Economic Geology
Sahar Tarabi; Mohamad Hashem Emami; Sourosh Modaberi; Seyed Jamal Shaykh Zakariaee
Abstract
Momen-abad area, in the southeast of Birjand and the northeast of Sarbisheh, is located in the Sistan-Zemestan zone. Based on the field studies, petrography, geochemical (XRF) and X-ray diffraction (XRD) in two volcanic sequences, the alteration conditions in the area have been investigated. According ...
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Momen-abad area, in the southeast of Birjand and the northeast of Sarbisheh, is located in the Sistan-Zemestan zone. Based on the field studies, petrography, geochemical (XRF) and X-ray diffraction (XRD) in two volcanic sequences, the alteration conditions in the area have been investigated. According to mineralogy and chemical studies, bentonites are sodium-calcium and heterogeneous. Mineralogy findings indicate that smectite minerals, cristobalite and quartz, alkaline feldspars (albite and anorthite and sanidine), gypsum, calcite, hematite, holandite, klinoptiolite, kaolinite, ileite, and halite minerals form bentonites. In the first sequence, the effects of argillic and iron oxide alterations and in the second sequence, the effects of alteration of argillic, carbonate, chlorite, calcite, albite, silicification and iron oxide are found. Altered units which are related to the second sequence in four layers include Rhyolytic perlites of the vein, masses, lenses; white bentonites and green; Rhyodacite and dacite with the effects of alteration of devitrification, and the alteration of perlite to bentonite, advanced argillic and silicification. In addition, the composition textures of lava-pyroclastic, devitrification and the alteration of perlite to bentonite due to diagenetic alteration are found out. Glass argillization and feldspars in volcanic units, and the alteration of plagioclase to albite + sericit, biotite to chlorite, stone to quartz, calcite, zeolite and chlorite in perlites, iron oxide veins and red unit are found out in the sequences. Moreover, the change color of bentonite in the region related to alteration hydrothermal, and the presence of fluids and iron-magnesium-rich solutions are obvious in these sequences.
