Lithospheric structure of the Costa Rican Isthmus: Effects of subduction zone magmatism on an oceanic plateau

Sallarès, Valentı́; Dañobeitia, Juan José; Flueh, Ernst R.

doi:10.1029/2000jb900245

Cited by 73 publications

(109 citation statements)

References 73 publications

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“…The Caribbean overriding plate, for example, shows a dramatic thinning from 16 km at the coastline in Guatemala [Ye et al, 1996], far and not influenced by Cocos Ridge subduction , to 12-14 km in Nicoya [Christeson et al, 1999;Sallares et al, 2001], where the sharp increase in subduction erosion rate is in agreement with the beginning of thickened crust subduction , to 3 km in Osa Peninsula [Walther, 2003]. A general increase in erosional rates along the margin toward Cocos Ridge can also be inferred from the trench morphology, where a sudden landward shift of the trench axis strike occurs coincident with the area of Figure 13.…”

Section: Postsubduction Deformation: Osa Mélange Exhumationmentioning

confidence: 99%

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

Vannucchi¹,

et al. 2006

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The Costa Rica portion of the Middle America Trench (MAT) is characterized by active tectonic erosion, a process that causes the removal of material from the base of the upper plate as the plate boundary migrates upward. Offshore studies demonstrate accelerated subduction erosion starting at the Miocene‐Pliocene boundary, as the result of subduction of thickened Galapagos related crust, as presently represented by the Cocos Ridge. The subduction of the Cocos Ridge also caused uplift and exposure of the outer forearc on the Osa Peninsula, which offers a window to explore the tectonic evolution of the area. The rocks outcropping on Osa Peninsula are a middle Eocene–middle Miocene mélange dominated by basalt, chert, and limestone resulting from accretion of seamounts. The accretion‐dominated period of the MAT evolution ended at the Miocene‐Pliocene boundary, when thickened crust, a paleo‐Cocos Ridge, produced at the Galapagos hot spot arrived at the trench. The thick crust caused uplift and severe tectonic erosion of the accretionary edifice allowing exhumation of the Osa Mélange. The change from accretion to erosion caused the outer forearc to be offset along subvertical faults that define small (kilometer to tens of kilometers size) blocks that are going through differential vertical movements in response to the morphology of the subducting ridge. Subduction accretion and erosion are two processes that can alternate in time and space or coexist along the same margin, so that mass removal can develop on a previously growing margin and completely remove an accretionary prism.

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Section: Postsubduction Deformation: Osa Mélange Exhumationmentioning

confidence: 99%

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

Vannucchi¹,

et al. 2006

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“…Recent models using inversion techniques do not indicate a large Moho velocity contrast at these depths (Figure 2a) [Quintero and Güendel, 2000;Quintero and Kissling, 2001;Husen et al, 2003]. Using wide-angle P-wave refraction data in the Nicoya Peninsula region, Sallarès et al [2001] suggested the continental Moho dipped from 30 km depth at the subducting slab to 40 km depth inland and that decreased V P ($7.4 km/sec) in the forearc mantle wedge was evidence of serpentinization. Constraining the depth to the continental Moho and the V P and V S structure of the forearc mantle wedge will improve seismic hazard assessment of the downdip rupture limit of large magnitude earthquakes in this region.…”

Section: Introductionmentioning

confidence: 99%

Evidence for serpentinization of the forearc mantle wedge along the Nicoya Peninsula, Costa Rica

DeShon

Schwartz

2004

Geophysical Research Letters

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[1] Characterizing the hydration state of the forearc mantle wedge yields valuable information on frictional stability at the downdip edge of subduction megathrusts. Simultaneous inversion of P-and S-wave arrival times collected as part of the Costa Rica Seismogenic Zone Experiment yields 1D and 3D P-and S-wave velocity models (V P and V S ) for the Nicoya Peninsula segment of the Middle America Trench. Nicoya Peninsula 1D velocity models show similar velocity gradients to country-wide 1D velocity models from 5 -30 km depth but diverge at expected Moho depths due to proximity to the subducting Cocos plate. 3D V P values range from 7.2-7.6 km/sec in the forearc mantle wedge. Receiver functions computed at Global Seismic Network station JTS in northwestern Costa Rica confirm these V P values, yield V P /V S of $1.85, and place the continental Moho at 36 ± 4 km depth. V P and V P /V S are consistent with 15 -25% serpentinization of the forearc mantle wedge.

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“…Un nuevo cálculo de Q sin usar las estaciones RMOI y PGLF, que son las más lejanas, da un nuevo resultado: (9) en el que se puede ver que el valor es menor (lo que significa que existe mayor atenuación) que cuando se incluyen aquellas dos estaciones; sin embargo, los valores de dispersión son mayores que los de la ecuación 8. La mayor atenuación de la región central podría tener su explicación, al menos en parte, debido a que esta es una zona de fragilidad cortical primero por el vulcanismo existente (Sallares et al, 2001) y luego por el importante número de fallas que la atraviesan (Fernández & Montero, 2002). Estas fallas han generado terremotos importantes y bastante someros como el de Piedras Negras en 1990 y el que destruyó la ciudad de Cartago en 1910 (Montero & Miyamura, 1981).…”

Section: Discusión Y Resultadosunclassified

Inversión de efectos de sitio y factor Q utilizando cocientes espectrales

Fernández¹

2009

Estud. geol.

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Site effects and Q factor were inverted using the spectral ratio technique. The study area corresponds to central Costa Rica where the Earthquake Engineering Laboratory (INII-UCR) runs a strong motion network. The technique differs from the usual approach in that it makes use of a reference earthquake instead of a reference site. For that reason, the amplitude of the site effects that are obtained corresponds to the absolute amplification. The results indicate that stations located on soft sediment sites tend to have larger amplification values compared to other stations located on more compacted soils. The Q factor we obtained was frequency dependent with an approximate value of Q(f) = (131,6 ± 0,1)f (1,1 ± 0,2) .

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Lithospheric structure of the Costa Rican Isthmus: Effects of subduction zone magmatism on an oceanic plateau

Cited by 73 publications

References 73 publications

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

From seamount accretion to tectonic erosion: Formation of Osa Mélange and the effects of Cocos Ridge subduction in southern Costa Rica

Evidence for serpentinization of the forearc mantle wedge along the Nicoya Peninsula, Costa Rica

Inversión de efectos de sitio y factor Q utilizando cocientes espectrales

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