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Meteoric sphaerosiderite lines and their use for paleohydrology and paleoclimatology

Greg A. Ludvigson·Luis A. Gonzalez·R.A. Metzger·B.J. Witzke·Richard L. Brenner·A.P. Murillo·T. S. White
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Abstract

Sphaerosiderite, a morphologically distinct millimeter-scale spherulitic siderite (FeCO 3 ), forms predominantly in wetland soils and sediments, and is common in the geologic record. Ancient sphaerosiderites are found in paleosol horizons within coal-bearing stratigraphic intervals and, like their modern counterparts, are interpreted as having formed in water-saturated environments. Here we report on sphaerosiderites from four different stratigraphic units, each of which has highly variable 13 C and relatively stable 18 C compositions. The unique isotopic trends are analogous to well-documented meteoric calcite lines, which we define here as meteoric sphaerosiderite lines. Meteoric sphaerosiderite lines provide a new means of constraining ground-water δ 18 O and thus allow evaluation of paleohydrology and paleoclimate in humid continental settings.

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Greg A. Ludvigson, Luis A. Gonzalez, R.A. Metzger, B.J. Witzke, Richard L. Brenner, A.P. Murillo, T. S. White. 1998. Meteoric sphaerosiderite lines and their use for paleohydrology and paleoclimatology. https://doi.org/10.1130/0091-7613(1998)026%3C1039%3Amslatu%3E2.3.co%3B2

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