南岭大义山地区锂铷矿化特征、赋存状态及找矿评价

The Lithium and Rubidium Mineralization in the Dayishan Area,Nanling:Characteristics,Occurrence and Prospecting Evaluation

湘南大义山复式花岗岩体为南岭地区重要的锡多金属成矿岩体之一,具有多期次、高分异演化特征。以往调查研究工作多注重锡矿,而锂铷等稀有金属矿勘查研究则相对薄弱。为了指导区域综合找矿评价,本文在系统分析大义山高分异花岗岩及其赋矿特征的基础上,总结了近年来该区锂铷矿的调查研究成果。区内锂铷矿化类型以蚀变花岗岩体型为主,其次为云英岩型、伟晶岩型。岩矿鉴定及电子探针分析显示,成矿元素Li、Rb主要赋存在云母中,与热液成因的黑鳞云母和富锂多硅白云母等的叠加蚀变关系密切,云母化蚀变强弱决定了锂铷含量的高低。本次研究显示伟晶岩中的原生云母主要为铁叶云母和白云母,分异程度相对较低,伟晶岩可能为稍早形成,并为晚期高分异花岗岩的热液蚀变及成矿提供一定的屏蔽条件。提出岩体内部晚期次细粒二(白)云母花岗岩小岩体、伟晶岩壳等应作为寻找锂铷矿的重要调查对象。

The Dayishan Complex Granite is one of the most important tin polymetallic mineralization bodies in the Nanling area, with characteristic of multi-stage and highly differentiated evolutions. Previous exploration and research work have mainly focused on tin ores, and research on rare metal ore exploration such as lithium and rubidium is relatively weak. In order to guide the evaluation of regional comprehensive ore exploration, this paper summarizes the achievements of lithium-rubidium mineral investigation in the Dayishan area in recent years, based on the systematic analysis of the highly differentiated granite and their mineralization characteristics. In this area,the lithium-rubidium mineralization types are mainly of altered granitic type,followed by greisen type and pegmatitic type. Systematic rock and ore identification and electron probe microanalysis show that the ore-forming elements Li and Rb are mainly occurs in mica, which is closely related to the superimposed alteration of hydrothermal protolithionite and Li-phengite. The intensity of mica alteration determines the concentration of lithium-rubidium. The primary mica in pegmatites of this study is mainly ferrifolite and muscovite, and the degree of differentiation is relatively low. The pegmatites may have been formed at an early stage, providing some shielding conditions for the hydrothermal alteration and mineralization of late high differentiated granite. Put forward that the small rock mass such as fine-grained twomica/white-mica granite of late stage and pegmatite crust in rock mass should be taken as important investigation objects.