Relation of MAGSAT Anomalies to the Main Tectonic Provinces of South America

Comparison of MAGSAT scalar magnetic anomaly data to the main tectonic provinces and boundaries of South America reveals a number of geologic correlations. South America is divisible into a broad platform of Precambrian shields and cratons separated by Phanerozoic basins, grabens and aulacogens to the east, the Phanerozoic Patagonian Platform to the south, and the Mesozoic to Cenozoic Andean Fold Belt and Caribbean Mountain System to the west and north. The continental shields are mainly more magnetic then continental basins and orogenic belts. Cratons, mainly covered by younger sedimentary rocks, are generally associated with magnetic gradients. Most of the anomalies associated with the Patagonian Platform are positive and have higher amplitudes eastward away from the Andean Fold Belt. The northern Andes are coincident with positive magnetic anomalies, whereas the central and southern Andes are associated mainly with negative anomalies.