nondeposition

Nondeposition is a term used in sedimentology and stratigraphy to describe a period during which sedimentation ceases in a given depositional setting. During such intervals no net accumulation of sediment forms, and the surface that hosts the depositional environment remains intact without new layers.

Causes and controls of nondeposition include changes in sediment supply, accommodation space, and environmental conditions. A reduction or halt in sediment input can occur due to tectonic uplift, erosion of source areas, or climatic factors that limit transport. In marine and coastal settings, nondeposition may accompany stages of sea-level fall, basin shallowing, or environmental stabilization that prevents sediment burial. In continental basins, aridification or wind and water reworking of surface materials can also produce intervals with little or no net deposition.

Identification and significance: Nondeposition is inferred from gaps in the stratigraphic record, abrupt contacts, or unexpected breaks in facies progression that lack the evidence of contemporaneous sedimentation. When a period of nondeposition is later followed by renewed deposition, the surface separating the older and younger deposits can form an unconformity, representing a hiatus in time. Distinguishing nondeposition from active erosion can be challenging, since erosion can accompany or overprint nondepositional intervals; nonetheless, a nondepositional interval emphasizes the absence of new sediment accumulation rather than the removal of existing material.

In basin analysis, recognizing nondeposition helps reconstruct the timing of tectonic or climatic events and the history of accommodation space, contributing to interpretations of sedimentary cycles and regional geologic evolution.