Picachos Epithermal Silver-Gold: San Dimas, Durango
The Picachos Property, in the southwestern part of the state of Durango, is centered about 100 km west-southwest of Durango City, and occurs north-northwest of the Durango-Mazatlán highway, about 8 km from Puerto Espinazo del Diablo (23 43’ north, and 105 48’ west). The Property consists of four concessions overlapping a contiguous surface area of 7778 Ha. The concessions are owned by Minera Tango S.A. de CV. (“Tango”), a subsidiary of Seafield Resources Ltd (SFF). Seafield purchased Minera Tango from Yamana Gold Inc. (YRI) 31 Dec. 2006. NWT has the right to acquire a direct 70% interest in the Picachos property portfolio by: (i) investing US$3,000,000 in exploration over three years, (ii) making cash payments in installments totaling US$400,000.00 to YRI, and (iii) issuing 1,000,000 common shares (also to YRI) over a three-year period.
Camargo continues to Operate the Picachos Project on behalf of NWT. On the Property, four significant epithermal precious metal districts have been defined: Guadalupe, El Pino, Los Cochis and El Toro. In late 2007, 3125.25 meters of drilling in 21 reverse circulation holes were completed at Los Cochis, mainly in a strong silver-in-soil geochemical anomaly defined by NWT in 2005. Results from several holes imply that high silver grades occur across substantial widths. For example, Hole COCH 3, returned values of 67 g/t Ag, 0.48% Zn and 0.22% Pb across 59.23 meters, including a higher grade interval of 198 g/t Ag, 1.15% Zn and 0.66% Pb across 9.12 meters. Geological modeling suggests that the mineralization is controlled by a permeable volcano-sedimentary horizon that dips gently southwest, and an additional 2785 meters of drilling in 21 holes are planned to test the down-dip potential of this mineralized Horizon. If successful, the program should provide enough information for an initial NI-43-101 compliant resource estimate on Los Cochis.
Location and Infrastructure
The Project area is located about 40 kilometers south-southeast of Tayoltita, one of the largest epithermal gold camps in the world. Past production from Tayoltita totals about 654 million ounces of silver and 9.14 million ounces of gold from over 19 million tonnes of ore (Enriquez and Rivera, 1998). Tayoltita was owned by Mexican gold miner Luismin, but they sold the mine and several other exploration stage properties to Wheaton River Minerals, which was taken over by GoldCorp Inc. in early 2005.
Access to the Property is via the Durango-Mazatlan highway, and a network of country roads that links the villages of La Mesa, Huizar, La Ventana, Picachos, El Duraznito, Neveros and Los Desmontes. A 230 KV electrical transmission line runs parallel to Highway 40, and a branch line to La Mesa de Los Negros. Rural satellite phones are installed in all of the villages. Water is readily available from mountain streams that are re-charged in the summer rainy season between July and October. Elevations range from 1900 meters in the village of La Mesa to about 500 meters in the Rio Los Tanques. Vegetation ranges from pine and oak above 1500 meters, to tropical brush and cactus in the valleys. Cattle ranching, logging and subsistence farming are the main economic activities in the region. The rainy season is from July to September, with intermittent winter storms. Temperatures range from freezing at higher elevations in the winter, to more than 45ºC in the valleys in summer.
Regional Geology
The Picachos Property is in the Sierra Madre Occidental (SMO), one of the largest silicic volcanic fields in the world. The SMO formed between the Cretaceous and the Tertiary when the last remnants of the Farallon plate were consumed below the western margin of Mexico, and the Sea of Cortez opened between Baja California and continental Mexico. The SMO consists of five igneous complexes (Ferrari et al., 2005): (1) Late Cretaceous to Paleocene volcanic and plutonic rocks, (2) Eocene rhyolites and andesites, (3) bimodal Oligocene ignimbrites (32-28 Ma) and basaltic lavas, (4) bimodal Miocene ignimbrites (24-20 Ma) and basaltic lavas, and (5) late Miocene bimodal alkaline basalts and ignimbrites. These new divisions are a modern refinement of McDowell’s and Clabaugh’s (1979) work which divided the SMO into a “Lower Volcanic Complex” dominated by andesitic rocks of Cretaceous to Tertiary ages deposited in a compressive tectonic environment, and an “Upper Volcanic Series” of Oligocene to Miocene age dominated by ignimbrites related to extensional tectonics. According to McDowell and Keizer (1977), most of the mineralization of the SMO province was in the “Lower Volcanic Complex” (Volcanic Complex 2 of Ferrari et. al, 2005). It is now recognized that all five Volcanic Complexes are mineralized, and work is on-going to better understand the metallogeny of each Complex. In the Property area, regional stratigraphic correlations imply that the geology of the Picachos Property is similar to the geology of Tayoltita, one of the largest precious metal districts in the world.
References
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