دردانه هنر ايران و قابليت هاي جهاني آن

Petrology and geochemistry of the intrusive bodies south of Bostan Abad

In a region northwest of Iran, (Bostan Abad, Eastern Azarbaijan) there are intrusive bodies with Eocene-Oligocence age, that have overall northwest- southeast trend. The rocks of these bodies fall within the range of medium to acidic, that have intruded the Eocene volcanic series and constituting contact metamorphic aureole of low grade Moreover, having the same features as ablite - epidote hornfels facies. These rocks compositionally belong to the calc-alkaline and based on computer-criteria, in the orogenic belt, follows the tectonical regime of the VAG. Considering changes in the abundance of minerals such as pyroxene, magnetite, amphibole, biotite, plagioclase and alkali feldspar in the intrusive rocks, hence, it is indicative of successive process of differentiation in intermediate magma, and utimately creating variation in lithology. The studies shows that water vapour pressure for the formation of igneous bodies has been 0.2-2 kbar- and with regards to conditions produced contact facies and textural characteristics ; it seems that magmas after formation and ascent reaches the epizonal level of the crust. In other words, these magmas have been emplaced in the subvolcanic conditions. The latter, more or less have undergone contaminations with crust, up to their emplacement. By considering trace elements, distribution patterns; the common character of VAG for the intrusive bodies, ultimately introduces the CAG Setting.