(Table 1) Upper Carboniferous spores abundances from ODP Holes 172-1062B, 172-1063A and 172-1063B

Color variations were interpreted in paleoceanographic terms for the late Pliocene-Pleistocene sediments recovered by ODP Leg 172 on deep-sea drifts at Blake-Bahama Outer Ridge and northeastern Bermuda Rise. The color-derived parameters used in interpretation included predicted carbonate content, terrigenous fluxes, and hematite content. Abundance of Upper Carboniferous spores indicates that the hematite is probably derived from the Permo-Carboniferous red beds of the Canadian Maritimes. In the last 800 kyr sedimentation pattern changes on the Blake-Bahama Outer Ridge were determined by the sediment delivery to the deep basin as well as circulation changes. Sediment delivery increased during glacials (especially during the last 500 kyr and particularly since Stage 6). A fundamental change in the thermohaline circulation occurred at about 500 ka corresponding to the end of the Mid-Pleistocene Transition period at the onset of the predominant 100-kyr climate cyclicity. Sedimentation related to WBUC had intensified at that time and had become more focused at depths below 3000 m. Changes in hematite content and sedimentation rate show a pulse of sediment via the St. Lawrence outlet at the Pliocene-Pleistocene boundary suggesting that a likely change in the hydrography/physiography of the Laurentide Ice Sheet could have been involved in the climatic and ocean circulation changes at that time.针对大洋钻探计划（Ocean Drilling Program, ODP）第172航次于布莱克-巴哈马外海脊及百慕大隆起东北部深海漂移沉积体中获取的上新世晚期-更新世沉积物，研究人员以古海洋学视角对其颜色变化特征展开解读。本次解读所采用的颜色衍生参数包括预测碳酸盐含量、陆源通量及赤铁矿含量。晚石炭世孢子的丰度指示，研究区的赤铁矿可能源自加拿大大西洋沿岸省份的二叠-石炭纪红层。过去80万年中，布莱克-巴哈马外海脊的沉积模式变化由向深盆的沉积物输送与海洋环流变化共同决定。冰期时段沉积物输送量有所提升，尤其在过去50万年，且自氧同位素第6期以来尤为显著。约500 ka时温盐环流发生根本性转变，这对应着中更新世过渡期的结束，以及主导性10万年气候旋回的开启。彼时与西边界下伏流（Western Boundary Undercurrent, WBUC）相关的沉积作用显著增强，且更集中于3000米以深的海域。赤铁矿含量与沉积速率的变化显示，在上新世-更新世边界时期存在通过圣劳伦斯河出口的沉积物脉冲事件，这表明劳伦泰德冰盖的水文状况与地貌格局可能发生了改变，进而参与了当时的气候与海洋环流演变过程。