二连盆地脑木根凹陷沉积型铀矿成矿特征

Metallogenic Features of Sedimentary Uranium Deposit in Nomgen Depression,Erenhot Basin

二连盆地乌兰察布坳陷是我国重要的沉积型铀矿成矿区,脑木根凹陷为二连盆地乌兰察布坳陷南缘的一个次级凹陷,其中的下白垩统赛汉组沉积了一套三角洲-湖泊相含煤碎屑岩建造,具备铀成矿基本条件。通过对煤田钻孔资料"二次开发",配合钻探验证,在下白垩统赛汉组中圈定了连续稳定的放射性异常区。发现了潜水氧化型和同沉积泥岩型铀矿成矿类型,研究区铀矿化主要受古气候、成矿期砂体沉积特征、铀源、后生氧化作用等多重因素的控制。建立了研究区潜水氧化叠合同沉积泥岩型铀矿成矿模式。

The Ulanqab depression in the Erenhot Basin is a significant sedimentary uranium metallogenic province in the country, while the Nomgen depression is a secondary depression in southern part of Ulanqab depression. The lower Cretaceous Saihan Formation in Nomgen depression has deposited a set of delta-lacustrine facies coal-bearing clastic rock formation with basic uranium metallogenic conditions. Through the “further utilization” of coalfield drilling data cooperating with drilling verification have delineated continuously stable radioactive abnormal places in Saihan Formation. Thereout have found phreatic oxidization and synsedimentary mudstone uranium metallogenic types. Uranium metallogenic in study area is mainly controlled by multiple factors including paleoclimate, sedimentary features of sand mass during metallogenic epoch, uranium source, epigenetic oxidation etc. The study has established phreatic oxidation superimposed by synsedimentary mudstone uranium metallogenic model in the area.