辽宁本溪地区关门山岩体地球化学特征及构造环境

对辽宁本溪地区关门山岩体正长花岗岩主量元素特征的研究表明,其属于高钾钙碱性系列.球粒陨石标准化稀土元素分配模式显示LREE相对富集,HREE相对亏损,具有中等亏损的负Eu异常,模式图总体呈"海鸥式"分布.微量元素蛛网图显示富集大离子亲石元素(LILE)Rb、Th、K,贫高场强元素(HFSE)Ta、P、Ti.正长花岗岩微量元素组成表明本区的花岗岩岩浆形成压力小于1.0 GPa,源区物质存在于30~40 km的地壳深处,属于减薄型地壳.正长花岗岩的形成时代为早白垩世,当时辽东陆块处于陆内伸展环境.

GEOCHEMISTRY AND TECTONIC ENVIRONMENT OF THE GUANMENSHNA INTRUSIVE ROCKS IN BENXI AREA,LIAONING PROVINCE

The major elements and trace elements of the Guanmenshan syenogranite in Benxi area, Liaoning Province are studied. The characteristics of the major elements show that the syenogranite belongs to high-K calcium-alkaline series. The seagull-shaped chondrite-normalized REE distribution patterns suggest enrichment of LREEs and depletion of HREEs, with medium negative Eu anomalies. Trace element spider diagram shows that the rocks are enriched in large ion lithophile elements （LILEs, such as Rb, Th and K）, whereas depleted in high field strength elements （HFSEs, such as Ta, P and Ti）. The composition of trace elements in syenogranite indicates that the formation pressure of granite magma is less than 1.0 GPa, and the source materials exist in the depth of 30-40 km of the earth crust, belonging to thinned crust. The syeogranite was formed in the Early Cretaceous when the Liaodong block was in intracontinental extension environment.