U.S.-France Collaborative Study of the Alteration of Ancient Stromatolites: New Insights through Coupled Petrology and Isotope Geochemistry

一种非技术性的解释是叠层石，微生物活动的宏观化石证据，是在早期地球和外星任务中寻找生命的重要生物标志。尽管赋予有机生物标志物的价值以定义过去生活的记录已经变得越来越重要，但叠层石仍然是最容易看到的微生物大型化石。然而，成岩和变质作用对叠层石的挖掘经济学效应鲜为人知，阻碍了它们作为过去生活的忠实记录者的用途。该项目提议开展一项新的合作，以描述和量化接触和区域变质作用以及流体诱导的成岩变化对苏必利湖地区1,878 Ma Biwabik-Gunflint铁建造的生物叠层石层的影响。之所以选择这个目标，是因为它提供了一个可以接近的非凡的自然实验室环境，可以在三维框架内仔细而准确地绘制样本，而且地质历史复杂，涵盖了几条不同的挖掘路径。这项完整的研究将对研究早期地球和外星目标上其他蚀变沉积物中的古生物和生物地球化学模式的研究人员具有重要意义。这项研究将为两名本科生提供关键的初级研究经验，在一所以本科生为主的机构，利用他们所在机构没有的机会促进他们的职业生涯。随着对岩石学和地球化学信息耦合的更多了解，PI的教学方法将得到加强。最重要的是，通过建立一种新的合作，将为基于项目的跨学科学习提供更多的机会，这构成了皮？S教学法的一个组成部分。技术描述这项国家创新中心提案的重点是在法国布雷斯特大学的世界级实验室工作。在此次访问期间，新的协作团队将分析样品中的铁同位素和微量元素地球化学指标，这些指标将与Pi？S关于生物叠层岩层变质梯度中的矿物学和岩石学变化的广泛数据库相结合。这一具体合作将补充和挑战先前关于铁建造的地球化学印记和保存古代化石沉积物中原始地球生物化学特征的研究。这将对天体生物学、地球化学、矿物学、经济地质学和古生物学等领域的研究人员具有重要意义。

a non-technical explanation Stromatolites, the macrofossil evidence of microbial activity, are an important biosignature in the search for life on early Earth and in extraterrestrial missions. Although it has become increasingly important to place value on organic biomarkers to define a record of past life, stromatolites remain the most readily visible microbial macrofossil. Yet, the taphonomic effect of diagenesis and metamorphism on stromatolites is poorly known, hampering their utility as a faithful recorder of past life.The project proposes to develop a new collaboration to describe and quantify the effects of contact and regional metamorphism and fluid-induced diagenetic changes on biogenic stromatolite beds of the 1,878 Ma Biwabik-Gunflint iron formations of the Lake Superior region. This target has been chosen because it offers a phenomenal natural laboratory setting that is accessible, samples can be carefully and accurately plotted in a three-dimensional framework, and the geologic history is complex and covers several divergent taphonomic pathways. The full study will be significant to researchers studying paleontological and biogeochemical patterns in other altered sediments both on early Earth and extraterrestrial targets. The research will provide critical primary research experience for two undergraduate students at a primarily undergraduate institution, enhancing their careers with opportunities not available at their host institution. The teaching methods of the PI will be enhanced with a greater understanding of coupled petrologic and geochemical information. Most critically, by creating a new collaboration, there will develop additional opportunities for interdisciplinary project-based learning which forms an integral component of the PI?s pedagogy.a technical description The focus of this CNIC proposal is to work in a world-class laboratory at the Université of Brest, France. During this visit, the new collaborative team will analyze samples for iron isotope and trace element geochemical proxies that will integrate with the PI?s extensive database on mineralogic and petrographic changes throughout the metamorphic gradient of a biogenic stromatolite layer. This specific collaboration will both complement and challenge previous research on the geochemical imprint of iron formations and the preservation of original geobiochemical signatures in ancient fossil deposits. The implications will be of major importance to researchers in fields as diverse as astrobiology, geochemistry, mineralogy, economic geology, and paleobiology.