华南低温热液脉状萤石矿床稀土元素地球化学特征

REE GEOCHEMICAL CHARACTERISTICS OF EPITHERMAL VEIN FLUORITE DEPOSITS IN SOUTH CHINA

华南地区广东、福建、江西等省内的萤石矿床，多数处于花岗岩的内外接触带上。成矿方式为脉状充填（交代）式。成矿严格受中国东部北东向构造控制。近百个样品稀土分析表明，萤石中稀土含量为１００×１０^（－６）－２００×１０^（－６），并且随着围岩中稀土含量的增加和萤石绿度的增加而增高，随着围岩蚀变强度的增强和矿化由早到晚而降低。萤石中的稀土配分曲线为右倾斜的平缓曲线，与黑云母花岗岩及其中的黑云母具有相似性和同步性。在稀土组成三角图中，由围岩到萤石，向中或重稀土转移。在Ｍｏｌｌｅｒｅｔａｌ．的Ｔｂ／Ｃａ－Ｔｂ／Ｌａ图中，这类与花岗岩有关的萤石均落在热液区中间部位。产于陆源碳酸盐岩（海相火山沉积岩与沉积碳酸盐接触面）中的以及产于沉积碳酸盐中的萤石，处于花岗岩的下部，而与火山岩有关的处于花岗岩之上。显然在Ｍｏｌｌｅｒｅｔａｌ．的图中，此类低温热液矿床的位置，仅与围岩的岩性有关。研究后确认，华南低温热液脉状萤石矿床，是在花岗宕及与其接触的其他岩石成岩后，由大气降水组成的地下热水溶液，不断对围岩进行淋滤，使Ｃａ、Ｆ、ＲＥＥ等重新活化、转移，最后成矿的。

Most fluorite deposits from Guangdong, Fujian and Jiangxi Provinces of South China occur in the endo-or exdo-contact zone of granite intrusions. The major mechanism of mineralization is vein filling (metasomatism), strictly controlled by NEstriking structures. The REE content in fluorite ranges from 100 × 10_(-6) to 200 ×10_(-6), and increases with increasing REE content of the country rock and the increasing green degree of fluorite, but decreases with the increasing intensity of alteration of the country rock and mineralization from early to late. The REE distribution pattern of fluorite inclines toward the right, which is similar to those of the biotite granite and the biotite from the granite. Fluorite is projected into near the MREE or HREE end, and the country rock near the LREE end on the REE ternary diagram. On the Moller's 'Tb/Ca-Tb/La diagram, fluorite from the granite falls into the hydrothermal field, whereas fluorite. from terrigenous carbonate rocks (in the contact zone of marine volcanic-sedimentary rocks and sedimentary carbonates)and sedimentary carbonates are projected below the field of fluorite of granite, even into the sedimentary field. Fluorite in the volcanic rocks are above the granite field. Apparently, this kind of epithermal deposit is only related to the lithology of the country rocks on the Moller's diagram. It is concluded that the epithermal vein-type fluorite deposits in South China formed after granitism. The ore-forming solution is the heated meteoric water, which constantly leached F, Ca and REE out of the country rock. By this way, the ore elements are reactivated, transported, and finally deposited in favorable sites.