Radiometric Ages of Granitic Rocks, Cape Breton Island: Discussion

1973 ◽  
Vol 10 (9) ◽  
pp. 1470-1470 ◽  
Author(s):  
R. F. Cormier

1972 ◽  
Vol 9 (9) ◽  
pp. 1074-1086 ◽  
Author(s):  
Randall F. Cormier

Rubidium–strontium whole-rock and mineral ages of granitic rocks from fourteen localities on Cape Breton Island have been measured. The ages cluster about a mean value of about 560 m.y. and indicate that most of the granitic rocks on the island have primary ages that are close to the Cambrian–Precambrian (Hadrynian) boundary. Some of the granitic rocks, particularly in the northern highlands, may have considerably younger, Siluro–Devonian (Acadian?), primary ages. Evidence is presented suggesting that simple biotite ages are not always reliable for the measurement of primary ages of granitic rocks. It. is suggested that, the granitic rocks having primary ages close to the Cambrian-Precambrian boundary be referred to a hitherto generally unrecognized episode of granitic intrusion, the Bretonian.





1981 ◽  
Vol 18 (7) ◽  
pp. 1187-1210 ◽  
Author(s):  
K. V. Rao ◽  
M. K. Seguin ◽  
E. R. Deutsch

As part of a major study of the Avalon zone in Cape Breton Island, we describe the paleomagnetism of radiometrically well-studied granitic rocks of two generations, representing the Acadian (350–450 Ma) and the Avalonian (520–580 Ma) Orogenies, respectively. Detailed alternating field (AF) and thermal experiments performed on the younger granites indicate that they are characterized by three different mean directions of magnetization in the 10–60 mT coercivity spectra: SE (D = 149°, I = +70°; K = 160, N = 4 sites); NE-1 (D = 72°, I = −70°; K = 320, N = 3 sites); and NE-2 (D = 31°, I = −24°; K = 67, N = 3 sites) with corresponding paleopole positions at CB-1 (16°N, 41°W; δp, δm = 6°, 7°); CB-2 (32°N, 97°W; δp, δm = 7°, 8°); and CB-3 (27°S, 96°W; δp, δm = 6°, 11°). The radiometric ages of these three remanence directions do not differ from each other by more than 50 Ma; these remanences are also present as low coercivity (5–25 mT) magnetizations in the Avalonian granites (10 sites). Antipole CB-3 agrees with other recently reported Early Devonian paleomagnetic results from the northern Appalachians. In contrast, the two other antipoles (CB-1 and CB-2) are located in southerly latitudes but do not differ significantly from poles of contemporaneous rocks in New Brunswick and Newfoundland. The "aberrancy" of southerly located Siluro-Devonian poles with respect to those in northern latitudes is discussed in the context of possible transcurrent motion of the "Acadia" displaced terrain with respect to cratonic North America. Presently available paleomagnetic data are not conclusive and cannot confirm or negate this possibility. The CB-1, CB-2, and CB-3 poles are interpreted as representing rapid apparent polar wander with respect to Cape Breton Island during Siluro-Devonian time.In the older Cambrian granites, pole CB (37°N, 176°E; δp, δm = 2°, 3°), derived from a high coercivity (20–70 mT) mean remanence direction NW (D = 318°, I = +15°; K = 298, N = 10 sites), probably corresponds to the Avalonian Orogeny. Further results are needed to interpret the paleogeographic setting of the Avalon microcontinent in early Paleozoic time.



1975 ◽  
Vol 12 (2) ◽  
pp. 252-262 ◽  
Author(s):  
Robert A. Wiebe

Acadian granitic rocks in northern Cape Breton Island consist entirely of even-grained leucocratic granodiorite and adamellite. The compositional range is small, and the average composition corresponds well with melts that could be generated in the crust. Abundant pegmatites in the contact zone suggest high water content.Within the major plutons these granitic rocks show: (1) high scatter on a Rb–Sr isochron (Cormier 1972), (2) apparently random areal variation in K and Ca, but a systematic areal variation in K/Rb and Ca/Sr, and (3) high scatter of Na2O and K2O on plots against differentiation index. The minor compositional heterogeneity indicated by these relations could have originated within the source region of melting or by assimilation during emplacement.The granitic plutons are elongate north–south and occur in an en echelon pattern within a NNE-trending migmatite zone. The spatial arrangement of pre-emplacement structures in the country rock and the distribution of xenoliths in the intrusions suggest that emplacement was accommodated by east–west expansion, upbowing of the surrounding country rock, faulting, and minor stoping.



1996 ◽  
Vol 296 (7) ◽  
pp. 789-817 ◽  
Author(s):  
R. A. Ayuso ◽  
S. M. Barr ◽  
F. J. Longstaffe


1987 ◽  
Vol 24 (5) ◽  
pp. 992-997 ◽  
Author(s):  
Sandra M. Barr ◽  
Robert P. Raeside ◽  
Otto van Breemen

The northernmost Cape Breton Highlands are underlain by the Blair River Complex, a distinctive assemblage of basement rocks including felsic and mafic gneisses, foliated gabbroic to granitic rocks, anorthosite, and foliated and unfoliated varieties of syenite. Major faults and mylonite zones separate the complex from schists, gneisses, and granitoid rocks typical of the rest of the Cape Breton Highlands. U–Pb dating of zircon from the Lowland Brook syenite of the Blair River Complex indicates a metamorphic age of [Formula: see text] and an igneous age of 1100–1500 Ma. These ages and the distinctive rock assemblage allow the Blair River Complex to be correlated with the Grenvillian rocks in the Long Range Inlier and Indian Head Range Complex of western Newfoundland. This is the first confirmed report of Grenvillian basement in Cape Breton Island, and it places new constraints on correlations between Newfoundland and the northern mainland Appalachians.



1989 ◽  
Vol 26 (11) ◽  
pp. 2255-2267 ◽  
Author(s):  
B. D. Loncarevic ◽  
S. M. Barr ◽  
R. P. Raeside ◽  
C. E. Keen ◽  
F. Marillier

The narrowest section of the Appalachian Orogen in Atlantic Canada (from Grenville-age basement in the west to the Avalon Terrane in the east) is preserved in Cape Breton Island, where components of four terranes display distinctive stratigraphic, igneous, metamorphic, aeromagnetic, and gravity characteristics. The Blair River Complex of northwestern Cape Breton Island is a fragment of Grenvillian rocks that is similar to units in western Newfoundland. The Aspy Terrane is characterized by mid-Paleozoic granitic rocks and high-pressure paragneisses and appears to continue across the Cabot Strait as the Gander Terrane of the Hermitage Flexure in Newfoundland. The Bras d'Or Terrane is composed of Hadrynian to Early Cambrian low-pressure metasedimentary units and dioritic to granitic plutonic rocks. As indicated by aeromagnetic anomalies, this terrane continues across the Laurentian Channel to the south coast of Newfoundland, where it may be terminated by the Hermitage Fault. The Avalon Terrane of southeastern Cape Breton Island bears many similarities to the Avalon Terrane of Newfoundland.A seismic reflection profile obtained as part of the Lithoprobe-East project shows that the Blair River Complex is juxtaposed against the Aspy Terrane by steeply dipping fault systems that cut through the entire crust and that the Bras d'Or Terrane is similarly juxtaposed with the Avalon Terrane. The nature of the boundary between the Aspy and Bras d'Or terranes is less clear, although metamorphic conditions and the seismic reflection profile both suggest that the Aspy Terrane represents a deeper crustal level, over which the Bras d'Or Terrane has been emplaced.



Author(s):  
Erna MacLeod

Cape Breton Island is a well-known North American tourism destination with long-standing attractions such as the Cabot Trail and more recently developed world-class offerings such as the Cabot Links Golf Course. Tourism contributes significantly to Cape Breton’s economy, particularly since the mid-20th century as traditional resource-based industries have declined. In the 21st century, culinary tourism has become increasingly important to expand the island’s tourism offerings and to provide “authentic” tourism experiences. This study examines local-food tourism in Cape Breton to illuminate its cultural and economic significance. I conducted interviews with food producers, restaurateurs, government representatives, and tourism executives. I also consulted websites and policy documents and compared local stakeholders’ experiences and perspectives with official tourism strategies. Promoting culinary tourism raises questions of power, autonomy, inclusion, and accountability. My study accentuates possibilities for aligning economic and ecological goals to create resilient communities, foster equitable social and ecological relations, and establish Cape Breton as a culinary tourism destination.



2007 ◽  
Vol 30 (5) ◽  
pp. 279-286 ◽  
Author(s):  
David J. Mossman ◽  
James D. Duivenvoorden ◽  
Fenton M. Isenor




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