Influence of sampling strategy, alignment method and growth morphology on the temporal contextualization of high-resolution geochemical data

High-resolution proxy reconstructions of physical and ecological variables in aquatic environments are commonly derived from biogenic archives such as bivalve shells. Interpretation of geochemical data measured in circular-shaped sample spots placed along shell cross-sections requires precise temporal alignment. The latter can be challenging, because differences in growth rate, morphology and sampling methods introduce biases to the reconstructed signals. This study systematically evaluates the impact of different sampling strategies and alignment methods on the reconstruction of environmental signals, i.e., temperature oscillations and phytoplankton blooms. Synthetic environmental signals and digital shell models of the bivalve Arctica islandica were used to numerically simulate how environmental variables are recorded during shell growth. A novel alignment method is presented, demonstrating significantly improved reconstruction accuracy when compared to traditional techniques. The new method enhances the reliability of proxy-based environmental reconstructions using biogenic archives and offers new insights into highly dynamic environmental signals such as phytoplankton blooms.