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Tag: Mantle flow

Subduction seismic anisotropy

Illustration of constraints on subduction zone seismic anisotropy from a global compilation of shear-wave splitting measurements.

Illustration of constraints on subduction zone seismic anisotropy from shear-wave splitting measurements from the compilation presented in Long (2013). The subduction trenches compiled by Bird (2003) are shown in black. The anisotropic signals of the wedge (orange) and back-slab regions (blue) are shown separately. Blue arrows indicate average fast directions for the back-slab splitting signal from SKS (seismic waves traveling through the Outer Core), local S, and source-side tele-seismic S-splitting measurements (Long and Silver, 2009; Paczkowski, 2012). Orange arrows indicate average fast directions for wedge anisotropy from local S splitting (Long and Wirth, 2013). In regions where multiple fast directions are shown, splitting patterns exhibit a mix of trench-parallel, trench-perpendicular, and oblique fast directions.

  • Creator: Fabio Crameri
  • This version: 01.09.2021
  • License: Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
  • Specific citation: This graphic by Fabio Crameri after Crameri and Tackley (2014) and Long (2013) is available via the open-access s-Ink repository.
  • Related references:
    Crameri, F., and P.J. Tackley (2014), Spontaneous development of arcuate single-sided subduction in global 3-D mantle convection models with a free surface, J. Geophys. Res. Solid Earth, 119(7), 5921-5942, doi:10.1002/2014JB010939
    Long, M. D. (2013), Constraints on subduction geodynamics from seismic anisotropy, Rev. Geophys., 51, 76–112, doi:10.1002/rog.20008
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Mobile-lid mantle convection

Temporal evolution of a global, fully spherical, 3D model of whole-mantle convection.

Animation showing the temporal evolution of whole-mantle convection including plate tectonics. The convective turnover of the mantle is characterised by hot rising mantle plumes (indicated by a hot, red temperature isosurface), and cold and stiff subduction zones of heavy tectonic surface plates (indicated by grey viscosity isosurfaces). Like on the Earth, in this model the mantle convects including its surface thermal boundary layer, with subduction zones (i.e., the sinking of cold and heavy oceanic plates) being its main driver. The global, fully spherical, 3D mantle convection model has been run by the code StagYY and represents the actual dynamics in the Earth’s mantle under some assumptions and simplifications.

  • Creator: Fabio Crameri
  • This version: 07.08.2021
  • License: Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
  • Specific citation: This graphic by Fabio Crameri from Crameri and Tackley (2016) is available via the open-access s-ink.org repository.
  • Related reference: Crameri, F., and P. J. Tackley (2016), Subduction initiation from a stagnant lid and global overturn: new insights from numerical models with a free surface, Progress in Earth and Planetary Science, 3(1), 1–19, doi:10.1186/s40645-016-0103-8
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Mantle convection

Illustrative vertical cross-section showing the oceanic plate as part of whole-mantle convection.

The oceanic plate as part of whole-mantle convection. Illustrative vertical cross-section showing the oceanic plate sinking and destructing on its way down into the deep mantle, whereas hot mantle plumes next to large-low-shear-wave-velocity provinces (LLSVPs) form and rise back to the surface forming the process of mantle convection. Resisting whole mantle overturn are only the continental lithosphere, which is light and strong and therefore resists subduction, and the large-low shear-wave velocity provinces (LLSVP), which are chemically heavy features atop the core-mantle boundary. Somewhat passive features in mantle covection are the centre parts of the mantle (in some locations at around 1’000–2’200 km depth) around which the anomalously hot or cold material circles, sometimes called BEAMS, an abbreviation for “bridgmanite-enriched ancient mantle structures“. Thicknesses of individual layers and structures are not perfectly to scale.

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