Neoproterozoic banded iron-formation interbedded with diamictite in Namibia and “Snowball Earth”hypothesis
نویسندگان
چکیده
منابع مشابه
A neoproterozoic snowball earth
Negative carbon isotope anomalies in carbonate rocks bracketing Neoproterozoic glacial deposits in Namibia, combined with estimates of thermal subsidence history, suggest that biological productivity in the surface ocean collapsed for millions of years. This collapse can be explained by a global glaciation (that is, a snowball Earth), which ended abruptly when subaerial volcanic outgassing rais...
متن کاملA major perturbation of the carbon cycle before the Ghaub glaciation (Neoproterozoic) in Namibia: Prelude to snowball Earth?
[1] A large (11–15%) negative shift in dC is observed in shallow water carbonates directly beneath Neoproterozoic glacial deposits (or correlative disconformity) in northwest Namibia ascribed to a snowball Earth. Reproducibility and stratigraphic concordance of this anomaly in 16 sections across the ancient continental shelf support a primary origin, and field relations show it predates the fal...
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We hypothesize that a demographic and ecological effect of Neoproterozoic ‘snowball Earth’ glaciations was to increase the fitness of group-level traits and consequently the likelihood of the evolution of macroscopic form. Extreme and repeated founder effects raised genetic relatedness – and therefore the influence of kin selection on the individuals within a group. This was permissive for the ...
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The Neoproterozoic glacial intervals represent one of the most curious expressions of Earth’s climate. Despite the popularity of the hard “Snowball” hypothesis in the popular press, the scientific community remains divided over the extent of the Neoproterozoic glaciations, the age of the glaciations, the number of glacial events and the triggering mechanism for the glaciations. A major, and yet...
متن کاملBiologically induced initiation of Neoproterozoic snowball-Earth events.
The glaciations of the Neoproterozoic Era (1,000 to 542 MyBP) were preceded by dramatically light C isotopic excursions preserved in preglacial deposits. Standard explanations of these excursions involve remineralization of isotopically light organic matter and imply strong enhancement of atmospheric CO(2) greenhouse gas concentration, apparently inconsistent with the glaciations that followed....
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ژورنال
عنوان ژورنال: The Journal of the Geological Society of Japan
سال: 2004
ISSN: 0016-7630,1349-9963
DOI: 10.5575/geosoc.110.6.xi_xii