Paleo-pedological record of the Rocourt pedosequence at Veldwezelt–Hezerwater (Belgian Pleistocene loess belt): Part 2 — Soil formation

Abstract

As the environment influences soil formation, Quaternary loess–paleosols provide an important, yet complex source on former climate and vegetation conditions. This study revises the paleopedological record of the Rocourt-complex, the pedostratigraphic marker for the Eemian and early Weichselian in the Belgian loess belt. Depth functions were established from an exceptionally well-preserved, in-situ sequence. Based on soil micromorphological features, total element contents, iron fractions and carbon content a reconstruction was made of the polygenetic formation of the Rocourt soil. Results indicate that only by combining multiple soil features, consistent information could be obtained. Furthermore, this study shows that cryogenic processes, transport of colloids, iron dynamics, redox-conditions, organic matter formation and biological activity were major soil forming processes. The hypothesis of six major stages of soil formation under varying climatic conditions was most supported by the data. During the warm to temperate oceanic climate of the Eemian, a strongly weathered argic horizon was formed. This horizon was later disrupted by reticulate ice segregation and stagnogley during the severe and prolonged cold conditions of the first cold stadial following the Eemian. Weak soil formation, during the relatively short continental St. Germain I interstadial, subsequently formed cambic soil properties and a humiferous horizon in a mixture of local and new sediments. These soils were disrupted by fragipan Formation, with its associated cryogenic structure, banded eluviation and redoxfront, during the succeeding stadial with periglacial conditions. During the St. Germain II, another A horizon formed in new, calcareous material during more stable climatic conditions, allowing organic matter build-up, eluviation of smectite and formation of pedogenetic iron. During the evolution from this warmer climate with forest or forested steppe to eventually periglacial open tundra, an accretionary humiferous soil concluded the last episode of soil formation before the onset of pleniglacial Weichselian conditions.