The Emerging Guerrero Gold Belt of Mexico

Overview

The 80km-long Guerrero Gold Belt (GGB) lies within Guerrero, a southern state of Mexico. Gold was discovered in the region in the 1920’s and small private mining operations worked in the region for several decades. In the 1990’s, following some consolidation of the private mining lands and the auction of government mining lands to private firms, more aggressive exploration began to take place. Several new deposits were discovered and in 2007 Goldcorp began production at Los Filos, a large operation consisting of 2 open pit mines and one underground mine. In 2009 Nyrstar began mining the G-9 deposit at Campo Morado and earlier this year Torex began mining at El Limon-Guajes. Torex is stockpiling ore while construction of the plant and the remainder of the mining operation El Limon progresses. A number of junior mining companies have established resources within the GGB and other still are actively exploring or hold properties in the region.

Regional Geology

Mineralization in the area is related to gold bearing iron skarn-porphyries. Gold deposits of the Guerrero Gold Belt occur within faults and as replacement deposits formed in and around igneous intrusions. VMS-style massive sulphide deposits also occur in the area. Overprinting of the skarn-porphyry systems are younger epithermal silver-gold deposits.

Deposit Geology

The geology of the Guerrero Gold Belt consists of early Tertiary (65-23.8 million years ago) tonalite, granodiorite and monzodiorite porhyries intruded into Cretaceous (145-65 million years ago) limestones and sandstones. The mineralization type is called a skarn, which is essentially altered and replaced rock along the contact between the igneous intrusions and the carbonate-rich country rock. The exchange of fluids between the two rocks results in the formation of calcium silicate minerals along the contact zone as well as gold deposition.  Within these contact zones iron and/or garnet-pyroxene minerals dominate as well as quartz, sericite (white mica), clays, iron oxides, and sulfide minerals.

Discussion

The Guerrero Gold Belt is considered “hot property” with over 31 million ounces (31 Moz) of gold discovered since the early 1990’s. For this reason, it is often referred to an “emerging gold belt”. The popularity of the area is sure to continue as additional discoveries in the area are made. As with any “hot” mining district many small junior have snapped up property on speculation alone, while others are actively working their properties. Since we last talked about the GGB, several properties have changed hands.

Companies and Projects