VEIN TYPE MINERALIZATION AND RELATED ALTERATIONS OF NARIGUN POLYMETALLIC DEPOSIT, EAST OF YAZD, CENTRAL IRAN

摘要

The Narigun area is located in Central Iran. Presence of Narigun granite as a source of mineralization and occurrence of faults systems in surrounding tuffs makes favorable condition to form polymetallic veins around the granitic pluton in brecciatcd zones. Major hydrothermal alterations around mineralized veins are: silicification, argillitization, carbonatization, and potassic alteration. The metallic mineral assemblage in the veins mainly consist of arsenides and sulpharsenides like nickeline and arsenopyrite, three generations of sulfides, including molybdenite, sphalerite, pyrite, and uranium mineralization as uraninitc. Hydrothermal fluids formed veins with high U, Ni, Co, Ag, and As content veins and caused related serialization and carbonatization in the wall rocks. Secondary boiling in hydrothermal fluids caused by decrease of pressure in tectonized zones led to precipitation of metals in the veins. The main characteristics of Narigun veins including mineral paragenesis, alteration, and regional tectonic control, show that it belongs to granite-related, poly-metallic vein type deposits.