Radiocarbon Age of Vertisols and Its Interpretation Using Data on Gilgai Complex in the North Caucasus

Abstract

Radiocarbon dates were analyzed to assess Vertisols age around the world. They show an increase of radiocarbon age from mainly modern–3000 BP in 0–100 cm layer up to 10,000 BP at a depth 100–200 cm. Older dates reflect the age of parent material. The inversion of 14C dates seems to be a frequent phenomenon in Vertisols. A series of new dates of Vertisols from gilgai microhigh, microslope and microlow in the North Caucasus was done in order to understand the nature of this inversion. 14C age in the gilgai soil complex ranges from 70 ± 45 BP in the microlow to 5610 ± 180 BP in the microhigh. A trend of similar depths being younger in the microslope and microlow was found. We explain this by intensive humus rejuvenation in the microlows due to water downward flow. The older date in the microhigh represents the old humus horizon sheared laterally close to the surface and preserved by impermeable water regime. We explain inversions of 14C age-depth curves by the sampling procedures. In a narrow pit, genetically different parts of former gilgai could easily be as a genetically uniform soil profile. Because of this strong microvariability, Vertisols require sampling in a trench accounting for gilgai elements, even when gilgai are not obvious.

Constraints on Fe‐Oxide Formation in Monsoonal Vertisols of Pliocene Kenya Using Rock Magnetism and Spectroscopy

“…The data do not provide evidence of strong mixing by pedoturbation, adding to a growing consensus that the “inversion” model does not adequately explain all Vertisol formation (Driese et al, ; Nordt et al, ). However, it should be noted that mixing and stratigraphic inversions may occur near the margins of gilgai topography and synclines (Kovda et al, ).…”

Radiocarbon Dating of Soil Organic Matter Fractions in Andosols in Northern Ecuador

“…However, which fraction provides the most accurate dates is not obvious. 14 C dating of humic substances rendered more accurate results in a range of soil types (Pessenda et al 2001;Kovda et al 2001;Dalsgaard and Odgaard 2001;van Mourik et al 1995), but Andosols were not yet investigated. Dating peat bog sediments by 14 C analysis is generally more straightforward than dating terrestrial soils, as peat sequences are much less disturbed.…”

Carbon Dynamics in Vertisols as Revealed by High-Resolution Sampling

“…Characteristic evidence for this pedoturbation are stress cutanes ("slickensides") found on aggregate surfaces below the zone of the cracks which are formed by the shear forces. Under certain circumstances, pedoturbation in Vertisols also leads to lateral inhomogeneity with elevated and depressed areas, a micro-relief called Gilgai after an Australian aborigines term (Blackburn et al 1979;Kovda et al 2001). In the soils studied here, however, no Gilgai phenomenon was observed.…”