Figure F1. Plots of isotopic values vs. depth for bulk carbonate from upper Campanian–Maastrichtian samples of Sites 1258,1259, 1260, and 1261. Carbon and oxygen data are plotted at the same scale in all plots. Note similar values are observed at all sites (including the few analyses for Site 1257; see Table T1, ). Relatively low values and high scatter in delta13C data may indicate a significant contribution from remineralized organic matter in secondary calcite in most samples. Relative lack of scatter in delta18O values may result from diagenetic temperatures that did not differ too greatly from primary values. There is also a minimum indelta18O values the upper half sections from Sites 1258, 1259, and 1260. VPDB = Vienna Peedee belemnite.

Figure F1. Plots of isotopic values vs. depth for bulk carbonate from upper Campanian–Maastrichtian samples of Sites 1258,1259, 1260, and 1261. Carbon and oxygen data are plotted at the same scale in all plots. Note similar values are observed at all sites (including the few analyses for Site 1257; see Table T1). Relatively low values and high scatter in

¹³C data may indicate a significant contribution from remineralized organic matter in secondary calcite in most samples. Relative lack of scatter in

¹⁸O values may result from diagenetic temperatures that did not differ too greatly from primary values. There is also a minimum in

¹⁸O values the upper half sections from Sites 1258, 1259, and 1260. VPDB = Vienna Peedee belemnite.