Pulsed subduction accretion and tectonic erosion reconstructed since 2.5 Ma from the tephra record offshore Costa Rica
Clift, Peter D.
Blusztajn, Jerzy S.
Layne, Graham D.
Kelly, Robyn K.
MetadataShow full item record
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.
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.
Showing items related by title, author, creator and subject.
Seismic evidence for fluids in fault zones on top of the subducting Cocos Plate beneath Costa Rica Van Avendonk, Harm J. A.; Holbrook, W. Steven; Lizarralde, Daniel; Mora, Mauricio M.; Harder, Steven H.; Bullock, Andrew D.; Alvarado, Guillermo E.; Ramirez, Carlos J. (John Wiley & Sons, 2010-03-09)In the 2005 TICOCAVA explosion seismology study in Costa Rica we observed crustal turning waves with a dominant frequency of ~10 Hz on a linear array of short-period seismometers from the Pacific Ocean to the Caribbean ...
Van Avendonk, Harm J. A.; Holbrook, W. Steven; Lizarralde, Daniel; Denyer, P. (American Geophysical Union, 2011-06-22)The Cocos plate experiences extensional faulting as it bends into the Middle American Trench (MAT) west of Nicaragua, which may lead to hydration of the subducting mantle. To estimate the along strike variations of volatile ...
Nitrogen cycling in the secondary nitrite maximum of the eastern tropical North Pacific off Costa Rica Buchwald, Carolyn; Santoro, Alyson E.; Stanley, Rachel H. R.; Casciotti, Karen L. (John Wiley & Sons, 2015-12-15)Nitrite is a central intermediate in the marine nitrogen cycle and represents a critical juncture where nitrogen can be reduced to the less bioavailable N2 gas or oxidized to nitrate and retained in a more bioavailable ...