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  • 1
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    Deep structure of the central Lesser Antilles Island Arc : relevance for the formation of continental crust (2011)
    Elsevier
    In:  Earth and Planetary Science Letters, 304 (1-2). pp. 121-134.
    Details
    Publication Date: 2019-09-23
    Description: Oceanic island arcs are sites of high magma production and contribute to the formation of continental crust. Geophysical studies may provide information on the configuration and composition of island arc crust, however, to date only few seismic profiles exist across active island arcs, limiting our knowledge on the deep structure and processes related to the production of arc crust. We acquired active-source wide-angle seismic data crossing the central Lesser Antilles island arc north of Dominica where the oceanic Tiburon Ridge subducts obliquely beneath the forearc. A combined analysis of wide-angle seismics and pre-stack depth migrated reflection data images the complex structure of the backstop and its segmentation into two individual ridges, suggesting an intricate relation between subducted basement relief and forearc deformation. Tomographic imaging reveals three distinct layers composing the island arc crust. A three kilometer thick upper crust of volcanogenic sedimentary rocks and volcaniclastics is underlain by intermediate to felsic middle crust and plutonic lower crust. The island arc crust may comprise inherited elements of oceanic plateau material contributing to the observed crustal thickness. A high density ultramafic cumulates layer is not detected, which is an important observation for models of continental crust formation. The upper plate Moho is found at a depth of 24 km below the sea floor. Upper mantle velocities are close to the global average. Our study provides important information on the composition of the island arc crust and its deep structure, ranging from intermediate to felsic and mafic conditions. In this study we model the deep structure of the Lesser Antilles Island Arc. We use a hybrid analysis of refraction and reflection seismic data. We image the complex structure of two ridges forming the backstop. Island arc crust composition ranges from intermediate to felsic to mafic conditions. We discuss the formation of island arc and continental crust.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.epsl.2011.01.024
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Unknown
    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
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Unknown
    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
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
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