• 主管:

      天津市地质矿产勘查开发局

    • 主办:

      天津地热勘查开发设计院

    • ISSN

      1001-1412  CN 12-1131/P

    太行山北段塔子沟隐爆角砾岩的成因矿物学研究

    Genetic Mineralogical Study of the Cryptoexplosive Breccia in Tazigou, Northern Taihang Mountains

    • 摘要: 太行山多金属成矿带是重要的中生代岩浆热液型矿床成矿带,而隐爆角砾岩筒是重要的含矿构造,具有重要的成矿指示意义。通过对太行山北段塔子沟二长花岗岩锆石U-Pb年代学、Lu-Hf同位素以及锆石和黑云母成因矿物学研究,获得以下认识:二长花岗岩的锆石U-Pb年龄为(117.2±1.2)Ma,系白垩纪早期产物;岩石源区存在年轻地幔物质与古老地壳的混合;锆石形态标型演化趋势揭示岩浆由混合源区向壳源区演化,暗示深部岩浆房经历地壳混染或分异结晶,促使成矿物质在浅部富集;锆石结晶温度为632.75~815.73 ℃、\lg f_\mathrmO_2 为−16.69~−5.00,ΔFMQ-1.75~FMQ+9.16,黑云母结晶温度为717.50~729.84 ℃、寄主岩浆氧逸度\lg f_\mathrmO_2 为−16.35~−16.02,反映高温、高氧逸度环境,可促进成矿元素迁移;黑云母具壳幔混源特征(IMg(Mg/(Fe+Mg))值为0.55~0.58,其值>0.5),属富镁黑云母;log(f_\mathrmH_2\mathrmO /fHF)fluid值为1.38~1.63,log(f_\mathrmH_2\mathrmO /fHCl)fluid值为4.11~4.65,表明岩浆晚期富挥发分,为热液成矿创造条件;综合陆缘弧构造背景、壳幔混源岩浆、隐爆角砾岩储矿空间及高氧逸度-富挥发分特征,认为研究区具备良好的岩浆热液型铜、金多金属矿床成矿潜力。

       

      Abstract: The Taihang Mountains Polymetallic Metallogenic Belt is an important Mesozoic magmatic-hydrometal metallogenic belt, and the cryptoexplosive breccia pipes within it are significant ore-hosting structures with important implications for mineralization. Based on zircon U-Pb geochronology, Lu-Hf isotopes, and genetic mineralogical studies of zircon and biotite from the monzogranite, which constitutes the main lithology of the cryptoexplosive breccia pipe in Tazigou, Tang County, Hebei Province, the following understandings have been obtained: Zircon U-Pb dating of the monzogranite yields an age of (117.2±1.2) Ma, indicating Early Cretaceous emplacement; The source region involves mixing of juvenile mantle-derived materials with ancient crustal components; Zircon morphological typology evolutionary trends reveal magma evolution from hybrid sources toward crustal domains, implying deep magma chambers experienced crustal assimilation or fractional crystallization, which facilitated preferential enrichment of metallogenic elements at shallow levels. Zircon crystallization temperatures (632.75 ℃ to 815.73 ℃) and oxygen fugacity values \lg f_\mathrmO_2 = –16.69 to –5.00; ΔFMQ = –1.75 to +9.16), combined with biotite crystallization temperatures (717.50 ℃ to 729.84 ℃) and host magma \lg f_\mathrmO_2 (–16.35 to –16.02), reflect a high-temperature, high-oxygen fugacity environment conducive to metallogenic element transport. Biotite exhibits hybrid crust-mantle signatures (IMg(Mg/(Fe+Mg))=(0.55 to 0.58)>0.5), classifying as magnesian biotite. The log(f_\mathrmH_2\mathrmO /fHF)fluid value ranges from 1.38 to 1.63 and the log(f_\mathrmH_2\mathrmO /fHCl)fluid value ranges from 4.11 to 4.65, indicating enrichment in volatiles during the late magmatic stage, creating favorable conditions for hydrothermal mineralization. Integrating the continental margin arc setting, hybrid crust-mantle magmas, cryptoexplosive breccia-hosted mineralization spaces, and high oxygen fugacity coupled with volatile-rich signatures, the study area is interpreted to possess significant potential for magmatic-hydrothermal copper-gold polymetallic mineralization.

       

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