seyed ahmad BABAZADEH - payamenoor university of birjand- iran.

Birjand region is located in east Iranian flysch trough or sistan suture zone and belongs to Cainiziic Alpide suture of sengor et al (1988). This region is one of the remnant basins in Sahlabad province (Babazadeh, 2003) thet located between two micricontinetal fragments (Lut and Afghan). These successions generally belong to the middle Alpine orogenic events started at the late cretaceous time (65 Ma) together with the compressinal phase (Laramid) and continued by the volcanism activities during the late paleogene and early Neogene (Elahpour, 2003). These activities are presumably associated with the final stages of subduction in eastern iran. the pyroclastic rocks covered the Paleocene - Eocene resedimented facies. Results show that the volcanic coomponents be related on orogenic mechanism and continental margine calcoalkaline lavas. Extraordinary distribution of pyroclastic components, considerable presence of amghibole phenocrysts, absence of linear relationship between Zr and TIO2 and extraordinary sufficiency of lithophyl elements with large ionic radiation, supported the results and reinforeced the idea of correlatior between Birjand area extrusive igneous rocks with active continenta margines calcalkalin lavas.

pyroclastic, andesite, calcoalkaline, birjand, iran