Identifying chronostratigraphic breaks in aeolian sediment profiles using near-surface luminescence dating and changepoint analysis

• Published in: Quaternary geochronology 2018-06, Vol.46, p.45-58
• Main Authors: Buckland, Catherine E., Bailey, Richard M., Thomas, David S.G.
• Format: Article
• Language: English
• Subjects: Aeolian systems; Changepoint; Chronostratigraphy; Environmental noise; Luminescence dating; Thresholds
• ISSN: 1871-1014; 1878-0350
• DOI: 10.1016/j.quageo.2018.03.011

Optical dating of depositional profiles provides information on environmental change and dune reactivation in aeolian systems. However, identifying the optimum locations and samples for luminescence dating is often confounded by a lack of visible internal structures and a highly discontinuous and heterogeneous record. We use a method that combines high-resolution coarse luminescence signals with statistical changepoint analysis to identify significant chronostratigraphic breaks. The changepoint algorithm demonstrates an ability to identify changes in a depositional profile with depth, allowing luminescence dating to be better-focused on specific points of chronological change. Likewise, this method ensures that chronostratigraphical breaks in the record are not missed due to coarse sampling strategies. This method is applied to a dataset from near-surface dune profiles from the Nebraska Sandhills, testing whether fully-prepped SAR luminescence ages from an identified chronostratigraphic section are representative of the wider unit identified in the changepoint analysis. Unlike previous methods, this therefore ensures that resultant chronologies are a factor of true chronological breaks as opposed to aliasing (i.e. misidentification of a signal), and capture the heterogeneous record across the dynamic environment.