| Abstract: | 40Ar/39Ar ages of coexisting biotite and hornblende from Proterozoic Y gneisses of the Berkshire and Green Mt massifs, as well as 40Ar/39Ar and K/Ar mineral and whole-rock ages from Palaeozoic metamorphic rocks, suggest that the thermal peaks for the dominant metamorphic recrystallization in western New England occurred 465 + or - 5 m.y. (Taconian). 40Ar/39Ar age data from a poorly-defined terrain along the eastern strip of the area suggests that the area has been retrograded during a metamorphism that peaked at least 376 + or - 5 m.y. (Acadian). Available age and petrological data from western New England indicate the presence of at least three separate metamorphic-structure domains of Taconic age: 1) a small area of relict high-P and low-T metamorphism, 2) a broad area of normal Barrovian metamorphism from chlorite to garnet grade characterized by a gentle metamorphic gradient and, 3) a rather narrow belt of steep-gradient, Barrovian series metamorphic rocks. Areas of maximum metamorphic intensity within the last domain coincide with areas of maximum crustal thickening in the later stage of Taconic orogeny. -L.di H |
| Genre: | Article |
| ProdID: | 70013365 |
| Citation Author: | Sutter, J. F.; Ratcliffe, N. M.; Mukasa, S. B. |
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| Citation End Page: | 136 |
| Citation Issue: | 1 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geological Society of America Bulletin |
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| Citation Number Of Pages: | 14 |
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| Citation Search Results Text: | 40Ar/39Ar and K-Ar data bearing on the metamorphic and tectonic history of western New England.; 1985; Article; Journal; Geological Society of America Bulletin; Sutter, J. F.; Ratcliffe, N. M.; Mukasa, S. B. |
| Citation Start Page: | 123 |
| Citation Volume: | 96 |
| Citation Year: | 1985 |
| Type: | citation/reference |
| Text: | 40Ar/39Ar and K-Ar data bearing on the metamorphic and tectonic history of western New England.; 1985; Article; Journal; Geological Society of America Bulletin; Sutter, J. F.; Ratcliffe, N. M.; Mukasa, S. B. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Tue, 1 Jan 1985 00:00 -0600 |
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