| Abstract: | A published Sm-Nd whole-rock isochron of 2,920 ?? 50 Myr, obtained from a wide range of lithologies in the Lewisian complex of north-west Scotland, was interpreted1 as the time of protolith formation. This date is ???260 Myr older than estimates for the timing of high-grade metamorphism in the complex at ??? 2,660 Myr2‘3, and this period is considered to represent the duration of the Lewisian crustal accretion-differentiation superevent (CADS)4. Here we give new Sm-Nd data, obtained specifically from granulite facies tonalitic gneisses, that yield a date of 2,600 ??155 Myr. Although depleted-mantle model ages (tDM suggest >200 Myr of premetamorphic crustal residence, the regression date and its associated initial Nd-isotopic parameters demonstrate Nd-isotopic homogenization during the high-grade event, as well as the probability of general rare-earth-element (REE) mobility. Models for selective element depletion in the complex have previously assumed REE immobility since 2,920 Myr, but the data presented here suggest that a reappraisal of the depletion mechanism is required. ?? 1988 Nature Publishing Group. |
| Genre: | Article |
| ProdID: | 70014327 |
| Citation Author: | Whitehouse, M. J. |
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| Citation End Page: | 707 |
| Citation Issue: | 6158 |
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| Citation Language: | English |
| Citation Larger Work Title: | Nature |
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| Citation Number Of Pages: | 3 |
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| Citation Search Results Text: | Granulite fades Nd-isotopic homogenization in the Lewisian complex of northwest Scotland; 1988; Article; Journal; Nature; Whitehouse, M. J. |
| Citation Start Page: | 705 |
| Citation Volume: | 331 |
| Citation Year: | 1988 |
| Type: | citation/reference |
| Text: | Granulite fades Nd-isotopic homogenization in the Lewisian complex of northwest Scotland; 1988; Article; Journal; Nature; Whitehouse, M. J. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Fri, 1 Jan 1988 00:00 -0600 |
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