Abstract

3.5Ga rocks in Western Australia and South Africa were in the past and are presently the target for remains of early life forms. Earliest field observations reported Stromatolites. The presence of photosynthesizing life forms in some earliest Archaean rocks is generally debated. The absence of oxygen in the Archaean atmosphere and Archaean oceans has likely supported anaerobic primitive Archaea such as found today in and around sea-floor Hydrothermal environments. These environments were created by intense meteorite bombardment of early Earth, and are believed by most recent researchers of life’s beginnings to have been the ideal environment for the synthesis of building blocks of life forms due to concentration of dissolved essential elements, the building blocks for encapsulation of a vesicle to start a cell of an organism in a warm environment. The earliest life forms described in the literature are associated with meteorite-impacted sediments, which may not be entirely accidental. It is debated as what was the precise influence of meteorites on cell formation or indeed whether there is any direct connection. It is agreed that hydrothermal environments where early life is believed to have begun were formed by meteorite impacts. Some microstructures resembling microbial cells observed in meteorites were reported as fossil microbes. Distinction between biogenic versus abiotically formed microstructures is a major obstacle in addressing the issue of earliest life forms.

Keywords:Archaean Eon; Pilbara craton; Barberton greenstone belt; Dresser formation; Apex basalt