大兴安岭玻乌勒山地区玛尼吐组火山岩地球化学特征及成矿预测

Geochemistry Characteristics and Metallogenic Prognosis of the Volcanic Rocks from Manitu Formation of Bowule Mountain Area in Da Hinggan Mountain

大兴安岭玻乌勒山地区玛尼吐组火山岩样品SiO2平均质量分数为59.93%,属中性岩,过铝质、富碱,为一套高钾钙碱性和钙碱性中性火山岩系列。稀土元素总量较高（∑REE=（144.06~212.88）×10-6）,铕异常不明显（δEu值介于0.75~0.99之间）,轻重稀土分馏明显,分馏系数（La/Yb）N介于10.49~13.47之间。富集大离子亲石元素K、La、Ce、Rb、Ba和LREE,亏损高场强元素Ta、Nb和Ti等,火山岩样品主要来源于受俯冲流体交代的地幔源区,火山活动与古亚洲洋或蒙古—鄂霍茨克洋俯冲有关。区内地、物、化、遥异常特征显著,综合预测圈出成矿有利地段2处,具有寻找岩浆热液型多金属矿床的潜力。

The SiO2 average mass fraction of volcanic rock of Manitu For mation at Bowule Mountain of the Da Hinggan Mountain was around 59.93% belonging to intermediate rock with peraluminous and alkali-rich.Whilst,it was found that the volcanic rock exhibited the characteristics of high calcium alkaline potassium and calcium neutral alkaline volcanic rocks series.The content of rare earth elements was higher（∑REE=（144.06~212.88）×10-6）,and light and heavy rare earth fractionation was remarkable with fractionation factor（La/Yb）N ranging from 10.49 to 13.47.Moreover,enrichment of large ion lithophile elements was K,La,Ce,Rb,Ba,LREE,and loss of high field strength elements was Ta,Nb and Ti.Generally,the volcanic rock sample primarily came from the mantle source region controlled by subduction fluid,and the volcanic activity was related to the Paleo-Asian Ocean or Mongolia-Okhotsk oceanic subduction.In the study region,characters of geology,geophysics,geochemistry as well as remote sensing were significant anomaly,therefore,two mineralization favorable location were predicted after comprehensive investigation,and the target region had the potential of magmatic hydrothermal type polymetallic deposit.