The Role of Monsoon in the Long-Term Topographic Evolution of East Asia (north China)

The East Asian monsoon impacts the livelihood of billions of people and also influences global climate change, yet its evolution is associated with considerable controversy. The topographic reconstruction of the LuliangTaihang region can provide a valuable topographic record of the East Asian monsoon development. In this study, we employed apatite and zircon (U-Th)/He data to reconstruct the two-dimensional (2-D) paleotopography of the Fangshan-Xiyang horizontal transect and the one-dimensional exhumation evolution of seven vertical profiles in the Luliang-Taihang region. The west segment of the 2-D transect reached a peak elevation of -3.7 km at -80 Ma. The 2-D results revealed that the watershed moved in 80 Ma. Furthermore, a rapid decrease in elevation (and relief) of the topography occurred during the Late Cretaceous in the west segment of the 2-D transect. This was attributed to the Huyanshan Fault activity, which may be related to the collision between the Okhotomorsk Block and East Asia in the Late Cretaceous. There was also a significant elevation reduction and exhumation acceleration for the east segment of the 2-D transect during the Late Oligocene-Middle Miocene, which is probably related to the effects of the East Asian monsoon. The result implies that the Luliang-Taihang region may have played an important role in blocking humid and warm Pacific air into the interior of East Asia after the East Asian monsoon expanded northwards into North China.