ORGANIC-WALLED MICROFOSSILS FROM BASINAL TO SUPRATIDAL MICROBIALITE FACIES ACROSS THE NEOARCHEAN CAMBELLRAND-MALMANI CARBONATE PLATFORM, KAAPVAAL CRATON, SOUTH AFRICA

The information contained within the Archean rock record has the potential to reveal the only origin of life scenario that we know with certainty exists: the story of life’s emergence and early evolution on Earth. Unfortunately, due to the nature of the rock cycle, the story hidden within the Archean rock record is fragmented and incomplete, but that does not mean there is no paleontological and geochemical evidence regarding life in the Archean to explore. Here we present preliminary results from a study of microfossils preserved within microbialite facies from across the Campbellrand-Malmani carbonate platform of the Neoarchean (2.68-2.50 Ga) Kaapvaal Craton, South Africa. The Campbellrand-Malmani carbonate platform is remarkably unaltered for its age. The microfossils presented here were found in microbialite facies from across the platform, and, therefore, represent a snapshot of marine basinal to supratidal microbial ecosystems as they existed during the late Archean era, just before the Great Oxidation Event, as the Campbellrand-Malmani carbonate platform gradually underwent its final drowning.

The ultimate purpose of this work is to describe and compare some of the best-preserved Neoarchean microbial ecosystems that existed during this pivotal time in the coevolution of our planet and the prokaryotic life that thrives upon it. In order to do so, we will describe the microbial morphospecies observed in the collected samples, use biostatistical analyses to describe the communities those morphospecies resided in, analyze mineralogical and stable isotope data to determine what metabolic processes may have existed in those communities, and compare these data across depositional environments to reveal previously unknown details of the Archean biosphere. This will be the first work to describe and compare both physiological and ecological characteristics in Archean microbial communities across an environmental gradient such as the Campbellrand-Malmani carbonate platform.