Mongolian summits: An uplifted, flat, old but still preserved erosion surface

In Gobi Altay and Allay, Mongolia, several flat surfaces, worn through basement rocks and uplifted during the ongoing tectonic episode to a similar altitude of 4000 m, suggests disruption of a single large-scale surface. New thermochronology and field data show that the plateau surfaces represent uplifted parts of an ancient peneplain that formed during Jurassic time. The Gobi Altay and Allay flat-topped massifs are tectonically and geomorphologically unique. Their preservation for similar to 150 m.y. implies that no further tectonic movements occurred before the onset of the last deformation episode, 5 +/- 3 m.y. ago. It also suggests that very low erosion rates were maintained by a dry climate over millions of years.