Kamaladdin Bazargani-Guilani - Department of Geology, University of Tehran, Tehran ۱۴۱۵۵-۶۴۵۵, Iran
Mohammad Sadegh Rabbani - Department of Chemistry, University of Tehran, Tehran ۱۴۱۵۵-۶۴۵۵, Iran
Ali Akbar Irajian - National Drilling Company, Ahwaz, Iran

Field, thin section, XRD, ICP-ES, ICP-MS and SEM studies of nalcime bearing tuffs of Abdolabad region, 120 km east of Tehran, central Alborz, were performed to understand the formation conditions of the analcime in tuffs of Karaj Formation Analcime was found with quartz in the lower layers of Karaj Formation, while white opal-CT and smectite were in the upper part of the Formation. Diagenetic dolomite and celestite with analcime bearing tuffs occur in the upper part of Karaj Formation. The absence of pumpellyite in association with analcime, the relatively low thickness of the Karaj Formation in the study region and absence of other metamorphic minerals with analcime are in favor of diagenetic character of analcime in the east central Alborz.

Analcime, Karaj Formation, Central Alborz