| Abstract: | K-feldspar Pb and whole rock Nd isotopic analyses from 25 Mesozoic and Cenozoic plutonic rocks and two gneisses from NE Washington and northern Idaho are used to elucidate the age and nature of the concealed cratonic basement. The plutons form two highly distinct isotopic groups: Group I have isotopic compositions suggesting derivation from rocks of the Belt Supergroup or their metamorphosed equivalents, Group II have highly retarded Pb isotopic compositions relative to the present day crustal average and require a source region with long-term U depletion, characteristic of cratonic lower crust. A U-Pb zircon upper intercept age of c2600 Ma obtained from one of the Group II samples, together with Sm-Nd data from the gneisses, indicates possible late-Archean crust at depth, which acted as a source region for Eocene extension-related plutonism. -from Authors |
| Genre: | Article |
| ProdID: | 70016896 |
| Citation Author: | Whitehouse, M. J.; Stacey, J. S.; Miller, F. K. |
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| Citation End Page: | 701 |
| Citation Issue: | 6 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Geology |
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| Citation Number Of Pages: | 11 |
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| Citation Search Results Text: | Age and nature of the basement in northeastern Washington and northern Idaho: isotopic evidence from Mesozoic and Cenozoic granitoids; 1992; Article; Journal; Journal of Geology; Whitehouse, M. J.; Stacey, J. S.; Miller, F. K. |
| Citation Start Page: | 691 |
| Citation Volume: | 100 |
| Citation Year: | 1992 |
| Type: | citation/reference |
| Text: | Age and nature of the basement in northeastern Washington and northern Idaho: isotopic evidence from Mesozoic and Cenozoic granitoids; 1992; Article; Journal; Journal of Geology; Whitehouse, M. J.; Stacey, J. S.; Miller, F. K. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1992 00:00 -0600 |
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