نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشگاه صنعتی بیرجند
2 گروه زمینشناسی، دانشکده علوم، دانشگاه بیرجند، بیرجند، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In Jannatabad area, bentonites formed as a result of the alteration of intermediate to acidic tuffs and lavas (andesite, trachyandesite, dacite) belonging to a calc alkaline series. XRD results show that montmorillonite is the dominant mineral, accompanied by cristobalite, anorthite, microcline, and minor amounts of kaolinite, and clinoptilolite. Thermal and ethylene glycol treatments confirm the montmorillonitic nature of smectite. SEM images show aggregates of fine smectite particles. EDS data indicate a silicate–aluminosilicate composition with minor Fe, K, Na, and Ca elements. XRF and ICP-MS results show that the lavas and bentonites fall within the rhyodacite–dacite and trachyandesite range of a subduction-related calc-alkaline series and the REE patterns suggest a common magmatic affinity.
Mass balance also shows SiO₂ enrichment and depletion of alkalis, consistent with hydrothermal alteration and montmorillonite formation. The Qaleh Sorkh fault, as structural controls have played an important role in guiding hydrothermal fluids and the formation of bentonites.
کلیدواژهها [English]
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