Petrography and mineral chemistry of alteration zones in the Kahang porphyry Cu-Mo deposit (Northeast of Isfahan)


1 اصفهان- سه راه سیمین- کوچه جنب اداره مالیات- مجتمع شهاب- واحد 3- آیتی

2 Department of Geology, Faculty of Sciences, University of Isfahan, Isfahan, Iran

3 Department of Mining Engineering, Isfahan University of Technology, Isfahan, Iran


The study area is located in the Uromieh-Dokhtar volcanic belt and composed of andesite-basalt, andesite, dacite and quartz-monzonite as volcanic and subvolcanic. The occurrence of phyllic, argillic and propyllitic alterations point to the presense of hydrothermal fluids. The studied amphiboles have tschermakite and ferro-edenite composition. The compositional changes from core (Fe-Mg-Mn) to rim (calcic) refer to the variation of physico-chemical condition of magma in the last stage of crystallization. The biotites are assumed to be primary, their Fe/Fe+Mg ratio is over than 0.33% and they are iron enriched. The composition of the chlorites plotted in the repidolite field with Fe and Si in the range of 6.56% to 6.76% and 5.19% to 5.61% respectively. The low content of Al+Fe3+ in sphene, can be the result of high temperature of its formation. The potassium content of the Kahang jarosites is more than that of the sodium indicating the hydrothermal-magmatic condition of these phases formation.