Along-strike structure of the Costa Rican convergent margin from seismic a refraction/reflection survey: Evidence for underplating beneath the inner forearc
| Autor: | W. S. Holbrook, J. T. St Clair, H. J. Van Avendonk, Daniel Lizarralde |
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| Rok vydání: | 2016 |
| Předmět: |
Underplating
geography geography.geographical_feature_category 010504 meteorology & atmospheric sciences Mantle wedge Subduction Seamount Subsidence 010502 geochemistry & geophysics 01 natural sciences Geophysics Basement (geology) Geochemistry and Petrology Magma Forearc Seismology Geology 0105 earth and related environmental sciences |
| Zdroj: | Geochemistry, Geophysics, Geosystems. 17:501-520 |
| ISSN: | 1525-2027 |
| DOI: | 10.1002/2015gc006029 |
| Popis: | The convergent margin offshore Costa Rica shows evidence of subsidence due to subduction erosion along the outer forearc and relatively high rates of uplift (∼3–6 mm/yr) along the coast. Recently erupted arc lavas exhibit a low 10Be signal, suggesting that although nearly the entire package of incoming sediments enters the subduction zone, very little of that material is carried directly with the downgoing Cocos plate to the magma generating depths of the mantle wedge. One mechanism that would explain both the low 10Be and the coastal uplift is the underplating of sediments, tectonically eroded material, and seamounts beneath the inner forearc. We present results of a 320 km long, trench-parallel seismic reflection and refraction study of the Costa Rican forearc. The primary observations are (1) margin perpendicular faulting of the basement, (2) thickening of the Cocos plate to the northwest, and (3) two weak bands of reflections in the multichannel seismic (MCS) reflection image with travel times similar to the top of the subducting Cocos plate. The modeled depths to these reflections are consistent with an ∼40 km long, 1–3 km thick region of underplated material ∼15 km beneath some of the highest observed coastal uplift rates in Costa Rica. |
| Databáze: | OpenAIRE |
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