DYNAMICS OF PLATE INTERIORS
Geodynamics Series, Vol. 1
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DYNAMICS OF PLATE INTERIORS, GEODYNAMICS SERIES, VOL. 1, PAGES 37–51, 1980

The origin of vertical crustal movements within lithospheric plates

E. V. Artyushkov

Institute of Physics of the Earth, Moscow

A. E. Shlesinger

Geological Institute of the USSR Academy of Sciences, Moscow

A. L. Yanshin

Institute of Geology and Geophysics of the Siberian Branch of the USSR Academy of Sciences


Abstract

At the core-mantle boundary the authors postulate a phase transformation from solid state into a liquid and denser state with the acquisition of metallic properties. This process leads to the formation of unmolten differentiates that are lighter than the lower mantle. Light lower mantle material is released with a periodicity of about 200 Ma and rises through channels (about 100 km in diameter) that heat the surrounding mantle and facilitate further passage of additional light lower mantle material. Such material then emerges in the upper mantle, differentiates further, and spreads below the lithosphere or even below the earth's crust. Thickness variations in the lithosphere lead to the formation of “;traps”; that preferentially catch the light material where the lithosphere is thin and the formation of “;antitraps”; where the lithosphere is thick. As such traps are located at the base of the moving plates of the earth, they would catch light material whenever they can get it from a deep channel rising from the lower mantle. The trapping of hot light material leads to the formation of broad uplift areas of minor relief (shields) when only minor amounts of light material can be intercepted repeatedly from relatively distant channels. However, in tectonically more active areas where larger traps are located near the ascent channels, the upper mantle is heated further and leads to broad uplift zones such as the western U.S. or the Baikal area. Low-lying shield areas may also be reactivated by vigorous new entrapment of light mantle material as in the Tien Shan Mountains.

Sedimentary basins are formed by any combination of three processes: (1) mantle consolidation in the area of a former trap, (2) conversion by phase transition of the lower part of the basaltic layer of the crust into eclogite, or (3) transition of a part of the overlying basalt into garnet granulite.

Large masses of heated light material supplied to the base of the lithosphere beneath the sedimentary basins on the platforms eventually displace colder upper mantle material to come into contact with the basaltic layer of the crust, there leading to a quick transition from basalt into garnet granulite and into eclogite. Such a history is reflected in the history of larger inland seas (e.g., south Caspian Basin) where an earlier platform sequence is separated by an unconformity suggesting uplift and followed by renewed and intensified subsidence.

Citation: Artyushkov, E. V., A. E. Shlesinger, and A. L. Yanshin, (1980), The origin of vertical crustal movements within lithospheric plates, in Dynamics of Plate Interiors, Geodyn. Ser., vol. 1, edited by A. W. Bally et al., pp. 37-51, AGU, Washington, D. C.