SUBSURFACE STRUCTURE INTERPRETATION OF THE NORTH OF THE WESTERN CORDILLERA, ECUADOR: INSIGHTS FROM AEROMAGNETIC DATA

To evaluate and estimate the resource potential of a region, it is critical to understand the geological processes involved in its evolution. This study focuses on the Western Cordillera of Ecuador, between 0⁰ and 1⁰ N latitudes, where at least two world-class porphyry deposits occur (Alpala and LLurimagua). A range of approaches have been used in this study to interpret aeromagnetic data for expanding our understanding of the subsurface geology and structure in this area.

We redefined the geometry of three principal system faults in this region: Western System Fault (WSF), Central System Fault (CSF) and Eastern System Fault (ESF); based on qualitative interpretation and spatial analysis. Characteristics about the deformation style were derived from further structural analysis. Our results show two consistent fault populations: (1) dominant NE/SW mostly dextral faults, preferably larger than about 6 km. (2) E-W both, dextral and sinistral faults, apparently shorter than 6 km. Additionally, depth estimation suggests deep sub-basins within the study area, to about 2-3 km depth, according with quantitative interpretation and 2D forward modelling.

Finally, we propose and discuss a model of the subsurface and the structural framework for this area, explained by a single deformation history and characterized by current transpression. We then consider the implications of these structures (WSF, CSF and ESF) on mineral potential - especially regarding magmatic-hydrothermal ore deposits with a preference for porphyry and epithermal styles as the new insights presented in this study may help to reduce exploration uncertainty and hopefully delineate new targets in the region.