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Peirce, C. [VerfasserIn]; Robinson, A. H. [VerfasserIn]; Campbell, A. M. [VerfasserIn]; Funnell, M. J. [VerfasserIn]; Grevemeyer, Ingo [VerfasserIn]; Hayman, N. W. [VerfasserIn]; Van Avendonk, H. J. A. [VerfasserIn]; Castiello, G. [VerfasserIn]

Seismic investigation of an active ocean–continent transform margin: the interaction between the Swan Islands Fault Zone and the ultraslow-spreading Mid-Cayman Spreading Centre

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  • Medientyp: E-Artikel
  • Titel: Seismic investigation of an active ocean–continent transform margin: the interaction between the Swan Islands Fault Zone and the ultraslow-spreading Mid-Cayman Spreading Centre
  • Beteiligte: Peirce, C. [VerfasserIn]; Robinson, A. H. [VerfasserIn]; Campbell, A. M. [VerfasserIn]; Funnell, M. J. [VerfasserIn]; Grevemeyer, Ingo [VerfasserIn]; Hayman, N. W. [VerfasserIn]; Van Avendonk, H. J. A. [VerfasserIn]; Castiello, G. [VerfasserIn]
  • Erschienen: Oxford University Press, 2019-10
  • Sprache: Englisch
  • DOI: https://doi.org/10.1093/gji/ggz283
  • Entstehung:
  • Anmerkungen: Diese Datenquelle enthält auch Bestandsnachweise, die nicht zu einem Volltext führen.
  • Beschreibung: The Swan Islands Transform Fault (SITF) marks the southern boundary of the Cayman Trough and the ocean–continent transition of the North American–Caribbean Plate boundary offshore Honduras. The CAYSEIS experiment acquired a 180-km-long seismic refraction and gravity profile across this transform margin, ∼70 km to the west of the Mid-Cayman Spreading Centre (MCSC). This profile shows the crustal structure across a transform fault system that juxtaposes Mesozoic-age continental crust to the south against the ∼10-Myr-old ultraslow spread oceanic crust to the north. Ocean-bottom seismographs were deployed along-profile, and inverse and forward traveltime modelling, supported by gravity analysis, reveals ∼23-km-thick continental crust that has been thinned over a distance of ∼70 km to ∼10 km-thick at the SITF, juxtaposed against ∼4-km-thick oceanic crust. This thinning is primarily accommodated within the lower crust. Since Moho reflections are not widely observed, the 7.0 km s−1 velocity contour is used to define the Moho along-profile. The apparent lack of reflections to the north of the SITF suggests that the Moho is more likely a transition zone between crust and mantle. Where the profile traverses bathymetric highs in the off-axis oceanic crust, higher P-wave velocity is observed at shallow crustal depths. S-wave arrival modelling also reveals elevated velocities at shallow depths, except for crust adjacent to the SITF that would have occupied the inside corner high of the ridge-transform intersection when on axis. We use a Vp/Vs ratio of 1.9 to mark where lithologies of the lower crust and uppermost mantle may be exhumed, and also to locate the upper-to-lower crustal transition, identify relict oceanic core complexes and regions of magmatically formed crust. An elevated Vp/Vs ratio suggests not only that serpentinized peridotite may be exposed at the seafloor in places, but also that seawater has been able to flow deep into the crust and upper mantle over 20–30-km-wide regions which may explain the lack of a ...
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