Tetravalent Uranium in Calcite

X-ray absorption spectroscopy and x-ray fluorescence microprobe studies of 35-million-year-old calcite from a Mississippi Valley-type zinc ore deposit indicate substitution of tetravalent uranium for divalent calcium. Thus, tetravalent uranium has a stable location in calcite deposited under reducin...

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Veröffentlicht in:	Science (American Association for the Advancement of Science) 1998-08, Vol.281 (5379), p.971-973
Hauptverfasser:	Sturchio, N. C., Antonio, M. R., Soderholm, L., Sutton, S. R., Brannon, J. C.
Format:	Artikel
Sprache:	eng
Schlagworte:	ABSORPTION SPECTROSCOPY AGE ESTIMATION AQUIFERS Atoms CALCITE CALCIUM Carbon dating Composition Coordination Earth sciences Earth, ocean, space Environment ENVIRONMENTAL SCIENCES Exact sciences and technology FLUORESCENCE Geophysical research Groundwater Line spectra Mineralogy Minerals Minerals (Geology) MISSISSIPPI Non silicates Observations Oxidation Paleontology Reference Materials Rock-forming minerals Rocks URANIUM Water X ray fluorescence ZINC ORES
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Beschreibung
Zusammenfassung:	X-ray absorption spectroscopy and x-ray fluorescence microprobe studies of 35-million-year-old calcite from a Mississippi Valley-type zinc ore deposit indicate substitution of tetravalent uranium for divalent calcium. Thus, tetravalent uranium has a stable location in calcite deposited under reducing conditions. This result validates uranium-series dating methods (including uranium/lead dating) for ancient calcite and shows that calcite provides a sink for uranium in deep groundwater aquifers and anoxic lacustrine and marine basins.
ISSN:	0036-8075 0193-4511 1095-9203
DOI:	10.1126/science.281.5379.971