Transient state diagenesis in continental margin muds

The surface layer of marine sediments is an environment in transition: sediment added to the top of the layer transits to the bottom of the layer and is buried. A complex set of chemical reactions alters the sediment as it transits, lowering the free energy of the system. If a balance can be achieved between the rate of the reactions and the supply of the reactants, the distributions of reactants and reaction products can reach a steady state. Near the sediment–water interface the steady state is rarely achieved, and diagenesis proceeds via a succession of transient states that reflects variable external forcing and involves a multitude of redox reactions whose relative importance can vary in time and space. The transient state can be difficult to observe directly with conventional techniques, and much of what is known comes from indirect evidence. Development and application of new technologies for benthic research and monitoring are needed to advance our understanding of the time variable nature of sediment diagenesis.