BOLIVAR: the Caribbean-South America plate boundary between 60W and 71W as imaged by seismic reflection data

We present the results of ~6000km of marine multi-channel seismic (MCS) reflection data collected offshore Venezuela as part of the Broadband Ocean Land Investigation of Venezuela and the Antilles arc Region project (BOLIVAR). The imaged area spans almost 12 degrees of longitude and 5 degrees of latitude and encompasses the diffuse plate boundary between South America (SA) and the SE Caribbean plate (CAR). This plate boundary has been evolving for at least the past 55My when the volcanic island arc that borders the CAR plate started colliding obliquely with the SA continent: the collision front has migrated from west to east. BOLIVAR MCS data show that the crustal architecture of the present plate boundary is dominated by the eastward motion of the Caribbean plate with respect to SA and is characterized by a complex combination of convergent and strike-slip tectonics. To the north, the reflection data image the South Caribbean Deformed Belt (SCDB) and the structures related to the thrusting of the CAR plate under the Leeward Antilles volcanic arc region. The data show that the CAR underthrusting continues as far east as the southern edge of the Aves ridge and detailed stratigraphic dating of the Venezuela basin and trench deposits suggests that the collision began in the Paleogene. The amount of shortening along the SCDB decreases toward the east, in part due to the geometry of plate motion vectors and in part as a result of the NNE escape of the Maracaibo block in western Venezuela. South of the SCDB the MCS profiles cross the Leeward Antilles island arc and Cenozoic sedimentary basins, revealing a complex history of Paleogene-Neogene multiphase extension, compression, and tectonic inversion, as well as the influence of the tectonic activity along the right-lateral El Pilar - San Sebastian fault system. East of the Bonaire basin the MCS data image the southern end of the Aves Ridge abandoned volcanic island arc and the southwestern termination of the Grenada basin, characterized here by middle Miocene inverted structures, likely related to the WNW-ESE transpression between CAR and SA. The easternmost MCS profile crosses the ongoing arc-continent collision of the Lesser Antilles arc with SA and the backarc (Grenada Basin) and forearc (Tobago Basin) basins as well as the suture between the Caribbean arc and the passive margin of the continental SA plate near eastern Trinidad.