广西姑婆山里松岩体及暗色包体的副矿物研究：含锡矿物特征与岩浆混合的矿物指示  

Accessory Minerals of Lisong Granite and Mafic Microgranular Enclaves in the Guposhan Area as Indicators of Magma Mixing

作　　者：王禄彬[1] 王汝成[1] 朱金初[1] 

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室,南京大学地球科学与工程学院,南京210093

出　　处：《高校地质学报》2011年第3期423-435,共13页Geological Journal of China Universities

基　　金：国家自然科学基金(40730423,40221301);中国地质调查局调查项目“南岭重要金属矿床成矿机理研究和找矿潜力预测”(1212010632100)联合资助

摘　　要：南岭中段以花山—姑婆山为起点,发育一条南西-北东向的燕山早期富钨锡A型花岗岩带,其中姑婆山岩体以其富含暗色微粒包体(MME)而闻名。为寻找岩浆混合的矿物学证据并探索基性岩浆与钨锡富集的关系,我们使用电子探针对姑婆山岩体花岗岩和暗色包体中的副矿物进行了系统的成分分析和对比。研究首次确认了暗色包体的铁镁矿物解理中含有岩浆成因的半自形锡石,同时在暗色包体中的锆石、榍石均指示了基性岩浆侵入后快速冷凝的过程。经过对比发现,花岗岩具有晚阶段榍石比早阶段榍石锡含量升高的特征,表明花岗岩中锡含量有随着岩浆的结晶分异作用上升的趋势;而暗色包体则显示早阶段榍石富锡、晚阶段榍石贫锡的特点,表明暗色包体中没有出现花岗岩中的充分分异演化过程。In the middle part of Nanling Range there is an early Yanshanian（Jurassic） A-type granite belt.The Guposhan granite batholith is well known by its mafic microgranular enclaves（MME） .In order to study the mineralogical evidence of magma mixing and the relationship between basic magma and tin-mineralization,we studied and compared the compositions of accessory minerals in the granite and MME by using elecron microprobe.We firstly confirmed the appearance of subhedral cassiterite of magmatic origin in cleavages of mafic minerals in MME.We also found that the zircon and titanite in MME show a rapid crystallization evidence after the basic magma emplacement.Particularly,consistent with the tin enrichment during the granite evolution,the late-stage titanite from the granite has higher tin contents than the early-stage one.However,the MME titanite has just the opposite evolution trend in the aspect of tin contents,which is the result of rapid crystallization.

关 键 词：姑婆山 暗色包体 锡石 榍石 锆石 岩浆混合 

分 类 号：P575.1[天文地球—矿物学]