Luminescence age modeling of variably-bleached sediment: Model selection and input. (15th December 2018)

• Record Type: Journal Article
• Authors: Chamberlain, Elizabeth L.; Wallinga, Jakob; Shen, Zhixiong
• Is Part Of: Radiation measurements. Volume 120(2019:Jan.)
• Page Start: 221
• Page End: 227
• Publication Date: 2018-12-15
• Subjects: Bleaching -- Luminescence dating -- Overdispersion -- Residual dose -- Quartz sand; Nuclear emulsions -- Periodicals; Particle tracks (Nuclear physics) -- Periodicals; Thermoluminescence -- Periodicals; Cosmic rays -- Periodicals; Radiation -- Measurement -- Periodicals; Radiometry -- Periodicals; Radiation Monitoring -- Periodicals; Émulsions nucléaires -- Périodiques; Particules (Physique nucléaire) -- Traces -- Périodiques; Thermoluminescence -- Périodiques; Rayonnement cosmique -- Périodiques; Radiométrie -- Périodiques; 539.77
• DOI: 10.1016/j.radmeas.2018.06.007
• Languages: English
• ISSNs: 1350-4487

Abstract

Abstract: Optically stimulated luminescence (OSL) dating of heterogeneously-bleached sediment by means of a minimum age model requires the input of a 'sigma_b' ( σ b ) value describing the overdispersion of the single-aliquot D e distribution expected for a well-bleached sample. We propose that σ b and associated uncertainty can be accurately determined if a large dataset of D e distributions is available and includes well-bleached samples. Our approach applies the bootstrapped Minimum Age Model (bootMAM) to a dataset of overdispersions in D e distributions, to obtain quantitative estimates of σ b . Corrections are made for constant-diameter aliquots of different grain sizes, based on the published dependency of overdispersion on the number of grains per aliquot. These adapted σ b values are then input to bootMAM to obtain robust paleodoses for the samples. We test the sensitivity of paleodose to σ b and we demonstrate that with correct σ b, identical paleodoses are obtained using bootMAM and the Central Age Model on samples judged to be well-bleached. We conclude that for large datasets consisting of well- and heterogeneously-bleached samples, appropriate σ b values can be obtained from the data, and that bootMAM can be applied to all samples within this dataset. Highlights: Archival OSL data from Mississippi Delta quartz sand samples (n = 42) inform age model selection and input. Valid overdispersion ( σ b ) inputs for age modeling are obtained from the dataset. The bootstrapped Minimum Age Model yields robust ages for well- and heterogeneously-bleached samples herein.