England, P., 1993. Convective removal of thermal boundary layer of thickened continental lithosphere: a brief summary of causes and consequences with special reference to the Cenozoic tectonics of the Tibetan Plateau and surrounding regions. In: M.J.R. Wortel, U. Hansen and R. Sabadini (Editors), Relationships between Mantle Processes and Geological Processes at or near the Earth's Surface. Tectonophysics, 223: 67-73. The tectonics of Tibet and its surroundings underwent marked changes at about 8 Ma. Normal faulting of the plateau appears to have initiated at about this time. Widespread highly potassic volcanism, interpreted as the result of rapid heating of the mechanical boundary layer, began about 12-8 Ma. Such rapid heating could be the consequence of convective removal of the lower lithosphere and its replacement by asthenosphere. This process would have raised the surface height of the plateau and could have provided the driving force for extension. The diffuse deformation in the Indian Ocean probably began at about 8 Ma; analysis of the buckling of a plastic lithosphere implies that the horizontal force per unit length required to drive this deformation is consistent with uplift of the Tibetan plateau by 1-3 km. The Indian monsoon intensified at about 8 Ma. This intensification is consistent with the rapid passage of the surface height of the plateau across a threshold required to disrupt the pre-existing atmospheric circulation of the region. Taken together, these observations imply that the surface height of the Tibetan plateau rose by between 1 and 3 km in a few million years around 8 Ma. Such a rapid increase in surface height affecting an area the size of the Tibetan plateau could not be achieved by crustal thickness changes, but could have been caused by the convective removal of a substantial thickness of lower continental lithosphere of the region. © 1993.
