准噶尔盆地北部乌伦古地区上白垩统红砾山组沉积特征及红杂色层成因探讨  

Discussion on Sedimentary Characteristics and Genesis of Red Variegated Layer of Upper Cretaceous Honglishan Formation in Wulungu Area,Northern Junggar Basin

作　　者：冀华丽 何中波[1] 钟军[1] 陈虹[2] 朱斌 吴玉[1] 东前[1] JI Huai;HE Zhongbo;ZHONG Jun;CHEN Hong;ZHU Bin;WU Yu;DONG Qian(CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Techniques,Beijing Research Institute of Uranium Geology,Beijing 100029,China;Geologic Party No.216,CNNC,Urumqi,Xinjiang 830011,China)

机构地区：[1]核工业北京地质研究院中核集团铀资源勘查与评价技术重点实验室,北京100029 [2]核工业二一六大队,新疆乌鲁木齐830011

出　　处：《铀矿地质》2023年第6期1019-1036,共18页Uranium Geology

基　　金：中核集团集中研发项目(编号:中核科发2021-143号);中核集团青年英才“菁英”项目(编号:地QNYC2201);中国核工业地质局铀矿勘查项目(编号:2022006006)联合资助。

摘　　要：沉积盖层的原生沉积环境特征是其铀成矿条件分析的关键要素之一,文章在宏观沉积特征和微观岩石学特征基础上,结合岩石样品主微量元素分析、黏土矿物分析及古生物孢粉组合测试数据,综合分析了研究区上白垩统红砾山组红杂色碎屑建造的原生沉积环境。结果表明:1)红砾山组具有“下砂上泥、下黄上红、下粗上细”的沉积特征,岩石类型以岩屑长石砂岩为主,少量为长石岩屑砂岩和长石砂岩;2)CIA、ICV指数反映红砾山组沉积时期,物源区岩石遭受了较强的化学风化作用,并指示周缘物源区开始进入了构造活动期;3)一系列微量元素组合比值对比趋势指示红砾山组沉积时为陆相淡水、循环较为顺畅的富氧-次富氧环境,并且灰-灰白色砂岩的还原能力较为有限;4)红砾山组沉积时期,黏土矿物组合类型以蒙皂石+伊利石+绿泥石型为主,孢粉以裸子植物占优势,苔藓、蕨类植物孢子居次要位置,整体反映红砾山组沉积时期古地理环境属干旱-半干旱、较炎热、贫K+、碱性、强氧化、强蒸发条件下的河流相沉积。The primary sedimentary environment of the sedimentary cover is one of the key elements in the analysis of uranium metallogenic conditions.Based on the macroscopic sedimentary characteristics and microscopic petrological characteristics,analysis of the main and trace elements of rock samples,clay minerals and the test data of paleontological sporopollen assemblages,this paper comprehensively analyzed the primary sedimentary environment of the red variegated clastic formation of the Upper Cretaceous Honglishan Formation in the study area.The Honglishan Formation was found with the sedimentary characteristics of“lower sand and upper mud,lower yellow and upper red,lower coarse and upper fine”and the rock types are mainly lithic feldspar sandstone with a small amount of feldspar lithic sandstone and feldspar sandstone.The CIA and ICV indexes suggested that rocks in source area experienced strong chemical weathering during the deposition period of the Honglishan Formation,and the surrounding source area entered the tectonic activity period.A series of trace element combination ratio comparison trends indicated that the Honglishan Formation was deposited in a continental fresh water,relatively smooth circulation of oxygen-rich and sub-oxygen-rich environment,and the reduction capacity of gray-white sandstone was relatively limited.During the deposition period of the Honglishan Formation,the clay mineral assemblage type was mainly S+I+C type,the spore-pollen was dominated by gymnosperms,and the moss and fern spores were in the secondary position.The overall reflection of the paleogeographic environment during the deposition period of the Honglishan Formation was arid-semi-arid,hot,poor in K+,alkaline,strong in oxidation and evaporation under the condition of river facies deposition.

关 键 词：主量元素 微量元素 黏土矿物组合 孢粉组合 上白垩统红砾山组 

分 类 号：P619.14[天文地球—矿床学]