摘要
四川甲基卡矿田是中国乃至世界上锂辉石资源量最集中的地区之一。近年来，在甲基卡矿田东北第四系覆盖区发现了编号为X03的稀有金属矿脉——新三号脉，新增氧化锂资源量64．31万吨，规模已达超大型，远大于世界上最著名的稀有金属伟晶岩脉——新疆可可托海3#号脉。新三号脉虽然分带性差，但呈层状、透镜状产出，厚度大，全脉矿化，Li2O平均品位1．5％，共、伴生的Be、Rb、Ta、Nb、Sn、Cs等均可综合回收利用。按照矿物组合，矿石分为钠长石一锂辉石型和石英一锂辉石型两大类；按照结构、构造，矿石可分为梳状锂辉石型、微晶毛发状锂辉石型、细晶粒状锂辉石型和巨晶柱状锂辉石型。矿石结构构造显示出多期次脉动式交代的成因特点，其中锂辉石的形成至少有3个世代。新三号脉为陆壳深融型富稀碱元素花岗岩演化与交代的产物，形成于晚三叠世（223～214／Via），是印支运动末期构造趋于稳定阶段的产物。文章在深入总结甲基卡矿田成矿规律的基础上，建立了“综合研究一遥感解译和坡一残积填图一重磁测量查明岩体和伟晶岩脉就位空间一优选靶区一电法定位化探定性解释推断异常一浅成雷达探测和便携式取样查明矿脉浅表边界及产状一钻探验证控制”的第四系覆盖区立体地质综合勘查模型，在甲基卡地区打破了第四系浮土草甸覆盖区“无矿”的禁锢，并提出了通过坡一残积锂辉石“寻根溯源”，实现地质找矿的新突破，为川西地区隐伏伟晶岩型稀有金属矿床的找矿和勘查工作提供参考。新三号脉在南北延伸方向上尚未封闭，找矿潜力仍然很大，值得进一步勘查。
The Jiajika orefield, located in northwestern Sichuan Province, is one of the most concentrated areas of spo- dumene resources in China and even in the world. In recent years, a number of rare metal veins have been dis-covered under Quaternary sediments in the northeast area of the Jia]ika orefield. Among these veins, the XO3 su- perlarge vein, known as the ＂new No. 3 vein＂, is the most important, with the Li2O resource up to 643 100 tons, much higher than that of the No. 3 vein in Keketuohai, Xinjiang. The latter is one of the most famous rare metal pegmatite veins in the world. Although poorly zoned, the newly discovered XO3 vein is attractive be- cause of its layered and lenticular occurrence, thickness, average Li2O grade up to 1.5 %, and the associated ele- ments such as Be, Rb, Ta, Nb, Sn and Cs which could be comprehensively recycled and reused. According to the main ore mineral assemblage, ores can be divided into two categories （albite-spodumene and quartz-spo- dumene）, while according to the fabric features, ores can be divided into four types, i.e., comb-like spodumene type, micro-crystalline spodumene type, hair-like fine grain spodumene type and giant crystal column spodumene type. Based on ore texture and structure, it is suggested that the Xo3 vein was formed by multiple infilling and replacement of ore-forming magmatic fluids that originated from granitic magma, with the formation of spo- dumene by at least three generations. The Xo3 vein is genetically related to alkali granite that originated from continental crust and formed in Late Triassic （223--214 Ma）, with a relative stable and suitable tectonic setting for the formation of large and superlarge pegmatite veins. Based on geological survey, geochemical survey and geophysical survey in the Jiajika orefield, especially the study of the metallogenic regularity, this paper provides a prospecting model, which can be outlined as ＂geological research-Quaternary mapping coordinated by remote sensing interpretation-preferred ore prospect by gravity and magnetic measurements-locating target by electrical survey-evaluating mineral resources type by geochemical characterization-verification by drilling＂. This model is suitable for prospecting for concealed pegmatite-type rare metal deposits in western Sichuan, especially in the ar- eas covered by Quaternary sediments. It is worthwhile to point out that even the newly discovered Xo3 vein whose north end and south end of the orebody has not been drilled deserves further work in that there probably exists a large potential for prospecting in depth and in the direction of extension.
出处
《矿床地质》
CAS
CSCD
北大核心
2015年第6期1172-1186,共15页
Mineral Deposits
基金
中国地质调查局"四川三稀资源综合研究与重点评价(编号:12120112208014)""稀有稀土稀散矿产调查""中国矿产地质与区域成矿规律综合研究(中国矿产地质志)项目(编号:1212011220369)"联合资助
关键词
地质学
新三号脉
稀有金属矿床
成矿特征
找矿模型
甲基卡
geology, newly discovered X03 vein, rare metals deposits, mineralization characteristics,prospecting model, Jiajika
