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Carmichael’s Concise Review


Coming Events 2017


Developmental Biology July 13–17, 2017 Minneapolis, MN


www.sdbonline.org/meeting?ResourceID=2715


Atomic Layer Deposition July 15–18, 2017


Denver, CO www.ald-avs.org


Materials Research Congress August 20–25, 2017 Cancun, Mexico www.mrs.org/imrc-2017


International Frontiers of Electron Microscopy in Materials Science


September 10–15, 2017 Johannesburg, South Africa http://femms2017.org


Microscience Microscopy Congress and EMAG2017 (mmc2017) July 3–6, 2017


Manchester, UK www.mmc-series.org.uk


Denver X-Ray Conference July 31–August 4, 2017


Big Sky, MT www.dxcicdd.com


Microscopy & Microanalysis 2017 August 6–10, 2017


St. Louis, MO www.microscopy.org 2018


Microscopy & Microanalysis 2018 August 5–9, 2018


Baltimore, MD www.microscopy.org 2019


Microscopy & Microanalysis 2019 August 4–8, 2019


Portland, OR www.microscopy.org 2020


Microscopy & Microanalysis 2020 August 2–6, 2020


Milwaukee, WI www.microscopy.org 2021


Microscopy & Microanalysis 2021 August 1–5, 2021


Pittsburgh, PA www.microscopy.org 2022


Microscopy & Microanalysis 2022 July 31–August 4, 2022


Portland, OR www.microscopy.org


T ere are no confi rmed microfossils older than 3,500 million years (Myr) on Earth. Recently Mathew Dodd, Dominic Papineau, Tor Grenne, John Slack, Martin Rittner, Franco Pirajno, Jonathan O’Neil, and Crispin Little may have identifi ed evidence of microbial life on Earth from at least 3,770 Myr ago or perhaps as long ago as 4,280 Myr [1]. T is would be relatively near the accepted time that the Earth was formed about 4,567 Myr ago! Microfossils that have biosignatures are considered evidence of early life. T ese take the form of tubes, knobs, fi laments, and/or branching fi laments that are likely biogenic. T ey are similar to younger microfossils in the same kinds of jasper rocks as well as to modern iron-oxidizing bacteria, and they are not the product of any known non-biologic chemical reactions. Dodd et al. pointed out that modern forms of these are known to form at hydrothermal vents on the ocean fl oor, and therefore life may have begun in a similar environment. A candidate location is a region in northern Québec, Canada, known as the Nuvvuagittuq Supracrustal Belt (NSB) that represents a fragment of the Earth’s primitive ocean fl oor with pillows of lava and where the metamorphosed remains of hydrothermal vents may be preserved as highly localized iron-rich carbonate rocks. Samples from the NSB were examined by light microscopy (transmitted and refl ected) as well as scanning electron microscopy (SEM) in back-scattered electron and secondary electron imaging modes. Other microscopy methods were correlated to analyze mineral targets including laser scanning confocal micro-Raman spectroscopy, electron probe micro-analysis, focused ion beam milling, and laser ablation inductively-coupled plasma mass spectrometry. To assess the biogenicity of the NSB putative microfossils, Dodd et al. considered if the microscopic structures they found could have possibly been formed by abiogenic mechanisms. Considering their structures as twisted iron-containing fi laments with microscopic dimensions, identical to younger microfossils and modern bacteria, and their


Did Life Begin Soon After the Earth Formed?


Stephen W. Carmichael Mayo Clinic , Rochester , MN 55905 carmichael.stephen@mayo.edu


More Meetings and Courses Check the complete calendar near the back of this magazine.


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Figure 1 : Haematite (containing ferric oxide) tubes from the NSB hydrothermal vent deposits. Photo credit: Matthew Dodd.


doi: 10.1017/S1551929517000608 2017 July


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