SGER: A Novel Paleoaltimetry Proxy: Calibration of Plant Biomarker Delta-D (dD) Values

SGER：一种新型古测法代理：植物生物标志物 Delta-D (dD) 值的校准

• 批准号: 0741400
• 负责人: Katherine Freeman
• 金额: --
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-15 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0741400&HistoricalAwards=false
• 关键词: SGER; Novel; Paleoaltimetry; Proxy; Calibration

This exploratory project aims to calibrate a new paleoaltimeter based upon the hydrogen isotope ratios of plant biomarkers. These ratios enable reconstruction of the isotopic signatures of paleoprecipitation, from which paleoelevations are inferred using a physically based isotope-elevation model. This approach is rooted in the systematic relationship between the hydrogen isotope composition of molecules that comprise the epicuticular waxy coating on plant leaves and the isotopic composition of precipitation. An evaluation of this new method is being carried out using plant-wax n-alkanes extracted from North American and Andean montane lakes representing a range of plant communities, hydrology and altitude. The modern lake sediments offer an ideal analog for the ancient lake environments often used for paleoaltimetry. Comparison of reconstructed precipitation hydrogen isotope ratios and elevation estimates with actual lake elevation and local precipitation composition will provide a powerful and direct means to evaluate hydrogen isotope ratios of plant-wax biomarkers as paleoelevation proxies. The role of plant physiology is being assessed by measuring the plant-wax hydrogen isotope composition in leaves roots and soils from monospecific stands of six different tree species, representing dominant Cenozoic taxa, grown under identical climate and water sources at the Siemianice Experimental Forest in Poland. These measurements allow evaluation of species-dependent differences in transpiration and isotopic fractionation accompanying plant-wax synthesis. Investigation of this new technique with modern samples is necessary before its widespread application as a paleoaltimeter.Paleoelevation is a key variable in tectonics and climate research. Observation-based estimates provide a benchmark to compare with models of mountain formation and help constrain the complex interactions driving uplift, denudation and climate. A plant-wax hydrogen isotope ratio paleoaltimeter will broaden the types of samples amenable to paleoaltimetry while pioneering an interdisciplinary and novel application of biogeochemical tools to the study of tectonic systems. This research also indirectly addresses the challenges of discerning climate histories in the terrestrial environment, and has potential to offer insights to the consequences of human-induced changes in climate, terrestrial hydrology and the physical landscape.

该探索性项目旨在根据植物生物标志物的氢同位素比率校准新型古高度计。这些比率能够重建古降水的同位素特征，并使用基于物理的同位素高程模型推断古海拔。这种方法植根于构成植物叶子表皮蜡质涂层的分子的氢同位素组成与降水同位素组成之间的系统关系。正在使用从代表一系列植物群落、水文和海拔的北美和安第斯山脉湖泊中提取的植物蜡正烷烃对这种新方法进行评估。现代湖泊沉积物为常用于古海拔测量的古代湖泊环境提供了理想的模拟。将重建的降水氢同位素比和海拔估计值与实际湖泊海拔和当地降水成分进行比较，将为评估作为古海拔代理的植物蜡生物标志物的氢同位素比提供强大而直接的方法。植物生理学的作用正在通过测量六种不同树种的单特异性林中的叶根和土壤中的植物蜡氢同位素组成来评估，这些树种代表了主要的新生代类群，在波兰谢米亚尼采实验森林的相同气候和水源下生长。这些测量可以评估植物蜡合成过程中蒸腾作用和同位素分馏的物种依赖性差异。在将这项新技术作为古高度计广泛应用之前，有必要用现代样本对其进行研究。古海拔是构造学和气候研究中的一个关键变量。基于观测的估计提供了与山脉形成模型进行比较的基准，并有助于限制驱动隆起、剥蚀和气候的复杂相互作用。植物蜡氢同位素比古高度计将拓宽适合古高度测量的样品类型，同时开创了生物地球化学工具在构造系统研究中的跨学科和新颖应用。这项研究还间接解决了辨别陆地环境气候历史的挑战，并有可能为人类引起的气候、陆地水文和自然景观变化的后果提供见解。