摘要
昌都地区位于"三江"成矿带中段,岩浆活动频繁,构造复杂,具良好成矿潜力,是我国重要有色金属-贵金属矿产地。夏雅岩体为中生代侵入体,以岩枝、岩脉等形式产出,岩性主要为黑云母二长花岗岩。黑云母二长花岗岩具高SiO2、K2O+Na2O,低Al2O3、TiO2、Fe2O3+FeO、MgO、CaO特点。Rittmann指数平均2.22,K2O含量高于Na2O,属钙碱性岩系。黑云母二长花岗岩ΣREE平均252.18×10-6,ΣCe/ΣY平均7.44,(La/Yb)N平均22.33,属轻稀土富集型。δEu平均0.42,铕亏损显著。夏雅岩体锶同位素初始值和TiO2含量与大陆地壳值相近,是造山期后环境下由上地壳物质重熔融形成的A型花岗岩。夏雅岩体具富F,B,W,Sn含矿特征。富F,B挥发份对稀有金属元素具亲和性,使W,Sn等元素首先进入富挥发份熔体中,挥发份的强解聚特性促使富氟花岗岩浆发生液态不混溶作用,使富挥发份熔体与母岩浆分离。含稀有金属熔体长距离的迁移利于W,Sn富集成矿。通过对夏雅黑云母二长花岗岩岩石化学特征、微量和稀土元素含量分析,结合矿区地质条件,初步探讨夏雅富氟、硼花岗岩类成矿作用。
ChangDu area is located in the middle of Sanjiang metallogenic belt, has frequent Magmatism and strong tectonic acivity,and being an important non-ferrous and precious mentals base for its good potential of mineralization. The Xiaya rockbody,a Mesozoic intrusions,which is constituted by biotite adamellite,forming appoplysis and rock dikes. The chemical constituents of Xiaya biotite adamellite are characterized by high Si02 and K20＋Na20 contents,but with low A1203,Ti02, Fe203＋Fe0,Mg0,Ca0 contents.lt belongs calc-alkalic rock series with the average of Rittman index is 2.22 and Higher K20 content.The average of ￡REE,SCe/2Y,5Eu and （La/Yb）N are 252.18〉〈10-6,7.44,22.33 and 0.42. LREE and HREE have strong differentiation.The biotite adamellite is rich in LREE,and with negative Eu anomalies.ini- tial 87Sr/86Sr ratios and Ti02 of Xiaya rockbody are similar with continental crust values,which belongs to A-type gran- ites.lt were formed by re-melting of the upper crust substances in a post orogenic environment.The elements of F、B、W and Sn are enriched in Xiaya rockbody.The F、B-rich volatile has an affinity for the rare metals,which make the elements of W、Sn first into the volatile-rich melt. The characteristics of strong depolymerization of volatiles promote the reaction of liquid immiscibility in fluorine-rich granitic magma,which make the Volatile-rich melt Separate from parent magma. The long-range transport of rare metals-rich melt conducive to the enrichment and mineralization of W、Sn.Combining the geological condition with the analysis of results of petrochemistry ^ trace element and REE of Xiaya biotite adamellite, this article makes a preliminary study of the mineralization of Xiaya rockbody.
出处
《新疆地质》
CAS
CSCD
北大核心
2013年第4期346-352,共7页
Xinjiang Geology
基金
西藏邦达地区地质矿产调查项目(1212010918028)资助
关键词
昌都
夏雅岩体
富氟
硼花岗岩
成矿作用
ChangDu area, Xiaya rockbody, Fluorine and Boron-rich granite magma, Mineralization
