深源矿致异常提取方法对比及应用: 以山东齐河—禹城地区航磁数据为例

doi:10.19657/j.geoscience.1000-8527.2024.004

摘要/Abstract

摘要：

深部磁铁矿体的埋深较大,且目标矿体和成矿岩体产生的磁异常往往相互耦合、干扰,加之航磁测量的观测面高,导致深源矿致航磁异常的信号一般较弱。因此,难以从原始航磁异常图中直接圈定深部磁铁矿靶区。位场分离技术是提取矿致异常的有效途径,但位场分离方法众多,且使用便捷性、提取效果存在差异,筛选适用于深部磁铁矿的矿致异常提取方法以及讨论相关参数调节方法具有较大的理论和实用价值。本文对比研究了6种常用的位场分离方法,分析了各方法参数调节的便捷性和有效性。通过模型试验,从全区和靶区两个尺度对比了各方法对矿致异常的提取效果。山东齐河—禹城厚覆盖区的深部赋存接触交代成因的磁铁矿床,是深部矿产的典型代表,本文根据该区地质模型建立理论磁性模型,验证了深部矿致异常提取的可行性。实测数据处理部分,提出基于标志剖面交互调节相关参数以及验证矿致异常提取效果,最终提取的矿致异常结果与已知的钻孔见矿信息匹配,表明该结果与实际的矿致异常相关性较高,可为后续矿体靶区圈定和钻孔位置布设提供参考。

关键词: 深部探测, 磁铁矿, 航空磁测, 位场分离, 靶区圈定

Abstract:

The large depth that the magnetite is buried and the long distance of aeromagnetic survey always leads to a weak signal of magnetic anomaly.In addition, due to that the deep magnetite mostly is formed through contact metasomatism caused by magmatic intrusion, the magnetic anomalies sourced from the source rocks and orebodies are always coupled and interfered with each other.This is challenging to directly delineate the target area for the deep magnetite orebody from the original map of aeromagnetic anomaly.Previous studies show that potential field separation technology is an effective approach to extract ore-caused anomalies.However, there are many potential field separation methods and they are all different, in terms of operation convenience and different results of extraction.In this paper, we systematically compared and analyzed the convenience of six commonly used separation methods, and evaluated the effects of extracting ore-caused anomalies from both the whole and target regions.Consequently, we established the theoretical model and verified the feasibility extracting the deep ore-caused anomalies based on the geologic background of the Qihe area, Shandong.At the end, we recommend using the marker profile line to verify the extraction effect of ore-induced anomalies when the measured data were processed.The ore-caused anomalies extracted agree with the known drilling data, indicating a strong correlation between the extracted and realistic anomalies.This study provides a reference for future delineation of target ore fields and laying-out of drilling locations.

Key words: sinoprobe, magnetite, aeromagnetic survey, potential field separation, delineation of target areas

中图分类号:

P318.63

高秀鹤, 于长春, 李行素, 葛藤菲, 何敬梓. 深源矿致异常提取方法对比及应用: 以山东齐河—禹城地区航磁数据为例[J]. 现代地质, 2024, 38(01): 25-34.

GAO Xiuhe, YU Changchun, LI Xingsu, GE Tengfei, HE Jingzi. Comparison and Application of Extraction Methods for Aeromagnetic Anomaly Caused by Deep Magnetite: A Case Study of the Qihe-Yucheng Ore Area, Shandong[J]. Geoscience, 2024, 38(01): 25-34.

图/表 13

图1 去延拓场滤波器的频率域响应函数

Fig.1 Schematic diagram of the method showing removing the upward continuation field filter

图2 高通滤波器的频率域响应函数

Fig.2 Schematic diagram of the method showing high pass filter

图3 匹配滤波器的频率域响应函数

Fig.3 Schematic diagram of the method showing matched filter

图4 理论模型及正演磁异常(h=200) (a)模型水平切片z=1.1 km; (b)模型垂直切片y=15 km; (c)模型垂直切片x=14 km; (d)模拟模型产生的航空总磁异常强度ΔT; (e)模拟仅岩体产生的航空总磁异常强度ΔT; (f)模拟仅矿体产生的航空总磁异常强度ΔT

Fig.4 Diagrams of the theoretical model and forward magnetic anomaly (h=200 m)

图5 位场分离得到的区域场图 (a)去延拓场法; (b)高通滤波法; (c)匹配滤波法; (d)算术平均法; (e)高斯平滑法; (f)插值切割法

Fig.5 Diagram of the regional field obtained by potential field separation

图6 位场分离得到的矿致异常图 (a)去延拓场法; (b)高通滤波法; (c)匹配滤波法; (d)算术平均法; (e)高斯平滑法; (f)插值切割法

Fig.6 Diagram of the local field obtained by potential field separation

图7 东西方向上的矿致异常主剖面曲线图(y=15.1 km)

Fig.7 Diagram of main profile showing the ore-caused anomalies in the east-west direction

表1 各方法提取的矿致异常与理论矿致异常的均方根误差(RMSE)

Table 1 Errors of ore-caused anomalies for all extraction methods (RMSE)

	去延拓场法	高通滤波法	匹配滤波法	算术平均法	高斯平滑法	插值切割法
全区	12.7131	5.7175	5.0571	5.4365	5.7794	5.6875
靶区	29.7301	4.4138	5.2610	4.5814	5.4659	5.7606

图8 齐河地区实测航磁数据及化极结果 (a)实测航磁数据; (b)化极结果

Fig.8 Diagrams of aeromagnetic data measured in the Qihe area and the results of reduction to pole

图9 齐河地区实测航磁化极数据位场分离得到的区域场 (a)高通滤波法;(b)算术平均法

Fig.9 Diagrams of regional field obtained by the potential field separation in the Qihe area

图10 齐河地区实测航磁化极数据位场分离得到的矿致异常 (a)高通滤波法; (b)算术平均法

Fig.10 Local field of ore-caused anomalies obtained by potential field separation in the Qihe area

图11 齐河地区实测航磁数据位场分离区域场、矿致异常的剖面曲线图(剖面位置如图8中白线所示) (a)(c)分别是高通滤波法、算术平均法得到的区域场(黑色线为原场,橘色线为区域场); (b)(d) 分别是高通滤波法、算术平均法得到的矿致异常

Fig.11 Profile diagrams of ore-caused anomalies in the potential field separation area of aeromagnetic data measured in the Qihe area

图12 截取李屯岩体地区矿致异常及钻孔位置示意图 (a)高通滤波法;(b)算术平均法

Fig.12 Schematic diagrams of ore-caused anomalies in the Litun area and the drilling positions

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