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.
