GEOCHEMICAL EVIDENCE OF ENVIRONMENTAL CHANGE SURROUNDING THE LATE SILURIAN LAU/KOZLOWSKII EXTINCTION EVENT FROM SHALE RECORDS OF PERUNICA (CZECH REPUBLIC)

The late Silurian was a time of widespread change environmentally, biotically, and oceanographically. Previously proposed Silurian climatic oscillations were often associated with marine extinction events. The Lau/Kozlowskii extinction (LKE) event, ~424 Ma, is recognized as the most severe marine extinction event in the Silurian. The LKE has been recognized in many major Paleozoic marine groups including conodonts, graptolites, fish, brachiopods, and acritarchs (phytoplankton group). Associated with this extinction is a large magnitude positive (+8–12‰) carbon isotope excursion (CIE), the Lau CIE. The Lau CIE has been recognized from many different basins on multiple paleocontinents and has been attributed to increased carbon burial as a result of widespread reducing conditions in the oceans. While previous studies have shown evidence for an increase in the global extent of anoxia coincident with LKE, these investigations have primarily been studied in low latitude areas. Here we present carbon isotope chemostratigraphy and local paleoredox proxy data (d³⁴S_py, Fe speciation, and trace metals) from a shale succession deposited in a high latitude setting on a peri-Gondwanan terrane, Perunica. The data generated from this study site will be correlated to previously published low latitude datasets from Baltica and Laurentia to further investigate marine redox dynamics and the extent of reducing conditions within the late Silurian oceans during this extinction interval. This multi-proxy dataset will further test the hypothesis which links the LKE and Lau CIE to a global expansion of anoxia and euxinia (anoxia with free hydrogen sulfide in the water column).