Fundamental molecules of life are suggested to be formed, proliferated, and evolved through microscopic dissipative structuring and autocatalytic replication under the UV-C solar spectrum prevalent at Earth’s surface throughout the Archean. Evidence is given in the numerous salient characteristics of these, including their strong absorption in this spectral region, their rapid nonradiative deca...

Molecular fossils of biological lipids are preserved in 2700-million-year-old shales from the Pilbara Craton, Australia. Sequential extraction of adjacent samples shows that these hydrocarbon biomarkers are indigenous and syngenetic to the Archean shales, greatly extending the known geological range of such molecules. The presence of abundant 2alpha-methylhopanes, which are characteristic of cy...

The effect of hydrogen on the rate of phototrophic Fe(II) oxidation by two species of purple bacteria was measured at two different bicarbonate concentrations. Hydrogen slowed Fe(II) oxidation to varying degrees depending on the bicarbonate concentration, but even the slowest rate of Fe(II) oxidation remained on the same order of magnitude as that estimated to have been necessary to deposit the...

The size of the marine sulfate reservoir has grown through Earth's history, reflecting the accumulation of oxygen into the atmosphere. Sulfur isotope fractionation experiments on marine and freshwater sulfate reducers, together with the isotope record, imply that oceanic Archean sulfate concentrations were <200 microM, which is less than one-hundredth of present marine sulfate levels and one-fi...

The record of terrestrial impact events is incomplete with no Archean structures discovered, despite the expected abundance collisions that must have occurred. Because been identified, necessary conditions to preserve an structure longer than 2 Byr are unknown. One significant effect shock metamorphism physical properties target rocks change, resulting in distinctive geophysical signatures stru...

The isotope record of sedimentary sulfides can help resolve the history of oxygen accumulation into the atmosphere. We measured sulfur isotopic fractionation during microbial sulfate reduction up to 88 degrees C and show how sulfate reduction rate influences the preservation of biological fractionations in sediments. The sedimentary sulfur isotope record suggests low concentrations of seawater ...

The western segment of the Churchill Province of Canada, west of Hudson Bay, was divided by Hoffman (1988) into the Archean Rae and Hearne domains separated by the Snowbird Tectonic Zone (STZ) (Fig. 1), defined on the basis of potential field data. The Hearne domain has been further subdivided into the northern Hearne and southern Hearne subdomains (Davis et al., this volume). There is little d...

The approximately 3,450-million-year-old Strelley Pool Formation in Western Australia contains a reef-like assembly of laminated sedimentary accretion structures (stromatolites) that have macroscale characteristics suggestive of biological influence. However, direct microscale evidence of biology--namely, organic microbial remains or biosedimentary fabrics--has to date eluded discovery in the e...

Studies of lithotectonic formations within the Keivy domain NE Baltic Shield have shown that was tectonically overlapped by adjacent microcontinents during regional collision processes in Late Archean. As a consequence, continental crust submerged, relative to other blocks crust, and described acquired features classical median massif. Surrounded on all sides systems, massif entered cratonizati...