بررسي پتروگرافي و كاني شناختي پهنه هاي دگرساني در آندزيت هاي معدن مس پورفيري سرچشمه (جنوب كرمان)

Studying of Petrography and Mineralogy of Alteration Zones in Andesites of Sar-Cheshmeh Porphyry Cupper Mine(Southwest of Kerman)

The Sar-cheshmeh porphyry Cu-Mo deposit is located in the south of Uromieh Dokhtar Volcanic belt(65 km southwest of Kerman City). The Eocene andesites are the predominant host rocks of the ore deposit. These rocks are characterized by gray color and porphyry texture. Plagioclase(oligoclase -andesine), hornblende, biotite(phlogopite), and minor quartz are the major minerals and Zircon and apatite are the magmatic accessory minerals of these rocks. The studied andesites have experienced hydrothermal alteration. Propylitic alreation is identified by crystallization of albite and replacement of plagioclase and K-feldspar by albite, and it is also characterized by epidote(pistashite), calcite, chlorite(clino chlore) and sulfide. Pervasive sericitization was the last hydrothermal stage leading to crystallization of sericite, quartz and sulphide. Hornblende is almost totally replaced by biotite and chlorite, and early biotite shows partial or total chloritization. Two generations of quartz, magmatic and hydrothermal are common. Furthermore, the widespread occurrence of opaque minerals(pyrite, chalcopyrite, chalcocite) in this zone is notable. Clay minerals(Illite, Kaolinite, Muscovite, Dickite) are the major mineral assemblage of argillic zone. Pyrite is the predominant disseminated sulfide in all alteration lithologies. Biotite from the propylitic and phyllic alteration zones possesses higher Al2O3, Si02, and FeO concentrations than magmatic one. This phenomenon is similar to that recorded for biotite of other porphyry Cu deposits Throughout the woeld. The mineral assemblages of the alteration zones along with different chemical composition of biotite, clearly point to the various physico - chemical condition governing the hydrothermal alteration processes.