GEOLOGICAL MAPPING: A VALUABLE TOOL FOR MINERAL EXPLORATION IN MEXICO

Mining exploration in Mexico has dramatically increased in the last decade. Most of the discoveries are related to the geological mapping of the country. In 1995, the Mexican Geological Survey (SGM) started two mapping programs: 1:250,000 and 1:50,000. The first ended in 2005, producing 119 maps that were the base for the 1:500,000 state sheets and the 1:2’000,000 Mexican Republic map. The 1:50,000 scale program is still in process with 30% of the country (580,000 km²) mapped.

Geological mapping starts in 1803-1804, when Alexander Von Humboldt travels to Mexico. He produced his Atlas géographique et physique du royaume de la Nouvelle Espagne, in 1811. Andrés Manuel Del Río, author of Orictognosia Elements in –a treaty about geology and fossils–, is another pioneer by 1795. The first geological map of the Republic was assembled by Antonio Del Castillo and presented during the Paris International Exposition opening the 20^th century. Since then, geological mapping in Mexico has noticeable evolved.

The Mexican Geological Society was born in 1904. By 1906 hosted the 10^th International Geological Congress, and in 1956, the 20^th session, gathering a profusion of maps and field trips on the Mexican geology. By 1970, the National Commission on National Territory (CETENAL) produced geological maps that, together with those from the Geological Institute of the National Autonomous University and other institutions, contributed to produce a reliable 1:2’000,000 scale map of Mexico.

Mapping Mexico requires appropriate methodology and tools like satellite imagery, geophysics, and geochemistry. Field data is uploaded to handheld computers, and then into geographical information systems (GIS). The age and rock distribution together with structural arrangement, tectonics and magmatic suite are included in the map. All the West Mexican Range, for instance, evolved from a subduction history that yielded a number of epithermal deposits –the Treasure of the Sierra Madre. As a result the SGM is continuously producing prospective areas, adding value in a map. More than 310 of those areas have been detected since 2007. The location of mineral appearances along a terrain helps to open the eyes of people searching mineralization. To conclude, prospection requires a high grade of training, but most of all, trustworthy geological information.