A comparison of the joint and independent inversions for magnetic and gravity data over kimberlites in Botswana
A comparison of the joint and independent inversions for magnetic and gravity data over kimberlites in Botswana
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DOI：
10.1111/1365-2478.13265
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发表时间：
2022-09
影响因子：
2.6
通讯作者：
S. Vatankhah;R. Renaut;K. Mickus;Shuang Liu;Matende Kitso
中科院分区：
文献类型：
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作者：
S. Vatankhah;R. Renaut;K. Mickus;Shuang Liu;Matende Kitso
互补的独立和联合聚焦反演调查适用于磁和重力数据集的两个金伯利岩管，BK 54和BK 55，在博茨瓦纳。磁测数据的分辨率很高，清楚地显示了勘查区的两个异常。该磁力数据的独立反演提供了地下的聚焦图像，其中两个管道的边界都很清晰。管道的延伸距离接近该地区现有钻孔的估计距离。另一方面，重力数据的空间分辨率相对较差。BK54井在剩余重力异常上没有出现，而BK55井则表现为正异常。重力数据的独立反演提供了BK55的几何形状，但不能识别BK54管道。虽然在BK54管道的地方有一些密度较低的材料，但没有发现具体的目标。此外，相关的是，BK55的重建模型没有聚焦。基于构造交叉梯度联动的联合聚焦反演被应用于重磁组合数据集。该算法产生结构相似的磁化率和密度模型。BK54管的材料密度分布较低，与磁化率分布相似。此外，与通过独立反演获得的结果相比，BK54的结构在深度上是连接的，并且BK54和BK55的重建模型共享稀疏性。这些模型不像独立获得的磁化率模型那样稀疏，但它们比独立获得的密度模型更集中。一个全面的比较重建的模型，也计算CPU时间，独立和联合反演。
Complementary independent and joint focusing inversion investigations are applied to the magnetic and gravity datasets for two kimberlite pipes, BK54 and BK55, in Botswana. The magnetic data are high resolution and, clearly, indicate two anomalies in the survey area. Independent inversion of this magnetic data provides a focused image of the subsurface with sharp boundaries for both pipes. The extensions of the pipes are close to those estimated by the available boreholes in the area. The spatial resolution of the gravity data is, on the other hand, relatively poor. The BK54 pipe does not appear on the residual gravity anomaly, while the BK55 is characterized by a positive anomaly. Independent inversion of the gravity data provides the geometry of the BK55 but does not identify the BK54 pipe. While there are some lower density materials in the place of the BK54 pipe, no specific target is revealed. Furthermore and relevant is that the reconstructed model for BK55 is not focused. A joint focusing inversion based on the structural cross‐gradient linkage is applied for the combined gravity and magnetic datasets. This algorithm produces structurally similar magnetic susceptibility and density models. A lower density distribution of material, similar to that of the magnetic susceptibility distribution, is revealed for the BK54 pipe. Moreover, in contrast to the result obtained by an independent inversion, the structure for BK54 is connected at depth, and the reconstructed models of BK54 and BK55 share the sparsity. The models are not as sparse as the magnetic susceptibility model that is obtained independently, but they are more focused than the independently obtained density model. A comprehensive comparison of the reconstructed models, and also computational CPU time, for independent and joint inversions is presented.