The Turfan Depression of the Western Turfan Basin, Northwest China: Aspects of Subsidence and Relation to Lateral Escape Tectonics

Abstract

During the Oligocene, lateral escape tectonics caused by India's collision with Eurasia started to affect the western part of the Turfan basin, and the Turfan depression was initiated. The depression's subsidence can be explained within the context of lateral escape tectonics. Of interest is that contractional as well as synchronous dilatational tectonics combined to lower the land surface below mean sea level. In the course of lateral escape, transpressional loading from the north and ESE-directed escape of the western part of the Turfan basin took place and continue today (Cunningham et al., 1996). In the western part of the Turfan basin, ongoing extension is a result of relative differences in lateral escape velocities–relatively “slow” escape in the north as a result of restraining bends, and relatively “fast” escape in the south. The northern margin of the Turfan depression is affected by contractional deformation, but at the same time the depression also is located in a domain of extensional faulting. Strike-slip tectonics play a key role in the formation of the Earth's deep depressions, which occur along transtensile segments of important lateral shear zones. In the case of the Turfan depression, this is not exactly true. However, strike-slip motion along the boundaries of the Turfan basin are the controlling factors for the formation of the Turfan depression.