One Dimensional Forward Study Of Metal Ores With Extremelylow Frequuency Electromagnetic Method

Electromagnetic sounding is regarded as an important mean of geophysics exploration to achieve the sounding goal,by anaylzing the differences of skin effects from different frequency signals.CSELF is seen as an method of electromagnetic sounding to study signals of frequency bands in the extremely low frequency(ELF)range(0.1Hz~300Hz).The magnetic method of extremely low frequency involves high-powered artificial sources which can be stimulated and generate signals,so that data can be collected far away from field source.The results show the signals from extreme low frequency possess some characters,including high precision,good stability and less attenuation during the propagation.The magnetic method of extremely low frequency has become an effective tool in detecting hidden metal ore and studying the space construction of ore body,for its advantages such as high intensity radiated field,low cost,large detection depth.With the rapid economic development of China,and excessive exploitation of mineral resources,metal ore,which can be found,recognized and detected easily at ground level and shallow part in our country's mineral resources,is getting less and less.Therefore,traditional mining method is not enough for the newly arising needs.The prospecting in concealed ore deposits and deep ore-body will become the major way and major requirements for the future exploitation of mineral resources in China.This thesis puts out 1 D forward modeling method of CSELF to detect metal ore.This thesis research that 1 D forward modeling method of CSELF is used to detect metal ore,through utilizing extremely low frequency electromagnetic signals(0.1Hz~300Hz)as field source.This kind of signal is not only high-powered but also high-precision,emitted by the world's first civilian extremely low frequency launching pad in a wireless transmission mode.The primary field generated by the emitter during thr propagation in a wave guide mode is calculated firstly,then,the primary field served as source is vertical into underground.With the stimulation of primary field,the underground conductive medium senses the eddies and creates the secondary field.Based on the recurrence formula of impedance,the formula of apparent resistivity is derived.According to the given initial model,the curve of apparent resistivity is obtained by simulation based on the formula.This method has been a kind of detection technology specially designed for hadal depth,which can probe to subsurface depths of ten thousand meters or more,for its advantages such as light equipment,high reliability,simple measurement,high efficiency and low cost.