31. Glaciers, Lakes, and Fault Zone, Tibet Plateau

The Tibet Plateau is the largest and highest elevated region in the world, 1200 kilometers (750 miles) from east to west, 900 kilometers (550 miles) north to south, with a mean elevation of over 4000 meters (13,100 feet). Since the plateau rises above so much of the atmosphere, photographs are typically brilliantly crisp and clear. A plethora of geological features are visible in any frame. This picture shows the northwest corner of the plateau near the point where the ground falls away to the Tarim Basin. The impressive snow-capped mountain at top right with well-developed valley glaciers is Muztag Ulu (7282 meters, 23,845 feet). The plateau was elevated as a consequence of the collision between India and Asia, which resulted in extensive shortening by overthrusting and folding. A second important consequence of the collision was major strike-slip faulting, facilitating the tectonic “escape” of China like a squeezed melon seed. The linear valley with two lakes may be the site of a strike-slip fault. At the lower right corner, two light-toned outcrops are also apparently displaced some 30 kilometers (18 miles) by a left lateral fault.

The blue lake at center shows extensive terraces around its northern shores. During glacial times, lake levels on the plateau stood as much as 300 meters (900 feet) higher than at the present day. Since the end of the Ice Age, the climate has become increasingly arid, and lakes have shrunk. The bounding Himalayan and Kun Lun mountain ranges act as effective barriers to moisture-laden winds.

STS-41G, October 1984. Picture #17-31-043.

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