3D correlation tomography inversion of gravity anomalies constrained by edge features and depth weighting
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摘要: 相关成像作为一种利用相关系数定性解释地质体空间位置的快速成像方法, 其不需要求解大型方程组就能够快速高效地得到地下异常体的分布, 具有计算方法简单稳定、计算速度快的优点。但是重力异常直接相关成像的结果存在深部发散、深度加权函数参数过多以及异常体之间横向分辨率和纵向分辨率低的问题。本文根据重力异常三维相关成像反演的基本原理, 引入重力异常均衡垂向导数和均衡解析信号振幅作为边缘特征对重力异常相关成像进行水平加权, 并且提出了一种更为简洁的深度加权函数。通过一系列的模型试验证明重力异常边缘特征约束提高了相关成像的横向分辨率; 使用新的深度加权函数提高了相关成像的纵向分辨率。最后, 将本文方法应用到澳大利亚Olympic Dam多金属矿区的实际资料中, 加权成像的结果与实际地质资料相吻合, 证明了该方法的正确性和有效性。Abstract: Correlation tomography is a fast tomography method using correlation coefficients to qualitatively interpret the spatial positions of geobodies. This method, featuring simple, stable, and fast calculations, can quickly and efficiently obtain the distribution of subsurface anomalies without solving large equations. However, the results of direct correlation tomography of gravity anomalies display deep divergence, excessive depth weighting function parameters, and low lateral and vertical resolution between anomalies. According to the fundamental principle of 3D correlation tomography inversion of gravity anomalies, this study introduced the balanced vertical derivative and balanced analytic signal amplitude of gravity anomalies as the edge features to horizontally weight the gravity anomaly correlation tomography, and proposed a more concise depth weighting function. As demonstrated by model tests, the lateral resolution of correlation tomography was improved under the constraint of gravity anomaly edge features, and the vertical resolution of correlation tomography was enhanced using the new depth weighting function. Finally, the method in this study was applied to the actual data of the Australian Olympic Dam polymetallic deposit, yielding consistent weighted tomography results with the actual geological data, thus proving the correctness and effectiveness of the method.
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Key words:
- gravity anomaly /
- correlation tomography /
- horizontal weighting /
- depth weighting /
- edge features
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