كاني‌شناسي و ژئوشيمي دگرساني‌هاي گرمابي در حاشيه شرقي باتوليت گرانيتوئيدي قهرود (جوينان)

Mineralogy an‎d Geochemistry of Hydrothermal Alterations in the Eastern Margin of the Qorud Granitoid Batholith (Jovinan)

زمين شناسي

The East Ghahroud area is located within the Central Iran structural–metallogenic zone an‎d is of significant importance for iron–copper mineralization. This study investigates the petrographic, mineralogical, alteration, an‎d geochemical characteristics of granitoid an‎d skarn units in order to clarify magma genesis an‎d the processes responsible for mineralization. The principal lithological units include granodiorite, associated granitoids, garnet–clinopyroxene skarn, peridotite, epidote skarn, an‎d sulfide–carbonate an‎d altered hydrothermal veins. Petrographic studies indicate that the granodiorites exhibit granular to porphyritic textures an‎d consist mainly of plagioclase, quartz, K-feldspar, an‎d biotite, affected by alteration processes such as chloritization, sericitization, an‎d epidotization. The skarns are predominantly calcic in composition an‎d are characterized by an‎dradite–grossular garnet an‎d diopsidic clinopyroxene. Mineralization occurs in vein-type, massive, ban‎ded, an‎d disseminated forms, including magnetite, hematite, chalcopyrite, chalcocite, an‎d secondary oxide minerals formed through supergene processes. Major an‎d trace element geochemical data reveal a calc-alkaline affinity an‎d metaluminous to weakly peraluminous nature for the granitoids. Rare earth element (REE) patterns display enrichment of LREE relative to HREE an‎d a negative Eu anomaly in the granitoids, suggesting plagioclase fractionation during magmatic evolution. In contrast, some skarn samples exhibit relatively flat REE patterns with positive Eu anomalies, indicating the influence of hydrothermal fluids. Tectonomagmatic discrimination diagrams place these rocks in a subduction-related magmatic arc setting, likely associated with the subduction of the Neo-Tethyan oceanic lithosphere along the margin of Central Iran. Accordingly, the iron–copper mineralization in the study area is interpreted as the result of interaction between calc-alkaline granitoid magma an‎d carbonate host rocks, accompanied by iron-rich hydrothermal fluids in a subduction-related tectonic environment. These findings provide valuable implications for the exploration of similar mineral deposits within the metallogenic zones of Central Iran.

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