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Publication - Dr David Schlaphorst

    Probing layered arc crust in the Lesser Antilles using receiver functions

    Citation

    Schlaphorst, D, Melekhova, L, Kendall, JM, Blundy, J & Latchman, JL, 2018, ‘Probing layered arc crust in the Lesser Antilles using receiver functions’. Royal Society Open Science, vol 5.

    Abstract

    Oceanic arcs can provide insight into the processes of crustal growth
    and crustal structure. In this work, changes in crustal thickness and
    composition along the Lesser Antilles Arc (LAA) are analysed at 10
    islands using receiver function (RF) inversions that combine
    seismological data with vP/vS ratios estimated
    based on crustal lithology. We collected seismic data from various
    regional networks to ensure station coverage for every major island in
    the LAA from Saba in the north to Grenada in the south. RFs show the
    subsurface response of an incoming signal assuming horizontal layering,
    where phase conversions highlight discontinuities beneath a station. In
    most regions of the Earth, the Mohorovičić discontinuity (Moho) is
    seismically stronger than other crustal discontinuities. However, in the
    LAA we observe an unusually strong along-arc variation in depth of the
    strongest discontinuity, which is difficult to explain by variations in
    crustal thickness. Instead, these results suggest that in layered crust,
    especially where other discontinuities have a stronger seismic contrast
    than the Moho, H–k stacking results can be
    easily misinterpreted. To circumvent this problem, an inversion
    modelling approach is introduced to investigate the crustal structure in
    more detail by building a one-dimensional velocity–depth profile for
    each island. Using this method, it is possible to identify any
    mid-crustal discontinuity in addition to the Moho. Our results show a
    mid-crustal discontinuity at about 10–25 km depth along the arc, with
    slightly deeper values in the north (Montserrat to Saba). In general,
    the depth of the Moho shows the same pattern with values of around 25 km
    (Grenada) to 35 km in the north. The results suggest differences in
    magmatic H2O content and differentiation history of each island.

    Full details in the University publications repository