Modelling heterogeneously bleached single-grain equivalent dose distributions: Implications for the reliability of burial dose determination

In optical dating, incomplete and heterogeneous resetting (“bleaching”) of the luminescence signal measured from mineral grains since the last episode of transport and deposition is commonly observed for sedimentary samples. As a result, different grains could have different equivalent dose (De) values at the time of deposition. For such samples, statistical treatment of the De distribution is required to estimate the burial dose. This study aims to assess the reliability of burial dose determination for heterogeneously bleached samples using the minimum age model (MAM). We modeled heterogeneous bleaching processes under various bleaching scenarios and simulated the resulting single-grain De distributions using a Monte Carlo method. Various factors that could potentially affect the reliability of burial dose estimates are investigated, including the distribution of residual dose, proportion of fully bleached grains, baseline dose, sample size, and unaccounted between-grain standard deviation. The simulation results reveal that the performance of the model depends primarily on the residual dose distribution. The proportion of fully bleached grains has the most influence on the reliability of MAM burial dose estimates.