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TitleEvaluation of the efficiency of several airborne electromagnetic systems: exploration implications
AuthorCheng, L Z; Smith, R S; Allard, M; Keating, P; Chouteau, M; Lemieux, J; Vallée, M A; Bois, D; Fountain, D K
SourceExploration and Mining Geology vol. 18, no. 1-4, 2009 p. 1-12,
Alt SeriesEarth Sciences Sector, Contribution Series 20080404
Mediapaper; on-line; digital
File formatpdf
Lat/Long WENS-79.5000 -79.0000 48.5000 48.2500
Subjectsgeophysics; economic geology; geophysical surveys; magnetic surveys; e m surveys; e m surveys, airborne; mineral occurrences; mineral potential; mineralization; Aldermac deposit; INPUT; GEOTEM; MEGATEMII
Illustrationslocation maps; plots; profiles
ProgramTargeted Geoscience Initiative (TGI-1), 2000-2003
Released2010 02 08
AbstractA comparison of data from INPUT, GEOTEM, and MEGATEM airborne electromagnetic (AEM) systems over the Aldermac deposit, Québec, Canada, was undertaken to evaluate the relative efficiency of these systems for the detection of small, deep conductors. The Aldermac orebody was mined between 1933 and 1934 to a depth of 200 m. A deeper mineralized zone was discovered in 1987. The MEGATEMII system was used to acquire 90- and 30-Hz data over the deposit in 2003 as part of a research project. These MEGATEMII data were compared with data acquired by other AEM systems (GEOTEM and INPUT), and the results show that the MEGATEMII response is ten times larger than the other systems. For the dB/dt response, 30 Hz gives a better signal-to-noise ratio, whereas 90 Hz has a better signal-to-noise ratio on the B-field.
The data were evaluated by numerical modeling. The deposit was best represented by a complex model, comprising two weakly conductive bodies to approximate the alteration halo, two deeper prisms representing known orebodies, and three bodies ranging in thickness from 3 to 6 m and in resistivity from 12 to 20 ohm?m, representing the chargeable overburden. This implies that the MEGATEMII system is able to see a small conductive body at more than 200 m depth in an area where the response is contaminated by conductive overburden.