postformational

Postformational is an adjective used to describe processes, features, or modifications that occur after the initial formation of a geological body, landscape feature, artifact, or biological structure. Elements described as postformational are typically superimposed on or overprint earlier characteristics and can modify, obscure, or refine the original state.

In geology and geomorphology, postformational processes include weathering, erosion, diagenesis, burial metamorphism, and surface coatings that develop after rock emplacement or exposure. In planetary science, postformational alteration refers to changes to rocks after crystallization, such as hydrothermal alteration, oxidation, or other surface modification. In archaeology and materials science, the term can apply to changes that occur after manufacture or deposition, such as corrosion, patination, or later repairs and refinements.

Identifying postformational signatures involves looking for evidence that alterations overprint prior features, such as overgrowths, cross-cutting relationships, or mineralogical changes that cut across original textures. Dating and context, including stratigraphic position and regional history, help constrain the timing of alteration relative to formation.

The concept is used to distinguish processes that act after formation from those that occur during formation (preformational or synformational processes). It is also employed to describe overprinting in rocks, artifacts, and ecological or biological systems where later changes modify an earlier state.

See also: postformational alteration, diagenesis, metamorphism, weathering.