Insights into terrestrial climate conditions of the high-latitude Southern Hemisphere during the Eocene greenhouse world: An integrated palynological and organic geochemical approach

在第一个项目阶段，我们研究了IODP站点U1156(南极洲威尔克斯岛)下至中始新世的陆生孢粉(花粉和孢子)。这导致：(1)认识到早期始新世在Wilkes陆地沿海地区盛行的热带热带雨林生物群，包括棕榈林和棕榈亚科；(2)首次对南极从始新世温室高峰期到始新世中期变冷的气候进行了定量的、季节性的重建。我们的孢粉学和MBT/CBT古测温数据的整合产生了内部一致的图景。年平均气温可能高达20摄氏度；值得注意的是，冬天非常温和(&gt；10摄氏度)，而且没有霜冻。虽然第一个项目阶段提供了对南极洲从新生代最热到始新世中期冷却的陆地气候和环境条件的新见解，但我们建议在最后一个项目年，使用相同的方法重建从古新世最冷的时期到始新世早期温室条件(约60至54 MYR)的南极洲陆地气候和环境。我们建议将ODP1172站作为研究点，该站位于古近纪时位于古纬度65°S的塔斯马尼亚高原上。1172D孔具有良好的年代地层年龄控制，前人对藻囊的研究表明，其序列显示出相对较高的孢子体丰度。最重要的是，由于地表水水流的配置，陆地孢粉的来源区域可以被限制为主要代表来自南极洲东部的高纬度信号。该项目将为南极洲从古近纪温室世界的崛起到黎明的第一次定量气候重建。

During the first project phase, we have studied terrestrial palynomorphs (pollen and spores) from the Lower to Middle Eocene of IODP Site U1156 (Wilkes Land, Antarctica). This has resulted in (i) the recognition of a paratropical rainforest biome including palms and Bombacoideae that prevailed in the coastal region of Wilkes Land during the early Eocene; and (ii) the first quantitative, seasonally resolved climate reconstructions for Antarctica from peak Eocene greenhouse conditions to mid-Eocene cooling. The integration of our palynological and MBT/CBT paleothermometry data yields an internally consistent picture. Mean annual temperatures may have been as high as 20°C; notably, winters were extremely mild (>10°C) and frost-free. While the first project phase has provided new insights into the terrestrial climate and environmental conditions on Antarctica from peak Cenozoic warmth to mid-Eocene cooling, we propose for the final project year to focus on the reconstruction of terrestrial climate and environments on Antarctica from the coolest interval of the Paleocene into the peak of early Eocene greenhouse conditions (~60 to ~54 myr) using the same methodologies. As study site, we propose ODP Site 1172, located on the Tasmanian Plateau at a paleolatitude of 65°S during the Paleogene. Hole 1172D has excellent chronostratigraphic age control, and previous work on dinocysts has shown that its succession exhibits a relatively high abundance of sporomorphs. Most importantly, due to the configuration of surface-water currents, the source area of terrestrial palynomorphs can be constrained to predominantly represent a high-latitude signal from East Antarctica. The project will yield the first quantitative climate reconstructions for Antarctica from the rise into the dawn of the Paleogene greenhouse world.