Crystal orientation in subantarctic planktic foraminifera shells from EBSD analysis from collections in the sub-Antarctic south of South Africa between 1993 and 2016

Here we present crystal orientation maps from the shells of planktic foraminifera, calcifying marine protists (G. inflata and G. truncatulinoides), from the Subantarctic ocean (net-tows) and underlying surface sediments (core-tops). The goal was to investigate post-mortem alteration of shells that might affect paleo-proxy interpretation (i.e., diagenesis). Living specimens were collected by S. Smart on VOY016 (Jul–Aug 2015) and VOY019 (Apr–May 2016) of the R/V S.A. Agulhas II in the Subantarctic south of South Africa (Smart et al., 2020). The core-top sample (PS2489-4; from 42.883 °S, 8.968 °E, water depth 3795 m) was collected on ANT-XI/2 of the R/V Polarstern in December 1993 (Gersonde et al., 2003), and access was provided by the Alfred Wegener Institute (AWI) and Max Planck Institute for Chemistry (MPIC), Germany. Shells were mounted in epoxy, cross-sectioned and thinly gold-coated for Scanning Electron Microscopy-Electron Backscatter Diffraction (SEM-EBSD) analysis by S. Smart at the Central Analytical Facility of The University of Alabama, USA, between 2021 and 2024. A. Pérez-Huerta provided EBSD training and mentoring, J. Goodwin and R. Holler provided technical support, and H. Stowell and S.E. Fawcett assisted with interpretation.