Potential fields modeling for the Cayos Basin (Western Caribbean Plate): Implications in basin crustal structure

Abstract

The Cayos Basin is an offshore basin located in the Colombian Caribbean Sea and forms part of the Lower Nicaraguan Rise, a geological province of the western region of the Caribbean Plate. Until now, the origin of the province is still being debated. Advanced research in the study area regarding its composition and structure, from land outcrops, petrology and geochemistry of drilled cores and dredged samples, and geophysical investigations, indicates a volcanic origin for this geological province, and a close relationship to the formation of the Caribbean Large Igneous Province. On the contrary, other studies suggest that the Lower Nicaraguan Rise may be part of the continental Chortis block. In this paper, we present and discuss alternative scenarios for the nature of the underlying crust below the sedimentary sequences in the Cayos Basin. We characterize the basin through the interpretation of magnetic and gravity anomaly grids, and 2D forward modeling, constructed based on three sections, by considering restriction seismic data from previous works. The results show that the Cayos Basin is underlain by geological bodies with high density and higher magnetization. From the gravity and magnetic forward modeling, we estimated the depth to the basement is about 2-6 km, and the Moho discontinuity to have an average of 18 km below, the Cayos Basin. Our investigation implies that, at least, the Cayos Basin is in the oceanic crust domain and shows no evidence of a continental source of the Chortis block.