The Caribbean and Farallon Plates Connected: Constraints From Stratigraphy and Paleomagnetism of the Nicoya Peninsula, Costa Rica

Plate kinematic reconstructions play an essential role in our understanding of global geodynamics, but become increasingly difficult to constrain back in geological time due to the subduction of oceanic lithosphere. Here, we attempt to kinematically reconstruct the Cretaceous and older plate tectonic history of the Caribbean Plate within the Mesozoic Panthalassa (paleo-Pacific) Ocean. To this end, we present new paleomagnetic data from Jurassic and Cretaceous oceanic sedimentary and volcanic Large Igneous Province-related rocks of the Nicoya Peninsula and Murcielago Islands of northwestern Costa Rica. We use these data, in combination with constraints from marine magnetic anomalies to infer the age of the lithospheric basement, seismic tomography to locate deep-mantle plume generation zones, and general kinematic feasibility, to test different reconstruction scenarios connecting the Caribbean Plate to the Farallon Plate as restored from Pacific spreading records. Our resulting reconstruction implies that the western Caribbean subduction zone initiated around 100 Ma, in an intraoceanic setting, breaking up oceanic lithosphere of at least 70 Myr old.