Calcareous nannofossils, pollen and spores from ODP Leg 178 sites

Calcareous nannofossils, pollen, and spores were examined on samples from Ocean Drilling Program Leg 178 Site 1095 on the continental rise and Sites 1097, 1100, and 1103 on the outer continental shelf of the western Antarctic Peninsula. Stratigraphically useful specimens of calcareous nannofossils occur in Site 1095 sediments assigned to Zones CN15, CN13b, and CN11. Calcareous nannofossils are rare but occur throughout the sedimentary sequences from seismic Units S1 to S3 on the continental shelf. Most of the calcareous nannofossils in Units S1 and S2 are composed of Cretaceous specimens that have been recycled by glacial processes. The occurrence of Dictyococcites in samples within Unit S3 upper Miocene sediments without any reworked specimens suggests those sediments are deposited in an open-ocean environment. These results are consistent with those from foraminifer and radiolarian studies. Pollen and spores including Nothofagidites, the genus for fossil pollen referred to as Nothofagus, are also observed in Unit S3 sediments. The sparse occurrence of pollen and spores, however, makes it difficult to assess the nature of the Antarctic terrestrial vegetation.

本数据集针对南极半岛西部大陆隆区大洋钻探计划（Ocean Drilling Program, ODP）第178航次1095站位，以及大陆架外缘的1097、1100与1103站位的沉积物样品，开展了钙质超微化石（calcareous nannofossils）、花粉与孢子的分析鉴定工作。在划归至CN15、CN13b与CN11带的1095站位沉积物中，发现了具有地层学应用价值的钙质超微化石标本。大陆架区的地震地层单元S1至S3沉积序列中虽钙质超微化石较为稀少，但均有产出；其中单元S1与S2内的钙质超微化石多为经冰川作用再沉积的白垩纪标本。单元S3晚中新世沉积物的样品中发现了网球藻属（Dictyococcites）化石，且未见再沉积标本，指示该套沉积物形成于开放大洋环境。该研究结果与有孔虫（foraminifer）、放射虫（radiolarian）的相关研究结论一致。单元S3沉积物中还检出了包括南山毛榉粉属（Nothofagidites，对应化石花粉隶属于南山毛榉属Nothofagus）在内的花粉与孢子化石。但由于花粉与孢子的产出较为稀少，难以准确评估南极陆地植被的特征。