资源环境科技发展态势分析平台

Magnetic particles associated with iron (Fe) oxides are widespread on the surface of Earth and Mars and serve as reasonable climatic indicators. Ferrimagnetic maghemite (Mgh) and antiferromagnetic hematite (Hm), which dominate magnetism and redness, often coexist or compete with each other in soils and sediments. The formation efficiency of Mgh relative to Hm could be modulated by geochemical background besides climate, especially by phosphate (P), which has a high affinity for the surfaces of precursor iron oxides in natural systems. We investigated two Ferralsol sequences around a P mining field with similar climates and contrasting P/Fe ratios. High P/Fe ratios retard iron oxide crystallization, grain growth and transformation into Hm, thereby promoting more effective accumulation of ferrimagnetic Mgh as an intermediate product. The lack of ligand‐protected effects well interprets asynchronous changes in magnetism and redness in soils and sediments across large spatio‐temporal scales, especially in highly weathered soils.