Geological and geochemical record of 3400-million-year-old terrestrial meteorite impacts.
Science
; 245(4921): 959-62, 1989 Sep 01.
Article
em En
| MEDLINE
| ID: mdl-17780536
ABSTRACT
Beds of sand-sized spherules in the 3400-million-year-old Fig Tree Group, Barberton Greenstone belt, South Africa, formed by the fall of quenched liquid silicate droplets into a range of shallow-to deep-water depositional environments. The regional extent of the layers, their compositional complexity, and lack of included volcanic debris suggest that they are not products of volcanic activity. The layers are greatly enriched in iridium and other platinum group elements in roughly chondritic proportions. Geochemical modeling based on immobile element abundances suggests that the original average spherule composition can be approximated by a mixture of fractionated tholeiitic basalt, komatiite, and CI carbonaceous chondrite. The spherules are thought to be the products of large meteorite impacts on the Archean earth.
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MEDLINE
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En
Revista:
Science
Ano de publicação:
1989
Tipo de documento:
Article