Geological, Mineralogical and Geochemical studies of Zeolitic tuffs in Damavand-Firuzkoh area, East Tehran

   Abstract:
      Studies area focused on the upper parts of karaj formation in Damavand-Firuzkoh area. Filed studies indicated that, green tuffs of karaj formation in kilan, Hesarbon, and Zarindasht are altered, due to this alteration they are changed to zeolite and clay minerals. The altered tuffs with comparison to flash tuffs are lighter and have less hardness. Microscopic studies of zeolitic tuffs have shown that, the main component from these tuffs is altered glass. This glass has a special shape, known as glass shards. The shards are changed to zeolites from their margins. Zeolites have low Interference color and low relief, In addition to zeolite mineral, clay mineral is also replaced to glass shards. Scanning Electron Microscopic studies are confirmed the change of glass shard to zeolite and clay mineral from their margins. Thermal curves testes (TG & DTG) are determined the existence of clinoptilolite and carbonate impurity in altered vitric tuff. There are also distinguished major mineral phase clinoptilolite, creistobalite and minor mineral phase. Muscovite, montmorillonite by X-Ray diffract meter. Geochemical studies on the base of XRF and ICP data are indicated that, chemical composition of this tuffs, are in the range of acid to intermediate rocks. Chemical composition of which is the same as the unaltered tuffs.
  
   Keywords: Tuff, Zeolite, Firuzkoh, Clinoptilolite