赣中聚源大型石英脉型白钨矿床含铀富钨矿物初步研究

聚源钨矿是华南地区为数不多的大型石英脉型白钨矿矿床之一。在详细的野外地质调查基础上,本文利用α径迹蚀刻、电子显微镜、扫描电镜以及电子探针等实验手段,对该矿床含钨和含铀矿物开展了精细矿物学的研究工作,探讨了成矿过程中钨和铀的富集规律。研究显示,该矿床钨铀矿物的形成可分为四个阶段:第一阶段,钨铀主要进入富含Nb、Ti的氧化物矿物,形成铌铁矿、钇易解石等富钨矿物,另有极少量的钨进入黑钨矿和早阶段白钨矿;第二阶段,铌铁矿与钇易解石被后期流体交代,形成含钨富铀的骑田岭矿、铌锰矿以及钛-钇易解石;第三阶段,钨进入中阶段白钨矿,这一阶段也是钨最主要的矿化阶段;第四阶段,钨进入晚阶段白钨矿。最后两阶段白钨矿中铀含量不高。骑田岭矿(WO_3 26.74%～29.68%),是聚源钨矿中除白钨矿和黑钨矿之外钨含量最高的含钨矿物。该矿易解石族矿物WO_3最高可达9.80%,极度富钨,是目前有文可查的钨含量最高的易解石。聚源钨矿中的含钨矿物大多数为白钨矿,但绝大多数的白钨矿却在骑田岭矿、易解石族矿物、铌铁矿族矿物、黑钨矿之后形成,说明成矿流体在演化过程中,绝大多数W首先进入富含Nb、Ti的含铀矿物和少量黑钨矿,之后才是白钨矿的大量结晶。

A primary study on U-bearing W-rich minerals in Juyuan large quartz vein type scheelite deposit, central Jiangxi Province

Juyuan W deposit is one of the few large quartz vein type scheelite deposits in South China. Based on detailed field geological surveys, this paper uses optical microscope and track etching and scanning electron microscope observations, together with electron probe micro analysis to study the tungsten and uranium-bearing minerals in this deposit. The formation of tungsten-uranium minerals in this deposit can be divided into four stages: (1) in the first stage, tungsten-uranium mainly enters oxide minerals rich in Nb and Ti, forming tungsten-rich minerals such as columbite and priorite, and a very small amount of tungsten enters the wolframite and the early stage scheelite; (2) in the second stage, the columbite and the priorite are replaced by later-formed minerals, forming the qitianlingite, mangancolumbite and Ti-rich priorite; (3) in the third stage, tungsten enters the middle stage scheelite, which is also the most important mineralization stage of tungsten; (4) in the fourth stage, tungsten enters the late stage scheelite. The uranium content in the last two stages of scheelite is not high. Except for scheelite and wolframite, the qitianlingite (WO₃ 26.74%~29.68%) is the tungsten-containing mineral with the highest tungsten contents in the deposit; and subordinately, the aeschynite is another mineral extremely rich in tungsten, which has a WO₃ content up to 9.80%. Most of the tungsten-bearing minerals in the poly-tungsten ore are scheelite, however, most scheelite is formed after the qitianlingite, the aeschynite, the coltan and the wolframite. During the evolution of ore-forming fluids, most of the W first entered the uranium-bearing minerals that is rich in Nb and Ti and the wolframite, and then it is the massive crystallization of scheelite.