ICE 2022


Recently reimaged seismic data from offshore Colombia has revealed previously unknown details of the central Caribbean and the active margin along northern Colombia. Approximately 60, 000 line kilometers of 2D seismic, from a total of 18 legacy surveys, was depth-imaged as a single, contiguous survey. Much of the Caribbean Large Igneous Province (CLIP) is composed of a smooth-topped, 2-layer basement (~12 km thick) and is likely a result of sub-aqueous flows on Pacific-origin oceanic crust as the plate passed over the Galapagos Hot Spot (GHS). This integrated data set provides new evidence of intra-plate spreading within the central Colombian Basin. This region of rugose-topped, 3.5 km crust is flanked by the 2-layer crust of the Embera Hills in the west and the Beata Ridge in the east. These flanks show crustal thinning in the central Caribbean and have dipping magmatic flows (similar to seaward dipping reflectors) seismic packages dipping towards the thinned region. Through the incorporation of filtered free-air gravity data we identify a paleo-spreading ridge and a northern transform, striking SW-NE and sub-parallel to the Hess Escarpment. This expanse of new crust and the surrounding 2-Layer CLIP, are being obliquely subducted at the Magdalena Fan and the South Caribbean Deformed Belt (SCDB). The timing of the Embera Hills deformation and a Late Miocene unconformity that surrounds this region of thin crust is coeval with the docking of Panama in the western Caribbean. In this study we submit that a combination of: 1) the arrival of the Panama Arch; 2) buttress effects of the Santa Marta Massif; 3) the onset of the Andean Orogeny and; 4) the progressive easterly plate motion of the CLIP and slab tear all contributed to extensional stresses and subsequent oceanic spreading in the Central Caribbean. The limited amount of magmatic material encircling this area indicate that crustal breakup involved minimal igneous activity before progressing to normal oceanic crust production. The rugose fabric of the oceanic crust indicates that the spreading rate of the ridge axis was slow and created fault scarps at the ridge. The highly variable crustal thickness plays an important role in the nature of subduction along the northern South America margin. This study highlights that understanding regional distribution of Late Cretaceous sedimentary units and the Late Miocene Unconformity is critical to understanding the evolution of the central CLIP.