Paleogene calcareous nannofossil stratigraphy of ODP Leg 120 sites@en

Calcareous nannofossils are abundant in the Paleogene sediments recovered during Ocean Drilling Program Leg 120. Although no continuous Paleogene section was obtained, Sites 747 through 751 complemented each other so as to provide a virtually complete composite stratigraphic section. The calcareous nannofossil biostratigraphy at Sites 747, 748, and 749 is discussed. Correlation of calcareous nannofossil biozones and magnetozones at these sites suggests some diachrony with low-latitude areas, as well as on a regional basis. Changes in calcareous nannofossil diversity throughout the Paleogene are analyzed and interpreted as reflecting major paleoclimatic events.大洋钻探计划（Ocean Drilling Program）第120航次所获取的古近纪沉积物中，钙石超微化石（Calcareous nannofossils）丰度极高。尽管本次航次未获取连续完整的古近纪沉积剖面，但747至751号钻探站位相互补充，共同构建了近乎完整的复合地层剖面。本文对747、748及749号站位的钙石超微化石生物地层学（biostratigraphy）展开探讨。通过对上述站位的钙石超微化石生物带（biozones）与磁极性带（magnetozones）开展对比分析，结果显示其与低纬度区域乃至区域尺度范围内均存在一定程度的穿时性（diachrony）。研究人员对整个古近纪时期钙石超微化石多样性的变化进行分析，并将其解读为反映了重大古气候事件（paleoclimatic events）的演化过程。