摘要:
湖南浏阳七宝山铜多金属矿床位于钦杭成矿带西南段,是湘东北规模最大的铜多金属矿床,其中矿区内的石英斑岩对成矿贡献非常大。七宝山矿区的石英斑岩是一套高钾(K20〉〉Na2O)、富铝、贫硅的亚碱性的粗面安山岩—安山岩—英安岩组合,地球化学上显示了富轻稀土(LREE)、大离子亲石元素(LILE)(Ba,K等)、成矿元素(Cu、Pb、Zn等),以及贫重稀土元素(HREE)特征。稀土元素配分模式为右倾,有轻微的Eu负异常,说明它具有部分幔源特征;而明显的Sr负异常,且与地壳丰度相似,加上较高Al2O3/TiO2、K2O/Na2O比值,投图后均显示岩石为地壳来源。综合上述特征本文认为该石英斑岩属壳幔同熔型花岗岩。矿体与岩体在空间、时间上关系密切,岩体很高的成矿元素含量正是形成矿体的物质来源。其作用过程是岩浆作为载体携带成矿元素从地幔到近地表,并且在各种导矿构造作用下充填交代成矿。
Abstract:
Qibaoshan Cu-ploymetallic section of Qinzhou-Hangzhou metallogenic deposit of Liuyang, belt. And it is the Hunan province, is occurred in the southwest largest Cu-polymetallic deposit in northeastern Hunan province. The quartz-porphyry is in a very large contribution to the mineralization of the Qibaoshan Cu-polymetallic deposit. The quartz-porphyry of the ore district is consist of trachyandesite, andesite and dacite with the geochemical feature of high K (K20〉〉Na20) and Al, low Si, and is characterized by significant enrich- ments in LREE, LILE ( Ba and K ), and minerogenetic elements (Cu, Pb, Zn etc.), as well as depletion in HREE. The slight right-dip model of REE and slight Eu negative anomaly considers that the source of magma is partly from the mantle. However, clear Sr negative anomaly is so similar to the crustal source magma. Higher Al2O3/TiO2, K20/Na20 ratio than ordinary granite is indicated that quartz porphyry is mainly coming from the crust. The quartz-porphyry may be the crnst-mantle syntectic granite. The ore bodies are so close with the quartz-porphyry which is rich in ore-forming elements in space and timing is indicated that the magma may provide the metals. The process is that the magma carries ore-forming elements from the mantle to the near surface, then mineralization after filling or metasomatism in a variety of structure.
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