Economic Geology
Kiamars Hosseini; Majid Shahpasandzadeh; Roghayeh zabihi khargh
Abstract
The Sangan Mining District (SMD) in the north of the Cenozoic magmatic belt of eastern Iran is constituted of predominantly acidic to intermediate volcanic and pyroclastic rocks, intruded by the Eocene granitoids. In the Baghak Fe skarn deposit, these granitoids are composed of pre-mineralization ...
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The Sangan Mining District (SMD) in the north of the Cenozoic magmatic belt of eastern Iran is constituted of predominantly acidic to intermediate volcanic and pyroclastic rocks, intruded by the Eocene granitoids. In the Baghak Fe skarn deposit, these granitoids are composed of pre-mineralization biotite quartz monzonite, biotite syenite to biotite syenogranite, alkali feldspar quartz syenite to alkali feldspar granite and syn-mineralization quartz alkali syenite and quartz syenite. These I type granitoids have a magnesian metaluminous, calcalkaline, high K alkaline to shoshonitic nature. The granitoids show enrichment of LREE/HREE and LILE/HFSE with negative anomalies of Eu,Sr,Ta,Th and Ti, posetive anomalies of U, K, Ba, and Rb together with high La values and Zr/Nb, Nb/Th, Nb/U, and Nb/La ratios which suggest not only their slab-derived mantle source, but also crustal mixing in evolution of the magma. The Sm/Yb versus La/Sm, Sm/Yb versus Sm and Dy/Yb versus La/Yb show derivation of the primary melt from low partial melting (2-5 %) of a garnet-spinel lherzolite at depth of ~66-68 kilometers of the upper mantle, affected by continental crust melts. According to this research, the tectono-magmatic setting of the granitoids is suggested syn- to post-orogenic magmatic arc.
Petrology
kiamars hosseini; Majid Shahpasandzadeh
Abstract
The Late Neoproterozoic-Early Cambrian albite-bearing metasomatite, rhyolites and rhyodacites predominantly constitute the host rocks of the Choghart magnetite-apatite deposit in Central Iran. The geologic evidences show three types of albites in the host albite-bearing metasomatite. The performed mineralogical ...
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The Late Neoproterozoic-Early Cambrian albite-bearing metasomatite, rhyolites and rhyodacites predominantly constitute the host rocks of the Choghart magnetite-apatite deposit in Central Iran. The geologic evidences show three types of albites in the host albite-bearing metasomatite. The performed mineralogical and geochemical investigations display enrichment of REE-Y-Ti-Th in the pink and fleshy red albites, whereas the white albites are barren without any ore mineralization. The concentration of REE-Y-Ti-Th-U bearing minerals along the fractures, the variation of Th/U ratio and result of stable isotopes studies of the calcites syn-paragenesis with the abiltes reveal the involvement of mixed magmatic and high-midium temperature hydrothermal processes play an important role in the ore genesis. The similarity pattern of the REEs and trace elements in different types of abilte-bearing metasomatite and rhyolite manifest the origin of REE-Y-Ti-Th mineralization as the rhyolitic-rhyodacitic magmas, related to a continental/oceanic subduction zone. According to this research, tectono-magmatic setting of the albite-bearing metasomatite in the Choghart deposit is suggested as a Calc-alkaline magmatism, associated with the active continental margin and oceanic island arcs.
