7. Data Report: Stable Isotopic Ratios in Bulk Carbonate from Upper Campanian and Maastrichtian Samples (Demerara Rise, Western Tropical North Atlantic)¹

Kenneth G. MacLeod²

ABSTRACT

Stable isotopic values of 174 upper Campanian and Maastrichtian bulk carbonate samples from Demerara Rise, in the western tropical Atlantic (Ocean Drilling Program Leg 207, Sites 1257–1261), largely fall between 0 and 2 for ¹³C and between –2 and –3 for ¹⁸O. The relatively low values and high scatter of ¹³C values observed suggest secondary calcite with a remineralized organic carbon component was present in most to all samples analyzed. Oxygen isotopic data exhibit less scatter and values closer to those expected for contemporary sea-surface conditions than do carbon data. However, trends in ¹⁸O data at any one section do not correlate among sites using shipboard age estimates. Regardless of whether subsequent age estimates modify correlation among holes, diagenetic concerns will remain a significant complication in any efforts to study isotopic trends during the late Campanian–Maastrichtian at these sites.

¹MacLeod, K.G., 2006. Data report: stable isotopic ratios in bulk carbonate from upper Campanian and Maastrichtian samples (Demerara Rise, western tropical North Atlantic). In Mosher, D.C., Erbacher, J., and Malone, M.J. (Eds.), Proc. ODP, Sci. Results, 207: College Station, TX (Ocean Drilling Program), 1–9. doi:10.2973/odp.proc.sr.207.110.2006

²Department of Geological Sciences, University of Missouri, Columbia MO 65211-1380, USA. macleodk@missouri.edu

Initial receipt: 21 October 2005
Acceptance: 5 February 2006
Web publication: 28 November 2006
Ms 207SR-110