二连盆地马尼特坳陷赛汉组上段赋铀沉积物源特征及其对砂岩型铀成矿的启示  

Provenance Characteristics of Uranium-Bearing Sediments of Upper Saihan Formation and Its Implications for Sandstone-Type Uranium Mineralization in Manite Depression,Erlian Basin

作　　者：刘华健 徐增连 汤超 金若时 段明 魏佳林 曾辉 张超[1,2] Liu Huajian;Xu Zenglian;Tang Chao;Jin Ruoshi;Duan Ming;Wei Jialin;Zeng Hui;Zhang Chao(Tianjin Centre of China Geological Survey,Tianjin 300170,China;Key Laboratory of Uranium Geology of China Geological Survey,Tianjin 300170,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]中国地质调查局铀矿地质重点实验室,天津300170

出　　处：《地球科学》2024年第10期3589-3609,共21页Earth Science

基　　金：中国地质调查局项目(No.DD20230269);国家自然科学基金重大研究计划项目(No.92162212);国际地球科学计划项目(No.IGCP-675)。

摘　　要：二连盆地马尼特坳陷西南缘陆海、准达赖是近年来新发现的大型砂岩型铀矿床,赋矿层位主要为下白垩统赛汉组上段.开展物源分析对丰富该地区砂岩型铀成矿理论具有十分重要的地质意义及找矿指示作用.对赋矿砂体进行了岩石学、重矿物、碎屑锆石U-Pb年代学研究工作.结果表明,赋矿砂岩类型以岩屑长石砂岩为主,其次为长石岩屑砂岩,指示物源主要来自再旋回碰撞造山带区,次为岛弧岩浆区,具混合特征.重矿物特征反映出赛汉组上段沉积时期存在北东-南西向和南东-北西向两条主河道在准达赖地区交汇的古地理格局.碎屑锆石年龄组成可划分出4个年龄区间,即120~140 Ma、200~240 Ma、260~360 Ma、390~510 Ma.陆海地区早古生代及中生代锆石年龄比重较高,而准达赖地区晚古生代锆石年龄比重明显增加.经与周缘岩体年龄谱对比,结合重矿物分析结果认为,陆海地区赛汉组上段物源可能来自于研究区北侧巴音宝力格隆起和南侧苏尼特隆起北部,而准达赖地区物源则主要来自苏尼特隆起南部,整体上呈南北双向供源模式.在限定物源的基础上,对蚀源区供铀能力分析认为,苏尼特隆起自早白垩世以来的隆升和高含铀岩体的剥蚀对研究区砂岩型铀成矿影响更为显著,指示了马尼特坳陷西南缘具有良好的砂岩型铀成矿前景.The Luhai and Zhundalai uranium deposits in southwestern margin of the Manite Depression in Erlian Basin are large sandstone-type uranium deposits newly discovered in recent years.The ore-bearing strata are mainly the upper Saihan Formation of the Lower Cretaceous.Provenance analysis of the upper Saihan Formation is of great significance to enrich the sandstone-type uranium metallogenic theory and guide the prospecting work in this area.In this paper,petrology,heavy minerals,and detrital zircon U-Pb geochronology were carried out on the ore-hosting sand bodies.The ore-hosting sandstone type is dominated by lithic feldspar sandstone,followed by feldspar lithic sandstone,indicating that the clastic material is mainly derived from the re-rotational collisional orogenic zone,followed by the island arc magmatic zone,with mixed characteristics.The characteristics of heavy minerals reflect the paleogeographical pattern that two main channels,NE-SW and SE-NW,converged in the Zhundalai area during the depositional period of the upper Saihan Formation.The age composition of detrital zircon can be divided into four age ranges of 120-140 Ma、200-240 Ma、260-360 Ma、390-510 Ma.The Early Paleozoic and Mesozoic zircon ages have a higher proportion in Luhai area,while the Late Paleozoic zircon ages in Zhundalai area have increased significantly.After comparing with the age spectrum of the surrounding rock mass and combined with the analysis results of heavy minerals,it believes that the provenance of the upper Saihan Formation in Luhai area may come from the Bayinbaolige rise in the north of the study area and the northern part of the Sunite rise in the south.The clastic material in Zhundalai area is mainly from the southern part of the Sunite rise.In general,the study area presents a north-south two-way supply model.On the basis of understanding the provenance conditions,it has analyzed the uranium supply capacity of the erosion source area.The uplift of Sunite rise since Early Cretaceous and the denudation of high uranium-b

关 键 词：碎屑锆石 重矿物 岩石学 赛汉组上段 物源分析 砂岩型铀矿 地层学 

分 类 号：P536[天文地球—古生物学与地层学]