Publikationsdatum:
2004-12-18
Beschreibung:
Archean rocks may provide a record of early Earth environments. However, such rocks have often been metamorphosed by high pressure and temperature, which can overprint the signatures of their original formation. Here, we show that the early Archean banded rocks from Isua, Akilia, and Innersuartuut, Greenland, are enriched in heavy iron isotopes by 0.1 to 0.5 per mil per atomic mass unit relative to igneous rocks worldwide. The observed enrichments are compatible with the transport, oxidation, and subsequent precipitation of ferrous iron emanating from hydrothermal vents and thus suggest that the original rocks were banded iron formations (BIFs). These variations therefore support a sedimentary origin for the Akilia banded rocks, which represent one of the oldest known occurrences of water-laid deposits on Earth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dauphas, Nicolas -- van Zuilen, Mark -- Wadhwa, Meenakshi -- Davis, Andrew M -- Marty, Bernard -- Janney, Philip E -- New York, N.Y. -- Science. 2004 Dec 17;306(5704):2077-80.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Origins Laboratory, Department of the Geophysical Sciences, and Enrico Fermi Institute, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA. dauphas@uchicago.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15604404" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Digitale ISSN:
1095-9203
Thema:
Biologie
,
Chemie und Pharmazie
,
Informatik
,
Medizin
,
Allgemeine Naturwissenschaft
,
Physik
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