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Were kinetics of Archean calcium carbonate precipitation related to oxygen concentration?Archean carbonates commonly contain decimetre- to metre-thick beds consisting entirely of fibrous calcite and neomorphosed fibrous aragonite that precipitated in situ on the sea floor. The fact that such thick accumulations of precipitated carbonate are rare in younger marine carbonates suggests an important change in the modes of calcium carbonate precipitation through time. Kinetics of carbonate precipitation depend on the concentration of inhibitors to precipitation that reduce crystallization rates and crystal nuclei formation, leading to kinetic maintenance of supersaturated solutions. Inhibitors also affect carbonate textures by limiting micrite precipitation and promoting growth of older carbonate crystals on the sea floor. Fe2+, a strong calcite-precipitation inhibitor, is thought to have been present at relatively high concentrations in Archean seawater because oxygen concentrations were low. The rise in oxygen concentration at 2.2-1.9 Ga led to the removal of Fe2+ from seawater and resulted in a shift from Archean facies, which commonly include precipitated beds, to Proterozoic facies, which contain more micritic sediment and only rare precipitated beds.
Document ID
20040089689
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
Authors
Sumner, D. Y.
(Massachusetts Institute of Technology 02139 United States)
Grotzinger, J. P.
Date Acquired
August 21, 2013
Publication Date
February 1, 1996
Publication Information
Publication: Geology
Volume: 24
Issue: 2
ISSN: 0091-7613
Subject Category
Geosciences (General)
Funding Number(s)
CONTRACT_GRANT: EAR-9058199
CONTRACT_GRANT: NAGW-2795
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Exobiology

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