Lake deposits as high-resolution archives of mid-Cretaceous equatorial climate variability: A combined approach including organic geochemistry and palynology

湖泊沉积物作为白垩纪中期赤道气候变化的高分辨率档案：有机地球化学和孢粉学的综合方法

• 批准号: 5428201
• 负责人: Professor Dr. Ulrich Heimhofer
• 金额: --
• 依托单位: Institut für Geologie
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2005-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5428201?language=en
• 关键词: Lake; deposits; resolution; archives; mid

The Cretaceous thermal maximum (KTM; Albian to Turonian) represents one of the best studied examples of greenhouse conditions in the geological record. The previously held view of an equable and stable mid-Cretaceous climate during this time of exceptional warmth is questioned by the occurrence of several short-term climatic perturbations (e.g. black shale events). Detailed information on Cretaceous climate fluctutations are mainly based on ¿ 18O studies from marine records of limited temporal resolution. This project will focus on continental lacustrine deposits (Araripe Basin, NE Brazil) to study equatorial climate variability during the onset of the KTM (Late Aptian to Albian) on a previously unobtained resolution. The existing biostratigraphic framework of the lacustrine succession will be refined by the use of chemostratigraphy based on ¿ 13C of land plant-derived biomarkers (long-chain n-alkanes) and fossil wood. Sequence-stratigraphic and palynofacies analysis of the lake deposits will provide detailed information on lake-level fluctuations. Additional information on changes in evaporation/precipitation and run-off patterns will be obtained from proxy data derived by organic and inorganic geochemical analyses (incl. C/N ration, Rock Eval, ¿ 13Corg, XRF scanning). The response of vegetation patterns to short- and long-term climate variability will be assessed by combining palynology and analyses of different land plant biomarkers. The proposed project will not only provide data on mid-Cretaceous environmental change on a unique resolution, it furthermore will significantly contribute to resolve the issue of the stability of warm climates.

白垩纪最高温度(KTM；阿尔比安至图罗尼亚)代表了地质记录中对温室条件研究最好的例子之一。之前关于白垩纪中期气候在这段异常温暖的时期保持稳定的观点受到了几次短期气候扰动(例如黑色页岩事件)的质疑。关于白垩纪气候波动的详细信息主要基于对时间分辨率有限的海洋记录的研究。该项目将侧重于陆相湖泊沉积(巴西东北部的Araripe盆地)，以研究KTM(阿普提亚晚期至阿尔比安)开始期间的赤道气候变异性，这是一个以前未获得的分辨率。现有的湖相序列生物地层学框架将通过使用基于陆地植物衍生生物标志物(长链正构烷烃)和化石木材的13C的化学地层学来精炼。湖泊沉积的层序地层学和孢粉相分析将提供有关湖泊水位波动的详细信息。关于蒸发/降水和径流模式变化的其他信息将从有机和无机地球化学分析(包括。C/N比、岩屑、13Corg、XRF扫描)。将结合孢粉学和对不同陆地植物生物标志物的分析，评估植被模式对短期和长期气候变化的反应。拟议的项目不仅将提供关于白垩纪中期环境变化的独特解决方案的数据，而且还将大大有助于解决温暖气候的稳定性问题。