摘要
处于大兴安岭中北段额尔古纳地块的莫尔道嘎地区发育大量花岗质岩石,本文报道了该地区与斑岩钼矿有关的花岗斑岩、花岗闪长斑岩的锆石U-Pb年龄、Hf同位素特征。锆石的LA-ICPMSU-Pb年龄测试结果显示,太平川含矿斑岩体的形成年龄分别为183.6、193.7和199.1Ma,表明花岗岩主要形成于早侏罗世,可能代表蒙古-鄂霍茨克洋闭合阶段的岩浆侵入事件。锆石的Hf同位素研究显示,3件含矿斑岩样品锆石εHf(t)分别为-3.2～0.4、-3.1～1.8和-3.7～-1.1,两阶段模式年龄分别为1322、1276和1394Ma,岩浆起源于中新元古代增生的地壳物质。结合额尔古纳地块已有的花岗岩锆石Hf同位素资料,认为额尔古纳地块在中新元古代曾发生过地壳增生,增生的地壳物质于早侏罗世发生熔融,形成花岗质岩浆并成矿。太平川含矿斑岩具有与乌奴格吐山含矿斑岩相似的大地构造背景、岩石地球化学特征和岩石年龄,推测太平川斑岩钼矿的成矿年代大致在195～180Ma。
Granitoids are developed in Mordaoga area of Eerguna block,northern-central Da Hinggan Mountains.On the basis of granite batholith,the Taipingchuan porphyry Mo-Cu deposit was discovered.Metallogenic host rocks are granite porphyry,granodiorite porphyry and granodiorite,which are characterized by high-K calc-alkalic series,adakite magmatic affinity and slightly negative anomalies of Eu.In order to study the ages and sources of the mineralized porphyry and the relationship between the intrusive body and the Taipingchuan porphyry Mo-Cu deposit,zircon this paper reports U-Pb ages and Hf isotope characteristics of granite porphyry and granodiorite porphyry related to the porphyry molybdenite deposit.LA-ICP-MS zircon U-Pb dating results reveal that the Taipingchuan mineralized porphyries have ages of 183.6 Ma,193.7 Ma and 199.1 Ma,suggesting that granitoids were formed in early Jurassic and might stand for magmatic intrusion activities related to the closure of Mongolia-Okhotsk Ocean.Zircon Hf isotope characteristics indicate that three mineralized porphyry samples have zircon εHf（t）values ranging from-3.2 to 0.4,-3.1 to 1.8 and-3.7 to-1.1,with model ages of 1 322 Ma,1 276 Ma and 1 394 Ma respectively,implying that magma originated from the crustal growth and accretion of Meso-Neoproterozoic.Combined with previous zircon Hf isotope data obtained from Eerguna block,the authors hold that crustal growth and accretion took place in Meso-Neoproterozoic,and partial melting occurred in early Jurassic and resulted in the formation of granitic magma and mineralization in Eerguna block.The Taipingchuan mineralized porphyries are comparable with Wunugetushan porphyry in that they have similar tectonic setting,geochemical characteristics and ages of the host porphyry.It is thus inferred that the ore-forming age of the Taipingchuan porphyry molybdenite deposit should be 195 to 180 Ma. 更多还原
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2010年第6期796-810,共15页
Acta Petrologica et Mineralogica
基金
国家科技支撑计划资助项目(2006BAB01A10)
国土资源调查基础性公益性地质调查项目(1212010781041)
中央地质勘查基金项目(2009151014)
关键词
太平川斑岩钼矿
锆石U-PB年龄
HF同位素
大兴安岭中北段
Taipingchuan porphyry molybdenite deposit
zircon U-Pb age
Hf isotope
northern-central Da Hinggan Mountains
