“…Patzkowsky et al, 1997;Ludvigson et al, 2000Ludvigson et al, , 2004Saltzman and Young, 2005;Young et al, 2008;Bergström et al, 2010;Buggisch et al, 2010). While some of this variability may result from diagenetic overprints, differences in sampling protocol for δ 13 C carb analysis (Swart and Eberli, 2005;Metzger and Fike, 2013), and/or incorrect chronostratigraphy (Sell et al, 2015), the observed variability might also reflect local to regional influences on carbon cycling.…”