Speaker Bios (Current Season)

March 19th, 2026

  In carbonaceous black cherts of the ca. 3.0 Ga-old Farrel Quartzite and the ca 3.4 Ga Strelley Pool Formation in the Pilbara Craton, Western Australia, similar morphological assemblages of microfossils occur. The assemblages are composed of small and large spheroids, films, lenses and filaments. Among them, sac-like, flexible-walled large spheroids (FWLSs; not from the Strelley Pool Formation, at present) and lenses are of special interests. They are unusually large (up to 300 µm for sac-like spheroids and up to 100 µm for lenses) as primitive life. In addition, the FWLSs are morphologically equivalent to leiosphaerids, common organic-walled microfossils (OWMs) in the Proterozoic and the lenses are characterized by sheet-like appendages (flange) and their morphological asymmetricity and diversity. These two morphotypes can be extracted from host cherts by conventional acid maceration. Namely, they comprise the oldest OWMs. Noteworthy is that FWLSs have been reported also from the 3.2 Ga Clutha Formatio and the 2.5 Ga Gamohaan Formation, South Africa and lenses do from the 3.4 Ga Kromberg Formation and the 3.2 Ga Fig Tree Group, South Africa. In this talk, I will review morphology, occurrences, taphonomy, and geochemisty (molecular chemistry, isotopic composition, and distribution of bioessential elements) of the microfossils from the Farrel Quartzite and the Strelley Pool Formation in the Pilbara Craton and argue their biogenicity. Furthermore, I will try to constrain our understanding of these Archean “large” microfossils in the context of the early evolution of life and Earth’s surface environment.