Paleosubarctic Eolian environments along the southern margin of the North American Icesheet and the southern margin of Siberia during the Last Glacial Maximum

Based on a negative correlation of magnetic susceptibility with organic matter content and the degree of gleying documented both in North American and southern Siberian eolian sequences, the authors propose that reducing conditions of incipient histosol development contributed to the alteration of magnetic minerals from strongly magnetic forms of oxidized iron to weakly magnetic forms. Therefore, the magnetic susceptibility is basically an indicator of redox cycles. Well-vegetated conditions generally dominated the later part of the Last Glacial Maximum (LGM; ∼15,000–∼8000 14C years BP) and poorly vegetated conditions the early part (∼21,000–∼15,000 14C years BP), with a rapid transition around 15,000 14C years BP chronologically corresponding to many well-documented rapid transitions around the world. The magnetic susceptibility signatures indicate approximately 1000-year-long cycles of environmental changes during the Last Glacial Maximum (∼21,000–10,000 14C years BP) in North America. The initial perturbation of these ∼1000-year-long cycles might have started in the Tropical Pacific and then been promptly transferred to the North Atlantic via the North American Icesheet. The southern Siberian eolian sequence recorded approximately 1400-year cycles. These ∼1400-year cycles might have been associated with the thermal variations in the Arctic Ocean that was directly linked with the thermal variations in the North Atlantic Ocean. To sum up, our research suggests that the North American eolian sequence recorded ∼1000-year cycles and the southern Siberian eolian sequence recorded ∼1400-year cycles, although it is not able to propose plausible mechanisms controlling the ∼1000- or/and ∼1400-year cycles.