Early Cretaceous lignites from inner-continental Asia as paleoclimate archive

关于早白垩纪温室期古亚洲大陆内部气候和环境条件的记录是稀疏的、零碎的，而且常常是相互矛盾的。对于阿普提安-阿尔比安区间，一组由代用的大陆古温度估算结果显示平均气温相对较低，这与从海洋领域获得的异常温暖的海面温度形成对比。蒙古中部的大陆唱诗班-尼亚尔加盆地含有厚厚的、富含褐煤的演替层，拥有保存异常完好的针叶树为主的植物群，代表了中纬度湿地生态系统。本研究计划将基于brgdgt的古温学、煤岩学和孢粉学分析相结合，对这些褐煤矿床进行研究。调查将集中在三个露天褐煤矿的材料和之前野外考察中研究和取样的钻芯。初步的有机地球化学和孢粉学结果表明，低成熟煤与碎屑互层非常适合该方法。将陆相碳同位素地层学、孢粉地层学与凝灰岩层位放射性U/Pb年代学相结合，改进现有的时间框架。该项目将提供新的、重要的古温度和古植被数据，这将有助于更好地约束全球异常变暖时期大陆内部的气候和生态系统动态。

Records documenting the climatic and environmental conditions prevailing in inner-continental paleo-Asia during the Early Cretaceous greenhouse phase are sparse, fragmentary and often contradictory. For the Aptian-Albian interval, a small set of proxy-derived continental paleotemperature estimates shows comparatively cool mean air temperatures, which contrast with exceptionally warm sea-surface temperatures obtained from the marine realm. The continental Choir-Nyalga Basin of central Mongolia contains thick, lignite-rich successions, which host an exceptionally well-preserved conifer-dominated flora representing a mid-latitude wetland ecosystem. This research proposal aims at studying these lignite-bearing deposits by combining brGDGT-based paleothermometry and coal petrology with palynological analyses. Investigations will focus on material from three open-cast lignite mines and a drill core studied and sampled during a previous field expedition. Preliminary organic geochemical and palynological results demonstrate that the low-mature coals and clastic interbeds are well suited for the chosen approach. The existing temporal framework will be improved by combining terrestrial carbon-isotope stratigraphy and palynostratigraphy with radiometric U/Pb chronology from tuffaceous horizons. The project will deliver new and important paleotemperature and paleovegetation data, which will help to better constrain the climate and ecosystem dynamics of continental interiors during times of exceptional global warmth.