下庄矿田西部黄沙坑地区蚀变碎裂岩地球化学特征与成矿机制探讨

Geochemical Characteristics and Metallogenic Mechanism of Altered Catabatic Rocks in the Huangshakeng Area, Western Xiazhuang Orefield

黄沙坑地区位于下庄铀矿田西部,以印支期下庄岩体似斑状黑云母花岗岩为主体,多处被北西西向黄陂石英断裂带切过,出露蚀变碎裂岩、构造角砾岩及碎裂化正长岩夹层,其蚀变种类多,后期热液活动频繁,断裂带上下盘构造均有铀异常反应,具有良好的找矿前景。本文以碎裂岩及围岩的岩相学和地球化学特征为研究内容,以构造带、花岗岩小岩体和热液蚀变"三位一体"原则探讨该地区的成矿机制,认为成矿区应定位于黄陂石英断裂带与花岗岩补体延伸的复合地段,中期中温富铀碱性热液与后期中低温富硅酸性热液叠加部位,即表现为硅化、赤铁矿化、钾长石化、绢云母化等蚀变同时出现、构造带碎裂岩、角砾岩碎裂程度高的深部往往有富大矿体。

Huangshakang area is located in the west of Xiazhuang uranium ore field. The porphyroid biotite granites of Xiezhuang rock in Indosinian period were the main parts, and many parts were cut by the north west west to the Huangye quartz fault zone. The cataclastic rocks and tectonic horns were exposed and altered. The conglomerate and disintegrated syenite interbeds have many types of alterations and frequent hydrothermal activities in the later period. There are uranium anomalies in the structure of the upper and lower plates of the fault zone, which has a good prospect for ore prospecting. In this paper, the petrographic and geochemical characteristics of cataclastic rock and surrounding rock are studied. The metallogenic mechanism of the area is discussed based on the principle of ＂trinity＂ of tectonic zone, small granite body, and hydrothermal alteration. It is believed that the metallogenic area should be located. In the composite section of the Huangqi quartz fault belt and the granite complement extension, the intermediate mid-temperature rich uranium alkaline hydrothermal fluid and the late-middle-temperature low-temperature silicon-rich acidic hydrothermal superposition indicate silicification, hematite mineralization, potassium long petrochemistry, and sericitization. A large orebody is often found in the deep parts where isomorphous alterations occur at the same time, in the tectonic belt cataclastic rocks, and in breccia fractures.