The geophysical study of Drybones kimberlite using 3D Time Domain EM Inversion and 3D ZTEM inversion algorithms
The geophysical study of Drybones kimberlite using 3D Time Domain EM Inversion and 3D ZTEM inversion algorithms
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使用 3D 时域 EM 反演和 3D ZTEM 反演算法对 Drybones 金伯利岩进行地球物理研究
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
D. Oldenburg
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文献类型：
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作者：
V. Kaminski;D. Oldenburg
摘要 在加拿大西北地区的 Drybones 金伯利岩上进行了两次机载电磁勘探。 Geotech 于 2005 年进行了 VTEM 直升机时域电磁调查，随后于 2009 年进行了 ZTEM 直升机自卸式电磁调查。 Geotech, Ltd 首先对金伯利岩上收集的数据集进行了反演和解释，对 VTEM 数据使用一维 TDEM 电导率深度变换，对 ZTEM 数据进行二维反演。将数据集传输至 UBC-GIF 进行 3D 反演和比较分析。 VTEM 和 ZTEM 数据现已进行 3D 反演，并将结果与金伯利岩上的钻探数据以及先前地球物理解释的较旧结果进行比较。 2D 和 3D ZTEM 反演显示相同的总体结构，但 3D 反演具有更大的电导率对比度，并且在低灵敏度区域中可能具有更少的伪影。在大尺度上，从时域数据的 3D 反演恢复的电导率结构与 CDI 变换的电导率结构相当，但 3D 结果显示了更复杂的电导率分布。 3D 磁力反演以前从未进行过，它显示了大约 400 m 深度的易受影响的物质，这与金伯利岩的已知几何形状一致。
Summary Two airborne EM surveys were conducted over the Drybones kimberlite, NWT, Canada. A VTEM helicopter time domain EM survey was flown by Geotech in 2005, followed by a ZTEM helicopter tipper EM survey flown in 2009. The data sets collected over the kimberlite were inverted and interpreted first by Geotech, Ltd using a 1D TDEM conductivity-depth transform for VTEM data and a 2D inversion for ZTEM data. The data sets were transferred to UBC-GIF for 3D inversions and comparative analysis. Both the VTEM and ZTEM data have now been inverted in 3D and the results compared with the drill data over the kimberlite and with older results of previous geophysical interpretation. The 2D and 3D ZTEM inversions show the same general structure but the 3D inversion has greater electrical conductivity contrast and may have fewer artefacts in zones of low sensitivity. On a large scale the conductivity structure, recovered from the 3D inversion of time domain data, is comparable to that from the CDI transform, but the 3D result shows a more complicated distribution of the conductive properties. The 3D magnetic inversion had not been done previously and it shows susceptible material to depths of approximately 400 m, which is consistent with the known geometry of the kimberlite.