The Study of Bentonites and Zeolites from Moalleman Area (South of Damghan), Sosanvar Bentonite and Gandi Zeolite Deposits

The study area with coordination of 54º 30' to 54º 39' E and 35º 18' to 35º 21' N is located in Moalleman area, in the south west of Torud Quadrangle. In the structural-sedimentary zoning, this area belongs to depression parts. In the north part of the area, equivalent of the Karaj Formation crops out from Sosanvar village to the south of Gandi kaolinite deposit. This formation is composed lithologically of shale, marl, sandstone, limestone, dolostone, radiolarite, tuffite, zeolite, and bentonite with the age of Lutetian (Middle Eocene). This paper has been focused on the types, composition, and environment of bentonite and zeolite layers of Sosanvar bentonite and Gandi zeolite formation. According to these investigations the bentonites and zeolites have been formed from acidic volcanic glass (ryolitic and dacitic) and their magmatic series is alkaline. Conversion of glass to bentonite and zeolite has occurred under diagenetic conditions in shallow sea water (e.g. lagoon). In diagenetic conditions, the bentonites have absorbed magnesium and calcium and zeolites absorbed sodium and potassium. The clay form of this Wyoming-type bentonite is smectite (bedellite) and zeolites are Na-clinoptilolite type.