滇西古近纪钾质—超钾质岩浆岩成岩成矿作用及构造意义  

Petrogenesis Mineralization and Tectonic Implications of Paleoproterozoic Potassic-Ultrapotassic Magmatic Rocks in Western Yunnan

作　　者：全海辉 柴鹏 袁玲玲 焦守涛 QUAN Haihui;CHAI Peng;YUAN Lingling;JIAO Shoutao(Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Natural Resources Comprehensive Survey Command Center,China Geological Survey,Beijing 100055,China)

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]中国地质调查局自然资源综合调查指挥中心,北京100055

出　　处：《黄金科学技术》2024年第2期220-240,共21页Gold Science and Technology

基　　金：国家重点研发计划项目专题“青藏高原典型地区深部新老地壳物质架构示踪方法”(编号:2019YFA0708602);中国地质科学院基本科研业务费项目“深地实验室重点攻关项目”(编号:JKYZD202312);国家自然科学基金项目“吉林延吉地区闹枝中硫化型浅成低温热液金—多金属矿床成矿过程精细刻画”(编号:41973045)联合资助。

摘　　要：滇西地区广泛发育古近纪钾质—超钾质岩浆岩,形成沿金沙江—哀牢山断裂带富碱岩浆岩带,因缺乏对该钾质—超钾质岩浆岩带的系统研究,岩石成因及其与成矿之间的关系尚存在诸多争论。通过收集该富碱岩浆岩带已发表的全岩主微量元素、Sr-Nd同位素、锆石Hf同位素及年代学数据,根据构造位置,将该岩带划分为南、中、北岩带3个部分。通过系统对比分析得出:滇西古近纪钾质—超钾质岩浆岩成岩年龄基本一致,峰值为35 Ma,为同一期构造热事件的产物;基性—超基性和中酸性岩类具有不同成因,前者富集大离子亲石元素(LILE),亏损高场强元素(HFSE),高(87Sr/86Sr)i比值,低εNd(t)值,可能来源于板片交代的富集岩石圈地幔,后者具有较高的SiO2含量,可能为壳幔混合的产物;基性—超基性和中酸性岩类的形成均与金沙江—哀牢山断裂的剪切走滑和拉伸作用相关,是同一构造热事件下岩石圈不同深度部分熔融的产物;南中岩带钾质—超钾质岩浆岩与斑岩型金—(铜—钼)矿床关系密切,其岩浆形成过程可能为成矿提供了高氧逸度和含水量的有利条件,以及成矿物质和成矿流体。The Paleoproterozoic potassic-ultrapotassic magmatic rocks are widely developed in western Yunnan,forming an alkali-rich magmatic rock belt along the Jinshajiang-Ailaoshan fracture zone.Due to the lack of systematic research on these potassic-ultrapotassic magmatic rocks,there are still many debates on the petrogenesis and their relationship with mineralization.In this paper,through the collection of published wholerock major and trace element,Sr-Nd isotope,zircon Hf isotope and geochronology data of the whole rock in the alkali-rich magmatic belt,the rock belt is divided into three parts,namely,south,central and north rock belts according to the tectonic position.Through systematic comparative analysis,it is concluded that the diagenetic age of Paleoproterozoic potassic-ultrapotassic rock formation in western Yunnan is basically the same,with a peak value of 35 Ma,which is the product of the same period of tectonic thermal events.The basic-ultramafic and intermediate-acid rocks have different genesis.The former enriched in LILEs,deficit HFSEs,high(87Sr/86Sr)i,and lowεNd(t)values,probably originating from a slab-accounted enriched lithospheric mantle.The latter may be the product of crust-mantle mixing due to its higher SiO2 content.The formation of both is related to the shear slip and tensile action of the Jinshajiang-Ailaoshan fault,which is the product of partial melting of the lithosphere at different depths under the same tectonic thermal event.The potassic-ultrapotassic rocks of the southern and central rock belts are closely related to porphyry Au-(Cu-Mo)deposits.The magmatic formation process may provide favorable conditions for mineralization with high oxygen fugacity and water content,as well as ore-forming materials and ore-forming fluids.

关 键 词：滇西 钾质—超钾质岩 岩石成因 成矿作用 新生下地壳 新生代 

分 类 号：P611[天文地球—矿床学]