川西九龙地区两期伟晶岩型稀有金属成矿作用

Two Periods Rare Metal Mineralization of the Pegmatite in Jiulong Area,Western Sichuan

川西是我国重要的稀有金属产地之一,有李家沟、业隆沟、甲基卡等超大型-大型锂铍矿床,其形成时代为220~200 Ma。本文总结了九龙地区主要稀有金属矿床特征及其相关花岗岩的成岩成矿时代,发现九龙地区以铍矿为主,且锂矿与燕山早期A型花岗岩有关,并存在两期稀有金属成矿(165~150 Ma、200~180 Ma),明显不同于甲基卡、可尔因、扎乌龙稀有金属矿集区。九龙地区因深切割、剥蚀程度高而缺失锂,暗示与九龙地区同处雅江盆地的甲基卡深部可能以赋存铍铌钽矿体为主。上述发现挑战了LCT(Li-Cs-Ta)与S型和I型花岗岩有关的观点,丰富了花岗岩与稀有金属成矿理论,为九龙地区稀有金属找矿指明了方向。

Western Sichuan is one of the important rare metal producing areas in China.There are Lijiagou,Yelonggou,Jiajika and other super-large lithium beryllium deposits,which are formed at the age of 220~200 Ma.The paper summarizes the characteristics of rare metal deposit,the diagenetic and metallogenic ages of the related granites in Jiulong area.Jiulong is dominated by beryllium deposit,and the lithium deposits are mainly related to the Early Yanshanian A-type granite in Jiulong area.There may be two periods rare metal mineralization(165~150 Ma and 200~180 Ma)in Jiulong area,which is obviously different from that rare metal ore concentration area in the Jiajika,keeryin,Zhawulong.The absence of lithium in Jiulong area due to deep cut and denudation suggests that beryllium-niobium and tantalum ore bodies may be mainly located in the deep of Jiajika ore concentration area in Yajiang Basin.This discovery poses a challenge to the traditional view that rare metals mineralization is associated with S-and I-Type granite,enriched the theory of granite and rare metal mineralization and pointing out the direction of rare metal prospecting in the Jiulong region.