recognition of debris flows with felsic lava fragments and sulphidic clasts, graphitic and cherty exhalites, moderate to strong silicification and sericitization, stringer Zn, Cu and Pb mineralization, and replacement style mineralization
This above is the important information from this NR. The most interesting part was the sulfide clasts. However at Kidd Creek, the sulfide clasts (very small "grains" of cpy) were seen in "Copper Hill" in Prosser twp, in a rhyolite. They were recognized at the time before the discovery drill hole as not proximal, but not really distal. Later they were found to be 6 miles from the main economic vent source which was the Kidd Creek Mine. The geologist for Texas Gulf who drilled the discovery hole at Kidd, Ken Darke, told me that the tiny clasts of copper fact upgraded the nearby conductors considerably. Clasts indicated venting. The very area of the clast system told of fecund ore venting.
The felsic lava fragments in debris flows could be 1 Km or more from a good producing vent. The nature of the sulfide deposition indicates the strong possibility of near economic deposition somewhere, if it escaped erosion. However moderate productive venting could be indicated by the stringers, and the cherty exhalites/graphite. These are often proximal features. It sounds like a mixing zone at the base of the mt. of a proximal (1 to 3 km distance) but low grade vent. (Vent systems can be quite distal from the volcanic source which exudes actual lava. There need not be volcanic mountain building in the area.) The stringer zone is usually below the main sulfide mineral body. Many of the geological features in the archean are overturned, so the main body could still be below the stringer zone, several hundred feet. In Australia one famous mine was found 1000 feet deeper than the surface zinc stringer zone. Cominco used to consider stringer zones of major significance and advised all field personnel to report and map them in detail.
A zone that was gone over in detail south of Timmins (Mallard Twp. area) by a group in the 90's resulted in the finding of lots of low grade copper that sort of fizzled. They never found more than say 1.5% Cu, in narrow systems. Within 6 miles there was copper porphyries which may have been clast systems, similar to Prosser, and I think that they may have missed the real zone. However a nearby area of interest that had also attracted the former TG staff, was walled-off by interests that were locked in dispute. The largest bombs were found in this area. Originally Darke felt the area was too phreatomagmatic. Occasionally you found surface bombs that at first looked like glacial erratics, sitting right on the outcrop, looking all the world like gigantic volcanic boulders. (some were as many as 50 tons.) They were ejecta that had been eroded out of nearby hills, perhaps in the pleistocene, and originally tossed perhaps 4 KM from the violently erupting volcanoes to the north. These kind of systems deserve revisiting with more than just casual aerial EM driven exploration efforts. This shotgun technique ignores the massive sea bed geological systems that are the real clues left behind that tell tale the ore systems. IT is like playing blind man's bluff when you are can just open your eyes to see where the donkey's ass really is.
The great mistake at Kidd Creek was not to study the vent related faulting more in depth and continue to explore in a systematic manner to discover the pattern of deposition for the inevitable other related vents. Once you find one massive sulfide orebody you know there are others in the area. In the case of Kidd they only found one. The other sulfide ores of the Timmins area are different age, and not directly related. This systematic exploration was done at Noranda in Quebec, where the sub volcanic intrusives (dalmationite porphyry) were dotted along the major ore producing fault, which in this case struck north west from Rouyn.
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