Postsedimentær

Postsedimentær is a geology term used to describe processes, structures, and features that form after sediments have been deposited, during later stages of burial, diagenesis, or tectonic reworking. The concept distinguishes changes that occur after deposition from those formed during it (syn-sedimentary) and from later metamorphism.

Its main focus is diagenesis, the suite of chemical and physical processes that transform sediment into rock. This includes compaction, cementation by minerals such as calcite or silica, dissolution, recrystallization, and the development of secondary porosity. Postsedimentære changes can alter grain contacts, pore spaces, mineralogy, and mechanical properties, influencing porosity and permeability in reservoir rocks.

Postsedimentære processes also cover tectonic deformation that reorganizes sediments after burial, such as faulting, fracturing, pressure solution, stylolites, and other deformation textures. Near surface weathering and chemical alteration, on rocks that remain within the post-depositional history, may also be described as postsedimentær in some contexts.

Context and usage: The term helps geologists separate the history of a rock into deposition, post-depositional modification, and subsequent geological events. While its exact scope can vary by region or discipline, postsedimentær generally refers to changes that follow deposition but precede full metamorphism, or to the broader set of near-surface diagenetic alterations that modify sedimentary rocks.

See also diagenesis, lithification, sedimentology, post-sedimentary deformation.