Accomplishment-Based Renewal: Testing Hypothesized CO2 Forcing of Climate, Glaciation, and Biotic Change During the End Carboniferous

ABR：在石炭纪末期测试假设的气候、冰川生物变化的CO2强迫Isabel Montanezalle-1024737摘要通过与同事和学生的合作，这个ABR项目的重点是关于晚古生代冰河时代的几个关键问题，这些问题仍然没有得到很好的限制。也就是说，二氧化碳变化的真实幅度，晚古生代气候敏感性，以及与区域水文气候，土壤生产力，冰盖稳定性和古热带植被重大重组的联系的性质。 建议的两个组成部分的研究计划集中在一个~ 900万年的石炭纪末的间隔，特别是一个假设？气候事件？在宾夕法尼亚纪中晚期的过渡时期第一部分将评估古二氧化碳分压在这段时间内的变化，以及它在广泛干旱和主要植被重建中的作用。预期的产品包括一个cyclothem规模（~105年）气孔指数为基础的记录古pCO 2使用两个长期和充分了解，湿地种子蕨类植物类群从伊利诺伊盆地。集成的旱生walchian针叶树cueries从选择的cyclothems将允许比较基于SI的CO2估计的湿地和旱地植物群和间冰期冰川尺度的CO2变化。化合物特定的同位素分析（Δ D和Δ 13 C）的相同的化石化石curidium将进一步限制的发病率和规模的古干旱在伊利诺伊州盆地和测试之间的因果关系pCO 2，陆地古热带干旱，和花卉生态重建。一个拟议的4年长时间，植物生长实验控制大气O2：CO2的比例和推断石炭纪气候条件下，将提供新的洞察化石为基础的趋势。将结果与古植物学数据和我们的古气候代理记录相结合，将用于为我们的气候建模工作开发适当的植被反馈组件。 第二个研究部分将利用已从两个古热带盆地收集的同一石炭纪末间隔的牙形刺（CAI 1-3），开发旋回尺度的Δ 18 O磷灰石记录。其目的是检验这一假设，即二氧化碳迫使全球变暖的时期也驱动冰盖消融和高频（104-105年）glacioeuvasts的幅度减少。通过合作，我们将测试的潜力？碳酸盐凝聚同位素？从一套保存异常完好和成岩筛选腕足动物从相同的地质部分确定降水的海面温度的方法。我们预计，对于保存最好的腕足动物，这种方法应该允许重建宾夕法尼亚州的SST和18 O海水，并最终最严格的评估冰量的相对变化在LPIA的日期。

ABR: Testing Hypothesized CO2 Forcing of Climate, Glaciation & Biotic Change During the End-CarboniferousIsabel MontanezEAR-1024737ABSTRACTThe focus of this ABR project, through collaboration with colleagues and students, is several key issues regarding the late Paleozoic Ice Age that remain poorly constrained ? i.e., the true magnitude of CO2 shifts, late Paleozoic climate sensitivity, and the nature of the linkages to regional hydroclimate, soil productivity, ice sheet stability, and major restructuring of paleotropical vegetation. The proposed two-component research plan focuses on a ~9 Myr interval of the end-Carboniferous, in particular a hypothesized ?climate event? during the mid-to-late Pennsylvanian transition. Component 1 will evaluate how paleo-pCO2 varied through this interval, and its role in widespread aridity and major vegetation restructuring. Anticipated products include a cyclothem-scale (~105 yr) stomatal index-based record of paleo-pCO2 using two long-ranging and well understood, wetland seed-fern taxa from the Illinois Basin. Integration of xerphytic walchian conifer cuticles from select cyclothems will permit comparison of SI-based CO2 estimates for wet- and dry-land flora and interglacial-glacial-scale CO2 variability. Compound-specific isotopic analysis (äD and ä13C) of the same fossil cuticles will further constrain the rate of onset and magnitude of paleoaridity in the Illinois Basin and test for causality between pCO2, terrestrial paleotropical aridity, and floral ecological restructuring. A proposed 4-year long-duration, plant growth experiment under controlled atmospheric O2:CO2 ratios and inferred Carboniferous climate conditions will provide novel insight into the fossil-based trends. Integration of results with paleobotanical data and our paleoclimate proxy records will be used to develop an appropriate vegetation-feedback component for our climate modeling efforts. The 2nd research component will develop a cyclothem-scale ä18O apatite record using already collected conodonts (CAI 1-3) from two paleotropical basins for the same end-Carboniferous interval. The objective is to test the hypothesis that periods of CO2-forced global warming also drove ice sheet ablation and a reduction in the amplitude of high-frequency (104-105 yr) glacioeustasy. Through collaboration, we will test the potential of the ?carbonate clumped isotope? method to define sea-surface temperatures of precipitation from a suite of exceptionally well-preserved and diagenetically screened brachiopods from the same geological sections. We anticipate that for the best-preserved brachiopods, this approach should permit reconstruction of Pennsylvanian SSTs and ä18Oseawater, and ultimately the most rigorous evaluation of relative changes in ice volume during the LPIA to date.