新疆青河县库布苏破碎蚀变岩型金矿元素迁移特征与规律研究

Characteristics and Regularities of Mass Transfer in the Kubusu Gold Deposit of Clastic-Altered Rock Type in Qinghe County,Xinjiang

本文以新疆库布苏金矿北矿带为研究对象,讨论了库布苏金矿床北矿带元素活动特征,成矿及伴生元素、主量元素、微量元素、稀土元素的质量迁移规律;根据稀土元素的质量迁移、地球化学特征,初步探讨了成矿流体的环境条件和来源问题;并依据元素迁移地球化学图研究了库布苏北矿带105勘探线剖面的元素质量迁移程度和范围。研究结果表明,赋矿闪长玢岩脉及围岩的元素发生明显的带入带出作用,元素迁移活动规律明显,成矿阶段发生明显带入有Au、As、Bi、Ag、Sb、K2O、Si O2,说明引起闪长玢岩脉和接触带围岩蚀变的流体中富含Au、As、K2O、Si O2等,导致这些带入元素向矿体迁移富集;发生明显带出的有Ba、Sr、Cu、Mg O、Na2O、Fe2O3、Ca O,说明Ba、Sr、Mg O、Na2O等受热液蚀变作用随流体迁出。矿区岩脉的稀土元素质量变化显著,发生明显的带入带出,岩脉交代蚀变前后的轻重稀土分馏均明显,蚀变后的岩脉轻重稀土分馏程度有减小趋势。赋矿闪长玢岩脉稀土元素配分曲线右倾,轻稀土富集,轻重稀土分馏明显,Eu强烈负异常,Ce弱负异常,说明库布苏金矿成矿流体条件应为较高温度和还原环境。从围岩与脉岩中元素的迁移程度和迁移范围可见,带入的成矿指示元素有As、W、Sb、Bi,带出的成矿指示元素有Mg、Na。

This paper focused on the northern belt of the Kubusu gold deposit in Xinjiang. It discussed the characteristics of element activity,mass transfer of metallogenic elements,associated elements,trace elements,major elements and rare earth elements in this area. It studies the environmental conditions and source of ore-forming fluids according to mass transfer and geochemical characteristics of rare earth elements. Degree and range of mass transfer were also studied in exploration line 105 of this belt based on the geochemical anomaly map of element mass transfer. The results show that the elements of ore-bearing diorite porphyrite veins and surrounding rocks played significant input and output roles,and the element migration has obvious regularities. Au,As,Bi,Ag,Sb,K2 O,and SiO 2were brought in to orebodies in metallogenic stage,suggesting that the fluids containing abundant Au,As,K2 O,SiO 2and so forth could cause alteration,making these elements move into orebodies and concentrate there. While Ba,Sr,Cu,MgO,Na2 O,Fe2O3,and CaO moved out,implying that Ba,Sr,MgO,Na2 O etc. were subject to hydrothermal alteration,causing these elements to flow out with fluids. The REE had also significant input and output,and light and heavy REEs before and after vein alteration all show obvious fractionation. After the vein alteration,the fractionation degree of light and heavy REEs had a decreasing tend. REE of ore-bearing diorite porphyrite veins distribution pattern is obviously dipping right and takes on light REE enrichment,strong Eu negative anomalies,weak Ce negative anomalies,showing that the property of Kubusu gold deposit's ore-forming fluids should be in a high-temperature and reduction environment. Based on degree and range of mass transfer of veins and surrounding rocks,input indicator elements are As,W,Sb,and Bi,and output indicator elements are Mg and Na.