南祁连党河南山地区中酸性浅成侵入体和岩脉岩石地球化学特征及其与金矿成矿关系

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摘要：南祁连党河南山地区加里东晚期中酸性小型浅成侵入体和岩脉包括花岗（斑）岩、次流纹斑岩、次英安斑岩和石英闪长（玢）岩。岩石SiO2质量分数为53.05%～74.12%，K2O与Na2O质量分数之和为4.01%～1043%。岩石系列包括钙碱性、高钾钙碱性、钾玄岩和碱性系列，以高钾钙碱性和碱性为主，具过铝质—准铝质性质。岩石稀土元素总含量较低，相对富集轻稀土元素、大离子亲石元素（Rb、Ba、La、Ce、Sr）、Th和U，亏损高场强元素（Nb、Ta、Zr、Hf）和重稀土元素，具弱—中等负Eu异常。中酸性侵入体和岩脉产出特征和微量元素特征显示岩石形成于后碰撞环境，岩浆源岩为变质基性岩及少量变质碎屑岩，可能指示其继承了源岩的地球化学特征。岩浆在侵位过程中与围岩发生了交代作用。岩浆分异程度从石英闪长（玢）岩→次英安斑岩→花岗（斑）岩→次流纹斑岩逐渐增强。脉岩Au含量较低，偏酸性脉岩在蚀变后Au含量普遍升高，偏中性脉岩（石英闪长岩）在狼查沟、东洞沟矿区为金矿成矿提供了热源和物源。

关键词：浅成侵入体；岩脉；地球化学；岩石成因；构造环境；金矿；古生代；祁连山

中图分类号：P588文献标志码：A

Geochemical Characteristics of Intermediateacid Hypabyssal Intrusions

and Dykes in Danghenanshan Area of South Qilian and

Its Implications on the Gold Mineralization

DAI Shuang1，2， LIU Bo1，2， YAN Ningyun1， ZHANG Xiang1，2，3， JIN Zhipeng4， MENG Zhen4，

YANG Huaiyu4， WU Zhijiang4， BAI Bin4， ZHANG Lili1，2， PENG Dongxiang1，2

（1. College of Earth and Environmental Sciences， Lanzhou University， Lanzhou 730000， Gansu， China；

2. Key Laboratory of Western Chinas Environmental Systems of Ministry of Education， Lanzhou University，

Lanzhou 730000， Gansu， China； 3. Gansu Institute of Geological Survey， Lanzhou 730000， Gansu， China；

4. No.2 Institute of Geological and Mineral Exploration of Gansu， Lanzhou 730030， Gansu， China）

Abstract： The Late Caledonian small intermediateacid hypabyssal intrusions and dykes in Danghenanshan area of South Qilian include granite and granite porphyry， subrhyolite porphyry， subdacite porphyry， quartz diorite and quartz diorite porphyrite. The mass fractions of SiO2 are 53.05%74.12%， and the sums of mass fractions of K2O and Na2O are 4.01%10.43%. The rock series include calcalkaline， highpotassium calcalkaline， shoshonite and alkaline with the characteristics of peraluminousquasialuminous， and the highpotassium calcalkaline and alkaline series are main. The rocks have the characteristics of low contents of rare earth elements， and are relatively eiched in light rare earth elements， large ion lithophile elements （Rb， Ba， La， Ce and Sr）， Th and U， and relatively depleted in high fieldstrength elements （Nb， Ta， Zr and Hf） and heavy rare earth elements with weakmediate negative Eu anomaly （0.70.9）. The occurrence characteristics of intermediateacid intrusions and dykes and the analysis results of trace elements show that the rocks form in postcollisional tectonic setting， and the source rocks of magma are mainly metabasite and a little of metasedimentary， so that the rocks maybe inherit the geochemical characteristics of source rocks. There is metasomatism between magma and wall rock in the process of emplacement. The magmatic differentiation is ranked by granite and granite porphyry， subrhyolite porphyry， subdacite porphyry， quartz diorite and quartz diorite porphyrite in the ascending order. The Au content of rock from dyke is low， and that of metaacid rock increases because of the alteration. The intermediate rock of dyke （quartz diorite） provides thermal source and provenance for gold mineralization in Langchagou and Dongdonggou mining areas.

推荐访问:祁连 成矿 地球化学 河南 酸性