THE NW MARGIN OF SOUTH AMERICA IN JURASSIC TIME: SOUTHERN EFFECTS OF THE OPENING OF THE GULF OF MEXICO AND PROTO-CARIBBEAN TECTONICS
Depositional systems in those ranges are very similar, with dominance of red volcaniclastic strata, epiclastic deposits and volcanic rocks, and localized presence of magmatic centers. Stratigraphic thickness may reach 7-9 kms in some areas, and abrupt changes in thickness occur across normal faults. All of these deposits accumulated in an extensional regime, with rift-axis trend changing from N-S to ENE, and all the systems ending toward the Santander massif. The restored configuration of the Lower-Middle Jurassic subduction zone in the pacific margin also changes in strike at the latitude of the Santander massif. The Jurassic extensional basins and associated magmatic arcs in the northernmost South America plate and amalgamated Mexican terranes were more dispersed, in contrast to the linear trend a subduction magmatic arc father south. The development of the proto-Caribbean plate that separated Mexican and Colombian terranes, and the influence of the opening of the Gulf of Mexico, favored the formation of extensional basins along the NW corner of South America.