To: hank2010 who wrote (34037 ) 2/26/2007 1:03:53 AM From: E. Charters Read Replies (1) | Respond to of 78421 First Narrows? New geophysical methods always get me going, but the only thing I have seen recently that seems to "HIT" from the air, is the BP thingie, aerial gravity. Which is kind of comical because in spite of its puported success in oil finding salt domes, gravity NEVER hits on the ground in mineral exploration! The successful geo(physical) or geo whatever methods and their chiefest rate of success I will list here. Geochem: Markedly unsuccessful in many areas by many implementations and full of snake oil methodologies, it has nevertheless a better track record to mine by the anomaly than geofizz does. Zinc and lead ore does not respond well to geofizz electrics, but does to geochem. Down Hole: the best track record of any 'lectrickal method in directing drills to anomalies that become mines. About 50 NA mines to its credit so far. If you don't use down hole when drilling you are missing a march. Geology: Without this starting point there would be no exploration. Just plain geological hole driving has found mines since the Roman Empire. Input/Time Domain: The favourite of many, but while it has found a few mines (Mattagami Lake, South Bay) it has spawned more dry holes than gopher colony in a desert. Slingram/Horizontal Loop: a ground technique that is much used but has a problem with positivity. While it does react to ore, it seems to help that one first knows the ore is there, as the reaction over just any old ground is much harder to read. VLF: another aerial/ground technique that works good from theory and gives much good information about the ground. However it is problematic to use now due to the fact that the sources of signal are no longer dependable. As well it has limited depth penetration. Most of the orenbodies are actually anomalies, but few of the anomalies are orebodies. VLF needs a replacement. IP: It is the darling of many and finds all kinds of things it is supposed to find. (Disseminated sulfides.) On the other hand its tie in "to found this mine" is weak. It is supposed to find porphyry type ores, not massive. It has trouble with graphite and is not really what you want to use to find massive sulphides. It is not designed for that. IP along with geochem is a very powerful tool for finding disseminated sulfides and associated minerals of gold deposits. Multi-Frequency: Aerial or ground method that supposedly has limited depth penetration, but in practice is adequate. It needs a lot of interpretation. It has some success. Computer power has made it a lot more palatable than it ancient cousins. AM/Moving Coil -- many of the older geofizsz electrical methods were fairly discriminatory, and found mines. ( Texas Gulf ) They need magnetic discrimination (phase) and also more frequencies to be good. (see multi frequency) Their advantage is they benefit from power and modern computer interpretation increases their usability. CSAMT/AMT/ Potential is good, and is a major development tool for the oil boys. More is needed in this area. Potential for computational technology to improve its efficacy is high, as interpretation is a key. Self Potential: Very positive, discriminatory, and although thought to be a hobbyist tool, is very good to use and not too expensive. Positive means the anomaly is very likely what you are looking for. Discriminatory means it can tell what an anomaly is that you may not be looking for. Self potential can reject graphite, and when it kicks it is 90% of the time sulfides. Gravity: Weird monkey. Finds great anomalies where you figure they should be, but never found a metal mine where they were just looking. And often it worked ever after the whole mine is mined out too! kinda strange. But it worked in oil lots. Finds salt Domes like a hot damn. And when they start flying gravity, which is no mean feat for certain physical reasons, it starts finding sulfide ore like crazy. hmmmmmmm Magnetics: Not to be sneezed at. Finds iron ore of the magnetite kind at any depth. Finds nickel and pyrrhotite, so was used by Inco in preference to electrical methods. Can even map rock types and faults. In the latter case it can be used in concert with AFMAG and Input to do a good job finding shear zones and faults. Mag can be used to find quartz that associates with gold. It can define kimberlites and other magnetic bodies. It has marvelous depth penetration. Too good often. Co-incident Coil methods: New wrinkle that uses two coils that are co-planar and very close together. New theories indicate they may be as efficacious as widely separated coil systems. No commercial models yet, as coil distortion is a problem that need elegant solutions. You will hear more about this as it may be a replacement for VLF someday. Beat Frequency Metal Detectors: Beep mats and the like fall into this category. Used by nugget hunters they will actually detect the difference between copper, gold and iron. That is because of the conductivity difference of these metals. In fact while scorned by professional geophysicists as a serious exploration tool, they are vastly under appreciated in my opinion. A large form of this kind detector might actually have some of magic. You have to know what you are looking for and where it might be geologically. Then you have to know what might kick your geofizz doodelbug that you ain't lookin' for. Then you have to have a lot of money for dry holes. And then trust to luck and know how to pray. There is something to new technology. I like geochem. I like self-potential. I like magnetics. I am suspicious of Time Domain systems. I don't think they work at all most of the time. As a matter of fact the way in which electricity actually works with regard to energizing sulfides and just how conductive they actually are, need a lot more thinking than has been given to the matter so far. There is room for a lot of dissent and further research in this industry. EC<:-}