Hi Inky,
Some weekend reading.
Saw a webinar from RNX during the week. Fascinating target at Mongoose deeps.
IMO it is fundamentally different to Perce on a
geophysical basis. Gravity only vs "coincident" strong gravity and
STRONG mag for Mongoose.
Geologically is another matter. Local detail for Perce is not available so regional it is with lots of jargon unfortunately. The general approach will be what a company might undertake.
Geol 301+ level discussion of the Northern Australian Craton with a focus on Mt Isa area.
This link to a 2021 EGRU video will send me back to text books to understand many of the terms used.
Lots of 'pretty' images the result of a huge effort by multiple organisations based around the economic geology of the area. A quick scan of parts of the video will show how, relatively, neglected the West Arunta is (or seems to be).
Details aside, the age of rocks is similar at Cloncurry and West Arunta.
Regional Mt Isa
Local stratigraphic column for
the Cloncurry 1:100K mapping below. No need to see the the text, just realise how much detail was available from surface mapping some 10 years ago vs what is below for ENR's area.
Not surprising given exposure and many years of mapping combined with significant mineral deposits to encourage research. Beginning now at Lake Mackay area.
Ernest Henry deposit is hosted by the Mt Constantine volcanics c 1740 (age of mineralisation less clear perhaps 1540-1500 Mya granite intrusive related IOCG).
Mt Webb GSWA 2014 West Arunta area.
The level of detail for the "Cloncurry" Chronostratigraphy highlights the difference of research done compared to Mt Webb/West Arunta. There will have been more work done in the West Arunta since the above though beyond my current research.
Another image from the EGRU video shows a subtle change in the age of the Chewings orogeny and Reynolds Range
[West Arunta as used in the above snip may be different to the way WA1/ENR generally use it.] Probably extends further east into the NT but interesting to see the age for Chewings Orogeny matching aspects of EAL1 dating.
Stepping back to what the Northern Australian Craton comprises, to some, in the EGRU video.
While Cloncurry and West Arunta/Aileron has rocks of similar ages they formed in different areas and have undergone a complex history as blocks that have been moved together and apart to arrive at the current configuration. Getting closer but a work in progress and subject to much discussion.
One construction that shows that Aileron and Cloncurry very different. Doesn't mean Perce geology will be substantially different. Zero hard geological evidence for what is at Perce until there is a drill hole. Geophysics can produce a range of models from the gravity that ultimately need to be tested.
RCR's Avalon, and Luni have been shown with inversion modelling but not presented for Perce, or others, though likely to have been done IMO.
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For fun this first vertical derivative image GA portal where multiple imagery is available.
ALL
CLONCURRY
Mongoose is part of the white blob at this scale. Patterns around this area more linear than Luni/Crean ?
AILERON WEST ARUNTA ENR etc
The major difference might be the level of metamorphism in the ENR/WA1 area. There is evidence of some stratigraphic control with linear features and local folding. Would be interesting to see a geophysicists interp with better resolution data.
Perce is possibly outside one of the possible fault blocks that make up the main part of ENR/WA1/AMN ground.
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An attempt playing at it
1 Probable fault bounded blocks extending from west of Crean/Luni to a little east of Perce. Rotation of blocks, vertical and lateral movements all need to be reconciled to give a complete picture. Beyond my pay grade if even real.
2 North of Crean magnetic trends are NS. Why?
3 West to P2 is a slightly different pattern which greys out to the west (?)under deeper cover.
4, a, b To the east the pattern becomes progressively more irregular and stretched out. Why? Metamorphic grade/depth/structure????
5 Possible large intrusive body.
6 Gneissic terrain? with hint of sediment to north
7 Possible fault bounded area with limited magnetics
8 Hidden Basin Beds - sediments. Southern margin dextral fault??.
9 Southern magnetic feature with Central Australian Suture a prominent EW linear with swirling patterns (folding +- intrusives??) of magnetics prominent to the east.
Geo interp - imagine what a geophysicist could do. Add on multi layered research as has happened around Mt Isa and a new story will emerge. Aspects of the old will be there but more fleshed out with some major changes.
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RCR detail came out of the above work.
Red dot is Pokali Cu +- Au/REE? which does appear to be a separate magnetic entity. Large low grade (IMO) Cu deposit shaping up.
Orange dot estimated location of Avalon gravity mag anomaly likened to Luni. Magnetics more prominent than Luni at this scale. Interesting drill target.
(20min delay)