Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber
The Margaree pluton extends for >40 km along the axis of the Ganderian Aspy terrane of northern Cape Breton Island, Nova Scotia. The pluton consists mainly of coarse-grained megacrystic syenogranite, intruded by small bodies of medium-grained equigranular syenogranite and microgranite porphyry, a...
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ftunivtoronto:oai:localhost:1807/100541 2023-05-15T15:46:45+02:00 Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber Sombini dos Santos, Gabriel Barr, Sandra M. White, Chris E van Rooyen, Deanne 2020-03-03 http://hdl.handle.net/1807/100541 http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2019-0220 unknown NRC Research Press (a division of Canadian Science Publishing) 0008-4077 http://hdl.handle.net/1807/100541 http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2019-0220 Article Article Post-Print 2020 ftunivtoronto 2020-06-17T12:31:13Z The Margaree pluton extends for >40 km along the axis of the Ganderian Aspy terrane of northern Cape Breton Island, Nova Scotia. The pluton consists mainly of coarse-grained megacrystic syenogranite, intruded by small bodies of medium-grained equigranular syenogranite and microgranite porphyry, all locally displaying rapakivi texture. The three rock types have similar U–Pb (zircon) ages of 363 ± 1.6, 364.8 ± 1.6, and 365.5 ± 3.3 Ma, respectively, consistent with field and petrological evidence that they are coeval and comagmatic. The rare earth elements display parallel trends characterized by enrichment in the light rare earth elements, flat heavy rare earth elements, moderate negative Eu anomalies, and, in some cases, positive Ce anomalies. The megacrystic and rapakivi textures are attributed to thermal perturbation in the magma chamber caused by the mixing of mafic and felsic magma, even though direct evidence of the mafic magma is mainly lacking at the current level of exposure. Magma evolution was controlled by fractionation of quartz, K-feldspar, and Na-rich plagioclase in molar proportions of 0.75:0.12:0.13. The chemical and isotopic (Sm–Nd) signature of the Margaree pluton is consistent with the melting of preexisting continental crust that was enriched in heat-producing elements, likely assisted by intrusion of mantle-derived mafic magma during Late Devonian regional extension. The proposed model involving magma mixing at shallow crustal levels in a cryptic silicic-mafic magma chamber during post-Acadian extension is consistent with models for other, better exposed occurrences of rapakivi granite in the northern Appalachian orogen. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author. Article in Journal/Newspaper Breton Island University of Toronto: Research Repository T-Space Canada Breton Island ENVELOPE(141.383,141.383,-66.800,-66.800) |
institution |
Open Polar |
collection |
University of Toronto: Research Repository T-Space |
op_collection_id |
ftunivtoronto |
language |
unknown |
description |
The Margaree pluton extends for >40 km along the axis of the Ganderian Aspy terrane of northern Cape Breton Island, Nova Scotia. The pluton consists mainly of coarse-grained megacrystic syenogranite, intruded by small bodies of medium-grained equigranular syenogranite and microgranite porphyry, all locally displaying rapakivi texture. The three rock types have similar U–Pb (zircon) ages of 363 ± 1.6, 364.8 ± 1.6, and 365.5 ± 3.3 Ma, respectively, consistent with field and petrological evidence that they are coeval and comagmatic. The rare earth elements display parallel trends characterized by enrichment in the light rare earth elements, flat heavy rare earth elements, moderate negative Eu anomalies, and, in some cases, positive Ce anomalies. The megacrystic and rapakivi textures are attributed to thermal perturbation in the magma chamber caused by the mixing of mafic and felsic magma, even though direct evidence of the mafic magma is mainly lacking at the current level of exposure. Magma evolution was controlled by fractionation of quartz, K-feldspar, and Na-rich plagioclase in molar proportions of 0.75:0.12:0.13. The chemical and isotopic (Sm–Nd) signature of the Margaree pluton is consistent with the melting of preexisting continental crust that was enriched in heat-producing elements, likely assisted by intrusion of mantle-derived mafic magma during Late Devonian regional extension. The proposed model involving magma mixing at shallow crustal levels in a cryptic silicic-mafic magma chamber during post-Acadian extension is consistent with models for other, better exposed occurrences of rapakivi granite in the northern Appalachian orogen. The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author. |
format |
Article in Journal/Newspaper |
author |
Sombini dos Santos, Gabriel Barr, Sandra M. White, Chris E van Rooyen, Deanne |
spellingShingle |
Sombini dos Santos, Gabriel Barr, Sandra M. White, Chris E van Rooyen, Deanne Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber |
author_facet |
Sombini dos Santos, Gabriel Barr, Sandra M. White, Chris E van Rooyen, Deanne |
author_sort |
Sombini dos Santos, Gabriel |
title |
Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber |
title_short |
Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber |
title_full |
Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber |
title_fullStr |
Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber |
title_full_unstemmed |
Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber |
title_sort |
petrology, age, and tectonic setting of the rapakivi-bearing margaree pluton, cape breton island, canada: evidence for a late devonian posttectonic cryptic silicic-mafic magma chamber |
publisher |
NRC Research Press (a division of Canadian Science Publishing) |
publishDate |
2020 |
url |
http://hdl.handle.net/1807/100541 http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2019-0220 |
long_lat |
ENVELOPE(141.383,141.383,-66.800,-66.800) |
geographic |
Canada Breton Island |
geographic_facet |
Canada Breton Island |
genre |
Breton Island |
genre_facet |
Breton Island |
op_relation |
0008-4077 http://hdl.handle.net/1807/100541 http://www.nrcresearchpress.com/doi/abs/10.1139/cjes-2019-0220 |
_version_ |
1766381455547564032 |