摘要
中国北方中生代含煤盆地常见煤、铀共伴生发育,且煤及煤系砂岩型铀矿表现为特征的“下煤上铀”的地层结构。为精确约束沉积要素在中生代含煤盆地煤及煤系砂岩型铀矿富集成藏(矿)中的作用,探讨煤、铀共伴生的沉积机理,优选准噶尔盆地东部发育“八道湾组煤–八道湾组铀”“西山窑组煤–头屯河组铀”两套“下煤上铀”地层结构的准东煤田及其邻区,聚焦侏罗系构造–沉积演化,通过典型地震剖面的构造解译和连井剖面的细致解析,重点开展等时地层对比和地层层序分析,精细刻画早侏罗世八道湾组至晚侏罗世奇古组的沉积相类型和沉积体系变化规律。结果表明:(1)准噶尔盆地东部准东煤田及其邻区侏罗系的沉积演化具有明显的旋回性,是一个顶、底面为区域性不整合面所限,由多个退积–进积的3级沉积旋回组成的完整2级沉积序列;(2)盆地退积–进积沉积演化的旋回性是“下煤上铀”地层结构发育的主要原因,它通过可容纳空间变化控制了沉积环境的转变和物质的空间配置,且进积比退积对应更强的聚煤作用和更适宜的铀储层砂体;(3)高级别的沉积旋回具备更强的强迫性,制约在2级旋回中处于退积环境的八道湾组的“下煤上铀”规模远小于处于进积环境的西山窑–头屯河组。沉积序列分析可用于含煤盆地的聚煤作用分析和铀储层铀成矿远景预测,特别是铀成矿新区新层位的预测。
Coal and sandstone-type uranium deposits in the Mesozoic coal-bearing basins in Northern China often show the stratigraphic structure of“lower coal and upper uranium”,indicating a good co-occurrence relationship between coal and uranium deposit.In order to precisely restrict the role of sedimentary factors in coal accumulation and uranium enrichment,and to explore the sedimentary mechanism of coal and uranium co-occurrence,we selected the Zhundong coalfield and its adjacent areas in the eastern Junggar Basin,where there are two sets of“lower coal and upper uranium”strata,as the research object.Based on the stratigraphic sequence analysis and isochronous stratigraphic framework construction,detailed sedimentary characterization of coal measure strata and an in-depth discussion of sediment-ary evolution law are carried out.The results show that the Jurassic strata in the Zhundong coalfield and its adjacent areas is a complete second-order sequence consistent of multiple third-order depositional cycles of retrogradation-progradation,and the top and bottom are limited by regional unconformities.The retrogradation-progradation sedimentary cycle is the main reason for the superposition of coal measure strata and uranium reservoir.It controls the change of sedimentary environment and the spatial configuration of materials by ac-commodating spatial changes,and progradation corresponds to stronger coal accumulation and better uranium reservoir sand body than ret-rogradation.Moreover,The second-order sedimentary cycle has stronger compulsion than the third-order sedimentary cycle,which re-stricts“lower coal and upper uranium”formation structure of Badaowan Formation in the regressive environment in the second-order cycle to be much smaller than that in Xishanyao-Toutunhe Formation in the progradative environment.All these results will provide a theoretic-al basis for the prospect prediction of uranium mineralization in other coal-bearing basins,especially for the identification of new uranium reservoirs and new
作者
吴兆剑
韩效忠
李紫楠
胡航
来强
WU Zhaojian;HAN Xiaozhong;LI Zinan;HU Hang;LAI Qiang(China Coal Geology Group Co.,Ltd.,Beijing 100040,China)
出处
《煤炭科学技术》
EI
CAS
CSCD
北大核心
2023年第12期52-64,共13页
Coal Science and Technology
基金
国家重点研发计划资助项目(2023YFC2906701)
国家自然科学基金资助项目(42202088)。
关键词
煤系砂岩型铀矿
下煤上铀
可容纳空间
沉积旋回
sandstone type uranium deposit
lower coal and upper uranium
accommodation
sedimentary cycle
