地质学报2018，Vol.92Issue(1)：107-124,18.
内蒙古东乌旗达亚纳钨-钼矿成岩成矿时代及其岩体地球化学研究
Geochronology and Geochemical Characteristic of Biotite Granite of the Dayana W-Mo Deposit in Dong Ujimqin Banner,Inner Mongolia, and Its Geological Significance
摘要
Abstract
The Dayana W-Mo deposit in Dong Ujimqin Banner of Inner Mongolia is a quartz-vein type deposit newly discovered in the mid-western part of Mongolia-Hinggan Orogen.It is typical of quartz vein-type wolframite-molybdenum ore deposit,with wolframite-bearing quartz veins occurring as nearly vertical,parallel quartz veins (75°) within biotite granite or in outer contact zone between rock mass and strata.Main mineralization and alteration includes greisenization,potash feldspathization,albitization,and silicification,etc.A large amount of molybdenite formed accompanied with wolframite and occurs on both sides of wolframite-bearing quartz veins or in quartz veins.Based on detailed analysis of deposit geological feature,this study carried out LA-ICP-MS zircon U-Pb dating and geochemistry analysis for ore-forming rock mass-biotite granite.The U-Pb dating yielded two similar ages (134±1 Ma (MSWD=0.41) and 135 ±1 Ma (MSWD=0.52)) for tow biotite granite samples.Major and trace element geochemistry shows that the biotite granite is characterized by high SiO2 and K2 O contents,a "right-inclined" shape of the chondrite normalized REE patterns,enrichment of large ion lithophile elements (LILEs),and depletion of high field strength elements (HFSEs) such as Nb,P,Ba.The biotite granite is high-K calc-alkaline,has a strong negative Eu anomaly (Eu/Eu* =0.22～0.45),low P2O5 content,A/CNK value close to 1.These characteristics define the Dayana biotite granite as a highly fractionated granite.The in situ zircon Hf isotopic data show that the 176 Hf/177 Hf isotopic ratio of the zircons from the biotite granite is 0.28295 ～0.28302,with εHf(t) values ranging from (+6.4) to (+8.8).It indicates that the source region of the biotite granite magma was derived from the juvenile Lower crust.The Re-Os isotopic analysis of seven molybdenite separates from the deposit yielded an isochron age of 133 ± 3 Ma (MSWD=2.2),suggesting that the biotite granite and mineralization have the identical age within error range,are probably genetically related,and closely related to the cretaceous metallogenic events in North China.关键词
内蒙古东乌旗/达亚纳/黑钨矿/辉钼矿/年代学/石英脉型/黑云母花岗岩Key words
Dong Ujimqin/Inner Mongolia/wolframite/molybdenite/geochronology/quartz vein/biotite granite/LA-ICP-MS/in situ zircon Hf/Re-Os引用本文复制引用
向安平,陈毓川,佘宏全,李光明,李应栩..内蒙古东乌旗达亚纳钨-钼矿成岩成矿时代及其岩体地球化学研究[J].地质学报,2018,92(1):107-124,18.基金项目
本文为国家基础科研项目(编号2013CB429803)、综合地质调查项目(编号121201010000150014)联合资助成果. （编号2013CB429803）
