Co-evolution of atmosphere-hydrosphere redox states and life at the end of the Lomagundi-Jatuli Event: A failed natural experiment for a prelude of the Cambrian Explosion of life?

洛马贡迪-贾图利事件结束时大气层-水圈氧化还原态和生命的共同演化：寒武纪生命大爆发前奏的失败自然实验？

• 批准号: 398445499
• 负责人: Professor Dr. Ronny Schönberg, Ph.D.
• 金额: --
• 依托单位: Arbeitsgruppe Isotopengeochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/398445499?language=en
• 关键词: Co; evolution; atmosphere; hydrosphere; redox

The Paleoproterozoic Francevillian sedimentary successions of the Republic of Gabon, West Africa were described to record the most prominent aftermaths of the Great Oxidation Event (GOE) constrained at ca. 2.46-2.32 Ga ago. These include (1) the Lomagundi-Jatuli Event (LE) ─ the most positive carbon isotope excursion of the Earth’s history, and (2) the evidence of putative colonies of large eukaryotes associated with a well-oxygenated surface ocean. However, a number of geochemical-based studies shown that the upper part of this ca. 2.1 Ga old Francevillian Group, overlaying the lower fossil-bearing part, was deposited under anoxic water column which also coincided with the end of the LE. Such an upper Francevillian ocean anoxia is particularly consistent with an emerging paradigm arguing for a global deoxygenation event into our planet some 200-300 Ma after the beginning of the GOE. Moreover, recent studies investigated Se isotope systematics for deep marine organic-rich shales and inferred that surface oceans were only suboxic during the onset of the GOE and thus O2 levels were not high enough to allow the development of eukaryotic life. Here we intend to investigate (i) the C and O isotopic compositions of organic- and carbonate carbon for bringing further insights on the global average fractionation between C-org and C-carb likely contributing to improve our understanding on the amount of oxygen released in the atmosphere-ocean system during the late stages of the GOE and the LE, (ii) the major and trace elements variations and Fe-Mo isotopic compositions of Francevillian sediments for a better understanding of the water column chemistry and associated redox states with particular emphasis on what controlled the cycling of transitional metals in the oceans during the late stages of the GOE and the LE, (iii) detailed stable Se isotope systematics to further test whether shallow oceans were oxygenated enough to allow the development and proliferation of complex life. The ultimate goal of this study however is to test the attempt of marine environmental conditions at creating higher life forms during the onset of the GOE and LE as well as why it probably did not work and what ended the LE.

西非加蓬共和国的古元古代francevian沉积序列记录了大约2.46-2.32 Ga前的大氧化事件（GOE）最显著的后果。这些包括(1)Lomagundi-Jatuli事件（LE）──地球历史上最积极的碳同位素漂移事件；(2)与氧合良好的表层海洋有关的大型真核生物假定群落的证据。然而，一系列基于地球化学的研究表明，这一约2.1 Ga古老的Francevillian群的上部覆盖了下部含化石部分，沉积在缺氧水柱下，这也与LE末期相吻合。这样的上法兰西海洋缺氧特别符合一个新兴的范式，即在GOE开始后约200-300 Ma的全球脱氧事件进入我们的星球。此外，最近的研究对深海富有机质页岩的Se同位素系统进行了研究，并推断在GOE开始时，表层海洋仅处于亚氧状态，因此O2水平不足以使真核生物发育。在这里，我们打算研究(i)有机碳和碳酸盐碳的C和O同位素组成，以进一步了解C-org和C-碳水化合物之间的全球平均分异，这可能有助于提高我们对GOE和LE后期大气-海洋系统中释放的氧气量的理解；（ii）研究Francevillian沉积物的主要和微量元素变化以及Fe-Mo同位素组成，以便更好地了解水柱化学和相关的氧化还原状态，特别强调在GOE和LE后期控制海洋中过渡金属循环的因素；（iii）详细介绍稳定Se同位素系统，以进一步测试浅海是否有足够的氧合以允许复杂生命的发展和繁殖。然而，这项研究的最终目标是测试海洋环境条件在GOE和LE开始时创造高等生命形式的尝试，以及为什么它可能不起作用，是什么结束了LE。

项目成果

Constraining provenance for the uraniferous Paleoproterozoic Francevillian Group sediments (Gabon) with detrital zircon geochronology and geochemistry

用碎屑锆石年代学和地球化学约束古元古代弗朗西维利群沉积物（加蓬）的物源

• DOI: 10.1016/j.precamres.2020.105724
• 发表时间: 2020
• 期刊: Precambrian Research
• 影响因子: 3.8
• 作者: Ossa Ossa;Hofmann;Ballouard;Vorster;Schoenberg;Friedrich;Mayaga- Mikolo;Bekker
• 通讯作者: Bekker

Increase in ecosystem complexity aided organic carbon sequestration during the c. 2.22-2.06 Ga Lomagundi carbon isotope excursion

c 2 22-2 06 Ga Lomagundi 碳同位素漂移期间生态系统复杂性的增加有助于有机碳固存

• DOI: 10.5194/egusphere-egu21-10828
• 发表时间: 2021
• 作者: Ossa Ossa;König;Hofmann;Bekker;Spangenberg;Schoenberg
• 通讯作者: Schoenberg