Abstract Fossil-bearing deposits in the Transantarctic Mountains, Antarctica indicate that, despite the cold nature of the continent’s climate, a tundra ecosystem grew during periods of ice sheet retreat in the mid to late Neogene (17–2.5 Ma), 480 km from the South Pole. To date, palaeotemperature reconstruction has been based only on biological ranges, thereby calling for a geochemical approach to understanding continental climate and environment. There is contradictory evidence in the fossil record as to whether this flora was mixed angiosperm-conifer vegetation, or whether by this point conifers had disappeared from the continent. In order to address these questions, we have analysed, for the first time in sediments of this age, plant and bacterial biomarkers in terrestrial sediments from the Transantarctic Mountains to reconstruct past temperature and vegetation during a period of East Antarctic Ice Sheet retreat. From tetraether lipids (MBT′/CBT palaeothermometer), we conclude that the mean continental summer temperature was ca. 5 °C, in agreement with previous reconstructions. This was warm enough to have allowed woody vegetation to survive and reproduce even during the austral winter. Biomarkers from vascular plants indicate a low diversity and spatially variable flora consisting of higher plants, moss and algal mats growing in microenvironments in a glacial outwash system. Abietane-type compounds were abundant in some samples, indicating that conifers, most likely Podocarpaceae, grew on the Antarctic continent well into the Neogene. This is supported by the palynological record, but not the macrofossil record for the continent, and has implications for the evolution of vegetation on Antarctica.

中文翻译：

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南极洲最后的森林：重建跨南极山脉新近纪天狼星群的植物群和温度

摘要 南极洲横贯南极山脉的含化石沉积物表明，尽管该大陆气候寒冷，但在新近纪中晚期（17-2.5 Ma）的冰盖退缩时期，苔原生态系统生长，距地球 480 公里。南极。迄今为止，古温度重建仅基于生物范围，因此需要一种地球化学方法来了解大陆气候和环境。关于这种植物群是否是被子植物与针叶树的混合植被，或者针叶树是否已经从大陆上消失，化石记录中存在矛盾的证据。为了解决这些问题，我们首次分析了这个时代的沉积物，来自横贯南极山脉的陆地沉积物中的植物和细菌生物标志物，以重建南极东部冰盖退缩期间过去的温度和植被。从四醚脂质（MBT'/CBT 古温度计），我们得出结论，大陆夏季平均温度约为 5 °C，与以前的重建一致。这足以使木质植被即使在南方冬季也能生存和繁殖。维管植物的生物标志物表明，低多样性和空间可变的植物群由生长在冰川外冲系统微环境中的高等植物、苔藓和藻垫组成。一些样品中含有大量松香烷类化合物，这表明针叶树，最有可能是罗汉松科，在南极大陆生长到新近纪。