Occurrence and significance of Silurian K-bentonite beds at Arisaig, Nova Scotia, eastern Canada

1997 ◽  
Vol 34 (12) ◽  
pp. 1630-1643 ◽  
Author(s):  
Stig M. Bergström ◽  
Warren D. Huff ◽  
Dennis R. Kolata ◽  
Michael J. Melchin
Keyword(s):  
Nova Scotia ◽  
North America ◽  
Geochemical Data ◽  
Northern Coast ◽  
Calc Alkaline ◽  
The South ◽  
Eastern Canada ◽  
Critical Information ◽  
Plate Margin ◽  
Alkaline Magmas

The most extensive succession of K-bentonite beds known in the Silurian of North America occurs at Arisaig on the northern coast of Nova Scotia. At least 40 ash beds are present in the Llandoverian Ross Brook Formation and at least four in the early Ludlovian McAdam Brook Formation. Most of the beds are thin (< 5 cm), but one bed (the Smith Brook K-bentonite bed) in the late Llandoverian crenulata Zone and another (the McAdam Brook K-bentonite bed) in the early Ludlovian nilssoni Zone each reach a thickness of 20 cm. New graptolite collections provide critical information on the biostratigraphic position of the K-bentonite beds in the Ross Brook Formation. Geochemical data show that the Arisaig ash beds represent calc-alkaline magmas from plate margin, subduction-related volcanic vents. Differences in K-bentonite stratigraphic distribution, combined with paleogeographic considerations, suggest that the volcanoes were located much farther to the south in the Iapetus than the source volcanoes of the British–Baltoscandian Llandoverian K-bentonites.

A comparison of magnetic character and alteration in three granite drill cores from eastern Canada

1988 ◽  
Vol 25 (8) ◽  
pp. 1141-1150 ◽  
Author(s):  
K. L. Harding ◽  
W. A. Morris ◽  
S. J. Balch ◽  
P. Lapointe ◽  
A. G. Latham
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
The South ◽  
Eastern Canada ◽  
General Observation ◽  
South Mountain Batholith ◽  
Magnetite Content ◽  
Bulk Magnetic Susceptibility ◽  
Primary Oxidation ◽  
Drill Cores

Bulk magnetic susceptibility (BMS) measurements have been made on granite drill cores from the St. George batholith (New Brunswick), the South Mountain batholith (Nova Scotia), and the Wedgeport pluton (Nova Scotia). The primary magnetite concentrations of the two Nova Scotia cores are statistically indistinguishable, thus lending support to the hypothesis that the Wedgeport pluton, despite being 50 Ma younger, is a satellite of the South Mountain batholith.The St. George core has a primary magnetite concentration over 30 times greater than the Nova Scotia cores, but low-temperature alteration (attributable to subsurface weathering) has greatly reduced its magnetite content. The two Nova Scotia S-type granites are shown to fall into the ilmenite-series category, whereas the St. George granite, which is either S- or A-type, is transitional between the magnetite and ilmenite series.The general observation of intergranular hematite and reduced BMS in the outcrops of some granites is suggested to have important consequences for primary oxidation studies and aeromagnetic interpretation.

scholarly journals Paleotethyan faunal/floral evidence in the Mississippian Maritimes Basin of Canada: An overview

2021 ◽  
pp. 1-20
Author(s):  
Pedro Cózar ◽  
Ian D. Somerville
Keyword(s):  
Nova Scotia ◽  
North America ◽  
New Brunswick ◽  
Western Europe ◽  
Statistical Analyses ◽  
Eastern Canada ◽  
Rheic Ocean ◽  
The North ◽  
Logical Connection ◽  
Maritimes Basin

Abstract In this study, middle to late Mississippian microfossil assemblages from the Maritimes Basin of eastern Canada (Nova Scotia, SW Newfoundland, and New Brunswick) are closely compared to those from Western Paleotethys basins. The comparison is focused mainly on foraminifers and calcareous algae. Most foraminifers and algae described from the Maritimes Basin are considered cosmopolitan, and the occurrence in western Europe and northern Africa of taxa previously considered endemic to the North America Realm suggests a close paleobiogeographic relationship. This European/African correlation is further supported by other foraminiferal/algal taxa, the importance of which were previously overlooked, including: Plectogyranopsis ex gr. P. hirosei (Okimura, 1965), Mikhailovella Ganelina, 1956, Koktjubina windsorensis (Mamet, 1970), Polysphaerinella bulla Mamet, 1973, Mstinia Dain in Dain and Grozdilova, 1953, Haplophragmina Reitlinger, 1950, Omphalotis Shlykova, 1969, Pseudolituotuba Vdovenko, 1971, Pseudoendothyra Mikhailov, 1939, Saccamminopsis (Sollas, 1921) Vachard and Cózar, 2003, Kamaenella Mamet and Roux, 1974, and Anthracoporellopsis Maslov, 1956. Some species recorded in the Maritimes Basin have been typically recorded in Britain and Ireland in the southern platform of Laurussia. This implies a connection via the Rhenohercynian Ocean, whereas statistical analyses suggest that Maritimes Basin assemblages are closer to those of the Gondwana platform, which could have been established via the Paleotethys Ocean, and also with terranes northwest of the Variscan Front, in which its most logical connection should be with a still-open Rheic Ocean during the Visean and early Serpukhovian. Those taxa demonstrate a more-or-less continuous faunal and microfloral interchange between the Maritimes Basin and the Western Paleotethys paleobiogeographic realm. Furthermore, the width of the Paleotethys and Rheic oceans separating these regions is not considered excessive, particularly during the late Visean and early Serpukhovian.

scholarly journals Metabasic rocks from the Variscan Schwarzwald (SW Germany): metamorphic evolution and igneous protoliths

2021 ◽  
Author(s):  
Rainer Altherr ◽  
Stefan Hepp ◽  
Hans Klein ◽  
Michael Hanel
Keyword(s):  
Amphibolite Facies ◽  
Geochemical Data ◽  
Bulk Rock ◽  
Calc Alkaline ◽  
Small Bodies ◽  
Plate Margin ◽  
Intimate Association ◽  
Facies Metamorphism ◽  
Back Arc ◽  
Igneous Protoliths

AbstractIn the Variscan Schwarzwald metabasic rocks form small bodies included within anatectic plagioclase-biotite gneisses. Many metabasites first underwent an eclogite-facies metamorphism at about 2.0 GPa and 670–700 °C, resulting in the assemblage garnet + omphacite + rutile + quartz ± epidote ± amphibole ± kyanite. Since these eclogites are nearly free of an OH-bearing phase, they underwent almost complete dehydration during subduction, suggesting formation along an average to warm top-of-the-slab geotherm of 10–13 °C/km. The age of the Variscan high-P/high-T metamorphism is > 333 Ma. After partial exhumation from ~ 65 to ~ 15 km depth, the eclogites were overprinted under increasing activity of H2O by a number of retrograde reactions. The degree of this overprint under amphibolite-facies conditions (0.4–0.5 GPa/675–690 °C) was very different. Up to now, only retrograde eclogites have been found, but some samples still contain omphacite. Kyanite is at least partially transformed to aggregates of plagioclase + spinel ± corundum ± sapphirine. On the other hand, there are amphibolites that are extensively recrystallized and show the assemblage amphibole + plagioclase + ilmenite/titanite ± biotite ± quartz ± sulphides. The last relic phase that can be found in such otherwise completely recrystallized amphibolites is rutile. After the amphibolite-facies metamorphism at ~ 333 Ma, the metabasites underwent a number of low-temperature transformations, such as sericitization of plagioclase, chloritization of amphibole, and formation of prehnite. The intimate association of metabasite bodies with gneisses of dominantly meta-greywacke compositions suggests derivation from an active plate margin. This view is corroborated by bulk-rock geochemical data. Excluding elements that were mobile during metamorphism (Cs, Rb, Ba, K, Pb, Sr, U), the concentrations of the remaining elements in most of the metabasites are compatible with a derivation from island-arc tholeiites, back-arc basin basalts or calc-alkaline basalts. Only some samples have MORB precursor rocks.

NOCTUA COMES, A NOCTUID NEW TO NORTH AMERICA (LEPIDOPTERA: NOCTUIDAE: NOCTUINAE)

1984 ◽  
Vol 116 (3) ◽  
pp. 479-480 ◽  
Author(s):  
Kenneth A. Neil
Keyword(s):  
British Columbia ◽  
Nova Scotia ◽  
North America ◽  
Museum Collection ◽  
Eastern Canada ◽  
Additional Specimen ◽  
Preliminary Identification ◽  
Palearctic Species ◽  
Simon Fraser University ◽  
Lepidoptera Noctuidae

On 19 August 1982, a female noctuid moth resembling the Palearctic species Noctua pronuba (Linnaeus), which has recently been introduced into Eastern Canada (Neil 1981), was collected at an ultraviolet light at Simon Fraser University, Burnaby, British Columbia. An additional specimen, a male, was taken 13 September 1982. A third was seen, but not captured, 2 September 1982. A comparison of the British Columbia material with figures and descriptions of other Noctua species given by Bretherton et al. (1979) revealed them to represent Noctua comes (Hübner), based on their smaller size, light brown, narrow primaries, and well defined discal dot on the secondaries. This preliminary identification was later confirmed by external morphological and genitalic comparison with specimens of various Noctua species obtained from the Nova Scotia Museum collection in Halifax.

Evidence of Xyleborinus attenuatus (Blandford 1894) (Coleoptera: Curculionidae: Scolytinae: Xyleborini) populations in Quebec, Canada

2014 ◽  
Vol 94 (1) ◽  
pp. 8-12
Author(s):  
Valentin Popa ◽  
Claude Guertin ◽  
Robert Werbiski
Keyword(s):  
British Columbia ◽  
Nova Scotia ◽  
North America ◽  
South America ◽  
Ambrosia Beetle ◽  
Western Canada ◽  
Eastern Canada ◽  
North And South America ◽  
North And South

Six species of the genus Xyleborinus (Reitter 1913) have been reported in North America. Five of these species were introduced, and one species is considered native to North and South America. Xyleborinus attenuatus (Blandford 1894), which was introduced into the Americas from Asia, was first recorded in 1995 in western Canada, in the province of British Columbia, and then in 2007 in the province of Nova Scotia, in eastern Canada. In Quebec, X. attenuatus was initially recorded in 2009 based on a single captured specimen. In this study, we present additional evidence of the presence of this alien ambrosia beetle in Quebec, Canada.

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

Early Cretaceous crust–mantle interaction linked to rollback of the Palaeo-Pacific flat-subducting slab: constraints from the intermediate–felsic volcanic rocks of the northern Great Xing’an Range, NE China

2021 ◽  
pp. 1-22
Author(s):  
Jia-Hao Jing ◽  
Hao Yang ◽  
Wen-Chun Ge ◽  
Yu Dong ◽  
Zheng Ji ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Volcanic Rocks ◽  
Geochemical Data ◽  
Calc Alkaline ◽  
Ne China ◽  
Asthenospheric Mantle ◽  
High K ◽  
Wide Range ◽  
Great Xing’An Range ◽  
Subducting Slab

Abstract Late Mesozoic igneous rocks are important for deciphering the Mesozoic tectonic setting of NE China. In this paper, we present whole-rock geochemical data, zircon U–Pb ages and Lu–Hf isotope data for Early Cretaceous volcanic rocks from the Tulihe area of the northern Great Xing’an Range (GXR), with the aim of evaluating the petrogenesis and genetic relationships of these rocks, inferring crust–mantle interactions and better constraining extension-related geodynamic processes in the GXR. Zircon U–Pb ages indicate that the rhyolites and trachytic volcanic rocks formed during late Early Cretaceous time (c. 130–126 Ma). Geochemically, the highly fractionated I-type rhyolites exhibit high-K calc-alkaline, metaluminous to weakly peraluminous characteristics. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high-field-strength elements (HFSEs), with their magmatic zircons ϵHf(t) values ranging from +4.1 to +9.0. These features suggest that the rhyolites were derived from the partial melting of a dominantly juvenile, K-rich basaltic lower crust. The trachytic volcanic rocks are high-K calc-alkaline series and exhibit metaluminous characteristics. They have a wide range of zircon ϵHf(t) values (−17.8 to +12.9), indicating that these trachytic volcanic rocks originated from a dominantly lithospheric-mantle source with the involvement of asthenospheric mantle materials, and subsequently underwent extensive assimilation and fractional crystallization processes. Combining our results and the spatiotemporal migration of the late Early Cretaceous magmatic events, we propose that intense Early Cretaceous crust–mantle interaction took place within the northern GXR, and possibly the whole of NE China, and that it was related to the upwelling of asthenospheric mantle induced by rollback of the Palaeo-Pacific flat-subducting slab.

Trend analysis of fire season length and extreme fire weather in North America between 1979 and 2015

2017 ◽  
Vol 26 (12) ◽  
pp. 1009 ◽  
Author(s):  
Piyush Jain ◽  
Xianli Wang ◽  
Mike D. Flannigan
Keyword(s):  
North America ◽  
Statistical Significance ◽  
Kendall Test ◽  
Fire Season ◽  
Fire Weather ◽  
Season Length ◽  
Eastern Canada ◽  
Reanalysis Dataset ◽  
Fire Weather Index ◽  
Extreme Fire

We have constructed a fire weather climatology over North America from 1979 to 2015 using the North American Regional Reanalysis dataset and the Canadian Fire Weather Index (FWI) System. We tested for the presence of trends in potential fire season length, based on a meteorological definition, and extreme fire weather using the non-parametric Theil–Sen slope estimator and Mann–Kendall test. Applying field significance testing (i.e. joint significance of multiple tests) allowed the identification of the locations of significant trends, taking into account spatial correlations. Fire season length was found to be increasing over large areas of North America, especially in eastern Canada and the south-western US, which is consistent with a later fire season end and an earlier fire season start. Both positive and negative trends in potential fire spread days and the 99th percentile of FWI occurred in Canada and the contiguous United States, although the trends of largest magnitude and statistical significance were mostly positive. In contrast, the proportion of trends with significant decreases in these variables were much lower, indicating an overall increase in extreme fire weather. The smaller proportion of significant positive trends found over Canada reflects the truncation of the time series, necessary because assimilation of precipitation observations over Canada ceased in the reanalysis post-2002.

Carabidae (Coleoptera) in Nova Scotia, Canada wild blueberry fields: prospects for biological control

2012 ◽  
Vol 144 (6) ◽  
pp. 779-791 ◽  
Author(s):  
G.C. Cutler ◽  
J.M. Renkema ◽  
C.G. Majka ◽  
J.M. Sproule
Keyword(s):  
Biological Control ◽  
Nova Scotia ◽  
Species Diversity ◽  
Insect Pests ◽  
Abundant Species ◽  
Conservation Biological Control ◽  
Carabid Beetles ◽  
Eastern Canada ◽  
Wild Blueberries ◽  
Wild Blueberry

AbstractThe Carabidae (Coleoptera) are a diverse family of beetles with almost 300 species identified in Nova Scotia, Canada. Carabid beetle communities have been studied in several agricultural systems, but not wild blueberries, an important crop in eastern Canada. In the interest of potentially developing conservation biological control programs in wild blueberry, we collected Carabidae in crop (fruit-bearing) and sprout (vegetative) blueberry fields in Nova Scotia in order to assess species diversity and abundance over space and time. Over 3200 specimens were collected, representing 51 species. A large portion of collected specimens (39%) were nonnative, and the most abundant species were generally predacious and synanthropic. Species diversity tended to be higher near forest edges than further into fields, but not for all abundant species. Several of the most prominent predators showed significant differences in preference of crop versus sprout fields, distribution throughout fields, and seasonable abundance. These findings have implications for conservation biological control efforts with carabid beetles against several insect pests in wild blueberry.

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