The Northern Transpolar Gateways

在第三阶段，主题B1计划将其重点扩大到北欧海和副极地北太平洋之间的北方跨极门户连接。这个海道系统只在罕见和短暂的上新世/更新世高峰间冰期与极端海平面高水位，当白令海峡，今天45米深，被淹没。将讨论两个主要目标：（1）目前从北太平洋流入北极和北大西洋的密度驱动的地表水流动的潜在逆转，以限制对全球温盐环流和气候稳定性的可能影响。这一目标将需要通过激光烧蚀技术获得新质量的稳定同位素和痕量金属数据，以重建过去海面分层的变化。(2)南极有孔虫物种的跨极交换，这在理论上是可能的，但肯定是罕见的，更重要的是，不同N.厚皮病(Nps)隐种的两侧的北冰洋，重建的形态测量记录的NPS和它的血统，为过去3万年。(3)此外，新建立的<$44/40 Ca为基础的SST代理单Nps壳现在将被用来限制古SST变化的丹麦海峡两岸在寒冷的Dansgaard-Oeschger stadials，并建立古温度记录选定的晚上新世冰期和间冰期阶段，需要精确重建的古密度梯度。

During Phase 3 Theme B1 is planning to expand its focus to the northern transpolar gateway connection between the Nordic Seas and the subpolar North Pacific. This seaway system was only open during rare and short-lasting Plio- / Pleistocene peak interglacials with extreme sealevel highstands, when the Bering Strait, today 45 m deep, was flooded. Two major objectives will be addressed: (1) Potential reversals in the density-driven flow of surface water today streaming from the North Pacific into the Arctic and North Atlantic, to constrain possible implications for the stability of global thermohaline circulation and climate. This target will require a new quality of stable-isotope and trace metal data obtained by laser ablation technique to reconstruct past variations in sea surface stratification. (2) The transpolar exchange of planktic foraminiferal species, which was possible by theory but certainly rare, and more important, the potential ¿race¿ in the evolution and extreme polar adaption of different N. pachyderma sin. (Nps) cryptospecies to both sides of the Arctic Sea, to be reconstructed by morphometric records of Nps and its lineages for the last 3 Myr. (3) In addition, the newly established ¿44/40Ca-based SST proxy of single Nps shells will now be employed to constrain paleo-SST variations to both sides of the Denmark Strait during cold Dansgaard-Oeschger stadials and to establish paleotemperature records for selected Late Pliocene glacial and interglacial stages, necessary for a precise reconstruction of paleodensity gradients.