Chemical weathering of the loess deposits in the lower Changjiang Valley, China, and paleoclimatic implications

Loess deposits (Xiashu Loess) are widely distributed in the lower Changjiang Valley, East China, and are considered to be of eolian origin with a similar provenance to the well-documented loess of north-central China. The Xiashu Loess is characterized by strong dissolution of carbonate, and considerable weathering of some silicate minerals, especially plagioclase. Chemical mobility of Ca > Sr > Na > Mg was observed in the Xiashu Loess sediments, whilst most transition metals are relatively enriched. Chemical index of variation (CIA) and element ratios of K/Na and K/Ca record several paleoclimate events in the lower Changjiang Valley during the mid-late Quaternary, corresponding with isotopic records in deep-sea sediments. East China might be governed by stronger summer monsoons than north-central China during interglacial periods of the mid-late Quaternary, which may somewhat obscure the record of winter monsoons during glacial periods. (C) 2003 Elsevier Ltd and INQUA. All rights reserved.