Detailed analyses of benthic foraminiferal fauna and planktonic foraminiferal stable carbon isotopes at IODP Site U1391 were performed to reconstruct orbital-scale variability in primary productivity off the Portuguese margin over the last 1.3 Myr. Q-mode factor analysis of benthic foraminiferal census data from the >250 μm fraction reveals four assemblages, which is mainly controlled by the organic matter flux to the seafloor deriving from surface water productivity. The Sphaeroidina bulloides assemblage accounts for nearly half of the total variance, consisting of S. bulloides, the agglutinated taxa and Lenticulina as major components and Cibicidoides robertsonianus, Planulina ariminensis and Uvigerina peregrina parva as subsidiary species. Cibicidoides wuellerstorfi and Bulimina mexicana are important accessory species of the Cibicidoides pachyderma-dominated assemblage. The miliolids assemblage is dominated by miliolids and B. mexicana with Uvigerina mediterranea as the important associated species. The Praeglobobulimina ovata assemblage is represented by P. ovata along with Globobulimina affinis, Melonis pompiloides, Melonis barleeanum and U. peregrina parva as important accessory species. High productivity often occurs during the interglacial stages and is characterized by the S. bulloides assemblage with subsidiary P. ovata assemblage, while low productivity often occurs during the glacial stages and is marked by the miliolids assemblage and the C. pachyderma assemblage. In addition to the distinct glacial/interglacial variations, there is a long-term decreasing trend in primary productivity recorded by benthic foraminifera, which is supported by a broadly increasing trend in the sediment redness (a*). Continuous wavelet analysis of high productivity-related Factor 1 loading (the S. bulloides assemblage) suggests that variations in primary productivity have a middle Pleistocene transition (MPT)-related shift in cyclicity from the ~41-kyr dominant cycle prior to the MPT to the ~100-kyr dominant cycle after the MPT. Cross-spectral analyses between the Factor 1 loading record and δ¹⁸O of Globigerina bulloides reveal the control of global ice volume changes on primary productivity. The high coherency between the Factor 1 loading record and δ¹³C of G. bulloides on the glacial/interglacial timescale suggests that primary productivity off the Portuguese margin may be largely affected by nutrient availability which was related to the Iberian surface hydrographic changes associated with changes in global ice volume.

对 IODP 站点 U1391 的底栖有孔虫动物群和浮游有孔虫稳定碳同位素进行了详细分析，以重建过去 1.3 Myr 葡萄牙边缘初级生产力的轨道尺度变化。来自 >250 μm 部分的底栖有孔虫普查数据的 Q 模式因子分析揭示了四种组合，这主要受地表水生产力产生的进入海底的有机物质通量控制。该Sphaeroidina bulloides组合占了将近一半的总方差，由S. bulloides，凝集的类群和Lenticulina为主成分的Cibicidoides robertsonianus，Planulina ariminensis和Uvigerina peregrina parva作为附属物种。Cibicidoides wuellerstorfi和Bulimina mexicana是Cibicidoides pachyderma占优势的组合的重要附属物种。该miliolids组合由miliolids和主导B.墨西哥与Uvigerina地中海作为重要的相关品种。所述Praeglobobulimina ovata的组合由下式表示P.卵形连同Globobulimina affinis的，枯病pompiloides，枯病barleeanum和U.蝇麦穗鱼作为重要的附属物种。高生产力通常发生在间冰期，以S. Bulloides组合与附属P. ovata组合为特征，而低生产力通常发生在冰期，以 miliolids 组合和C. pachyderma组合为特征。除了明显的冰期/间冰期变化外，底栖有孔虫记录的初级生产力还存在长期下降趋势，这得到沉积物红色（a*）的广泛增加趋势的支持。与高生产力相关的因子 1 加载的连续小波分析（S. Bulloides组合）表明初级生产力的变化具有中更新世过渡（MPT）相关的周期性转变，从 MPT 之前的~41-kyr 主导周期到 MPT 之后的~100-kyr 主导周期。因子 1 加载记录和Globigerina billoides 的δ ¹⁸ O之间的交叉光谱分析揭示了全球冰量变化对初级生产力的控制。在冰川/间冰期时间尺度上，因子 1 加载记录与G. billoides 的δ ¹³ C之间的高度一致性表明，葡萄牙边缘的初级生产力可能在很大程度上受养分可用性的影响，养分供应与伊比利亚表面水文变化有关在全球冰量中。