I was checking up on the meaning of the phrase “Granite-wash” that is the source rock for natural gas in Oklahoma and Texas. It seems that some deep drilling was done years ago and the hole stopped in molten sulphur at depth, and somehow the conclusion made that the drilling bit melted due to being immersed in the liquid sulphur.
But I digress and ‘granite-wash’ ? It’s a sediment derived from the erosion of granite and consisting of sand sized particles, hence sandstone, ahem. Problem.
Chemically weather granite as observed in Western Australia and you end up with clays but no sand. I’ve drilled enough holes in granite looking for gold to make that statement as fact. So to get quartz grains and presumably feldspar grains as well, requires a non-chemical or slightly chemically eroding process to yield distinct crystals of quartz and feldspar to act as the primary source of the sandstone to be deposited elsewhere. It is assumed the granite is a topographic high since you need a gradient to move the released quartz grains, etc., down the drainage systems to allow comminution of the grains to reduce them into sand sized particles.
And if a large quartz crystal is going to be reduced in size by attrition, then the products of this process need to be accounted for as deposits of, say, siliceous material such as chert? In other words quartz crystal ==> smaller crystal + siliceous dust or smaller qtz crystals. And if it is a fluvial environment in which the water coats the quartz grains (quartz is hydrophilic) then the grains are actually protected from collision by a liquid coating, so fluvial transport actually does not have the ways and means of attritioning quartz into smaller particles. While this can be done in a standard metallurgical mill, where steel balls are used to grind the rock into smaller size fractions, no such mechanisms exist in nature; rivers are not ball-mills.
And I know from extensive personal experience that the bed-loads in sand choked drainages also do not move downstream but stay in place in the channel depressions over which the active bed load, usually as lag gravels, travel. Totally counter intuitive but a fact none the less.
A distraction. Some years back I edited some scientific papers for a Russian scientist on kimberlite genesis, published in the New Concepts of Global Tectonics Newsletter, now a journal, and he was a little apprehensive about my theoretical stance as a former De Beers geologist and my assumption that kimberlites were deep seated mantle originated rocks. The Russian observation was that kimberlites seemed chemically to be near surface phenomena, akin to a variation of acid volcanics, and not deep sourced as we in De Beers assumed.
The Russian view was that kimberlites were near surface phenomena produced by external electrical effects of by-passing bolides or meteors. Or as I now understand it, near surface plasma effects. I should point out that I no longer accept the idea that kimberlites are initiated at depth but are first formed at the Earth’s surface and then tunnel downwards towards the mantle, where pressure release then results in an uprush of kimberlite magma, and if one is lucky, the occasional diamond. In addition I suspect that electric discharge also has a role and the source of the kimberlite might be more shallow as the Russians suggest from chemical characteristics. Here the increased electric field strength may push the diamond-graphite stability boundary upwards to zones of less confining pressure, if such a situation exists at all.
The other problem is no one has seen a kimberlite erupt, so it’s all educated guessing.
So let’s cut to the chase and muse that the “granite-wash” isn’t a sediment produced by fluvial action, but a volcanogenic sediment emplaced by a fluidic process derived from the plasma machining of gneissic and granitic rocks.