CONTINENTAL LITHOSPHERE FOLDING IN CENTRAL-ASIA .1. CONSTRAINTS FROM GEOLOGICAL OBSERVATIONS

Geological observations support the occurrence of long-wavelength surface undulations in Central Asia, which can be treated in terms of folding of the whole lithospheric plate. The characteristic wavelength of the whole lithosphere folding is 360 km in the western part of the Gobi sub-plate. Superimposed on the long wavelength deformation, two shorter wavelength scales of spatially periodical deformation are also observed. An intermediate wavelength of 30-50 km of the intraplate deformation reflects the response of the mechanically strong upper-crustal part of the Central Asian lithosphere. Small wavelength (4-9 km) deformation corresponds to faulting in the uppermost crustal layer and folding and faulting in the sedimentary cover. Folding of the lithosphere controls the location and geometry of compressional basin formation in the western part of the Gobi sub-plate. A number of folding and faulting characteristics of continental intraplate deformation in Central Asia presented in this study are strikingly similar to observed styles of intraplate deformation in oceanic lithosphere in the northeastern Indian Ocean.