A couple of things to think about when dreaming about how much Ni and PGM are in those anomalies.
In geology we learn that geological events take place of large scales (100's or 1000's of km), over long periods (millions of years), in 3D (the earths crust was how thick in the JBL when this happened? It is now about 30-40Km thick), and complex. So when we talk geological events we are often talking in term of generalities on large scales.
For a magma plume to erupt out of the core/mantle there needed to be an event that enables that. It could have been one of the polar flips where the earth’s polar axis reversed, a wobbling on the axis that caused stress on the crust, compression or contraction fractures etc etc. Whatever it was it allowed a large volume of magma to erupt into the crust and melt its way upwards. If the event was powerful enough to toss off one plume it was probably powerful enough to toss of more than one. They may all pile up under each other or there may be lateral dispersion as well.
Here is where 3D comes in. Think of it as a lava lamp. The wax melts, density decreases, it rises towards the surface. As it raises it cools down, starts to solidify, and then drops. The big 'blobs' raises the most as they cool the slowest and the small the rise least since they cool down the fastest. In 3D we will have plumes of various size scattered through a 30KM thick vertical column of crust plus lateral dispersion. We have plumes from below that crash into plumes above them that had become stuck. Then we have plumes that are lucky enough to find faults in the crust that allow them to rise much more rapidly then others.
These plumes are nothing like the gentle blob of wax floating up to the surface of the lava lamp. They are massive (kms in diameter) smoke'n hot balls of molten rock that are ripping through the crust melting and fracturing everything in their way. Rock bulges around them and above them and fractures and faults to relieve the stress of their passage. Think of it as one massive explosion after another after another after another as it works its way upward through weakness in the crust. All the time it is cooling down, heavy elements are settling to the bottom, its becoming diluted with melting crustal rock that changes the solubility of the minerals in the magma, parts are being squeezed off etc etc. Eventually it either gets stuck in the crust and cools over 10,000s of years or the top layer erupts to the surface as volcanics with VMS deposits ( economic or not). Although there may be NI and PGM in the VMS deposits most of the Ni and PGM will get concentrated in the bottom of the magma chamber.
How the fluids in the bottom of the chamber get to the surface is anyone's guess. Mine is that as the magma plume cools it contracts and the surrounding rock fractures yet again as does the plume. Pressure from the contracting plume (or maybe pressure from a colliding plume from below, squeezes out yet more molten fluid. This time it is super enriched with Ni and PGM. The molten metal rich fluid burns it way through the remaining crust to reach the near surface where it cools rapidly and deposits the minerals.
Over the next 100s of million of years the rock get uplifted, folded, faulted, eroded, etc ect. As this happens deposits get remobilized, concentrated, altered etc depending on the structural and geochemical solutions. So even if you had a nice simple deposits its not likely to have stayed that way. Everything about geology is complex as soon as you go fro generalities to specific.
In mining we look for thing on the surface. If we get lucky we find something that is buried (a whole 10 meters for DE1) under overburden. If we get really really lucky we find a truly buried deposit like ARU (~100m). Our exploration tools don't allow us to look much deeper than 500m and even then the risk/reward is usually to low to try. We tend to explore in that top 0.1% of the earth's crust.
So it is entirely possible that there are multiple magma plumes or parts of the same one. We just don't know until they find the first, or second or third. Similarly we don't know what is in each of the anomalies until we drill them. What we know is that NOT has an economic MMS and has anomalies in very close proximity that are probably related. We also know that the mineralization of DE1 and DE2 are different but don't know what that means (and neither will NOT until they get the assays back).
As to the regional plays the story is the same. They all have good stories to tell but until they are drilled and assayed they are good prospects. I fully expect that their will be other finds in the area but there will also be a lot of non-economic anomalies drilled and a fair number of out right duds. Those are the odds of drilling anything.
If I'm wrong and they hit all over the place I won't mind. I have enough NOT and area plays now that I'll be able to tolerate the pain of being wrong as I retire to my own South Pacific island :)
Hope this helps
… Been There
