Whole-rock oxygen and carbon isorope record across the Cretaceous/Tertiary boundary in ODP Hole 130-807C

Whole-rock d18O analyses of the Paleogene and Upper Cretaceous succession at Ocean Drilling Program Hole 807C suggest the presence of hiatuses between 876.95 and 894.47 mbsf and between 1138.82 and 1140.94 mbsf. The d13C data show a pronounced positive excursion between 1130 and 1180 mbsf that corresponds to the positive d13C values characteristic of the Paleocene. Despite the stratigraphic breaks in the section, the d18O data show a systematic increase between 1360 mbsf and the hiatus between 876.95 and 894.47 mbsf, which is consistent with previous suggestions of long-term climatic cooling through the Paleogene. The Cretaceous/Tertiary transition is apparently complete in this section and is of remarkable thickness. The expanded nature of this portion of the succession is probably the result of secondary depositional processes. High-resolution sampling across this boundary may reveal detailed structure of the d13C decline associated with the extinctions that mark the termination of the Cretaceous.

对大洋钻探计划(Ocean Drilling Program)807C孔处的古近系与上白垩统沉积序列开展的全岩氧同位素(d¹⁸O)分析显示，在876.95~894.47 海底以下米（meters below seafloor, mbsf）以及1138.82~1140.94 mbsf层位之间存在沉积间断。碳同位素(d¹³C)数据显示，在1130~1180 mbsf层位间存在显著的正同位素偏移，该偏移与古新统标志性的正碳同位素值特征相吻合。尽管该剖面存在地层间断，全岩氧同位素数据仍显示，在1360 mbsf至876.95~894.47 mbsf层位间的沉积间断区间内，同位素值呈现系统性升高趋势，这与此前提出的"古近纪存在长期气候变冷"的观点一致。该剖面中的白垩纪/第三纪界线整体保存完整，且厚度可观。该套沉积序列该段的增厚特征，大概率由次生沉积作用所致。对该界线开展高分辨率采样，或可揭示与白垩纪末灭绝事件相关的碳同位素下降的精细结构。