a little bit of balance., page-10

Wortza

That comment is in reference to the inherent uncertainty associated with potential field modeling and inversion.

(skip to the end if you dont want to read the detail)

Potential field geophysical modelling is based on 2 main constraints.

1. Observed Geophysical response (magnetics and gravity in this case). This is basically the recorded geophysical response preserved in the final survey. Its the natural geophysical response of the rocks.

2. Geological information - inclusive of surface mapping and drill hole logs.

And 2 major variables.

1. Geophysical attributes - (magnetic suceptability and density) for different rock units. In the case of magnetics rocks with a mineral called magnetite will have a high magnetic response while those with low magnetite will have a low response. The geophysical modeller needs to assign sensible values based on known results from assumed rock types. These are documeted by various authors.

2. Geometry of the bodys. This is the shape of the different geophysical bodies (hopefully equivelant to geology!) in the earth.

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Without good constraint on the geology and acutal geophysical response of the units there is increased model uncertainty. In short, there can be many different model answers to generate the observed geophysical survey response.

While it could be argued that the "bulk of the magnetic components of each feature are ≥ 250 m" represents the extent of oxidation (magnetite becomes heamatite = demagnetisation) I dont think its likely as its so deep!
The modelled pipe like geometry is a good thing as at least the body sounds like its an intrusive!