姚五沟岩株地球化学特征及构造环境

姚五沟岩株位于内蒙古太仆寺旗境内,其岩性为花岗斑岩,其形态近似为一南北向椭球形,岩石具斑状结构和块状构造,其主要矿物成分为石英、钾长石、斜长石,次要矿物成分为黑云母.化学成分中,SiO_2平均含量值略低于中国花岗岩的平均值,富钾贫钠,FeO 和CaO含量极低,铝过饱和;岩体分异指数极高,稀土元素总量极高,轻稀土含量高于重稀土含量,具极弱的稀铕负异常.其成因应属S型花岗岩,其构造环境为大陆碰撞花岗岩.

GEOCHEMICAL CHARACTERISTICS AND TECTONIC ENVIRONMENT OF YAOWUGOU GRANITE PORPHYRY

Located in Taibus Banner of Inner Mongolia, the Yaowugou stock is a granite porphyry assuming a north-south spheroidal form. The rock has porphyritic texture, and the minerals are mainly quartz, plagioclase, plagioclase and subordinately biotite. As for chemical components, SiO_2 is slightly lower than the average SiO_2 value of granites, potassium is rich but sodium is poor, FeO and CaO are very low, and aluminum is oversaturated. The rock has high differentiation index and high total REE. The values of LREE are by far higher than the values of HREE, with a very weak negative Eu anomaly. All this indicates that the Yaowugou stock should be genetically a S-type granite.