Latest Triassic to Early Cretaceous tectonics of the Northern Andes: Geochronology, geochemistry, isotopic tracing, and thermochronology

Abstract Triassic rifting within western Pangaea was followed by almost-continuous subduction beneath the western margin of northern South America, which was disturbed during the collision and accretion of the Caribbean Large Igneous Province (CLIP) at 75 Ma. We review a very large quantity of geochronological, geochemical, isotopic, and thermochronological data that are used to develop a coherent geological model for the period spanning the latest Triassic to the Early Cretaceous, prior to the collision of the CLIP. These data have been collected over a trench (Pacific)-parallel distance of > 1500 km (Colombia and Ecuador), and reveal continuous subduction within a long-lived extensional regime. The Pacific active margin commenced at 209 Ma, and continued until 115 Ma above an east-dipping subduction zone that was rolling back, attenuating South America and forming new continental crust. Oceanward arc migration occurred during 194–193 Ma, and was pronounced 144–115 Ma, while the arc spanned a width of ~ 100 km during 193–144 Ma, during which time its location may have oscillated relative to the trench. Extension during 144–115 Ma was significant, and generated isotopically juvenile, transitional crust, which is best preserved in Ecuador (Peltetec crust), and significant intra-arc basins (the Salado Basin), while continental slivers were temporarily rifted from South America. The amount of Early Cretaceous extension increased from Colombia toward southern Ecuador, perhaps due to increasing amounts of slab retreat. The opening of the South Atlantic drove South America westwards, compressed the Pacific margin of northwestern South America at 115 Ma, closed the Salado Basin, redocked para-autochthonous blocks and obducted and exhumed a subduction zone, which is now exposed proximal to the Early Cretaceous South American margin.