Development of a High-Resolution Stromatolite Facies Model: Environmental Impacts at the Dawn of Oxygenation

高分辨率叠层石相模型的发展：氧化初期的环境影响加州州立大学（Chico State） Animikie盆地的古元古代含铁地层拥有一些保存最完好的微化石和多种叠层石，这些叠层石来自地球从缺氧海洋转向含氧海洋的时期。这段时间被称为“大氧化事件”，是古生物学家、地球化学家和经济地质学家越来越重要的研究领域。然而，叠层石沉积的古环境背景仍然存在重要问题，限制了对海洋条件与局部细菌生态系统之间复杂相互作用的理解。该提案通过将强大的三维建模软件（Petrel v.2010）应用于非凡的专有钻探岩心集合，解决了叠层石在空间中如何随着海洋和环境条件的变化而变化。具体而言，本文提出了以下问题：(1)叠层石在多大程度上可以用来描绘岸线地貌，加强古环境重建？(2)埋藏学在叠层石和微化石保存中的作用是什么？四种主要的叠层石类型在整个Animikie盆地大约两米尺度的地层中被发现，尽管不一定是连续的地层。露天塔克石矿壁（现被淹）的制图表明，宏观结构的变化出现在10至100米的尺度上。叠层石是生物成因的，在正常的海洋条件下形成，在趋化斜层之上，在缺氧的水中。在此基础上，我们相信叠层石的宏观结构形式，连同稀疏但保存完好的微化石记录，可以与沉积学和地层学数据相结合，建立叠层石生物面模型，这将有助于限制地球历史上这一关键时期独特的海洋变率。该研究项目将在空间分辨率上解决叠层石变化和古环境构造意义，这是以往研究中未实现的。更广泛的影响。该项目的研究结果将为研究其他前寒武纪盆地在“大氧化事件”期间的古生物学和生物地球化学模式提供参考。该传播计划要求在YouTube上制作一系列短片，向广大观众展示早期含氧地球微生物-沉积物相互作用的动态和复杂世界。这项研究将为一所主要本科院校的几名本科生提供重要的初步研究经验。PI的教学方法将通过更好地理解这一关键间隔和基于项目的学习机会而得到加强，这是他教学法的一个组成部分。

Development of a High-Resolution Stromatolite Facies Model: Environmental Impacts at the Dawn of OxygenationRussell ShapiroCalifornia State University, Chico StateThe Paleoproterozoic iron-bearing formations of the Animikie Basin host some of the best-preserved microfossils and diverse stromatolites from a time when the Earth was switching from anoxic to euxinic oceans. This interval, known as the "Great Oxidation Event," is an increasingly important research area for paleobiologists, geochemists, and economic geologists. However, important questions still exist as to the paleoenvironmental setting of the stromatolitic deposits, limiting the understanding of the complex interplay between oceanic conditions and the localized bacterial ecosystems. This proposal addresses how stromatolites vary in space in response to changing oceanographic and environmental conditions by applying powerful 3-D modeling software (Petrel v.2010) to an extraordinary collection of proprietary drill core. Specifically, this proposal addresses: (1) To what extent can the stromatolites be used to delineate shoreline geomorphology, enhancing paleoenvironmental reconstructions? and (2) What is the role of taphonomy in both stromatolite and microfossil preservation?Four major stromatolite types are found in roughly two, meter-scale horizons throughout the Animikie Basin, though not necessarily as continuous horizons. Mapping of open taconite mine walls (now flooded) demonstrated that macrostructural variability appears at scales of 10 to 100 meters. The stromatolites are biogenic and formed under normal marine conditions, above the chemocline, in suboxic waters. Based on this work, it is believed that the macrostructural forms of stromatolites, together with the sparse but well-preserved microfossil record, can be integrated with the sedimentologic and stratigraphic data to develop a model of stromatolite biofaces that will help to constrain the unique oceanographic variability in this critical interval of Earth history. The proposed research project will address stromatolite variation and the paleoenvironmental tectonic implications at a spatial resolution that has not been achieved in previous studies of this interval.Broader Impacts. The results of this project will be valuable to researchers studying paleontological and biogeochemical patterns in other pre-Cambrian basins during the "Great Oxidation Event." The dissemination plan calls for the development of a series of YouTube short films that will open up the dynamic and complex world of microbial-sediment interactions of the early oxygenated Earth to a broad audience. The research will provide critical primary research experience for several undergraduate students at a primarily undergraduate institution. The teaching methods of the PI will be enhanced with a greater understanding of this critical interval and opportunities for project-based learning which form an integral component of his pedagogy.