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贺文,叶会寿,曹晶. 2018. 冀东唐杖子金(钼)多金属矿区侵入岩体锆石U-Pb年龄、Hf同位素特征及其地质意义. 岩石学报, 34(9): 2703-2715
冀东唐杖子金(钼)多金属矿区侵入岩体锆石U-Pb年龄、Hf同位素特征及其地质意义
作者单位E-mail
贺文 中国地质大学地球科学与资源学院, 北京 100083  
叶会寿 中国地质科学院矿产资源研究所, 国土资源部成矿作用与资源评价重点开放实验室, 北京 100037 yehuishou@163.com 
曹晶 中国地质大学地球科学与资源学院, 北京 100083  
基金项目:本文受国家重点研发计划(2017YFC0601403)资助.
摘要:
      唐杖子金(钼)多金属矿床位于冀东地区,矿区内出露的主要岩性为花岗斑岩、石英二长岩和辉绿岩。本文对矿区主要的侵入岩进行锆石U-Pb定年和Hf同位素研究,探讨成岩-成矿相互关系,获取岩体源区信息。锆石U-Pb定年结果显示,花岗斑岩206Pb/238U加权平均年龄分别是161.2±0.7Ma、173.0±5.5Ma,结合锆石特征、锆石U-Pb定年结果,推测该矿区存在两期花岗质岩浆侵位;辉绿岩206Pb/238U加权平均年龄为166.0±0.9Ma;石英二长岩206Pb/238U加权平均年龄为176.7±3.3Ma。唐杖子矿区辉钼矿Re-Os年龄为170Ma,从时间尺度上来看辉钼矿化与早期花岗斑岩(173Ma)关系密切。花岗斑岩εHft)=-24.4~-14.1,tDMC=2104~2744Ma,表明岩石来源于古老地壳;辉绿岩εHft)=7.8~10.9,tDM=391~523Ma,表明岩石源区为古生代的亏损地幔。唐杖子花岗斑岩和辉绿岩都形成于中侏罗世,成岩时代相近,但源区明显不同,表明冀东地区在中侏罗世既存在下地壳的部分熔融的过程(形成了唐杖子花岗斑岩),又存在亏损地幔物质上涌侵入地壳的过程(形成了唐杖子辉绿岩),暗示了华北克拉通东缘在中侏罗世经历了一次岩石圈减薄的过程。
英文摘要:
      The Tangzhangzi Au (Mo) poly-metallic deposit is located at East Hebei Province. The granite porphyry, quartz monzonite and diabase dominantly outcrop in the mine area. Researches of zircon U-Pb dating and Hf isotopes of the intrusive bodies are reported in this paper, which can be used to understand the relationship of the diagenesis and mineralization and acquire the information of source rocks. The weighted mean 206Pb/238U ages of the granite porphyry are 161.2±0.7Ma and 173.0±5.5Ma, respectively. We suggest there are two intrusive activities of granitic magma taking account of the characteristics of zircons, the zircon U-Pb dating results and the previous dating results. The weighted mean 206Pb/238U ages of the diabase and the quartz monzonite are 166.0±0.9Ma and 176.7±3.3Ma, respectively. The molybdenite Re-Os age is 170Ma according to early studies. Thus, the molybdenite mineralization shares an intimate relationship with the granite porphyry in time scale. According to the analytic data, the εHf(t) and tDMC of the granite porphyry are -24.4~-14.1 and 2104~2744Ma, which suggests the source of the intrusion is from the ancient crust; and the εHf(t) and tDMC of diabase are 7.8~10.9 and 391~523Ma, which suggests the intrusion was derived from depleted mantle in Paleozoic. The granite and diabase were formed in middle Jurassic and the results of zircon U-Pb dating exhibit a similar diagenetic age of the intrusions while the magma sources are quite different, which suggests that partial melting of the lower crust and the upwelling of depleted mantle took place in Middle Jurassic in Jidong area. And all this information indicates lithospheric thinning took place in the eastern NCC during Middle Jurassic.
关键词:锆石U-Pb定年  Hf同位素组成  岩石圈减薄  唐杖子金(钼)多金属矿床
投稿时间:2017-10-26  修订日期:2018-02-03
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