مروری بر زایش کانسارهای مس و ویژگی های ژئودینامیکی آنها در منطقه عباس آباد – استان سمنان

ABSTRACT

     Abbas-Abad copper deposits ore confined within a well-defined volcanic horizon of 
trachybasaltic affinity. This horizon is in turn lying in upper part of volcanic pile which lies in
middle of a thick volcano-sedimentary sequence of Eocene age. The ore –mineralization is
represented by an isometric chambered and or stockwork type. Primary ore-paragenesis  is a combination of chalcocite + digenite +covellite +bornite + magnetite + hematite which are assaciated with secondary malachite. The  chief gangue-minerals is quartz. Main alterations are chloritization and propylitization. Geochemical studies on host volcanic sequence  indicate a within-plate rift environment. Mineralizations  occur in a epicontinental zone of this tectonic environment.The above mentioned data indicate many similarities of this mineralization with the so-called Besshi-type  massive  sulphides, except the lack of pyrite and  presence of  high-temperature magnetite + hematite. Magnetite and hematite of this type in Abbas-Abad copper belt is interpreted by presence of high oxygen-fugacity in mineralizing fluids.

کلید واژه ها: ژئودینامیکی زمین شناسی اقتصادی واکتشاف سمنان