Document Type : Original Research Paper


1 School of Geology, University College of Science, University of Tehran, Tehran, Iran.

2 School of Geology, University College of Science, University of Tehran, Tehran, Iran

3 Department of Geology, Islamic Azad University, Science & Reseach Campus, Tehran, Iran


In the west and north west of Hassan-Abaad village of Yazd, massive dikes of alkali andesite in the diorite, quartz diorite and granodiorite are observed. Clinopyroxene phenocrysts in these rocks have obvious zoning. Reconnaissance work indicates that groundmass pyroxenes in the alkaline rocks are similar to the more evolved phenocryst rims. Obtained data from core to rim of Clinopyroxene phenocrysts by SEM point analysis, show that Clinopyroxene composition, contains Chrome-diopsides, Salites-ferrosalites and Titanaugite. Clinopyroxene zoning formed during crystal growth. These pyroxenes are believed to record an intricate history of stop-start differentiation, magma-mixing, entry or disappearance of high-pressure precipitates. The salitic and ferrosalitic crystals of the Hassan-Abaad andesite also represent accidental fragments of anomalous upper mantle wall rocks.


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