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Interessante geophysikalische Analyse (allgemein und James Bay): http://www.agoracom.com/ir/Noront/messages/635238#message Geophysics... Posted by: Bentonstocks on November 17, 2007 06:22PM Just to add my two cents to confirm and/or expand on what others have said recently on this topic, and to reiterate what I have said in the past on the matter, geophysics alone do not tell you where mineralization (deposits) are. Rather, they are a starting point, or an indicator of where to start looking, used in conjunction with historical geological data/maps/reports, and aerial photos and/or landsat imagery. Some or all of the above will be used depending on what is available, and the geological environment or setting. Airborne geophysics conducted with fixed wing aircraft are usually the first type of geophysical survey conducted on 'new' ground - it is much cheaper and more efficient to cover large of areas of ground with an airplane than it is with a helicopter. This process records and maps the natural magnetic signature of the rocks and surface immediately below the aircraft. I say "surface" because and airborne geophysics data will pick up structures on surface such as power lines, metal structures, etc., depending on the line spacing, how low the aircraft is flying, and the' filters' employed to weed out the noise in the data being collected. There are many variables/factors that affect the final product, i.e., the geophysical maps that are generated based on how the data is eventually interpreted by computer programs. There are also many things that can contaminate or disturb the data being collected, including problems or equipment failures on the aircraft itself. The recording equipment onboard the aircraft is calibrated to tune-out the natural frequencies/'noise' emitted by the aircraft while it is operating. The moment something changes on the aircraft (e.g. a fuel pump failure) that tuning will be rendered ineffective and the data corrupted. The final product, the geophysical maps, reveal rock structure that would not otherwise be apparent from other sources, or just by a pair of trained eyes walking on surface. In addition, the magnetic signature that is detected and recorded by the equipment will include that which is emitted by rock below surface to limited depth dependant on some of the variables mentioned above. Since different types of rock have different degrees of magnetism, or lack thereof, the geophysical data will produce maps that reveal rock structure simply by generating maps that are records of their magnetic signatures. The different colours on the maps only represent degrees of magnetism - nothing more, and those colours are chosen by the data processors through manipulation or programming of the software used to process the data. Anyone looking at the nice colours on the available maps and trying to figure out for themselves where the next 'eagle' is... well... misguided. If it were that easy, we would require neither the geophysicists nor the geologists. Anyway, these maps are then interpreted based on the known geological setting (regional geology, rock provinces/types, known mineralization occurrences if any, etc.) to pinpoint areas where mineralization may have occurred. Mineralization is usually manifested in, or associated with, anomalous rock structure. Since magnetic anomalies are in fact rock structure anomalies, they are a good place to look, or start from, if the geological setting is such that mineralization is thought to have possibly or likely occurred in that setting. Once areas of interest are determined, the next step is usually to conduct some field work to take surface samples, and map the surface geology/topography, after putting in a line grid. Bear in mind that this is just very sort of brief sort of overview of the process.... Because the McFauld's Lake area is largely lowlands with very little, if any, visible rock structure on surface, this requires a greater reliance on various forms of geophysics to pinpoint potential areas of mineralization. Diamond drill holes are very expensive (one hole can cost hundreds of thousands of dollars depending on depth), and are a very precise or 'narrow' method of testing for mineralization - you do not normally just start drilling holes without having spent considerable time analyzing various types of exploration data (geophysics, surface sampling, mapping, etc.) to determine where to position a hole if you think the area warrants drill-testing. This is why other companies in the area have not just up and started drilling as some people on this forum have asked. The hardest part of the exploration process is determining where to position/drill the holes. In fact, the purpose of all the exploration work is to enable the geologists to make their best educated guesses as to where to position drill holes, or even make a determination as to whether they should even drill test the area of interest - it all leads to that. So, because of the environment (wet lowlands with virtually no visible rock on surface) in the Ring of Fire, the companies are having to rely more on geophysical data - they are almost going at it blindly because they can glean very little, if anything, about structure from what they see at surface. This is why other more specific/profound/detailed types of geophysics are being employed in the analytical process. These include the ground geophysics, down-hole geophysics, EM geophysics, and the AeroTEMII being flown by helicopter. This is also why NOT have been drilling many holes over a limited strike length. Without the benefit of other geophysical data (currently being collected and processed) to help them decipher the geometry, they would have had to have taken ‘baby steps’ as they step-out from the original discovery hole since they would have had very little understanding, virtually none in fact, of what is below the surface. This is also why they would have holes at different angles from the same set-up (position). From the comment/questions I have seen on this board, it is clear to me that very few of you appreciate or understand how difficult it is to position drill holes and understand what is going on many meters below the surface. As an analogy imagine two rooms separated by a wall. In one room is the drill, and in the other room is the deposit which in this case will be a glass coffee table with 3 legs. Now, to find the deposit, you have to drill through the wall, which you cannot see through and try and hit the coffee table, while not even knowing that what is on the other side is a coffee table, where or how it is positioned (on its side, or upside down, or balanced on one leg) in the room, or if it even exists - all your wall penetrating 'radar' (the geophysics) has told you is that there is something in that room that might be of interest. If you are able to actually hit any part of the coffee table with your drill, you pull your drill tube back through the wall and then examine the bits to and hopefully figure out that you have hit a coffee table, and try to piece together where you have intercepted it, and at what angle, so that you can try to determine where to drill your next hole based only on an analysis bits of glass or metal that you think might me a coffee table. Sound hard? Well that because it is... At any rate, what is both interesting and significant about NOT's discovery is the fact that the airborne MAG high and associated EM (conductive) anomaly have been shown to be VMS and PGM mineralization, in this particular case. In other words, a particular magnetic high (MAG) anomaly, with an associated electrical conductive anomaly (metals are conductors of electricity) has been shown, through drill-testing, to be mineralization with the right kinds of metals. Until the drill bit proved this, this particular MAG/EM anomaly, our beloved Eagle 1, was only just a structural anomaly with anomalous amount of conductivity, and many things could have been the 'cause', including a graphite structure, which is why these anomalies were ignored in the past - the geological setting did not make it likely that a MAG high and associated EM anomaly would be VMS or even PGM mineralization. Now that NOT has proved otherwise with their discovery, ‘the exploration clock has been reset to zero', so to speak, and all of the anomalies are being revisited, and more precise geophysics are being conducted. Now, because NOT's Eagle 1 has proven to be a VMS/PGM discovery, it does not mean that all other similar anomalies are going to be the same thing. In fact, it is far more likely that other things will be found to be the cause of such anomalies. Remember, that these MAG anomalies are just indicators of rock structure, and the conductivity could be caused by many things. Referring back to our coffee table analogy, if our wall-penetrating radar (our geophysics) has detected something, an anomaly, which is actually a couch, or a desk, but we have no idea what it is, just that something is somewhere in the room, and if it is only glass coffee tables that are of interest or value to us, only drilling will determine if those anomalies are other glass coffee tables (deposits) waiting to be discovered, once we actually find (hit) them with the drill bit.. What is interesting about FNC is that the anomaly on their claim adjoining NOT's discovery claim is most likely, but not certainly, part of the same anomaly, and therefore the same body of VMS/PGM mineralization - the anomalies and/or mineralization do not stop at the borders of claims. If the FNC anomaly was anywhere else on their property, and therefore removed or separate from NOT’s Eagle 1 discovery, it would have no better odds of being mineralization than any of the other associated MAG/EM anomalies of interest in the Ring of Fire. It is silly for anyone to think that just because it is on FNC's ground, that it could not be part of the same discovery. The association has been established on NOT's claim, and if the anomaly continues, 'unbroken' onto another company's ground, it is logical to conclude that it is the same thing, rather than something different. However, there is nothing in the known data that could quantify who has how much. Again, the only reasonable conclusion is that there is - probably - some of Eagle 1 on FNC's ground, and only drill-testing will eventually prove how much, if any, of Eagle 1 is on FNC' ground. It also true that at this juncture, no other company, other than NOT, has higher odds of having mineralization of significance on any of their claims than does FNC, and this only because of proximity. Regards, B. Gruß, Fantomas |
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| aus der Diskussion: | FAKTENTHREAD: JAMES BAY LOWLANDS (firmenunabhängige Übersicht) |
| Autor (Datum des Eintrages): | Fantomas96 (18.11.07 23:15:34) |
| Beitrag: | 75 von 243 (ID:32475085) |
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