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Rapid Growth of Magnesium-Carbonate Weathering Products in a Stony Meteorite from Antarctica

1988; American Association for the Advancement of Science; Volume: 242; Issue: 4877 Linguagem: Inglês

10.1126/science.242.4877.417

1095-9203

A. J. T. Jull, Cheng Sai, J. L. Gooding, M. A. Velbel,

Paleontology and Stratigraphy of Fossils

Nesquehonite, a hydrous magnesium carbonate, occurs as a weathering product on the surface of the Antarctic meteorite LEW 85320(H5 chondrite). Antarctic meteorites have resided on the earth for periods of 10(4) to 10(6) years, but the time needed for weathering products to form has been uncertain. Isotopic measurements of delta(13)C and delta(18)O indicate that the nesquehonite formed at near freezing temperatures by reaction of meteoritic minerals with terrestrial water and carbon dioxide. Results from carbon-14 dating suggest that, although the meteorite has been in Antarctica for at least 3.2 x 10(4) to 3.3 x 10(4) years, the nesquehonite formed after A.D.1950.