Diamond formation

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.

About Louis Hissink

Retired diamond exploration geologist. I spent my professional life looking for mineral deposits, found some, and also located a number of kimberlites in NSW and Western Australia. Exploration geology is the closest one can get to practicing the scientific method, mineral exploration always being concerned with finding anomalous geophysical or geochemical data, framing a model and explanation for the anomaly and then testing it with drilling or excavation. All scientific theories are ultimately false since they invariably involved explaining something with incomplete extant knowledge. Since no one is omniscient or knows everything, so too scientific theories which are solely limited to existing knowledge. Because the future always yields new data, scientific theories must change to be compatible with the new data. Thus a true scientist is never in love with any particular theory, always knowing that when the facts change, so too must he/she change their minds.
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3 Responses to Diamond formation

  1. malagabay says:

    We know SFA about the Earth’s interior.

    Shouldn’t that be emblazoned above the door of every Geological Society?

    Like

  2. fabio says:

    In the same areas of Brazil where there is diamond mining, such as Diamantina Highlands and Mount Roraima (which inspired Lost World of Conan Doyle), there are also interesting geological formation undeniable due to plasma discharges, which shape seem to be made by human stonework. Indigenous legends tell us that diamonds occur where there is fog in the morning. Well, the Mantiqueira Mountains begin in north part of São Paulo city, which name seem to be a change in colonial times from “Diamantiqueira”, and there is a park called “Mata Fria” (this is, Coldgrove). Gold, by its turn, seems to occur where the soil is ‘hot’.

    Like

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