松辽盆地南部地层结构及含矿段地层结构

Configuration of Strata in Southern Songliao Basin and the Stratigraphic Configuration of Ore-hosting Segments

上白垩统为松辽盆地南部含铀目标层位,前人大部分研究仅聚焦于铀矿带范围内的姚家组,对南部区域以及整个上白垩统研究程度较低,缺乏系统认识。文章通过系统梳理南部大量钻孔的岩心、测井资料,结合地质背景,对研究区晚白垩世主要含铀目的层特征(泉头组、青山口组和姚家组)及地层充填样式进行了阐述;在此基础上,运用沉积地层学及砂岩型铀矿成矿理论对研究区的地层结构以及主要含矿段地层结构进行了系统总结,认为:研究区晚白垩世时期地层受坳陷盆地结构及架玛吐隆起的影响,区域上地层厚度变化较大,呈现凹隆相间的格局;地层展布整体呈现西缘超覆东缘抬升剥蚀的特点;根据各个矿区及其外围含矿层位和矿化特点的不同,总结出研究区具有下红上灰式“泥-砂-泥”型、基底接触式“砂-泥”型、两红夹一灰式“泥-砂-泥”型、砂泥岩接触面型4种含铀地层结构。该研究首次全面系统的阐述了松辽盆地南部上白垩统的地层结构和含矿段地层结构,完善了该地区基础地质理论研究,可为南部砂岩型铀矿找矿工作的进一步开展提供指导。

Upper Cretaceous is the target horizon of uranium in southern Songliao Basin. Most of the previous studies only focused on the Yaojia Formation within the uranium ore belt,with a low degree of research on the southern region and the whole Upper Cretaceous, which result in poor systematic understanding. By systematically combing the core and logging data of a large number of boreholes in the south, with the geological background, the characteristics of the main uranium-bearing target layer(Quantou Formation,Qingshankou Formation, and Yaojia Formation) and strata filling styles in the study area were expounded in this paper. On this basis, stratigraphic configuration and ore-bearing segment stratigraphic configuration of uranium-bearing target layer are systematically summarized by using sedimentary stratigraphy and sandstone-type uranium metallogenic theory. The main conclusions have been summarized as follows: Firstly, affected by the structure of the depression basin and the Jimatu uplift,the strata thickness of Late Cretaceous changed greatly, showing a pattern of inter-concave and uplift. Secondly, the overall stratigraphic distribution shows the characteristics of western margin overlapping and eastern margin uplift-erosion. Thirdly, according to the different ore-bearing strata and mineralization characteristics of each mining area and its periphery, it was concluded that there are four types of uraniferous stratigraphic configuration in the study area:“mud-sand-mud” type of lower red and upper grey, “sand-mud” type of base contact, “mud-sand-mud” type of two red and one grey, and sand-mudstone contact surface type. This study comprehensively and systematically expounded the stratigraphic configuration and ore-bearing segment stratigraphic configuration of Late Cretaceous in southern Songliao Basin for the first time, which improved the basic geological theory research.In addition, this research can provide guidance for the further exploration of sandstone-type uranium deposits in the southern Songliao Basin.