Geldmacher, Jörg , Hoernle, Kaj , van den Bogaard, Paul, Hauff, Folkmar and Klügel, Andreas (2008) Age and Geochemistry of the Central American Forearc Basement (DSDP Leg 67 and 84): Insights into Mesozoic Arc Volcanism and Seamount Accretion on the Fringe of the Caribbean LIP. Journal of Petrology, 49 . pp. 1781-1815. DOI 10.1093/petrology/egn046.

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Abstract

The igneous forearc basement along the Pacific coast of northern Central America (between southern Mexico and Costa Rica) comprises a highly tectonized accretionary assemblage of igneous and ultramafic rocks. Volcanic and gabbroic rocks with primitive arc geochemical signatures formed between ∼100 and ≥180 Ma and are interpreted to have originated by arc magmatism resulting from subduction of the Pacific–Farallon plate. Geochemically enriched ocean island basalt (OIB)-like units are interpreted as accreted seamounts and islands of a hotspot track, which was active between ≥220 and 100 Ma and originated from a hotspot located in the central Pacific. Based on their combined Pb, Nd and Hf isotopic compositions an affiliation of these rocks with the Caribbean Large Igneous Province or the present-day Galápagos hotspot appears unlikely. Rocks of similar age and geochemistry are exposed on the Santa Elena Peninsula in Costa Rica, suggesting that a similar forearc basement is accreted to the continental Chortis Block from southern Mexico to Costa Rica.

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