CAREER: Tracking deep-time environmental change through statistical analyses of the sedimentary geochemical record

历史地球生物学研究地球上的环境如何随着时间的推移而变化，以及地球上的生命如何应对这些变化。这段历史被存档在地球化学记录中，这项资助利用了一个开放的国际研究联盟，沉积地球化学和古环境项目（SGP），来建立和分析这一记录。具体而言，SGP旨在建立一个大型沉积地球化学记录数据库（例如，成千上万的样本）使用独特的“众包”方法。除了汇编已发表的数据外，这笔赠款还将对研究不足的时间间隔进行新的沉积地球化学研究;这些项目将涉及来自不同机构和背景的16名本科生。然后将对数据库进行分析，以了解海洋中的初级生产力和氧气水平如何在地质时期发生变化。赠款活动将有助于小额赠款方案网站的开发，该网站目前是最大的沉积地球化学测量公开数据库的门户。这种开放获取的数据产品对于从事沉积岩研究的行业特别有用，例如碳氢化合物和矿物勘探（贱金属矿床，关键金属）以及地下水研究。 该提案将使用SGP数据产品来解决地球历史中的两个关键问题。首先，有机碳埋藏和底栖生物的食物供应如何随时间变化（以页岩总有机碳（TOC）含量为代表）？第二，如何改变了海洋的氧化还原景观通过地球的历史（作为代理的氧化还原敏感的微量金属丰度在缺氧/富氧黑色页岩）？该提案将通过利用大型SGP数据库和复杂的分析方法来测试先前从文字数据分析和较小数据集生成的假设，包括用于解决时空采样异质性的重加权自举技术和用于消除时空采样异质性的机器学习技术。综合多种地质偏差对地球化学代用指标的影响。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估。

The field of historical geobiology investigates how environments have changed on Earth over time and how life on Earth has responded to these changes. This history is archived in the geochemical record, and this grant utilizes an open international research consortium, the Sedimentary Geochemistry and Paleoenvironments Project (SGP), to both build and analyze this record. Specifically, SGP aims to assemble a large database of sedimentary geochemical records (e.g., hundreds of thousands of samples) using a unique ‘crowd sourcing’ approach. In addition to compiling published data, this grant will conduct new sedimentary geochemistry studies of under-studied time intervals; these projects will involve 16 undergraduate students from diverse institutions and backgrounds. The database will then be analyzed to understand how primary productivity and oxygen levels in the ocean have changed through geological time. Activities in the grant will contribute to development of the SGP website, which is currently the portal to the largest publicly available database of sedimentary geochemical measurements. This open access data product is particularly useful for industries working in sedimentary rocks such as hydrocarbon and mineral exploration (base metal deposits, critical metals) as well as groundwater research. This proposal will use SGP data products to address two key questions in Earth history. First, how has organic carbon burial and food supply to the benthos changed through time (as proxied by shale total organic carbon (TOC) contents)? Second, how has the ocean’s redox landscape changed through Earth history (as proxied by redox-sensitive trace metal abundances in anoxic/euxinic black shales)? This proposal will test previous hypotheses generated from literal data analysis and smaller datasets by utilizing the large SGP database and sophisticated analytical methods, including re-weighted bootstrapping techniques to address spatio-temporal sampling heterogeneity and machine learning techniques to de-convolve the influence of multiple geological biases on a geochemical proxy.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.