Abstract
The problem of the determination of thermomechanical conditions in the upper mantle under a moving lithospheric plate at a given shear stress does not have a unique solution. Given a fixed heat flux from the lower mantle, two types of motion are possible in the mantle: subcritical (slower and colder) and supercritical (faster and hotter). In this work, it is shown that, if these modes are rather close to each other (in the near-critical state of the mantle), transitions from one mode to another and backward are possible. The calculated period of a change in the mantle state amounts to ∼0.3 Myr for the Pacific plate. The oscillatory regime of the mantle state can manifest itself in the activity pulsations of hotspots located near fast separating mid-ocean ridges.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
C. Froidevaux and G. Schubert, “Plate Motion and Structure of the Continental Asthenosphere: A Realistic Model of the Upper Mantle,” J. Geophys. Res. 80, 2553–2564 (1975).
C. Froidevaux, G. Schubert, and D. A. Yuen, “Oceanic Lithosphere and Asthenosphere: Thermal and Mechanical Structure,” J. Geophys. Res. 81, 3525–3540 (1976).
C. Froidevaux, G. Schubert, and D. A. Yuen, “Thermal and Mechanical Structure of the Upper Mantle,” Tectonophysics 37, 233–245 (1977).
S. V. Gavrilov, V. N. Zharkov, and T. V. Ruzmaikina, “Convective Instability of Real Upper Mantle Models,” Izv. Akad. Nauk SSSR, Fiz. Zemli, No. 12, 3–8, (1977).
S. V. Gavrilov and V. N. Zharkov, “Stability of a Thermomechanical Model of the Continental Upper Mantle,” Izv. Akad. Nauk SSSR, Fiz. Zemli, No. 12, 3–14 (1979).
S. V. Gavrilov, V. N. Zharkov, and T. V. Ruzmaikina, “On the Convective Instability of Real Models of the Upper Mantle and Shear Flows beneath the Continental Lithosphere,” Phys. Earth Planet. Inter. 22, 225–237 (1980).
S. V. Gavrilov and V. N. Zharkov, “Construction of a Thermomechanical Model of the Continental Upper Mantle,” Izv. Akad. Nauk SSSR, Fiz. Zemli, No. 4, 3–13 (1981).
G. Schubert and D. A. Yuen, “Asthenospheric Shear Flow: Thermally Stable Or Unstable?,” Geophys. Rev. Lett. 4, 503–516 (1977).
D. L. Turcotte and J. Schubert, Geodynamics: Applications of Continuum Physics in Geological Problems (Wiley, New York, 1982; Mir, Moscow, 1985).
V. N. Zharkov, Geophysical Studies of Planets and Their Satellites (OIFZ RAN, Moscow, 2003) [in Russian].
Author information
Authors and Affiliations
Additional information
Original Russian Text © S.V. Gavrilov, A.N. Boiko, 2008, published in Fizika Zemli, 2008, No. 1, pp. 44–49.
Rights and permissions
About this article
Cite this article
Gavrilov, S.V., Boiko, A.N. On stochastic near-critical oscillations in the upper mantle. Izv., Phys. Solid Earth 44, 38–42 (2008). https://doi.org/10.1134/S1069351308010059
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S1069351308010059