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

这一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一种新的古高度计。这些比率能够重建古沉淀的同位素特征，并使用基于物理的同位素-海拔模型来推断古海拔。这种方法植根于组成植物叶片表层蜡质涂层的分子的氢同位素组成与降水的同位素组成之间的系统关系。正在使用从北美和安第斯山地湖泊中提取的植物蜡正构烷烃对这一新方法进行评估，这些正烷烃代表了一系列植物群落、水文和海拔。现代湖泊沉积物为通常用于古高程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值和海拔估算值与湖泊实际海拔和当地降水组成进行比较，将为评价植物蜡生物标志物作为古海拔代用的氢同位素比值提供有力和直接的手段。正在通过测量六个不同树种的单一树种的叶、根和土壤中的植物蜡氢同位素组成来评估植物生理学的作用，这些树种代表了波兰西米亚尼斯实验森林在相同气候和水源下生长的主要新生代分类群。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差异。在作为古高度计广泛应用之前，用现代样品对这项新技术进行研究是必要的。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一个基准，用于与山脉形成模型进行比较，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于古高度计的样品类型，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应用。这项研究还间接解决了在陆地环境中识别气候历史的挑战，并有可能对人类引起的气候、陆地水文学和自然景观变化的后果提供见解。

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.