Perturbation of the Earth System at the Proterozoic-Phanerozoic transition and the resilience of the biosphere

Lead Research Organisation: NERC British Geological Survey
Department Name: NERC Isotope Geosciences Laboratory

Abstract

Charles Darwin's great dilemma was why complex life in the form of fossil animals appear so abruptly in rocks around 520 million years ago (Ma), in what is widely known as the Cambrian explosion. During recent decades, exceptionally preserved animal fossils have been found throughout the Cambrian Period, which began 20 million years earlier, and arguably even through the entire, preceding Ediacaran Period, which directly followed the worldwide 'Snowball Earth' glaciations (~715 - 635 Ma). Most of these exceptional deposits were discovered in South China, which possesses the best preserved and dated geological record of the marine environment for this time. In this genuinely collaborative UK-China project, we propose to use the South China rock archives to construct a much higher resolution, four-dimensional (temporal-spatial) picture of the evolutionary history of the earliest animals and their environment. Towards this endeavour, our group combines complementary expertise on both the UK and Chinese research teams in: 1) geochronology - the dating of rocks; 2) geochemistry - for reconstructing nutrient and the coupled biogeochemical cycle (O and C); 3) phylogenomics - for making a genetically-based tree of life to compare with, and fill gaps in the fossil records; and finally 4) mathematical modelling, which will enable us to capture geological information, in such a way as to test key hypotheses about the effects of animal evolution on environmental stability. Our project aims to address three central scientific questions: 1) How did the coupled biogeochemical cycles of C, O, N, P and S change during these evolutionary radiations?; 2) Did environmental factors, such as oxygen levels, rather than biological drivers, such as the emergence of specific animal traits, determine the trajectory of evolutionary change?; and 3) Did the rise of animals increase the biosphere's resilience against perturbations? This last question has relevance to today's biosphere, as the modern Earth system and its stabilising feedbacks arose during this key interval. By studying it in more detail, and establishing temporal relationships and causality between key events, we can find out how the modern Earth system is structured, including which biological traits are key to its continued climatic and ecosystem stability. One further goal of this project is to strengthen existing and establish new, and genuinely meaningful collaborations between the UK and Chinese investigators. We will achieve this by working jointly in four research teams, by integrating all existing and new data into an international database, called the Geobiodiversity Database, sharing a joint modelling framework, and by providing collaborative training for the early career researchers involved in this project each year of the project.

Planned Impact

The nature of the research topic means that much of the direct benefit will be for the academic community (see Academic Beneficiaries), however as it tackles the emergence of complex life on Earth there will be significant public interest in the research topic, approach, progress and outputs. Going beyond the topic itself, our approach is non-traditional in that it is highly integrative and seeks to develop and exploit a step change to develop inter-operable multi-parameter datasets and models, impacting how others research similar 'Earth System' topics.
Beyond the academic community (see Academic Beneficiaries) we expect the general public, in UK and China, will be beneficiaries of the research. The 'Cambrian explosion' and the origin of complex life on our planet was listed in an Economist article 'Life, the multiverse and everything, Science has remade the world, but scientists are not finished yet' (6th August 2015) as one of Science's six unsolved mysteries. This highlights that the research topic covered by this proposal is one of the big ones that captures the public's interest. We will develop novel web, using Quick Response (QR) codes and MediaWIKI infrastructure to communicate project science at sites where the rocks outcrop, and museums. We expect this to generate interest in the Earth and Biological Sciences, highlighting how the Earth system has evolved and operated prior to becoming our familiar world, will allow us to engage with the public and get them to think about complexity, feedbacks, and how systems evolve. Whilst the current changes facing the planet are operating at different timescales there are parallels to be made and lessons to be learnt from studying the 'Cambrian explosion'.
The focus on 'data mining and management' within this project allows us to identify those organisations and professional scientific bodies who are invested in developing geoscience 'data management' tools. In the case of this project, such organisations would include the International Commission on Stratigraphy (ICS), the Interdisciplinary Earth Data Alliance (IEDA), and the EARTHTIME Initiative. These organisations will benefit from our engagement with such systems and using this project to accelerate development in identified key areas. These will include aiding the federation of data from the GEOCHRON databased with the stratigraphic data in the GeoBiodiversity Database, and the development of 'age-model' tools within the later.
A third group of beneficiaries represent the industries that are engaged with exploring the resource potential of late Precambrian and earliest Phanerozoic sedimentary successions. The resources in question are primarily hydrocarbons although economic sulphide and phosphorite deposits occur within these successions. With respect to hydrocarbons the late Precambrian is considered a frontier for exploration, and significant accumulations of Precambrian occur in basins such as the South Oman Salt Basin. The primary research we will generate will include information about the geochemistry of specific successions of the South China Platform, information about their palaeogeographic history and information about basin development. Companies and industry funded research consortia will benefit from the approach developed in this research programme. Furthermore, the data generated, placed within the developing global 4D framework will allow us to export information to other basins which may have an economic potential (e.g., Oman, Brazil).