Upper lithospheric structure of the subduction zone offshore of southern Arauco peninsula, Chile, at ∼38°S

Contreras‐Reyes, Eduardo; Grevemeyer, Ingo; Flueh, Ernst R.; Reichert, Christian

doi:10.1029/2007jb005569

Cited by 112 publications

(156 citation statements)

References 55 publications

(125 reference statements)

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“…This is in agreement with Nazca plate oceanic crustal thicknesses from other studies (e.g. Krawczyk et al 2006;Contreras-Reyes et al 2008a).…”

Section: Correlating S-wave Velocity and Poisson's Ratio Models To Otsupporting

confidence: 82%

“…Strong lithospheric hydration, which was independently corroborated by Tilmann et al (2008) and Contreras-Reyes et al (2008a), occurs due to bendingrelated faulting at the outer rise offshore. This allows the percolation of sea water down to the upper oceanic mantle (Contreras-Reyes et al 2008a). Poisson's ratios in the oceanic crust and upper mantle are lower onshore than they are offshore, showing the effect of the dehydration of the oceanic plate during the subduction process.…”

Section: Poisson's Ratio Model V P /V S Ratio Model and Observed Clumentioning

confidence: 85%

“…Due to bending-related faulting at the outer rise offshore, the oceanic crust and upper mantle are hydrated (Contreras-Reyes et al 2008a), explaining high Poisson's ratios observed offshore (∼0.28-0.33 in the oceanic crust and ∼0.29 in the upper mantle) (ContrerasReyes et al 2008b). Onshore, however, these values decrease.…”

Section: Correlating S-wave Velocity and Poisson's Ratio Models To Otmentioning

confidence: 99%

“…The yellow and magenta lines mark the CDP line of the SPOC onshore seismic reflection profile and the SPOC wide-angle refraction profile (SPOC WA), respectively (Krawczyk & the SPOC Team 2003). The green line marks the easternmost part of the integrated TIPTEQ and SPOC reflection and refraction wide-angle offshore profile (Contreras-Reyes et al 2008a). The red line maps the surface trace of the Lanalhue fault zone (LFZ; after Melnick & Echtler 2006).…”

Section: Introductionmentioning

confidence: 99%

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Shear wave velocity and Poisson's ratio models across the southern Chile convergent margin at 38°15′S

2016

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“…This is in agreement with Nazca plate oceanic crustal thicknesses from other studies (e.g. Krawczyk et al 2006;Contreras-Reyes et al 2008a).…”

Section: Correlating S-wave Velocity and Poisson's Ratio Models To Otsupporting

confidence: 82%

Section: Poisson's Ratio Model V P /V S Ratio Model and Observed Clumentioning

confidence: 85%

Section: Correlating S-wave Velocity and Poisson's Ratio Models To Otmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Shear wave velocity and Poisson's ratio models across the southern Chile convergent margin at 38°15′S

2016

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“…Large earthquake ruptures along the margin tend to occur within highly coupled segments (Métois et al, 2012). We focus on the Maule segment, which is demarcated by the Mocha Block to the south and the Juan Fernández Ridge to the north (Contreras-Reyes et al, 2013). The Maule segment last fully ruptured during the great 1835 Concepción earthquake and was recognised as a mature seismic gap (e.g.…”

Section: Characteristics Of the Central Chile Subduction Zonementioning

confidence: 99%

Anatomy of a megathrust: The 2010 M8.8 Maule, Chile earthquake rupture zone imaged using seismic tomography

Hicks

Rietbrock

Ryder

et al. 2014

Earth and Planetary Science Letters

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Knowledge of seismic velocities in the seismogenic part of subduction zones can reveal how material properties may influence large ruptures. Observations of aftershocks that followed the 2010 M w 8.8 Maule, Chile earthquake provide an exceptional dataset to examine the physical properties of a megathrust rupture zone. We manually analysed aftershocks from onshore seismic stations and ocean bottom seismometers to derive a 3-D velocity model of the rupture zone using local earthquake tomography. From the trench to the magmatic arc, our velocity model illuminates the main features within the subduction zone. We interpret an east-dipping high P-wave velocity anomaly (>6.9 km/s) as the subducting oceanic crust and a low P-wave velocity (<6.25 km/s) in the marine forearc as the accretionary complex. We find two large P-wave velocity anomalies (∼7.8 km/s) beneath the coastline. These velocities indicate an ultramafic composition, possibly related to extension and a mantle upwelling during the Triassic. We assess the role played by physical heterogeneity in governing megathrust behaviour. Greatest slip during the Maule earthquake occurred in areas of moderate P-wave velocity (6.5-7.5 km/s), where the interface is structurally more uniform. At shallow depths, high fluid pressure likely influenced the up-dip limit of seismic activity. The high velocity bodies lie above portions of the plate interface where there was reduced coseismic slip and minimal postseismic activity. The northern velocity anomaly may have acted as a structural discontinuity within the forearc, influencing the pronounced crustal seismicity in the Pichilemu region. Our work provides evidence for how the ancient geological structure of the forearc may influence the seismic behaviour of subduction megathrusts.

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Serpentinization of mantle‐derived peridotites at mid‐ocean ridges: Mesh texture development in the context of tectonic exhumation

Rouméjon

Cannat

2014

Geochem Geophys Geosyst

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At slow spreading ridges, axial detachment faults exhume mantle-derived peridotites and hydrothermal alteration causes serpentinization in a domain extending more than 1 km next to the fault. At the microscopic scale, serpentinization progresses from a microfracture network toward the center of olivine relicts and forms a mesh texture. We present a petrographic study (SEM, EBSD, and Raman) of the serpentine mesh texture in a set of 278 abyssal serpentinized peridotites from the Mid-Atlantic and Southwest Indian Ridges. We show that serpentinization initiated along two intersecting sets of microfractures that have consistent orientations at the sample scale, and in at least one studied location, at the 100 m scale. We propose that these microfractures formed in fresh peridotites due to combined thermal and tectonic stresses and subsequently served as channels for serpentinizing fluids. Additional reaction-induced cracks developed for serpentinization extents <20%. The resulting microfracture network has a typical spacing of $60 mm but most serpentinization occurs next to a subset of these microfractures that define mesh cells 100-400 mm in size. Apparent mesh rim thickness is on average 33 6 19 mm corresponding to serpentinization extents of 70-80%. Published laboratory experiments suggest that mesh rims formation could be completed in a few years (i.e., quasi instantaneous at the plate tectonic timescale). The depth and extent of the serpentinization domain in the detachment fault's footwall are probably variable in time and space and as a result we expect that the serpentine mesh texture at slow spreading ridges forms at variable rates with a spatially heterogeneous distribution.

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Upper lithospheric structure of the subduction zone offshore of southern Arauco peninsula, Chile, at ∼38°S

Cited by 112 publications

References 55 publications

Shear wave velocity and Poisson's ratio models across the southern Chile convergent margin at 38°15′S

Shear wave velocity and Poisson's ratio models across the southern Chile convergent margin at 38°15′S

Anatomy of a megathrust: The 2010 M8.8 Maule, Chile earthquake rupture zone imaged using seismic tomography

Serpentinization of mantle‐derived peridotites at mid‐ocean ridges: Mesh texture development in the context of tectonic exhumation

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