南岭西段金鸡岭复式花岗岩基地质及岩浆动力

对南岭西段金鸡岭复式花岩岩基进行的Rb-Sr同位素定年研究，确定Ⅰ阶段黑云母二长花岗岩的等时线年龄为169．5MaⅡ、Ⅲ阶段黑云母花岗岩和二云母花岗岩为150．7Ma，其ISr值分别为0．7163和0．7206，表明该复式岩基属燕山早期。金鸡岭复式花岗岩基岩石属钙碱性系列，从Ⅰ阶段到Ⅱ、Ⅲ阶段表现出有规律的演化特征：岩石由准铝质（Ⅰ），演化为过铝质（Ⅱ）和强过铝质（Ⅲ）；钾长石有序度由0．33（Ⅰ），增高到0．69（Ⅱ）和0．80（Ⅲ）；斜长石油An37（Ⅰ）降低到An26（Ⅱ）和An7(Ⅲ)；黑云母由铁质黑云母（Ⅰ）向铁叶云母（Ⅱ）和铁白云母（Ⅲ）方向演化；氧化物（SiO2,Al2O3,TFeO,MgO,TiO2,CaO)-DI图解上呈良好的线性演化关系；成岩温度逐阶段降低，由745℃（Ⅰ）降低到673℃（Ⅱ）至505℃（Ⅲ）。采用地质地球化学方法估算出金鸡岭岩基的侵位深度约为6．3km，成岩压力为180MPa，具中深成相特征，属S型花岗岩并形成于华南板块内部的碰撞构造环境。

Geology and Magma-Dynamical Features of Jingjiling Composite Granitic Batholithin the Western Nanling Region

Jinjling composite batholithin the west Nanling Region consis ts of three granite bodies with different ages of intrusion: I stage,amphibole-bearing bi otite adamellite; Ⅱ stage,biotit e granite; Ⅲ stage,two-mica granite.The ages and initial strontium ratios for the Ⅰ stage and Ⅱ stage granites by Rb-Sr whole-rock isochron method are 169 .5Ma and 0.7163,and 150.7Ma and 0.7206,respectively.It indicates that they are intru sions of early Yanshanian period.Granites of the Jinjiling batholith belong t o calc-alkaline rock series and show a general evolution trend from Ⅰ stage a d amellite,to Ⅱ stage granite and Ⅲ stage bimicaceous granite as follows: aluminium saturation index increases from metaluminous (Ⅰ) to peraluminous ( Ⅱ) and highly peral uminous; ordering degree of K-feldspar increases from 0.33(Ⅰ) to 0.69 (Ⅱ) an d 0.80(Ⅲ); An of plagiaclase decreases from 37(Ⅰ) to 26(Ⅱ) and 7(Ⅲ); chemica l composition of biotite varies from Fe-biotite(Ⅰ),to lepidomelane(Ⅱ) an d Fe-mica(Ⅲ); oxides (SiO2,Al2O3,TFe,MgO,TiO,CaO)versus DI diagrams sh ow a linearevolution features; rock-forming temperatures gradually drop down f rom 745 ℃(Ⅰ) to 673℃(Ⅱ) and 505℃(Ⅲ).By means of geochemical and geobarometric met hod s,it is estimated that the depth of emplacement for Jinjiling batholith was abo ut 6 .5km,and the rock-forming pressure was about 180MPa.Jinjiling c omposite granitic batholith belongs to S-type granitoids,forming in coll ision orogeny environment.