Diversity and faunal composition of benthic foraminifera in Hole 44-390A on the Blake Nose Plateau

Benthic foraminiferal assemblages are a widespread tool to understand changes in organic matter flux and bottom-water oxygenation and their relation to paleoceanographic changes in the Upper Cretaceous oceans. In this study, assemblage data (diversity, total number, and number per species and gram) from Deep Sea Drilling Project (DSDP) Site 390 (Blake Nose, western North Atlantic) were processed for the lower Maastrichtian (Globotruncana falsostuarti – Gansserina gansseri Planktic Foraminiferal Zone). These data document significant changes in nutrient flux to the sea floor as well as bottom-water oxygenation during this time interval. Parallel to the observed changes in the benthic foraminiferal assemblages the number of inoceramid shells decreases, reflecting also a significant increase in bottom-water oxygenation. We speculate, that these data could reflect the onset of a shift from warmer low-latitude to cooler high-latitude deep-water sources. […]

底栖有孔虫群集是理解有机物质通量变化、底部水体氧合作用及其与白垩纪晚期海洋古海洋学变化的相互关系的一种广泛使用的工具。在本研究中，针对深海钻探计划（DSDP）390号站位（布莱克鼻，北大西洋西部）的群集数据（包括多样性、总数以及每个物种和每克的数量），对下玛斯特里赫特阶（Globotruncana falsostuarti – Gansserina gansseri浮游有孔虫带）进行了处理。这些数据记录了该时间段内向海底的营养物质通量以及底部水体氧合作用的显著变化。与底栖有孔虫群集的观察到的变化并行，环生贝类壳的数量减少，这也反映了底部水体氧合作用的显著增加。我们推测，这些数据可能反映了从较温暖的低纬度到较寒冷的高纬度深水来源的转变的起始。