نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زمینشناسی اقتصادی، دانشگاه تربیت مدرس، تهران، ایران
2 گروه زمینشناسی اقتصادی، دانشگاه تربیت مدرس، تهران.ایران
3 گروه زمینشناسی اقتصادی، دانشگاه تربیت مدرس، تهران ، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The Gishoun Pb-Zn deposit is located in the northwest of Bam, on the southwestern margin of the Lut Block, within the Cenozoic tectono-magmatic zone of Central Iran. It is associated with the Urumieh-Dokhtar magmatic arc. The Eocene volcanic rocks in the area comprise basalt, andesite, dacite, rhyolite, and pyroclastic tuffs, and are mineralogically composed mainly of plagioclase, quartz, K-feldspar, biotite, clinopyroxene, and olivine. Subvolcanic dikes of both doleritic and granitic compositions are also observed in the region. These rocks belong to the medium- to high-K calc-alkaline to shoshonitic magmatic series. The systematic decrease in CaO, MgO, FeOt, TiO₂, and P₂O₅ with increasing SiO₂ reflects the role of fractional crystallization in their magmatic evolution. Enrichment in LILE and LREE, along with negative anomalies of Nb, Ta, and Ti, are diagnostic features of these rocks. Doleritic dikes, characterized by higher Sr and Ni contents and a weaker negative Eu anomaly, served as the primary heat source and played a decisive role in the development of the Gishoun epithermal deposit, but they are not hosts to mineralization. In contrast, granitic dikes, enriched in Rb, Th, and K₂O with a more pronounced negative Eu anomaly, show no association with alteration or mineralization. The integrated petrographic and geochemical data indicate that all rock units of the Gishoun deposit formed in a continental magmatic arc setting related to the subduction of the Neotethyan oceanic slab.
کلیدواژهها [English]
)