NEW INSIGHTS INTO THE LOCAL REDOX LANDSCAPE OF THE MIDDLE ORDOVICIAN BALTOSCANDIAN CARBONATE SHELF FROM I/CA RECORDS
Here, we employ the iodine-to-calcium ratio (I/Ca) redox proxy as a tool to investigate the local redox landscape of several carbonate-dominated Middle Ordovician sections spanning the Baltoscandian paleoshelf. Iodine is one of the first elements to respond to changes in water column oxygenation, making this proxy especially useful for evaluating local shifts in marine oxygen content relative to the timings of Ordovician biodiversification pulses. The findings of this study expand upon and are consistent with previously published high-resolution I/Ca records from Baltica by Lindskog et al. (2023), suggesting these regional marine environments underwent shifts to comparatively more oxygenated conditions that are coincident with increases in diversity (i.e., carbonate skeletal variety and abundance). Though we cannot unambiguously connect biodiversity trends to redox conditions on global scales based on our I/Ca data alone, this regional study at least further implicates local marine oxygenation as one of the drivers of increased biodiversity in Baltica and may provide insight into connections between habitability, oxygenation, and climate during the GOBE.