湘东北幕阜山地区燕山期岩浆演化与稀有金属成矿的关系

湘东北幕阜山地区分布传梓源(锂矿、铌钽矿)、仁里(钽铌矿)和虎形山(钨矿、铍矿)大型稀有金属矿床,是湖南省重要的伟晶岩型稀有金属矿集区。通过对幕阜山地区花岗岩和伟晶岩开展年代学和地球化学研究,探讨该区燕山期岩浆演化与稀有金属成矿的关系,结果表明: 该区岩浆活动自侏罗纪(154 Ma)持续到白垩纪(92 Ma),形成了复式花岗岩体和伟晶岩脉,伟晶岩空间具有含矿分带性; 伟晶岩的成矿年龄(130~127 Ma)与二云母二长花岗岩的成岩年龄(137~129 Ma)相近,成矿作用与岩浆高分异演化密切相关; 伟晶岩含矿分带性受成矿流体温度影响,矿流体温度由岩体向外成逐渐降低,形成了“岩体内伟晶岩型铍矿带—距岩体0~3 km伟晶岩型铌钽矿带—距岩体3~5 km伟晶岩型锂铌钽矿带—距岩体5~10 km石英脉型铍矿带”的环状分布格局。

Relationship between Yanshanian magmatic activity and rare metal mineralization in Mufushan area of Northeast Hunan

The big rare metal deposits, such as Chuanziyuan (Li ore and Nb-Ta ore), Liren (Nb-Ta ore) and Huxingshan (W ore and Be ore), are distributed in Mufushan area of Northeast Hunan, and this area is an important pegmatite-type rare metal deposits ore-concentrated area. According to the chronological and petrogeochemical characteristics of granite and pegmatite in Mufushan area, the authors discussed the relationship between Yanshanian magmatic activity and rare metal mineralization. The results show that the magmatic activity lasted from Jurassic (154 Ma) to Cretaceous (92 Ma), and complex granite bodies and pegmatite veins have been formed, with lithologic zonation characteristics in pegmatite veins. The ore-forming age of pegmatite (130~127 Ma) is similar to the rock-forming age of mica monzonitic granite (137~129 Ma), and the mineralization of pegmatite is closely related to the high differentiation evolution of magma. The lithologic zonation characteristics in pegmatite veins are affected by the ore-forming fluid temperature, and the temperature in pegmatite decreased with the increase of distance from the rock body. Therefore, the circular distribution pattern has been formed form the rook body, with a sequence order of the pegmatite-type Bb ore belt lin the rock body→the pegmatite-type Nb-Ta ore belt (0~3 km)→the pegmatite-type Li-Nb-Ta ore belt (3~5 km)→the quartz vein type Be ore belt.