@article{fdi:010063152,
  title = {{F}lat versus normal subduction zones : a comparison based on 3-{D} regional traveltime tomography and petrological modelling of central {C}hile and western {A}rgentina (29 degrees-35 degrees {S})},
  author = {{M}arot, {M}. and {M}onfret, {T}ony and {G}erbault, {M}uriel and {N}olet, {G}. and {R}analli, {G}. and {P}ardo, {M}.},
  editor = {},
  language = {{ENG}},
  abstract = {{O}ur study compares the seismic properties between the flat and normal subduction regions in central {C}hile, to better understand the links between the slab geometry, surface deformation and the deeper structures. {I}n comparison with previous studies, we show the most complete 3-{D} regional seismic tomography images for this region, in which we use (1) a larger seismic data set compiled from several short-term seismic catalogues, (2) a denser seismic array allowing a better resolution of the subduction zone from the trench to the backarc and into the upper similar to 30 km of the slab and (3) a starting 1-{D} background velocity model specifically calculated for this region and refined over the years. {W}e assess and discuss our tomography results using regional seismic attenuation models and estimating rock types on the basis of pressure and temperature conditions computed from thermomechanical models. {O}ur results show significant seismic differences between the flat and normal subduction zones. {A}s expected, the faster seismic velocities and increased seismicity within the flat slab and overriding lithosphere are generally consistent with a cooler thermal state. {O}ur results are also consistent with dehydration of the mantle above the subducted {J}uan {F}ernandez {R}idge at the eastern tip of the flat slab segment, indicating that the latter retains some fluids during subduction. {H}owever, fluids in the upper portion of the flat slab segment are not seismically detected, since we report instead fast slab seismic velocities which contradict the argument of its buoyancy being the cause of horizontal subduction. {T}he forearc region, above the flat slab, exhibits high {V}s and very low {V}p/{V}s ratios, uncorrelated with typical rock compositions, increased density or reduced temperature; this feature is possibly linked with the aftershock effects of the {M}w7.1 1997 {P}unitaqui earthquake, the flat slab geometry and/or seismic anisotropy. {A}t the surface, the seismic variations correlate with the geological terranes. {T}he {A}ndean crust is strongly reduced in seismic velocities along the {L}a {R}amada-{A}concagua deformation belt, suggesting structural damage. {S}low seismic velocities along the {A}ndean {M}oho match non-eclogitized hydrated rocks, consistent with a previous delamination event or a felsic composition, which in turn supports the extent of the {C}hilenia terrane at these depths. {W}e confirm previous studies that suggest that the {C}uyania terrane in the backarc region is mafic and contains an eclogitized lower crust below 50-km depth. {W}e also hypothesize major {A}ndean basement detachment faults (or shear zones) to extend towards the plate interface and canalize slab-derived fluids into the continental crust.},
  keywords = {{S}eismicity and tectonics ; {S}eismic tomography ; {S}ubduction zone processes ; {D}ynamics: seismotectonics ; {S}outh {A}merica ; {CHILI} ; {ARGENTINE}},
  booktitle = {},
  journal = {{G}eophysical {J}ournal {I}nternational},
  volume = {199},
  numero = {3},
  pages = {1633--1654},
  ISSN = {0956-540{X}},
  year = {2014},
  DOI = {10.1093/gji/ggu355},
  URL = {https://www.documentation.ird.fr/hor/fdi:010063152},
}