OSL and sediment accumulation rate models: Understanding the history of sediment deposition

Coastal deposits are very dynamic systems that may not have constant sediment accumulation rates over time. High-resolution reconstruction and dating of coastal environments, e.g. timing of vertical accretion of dune and/or beach ridges, can be achieved when collection of samples is closely-spaced, although this method is not always economically viable or time-effective. The low terrestrial dose rate environment leads to an unusual situation in which sample ages depend on the rate of accumulation of the overburden. By mathematically coupling successive sample ages obtained from vertical sediment cores, we are able to provide constraints on the model accumulation profiles. The dependence of sample age on the accumulation model is presented, and sample ages are compared with leading accumulation models of dune and beach ridge formation.

► OSL ages depend on the rate of accumulation of sediment.
► Overburden thickness is critical when cosmic dose is a large part of the total dose.
►  A method of calculating dose rates as a function of changing overburden over time.
► The Stepwise Accumulation Model constrains the re calculated OSL age range.
► This more realistic model of sediment accumulation can change OSL ages up to 5%.