豫西雷门沟斑岩钼矿床钾长石化蚀变特征及其成矿意义  

Alteration Characteristics of K-feldspar in Leimengou Porphyry Mo Deposit in Western Henan Province and Its Insight into Metallogenetic Process

作　　者：陈小丹[1] 叶会寿[2] 汪欢[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院矿产资源研究所,北京100037

出　　处：《现代地质》2012年第3期478-488,共11页Geoscience

基　　金：国土资源部全国危机矿山接替资源找矿项目(20089949;200841019)

摘　　要：豫西雷门沟钼矿床属于东秦岭钼矿带典型的斑岩型矿床之一,矿床广泛发育钾长石化,呈面型和线型2种形式产出。据野外观察,面型钾长石化以成矿前钾长石化蚀变围岩为特征,包括钾长石化花岗斑岩和钾长石化片麻岩,蚀变岩石主要由钾长石构成,少量石英和斜长石残留,蚀变强烈时石英、斜长石等消失,全岩钾长石化,为成矿前围岩蚀变;线型钾长石化包括钾长石细脉、钾长石-萤石辉钼矿脉和石英辉钼矿脉边部的钾长石化晕,钾长石呈脉状充填或者交代脉边部的石英,为成矿阶段蚀变。电子探针成分分析表明,蚀变形成的钾长石K2O含量较高,Na2O、CaO含量较低。X衍射结构显示,蚀变形成的钾长石为微斜长石,蚀变温度为310～418℃,表明由碱性热液交代形成。Pb同位素组成显示钾长石中K质主要来源于地幔。根据成矿热液具有富碱质的地幔来源特征,结合Mo元素地球化学特征,认为退化碱质交代作用有助于雷门沟斑岩钼矿床的形成。Leimengou Mo deposit in Western Henan Province is a typic porphyry Mo deposit in East Qinling Mo- lybdenum belt. The deposit pervasively develops K-feldspar alteration, including vein type and whole rock al- teration. The whole rock alteration charactered as the porphyry and the gneiss being potassic altered absolutely. Vein type alteration is represented by the K-feldspar slevage, K-feldspar fluorite vein amd K-feldspar halo be- side the margin of quartz-molybdenum veinnet. This paper analyzed the alteration features of K-feldspar, compo- sition of altered minerals, X-ray powder diffraction and Pb isotope composition of types of altered K-feldspar. The compositions of feldspar show that K20 is the main compontent; X-ray powder diffraction data suggest that K-feldspar are andesine-microcline with alteration temperatures of 310 -418 ~C. Pb isotope composition show that K in K-feldspar originates from mantle. According to the mantle derived characteristics of the ore-forming fluid, combining with the geochemistry of Mo, we conducted that the K-feldspar alteration has a good interpreta- tion on the metallogenic process.

关 键 词：钾长石化 X衍射 PB同位素 雷门沟斑岩钼矿床 豫西 

分 类 号：P614[天文地球—矿床学] P618.6[天文地球—地质学]