内蒙古中东部两类花岗岩地质地球化学特征及成因意义  

GEOLOGICAL,GEOCHEMICAL CHARACTERISTICS AND GENETIC SIGNIFICANCE OF THE TWO TYPE GRANITES IN CENTRAL EASTERN INNER MOGOLIA

作　　者：王翔[1] 汪雅菲 何苗[1] 

机构地区：[1]安徽省地质调查院,安徽合肥230001 [2]合肥工业大学资源与环境工程学院,安徽合肥230009

出　　处：《矿物岩石》2014年第1期78-86,共9页Mineralogy and Petrology

基　　金：内蒙古地质勘查基金项目(NMKD-2008-21;NMKD2008-22)

摘　　要：内蒙古中东部沿凉城—土贵乌拉一线分布着大量强过铝质石榴石花岗岩及少量淡色花岗岩。石榴石花岗岩SiO2含量、A12O3/TiO2比值(小于100),Rb/Sr比值和Rb/Ba比值低,但CaO/Na2O比值高(大于0.3)。铕均为负异常,呈重稀土元素平坦、轻稀土元素中等富集的配分模式。淡色花岗岩SiO2含量高,A12O3/TiO2比值,Rb/Sr比值和Rb/Ba比值以及CaO/Na2O比值变化大。稀土元素复杂,正Eu异常、Eu异常不明显均发育。两类花岗岩微量元素特征总体相似,均显示出大离子亲石元素(K,Rb,Ba)相对富集,高场强元素(Nb,Ti,P)亏损。两类花岗岩不同的地球化学特征暗示了其源区成分及构造背景的差异。石榴石花岗岩的源区成分应为杂砂岩,熔融温度较高,来源较深;而淡色花岗岩的源区成分复杂,熔融压力较高。A large amount of strongly peralumious garnet granites,as well as a small amount of leucogranites occurred along the Liangcheng-Tuguiwula in the central eastern Inner Mogolia. Gar- net granites are characterized by lower SiO2 content, A1203/TiO2 ratio （ 100）, Rb/Sr ratio and Rb/Ba ratio, but higher CaO/Na20 ratio （ 0.3）, showing intermediate LREE enrichment and flat HREE patterns with negative Eu. Leucogranites are characterized by higher SiO2 content, A1203/TiO2 ratio,Rb/Sr ratio,Rh/Ba ratio and highly varied CaO/Na20 ratio. REE is complex： samples have positive, negative or normal Eu anomalies. The two types of granites have similar REE features,relatively enriched in LILE （such as K,Rb,Ba） and depleted in HSFE （such as Nb,Ti,P）. The inconsistency geochemical characteristics of the two type granites indicate their different source composition and tectonic setting. Garnet granites were sourced from greywacke with high melting temperature and deep source, but leucogranites source composition is complicat- ed with higher melting temperature.

关 键 词：强过铝质花岗岩 地球化学特征 构造背景 成因意义 内蒙古中东部 

分 类 号：P588.121[天文地球—岩石学]