The nature of sialic basement to the Dunnage Zone, northern Newfoundland: evidence from crustal xenoliths
Quartzofeldspathic xenoliths representing the probable structural basement to the northern Dunnage Zone occur in lamprophyre dykes on Alcock Island and vicinity, Notre Dame Bay. The dykes occur close to the boundary between seismically defined lower crustal blocks (LCB) below the Dunnage Zone, so th...
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1991
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crcansciencepubl:10.1139/e91-097 2023-12-17T10:18:04+01:00 The nature of sialic basement to the Dunnage Zone, northern Newfoundland: evidence from crustal xenoliths Owen, J. Victor Greenough, John D. Fryer, Brian J. 1991 http://dx.doi.org/10.1139/e91-097 http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-097 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Earth Sciences volume 28, issue 7, page 1073-1077 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 1991 crcansciencepubl https://doi.org/10.1139/e91-097 2023-11-19T13:38:50Z Quartzofeldspathic xenoliths representing the probable structural basement to the northern Dunnage Zone occur in lamprophyre dykes on Alcock Island and vicinity, Notre Dame Bay. The dykes occur close to the boundary between seismically defined lower crustal blocks (LCB) below the Dunnage Zone, so the assignment of the xenoliths to a specific subsurface source is equivocal. The xenoliths include (i) clinopyroxene-bearing meta-(quartz) diorite to tonalite; (ii) plagioclase + quartz-rich rocks; and (iii) garnetiferous gneiss, including granulite. Paragneiss is absent, so the gneissic xenoliths do not appear to be direct analogues of Gander Zone metasediments thought to underlie parts of the Dunnage Zone farther to the southeast. The xenoliths also differ from Grenvillian crust exposed in western Newfoundland: the granulites are mineralogically distinct (contain clinopyroxene + garnet rather than orthopyroxene + garnet) and yield higher metamorphic P (approx. 8–10 kbar versus approx. 3–7 kbar) (1 kbar = 100 MPa), and the granitoid xenoliths are dioritic–tonalitic rather than granitic. Consequently, we propose that the xenoliths are derived from a non-Gander, non-Grenville source that may include Central LCB and (or) exotic basement material. We cannot, however, exclude the possibility that the xenoliths represent deeper structural levels of Grenvillian or Gander Zone crust than are presently exposed in outcrop. Article in Journal/Newspaper Alcock Island Newfoundland Canadian Science Publishing (via Crossref) Alcock ENVELOPE(-61.127,-61.127,-64.240,-64.240) Notre Dame Bay ENVELOPE(-54.998,-54.998,49.750,49.750) Canadian Journal of Earth Sciences 28 7 1073 1077 |
institution |
Open Polar |
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Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Owen, J. Victor Greenough, John D. Fryer, Brian J. The nature of sialic basement to the Dunnage Zone, northern Newfoundland: evidence from crustal xenoliths |
topic_facet |
General Earth and Planetary Sciences |
description |
Quartzofeldspathic xenoliths representing the probable structural basement to the northern Dunnage Zone occur in lamprophyre dykes on Alcock Island and vicinity, Notre Dame Bay. The dykes occur close to the boundary between seismically defined lower crustal blocks (LCB) below the Dunnage Zone, so the assignment of the xenoliths to a specific subsurface source is equivocal. The xenoliths include (i) clinopyroxene-bearing meta-(quartz) diorite to tonalite; (ii) plagioclase + quartz-rich rocks; and (iii) garnetiferous gneiss, including granulite. Paragneiss is absent, so the gneissic xenoliths do not appear to be direct analogues of Gander Zone metasediments thought to underlie parts of the Dunnage Zone farther to the southeast. The xenoliths also differ from Grenvillian crust exposed in western Newfoundland: the granulites are mineralogically distinct (contain clinopyroxene + garnet rather than orthopyroxene + garnet) and yield higher metamorphic P (approx. 8–10 kbar versus approx. 3–7 kbar) (1 kbar = 100 MPa), and the granitoid xenoliths are dioritic–tonalitic rather than granitic. Consequently, we propose that the xenoliths are derived from a non-Gander, non-Grenville source that may include Central LCB and (or) exotic basement material. We cannot, however, exclude the possibility that the xenoliths represent deeper structural levels of Grenvillian or Gander Zone crust than are presently exposed in outcrop. |
format |
Article in Journal/Newspaper |
author |
Owen, J. Victor Greenough, John D. Fryer, Brian J. |
author_facet |
Owen, J. Victor Greenough, John D. Fryer, Brian J. |
author_sort |
Owen, J. Victor |
title |
The nature of sialic basement to the Dunnage Zone, northern Newfoundland: evidence from crustal xenoliths |
title_short |
The nature of sialic basement to the Dunnage Zone, northern Newfoundland: evidence from crustal xenoliths |
title_full |
The nature of sialic basement to the Dunnage Zone, northern Newfoundland: evidence from crustal xenoliths |
title_fullStr |
The nature of sialic basement to the Dunnage Zone, northern Newfoundland: evidence from crustal xenoliths |
title_full_unstemmed |
The nature of sialic basement to the Dunnage Zone, northern Newfoundland: evidence from crustal xenoliths |
title_sort |
nature of sialic basement to the dunnage zone, northern newfoundland: evidence from crustal xenoliths |
publisher |
Canadian Science Publishing |
publishDate |
1991 |
url |
http://dx.doi.org/10.1139/e91-097 http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-097 |
long_lat |
ENVELOPE(-61.127,-61.127,-64.240,-64.240) ENVELOPE(-54.998,-54.998,49.750,49.750) |
geographic |
Alcock Notre Dame Bay |
geographic_facet |
Alcock Notre Dame Bay |
genre |
Alcock Island Newfoundland |
genre_facet |
Alcock Island Newfoundland |
op_source |
Canadian Journal of Earth Sciences volume 28, issue 7, page 1073-1077 ISSN 0008-4077 1480-3313 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/e91-097 |
container_title |
Canadian Journal of Earth Sciences |
container_volume |
28 |
container_issue |
7 |
container_start_page |
1073 |
op_container_end_page |
1077 |
_version_ |
1785541166053195776 |