(Table 1) Distribution of upper Campanian-lower Maestrichtian calcareous nannofossils at DSDP Hole 71-511@en

Calcareous nannofossils from upper Campanian-lower Maestrichtian Deep Sea Drilling Project Leg 71 Cores 511-23 and 511-24 are described and correlated with assemblages of similar age from piston and drill cores on the Falkland Plateau, South Atlantic Ocean. The Leg 71 cores partially fill a drilling gap of at least 20 meters left within a thick (50 m) carbonate section first drilled by DSDP Leg 36 at Site 327. Cores 511-23 and 511-24 both fall within the upper portion of the Biscutum coronum Zone of Wind and demonstrate an overlap in the range of Monomarginatus quaternarius with the ranges of M. pectinatus, Misceomarginatus pleniporus, and Biscutum coronum across the Campanian/ Maestrichtian boundary. Resolution of the sequence of highest occurrence datums for the latter species must await the recovery of a more complete section. Comparison of the Site 511 assemblages with those from Mas Orcadas Core 07-75-44 to the north confirms earlier speculation that the Falkland Plateau served as an important boundary between major water masses during the Late Cretaceous.本文对取自深海钻探计划（Deep Sea Drilling Project, DSDP）第71航次511-23号与511-24号岩心的坎潘期晚期-马斯特里赫特期早期钙质超微化石（calcareous nannofossils）进行了系统描述，并将其与南大西洋福克兰高原地区同年代活塞岩心及钻探岩心中的化石组合开展对比分析。本次第71航次的岩心部分填补了327站位由DSDP第36航次首次钻获的厚达50米碳酸盐岩地层中遗留的至少20米的钻探空白。511-23与511-24号岩心均隶属于Wind等人建立的冠形盘星石（Biscutum coronum）组合带上部，且显示出四齿单缘球（Monomarginatus quaternarius）的延限范围与M. pectinatus、厚孔混缘球（Misceomarginatus pleniporus）以及冠形盘星石（Biscutum coronum）的延限范围在坎潘期/马斯特里赫特期界线处存在重叠。针对后述物种的最高产出基准面序列的厘定，尚需等待更完整地层剖面的获取。将511站位的化石组合与北部的马斯奥达斯（Mas Orcadas）07-75-44号岩心的化石组合进行对比后，证实了此前的学术推测：福克兰高原在白垩纪晚期曾是全球主要水团之间的重要分界。