砂岩型铀矿广域电磁法试验与探讨

Test and Discussion of Wide Field Electromagnetic Method in Sandstone-type Uranium Deposits Exploration

为探究广域电磁法在砂岩型铀矿勘查中的应用效果,选择在松辽盆地宝龙山和克东地区开展广域电磁法与AMT及CSAMT的对比试验。从采集频率、视电阻率曲线、反演电阻率断面三个角度对上述方法进行了对比,认为:WFEM可供选择的有效采集频率更低,频点密度与AMT及CSAMT相当或更密;三种方法在同测点上的视电阻率曲线基本一致,但WFEM最低有效频率较AMT及CSAMT更低,视电阻率质量更高;同剖面、同反演参数的电阻率断面上,WFEM反演电阻率断面在水平成层性及垂向分层能力方面略优于AMT及CSAMT,探深能力比AMT及CSAMT方法强。利用WFEM方法识别了松辽盆地两个试验区的地层结构,且与钻孔揭露情况吻合较好,表明WFEM方法在砂岩型铀矿成矿环境探测中具有一定的应用效果,有必要开展进一步的方法试验工作。

In order to research the application effect of wide field electromagnetic method on sand-type uranium deposit exploration,the comparative tests of wide-area electromagnetic method(WFEM),AMT and CSAMT were carried out in Baolongshan and Kedong area of Songliao basin.The above methods are compared from three aspects,acquisition frequency,apparent resistivity curve,and inversion resistivity section.The conclusions are summarized as follow:(1)The available effective acquisition frequency for WFEM is lower,the frequency point density is equivalent to or denser than AMT and CSAMT.(2)The apparent resistivity curves of the three methods at the same point are basically the same,but WFEM’s lowest effective frequency is lower than that of AMT and CSAMT,and the apparent resistivity quality is higher.(3)For inversion resistivity sections with the same profile and same inversion parameters,the resistivity section inverted by WFEM is slightly better than AMT and CSAMT in terms of horizontal stratification and vertical stratification,and its depth exploration capability is stronger than that of AMT and CSAMT.The WFEM method is used to identify the stratigraphic structure of the two test areas in Songliao basin,and it is in good agreement with the drilling exposure,indicating that WFEM has a good application effect in the mineralization environment exploration of sandstone-type uranium deposits,and it is necessary to carry out further test and research.