铜陵地区中酸性侵入岩锆石群结晶特征及成因  

Crystalization Characteristics and Genesis of the Zircon Group in Intermediate-Acid Intrusive Rocks of Tongling Area

作　　者：吴才来[1] 周珣若[1] 黄许陈[1] 张成火[1] 

机构地区：[1]中国地质大学,安徽省地矿局321地质队

出　　处：《岩石矿物学杂志》1994年第3期239-247,共9页Acta Petrologica et Mineralogica

基　　金：高等学校博士学科点专项科研基金及国家科技攻关项目

摘　　要：铜陵地区中生代中酸性侵入岩锆石的晶面统计分布，呈不对称正态和不对称对数正态的单峰、双峰和双曲线型；同时，同一岩体中出现不同端员锆石群晶型的共生，它们反映岩浆混合作用的存在。由锆石晶面统计分析可以求得不同类型岩方开始与终止结晶的温度：辉石二长闪长岩，９００－７００℃；石英二长闪长岩，８５０－６５０℃；花岗闪长岩，８００－６５０℃；花岗闪长斑岩，６５０－６００℃。岩浆物理学研究表明，高粘度的花岗闪长斑岩岩浆有利于钻石（３１１）晶面发育，低粘度的辉石二长闪长岩岩浆有利于钻石（１１１）晶面发育。锆石群的平均碱度指数和平均温度指数相关图解表明，本区中酸性侵入岩岩浆的物质来源为幔壳混源型。The corrosion holes on the crvstal faces of zircon from the Mesozoic inter-mediate-acid intrusive rocks of Tongling area resulted from the rising tem-perature caused by heat or latent heat of crystallization arising from upward intrusion of deep magma after the crystallization of zircon. Statistics of zircon crystal faces show asymmetric normal and asymmetric lognormal distribution patterns noted for unimodal,bimodal and hyperbolic forms,and there exists the association of different crystal forms of zircon which belong to different end-member zircon groups in the same intrusive body,suggesting the hybri-dization of different genetic types of magma. The crystallization temperatures of different types of rocks as shown by statistics of zircon crystal faces are in the range of 900-700℃ for pyroxene monzodiorite,850-650℃ for quartz monzodiorite,800-650℃ for granodiorite,and 650-600℃ for granodiorite porphyry respectively,Studies of magma physics have shown that the compo-sition,crystalline state and temperature of magma decided the viscosity of magma, which,in turn,conditioned the development of different zircon crys-tal faces in intermediate-acid intrusive rocks.For example,the high viscosity of granodiorite was favorable for the development of(311) face while the low viscosity of pyroxene monzodiorite for that of(111)face.The correlogram bettween the average alkalinity index and the average temperature index of zircon demonstrates that magmatic materials responsible for the intermediate-acid intrusive rocks in the area were derived from the mantle-crust mixtures.

关 键 词：中酸性 侵入岩 锆石群 结晶 成因 

分 类 号：P588.12[天文地球—岩石学]