(Figure 4) Stratigraphic distribution of planktonic foraminifera in DSDP Hole 93-604

During Deep Sea Drilling Project Leg 93, upper Miocene through Quaternary sediments were continuously cored in Hole 604, located on the upper continental rise of the New Jersey transect (western North Atlantic). A detailed biostratigraphic study of these strata has been made using the vertical distribution of planktonic foraminifers. The Quaternary climatic zonation of Ericson and Wollin (1968) has been tentatively delineated and all the Pliocene zones and subzones (sensu Berggren, 1977) have been recognized. The rate of sedimentation was slow during most of the Pliocene but underwent a significant acceleration in the early Pleistocene. Quantitative variations in the distribution of planktonic foraminifers appear to be influenced by various factors, such as hydrodynamic winnowing resulting from the action of bottom currents and surficial thermal conditions caused by climatic changes. Both dissolution intervals and brief increases in the coarser detrital input seem, most of the time, to be correlated with indications of climatic cooling and may correspond to glacial events or cycles. This chapter delineates a precursor stage in the inception of Northern Hemisphere glaciation at 3 Ma and wide-scale Quaternary glacial-interglacial cycles.
Data from a detailed study of Hole 604 are briefly compared with the main sedimentary and microfaunal features of contemporaneous series previously drilled along the east American margin in the northwestern Atlantic. One of the striking observations appears to be the intense redistribution of sediments that affected this region in Neogene-Quaternary times.

在深海钻探计划（Deep Sea Drilling Project）第93航次期间，位于新泽西断面（西北大西洋）大陆隆上部的604号钻孔连续获取了从晚中新世至第四纪的沉积岩心。研究人员依托浮游有孔虫（planktonic foraminifers）的垂直分布特征，对这套地层开展了详细的生物地层学研究。埃里克松与沃林（1968）提出的第四纪气候分带方案已被初步厘定，且所有按照伯格伦（1977）定义的上新世带及亚带均已被识别。上新世大部分时期的沉积速率较为缓慢，但在早更新世出现了显著增速。浮游有孔虫分布的数量变化似乎受多种因素调控，包括底流作用引发的流体动力分选作用，以及气候变化驱动的表层热环境变化。多数情况下，溶解层与粗碎屑输入的短暂增加均与气候变冷的信号相关，可能对应冰期事件或冰期旋回。本章阐明了北半球冰川作用于3 Ma起始的前驱阶段，以及大规模第四纪冰期-间冰期旋回的演化过程。
本次针对604号钻孔的详细研究所得数据，与此前在西北大西洋美洲东缘钻取的同期沉积序列的主要沉积学及微古生物特征进行了简要对比。其中一项引人注目的观测结果是，新近纪-第四纪时期该区域经历了强烈的沉积物再分配作用。