Rhizoliths in loess - a new tool to estimate post-sedimentary incorporation of organic matter in terrestrial environments

Pedogenic (secondary) carbonates are a typical feature of soils in arid and semiarid regions. In calcareous parent material, they are formed by dissolution of lithogenic (primary) carbonate and recrystallization with soil CO2. Usually, hundreds to thousands of years are necessary for complete recrystallization of primary CaCO3. δC of pedogenic carbonates reflects the photosynthetic pathway of the predominant local vegetation, because secondary CaCO3 is formed in isotopic equilibrium with soil CO2 released by root and rhizomicrobial respiration. Therefore, δC of pedogenic carbonates is used for paleoenvironmental reconstructions.