EAR-PF: Investigating Redox-Related Preservation of Organic-Walled Microfossils in Proterozoic Shales: a Multi-Scale Approach.

EAR-PF：研究元古代页岩中有机壁微化石的氧化还原相关保存：多尺度方法。

基本信息

批准号：
2204590
负责人：
Christina Woltz
金额：
$ 18万
依托单位：
Woltz, Christina Rose
依托单位国家：
美国
项目类别：
Fellowship Award
财政年份：
2023
资助国家：
美国
起止时间：
2023-04-01 至 2025-03-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2204590&HistoricalAwards=false
关键词：
EAR PF Investigating Redox Related

项目摘要

Dr. Christina Woltz has been awarded an NSF EAR Postdoctoral Fellowship to carry out research and education plans at Stanford University. Before the widespread appearance of animals around 550 million years ago, life on Earth was almost entirely microscopic. Eukaryotes—the domain of life that includes animals, plants, and a great diversity of single-celled organisms—first appear in the fossil record around 1650 million years ago as microscopic organic structures compressed in fine-grained rock. Although their fossil record documents large-scale changes in diversity through time, it can also be influenced by changes in the environmental conditions that control fossilization. In particular, the presence of oxygen is thought to increase the degradation of organic matter, but the effects of oxygen on the quality of the early eukaryotic fossil record have not been examined comprehensively. The goal of this project is to explore how the presence of oxygen in the burial environment might have influenced the preservational quality of microfossil assemblages. By understanding the relationship between microfossil preservation and oxygen, this project will assess if certain time intervals of fluctuating oxygen concentrations have biased our current understanding of early eukaryotic evolution. This project will also develop teaching modules that connect undergraduate students to current research topics using a large open-access geochemistry database (available through the Sedimentary Geochemistry and Paleoenvironments Project). These teaching modules will expose students to applications of Earth science, which increases student engagement, and equips them with skills in data management to support their continued involvement in science. It is a long-held assumption that local ocean anoxia is necessary for the fossilization of organic remains. Although this relationship is well-documented in the Phanerozoic record of soft-tissue animal fossils, it is unclear if the same conditions apply to the record of Proterozoic organic-walled microfossils. Here, the preservational quality of microfossil assemblages will be compared to several redox proxies—including iron speciation, and uranium and molybdenum abundances—measured from a suite of shale samples that span mid to late Proterozoic time. Since redox conditions can vary significantly over short time intervals, redox proxies (including iron species) will be measured at ultra-high resolution on select samples using synchrotron-based x-ray spectroscopy. By quantifying the relationship between fossil preservation and paleoredox conditions, this project lays the groundwork for detecting largescale changes in preservation potential within the Proterozoic fossil record. For example, the first appearance of eukaryotes in the fossil record (around 1650 Ma) occurs much later than is predicted by molecular clock estimates and the complexity of the first eukaryotic fossils. It is possible that the appearance of eukaryotes at this time marks the onset of more favorable preservational conditions. Additionally, this project develops teaching modules aimed towards engaging a diverse undergraduate community in Earth science research. Laboratory modules will develop skills related to the management and analysis of large datasets, which are necessary yet underdeveloped skills in the undergraduate population.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.

克里斯蒂娜·沃尔茨 (Christina Woltz) 博士获得了美国国家科学基金会 (NSF) EAR 博士后奖学金，负责在斯坦福大学开展研究和教育计划。在大约 5.5 亿年前，地球上的生命几乎完全是微观的真核生物。包括动物、植物和多种单细胞生物——在大约 16.5 亿年前首次出现在化石记录中，作为压缩在细粒岩石中的微观有机结构，尽管它们的化石记录记录了这些生物。随着时间的推移，多样性发生大规模变化，它也可能受到控制化石化的环境条件变化的影响，特别是，氧气的存在被认为会增加有机物的降解，但氧气对有机物质量的影响。该项目的目标是通过了解微体化石保存与氧气之间的关系，探索埋藏环境中氧气的存在如何影响微体化石组合的保存质量。将评估如果氧气浓度波动的某些时间间隔使我们目前对早期真核进化的理解产生偏差，该项目还将开发教学模块，使用大型开放访问地球化学数据库（可通过沉积地球化学和古环境项目获取）将本科生与当前的研究主题联系起来。这些教学模块将使学生接触地球科学的应用，从而提高学生的参与度，并为他们提供数据管理技能，以支持他们继续参与当地海洋科学。缺氧对于有机遗骸的化石化是必要的，尽管这种关系在软组织动物化石的显生宙记录中得到了充分的记录，但尚不清楚同样的条件是否适用于元古代有机壁微化石的记录。微化石组合的质量将与几种氧化还原指标进行比较——包括铁形态、铀和钼丰度——通过一系列测量由于氧化还原条件在短时间内可能发生显着变化，因此将使用基于同步加速器的 X 射线光谱法以超高分辨率测量选定的样品。通过研究化石保存与古氧化还原条件之间的关系，该项目为检测元古代化石记录中保存潜力的大规模变化奠定了基础，例如真核生物在古生代中的首次出现。化石记录（大约 1650 Ma）的出现比分子钟估计的要晚得多，而且第一批真核生物化石的复杂性可能表明此时真核生物的出现标志着更有利的保存条件的开始。开发教学模块，旨在让多元化的本科生参与地球科学研究。实验室模块将培养与大型数据集管理和分析相关的技能，这些技能对于本科生来说是必要但尚未开发的技能。该奖项反映了 NSF 的法定使命，并具有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，被认为值得支持。

项目成果

期刊论文数量（4）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Evaluating the effects of preservation on eukaryotic diversity patterns of the late Tonian Chuar and Uinta Mountain groups of western Laurentia

评估保护对劳伦西亚西部托尼安楚阿晚期和尤因塔山群真核生物多样性模式的影响

DOI：
10.1130/abs/2023am-394325
发表时间：
2023-10
期刊：
Abstracts with Programs
影响因子：
0
作者：
Woltz, Christina R.;Porter, Susannah M.;Dehler, Carol M.;Riedman, Leigh Anne
通讯作者：
Riedman, Leigh Anne

Patterns in early eukaryote diversity and their preservation in Proterozoic shales

早期真核生物多样性模式及其在元古代页岩中的保存