scholarly journals Beaconites antarcticus in the (?Middle) Late Devonian McAras Brook Formation, Cape George, Nova Scotia

10.4138/1589 ◽  
1985 ◽  
Vol 21 (1) ◽  
Author(s):  
P. M. Bruck ◽  
W. H. Forbes ◽  
D. Nance ◽  
R. K. Pickerill
Keyword(s):  
Nova Scotia ◽  
Late Devonian

An evaluation of crustal assimilation within the Late Devonian South Mountain Batholith, SW Nova Scotia

2012 ◽  
Vol 149 (3) ◽  
pp. 353-365 ◽  
Author(s):  
J. GREGORY SHELLNUTT ◽  
JAROSLAV DOSTAL
Keyword(s):  
Nova Scotia ◽  
Chemical Evolution ◽  
Hydrothermal Fluids ◽  
Eastern North America ◽  
Late Devonian ◽  
Metal Enrichment ◽  
Crustal Assimilation ◽  
South Mountain Batholith ◽  
Appalachian Orogen ◽  
Zircon Saturation

AbstractThe Late Devonian South Mountain Batholith (SMB) of southwestern Nova Scotia is the largest batholith in the Appalachian Orogen of Eastern North America and contains economic deposits of U and Sn. The SMB comprises at least 11 individual plutons, which range in composition from granodiorite to biotite monzogranite, leucomonzogranite and leucogranite. Previous studies have suggested that a combination of fractional crystallization, assimilation of Meguma Supergroup country rocks and an influx of magmatic fluids contributed to the chemical evolution of the SMB. The amount of crustal assimilation is estimated to be as high as 33%. MELTS modelling assuming a starting composition of granodiorite with H2O = 4 wt%, pressure = 4 kbar (~12 km) and fO2 = FMQ can reproduce the chemical evolution observed in the SMB. However, some leucogranites likely require an additional component (e.g. hydrothermal fluids) to explain their alkali metal enrichment (e.g. Na, K, Rb). Zircon saturation thermometry estimates indicate the Salmontail Lake and Scrag Lake granodiorite plutons had high minimum initial temperatures of 823 ± 6°C and 832 ± 2°C, respectively, which are similar to low zircon-inheritance granitoids. The TiO2/Al2O3 and alkali-lime ratios of the surrounding country rocks and the leucogranites indicate the amount of crustal assimilation is likely to be between 10% and 20%. Our findings suggest the granodiorites of the SMB were likely produced by partial melting of the sub-Meguma Supergroup (e.g. Avalon terrane) lower crust caused by the contemporaneous injection of high temperature mafic to ultramafic magmas.

scholarly journals Carboniferous barite-fluorite mineralization in the Late Devonian Kinsac Pluton, southern Nova Scotia

10.4138/2026 ◽  
1999 ◽  
Vol 35 (2) ◽  
Author(s):  
Daniel J. Kontak ◽  
Richard J. Horne ◽  
Kevin Ansdell ◽  
Douglas A. Archibald
Keyword(s):  
Nova Scotia ◽  
Late Devonian

scholarly journals Locomotory behaviour of early tetrapods from Blue Beach, Nova Scotia, revealed by novel microanatomical analysis

2021 ◽  
Vol 8 (5) ◽  
pp. 210281
Author(s):  
Kendra I. Lennie ◽  
Sarah L. Manske ◽  
Chris F. Mansky ◽  
Jason S. Anderson
Keyword(s):  
Nova Scotia ◽  
Fossil Record ◽  
Early Carboniferous ◽  
Late Devonian ◽  
Ground Reaction Forces ◽  
Limb Bones ◽  
Additional Information ◽  
Reaction Forces ◽  
Early Tetrapods ◽  
Locomotory Behaviour

Evidence for terrestriality in early tetrapods is fundamentally contradictory. Fossil trackways attributed to early terrestrial tetrapods long predate the first body fossils from the Late Devonian. However, the Devonian body fossils demonstrate an obligatorily aquatic lifestyle. Complicating our understanding of the transition from water to land is a pronounced gap in the fossil record between the aquatic Devonian taxa and presumably terrestrial tetrapods from the later Early Carboniferous. Recent work suggests that an obligatorily aquatic habit persists much higher in the tetrapod tree than previously recognized. Here, we present independent microanatomical data of locomotor capability from the earliest Carboniferous of Blue Beach, Nova Scotia. The site preserves limb bones from taxa representative of Late Devonian to mid-Carboniferous faunas as well as a rich trackway record. Given that bone remodels in response to functional stresses including gravity and ground reaction forces, we analysed both the midshaft compactness profiles and trabecular anisotropy, the latter using a new whole bone approach. Our findings suggest that early tetrapods retained an aquatic lifestyle despite varied limb morphologies, prior to their emergence onto land. These results suggest that trackways attributed to early tetrapods be closely scrutinized for additional information regarding their creation conditions, and demand an expansion of sampling to better identify the first terrestrial tetrapods.

Interaction among upper crustal, lower crustal, and mantle materials in the Port Mouton pluton, Meguma Lithotectonic Zone, southwest Nova Scotia

2000 ◽  
Vol 37 (4) ◽  
pp. 579-600 ◽  
Author(s):  
D Barrie Clarke ◽  
Raymond Fallon ◽  
Larry M Heaman
Keyword(s):  
Nova Scotia ◽  
Lower Crust ◽  
Early Stage ◽  
Late Devonian ◽  
Upper Crust ◽  
Middle Stage ◽  
Two Component ◽  
Granitoid Rocks ◽  
Mafic Magmas ◽  
Lithotectonic Zone

The Port Mouton pluton is unique among the Late Devonian peraluminous granitoid bodies in the Meguma Lithotectonic Zone of southwestern Nova Scotia in its lithological heterogeneity, extensive physical and chemical interaction with the country rocks, clear evidence for mingling and mixing with mafic magmas, and highly abundant pegmatites. New U–Pb age determinations on monazite establish an intrusion age of 373 ± 1 Ma, similar to the ages of other Meguma Lithotectonic Zone granitoid plutons and mafic intrusions. Field relations, petrology, and geochemistry define three stages of intrusion of the Port Mouton pluton: (i) early stage, discontinuously exposed around the outer margin of the pluton, dominated by coarse-grained tonalite-granodiorite, and with Rb/Sr < 0.55, Eu/Eu* > 0.40, and GdN/LuN < 2; (ii) middle stage, occupying the interior of the pluton, dominated by medium-grained granodiorite-monzogranite, and with Rb/Sr > 0.55, Eu/Eu* < 0.40, and GdN/LuN > 2; and (iii) late stage, consisting of abundant minor sheets throughout the pluton, dominated by fine-grained tonalite, granodiorite, and leucogranite that are similar to rocks of the early and middle stages. The Port Mouton pluton shows a wider range of 87Sr/86Sri (0.7036-0.7154), and a wider range and generally higher εNdi (–3.72 to +2.12), than other granitoid rocks in the Meguma Lithotectonic Zone, potentially reflecting a complex, partially equilibrated, interaction among mantle, lower crust, and upper crust. Field, petrological, and chemical evidence for the involvement of mantle-derived magmas and melting of upper crust permit modelling of the Port Mouton pluton granitoid compositions by three simultaneous mixing equations. These mixing model results suggest that the early stage granitoid rocks can form from simple three-component mixing relationships when the bulk distribution coefficients between residuum and melt for Sr and Nd range from 1.05 to 1.18, or two-component mixing combined with fractionation of material like the known felsic lower crust. The middle stage granitoid rocks only yield solutions involving two-component mixing and fractionation of material unlike the known felsic lower crust. We conclude that the Late Devonian mafic magmas played a major role in the formation of granitoid magmas in the Meguma Lithotectonic Zone by supplying heat and material to cause partial fusion of the Avalon lower crust.

The age and significance of Carboniferous plutons of the western Cobequid Highlands, Nova Scotia

1989 ◽  
Vol 26 (6) ◽  
pp. 1297-1307 ◽  
Author(s):  
Georgia Pe-Piper ◽  
R. F. Cormier ◽  
David J. W. Piper
Keyword(s):  
Nova Scotia ◽  
Volcanic Rocks ◽  
Older Age ◽  
Ductile Deformation ◽  
Late Devonian ◽  
Crustal Extension ◽  
Eastern Canada ◽  
Appalachian Orogen

A series of granite plutons with minor gabbro–diorite phases outcrops immediately north of the Cobequid Fault in the western Cobequid Highlands, Nova Scotia. The plutons were cut by numerous dykes, and parts of some plutons and some dykes subsequently underwent ductile deformation. Four Rb–Sr whole-rock–K-feldspar isochron dates ranging from 338 to 356 Ma have been obtained from these plutons and the dykes that cut them. The ages of these plutons are indistinguishable from an age of 341 Ma obtained for the nearby Fountain Lake Group volcanic rocks, within estimated uncertainties. Measured Carboniferous granite ages are uncommon in the Appalachian Orogen of eastern Canada. The geochemical character of these plutons indicates that they result from crustal extension. This extension and the compression observed in the granites with ductile deformation are related to transcurrent motion between the Avalon and Meguma terranes along the Minas fault zone.Preliminary Rb–Sr whole-rock data from poorly exposed plutons in the northern part of the Cobequid Highlands suggest a Middle to Late Devonian or older age. These plutons may represent an earlier phase of crustal extension.

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