Extraterrestrial impact episodes and Archaean to early Proterozoic (3.8-2.4 Ga) habitats of life

Andrew Glikson*

*Corresponding author for this work

    Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

    1 Citation (Scopus)


    The terrestrial record is punctuated by major clustered asteroid and comet impacts, which affected the appearance, episodic extinction, radiation, and reemergence of biogenic habitats. Here I examine manifest and potential extraterrestrial impact effects on the onset and evolution of Archaean to early Proterozoic (3.8-2.4-Ga) habitats, with reference to the Pilbara (Western Australia) and Kaapvaal (eastern Transvaal) Cratons. The range of extraterrestrial connections of microbial habitats includes cometary contribution of volatiles and amino acids, sterilization by intense asteroid and comet bombardment, supernova and solar flares, and impacttriggered volcanic and hydrothermal activity, tectonic modifications, and tsunami effects. Whereas cometary dusting of planetary atmosphere may contribute little modified extraterrestrial organic components, large impact effects result in both incineration of organic molecules and shock synthesis of new components. From projected impact incidence, ∼1.3% of craters >100 km and ∼3.8% of craters >250 km have to date been identified for post-3.8-Ga events, due to the mm-scale of impact spherules and the difficulty in their identification in the field -only the tip of the iceberg is observed regarding the effects of large impacts on the Precambrian biosphere, to date no direct or genetic relations between impacts and the onset or extinction of early Precambrian habitats can be confirmed. However, potential relations include (1) ∼ 3.5-3.43 Ga-intermittent appearance of stromatolite-like structures of possible biogenic origin on felsic volcanic shoals representing intervals between mafic volcanic episodes in rapidly subsiding basins, a period during which asteroid impacts are recorded; (2) ∼ 3.26-3.225 Ga-impact-triggered crustal transformation from mafic-ultramafic volcanic environments to rifted troughs dominated by felsic volcanics and turbidites, marked by a major magmatic peak, resulting in extensive hydrothermal activity and development of sulphate-reducing microbes around anoxic submarine fumarole ("black smoker") environments; (3) ∼ 2.63-2.47 Ga-impact-triggered tsunami effects in oxygenated carbonate-dominated epicontinental and intracratonic environments (Hamersley and Transvaal basins); (4) in at least three instances onset of ferruginous sedimentation closely following major impact events, possibly signifying hydrothermal Fe-enrichment related to impact-triggered volcanic activity. Due to limitations on the phylogenic speciation of Precambrian stromatolite and bacterial populations, major impact-extinction-radiation relations are identified only from the late Proterozoic, beginning with the ∼0.59-Ga Acraman impact and continuing with major Phanerozoic extinctions and radiations associated with impact and volcanic events in the late Ordovician, late Devonian, late Triassic, late Jurassic, and late Cretaceous.

    Original languageEnglish
    Title of host publicationComets and the Origin and Evolution of Life
    EditorsPaul Thomas, Christopher Chyba, P. Christopher
    Number of pages31
    Publication statusPublished - 2006

    Publication series

    NameAdvances in Astrobiology and Biogeophysics
    ISSN (Print)1610-8957
    ISSN (Electronic)1613-1851


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