Environmental magnetism and paleoclimatic interpretation of the Sanmenxia loess-paleosol sequence in

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This is a report of multi-parameter mineral magnetic results of the Sanmenxia loess-paleosol couplets in the SE extremity of the Chinese Loess Plateau (CLP) over the interval of L1-L13spanning the last 1 Ma. These results show that mass-specific magnetic susceptibility (χ), χARM and SIRM and their ratios exhibit parallel stratigraphic variations. Since superparamagnetic (SP) particles have significant contribution to χ but no contribution to remanence, e.g., ARM and SIRM, the strong linear correlations between χ 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 χ as supposed in previous studies has been obviously overestimated.χARM/χ data in Sanmenxia and median grain size records of typical loess sections from the hinterland of the CLP display a strong resemblance, implying that χARM/χ may be regarded as a reliable indicator for monitoring the variations of ferrimagnetic grain sizes.The results of S-ratio and HIRM ((SIRM+IRM-o.3T)/2)measurements indicate that there is significant enhancement of both soft magnetite/maghemite and hard hematite/goethite in paleosols associated with pedogenesis.
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