摘要
西藏尼木斑岩铜多金属矿区位于冈底斯铜钼多金属成矿带中段,具典型斑岩型铜矿床矿化特征。区内岩浆岩从酸性到中酸性均有出露,通过对不同类型岩浆岩主量、微量、稀土元素的分析测试结果显示,其SiO_2变化于57.94%~70.12%,平均为67.63%,K_2O+Na_2O变化于6.68×10^(-6)~8.84×10^(-6),平均约7.97×10^(-6),多属高钾钙碱性岩石;各类岩石中W、Pb、Th,Ba、As、Sb、Bi、Ag、Rb、Te、Cs、Hf明显富集,而Ta、V、Hg、Au、Sc、Cr、Co、Ni、Nb、Mo等明显贫化;稀土总量变化于89×10^(-6)~427×10^(-6),稀土配分曲线呈明显的右倾型,轻稀土相对富集,基本无Eu异常。里特曼指数(δ)-戈蒂尼指数(τ )关系图、(Yb+Ta)-Rb、(Y+Nb)-Rb构造环境判别图均显示其形成于岛弧环境造山带环境;A-C-F图解显示为I-S型过渡型,相对偏向于S型。综合分析认为区内岩浆岩应为青藏高原隆升中地壳部分融熔的产物,可能为同源、同构造环境下岩浆分异的结果。
The porphyry copper polymetallic mining area in Nimu is located in the middle of Gangdese copper molybdenum polymetallic metallogenic belt with typical porphyry copper deposit mineralization characteristics. The acidic magmatic rocks are exposed from the intermediate-acid to the acid. Major, trace and rare element analysis to the magmatic rock shows that its SiO2 contents are in the range of 57.94% -70. 12% （average 67.63% ）, K2O ＋ Na2O contents are in the range of 6.68 × 10 ^-6 - 8.84× 10^ -6 （ average 7.97 × 10^-6 ） ,most of them are character- ized by highly-enriched kalium cale-alkaline. The trace elements are characterized by enrichment of W, Pb, Th, Ba, As, Sb, Bi, Ag, Rb, Te, Cs, Hf, depletion of Ta, V, Hg, Au, Sc, Cr, Co, Ni, Nb, Mo. The total rare earths range from 89 ×10^ -6 to 427× 10^-6. They have right-declining of rare earth elements distribution patterns and there is no Eu anomalies. Rittmann index（8） vs GeDiNi index（t）, （Yb ＋ Ta） vs Rb, （Y ＋ Nb） vs Rb diagram all indicate the magmatic rock are formed in island-arc environment or orogenic belt environment. A vs C vs F diagram shows it be- longs to the I-S transitional type, relative tend to S type. Comprehensive analysis shows that the magmatic rocks are produced by the partial melting of crustal in the process of Qinghai-Tibet Plateau uplifting. Maybe, they were pro- duced by the differentiation of homologous magma in the same tectonic setting.
出处
《科学技术与工程》
北大核心
2016年第4期141-147,151,共8页
Science Technology and Engineering
基金
云南省科技计划项目资助
关键词
斑岩铜矿
岩浆岩
地球化学特征
成因
西藏尼木
porphyry copper
magmatic rock
geochemical characteristics
genesis
Nimu in Tibet
