Mineralogy and Ore genesis of Bayche - Bagh Five Elemen (Ag- Ni-Co-As-Bi) Vein Deposit (NW Zanjan, Iran)

The Bayche – Bagh mine area in the northern part of Takab based on lithostratigraphy point of view includes gneisses and amphibolites of Precambrian, which are unconformably overlain by volcanic – volcanoclastic and associated sedimentary rock units of Tertiary and Quaternary age. The volcanic rocks are divided into rhyolitic and andesitic groups in which the rholitic group provides the main host – rock of the deposit. Ore parageneses include copper, lead, zinc, nickel, cobalt and Bismuth mineral occurred in nine veins of main orders and few veinlets. The physico chemical conditions of ore – fluids governing the ore – mineralization, were controlled by fluid inclusion studies and the related obtained parameters are as follows:- Temperature of homogenization (TH) from 212Cº to 470Cº- Salinity (in NaCl-equivalent percent) about 25%-Trapping pressure from 50 to 800 bars The ore-generation processes based on the nature of magmatic host rocks, ore assemblages and thermometric data in the Bayche-Bagh deposit, similar to other hydrothermal five – element vein deposits, seem to be occurred in relation to ore recycling and fluid migrations. These fluids the metals of recycled the deep-seated basic and ultrabasic rocks of the old basement as also adjacent volcanoclastic hosts and deposited the ore minerals in the fault spaces in under suitable conditions.