I was wondering where some of the geology interpretation came...

I was wondering where some of the geology interpretation came from as drilling doesn't give complete coverage (if any) of the phoscorite, mafic and aspects of the complex.

Putting the outlines of the zones in the map onto the 2023 infill gravity (+magnetics) gives an answer.


The phoscorite represent magnetic highs that influence the shapes.

Detail from the above image showing western Luni

Colours are gravity (white high to reds etc) and contours magnetics.

The gravity is a perfect fit for the interpreted carbonatite. Not too surprising as the interp represents a combination of gravity/logging and geochem. However, is it too close a fit?

No drilling(?) into the mafic unit with might reflect a subtle mag feature.

Stepping out and showing Geological Survey mapping with outcrops plus ENR interpreted activity.



Red outlines are mapped Lake Mackay quartzite (Age c1770 Mya), Dashed yellow are gneissic country rocks of similar or perhaps earlier vintage to the quartzite.
The presence of a previously unsuspected carbonatite at Luni and elsewhere does put a cat amongst the pigeons regarding the geology of this area. Some will survive the renewed scrutiny while changes may be needed elsewhere.

The relation of the Sambhar mag/gravity feature to Luni will, IMO, ultimately be one of the aspects studied. The current MRE geology suggests they are separate. Time will tell what, if any, relationship exists..