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

该探索性项目旨在根据植物生物标志物的氢同位素比值校准一种新的古高度计。这些比率使重建的同位素签名的古沉淀，从古海拔推断使用物理为基础的同位素海拔模型。这种方法是植根于系统的氢同位素组成的分子，包括植物叶片上的表皮蜡质涂层和降水的同位素组成之间的关系。正在使用从北美和安第斯山的湖泊中提取的植物蜡正构烷烃对这种新方法进行评估，这些湖泊代表了一系列植物群落、水文和海拔高度。现代湖泊沉积物为古湖泊环境提供了理想的模拟物。重建的降水氢同位素比值和高程估计与实际湖泊高程和当地降水组成的比较，将提供一个强大的和直接的手段来评估氢同位素比值的植物蜡生物标志物作为古高程代理。在波兰的Siemianice实验森林，在相同的气候和水源下生长的六个不同树种的单种林分，代表着新生代的主要分类群，通过测量叶、根和土壤中植物蜡的氢同位素组成，正在评估植物生理学的作用。这些测量允许评估植物蜡合成伴随的蒸腾作用和同位素分馏的物种依赖性差异。古高程是构造和气候研究中的一个重要变量。基于观测的估计提供了一个基准，可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扩大适合古高度测量的样品类型，同时开创了地质地球化学工具在构造系统研究中的跨学科和新应用。这项研究还间接地解决了识别陆地环境中气候历史的挑战，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。

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.