Brazilian semiarid soils formed during the last glacial maximum

Soils formed on pisoliths and sandstones in the Brazilian semiarid were investigated using a high-resolution depth approach to give pedosedimentary and paleoenvironmental reconstructions of the Late Glacial/Holo-cene pedosequence. Differential erosion favored dissection of an erosion surface that formed isolated plateaus in the Brazilian semiarid. Hyperdystric Ferralsols and Plinthosols occur in flat tops and steep slopes of isolated plateaus. Pedogenesis and erosion/sedimentation-driven pedogenesis influenced the formation of deep, dystro-phic, and well-developed soils in plateaus due to environmental conditions from the Late Glacial Maximum throughout the Holocene. Wavy extinction of coarse fraction and Fe-rich nodules, described in thin sections of diagnostic horizons, indicated a similar parent material of soils in plateaus. The TiO2/ZrO2 content ratio of the sand fraction, determined by X-ray fluorescence, indicated horizons buried at 18 kyr, whose strong formation corresponds to a dense paleovegetation and a humid palaeo-climate. The Last Glacial Maximum enabled the formation of Ferralsols by pisoliths and sandstones weathering in plateaus, and semi-deciduous forests persisted on plateaus despite a dry climate since the Late Holocene. Hypereutric Luvisols and Regosols are derived from gneiss in lowlands associated with the modern semiarid climate.

Automated summary

This study investigates the soils formed on pisoliths and sandstones in the Brazilian semiarid, providing insights into the pedosedimentary and paleoenvironmental histories of the Late Glacial/Holocene pedosequence. The formation of isolated plateaus in the Brazilian semiarid resulted from differential erosion. Pedogenesis and erosion/sedimentation-driven pedogenesis influenced the development of deep, dystrophic soils in the plateaus from the Late Glacial Maximum to the Holocene. The presence of similar parent materials and buried horizons suggests a consistent formation process in the plateaus.