云南南涧各救母岩体地球化学特征及其构造背景

各救母岩体位于滇西富碱斑岩带中,属于金沙江-红河富碱侵入岩带的南段。对岩体进行了地球化学特征分析。样品主量元素的分析表明,各救母岩体属中酸性岩,具有高钾、高碱的特征,属于高钾钙碱性或钾玄岩系列;微量和稀土元素的分析表明,该岩体LREE/HREE值和(La/Yb)_N值分别为12.60~19.25和17.02~34.87,属于轻稀土富集型,δEu为0.73~0.98,Eu具轻微的负异常,形成各救母岩体的岩浆应来自于高压环境的上地幔-下地壳,经历了地幔交代作用,并与富碱岩浆进行了混合。各救母斑岩体锆石U-Pb定年(LA-MC-ICPMS)加权平均年龄为(37.91±0.35) Ma(n=27,MSWD=0.99)。研究表明各救母岩体处于印度欧亚大陆的晚碰撞构造转换阶段,亦为后碰撞的早期阶段。

Geochemical Characteristics and Tectonic Setting of Gejiumu Lithosome in Nanjian County,Yunnan

Gejiumu Lithosome located in the western Yunnan alkali‐rich porphyry band , which belongs to the southern section of Jinshajiang Red River alkali‐rich intrusive lithosome .An analysis is conducted to figure out the geochemical characteristics of the rock mass .The result shows that Gejiumu Lithosome is characterized by high potassium ,alkali ,and belongs to a high potassium calc‐alkali or potassium basalt series .The trace and lanthanon elements analysis show that the ratios of LREE/HREE and (La/Yb)N are 12 .60 19 .25 and 17 .02 34 .87 respectively , belonging to the light lanthanon enrichment type ,with the delta Eu of 0 .73 0 .98 ,a slight negative Eu anomaly . The magma of Gejiumu Lithosome should come from a high‐pressure environment of the upper mantle or the lower.