内蒙古浩尧尔忽洞金矿区花岗岩岩石成因及构造意义

内蒙古浩尧尔忽洞金矿为低品位超大型中低温热液型金矿,矿区内海西期花岗岩发育.在矿区内可见黑云花岗岩、花岗细晶岩、花岗伟晶岩和花岗斑岩.花岗岩中SiO2含量65.36％ ～74.29％,Na2O/K2O比值0.43 ～1.01,平均值为0.75,花岗脉岩类属于高钾钙碱性,黑云花岗岩属于钾玄岩系列.哈克图解上各元素含量随SiO2变化呈线性规律明显,具Ⅰ型花岗岩特征.∑REE值在64.86×10-6～164.80×10-6范围内变化,总体上稀土含量较低.（La/Yb）N值为6.59 ～ 16.98,显示轻重稀土有明显的分馏.稀土元素蛛网图表现为右倾.黑云母花岗岩δEu平均值0.30,具低Sr低Y的特点.花岗脉岩类δEu平均值为0.65,表现出高Sr低Y的特点.花岗岩类具有中等到强的铕亏损.根据其地球化学特征,认为该岩体为同碰撞—后碰撞期形成的高钾钙碱性Ⅰ型花岗岩.

PETROGENESIS AND TECTONIC SIGNIFICANCE OF GRANITE IN THE HAOYAOERHUDONG GOLD DEPOSIT IN INNER MONGOLIA

The Haoyaoerhudong gold deposit is a mesothermal-epithermal deposit with ultra-large reserves and low grade. Hercynian granite was developed in the gold deposit. Granitite, granite aplite, granite pegmatite and granite-porphyry could be found in the Haoyaoerhudong gold deposit. The content of SiOz is from 65.36 to 73.07, and Na20/K20 is 0.43 to 1.01, with average value of 0.75. The granite dikes belong to high potassium calcium alkaline. The biotite granitization belongs to shoshonitic series. The variation tendency of other elements with following the content of SiO2 is obviously linear, and then it expresses the characters of I-type granite. The content of ∑ REE ranges from 64. 86×10-6 to 164. 80 ×10-6, which means low content of REE. The ratio of （La/Yb） ranges from 6.59 to 16.98, revealing apparent fractionation between LREE and HREE. The distribution curve of REE is right deviation. The δEu average value of biotite granitization is 0.30. The SEu average value of granite dikes is 0.65, indicating high and medium negative anomaly of Eu elememt. The biotite granitization showed low Sr and low Y characteristics. The granite dikes showed high Sr and low Y characteristics. According to the geochemical characteristics, the granitoids belong to collision-post collision environment I-type granite.