Ann: Major Greenfields Drilling Programme Commences, page-14

Hi Onceover,
As part of some musings about the lead up to this year's field programs:

I have been mulling over your Q with respect to early mid time anomalies. Partly because you sound optimistic about them whereas my understanding was that late time anomalies test to greater depth and are often attributed to "better" conductors.

"Better" does refer to geophysical response which may, or may not, mean better in economic mineral content. There don't appear to be many (any) contributors with strong geophysics backgrounds on these forums - might be that the math needed to explain WHY would freak most - your's truly included.- readers.

This intro from a paper (Macnae 2013) on early and late AEM probably gives enough information for purposes of this post.



I don't know how good the analogy is but the way whales communicate over long distances has to do with the frequency of their "sonar". Different frequencies enable variable penetration and definition.

The anecdotal report that Winu was a "poor", possibly formational AEM target means it is not wise to ignore even poor, wide, early whatever conductors in this environment.

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The background magnetic maps used for the recent 2019 Citadel and the London 121 presentation are much more detailed than any I have seen before.
Keeping to the 100% AZY NW claim block for the moment the amount of detail puts some of the AEM targets in some sort of context that, imo, was lacking previously.


Versus:

Plotting the AEM anomalies as narrow linear wiggles (40-42) allows the underlying mag to show through. [The location, shape and detail is only approximate enough to give some broad ideas about the targets.]

The coincidence of mag and AEM is, IMO, not great. There are some minor local blips but the AEM targets are not obviously strong magnetic targets. Plotting the Winu drilling approximately on the mag map gives these images:



Below is this slightly more accurate plot of the drilling.using mag data from the Citadel JV proposal [which does a good job of masking the Winu mag pattern].




How do the Winu anomaly and AEM on 100% AZY ground to the NNW correlate?

• Winu is apparently structurally controlled [perhaps by a feature parallel to the prevailing NW faults and ?dykes.]
• The axis for the Winu drilling roughly corresponds to the broken mag linear (dyke?) going NW towards AZY's "new" AEM anomaly 43.
• IMO there are two airmag surveys "stitched" together between Winu and 43. The lower resolution (my term).
• There are subtle magnetic features in this "low resolution area" for which Rio will have data.
• This magnetic linear is similar (but weaker) to the feature that cuts Havieron. . [ARV targets along a more contiguous magnetic feature going N from Havieron].
• Not clear but could be a subtle mag blip coincident with 43.
• AEM 40 appears to be off the main trend but close enough to have possibilities. There is a significant "mag blip" about half way along 40 but seems more N-S than the main AEM trend of 40.
• There are many ways to process and present magnetic data. The above gives only one viewpoint. Magnetic (and other geophysical) inversion presentations could be useful.....
• I suspect the large magnetic features on AZY's 100% ground would resolve into reasonable sized bodies perhaps related to intrusives.
• The magnetic detail on these features shows linear features which may be fault boundaries. If the intrusive interp is reasonable then they would cross cut the NW trend and timing becomes important.
• Have Rio contributed to the AEM anomaly data on AZY ground?? Rio would have covered this section with nearly every reasonable geophysical method. Share????

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True weekend musings. Apologies for the shotgun approach as it evolved from some research into the GAIP surveys planned for Citadel this year. A separate post for tomorrow perhaps.