伊犁盆地南缘三工河组沉积特征与铀成矿关系

Sedimentary Characteristics of Sangonghe Formation and Their Relationship with Uranium Mineralization in the Southern Margin of Yili Basin

文章在综合研究野外露头、钻井岩心特征、砂体厚度、岩石粒度等特征的基础上,进行单井分析和连井剖面分析,并结合砂岩型铀矿的成矿规律,初步探讨不同沉积特征与铀成矿的关系。阐明了研究区三工河组的砂体发育特征,编制出该时期的沉积相图,总结了该地区的沉积特征。认为三工河组发育一套辫状河三角洲沉积体系,该沉积体系内发育四期正旋回的砂(砾)岩-泥岩岩石组合形式,砂体厚度及砂地比值适当,沉积物富含还原物质,有利于铀成矿作用。指出分流河道微相对铀成矿的控制作用以及三工河组沉积期后沉积环境变化对铀成矿作用的影响,初步筛选出有利的铀成矿区段。

In order to study the sedimentary characteristics of Sangonghe Formation in the southern margin of Yili Basin and its relationship with uranium mineralization so as to provide a basis for the division of favorable uranium metallogenic sections.Based on the comprehensive study of field outcrops,drilling core characteristics,sand body thickness and sedimentary grain size characteristics,single well analysis and well profile analysis were carried out.Combined with the metallogenic theory of sandstone-type uranium deposits,the relationship between sedimentary characteristics and uranium mineralization of the Sangonghe Formation was analyzed and studied.The sand body characteristics of Sangonghe Formation in this area were discussed,the correspondent sedimentary facies map was compiled to study the sedimentary characteristics.It was considered that there was a set of braided river delta sedimentary system in Sangonghe Formation,in which there are four normal cycles of sand-gravel to mudstone rock assemblages.The sand body thickness,the ratio of sand layer thickness to whole strata was found favorable to uranium mineralization with rich reductive materials.The channel microfacies of Sangonghe Formation controlled the uranium mineralization and environment changes after the deposition of Sangonghe Formation affect the uranium mineralization.The favorable ore-forming horizon and favorable ore forming area were preliminarily screened for the next exploration.