Developing an efficient modelling and data presentation strategy for ATDEM system comparison and survey design
Magdel Combrinck26 Rocky Ridge Heights, Northwest, Calgary, Alberta, Canada T3G 4J6. Email: magdel.tau@gmail.com
Exploration Geophysics 46(1) 3-11 https://doi.org/10.1071/EG14026
Submitted: 13 March 2014 Accepted: 8 August 2014 Published: 1 October 2014
Abstract
Forward modelling of airborne time-domain electromagnetic (ATDEM) responses is frequently used to compare systems and design surveys for optimum detection of expected mineral exploration targets. It is a challenging exercise to display and analyse the forward modelled responses due to the large amount of data generated for three dimensional models as well as the system dependent nature of the data. I propose simplifying the display of ATDEM responses through using the dimensionless quantity of signal-to-noise ratios (signal:noise) instead of respective system units. I also introduce the concept of a three-dimensional signal:noise nomo-volume as an efficient tool to visually present and analyse large amounts of data. The signal:noise nomo-volume is a logical extension of the two-dimensional conductance nomogram. It contains the signal:noise values of all system time channels and components for various target depths and conductances integrated into a single interactive three-dimensional image. Responses are calculated over a complete survey grid and therefore include effects of system and target geometries. The user can interactively select signal:noise cut-off values on the nomo-volume and is able to perform visual comparisons between various system and target responses. The process is easy to apply and geophysicists with access to forward modelling airborne electromagnetic (AEM) and three-dimensional imaging software already possess the tools required to produce and analyse signal:noise nomo-volumes.
Key words: airborne electromagnetics, modelling, survey design, visualisation.
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