ENR poormans WA1, page-65

@U3O8_Wave

Some very dense reading for weekend consumption.

Way above geology 101 and more an indulgence for me as it is way beyond the average HC post and takes me to topics that I have seldom understood well, if at all.

The boffins at ENR and WA1 have access to better data.


The term imbricated probably defines the style of faulting your diagrams show. Link to google images - complex structures. There is probably no single structural explanation as the area has probably had a complex history with the latest leaving, perhaps, the most obvious traces.

WA1 have been leaving breadcrumbs about the geology, geophysics, geochem, drilling in their announcements which often overlap with ENR tenure.

Some diagrams fromWA1's prospectus:

Interpreted regional geology

The yellow Neoproterozoic sediments (Prefix Neo = "younger" which means an age range of ~540-1000 Million years ago within the protoerozoic that ranges from 538-2400+-Mya (neo, meso (1000-1600), palaeo (source Wikipedia))) are the main unit and commonly occupy areas of low magnetic responses. The Neoproterozoic seds are in turn overlain, locally, by more recent units including those of the Canning Basin.
Units below it (lower right) are progressively older - see stratigraphic column below.

The blue arrow shows the apparent left lateral movement that may have occurred displacing the grey and 'bluish' units. Some other apparent displacements are consistent with this.
Detail of the magnetics south of Luni can also be interpreted to show this style of displacement with some possible drag folds evident.





More detail geology


Not easy to distinguish the colour codes. There is relatively little actual outcrop available which means a lot of photo and, more likely, magnetic interpretation are needed to fill in the gaps.

The Lake Mackay quartzite is almost a marker unit which shows up as the grey unit in the bedrock interpretation map (above). Question for geophysicists - is there a definitive magnetic pattern for this quartzite unit. I find it difficult to differentiate from the general magnetic patterns.

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Some more detailed geophysical images are shown in WA1 data.
Gravity:
Luni/Sambhar and Urmia areas
Note this is an 800x enlargement from the original - survived this very well.


Schematic locations for drill holes.
2010 drill hole was an EIS hole - first drilling in the whole area. Considered an economic failure for Cu/Au and major alteration. REE and Nb may not have been on the assay suite.
Q for geophysicists. Comparison of mag and gravity give significant differences. While not unusual what is going on?





Various surveys.

Different surveys give different resolutions. The one in the bottom left is either different or has been processed differently giving more fine detail. Residual gravity (lower right) has much less resolution than the first gravity image above.
ENR are doing a mag/radiometric (Rmx) survey which IMO will yield images like the one in the lower left for magnetics. What the Rmx will show could be a bonus.
Geochem has been done with some intriguing results both in the Urmia/Radiator area and at Pachpadra more recently by WA1. [P2 was not considered suitable for first pass soils but...maybe worth an orientation survey now.

Interestingly the first drill announcement (18/8/22) of visuals did not mention carbonatites.

“Preliminary visual observations have interpreted the presence of wide zones of hematite alteration, consistent with the model for an iron-oxide copper-gold (IOCG) style mineralised system. Drill samples have been submitted for analysis and detailed geochemical and geological interpretations are also underway" P Savich.

The last sentence is the key with carbonatite being announced at P2 though no detail is given (?). REE, P2O5 Nb probably the key elements with hematite alteration masking the host lithologies until some petrographic or lithogeochem work can distinguish them.

[In China Bayan Obo (major REE deposit) has been known, and mined, for around 100 years. There is still active debate as to whether it is a carbonatite! Suspect the carbonatite faction is in ascendancy now with detailed chemistry available.

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Implications for ENR are fairly obvious in this statement from WA1:

The identification of mineralised carbonatite intrusions is a significant finding for the West Arunta region. The Company has multiple untested targets within the region and the potential for further discovery with future exploration efforts has been greatly enhanced by the results from Luni and P2.

ENR are adjacent and perhaps along strike from both these carbonatite discoveries.

However, there are many structural complexities combining with the possible near random placement of what are probably intrusive carbonatites which means 'the game is afoot'.
Geophysics and drilling will be the main way going forward with no guarantee any more mineralised zones/carbonatites will be found. Worth some effort for sure.