Geologic and Tectonic Development of the Caribbean Plate Boundary in Southern Central America

Early Tertiary arc volcanics from eastern Panama Available to Purchase
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Published:January 01, 1995
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CiteCitation
René C. Maury, Marc J. Defant, Hervé Bellon, Jelle Zeilinga de Boer, Robert H. Stewart, Joseph Cotten, 1995. "Early Tertiary arc volcanics from eastern Panama", Geologic and Tectonic Development of the Caribbean Plate Boundary in Southern Central America, Paul Mann
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Early Tertiary volcanic clasts were collected from the streambed of the Rio Morti near the village of Morti, eastern Panama, as part of a reconnaissance study. The samples range from basalts to rhyolites. K-Ar dates cluster around 58 Ma. The phenocryst mineralogy of the samples is typical of that found in arc-related volcanics: plagioclase (the dominant phase), clinopyroxene, titanomagnetite, and minor orthopyroxene. The clinopyroxenes are augites that plot in the field of orogenic lavas. The geochemistry of the rocks—high ratios of large-ion lithophile elements to high-field strength elements, negative Nb and Ta anomalies, positive Ba anomalies, and relatively low Th to U values—confirms that they are arc related (specifically the calc-alkaline series) and strongly suggests that the samples are not cogenetic.
Volcanic rocks with similar ages are exposed in several other localities throughout Panama and Costa Rica (e.g., the Azuero and Sona Peninsulas in Panama and the Nicoya Peninsula in Costa Rica as well as other areas in the Darien of eastern Panama). We suggest that there may have been a more or less continuous arc from South America to the Chortis block of Nicaragua during the Paleocene-Early Eocene. The presence of the arc would imply that the breakup of the Farallon plate and its subduction below the new Caribbean plate in present-day southern Central America probably started some time close to the Cretaceous-Tertiary boundary.
- absolute age
- basalts
- calc-alkalic composition
- Caribbean Plate
- Caribbean region
- Cenozoic
- Central America
- Chortis Block
- clasts
- Costa Rica
- Cretaceous
- Darien
- dates
- East Pacific
- Eocene
- Farallon Plate
- Gulf of Panama
- igneous rocks
- island arcs
- K-T boundary
- K/Ar
- lithophile elements
- lower Eocene
- lower Paleocene
- lower Tertiary
- major elements
- Mesozoic
- mineral composition
- Nicaragua
- Nicoya Peninsula
- North Pacific
- Northeast Pacific
- Pacific Ocean
- Paleocene
- Paleogene
- Panama
- petrography
- phenocrysts
- plate tectonics
- rhyolites
- sampling
- spectra
- stratigraphic boundary
- stratovolcanoes
- subduction
- Tertiary
- trace elements
- Upper Cretaceous
- volcanic rocks
- volcanoes
- Azuero Peninsula
- Sona Peninsula
- eastern Panama
- Rio Morti
- V-El
- B-El Baru
- Morti Panama