Age estimation of submarine landslides in the la Aguja submarine canyon, Northwestern Colombia

Abstract

La Aguja Submarine Canyon (LASC) is a remarkable bathymetric feature that cuts the continental margin of the Colombian Caribbean Coast offshore of the Santa Marta massif. This section of the margin is strongly influenced by two active strike-slip fault systems: the NNW-trending Santa Marta – Bucaramanga Fault (SMBF) and the EW-trending Oca- Fault (OF). Based on 6,500 km2 of high resolution multibeam bathymetry and one 2D seismic reflection profile (~60 km), we identified submarine landslides associated with the LASC. Along the canyon we observe channel morphologies high sinuosity, variable widths (between 2 and 8 km), and both U- and V-shaped asymmetric cross sections. The occurrence of mud volcanoes in the surrounding area, some of which stand above the flanks of the canyon, is also common. The available data allowed us to identify 31 submarine landslides on the LASC flanks, between water depths of 1,200 and 3,285 m, with slopes ranging between 6.1° and 36.8°. Using numerical solutions of the diffusion equation of these scarps we estimate ages of between <1.0 to ~631.6 ka. According to observations, the triggering mechanisms of landslides could be closely related to earthquakes originated in the convergence zone of SMBF and OF, and/or to the flanks instabilities driven by mud diapirism.