CAJ | 학술논문

鄂尔多斯盆地的东胜铀矿床是一个重要的大型砂岩型铀矿床,业已查明铀石是该铀矿床的主要含铀矿物,铀石的颗粒十分细小.大量的显微镜薄片和电子显微镜观察发现,铀石通常以不规则的集合体产出于蚀变黑云母裂隙和黄铁矿边缘.电子探针分析表明,铀石中w(UO2)变化较大,在50%～70%间.与铀石相关的黑云母已经强烈蚀变,转变为水黑云母、水白云母和绿泥石.黑云母在蚀变过程中K+逐渐流失,直到基本流失殆尽,与原始黑云母相比,水黑云母w(K2O)总体减少了6.54%[占原始蚀变黑云母中w(K2O)的74%],同时w(FeO)减少了7.40%[占原始蚀变黑云母中w(FeO)的29%];水白云母与原始黑云母相比,矿物成分也发生了很大的变化,其中,w(K2O)总体减少了7.87%[占原始蚀变黑云母中w(K2O)的89%],同时w(FeO)减少了19.22%[占原始蚀变黑云母中w(FeO)的76%],w(Al2O3)由16.64%增加至32.72%,增加了16.08%.根据铀石产出的特征和蚀变水黑云母和蚀变水白云母成分特征,探讨了铀酰离子(UO2+2)被还原成U4+和形成铀石[U(SiO 4) 1-x(OH) 4x]的机理,指出古层间氧化带中铀石的形成与黑云母的蚀变以及黄铁矿的形成有着密切的联系.
악이다사분지적동성유광상시일개중요적대형사암형유광상,업이사명유석시해유광상적주요함유광물,유석적과립십분세소.대량적현미경박편화전자현미경관찰발현,유석통상이불규칙적집합체산출우식변흑운모렬극화황철광변연.전자탐침분석표명,유석중w(UO2)변화교대,재50%～70%간.여유석상관적흑운모이경강렬식변,전변위수흑운모、수백운모화록니석.흑운모재식변과정중K+축점류실,직도기본류실태진,여원시흑운모상비,수흑운모w(K2O)총체감소료6.54%[점원시식변흑운모중w(K2O)적74%],동시w(FeO)감소료7.40%[점원시식변흑운모중w(FeO)적29%];수백운모여원시흑운모상비,광물성분야발생료흔대적변화,기중,w(K2O)총체감소료7.87%[점원시식변흑운모중w(K2O)적89%],동시w(FeO)감소료19.22%[점원시식변흑운모중w(FeO)적76%],w(Al2O3)유16.64%증가지32.72%,증가료16.08%.근거유석산출적특정화식변수흑운모화식변수백운모성분특정,탐토료유선리자(UO2+2)피환원성U4+화형성유석[U(SiO 4) 1-x(OH) 4x]적궤리,지출고층간양화대중유석적형성여흑운모적식변이급황철광적형성유착밀절적련계.
Dongsheng U-deposit in Ordos Basin is an important large scale sandstone type U-deposit in China. Coffinite, as the main U-bearing mineral in the U-deposit, occurs as a micro-grain. The SEM and EPMA study indicates that the formation of coffinite is closely related to biotite, pyrite and clay minerals in the ore and that w(UO2)in the coffinite varies from 50% to 70%. The biotite has strongly altered and changed into hydrobiotite, hydromuscovite and chlorite when the biotite altered and K+ is separated from the biotite. Compared with the original biotite, w(K2O)and w(FeO) reduced 6.54% and 7.40% respectively in the hydrobiotite, reduced 7.87% and 19.22% separately in the hydromuscovite,while w(Al2O3) increased from 16.64% to 32.72%. The article probes into the formation mechanisms of U4+, which uranyl (UO2+2) was deoxidized into, and the formation mechanisms of coffinite (U(SiO4) 1-x(OH) 4x). The occurrence of coffinite, pyrite and clay minerals reflects that the formation of coffinite was closely related to the decomposition of biotite and the formation of pyrite in ancient interlayer oxidizing zone.