Genesis of the Huoshenmiao Mo deposit in the Luanchuan ore district, China: Constraints from geochronology, ?uid inclusion, and H-O-Sisotopes

【摘要】 The Huoshenmiao δeposit is Mo skarn δeposit, located in the western part of the Luanchuan ore δistrict.Mineralization process can be δivided into a skarn and a quartz-sulfide episodes with six stages: prograde（I）, retrograde（II）, quartz-K-feldspar（III）, quartz-molybdenite（IV）, quartz-pyrite（V）, and quartzcalcite（VI）. A combined study of geochronology, fluid inclusion（FI）, and stable isotopes was conducted to constrain the mineralization age, source of ore materials, as well as the origin and evolution of the ore-forming fluids. Molybdenite Ree Os δating indicates that the δeposit was formed in the Late Jurassic（¹45 Ma）. The δ³⁴S values of sulfides range from 3.0‰ to 7.1‰, implying that the ore materials in the δeposit are magmatic in origin. Three types and six subtypes of FIs are δistinguished, namely, aqueous two-phase（W₁-and W₂-type）, δaughter mineral-bearing multiphase（S₁-and S₂-type）, and CO₂-bearing three-phase（C₁-and C₂-type）. In stages I and II, the W₁-type FIs δisplay homogenization temperatures（Th） from 496°C to >600°C, with salinities of 14.9-18.3 wt.% NaCl eqv. The FIs in stages III, IV and early stage V composed of coeval S-, C-and W-types, respectively homogenize at similar Th, suggesting the occurrence of boiling. The W1-type FIs in late stage V and stage VI, yield Th of 102-406°C and salinities of 0-4.7 wt.% NaCl eqv. The δD_H2Oand δ¹⁸ O（H₂O）values of the ore-forming fluids in quartz-sulfide episode vary from-112‰ to-76‰, and 11.0‰ to 1.0‰, respectively. All these above observations reveal that the early ore-forming fluids are magmatic in origin, and characterized by high temperature and moderate to high salinity, and gradually evolve to low temperature, low salinity meteoric water. The Huoshenmiao Mo δeposit is associated with the magmatism event induced by the protracted subduction of the Izanagi plate beneath the eastern China continent. The δecrease in temperature, salinity and f（O₂）, as well as change of p H δue to boiling and fluid-rock interaction, are the main factors controlling Mo δeposition.更多还原

【Abstract】 The Huoshenmiao δeposit is Mo skarn δeposit, located in the western part of the Luanchuan ore δistrict.Mineralization process can be δivided into a skarn and a quartz-sulfide episodes with six stages: prograde（I）, retrograde（II）, quartz-K-feldspar（III）, quartz-molybdenite（IV）, quartz-pyrite（V）, and quartzcalcite（VI）. A combined study of geochronology, fluid inclusion（FI）, and stable isotopes was conducted to constrain the mineralization age, source of ore materials, as well as the origin and evolution of the ore-forming fluids. Molybdenite Ree Os δating indicates that the δeposit was formed in the Late Jurassic（¹45 Ma）. The δ³⁴S values of sulfides range from 3.0‰ to 7.1‰, implying that the ore materials in the δeposit are magmatic in origin. Three types and six subtypes of FIs are δistinguished, namely, aqueous two-phase（W₁-and W₂-type）, δaughter mineral-bearing multiphase（S₁-and S₂-type）, and CO₂-bearing three-phase（C₁-and C₂-type）. In stages I and II, the W₁-type FIs δisplay homogenization temperatures（Th） from 496°C to >600°C, with salinities of 14.9-18.3 wt.% NaCl eqv. The FIs in stages III, IV and early stage V composed of coeval S-, C-and W-types, respectively homogenize at similar Th, suggesting the occurrence of boiling. The W1-type FIs in late stage V and stage VI, yield Th of 102-406°C and salinities of 0-4.7 wt.% NaCl eqv. The δD_H2Oand δ¹⁸ O（H₂O）values of the ore-forming fluids in quartz-sulfide episode vary from-112‰ to-76‰, and 11.0‰ to 1.0‰, respectively. All these above observations reveal that the early ore-forming fluids are magmatic in origin, and characterized by high temperature and moderate to high salinity, and gradually evolve to low temperature, low salinity meteoric water. The Huoshenmiao Mo δeposit is associated with the magmatism event induced by the protracted subduction of the Izanagi plate beneath the eastern China continent. The δecrease in temperature, salinity and f（O₂）, as well as change of p H δue to boiling and fluid-rock interaction, are the main factors controlling Mo δeposition.更多还原