1. THE ARCHEAN - PROTEROZOIC TRANSITION
The role of serpentinization in the promotion of biogenic activity
Prof. W.R. Church
Prof. W.R. Church

2. Introduction
In this talk I will try to explain how oxygen producing biotic activity fed by energy from the olivine - serpentine reaction caused the removal of CH4 and H2S from, and the introduction of oxygen into the Archean atmosphere, eventually leading to the development of ‘greenhouse’ photosynthetic biogenesis during the Lower Proterozoic
The talk is a modification of the paper by Melezhik et al “Emergence of the aerobic biosphere during the Archean - Proterozoic tranisiton: Challenges of future research”, GSA Today, 15, 11, p
Professor William R. Church

3. The Archean
Olivine in the form of komatiite is abundant in the Archean, as is cherty magnetite iron
Given the abundance of olivine as a component of the komatiite in the Archean, is it possible that the
Archean iron formations are a
by-product of the serpentinization process?

4. Serpentinization as a geochemical energy source for biotic activity
The conversion of olivine to serpentine is an exothermic reaction
Serpentinization is accompanied by the oxygenic conversion of the fayalite component of olivine to magnetite and silica - serpentinites are therefore invariably magnetic.
If so, where does the oxygen for the fayalite conversion come from?
Could the oxygen be biotic in origin, and could the serpentinization reaction provide the energy for biotic reduction of atmospheric CO2.
Serpentinization of Oceanic Peridotites: Implications for Geochemical Cycles and Biological Activity Gretchen L. Früh-Green, James A.D. Connolly, and Alessio Plas. Geophysical Monograph 144 The sub sea‑floor biosphere at Mid-ocean ridges.

5. The biotic removal of H2S and CH4 from the atmosphere
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6. Sulphate reduction and sulphur fractionation in oceanic hydrothermal systems
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7. The lithologic character of the Lower Prototerozoic
The Huronian and Medicine Bow Lower Proterozoic successions
Aluminosilicates and weathering
The location of the first red beds
The Gowganda glaciation

8. Photosynthesis and the Oxyatmoversion event
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9. The Lomagundi-Jatuli event
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10. Location map of the Pechenga greenstone belt and the Onega basin

13. The Shunga Event Summarize any actions required of your audience
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14. Conclusions Summarize any actions required of your audience
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