CONCLUSIONS

Comparisons of ¹⁸O values among five sites from OJP and one site from Manihiki Plateau suggest that widespread Maastrichtian cooling affected these regions as well. These sites are farther south and west than other Maastrichtian tropical to subtropical Pacific sites. The ¹⁸O evidence for cooling appears to be a remarkably robust signal; it seems to have survived at all sites despite moderate to high degrees of lithification. The differences in average ¹⁸O values among sites matches the predicted pattern of initial alteration toward higher values and subsequent alteration toward lower values. In contrast to the systematic trends through the Maastrichtian in ¹⁸O values, ¹³C values seem to be relatively constant through the late Campanian and Maastrichtian. An excursion at or near the K/T boundary interval at four of the study sites is most likely the result of selective cementation of limestones in the boundary interval.