INVESTIGATIONS OF ALTERATION ZONES BASED ON FLUID INCLUSION MICROTHERMOMETRY AT SUNGUN PORPHYRY COPPER DEPOSIT, NW IRAN

Indexed In

Volume 140 / 2010

Authors:

Omid ASGHARI, Ardeshir HEZARKHANI

Keywords:

Fluid Inclusion, Porphyry copper deposit, Potassic alteration, Phyllic alteration, Microthermometry, Sungun, İran.

Abstract:

The Sungun porphyry copper deposit is located in East Azerbaijan, NW of Iran. The porphyries occur as stocks and dikes ranging in composition from quartz monzodiorite to quartz monzonite. Four types of hypogene alteration are developed; potassic, phyllic, propylitic and argillic. Three types of fluid inclusions are typically observed at Sungun; (1) vapor-rich, (2) liquid-rich and (3) multi-phase. Halite is the principal solid phase in the latter. The primary multiphase inclusions within the quartz crystals were chosen for micro-thermometric analyses and considered to calculate the geological pressure and hydrothermal fluid density. In potassic zone, the average of homogenization temperature is 413.6°C while in phyllic alteration, 375.9 °C. As expected in potassic alteration, the temperature of hydrothermal solutions is higher than that in phyllic zone. The salinity of the hydrothermal fluids has a high coherency with homogenization temperature, so the average of salinity in potassic samples is 46.3 (wt% NaCl) which is higher than phyllic samples. Based on the location of potassic alteration, as expected, the lithostatic pressure is much more than the phyllic one. Finally, the average density of hydrothermal fluids in the potassically altered samples is 1.124 (gr/cm³ ) which is higher than the ones in phyllic zone (1.083 gr/cm³ ).