Tectono-sedimentary analysis of alternate-polarity half-graben basin-fill successions: Late Devonian-Early Carboniferous Horton Group, Cape Breton Island, Nova Scotia

1989 ◽  
Vol 2 (4) ◽  
pp. 239-255 ◽  
Author(s):  
ANTHONY P. Hamblin ◽  
BRIAN R. Rust
Keyword(s):  
Nova Scotia ◽  
Early Carboniferous ◽  
Late Devonian ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Half Graben ◽  
Basin Fill

Chronology of Devonian to early Carboniferous rifting and igneous activity in southern Magdalen Basin based on U-Pb (zircon) dating

2002 ◽  
Vol 39 (8) ◽  
pp. 1219-1237 ◽  
Author(s):  
Greg R Dunning ◽  
Sandra M Barr ◽  
Peter S Giles ◽  
D Colin McGregor ◽  
Georgia Pe-Piper ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Fault Zone ◽  
Middle Devonian ◽  
Volcanic Rocks ◽  
Early Carboniferous ◽  
Late Devonian ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Igneous Activity ◽  
Age Determinations

Fifteen U–Pb (zircon) radiometric age determinations have been made on igneous rocks of Middle Devonian to Early Carboniferous age from the southern margin of the Magdalen basin in Cape Breton Island and northern mainland Nova Scotia. Volcanic rocks interbed with early rift-basin sedimentary rocks with some palynological biostratigraphy; dated intrusive rocks cut these sedimentary units. Our biostratigraphically constrained ages are in close agreement with the current Devonian time scale. Combined with previously published data, the age determinations show that igneous activity occurred in four pulses: Middle Devonian (390–385 Ma), early Late Devonian (375–370 Ma), latest Devonian to early Tournaisian (365–354 Ma), and late Tournaisian to early Visean (ca. 339 Ma). Middle Devonian (385–389 Ma) volcanic rocks are confined to the Guysborough Group. The Fisset Brook Formation (basalt and minor rhyolite) in the type area and elsewhere in Cape Breton Island and northern mainland Nova Scotia is Late Devonian (ca. 373 Ma), whereas the biostratigraphically distinct succession at Lowland Cove is younger (365 Ma). These Late Devonian rocks are synchronous with plutonism in the Cape Breton Highlands and the Meguma terrane. In the Cobequid Highlands, rhyolite of the Fountain Lake Group was synchronous with Horton Group deposition and with widespread granite plutons (362–358 Ma) emplaced during shear on the Cobequid fault zone. The overlying Diamond Brook Formation basalts are slightly younger (355 Ma). Late Tournaisian – early Visean mafic intrusions and minor basalt occur along the Cobequid – Chedabucto fault zone and in a belt from southern New Brunswick through Prince Edward Island to southwestern Cape Breton Island.

Late Devonian – Early Carboniferous volcanism in western Cape Breton Island, Nova Scotia

1984 ◽  
Vol 21 (7) ◽  
pp. 762-774 ◽  
Author(s):  
Marie-Claude Blanchard ◽  
Rebecca A. Jamieson ◽  
Elizabeth B. More
Keyword(s):  
Tectonic Setting ◽  
Early Carboniferous ◽  
Alluvial Fan ◽  
Late Devonian ◽  
Fluvial Sediments ◽  
Western Cape ◽  
Cape Breton Island ◽  
The North ◽  
Cape Breton ◽  
Geochemical Studies

The Fisset Brook Formation of western Cape Breton Island and its equivalents at MacMillan Mountain and the north Baddeck River are examples of Late Devonian and Early Carboniferous volcanic sequences associated with the formation of post-Acadian successor basins in the northeastern Appalachians. They consist of bimodal basalt–rhyolite suites interbedded with alluvial fan, lacustrine, and rare fluvial sediments. The earliest volcanic products are rhyolites and somewhat evolved basalts associated with coarse sediments, followed by tholeiitic to transitional basalt flows interlayered with lacustrine-type deposits. Geochemical studies on the Fisset Brook Formation indicate extensive remobilization of alkalies, Ca, Rb, and Sr, making these elements inappropriate for determining tectonic setting or magmatic affinity. Use of less mobile elements (Ti, Nb, Y, and Zr) suggests that the basalts are tholeiitic and that the apparent alkalinity of the type section lavas is a result of alteration. We conclude that volcanism in western Cape Breton Island started at MacMillan Mountain and migrated westwards, probably towards the centre of the deepening Magdalen Basin.

Appalachian basement and its intrusion by Cretaceous dykes, offshore southeast Nova Scotia, Canada

1993 ◽  
Vol 30 (12) ◽  
pp. 2495-2509 ◽  
Author(s):  
L. F. Jansa ◽  
G. Pe-Piper ◽  
B. D. Loncarevic
Keyword(s):  
Nova Scotia ◽  
Short Wavelength ◽  
Lower Grade ◽  
Aeromagnetic Data ◽  
Cape Breton Island ◽  
Late Proterozoic ◽  
Cape Breton ◽  
Depleted Mantle ◽  
Half Graben ◽  
Meguma Terrane

Aeromagnetic data collected between eastern Nova Scotia and southern Newfoundland provide new information about the offshore extension of the Avalon and Meguma terranes. A zone of short-wavelength anomalies that delineates Scatarie Ridge extends westward to the Late Proterozoic Fourchu Group in southeastern Cape Breton Island and eastward towards the Burin Peninsula of Newfoundland, suggesting that both regions belong to the same tectono-stratigraphic province of the Avalon composite terrane. A different zone of short-wavelength, discontinuously lineated anomalies at the northern edge of the Canso Ridge correlates with amphibolite-facies metamorphic rocks of the Meguma terrane on the Canso Peninsula, interpreted as an exhumed deeper metamorphic level of the Meguma terrane at its boundary with the Avalon terrane. The S-shaped pattern of long linear magnetic trends, characteristic of lower grade Meguma rocks on the southern flank of the Canso Ridge, indicates plastic deformation of the Meguma terrane during the Acadian orogeny when emplaced against the rigid Cape Breton Island block indentor. Analogous patterns occur off western Nova Scotia, suggesting little strike-slip motion occurred between the Meguma and Avalon terranes since the Acadian orogeny.Late Proterozoic rocks on Scatarie Ridge are intruded by Cretaceous diabase dykes. The diabase is alkaline with a within-plate geochemical signature, similar in composition to basalt flows in the Orpheus half-graben. A depleted-mantle model age TDM (Nd) of 731 Ma, εNd = +6.5, suggests that the magma was sourced from a lithospheric mantle reservoir involved in Late Proterozoic magmatic activity. Aeromagnetic data interpretation confirms the distribution of Cretaceous basalt flows and sills within Mesozoic sedimentary strata of the Orpheus half-graben previously outlined by seismic methods but was unable to differentiate between Proterozoic and Mesozoic intrusive rocks where the Proterozoic rocks lay near to the ocean floor.

The youngest Paleozoic plutonism of the Newfoundland Appalachians: U–Pb ages from the St. Lawrence and François granites

1993 ◽  
Vol 30 (12) ◽  
pp. 2328-2333 ◽  
Author(s):  
A. Kerr ◽  
G. R. Dunning ◽  
R. D. Tucker
Keyword(s):  
Nova Scotia ◽  
South Coast ◽  
Tectonic Activity ◽  
Late Devonian ◽  
Early Paleozoic ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Younger Age ◽  
Age Limit ◽  
Magmatic Event

The posttectonic St. Lawrence and François granites have long been regarded as the youngest Paleozoic plutonic suites of the Newfoundland Appalachians. Their U–Pb ages of 374 ± 2 and 378 ± 2 Ma, respectively, define a Middle to Late Devonian magmatic event. Mid-Carboniferous magmatic and (or) rifting events, suggested on the basis of earlier Rb–Sr dating of the St. Lawrence Granite, are not supported by these new data. Both granites intrude major ductile and brittle structures that were active during the early Paleozoic, and they provide a younger age limit for major tectonic activity in the Avalon Zone and on the south coast of Newfoundland. The granites may correlate with plutons of closely similar age reported from the Aspy and Mira terranes of Cape Breton Island, Nova Scotia.

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