A comparative analysis of elemental imaging of marine mollusc shells using Laser Induced Breakdown Spectroscopy

Abstract

The elemental composition of marine mollusc shells can offer valuable information about palaeoclimate and the season of shell collection. In particular, the correlation between Mg/Ca ratios of shell carbonate and the sea surface temperature has been tested. However, this correlation can also be strongly dependent on endogenous mechanisms of the animals. These mechanisms are still poorly understood and are often difficult to distinguish from methodological effects. Here we present the results of a comparative study of LIBS analyses performed on modern limpet (Patella vulgata Linnaeus, 1758) shells in two different laboratories (UC-PEG and LEIZA). In particular, 2D LIBS imaging has been performed to obtain the associated elemental composition in an attempt to avoid the uncertainties derived from the use of linear scanning trajectories on the shells. The goal of this study is to evaluate the impact of the different setups and processing techniques employed on the obtained results regarding palaeoclimatic information and the possible implications in the interpretation of these data. We demonstrate that the uncertainties found in the analysis of some of the specimens are not related to the specifics of the LIBS technique, but to the irregularity of limpet growth patterns themselves.