NEW δ7LI DATA ACROSS THE LLANDOVERY-WENLOCK BOUNDARY OF GOTLAND, SWEDEN

The Ireviken Biogeochemical Event (IBE) occurred across the Llandovery-Wenlock boundary and is one of several major biogeochemical events that occurred throughout the Silurian. This event consisted of increased biotic turnover, a major positive carbon isotope excursion, and significant perturbations within other geochemical cycles. Recent stable sulfur isotope work through this interval demonstrated a correlation with the expansion of reducing marine conditions near the onset of the positive carbon isotope excursion. An expansion of reduced environments can be driven by increased nutrient availability that fuels primarily productivity and eventually leads to reduced zones as biologic material decays. While this mechanism for the production of increased reducing environments is largely accepted, the cause of increased nutrient availability during the Ireviken event remains unknown.

Lithium stable isotopes ( δ⁷Li) could provide insight into the potential source of increased nutrient availability at the onset of the Ireviken biogeochemical event. This stable isotopic system is primarily affected by silicate weathering and provides a unique opportunity to look at perturbations within geochemical cycles unaffected by biologic function. The Altajme core from Gotland, Sweden, offers an exceptionally well preserved and expanded stratigraphic sectionand provides an ideal study interval to determine the precise timing of biogeochemical events during this time. New lithium data along with previous carbon and sulfur work provide key insights into the potential relationship between continental weathering, increased nutrient availability, and the expansion of reduced environments during the Ireviken Biogeochemical Event.