准噶尔盆地东部沙帐断褶带下侏罗统沉积体系研究及其找矿意义

Study on Lower Jurassic Depositional System and Its Prospecting Significance in Shazhang Fault-fold Belt,Eastern Junggar Basin

沙帐断褶带位于准噶尔盆地东部,其下侏罗统已发现较大规模的层间氧化带及其控制的铀矿体。文章依据近几年最新铀矿勘查成果及前人煤田资料,重点对沙帐断褶带下侏罗统沉积体系进行了分析与研究,深入探讨了沉积体系与铀成矿的关系,预测了成矿最有利地段及其规模、矿化与前景,为今后找矿工作指明了方向。研究结果表明,研究区下侏罗统三工河组辫状河三角洲平原相与前缘相过渡部位为铀成矿有利相带,砂体较为发育,固结疏松,透水性好;八道湾组扇三角洲平原相与前缘相过渡部位为铀成矿较为有利相带;铀成矿有利相带与层间氧化带及其铀矿化关系密切。三工河组层间氧化带规模最大,矿化最好,具有良好的砂岩型铀矿找矿条件,是今后该区域主要找矿目的层;帐蓬沟以西发育多个产状较平缓的褶皱,氧化前锋线多位于背斜的南端及向斜的翼部,多处赋存工业矿化、异常,是今后主要找矿地段,可能具有“中-大型”砂岩型铀矿成矿前景。

Shazhang fault-fold belt is located in the east of Junggar Basin,where a large scale interlayer oxidation zone and uranium ore bodies have been found in the Lower Jurassic.Based on the latest uranium exploration results in recent years and previous coalfield data,the article focused on analyzing and studying the sedimentary system of Lower Jurassic in Shazhang fault-fold belt,deeply explored the relationship between the sedimentary system and uranium mineralization,predicted the most favorable areas for mineralization and their scale,and pointed out the direction for future mineral exploration work.The transition part between plain facies and front facies of braided river delta in Sangonghe Formation of Lower Jurassic in the study area was found favorable for uranium mineralization,with relatively developed sand bodies,loose consolidation and good water permeability;The transitional area between the fan delta plain and front facies of Badaowan Formation was believed a favorable facies zone for uranium mineralization.The favorable facies zones for uranium mineralization are closely related to interlayer oxidation zones and their uranium mineralization.In Sangonghe Formation,large scale of interlayer oxidation zones were discovered with the best mineralization,and good conditions for prospecting sandstone type uranium deposits.Multiple gently occurring folds were discovered to the west of Zhangpenggou,and the oxidation front line is mostly located at the southern end of the anticline and the wing of the syncline with mineralization and anomalies,which was believed with the potential to form"medium to large"sandstone type uranium deposit and the main prospecting area in the future.