نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه زمینشناسی، واحد تهران شمال، دانشگاه آزاد اسلامی، تهران، ایران.
2 گروه زمینشناسی، واحد لاهیجان، دانشگاه آزاد اسلامی، لاهیجان، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The NE Natanz (Badroud) intrusive bodies, outcropping in the Mahur–Chah-Kaleh elevations (120 km SE of Kashan, NE Badroud, Isfahan Province; 52∘15′–52∘30′ E and 33∘52′–34∘00′ N), are emplaced within Eocene volcanic sequences in the central Urumieh–Dokhtar Magmatic Belt (UDMB). The intrusive complex predominantly comprises granite, granodiorite, syenite, and syenodiorite. Geochemically, these rocks exhibit high-K calc-alkaline affinities, dominant metaluminous to borderline peraluminous signatures, and characteristic I-type granitoid features. On normalized multi-element diagrams, pronounced enrichments in large-ion lithophile elements (LILEs) and light rare earth elements (LREEs), coupled with prominent negative high-field-strength element (HFSE) anomalies (notably Nb, Ta, and Ti), demonstrate the significant role of subduction-related metasomatism in the source region. Elevated La/Sm and Sm/Yb ratios reflect derivation from an enriched lithospheric mantle (EM) source. Variations in trace-element systematics (e.g., Zr–Y) are attributed to post-melting processes and accessory phase fractionation (zircon and apatite), entirely consistent with the source characteristics. Geochemical trends delineate two distinct evolutionary paths: (1) granitoids generated via fractional crystallization of arc calc-alkaline magmas dominated by plagioclase and amphibole fractionation; and (2) syenitic–syenodioritic suites derived from low-degree partial melting of a metasomatized mantle with intra-suite differentiation coupled with minor crustal contamination at shallow emplacement levels. Overall, this intrusive assemblage records a transitional continental arc to post-collisional tectonic setting related to the Neo-Tethyan subduction system during the Eocene.
کلیدواژهها [English]
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