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  

The study of zircon U-Pb ages and Hf isotopes of the intrusions of the Tangzhangzi Au(Mo) poly-metallic deposit and the geological implications

作　　者：贺文[1] 叶会寿[2] 曹晶[1] HE Wen;YE HuiShou;CAO Jing(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing 100037,China)

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]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

出　　处：《岩石学报》2018年第9期2703-2715,共13页Acta Petrologica Sinica

基　　金：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^(206)Pb/^(238)U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^(206)Pb/^(238)U加权平均年龄为166. 0±0. 9Ma;石英二长岩^(206)Pb/^(238)U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εHf(t)=-24. 4^-14. 1,tCDM=2104~2744Ma,表明岩石来源于古老地壳;辉绿岩εHf(t)=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。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 206 Pb/238 U ages of the granite porphyry are 161. 2 ± 0. 7 Ma and 173. 0 ± 5. 5 Ma,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 206） Pb/238 U ages of the diabase and the quartz monzonite are 166. 0 ± 0. 9 Ma and 176. 7 ± 3. 3 Ma,respectively. The molybdenite Re-Os age is 170 Ma according to early studies. Thus,the molybdenite mineralization shares an intimate relationship with the granite porphyry in time scale. According to the analytic data,theεHf（ t） and tCDMof the granite porphyry are-24. 4 ～-14. 1 and 2104 ～ 2744 Ma,which suggests the source of the intrusion is from the ancient crust; and the εHf（ t） and tCDM of diabase are 7. 8 ～ 10. 9 and 391 ～ 523 Ma,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 

分 类 号：P597.3[天文地球—地球化学] P618.2[天文地球—地质学]