I think the main tuff event emplacing the Onaping was fast, but the previous south of the rim pyroclastic events occurred over time. As well the post tuff Vermillion River Cu-Zn occurred over time. The orebody emplacement need not have been that fast. There is about five to ten million years between the Norite intrusions/flows ( choose your religion here).. but that is very iffy because of the age dating inaccuracy.. they could be very near the same age. They cannot be exactly the same as they are different in character and one does not intrude the other.. how they are separate intrustions without any interference is beyond me. They are astonishingly co-operative in their conformity. They seem all the world like they want to be flows just like all the other fine grained conformably "contacted" rocks, but a few geologists won't let them be.
The sublayer sediment, highly fractured by either endogoneous explosion/exogenous impact (pick church and pew in this space) was earlier still and predicates a quietus after the south-of-the rim felsic volcanic episodes. As well the differing composition of the Norites does not point to their being explaced or displaced soon after the impact/volcanic explosion.. One is mafic, the other felsic. That corresponds to long term changes in volcanic modes.. at least 5 million years apart classicly if we go by the standard volcanic facies changes over time.. The Norites and the subslayer appear to be embayed and conformable.. If they were emplaced before the ore, IMHO, they would not be so.. nor could the ore intrude in such a damnably conformable manner.. The neo-classic impact related theory, is impact, norite intrustion and subsequent ore intrusion.. by (continued.. they don't say how) magmatic event(s)...
from the FNX SEDAR files -- note the sedimentary features of Sudbury basin..
The Whitewater Group consists of synformal, Aphebian age epiclastic and sedimentary rocks comprising the Onaping Tuff and Onwatin Slate topped by the Chelmsford Sandstone in the center of the basin. The Whitewater Group was deposited after emplacement of the irruptive. The tuffs, related to volcanic activity associated with intrusion, were laid down and followed by erosion of
the SIC and sedimentation within the basin.
So what we neoclassically have is volcanism eposides, then tuff layering then impact and cratering.. no, wait a minute that can't be right, the tuff is still there... so what did the ore magmatically intrude into.. the crater has to come first, and then the norite, no that can't be right, have to preserve the norite, the impact would wipe it out.. or did it cause it to come in? the impact, the tuff, then the norite.. then the nickel (remobilized from the asteroid and the sulfur added in just the right terrestrial isotopic ratios to disguise its obvious meteoric origin), and then the copper zinc in the middle of the basin after 30 million years of sedimentation..
Magmatism is confusing.. it has to be right, but its history is so demanding of fortuitous events.. first we have a great volcanic ore area under the sea, then we wipe it out with an asteroid like a cosmic bullet hitting from a star at one trillion to one accuracy, fire it up with new meteroic nickel and then we bang the stuff back out in ore veins at 2000 degrees, despite the fact at that temerature sulfides will not flow at all, and we freeze it in 100 orebodies over 200 miles just at a magic second when it just successfully intruded one mile of now vertical vein dilation systems that were not there before, fortuitously again at the one contact for 200 miles ignoring all other shear and crack structures radially formed by this gigantic meteor hit, except for a few dykes, which are coming through established tension fractures structures that exist elsewhere throughout the archean 1 billion years per dating.... What luck.. what blind dumb luck..
What the magmatic theorists do not deal well with more than anything, is how the melt fractionated and pushed out all that massive sulfide into all those vein "cracks" at the norite sublayer contact .. where did the pressure to push that stuff come from? To say volcanic pressure is not enough, as if that were so, why did the main volcanic melt composition not predominate.. why did the sulfur and nickel get preferred? As I pointed out before.. was it steam pressure, from circulating sea water that forced the fractionated nickel into the contact? Why that area? Why not myriad other more convenient cracks.. that must have existed -- that were already there? Instead of a sealed contact between massive intrustions/flows? What was weak about that contact? Why was it sheared all around the rim? What kind of geological structure does this.. are their other examples.. (I will give you cone sheet instrusives diabases, but they are different animals andmuch more homogeous silicate melts..) Why did the intruding ore prefer concave to the inside of the basin contact areas?
We have to imagine the volcanic melt turned to solid sulfide... where are similar systems? Do we have solid pyrite volcanoes?(there is the odd tuff pyrite cinder cone.. but that is different again.. little bits of FeS2 spit out of volcanoes at some phase are not massive sulfide flows..) Massive pentlandite cones? Why not? Because rock/metal when it melts does not differentiate that much.. it mixes.. like a giant fire assay.. and when it precipitates it forms iron/light metal silicate flux mixes.. granite, andesite, gabbro.. what volcanoes are made of.. and the metals to be precipitated as sulfide matte has to be reduced.. partially ... what the magmatists want is for the melt to be reduced to sulfide matte, fractionated in a magma chamber almost 100% from the silicates, retain its fluidity (without other silica flux ore extremely elevated temperature I fail to see how) and then locally at one shear weakness pressed by some force into cracks selectively (which are not there a priori, it must create them by violent stoping) and massively concentrated..
If the melt veins were like a fire assay flux, they would solidify over time, fractionating into matte at the base of the melt in a mass.. The only theory that has been able to deal with the chemistry and fluidity and fractionating processes to evolve heat driven veins and what we have seen at the seafloor and in 1000 different orebodies, is dissolution and hot water-borne mineralization.. It is called hydrothermal emplacement and it operates the same whether it is in veins or on the sea bed. No other theory matches contemporary reality and what we seen of geological "fossil ores" at hotsprings, in vein systems, on the sea floor and in the myriad solidified ore bodies we have drilled or mined for a millenial.. It the ore were magmatic, then the eutectic or temperature of formation and the crystal structure would reflect the 2000 degree temperature. In addition its composition would be 80% silica in order to form a pressure driven vein which would make its own dilation zone. We would be looking at a nickel silicate or a fractionated sulfure matte, or perhaps a disseminated porphyry type ore. Instead we see Pentlandite that formed at 275 degrees celsius. The exact temperature of a hot water vent sea floor bed, that you can get a TV picture of today, forming at the sea floor spreading zones.. When you can see the process happening today, making up an LGM theory of magma that you cannot duplicate in a lab or in any other orebody.. is rather sad. Explaining the temperature differential between a magma and the known Pentlandite formation temperature is even sadder, It requires contortions of the extreme barythometric position.
Look at volcanoes today. What comes out of lava tubes? Melt rock. What comes of out the vent? Silicate lava, either mafic, intermediate or felsic.. how do you get metals to flow.. add flux.. what is that flux? silica, carbonates.. what are rocks made of? Silica, iron silica.. etc.. where are the sulfides? fractionated in the matrix. today where do we see ore formed? In Kurokoa lavas, or on sea beds, near volcanic vents. How do we see it? Hot springs, or sea vents ..black smokers.. have see seen any contemporary metal lavas? No.. can we make them in the lab and make the flow any distance..? no.. Can we make metals at 2000 degrees in a melt and then make them cool slowly so that they change structure to seem as if they were formed at less than 300 degrees C? no.. can we dissolve them, and either boil them in water and get them to precipitate or cool them so they do come outof solution? Sure, ever operate a boiler and have to remove metal (calcium) scale? uh-huh.. so where do these magic low temperature magma metals come from with terrestrial isotopic signatures and hot water temperatures of formation on the top of sediments in volcanic sedimentary basins in valleys under the sea floor, with other sea floor hot water minerals and 100 million year or more volcanic and sedimentary history? Well from asteroids of course.. and they come with special Martian catalysts so they can disguise their temperature ranges and their true isotopic composition when they land.. because they don't want to be recognized..And they hide in obvious sea bed valleys on sedimentary basin floors at contacts, so people won't suspect they came from outer space. They add sulfur to their composition by calling it up from the mantle, or them pesky nearby volcanoes.. and then they jump out of the melt, providing themselves with hot rocket gases to drill into the layers of rock.. they like that Martian Norite.. they hate all other rocks. When you have martian rocket fuel behind you and 20 million kilobars of pressure.. you don't need no stinking dilation zones, or tension fractures, you just barrel in and imitate stratabound minerlization.. the object is to confuse geology students and get them to weaken intellectually... taking over the planet after that will be a snap because they should believe anything..
If I fire assay pentlandite nickel today with a silicate melt I can get a sulfide to form with sulfur added to make a reduced fractioned matte or speiss. But it is clear what you get with this kind of assay at 1850 degrees F. You get a form of nickel sulfide that is not seen in Sudbury. It has the PGMs in it, but itis not the crystal structure of the Pentlandite. It is closer to millerite.
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