Ron:
In response to this and your previous query.
We have found what I can only describe as a number of probable breccias related to Cretaceous and possible Tertiary igneous activity at Paraguari.
There has been very, very little maping done in the past, as Paraguay has an extremely limited mining history. As you may have heard before, we have the data which was generated in the past by Anschutz and we helped to write the local mining law. (Anecdotally, while the law was being drafted, they asked for a (percentage)royalty in the 30's. We showed the government officials what was common in other countries and the figure was cut by a factor of 10.)
Gold was first discovered in the Cripple Creek district in 1870, with production beginning in 1891 and amounting to 20 million ounces Au over the following century. The Cresson Deposit at Cripple Creek, Colorado was discovered in 1903, and produced until the late 1950's.
Last February, we found our first drill target, a 20 by 70 meter outcropping where we took the first 16 samples averaging 0.48 g/t Au, with values of 1 to 1.8 g/t Au. A second round of 45 samples repeated the average (0.45 g/t Au) but with values to 2.7 g/t Au. Additional elements correlating well with gold found were fluorine, chromium, vanadium and arsenic, with some antimony, copper, silver, lead, zinc and phosphorus... many of these elements are also found at Cripple Creek. Also, like Cripple Creek, petrographic work at our target confirms an adularia-sericite system related to a former hot spring.
We've expanded the area noted above through hand augering to more than 100 by 100 meters, with the area open in two directions. Beyond this, geochemical sampling suggests the mineralized zone may extend 350 meters north and 250 meters south ie. for 600 meters. This is a round-about way of saying we don't yet know how large the zone is but we're working on it. (As you realize, this may be totally irrelevant but Cresson was a 90 by 180 meter diatreme which produced 2 million ounces of gold.)
To quote one relavent geologic report:
"The Cresson Mine was unique for the district in that ore-grade mineralization formed in large masses within and adjacent to a lamporophyric diatreme."
This report goes on to note that the shape of the body and improving mining methods allowed for low cut-off grades, bulk mining and an extended mine life.
To shothand/quote the report:
"The Cripple Creek volcanic pipe is a Tertiary alkaline diatreme/caldera complex dated at 28 Ma."
... surrounding country rocks ...Precambrian granites & metamorphic units. Emplacement of alkaline diatreme debated but believed associated with initial development of Rio Grande Rift system... biscets New Mexico & continues into south & central Colorado...
"The alkaline rocks of the Cripple Creek district are beleived to have a metallogenic association with an under-saturated mantle derived melt, emplaced in part by rapid verticle transport in a diatreme complex. The Cripple Creek gold system has an unusually high gold to silver ratio of about 9:1. The mineralizing fluids are believed to be CO2 dominant with a deep-seated mantle component..."
Cripple Creek breccia is highly variable, containing diatremal breccia and various volcaniclastic derived breccias and tuffs... units were later covered and intruded by phonolite flows and hypabyssal dikes... last phase volcanic activity was emplacement of mafic to ultramafic dikes & development of late-stage diatremal pipes....
One of the objects of Yamana's current drilling program is to confirm structure at Picua.
At Cripple Creek, structures are primarily steeply-dipping with many areas showing sympathetic low-angle structures between high-angle features...
gold mineralization in Cripple Creek district -- two environments: a) narrow high-grade gold telleride-bearing veins with consisten mineralogy and grade over more than 3,000 feet and b)as broad zones of low-grade, near surface (upper 1,000 feet of volcanic complex) disseminated gold...
I hope this helps.
Greg |
