To: Mike Gold who wrote (19660 ) 10/21/1999 7:47:00 AM From: Mike Gold Read Replies (2) | Respond to of 25548
To Rich519 on the RB thread: "A couple questions for Mike Gold. Can you help? It seems there are about 4 breccia pipes discovered at Lipangue and on the adjoining CD property and more may exist. Diameter of the breccia pipes can be as large as 250 meter. The maximum distance between pipes seems to be about 1.7 kilometers. Some have indicated the pipes go about 1,000 meters deep, if not more. Can you give us some comparisons if any to conditions including breccia pipes found at the multi billion ton Rio Blanco deposit located 40 miles away and located on one of the same structural weaknesses that underlies the Lipangue LDM complex?" Rich, you need to read,"Porphyry Copper and Tourmaline Breccias at Los Bronces-Rio Blanco, Chile" by Fred W. Warnaars, etc... published in Economic Geology Vol 80, 1985, pp. 1544-1565 The only connection between Lipangue and Los Bronces-Rio Blanco is the eastward projection of the east-northeast-oriented Juan Fernandez ridge south of the Nazca plate and the Challenger fracture zone. The intersection of this tectonic feature with the Andes mountains may have caused a zone of weakness to allow magma to raise at Los Bronces. I have speculated that the same thing may have occurred with the tectonic feature intersecting the Coastal range with Lipangue area being the summit of the Coastal range.(Los Bronces is about 40 miles due East of Lipangue along this feature.) Other geologic features between Lipangue/Los B. vary radically. Los B. consists of a "composite" breccia pipe-actually 7 separate breccia pipes formed so close together that they overlap into one mega pipe some 2 Kilometers long and 0.7 wide.(only a portion of it is ore bearing.) Compare that to the much smaller pipes at Lipangue/Lobo. Copper ore at Los Bronces use to contain incredible 20% copper content between 1865 and the 1920 before the supergene enrichment zone was mined out. Compare that to Lipangue! (Note: No gold at Los B.-wrong type of magma.) Of course, at Lipangue/Lobo-the largest gold nuggest discovered in Chile was found there.. what does that tell you? At Los B., the porphyry is secondary in importance-much of the original porphyry was destroyed during the formation of the pipe. What's left consists of the underground mine at Rio Blanco. (Recall, a pipe can be formed before/during/after the porphyry deposits-that determines whether destructive or not to the minerlization-the narrow snake-like dimensions of the pipes at Lipangue are more suggestive of the geology at Lepanto, Phillippines-thin pipe 1200 meters long with large underlying porphyry.) The rock types at Los B/Lipangue are very disimiliar etc etc. I could go on and on-certainly you should read the Paper(available at a University Library)for a complete analysis. In a nutshell-it appears to me that geologic processes in vicinity of this tectonic feature went into over drive once upon a time...