scholarly journals Neoproterozoic U–Pb (zircon) and 40Ar/39Ar (muscovite) ages from granitic pegmatite clasts, basal Ross Island Formation, Grand Manan Island, New Brunswick, Canada

2019 ◽  
pp. 265-274
Author(s):  
Sandra M. Barr ◽  
James K. Mortensen
Keyword(s):  
New Brunswick ◽  
Granitic Pegmatite ◽  
Island Formation ◽  
Depositional Age ◽  
Penobscot Bay

Zircon grains from a granitic pegmatite clast from conglomerate at the base of the Ross Island Formation on Grand Manan Island indicate an igneous crystallization age of 664.1 ± 4.6 Ma.  The clast also contains abundant older inherited grains back to the Archean. Muscovite in the same clast and an additional similar clast yielded cooling ages of 607.0 ± 3.7 Ma and 619.6 ± 4.1 Ma, respectively, providing a maximum depositional age for the host conglomerate of the Ross Island Formation.   The similarity in age to pegmatite in the Seven Hundred Acre Island Formation in Penobscot Bay, Maine, supports earlier correlations between the two areas based on similarities in Neoproterozoic quartzite and carbonate units.

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.

Neoproterozoic and Cambrian U–Pb (zircon) ages from Grand Manan Island, New Brunswick: implications for stratigraphy and northern Appalachian terrane correlations

2007 ◽  
Vol 44 (7) ◽  
pp. 911-923 ◽  
Author(s):  
B V Miller ◽  
S M Barr ◽  
R S Black
Keyword(s):  
New Brunswick ◽  
Long Island ◽  
Fault System ◽  
Bay Of Fundy ◽  
Early Cambrian ◽  
Island Formation ◽  
Rock Types ◽  
Head Formation ◽  
Minimum Age ◽  
Late Neoproterozoic

Pre-Mesozoic rocks are exposed on the southeastern third of Grand Manan Island and adjacent offshore islands in the Bay of Fundy. U–Pb (zircon) ages reported here demonstrate that most of these rocks are late Neoproterozoic to Early Cambrian. The oldest dated unit is the Ingalls Head Formation, from which two felsic tuff samples yielded ages of 617.6 ± 3.2 and 618.3 ± 2.8 Ma. The Three Islands granite, exposed only on offshore islands, is younger than the Ingalls Head Formation at 611.1 ± 2.4 Ma. It provides a minimum age for marble of the Kent Island Formation, which occurs as large xenoliths in the granite. The High Duck Island granite yielded an age of 547.3 ± 1.1 Ma, providing a minimum late Neoproterozoic age for the host Long Island Bay Formation. An age of 539.0 ± 3.3 Ma from a dacitic lithic-crystal tuff demonstrates that the Priest Cove Formation is earliest Cambrian; this supersedes a Silurian age previously suggested on the basis of poorly documented fossil evidence. The Long Pond Bay Formation is considered to be the youngest pre-Mesozoic unit on Grand Manan Island, based on petrological features, but a felsic intrusive sample from the unit yielded ca. 588 Ma xenocrystic zircon grains that provide only a maximum age for the unit. Although lack of exposed contacts or U–Pb ages from a few units precludes a complete stratigraphic picture, the ages reported here deomonstrate that most pre-Mesozoic units on Grand Manan Island are not Paleozoic as previously assumed. Some units on Grand Manan Island show similarities in rock types and ages to components in the Islesboro block in Penobscot Bay in coastal Maine. Overall, the range of ages and rock types suggests that they correlate with the New River and Mascarene terranes of southern New Brunswick, requiring an offset of at least 40 km between southern New Brunswick and adjacent Maine along the Grand Manan – Oak Bay fault system. Hence, both the Ganderia–Avalonia and Avalonia–Meguma boundaries lie farther offshore than Grand Manan Island.

scholarly journals Detrital zircon signatures in Precambrian and Paleozoic sedimentary units in southern New Brunswick – more pieces of the puzzle

2019 ◽  
Vol 55 ◽  
pp. 275-322 ◽  
Author(s):  
Sandra M. Barr ◽  
Deanne Van Rooyen ◽  
Brent V. Miller ◽  
Chris E. White ◽  
Susan C. Johnson
Keyword(s):  
New Brunswick ◽  
Detrital Zircon ◽  
Strong Influence ◽  
West African Craton ◽  
Multiple Datasets ◽  
Amazonian Craton ◽  
Appalachian Orogen ◽  
Depositional Age ◽  
Late Neoproterozoic ◽  
Detrital Zircon Ages

Southern New Brunswick consists of a complex collage of fault-bounded belts of Late Neoproterozoic igneous and metamorphic rocks, Early Paleozoic sedimentary, metamorphic and igneous units, and overlying Carboniferous sedimentary rocks. The area also contains the boundary between the Avalonian and Ganderian terranes as interpreted in the northern Appalachian orogen. New detrital zircon ages reported here provide improved understanding of depositional ages and provenance of diverse Neoproterozoic to Carboniferous rocks in this complex area. Detrital zircon data from samples with Neoproterozoic maximum depositional ages indicate a dominantly Gondwanan provenance with a strong influence from the Amazonian craton. However, quartzite from The Thoroughfare Formation on Grand Manan Island contains dominanly 2 Ga zircon grains, consistent with derivation from the West African Craton. The age spectrum is similar to that from the Hutchins Island Quartzite in the Isleboro block in Penobscot Bay, Maine, strengthening the previously proposed correlation between the two areas. Cambrian samples also show prominent peri-Gondwanan provenance with strong influence from Ediacaran to Early Cambrian arc magmatism. The maximum depositional ages of these samples are consistent with previous interpretations of Cambrian ages based on fossil correlations and field data. A Carboniferous sample from Avalonia shows a significant contribution from Devonian magmatism as the youngest detrital component, although its depositional age based on field relationships is Carboniferous. The results exemplify the need to integrate multiple datasets in making interpretations from detrital zircon data.

scholarly journals U–Pb zircon geochronology of Proterozoic and Paleozoic rocks, North Islesboro, coastal Maine (USA): links to West Africa and Penobscottian orogenesis in southeastern Ganderia?

2018 ◽  
pp. 189-221 ◽  
Author(s):  
Douglas N. Reusch ◽  
Christopher S. Holm-Denoma ◽  
John F. Slack
Keyword(s):  
New Brunswick ◽  
West African ◽  
Detrital Zircons ◽  
Passive Margin ◽  
Central Position ◽  
Magmatic Zircon ◽  
New Name ◽  
The North ◽  
Small Peak ◽  
Penobscot Bay

Within the Ganderian inlier of Penobscot Bay, coastal Maine, the Islesboro fault block occupies a central position between the St. Croix terrane of continental affinity and, to the east, the Ellsworth terrane of oceanic affinity. New field, petrographic, geochemical, and U–Pb LA-ICP-MS geochronological data on detrital and magmatic zircon grains constrain the provenance and transfer history of these terranes from Gondwana to the Appalachian margin of Laurentia. On North Islesboro, the Coombs Limestone and Hutchins Island Quartzite (new name), intruded by E-MORB amphibolite, constitute a newly recognized local inlier of Proterozoic basement. Together with the nearby Seven Hundred Acre Island Formation, these mature, carbonate-rich strata record deposition on a low-latitude passive margin. Abundant detrital zircon grains in the Hutchins Island Quartzite, all older than ca. 1.8 Ga, have a predominant population at ca. 2.0 Ga and a small peak between ca. 2.8 Ga and 2.4 Ga, an age spectrum strikingly similar to those of both the Paleoproterozoic Taghdout Quartzite in Morocco, on the West African craton, and basement rocks from Georges Bank, offshore Massachusetts. The overlying Neoproterozoic–Cambrian Islesboro Formation records a second period of extension (interstratified EMORB greenstone) synchronous with accumulation of interbedded siliciclastic and carbonate sediment, prior to recumbent folding. At the base of the moderately deformed Turtle Head Cove (new name) cover sequence, immature greywacke has a youngest zircon population of ca. 515 Ma, large late Neoproterozoic populations (ca. 624 Ma and 678 Ma), a small peak at 1.2 Ga, a moderate number of ca. 1.5 Ga to 2.0 Ga grains, and a few Late Archean grains. Compared with many similar Ganderian age spectra reported from Vermont to New Brunswick, which are all consistent with a source in either the Amazonian or West African cratons, this new age spectrum most closely resembles those from quartzites in the Grand Manaan and Brookville terranes of coastal New Brunswick. Significantly, exotic blocks lithologically indistinguishable from Proterozoic strata on Islesboro occur in the St. Croix terrane within a Lower Ordovician black shale mélange at the base of the Penobscot Formation, suggesting that the St. Croix terrane, Islesboro block, and Ellsworth terrane were initially juxtaposed by Penobscottian thrusting prior to the Middle Ordovician. Subsequently, the Islesboro block was isolated between the bounding post-Silurian, pre-Late Devonian Turtle Head and Penobscot Bay dextral strike-slip faults. Along the North Islesboro fault, a fault-bounded lens of foliated pyritic felsic volcanic and volcaniclastic rock, dated at ca. 372 Ma and containing Devonian to Archean detrital zircons, records late Paleozoic deformation recognized previously in coastal New Brunswick but not in Penobscot Bay.

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

Book Reviews

2014 ◽  
Vol 2 (1) ◽  
pp. 80-95
Author(s):  
Ulrike Flader ◽  
Vera Ecarius-Kelly ◽  
Clemence SCALBERT-YÜCEL ◽  
Michael M. Gunter ◽  
Tozun Bahcheli ◽  
...  
Keyword(s):  
New Brunswick ◽  
Economic Impacts ◽  
Publishing House ◽  
Rutgers University ◽  
Ashgate Publishing ◽  
Kurdish Question ◽  
Newcastle Upon Tyne

Cengiz Gunes and Welat Zeydanlıoğlu (eds.), The Kurdish Question in Turkey: New Perspectives on Violence, Representation and Reconciliation, London: Routledge, 2014, 288 pp., (ISBN: 978-0-415-83015-7).Almas Heshmati and Nabaz T. Khayyat, Socio-Economic Impacts of Landmines in Southern Kurdistan, Newcastle upon Tyne: Cambridge Scholars Publishing, 2013, 341 pp., (ISBN: 978-1-4438-4198-6).Estelle Amy de la Bretèque, Paroles Mélodisées: Récits épiques et lamentations chez les Yézidis d’Arménie (Melodised speech. Heroic songs and laments among the Yezidis of Armenia), Paris: Classiques Garnier, 2013, 230pp., (ISBN: 978-2-8124-0787-1).Diane E. King, Kurdistan on the Global Stage: Kinship, Land, and Community in Iraq, New Brunswick and London: Rutgers University Press, 2014. 286 pp., (ISBN: 9780813563534).Michael M. Gunter and Mohammed M.A. Ahmed (eds.), The Kurdish Spring: Geopolitical Changes and the Kurds, Costa Mesa: Mazda Publishers, 2013, 344 pp., (ISBN: 978-1568592725).Derya Bayır, Minorities and Nationalism in Turkish Law, Surrey: Ashgate Publishing House, 2013, 314 pp., (ISBN: 9781409420071).

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