地质通报2017，Vol.36Issue(8)：1359-1368,10.
内蒙古翁牛特旗晚志留世二长花岗岩年代学及地球化学特征
Zircon U-Pb chronology and geochemical characteristics of Late Silurian monzogranite in Ongniud Bannar, Inner Mongolia
摘要
Abstract
The granite widely distributed in the Xiaoyingzi lead-zinc ore deposit of Ongniud Bannar,Inner Mongoha,consists of monzogranite as revealed by field geological survey and thin section identification.Zircon LA-ICP-MS U-Pb dating result shows that the monzogranite was formed in late Silurian (419.3 ± 9.2Ma) rather than in Mesozoic as previously held.The values of SiO2,K2O,K2O/Na2O,A12O3 are 74.41％～75.05％,3.05％～4.42％,0.70～1.11,13.22％～14.02％ respectively,the aluminum saturation indexes (A/CNK) range from 0.99 to 1.1,and the oxides of Fe,Mg,Ti are relatively low,which imphes that the monzogranite is I-type granite.The ratios of light and heavy rare elements (LREE/HREE) are between 10.61 and 16.61,and the (La/Yb)N ratios are between 12.52 and 27.44,suggesting obvious fractionation between hght and heavy rare elements.The values of δ Eu are 0.48～0.81with moderate negative europium anomaly.It is enriched in large ion hthophile elements (LILEs) Rb,Ba,U,K,depleted relatively in high field strength elements (HFSEs) Nb,Zr,Hf,and depleted relatively in Sr,Yb.All these geochemical characteristics show that the monzogranite is a product of volcanic arc on an active continental margin.The regional geological data reveal that the monzogranite was formed in the process of extinction of Bainaimiao island arc in the setting of subduction of the Paleo Asian Ocean to the North China craton.关键词
翁牛特旗/二长花岗岩/锆石U-Pb测年/地球化学/白乃庙岛弧Key words
Ongniud Bannar/monzogranite/zircon U-Pb dating/geochemical/Bainaimiao island arc分类
天文与地球科学引用本文复制引用
陈井胜,刘淼,李斌,李伟,李崴崴,杨帆,汪岩..内蒙古翁牛特旗晚志留世二长花岗岩年代学及地球化学特征[J].地质通报,2017,36(8):1359-1368,10.基金项目
中国地质调查局项目《内蒙古1∶5万敖汉旗、捣各郎营子、新地、铁匠营子幅区域地质矿产调查》(编号:12120113053400)、《辽宁1∶5万台吉、他拉皋、七道岭、十二台营子幅区域地质调查》(编号:DD20160048-05)、《内蒙古敖汉旗大黄花地区矿产地质调查》(编号:12120114055501) （编号:12120113053400）
