Interaction of the Galapagos plume with the southern Central American volcanic front:

Form the accretion of Galapagos-related oceanic complexes to the recent recycling of Galapagos tracks and the possible influx of Galapagos-modified mantle, the volcanic front of southern Central America is an ideal natural laboratory to study the effects of different interactions between a convergent margin and a mantle plume. I produced a detailed characterization of the different accreted oceanic complexes in southern Central America. This characterization was then incorporated in a regional that allowed me to reconstruct the evolution of the Galapagos Plume since its initial peak in the Cretaceous and through different types of interaction between the plume and the arc in southern Central America. I also contributed to the first quantitative comparison between modern ocean-island basalt (OIB) and large igneous provinces (LIPS) that show petrological evidence that the mantle sources of LIPS were hotter and more magmatically productive than modern-day OIB. Here I also present the geochemical evolution of the volcanic arc in Costa Rica since the Oligocene, where I discover that the volcanic front lavas were “normal arc lavas” until c. 6 Ma, where the Galapagos-OIB signature is first evident in the arc. I interpreted the appearance of the OIB signature as the result of the recent (10-8 Ma) recycling of the subducting Galapagos Hotspot Tracks. Interaction between partial melts of the Galapagos Tracks (Seamount Province and Cocos/Coiba Ridge) produced a metasomatic enrichment (re-fertilization) of the mantle in the wedge and the lithospere. I also present new petrologic and geochemical evidence that the Galapagos-modified asthenosphere may actually flow into the mantle wedge below southern Costa Rica and Panama, producing a broad thermal anomaly that triggered melting in the mantle wedge and in the previously re-fertilized lithosphere. From the accretion of exotic terranes to the recent recycling of the Galapagos hotspot tracks through the subduction system and the possible influx of Galapagos-modified asthenosphere, the geologic history of the convergent margin in Southern Central America has been characterized by long term interaction with the Galapagos Plume.Ph.D.Includes bibliographical referencesby Esteban Gazel Dond