Details of Award
NERC Reference : NE/C510883/1
Critical testing of suggested occurrences of early (3500Ma year old) life.
Grant Award
- Principal Investigator:
- Professor M. D. Brasier, University of Oxford, Earth Sciences
- Co-Investigator:
- Dr D Wacey, University of Oxford, Earth Sciences
- Grant held at:
- University of Oxford, Earth Sciences
- Science Area:
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Biodiversity
- Science Topics:
- Palaeobiology
- Biogeochemical Cycles
- Abstract:
- Locating the first evidence for life on Earth is a question of major scientific interest but considerable difficulty. It needs a well-constrained geological context, evidence for biology-like shape (morphology), chemical evidence for metabolism, plus falsification of plausible non-biological origins. We have questioned (Brasier et al. 2002, Nature 416, 76-81) the context and morphology of the world' oldest microfossil' assemblage from the 3460 Ma old Apex chert of Western Australia and others have questioned the reliability of biomarkers such as carbonaceous composition and carbon isotopes from ~3800 Ma rocks in Greenland. Microbial borings into ancient rocks have considerable potential in the search for early life. They can preserve not just cellular morphology but evidence for behaviour, e.g., preferential substrate selection, dissolution and metabolism. While such 'rock munching' microborings are only known from limestones younger than c.1500 Ma, microtubules of suggested microbial origin have recently been reported from 3500 - 3300 Ma old pillow lavas in South Africa (Fumes et al. 2004, Science 304, 578-581). We have discovered a new assemblage of microtubular structures (~5-9 micron in modal diameters) that will help to test this story. They occur within ~3500 Million year old pebbles and sand grains that come from the earliest known shoreline and beach deposits on Earth. Our microtubules structures closely resemble those from South Africa except that ours: 1, occur within shallow marine sediments (with potential to characterise any surface water biology); 2, suggest selective 'behaviour' with respect to differing pebble lithologies (i.e. potential to characterise any early 'biological processing' of rocks); 3, associate with strong chemical gradients including Earth's oldest phosphatic sediments (i.e., potential for characterisation of S, Fe and P-related biological processes); 4, are of two distinct morphologies; 5, are open as well as infilled tubes (i.e., potential for fluid inclusion studies of the earliest conditions). The aim of this project is to characterise the context and evidence for these microtubules from ~3500 Ma old sediments and lavas in Australia. We plan to test whether our microtubules can be sustained as Earth's oldest putative 'microfossil' assemblage that formed on an ancient land surface and/or upon the shallow seafloor by a process of bacterial boring into glassy pebbles. The first objective is to resolve just where and when these microtubules were formed, to see if they are restricted to certain kinds of rock type, and are not later contaminants. The second aim is to test how they formed, by detailed mapping of their morphology and geochemistry at the micron to nanomicron scale, and by controlled laboratory experiments. The final objective is to explore whether chemical zonations in these most ancient pebbles could reflect evidence for ancient, bacteria-like, metabolic processes. The Australian rocks to be tested here share similarities with habitats now being searched for life on Mars: rounded pebbles plus iron rich mineral phases, laid down in a high-energy, poorly-oxygenated, shallow water setting some 3500 Ma years ago. Our work will therefore help to test the approaches needed for later Mars sample return missions. Positive evidence for biological microboring into metaliferous silica at 3500 Ma, if confirmed, would point to early life's involvement in rock weathering and chemical cycles. Activities of bacterial metabolism, if present, will also have major implications for biosphere evolution, for the atmospheric history of the planet, and even for our place in the universe.
- NERC Reference:
- NE/C510883/1
- Grant Stage:
- Completed
- Scheme:
- Standard Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Standard Grant
This grant award has a total value of £283,811
FDAB - Financial Details (Award breakdown by headings)
| Total - T&S | Total - Staff | Total - Other Costs | Total - Equipment | Total - Indirect Costs |
|---|---|---|---|---|
| £19,250 | £132,002 | £59,029 | £12,808 | £60,721 |
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