Age models of ODP sites from the Barents Sea-Svalbard region@en

Based on a revised chronostratigraphy, and compilation of borehole data from the Barents Sea continental margin, a coherent glaciation model is proposed for the Barents Sea ice sheet over the past 3.5 million years (Ma). Three phases of ice growth are suggested: (1) The initial build-up phase, covering mountainous regions and reaching the coastline/shelf edge in the northern Barents Sea during short-term glacial intensification, is concomitant with the onset of the Northern Hemisphere Glaciation (3.6-2.4 Ma). (2) A transitional growth phase (2.4-1.0 Ma), during which the ice sheet expanded towards the southern Barents Sea and reached the northwestern Kara Sea. This is inferred from step-wise decrease of Siberian river-supplied smectite-rich sediments, likely caused by ice sheet blockade and possibly reduced sea ice formation in the Kara Sea as well as glacigenic wedge growth along the northwestern Barents Sea margin hampering entrainment and transport of sea ice sediments to the Arctic-Atlantic gateway. (3) Finally, large-scale glaciation in the Barents Sea occurred after 1 Ma with repeated advances to the shelf edge. The timing is inferred from ice grounding on the Yermak Plateau at about 0.95 Ma, and higher frequencies of gravity-driven mass movements along the western Barents Sea margin associated with expansive glacial growth.本研究基于经修订的年代地层学（chronostratigraphy）以及巴伦支海大陆边缘钻孔数据的汇编，针对过去350万年（Ma）的巴伦支海冰盖提出了一套连贯统一的冰川作用模型。研究提出了三期冰体增长过程：（1）初始冰体构建阶段：该阶段与北半球冰川作用（Northern Hemisphere Glaciation）的启动时段（3.6~2.4 Ma）同步发生，在短期冰川强化过程中，冰体率先覆盖山区，最终延伸至巴伦支海北部的海岸线与陆架边缘。（2）过渡增长阶段（2.4~1.0 Ma）：此阶段冰盖向巴伦支海南部扩张，并抵达喀拉海西北部。该推论依据为：西伯利亚河流输入的富蒙脱石（smectite）沉积物呈阶梯式衰减，这大概率由冰体阻滞作用所致，同时喀拉海的海冰形成作用可能有所减弱，加之巴伦支海西北部陆缘的冰成楔体（glacigenic wedge）发育，阻碍了海冰沉积物被裹挟并输送至北极-大西洋通道。（3）大规模冰川作用阶段：巴伦支海在1 Ma之后进入该阶段，冰体多次向陆架边缘推进。该时期的判定依据为：约0.95 Ma时耶马克高原（Yermak Plateau）出现冰体固着锚定现象，且巴伦支海西部陆缘伴随大规模冰川增长，出现了频率更高的重力驱动型块体运动（gravity-driven mass movements）。