摘要
Based upon geological and geochemical data on the genesis of Gongchangling rich magnetite deposit, it is suggested that the deposit is of multigenesis, and a three-stage geochemical model for the genesis of the deposit is proposed : (1) Depositional stage : the deposition of banded low-grade ores (magnetite-quartzite) was accompanied by high-grade magnetite (hematite)-siderite ores which are intercalated with magnetite-quartzites as lenses or stratoid shoots. (2) Metaamorphic stage: In response to metamorphism, siderite was decomposed into magnetite and graphite with decreasing fo2 and increasing PCO2. On the margin of magnetitc-siderite ores or within the thin intercalated layers where fO2, was high relative to PCO2 were formed graphite-free rich magnetite ores. (3) Hydrothermal stage: As a result of later hydrothermal process diffusive metasomatism between the shoots and host rocks anti silica leaching took place, thus giving rise to the rich magnetite ores of metasomatic type, and altered rocks.
Based upon geological and geochemical data on the genesis of Gongchangling richmagnetite deposit,it is suggested that the deposit is of multigenesis,and a three-stagegeochemical model for the genesis of the deposit is proposed:(1)Depositional stage:the deposition of banded low-grade ores(magnetite-quart-zite)was accompanied by high-grade magnetite(hematite)-siderite ores which areintercalated with magnetite-quartzites as lenses or stratoid shoots.(2)Metamorphic stage:In response to metamorphism,siderite was decomposedinto magnetite and graphite with decreasing f_(o_2)and increasing P_(co_2).On the margin ofmagnetite-siderite ores or within the thin intercalated layers where f_(o_2),was high relativeto P_(co_2)were formed graphite-free rich magnetite ores.(3)Hydrothermal stage:As a result of later hydrothermal process diffusive me-tasomatism between the shoots and host rocks and silica leaching took place,thusgiving rise to the rich magnetite ores of metasomatic type,and altered rocks.
出处
《地球化学》
CAS
1982年第2期113-121,共9页
Geochimica
