The Trans-Mexican Volcanic Belt (TMVB) has seen through its long history, the flourishing of mining districts of the importance of Pachuca and El Oro-Tlalpujahua. Both world class deposits are reckoned to have produced significant amounts of Au and Ag resources with bonanza grades in the past.
Recent exploration programs conducted by some companies have proven the prospectivity of the region with the significant discoveries of the low- sulphidation epithermal deposit of Ixtaca in Puebla and the high-sulphidation epithermal deposit of Caballo Blanco in Veracruz.
At this time, mining companies have outlined total published resources for 5.8 M oz Au, 563 M oz Ag, 297 M lb Cu, 350 M lb Pb, and 835 M lb Zn in fifteen mining properties, four of which are in production and 11 more in feasibility or development.
The most relevant mineralization style in the TMVB is that of low-sulphidation epithermal affinity, with more than 3.8 M oz Au and 411 M oz in eleven deposits that represent over 67% and 73%, of the total resources of Au and Ag respectively. This mineralization style is followed by the intermediate-sulphidation epithermal style with almost 950K oz Au and 148 M oz Ag in three deposits that represent over 16% and 26% of the total resources of Au and Ag respectively. In addition these deposits also have over 297 M lb Cu, 350M lb Pb, and 835 M lb Zn.
Just one high-sulphidation epithermal deposit with published resources is present in the TMVB, Caballo Blanco, which contains almost 1 M oz Au and 4 M oz Ag that represents over 17% of the total resources of Au.
The TMVB region offers high prospectivity to find shallow mineralized systems as attested by the recent discoveries of the ore deposits of Caballo Blanco e Ixtaca. The TMVB region is currently being explored for some mining companies in search of additional resources.
The table below shows the total gold, silver, copper, lead, and zinc resources (all inclusive) for each mineralization style.
Although the TMVB has not been historically a mineral region with significant copper-lead-zinc ore deposits, it has seen relevant base metal past production, as is the case of Cuale mining district. Just in the period 1980-1990, Fresnillo Company produced from over 18 volcanogenic massive sulphide deposits in this mining district, over 13 M Lb Cu, 57 M lb Pb, and 179 M Lb Zn from 2.47 M tons with grades of 0.23% Cu, 1.03% Pb, and 3.22% Zn (plus Au & Ag credits).
At this time, the TMVB region has two mines with published resources of copper, lead, and zinc: the San Martin Bolaños Mine in Jalisco State owned by First Majestic (now in production), and Angangueo Mine in Michoacan State which is in turn owned by Grupo Mexico, and expected to re-start production soon.
To date, the TMVB has published resources for over 297 M Lb Cu, 350 M Lb Pb, and 835 M Lb Zn, contained exclusively in low-intermediate sulphidation epithermal deposits.
The table below shows tonnages, grades, as well as copper, lead, and zinc resources (all inclusive) for each of these deposits.
Although the TMVB is not the most significant mining region in Mexico, it has produced historically a significant amount of gold from several mineralization styles. The most relevant by size are the low-sulphidation epithermal deposits of Pachuca with 7 M Oz and El Oro-Tlalpujahua with 8 M Oz Au.
Currently, the TMVB has published gold resources contained exclusively in low, intermediate, and high-sulphidation epitermal deposits for over 5.8 M Oz Au. Of these, over 3.8M Oz Au occur in eleven low-sulphidation epithermal deposits, 948K oz Au in three properties of intermediate-sulphidation epithermal affinity, and 994K oz Au in a single high-sulphidation epithermal style.
Over half of the total gold resources are contained in two deposits: Almaden´s Ixtaca deposit in Puebla State, with published all-inclusive resources for almost 2 M Oz of Au at a grade of 0.54 g/t Au, and Caballo Blanco in Veracruz State, recently acquired by Candelaria Mining Corp., from Timmins Gold, with almost 1M Oz Au at a grade of 0.58 g/t Au.
These deposits are followed by Candente´s El Oro and Agnico´s El Barqueño deposits with 762K Oz Au at a grade of 3.44 g/t Au and 610K Oz Au at a grade of 0.96 g/t Au respectively.
Eleven additional deposits with less than 500K Oz Au occur in the TMVB and plenty of gold exploration plays are widespread in this mining region of Mexico.
The table below shows tonnages, grades, as well as gold resources (all inclusive) for each of these Deposits.
The Trans-Mexican Volcanic Belt (TMVB) has had a long mining history, as it is attested by the discoveries in 1524 and 1525 respectively of the well known world class deposits of Pachuca and El Oro-Tlalpuhajua. This mining region has a great diversity of ore deposit mineralization styles, being the low-sulphidation epithermal affinity the most prominent genre in this mineralized belt.
Published all-inclusive resources for 3.9 M oz Au and 411 M oz Ag have been defined to date on eleven mining properties, all of them by public mining companies.
Ixtaca of Almaden, has the biggest resource with almost 2 M oz Au and more than 114 M oz Ag at grades of 0.54 g/t Au and 30.9 g/t Ag. Other significant deposits are the Candente´s El Oro with more than 760K oz Au and 9.7 M oz Ag (historical resources non NI 43-101 compliant) at grades of 3.44 g/t Au and 44 g/t Ag, Monte El Favor with 316K oz Au and 84 M oz Ag at grades of 0.85g/t Au and 224.68 g/t Ag, and the Agnico Eagle´s El Rayo with 52K oz Au and 113 M oz Ag at grades of 1.52 g/t Au and 69.81 g/t Ag
The TMVB still has several potential areas with enough merits to be explored for mining companies in search of new discoveries.
The table below shows tonnage, grades, as well as gold and silver resources for each of these deposits.
The Trans-Mexican Volcanic Belt (TMVB) is an active magmatic arc related to subduction of the Rivera and Cocos plates beneath the southern edge of the North America Plate. The TMVB products cover older features of the cordillera over a broad region in central Mexico.
TMVB resources as a function of ore deposit styles include fifteen mining properties with published resources to date of which eleven are low-sulphidation epithermal ore deposits, three deposits are of intermediate-sulphidation epithermal affinity, and just one is a high-sulphidation epithermal deposit.
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.
In the image below, a color anomaly from the El Coporo project, Michoacan State.
The Trans-Mexican Volcanic Belt (TMVB), also known as the Neo-Volcanic Axes, 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 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.
The TMVB hosts historical mining districts such as Pachuca-Real del Monte in Hidalgo, and El Oro-Tlalpuhajua in Michoacan-Mexico States. To date, this mining region contains published resources in 15 mining properties, of which 4 are mines and 11 are advanced projects. The TMVB region is currently being explored for some mining companies in search of additional resources.
The image below shows 4 mines in red and 11 advanced projects in blue for a total of 15 mining properties with published resources. In the following weeks more information on the resources and deposit types of the Trans-Mexican Volcanic Belt will be posted.