2.05-Ga Isotopic Ages for Transvaal Mississippi Valley–Type Deposits: Evidence for Large-Scale Hydrothermal Circulation around the Bushveld Igneous Complex, South Africa
2.05-Ga Isotopic Ages for Transvaal Mississippi Valley–Type Deposits: Evidence for Large-Scale Hydrothermal Circulation around the Bushveld Igneous Complex, South Africa
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德兰士瓦密西西比河谷型矿床的 2.05 Ga 同位素年龄：南非布什维尔德火成岩杂岩周围大规模热液循环的证据
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
H. Zwingmann
中科院分区：
文献类型：
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作者：
J. Gleason;J. Gutzmer;S. Kesler;H. Zwingmann
与 2.055 Ga 布什维尔德火成岩杂岩体 (BIC) 侵位相关的热液循环的已知规模随着 BIC 周围围岩（德兰士瓦超群）中古元古代矿床的新同位素年龄而扩展。 Zeerust 地区富含萤石的密西西比河谷型 (MVT) 矿床，年代为 2.05 Ga（Sm-Nd 等时线年龄），其 Nd 同位素组成与 BIC 侵入序列晚期的同期富 F Lebowa 花岗岩相同，表明岩浆流体输送到 BIC 目前边缘以外约 100 公里处。来自 Zn-Pb MVT Bushy Park 矿床的热液伊利石，通过 K-Ar 地质年代学测得的年代为 2.05 Ga，将 Kaapvaal 克拉通广泛的 MVT 矿床与 BIC 侵位相关的大规模盆地盐水循环联系起来。这些数据与金矿脉、磷酸盐矿物和古地磁重置年龄相结合，表明存在一个区域规模的布什维尔德时代热液系统，该系统从 BIC 目前的边缘向外循环 700 公里。
The known dimensions of hydrothermal fluid circulation associated with emplacement of the 2.055-Ga Bushveld Igneous Complex (BIC) are extended with new isotopic ages for Paleoproterozoic mineral deposits in wallrocks (Transvaal Supergroup) surrounding the BIC. A fluorite-rich Mississippi Valley–type (MVT) deposit in the Zeerust district, dated at 2.05 Ga (Sm-Nd isochron age), has Nd isotopic compositions that are identical to coeval F-rich Lebowa Granite late in the BIC intrusive sequence, suggesting transport of magmatic fluids ∼100 km beyond the present margins of the BIC. Hydrothermal illite from the Zn-Pb MVT Bushy Park deposit, dated at 2.05 Ga by K-Ar geochronology, links widespread MVT deposits of the Kaapvaal craton to large-scale basinal brine circulation associated with emplacement of the BIC. These data, in combination with gold vein, phosphate mineral, and paleomagnetic resetting ages, indicate a regional-scale Bushveld-age hydrothermal system circulating 700 km outward from the present margins of the BIC.