二连盆地巴赛齐赛汉组含铀古河谷沉积特征及铀成矿流体动力学

Depositional Characteristics and Uranium Metallogenic Fluid Dynamics of Uranium Bearing Paleo-valley of the Saihan Formation in Basaiqi,Erlian Basin

本文分析了二连盆地巴赛齐赛汉组含铀古河谷的钻孔、地震、测井等资料,对其进行了沉积特征及地层划分。结果显示,古河谷内赛汉组下段主要发育三角洲-湖沼沉积,可划分为两层。赛汉组上段主要为冲积扇-河流沉积,可划分为4层,不同地段顶部遭受了不同程度的剥蚀。古河谷内铀矿化主要位于赛汉组上段第一、第二层辫状河砂体中。古河谷铀成矿流体动力学研究表明,古河谷内铀成矿作用方式主要为：（1）砂体本身还原介质及深部油气还原的氧化还原成矿;（2）不同盐度含铀含氧流体混合卸载成矿。通过地层划分对比及铀成矿流体动力学研究,合理解释了古河谷内砂岩型铀矿床分布的原因及关系。

On the basis of borehole,seismic and well logging data,sedimentary characteristics,stratigraphic division of the Saihan Formation of basaiqi U-bearing paleo-valley at the Erlian Basin were carried out in this study. The lower member of the Saihan Formation mainly developed delta-lacustrine deposits which can be subdivided into two layers. the upper member of the Saihan Formation mainly developed alluvial fan-fluvial deposits that can be subdivided into 4 different layers. Different layers have experienced variable degrees of erosion in the top. Uranium mineralization is mainly hosted in the braided sandstone of first and second layers in the upper member of the Saihan Formation. Fluid dynamics of uranium mineralization indicates that there are two uranium mineralization patterns：（ 1） Reduction of U by reduced deep oil and gas within sandstons;（ 2） Mixing of oxidized U-bearing fluids of different salinities triggered the deposition of U. Through the study of stratigraphic division and metallogenic fluid dynamics,distribution of sandstone type uranium deposits in the paleo-valleys could be well constrained.