Re-inventing the planet: the Neoproterozoic revolution in oxygenation, biogeochemistry and biological complexity

地球是一个真正了不起的星球。除了驱动板块构造、气候和海洋-大气交换的物理过程外，它还支持着从微生物到哺乳动物以及介于两者之间的各种生物的非凡多样性。然而，情况并非总是如此，很明显，地球及其生物圈都在进化-事实上，共同进化-在很长的时间里。在过去的20亿年里，迄今为止，这种共同进化过程中最根本的转变发生在新元古代（1000至5.42亿年前），这是一场行星革命，最终形成了现代地球系统。新元古代开始于一个几乎完全由微生物组成的生物圈，并在其有史以来最大的进化辐射中结束-包括定义现代生物圈的各种宏观生物和生物矿化生物。与此同时，它见证了地球有史以来最大的气候和地球化学扰动，以及重大的古地理重新配置和第一次变得含氧的深海。毫无疑问，这些现象在很大程度上是相互关联的，但原因、后果和共同进化反馈的纠缠还没有被令人信服地分开。为了重建新元古代的革命，我们提出了一个多学科的研究计划，将捕捉其不断变化的地球化学和生物特征前所未有的细节。最重要的是，将在共同进化的地球系统的背景下评估和模拟这些整理的数据，其中一个分区的发展可能会促进和升级另一个分区的发展，有时甚至会产生全新的现象和共同进化的机会。我们的方法将由三个一般性假设指导，这些假设可以通过不断积累的数据和理论来检验：H1）与陆栖真核生物相关的增强的风化作用始于新元古代早期，导致主要的环境变化，包括极端冰川和大气氧浓度的逐步增加; H2）新元古代中期的主要环境变化引发了动物的出现;和H3），晚新元古代-寒武纪动物的辐射和生物矿化本身负责大部分伴随的地球化学扰动。该项目的主要数据将来自英国和华北地区关键地质剖面的实地研究，沿着来自纳米比亚、斯匹次卑尔根群岛的样品集和各种存档收藏。总之，这些提供了接近新元古代的全面覆盖面-尤其是，来自查恩伍德森林的埃迪卡拉巨型化石的壮观新表面。将对收集的样品进行分析，以评估相关的风化和气候（Sr、C、O和S同位素）、海洋氧化还原条件（Fe形态和微量金属）、营养动态（P形态和微量金属）和生物成分（微化石、宏化石和生物标志物分子）。这些数据将通过开发启发式、空间和进化模型进行整合和查询。除了其综合方法，这一建议的力量在于贡献研究人员的多样性。除了我们在生物地球化学、古生物学和地球系统建模方面的专业知识之外，我们很高兴在新元古代地层学、地质年代学和生物标志物分析方面吸引了世界一流的项目合作伙伴。进一步的见解将来自我们的两个PDRA和三个博士生的队伍，他们在一系列主题中工作，并通过定期团队会议的时间表联系起来。总之，我们预计从根本上提高了对新元古代地球系统的理解，以及生物圈和地球之间的共同进化相互作用。

The Earth is a truly remarkable planet. In addition to the physical processes driving plate tectonics, climate and ocean-atmospheric exchange, it supports an extraordinary diversity of living organisms, from microbes to mammals and everything in between. Such wasn't always the case, however, and it is clear that both the planet and its biosphere have evolved - indeed, co-evolved - over deep time. In the past two billion years, by far the most fundamental shift in this co-evolutionary process occurred during the Neoproterozoic (1000 to 542 million years ago), a planetary revolution that culminated in the modern Earth system. The Neoproterozoic begins with a biosphere populated almost exclusively by microbes, and ends in the midst of its greatest ever evolutionary radiation - including the diverse macroscopic and biomineralizing organisms that define the modern biosphere. At the same time, it witnessed the greatest climatic and biogeochemical perturbations that the planet has ever experienced, alongside major palaeogeographic reconfigurations and a deep ocean that is becoming oxygenated for the first time. There is no question that these phenomena are broadly interlinked, but the tangle of causes, consequences and co-evolutionary feedbacks has yet to be convincingly teased apart. In order to reconstruct the Neoproterozoic revolution, we propose a multidisciplinary programme of research that will capture its evolving geochemical and biological signatures in unprecedented detail. Most significantly, these collated data will be assessed and modeled in the context of a co-evolving Earth system, whereby developments in one compartment potentially facilitate and escalate those in another, sometimes to the extent of deriving entirely novel phenomena and co-evolutionary opportunities. Our approach will be guided by three general hypotheses, testable against accruing data and theory: H1) that the enhanced weathering associated with land-dwelling eukaryotes was initiated in the early Neoproterozoic leading to major environmental change, including extreme glaciations and stepwise increase(s) in atmospheric oxygen concentration; H2) that major environmental changes in the mid Neoproterozoic triggered the emergence of animals; and H3) that the late Neoproterozoic-Cambrian radiations of animals and biomineralization were themselves responsible for much of the accompanying biogeochemical perturbation. Primary data for this project will be assembled from field studies of key geological sections in the UK and North China, along with contributed sample sets from Namibia, Spitsbergen and various archived collections. Together, these offer close to comprehensive coverage of the Neoproterozoic - not least, spectacular new surfaces of Ediacaran macrofossils from Charnwood Forest. Collected samples will be analysed to assess associated weathering and climate (Sr, C, O and S isotopes), oceanic redox conditions (Fe speciation and trace metals), nutrient dynamics (P speciation and trace metals) and biological constituents (microfossils, macrofossils and biomarker molecules). These data will be integrated and interrogated through the development of heuristic, spatial and evolutionary models. Beyond its integrative approach, the strength of this proposal lies in the diversity of the contributing researchers. Alongside our own expertise in biogeochemistry, palaeobiology and Earth system modelling, we are very pleased to have attracted world-class project partners in Neoproterozoic stratigraphy, geochronology and biomarker analysis. Further insight will come from our contingent of two PDRAs and three PhD students working across the range of topics and linked via a schedule of regular team meetings. Taken together, we anticipate a fundamentally improved understanding of the Neoproterozoic Earth system and the co-evolutionary interplay between the biosphere and planet.