Predepositional

Predepositional describes processes, conditions, or chemical signatures that exist before a sediment is deposited. It is used primarily in geology, sedimentology, and environmental geochemistry to distinguish changes that occur in the source materials, provenance environment, or transport media prior to incorporation into a sedimentary record from processes that operate after deposition (postdepositional) or during burial (diagenetic).

In practice, predepositional factors include the weathering of parent rocks, chemical alteration during transport, concentration or depletion of elements in source materials, and other preparatory changes that shape the composition and mineralogy of the sediment before it settles. The concept is often invoked when interpreting isotopic ratios, elemental abundances, or mineral assemblages in sediments, where the observed signatures may reflect source-area processes rather than the conditions of the depositional environment itself.

Applications of the term appear in provenance studies, sedimentary geology, and environmental assessments, where distinguishing predepositional from postdepositional controls helps reconstruct transport pathways, source regions, and the history of sedimentary basins. It also informs models of metal mobility and enrichment, as predepositional alterations can set the stage for how elements behave during transport and burial.

See also: postdepositional, diagenesis, provenance, sedimentology.