Coordinated and Competitive Formation of Soil Magnetic Particles Driven by Contrary Climate Development

Abstract

Abstract Ferrimagnetic (FM) and antiferromagnetic (AFM) iron oxide particles are considered pedogenic and climatic indicators due to their enrichment with comparable increasing in rainfall and temperature. However, the opposite changes in rainfall and temperature result in rapid change of relative humidity (RH), which could lead to their competition and transformation. We examined two soil sequences which have undergone contrary climate development on the eastern edge of the Tibetan Plateau. Dry and warm climate with low RH favors the coordinative enrichment of AFM hematite and FM particles, while wet and cool climate with high RH mainly produces goethite but leads to competition between low content AFM hematite and FM particles. The outcome well interprets the changing relationship between color and magnetism in soils and sediments, and suggests that temperature is as important as precipitation in paleoclimate reconstruction based on iron oxides, especially during strong dry‐wet cycles and climate pattern shifts.

Keywords

• magnetism
• color
• iron oxides
• relative humidity
• paleoclimate reconstruction