Determinatin of the mineralization potential of quartz veins in eosen volcanics of the Iznik-Mecidiye (Bursa) region

Armutlu Peninsula is located in Armutlu-Almacık Zone. The Armutlu Peninsula, which is limited to the İstanbul-Zonguldak zone in the north, the Sakarya continent in the south and the branches of the North Anatolian Fault are are divided into three as the north, middle, and south zones. Today, these three zones are limited by the North Anatolian Fault. The North Zone consists of the Armutlu metamorphic assemblage and overlying the Late Cretaceous-Tertiary cover units. The middle zone is predominantly dominated by 2 tectonic units. These units are the İznik Metamorphic Community and the Gevye Metaophiolite. The northern and middle zones are overlain by Late Mesozoic-Late Tertiary units. The southern zone includes the Sakarya continent units. The study area (İznik-Mecidiye) is located to the south east of the Marmara Region, to the north-east of the Iznik Lake. Iznik district is connected to Bursa province and is 85 km away. On the basis of the study area, Permian-Triassic metamorphic rocks are present. Upper Cretaceous sedimentary rocks are unconformably overlain by this basement. The unit, which is mainly composed of mudstone, shale and sandstones, forms around Kızılağaç Hill and Pilav Hill. The Eocene volcanics are unconformably overlain by these units. The volcanics which are exposed in large areas around Mecidiye are cut by slope-slip faults. The Eocene volcanics (Kızderbent volcanics) in the study area can be seen in three zones as north, middle and south. This work was carried out by field, laboratory and office work. A geological map of an area of approximately 30 km2 remaining on the G23-d3 map of Bursa with a scale of 1/25000 is made. A total of 50 samples are collected at each location where observations were made, representing lithology, for mineralogical, petrographic and chemical analyzes. Laboratory studies include chemical analyzes and mineralogicalpetrographical surveys. Office work indicates interpretation of all data obtained, collection under specified headings, forming of graphs and tables, and thus passing all data and writing stage. The mineralogical and textural characteristics of the Eocene volcanic rocks were determined. As a result of polarizing microscopy, rocks were classified according to their modal ratios and phenocrystalline and dough contents are determined. The volcanics in the Mecidiye region are composed of rocks ranging from basalt to dasite. This units are divided into two main groups according to their mineralogical features (according to their formulas and they contain mafic minerals with water or not); as anhydrous lava series and hydrous lava series.The lava from hydrous series are composed of andesitic and trachy-andesitic rocks which contain clinoproxene and xx amphibole as mafic minerals. Anhydrous series are represented by basaltic and basaltic andesitic rocks. This rocks are made by plagioclase + clinopyroxene + opaque minerals. Along the fault and joint planes within the Eocene volcanics, quartz veins observed. Opaque minerals and alterations were found along these quartz veins. Kızderbent volcanics affected by hydrothermal solutions include sulphide such as pyrite and chalcopyrite; minerals with oxide and hydroxid such as magnetite, hematite and goethite were determined. In order to determine the geochemical properties of 60 samples taken from the study area, major, trace and rare element analyzes are examined in the geochemistry laboratory (ITU-JAL) in Geochemistry Department of Minin Faculty of Geological Engineering Department. Diagrams were created according to the results of the chemical analysis of the selected 40 samples and the properties of the samples were determined. Detailed data are obtained by using ICP-MS and XRF devices. The geochemical results show that the rocks are in a wide range ranging from basalt to dasite and they are calcalkaline and high potassium calc-alkaline. While an enrichment is observed in spider diagrams normalized according to N-MORB and primary mantle in terms of elements of wide ion radius (LIL) (Sr, Rb, K, Ba, Th), in terms of HFS (Ta, Nb, P) elements there is depletion and there is a parallelism to the normalized MORB line. Nb, Th, Ti, and P elements show a relatively negative anomaly while Pb shows positive anomaly. These data are characteristic for the subduction zone and post-collision lava. The negative Eu anomaly seen in the diagrams reflects the effects of a shell-based addition to the mafic magma, or it is a reduction caused by crystallization of plagioclases. The overall result obtained from all tectonic divergence diagrams reveals that the Eocene volcanics are the end products of the subduction. The Harker diagrams were used in order to compare / differentiate the magma series with SiO2, which is a simple but very useful method. Thanks to the trends obtained from these diagrams, it is possible to comment on issues such as cold crystallization, magma mixture and partial melting. The general characteristics observed in the Harker diagrams are as follows: Al2O3 MgO, CaO, TiO2 ve Fe2O3 show a tendency to decrease against increasing silica value. This negative trend shows that the main oxides are consumed in magma and enter the crystal structure. These trends observed in diagrams can be interpreted as the rocks coming from the same magma. The Au anomaly (0.109 ppm) and the presence of pyrite-chalcopyrite minerals in the zones where the rocks are widely silicified, indicate the hydrothermal alteration. Various alteration indices have been used to determine the mineralogical and chemical changes occurring in the rock as a result of hydrothermal alteration. The most common alteration in volcanics is sericitic alteration. Quartz veins are widely observed in discontinuity planes which is seen in NW-SE extending slope fault fault zone and north of Kel Hill. Pyrite and trace amounts of calcopyrite are observed along these veins. As a result of geochemical analysis studies performed in this region, W, Zn and Cu anomalies are seen with V anomaly. As a result of the laboratory and field studies, it is determined that the vein type hydrothermal mineralization is observed within the Eocene volcanics and the vein thickness is limited. Pyrite and rarely chalcopyrite are observed in the veins. The observation of quartz veins in volcanics in the region shows that the fracture systems are effective in mineralization.