Nearly half way to Earth's center, the boundary between the solid silicate rock mantle and the liquid iron‐alloy outer core was long thought to be a sharp discontinuity between the two vastly different regimes. Recently, detailed seismological analyses have depicted the core‐mantle boundary (CMB) as being far from simple, and in fact shows evidence for an additional thin veneer of anomalous properties in certain geographical regions. Imaged as thin as a couple of km, and up to 50‐km thick, these unique zones are characterized by strong reductions in the speeds of seismic waves relative to the overlying mantle. These areas have thus been dubbed “ultra‐low velocity zones” (ULVZs).
Seismic probes
Seismology remains the most direct remote sensing tool for deciphering the subtleties of Earth's inaccessible deep interior. This is most commonly accomplished through the use of elastic energy that propagates away from earthquakes, traveling through the entire interior of the planet; some energy...
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Buffett, B.A., Garnero, E.J., and Jeanloz, R., 2000. Sediments at the top of the Earth's core. Science, 290: 1338–1342.
Garnero, E.J., and Jeanloz, R., 2000. Earth's enigmatic interface. Science, 289: 70–71.
Garnero, E.J., and Vidale, J., 1999. ScP; a probe of ultralow‐velocity zones at the base of the mantle. Geophysical Research Letters, 26: 377–380.
Garnero, E.J., Revenaugh, J.S., Williams, Q., Lay, T., and Kellogg, L.H., 1998. Ultralow velocity zone at the core‐mantle boundary. In Gurnis, M., Wysession, M., Knittle, E., and Buffet, B. (eds.) The Core‐Mantle Boundary. Washington, DC: American Geophysical Union, pp. 319–334.
Grand, S.P., 2002. Mantle shear‐wave tomography and the fate of subducted slabs. Philosophical Transactions of the Royal Society of London A, 360: 2475–2491.
Helmberger, D.V., Wen, L., and Ding, X., 1998. Seismic evidence that the source of the Iceland hotspot lies at the core‐mantle boundary. Nature, 396: 251–255.
Knittle, E., and Jeanloz, R., 1989. Simulating the core‐mantle boundary: an experimental study of high‐pressure reactions between silicates and liquid iron. Geophysical Research Letters, 16: 609–612.
McNamara, A.K., van Keken, P.E., and Karato, S.I., 2002. Development of anisotropic structure in the Earth's lower mantle by solid‐state convection. Nature, 416: 310–314.
Rost, S., and Revenaugh, J., 2001. Seismic detection of rigid zones at the top of the core. Science, 294: 1911–1914.
Tan, E., Gurnis, M., and Han, L., 2002. Slabs in the lower mantle and their modulation of plume formation. Geochemistry, Geophysics, Geosystems, 3(11): 1067 (doi: 10.1029/2001GC000238).
Thorne, M.S., and Garnero, E.J., 2004. Inferences on ultralow‐velocity zone structure from a global analysis of SPdKS waves. Journal of Geophysical Research, 109: B08301 (doi: 10.1029/2004JB003010).
Wen, L., and Helmberger, D.V., 1998. Ultra‐low velocity zones near the core‐mantle boundary from broadband PKP precursors. Science, 279: 1701–1703.
Williams, Q., Revenaugh, J.S., and Garnero, E.J., 1998. A correlation between ultra‐low basal velocities in the mantle and hot spots. Science, 281: 546–549.
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Garnero, E., Thorne, M. (2007). Ulvz, Ultra‐Low Velocity Zone. In: Gubbins, D., Herrero-Bervera, E. (eds) Encyclopedia of Geomagnetism and Paleomagnetism. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-4423-6_309
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