Some time ago Russian scientist Konstantin Khazanovitch-Wulff (K-W) had a paper published in the NCGT News (or Journal), in which he proposed that kimberlite was a shallow source igneous rock; I proof read that paper. K-W was concerned that as a De Beers type of diamond geologist, I would have misgivings about shallow sourced diamonds and kimberlites. Not necessarily for if the data show shallow origin, so be it.
Geochemically K-W was on the mark and I then surmised that if the Russian view of kimberlite geochemistry was right, then one way diamonds could be formed at shallow depths was by subterranean electrical discharges of CO2 saturated material during the formation of the kimberlite.
I had previously published a view that kimberlites were electric discharge structures machined from the surface down by a vortex mechanism, aka Birkeland currents. Then I had the problem of figuring out how could these surficial phenomena penetrate through the MOHO and into the asthenosphere to tap into the deep seated diamonds, depth of stability being essentially determined by Pressure (P) and temperature (T), aka the diamond stability plot. K-W’s theory offered another explanation.
Some years back at an AIG Students night in Perth I suggested to one budding post-graduate student that he should look into adding a third vector for mineralogical phase plots, that of P,T and E, E being electric field strength. The idea being that increased E would perhaps cause diamond to be stable at much lower P&T, compatible with the K-W theory of shallow origin for kimberlite and hence diamond.
Given that volcanos are essentially electric discharges in the earth’s crust, then I would suspect that the our standard petrological phase diagrams that allow us to infer depth of burial from P&T factors is incomplete and that if we include E, the electric field as an additional parameter, or factor, that maybe our subsurface phase modelling is thus wrong.
This would have serious implications for the phase stability of the hydrous silicate Ringwoodite, and indeed for the modelling of the Earth’s subsurface in terms of seismology.
As for diamond genesis, I would also venture a guess that high dalton number hydrocarbons might also be formed by subterranean electrical discharges, rather than by the usual process of subduction.
The upshot is that we know SFA about the Earth’s interior.