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

叠层石是微生物活动的大型化石证据，是寻找早期地球生命和地外任务的重要生物标志。尽管利用有机生物标记物来定义过去生命的记录变得越来越重要，但叠层石仍然是最容易看到的微生物大化石。然而，成岩作用和变质作用对叠层石的埋藏学影响尚不清楚，这阻碍了叠层石作为过去生命忠实记录者的作用。该项目建议开展一项新的合作，以描述和量化苏必利尔湖地区1878 Ma Biwabik-Gunflint铁地层的接触和区域变质作用以及流体诱发的成岩变化对生物成因叠层石床的影响。之所以选择这个目标，是因为它提供了一个非凡的自然实验室环境，可以接近，样品可以在三维框架中仔细准确地绘制，地质历史很复杂，涵盖了几种不同的埋藏路径。完整的研究对于研究早期地球和外星目标上其他改变沉积物的古生物学和生物地球化学模式的研究人员来说意义重大。这项研究将为一所主要本科院校的两名本科生提供重要的初级研究经验，并为他们的职业生涯提供在其所在院校无法获得的机会。加深对岩石学和地球化学耦合信息的理解，将加强PI的教学方法。最重要的是，通过建立新的合作关系，将为跨学科的基于项目的学习提供额外的机会，这是PI的一个组成部分。教育学。这项CNIC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，新的合作团队将分析铁同位素和微量元素地球化学代理样品，这些样品将与PI？广泛的矿物学和岩石学变化数据库，整个生物成因叠层石层的变质梯度。这一具体的合作将补充和挑战先前对铁地层的地球化学印记和古代化石矿床中原始地球生物化学特征的保存的研究。这对天体生物学、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来说意义重大。

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.