| Abstract: | Two distinct types of compositional zoning are recognised in idioblastic to subidioblastic garnets in amphibolite facies metapelites in western Fiordland. One type occurs in kyanite (?? sillimanite)-bearing rocks and is characterised by a core to rim increase in CaO content, and a sympathetic decrease in FeO and MgO, with MnO remaining essentially constant, or decreasing slightly near the rim. This zoning pattern formed during garnet growth, and records adjustment of mineral equilibria under conditions of increasing load pressure. A much less common type of zoned garnet occurs in sillimanite + K-feldspar-bearing metapelites and is characterised by a core to rim decrease in CaO and MgO contents and a sympathetic increase in FeO and MnO near the rim. This zoning pattern is interpreted to result from post-growth volume diffusion, and records metamorphism at significantly lower pressures. -from Author |
| Genre: | Article |
| ProdID: | 70015090 |
| Citation Author: | Bradshaw, J. Y. |
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| Citation End Page: | 270 |
| Citation Issue: | 3 |
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| Citation Language: | English |
| Citation Larger Work Title: | New Zealand Journal of Geology and Geophysics |
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| Citation Number Of Pages: | 10 |
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| Citation Publisher: | Taylor and Francis |
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| Citation Search Results Text: | Zoned garnets in metapelites in western Fiordland, southwest New Zealand: polychronic crystallisation and insight into the nature and extent of early Cretaceous regional metamorphism; 1991; Article; Journal; New Zealand Journal of Geology and Geophysics; Bradshaw, J. Y. |
| Citation Start Page: | 261 |
| Citation Volume: | 34 |
| Citation Year: | 1991 |
| Type: | citation/reference |
| Text: | Zoned garnets in metapelites in western Fiordland, southwest New Zealand: polychronic crystallisation and insight into the nature and extent of early Cretaceous regional metamorphism; 1991; Article; Journal; New Zealand Journal of Geology and Geophysics; Bradshaw, J. Y. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1080/00288306.1991.9514464 |
| Date Other: | Tue, 1 Jan 1991 00:00 -0600 |
| Publisher: | Taylor and Francis |
