大兴安岭中段驼峰岭天池大黑沟期玄武岩地质、地球化学特征及构造背景

Geological,geochemical characteristics and tectonic setting of Daheigou period basalt in Tuofengling Tianchi,the middle section of Greater Khingan Mountains

研究区驼峰岭天池出露的上更新世大黑沟期火山岩为一套基性火山岩,通过对驼峰岭天池地质调查,确定该火山活动分为二次火山喷发事件,形成熔岩台地、火山锥、椅子状山及带水低平火口湖不同地貌,岩相依次构成火山爆发相(E)-火山溢流相(EFF)-火山颈相(VNF)。岩石地球化学特征表明该期玄武岩具有贫硅、锰,富铝、铁特征,利用里特曼-戈蒂尼图解进行构造环境判别,说明了该期玄武岩为大陆裂谷性质偏碱性拉斑玄武岩,玄武岩全岩K-Ar法年龄分别为(0.92±2)Ma和1 Ma,其火山活动形成的地质时代为第四纪上更新世,研究成果为大黑沟期玄武岩成因及构造背景研究提供了参考依据。对阿尔山国家森林公园、国家地质公园旅游资源开发、建设及保护奠定了地质学基础。

The Daheigou period of Upper Pleistocene volcanic rocks exposed in Tuofengling Tianchi in the study area are a set of basic volcanic rocks.Through the geological survey of Tuofengling Tianchi,it is determined that the volcanic activity is divided into two volcanic eruptions,forming different landforms of lava platform,volcanic cone,chair-shaped mountain and low level crater lake with water.The lithofacies in turn constitute volcanic eruption facies(E)-volcanic overflow facies(EFF)-volcanic neck facies(VNF).The rock geochemical characteristics show that the basalts in this period are poor in silicon and manganese,rich in aluminum and iron.By using the Rittman-Gottini diagram to distinguish the tectonic environment,it is shown that the basalts in this period are continental rift alkaline tholeiite basalts.The data show that the K-Ar ages of the whole basalt are(0.92±2)Ma and 1Ma respectively.The geological age of the volcanic activity is the Quaternary Upper Pleistocene,and the research results provide a reference for the study of the genesis and tectonic background of Daheigou basalt.The geological foundation has been laid for the development,construction and protection of tourism resources in Arshan National Forest Park and National Geopark.