摘要
随着社会经济的发展,各类输电线网络几乎遍布全国,对电磁法探测带来严重的干扰,即使在塔里木盆地的戈壁滩等偏远地区开展天然源电磁法探测也受到较大影响,因此需采用人工源电磁法进行探测以提高信噪比,从而获得研究区准确的地下地质结构。以频域电磁法中的可控源音频大地电磁法和时间域瞬变电磁法中的电性源瞬变电磁法为例,对塔里木盆地巴楚隆起地区地电结构进行模拟研究,从正演角度分析两种方法在砂岩型铀矿中对目标砂体分辨能力及地层结构的探测效果。结果表明:在塔里木盆地巴楚隆起地区砂岩型铀矿低阻特征的地电结构中,采用人工源电磁法中的可控源音频大地电磁法和电性源瞬变电磁法均能对一定厚度的目标砂体进行有效探测,但在斜坡带的地质结构中,CSAMT即使采用较大的收发距近源现象依然较为严重,对深部基底的地质结构探测产生较大影响,而电性源瞬变电磁法可以准确反映浅部和深部的地电结构特征,同时电性源瞬变电磁法对目标砂体的异常响应较大且对整体的地层结构分辨能力较强。因此,综合两种人工源电磁法正演模拟结果与对比分析,采用电性源瞬变电磁法对于塔里木盆地低阻特征的铀成矿环境来说,其探测效果相对较好。
With the development of social economy,various kinds power transmission line networks distribute all over the country,which has caused serious interference to electromagnetic method detection. Even if naturalsource electromagnetic method detection is carried out in remote areas such as the Gobi Desert in the Tarim Basin,it has also been greatly affected. Therefore,artificial source electromagnetic method needs to be used for detectionto improve the signal noise ratio,so as to obtain accurate underground geological structure in the study area. Thecontrollable source audio frequency magnetotelluric method in the frequency domain electromagnetic method andthe electrical source transient electromagnetic method in the time domain transient electromagnetic method werestudied in this paper with forward modeling the geoelectric structure in Bachu uplift area of the Tarim Basin. Theresults showed that in the geoelectric structure with low resistivity characteristics of sandstone type uranium depositsin Bachu uplift area of Tarim Basin,the controllable source audio frequency magnetotelluric method and electricalsource transient electromagnetic method in the artificial source electromagnetic method can effectively detect thetarget sand body with a certain thickness,but in the geological structure of slope zone,the CSAMT near sourcephenomenon was still serious even with the large transceiver distance, which greatly affected the explorationaccuracy for the geological structure of deep basement,but the electrical source transient electromagnetic methodwas not interfered and can accurately reflect the characteristics of the shallow and deep geoelectric structure. Atthe same time,the electrical source transient electromagnetic method had a large abnormal response to the targetsand body and the ability to distinguish the overall stratigraphic structure. Therefore, based on the forward modelingresults and comparative analysis of the two artificial source electromagnetic methods,the detection effect of theelectrical source transient electromagnetic method will be relatively good for the uranium metallogenic environmentwith low resistivity characteristics in the Tarim basin.
作者
胡英才
程纪星
HU Yingcai;CHENG Jixing(National Key Laboratory of Uranium Resources Exploration-Mining and Nuclear Remote Sensing,Beijing 100029,China;Beijing Research Institute of Uranium Geology,Beijing 100029,China;CNNC Key Laboratory of Uranium Resources Exploration and Evaluation Technology,Beijing 100029,China)
出处
《世界核地质科学》
CAS
2024年第6期1141-1155,共15页
World Nuclear Geoscience
基金
核技术研发科研项目(编号:地HTLM2101)资助。
关键词
瞬变电磁法
正演模拟
砂岩型铀矿
TEM
forward simulation
sandstone type uranium deposit