Probing Earth's earliest ecosystems: a multi-proxy study of the ~2.7 Ga Belingwe Greenstone Belt, Zimbabwe

探索地球最早的生态系统：对津巴布韦~2.7 Ga Belingwe 绿岩带的多代理研究

基本信息

批准号：
NE/M001768/1
负责人：
Euan Nisbet
金额：
$ 14.72万
依托单位：
Royal Holloway University of London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FM001768%2F1
关键词：
Probing Earth earliest ecosystems multi

项目摘要

Biology has been a major driver for global change since the very earliest stages of our planetary history. Life first evolved on Earth as early as 3.8 billion years ago, but for the first ~3 billion years it was composed entirely of small unicellular organisms lacking a nucleus (prokaryotes). Unlike their larger eukaryotic counterparts which mainly use oxygen and organic carbon as fuel for respiration, prokaryotes have diverse metabolisms that produce energy from a wide array of chemical compounds, including sulfide, methane, and even toxic metals. These metabolisms catalyse chemical reactions that only proceed rapidly with biological intervention, and their products can have an irrevocable effect on the chemistry of the environment. The modern Earth environment carries the irrefutable imprint of current and past biochemical reactions, as does the geologic record of past environments. Before ~2.4 billion years ago, Earth's atmosphere was dominated by carbon dioxide and methane (with little to no oxygen), and the oceans were rich in dissolved iron and, periodically, sulfide. This environment was inhospitable to large multi-cellular organisms, but prokaryotic ("microbial") ecosystems thrived. Sometime around ~2.7 billion years ago, organisms called cyanobacteria (the precursors to modern plants) evolved the ability to generate energy and biomass by combining H2O with CO2 in the presence of sunlight. This newly developed metabolism, termed oxygenic photosynthesis, constituted a major biological innovation and significantly increased the efficiency of global carbon cycling. Of particular significance to our history of planetary change - the waste product of this metabolism was molecular oxygen, which subsequently began to accumulate in the environment for the first time ever. The eventual buildup of oxygen in the atmosphere, termed the Great Oxidation Event, was a prerequisite for the evolution of animals and multi-cellular organisms, and eventually enabled the global biosphere that we inhabit today. Despite the importance of progressive oxygenation on the early Earth, geoscientists still lack a fundamental understanding of how ancient ecosystems contributed to oxygen production and responded to molecular oxygen in the environment. Central to unravelling feedbacks between global carbon fixation and oxygen production is understanding the changes in the cycling of other biologically-required nutrients that react with O2. Nitrogen, in particular, is ubiquitous to life and required for the formation of nearly all biomolecules, including nucleic acids (DNA and RNA) and proteins. The marine nitrogen cycle is driven largely by biological processes which produce changes that can be measured in nitrogen-bearing compounds and isotopes preserved in the rock record. This research seeks to investigate the interplay of elemental transformations in early microbial ecosystems, using geochemical analyses of pristine sediments that formed ~2.7 billion years ago. Of central importance to this project are new drill cores that are extremely well-preserved for rocks of this time period, and include some of the earliest evidence for fossilized microbial ecosystems (possibly including cyanobacteria). We will measure proxies for biogeochemical N, C, and S cycling, along with additional geochemical analyses for oxygen availability, to examine interactions between the oxygen, carbon, sulfur, and nitrogen cycles during early biospheric evolution. These records from ~2.7 billion year old rocks will contribute to our fundamental understanding of the chemical and biological evolution of Earth's surface environments during the time period most closely associated with cyanobacterial evolution, a prerequisite to biospheric oxygenation and the proliferation of complex life on Earth.

自地球历史的最初阶段以来，生物学一直是全球变化的主要驱动力。生命早在 38 亿年前就在地球上首次进化，但在最初的约 30 亿年里，生命完全由缺乏细胞核的小型单细胞生物（原核生物）组成。与主要使用氧气和有机碳作为呼吸燃料的较大真核生物不同，原核生物具有多种新陈代谢，可以从多种化合物产生能量，包括硫化物、甲烷，甚至有毒金属。这些新陈代谢催化的化学反应只有在生物干预下才能快速进行，其产物会对环境化学产生不可逆转的影响。现代地球环境带有当前和过去生化反应无可辩驳的印记，过去环境的地质记录也是如此。在约 24 亿年前，地球大气层主要由二氧化碳和甲烷（几乎没有氧气）组成，海洋中富含溶解的铁，并且定期含有硫化物。这种环境不适合大型多细胞生物，但原核（“微生物”）生态系统却蓬勃发展。大约 27 亿年前，称为蓝藻的生物体（现代植物的前身）进化出了通过在阳光下将水与二氧化碳结合来产生能量和生物质的能力。这种新开发的新陈代谢，称为氧光合作用，构成了一项重大的生物创新，并显着提高了全球碳循环的效率。对于我们的行星变化历史具有特别重要的意义 - 这种新陈代谢的废物是分子氧，随后它首次开始在环境中积累。大气中氧气的最终积累，被称为“大氧化事件”，是动物和多细胞生物进化的先决条件，并最终形成了我们今天居住的全球生物圈。尽管渐进式氧化对早期地球很重要，但地球科学家仍然对古代生态系统如何促进氧气产生以及对环境中分子氧的反应缺乏基本了解。揭示全球碳固定和氧气产生之间的反馈的核心是了解与氧气发生反应的其他生物所需营养物质循环的变化。尤其是氮，它在生命中无处不在，是几乎所有生物分子形成所必需的，包括核酸（DNA 和 RNA）和蛋白质。海洋氮循环主要由生物过程驱动，这些生物过程产生的变化可以通过岩石记录中保存的含氮化合物和同位素来测量。这项研究旨在利用约 27 亿年前形成的原始沉积物的地球化学分析来研究早期微生物生态系统中元素转化的相互作用。该项目最重要的是新的钻芯，这些岩芯在这一时期的岩石中保存得非常完好，并且包括一些化石微生物生态系统（可能包括蓝藻）的最早证据。我们将测量生物地球化学氮、碳和硫循环的替代指标，并对氧气可用性进行额外的地球化学分析，以检查早期生物圈演化过程中氧、碳、硫和氮循环之间的相互作用。这些来自约 27 亿年前岩石的记录将有助于我们对与蓝藻进化最密切相关的时期地球表面环境的化学和生物进化的基本了解，蓝藻进化是生物圈氧化和地球上复杂生命增殖的先决条件。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Very Strong Atmospheric Methane Growth in the 4 Years 2014-2017: Implications for the Paris Agreement

2014-2017 四年间大气甲烷增长非常强劲：对《巴黎协定》的影响

DOI：
http://dx.10.1029/2018gb006009
发表时间：
2019
期刊：
Global Biogeochemical Cycles
影响因子：
5.2
作者：
Nisbet E
通讯作者：
Nisbet E

Early global mantle chemical and isotope heterogeneity revealed by the komatiite-basalt record: The Western Australia connection

科马提岩-玄武岩记录揭示了早期全球地幔化学和同位素异质性：与西澳大利亚的联系

DOI：
http://dx.10.1016/j.gca.2021.11.030
发表时间：
2022
期刊：
Geochimica et Cosmochimica Acta
影响因子：
5
作者：
Puchtel I
通讯作者：
Puchtel I

Secular mantle oxidation across the Archean-Proterozoic boundary: Evidence from V partitioning in komatiites and picrites

跨太古代-元古代边界的长期地幔氧化：科马提岩和苦铁矿中 V 分配的证据

DOI：
10.1016/j.gca.2019.01.037
发表时间：
2019-04-01
期刊：
Geochimica et Cosmochimica Acta
影响因子：
5
作者：
R. Nicklas;I. Puchtel;Richard D. Ash;P. Piccoli;E. Hanski;E. Nisbet;P. Waterton;D. Graham Pearson;Ariel D. Anbar
通讯作者：
Ariel D. Anbar

The d53Cr isotope composition of komatiite flows and implications for the composition of the bulk silicate Earth

科马提岩流的 d53Cr 同位素组成及其对大块硅酸盐地球组成的影响