Geochemistry of magnetite and maghemite in soils in European Russia

• Published in: Geochemistry international Vol. 47; no. 3; pp. 297 - 310
• Main Authors: Vodyanitskii, Yu. N., Morgun, E. G., Obydenova, L. A., Rumyantseva, K. A., Chapygina, N. V.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.03.2009; Springer Nature B.V
• Subjects: Earth and Environmental Science; Earth Sciences; Geochemistry; Reagents; Soil treatment; Soils; Steppes; Studies; Trace elements; Russia; Magnetic Susceptibility; Humus Horizon; Magnetite; Geochemistry International; Maghemite
• ISSN: 0016-7029; 1556-1968
• DOI: 10.1134/S0016702909030070

A method is proposed for determining the proportions of soluble Fe oxides (magnetite, FeOFe 2 O 3 , and maghemite, γ-Fe 2 O 3 ) based on the measured magnetic susceptibility before and after treatment of soil with the Tamm or Mehra-Jackson (DCB) reagents. The development of hydromorphism in steppe soils in Ciscausiaia is associated with an increase in the magnetite fraction and, consequently, the average magnetite: maghemite ratio increases from 0.8–0.9 to 1.1. In these soils, smectites facilitate magnetite oxidation to maghemite. Soddy-podzolic and dark humic soils in the Cis-Ural region are noted for low values of the magnetite: maghemite ratio (0.5 on average) due to maghemite predominance. Soils in the Cis-Ural region on cover red-earth clays inherit lithogenic Fe oxides: hematite and maghemite. Hydromorphism in humid environments in northern taiga is accompanied by a significant increase in the magnetite: maghemite ratio to 4–9. Some issues of Fe geochemistry in magnetite and maghemite are considered.