Palynology analyses of Eocene to Oligocene sediments of DSDP Hole 38-338@en

Against the background of the profound global climatic shift from greenhouse to icehouse conditions during the Eocene–Oligocene transition, major geographic and oceanographic changes were taking place in the Norwegian–Greenland Sea region. The Vøring Plateau was a prominent structural feature which influenced the evolution of water mass circulation in the Nordic seas, and we present detailed palaeoenvironmental reconstructions of this structure. New palynological results suggest that shallow water inner-neritic environments were developed across parts of the Vøring Plateau during early Eocene times, with terrestrial and brackish water palynomorphs indicating that both basement highs to the north, and the crestal part of the Vøring Escarpment, may have been emergent. A transition from marginal-marine to open marine conditions occurred around 44 Ma ago, with the complete subsidence of the Vøring Plateau below sea level, facilitating inter-basinal surface water circulation and promoted a significant increase in photic zone fertility. Carbon sequestration associated with such enhanced productivity in the late Eocene Nordic seas may have contributed to declining Cenozoic atmospheric carbon dioxide levels, thence to declining global temperatures and the development of limited Northern Hemisphere continental ice on Greenland in the latest Eocene.在始新世-渐新世过渡期全球气候由温室状态向冰室状态发生深刻转变的背景下，挪威-格陵兰海域正经历着重大的地理与海洋学变革。沃林高原（Vøring Plateau）作为一处显著的构造特征，对北欧海域的水团环流演化产生了重要影响，本研究针对该构造开展了详细的古环境重建工作。新的孢粉学研究结果显示，始新世早期，沃林高原部分区域发育了内浅海环境；陆生与半咸水孢粉化石表明，其北侧的基底隆起带以及沃林陡崖（Vøring Escarpment）的顶部区域均可能曾出露于水面之上。约44 Ma（百万年）前，该区域发生了从边缘海向开阔海环境的转变，沃林高原完全沉降至海平面以下，这促进了盆地间表层水的环流，并大幅提升了透光带的生物生产力。晚始新世北欧海域中，与这种生产力提升相关的碳固存作用，可能推动了新生代大气二氧化碳浓度持续下降，进而导致全球气温降低，并在始新世最晚期于格陵兰地区形成了有限的北半球大陆冰盖。