Focusing in on your questions - sorry for repeating things just easier. Could you expand on why you believe that the intrusions are felsic not carbonates? Previous post was an attempt.
I am not a geologist and do not know much about felsite beyond a look at wikipedia and reading that they form from volcanic ash.
Felsite? Did you mean felsic? The Durlacher Supersuite apparently has a wide range of intrusives - I don't know exactly what, but Dean Tuck of DRE said that there are many and they have variable magnetic signatures (latter my comment based on some hints from him). His, DTs, off the cuff comment about the magnetic features in the Lyons (LNR) area was that they were granitic or similar. Hence my post above trying to come to grips with apparently conflicting ideas.
I have been wondering what the magnetic susceptibility could be showing other than carbonatite intrusions.
Can't comment much on that as it is a complex modelling issue which is presented by FP and LNR geophysicists. Granites come in so many magnetic guises that I doubt mag sus would be definitive enough to separate from other species of rock. The lack of carbonatite outcrop at surface on Lyon/LNR is a problem for the model but exploration is still very early. Gravity could be useful as a method to distinguish granite (SG often 2.7+-) versus fresh carbonatite 2.85 from some source I saw. Probably enough difference even if subtle.
From my research, dykes and fenetised rock often occur within a 5km radius of the intrusive source.
Fenitisation seems to be a local alteration around dykes and perhaps in the centimetres to tens of meter range.
The ironstone dykes are wide spread at Gifford Creek (= Yin Yang and Lyon areas for a collective term not related to any company). This does suggest multiple carbonatites are present which may include the magnetic features on Lyon/LNR as announced.
Some ideas that need checking. To attribute all the ironstones in the area to the known carbonatites may be a step too far though could be possible. The reported ironstones are not consistent with a radial distribution around the interpreted Lyon/LNR carbonatites.
Since Hastings has stated that it looks there is an unfound source of their mineralisation, I’ve agreed with LNR’s assumption that these are carbonatite intrusions. I would reserve calling them carbonatites until the EIS drilling confirms them. The 3D magnetic shapes are fascinating. If accurate they may be one of the reasons these are called carbonatites. That they have been eroded at Bald Hill (BT comment) I find a bit too convenient an explanation as to why they are missing in one area and present less than 5 Kms away. Possible though makes one wonder how such a difference would occur in what is considered an area impacted by the pull apart basin. DRE's mapped carbonatites are small. The overall magnetic signature is significant and could just be the tip of an iceberg. HAS have not reported any but missed the magnetic signature that was on the edge of their mag/radiometric survey in 2016 so there is room for wiggle on finding more. Also the possibility of multiple styles of different vintage.
Getting repetitious and beyond even my level of HC post.
Tossing out some thoughts which may not survive long. As I said fence sitting on this one.
Hope everyone gets some carbonatites which apparently have around a 1 in 10 chance of being economic. DRE at 7 LNR at 3+ monsters if real.
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