(1. 中南大学 有色金属成矿预测教育部重点实验室，长沙 410083；
2. 中南大学 地球科学与信息物理学院，长沙 410083)
摘 要: 提出利用CSAMT与MT的响应相对误差来区分CSAMT近区、过渡区与远区场数据的方法，考虑发收距r、测量角度φ、测深频率f、覆盖层厚度h1和各层电阻率等因素。通过3种数值模型，讨论复杂介质条件下最小发收距rmin的选择方案。结果表明：均匀半空间模型中，rmin的值可精确给定；两层介质时，rmin的选择需根据勘探深度分情况讨论；多层介质时，可等效成两层介质进行估计。
关键字: 地球物理；电磁勘探；可控源音频大地电磁法；复杂介质；测量范围；发收距
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China？
2. School of Info-physics and Geomatics Engineering, Central South University, Changsha 410083, China）
Abstract:A method used to identify the near-field area, transition-field area and the far-filed area were proposed by the relative error of the responses of the CSAMT and MT. The transmit-receive distance r, angle φ, frequency f, overburden thickness h1 and resistivity of each layer were considered. The approaches used to select the optimal rmin were demonstrated based on three numerical models. The results show that, on homogeneous half-space, rmin can be given precisely. On two layer model, rmin is calculated by different cases with different exploration depth. On multi-layer model, rmin can be estimated by a equivalent two layered model.
Key words: geophysics; electromagnetic prospecting; controlled source audio-frequency magnetotelluric; complicated media; measure zone; transmit-receive distance
