You can't ever help anyone by not telling them the truth.
The only way a gold laden quartz vein forms is over a long time (on the order of millions of years) which is required to concentrate gold from its background occurrence. A gold laden quartz vein does not force itself into an overlying rock like a nail, but rather is deposited along faults and fractures by geochemical processes over extremely long time driven by tectonics. Not any point in time event like a volcanic eruption.
What you quoted from Glover seems to be his version of innuendo and fantasy. He says
If volcanic terrain is known to produce rich gold deposits
but that really isn't the case. Tectonic processes, doesn't require any volcano. I don't see where he ever claims there is any gold in the younger rock anyway. Does anyone? This I why I have said over my time here when I ramble geologic - find the old rocks. I think we agree there is no gold (worthwhile) in the Dacite. I guess Glover ends up at the right conclusion that there is no gold in the dacite, but he babbles irrelevant to get there.
He mentions Nevada, and that very fine size gold (and lots of it) is well studied. About that stuff: "a tectonic trigger that led to extremely efficient transport and deposition of gold." "Au occurs in solid solution or as submicrometre particles in pyrite"
This is a good read on modern theory, it deviates slightly in that the ultimate source from which the gold migrates is deep magma (no sort of eruption either) - but even then it is magma which is recycling subducting crustal rock of average initial composition, but the subduction zone process works akin to a separation and refining process.
Check out the time spans for that enrichment process:
A long-lived east-dipping subduction zone was established along
western North America by the Middle Triassic period. Back-arc
magmatism in Nevada began in the Middle to Late Jurassic period
and ended by 65 Myr bp owing to flattening of the subducting
Farallon slab14. During 175 Myr of arc magmatism and slab
dehydration, the mantle wedge beneath the Great Basin was
continually hydrated15 and metasomatized with metals including
As, Sb, Tl, Pb, Cu (refs 1618) and possibly Au (see Supplementary
Note S3). Early moderately oxidized magmas may have fractionated
a Au-rich sulphide residue during evolution of the subcontinental
lithospheric mantle19 (SCLM; see Supplementary Note S4). During
the 20 Myr of shallow subduction, from 65 to 45 Myr bp,
the base of the SCLM was further hydrated and metasomatized
by slab-derived fluids20.
And that ore is very fine, even solid solution (like molecule fine).
I think this is it:
http://www.nevadaexploration.com/_resources/Muntean_et_al_Carlin_Genetic_Model-2011.pdf
CN,
We are arguing semantics.
Not me. There is a real nontrivial distinction between correct or not. I don't consider misstatements dismissible as semantics. And, I am not trying bust anyone's chops either. People try to learn from what they read, and if isn't quite right they are done a disservice and then every little thing perpetuates itself until we are all uneducated morons who get so personally frustrated they can no longer converse. ( <-- there is a grammar issue there
) I find you to be less prone to that rabbit hole. If you feel I am wrong about some fact or claim of mine, lets talk it out. I made specific corrections, if you disagree, lets work on it.
The simplest explanation is that while we have a lot of rock formations hundreds of millions (or billions) of years old, when a new geologic event happens,
This is almost semantics, but I don't think processes taking tens of millions of years are correctly referred to as events, even on geologic time scales. Geology is more akin to a slow continuum anyway, punctuated by relatively short intense incidents. Not interchangeable terminology/concepts.
it can force itself up through the older formations causing veins, shear zones, volcanic upthrusts, etc. that are much newer and contain minerals that didn't form in the older (original) rock formations.
On its face that ^says that an event can force itself. I am sure you meant a formation can. But really, I am not so sure we have evidence of formations doing that. Magma does. Hydrothermal solutions seep through fissures/faults/whatnot created by tectonics. Rock becomes deformed at the periphery of magma movements. Tectonics folds things and faults things and what not. Some formations get moved around by tectonics. Formations have no motive force to cause things. (well other than how gravity affects the things underlying them - I supposed you can implicate their mass.) Veins are not 'caused' as described ^. And that last part ... about mineral content... I'll wait until you rephrase if you disagree with me so far. Now, that being said, it is possible that in the millions of years preceding the catastrophic volcanic events - associated magma and tectonic processes metamorphosed the preexisting rock contributing to mineralization in the areas we all know about from documented mines.
You may have also misinterpreted some things I have said.
I might not be perfect, but I try to take things at face value.
If you think I believe completely
only partially?
that I believe the quartz vein in the LDM is from one of the three volcanic actions that formed Supers Caldera Rings, you have misread my thoughts.
Damned tarot cards messing with me again!!
Without going back into my older posts I will restate what I previously stated several times:
I think the quartz vein in the LDM is in the rock that underlies the Dacite/Tuff Volcanic Overlay. Where that mineralization shows through are from Volcanic Upthrusts, Shear Zones, Landslides, Earthquakes, and water/wind erosion. Places like that are where the Peraltas found their rich veins.
Agreed. If either LDM or PM's exist and contain gold they would be in the older rocks, not the tuffs.
Here is a quote from Glover's Book:
What is the citation to that book, I'll check if I can read it online. I just had a gander at the bible by helen that way ... and as long as I have your attention .... how do you feel about the death bed quotes from german translation? Not about the correctness of translation, but are those thought to be fairly accurate? I ask because as the book discusses they lead to well known heavily investigated area. How does the age of rocks in that area pan out?
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