(Table T1) Stable oxygen and carbon isotopes of bulk carbonate from ODP Leg 207 sites@en

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 per mil and 2 per mil for d13C and between -2 per mil and -3 per mil for d18O. The relatively low values and high scatter of d13C 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 d18O 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.取自西热带大西洋德马拉拉海隆（大洋钻探计划Ocean Drilling Program第207航次、站位1257至1261）的174件晚坎潘期至马斯特里赫特期全岩碳酸盐样品的稳定同位素数据显示：其碳同位素（δ13C）值大多介于0‰至2‰之间，氧同位素（δ18O）值则集中于-2‰至-3‰区间。观测到的碳同位素值偏低且离散度较高，表明本次分析的绝大多数乃至全部样品中均含有携带有机碳再矿化组分的次生方解石。相较于碳同位素数据，氧同位素数据的离散度更低，其数值更接近现代海面环境的理论预期值。不过，基于船上实验室给出的年龄估算结果，单个剖面的氧同位素数据趋势在各站位间并不具有相关性。无论后续的年龄估算结果是否会修正钻孔间的相关性，在这些站位开展晚坎潘期至马斯特里赫特期同位素趋势研究时，成岩作用相关的干扰都将是一项显著的复杂问题。