Contribution
Kinematics of Tibet
Ratschbacher, Lothar
Zeitschrift der Deutschen Geologischen Gesellschaft Band 147 Heft 3 (1996), p. 427 - 434
12 références bibliographiques
publié: Nov 7, 1996
DOI: 10.1127/zdgg/147/1996/427
ArtNo. ESP171014703002, Prix: 15.00 €
Abstract
Tibet is mysterious: when you walk around Mount Kailas (in the Transhimalayas), the holiest mountain on earth, you save one rebirth on the way to the Nirvana - but do it clockwise (the Buddist way)! Tibet is remote: more western scientists have visited Antarctica than parts of the high plateau. It's huge, ~ 3500 x 1500 km across, high, ~ 5 km in average elevation, and remarkably flat, the relief is ≤ 1 km for Tibet as opposed to ≤ 6 km at the plateau edges. Although it has attracted people like invaders and scientists, the Tibetan plateau is actually important to many of us. For example, it has influenced climate by affecting atmospheric circulation over the entire northern hemisphere. Because of its high altitude and lateral extent, it provides a heat source opposing classical Hadley circulation and drives the circulation characteristic of summer monsoon. Even human evolution may have been influenced by the surface uplift of the Tibetan plateau and the accompanying contribution to regional climate change at ~ 8 Ma ago. And, it may help us understand how mountains are built, as mountain building and plateau forming processes are in full action in Central Asia (see Figure 1 for a geographic and tectonic overview) and, in several aspects, may be unique for the last 600 Ma. Since the 60's, the time of the earth-science revolution leading to the theory of plate tectonics, we believe that we have an idea how the earth works. In this theory, oceanic lithosphere is created from the underlying asthenosphere along narrow and long ridges and is recycled at deep-sea trenches, which again are narrow and long zones of vigorous tectonic activity, best manifested by earthquakes. In this model, huge (up to several 1000 km across) and rigid oceanic plates oppose narrow (usually a few km wide) plate boundaries. Continents, buoyant and old, passively drift with the oceanic lithosphere and ultimately collide with each other, forming mountain belts and forcing a re-organization of the creation-recycling structures by refusing to go down into the mantle.
Mots-clefs
Review • kinematics • crustal thickening • plate collision • crustal shortening • strike-slip faults • thrusting • rotation • uplift • Tertiary • neotectonics • Himalaya • Tibet