福建省政和县狮子岗含矿交代岩研究
发布时间：2019-04-21 14:36
【摘要】：狮子岗含矿交代岩位于福建省政和县城东,属于铁山岩体的西南端。铁山岩体呈北东向展布于东峰-铁山-张元庵一线,其侵位受北东向政和-大埔断裂控制,长期以来被认为是中国东南部仅有的两个印支期正长岩体之一。狮子岗地区以往也认为是正长岩体,通过详细的野外地质调查和钻探工程验证,发现该“岩体”具有明显的铜铅锌多金属矿化,出露隐爆角砾岩和次火山岩,特别是发育强烈的流体交代蚀变作用(包括青磐岩化、黄铁绢英岩化、钾化、硅化等),但缺乏典型的正长岩。因此,狮子岗地区的赋矿母岩究竟是正长岩、还是隐爆角砾岩或交代蚀变岩之争。笔者通过对狮子岗不同岩类进行矿物学、地球化学、年代学研究,发现“岩体”角砾岩、浅色部分(包括钾化脉及成因存在争议的正长岩部分)具有类似地球化学、年代学特征,并具有相同的暗色矿物组合,由此可以认为狮子岗地区出现的岩石类型为交代蚀变岩。“岩体”中浅色部分(包括钾化脉及成因存在争议的正长岩部分)所有钾长石均为微斜长石,其结构温度为200-370℃之间,低于中酸性岩浆岩的固相线温度(650℃-925℃),这为该“岩体”的交代成因提供了又一重要的证据。狮子岗交代岩中不同岩类锆石具有花岗岩的微量元素特征,锆石LA-MC-ICP-MS定年集中在250-255Ma之间,显示狮子岗地区存在印支期的岩浆活动。狮子岗交代岩锆石具有变化较大的εHf(t),暗示其形成锆石的初始岩浆为岩浆混合成因,而其中个别锆石εHf(t)0,为幔源组分在岩浆的成岩活动过程的贡献提供了直接证据。锆石二阶段模式年龄变化较大,范围为1.20～1.86Ga,显示中-古元古代地层为其最主要物源区,但其年龄大多数小于华夏地壳基底变质岩,这也为成岩过程中存在幔源组分参与提供了有力的证据。
[Abstract]:Shizigang ore-bearing metasomatism rock is located in the east of Zhenghe County, Fujian Province, and belongs to the southwest end of Tieshan rock mass. The Tieshan massif is distributed in the Dongfeng-Tieshan-ZhangYuanan line, and its emplacement is controlled by the NE-trending Zhenghe-Dapu fault. It has long been considered to be one of the only two Indosinian syenite bodies in southeastern China. Shizigang area also considered as syenite in the past. Through detailed field geological investigation and drilling engineering verification, it was found that the "rock mass" had obvious Cu, Pb and Zn polymetallic mineralization, and exposed cryptoexplosive breccia and subvolcanic rocks. Especially, strong fluid metasomatism and alteration (including cypress, pyrite sericite, potash, silicification, etc.), but lack of typical syenite. Therefore, whether the host rock in Shizigang area is syenite, cryptoexplosive breccia or metasomatism altered rock. On the basis of mineralogical, geochemical and chronological studies of different rocks in Shizigang, it is found that the breccia of "rock mass", the light-colored part (including potash vein and the disputed syenite part of origin), has similar geochemistry. Because of the chronological characteristics and the same dark mineral assemblage, the rock types in Shizigang area are metasomatism altered rocks. All of the potash feldspar are microplagioclase in the light color part of the "rock mass" (including potash vein and the disputed syenite), whose structure temperature is between 200 鈩，
本文编号：2462296
[Abstract]:Shizigang ore-bearing metasomatism rock is located in the east of Zhenghe County, Fujian Province, and belongs to the southwest end of Tieshan rock mass. The Tieshan massif is distributed in the Dongfeng-Tieshan-ZhangYuanan line, and its emplacement is controlled by the NE-trending Zhenghe-Dapu fault. It has long been considered to be one of the only two Indosinian syenite bodies in southeastern China. Shizigang area also considered as syenite in the past. Through detailed field geological investigation and drilling engineering verification, it was found that the "rock mass" had obvious Cu, Pb and Zn polymetallic mineralization, and exposed cryptoexplosive breccia and subvolcanic rocks. Especially, strong fluid metasomatism and alteration (including cypress, pyrite sericite, potash, silicification, etc.), but lack of typical syenite. Therefore, whether the host rock in Shizigang area is syenite, cryptoexplosive breccia or metasomatism altered rock. On the basis of mineralogical, geochemical and chronological studies of different rocks in Shizigang, it is found that the breccia of "rock mass", the light-colored part (including potash vein and the disputed syenite part of origin), has similar geochemistry. Because of the chronological characteristics and the same dark mineral assemblage, the rock types in Shizigang area are metasomatism altered rocks. All of the potash feldspar are microplagioclase in the light color part of the "rock mass" (including potash vein and the disputed syenite), whose structure temperature is between 200 鈩，
本文编号：2462296
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