南岭西段永和—太保花岗岩体的地球化学特征及其大地构造环境  

Geochemical characteristics of Yonghe—Taibao granitic pluton in western Nanling and its tectonic setting

作　　者：鲁学悟[1] 冯佐海[1] 郭俊刚[2] 杨锋[1] 

机构地区：[1]桂林工学院资源与环境工程系,广西桂林541004 [2]中国地质科学院河南郑州矿产综合利用研究所,郑州450006

出　　处：《世界地质》2008年第2期156-163,共8页World Geology

基　　金：广西自然科学基金项目(桂科自:0542001)

摘　　要：永和太保花岗岩体主要为钙碱性石英闪长岩和二长花岗岩。在超单元中从早期单元到晚期单元的岩浆演化序列中,岩石类型具有由钙碱性向偏碱性演化的特征;各单元岩石中微量元素含量随着元素相容性程度的升高而减少,整个超单元Ba、Nb、Sr强烈亏损,Rb、Th较为富集,显示出自早期单元到晚期单元部分熔融程度逐渐下降的演化趋势;岩体为轻稀土富集型,稀土元素分布曲线呈较弱的Eu负异常,轻稀土元素斜率较大,而重稀土较为平坦,具有挤压型构造环境的特点。结合永和太保花岗岩体的地球化学特征和南岭构造带的演化,确认该花岗岩体形成于加里东期扬子板块与华夏板块碰撞期,应力体制处于火山弧向同碰撞转换的挤压构造环境。The main components of the Yonghe-Taibao granitic pluton are calc-alkali quartz diorite and monzonite. In the sequence evolution of magma from early units to late units inside the super-unit, the style of rock has a character from the calc alkali to partial alkali in evolution. Trace elements of the rock in each unit reduce along with the increasing of the extent of elements compatibility. The contents of Ba, Nb and Sr are in depletion, and the contents of Rb and Th are enriched in the whole super-unit. It shows the declined trend about the extent of partial melting from early to late units. The granitic pluton has LREE enrichment ; the distributing curve of LREE assumes faintish Eu minus anomaly; the slope of LREE is larger, while the distributing curve of HREE is flat. It shows a character of extrusion tectonic environment. Combining the geochemical characteristics of Yonghe-Taibao granitic pluton and the evolvement of western Nanling tectonic belt, it is confirmed that the granitic pluton formed in the collision period of Yangtze Plate with the Chathaysia Plate in Caledonian. The stress system formed in compressional structure setting from volcanic arc to syn-collision conversion.

关 键 词：花岗岩体 地球化学 大地构造环境 永和——太保 南岭 

分 类 号：P595[天文地球—地球化学] P541[天文地球—地质学]