Publication GSC6

Deep electromagnetic imaging of the Bathurst No. 12 deposit: 3-D forward modelling, 2-D inversion and sensitivity tests

Queralt, P., A.G. Jones and J. Ledo


A detailed three-dimensional (3-D) numerical electrical resistivity model of the Bathurst No. 12 deposit (New Brunswick) has been constructed using available geological and geophysical information. This model facilitates studies of the capabilities of audio-magnetotellurics (AMT) at locating and defining mineral targets at depth, and of methods of optimizing data acquisition. Different conditions were analysed: presence of overburden, dimensions and positions of the orebody, and varying data sampling. The behaviour of 3-D electromagnetic fields are compared with ones from a body of infinite length extent (a two-dimensional case). The 3-D and 2-D AMT responses are similar at high frequencies, so 2-D modelling is sufficient. However, at low frequencies only those responses for current flow perpendicular to the body (the Transverse Magnetic mode) are reasonably alike. The sensitivity tests show that an optimized cost-effective field experiment would be with fixed magnetic sensors and roving electric ones.


Geol. Surv. Canada Current Research, , 2002-D3, 8 p., 2002.

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Alan G Jones / 10 June 2004 /