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

在项目的第一阶段，我们研究了IODP站点U1156（威尔克斯地，南极洲）的下至中始新世的陆生孢粉（花粉和孢子）。这导致了（i）确认了始新世早期在威尔克斯地沿海地区盛行的包括棕榈树和木棉科在内的一个热带雨林生物群落;（ii）首次定量、季节性地重建了南极洲从始新世温室条件峰值到始新世中期冷却的气候。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片。年平均气温可能高达20°C;值得注意的是，冬季非常温和（>10°C），无霜。虽然第一个项目阶段提供了新的见解南极洲的陆地气候和环境条件，从新生代温暖的高峰到始新世中期冷却，我们建议在最后一个项目年侧重于重建南极洲的陆地气候和环境，从古新世最冷的间隔到始新世早期温室条件的高峰（~60至~54百万年）使用相同的方法。作为研究地点，我们建议ODP站点1172，位于塔斯马尼亚高原上的古纬度为65°S的古第三纪。孔1172 D有很好的年代地层年龄控制，和以前的工作，对dinocytes已经表明，其继承表现出相对较高的丰度的孢子。最重要的是，由于表面水流的配置，陆地palynomorphs的源区可以被限制为主要代表来自东南极洲的高纬度信号。该项目将产生第一个定量气候重建南极洲从上升到黎明的古近纪温室世界。

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.