摘要: According to a large volume of data, a rapid crustal uplift began in the Oligocene over about one half of the continental areas after a period of relative stability, -150 Ma long. This Neotectonic uplift has produced most of the p... 展开 According to a large volume of data, a rapid crustal uplift began in the Oligocene over about one half of the continental areas after a period of relative stability, -150 Ma long. This Neotectonic uplift has produced most of the present high topographic features, e.g., the South African plateau and many mountain ranges in the Alpine belt and Central and North-eastern Asia. A wide occurrence of shallow-water fossils indicates, that the Tien Shan and Caucasus were below sea level 40 Ma and 10 Ma ago, respectively. A strong acceleration of the uplift took place during the last 3-5 Ma. 1.6 Ma ago the Tien Shan was at half the present-day elevation. Most of the Neotectonic uplift took place on Precambrian, Paleozoic and Mesozoic crust and occurred far from active plate boundaries, without significant horizontal deformation and disturbance of isostasy. High gradients of the uplift are observed in many areas. Under such circumstances, the uplift should be caused by a density decrease in the lithosphere. Geophysical data show that in some regions the Neotectonic uplift was associated with recent asthenospheric upwelling which resulted from a partial or complete erosion of mantle lithosphere. This collapse of mantle lithosphere occurred without significant horizontal deformations. It could probably be associated with infiltration of volatiles into this layer from a fluid-containing anomalous mantle which ascended from a deep mantle in some places and rapidly spread into the other areas along the base of the lithosphere. Asthenospheric upwelling can ensure up to 1.5-2.5 km of the uplift. Delamination of dense eclogite from the crust or transformation of garnet granulites in the lower crust into a less dense gabbro under a contact with the asthenosphere can increase the magnitude of the uplift up to 3-4 km. 收起