Pedostratigraphy and Carbonate Accumulation in the Last Interglacial Pedocomplex of the Chinese Loess Plateau

Abstract

This paper examines the geographic variations of carbonate concentrations in last interglacial pedocomplex (S1) profiles along a northwest (NW)–southeast (SE) transect across the Chinese Loess Plateau. The average S1 carbonate concentration is the same as that of overlying loess (L1) and underlying loess (L2) at the northwesternmost site (Lanzhou), but variations in carbonate concentration within S1 pedocomplex are greater than the within‐loess (L1 and L2) variations, indicating that the carbonate translocation within the S1 pedocomplex had occurred. Carbonate was leached to greater depths to form more pronounced peaks in the three paleosols (S1S1, S1S2, S1S3) within the S1 pedocomplex at the Dingxi section. Farther SE to the Qinan section, the three paleosols (S1S1, S1S2, S1S3) have more distinguishable carbonate leaching and accumulation zones than at the Dingxi section. The S1 carbonate concentration at the Tianshui section suggests that the three paleosols were partially welded, as evidenced by the S1S3 and S1S2 paleosols sharing a major portion of the paleosol profile. Soil‐forming events occurred repeatedly in a single paleosol profile and the Ck horizon might have served as the carbonate accumulation zone for all three paleosols (S1S1, S1S2, S1S3) at the southeasternmost site (Lantian). Land surface stability complicated carbonate concentration processes in loessial paleosols and extra caution should be observed when interpreting climate implication of carbonate concentration data.