磁法位场转换在非典型磁异常铁矿勘查中的相关研究

    Application of magnetic potential field transformation in exploration of iron deposits with atypical magnetic anomaly

    • 摘要: 辽宁地区地磁倾角在60°左右,一直以来磁法解译均以总场异常(ΔT)或垂直场异常(ΔZ)为主,但对于缓倾铁矿仅在矿头部分存在上述异常. 通过鞍山式铁矿消磁计算,发现非南向缓倾矿体磁化方向大幅向顺层方向(水平向)偏转. 于是利用位场转换的方法,将地磁剖面ΔT异常转换为ΔH异常,在缓倾矿体主体部分上方(ΔZ、ΔT无异常部分)见低缓ΔH异常. 因此,可利用转换后的ΔH异常定性圈定缓倾矿体范围. 该方法应用于实际勘查工作中取得了较好效果.

       

      Abstract: In Liaoning region, where the geomagnetic inclination is approximately 60°, the magnetic data interpretation has traditionally relied primarily on total field magnetic anomalies (ΔT) or vertical component anomalies (ΔZ). However, for gently dipping iron orebodies, these anomalies are only present over the upper parts(ore heads) of the deposits. Based on demagnetization calculations for Anshan-type iron deposits, it is found that the magnetization direction of non-southward gently dipping orebodies shifts significantly towards the direction parallel to the bedding plane(horizontal direction). Consequently, using the magnetic potential field transformation, the geomagnetic profile ΔT anomalies were converted into ΔH anomalies, and weak ΔH anomalies were revealed over the main parts of gently dipping orebodies, precisely where ΔZ and ΔT show no significant anomalies. Therefore, the transformed ΔH anomaly can be utilized to qualitatively delineate the extent of these gently dipping orebodies. The successful application of this method in practical exploration has demonstrated positive results.

       

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