湖南黄沙坪多金属矿床成矿斑岩锆石U-Pb年代学及Hf同位素制约  

Zircon U-Pb geochronology and Hf isotopic compositions of ore-related granites from Huangshaping polymetallic deposit of Hunan Province

作　　者：艾昊[1,2] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵州贵阳550002 [2]中国科学院大学,北京100049

出　　处：《矿床地质》2013年第3期545-563,共19页Mineral Deposits

摘　　要：湖南黄沙坪铅锌钨钼多金属矿床位于南岭花岗岩带中段的北缘,是区内的典型矿床之一。该矿床与成矿关系密切的岩体为花岗斑岩、花斑岩和石英斑岩。LA-ICP-MS锆石U-Pb年代学显示,花岗斑岩的成岩年龄为(150·1±0·4)Ma,花斑岩的年龄为(150·2±0·4)Ma,石英斑岩的年龄为(155·3±0·7)Ma,表明岩体形成于晚侏罗世。锆石原位Hf同位素数据分析结果表明,含矿斑岩可能来源于中元古代古老基底的重熔,其中石英斑岩主要来源于地壳,花岗斑岩与花斑岩的形成伴有少量地幔物质的加入,是壳幔相互作用的产物。另外,由于花岗斑岩与花斑岩成岩年龄相近,Hf同位素组成相似,进一步印证了花斑岩和花岗斑岩是同源同期岩浆的产物。结合该矿床所处的区域大地构造背景以及成矿年龄,认为该矿床形成的动力学机制主要为中-晚侏罗世活动的Farallon-Izanagi洋岭和转换断层俯冲,导致华南内陆岩石圈全面伸展-减薄-地幔物质上涌,从而使得地壳物质部分熔融。U-Pb radioactive age and Hf isotope composition were systematically determined by means of LA-（MC）- ICP-MS for zircons from granophyre, granite porphyry and quartz-porphyry in the Huangshaping polymetallic deposit of Hunan Province, which is distributed in the west of the Qianlishan-Qitianling ore-forming belt and in the north of the Nanling Mountains granite belt. LA-ICP-MS analysis shows that the crystallization ages of ore- related porphyries are （150.1 ±0.4） Ma, （150.2 ±0.4） Ma and （155.3±0.7） Ma respectively, suggesting a middle Yanshanian emplacement. The in situ Hf isotope analysis reveals that these ore-related porphyries were derived from the mixed sources of the lower crust and the mantle. Based on this study in combination with the tectonic background, the authors hold that the formation process of Huangshaping ore-related porphyries might have been related to some mantle materials and formed under an extensional regime, which had to do with mid- dle Late Jurassic Farallon-Izanagi triple ridge subduction and transform faults subduction.

关 键 词：地球化学 黄沙坪 含矿斑岩 锆石U-Pb年龄 HF同位素 壳幔相互作用 洋岭 转换断层俯冲 

分 类 号：P618.4[天文地球—矿床学] P597[天文地球—地质学]