摘要
霍吉河钼矿是小兴安岭地区于近年发现的大型斑岩型钼矿床。本文在对矿化特征分析的基础上,采用LAICP-M S锆石U-Pb技术对霍吉河成矿花岗质杂岩测年,获得中细粒花岗闪长岩和斑状花岗岩成岩年龄分别为18110?119 M a(n=15,M SWD=417)和19316?114 M a(n=25,M SW D=213)。通过辉钼矿R-e Os同位素分析,获得等值线年龄17613?511 Ma(n=5,M SWD=113)和加权平均年龄为18112?118 M a(n=5,M SWD=113)。两种方法获得的年龄大致相近,表明成岩与成矿于同一系统形成,成岩大致始于19316?114 M a,成矿于岩浆期后18112?118 M a。霍吉河钼矿成岩成矿年龄与乌奴格吐山铜钼矿、兰家沟钼矿和杨家杖子钼矿等矿床辉钼矿Re-Os同位素年龄相近,表明中国东北地区广泛存在早侏罗世岩浆成矿作用。微量元素和同位素显示,霍吉河花岗闪长岩和斑状花岗岩属A型花岗岩,形成于地壳挤压向拉伸转换的构造环境,成矿物质主要来自岩浆。
The Huojihe molybdenum deposit in the Xiao Hinggan metallogenic belt is a large porphyry deposit discovered in recent years. Based on the analysis of characteristics of mineralization, the authors conducted the LA-ICP-MS U-Pb dating of zircon from metallogenic granitic complex and Re-Os dating of molybdenite in Huo- jihe area. LA-ICP-MS U-Pb ages of zircons from medium-fine grained granodiorite and porphyritic granite are 181.0 ± 1.9 Ma （ n = 15, MSWD = 4.7） and 193.6 ± 1.4 Ma respectively, The molybdenite Re-Os isochrones age is 176.3 ± 5.1 ]Via （ n = 6, MSWD = 1.3）, with weighted average model age of 181.2±1.8 Ma. The ages from the two methods are close to each other, suggesting that they might have been formed in the same petroge- netic ore-forming system. The petrogenesis started at 193.6 -＋ 1.4 Ma and the mineralization in the magma oc- curred at 181.2 ＋ 1.8 Ma. The ore-forming age of the Huojihe molybdenum deposit is close to the molybdenite Re-Os isochron age of the Wunugetu Cu-Mo deposit and the Lanjiagou and Yangjiazhangzi molybdenum deposits. There existed an early Jurassic magmatic-mineralization event in Northeast China, Trace dement and isotope show that granodiorite and porphyritic granite in Huojihe belong to A-type granites. Petrogenesis and mineralization of Huojihe molybdenum deposit were related to changes of the tectonic environment from crust extruding to ex- tending. The mineral murce was derived from magma.
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2013年第5期733-750,共18页
Acta Petrologica et Mineralogica
基金
中国地质调查局国土资源大调查项目(1212010010845)
