Fig. 2. The Isthmus of Panama and northwestern Colombia with locations of some crystalline rocks (igneous and metamorphic) with reported Paleocene-Eocene radiometric ages (squares and triangles).

Montes et al. (15) proposed that Eocene detrital zircons in middle Miocene sediments of the Magdalena Basin (blue dots) could only be from plutonic rocks of the Panama Arc (dark green outline). However, several other rock units (for example, Western, Central, and Eastern Cordilleras plus the Sierra Nevada de Santa Marta; red outlines and table S2) exhibit radiometric ages in the same interval and therefore must also be considered as potential sources. From previous studies (24–26, 30, 31, 132).