Deep electrical resistivity structure of northwestern Costa Rica

Brasse, Heinrich; Kapinos, G.; Mütschard, Lutz; Alvarado, Guillermo E.; Worzewski, Tamara; Jegen, Marion

doi:10.1029/2008gl036397

Cited by 27 publications

(31 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This apparent lack of deep seismicity, together with the presence of the gap in Quaternary volcanism and an OIB-type geochemical signature for the volcanic rocks in the area (Hoernle et al, 2008), has led to several interpretations for the source of the adakites found in southeastern Costa Rica and western Panama (Fig. 5) (de Boer et al, 1991;Drummond et al, 1995). The hypothesis imply the melting of the slab edge by interaction with hot mantle through either a slab window (Johnston and Thorkelson, 1997;Abratis and Wörner, 2001) or a slab detachment (Gazel et al, 2011).…”

Section: Alternative Modelmentioning

confidence: 99%

“…White arrows show direction and rate of plate motions relative to the Caribbean Plate (fixed) according to DeMets et al (1994DeMets et al ( , 2010 and DeMets (2001). Plate boundaries modified from Coffin et al (1998) and Lonsdale (2005). Black lines depict the coastline and international borders.…”

Section: O H Lücke and I G Arroyo: Costa Rican Subduction Zone 2 mentioning

confidence: 99%

“…Receiver functions by Dzierma et al (2010Dzierma et al ( , 2011, respectively provide insights into the structure of the overriding plate and the geometry of the plate interface for the northwestern end of the Talamanca Range. Additionally, magneto-telluric surveys by Brasse et al (2009) andWorzewski et al (2010) provide information on the electrical properties of the lithosphere for northwestern Costa Rica and the fluid cycle of the subduction system.…”

Section: Geophysical Constraints On Geometry and Structurementioning

confidence: 99%

“…: Guatemala; Jam. : Jamaica; CCRDB: Central Costa Rica Deformed Belt; MPFS: Motagua-Polochic Fault System; ND: Nicaragua Depression; NPDB: North Panamá Deformed Belt; PFZ: Panamá Fracture Zone; RSB: rough-smooth boundary modified from Hey (1977); SITF: Swan Islands Fault; SR: Sandra Rift (de Boer et al, 1988). White contour represents the −2000 m bathymetric level outlining the Cocos Ridge, bathymetric data from global multi-resolution topography by Ryan et al (2009). 15 • N and continues 1100 km parallel to the MAT, ending at the Irazu-Turrialba volcanic complex in central Costa Rica (Fig.…”

Section: O H Lücke and I G Arroyo: Costa Rican Subduction Zone 2 mentioning

confidence: 99%

See 3 more Smart Citations

Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data

Lücke

Arroyo

2015

Solid Earth

View full text Add to dashboard Cite

Abstract. The eastern part of the oceanic Cocos Plate presents a heterogeneous crustal structure due to diverse origins and ages as well as plate-hot spot interactions which originated the Cocos Ridge, a structure that converges with the Caribbean Plate in southeastern Costa Rica. The complex structure of the oceanic plate directly influences the dynamics and geometry of the subduction zone along the Middle American Trench. In this paper an integrated interpretation of the slab geometry in Costa Rica is presented based on 3-D density modeling of combined satellite and surface gravity data, constrained by available geophysical and geological data and seismological information obtained from local networks. The results show the continuation of steep subduction geometry from the Nicaraguan margin into northwestern Costa Rica, followed by a moderate dipping slab under the Central Cordillera toward the end of the Central American Volcanic Arc. Contrary to commonly assumed, to the southeast end of the volcanic arc, our preferred model shows a steep, coherent slab that extends up to the landward projection of the Panama Fracture Zone. Overall, a gradual change in the depth of the intraplate seismicity is observed, reaching 220 km in the northwestern part, and becoming progressively shallower toward the southeast, where it reaches a maximum depth of 75 km. The changes in the terminal depth of the observed seismicity correlate with the increased density in the modeled slab. The absence of intermediate depth (> 75 km) intraplate seismicity in the southeastern section and the higher densities for the subducted slab in this area, support a model in which dehydration reactions in the subducted slab cease at a shallower depth, originating an anhydrous and thus aseismic slab.

show abstract

Section: Alternative Modelmentioning

confidence: 99%

Section: O H Lücke and I G Arroyo: Costa Rican Subduction Zone 2 mentioning

confidence: 99%

Section: Geophysical Constraints On Geometry and Structurementioning

confidence: 99%

Section: O H Lücke and I G Arroyo: Costa Rican Subduction Zone 2 mentioning

confidence: 99%

See 2 more Smart Citations

Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data

Lücke

Arroyo

2015

Solid Earth

View full text Add to dashboard Cite

show abstract

“…Strong constrains on fluid location is provided by electrical conductivity tomographic images (Baba, et al 2010;Brasse and Eydam 2008;Brasse, et al 2009;Ichiki, et al 2009). Over the last decade, the accuracy and The effect of hydration is to reduce sound velocities (green arrow).…”

Section: Magnetotelluricsmentioning

confidence: 99%

Mantle hydration and Cl-rich fluids in the subduction forearc

Reynard

2016

Prog. in Earth and Planet. Sci.

View full text Add to dashboard Cite

In the forearc region, aqueous fluids are released from the subducting slab at a rate depending on its thermal state. Escaping fluids tend to rise vertically unless they meet permeability barriers such as the deformed plate interface or the Moho of the overriding plate. Channeling of fluids along the plate interface and Moho may result in fluid overpressure in the oceanic crust, precipitation of quartz from fluids, and low Poisson ratio areas associated with tremors. Above the subducting plate, the forearc mantle wedge is the place of intense reactions between dehydration fluids from the subducting slab and ultramafic rocks leading to extensive serpentinization. The plate interface is mechanically decoupled, most likely in relation to serpentinization, thereby isolating the forearc mantle wedge from convection as a cold, potentially serpentinized and buoyant, body. Geophysical studies are unique probes to the interactions between fluids and rocks in the forearc mantle, and experimental constrains on rock properties allow inferring fluid migration and fluid-rock reactions from geophysical data. Seismic velocities reveal a high degree of serpentinization of the forearc mantle in hot subduction zones, and little serpentinization in the coldest subduction zones because the warmer the subduction zone, the higher the amount of water released by dehydration of hydrothermally altered oceanic lithosphere. Interpretation of seismic data from petrophysical constrain is limited by complex effects due to anisotropy that needs to be assessed both in the analysis and interpretation of seismic data. Electrical conductivity increases with increasing fluid content and temperature of the subduction. However, the forearc mantle of Northern Cascadia, the hottest subduction zone where extensive serpentinization was first demonstrated, shows only modest electrical conductivity. Electrical conductivity may vary not only with the thermal state of the subduction zone, but also with time for a given thermal state through variations of fluid salinity. High-Cl fluids produced by serpentinization can mix with the source rocks of the volcanic arc and explain geochemical signatures of primitive magma inclusions. Signature of deep high-Cl fluids was also identified in forearc hot springs. These observations suggest the existence of fluid circulations between the forearc mantle and the hot spring hydrothermal system or the volcanic arc. Such circulations are also evidenced by recent magnetotelluric profiles.

show abstract

Experimental constraints on the serpentinization rate of fore‐arc peridotites: Implications for the upwelling condition of the slab‐derived fluid

Nakatani

Nakamura

2016

Geochem Geophys Geosyst

View full text Add to dashboard Cite

To constrain the water circulation in subduction zones, the hydration rates of peridotites were investigated experimentally in fore‐arc mantle conditions. Experiments were conducted at 400–580°C and 1.3 and 1.8 GPa, where antigorite is expected to form as a stable serpentine phase. Crushed powders of olivine ± orthopyroxene and orthopyroxene + clinopyroxene were reacted with 15 wt % distilled water for 4–19 days. The synthesized serpentine varieties were lizardite and aluminous lizardite (Al‐lizardite) in all experimental conditions except those of 1.8 GPa and 580°C in the olivine + orthopyroxene system, in which antigorite was formed. In the olivine + orthopyroxene system, the reactions were interface‐controlled except for the reaction at 400°C, which was transport‐controlled. The corresponding reaction rates were 7.0 × 10−12 to 1.5 × 10−11 m s−1 at 500–580°C and 7.5 × 10−16 m2 s−1 at 400°C for the interface and transport‐controlled reactions, respectively. Based on a simple reaction‐transport model including these hydration rates, we infer that penetration of the slab‐derived fluid all the way through a water‐unsaturated fore‐arc mantle is allowed only when focused flow occurs with a spacing larger than 77–229 km in hot subduction zones such as Nankai and Cascadia. However, the necessary spacing is only 2.3–4.6 m in intermediate‐temperature subduction zones such as Kyushu and Costa Rica. These calculations imply that fluid leakage in hot subduction zones may occur after the fore‐arc mantle is totally hydrated, whereas in intermediate‐temperature subduction zones, leakage through a water‐unsaturated fore‐arc mantle may be facilitated.

show abstract

Deep electrical resistivity structure of northwestern Costa Rica

Cited by 27 publications

References 23 publications

Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data

Density structure and geometry of the Costa Rican subduction zone from 3-D gravity modeling and local earthquake data

Mantle hydration and Cl-rich fluids in the subduction forearc

Experimental constraints on the serpentinization rate of fore‐arc peridotites: Implications for the upwelling condition of the slab‐derived fluid

Contact Info

Product

Resources

About