云南光茅山地区斑岩体地质特征及构造环境分析——来自主量元素地球化学方面的证据

对云南光茅山地区斑岩体的岩石学和主量元素地球化学特征进行分析,研究区斑岩体的SiO2、Al2O3、Na2O和K2O的平均质量百分数分别为67.84%、15.39%、3.40%和4.37%,里特曼指数平均为2.40,固结指数和分异指数平均值分别为11.14和82.95。主量元素特征表明:其属SiO2过饱、过铝质和富碱高钾的钙碱性系列的斑岩体,属于造山期后A型花岗岩;其形成于喜山期陆陆碰撞接壤处的地壳消减带构造环境。研究区斑岩体在主量元素地球化学特征和成岩构造环境方面,不同程度的表现出与马厂箐斑岩体的相似性,具有寻找与马厂箐斑岩型矿床相同模式的铜、钼(金)多金属矿床的前景。

An analysis of geological characteristics and tectonic environment of porphyry body in Guangmaoshan area of Yunnan- geochemical evidence of the major elements

The analysis on petrology and geochemical characteristics of maj or elements of the porphyry body in Guangmaoshan area of Yunnan indicates that the average weight percentage of SiO2 ,Al2 O3 ,Na2 O and K2 O in porphyry body are respectively 67.84%,15.39%,3.40% and 4.37%,and Rittman index averages 2.40, and the average solidification index and the average differentiation index are respectively 11.14 and 82.95. The characteristics of maj or elements indicate that the porphyry body is a kind of calc-alkalic series porphyry body which is characterized by supersaturated SiO2 ,peraluminous,alkaline-rich and potassium-rich,and it falls in the category of post orogenic type A granite.It is formed in the tectonic environment of crustal sub-duction zone which locates at the boundary of continent-continent collision during Himalayan period.The ge-ochemical characteristics of maj or elements and diagenetic structure environment of the porphyry body in the study area exhibit similarity with those of Machangqing porphyry body to varying degrees,and the study area has a favorable prospect as Machangqing Porphyry deposit in discovering Cu-Mo （Au）polymetallic deposits by using the same mode.