(Table 1) Distribution of Lower Cretaceous calcareous nannofossils at DSDP Hole 93-603B@en

Upper Berriasian to lower Aptian calcareous nannofossil assemblages have been studied from a siliciclastic deep-sea fan complex and a subjacent limestone sequence drilled beneath the lower continental rise in the western North American Basin, 270 miles (435 km) off Cape Hatteras, North Carolina (USA). Sharp lithologic facies changes and reworking by turbidites complicate the biostratigraphic interpretation, but provide an excellent opportunity to better distinguish \"nearshore\" from open-ocean nannofossil species, and to investigate the introduction of neritic taxa into the deep-see environment, a phenomenon that appears to have been widespread within the circum-North Atlantic during Neocomian times. Well-preserved assemblages in dark, carbonaceous claystones were probably displaced from the oxygen minimum zone along the upper slope or outer shelf. Neritic, continental margin species prevalent in this facies include the holococcolith Zebrashapka vanhintei n. gen., n. sp., Lithraphidites alatus magnus n. spp., Pickelhaube furtiva n. gen., and a host of nannoconids and micrantholiths. […]本次研究针对美国北卡罗来纳州哈特勒斯角外海270英里（435千米）处的北美西部盆地下大陆隆之下所钻取的硅质碎屑深海扇复合体（siliciclastic deep-sea fan complex）与下伏石灰岩序列（subjacent limestone sequence），对其中贝利阿斯阶上部（Upper Berriasian）至阿普第阶早期（lower Aptian）的钙质超微化石（calcareous nannofossil）组合展开了系统分析。浊积岩（turbidites）引发的显著岩相变化与再沉积作用，虽使生物地层解译（biostratigraphic interpretation）工作面临诸多复杂情况，但也为精准区分近岸（nearshore）与远洋钙质超微化石物种，以及探究浅海分类群（neritic taxa）向深海环境的输入现象提供了绝佳契机——该现象在早白垩世凡兰吟期（Neocomian）的北大西洋周缘（circum-North Atlantic）区域曾广泛分布。暗色碳质黏土岩中保存完好的化石组合，大概率是从陆坡上部或外陆架的低氧层（oxygen minimum zone）经搬运而来。该岩相中的优势浅海、大陆边缘类群涵盖全颗石藻（holococcolith）类的新属Zebrashapka、新种vanhintei（n. gen., n. sp.），新亚种Lithraphidites alatus magnus（n. spp.），新属Pickelhaube、新种furtiva（n. gen.），以及大量球石藻类（nannoconids）和微颗石类（micrantholiths）。[…]