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ARS Home » Southeast Area » Booneville, Arkansas » Dale Bumpers Small Farms Research Center » Research » Publications at this Location » Publication #338486

Title: Geochemical characterization of the loess-paleosol sequence in northeast China

item SUN, ZHONG-XIU - Shenyang Agricultural University
item JIANG, YING-YING - Shenyang Agricultural University
item WANG, QUI-BING - Shenyang Agricultural University
item Owens, Phillip

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2018
Publication Date: 2/20/2018
Citation: Sun, Z., Jiang, Y., Wang, Q., Owens, P.R. 2018. Geochemical characterization of the loess-paleosol sequence in northeast China. Geoderma. 321:127-140.

Interpretive Summary: This article describes the methodology to examine soil that was developed in geologically older materials to determine weathering intensity. Novel techniques were used that focused on minor stable trace elements as a proxy to determine gains and losses within the silty geologic section in China. The results of the research found that there were 4 different periods of high weathering intensity over the last 423,00 years that likely corresponded to warmer and wetter climates. This research will help scientists understand the rate of soil formation and the potential linkages between changes in temperature and rainfall.

Technical Abstract: The long-term weathering evolution of northeastern China is not well known due to few well-preserved terrestrial paleo-environmental archives in this area. The Chaoyang section is a well-preserved loess-paleosol sequence located in northeast China, with continuous deposition since 423 ka BP; therefore, the deposit represents an archive of climate change for this region. In this section, forty-two loess and paleosol samples of Chaoyang section were geochemically characterized by major elemental compositions, elemental ratios, the ternary diagram of Al2O3-(CaO*+Na2O)-K2O, the improved quantitative reconstruction and elemental distributions with respect to the average upper continental crust (AUCC). The geochemical features of Lingtai section are used for the comparison loess-paleosol section. The similar AUCC-normalized major elemental distributions and high correlation of the major elemental compositions between loess-paleosol samples in Chaoyang section and Lingtai section indicates that they may originate predominantly from a similar loess source. Based on the variability of chemical indices corresponding consistently to soil magnetic susceptibility (SUS) and field observations, the loess-paleosol formation period of 423-77 ka BP has been separated into eight sub-periods including four periods with higher chemical weathering intensity (paleosol) and four periods characterized by the relative lower chemical weathering intensity (loess). Relatively intense desilication and fersiallitization primarily occurred in the Chaoyang section with greater losses of SiO2 (3.54% in average) and gains of Fe2O3 (0.77%) and Al2O3 (0.33%). Such processes also are reflected in an increase in the amount of K2O (0.41%). Ca and Na leaching were still predominant in the Lingtai section with greater losses of CaO (28.03%) and Na2O (14.03%). The Chaoyang section has recorded the chemical weathering history during 423-77 ka BP, which is comparable to the weathering cycles in the Lingtai section.