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- Title
Fluid inclusion and stable isotope constraints on the genesis of the Jian copper deposit, Sanandaj- Sirjan metamorphic zone, Iran.
- Authors
Asadi, S.; Moore, F.; Fattahi, N.
- Abstract
The Jian copper deposit, located on the eastern edge of the Sanandaj- Sirjan metamorphic zone, southwest of Iran, is contained within the Surian Permo- Triassic volcano-sedimentary complex. Retrograde metamorphism resulted in three stages of mineralization (quartz ± sulfide veins) during exhumation of the Surian metamorphic complex (Middle Jurassic time; 159-167 Ma), and after the peak of the metamorphism (Middle to Late Triassic time; approximately 187 Ma). The early stage of mineralization (stage 1) is related to a homogeneous H2 O- CO2 ( XCO2 > 0.1) fluid characterized by moderate salinity (<10 wt.% Na Cl equivalent) at high temperature and pressure (>370°C, >3 kbar). Early quartz was followed by small amounts of disseminated fine-grained pyrite and chalcopyrite. Most of the main-ore-stage (stage 2) minerals, including chalcopyrite, pyrite and minor sphalerite, pyrrhotite, and galena, precipitated from an aqueous-carbonic fluid (8-18 wt.% Na Cl equivalent) at temperatures ranging between 241 and 388°C during fluid unmixing process ( CO2 effervescence). Fluid unmixing in the primary carbonaceous fluid at pressures of 1.5-3 kbar produced a high XCO2 (>0.05) and a low XCO2 (<0.01) aqueous fluid in ore-bearing quartz veins. Oxygen and hydrogen isotope compositions suggest mineralization by fluids derived from metamorphic dehydration (δ18 Ofluid = +7.6 to +10.7‰ and δ D = −33.1 to −38.5‰) during stage 2. The late stage (stage 3) is related to a distinct low salinity (1.5-8 wt.% Na Cl equivalent) and temperatures of (120-230°C) aqueous fluid at pressures below 1.5 kbar and the deposition of post-ore barren quartz veins. These fluids probably derived from meteoric waters, which circulated through the metamorphic pile at sufficiently high temperatures and acquire the characteristics of metamorphic fluids (δ18 Ofluid = +4.7 to +5.1‰ and δ D = −52.3 to −53.9‰) during waning stages of the postearly Cimmerian orogeny in Surian complex. The sulfide-bearing quartz veins are interpreted as a small-scale example of redistribution of mineral deposits by metamorphic fluids. This study suggests that mineralization at the Jian deposit is metamorphogenic in style, probably related to a deep-seated mesothermal system.
- Subjects
IRAN; METAMORPHISM (Geology); COPPER; MINERALOGY; IRON ores
- Publication
Geofluids, 2013, Vol 13, Issue 1, p66
- ISSN
1468-8115
- Publication type
Article
- DOI
10.1111/gfl.12013