Earlier speculation about why the applications north of...

Earlier speculation about why the applications north of EAL1/Luni/P2 were pegged was given in this post.

Like much of the work done in this area it was preliminary. The discovery of Carbonatites and (perhaps) lamprophyres recently shows there is much to be learned about this largely under cover area.

Government surveys have been upgrading their knowledge of the area with publications coming out over the last decade or so.

Of particular interest to the West Arunta area are investigations into the various sub basins of the Centralian Superbasin with work done both in WA and the NT.



Summary power point presentation for the work by Haines et al 2017.

Coincidence that ENR's projects appear to track the margins of sub basins?

An old adage from exploration is that deposits are located at the corner of 4 map sheets. Add in a state/territory boundary and a near certainty of finding something under that concept LOL. Does make it tricky to get maps to meld together especially when some were made in the 1950s.

These papers focus mainly on the Murraba basin which lies just north of EAL1/Luni.

1 Haines et al 2017 Paper.
2 Ahmad et al NT side of Murraba Basin.
3 Haines et al abstract to presentation.
4 Joly et al West Arunta geology/geophysics.


The four corner issue writ large with geology in SW from Joly, NW by Haines and to east by separate 250K map sheets of NTGS. Outline of the Murraba Basin in White dashed line (plus faulted contacts.
Some 90+% of the recent ENR applications plot within the Murraba Basin and the underlying Hidden Basin Beds.



Samples collected from EAL001 are significantly older than the Murraba Basin sediments. The jury is still out on the age of the Hidden Basin Beds but they also may be too young to host Olympic Dam age intrusives at Surface. Sub surface is another matter though with 2000+-m of sediments depth is likely to preclude cheap exploration.



Haines et al (2017) re-interpreted the statigraphy of the Hidden Basin Beds.
The Munyu Sandstone "type section" is located ~70Kms ENE of EAL 1 (Haines p9).



The Munyu sandstone unit represents the base of the Murraba Basin sequence and is assigned a date around 1000 Mya - some 5-600 My younger than the dates from EAL001.

Other basins are found in the Centralian Superbasin and attempts have been made to correlate with the most likely being the Amadeus and Murraba basins. Rocks of similar age to these are found near Telfer (Paterson/Yeneena/Lamil).

I added Browns Range and Cummins Range carbonatites to the WA side of the border and Nolans to the East. The question I had for this was what could be the exploration potential be in the Murraba if Browns/Cummins were of that age.
Not the case for Browns Range (C1646 Mya) though some hydrothermal effects may distort this.
Hidden Beds are correlated with Birrindudu Basin seds of similar vintage to Browns Range.



Cummins Range on margin of Neoproterozoic?

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Gravity draped on first vertical derivative from Geoscience Oz portal to show the trend of major structures ENE of EAL001 along the Elephant Island Fault trend (and Parallel structures?) on the ground applied for by M&M Walter Consulting (Red). P2-Hosche(EAL1) 20+ Kms. 10 Kms E1 to Luni!


Simplified margins of different units + faults in solid black.
White Murraba
Dark blue Arunta orogen from Haines et al.
Black Carrington suite NTGS
Red Hidden Basin Beds.

Most geology is interpreted from the magnetics and gravity with some input from the limited outcrop. Joly et al (2013) is a good example.

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What does it all mean?
Lots of space and targets to be looked at.
Unless there is something surprising the Murraba and Hidden Basin units are not obvious targets for REE/Nb IMO.
ENR and others pegged the ground and on strike for a reason which will be revealed in due course.