Investigating Flat Slab Subduction and Plate Edge Tectonics in Northern South America


Caribbean-Merida Andes (CARMA) Array. Triangles are broadband seismographs: Red are PASSCAL. White & light blue are Servicio Geologica Colombiana. Dark blue and green are FUNVISIS. SM is the Santa Marta uplift.

NSF Geophysics EAR 1459047

Flat-Slab Subduction and Laramide-style Uplifts in Northwestern South America

Alan Levander, Fenglin Niu

Flat subduction of the Caribbean plate beneath northwestern South America is thought to have created the Laramide-style uplifts of the young (< ~10 Ma) Santa Marta block, Perija Range, and the Merida Andes.  These mountain belts and the subducting Caribbean plate, much of which is a Large Igneous Province, appear to be a modern analog for the Late Cretaceous-Early Cenozoic Laramide uplifts of the western U.S. Goals of the project include seismic imaging and characterization of the mechanical properties of the lithospheres of the South American and the subducting Caribbean plates, identifying current zones of deformation within the South American plate, and examining the mechanical coupling between the two plates to determine how deformation in the over-riding plate is controlled by the subducting plate. Images of the upper mantle from the BOLIVAR NSF CD project under western Venezuela (below, from Bezada et al., 2010, JGR) suggest that the Caribbean plate subducts steeply to the southeast beneath the Merida Andes, however this image is at the edge of the BOLIVAR array and is unclear at depths less than ~200 km.  The CARMA array is designed to image the Caribbean plate shoreward from the Southern Caribbean Deformed Belt thru the Merida Andes.

With our partners FUNVISIS (Fundacion Venezolana de Investigaciones Sismologicos) and the SGC (Servicio Geologico Colombiano), we installed a 65 station broadband array crossing the three ranges in March-April 2016.  The array extends from the Caribbean Sea in northern Colombia and Venezuela to the northern South American interior plains to the Orinico river basin. The array will operate thru April 2018.

Data from this array will be used for teleseismic and local body wave tomography, surface wave and ambient noise tomography, scattered wave imaging, anisotropy measurements, and micro-seismicity studies.