川西甲基卡花岗岩和新三号矿脉的形成时代及意义

Formation ages of granite and X03 pegmatite vein in Jiajika, western Sichuan,and their geological significance

锂被称为21世纪的能源金属,近年来在国内外受到了普遍重视。四川甲基卡矿田是中国乃至于世界上锂矿资源最集中的地区之一,近年来又发现了新三号矿脉。文章对矿田内唯一出露的马颈子花岗岩岩体中的锆石及岩体周围新三号花岗伟晶岩型锂矿脉中的锆石和铌钽矿物进行了LA-ICP-MS U-Pb同位素定年,分别获得(223±1)Ma、(216±2)Ma和(214±2)Ma的数据,表明成岩成矿作用发生于印支晚期,伟晶岩型稀有金属矿床的形成与马颈子岩体属于同期,因而含矿围岩原定为上三叠统新都桥组不合适,定为侏倭组更合理。

Lithium is known as the 21st Century energy metal and hence attracts great interest in recem yeaas the recent discovery of XO3 mega pegmatite Li mineral vein, the Jiajika orefield becomes one of the richest areas of Li resources in China and even in the world. In this study, the authors collected several zircon samples from the Majinzi granite and some niobium-tantalum mineral samples around the XO3 vein in the Jiajika orefield, and conducted LA-ICP-MSU-Pb isotope dating of all these mineral samples. Three formation ages of （223± 1） Ma, （216± 2）Ma and （214 ± 2） Ma were obtained. The results indicate that the pegrnatite rare metal deposit has the same age with the granite, and the ore-forming and rock-forming process occurred in the Late Indosinian epoch. Therefore, the wall rocks of the pegmatite should be Zhuwo Formation rather than Xindujiao Formation.