by Anthony R. Prave, Kristin Bergmann, Simone A. Kasemann, Francis A. MacDonald, Sarah Pruss, Sarah Pruss, Catherine V. Rose, Andreas Nduutepo, Ricardo I. F. Trindade, Maoyan Zhu

The Neoproterozoic Era (1000 - 541 Ma) is one of the most dramatic in Earth history: metazoans evolved, the supercontinent Rodinia formed and broke apart, the global carbon cycle underwent high-amplitude fluctuations, oxygen concentrations rose and climate experienced at least two episodes of worldwide glaciation. However, the discontinuous and fragmented nature of outcrop-based studies has hindered developing quantitative models of Earth system functioning during that Era. This proposal will begin to rectify this scientific shortcoming by obtaining 13 cores, each from 150 to 550 m, through the archetype successions that record the environmental and biogeochemical context during which animals evolved. The specific targets are the Ediacaran-Cambrian transition (ECT; c. 560-530 Ma) strata of west Brazil (Corumbá Group), south China (Doushantuo, Dengying and equivalent formations) and south Namibia (Nama Group). Our objective is to create a core network of correlative ECT strata that will enable constructing a highly resolved, temporally constrained geobiological, stratigraphic and geochemical database, as well as provide a legacy archive for future research. The goal is to understand the drivers of the Neoproterozoic Earth system revolution: it began with simple eukaryotes that populated Earth during the preceding billion years of the Mesoproterozoic, underwent multiple Snowball Earth events, and emerged with the oxygenated, diverse ecosystems of the Cambrian. The three-nation drilling programme will be undertaken sequentially: the successful FAPESP award to R Trindade will enable drilling to commence in Brazil in 2018, with successive drilling in China and Namibia. The identified drill sites are: the shallow-to-deeper marine rocks at Sobramil Harbour and Laginha Mine in Brazil, the shallow-marine rocks at Dahai, Huangniuya and Beidoushan and their deeper slope equivalents at Longhizui, Piyuancum and Tongle in south China, and the shelf-to-basin transect recorded in the Pokkenbank, Tierkloof, Witputs Nord, Swartpunt and Orange River localities in south Namibia. All cores will be split into halves with one-half being archived in repositories within each of the target nations and used for research purposes by GRIND-ECT scientists and for education and training for national capacity building and outreach activities. The other half of all cores will be shipped to the the Federal Institute for Geosciences and Natural Resources in Berlin-Spandau, Germany, for permanent archiving. The cores at all the repositories will be available for future research and education activities and will mark the first step towards creating an on-shore continental scientific drilling archive that will match in stature that of the IODP.

• GRIND-ECT has three main scientific objectives:
• Construct a highly resolved temporal framework that will lead to the development of age models for the ECT.
• Refine the patterns of biotic evolution of organic-walled and mineralised microfossils, metazoans and trace fossils and identify the links between and test hypotheses about biological evolution and environmental change.
• Determine the palaeoenvironmental and biogeochemical conditions that led to the rise of oxygen and distinguish cause-and-effect relationships and basin-specific versus global-scale secular trends in geochemical and stable isotope patterns. We will use our findings to answer these key unresolved questions:
• What was the timing and rates of the advent, expansion and extinction of Ediacaran biota?
• What was the environmental context and timing for changing skeletal mineralogy and diversification of biomineralising metazoa?
• What was the pattern of oxygenation (globally and regionally) and how does it relate to other geochemical patterns? Was there a Neoproterozoic oxygenation event?
• What was the timing, duration, genesis and implications for the global C cycle and the large amplitude C-isotope excursions in late Ediacaran to Cambrian strata?
• Is the Ediacaran-Cambrian boundary a synchronous worldwide biological event or a lengthy episode of biological innovation? This approach will provide high-resolution sedimentological, geochemical, palaeobiological, palaeomagnetic, geochronological and cyclostratigraphic data to determine rates of change of biogeochemical processes, evolutionary tempos and the spatio-temporal record of oxygenation in a spectrum of environmental settings.

Africa, Asia, Brazil, Cambrian Explosion, China, ECT, Ediacaran, Evolution, GRIND, Namibia, Neoproterozoic, South America

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