Petrology of the metabasites of Dezg ophiolite melange complex, southeast of Qayen, east of Iran

Abstract

ABSTRACT The study area is located southeast of Qayen and in the northern part of the Sistan suture zone in the east of Iran and it is in real an ophiolitic complex with an approximate complete sequence and with a special metamorphic zone including metabasite rocks such as greenschist, epidote amphibolite, amphibolite and granulite in its eastern part. The metabasite rocks associated with ophiolite, have been affected by low to high-grade dynamo thermal regional metamorphism that has outcropped as a special metamorphic zone in the eastern part of ophiolite. On the base of geochemical diagrams most of these metamorphic rocks are a result of dynamothrmal regional metamorphism of primary pillow basaltic lavas and magmatic series of metabasite protoliths, which is tholeiitic. This composition is showing their relationship with MORB origin magma. The thermobarometric investigation done on these rocks show that these metamorphic rocks have been affected by metamorphism in maximum pressure of 3.9 – 5.3 Kbar and maximum temperature of 725±25 degrees of centigrade and in most extensive metamorphic position, changing of metamorphic pressure has been an important effect in paragenesis changes.