Morphological expression of submarine landslides in the accretionary prism of the caribbean continental margin of Colombia

Abstract

Morphological analyses of ∼ 14,500 km2 of high-resolution-bathymetric data in the Caribbean continental margin of Colombia has allowed us to identify submarine landslides in the Sinú Accretionary Prism (SAP) and Magdalena submarine fan (MSF) areas. In the MSF area most of submarine failures are disintegrative, i.e. with no obvious deposit near or at the base of the scar, and are related to a system of canyons belonging to the Magdalena turbidite system and to an abrupt slope break at the border of the continental shelf. Landslides in the SAP area are mainly associated to the steeper flanks (12-18°) of anticline-related ridges. In many cases, the associated landslide deposits are buried by subsequent sediments related to broad fans formed in the mouth of channels and canyons. The cohesive landslides identified exhibit blocky deposits with rubble masses up to 50 m high and runout distances between 3.6 and 11 km. Morphometric analyses of scarps allowed us to calculate landslides ages in function of the constant κ of diffusivity. Estimations using a κ value of 0.015 m2y-1 suggest ages ranging between 13.8 and 9,761.9 ky for the MSF and ages between 12.2 and 1,031.8 ky for the SAP.