Geochemical discrimination of intrusions in the Choran Cu-Au deposit, Iran, using silicate chemistry
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External Organisational units
- Shahid Chamran University of Ahvaz
- Faculty of Earth Sciences
The Choran CueAu deposit is located 70 km of Bardsir in the southern part of Urumieh-Dokhtar magmatic belt (UDMB). In this area, mineralization is associated with Oligocene –Miocene quartz diorite and granodiorite intrusions emplaced within Eocene volcanic–pyroclastic – sedimentary sequences. Main hydrothermal altera- tions in the Choran region include sodic-potassic and potassic as well as phyllic, alunite and kaolinite which extended mostly in the granodiorite. Mineralizations at the Choran deposit involve pyrite, arsenopyrite, chal- copyrite, chalcocite, covellite and sphalerite. The composition of the plagioclase in the granodiorite and quartz diorite rocks ranges from albite (66.8 to 48.7) and (64.8 to 51.4) respectively. Also, Al/(Ca + Na + K) ratios of plagioclase in granodiorite samples (average; 1.50) are higher than that of quartz diorite intrusions (average; 1.33) which is analogous to those reported previously for mineralized porphyry systems. All studied primary and re-equilibrated biotites are collectively clustered in the Mg-biotite field. However, based on the log (XMg/XFe) versus log (XF/XOH) of biotite, granodiorite units are associated with I-type moderately crustal contaminated (I- MC) suite, whereas quartz diorite biotites represent I-type weakly crustal contaminated (I-WC) character. Comparison of biotite halogen contents indicates that F and Cl values increase from quartz diorite to grano- diorite intrusions. Importantly, biotite thermometry of granodiorite and quartz diorite samples indicate tem- peratures of < 400 °C (quartz diorite; average 340 °C, granodiorite; average 379 °C) which are overlapped with temperature of sulfide mineralization in the porphyry systems (< 400 °C). Totally, through assessing the key factors of mineralization using silicate chemistry, it is proved that granodiorite units have higher potential to form porphyry-style sulfide mineralization in the Choran deposit.