Presentation at the Discoveries 2016 Mining Conference held in Hermosillo, April 2016 (Downloads at the bottom of the page)
Mineral Resources of the Trans-Mexican Volcanic Belt
Miguel Angel Heredia Barragán, Jorge E Cirett Galán
Gambusino Prospector de México, S.A. de C.V.
The Trans-Mexican Volcanic Belt (TMVB), also known as the Neo-volcanic Axis, is an east-west trending dominantly mafic to intermediate, Neogene and still active, continental volcanic arc. It extends across Central Mexico, from the Pacific Ocean in the west to the Gulf of Mexico in the east. It is over 1,000 km long by 80-230 km wide and spans the states of Nayarit, Jalisco, Colima, Michoacan, Guanajuato, Queretaro, Mexico, DF, Hidalgo, Morelos, Tlaxcala, Puebla, and Veracruz. The TMVB is related to the northeasterly subduction of the oceanic Rivera and Coco Plates beneath the southern edge of the North America Plate (Middle America Subduction Zone). The TMVB is divided into four different sectors with distinct geological and tectonic features: the Western, Central, Eastern and Easternmost Sectors (Ferrari et al., 2012). The topography is characterized by valleys and lakes bounded by volcanoes. The TMVB hosts the tallest peaks in Mexico (> 5,000m), several of which present year-long, snow-capped summits.
In order to make an analysis of the current mineral resources outlined by public or private companies in the TMBV, a search of public information was carried out in NI 43-101 technical reports annual filings, corporate presentations, etc., and, in a few cases, in material disclosed in technical conferences and, interviews, or on the web.
Fifteen mining properties were reviewed, of which four are mines or development projects and eleven are advanced projects. Cumulative resources from these properties include: 5.8M oz gold, 563 M oz Ag, 297 M lb Cu, 350 M lb Pb, and 835 M lb Zn.
TMVB resources as a function of ore deposit styles include: eleven low-sulphidation epithermal ore deposits with a total of 3.8M oz Au and 411M oz Ag, including Almaden´s recently discovered Ixtaca deposit with 2M oz Au and 114.4M oz Ag: three of intermediate-sulphidation epithermal affinity with 949K oz Au, 148M oz Ag, 297M lb Cu, 350M lb Pb, and 835M lb Zn, including Agnico Eagle´s Barqueño deposit with 610K oz Au, and First Majestic´s Bolaños deposit with 272K oz Au, 38.1M oz Ag, 93.2M lb Cu, 287M lb Pb, and 457M lb Zn; and just one high-sulphidation epithermal deposit (the Caballo Blanco deposit of Timmins Gold) with 994K oz Au and 4M oz Ag.
Other TMVB ore deposit styles with past production but as yet undetermined resources include, volcanogenic massive sulphide (VMS) deposits such as Cuale and Autlan in Jalisco, and Aire Libre in Puebla; porphyry copper deposits such as El Cobre in Veracruz, Agua Blanca and La Sorpresa in Jalisco, and Tiamaro in Michoacan;, and skarn deposits such as Las Minas-Tatatila in Veracruz, and Tlamanca and La Preciosa in Puebla.
The recent discoveries of Caballo Blanco and Ixtaca attest to the continued prospectivity of the TMVB.