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相山铀矿田河元背地区电性结构特征及其地质意义

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位于相山铀矿田西部的河元背地区是铀多金属深部找矿的重要远景地段,但目前该区对深部控矿要素的展布以及深部多金属矿化的产出有利空间仍缺乏足够的认识和可靠约束,因此查明该地区深部控矿要素的空间展布对推动深部找矿突破具有重要意义.本文利用一条8 km长的音频大地电磁剖面,采用相位张量分析方法对数据进行分段阻抗张量旋转后,采用非线性共轭梯度法开展带地形二维反演,构建了研究区精细电性结构模型.结合区域地质、钻孔和重磁资料,得到以下结论:(1)研究区红盆范围呈现出两层电性结构,即低阻的红层上覆在高阻的变质岩基底之上;火山盆地范围则呈三层电性结构特征,分别为高阻的鹅湖岭组、中低阻的打鼓顶组火山岩和高阻的变质岩基底.(2)河元背地区主要控矿断裂为F河-小和F苦-小断裂,其与火山岩组间界面、变质岩基底顶界面的复合变异部位为含矿热液提供了有利容矿空间,控制着铀多金属矿的产出,深部增厚火山岩是下一步多金属找矿突破的有利远景区段.(3)相山铀矿田西部早期富含多金属的热液流体在深部混合下渗的大气降水后交代沉淀形成多金属矿化,在持续伸展拉张环境下,后期含矿热液流体继续沿着深断裂上升运移和分异演化,并不断萃取火山岩中的铀元素沉淀成矿,最终形成了上铀下多金属的垂向分布特征.
Electrical structure and geological significance of Heyuanbei area in Xiangshan uranium orefield
The Heyuanbei area,located in the western part of the Xiangshan uranium orefield,is an important prospective region for deep uranium and polymetallic exploration.However,the current understanding and reliable constraints on the spatial distribution of deep ore-controlling factors and the favorable space for deep polymetallic mineralization in this area are still insufficient.Therefore,determining the spatial distribution of deep ore-controlling factors in this area holds significant importance for advancing breakthroughs in deep ore exploration.This paper utilizes an 8-kilometer-long audio-magnetotelluric profile.The data is subjected to segment-wise impedance tensor rotation through the application of the phase tensor analysis methods.Subsequently,a non-linear conjugate gradient method is employed to conduct two-dimensional inversion incorporating terrain effects.This process results in the construction of a detailed electrical structure model of the study area.By combining regional geological,borehole,and gravity-magnetic data,the following conclusions have been reached:(1)In the study area,the red basin range exhibits a two-layer of electrical structure,with a low-resistivity red layer overlaying a high-resistivity metamorphic rock basement.In constrast,the volcanic basin range exhibits a three-layer electrical structure,consisting the high-resistivity Ehuling formation,the intermediate to low-resistivity Daguding formation volcanic rock,and a high-resistivity metamorphic rock basement.(2)The primary ore-controlling faults in the Heyuanbei area are the He-Xiao fault and the Ku-Xiao fault.These faults,along with compolex variation positions at the boundaries between the volcanic rock group and the upper boundaries of the metamorphic rock basemengt,provide favorable space for mineral-bearing hydrothermal fluids,thereby controlling the production of uranium and polymetallic deposits.The thickening volcanic rocks in deeper sections offer promising prospective areas for further polymetallic prospecting breakthroughs.(3)Early polymetallic rich hydrothermal fluids in the western part of the Xiangshan uranium orefield formed polymetallic mineralization through metasomatic precipitation after deep mixing and infiltration of atmospheric precipitation.In a sustained extensional tectonic environment,mineral-bearing hydrothermal fluids in later stages persistently ascended,migrated,and underwent differentiation and evolution along deep faults.These fluids continuously extracted uranium elements from volcanic rocks and precipitated them into mineral deposits,ultimately resulting in a vertical distribution pattern characterized by uranium enrichment above and polymetallic below.

Xiangshan uranium orefieldHeyuanbei areaAudio frequency magnetotelluric soundingElectrical structureOre-controlling factors

苏鹏锦、邓居智、陈辉、余辉、银涌兵、陈凯、高科宁、游越新

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东华理工大学地球物理与测控技术学院,南昌 330013

东华理工大学核资源与环境国家重点实验室,南昌 330013

江西省地质局核地质大队,鹰潭 335001

相山铀矿田 河元背地区 音频大地电磁 电性结构 控矿要素

国家自然科学基金国家自然科学基金国家自然科学基金江西省科技计划核资源与环境国家重点实验室开放基金自然资源部深地科学与探测技术实验室开放基金

42130811418640044167407720204BCJL230582022NRE18Sinoprobe Lab 202214

2024

10.6038/pg2024HH0235

地球物理学进展
中国科学院地质与地球物理研究所 中国地球物理学会

地球物理学进展

CSTPCD北大核心
影响因子：1.761
ISSN：1004-2903
年,卷(期)：2024.39(2)