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

Peter Dominic Clift, L H Chan, J Blusztajn, G D Layne, M Kastner, R K Kelly

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

[1] 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 epsilon(Nd) and maximum Li/Y consistent with very high degrees of sediment recycling at this time. However, overall Li/Y and delta Li-7 increase with SiO2 content, suggesting addition of heavy Li through forearc tectonic erosion and crustal assimilation. Peak values in delta Li-7 starting at 1.45 Ma and lasting similar to 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.

Original languageEnglish
Article numberQ09016
Number of pages21
JournalGeochemistry, Geophysics, Geosystems
Volume6
Issue number5
DOIs
Publication statusPublished - 27 Sep 2005

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Costa Rica
Tectonics
tephra
erosion
Erosion
tectonics
Sediments
sediments
subduction
accretion
arcs
seamounts
Geochemistry
assimilation
peninsulas
Trace Elements
geochemistry
sediment
recycling
drilling

Keywords

  • Costa Rica
  • subduction
  • geochemistry
  • tephra
  • volcanology
  • volcanoclastic deposits
  • subduction zone processes
  • Pacific ocean
  • lithium isotopic composition
  • american volcanic arc
  • slab-derived fluids
  • convergent margin
  • Pacific margin
  • regional variations
  • boron geochemistry
  • Nicoya peninsula
  • Northeast Japan
  • subarc mantle

Cite this

Pulsed subduction accretion and tectonic erosion reconstructed since 2.5 Ma from the tephra record offshore Costa Rica. / Clift, Peter Dominic; Chan, L H ; Blusztajn, J ; Layne, G D ; Kastner, M ; Kelly, R K .

In: Geochemistry, Geophysics, Geosystems , Vol. 6, No. 5, Q09016, 27.09.2005.

Research output: Contribution to journalArticle

Clift, Peter Dominic ; Chan, L H ; Blusztajn, J ; Layne, G D ; Kastner, M ; Kelly, R K . / Pulsed subduction accretion and tectonic erosion reconstructed since 2.5 Ma from the tephra record offshore Costa Rica. In: Geochemistry, Geophysics, Geosystems . 2005 ; Vol. 6, No. 5.
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abstract = "[1] 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 epsilon(Nd) and maximum Li/Y consistent with very high degrees of sediment recycling at this time. However, overall Li/Y and delta Li-7 increase with SiO2 content, suggesting addition of heavy Li through forearc tectonic erosion and crustal assimilation. Peak values in delta Li-7 starting at 1.45 Ma and lasting similar to 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.",
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AU - Layne, G D

AU - Kastner, M

AU - Kelly, R K

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KW - Costa Rica

KW - subduction

KW - geochemistry

KW - tephra

KW - volcanology

KW - volcanoclastic deposits

KW - subduction zone processes

KW - Pacific ocean

KW - lithium isotopic composition

KW - american volcanic arc

KW - slab-derived fluids

KW - convergent margin

KW - Pacific margin

KW - regional variations

KW - boron geochemistry

KW - Nicoya peninsula

KW - Northeast Japan

KW - subarc mantle

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JO - Geochemistry, Geophysics, Geosystems

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