Mantle convection

Simplified model of mantle convection:[1] Whole-mantle convection

Mantle convection is the very slow creep of Earth's solid silicate mantle as convection currents carry heat from the interior to the planet's surface.[2][3] Mantle convection causes tectonic plates to move around the Earth's surface.[4]

The Earth's lithosphere rides atop the asthenosphere, and the two form the components of the upper mantle. The lithosphere is divided into tectonic plates that are continuously being created or consumed at plate boundaries. Accretion occurs as mantle is added to the growing edges of a plate, associated with seafloor spreading. Upwelling beneath the spreading centers is a shallow, rising component of mantle convection and in most cases not directly linked to the global mantle upwelling. The hot material added at spreading centers cools down by conduction and convection of heat as it moves away from the spreading centers. At the consumption edges of the plate, the material has thermally contracted to become dense, and it sinks under its own weight in the process of subduction usually at an oceanic trench. Subduction is the descending component of mantle convection.[5]

This subducted material sinks through the Earth's interior. Some subducted material appears to reach the lower mantle,[6] while in other regions this material is impeded from sinking further, possibly due to a phase transition from spinel to silicate perovskite and magnesiowustite, an endothermic reaction.[7]

The subducted oceanic crust triggers volcanism, although the basic mechanisms are varied. Volcanism may occur due to processes that add buoyancy to partially melted mantle, which would cause upward flow of the partial melt as it decreases in density. Secondary convection may cause surface volcanism as a consequence of intraplate extension[8] and mantle plumes.[9] In 1993 it was suggested that inhomogeneities in D" layer have some impact on mantle convection.[10]

  1. ^ Carlo Doglioni, Giuliano Panza: Polarized Plate Tectonics. Advances in Geophysics, Volume 56, 2015.
  2. ^ Kobes, Randy. "Mantle Convection". Archived from the original on 9 June 2011. Retrieved 26 February 2020. Physics Department, University of Winnipeg
  3. ^ Ricard, Y. (2009). "2. Physics of Mantle Convection". In David Bercovici and Gerald Schubert (ed.). Treatise on Geophysics: Mantle Dynamics. Vol. 7. Elsevier Science. ISBN 9780444535801.
  4. ^ Moresi, Louis; Solomatov, Viatcheslav (1998). "Mantle convection with a brittle lithosphere: thoughts on the global tectonic styles of the Earth and Venus". Geophysical Journal International. 133 (3): 669–82. Bibcode:1998GeoJI.133..669M. CiteSeerX 10.1.1.30.5989. doi:10.1046/j.1365-246X.1998.00521.x.
  5. ^ Gerald Schubert; Donald Lawson Turcotte; Peter Olson (2001). "Chapter 2: Plate tectonics". Mantle convection in the earth and planets. Cambridge University Press. pp. 16 ff. ISBN 978-0-521-79836-5.
  6. ^ Fukao, Yoshio; Obayashi, Masayuki; Nakakuki, Tomoeki; Group, the Deep Slab Project (2009-01-01). "Stagnant Slab: A Review" (PDF). Annual Review of Earth and Planetary Sciences. 37 (1): 19–46. Bibcode:2009AREPS..37...19F. doi:10.1146/annurev.earth.36.031207.124224. {{cite journal}}: |last4= has generic name (help)
  7. ^ Gerald Schubert; Donald Lawson Turcotte; Peter Olson (2001). "§2.5.3: Fate of descending slabs". Cited work. Cambridge University Press. pp. 35 ff. ISBN 978-0-521-79836-5.
  8. ^ Foulger, G.R. (2010). Plates vs. Plumes: A Geological Controversy. Wiley-Blackwell. ISBN 978-1-4051-6148-0.
  9. ^ Kent C. Condie (1997). Plate tectonics and crustal evolution (4th ed.). Butterworth-Heinemann. p. 5. ISBN 978-0-7506-3386-4.
  10. ^ Czechowski L. (1993) Geodesy and Physics of the Earth pp 392–395, The Origin of Hotspots and The D" Layer