现代地质2017，Vol.31Issue(2)：234-245,12.
内蒙古海拉尔北部八大关地区花岗岩的成岩时代、地球化学特征与成因
Age, Geochemistry and Petrogenesis of Granites from Badaguan Area in Northern Hailaer, Inner Mongolia
摘要
Abstract
The granite of Badaguan is mainly composed of syenogranite and monzonitic granite.Zircon U-Pb isotopic dating yields age of (212 + 1.7)-(226.7 + 1.6) Ma,indicating that they were formed in the Late Triassic.The granites are metaluminous with A/CNK ratios of 1.01-1.10 and differentiation index (DI) of 92.5-95.8.The granites are enriched in K,Rb and LREE,and depleted in Ba,Sr and HFSE,e.g.,Nb,Ta,P and Ti,with moderate Eu negative anomalies (δEu =0.51-0.71).The relatively low values of 10,000 Ga/A1 (average at 1.91),low zircon saturation temperature (average at 683 ℃) and other geochemical features suggest that the syenogranite and monzonitic granites in the study area are high differentiation I-type granites.The zircons in the granites show high values of εHf(t) (4.50-10.45) with two-stage Hf model ages of 0.59-0.97 Ga,suggesting that they are derived from the newly formed crust which is separated from Neo-Proterozoic depleted mantle.Combined with the U-Pb ages and other geochemical features,we proposed that the granite of Late Triassic formed in an active continental margin setting of the Mongolian-Okhotsk oceanic plate.关键词
花岗岩/锆石U-Pb定年/岩石成因/构造背景/八大关Key words
granite/zircon U-Pb dating/petrogenesis/tectonic setting/Badaguan分类
天文与地球科学引用本文复制引用
李研,王建,孙德有,陈德兵,韩志滨,崔家瑞..内蒙古海拉尔北部八大关地区花岗岩的成岩时代、地球化学特征与成因[J].现代地质,2017,31(2):234-245,12.基金项目
中国地质调查局项目(12120113053700). （12120113053700）
