Nahid Asadi; Mohammad Hashem Emami; Monireh Kheirkhah
Volume 1, Issue 3 , December 2010, , Pages 11-28
Abstract
The Abtorsh- Youzbashichai alteration zone, located in Tarom zone, is an obvious example of hydrothermal type alteration that found in trachyandesitic tuffs and lavas. Based on the ...
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The Abtorsh- Youzbashichai alteration zone, located in Tarom zone, is an obvious example of hydrothermal type alteration that found in trachyandesitic tuffs and lavas. Based on the field observations, mineralogical and geochemical investigations and satellite images there are argillic, advanced argillic, alunitic and silicic zones in this altered area. These zones exhibit a regular zonation from down to up. Some evidences such as following of alteration from rock fractures system and the patches of unaltered host rock in alteration body also confirm the hydrothermal type alteration in this area. Considering widespread existence of some minerals such as kaolinite, alunite, jarosite, and silica in alteration paragenesis and the trend of enrichment and depletion of elements (major & trace) observed in alteration stages, it seems that this area is influenced by acid- sulfate (high sulfidation) type alteration. The diagrams and alteration reactions confirm that enrichment or depletion of elements in alteration stages depends on their geochemical nature, their abundances in source rock, the type of altered minerals and their structures as well as physicochemical properties of alteration solutions.
