Collaborative Research: Anatomy of a Greenhouse World: The Early Eocene of the Green River Basin, Wyoming

合作研究：温室世界的解剖：怀俄明州格林河流域的始新世早期

• 批准号: 1813088
• 负责人: Mark Schmitz
• 金额: $ 25.54万
• 依托单位: Boise State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1813088&HistoricalAwards=false
• 关键词: Collaborative; Research; Anatomy; Greenhouse; World

The geologic record of past environmental change offers an illuminating glimpse into the behavior of Earth's natural systems. The deposits formed in ancient lakes are particularly useful in this regard for several reasons: they are highly sensitive to climate change; they often contain relatively complete geologic archives with relatively few gaps; and they can potentially be used to document changes that occurred over time scales meaningful to humans. The Green River Formation in the western U.S. offers an especially valuable record of the most geologically recent period of prolonged greenhouse conditions, which occurred approximately 50-53 million years ago during the Eocene Epoch. It is famous for its rich assemblages of fossil vertebrates, insects, and plants, and for containing the world's largest commercial deposits of soda ash and oil shale. This research project will focus on evidence for repeated rapid warming events during this time, by examining how river courses changed, the types of sediment that accumulated within the lake, and variations in ancient soil development and chemistry. Equally important, this study will build a time scale of unprecedented accuracy and precision for these important deposits, based on new radiometric dates of volcanic ash in the lake, the chronology of changes in the Earth's magnetic field, and sedimentation patterns that were driven by periodic oscillations in the Earth's rotation and orbit. Broader impacts of this proposal will include development of local 2-hour field trips for middle and high school students, enhanced through the use of innovative data visualization technology on portable devices. The Early Eocene Climatic Optimum (EECO) was a time of persistent global warmth, of which the cause remains incompletely determined. Lake deposits of the Green River Formation preserve a rich and previously untapped record that complements that contained in marine sediments, and present an opportunity to advance the precision and accuracy of the Early Eocene timescale. This project is an integrated, multidisciplinary investigation focused on one of the world's richest and best studied systems of ancient lake strata. The research will investigate three principal questions: 1. How did the timing of terrestrial warming compare to that inferred from the marine record, and to predicted patterns of the Earth's orbital variations? Recent advances in radioisotopic dating can be used to directly test the relationship of warming events to Earth's orbital changes, and calibrate dynamic gravitational models of the solar system back to ca. 50 million years. 2. How did temperatures, seasonality, hydrologic cycling, and weathering on land evolve during the EECO? One hypothesis is that warming was amplified on continents relative to the oceans and was accompanied by more equable temperatures year-round, whereas precipitation seasonality and intensity increased. 3. How did the complex tectonic and magmatic evolution of western North America impact the preservation of EECO climate signals? The research will test the hypothesis that repeated, stepwise drainage reorganizations within the tectonically-active uplands modified the hydrologic balance and sedimentary deposits of the Eocene lake environment and its response to orbital changes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

过去环境变化的地质记录为我们了解地球自然系统的行为提供了启发性的一瞥。 古代湖泊中形成的沉积物在这方面特别有用，原因如下：它们对气候变化高度敏感；它们往往包含相对完整的地质档案，且空白相对较少；它们有可能被用来记录一段时间内发生的对人类有意义的变化。 美国西部的绿河地层为地质学上最近时期的长期温室条件提供了特别有价值的记录，该条件发生在大约 50-5300 万年前的始新世时期。 它以其丰富的脊椎动物、昆虫和植物化石组合以及世界上最大的纯碱和油页岩商业矿藏而闻名。 该研究项目将通过研究河道如何变化、湖内积累的沉积物类型以及古代土壤发育和化学的变化，重点关注这段时间反复出现的快速变暖事件的证据。 同样重要的是，这项研究将为这些重要的沉积物建立一个前所未有的准确度和精度的时间尺度，基于湖中火山灰的新辐射日期、地球磁场变化的年表以及由周期性变化驱动的沉积模式。地球自转和轨道的振荡。 该提案的更广泛影响将包括为中学生和高中生开展当地 2 小时实地考察，并通过在便携式设备上使用创新的数据可视化技术来增强这一成果。 始新世早期气候最佳期（EECO）是全球持续变暖的时期，其原因尚未完全确定。 绿河组的湖泊沉积物保留了丰富的、以前未开发的记录，补充了海洋沉积物中所包含的记录，并为提高早始新世时间尺度的精度和准确性提供了机会。 该项目是一项综合的、多学科的调查，重点关注世界上最丰富、研究最透彻的古代湖泊地层系统之一。该研究将调查三个主要问题： 1. 陆地变暖的时间与从海洋记录推断的时间以及地球轨道变化的预测模式相比如何？ 放射性同位素测年的最新进展可用于直接测试变暖事件与地球轨道变化的关系，并将太阳系的动态引力模型校准回约。五千万年。 2. EECO期间陆地上的温度、季节性、水文循环和风化是如何演变的？一种假设是，相对于海洋，大陆变暖加剧，并伴随着全年气温更加均匀，而降水季节性和强度增加。 3. 北美西部复杂的构造和岩浆演化如何影响EECO气候信号的保存？ 该研究将检验以下假设：构造活动高地内重复、逐步的排水重组改变了始新世湖泊环境的水文平衡和沉积物及其对轨道变化的响应。该奖项反映了 NSF 的法定使命，并被认为值得支持通过使用基金会的智力优点和更广泛的影响审查标准进行评估。

项目成果

Astronomical and tectonic influences on climate and deposition revealed through radioisotopic geochronology and Bayesian age-depth modeling of the early Eocene Green River Formation, Wyoming, USA

• DOI: 10.1130/b36584.1
• 发表时间: 2023-03-16
• 期刊: GEOLOGICAL SOCIETY OF AMERICA BULLETIN
• 影响因子: 4.9
• 作者: Bruck, Benjamin T.;Singer, Brad S.;Jicha, Brian R.
• 通讯作者: Jicha, Brian R.