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This is a report of multi-parameter mineral magnetic results of the Sanmenxia loess-pa-leosol couplets in the SE extremity of the Chinese Loess Plateau (CLP) over the interval of L1- L13 spanning the last 1 Ma. These results show that mass-specific magnetic susceptibility (X), XARM and SIRM and their ratios exhibit parallel stratigraphic variations. Since superparamagnetic (SP) particles have significant contribution to X but no contribution to remanence, e.g., ARM and SIRM, the strong linear correlations between X and remanence (e.g., ARM and SIRM) suggest that the pedogenesis-produced magnetic grains are predominantly in small single domain range. Consequently, the significant contribution of SP particles to the bulk X as supposed in previous studies has been obviously overestimated. XARM/X data in Sanmenxia and median grain size records of typical loess sections from the hinterland of the CLP display a strong resemblance, implying that XARM/X may be regarded as a reliable indicator for monitoring the variations of ferrimagnetic grain sizes. The results of S-ratio and HIRM ((SIRM+IRM-0.3T)/2) measurements indicate that there is significant enhancement of both soft magnetite/maghemite and hard hematite/goethite in paleosols associated with pedogenesis.
This is a report of multi-parameter mineral magnetic results of the Sanmenxia loess-pa-leosol couplets in the SE extremity of the Chinese Loess Plateau (CLP) over the interval of L1- L13 spanning the last 1 Ma. These results show that mass -specific magnetic susceptibility (X), XARM and SIRM and their ratios exhibit parallel stratigraphic variations. Since superparamagnetic (SP) particles have significant contributions to X but no contributions to remanence, eg, ARM and SIRM, the strong linear correlations between X and remanence (eg, ARM and SIRM) suggest that the pedogenesis-produced magnetic grains are predominantly in a small single domain range. Thus, the significant contribution of SP particles to the bulk X as supposed in previous studies has been obviously overestimated. XARM / X data in Sanmenxia and median grain size records of typical loess sections from the hinterland of the CLP display a strong resemblance, implying that XARM / X may be regarded as a reliable indicator for monitoring the variations of ferrimagnetic grain sizes. The results of S-ratio and HIRM ((SIRM + IRM-0.3T) / 2) measurements indicate that there is significant enhancement of both soft magnetite / maghemite and hard hematite / goethite in paleosols associated with pedogenesis.