巴音戈壁盆地中南部中新生代构造-沉积演化对铀成矿的制约及找矿预测  

Constraints of Mesozoic-Cenozoic tectonic-sedimentary evolution on uranium mineralization and prospecting prediction in the central and southern Bayin Gobi Basin

作　　者：李鹏 刘波 叶茂 刘剑剑 郝朋 熊攀 张鹏飞 LI Peng;LIU Bo;YE Mao;LIU Jianjian;HAO Peng;XIONG Pan;ZHANG Pengfei(No.208 Geological Party,CNNC,Baotou of Inner Mongolia,014010,China;Institute of sedimentary geology Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]核工业二〇八大队,内蒙古包头014010 [2]成都理工大学沉积地质研究院,四川成都610059

出　　处：《中国地质》2022年第2期542-557,共16页Geology in China

基　　金：中国核工业地质局项目“内蒙古巴音戈壁盆地及周缘铀矿资源调查评价与勘查”(202203)资助。

摘　　要：【研究目的】巴音戈壁盆地中新生代主要经历了早白垩世断陷、断坳转折以及晚白垩世坳陷发育阶段,多期次构造改造对铀成矿的制约尚不清晰,影响下一步的找矿预测工作。【研究方法】本文选择盆地中南部凹陷带为研究区,综合以往成果认识与地质剖面对比研究,系统研究了凹陷构造样式、构造演化对沉积充填的影响。【研究结果】在早白垩世中晚期、晚白垩世晚期—古近纪以及新近纪,盆地内构造-沉积演化一方面利于形成剥蚀天窗,进而发育大规模层间氧化以及多期次的后生叠加作用,控制着成矿流体以及层间氧化带由凹陷边缘向凹陷中心发育,在氧化还原障附近形成铀矿化;另一方面致使盆地南部地下水由径流—弱径流转为滞水,利于水岩作用下成矿流体中铀元素分解、析出、富集成矿。【结论】巴音戈壁盆地中南部铀成矿在有利的构造背景下,主要受沉积相控制与层间氧化带制约。This paper is the result of mineral exploration engineering.[Objective] The Mesozoic and Cenozoic Bayin Gobi basin mainly experienced Early Cretaceous fault depression, fault depression transition and Late Cretaceous depression development stages. The restriction of multi-stage structural transformation on uranium mineralization is not clear, which affects the next prospecting and prediction work. [Methods] In this paper, the depression in the central and southern part of the basin is selected as the research area. Based on the previous achievements and the comparative study of geological sections, the influence of depression structural style and structural evolution on sedimentary filling is systematically studied. [Results] During the Early Cretaceous, Middle and Late(109.7 ± 1.5) Ma-(115.5 ± 1.5) Ma, Late Cretaceous Paleogene(45.4 ± 0.6) Ma-(70.9 ± 1.0) Ma and Neogene(12.3 ± 0.2) Ma-(2.5 ± 0.0) Ma, on the one hand, the tectonic sedimentary evolution in the basin is conducive to the formation of denudation window, and then the development of large-scale interlayer oxidation and multi-stage epigenetic superposition which controls the development of ore-forming fluid and interlayer oxidation zone from the edge of the depression to the center of the depression, and forms uranium mineralization near the redox barrier;On the other hand, the groundwater in the south of the basin changes from runoff weak runoff to stagnant water, which is conducive to the decomposition, precipitation and enrichment of uranium in the ore-forming fluid under water-rock process. [Conclusions] Under the favorable tectonic background, uranium mineralization in the central and southern Bayingobi basin is mainly controlled by sedimentary facies and interlayer oxidation zone.

关 键 词：巴音戈壁盆地 构造-沉积演化 剥蚀天窗 成矿模式 矿产勘查工程 

分 类 号：P619.14[天文地球—矿床学]