Sedimentology of the ∼3.3 Ga upper Mendon Formation, Barberton Greenstone Belt, South Africa
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چکیده
منابع مشابه
Depositional and tectonic setting of the Archean Moodies Group, Barberton Greenstone Belt, South Africa.
The 3.22-3.10 Ga old Moodies Group, uppermost unit of the Swaziland Supergroup in the Barberton Greenstone Belt (BGB), is the oldest exposed, well-preserved quartz-rich sedimentary sequence on earth. It is preserved in structurally separate blocks in a heavily deformed fold-and-thrust belt. North of the Inyoka Fault, Moodies strata reach up to 3700 m in thickness. Detailed mapping, correlation ...
متن کاملPetrology and Geochemistry of 3.3 Ga Komatiites– Weltevreden Formation, Barberton Greenstone Belt
Introduction: Komatiites provide several ways of assessing the chemical and thermal evolution of the mantle. Komatiitic liquids are produced from very high degrees of partial melting of the deep mantle, and erupted as extremely fluid lavas. Komatiites are important in the study of the early Earth because they are a significant constituent of the Archean crust. It has been proposed that komatiit...
متن کامل3.5-Ga hydrothermal fields and diamictites in the Barberton Greenstone Belt-Paleoarchean crust in cold environments.
Estimates of ocean temperatures on Earth 3.5 billion years ago (Ga) range between 26° and 85°C. We present new data from 3.47- to 3.43-Ga volcanic rocks and cherts in South Africa suggesting that these temperatures reflect mixing of hot hydrothermal fluids with cold marine and terrestrial waters. We describe fossil hydrothermal pipes that formed at ~200°C on the sea floor >2 km below sea level....
متن کاملArchean spherule layers in the Barberton Greenstone Belt, South Africa: A discussion of problems related to the impact interpretation
This review of the current knowledge of impact spherule layers in the Barberton greenstone belt, together with new petrographic, geochemical, and field data on a number of impact and volcanic spherical particle horizons, highlight a number of problems with the proposition of frequent and large meteorite impacts during mid-Archean times. Field data indicate that some of the four previously propo...
متن کاملImplications of a 3.472-3.333 Gyr-old subaerial microbial mat from the Barberton greenstone belt, South Africa for the UV environmental conditions on the early Earth.
Modelling suggests that the UV radiation environment of the early Earth, with DNA weighted irradiances of about three orders of magnitude greater than those at present, was hostile to life forms at the surface, unless they lived in specific protected habitats. However, we present empirical evidence that challenges this commonly held view. We describe a well-developed microbial mat that formed o...
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ژورنال
عنوان ژورنال: Precambrian Research
سال: 2016
ISSN: 0301-9268
DOI: 10.1016/j.precamres.2016.06.003