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Contrasting behavior of hematite and goethite within paleosol S5 of the Luochuan profile, Chinese Loess Plateau
Author(s) -
Liu Qingsong,
Bloemendal Jan,
Torrent Jose,
Deng Chenglong
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl027172
Subject(s) - hematite , paleosol , goethite , geology , loess , rock magnetism , mineralogy , loess plateau , environmental magnetism , paleoclimatology , plateau (mathematics) , remanence , geochemistry , magnetite , soil science , geomorphology , paleontology , chemistry , magnetization , climate change , magnetic field , mathematics , mathematical analysis , oceanography , adsorption , quantum mechanics , physics , organic chemistry
The Chinese loess/paleosol sequence provides an excellent record of long‐term variations in the East Asian paleomonsoon. For representative loess profiles, paleosol units have enhanced magnetic properties compared to loess units. However, at some depth intervals with special paleoenvironmental conditions, selective depletion of antiferromagnetic (AFM) minerals (hematite and goethite) could occur, resulting in complexities in accurately linking variations in magnetic properties to long‐term fluctuations in paleoclimate. To resolve this problem, we directly measured the mass concentrations of these AFM minerals using second‐order diffuse reflectance spectroscopy (DRS), and then correlated the DRS results to high‐field isothermal remanent magnetization (HIRM) from paleosol unit S5 at the Luochuan profile, central Chinese Loess Plateau. Our results suggest that a low HIRM anomaly just below the sub‐paleosol unit S5S1 is caused by fluctuations specifically in goethite content, while the hematite concentration exhibits a maximum over the same depth interval. This appears to rule out significant loss of hematite to reductive dissolution and further indicates that hematite and goethite may respond differently to changes in the paleoclimate conditions.