The West Indian Road pit, central Nova Scotia: key to the Early Cretaceous Chaswood Formation

2006 ◽  
Vol 43 (3) ◽  
pp. 391-403 ◽  
Author(s):  
Jean-Philippe Gobeil ◽  
Georgia Pe-Piper ◽  
David JW Piper
Keyword(s):  
Nova Scotia ◽  
Early Cretaceous ◽  
West Indian ◽  
Tectonic Deformation ◽  
Maritime Provinces ◽  
The West ◽  
South Mountain Batholith ◽  
The North ◽  
Quartz Arenite ◽  
Sand And Gravel

The West Indian Road pit is the only large outcrop in Nova Scotia of the Chaswood Formation, the terrestrial equivalent of the offshore Missisauga and Logan Canyon formations. It provides outcrop information on sedimentology, gravel petrology, and structures for a formation that is otherwise known from a few small overgrown pits and from boreholes. The Chaswood Formation in the pit is > 60 m thick and consists principally of sorted sand and gravel with three thinner clay units. Successions of sedimentary structures indicate deposition from a coarse-bedload river flowing to the east-southeast. Gravel consists principally of vein quartz, quartz arenite, and subarkose, together with minor igneous lithologies that can be matched to sources in the Cobequid Highlands to the north. Quartz arenite and subarkose appear derived from Carboniferous Horton Group. Single-crystal 40Ar/39Ar dates of detrital muscovite are a little older than the muscovite ages for the South Mountain batholith, interpreted to mean that the muscovite is second cycle from the Horton Group, which records the earliest unroofing of the batholith. The Chaswood Formation accumulated during progressive tectonic deformation along NNE-trending strike-slip faults in basement rocks, resulting in syn-sedimentary faulting and local unconformities. Sedimentation kept pace with the creation of accommodation. Unrelated younger deformation folded the Chaswood Formation at the pit into an east–west-trending syncline. The Early Cretaceous paleogeography of the Maritime Provinces is interpreted to have consisted of fault-bound horsts shedding coarse detritus surrounded by an interconnected series of basins that accumulated fluvial sands and gravels and overbank muds with well-developed paleosols.

scholarly journals Alethopteris and Neuralethopteris from the lower Westphalian (Middle Pennsylvanian) of Nova Scotia and New Brunswick, Maritime Provinces, Canada

2020 ◽  
Vol 56 ◽  
pp. 111-145
Author(s):  
Carmen Álvarez-Vázquez
Keyword(s):  
United States ◽  
Nova Scotia ◽  
New Brunswick ◽  
Western Europe ◽  
The United States ◽  
Maritime Provinces ◽  
Eastern Canada ◽  
Systematic Revision ◽  
Insufficient Attention ◽  
The North

A systematic revision of Alethopteris and Neuralethopteris from upper Namurian and lower Westphalian (Middle Pennsylvanian) strata of Nova Scotia and New Brunswick, eastern Canada, has demonstrated the presence of eight species: Alethopteris bertrandii, Alethopteris decurrens, Alethopteris cf. havlenae, Alethopteris urophylla, Alethopteris cf. valida, Neuralethopteris pocahontas, Neuralethopteris schlehanii and Neuralethopteris smithsii. Restudy of the Canadian material has led to new illustrations, observations and refined descriptions of these species. Detailed synonymies focus on records from Canada and the United States. As with other groups reviewed in earlier articles in this series, it is clear that insufficient attention has been paid to material reposited in Canadian institutions in the European literature. The present study emphasizes the similarity of the North American flora with that of western Europe, especially through the synonymies.

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.

New records of Melyridae (Coleoptera) from the Maritime Provinces of Canada

2005 ◽  
Vol 137 (3) ◽  
pp. 325-327 ◽  
Author(s):  
Christopher G. Majka
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
North American ◽  
New Records ◽  
Atlantic Canada ◽  
Maritime Provinces ◽  
The North ◽  
The World

The Melyridae (soft-winged flower beetles) are a diverse, abundant, and widespread family of beetles found throughout the world, with more than 300 genera and 6000 species worldwide (Mayor 2002). Melyrids are particularly abundant in dry, temperate regions of the world. Mayor's (2002) synopsis of the North American fauna includes 58 genera and 520 species. Bright (1991) tabulates 49 species in 14 genera in the Canadian fauna. Only one species, the introduced Palearctic Malachius aeneus (L.), was reported for Atlantic Canada, with records in New Brunswick, Nova Scotia, and Newfoundland.

Thermal history of the southwestern Meguma zone, Nova Scotia, from an 40Ar/39Ar and fission track dating study of intrusive rocks

1987 ◽  
Vol 24 (10) ◽  
pp. 1952-1965 ◽  
Author(s):  
P. H. Reynolds ◽  
P. Elias ◽  
G. K. Muecke ◽  
A. M. Grist
Keyword(s):  
Nova Scotia ◽  
Fission Track ◽  
Southern Region ◽  
Small Areas ◽  
South Mountain Batholith ◽  
Sedimentary Sequences ◽  
The North ◽  
Meguma Terrane ◽  
Fission Track Ages ◽  
Intrusive Activity

Two geologically distinct regions within the Meguma terrane have been studied in detail and are shown to have contrasting thermal histories. This conclusion is based on 31 new 40Ar/39Ar age spectra on micas, K-feldspars, and hornblendes from several of the plutons in southern Nova Scotia, which are satellites to the much larger South Mountain batholith (SMB). In addition, we report four K-feldspar age spectra from a locality in the northeastern part of the SMB and seven fission track ages from both the southern and northern areas.The complex age spectrum of hornblende from a mafic phase associated with the Barrington Passage pluton suggests a minimum intrusive age of 385 Ma, a result consistent with geologic evidence that this pluton represents an early, less evolved magmatic pulse. Later intrusive activity appears to have been coeval with the intrusion of the SMB at ca. 370 Ma ago. In the southern region, argon clocks in feldspars were completely reset and mica clocks variably reset by a later thermal event. The cumulative geochronologic and geologic evidence constrains this event to 300–320 Ma ago. In the SMB, this Alleghanian/Hercynian thermal disturbance is much less pronounced and appears to be localized to small areas that are often associated with economic mineralization.K-feldspars from the southern plutons record an episode of argon loss 220–230 Ma ago, which is less evident in the SMB to the north. Upper Triassic dike injection in the southern region, associated with the initial rifting phase of the Canadian Atlantic margin, accompanied this milder thermal pulse.Apatites in the two regions record a mean fission track age of ca. 180 Ma, which we attribute to the final cooling of the terrane below about 100 °C. The timing of this event coincides with regional uplift recorded in sedimentary sequences along much of the Maritime continental shelf.

Monitoring Agricultural Drought in the West Indies

2005 ◽  
Author(s):  
Abraham Anthony Chen ◽  
Trevor Falloon
Keyword(s):  
West Indies ◽  
West Indian ◽  
Caribbean Sea ◽  
Lesser Antilles ◽  
Greater Antilles ◽  
The West ◽  
Blue Mountains ◽  
The North ◽  
The Caribbean ◽  
Azores High

The core of the West Indies consists of the archipelago of islands that stretches southeast from the Yucatan and Florida peninsulas to Venezuela. Generally the term “West Indies” is synonymous with the “Antilles” and is therefore often used to refer to the islands that compose the Greater and Lesser Antilles. The islands of the Greater Antilles include Cuba, Hispaniola, Puerto Rico, and Jamaica—all located in the north Caribbean Sea—while the Lesser Antilles encompasses the smaller islands found to the south and east. In total, the West Indies embraces about 25 island territories. There are complex mountain ranges in the Greater Antilles, such as the Blue Mountains (2257 m) in central Jamaica and the Pico Duarte (3175 m) in the Dominican Republic, smaller volcanic peaks in the northeast island arc, and low-lying islands composing the remainder of the Lesser Antilles. The variation in local topography contributes significantly to the general rainfall pattern across the West Indian islands, as the windward sides of the larger and more mountainous islands are rainy and windswept, while the leeward sides are drier. In comparison, the low-lying eastern islands receive much less rainfall due to their lack of topographic relief and are much more dependent on seasonal rains. It is, however, the location of the West Indian islands between the permanent high pressure zone of the subtropical north Atlantic (the Azores high) and the equatorial trough of low pressure that gives rise to the mean monthly West Indian rainfall depicted in figure 11.2. Early in the year (December through March) and for a brief period in July, the Caribbean is dominated by subsidence from the inner zone of the Azores high and is at its driest. Rainfall during this period (barring July) is largely from the intrusion of fronts from North America. By the onset of the rainy season, however, the Azores high drifts farther north, resulting in weakened trade winds. At the same time, the Caribbean Sea warms up.

scholarly journals The Rockall and the Orphan Basins of the Southern North Atlantic Ocean: Determining Continuous Basins across Conjugate Margins

Geosciences ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 178
Author(s):  
Heide MacMahon ◽  
J. Kim Welford ◽  
Larry Sandoval ◽  
Alexander L. Peace
Keyword(s):  
Atlantic Ocean ◽  
Early Cretaceous ◽  
North Atlantic ◽  
Driving Forces ◽  
North Atlantic Ocean ◽  
The West ◽  
The North ◽  
Plate Reconstructions ◽  
Conjugate Margins ◽  
Atlantic Margin

Reconstructions of the opening of the North Atlantic Ocean generally result in the Orphan Basin, offshore Newfoundland, Canada, lying approximately conjugate to the rift basins on the Irish Atlantic margin at the onset of seafloor spreading toward the end of the Early Cretaceous. Most of these plate reconstructions have involved rigid plates with plate motions based solely on the interpretation of oceanic magnetic anomalies. In particular, these reconstructions often show the Rockall Basin, west of Ireland, forming a continuous Mesozoic basin with the West Orphan Basin, offshore Newfoundland. However, more recent plate reconstructions involving deformable plates have called this conjugate relationship into question. The goal of this study is to investigate the validity of this potentially continuous basin system by reconstructing and restoring present-day seismically-constrained geological models both spatially and temporally back to their original configurations pre-rift. By comparing the reconstructions in terms of sedimentary package thicknesses and crustal thicknesses in 3D, using both rigid and deformable plate reconstructions to orient the reconstructed models, we are able to test different basin connectivity scenarios using a multidisciplinary approach. Our analysis provides subsurface geophysical support for the hypothesis that the Rockall Basin was originally conjugate to and continuous with the East Orphan Basin during Jurassic rifting, later linking to the West Orphan Basin as rifting evolved during the Early Cretaceous. This complex basin evolution example highlights the need for using 3D rifting mechanism models to properly understand the fundamental driving forces during rifting and has significant implications for assessing basin prospectivity across conjugate margin pairs.

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