بررسی دگرسانی های حاشیه رودخانه قزل اوزن در شمال شرق زنجان

The Study area is located in northeast of Zandjan and is a part of Hashjin-Tarom poly-metal zone. The results of geochemical and heavy mineral explorations in this region led to the discovery of significant anomalies of elements such as Au, Ag, Sb, Bi, Sn, W, Mo, Cu and Pb in zones related to hydrothermal alterations.  Two types of alterations are present in this area, ۱)  acid–sulfate which is intimately associated with shear zones in south of Qezel–Ozan  river and ۲) neutral-pH alterations developed along the margin of Qezel–Ozan river. Acid-sulfate alterations are divided into two types, ۱) hypogene (silisic, alunitic, advanced argillic, phillic and propylitic zones) and ۲) supergene (principally oxidized and leached zone containing jarosite, alunite, kaolinite, limonite, geothite, native sulfur and gypsum). Sulfuric acid has been the main altering agent which was produced by oxidation of H_۲S relealsed from boiling fluids at depth or oxidation of pyrite by supergene oxidizing solutions. Neutral-pH alterations include argillic, calc-silicate (prehnite, epidote,  pyrite, calcite, fluorite, albite, K-feldspar, quartz, zeolite) and  zeolitic zones, and are thought to have formed by Cl^¯-bearing fluids. Based upon field evidence and laboratory investigations, these altertions occurred during late-Oligocene to middle-Miocene.

کلید واژه ها: زنجان