Capability of pozzolanic activity of north Dehgolan volcanic ash (East of Kurdistan)

In the north of Dehgolan in Uromieh-Dokhtar zone, volcanic rocks of Miocene age are exposed. Composition of the rocks is mainly intermediate to acidic and rarely basic. Porphyric texture is dominated. Rhyodacitic lahar and ash are main units in the area. Plagioclase and hornblende are main phonocrystals and quartz, alkali feldspar and biotite are also present. Matrix is mainly silicic glass. The ash unit is characterized by its abundant xenoliths and low density because of high degree of porosity. After petrography and geochemical study, pozzolanic activity of ash unit was investigated by thermogravimetry (STA) method. Pozzolanic activity for Dehgolan acidic ash is 49.36 percent which present the first order stand in classification of activity. Chemically, mole ratio values of Dehgolan samples (Al2O3/ (CaO+Na2O+K2O) per Al2O3/ (K2O+Na2O)) are in good agreement with known pozzolans in Iran and other countries.