The Bijvard epithermal gold-manganese prospect area, Northern Bardaskan, Khorasan Razavi: Evidence from geology, mineralization and geochemistry

Bijvard prospect area is located in the northern part of Central Iran zone, Sabzevar zone, about 40 km north of Bardaskan. The rock units exposed in the area include Cretaceous volcano-sedimentary rocks (andesite, basalt, graywacke and conglomerate) that syenogranite porphyry unit has intruded into them.  Mineralization has structural control, with N35E trending, and has altered the andesitic rock unit. Mineralization in this area has occurred in two parts: 1- Gold-bearing ores, that are mostly associated with silica and argillic alterations within gossan zone, which is surrounded by propylitic alteration 2- Manganese mineralization has occurred within gray wacke unit. Mineralogy is simple and primary minerals are pyrite, chalcopyrite, pyrolusite and braunite and secondary minerals include goethite, hematite, covellite, chalcocite, malachite and various Mn-bearing minerals. Quartz and clay minerals associated with minor calcite are the most important gangue minerals. The maximum value of gold is 1.4 ppm and the minimum value of gold is 0.01 ppm. In addition, the amount of copper is ranging between 88 ppm and 2.2%, arsenic is 21 to 100 ppm, and zinc is 162 to 495 ppm. Based on tectonic setting, host rock, structural control, type of alteration and the absence of high and low sulfide index minerals, Bijvard prospect area is probably an intermediate sulfidation epithermal type.