Astronomically forced climate evolution in the North China Plain since the Late Pliocene

Abstract

Under the background of global warming, the impact of climate change in the densely populated North China Plain is becoming increasingly prominent. Cenozoic deposits in this area can provide insights into the evolution of the monsoon and the associated climate changes. This study focused on the SYZK01 borehole in the Beijing Plain area, primarily consisting of fluvial-lacustrine sediments. By employing detailed magnetic stratigraphy and multi-dating methods, we determined the age of the deposits to be approximately 0–3.3 Ma. Grain size and spontaneous potential logging were selected as proxies for paleoclimate. Our results reveal a strong coupling between the 0.063–0.25 mm grain size component, spontaneous potential logging and deep-sea δ18O in the overall sediment, confirming that glacial-interglacial cycles are the most significant form of climate change affecting the sedimentation process in the North China Plain. We observed a dominant 100 kyr eccentricity cycle within the 0.063–0.25 mm grain size component through the spectral analysis of the time-domain series of grain size indicators. In comparison, the 41 kyr cycle exhibited significant influence only from 1.1 to 0.6 million years ago. Notably, our study highlights that the SYZK01 borehole records the “late Pliocene-early Pleistocene 100 kyr problem,” characterized by phase and amplitude variations that do not align with Earth's orbital eccentricity.