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Gold/Mining/Energy : Gold and Silver Juniors, Mid-tiers and Producers -- Ignore unavailable to you. Want to Upgrade?

To: jpthoma1 who wrote (32248)	2/8/2007 9:15:05 AM
From: E. Charters	Read Replies (3) \| Respond to of 78421

The meteor theory does not dispute how the nickel got into the veins except for some wild and wooly extrapolations about the amount of nickel in a very large asteroid collision. Unless it were a very, very large, almost planet destroying sulfide asteroid with just the right terrestrial isotopic mix of ni-cu-pt, and it was very very rich in ni-pt-cu it would not work. And the ni-iron asteroids are not sulfide asteroids, and their isotopic ratios are different than the ni-pt found in Sudbury. They do not contain sufficient copper. They are nickel iron. different animals. The copper zinc of Vermillion river, where did that come from? Fortuitously system related? Perhaps.. but it is a red herring. We have sea bed VMS minerals in the center of the basin, but not at the rims... well.. explain the history better to resolve that one.. One of the important questions is why would a segregated fractionated pure sulfide melt suddenly gain the pressure to emplace all the ore around the rim all at once? Where did it get that intrusive stoping capacity after melt fractionation at the base? Steam pressure? Throughout the system, to emplace at just tha weakness point or the norite contact and a very few dykes? And the silica? I can see an intrusive stoping in if it is very broad or a dilation system crack is there, but all over at a contact ina vein manneer? Hard to figure. The Mineralization has been declared decidedly terresterial by some sources. It would be fortuitous indeed if a rich nickel iron asteroid hit a productive metal rich craton with a previous history of felsic volcanism. Remember the volcanism has to both predate and postdate the meteor, as the felsics to the south of the rim are older than the ore, and the tuff and the Vermillion Cu-Zn is younger. This is both stratigraphic and age dated. That they are definitely not VMS is not decided in the bible either. Their first and most probably correct designation was as hydrothermal in 1948. They did not become magmatic until Naldrett, and later theorists. The grave difficulty with magmatic is: how can the plumbing system transport such a rich sulfide magma through extensive vein systems and disseminated deposits and have it freeze just so when fully extended in the veins? Was there outpouring at the end of vein for just so long until the magic moment of all-over freezing of the fluid? How can such a turgid all sulfide transport fluid flow in tiny vein branches? Did it stope its way in intrusively into the norite contact with perfection? Why is their no extensive vein brecciation? Why are not all the veins like dykes? Why is the temperature of the formation of the Pentlandite so low, consistent with precipitation from super heated water or acidulated aqueous gas? "Pyrite started to exsolve below 700° C, chalcopyrite below 450° C, and pentlandite below 300° C. Monoclinic pyrrhotite formed from the host hexagonal pyrrhotite probably between 300° and 250° C." ucmp.berkeley.edu No other vein theory or massive sulfide model calls for such an emplacement mode. All others, the discredited replacement theory, segregation theory and hot water precipitation theory are different for every other ore body. Why could they be VMS? Because they are the right temperature, the volcano is there, the mineral suite for VMS is there, the two norites are fine grained enough to be flows, the veins appear evidently huydrothermal, they have sea-water quench structures in radially striated nodules or suflides, they occur at natural embayments, in a sub sea-bed volcanic caldera, and they occur between two differently aged flow strata! It is called the Sudbury basin. It was in an inland sea floor. It has sediments in the middle and volcanic pyroclastics around the rim. We know it was volcanic. Tuffs. What more could one want to declare them sedimentary which is what VMS is? The Timmins deposits are, as in the Redstone. They are at the contact between two dunite flows. It was once thoughtthey were segregations, but no characteristics of magmatic segregation are there. Similarly Sudbury ores cannot be segregations as they occur in embayments, once thought to be dilation zones, but except in the case of the Strathcona, cannot be so. I will admit more than one type of occurrence is at Sudbury. The Strathcona, a dendritic vein system, the Creighton, a disseminated system, and the Frood are very different modes of emplacement. They however except for the Creighton clearly hydrothermal, both in temperature and geometry. The Creighton is explainable as a vent system by tuff and flow mixing at formation time of the outflowing flow rock mass. The magmatic theory cannot explain all the different modes of emplacement you would need at Sudbury. It can only do one vein type model. Stoped-out force dilation and instrusion. Unfortunately, the walls of the veins are not consistent with such a model unless gaping cavities were already there. As well no one has ever called for such a model before, which requires drastic and complete segregation of a melt into sulfide species for emplacement and in some cases different mixing and totally different melt chemistry to get the required silicates in other parts of the veins. The water emerges from a hydrothermal vent at temperatures ranging up to 400°C, compared to a typical 2°C for the surrounding deep ocean water. The high pressure at these depths significantly expands the thermal range at which water remains liquid, and so the water doesn't boil. Water at a depth of 3,000 m and a temperature of 407°C becomes supercritical.[3] However the increase in salinity pushes the water closer to its critical point. Some hydrothermal vents form roughly cylindrical chimney structures. These form from minerals that are dissolved in the vent fluid. When the super-heated water contacts the near-freezing sea water, the minerals precipitate out to form particles which add to the height of the stacks. Some of these chimney structures can reach heights of 60 m.[4] An example of such a towering vent is "Godzilla", a structure in the Pacific Ocean near Oregon that rose to 40 m before it fell over. The initial stages of a vent chimney begin with the deposition of the mineral anhydrite. Sulfides of copper, iron and zinc then precipitate in the chimney gaps, making it less porous over the course of time. Vent growths on the order of 30 cm per day have been recorded.[5] Chimney structures that emit a cloud of black material are called "black smokers", named for the dark hue of the particles they emit. The black smokers typically emit particles with high levels of metal sulfides. Vents that emit lighter-hued minerals have also been discovered, and these are named "white smokers". They are typically lower in temperature than black smokers, and are deficient in copper, iron and hydrogen sulfide, while being rich in zinc.[5] EC<:-}