甘肃省南祁连化石沟铜矿区绢英岩蚀变地球化学特征  

Geochemical characteristics of sericitolite in Huashigou copper deposit, South Qilian, Gansu

作　　者：潘美慧[1] 贾志磊[2,3] 欧健[4] 侯鹏博 

机构地区：[1]西北师范大学地理与环境科学学院,甘肃兰州730070 [2]兰州大学地质科学与矿产资源学院,甘肃兰州730000 [3]甘肃省地质矿产勘查开发局,甘肃兰州730000 [4]江苏省地质调查研究院,江苏南京210018 [5]甘肃省电力设计院,甘肃兰州730050

出　　处：《地球化学》2015年第4期370-376,共7页Geochimica

基　　金：甘肃省2009年矿产资源补偿费项目(甘国土资勘发〔2009〕15号)

摘　　要：化石沟铜矿位于阿尔金-祁连-柴北缘的交汇部位，区内侵入岩发育，中二叠世英云闪长斑岩与铜矿的关系最为密切，岩石绢英岩化、硅化等后期蚀变发育，部分交代作用强者转变为绢英岩。绢英岩具有高Si、Ba、LREE，低Al、Ti、Ca、Sr、Y和MREE的地球化学特征，运用Isocon图解法，经与原岩（英云闪长斑岩）对比，认为蚀变热液是富Si的，并带入大量SiO2，而CaO、Na2O、TiO2、MnO等明显迁出。岩石δ18^Ov-SMOW值（12．6‰～12．8‰）与原岩基本一致，表明参与蚀变的流体来源于岩浆后期热液，该热液类型可能在成矿作用过程中起到十分重要的作用。The Huashigou copper deposit, located about 90km southwest of Lenghu Town and 120km east of Akasay County, is tectonically situated in the southwest margin of South Qilian Mountains. The granitoids and the tonalite porphyry formed in Middle Permian are most closely related to formation of Cu-deposit. Alteration such as phyllic alteration and silicification, etc. develops well in the tonalite porphyry, which serves to convert the rock type to sericitolite in some areas. Sericitolite resulted from alteration shows high contents of Si, Ba and LREEs, and low contents of Al, Ti, Ca, Sr, Y and MREEs. Plot of SiO2 projection above the Isocon line and plots of CaO, Na2O, TiO2, MnO projection under the Isocon line show that the former migrates from hydrothermal alteration while the latter is removed out of the country rock. The characteristics of high-Si and δ^18OV-SMOW values （12.6‰-12.8‰） indicate that the hydrotherm is Si-enriched and originates from late magmatic hydrothermal fluid of tonalite porphyry. However, the hydrotherm may be significant to Cu metallization due to the close relationship between tonalite porphyry and Cu ore bodies.

关 键 词：蚀变 热液 元素迁移 化石沟 南祁连 

分 类 号：P59[天文地球—地球化学] P595[天文地球—地质学]