“…South of this boundary, the Costa Rican isthmus is floored by a CLIP-like mafic basement (geophysical studies: Sallar es, Dañobeitia, & Flueh, 2001;Brasse et al, 2009;geochemical study: Feigenson, Carr, Maharaj, Juliano, & Bolge, 2004). It is not possible to distinguish the Manzanillo Terrane from the (Schmidt-Effing, 1979;Bandini et al, 2008) Planktonic Foraminifera (Azéma & Tournon, 1979) 40Ar/39Ar age (Sinton et al, , 2009Alvarado et al, 1997;Hauff et al, 2000;Hoernle et al, 2004: Madrigal et al, 2016 87Sr/86Sr on Inoceramus (Flores et al, 2003a;Weber, 2013) Radiolaria (this study) Nicoya Complex on the basis of plateau geochemistry alone. The distinction between the two terranes is mainly based on their age characteristics and on age and facies of the associated sediments (see below).…”