Stratigraphic and paleomagnetic evidence of mid-Pleistocene rapid deformation and uplift of the NE Tibetan Plateau

Abstract

The NE Tibetan Plateau has become an important region for deciphering the Cenozoic uplift of the Plateau. Previous studies have verified that the Quaternary uplift in this region had a multi-stage character; however geologists have not established which event constituted the main tectonic phase. Fortunately, stratigraphic and paleomagnetic evidence from the Jiuquan Basin, Gansu Province, China, now confirm that the Laojunmiao Movement (represented as an angular unconformity) occurred between ∼ 0.9 and 0.8 Ma; and an almost synchronous tectonic event has been well recorded within and around the Plateau. Moreover, many proxies indicate that the global climate changed more rapidly after ∼ 0.9 Ma. These proxies include eolian loess and vermiculated red soils caused by the Asian monsoon, the eolian sedimentation rate, the Stilostomella extinction, changes in the global thermohaline circulation, and the increased δ 13C values recorded in the marine sediments. Based on the uplift-driven climate change, the mid-Pleistocene Transition (MPT) could be the result of the Laojunmiao Movement. Certainly, the Laojunmiao Movement and MPT had the significant impact on the Quaternary earth. We conclude that the Laojunmiao Movement was likely the main tectonic phase of the Quaternary Plateau uplift.