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There is very little data processing required before resistivity and induced polarization data can be inverted. However, it is normal to plot raw results as conventional pseudosections so that preliminary interpretations can be made. This is important for assessing data quality, and for anticipating geology that should be visible on inverted sections. Also, plotting raw data is important for identifying any readings that may need additional errors assigned. This can happen, for example, at locations where it was difficult to get adequate electrode placements in the field. Figure 1 below shows pseudosections of data gathered along line 47000E at the Century deposit. Red resistivities are relatively low values (units of Ohm-m), while red IP phase represents the high chargeabilities (units of milliradians). Bodies of high chargeability are observed, but details about horizontal location and depth are difficult to infer from the pseudosection.
Figure 1. Pseudosections of apparent resistivity (units of Ohm-m) and apparent chargeability (units of milliradians). Note the vertical scale is not in meters because plotting position is an artifact of the pseudosection. |
Before running inversions, resistivity data must be supplied in terms of the measured potentials (normalized by transmitter current). Chargeability can be supplied in units of msec, mrad, or as a dimensionless quantity. In addition, some assessment of the error associated with each datum is required. It is recommended that less reliable data points be assigned larger values for their estimated standard deviations based on the interpreter's judgement of data quality.
 home © UBC-GIF
April 23, 2007
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