North China craton: A unique window into Earth&#39;s middle age

GSTDTAP

项目编号	NE/R010129/1
	North China craton: A unique window into Earth's middle age
	Graham Anthony Shields-Zhou
主持机构	University College London
项目开始年	2018
	2018-07-01
项目结束日期	2021-06-30
资助机构	UK-NERC
项目类别	Research Grant
项目经费	649014(GBP)
国家	英国
语种	英语
英文摘要	Biological evolution is commonly viewed as a gradual and largely predictable journey from simple, single-celled bacterial ancestors, to ever larger and more complex life forms. Similarly, the evolution of Earth's atmosphere and oceans (which is considered to play a crucial role in biological evolution) is generally viewed as a gradual, albeit stepwise, trajectory towards greater oxygenation, with each rise occurring in tandem with, and facilitating progressive increases in, biological size and complexity. This paradigm of a monotonous progression towards modern conditions and the implied linkage between key evolutionary steps and oxygenation has recently been challenged. However, relevant data to resolve the issue are scarce and ambiguous. Geochemical estimates of atmospheric oxygen levels during the Proterozoic range widely, and our understanding of ocean oxygenation levels have complicated this picture further, indicating a dynamic environment fluctuating between abundant oxygen levels and no oxygen (anoxic). As such, links between Earth surface oxygenation and early biological evolution have been particularly difficult to unravel. Recently discovered, large eukaryote fossils from North China are particularly difficult to understand in the light of current understanding of Earth's atmospheric evolution which suggests exceedingly low oxygen levels at this time of diversification. Studies of early Earth environments have been severely hampered by the poor quality of geological samples (burial and subsequent exposure at the Earth's surface can destroy the primary geochemistry of rocks). With this in mind, we propose a multidisciplinary study of superbly preserved mid-Proterozoic samples from the North China craton, largely obtained by drilling, to reconstruct the oxygenation history of the ocean and to investigate how nutrients in the ocean interact with this history. This will be combined with new paleontological data to demonstrate how nutrients and redox constrained the early evolution of eukaryotes, the ancestral lineage of all extant animals. By specifically targeting the best quality samples that can be obtained across this crucial interval in the history of life on Earth, the research outlined in this proposal will shed fundamental new insight into the enigmatic mid-Proterozoic Earth system, including why it took so long for large, complex multicellular eukaryotes to dominate marine ecosystems. In this project we propose an integrated approach to test assumed linkages between Earth surface conditions and biological evolution during the mid-Proterozoic (~1.7-0.9 Ga). A combination of fieldwork and targeted shallow drilling of demonstrably preserved rocks on the North China craton will provide the basis for a detailed study of a crucial interval of early biological diversification. In particular, we will utilize key redox and novel nutrient tracers, organic-walled fossils and molecular biomarkers. Reconstruction of early marine ecosystems and their environment will allow us to test highly topical hypotheses relating to the delayed evolution of biological complexity on Earth, including the potential roles of nutrient availability and Earth surface oxygenation.
来源学科分类	Natural Environment Research
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/87168
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Graham Anthony Shields-Zhou.North China craton: A unique window into Earth's middle age.2018.