Southern high-latitude terrestrial climate change during the Palaeocene-Eocene derived from a marine pollen record (ODP Site 1172, East Tasman Plateau)
Southern high-latitude terrestrial climate change during the Palaeocene-Eocene derived from a marine pollen record (ODP Site 1172, East Tasman Plateau)
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DOI：
10.5194/cp-10-1401-2014
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发表时间：
2014-07
影响因子：
4.3
通讯作者：
Lineth Contreras;J. Pross;P. Bijl;R. O’Hara;J. Raine;A. Sluijs;H. Brinkhuis
中科院分区：
文献类型：
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作者：
Lineth Contreras;J. Pross;P. Bijl;R. O’Hara;J. Raine;A. Sluijs;H. Brinkhuis
抽象的。重建南高纬度陆地环境的早期古近纪气候动态对于评估高纬度物理和生物地球化学过程在全球气候系统中的作用非常重要。然而，尽管近年来南方高纬度海洋领域已经获得了许多高质量的古近纪气候记录，但同时期陆地气候和生态系统的长期演变却知之甚少。我们根据东塔斯曼高原海洋钻探计划 (ODP) 站点 1172 的孢子形态记录，探索塔斯马尼亚从古新世中期到始新世早期（60.7–54.2 Ma）的气候和植被动态。我们的研究结果表明，在古新世中期至始新世早期的高降水条件下，塔斯马尼亚岛生长着三种截然不同的植被类型，每种类型代表不同的温度条件：（i）以裸子植物为主的暖温带森林，在古新世中晚期（不包括古新世中晚期过渡时期）占主导地位； (ii) 以南山毛榉 (Nothofagus) 和南洋杉为主的冷温带森林，在中/晚古新世过渡期（约 59.5 至约 59.0 Ma）短暂盛行； (iii) 富含蕨类植物的副热带森林，是在古新世-始新世极热期 (PETM) 期间和之后形成的。在古新世中/晚期过渡时期，缺乏任何霜冻敏感元素（即棕榈树和苏铁树）的冷温带森林的短暂建立表明塔斯马尼亚在此期间的气候明显凉爽，冬季出现霜冻。我们的孢子形态数据与之前发布的来自 ODP Site 1172 的基于 TEX86 的海面温度相结合，证明塔斯马尼亚的植被动态与西南太平洋地区塔斯曼地区的温度演变密切相关。此外，我们对 ODP 站点 1172 的孢子体组合的季节特定气候估计与基于 TEX86L 和 TEX86H 的温度数据进行比较表明，这两种校准对于南高纬度古近纪早期都有温暖的偏差。
Abstract. Reconstructing the early Palaeogene climate dynamics of terrestrial settings in the high southern latitudes is important to assess the role of high-latitude physical and biogeochemical processes in the global climate system. However, whereas a number of high-quality Palaeogene climate records has become available for the marine realm of the high southern latitudes over the recent past, the long-term evolution of coeval terrestrial climates and ecosystems is yet poorly known. We here explore the climate and vegetation dynamics on Tasmania from the middle Palaeocene to the early Eocene (60.7–54.2 Ma) based on a sporomorph record from Ocean Drilling Program (ODP) Site 1172 on the East Tasman Plateau. Our results show that three distinctly different vegetation types thrived on Tasmania under a high-precipitation regime during the middle Palaeocene to early Eocene, with each type representing different temperature conditions: (i) warm-temperate forests dominated by gymnosperms that were dominant during the middle and late Palaeocene (excluding the middle/late Palaeocene transition); (ii) cool-temperate forests dominated by southern beech (Nothofagus) and araucarians that transiently prevailed across the middle/late Palaeocene transition interval (~ 59.5 to ~ 59.0 Ma); and (iii) paratropical forests rich in ferns that were established during and in the wake of the Palaeocene–Eocene Thermal Maximum (PETM). The transient establishment of cool-temperate forests lacking any frost-sensitive elements (i.e. palms and cycads) across the middle/late Palaeocene transition interval indicates markedly cooler conditions, with the occurrence of frosts in winter, on Tasmania during that time. The integration of our sporomorph data with previously published TEX86-based sea-surface temperatures from ODP Site 1172 documents that the vegetation dynamics on Tasmania were closely linked with the temperature evolution in the Tasman sector of the Southwest Pacific region. Moreover, the comparison of our season-specific climate estimates for the sporomorph assemblages from ODP Site 1172 with the TEX86L- and TEX86H-based temperature data suggests a warm bias of both calibrations for the early Palaeogene of the high southern latitudes.