Investigation of the geological, geochemical origin and gold potential of mineralizations and hydrothermal alterations in the ortakoy (Kumluca, Antalya) region

This is probably the first work on geochemical investigation in the Ortaköy village, located within the Gödene Zone, SW of the Antalya Complex. The Gödene Zone is about 15 – 20 Km north of Kumluca town in the Antalya Province. Four geological formations (Kirkdirek, Karadere, Çandır and Alakırçay) out of the six in the zone as well as some stream sediments were investigated in this research. Rock types of the four formations included serpentinites, micrite, cherts, sandstones, siltstones, mudstones, claystones, microconglomerates, basalt, spilites and spilitic basalts. Thirty-one samples of rocks and sediments were analyzed. The dominant minerals (analcime, augite, amphibole and plagioclase) in the volcanic rock and their textural relationship revealed variation in the depth of formation of the rock samples. They showed both intrusive and extrusive characteristics. A bimodal volcanism is thought to have occurred in the area. The mineralogy of the serpentinites reveal low grade metamorphism, as well as low grade chromite and magnesite ores were revealed. Platinum Group Minerals (PGM) and Au bearing minerals were undetected. However, precious metals (Au, Pt, Ag and Hg) were identified in very low concentrations compared to their ore grade concentration. The platinum were probably hosted by Ni-Co mineralization. The Au occurrences were probably associated to Cu and Ni in the ultramafic and mafic rocks, to sulphide in stream sediments, and to SiO2 in the claystone. The highest concentration of Pt (10.0 ppb) was occurred in the serpentinites while highest concentration of Au (50.6 ppb) were in siltstones. Averagely, concentrations of Pt were higher in serpentinites (7.25 ppb) compared to claystones (1.15 ppb), soil (1.14 ppb), siltstones (1.13 ppb) and basalts (0.93 ppb); concentration of Au were higher in siltstones (14.03 ppb), followed by soil (2.89 ppb), stream sediments (2.18 ppb), claystones (2.07 ppb), serpentinites (0.61 ppb) and basalts (0.36 ppb); concentration of Ag were higher in claystones (33.5 ppb) compared to serpentinites (18.88 ppb), soil (12.14 ppb), siltstones (10.5 ppb), stream sediments (7.5 ppb) and basalts (6.86 ppb); and concentrations of Hg were higher in soil (18.82 ppb), followed by claystones (18.5 ppb), stream sediments (10.63 ppb), siltstones (6.31 ppb), serpentinites (4.31 ppb) and basalts (6.86 ppb). Discriminant plot of Sr/Y to delineate mineralized from non-mineralized formations showed no possible mineralization. However, the primary and secondary halos were compared to data from other exploration results. This presence of Pt suggest a further investigation of the area be carried out, which should includes additional precious metals (Ru, Rh, Os and Pd). The north-eastern and southern portion of the study area showed relatively high concentrations of Pt and Au respectively, as identified using spatial distribution maps. The clr-biplot showed very low variability of the elements were explained. This may be attributed to the differences in the sampled media types analyzed together. Comprehensively, all the samples were separated into three main category. This signified three main parent source. Serpentinites were enriched with Mg, Ni, Cr, Co, Hf, Pt and Nb, the basalt and soil were enriched in Ti, Na, Al, Zr, Li, Ca, Zn and V, and other sedimentary media were enriched with Au, Pb, Cu, Ag, Ba, Mn, La and Ce and Y. The basalts were thought to be the main source material for the soil. An intermediate to felsic magmatic rock is thought to be the main source of the sediments. The parent magma of the basalts showed poor evolution with respect to silica, this further confirms a possible bimodal magmatic source or poor fractionation of magma. The serpentinites showed no evolution because they were trusted unto the continent by the compressional tectonic regime. Volcanic series association further showed the igneous rocks tholeiitic and calc-alkaline in character. This suggest a volcanic arc origin or a mixture of continental and ocean crust materials. The basalts varied in chemical content and showed some level of low-grade alteration considering Hf/Zr relationship. The sediments showed no variations nor any recycling. However, the Hf/Zr relationship indicated the sediments had experienced weathering. The depletion of Nb observed in the basalts may have been as a result of their low concentration or absence in the magma. Niobium, and the relatively high concentrations of Zr and Ti are thought to have resulted from crustal contamination. Multi-element normalization for concentrations of elements in the basalts and serpentinites were done with respect to the primitive mantle, average crust and chondrite concentration values. Enrichments of the elements to the primitive mantle and chondrites concentrations were obswerved, while there were depletion compared to the average crust. The enrichment of Rb, U, Pb, Sr and P may be attributed to crustal contamination, relating to continental-oceanic arc magmatism. Discriminant plot using the felsic, mafic and weathering parameters showed that the serpentinites, two basalt samples and most of the siltstone, claystones, soils and stream sediments samples experienced some degree of chemical weathering. Based on field observation, at least of two tectonic regimes are thought to have influenced the terrane of the area. The tectonic regime is thought to have deposited the volcanic rocks. The second regime is thought to have faulted the basalts, facilitated emplacement of the dykes, shattered some of the rocks, and metamorphosed some of the rocks in the area. Regional, hydrothermal and dynamic metamorphic activities were evident to have affected the area based on mineralogy and mélange.