THE IMPOSTERS: Younger Biological Contaminants and Non-Biological Artefacts
This section contains images of the various types of contaminants and artefacts that may be confused for ancient life in early Archean rocks. Contaminants may be introduced by hydrothermal and metamorphic fluids at various stages throughout the (often complex) history of the host rock unit, or they may be introduced by weathering whenever the rock unit is exposed at or near the surface of the Earth. Contaminants may be very young indeed, introduced by modern soils or microbes, or even from human activity during sample collection, processing and preparation.
Various inorganic structures can also be confused for ancient life. In the main, these are purely chemical precipitates that can be misinterpreted as microfossils and/or biological stromatolites. Some types of physical sedimentary (e.g., ripples) and deformational structures (e.g., micro-folds) can also be mistaken for biological stromatolites, whilst non-biological processes can mimic biological isotope signatures (see also Fig. A35).
KeywordsGreenstone Belt Hydrated Calcium Silicate Precambrian Research Tectonic Fabric Ancient Life
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