MICROCT ASSESSMENT OF FORAMINIFERAL CALCITE PRESERVATION FROM THE PETM AND K/PG BOUNDARY, AGULHAS PLATEAU

This study seeks to use micro-computed tomography (MicroCT) as a screening tool for fossil specimens of foraminifera prior to geochemical analysis. MicroCT imaging facilitates the documentation of diagenetic alteration, including the degree of recrystallization, test infilling, and post-depositional introduction of geochemical contaminants. Recent work has also pioneered this technique for determination of foraminiferal calcite test density in cross-sectional view. In the present study, over 40 high resolution scans were performed on planktonic and benthic foraminifera from the Paleocene-Eocene boundary, and 20 scans were performed on specimens from the Cretaceous/Paleogene (K/Pg) boundary interval of IODP Expedition 392 cores (Agulhas Plateau, Southwest Indian Ocean). Calcite volumes and density maps were generated using Dragonfly 3D World and facilitate the assessment of foraminifera trends through the PETM and K/Pg boundaries. Following MicroCT analysis, laser ablation ICP-MS and whole-test stable isotopic analyses (δ13C, δ18O) were also performed to compare tests with different calcite qualities with their geochemical values. Additionally, low-resolution scans of multiple specimens may be applicable as a rapid screening tool to avoid specimens with significant contamination.