In situ Mg isotope measurements of biogenic carbonates using laser ablation multi‐collector inductively coupled plasma mass spectrometry: A new tool to understand biomineralisation

Rationale Magnesium is one of the most abundant elements in the earth's crust and in seawater. Fractionation of its stable isotopes has been shown to be a useful indicator of many geological, chemical, and biological processes. For example, biogenic carbonates display an ~5‰ range of δ26Mg values, which is attributed to variable degrees of biological control on Mg ions during biomineralisation. Understanding this biological control is essential for developing proxies based on biogenic carbonates. Methods In this work, we present a new approach of measuring Mg isotopes in biogenic carbonates using Laser Ablation Multi‐Collector Inductively Coupled Plasma Mass Spectrometry (LA‐MC‐ICPMS). Results Our results show that this microanalytical approach provides relatively fast, high spatial resolution (