Elemental mapping of Mg/Ca intensity ratios in marine mollusc shells using laser-induced breakdown spectroscopy

Abstract

Here we apply Laser Induced Breakdown Spectroscopy (LIBS) to efficiently map the elemental change throughout the growth increments of three mollusc shells. We employ an automated LIBS setup to map the Mg/Ca composition of whole shell sections with over 2000 data points per hour.

Annual Growth Patterns and Interspecimen Variability in Mg/Ca Records of Archaeological Ostrea edulis (European Oyster) from the Late Mesolithic Site of Conors Island

“…Mg/Ca ratios Besides the connection between Mg/Ca ratios and growth rates, there are further factors influencing the elemental composition (Elliot et al 2009;Freitas et al 2012;Poulain et al 2015;Hausmann et al 2017). These additional factors have the potential to superimpose seasonal patterns of growth, and thus frustrate the interpretation of the season of death.…”

“…These additional factors have the potential to superimpose seasonal patterns of growth, and thus frustrate the interpretation of the season of death. Most prominently, these additional factors have been identified as the following: (1) gradual change of the Mg/Ca ratios with increasing distance to the hinge (Hausmann et al 2017), (2) age-related (ontogenetic) baseline shifts of Mg/Ca ratios (Elliot 2009), and, (3) short-lived peaks of high Mg/Ca ratios during unpredicted growth cessations leading to organically rich lines (Schöne et al 2013), which are additional to the predicted annual growth cessation. By mapping the entirety of the hinge section (Figure 3a), we aim to assess the spatial impact of these factors across the growth increments and find ways to avoid or acknowledge them in our interpretation of growth patterns.…”

“…Building on this, we employed the spectroscopic method of Laser Induced Breakdown Spectroscopy (LIBS), which has recently been used as a fast elemental mapping technique for mollusc shells (Hausmann et al 2017;Hausmann et al 2019a), has been shown to reach analytical speeds of over 300,000 measurements per hour (Cáceres et al 2017), and requires little sample preparation (Cobo et al 2015;García-Escárzaga et al 2015;Cobo et al 2017;Hausmann et al 2019b). We aim to explore the use of LIBS to create 2-dimensional maps of Mg/Ca ratios, and relate these 2D patterns to the incremental growth structures of the European oyster obtained via microscopic analysis.…”

Red Sea Palaeoclimate: Stable Isotope and Element-Ratio Analysis of Marine Mollusc Shells

“…Graniero et al 2017). Nevertheless, elemental ratios have the advantage that they can be assessed very quickly (Cobo et al, 2017;Durham et al 2017;Giakoumaki et al, 2007) and can easily be analysed in the form of spatially detailed maps (Cáceres et al, 2017;Hausmann et al, 2017). Additionally, fast analyses have the benefit of lower costs for individual samples, which can result in larger archaeological datasets of seasonal coastal exploitation.…”

“…The experiments were carried out using the LIBS setup described in Hausmann et al (2017), which can be used to provide maps of elemental ratios with a resolution of ~90 µm. However, sample locations were measured using single pulses instead of 10 to achieve a faster acquisition speed.…”