نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشگاه پیام نور
2 گروه زمین شناسی، دانشگاه پیام نور
3 گروه زمین شناسی، دانشکده علوم، دانشگاه شهید بهشتی
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The Belqis Mountain demantoid occurrence, located northeast of Takab in the northern Sanandaj–Sirjan Zone, is one of the most important skarn-related gemstone garnet deposits in Iran. This study investigates the geology, mineralogy, mineral chemistry, and gemological characteristics of the demantoids using field observations, petrography, gemological analyses, and electron probe microanalysis (EPMA). The garnets belong to the andradite–grossular series, and chromium enrichment (up to 3.47 wt.% Cr₂O₃ and 11.95 mol% uvarovite component) is the principal cause of the characteristic green color. Oscillatory zoning indicates fluctuations in fluid composition and oxidation conditions during garnet growth. The mineral assemblage comprises garnet, diopside, wollastonite, and magnetite. Garnet–clinopyroxene geothermometry indicates formation at 500–650 °C and 1–2 kbar. Fibrous chrysotile inclusions and chromium enrichment indicate the influence of fluids derived from adjacent ultramafic rocks. Petrographic, geochemical, and gemological evidence suggests that the Belqis demantoids formed within a skarn system controlled by magmatic, hydrothermal, and ultramafic-related processes.
کلیدواژهها [English]
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