Abstract:

Badain Jaran Desert has a rare group of megadunes in the world; the audiomagnetelluric(AMT) method was used to study the structure of megadunes in Badain Jaran desert. The audiomagnetelluric data was processed by nonlinear conjugate gradients method, and the resistivity sections of megadunes were obtained. There is a apparent lowresistivity zone existing in the deep of the section, and a certain scale highresistivity zone in the central of the megadunes. It is inferred that the formation of megadunes is related to the stabilized northwest wind, continuous groundwater replenishment and the special environment. The groundwater rises through transpiration and is obstructed by calcareous layers in the ancient sand dunes, then is evaporated from the bottom of the leeward slope; the water vapor is condensed on the surface of sands which roll down from the top of dunes, enhancing the ability to resisting wind erosion of sands, thus the sand dunes get larger and larger as time goes by, turning to megadunes.

Key words: audiomagnetelluric method, megadune, structure and formation, Badain Jaran Desert