A study of different zoning types in clinopyroxenes of sodic and potassic alkaline volcanic rocks from North Lahrud, NW Iran

Clinopyroxene phenocrysts and microphenocrysts in potassic and sodic Eosen alkaline volcanic rocks from the northern Lahrud (NW Iran) record various stages in the crystallization and evolution history of the alkaline melt as well as its origin. The rock series hosting the clinopyroxene phenocrysts is phonolitic tephrite and tephritic phonolite composition. Theses rocks generally show porphyritic texture and have a variable phenocryst-rich nature (25–50%), with phenocryst assemblages characterized by Cpx ± An ± Pl. The studied clinopyroxenes have relatively high Mg-numbers (0.66-0.90), variable Al2O3 (3.77-7.31 wt%), low TiO2 (