南岭东段与稀土矿有关岩浆岩的成矿专属性特征

Metallogenic Specialization of Rare Earth Mineralized Igneous Rocks in the Eastern Nanling Region

南岭是我国特有的离子吸附型稀土矿集区,区内出露的大面积岩浆岩为矿床的形成提供了成矿物质来源。近十几年来,积累了一批与稀土矿有关岩浆岩的同位素年代学、矿物学、岩石地球化学资料,为其成矿专属性研究提供了新的依据。本文通过对南岭东部成矿花岗岩类系统的年代学、矿物学及地球化学特征研究,以及与非成矿花岗岩的对比,认为：（1）成矿花岗岩类的锆石U-Pb年龄主要分布在150~461 Ma,形成于加里东期、印支期和燕山期；（2）成矿花岗岩中含一定量易风化的稀土载体矿物,尤其是可见稀土独立矿物。稀土载体矿物的含量和配分类型决定成矿母岩中稀土含量和配分类型；（3）基性、中性、酸性及碱性岩类均能成为良好的成矿母岩,但钾长花岗岩、黑云母花岗岩、二长花岗岩为主要的成矿岩石类型；（4）成矿花岗岩中,碱含量偏高,且钾含量大于钠,稀土含量也普遍偏高。重稀土型成矿花岗岩比轻稀土型成矿花岗岩更加富集重稀土,也易富集Rb、Pb等元素,更亏损Ba、Zr等元素。南岭地区具有得天独厚的稀土成矿条件,仍具有较大的找矿潜力。

The Nanling region is famous for the ion-adsorption type rare earth ore resources in the world. The widespread igneous rocks in the area provide ore-forming materials for the formation of the rare earth ores. In the last decade, we compiled a huge mass of data of isotope chronology, mineralogy, geochemistry of rare earth ore-bearing igneous rocks which enable us to carry out the research of metallogenetic specialization. This paper studied on isotope chronology, mineralogy, geochemistry of rare earth ore-bearing igneous rocks in the eastern Nanling region, and compared the difference between the ore-bearing and barren granites. Finally, four conclusions can be drawn：（1） Rare earth ore-bearing granites have zircon U-Pb ages ranging from 461 to 150 Ma, formed in the Caledonian, Indosinian and Yanshanian periods. （2） Rare earth ore-bearing granites contain REE-bearing minerals which vulnerable to weathering, especially the independent REE minerals. Thus, REE contents and patterns of ore-bearing granites are controlled by the characteristics of the REE carriers. （3） The types of rare earth ore-bearing rocks include basic, neutral, acid, and alkaline rocks, however, moyite, biotite granite, and adamellite are more important. （4） Ore-bearing granites have high alkali （K2O〉Na2O） and REE contents. Relative to LREE-bearing granites, HREE-bearing granites are more enriched in heavy rare earth, Rb, Pb and more depleted in Ba and Zr. With the good metallogenic conditions, the Nanling region still has great prospecting potential of ion-adsorption type rare earth resources.