赣南于都万田花岗岩锆石铀-铅定年及启示

摘要

南岭是国内外著名的钨、锡及稀土成矿带,以往的研究成果大多认为其成矿作用与中生代的岩浆活动关系密切.相对地,关于加里东期花岗岩与成矿作用关系的研究较少,而实际上加里东期花岗岩的出露面积在该区域仅次于中生代花岗岩,与钨、锡及稀土成矿作用是否存在一定的联系.本文在野外调研的基础上,利用激光剥蚀-电感耦合等离子体质谱(LA-ICP-MS)技术对位于赣南于都万田花岗岩进行了锆石U-Pb定年,同时结合该区域已有的地层和花岗岩成矿元素钨、锡进行了对比分析.结果表明,万田花岗岩体成岩确定年龄为464.9 Ma,由加里东期到燕山期,花岗岩对成矿元素钨、锡富集程度呈逐渐增强的趋势,可能暗示该区的成矿作用具有一定的继承性.%The Nanling region, a famous W, Sn and rare-earth metallogenetic belt, is closely related to Mesozoic magmatic activities based on previous research work. There has been little research on the relationship between Caledonian granite and mineralization. The outcrop area of Caledonian granite in this region is slightly less than that of the Mesozoic granite and may be related with mineralization of W, Sn and rare earth elements (REEs). Based on field research, Laser Ablation-Multicollector Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICPMS) was applied to date the zircon from the Wantian granite. The W/Sn ratios from sediments and granites were compared in this area. The results show that the accurate diagenetic age of the Wantian granite is 464. 9 Ma. From the Caledonian to Yanshanian eras, the enrichment of the ore-forming elements W/Sn has gradually increased, which hints that mineralization of the area may have some inheritance.