Petrology of the Oligocene volcanic rocks in the southZenogan area (Lut Block)

The studied area comprise Oligocence volcanic rocks which are including andesite, trachy andesite, trachydacite, dacite and rhyolite. Petrography studies indicate that they show phyric texture with abandance amphibole. It seems that they have registered the evidence of magma mixing and mingling probably produced from aqueous magma chamber. The geochemical diagrams display calc alkaline trend probably related to postcollision volcanism. Field observation revealed that most of Oligocene volcanism occured in aqueous to sub-area environments spider-diagrams display enrichment of LILE in relative to HREE, with depletion of HFSE, probably indicating of subduction signatures. It seems that partial melting of Sub Continental Lithospheric Mantle (SCLM) which has been previously enriched by subduction components were responsibly for the Oligocene volcanism in south Znogan area.