiths 1996) into the REE content of the Cretaceous Serra deMonchiqueNepheline-Syenite intrusion, this project examines the clay mineralogy and geochemistry of a selection of pedogenic profiles, logging their variations in mineralogy, bulk chemistry and specific REE content and comparing them to currently producing regions in Southern China. Investigation is under way using a five stage sequential leach-ICP-MS method to identify REE hosting minerals and mineralogical hosting phases, supported byXRDanalysis ofmineralogy and clay structures. Initial results indicate similarities in clay hosted REE distributions through laterite profiles to other researched formations in Madagascar (Berger 2014) and China (Zhou 2013), where specific organic rich (acidic) soils and biogenic profiles of tropical (rainforest) environments were presented as a key factor for REE mobilisation during pedogenesis. Serra de Monchique has a unique climate, with similar seasonal rainfall and cycling, but is not a rainforest, nor in a tropical region. It is therefore hypothesised that classic REE distribution models may also be applied to non-classic environments for this deposit type, supporting the hypothesis of Herrington (Herrington 2007) that China-type REE hosting ionadsorption clay profiles could exist across Europe in novel and previously unresearched environments.