Petrographic and geochemical investigation of Eocene volcanic rocks in Shirinsu area (South of Lowshan) and comparison with alteration zones
|Location||The 24 Symposium of Geosciences|
|Author||Asadi, Nahid*** Emami, mohammad Hashem**Imanipoor, Maryam*|
|Holding Date||27 August 2007|
Shirinsu area is a part of West Alborz structural zone and is portion of Sofla Tarom area. Rock units in this area are consist of olivine basalt, andesite, trachyandesite, dacite and rhyodacite with Eocene age.Basalts are related to alkaline series with high Potassium content and intetmediate and acidic terms are related to calc-alkaline series with intermediate to high Potassium content.Field observation, petrographic and geochemical evidences lead to fractionation, mixing, contamination and crustal melting phenomenona in formation of intermediate- acidic terms.
The alteration is one of important characterizes of this area. Alteration zones are very wide and consist of argilic- alunitic and silicic parts. Formation of this alteration zones is a result of high sulfide alteration soloutions effect on volcanic units. Some times alteration is of supergene type and resulted from atmospheric soloutions influence on the country,s rocks. This kind of alteration is mostly argilic