penecontemporane

Penecontemporaneous refers to geological events or processes that occur very close in time. In stratigraphy, it describes depositional units that are formed at essentially the same time but in different locations. This concept is crucial for understanding the lateral relationships and synchronous development of rock layers. For instance, if a river delta forms and a marine environment exists nearby, the sediments deposited in the delta and the marine sediments might be considered penecontemporaneous if their formation periods overlap significantly.

The term is also applied to diagenetic processes, which are changes that occur in a sediment after its initial deposition. Penecontemporaneous diagenesis happens very soon after deposition, while the sediment is still relatively unlithogenic or unconsolidated. Examples include early cementation, bioturbation by organisms, and the formation of concretions. Understanding penecontemporaneous diagenesis is important because these early alterations can profoundly influence the final properties of the rock, such as its porosity and permeability. The precise temporal resolution implied by "penecontemporaneous" can vary depending on the geological context and the processes being studied, but it generally signifies a high degree of temporal proximity.