(Table 1) Facies classification for ODP Site 174-1072@en

Commonly accepted models for the evolution of continental margins link sediment erosion, transport and deposition to eustasy. To test these models, we constructed an oxygen isotope record from 520 m of Pleistocene sediment recovered by the Ocean Drilling Program Leg 174A from the New Jersey continental slope. The delta18O record was calibrated to SPECMAP oxygen isotope time scale [Imbrie et al. (1984), in: Berger et al. (Eds.), Milankovitch and Climate, 269-305] with radiocarbon ages, nannoplankton biostratigraphy, magnetostratigraphy, and opal and calcium carbonate stratigraphy. Sixteen glacial/interglacial fluctuations of global ice volume have been recorded in the Pleistocene: oxygen isotope stages (OIS) 1 (partial), 2-4, 5 (partial) and 8 throughout 18. Contrary to predicted sedimentation models, a classification of mass-wasting deposits, based on variations in the styles of soft-sediment deformation and grain size, shows that: (1) mass-wasting is not restricted to glacial times but is present during both glacial and interglacial stages; (2) glacial stages are dominated by fine-grained sediments some of which were deposited by gravity flows; and (3) the transitions from glacial to interglacial stages are characterized by the deposition of coarse sands. The sedimentary record shows large-scale trends that do not fit the traditional models of higher glacial sedimentation rates since there is no consistent variation in sediment accumulation between glacial and interglacial stages. Instead there are longer-term sedimentation patterns. Uniform sedimentation rates of 62 cm/kyr characterize the early middle Pleistocene (OIS 12-18), followed by varying rates from low to very high for three consecutive time periods: OIS 11 to 9 (98-560 cm/kyr), OIS 8 (52-560 cm/kyr), and OIS 5 to 2 (37-353 cm/kyr). Each of these depositional units is contained within one seismic-stratigraphic sequence and bounded by sequence boundaries. Their deposition was influenced by the supply of sediment rather than eustasy. Sediment supply was modulated by: (1) the transition from the dominance of obliquity to that of eccentricity (OIS 18-12 to OIS 11-1); and (2) the proximity of the ice sheet (located not, vert, similar150 km away from the paleoshoreline during the last glacial maximum).当前学界公认的大陆边缘演化模型，均将沉积物侵蚀、搬运与沉积作用与全球海平面升降（eustasy）相联系。为验证上述模型，本研究基于大洋钻探计划（Ocean Drilling Program）174A航次于新泽西大陆斜坡钻取的520米更新世沉积物岩芯，建立了氧同位素序列。本研究通过放射性碳年代学、颗石藻生物地层学、磁性地层学以及蛋白石与碳酸钙地层学数据，将δ¹⁸O序列校准至SPECMAP氧同位素时间标尺[Imbrie等人，1984；收录于Berger等人主编《米兰科维奇与气候》，第269-305页]。更新世地层中已记录到16次全球冰量的冰期/间冰期旋回，对应氧同位素阶段（Oxygen Isotope Stages，OIS）1（部分段）、2-4、5（部分段）以及8至18阶段。与传统沉积模型的预测结果相悖，基于软沉积物变形样式与粒度变化划分的块体搬运沉积研究显示：（1）块体搬运作用并非仅局限于冰期，在冰期与间冰期阶段均有发育；（2）冰期阶段以细粒沉积物为主，其中部分沉积物由重力流沉积形成；（3）冰期向间冰期的过渡阶段以粗砂沉积为典型特征。本次研究的沉积记录呈现出与传统模型不符的大规模演化趋势：传统模型认为冰期沉积速率更高，但本研究中冰期与间冰期阶段的沉积物堆积量并无持续一致性差异，反而存在长期的沉积演化模式。中更新世早期（OIS 12-18）的沉积速率稳定在62厘米/千年，随后的三个连续时间段内沉积速率出现显著变化，跨度从极低到极高：OIS 11至9（98-560厘米/千年）、OIS 8（52-560厘米/千年）以及OIS 5至2（37-353厘米/千年）。上述每个沉积单元均赋存于一个地震地层序列内部，并以层序界面为边界。这些沉积单元的沉积作用主要受沉积物供给量控制，而非全球海平面升降。沉积物供给量受两大因素调控：（1）地球轨道参数主导周期从黄赤交角转向偏心率（对应OIS 18-12至OIS 11-1阶段）；（2）冰盖的空间展布（末次冰盛期时，冰盖距古岸线约150公里）。