河南省卢氏县灰池子岩体外围花岗伟晶型铀矿地质特征研究

灰池子岩体外围发育大量的伟晶岩脉,是伟晶岩型铀矿的重要富集区,已在陕西境内发现2个大型伟晶岩型铀矿床。经过近几年的铀矿勘查,在河南省卢氏县灰池子岩体外围也发现了伟晶岩型铀矿体,证明该区存在巨大的铀矿找矿潜力。然而,由于该区研究程度较低,不利于进一步的铀矿勘查。文章以灰池子岩体外围含铀伟晶岩为研究对象,在全面分析其宏观、微观及地球化学特征的基础上,指出研究区伟晶岩型铀矿以晶质铀矿和铀钍石的形式赋存于黑云母花岗伟晶岩中,并提出了伟晶岩型铀矿的宏观、微观及地球化学找矿标志。通过对研究区伟晶岩铀矿石与光石沟铀矿石的对比研究,发现两区铀矿石虽具有相似的矿物组成及结构构造等特征,但在常量及微量元素含量、副矿物种类、岩石分异度、稀土元素及微量元素配分等方面存在一定差异,推测导致这种差异的主要原因与两个地区所处的构造位置及岩浆活动强烈程度有关。

A study of geological features of granitic pegmatite-type uranium ore deposits on periphery of Huichizi granitic pluton in Lushi County, Henan Province

There are lots of pegmatite veins on the periphery of the Huichizi granitic pluton, which constitute an important uranium concentration area, where many large pegmatite-type uranium deposits have been discovered, such as Guangshigou and Chenjiazhuang pegmatite-type uranium deposits in Shanxi Province. Uranium exploration in recent years led to the discovery of many pegmatite-type uranium orebodies on the periphery of Huichizi granitic pluton in Henan Province, which proves great metallogenetic potentiality of pegmatite-type uranium ore deposits. Based on comprehensive analysis and study of the macroscopic, microcosmic and geochemical characteristics of U-bearing biotite pegmatites, this paper points out that pegmatite-type uranium ore deposits are located in the biotite granite pegmatite in the form of crystalline uranium and uranothorite. Meanwhile, this paper points out firstly the macroscopic, microcosmic and geochemical ore-prospecting criteria in search for granitic pegmatite-type uranium ore deposits in the study area, which are red rocks, relatively big rock mineral composition, gray oily luster quartz, rich potassium feldspar and biotite, strong potassium alteration, higher values of SiO₂, K and differentiation index, lower rittmann index and oxygen fugacity, and richer Zr, Hf, V, Ti and Mo. A comparison of U-bearing biotite pegmatites between the study area and Guangshigou shows that they share similar mineral compositions and textures or structures, but are somewhat different in major and trace elements, representative mineral type, disparity, distribution of REE and some of trace elements. The main reason is possibly attributed to the different intensities of structure and magmatic activities in the two areas.