Geological, mineralogical, petrographical and geochemical properties of the Goshgarchay (West Azerbaijan) porphyry copper deposit

Copper is an indispensable natural resource for humanity in different application areas from ancient times to the present. In this master thesis, it is aimed to investigate the geological, mineralogical, petrographical and geochemical properties of the Goshgarchay porphyry copper deposit, which is considered one of the most important natural sources of the country in the west of the Republic of Azerbaijan. The main subject of the study, the Goshgardag (West Azerbaijan), porphyry copper deposit was discovered in the 19th century and was the subject of more detailed studies by the former Soviet researchers in the 20th century. Since the end of the 20th century, the discovery of promising porphyry copper deposits in the Goshgardag and Goshgarchay ore fields of the Azerbaijan part of the Lesser Caucasus and especially the Murovdag mineralization area has led to more interest in the region. The presence of plutonic complexes with different compositions, hydrothermal alteration zones, metasomatites and faults originating from the mineralization in and around the Goşgardağ mineralization area, the observational geological features of the mineral deposits and occurrences in the region, the presence of geochemical and geophysical anomalies attract the attention of researchers to examine the region in detail. In this study, it is aimed to determine the most suitable method for the operation of the deposit by investigating the geological, structural, mineralogical-petrographical and geochemical properties of the Goşgarçay porphyry copper deposit, revealing the distribution, geometry, quantity, and reserve of the ore. To this aim, In the Goşgarçay porphyry copper deposit, ores and bedrocks were identified, the structural features of the mineralization were investigated, the distribution of ore minerals and some indicators and trace elements in metasomatites and host rocks were tried to be determined, and the boundaries of high-grade mineralization areas were determined. In the Goşgarçay mineralization area, mainly andesite-basalt complexes, basic and intermediate volcanics, proclastics and sedimentary rocks crop out. The main ore minerals found in the Goşgarçay porphyry-copper deposit are pyrite, chalcopyrite, sphalerite, and magnetite. In the mineralization, gangue minerals, quartz, plagioclase, alkali feldspar, clay minerals, zeolites, dolomite, calcite, amphibole, hematite, and micas were detected in the wall rocks. The average amount of the main components in the samples taken from the ores and bedrocks in the Goşgarçay porphyry Cu deposit is 56.7% SiO2, 8.16% Al2O3, 6.37% Fe2O3, 2.75% CaO, 2.14% MgO, 1.61% Na2O and 1.09% K2O. There is an average of 19094.6 ppm Cu in the Goşgarçay porphyry copper deposit and the variation interval is 34.2 - 64500 ppm. Cu in the deposit is bound to chalcopyrite, bornite, and copper-containing sulfates determined in mineralogical and petrographical analyzes. While the Zn ratio in the deposit varies between 12.2 and 437 ppm, Au reaching 11.3 ppm, As reaching 475 ppm, V reaching 234 ppm, Ba reaching 373 ppm are significant. Pyrite, chalcopyrite, sphalerite and galenite is the main minerals of Pb, Zn, Fe and Cu. According to the sulfur isotope analyzes, δ34S values vary between ‰ -0.5 and ‰ 6.5 in samples separated at nearly 100% purity from the Goşgarçay porphyry-copper deposit. The δ34S values of chalcopyrites vary between ‰ -0.2 - ‰0.2, the δ34S values of pyrites vary between -0.5 - ‰6.5, while the δ34S value of bornite is ‰0.1 According to the fluid inclusion study performed on 4 quartz samples taken from the deposit, primary and secondary inclusions were determined, and primary inclusions were formed during the formation of the mineral, and secondary inclusions were formed in microfractures after the formation of the mineral. Primary inclusions are two-phase inclusions containing liquid and gas (SG-type) at room temperature, and the liquid phase is larger and predominant in volume than the gas phase. The measured SG-type primary inclusions are 5-30 mμ in size, commonly 15 microns in size. In the measurements made in SG-type inclusions, Tm-ice values vary between -1.5 and -4.8 °C, homogenization temperatures (Th, °C) vary between 253.3 °C and 380 °C, and salinities corresponding to Tm-ice are 2%, It varies between 6 and 7.6% NaCl. According to the geological investigations carried out in the Goşgarçay porphyry copper deposit, the lithological properties of the ores and bedrocks, mineralogical-petrographical and geochemical analyzes, and sulfur isotope and fluid inclusion data, the mineralization in the mineralization region was formed in hypothermal conditions on the border of the Late Cretaceous aged basic-intermediate plutonic rocks that cut the Dogger aged volcano-sedimentary rocks. Keywords: Azerbaijan, Alteration, Porphyry copper, Gold, hypothermal, Goshgarcay