scholarly journals Petrology, tectonic setting, and economic potential of devonian peraluminous granitoid plutons in the Canso and Forest Hill areas, eastern Meguma Terrane, Nova Scotia

1991 ◽  
Author(s):  
J D Hill
Keyword(s):  
Nova Scotia ◽  
Tectonic Setting ◽  
Economic Potential ◽  
Meguma Terrane

Petrology, age, and tectonic setting of the Seal Island Pluton, offshore southwestern Nova Scotia

2007 ◽  
Vol 44 (10) ◽  
pp. 1467-1478 ◽  
Author(s):  
Patrick C Moran ◽  
Sandra M Barr ◽  
Chris E White ◽  
Michael A Hamilton
Keyword(s):  
Nova Scotia ◽  
Tectonic Setting ◽  
Heavy Rare Earth ◽  
Zircon Age ◽  
Relative Age ◽  
Form Part ◽  
Heavy Rare Earth Elements ◽  
Granitoid Rocks ◽  
Meguma Terrane ◽  
Granite Samples

The Seal Island Pluton outcrops only on small islands located on the continental shelf 45 km south of Nova Scotia, although geophysical data indicate that the pluton is part of large granitoid units that cover thousands of square kilometres farther offshore. Based on the island outcrops, the Seal Island Pluton consists of biotite monzogranite and muscovite–biotite monzogranite of uncertain relative age. Metasedimentary xenoliths combined with characteristic magnetic patterns indicate that the pluton intruded the Cambrian–Ordovician Meguma Group. Compared with the biotite monzogranite, the muscovite–biotite monzogranite is higher in SiO2, more peraluminous, and more depleted in heavy rare-earth elements, and also has lower εNd (–1.39 versus +0.82), possibly the result of more contamination by Meguma Group sedimentary rocks. The biotite monzogranite yielded a Late Devonian U–Pb (zircon) age of 362.8 ± 0.7 Ma. Although the relatively minor petrological differences between the two units do not preclude a co-magmatic relationship, the muscovite–biotite monzogranite could be 10–15 Ma older than the biotite monzogranite, based on its petrological similarities to parts of the onshore ca. 376–372 Ma Shelburne and Port Mouton plutons. Comparison with granite samples in offshore drill core indicates that granitoid rocks similar to those exposed on Seal and surrounding islands form part of large plutons farther offshore in the Meguma terrane. The age and petrochemical data from both onshore and offshore plutons indicate that peraluminous granitoid rocks in the Meguma terrane were derived from similar sources over a span of at least 20 million years. Magma genesis may have been related to mantle upwelling and stepping back of the subduction zone to the southeast subsequent to docking of Meguma terrane with adjacent Avalonia.

Petrology, age, and tectonic setting of the White Rock Formation, Meguma terrane, Nova Scotia: evidence for Silurian continental rifting

2002 ◽  
Vol 39 (2) ◽  
pp. 259-277 ◽  
Author(s):  
Lisa A MacDonald ◽  
Sandra M Barr ◽  
Chris E White ◽  
John WF Ketchum
Keyword(s):  
Nova Scotia ◽  
Shear Zone ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Granitic Rocks ◽  
Chemical Characteristics ◽  
Rock Formation ◽  
Meguma Terrane ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

The White Rock Formation in the Yarmouth area of the Meguma terrane of southern Nova Scotia consists mainly of mafic tuffaceous rocks with less abundant mafic flows, epiclastic and clastic sedimentary rocks, and minor intermediate and felsic crystal tuff. It is divided into seven map units that appear to young from west to east, inconsistent with a previously assumed synclinal structure. The White Rock Formation is flanked on both northwest and southeast by mainly the Cambrian to Lower Ordovician Halifax Formation; the western contact is interpreted to be a sheared disconformity, whereas the eastern contact appears to be a major brittle fault and shear zone that juxtaposes different crustal levels. The granitic Brenton Pluton forms a faulted lens within the eastern shear zone. A felsic tuff from the upper part of the White Rock Formation yielded a U–Pb zircon age of 438+3–2 Ma, identical within error to published ages for the Brenton Pluton and felsic volcanic rocks near the base of the White Rock Formation in the Torbrook area of western Nova Scotia. The chemical characteristics of the mafic volcanic rocks and associated mafic intrusions consistently indicate alkalic affinity and a continental within-plate setting. The felsic volcanic rocks and Brenton Pluton have chemical characteristics of within-plate anorogenic granitic rocks, and the pluton is interpreted to be comagmatic with the felsic volcanic rocks. The igneous activity may have occurred in response to extension as the Meguma terrane rifted away from Gondwana in the latest Ordovician to Early Silurian. Epsilon Nd values are similar to those in voluminous Devonian plutonic rocks of the Meguma terrane, and the magmas appear to have been derived from similar sources.

Syn-Acadian emplacement model for the South Mountain batholith, Meguma Terrane, Nova Scotia: Magnetic fabric and structural analyses

1997 ◽  
Vol 109 (10) ◽  
pp. 1279-1293 ◽  
Author(s):  
Keith Benn ◽  
Richard J. Horne ◽  
Daniel J. Kontak ◽  
Geoffrey S. Pignotta ◽  
Neil G. Evans
Keyword(s):  
Nova Scotia ◽  
Magnetic Fabric ◽  
The South ◽  
South Mountain Batholith ◽  
Meguma Terrane

40Ar/39Ar ages of detrital muscovite within Lower Cambrian and Carboniferous clastic sequences in northern Nova Scotia and southern New Brunswick: implications for provenance regions

1997 ◽  
Vol 34 (2) ◽  
pp. 156-168 ◽  
Author(s):  
R. D. Dallmeyer ◽  
J. D. Keppie ◽  
R. D. Nance
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Lower Cambrian ◽  
Source Region ◽  
Regional Distribution ◽  
Coarse Grained ◽  
Cape Breton Island ◽  
Late Proterozoic ◽  
Cape Breton ◽  
Meguma Terrane

Detrital muscovite from lowermost Cambrian sequences exposed in the Avalon Composite Terrane in Nova Scotia and New Brunswick record 40Ar/39Ar plateau ages of ca. 625–600 Ma. These are interpreted to date times of cooling in source areas. The regional distribution of coarse-grained detrital muscovite in Lower Cambrian rocks of Avalonian overstep sequences suggests a source region of dimensions considerably larger than any presently exposed in Appalachian segments of the Avalon Composite Terrane. Late Proterozoic tectonic reconstructions locate the Avalon Composite Terrane adjacent to northwestern South America, thereby suggesting a possible source within Late Proterozoic PanAfrican – Brasiliano orogens. Detrital muscovite from clastic sequences of the proximally derived, Lower Carboniferous (Tournaisian) Horton Group and the more distal Upper Carboniferous (Westphalian D – Stephanian) Pictou Group in Nova Scotia records 40Ar/39Ar spectra that define plateau ages of ca. 390–380 Ma (Horton Group) and and ca. 370 Ma (Pictou Group). Finer grained fractions from samples of the Horton Group display more internally discordant age spectra defining total-gas ages of ca. 397–395 Ma. A provenance for the finer muscovite may be found in southern Nova Scotia where Cambrian–Ordovician turbidites of the Meguma Group display a regionally developed micaceous cleavage of this age. The ca. 390–380 Ma detrital muscovites probably were derived from granite stocks presently exposed in proximal areas of northernmost Cape Breton Island. A more distal source for the ca. 370 Ma detrital muscovites in the Pictou Group is suggested by its original extensive distribution, although a local, possibly recycled, source may also have been present. The presence of only 400–370 Ma detrital muscovite suggests a rapidly exhumed orogenic source with characteristics similar to those of crystalline rocks presently exposed in the Cape Breton Highlands and (or) the Meguma Terrane.

scholarly journals Effects of fluid flow, cooling and deformation as recorded by 40Ar/39Ar, Rb–Sr and zircon fission track ages in very low- to low-grade metamorphic rocks in Avalonian SE Cape Breton Island (Nova Scotia, Canada)

2014 ◽  
Vol 152 (5) ◽  
pp. 767-787 ◽  
Author(s):  
ARNE P. WILLNER ◽  
SANDRA M. BARR ◽  
JOHANNES GLODNY ◽  
HANS-JOACHIM MASSONNE ◽  
MASAFUMI SUDO ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Fission Track ◽  
White Mica ◽  
Low Grade ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Zircon Fission Track ◽  
Meguma Terrane ◽  
Fission Track Ages ◽  
Oriented Parallel

Abstract40Ar/39Ar in situ UV laser ablation of white mica, Rb–Sr mineral isochrons and zircon fission track dating were applied to determine ages of very low- to low-grade metamorphic processes at 3.5±0.4 kbar, 280±30°C in the Avalonian Mira terrane of SE Cape Breton Island (Nova Scotia). The Mira terrane comprises Neoproterozoic volcanic-arc rocks overlain by Cambrian sedimentary rocks. Crystallization of metamorphic white mica was dated in six metavolcanic samples by 40Ar/39Ar spot age peaks between 396±3 and 363±14 Ma. Rb–Sr systematics of minerals and mineral aggregates yielded two isochrons at 389±7 Ma and 365±8 Ma, corroborating equilibrium conditions during very low- to low-grade metamorphism. The dated white mica is oriented parallel to foliations produced by sinistral strike-slip faulting and/or folding related to the Middle–Late Devonian transpressive assembly of Avalonian terranes during convergence and emplacement of the neighbouring Meguma terrane. Exhumation occurred earlier in the NW Mira terrane than in the SE. Transpression was related to the closure of the Rheic Ocean between Gondwana and Laurussia by NW-directed convergence. The 40Ar/39Ar spot age spectra also display relict age peaks at 477–465 Ma, 439 Ma and 420–428 Ma attributed to deformation and fluid access, possibly related to the collision of Avalonia with composite Laurentia or to earlier Ordovician–Silurian rifting. Fission track ages of zircon from Mira terrane samples range between 242±18 and 225±21 Ma and reflect late Palaeozoic reburial and reheating close to previous peak metamorphic temperatures under fluid-absent conditions during rifting prior to opening of the Central Atlantic Ocean.

scholarly journals Sedimentary and tectonic setting of a mass-transport slope deposit in the Halifax Group, Halifax Peninsula, Nova Scotia, Canada

2015 ◽  
Vol 51 (1) ◽  
pp. 084 ◽  
Author(s):  
John W.F. Waldron ◽  
Rebecca A. Jamieson ◽  
Hayley D. Pothier ◽  
Chris E. White
Keyword(s):  
Nova Scotia ◽  
Mass Transport ◽  
Tectonic Setting ◽  
Tectonic Deformation ◽  
Font Size ◽  
Fine Grained ◽  
Metasedimentary Rocks ◽  
Internal Structures ◽  
Transport Direction ◽  
Deformation Features

<p align="LEFT">Fine-grained metasedimentary rocks of the Halifax Group in southern mainland Nova Scotia can be subdivided into mappable units. In Halifax Peninsula, sulphide-rich hornfels, black slate, metasiltstone, and metasandstone of the Cunard Formation are overlain by grey metasedimentary rocks with abundant cross-laminations and local carbonate and calc-silicate concretions, assigned to the Bluestone Quarry Formation. No fossils are known from the Bluestone Quarry Formation but lithological correlatives elsewhere are Tremadocian. The Bluestone Quarry Formation is here divided into four members. The lowest (Point Pleasant member) contains thin parallel-laminated and cross-laminated <span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">metasandstone beds with Bouma T</span></span><span style="font-family: MinionPro-Regular; font-size: xx-small;"><span style="font-family: MinionPro-Regular; font-size: xx-small;">bcde </span></span><span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">and T</span></span><span style="font-family: MinionPro-Regular; font-size: xx-small;"><span style="font-family: MinionPro-Regular; font-size: xx-small;">cde </span></span><span style="font-family: MinionPro-Regular; font-size: small;"><span style="font-family: MinionPro-Regular; font-size: small;">structures, and thicker beds with Bouma ‘a’ divisions. The Black Rock </span></span>Beach member lacks the thicker massive beds and is dominated by rippled and cross-laminated metasedimentary rocks. The overlying Chain Rock member, an erosion-resistant ridge-forming unit, is disrupted by folds and boudinage. Bedding is truncated at the upper contact, and the internal structures are overprinted by (and therefore predate) the Neoacadian cleavage. They are interpreted as products of synsedimentary mass transport. Scarce folds in the Chain Rock member and current ripples in the underlying unit are consistent with a N or NW transport direction. The overlying Quarry Pond member consists of thinly bedded coherent metasedimentary rocks that generally resemble those of the Black Rock Beach member. Although there are indications of upward shallowing in equivalent successions elsewhere in the Halifax Group, the presence of a major mass transport deposit in the Bluestone Quarry Formation shows that this part of the Halifax Group was deposited on a submarine paleoslope. The failure of geologists to identify this feature in much-visited outcrops testifies to the difficulty of identifying synsedimentary deformation features that have been overprinted by later tectonic deformation.</p>

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