A reaction-transport model of periodic precipitation of pyrite in anoxic marine sediments

Periodic precipitation patterns (Liesegang bands) constitute good manifestations of self-organization in geochemical systems. Examples of periodic pyrite bands have been previously reported in anoxic sediment systems, such as sapropels from the Eastern Mediterranean. In this contribution, we present a model of Liesegang pyrite band formation in anoxic marine sediments. The model is based on early diagenetic reactive-transport processes and incorporates nucleation and growth of pyrite crystallites. The simulation results of pyrite band formation are compatible with the experimental pyritization pattern observed in a sediment analog, as well as the observations in sapropel sediments.

► Periodic precipitation patterns (Liesegang bands) are manifestations of self-organization in geochemistry. ► Model of Liesegang pyrite band formation in anoxic marine sediments is suggested. ► The model combines early diagenetic reaction-transport, nucleation and growth of pyrite crystallites. ► Results are compatible with experimental pyritization pattern and observations in sapropel sediments. ► Main factors controlling the pyrite pattern are discussed.