40Ar/39Ar dating in the Lochaber–Mulgrave area, northern mainland Nova Scotia: implications for timing of regional metamorphism and sediment provenance in the Late Devonian – Early Carboniferous Horton Group

2004 ◽  
Vol 41 (8) ◽  
pp. 987-996 ◽  
Author(s):  
P H Reynolds ◽  
S M Barr ◽  
C E White ◽  
P J Ténière
Keyword(s):  
Nova Scotia ◽  
Regional Metamorphism ◽  
Early Carboniferous ◽  
Fault System ◽  
Sediment Provenance ◽  
Late Devonian ◽  
The South ◽  
Two Samples ◽  
Meguma Terrane ◽  
Fusion Analysis

40Ar/39Ar dating of whole-rock samples and muscovite separates using age spectrum analysis, and of single muscovite grains using total fusion analysis, yields new insights into the timing of regional metamorphism and sediment provenance in the Late Devonian – Early Carboniferous Horton Group in the Lochaber–Mulgrave area of Nova Scotia. The time of regional metamorphism is constrained to ca. 340–335 Ma by whole-rock spectra from well-cleaved slate and shale samples from the lowermost Clam Harbour River and overlying Tracadie Road formations of the Horton Group. This ca. 340–335 Ma event may have been the result of burial and deformation of the Horton Group by older volcanic and sedimentary rocks of the Guysborough Group, which were overthrust from the south as the result of development of a positive flower structure at a restraining bend along the Cobequid–Chedabucto fault system, the boundary between the Meguma and Avalon terranes. Detrital muscovite ages of ca. 410–380 and ca. 500 Ma were obtained from single-grain analysis and from spectral analysis of separated grains. Whole-rock spectra for two samples from a mylonitic metasedimentary unit in the Cape Porcupine Complex yielded plateau ages of 364 ± 4 and 367 ± 4 Ma, providing a likely source for ca. 370–360 Ma detrital muscovite, ages that may be reflected in some of the age spectrum data. However, the Meguma terrane to the south is the most likely source for most of the detrital muscovite.

Sediment sources and dispersion as revealed by single-grain 40Ar/39Ar ages of detrital muscovite from Carboniferous and Cretaceous rocks in mainland Nova ScotiaGeological Survey of Canada contribution 20090289.

2010 ◽  
Vol 47 (7) ◽  
pp. 957-970 ◽  
Author(s):  
Peter H. Reynolds ◽  
Georgia Pe-Piper ◽  
David J.W. Piper
Keyword(s):  
Nova Scotia ◽  
Early Cretaceous ◽  
Early Carboniferous ◽  
Metamorphic Rocks ◽  
Sediment Sources ◽  
The South ◽  
Lower Carboniferous ◽  
South Mountain Batholith ◽  
Single Grain ◽  
Meguma Terrane

Single-grain ages of detrital muscovite from 15 sand(stone) samples from the Lower Carboniferous Horton Group and the Lower Cretaceous Chaswood Formation of central Nova Scotia were used to infer the nature of the Early Carboniferous unroofing of the Meguma terrane and the reworking of Carboniferous rocks in the Early Cretaceous. In the western Windsor Basin, a sample from the oldest Horton Group rocks yielded ages principally between ca. 400 and 380 Ma, suggesting that most of the muscovite present came from the metamorphic rocks of the Meguma terrane but was variably reset by the intrusion of the South Mountain Batholith at ca. 380 Ma. Other samples in this part of the basin show partial post-depositional resetting. Younger Horton Group metamorphic rocks in the eastern Windsor Basin contain many grains with ages of ca. 370–360 Ma, suggesting derivation from the central core of the South Mountain Batholith or the Musquodoboit Pluton. Horton Group sandstones from the western part of the St. Marys Basin contain muscovite derived from the Liscomb Complex along with metamorphic muscovite variably reset by the intrusion of this complex. In general, our data suggest predominant northward dispersion of muscovite from the Meguma terrane to the Horton Group and a lack of axial transport along the Horton grabens through central Nova Scotia, a pattern compatible with tectonic models in which the Meguma terrane is ramped over the Avalon terrane. Muscovite ages obtained for the Chaswood Formation compare well with those from the Horton Group rocks in the western St. Marys Basin. These rocks may have been exposed to rapid erosion by reactivation of the Cobequid–Chedabucto fault zone in the Early Cretaceous and the resulting sediments were perhaps transported to depositional sites along northeast-trending faults. Unlike the detrital monazites in these rocks, there is no evidence that any of the detrital muscovites came from distal sources outside the Meguma terrane.

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

Kennetcook thrust system: late Paleozoic transpression near the southern margin of the Maritimes Basin, Nova Scotia

2010 ◽  
Vol 47 (2) ◽  
pp. 137-159 ◽  
Author(s):  
John W.F. Waldron ◽  
Carlos G. Roselli ◽  
John Utting ◽  
Stanley K. Johnston
Keyword(s):  
Nova Scotia ◽  
Early Carboniferous ◽  
Late Paleozoic ◽  
The South ◽  
Seismic Profiles ◽  
Southern Margin ◽  
Fault Structures ◽  
Thrust System ◽  
Maritimes Basin

A major zone of deformation affects Early Carboniferous rocks in the southern part of the Maritimes Basin of Nova Scotia, close to the boundary between the Avalon and Meguma terranes of the Appalachians. Field relationships at Cheverie indicate thrusting of Tournaisian Horton Group clastics over Viséan Windsor Group carbonates, evaporites, and clastics, a relationship confirmed by the Cheverie #01 well. Mapped relationships to the south indicate that a system of thrusts, here termed the Kennetcook thrust system, climbs upsection to the southeast, becoming a décollement within Windsor Group evaporites. Industry seismic profiles clearly show deformed Windsor Group, and include fold and fault structures indicative of evaporite flow and solution collapse. Below the Windsor Group, half-grabens filled with Horton Group are clearly imaged; offsets at graben-related faults show that these structures were inverted during later shortening. Above the Windsor Group, less deformed rocks of the Pennsylvanian Scotch Village Formation (Cumberland Group) fill minibasins created by the withdrawal or solution of deformed Windsor evaporites. The timing of thrusting is constrained by these relationships and by crosscutting intrusions to a narrow interval around the Mississippian–Pennsylvanian boundary prior to ∼315 Ma. Deformation was probably related to dextral transpression along the former Avalon–Meguma boundary. Depending on how shortening was transmitted to the southeast, up to 1500 km2 of southern mainland Nova Scotia may be underlain by tectonically transported rocks.

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.

La tectonique cisaillante polyphasee du Sud Limousin (Massif central francais) et son interpretation dans un modele d'evolution polycyclique de la chaine hercynienne

2000 ◽  
Vol 171 (3) ◽  
pp. 295-307 ◽  
Author(s):  
Jean-Yves Roig ◽  
Michel Faure
Keyword(s):  
Middle Devonian ◽  
Early Carboniferous ◽  
Evolution Model ◽  
Ductile Deformation ◽  
Late Devonian ◽  
French Massif Central ◽  
The South ◽  
Massif Central ◽  
Mafic Rocks

Abstract Structural, kinematics and thermo-barometric analyses of the ductile deformation of the south-Limousin metamorphic formations show a polyphase shear tectonics corresponding to two different thrusting events. The older one, is a to the top-to-the-SW thrusting during middle Devonian. This deformation occurs under minimum PT conditions of 7 Kbar/700 degrees C simultaneously to anatexis. The second event is a top-to-the-NW shearing which occurred in late Devonian-early Carboniferous under Barrovian conditions (5 kbar/600 degrees C). Diorites bodies and non-eclogitized mafic rocks allow us to argue for an extensional phase between the two thrusting events. These two ductile and syn-metamorphic deformations take place in a polycyclic evolution model of the Hercynian belt of the French Massif Central.

Detrital zircon characterization of early Cambrian sandstones from East Avalonia and SE Ireland: implications for terrane affinities in the peri-Gondwanan Caledonides

2018 ◽  
Vol 156 (07) ◽  
pp. 1217-1232 ◽  
Author(s):  
JOHN W.F. WALDRON ◽  
DAVID I. SCHOFIELD ◽  
GRAHAM PEARSON ◽  
CHIRANJEEB SARKAR ◽  
YAN LUO ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Laser Ablation ◽  
West Africa ◽  
Detrital Zircon ◽  
Early Cambrian ◽  
The South ◽  
The Core ◽  
Stage 4 ◽  
Meguma Terrane

AbstractThe Caledonides of Britain and Ireland include terranes attributed to both Laurentian and Gondwanan sources, separated along the Solway line. Gondwanan elements to the south have been variably assigned to the domains Ganderia and East Avalonia. The Midland Platform forms the core of East Avalonia but its provenance is poorly known. Laser ablation split-stream analysis yields information about detrital zircon provenance by providing simultaneous U–Pb and Lu–Hf data from the same ablated volume. A sample of Red Callavia Sandstone from uppermost Cambrian Stage 3 of the Midland Platform yields a U–Pb age spectrum dominated by Neoproterozoic and Palaeoproterozoic sources, resembling those in the Welsh Basin, the Meguma Terrane of Nova Scotia and NW Africa. Initial εHf values suggest that the Neoproterozoic zircon component was derived mainly from crustal sources < 2 Ga, and imply that the more evolved Palaeoproterozoic grains were transported into the basin from an older source terrane, probably the Eburnean Orogen of West Africa. A sample from Cambrian Stage 4 in the Bray Group of the Leinster–Lakesman Terrane shows, in contrast, a distribution of both U–Pb ages and εHf values closely similar to those of the Gander Terrane in Newfoundland and other terranes attributed to Ganderia, interpreted to be derived from the margin of Amazonia. East Avalonia is clearly distinct from Ganderia, but shows evidence for older crustal components not present in West Avalonia of Newfoundland. These three components of the Appalachian–Caledonide Orogen came from distinct sources on the margin of Cambrian Gondwana.

Structural setting and age of the Partridge Island block, southern New Brunswick, Canada: a link to the Cobequid Highlands of northern mainland Nova Scotia

2014 ◽  
Vol 51 (1) ◽  
pp. 1-24 ◽  
Author(s):  
Adrian F. Park ◽  
Robert L. Treat ◽  
Sandra M. Barr ◽  
Chris E. White ◽  
Brent V. Miller ◽  
...  
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Tectonic Setting ◽  
Sedimentary Rocks ◽  
Alkali Feldspar ◽  
Early Carboniferous ◽  
Late Devonian ◽  
Island Formation ◽  
Lake Formation ◽  
Saint John

The Partridge Island block is a newly identified tectonic element in the Saint John area of southern New Brunswick, located south of and in faulted contact with Proterozoic and Cambrian rocks of the Ganderian Brookville and Avalonian Caledonia terranes. It includes the Lorneville Group and Tiner Point complex. The Lorneville Group consists of interbedded volcanic and sedimentary rocks, subdivided into the Taylors Island Formation west of Saint John Harbour and West Beach Formation east of Saint John Harbour. A sample from thin rhyolite layers interbedded with basaltic flows of the Taylors Island Formation at Sheldon Point yielded a Late Devonian – Early Carboniferous U–Pb (zircon) age of 358.9 +6/–5 Ma. Petrological similarities indicate that all of the basaltic rocks of the Taylors Island and West Beach formations are of similar age and formed in a continental within-plate tectonic setting. West of Saint John Harbour, basaltic and sedimentary rocks of the Taylors Island Formation are increasingly deformed and mylonitic to the south, and in part tectonically interlayered with mylonitic granitoid rocks and minor metasedimentary rocks of the Tiner Point complex. Based on magnetic signatures, the deformed rocks of the Tiner Point complex can be traced through Partridge Island to the eastern side of Saint John Harbour, where together with the West Beach Formation, they occupy a thrust sheet above a redbed sequence of the mid-Carboniferous Balls Lake Formation. The Tiner Point complex includes leucotonalite and aegirine-bearing alkali-feldspar granite with A-type chemical affinity and Early Carboniferous U–Pb (zircon) ages of 353.6 ± 5.7 and 346.4 ± 0.7 Ma, respectively. Based on similarities in age, petrological characteristics, alteration, iron oxide – copper – gold (IOCG)-type mineralization, and deformation style, the Partridge Island block is correlated with Late Devonian – Early Carboniferous volcanic–sedimentary–plutonic rocks of the Cobequid Highlands in northern mainland Nova Scotia. Deformation was likely a result of dextral transpression along the Cobequid–Chedabucto fault zone during juxtaposition of the Meguma terrane.

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