四川省牦牛坪稀土矿床成矿流体与碳酸岩-正长岩杂岩体成因联系评述

四川省牦牛坪稀土矿床是中国第二大原生轻稀土矿床 ,萤石是矿区主要脉石矿物之一 ,碳酸岩和正长岩在空间和时间上与稀土成矿存在密切联系 .在过去萤石和碳酸岩 -正长岩杂岩体地球化学研究的基础上 ,评述了稀土成矿流体与碳酸岩 正长岩杂岩体的成因联系 .矿区碳酸岩和正长岩具有相似的REE配分模式、( 87Sr 86Sr)0 ,( 14 3 Nd 14 4 Nd)0 ,2 0 6Pb 2 0 4Pb ,2 0 8Pb 2 0 4Pb同位素比值 ,位于地幔端元EM1和EM2之间 ,它们是造山环境的产物 .与稀土矿化共生的萤石显示不同的稀土配分模式 ,但是它们具有一致的Sr、Nd、Pb同位素比值 ,与碳酸岩和正长岩相似 .这些表明不同稀土特征的萤石来自相同的源区 ,稀土成矿流体与碳酸岩和正长岩岩浆存在密切联系 .

Genetic Relation of Ore-Forming Fluids and Carbonatite- Syenite Complex in Maoniuping REE Deposit, Sichuan Province, China:A Review

The Maoniuping REE deposit is the second largest primary light REE deposit in China. Fluorite is one of main gangue minerals in the orefield. Carbonatites and syenites are spatially and temporally associated with rare earth mineralization. Based on the previous geochemical studies of fluorite and carbonatite-syenite complex, we review the genetic relation of REE ore-forming fluids and carbonatite-syenite complex. It shows that carbonatites and syenites have similar REE distribution patterns, ( 87 Sr/ 86 Sr) 0, ( 143 Nd/ 144 Nd) 0, 206 Pb/ 204 Pb, 208 Pb/ 204 Pb ratios, and plot to the area between the mantle end-member EM1 and EM2. They were formed in orogenic setting. Fluorites associated with REE mineralization display different REE distribution patterns, but their Sr, Nd, Pb isotopic ratios are uniform, and are similar to those of carbonatites and syenites. This suggests that the different REE fluorites were products of the same source, and REE ore-forming fluids were related to carbonatite and syenite magmas.