Detached and shelf-attached mass transport complexes on the magdalena deepwater fan

Abstract

The Magdalena submarine fan, fed mainly by the Magdalena River, is part of a Miocene-Recent accretionary prism off the Caribbean coast of Colombia, S.A. Periodic shifts of the Magdalena River controlled the evolution of the fan. The integration of multibeam bathymetry, GLORIA images, and 2D seismic profiles reveal a series of deep-water channel systems and mass transport complexes (MTCs) on the seafloor. The MTCs were subdivided into detached and shelf-attached types. Relative timing of the detached MTC processes cannot be determined due to their local character. Four major shelf attached MTCs are described from interchannel low areas. We hypothesize that these attached MTCs began to be generated during a low stand of sea level (140-120 ka) which prompted hydrostatic pressure changes and/or gas hydrate dissolution on the slope, leading to collapse. Later processes of slope deformation and slope instability continued feeding MTCs to the interchannel lows. A southerly shift of the Magdalena River depocenter (middle Pleistocene) and abandonment of the Galerazamba region channel-levee systems coincided with the lowstand. © Springer Science + Business Media B.V. 2010.