| |
Detailed discussion of results from one line
Recovered 1D resistivity structure along the survey line is shown below. Note that vertical exaggeration is 3:1. See the image on the introduction page for an annotated version with no vertical exaggeration.
Here are comments comparing recovered geophysical models with known geological features.
- There is a surface conductive layer of approximately 5 to 10 metres depth, probably the result of reworked surface material from alluvial mining. There is some topography which is associated with this layer.
- The resistive basement is archean greenstones containing some sulphides.
- Between the thin surficial conductive layer and resistive basement, there is a weathered sapprolite layer of varying thickness.
- From 21900E to 22300E the conductive layer at the base of the weathered layer can be described as a mixed zone in the weathering profile where the sulphides associated with mineralization have produced acid at the bottom of the weathering profile, which has not yet been flushed by meteoric water.
- The strong conductive features at the 22000 end of this layer are associated with sulphide mineralization. It probably does not extend to depth but is restricted to the layer above the bedrock.
Inversion results along four different lines
This final figure shows four lines from the same property, each separated by 200 metres. Note that the colour scale is reversed compared to the first figure. White regions coincide with surface ponds, where data could not be acquired. Recall that the objective function in the inversion penalizes variation of conductivity in the vertical direction so existing layer boundaries are likely imaged as transition zones. Nevertheless, in these examples the large contrast between sapprolite and the resistive basement shows up as a reasonably well defined boundary. Also the overburden layer has been reasonably well defined and its variability and depth have been verified by subsequent drilling.
~ ~ ~
| © UBC-GIF
January 9, 2007
|
|
|
|
|
