Laterites in Guatemala

What is it about?

The Izabal Geosol is a new stratigraphic unit defined by the author within the Sierra de Santa Cruz (SSC) ophiolitic belt which is located to the north of Lake Izabal, in the east-central portion of Guatemala, some 140 km northeast from Guatemala City. The Geosol Izabal is composed of the following five pedosols: a. Gossan or Iron Cap (a.k.a. Ferricrete) b. Limonitic Horizon c. Stoneline Horizon d. Mottled Zone Horizon (a.k.a. Transition Zone) e. Saprolitic Horizon The Saprolitic Horizon lies over a Saprock Horizon, which, in turn, lies directly over a less weathered bedrock of the SSC ophiolitic belt. The most complete profiles are usually presented over weathered dunites and serpentinites, while on top of the less altered pyroxenites there usually forms only a limonitic horizon. The SSC ophiolitic belt overthrusted the Maya Block of the North American Continental Plate during the Early Tertiary period along a flat structure that outcrops at its base. The SSC is one of the five ophiolitic belts identified to date in Central Guatemala that are related to the northwestern border of the Caribbean Plate and, thus, to the ophiolitic belts from Cuba and Dominican Republic. The intrusives of this belt are composed of alternating layers of dunite and pyroxenites, usually strongly serpentinized. Existing data indicate that these rocks underwent fractional crystallization and probably some degree of magma mixing and contamination prior to their main tectonic event. The Izabal Geosol represents a case of arrested development of a wet lateritic profile, which develops mainly as large pockets controlled by tectonics and the presence of dunitic rocks. Its most striking difference from other wet laterites is the presence of up to 30% magnetite within the Saprolitic Horizon, which indicates relatively young age of these laterites. This magnetite carries nickel grades of 1.5 to 2% associated to nickel sulphides. It could represent a secondary product for a plant producing ferro-nickel or steel products. The presence of these large amounts of magnetite also allows the use of aeromagnetic surveys for the identification of areas of interest.

Featured Image

Photo by Michiel Ton on Unsplash

Photo by Michiel Ton on Unsplash

Why is it important?

Detailed description of the geology and evolution of lateritic nickel deposits in Guatemala

Perspectives