9 - Calcium Carbonate Features

Abstract

The precipitation of calcium carbonate is common in soils and regoliths, especially in soils of arid environments. The precipitation and the accumulation of calcium carbonate in soils and regoliths are very complex phenomena. As they are linked to the interaction between the lithosphere, the biosphere, and the atmosphere, pedogenic carbonates may be important proxies of paleoenvironmental changes. The study of the morphological expression and hierarchical organisation of calcitic pedofeatures in thin sections allows us to partially decipher the climatic, geochemical, and biological influences on the precipitation of carbonates in soils. With the contribution of submicroscopic techniques (e.g., SEM), progress has been made in the understanding of the relation between the biological activity and the precipitation of carbonate, and many calcitic features seem to be linked to biological processes, in a direct or indirect manner. The carbonates may represent a highly active phase, undergoing intense transformation such as recrystallisation, dissolution, and secondary carbonate precipitation.