摘要
黄毛土沟南岩体位于北山,属西部额尔齐斯增生楔火山岩带活动大陆边缘体系,岩性主要为花岗闪长岩,产于下石炭统红柳园组。本文通过年代学研究,获得其LA-ICP-MS锆石U-Pb年龄为418.6±2.8Ma,岩石形成为晚志留世。岩石地球化学显示,稀土元素以轻稀土强烈富集、Eu亏损不明显为特征,且富集大离子亲石元素Rb和高场强元素Th、Hf,表明该岩体属同熔型成因,其岩浆均来源于下地壳或上地幔,在其上侵过程中混染了壳源物质,形成同熔岩浆,使其具壳幔混合特性,这是岛弧环境花岗岩所独有的特征,是北山早古生代洋盆向南俯冲形成的弧后盆地俯冲消减的产物。
The Huang maogounan pluton,located in Beishan,belongs to the active continental margin system of the western Irtysh accretive wedge volcanic belt.The lithology is mainly granodiorite and occurs in the Lower Carboniferous Hongliuyuan Formation.The LA-ICP-MS zircon U-Pb age is 418.6+2.8Ma,indicating that the rock was formed in the Late Silurian epoch.Petrogeochemistry shows that the rare element is characterized by strong enrichment of light rare earth and weakly Eu anomalies,enriched in Rb,Th and Hf,indicating the syntectite genesis.The magma originated from the lower crust or upper mantle,and mixed with crust-source material in the uptrusion process to form the syntectic magma,showing the characteristics of crust-mantle mixing,and the feature of island arc granite.Huangmaogou pluton is the product of subduction of the back-arc basin formed by the south subduction of the early Paleozoic ocean basin in Beishan.
作者
高志杰
GAO Zhi-jie(Gansu Geological Survey Institute,Lanzhou 730000)
出处
《四川地质学报》
2023年第2期347-351,362,共6页
Acta Geologica Sichuan
基金
中国地质调查局甘肃北山1:5万区域地质调查项目(K47E021015、K47E021016、K47E022015)。
作者简介
高志杰(1984-),男,汉族,甘肃景泰人,工程师,主要从事区域地质矿产调查。
