We have measured Mg/Ca, Sr/Ca and Na/Ca in carbonate shells of the deepwater bivalve Acesta excavata. The samples were collected in the Sula reef and the Leksa reef on the Norwegian margin in summer 2014.Measurements were conducted using LA-ICP-MS.Laser ablation was performed using a Resolution M50 193 nm ArF Excimer Laser system (Resonetics), with a 72 μm beam diameter, a pulse rate of 10 Hz and 10 μm/s scan speed. Total sweep time was 0.65 s. Prior to the measurement a fast precleaning pass was conducted at 0.2 mm/s, 10Hz, and 104 μm laser spot size. Elemental ratio analysis was performed with a Thermo-Scientific ELEMENT XR sector field ICP-MS.In total, eight specimens were measured. In three specimens we measuerd perpendicular to the shell to investigate all shell layers. Additionally, we measured all eight samples in the fibrous and microgranular shell section (calcite). The measurements were taken from the ontogenetic oldest part of the bivalve (ventral side), spanning a length of 20 mm.