The Mount Peyton Batholith, Central Newfoundland: A Bimodal Calc-Alkaline Suite
The lower Devonian (375 ± 15 Ma) Mount Peyton batholith of central Newfoundland posttectonically intruded Ordovician and Silurian volcanic and sedimentary rocks following closure of the proto-Atlantic ocean. The Silurian country rocks are of lower greenschist regional metamorphic grade with a narrow...
| Published in: | Journal of Petrology |
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| Main Author: | |
| Format: | Text |
| Language: | English |
| Published: |
Oxford University Press
1979
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| Online Access: | http://petrology.oxfordjournals.org/cgi/content/short/20/1/119 https://doi.org/10.1093/petrology/20.1.119 |
| Summary: | The lower Devonian (375 ± 15 Ma) Mount Peyton batholith of central Newfoundland posttectonically intruded Ordovician and Silurian volcanic and sedimentary rocks following closure of the proto-Atlantic ocean. The Silurian country rocks are of lower greenschist regional metamorphic grade with a narrow contact aureole, indicating a shallow level of intrusion. Geophysical data suggest a subsurface conical shape for the batholith extending to about 12 km depth with about 1 km of granite at the top. Gabbro and granite dominate the exposed surface of the batholith, forming a bimodal assemblage with very minor peraluminous intermediate compositions. Nevertheless, classification by common geochemical parameters indicates calc-alkaline variation patterns of both major and trace elements. The available petrological evidence suggests that the suite crystallized under pressures of less than about 4 kb and relatively low temperatures. The gabbroic. intermediate and granitic rocks do not appear to be related by any common fractionation scheme, and there is some evidence to suggest independent origins, with gabbroic rocks derived from the upper mantle and the others formed by crustal anatexis. |
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