Rifting of Africa and pattern of mantle convection beneath the African plate

Abstract

Pavoni, N., 1992. Rifting of Africa and pattern of mantle convection beneath the African plate. In: P.A. Ziegler (Editor), Geodynamics of Rifting, Volume III. Thematic Discussions. Tectonophysics,215: 35-53.The Mesozoic and Cenozoic tectonic setting of the African continent is characterized by an extensional stress regime, as is evident ffom the evolution of the West, Central and East African rift systems, the opening of the Indian and Atlantic oceans and the development of Tethys domain, as well as from the results of geophysical investigations.

Geology and geomorphology of the Urema Graben with emphasis on the evolution of Lake Urema

“…Different models exist with regard to the evolution of the EARS: (1) emphasizing active rifting associated with one or several mantel plumes with lateral tensions and fracturing and (2) defending passive rifting with localized thinning of crust and pressure-released melting. The conclusion might be a combination of both, active and passive rifting influenced by lithospheric regional patterns of tensions, stress propagation through rigid cratons and convection in the asthenosphere (Logatchev et al, 1972;Ebinger, 1989;Pavoni, 1992;Nyblade and Brazier, 2002). The UG is part of the western branch of EARS.…”

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“…Geological observations, such as an alternation of long transform faults with relative short ridge segments along active oceanic ridges (observed in the central Mid-Atlantic Ridge region), the existence of ridge-ridgeridge triple junctions, or the occurrence of lateral migration or jumping of ridge axes argue against active upwelling and diverging flow in the mantle below the ridge, and against symmetrically diverging plate movement at one-half spreading rate, away from the ridge axis [Pavoni, 1969[Pavoni, , 1992.…”

“…[Pavoni, 1969]. (d) Symmetric accretion caused by neighboring plates moving in the same direction at different velocities [Pavoni, 1992] In a recent analysis of multichannel seismic, magnetic, and gravity data, Lafoy et al [2005] distinguished a northern NW-SE trending, thinned continental segment of the basin from a southern N-S trending segment of oceanic origin.…”

[Comment on “Tree tectonics” by Peter R. Vogt] Seafloor spreading: Symmetric accretion does not mean symmetrically diverging movement of adjacent plates

“…Geological observations, such as an alterna tion of long transform faults with relative short ridge segments along active oceanic ridges (observed in the central Mid-Atlantic Ridge region), the existence of ridge-ridge-ridge triple junctions, or the occurrence of lateral migra tion or jumping of ridge axes argue against active upwelling and diverging flow in the mantle below the ridge, and against symmetri cally diverging plate movement at one-half spreading rate, away from the ridge axis [Pavoni, 1969[Pavoni, ,1992.…”