The Cretaceous/Tertiary boundary is marked by a particularly extensive change in the fossil record. A consequence of this major biotic perturbation would be a change in the composition and the amount of organic matter contributed to depositing sediments. The project will investigate the nature of the organic matter contents of sediments deposited during late Maastrichtian times, at the K/T boundary itself, and during early Danian times. Analyses will include elemental, isotopic, and molecular identifiers of the sources and of the preservation of organic matter components. Two K/T sections, Brazos (Texas) and Raton Basin (New Mexico), have been studied by many investigators. Microfossil, palynological, and other stratigraphic information exist from both locations, which will be helpful in interpreting the geochemical data in terms of paleoenvironmental changes. Closely spaced samples from several sites at these locations will be the subject of this project. The investigation will extend to "background" sediments deposited well before and well after the actual K/T boundary in order to determine the extent of natural variability. Furthermore, geochemical information has suggested a relationship between iridium anomalies at the boundary and microbial activity, which can be tested by searching for biomarker molecules indicative of microbial residues in the organic matter record.
