Characteristic directions and polarity ratings and polarity chron assignments of ODP Leg 171B sites

The full suite of magnetic polarity chrons from Subchron M''-2r'' (early Albian) through Chron C13r (latest Eocene) were resolved at one or more Ocean Drilling Program sites on the Blake Nose salient of the Florida continental margin. These sediments preserve diverse assemblages of calcareous and siliceous microfossils; therefore, the composite suite provides a reference section for high-resolution correlation of biostratigraphic datums to magnetic polarity chrons of the Late Cretaceous and Paleogene. Relative condensation or absence of polarity zones at different sites along the transect enhance the recognition and dating of depositional sequences and unconformities within the margin succession. A stable paleolatitude of ~25°N was maintained from the late Aptian through Eocene.完整的地磁极性时（magnetic polarity chrons）序列，覆盖从亚地磁极性时（Subchron）M''-2r''（阿尔布阶早期，early Albian）至C13r时（始新世最晚期，latest Eocene）的全部时段，在佛罗里达大陆边缘布雷克鼻凸起（Blake Nose salient）的一处或多处大洋钻探计划（Ocean Drilling Program, ODP）站位中得以解析。这些沉积物保存了丰富多样的钙质与硅质微化石组合，因此这套复合剖面可为晚白垩世（Late Cretaceous）及古近纪（Paleogene）的生物地层基准面（biostratigraphic datums）与地磁极性时的高分辨率对比提供标准参考剖面。该采样断面不同站位的极性带相对凝缩或缺失，这有助于识别该大陆边缘沉积序列中的沉积层序（depositional sequences）与不整合面（unconformities）并对其进行定年。从晚阿普第阶（late Aptian）至始新世（Eocene），研究区始终维持约25°N的稳定古纬度（paleolatitude）。