Missing history (16–71 Ma) of the Galápagos hotspot: Implications for the tectonic and biological evolution of the Americas

Abstract

We present the results of volcanological, geochemical, and geochronological studies of volcanic rocks from Malpelo Island on the Nazca plate (15.8–17.3 Ma) belonging to the Gala´pagos hotspot tracks, and igneous complexes (20.8–71.3 Ma) along the Pacific margin of Costa Rica and Panama. The igneous complexes consist of accreted portions of ocean island and seamount volcanoes and aseismic ridges, representing the missing (primarily subducted) history of the Gala´pagos hotspot. The age and geochemical data directly link the Gala´pagos hotspot tracks on the Pacific Ocean floor to the Caribbean large igneous province (ca. 72–95 Ma), confirming a Pacific origin for the Caribbean oceanic plateau from the Gala´pagos hotspot. We propose that emplacement of this oceanic plateau between the Americas and interaction of the Gala´pagos hotspot tracks with the Central American Arc played a fundamental role in the formation of land bridges between the Americas in Late Cretaceous–Paleocene and Pliocene-Holocene time. The land bridges allowed the exchange of terrestrial faunas (e.g., dinosaurs, mastodons, saber-tooth cats, and ground sloths) between the Americas and served as barriers for the exchange of marine organisms between the central Pacific Ocean and the Caribbean Sea and the central Atlantic Ocean.