Guerrero Gold Belt

Mon, 10/21/2013 - 15:26

The Guerrero Gold Belt (GGB) is a northwest-southeast aligned trend of gold intrusions that span over 55km in the state of Guerrero. This mining district is typified by large and multiple deposits scattered over a broad area, albeit unified by the same geological characteristics. One of the most important features of the GGB – besides its obvious geological potential – is the infrastructure found near the district. The presence of highway infrastructure connecting Mexico City to Acapulco, access to water and electricity, as well as the availability of a qualified workforce, have made this district very attractive to investors.

The GGB is described as an intrusion hosted skarn-porphyry style that includes a strong epithermal overprint and is associated with a series of magnetic anomalies along a 55km northwest trending strike length. The mineralization is associated with early Tertiary granodiorite porhyries that were formed in Cretaceous limestones and sandstones. In addition to their common iron or garnet-pyroxene alterations, skarns along the trend are also associated with other products such as quartz, sericite, clays, hypogene iron oxides, and sulfide minerals. Each of the gold deposits within the GGB often occur in clusters within or near the contacts of these intrusions and typically have deposits in excess of 3 million ounces of gold.

The history of the GGB goes back to 1924, when Francisco Urias found an important gold deposit in Xochilapa. He operated a small family-owned mine and mill until 1988, producing a reported total of 360,000oz of gold. This discovery attracted the attention of many small mining companies looking for gold and other metals such as silver, lead, and zinc. Once these small scale operations reported success, larger mining companies came to explore the area. The original Nukay mine was a small underground cut-and-fill gold mining operation where about 500,000 tonnes of ore – grading 18 g/t of gold (290,000oz of gold) – were extracted between 1947 and 1964. The Morelos Mineral Reserve was created in 1983 by the Federal Mexican Government and consisted of 47,000 hectares, where many of the current projects (such as Nukay, Xochipala, and Bermejal) are located. After the privatization of the Morelos Mineral Reserve in 1998, the mining district saw a significant increase in exploration, leading to several new discoveries that rank today among the biggest mineral ore deposits in the country.

During the 1990s approximately 250,000oz of gold were discovered. This has since increased considerably. The discovered 5.4 million ounces at the Morelos project and the 13 million ounces at Los Filos mine, plus the 2.2 million ounces found at Ana Paula, push the GGB mining district up to over 21 million ounces of gold. These discoveries position Mexico as a prominent new source of mega mineral deposits and possibly one of the key players in the gold market within the next five years.