Structure of the Thermal Lithosphere and Asthenosphere
beneath Oceans and Continents

L. E. Levin

Russian State Geological Prospecting University, Miklukho-Maklaya ul. 23, Moscow, 117997 Russia

e-mail: leo.levine@rambler.ru

Received September 21, 2005

Abstract—The lithosphere and asthenosphere make up a common geodynamic system but are characterized
by different physical parameters. The former has a temperature of 1200-1300°C, a density of 3.3 g/cm³, and a
viscosity of 10²² poise, while the latter has a density of 3.23 g/cm³, a viscosity in the range 10²¹–10¹⁸¹⁹ poise,
and a temperature from 1200–1300°C to 1600-1700°C. The asthenosphere is distinguished by a great variabil-
ity of its physical state in the lateral and vertical directions. This circumstance necessitates the recognition of
the different types of the asthenosphere: seismic (LVZ zone), electrical, thermal, and seismological. The struc-
ture and the physical state of the thermal asthenosphere is considered in this paper on the basis of param-
eters. Its state normally fits viscous Newtonian liquid beneath the continents and provides partial (5–20%) melt-
ing in spreading zones and along continental margins. No partial melting is detected beneath the main portion
of the continents. The interaction between the asthenosphere and lithosphere is characterized by spatiotemporal
migration of partial melting zones and asthenosphere upwelling, and such interaction determines the entire
range of geodynamic processes from spreading and rifting to collision and vertical motions of different senses.

DOI: 10.1134/S0016852106050037

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