Cenozoic tectono-geomorphic evolution of Yabrai Mountain and the Badain Jaran Desert (NE Tibetan Plateau margin)

Abstract Cenozoic tectono-geomorphic growth processes of the Yabrai Fault (YBF) along Yabrai Mountain (YM) and their impacts on the landscape formation of Badain Jaran Desert (BJD) during the late Quaternary are still unsolved, and yet are crucial to exploring the tectonic evolution of the boundary between the northeastern Tibetan Plateau and southern Gobi Alxa block. This study addresses these issues using information extraction-based interpretations of multiple satellite images coupled with field observations. The 138 km-long NE-NEE striking YBF can be divided into 3 segments: southwestern, central, and northeastern segments all characterized by left-lateral faulting with normal faulting components. Apatite (U-Th)/He thermochronology and calcite (U-Th) dating integrated with regional tectonic evolution history provides new geochronological evidence for understanding the multi-stage evolution of the YM and YBF. (1) Before the late Cretaceous (135–72 Ma), the mountain experienced rapid cooling and uplift. (2) During the late Cretaceous to Eocene (ca. 70–33.9), the YM is likely to have experienced denudation and flattening. (3) From the Oligocene to early Pliocene (33.9–5 Ma), the YBF underwent ~47 km of left-lateral displacement that accommodated the slip of Altyn Tagh Fault (ATF). (4) Since the Pliocene (5 ± 1 Ma), the YBF is characterized by left-lateral strike-slip faulting with a normal faulting component. The normal faulting resulted in uplift and the creation of topography along the central segment of the YBF. This has impeded the southeastward migration of sand dunes, building the world's highest megadune within the BJD. The tectono-geomorphic growth of the YM and YBF plays a key role in formation of the unique megadune-lake pattern and in preventing the merging of the BJD and Tengger Desert (TD).