The earths crust, the hard bit, averages 10 to 40km thick. All metallic deposits have to come from the liquid mantle, magma, below the crust. It has to flow up thru cracks made by plate tectonics aka continental and oceanic plates making up the crust smashing into or pulling apart or rubbing against each other.
Plate tectonic collisions buckle the continental plates up, mountain building, and because it’s rock it breaks ( vertical faults. These are the cracks the magma comes up including the metals within the magma.
The earth and magma is near 70% iron. Next is silicon magnesium aluminium making up say 20% and the rest is everything else on the old periodic table of elements.
Sometimes the magma gets to the surface aka volcanoes but mostly not and forms plutons of cooled stuff underground.
The basement is hard dried out magma and the sediments into are eroded mountain sediments either from on land or old ocean floor seds.
IOCGU and IRGS are the main intrusive plutons. VMS too. They bust thru the basement into the seds and spread out and cool. These feeder cracks will recrack with more tectonics and reimpose more magma.
At the crack under the plate basement the magma scours our the crack into a hole or inverted cone in the underside of the plate. Water from surface and in the seds aquifers trickles down the crack and hits the magma into super steam that blasts back up the crack into a volcano followed by magma.
In the first phase the magma is iron rich.
the second phase silicon Rich to give silica and granites
Third phase is Mag and al rich
Each phase is different cause that’s what’s left in the scour pocket.
Last phase is non ferrous iron metal rich here come the base and precious metals copper lead zinc tin platinum silver gold.
Each has different melting points and ionic chemistry.
Each precipitates out in turn.
The iron cools first (lower down) then base then precious metals higher up in the crust.
Also, the horizontal stress of tectonics pushes both the basement and the overlying seds. The seds are softer so move more over the basement. They are weaker and will get melted by magma.
There is a natural weakness area between 1 and 3 Km from surface due to the overlying pressure of kms of seds.
Thus from 1km to 3km down you generally have mainly iron, as magnetite (the dense Iron rich body).
From 500m to 2km it transitions to base metals mainly copper.
From near surface to 500m or so you get precious metals.
IRGS sits on top of IOCG kind of but also intermingled.
But the iron, it can be from 1km to 40Km vertically thick.
It can be high grade or low grade in %
Thats what Gravity and MT both see, a signal from below that is a combination of % and depth.
A high % shallow and a low % deep will have the same signal at surface.
Its the interface between basement and seds that’s important here. That’s where iron changes to base metals and gold etc.
So you MUST know the depth of basement. That allows you to devolve the %x depth conundrum into a specific %.
Thats why use seismics
They didnt
They could easily cheaply have
Wildcatting in the dark.
Another geophysics to use is ion (not iron) surface trace analysis that suggests the % once have the depth.
Every high content metal body releases ions in water. Remember the water driving the magma crack flow.
It ionises the metals, we call it acid generating.
Metal ions travel vertically up through the seds.
They hit the surface and the oxygen and precipitate as faint metal oxides in the top soil.
They can be “seen” by areal ion physics.
Another geophysics.
The gravity tell us there is a dense body there, the Mag tells us it’s iron so maybe also base metals, the seismics tells us how deep and then the ions divulge the %.
Then, when 1 in 100 of the gravity blobs have all those, you drill!
IVR Price at posting:
1.3¢ Sentiment: None Disclosure: Not Held
