USING X-RAY MICRO CT SCANNING TO ASSESS PRESERVATION OF FORAMINIFERA ACROSS MULTIPLE SITES IN THE SUB-ANTARCTIC SOUTHERN OCEAN

The post-depositional dissolution of foraminiferal calcite has been described across multiple deep sea drilling sites in the global ocean and is known to be controlled by initial calcite composition and bottom water carbonate chemistry. Various foraminifera-based geochemical proxies can be susceptible to dissolution, motivating approaches to independently quantify its effects on ensuing paleoceanographic reconstructions. Here, we use X-Ray Micro CT Scanning (XMCT) as a means to assess the extent and locations of dissolution within a single foraminiferal test. Past laboratory studies have highlighted the potential promise of this approach, but detailed studies on specimens collected from marine sediment cores remain lacking. Accordingly, we will perform XMCT on planktic foraminifera collected from a series of successively deeper sites from the sub-Antarctic Southern Ocean. We focus on the planktic foraminifer Globigerina bulloides from the mudline/coretop sediments of IODP Expedition 392 Sites 1579 (2498 mbsl), U1580 (2560 mbsl), U1582 (3429 mbsl) drilled on the Agulhas Plateau; Site U1581 (4591 mbsl) in the Transkei Basin, and ODP Leg 177 Site 1088 (2082 mbsl) located on the Agulhas Ridge. As the calcite saturation state of seawater decreases with increasing water depth, it is reasonable to hypothesize that the foraminifera at the deeper sites will be less preserved than those at the shallower sites.