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To: c.hinton who wrote (81280)	1/30/2002 4:23:04 AM
From: E. Charters	Respond to of 116753

The Salton Sea is a dry area of California where such sea bed ores formed many years ago. Off Japan, in the Straits of Juan de Fuca off Vancouver Island, and off New Guinea are contemporary volcanic hydrothermal exhalative vents that are forming copper orebodies on the seafloor as we speak. Hot waters around 600 degrees farenheit hit cold sea water and precipitate metals around the vent area. Copper grade is around 5%. So far about 5 million tons of ore has been deposited around the vents in the Juan de Fuca vents which have been studied by the USGS and the GSC. What is interesting about these deposits is their proximity to volcanic centres, their mineralogy and their lithology. They correspond to classic exhalative sedex or volcanigenic deposits. Unlike many geologists I do not make a distinction between SEDEX and Volcanigenic. One is just a variant of the other. High manganese, proximity to porphyries, felsic rocks, and also to sea floor spreading or continental overthrust faults makes the contemporary seafloor deposits classically like our banded Canadian CU-ZN mineral deposits. These deposits pulsate alternately one mineral then another, resulting in dsitinctive layers of different minerals. Any time you see mineral differentiation or layering, you have to suspect pulsating seafloor-interface vents. Strange animal life abounds near these vents, such as giant tube warms and metal fixing Archea bacteria. What we can surmise is that in our ancient Archean geology, and later, we can look for similar environments, such as at the sutures of continental cratons where they contact subduction zones and by continental drift give rise to mobile zones of uplift (coastal mountain ranges) and resulting offshore island arcs. Up to 250 miles from these subduction heating zones and alpine volcanoes, vents emanate and quiet metal deposition takes place. One seems to need rhyolite with seawater circulation to leach metals and then re-vent them back up to the seafloor. Rhyolite and porphyry retains the heat. The porphyry is pushed up from the subduction zone as a diapir. The rhyolite pluts the volcano with a turgid mass and the heat and seawater circulates throught the porous rhyolite dissolving its metal with sulfuric acid. The discovery of these vents and explanation of the process of ore formation post dates the discoveries of a company called Texas Gulf Sulphur whose geologists used the first such theory of deposition to find several massive sulphide copper orebodies in Canada. They had thought that discoveries they had made using the Frasch process to leach sulphur from desert beds meant that ore formation processes were more likely sedimentary-surficial in the case of many ores, rather than by volcanic replacement at depth as classical theory seemed to say. Still to this day, many geologists cling to the theory of replacement or vein injection of molten sulphides to explain ores such as Sudbury's nickel ores. When the temperature of formation of the Pentlandite is found to be about 300 degrees centigrade, and the ore is found at what could be a sea bed basin contact it still does not dissuade these theorists. They will learn in time. If the proper environmental theory is used to predict the placement of ores, they become a lot easier to find. EC<:-}