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  • 1
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    Crustal thickness and mantle wedge structure from receiver functions in the Chilean Maule region at 35°S (2013)
    Elsevier
    In:  Tectonophysics, 592 . pp. 159-164.
    Details
    Publication Date: 2019-09-24
    Description: A temporary passive seismic network of 21 broad-band stations was deployed in Central Chile between 35°S to 36°S. The network recorded data prior to the magnitude Mw = 8.8 2010 Maule earthquake at a latitude of the major slip and surface deformation. The experiment was conducted to survey crustal and mantle structures and to assess the state of hydration of the mantle wedge. We present results of a teleseismic P receiver function study, supporting a continental Moho at approx. 38 km depth. Phase conversion at this boundary could be observed continuously from the intersection of the subducting slab with the continental Moho towards the Andes. The character of receiver functions indicated little evidence for infiltration of water from the subducting plate into the overlying mantle wedge, suggesting that only a small amount of water is released from the subducting plate. Aftershocks of the Maule earthquake and post-seismic slip reached depths of 50 km and hence slip spread down-dip of the continental Moho in the post-seismic phase. Co-seismic rupture, however, occurred updip of the continental Moho. Spare aftershock seismicity is observed at the intersection of the continental Moho with the subducting slab.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.tecto.2013.02.015
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Structure and geodynamics of the post-collision zone between the Nazca–Antarctic spreading center and South America (2012)
    Elsevier
    In:  Earth and Planetary Science Letters, 345/348 . pp. 27-37.
    Details
    Publication Date: 2019-09-23
    Description: The Chile Triple Junction (CTJ) is the place where the Chile Ridge (Nazca–Antarctic spreading center) is subducting beneath the continental South American plate. Sediment accretion is active to the south of the CTJ in the area where the northward migrating Chile Ridge has collided with the continent since 14 Ma. At the CTJ, tectonic erosion of the overriding plate narrows and steepens the continental slope. We present here a detailed tomographic image of the upper lithospheric Antarctic–South America subduction zone where the Chile Ridge collided with the continent 3–6 Ma off Golfo de Penas. Results reveal that a large portion of trench sediment has been scraped off and frontally accreted to the forearc forming a 70–80 km wide accretionary prism. The velocity–depth model shows a discontinuity at 30–40 km landward of the deformation front, which is interpreted as the contact between the frontal (poorly consolidated sedimentary unit) and middle (more compacted sedimentary unit) accretionary prism. The formation of this discontinuity could be related to a short term episode of reduced trench sedimentation. In addition, we model the shape of the continental slope using a Newtonian fluid rheology to study the convergence rate at which the accretionary prism was formed. Results are consistent with an accretionary prism formed after the collision of the Chile Ridge under slow convergence rate similar to those observed at present between Antarctic and South America (∼2.0 cm/a). Based on the kinematics of the Chile Ridge subduction during the last 13 Ma, we propose that the accretionary prism off Golfo de Penas was formed recently (∼5 Ma) after the collision of the Chile Ridge with South America.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2012.06.023
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Revealing the deep structure and rupture plane of the 2010 Maule, Chile earthquake (Mw=8.8) using wide angle seismic data (2011)
    Elsevier
    In:  Earth and Planetary Science Letters, 307 . pp. 147-155.
    Details
    Publication Date: 2017-06-08
    Description: The 27 February, 2010 Maule earthquake (Mw=8.8) ruptured ~400 km of the Nazca-South America plate boundary and caused hundreds of fatalities and billions of dollars in material losses. Here we present constraints on the fore-arc structure and subduction zone of the rupture area derived from seismic refraction and wide-angle data. The results show a wedge shaped body ~40 km wide with typical sedimentary velocities interpreted as a frontal accretionary prism (FAP). Landward of the imaged FAP, the velocity model shows an abrupt velocity-contrast, suggesting a lithological change which is interpreted as the contact between the FAP and the paleo accretionary prism (backstop). The backstop location is coincident with the seaward limit of the aftershocks, defining the updip limit of the co-seismic rupture and seismogenic zone. Furthermore, the seaward limit of the aftershocks coincides with the location of the shelf break in the entire earthquake rupture area (33°S–38.5°S), which is interpreted as the location of the backstop along the margin. Published seismic profiles at the northern and southern limit of the rupture area also show the presence of a strong horizontal velocity gradient seismic backstop at a distance of ~30 km from the deformation front. The seismic wide-angle reflections from the top of the subducting oceanic crust constrain the location of the plate boundary offshore, dipping at ~10°. The projection of the epicenter of the Maule earthquake onto our derived interplate boundary yielded a hypocenter around 20 km depth, this implies that this earthquake nucleated somewhere in the middle of the seismogenic zone, neither at its updip nor at its downdip limit.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2011.04.025
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Crustal intrusion beneath the Louisville hotspot track (2010)
    Elsevier
    In:  Earth and Planetary Science Letters, 289 . pp. 323-333.
    Details
    Publication Date: 2019-09-23
    Description: We report here the first detailed 2D tomographic image of the crust and upper mantle structure of a Cretaceous seamount that formed during the interaction of the Pacific plate and the Louisville hotspot. Results show that at ∼ 1.5 km beneath the seamount summit, the core of the volcanic edifice appears to be dominantly intrusive, with velocities faster than 6.5 km/s. The edifice overlies both high lower crustal (〉 7.2–7.6 km/s) and upper mantle (〉 8.3 km/s) velocities, suggesting that ultramafic rocks have been intruded as sills rather than underplated beneath the crust. The results suggest that the ratio between the volume of intra-crustal magmatic intrusion and extrusive volcanism is as high as ∼ 4.5. In addition, the inversion of Moho reflections shows that the Pacific oceanic crust has been flexed downward by up to ∼ 2.5 km beneath the seamount. The flexure can be explained by an elastic plate model in which the seamount emplaced upon oceanic lithosphere that was ∼ 10 Myr at the time of loading. Intra-crustal magmatic intrusion may be a feature of hotspot volcanism at young, hot, oceanic lithosphere, whereas, magmatic underplating below a pre-existing Moho may be more likely to occur where a hotspot interacts with oceanic lithosphere that is several tens of millions of years old.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Format: text
    DOI: 10.1016/j.epsl.2009.11.020
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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