松辽盆地宝龙山铀矿床控矿因素与成矿模式研究

Study on Ore Controlling Factors and Metallogenic Model of the Baolongshan Uranium Deposit

产于松辽盆地西南部的宝龙山铀矿床是盆地代表性矿床之一,开展矿床控矿要素和成矿模式的研究对推进盆地区域找矿工作具借鉴意义。文章通过对宝龙山铀矿床成矿地质背景分析与矿化特征研究,厘定矿床关键控矿要素为辫状河灰色砂体、反转背斜(剥蚀天窗)和流体叠加改造;通过矿石U-Pb同位素分析与等时线拟合获得了81.2 Ma、74.5 Ma、52.3 Ma和46.6 Ma等成矿年龄数据,表明铀成矿作用由晚白垩世末持续至古近纪早中期,具有多期次叠加成矿的特征。在此基础上结合区域构造演化和铀矿化发育特征分析,将矿床成矿过程划分为成岩预富集、油气改造扩大、层间氧化成矿、油气渗出保矿4个阶段,并构建了宝龙山铀矿床4阶段成矿模式,为矿区外围和新区铀矿勘查工作部署提供借鉴。

Baolongshan deposit,located in the southwest of the Songliao Basin,is one of the representative deposits in Tongliao uranium belts.Study on ore controlling factors and metallogenic model of Baolongshan deposit will benefit the regional uranium prospecting in the basin.Based on the study of geological background and mineralization characteristics,the gray sand body of braided river facies,reversal anticline structure(erosion window)and hydrothermal overprinting were regarded as the main ore-controlling factors.Four oreforming ages of 81.2 Ma,74.5 Ma,52.3 Ma and 46.6 Ma were obtained by U-Pb dating,which indicated that the uranium metallogenesis are with multi-stages superposition lasted from the end of the Late Cretaceous to Early-Middle Paleogene.Combined with the analysis of the regional tectonic evolution and the ore body features,4 stages of ore-forming processes were identified i.e.,the syngeneic pre-enrichment,rework of oil and gas,interlayer oxidation mineralization and ore-preserving by oil-gas seepage As a result,a 4-stage metallogenic model was established for Baolongshan deposit,which will support the uranium deployment in the periphery of the mining area and the new areas.