Pulsed subduction accretion and tectonic erosion reconstructed since 2.5 Ma from the tephra record offshore Costa Rica

dc.contributor.author Clift, Peter D.
dc.contributor.author Chan, Lui-Heung
dc.contributor.author Blusztajn, Jerzy S.
dc.contributor.author Layne, Graham D.
dc.contributor.author Kastner, Miriam
dc.contributor.author Kelly, Robyn K.
dc.date.accessioned 2006-01-25T19:34:01Z
dc.date.available 2006-01-25T19:34:01Z
dc.date.issued 2005-09-27
dc.description Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 6 (2005): Q09016, doi:10.1029/2005GC000963.
dc.description.abstract Tephra layers recovered by Ocean Drilling Program from the forearc and trench regions offshore the Nicoya Peninsula of Costa Rica allow the temporal evolution of the volcanic arc to be reconstructed since 2.5 Ma. Major and trace element analyses by microprobe methods reveal a dominant tholeiitic character and a provenance in the Costa Rican area. The tephra show long-term coherent variability in geochemistry. One tephra dated at 1.45 Ma shows minimum values in ɛ Nd and maximum Li/Y consistent with very high degrees of sediment recycling at this time. However, overall Li/Y and δ7Li increase with SiO2 content, suggesting addition of heavy Li through forearc tectonic erosion and crustal assimilation. Peak values in δ7Li starting at 1.45 Ma and lasting ∼0.5 m.y. indicate enhanced tectonic erosion of the forearc possibly caused by subduction of a seamount at 1.45 Ma. The tephra record indicates significant temporal variability in terms of sediment subduction, reconciling the geologic evidence for long-term tectonic erosion and geochemical evidence for recent sediment accretion in the modern Central American arc. en
dc.description.sponsorship Financial support for the analytical work was gratefully received from JOI-USSAC. The lithium isotope work was supported in part by National Science Foundation grant OCE-990554 to L.H.C. en
dc.format.extent 1261051 bytes
dc.format.mimetype application/pdf
dc.identifier.citation Geochemistry Geophysics Geosystems 6 (2005): Q09016 en
dc.identifier.doi 10.1029/2005GC000963
dc.identifier.uri https://hdl.handle.net/1912/446
dc.language.iso en_US en
dc.publisher American Geophysical Union en
dc.relation.uri https://doi.org/10.1029/2005GC000963
dc.subject Costa Rica en
dc.subject Subduction en
dc.subject Geochemistry en
dc.subject Tephra en
dc.title Pulsed subduction accretion and tectonic erosion reconstructed since 2.5 Ma from the tephra record offshore Costa Rica en
dc.type Article en
dspace.entity.type Publication
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