| Abstract: | Analyses of oxygen isotopes in whole-rock samples of 58 Precambrian and Phanerozoic trondhjemites and siliceous gneisses and of 28 cogenetic mafic to intermediate rocks from North America, Fennoscandia, and southern Africa give the following results: 1. (1) 47 trondhjemites, tonalites, and mostly Archean acidic gneisses that apparently are not isotopically disturbed show an overage ?? 15O of +7.3??? and a range of 5.2-8.9???; 11 other samples are slightly to moderately disturbed and show higher values; and 2. (2) the mafic rocks show a wide range of ??-values, from about 0-9??? but the undisturbed ones give an average ?? 18O of 5.2???. The ?? 18O values of the trondhjemitic intrusives and siliceous gneisses of similar composition are lower than those of most granitic rocks and support models for derivation of these rocks from basaltic parents. This approach, however, cannot be used to determine if individual bodies formed by differentiation or by partial melting. ?? 1976. |
| Genre: | Article |
| ProdID: | 70011166 |
| Citation Author: | Barker, F.; Friedman, I.; Hunter, D. R.; Gleason, J. D. |
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| Citation End Page: | 557 |
| Citation Issue: | 6 |
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| Citation Language: | English |
| Citation Larger Work Title: | Precambrian Research |
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| Citation Number Of Pages: | 11 |
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| Citation Search Results Text: | Oxygen isotopes of some trondhjemites, siliceous gneisses, and associated mafic rocks; 1976; Article; Journal; Precambrian Research; Barker, F.; Friedman, I.; Hunter, D. R.; Gleason, J. D. |
| Citation Start Page: | 547 |
| Citation Volume: | 3 |
| Citation Year: | 1976 |
| Type: | citation/reference |
| Text: | Oxygen isotopes of some trondhjemites, siliceous gneisses, and associated mafic rocks; 1976; Article; Journal; Precambrian Research; Barker, F.; Friedman, I.; Hunter, D. R.; Gleason, J. D. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Thu, 1 Jan 1976 00:00 -0600 |
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