Grenvillian basement in the northern Cape Breton Highlands, Nova Scotia

1987 ◽  
Vol 24 (5) ◽  
pp. 992-997 ◽  
Author(s):  
Sandra M. Barr ◽  
Robert P. Raeside ◽  
Otto van Breemen
Keyword(s):  
Nova Scotia ◽  
Long Range ◽  
Granitic Rocks ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Basement Rocks ◽  
Northern Cape ◽  
Granitoid Rocks

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.

Radiometric Ages of Granitic Rocks, Cape Breton Island, Nova Scotia

1972 ◽  
Vol 9 (9) ◽  
pp. 1074-1086 ◽  
Author(s):  
Randall F. Cormier
Keyword(s):  
Nova Scotia ◽  
Mean Value ◽  
Granitic Rocks ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Granitic Intrusion ◽  
Radiometric Ages ◽  
Northern Highlands

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.

Magmatism and metamorphism in a Grenvillian fragment: U-Pb and 40Ar/39Ar ages from the Blair River Complex, northern Cape Breton Island, Nova Scotia, Canada

1996 ◽  
Vol 108 (2) ◽  
pp. 127-140 ◽  
Author(s):  
Brent V. Miller ◽  
Gregory R. Dunning ◽  
Sandra M. Barr ◽  
Robert P. Raeside ◽  
Rebecca A. Jamieson ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Northern Cape

Origin and Emplacement of Acadian Granitic Rocks, Northern Cape Breton Island

1975 ◽  
Vol 12 (2) ◽  
pp. 252-262 ◽  
Author(s):  
Robert A. Wiebe
Keyword(s):  
Country Rock ◽  
Source Region ◽  
Spatial Arrangement ◽  
High Water ◽  
Granitic Rocks ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Northern Cape ◽  
Areal Variation ◽  
Differentiation Index

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.

scholarly journals Geology, Northern Cape Breton Island, Nova Scotia

1992 ◽  
Author(s):  
S M Barr ◽  
R A Jamieson ◽  
R P Raeside
Keyword(s):  
Nova Scotia ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Northern Cape

AGE AND FORMATION OF ANORTHOSITIC ROCKS WITHIN THE BLAIR RIVER INLIER OF NORTHERN CAPE BRETON ISLAND, NOVA SCOTIA (CANADA)

2019 ◽  
Author(s):  
J. Gregory Shellnutt ◽  
◽  
Jaroslav Dostal ◽  
J. Duncan Keppie ◽  
D. Fraser Keppie
Keyword(s):  
Nova Scotia ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Northern Cape

scholarly journals Formation of Anorthositic Rocks within the Blair River Inlier of Northern Cape Breton Island, Nova Scotia (Canada)

Lithosphere ◽  
2021 ◽  
Vol 2020 (1) ◽  
Author(s):  
J. Gregory Shellnutt ◽  
Jaroslav Dostal ◽  
J. Duncan Keppie ◽  
D. Fraser Keppie
Keyword(s):  
Nova Scotia ◽  
Crustal Contamination ◽  
Parental Magma ◽  
Intrusive Complex ◽  
Early Devonian ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Iapetus Ocean ◽  
Northern Cape ◽  
Mineral Compositions

Abstract Rocks from the Blair River inlier of Northern Cape Breton Island (Nova Scotia, Canada) have been correlated with either the Grenville basement of eastern Laurentia or the accreted Avalon terrane. Additional zircon U-Pb dates of spatially associated anorthositic dykes (425.1±2.2 Ma) and a metagabbro (423.8±2.5 Ma) from the Fox Back Ridge intrusion of the Blair River inlier reveal Late Silurian emplacement ages. Their contemporaneity suggests that they may be members of a larger intrusive complex. The anorthositic rocks have high Eu/Eu∗ values (>2.5), and bulk compositions are similar to the mineral compositions of labradorite (An50-70) and andesine (An30-50). The metagabbro is compositionally similar to alkali basalt and does not seem to have been affected by crustal contamination (Nb/U>24; Th/NbPM≤1.1) although it was metamorphosed. The high Tb/YbN (1.8-1.9) ratios suggest that the parental magma of the metagabbro was derived from a garnet-bearing peridotite. Fractional crystallization and mass balance calculations indicate that the anorthositic rocks can be derived by mineral accumulation from a mafic parental magma similar in composition to the metagabbro of this study. The Late Silurian ages suggest that the rocks were emplaced into the Avalon terrane after the closure of the Iapetus Ocean but before Early Devonian (415-410 Ma) sinistral transpression.

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