Exploring the Sierra Madre of Mexico for gold and base metals.
The core of the Tango Project is a partially exposed, but undrilled, Climax-type molybdenum porphyry prospect surrounded by gold-rich polymetallic veins. Climax-type deposits are the largest and highest grade type of molybdenum deposit in the world, with potential for multiple ore-shells at different elevations within the ore-forming plutonic complex. If drill-testing eventually proves out an orebody, the molybdenum deposit will probably be mineable either by open pit or underground block caving methods. Some of the larger gold-rich veins may be exploitable by selective underground methods.
The Property overlaps 3954.1 Ha and is centered in Southern Sinaloa State, Mexico, near geographic co-ordinates 105º45’W and 23º12’ N (1:50 000 map sheets F13A47 and F13A48). It is owned 100% by Minera Camargo S.A. de C.V. Mining concessions that define the Property were acquired by staking between 2003 and 2012 over the former “Viva Zapata” Mineral Reserve, a project that was staked and explored by the Servicio Geologico Mexicano (SGM) in the 1980’s. Geographically, the Property overlaps part of the western foothills of the Sierra Madre Occidental, one of the world’s largest silicic igneous provinces. Regional geochemical work by the SGM at the turn of the millennium highlighted the Reserve as one of the largest contiguous anomalies for gold and base metals in southern Sinaloa and Northern Nayarit.
Of the three volcano-sedimentary sequences on the Property, two have recognized potential by the USGS (United States Geological Survey) for porphyry systems. The oldest sequence (USGS Tract L-2) includes rocks of the Laramide continental arc that is known to host 15 of the 21 known economic porphyry systems in Mexico, including Cananea. The youngest sequence includes rocks of the Tertiary extensional arc (USGS Tract T-2) that contains no known porphyry systems, but does contain several known polymetallic prospects that might represent upper or adjacent parts of porphyry systems (Hammarstom et al., 2010). As a group, these rocks are more silicic and more potassic than the Laramide rocks. It is the author’s opinion that Tract T-2 is highly prospective for porphyry molybdenum deposits due to its evolved nature, and that the deposit type may have been largely overlooked by previous workers focused on silver and gold-rich veins. Specifically, unless historic assaying included molybdenum, porphyry molybdenum deposits in most of tract T-2 were probably overlooked. Hammarstom et al. (2010) assigned the Tango prospect to Tract L2 in their Table 2. However, recent radiometric age dates by Ferrari et al. (2013) imply that most plutons on the Property are early to mid-Miocene in age, therefore Tango should be assigned to Tract T-2.
Geologic mapping of the Property indicates that rocks of USGS Tract L-2 mainly outcrop in the southwestern 25 % of the Property, with rocks of USGS Tract T-2 overlapping the rest of the Property. At this time, the data implies that USGS Tract L-2 on the Property consists of: (i) basaltic andesite intruded by (ii) feldspar megacrystic diabase and overlain by (iii) intermediate volcaniclastic rocks, including some ignimbrite. All of these rocks were eroded for most of the Eocene, and red-bed deposits of conglomerate and sandstone define this hiatus. Starting in the Oligocene, volcanism initiated again with at least 100 m of basaltic andesite overlain by and intercalated with massive to thickly bedded proximal rhyolitic ignimbrite deposits overlain by finer, more thinly bedded, ash-fall tuffs. These rocks are intruded first by Miocene granodiorite, then by a felsic plutonic complex that includes: (i) massive quartz-porphyritic rhyolite crypto-domes with (ii) marginal flow-banded rhyolite, (iii) syenite porphyry, (iv) aplite and (v) felsic porphyritic dikes. Late Miocene magnetic mafic dikes cross cut all geological units, and occur in older faults.
Pórfido del Cuervo, the porphyry molybdenum prospect in the northern part of the Property, appears to be related to Miocene felsic plutonic activity in USGS Tract T-2. However, most of the rocks that outcrop in the area are strongly altered, and detailed mapping, diamond drilling and analytical work will be required to clearly define the geological environment of Mo-mineralization.
Alteration mapping of the porphyry system indicates that potassic alteration is co-incident with development of unidirectional solidification texture (UST) of quartz-aplite and molybdenite. Structural measurements of the UST’s imply the cupola related to Pórfido el Cuervo may be tilted easterly, and phyllic alteration adjacent to and overlying potassic alteration is best developed east of the known UST zones.
A prominent northeasterly trending scarp between San Agustin and El Pino underground gold mines is a major regional fault that juxtaposes Oligocene rhyolite to the southeast against older mafic rocks to the northwest. This fault appears cross-cut by younger northwest trending faults into numerous segments, including San Agustin, Los Yegaros, Los Tejones and La Colcomeca, among others. Both directions of faulting contain gold-rich mineralization with potential as underground mineable precious metal deposits.
Further work is warranted to develop the potential of the Project. Specifically, San Agustin is a target for near-term development as an underground minable gold-silver resource, and Pórfido del Cuervo has the potential to be a major source of molybdenum in Mexico. Some additional studies are recommended, including geological, topographic and geophysical mapping. However, the bulk of the planned work is diamond core drilling of Pórfido del Cuervo, San Agustin, and other gold-rich veins. Overall, a budget of 1.44 million USD is proposed. Click here for a Project summary. Please contact us for further information.