TECTONIC CONTROL ON THE DEVELOPMENT OF THE NEOGENE QUATERNARY CENTRAL ANATOLIAN VOLCANIC PROVINCE, TURKEY

The Neogene-Quaternary Central Anatolian Volcanic Province (CAVP) is elongated in a north-east south-west direction within pre-Oligocene basement in central Turkey. This study investigates the field evidence relating to the development of the CAVP. Two dominant fault systems are recognized in the area. The first consists of the major conjugate faults in the region, namely, the right-lateral Tuzgolu and left-lateral Ecemis fault zones, and other faults parallel to these zones. The faults in this system are mostly active and cut the CAVP almost at right angles. The second fault system trends in a N60-degrees-70-degrees-E direction, parallel to the volcanic axis and to the alignment of the major eruption centres. These faults, which are of the normal type, are mostly buried beneath the products of recent volcanic eruptions. The behaviour of the first system is explained with reference to the present north-south convergence that occurs in the eastern Mediterranean region. These faults, which might be reactivated palaeotectonic structures, are a response to a present day compressive stress direction of about N10-degrees-W. The second fault system, in contrast, is the product of a short-term tensional period that occurred during the Mid-Late Miocene to Pliocene. This extension is almost at right angles to the convergence. As a result, the pre-Oligocene basement in the area was fractured in a N60-degrees-70-degrees-E direction and these fractures served as pathways for the extrusive rocks that formed the CAVP. The major eruption centres of the CAVP (i.e. the Hasandag, Keciboyduran and Melendiz stratovolcanoes) are located at the intersection of the major faults of these two fault systems.