Petrography and mineral chemistry of volcanic rocks south of Bardsir (Dahaj-Sarduieh, Iran): evidence for magma mixing

摘要

The Shirinak volcanic rocks are located in south-east Bardsir (Kerman Province).Geologically, the area is part of the Urumieh-Dokhtar volcanic belt, which is known as the Dahaj-Sarduieh belt in Kerman Province.The studied lavas are porphyritic with phenocrysts of plagioclase, clinopyroxene and olivine set in a microlithic and fine-grained matrix.On the basis of petrographic observations and electron microprobe analyses the plagioclases are labradorite-bytownite with sieve textures due to thermal and compositional magma mixing.On the other hand, the clinopyroxenes are augite and their physical and chemical conditions indicate formation at different depths in the ascending magma under oxygenated condition with H2O ranging up to 10 wt％.The Cpx thermometry yields temperatures of 550-1110℃.The clinopyroxene compositions suggest formation from a mafic magma with tholeiitic to calc-alkaline affinities in a volcanic arc.