鄂尔多斯盆地西南缘砂岩型铀矿含矿目的层——洛河组砂岩的沉积物源特征  

Sediment Source Characteristics of the Target Sandstone Layer for Sandstone-type Uranium Deposit in Southwestern Ordos Basin

作　　者：张翔[1] 胡永兴[1] 杨涛[1] 胡妍 柳永刚 欧扬剑 ZHANG Xiang;HU Yongxing;YANG Tao;HU Yan;LIU Yonggang;OU Yangjian(Geological Survey of Gansu Province,Lanzhou,Gansu 730000,China;Geological Survey Fund Management Center of Gansu Province,Lanzhou,Gansu 730000,China)

机构地区：[1]甘肃省地质调查院,甘肃兰州730000 [2]甘肃省地质勘查基金管理中心,甘肃兰州730000

出　　处：《铀矿地质》2022年第2期153-167,共15页Uranium Geology

基　　金：甘肃省科技重大专项“陇东地区砂岩型铀矿成矿规律研究”(编号:18ZD2GF019);中国地质调查局项目“甘肃省鄂尔多斯盆地南缘泾川一带铀矿地质调查”(编号:DD20160128-06);2020年陇原青年创新创业人才项目“陇东地区砂岩型铀矿成矿规律与找矿方向研究”;2020年甘肃省青年科技人才托举工程项目“陇东地区白垩系砂岩型铀矿成矿规律与战略选取研究”联合资助。

摘　　要：鄂尔多斯盆地西南缘洛河组砂岩中见有较好的铀矿化现象,具有较大的铀成矿潜力。文章针对盆地西南缘洛河组砂岩开展了碎屑锆石U-Pb定年及重矿物组合分析,并综合探讨了盆地西南缘洛河组沉积物源特征。研究表明:区内洛河组砂岩碎屑锆石U-Pb年龄主要分布在460~95 Ma、1133~982 Ma、2114~1483 Ma、2719~2230 Ma四个年龄区间,以锆石+赤褐铁矿+磷灰石为主的重矿物组合表示沉积物源可能以中酸性岩浆岩为主。通过与周缘岩体年龄进行对比分析,认为研究区洛河组物源主体来源于盆地北侧华北克拉通北缘地区显生宙、古元古代以及新太古代中酸性岩浆岩及变质岩,同时存在西北侧阿拉善地块与兴蒙造山带的小部分贡献。Sandstone-type uranium mineralization has been identified in the Luohe Formation in southwestern Ordos Basin,indicating great uranium mineralization potential.Detrital zircon U-Pb dating and heavy mineral assemblage analysis for Luohe Formation sandstones was carried out to constrain the sediment source characteristics.The U-Pb ages of detrital zircons in the Luohe Formation sandstones can be mainly divided into four groups,namely:460~95 Ma,1133~982 Ma,2114~1483 Ma and 2719~2230 Ma.The heavy mineral assemblage of zircon+hematite/limonite+apatite in the Luohe Formation sandstones indicates that the sediment source may be dominated by intermediate acid magmatic rocks.Through the U-Pb age comparison between the detrital zircons from Luohe Formation and the surrounding magmatic rocks,it is suggested that the sediment sources of the Luohe Formation in the study area might be mainly from the Phanerozoic,Paleoproterozoic and Neoarchean intermediate-acid magmatic rocks and metamorphic rocks from the northern margin of the North China Craton to the north of the basin,with small contribution from the Alxa block in the northwest and Xing-Meng orogenic belt in the north.

关 键 词：洛河组 物源分析 碎屑锆石 重矿物特征 砂岩型铀矿 鄂尔多斯盆地西南缘 

分 类 号：P619.14[天文地球—矿床学]