Characteristics of the typical loess profile with a macroscopic tephra layer in the northeast China and the paleoclimatic significance

Abstract Tephra layers can serve as ideal datable horizons to provide invaluable datums for supplementing research on loess-paleosol sequences. The objective of this research was to evaluate a typical loess profile interbedded with a macroscopic tephra in northeastern China to better understand its formation to determine the potential impact of volcanism on climate change, as evidenced by loess pedogenesis. Geochemical and physical properties of the profile were determined and compared with loess materials from other areas to address its characteristics and potential significance for understanding climate variability. Results showed the tephra layers with overlying loess horizons were uniform in parent material, as inferred from evidence such as uniform Ti/Zr ratios with depth, similar rare earth element distribution patterns, and major elemental distributions with depth. The volcanic properties in the bottom of the profile, including morphology, high phosphate adsorption capacity (PAC) and pH (NaF) values, further supported the speculation that the depositions of aeolian dust and volcanic materials were synchronous with pedogenic processes. According to the comparison of magnetic susceptibility of the typical profile with the global δ18O curve, the local paleoclimate showed an increase in temperature in warmth and wetness, which may have been affected by volcanism. Research on the loess profile interbedded with a macroscopic tephra could improve our knowledge of loess formation and deepen our understanding of the impact of volcanism on climate changes.