ALTERATION ZONES ASSOCIATED WITH EOCENE MAGMATISM IN THE OLUR (ERZURUM) AREA, EASTERN PONTIDES AND THEIR SIGNIFICANCE
Authors: Güzide ÖNAL, Mustafa AKYILDIZ, İsmet CENGİZ, Mehmet ASLAN, Serkan ÖZKÜMÜŞ
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The Alpine Orogenic Belt with numerous porphyry Cu-Mo-Au mineralizations, starts from Eastern Europe continues through Turkey and the Caucasus and extends into Iran and Afghanistan. The study area of the Eastern Pontides is in this orogenic belt. Using fi eld and laboratory studies an attempt has been made to establish the origin of Yeşilbağlar, Kaban and Köprübaşı alteration zones in the Olur area (Erzurum). In the study area Early Eocene Coşkunlar volcanics and sub volcanic rocks have contact with the Oltu çayı volcanics of Early-Middle Jurassic. Alteration in the study area effects these Oltuçayı and Kaban volcanics. In the study area mineralizations are present in the alteration zones. Disseminated, stockwork, vein/veinlet and fi ssure type mineralizations are present in the Coşkunlar dacite. Paragenesis in the alteration zones are pyrite, chalcopyrite, sphalerite, galena, pyrrohotite, quartz, calcite and barite. FT-IR and XRD studies showed the presence of clay, sulphate, sulphur, carbonate, silicate and oxide minerals in the alteration zones. Field and petrographical studies showed that alteration types in the Yeşilbağlar, Kaban and Köprübaşı areas are, advanced argillic-argillic, pyropylitic and sericitic. They are similar to the alterations present in the upper part of the mineralizations in the porphyry systems of the Alpine Orogenic Belt. In the Eastern Pontides starting in Early Jurassic, continuation of subductions resulted in closure of the İzmir-Ankara- Erzincan ocean and in Early Eocene the Taurid platform collided with the Eurasian active continental margin. Data from the study area indicate the presence of alteration zones in the upper part of the buried porphyry system and the possibility of mineralized parts in the deeper parts of the system.