Interpretation of geophysical anomalies for mineral resource potential evaluation in Colombia: Examples from the northern Andes and Amazonian regions

Abstract

This paper focuses on presentation of the methodology used by geophysicists at the Servicio Geológico Colombiano (SGC) for the processing, anomaly selection and interpretation of airborne magnetometry and gamma spectrometry data. Three (3) selected magnetic anomalies from different geological settings (Andes Cordillera, San Lucas Range and Amazon region) are presented as examples. 3D magnetic vector inversion (MVI) modeling of each of the selected magnetic anomalies shows magnetic sources less than 100 m deep or exposed with sizes from 2.5 to 6 km. The magnetic data interpretation also allows the identification of linear features that could represent structural control for fluid migration and/or ore emplacement. Additionally, the integration of the geophysical data with other geoscientific information (geologic, metallogenic and geochemical data) leads to the proposition of an exploration model for each anomaly: intrusion-related/VMS deposits for the Andes, porphyry/intrusion-related/epithermal deposits for San Lucas and carbonatite/kimberlite for Amazonas. The methodology used and examples presented illustrate the potential of SGC airborne geophysical data for mineral resource evaluation and as input for the design of fieldwork for geological, geophysical, geochemical and metallogenic characterization of an area of interest.