Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published February 1996 | metadata_only
Journal Article

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. Fe^(2+), 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 Fe^(2+) 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.

Additional Information

© 1996 Geological Society of America. Manuscript received July 10, 1995. Revised manuscript received November 13, 1995. Manuscript accepted November 22, 1995. Supported by a National Science Foundation Graduate Fellowship and the Gretchen L. Blechschmidt Fund of the Geological Society of America (Sumner) and by NASA grant NAGW-2795 and NSF grant EAR-9058199 (Grotzinger). We thank Lynn Walter for pointing out the experimental work on Fe calcite precipitation, and James Kasting and an anonymous reviewer for helpful comments.

Additional details

August 22, 2023
August 22, 2023