sedimentytan

Sedimentytan is a term found in some speculative discussions within sedimentology to describe a theoretical class of fine-grained, organic-rich deposits formed in low-energy aquatic environments. The name signals a distinct facies, though usage varies and it is not universally standardized.

Formation and composition: Sedimentytan deposits are typically dominated by clay minerals such as illite and smectite, with interbedded quartz and minor feldspar. They often contain substantial organic matter, including humic substances and kerogen-like material, and may host trace iron sulfides such as pyrite. The pore network is fine, yielding low permeability but high porosity when buried.

Depositional settings: These deposits are associated with calm, stratified water bodies—deep lakes, stable floodplains, backbarrier lagoons, and prodelta environments—where sedimentation rates bury organic matter rapidly while limiting oxidation.

Diagenesis and significance: In early diagenesis, organic matter interacts with pore fluids to form textures unique to this facies, contributing to carbon burial and informing paleoenvironmental interpretations. Because sedimentytan is not widely used as a formal facies, it remains a provisional concept in current literature.

See also: sedimentology, organic-rich muds, diagenesis.