| Abstract: | Two major periods of uranium mineralization are indicated by U-Pb isotope dating of uranium ores from collapse breccia pipes in the Grand Canyon region, northern Arizona. The Hack 2 and 3, Kanab North, and EZ 1 and 2 orebodies apparently formed in the interval of 200 ?? 20 Ma, similar to ages inferred for strata-bound, Late Triassic-hosted uranium deposits in southern Utah and northern Arizona. Samples from the Grand Canyon and Pine Nut pipes, however, indicate a distinctly older age of about 260 Ma. The clustering in ages for a variety of uranium deposits at about the age of the lower part of the Chinle Formation (Late Triassic) suggests that uranium in these deposits may have been derived by leaching from volcanic ash in the Chinle and mobilized by ground-water movement. Pb isotope ratios of galenas in mineralized pipes are more radiogenic than those of sulfides from either uranium-poor pipes or occurrences away from pipes. Fluids which passed through the pipes had interacted with the Proterozoic basement, possibly through the vertical fractures which influenced the location and evolution of the pipes themselves. -from Authors |
| Genre: | Article |
| ProdID: | 70016841 |
| Citation Author: | Ludwig, K. R.; Simmons, K. R. |
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| Citation End Page: | 1765 |
| Citation Issue: | 7 |
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| Citation Language: | English |
| Citation Larger Work Title: | Economic Geology |
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| Citation Number Of Pages: | 19 |
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| Citation Search Results Text: | U-Pb dating of uranium deposits in collapse breccia pipes of the Grand Canyon region; 1992; Article; Journal; Economic Geology; Ludwig, K. R.; Simmons, K. R. |
| Citation Start Page: | 1747 |
| Citation Volume: | 87 |
| Citation Year: | 1992 |
| Type: | citation/reference |
| Text: | U-Pb dating of uranium deposits in collapse breccia pipes of the Grand Canyon region; 1992; Article; Journal; Economic Geology; Ludwig, K. R.; Simmons, K. R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1992 00:00 -0600 |
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