诺敏火山群钾质火山岩特征与成因

Characteristics and genesis of potassic volcanic rocks from Nuomin volcanic groups

为了进一步研究诺敏火山群钾质火山岩的特征及其形成的古构造环境,对该区钾质火山岩样品,做了硅酸盐、同位素与微量元素分析。数据分析结果表明,诺敏火山群钾质火山岩主要岩性为橄榄玄武岩、白榴玄武岩、玄武质浮岩。钾质火山岩是由于地幔物质上涌,底侵于陆壳的底部,造成下地壳少量物质与地幔物质发生混溶作用,以及钾质交代作用而形成的,是大陆板块内部裂谷期岩石圈伸展作用的产物。该套火山岩成因与许多重要的浅成低温热液金矿床及斑岩型铜(金)矿床具有密切联系。该研究对恢复古构造环境,了解地幔组成具有重要意义。

The endeavor to depen the study on the features of patassic volcanic rocks and its formation environment in Nuomin volcano group results in the analysis of silicate, isotope and microelement on the samples derived from the patassic volcanic rocks. The result shows that Nuomin patassic volcanic rocks consist mainly of olivine basalt, leucite basalt and basaltic pumice. The upwelling mantle, invading to the bottom of crust, leading to potassic metasomatism and mixture of mantle and continental crust substance, produced the potassic volcanic rocks, and its producing are the result of the extension stage of the rift of continental intraplate. The cause of the formation of the rocks are also related to lots of shallow-created low-temperature hot liquid gold deposits and the formation of porphyry-type copper deposits. The study on the patassic volcanic rocks is of significance to reviewing the old formation environment, and the construction of mantle.