SORKHE-DIZAJ IRON OXIDE -- APATITE DEPOSIT, NORTHWEST IRAN: MINERALOGY, TEXTURE, STRUCTURE AND ALTERATION.

Sorkhe-Dizaj iron oxide - apatite deposit is located within the Cenozoic Tarom volcano- plutonic belt in southeast of Zanjan, northwest Iran. The oldest units at the Sorkhe-Dizaj area are of Eocene age including trachyte, trachyandesite and andesitic tuffs intruded by quartz-monzonite, monzonite and granite plutons of Upper Eocene-Oligocene. The syn- to post-orogenic island arc magmatism and the plutonic rocks show characteristics of I- type granites. Mineralization in the area is divided into three main zones (A, B and C) all of which are hosted by the intrusive rocks. These three zones are similar in terms of host rock, mineralogy, alteration, structure, texture and metal content. Mineralization within the volcanic rocks occurs as veins similar to those three zones, but is less abundant. The most important minerals at the Sorkhe-Dizaj deposit are low-Ti magnetite, apatite, chalcopyrite, bornite, pyrite and monazite. Minor to trace amounts of ilmenite, spinel (titanium magnetite), galena, and sphalerite are also present. The main types of alteration at the deposit are silicification, tourmalinization, K-feldspar metasomatism, actinolitization, argillic, sericitization and chlorite-epidotic. Sorkhe- Dizaj is similar in many aspects including tectonic setting, host rock, mineralogy, alteration, structure and texture to the Kiruna type Iron Oxide - Apatite (IOA) deposits classified as a subgroup of hydrothermal Iron Oxide Copper Gold (IOCG) deposits. [ABSTRACT FROM AUTHOR]