introduction the study area is a small part of the urumieh-dokhtar structural zone in the markazi province, located in the northeastern part of the farmahin, north of arak (hajian, 1970). the volcanic rocks studied from the area include andesite, dacite, rhyodacite, ignimbrite and tuff of middle to late eocene age (middle lutetian to upper lutetian) (ameri et al., 2009). it seems that folding a...