论文部分内容阅读
川西冕宁-德昌稀土成矿带是中国最重要的稀土成矿带之一,所有稀土矿床均与碳酸岩-正长岩杂岩体有关。前人研究表明,牦牛坪、木落寨和里庄碳酸岩-碱性杂岩体成岩年龄与其相应矿床的成矿年龄基本一致,而大陆槽正长岩年龄与REE 矿床的成矿年龄相差甚远。本文对大陆槽碳酸岩、英碱正长岩进行了 SHRIMP U-Pb 锆石年代学和 LA-MC-ICPMS 锆石Hf 同位索原位测量,它们的形成年龄分别为12.99±0.94Ma、14.53±0.31Ma,表明两者是同时形成的,且与其成矿年龄基本一致。碳酸岩和正长岩的ε_(Hf)(t)值、Hf 模式年龄与它们的ε_(Nd)(t)值、Nd 模式年龄所展现出来的特征一致,说明在其形成过程中有地壳物质的加入。
The Mianning-Dechang Rare Earth metallogenic belt in western Sichuan is one of the most important rare-earth metallogenic belts in China. All rare-earth deposits are related to carbonate-syenite complex. Previous studies have shown that the diagenetic ages of the Maoniuping, Muluozhai and Lizhuang carbonate-alkaline complexes are basically the same as the mineralization ages of their corresponding deposits, while the age of the continental trough is a long way from that of the REE deposit . In this paper, SHRIMP U-Pb zircon chronology and LA-MC-ICPMS zircon Hf isotope measurements were performed on continental trough carbonate and alkali-alkali syenite. Their formation ages were 12.99 ± 0.94Ma and 14.53 ± 0.31Ma, indicating that the two are formed at the same time and are basically consistent with their metallogenic age. The values of ε_ (Hf) (t) and Hf ages of carbonatite and syenite are consistent with those of their Nd_ (t) values and Nd ages, indicating that the crustal material Join.