作为中国北方主要产煤铀盆地之一,松辽盆地西南缘开鲁盆地一直是铀矿找矿工作的重点区域.基于开鲁盆地陆西凹陷绍根地区煤田勘探过程中发现的大量伽马异常信息,对该区展开煤田资料的铀矿二次开发,并钻探发现了铀矿化显示.在此背景下,对绍根地区早白垩世裂陷期晚期至今沉积地层展开地层精细对比划分、沉积环境和构造演化分析、铀成矿类型和赋矿规律探讨.综合分析认为:1)绍根地区自早白垩世阜新期以来发育阜新组、姚家组、嫩江组、四方台组和泰康组,泉头—青山口组、明水组缺失.2)绍根地区阜新期为断陷期末期深湖—湖沼相沉积,发育多层煤;之后受燕山运动影响,阜新期末发生构造反转,泉头—姚家期早期处于构造隆升的欠补偿时期,阜新组顶部遭受剥蚀,泉头—姚家早期未接受沉积;姚家晚期—嫩江期为热沉降坳陷阶段,发育冲积扇相和滨浅湖—半深湖相沉积;四方台期为挤压反转期,地层快速隆升,发育冲洪积扇沉积.3)嫩江组和四方台组为绍根地区主要赋矿层,其中嫩江组发育泥岩型铀矿体,四方台组发育砂岩型铀矿体.4)泥岩型铀矿体顺层呈中心向下凹的薄板状发育,为典型的同生沉积成岩成矿;砂岩型铀矿体呈板状,主要赋存于四方台组底部红褐色与灰绿色交界部位的灰绿色砂砾岩中,其成矿类型可能为潜水氧化型.上述成果认识与钱家店等邻区有较大差异,对绍根地区下一步的铀矿找矿工作具有较好的指导意义.%As one of the major coal and uranium bearing basins in Northern China,Kailu Basin,which locates in the southwest of Songliao Basin,has always been an emphasis area for uranium exploration. Based on a large number of gamma anomalies found in the coal exploration in Shaogen area of Kailu Basin,a uranium geological survey launched few years ago and some uranium mineralization points were discovered. In this case,researches such as detailed strati-graphic correlation,serious analysis of sedimentary environment and tectonic evolution,discussion of uranium miner-alization characteristics have been carried out. In view of the above comprehensive analysis,we get four main conclu-sions:①Shaogen area developes Fuxin,Yaojia,Nenjiang,Sifangtai and Taikang Formation from the bottom up with absence of Quantou to Qingshankou Formation and Mingshui Formation. ②Fuxin stage is in the end of fault depression period developing lacustrine swamp environment with several layers of coal;whilst due to compression and uplifting af-ter Fuxin period,there has been no sediments from Quantou to early Yaojia Period;then it switches into a slight ex-tensional environment and deposits lacustrine silt in Nenjiang stage;accompany with the following structrral inversion, alluvial fan deposits in the Sifangtai Formation. ③Both Nenjiang and Sifangtai Formation are the uranium ore-bearing strata,while mudstone type uranium develops in Nenjiang Formation and sandstone type uranium in Sifangtai Forma-tion. ④Mudstone type uranium orebody which locates in trasition zone of the yellow green and gray mud in the up of Nenjiang Formation presents a thin plate with a central downward concave shape,indicating a synsedimentary deposi-tion;While sandstone type uranium orebody which locates in transition zone of reddish brown and gray green sandy conglomerate in the bottom of Sifangtai Formation presents a short plank shape and may illustrate a phreatic oxidation type mineralization. These research results have the extensive applicability and practical instruction significance in U-ranium exploration of Shaogen area.
展开▼
