U-Pb zircon, titanite, and monazite ages in the Bras d'Or and Aspy terranes of Cape Breton Island, Nova Scotia: Implications for igneous and metamorphic history

Abstract

Research Article| March 01, 1990 U-Pb zircon, titanite, and monazite ages in the Bras d'Or and Aspy terranes of Cape Breton Island, Nova Scotia: Implications for igneous and metamorphic history G. R. DUNNING; G. R. DUNNING 1Department of Earth Sciences, Memorial University of Newfoundland St John's, Newfoundland AIB 3X5 Canada Search for other works by this author on: GSW Google Scholar S. M. BARR; S. M. BARR 2Department of Geology, Acadia University, Woodle, Nova Scotia B0P 1X0 Canada Search for other works by this author on: GSW Google Scholar R. P. RAESIDE; R. P. RAESIDE 2Department of Geology, Acadia University, Woodle, Nova Scotia B0P 1X0 Canada Search for other works by this author on: GSW Google Scholar R. A. JAMIESON R. A. JAMIESON 3Department of Geology, Dalhousie University, Halifax, Nova Scotia B3H 3J5 Canada Search for other works by this author on: GSW Google Scholar GSA Bulletin (1990) 102 (3): 322–330. https://doi.org/10.1130/0016-7606(1990)102<0322:UPZTAM>2.3.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation G. R. DUNNING, S. M. BARR, R. P. RAESIDE, R. A. JAMIESON; U-Pb zircon, titanite, and monazite ages in the Bras d'Or and Aspy terranes of Cape Breton Island, Nova Scotia: Implications for igneous and metamorphic history. GSA Bulletin 1990;; 102 (3): 322–330. doi: https://doi.org/10.1130/0016-7606(1990)102<0322:UPZTAM>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract New U-Pb ages from zircon, titanite, or monazite separates from 12 units in the Aspy and Bras d'Or terranes, Nova Scotia, range from late Precambrian to Devonian and generally support the interpretation that the 2 terranes had differing histories until juxtaposition in the Devonian. Five plutons of dioritic, tonalitic, and granodioritic compositions in the northern Bras d'Or terrane yielded zircon ages between 575 (maximum) and 556 ± 4 m.y. Younger titanite ages of 548 ± 2 and 521 ± 2 m.y. from two of these plutons may indicate younger metamorphism. Previously undocumented Early Ordovician plutonism (493 ± 2 Ma, zircon) and metamorphism (496 ± 5 Ma, titanite) also occurred in the Bras d'Or terrane.In the Aspy terrane, a zircon age of 433 +7/-4 m.y. was obtained for a rhyolite unit in the upper part of a widespread metavolcanic-metasedimentary sequence, which together with higher-grade, probably correlative units, is characteristic of the terrane. The age is interpreted to indicate that most metamorphic rocks in the terrane are Ordovician to Early Silurian in age, in contrast to Precambrian ages in the Bras d'Or terrane. Devonian plutonism was widespread in the Aspy terrane, whereas Devonian plutonism in the Bras d'Or terrane appears restricted to the vicinity of the boundary with the Aspy terrane. Zircon, titanite, or monazite ages from 4 plutonic and orthogneissic units in the Aspy terrane and in the Bras d'Or terrane adjacent to the terrane boundary range from 403 ± 3 to 375 +5/-4 m.y. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.