Wavelet Multi-Scale Decomposition of Magnetic Anomaly and Its Application in Searching for Deep-Buried Minerals in Crisis Mines: A Case Study from Daye Iron Mines
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摘要: 大冶铁矿是多年开采老矿山, 浅部的铁矿已开采殆尽, 为了进一步挖潜, 利用小波多尺度分析方法, 将磁异常分解到不同尺度空间, 结合谱分析方法解释深部盲矿体.理论模型和19-1勘探线的实际资料的小波分解结果表明, 该方法比常规的空间延拓、高次导数、匹配滤波等方法要好.通过处理与解释指出了西段(尖林山、龙洞、铁门坎) 五阶小波细节已无剩余异常存在, 推测在1000m以下已没有大型的铁矿体存在.但在东段(尖山、犁头山) 五阶小波细节还有剩余异常, 推测1000m深部可能还有铁矿体.根据小波多尺度分析方法结合人机交互反演推断15~12线有铁矿体, 2005年9月布钻验证, 在15~1线打到30多米厚磁铁矿体.Abstract: The shallow iron ores of Daye mines are exhausted after years of exploration and mining. In order to search for deep-buried ores, the wavelet multi-scale analysis method was employed to decompose the magnetic anomaly into different scales and further explain the deep-buried unknown ore body through the combination of spectrum analysis. Theoretical modeling indicates that this method is superior to ordinary approaches such as analytical continuation, higher order derivatives, matched filter and so on. Magnetic data processing and interpretation of the Daye iron mines show that there is no large-scale iron ore below the depth of 1 000 m at its western part (Jianlinshan, Longdong and Tiemenkan), for the residual magnetic anomaly is not present in its five order wavelet approximation map. On the contrary, the residual anomaly still exists in the five order wavelet approximation map of the eastern mines (Jianshan, Litoushan), indicating the possible existence of iron ores at the depth of 1 000 m, which needs to be further researched.
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图 2 垂直磁化组合球体磁场及小波多尺度分解
Fig. 2. Fig2 Field of vertically magnetized spheres and wavelet multi-scale decomposition
图 3 19-1线ΔZ磁异常的小波分解和已知磁性体的对应关系
a.ΔZ磁异常的小波分解和已知磁性体的正演; b.已知磁性体
Fig. 3. Relationship of wavelet multi-scale decomposition of ΔZ magnetic anomalies and known magnetic object
图 4 冶铁矿ΔZ磁异常及小波多尺度分解结果
a.原始ΔZ磁异常；b.小波多尺度分解一阶细节；c小波多尺度分解五阶细节；d小波多尺度分解五阶逼近
Fig. 4. ΔZ magnetic anomalies and wavelet multi-scale decomposition of Daye iron mines
表 1 球体模型参数
Table 1. Sphere model parameters
表 2 球体模型磁场极大值(nT)
Table 2. Maximal value of sphere model magnetic field
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