Th-Pb and U-Pb Dating of Ore-Stage Calcite and Paleozoic Fluid Flow

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Science  26 Jan 1996:
Vol. 271, Issue 5248, pp. 491-493
DOI: 10.1126/science.271.5248.491


Thorium-232-lead-208 and uranium-238-lead-206 radiometric ages for ore-stage calcite show that Mississippi Valley-type (MVT) ore deposits can form in distinct tectonic settings. An age of 251 ± 11 million years for the Jumbo Mine in Kansas, United States, is in agreement with other ages for MVT deposits in the midcontinent of North America. The similarity of ages of these deposits supports the concept that they formed in response to fluid flow during the late Paleozoic Alleghenian-Ouachita orogeny. An age of 351 ± 15 million years for Twelve Mile Bore and Bloodwood-Kapok deposits in Australia indicates that these MVT ores were deposited in a rifting environment.