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Our Earth’s ancient history is best studied from the Archaean time period. During the course of Earth’s evolution from c. 4.0 Ga to 2.5 Ga, significant geologic events have led to pivotal changes on our early Earth. These are preserved in the rock record of ancient cratons. Major highlights are volcanic eruptions (i.e., mafic-ultramafic) noted mostly under sub-marine settings, association of deep-water sedimentary rocks, widespread presence of chemical sedimentary rocks and emplacement of tonalite- trondhjemite-granodiorite (TTG) suite together with explosive style felsic magmatism. These geologic processes are common to almost all Archaean cratons. Likewise, preservation of microbial lifeforms from metasedimentary rocks of the Archaean record provide us evidence for an early emergence life in sub-surface environments. Few snapshots of these key early Earth processes will be presented from Greenland, South Africa, Australia, India and Zimbabwe. However, what remains at the core of this research aspect is collective evaluation of facts based on field geology, geochronology, geochemistry, radiogenic isotopes, stable isotopes etc. This has led to an overall understanding related to early Earth conditions from the Archaean times. |