【摘要】 大兴安岭北段克一河地区满克头鄂博组岩石主体岩性为流纹质、英安质火山岩,火山岩TAS图解中显示其为流纹岩。LA-ICP-MS锆石U-Pb定年结果显示,其形成于（139±2）Ma。火山岩多为高钾钙碱性系列,具有高SiO₂和全碱含量。稀土元素总量较低(ΣREE=137.34×10^-6191.18×10^-6),轻重稀土元素分馏明显（（La/Yb）_N=12.57²2.25）,具中等负Eu异常（δEu=0.40⁰.72）。富集大离子亲石元素Rb、Th、U和轻稀土元素,亏损高场强元素Nb、Ta、P、Ti。岩石Sr平均值为115×10^-6,Yb的平均值为1.70×10^-6,Y/Yb平均值为9.46,（Ho/Yb）_N平均值为1.04,且具负的Eu异常,暗示岩浆可能来源于加厚麻粒岩下地壳部分熔融,结合区域特征,推测该火山岩可能形成于蒙古—鄂霍茨克洋闭合碰撞造山所导致的地壳加厚环境。更多还原

【Abstract】 Petrographically,the volcanic rocks in Manketouebo Formation from keyihe area northern Da Hinggan Mountains are mainly composed of rhyolitic and dacitic volcanic rocks. The TAS diagram displays that they are rhyolite. LA-ICP-MS zircon U-Pb dating results show that they formed at 139 ± 2Ma. The volcanic rocks,which are rich in SiO₂ and alkalis,belong to high K Calc alkaline series. They are low in total rare earth elements(ΣREE = 137. 34 × 10^-6 191. 18 × 10^-6),whilst highly fractionated LREE from HREE（（La/Yb）_N= 12. 57 ²2. 25）,with moderately negative Eu anomalies（δEu = 0. 40 0. 72）. They are characterized by the enrichment of large ion lithophile elements（ such as Rb,Th and U） and LREE,and deplection of high field strength elements（ such as Nb,Ta,P,and Ti）. The average value of Sr is 115 × 10^-6,Yb is 1. 70 × 10^-6,Y/Yb is 9. 46,（Ho/Yb）_N is 1. 04,with negative Eu indicating that the magmas of these volcanic rocks are derived from partial melting of the granulite fracies of thickened lower crust. Integrating regional geology,it is suggested that the formation of the volcanic rocks were related to the crustal thickening during the closure of Mongol-Okhotsk Ocean.更多还原