Continuous record of Upper Ordovician (Katian) to lower Silurian (Telychian) global δ 13 <scp>C</scp> excursions in the Williston Basin

The Williston Basin retained a high-resolution record of global δ13C fluctuations during the ~13 Myr duration Upper Ordovician-lower Silurian, and is a possible missing link in correlations between Laurentian margins and its interior. This study integrates δ13C and conodont biostratigraphy to yield a high-resolution, continuous composite spanning from the Upper Ordovician Aphelognathus grandis Zone into the lower Silurian D. staurognathoides Zone. From oldest to youngest, six global δ13C excursions are identified: (1) Whitewater (=Moe) and (2) Elkhorn (=Paroveja) in the Amorphognathus divergens Zone ; (3) LHICE (KaH?) in the Aphelognathus shatzeri Zone ; (4) HICE in the Ozarkodina hassi Zone ; (5) early Aeronian within the Distomodus kentuckyensis – Pranognathaus tenuis zones and (6) late Aeronian within the Psuedolonchodina expansa – D. staurognathoides zones. This δ13C record helps to alleviate some of the uncertainties in determining the precise order, duration, and timing of events influencing the biotic, climatic, oceanic, and sea-level evolution of the Upper Ordovician-lower Silurian successions across Laurentia.