ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    赤城县马道口钼矿床流纹斑岩地球化学特征及找矿意义

    Geochemical Characteristics and Prospecting Significance of Perdu Rhyolite Porphyry in Madaokou Molybdenum Deposit, Chicheng County

    • 摘要: 张家口沽源中生代火山断陷盆地周边已发现张麻井(460)、大官厂(534)等大中型铀钼矿床和多个铀钼矿化点,铀钼矿(化)体多赋存于早白垩世张家口组火山岩地层之下的流纹斑岩中。近年来发现的赤城马道口钼矿床位于沽源火山盆地边缘,钼矿体亦主要赋存于流纹斑岩。笔者通过对马道口钼矿区流纹斑岩与张麻井(460)、大官厂(534)流纹斑岩形成时代及岩石地球化学对比分析发现,马道口钼矿床流纹斑岩形成时代与460、534铀钼矿区相近,均形成于早白垩世;马道口钼矿区含矿与不含矿流纹斑岩相比,不含矿斑岩发生明显碱交代作用,SiO2和Mo含量显著降低,K2O、Na2O含量明显升高,矿床属碱交代型热液铀矿床。流纹斑岩体中Mo含量与460、534斑岩体相当或接近,而U显著低于460、534矿区流纹斑岩体,与华北地台花岗岩均值接近,显示马道口矿区为单钼矿床,非铀钼矿床类型,这也与目前找矿勘查现状相吻合。研究显示流纹斑岩不仅是主要的成矿物质来源,也是重要的找矿勘查目标地质体。

       

      Abstract: There are some Large and medium-sized uranium-molybdenum deposits such as Zhangmajing (460) and Daguangchang (534) and several uranium-molybdenum mineralization sites have been found around the Guyuan Mesozoic volcanic faulted basin in Zhangjiakou. Uranium-molybdenum deposits (mineralization bodies) mostly occur in the perdu rhyolite porphyry under the volcanic strata of the Zhangjiakou Formation of the Early Cretaceous. Madaokou molybdenum deposit which lie in volcanic basin edge is been found in recent years, based on the analysis of rock geochemical and formation age of perdu rhyolitic porphyry, conclude that the formation age of Madaokou perdu rhyolite porphyry is similar to 460, 534 uranium deposits, are all formed in the Early Cretaceous; Compared with the ore-bearing gray perdu rhyolite porphyry to ore-free porphyry of Madaokou area, the ore-free porphyry has obvious alkali metasomatism, and the contents of SiO2 and Mo are significantly reduced, while the contents of K2O and Na2O are significantly increased. The content of Mo element in Madaokou porphyry mass is similar to or close to 460 and 534 porphyry mass, while U element is significantly lower than 460 and 534 porphyry mass, which is close to the average value of granite in North China platform. Indicating that Madaokou mining area is a single molybdenum deposit, non-uranium molybdenum deposit type, which is also consistent with the current prospecting status. The perdu rhyolite porphyry is the main source of ore-forming material, the type of ore deposit belongs to alkali metasomatic hydrothermal deposit. The perdu rhyolite porphyry can be used as an important target geological body for mineral exploration.

       

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