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  • 1
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    The northern Appalachian terrane wreck model
    Canadian Science Publishing ; 2021
    In:  Canadian Journal of Earth Sciences Vol. 58, No. 6 ( 2021-06), p. 542-553
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 58, No. 6 ( 2021-06), p. 542-553
    Abstract: Ordovician and Siluro-Lower Devonian magmatic rocks in the northern Appalachians south of the Iapetus suture are currently interpreted as distinct belts composed of multiple, small, peri-Gondwanan terranes that amalgamated during the sequential closures of Iapetus (latest Ordovician), the Tetagouche backarc basin (early Silurian), the Acadian seaway (Siluro-Devonian), and the Rheic Ocean (Devono-Carbonferous) (multiple terrane model). Here, the Siluro-Lower Devonian magmatic belts are shown to have slab failure affinities and together with the Ordovician arcs form paired belts parallel to the Iapetus suture, which suggests that they were emplaced along the common, peri-Avalonian margin during pre- and post-collisional processes. The Iapetan suture and the paired belts are inferred to repeat in Atlantic Canada due to dextral, strike-slip processes of mid-Late Devonian or younger age (terrane wreck model). In Newfoundland, the repetition is inferred to be the result of oblique, dextral offset of ca. 250 km. In the Quebec Embayment, the Iapetan paired magmatic belts are repeated twice in the limbs of a Z-shaped orocline related to oblique, dextral offsets of ca. 1200 km of the southern limb. Limited Siluro-Devonian paleomagnetic data indicate no paleolatitudinal differences across the Iapetus suture, however ca. 100° post-mid Silurian clockwise rotation is indicated for the middle fold limb; these data favour the terrane wreck model. The terrane wreck model results in a simple tectonic scenario of southerly subduction of Iapetus beneath a single ribbon continent (Avalonia sensu lato) that was subsequently deformed.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/cjes-2020-0114
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2021
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  • 2
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    Development of late Paleozoic volcanic arcs in the Canadian Cordillera: an example from the Klinkit Group, northern British Columbia and southern Yukon
    Canadian Science Publishing ; 2003
    In:  Canadian Journal of Earth Sciences Vol. 40, No. 7 ( 2003-07-01), p. 907-924
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 40, No. 7 ( 2003-07-01), p. 907-924
    Abstract: The late Paleozoic volcanic rocks of the northern Canadian Cordillera lying between Ancestral North America to the east and the accreted terranes of the Omineca belt to the west record early arc and rift magmatism along the paleo-Pacific margin of the North American craton. The Mississippian to Permian volcano-sedimentary Klinkit Group extends discontinuously over 250 km in northern British Columbia and southern Yukon. The two stratotype areas are as follows: (1) in the Englishman Range, southern Yukon, the English Creek Limestone is conformably overlain by the volcano-sedimentary Mount McCleary Formation (Lower Clastic Member, Alkali-Basalt Member and Volcaniclastic Member), and (2) in the Stikine Ranges, northern British Columbia, the Screw Creek Limestone is conformably overlain by the volcano-sedimentary Butsih Formation (Volcaniclastic Member and Upper Clastic Member). The calc-alkali nature of the basaltic volcaniclastic members of the Klinkit Group indicates a volcanic-arc setting ((La/Yb) N = 2.774.73), with little involvement of the crust in their genesis (ε Nd = +6.7 to +7.4). Alkali basalts in the Mount McCleary Formation ((La/Yb) N = 12.517.8) suggest periodic intra-arc rifting events. Broadly coeval and compositionally similar volcano-sedimentary assemblages occur in the basement of the Mesozoic Quesnel arc, north-central British Columbia, and in the pericratonic YukonTanana composite terrane, central Yukon, suggesting that they all represent pieces of a single long-lived, late Paleozoic arc system that was dismembered prior to its accretion onto Ancestral North America. Therefore, YukonTanana terrane is possibly the equivalent to the basement of Quesnel terrane, and the northern Quesnel terrane has a pericratonic affinity.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/e03-025
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2003
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  • 3
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    The Eocene–Oligocene magmatic hiatus in the south-central Canadian Cordillera: a capture of the Kula Plate by the Pacific Plate?
    Canadian Science Publishing ; 2008
    In:  Canadian Journal of Earth Sciences Vol. 45, No. 1 ( 2008-01-01), p. 69-82
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 45, No. 1 ( 2008-01-01), p. 69-82
    Abstract: The Tertiary (Paleogene and Neogene) geological record in south-central Canadian Cordillera is dominated by the 350–400 km wide, lower Eocene volcanic arc and the overlying Miocene–Recent back-arc lavas that are separated by a hiatus in magmatic activity between 48 and 24 Ma. In the Black Dome area (~240 km north of Vancouver), the Eocene volcanic rocks are mainly continental margin calc-alkaline andesite and dacite, resulting from the melting of a juvenile mafic source at the base of the crust. In contrast, the Miocene volcanic rocks resemble continental flood basalts. Both Eocene and Miocene rocks from the Black Dome volcanic complex have high positive ε Nd values (+7.2 to +7.4 and +6.4 to +7.6, respectively) and low initial Sr isotopic ratios (0.702 516 – 0.703 528 and 0.703 376 – 0.703 392, respectively) comparable to modern oceanic basalts. The onset of the hiatus in magmatism at 48 Ma coincides with capture of the Kula Plate by the Pacific Plate resulting in a change in convergence direction with the North American Plate from orthogonal to margin-parallel. The margin-parallel motion is inferred to have removed a 50–100 km sliver of the Eocene forearc that formed the boundary between the Pacific and subducted Kula Plate. Reinitiation of arc magmatism at 24 Ma is related to subduction of the Farallon and associated plates and it superimposed back-arc tholeiitic magmatism on top of the Eocene arc.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/e07-062
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2008
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  • 4
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    Bokan Mountain peralkaline granitic complex, Alexander terrane (southeastern Alaska): evidence for Early Jurassic rifting prior to accretion with North America
    Canadian Science Publishing ; 2013
    In:  Canadian Journal of Earth Sciences Vol. 50, No. 6 ( 2013-06), p. 678-691
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 50, No. 6 ( 2013-06), p. 678-691
    Abstract: The circular Bokan Mountain complex (BMC) on southern Prince of Wales Island, southernmost Alaska, is a Jurassic peralkaline granitic intrusion about 3 km in diameter that crosscuts igneous and metasedimentary rocks of the Alexander terrane. The BMC hosts significant rare metal (rare earth elements, Y, U, Th, Zr, and Nb) mineralization related to the last stage of BMC emplacement. U–Pb (zircon) and 40 Ar/ 39 Ar (amphibole and whole-rock) geochronology indicates the following sequence of intrusive activity: (i) a Paleozoic basement composed mainly of 469 ± 4 Ma granitic rocks; (ii) intrusion of the BMC at 177 ± 1 Ma followed by rapid cooling through ca. 550 °C at 176 ± 1 Ma that was synchronous with mineralization associated with vertical, WNW-trending pegmatites, felsic dikes, and aegirine–fluorite veins and late-stage, sinistral shear deformation; and (iii) intrusion of crosscutting lamprophyre dikes at 〉 150 Ma and again at ca. 105 Ma. The peralkaline nature of the BMC and the WNW trend of associated dikes suggest intrusion during NE–SW rifting that was followed by NE–SW shortening during the waning stages of BMC emplacement. The 177 Ma BMC was synchronous with other magmatic centres in the Alexander terrane, such as (1) the Dora Bay peralkaline stock and (2) the bimodal Moffatt volcanic suite located ∼30 km north and ∼100 km SE of the BMC, respectively. This regional magmatism is interpreted to represent a regional extensional event that precedes deposition of the Late Jurassic – Cretaceous Gravina sequence that oversteps the Wrangellia and Alexander exotic accreted terranes and the Taku and Yukon–Tanana pericratonic terranes of the Canadian–Alaskan Cordillera.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/cjes-2012-0139
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2013
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  • 5
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    Rifting of a Mississippian continental arc system: Little Salmon formation, Yukon–Tanana terrane, northern Canadian Cordillera
    Canadian Science Publishing ; 2007
    In:  Canadian Journal of Earth Sciences Vol. 44, No. 9 ( 2007-09-01), p. 1267-1289
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 44, No. 9 ( 2007-09-01), p. 1267-1289
    Abstract: The Yukon–Tanana terrane in the northern Canadian Cordillera records the development of a series of mid- to late Paleozoic arc systems, punctuated by intra-arc deformation, uplift, and episodic rifting coeval with back-arc extension, built upon a metasedimentary basement of northwestern Laurentian affinity. In central Yukon, the Little Kalzas formation records the development of one of these Mississippian continental arcs, whereas the Little Salmon formation records the development of an intra-arc rift basin within a continental arc. The Little Salmon formation lower succession comprises mainly volcaniclastic rocks derived from erosion of Early Mississippian and older units, including rocks of the Little Kalzas continental arc. Above a medial limestone member, the upper succession of the Little Salmon formation includes alkali basalt, breccia, and crystal and ash tuffs in the north and predominantly epiclastic rocks interbedded with crystal and ash tuffs in the south. The alkali basalts have the geochemical characteristics of ocean-island basalts and their positive ε Nd 340 (+7.3) and low 87 Sr/ 86 Sr values (0.705) suggest a primitive magma source with little or no involvement of continental crust. The transition between the northern and southern facies of the upper succession of the Little Salmon formation coincides with a northeast-trending synvolcanic fault inferred to have controlled alkali basalt eruptions and deposition of Mn-bearing exhalite in the north and basin plain sedimentation in the south. The environment of deposition of the Little Salmon formation resembles that of the modern Sumisu rift in the Izu–Bonin–Mariana arc system or the early stages of development of the Japan island-arc system.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/e07-022
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2007
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  • 6
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    Nd and Pb isotopes from the Lake of the Woods greenstone belt, northwestern Ontario: implications for mantle evolution and the formation of crust in the southern Superior Province
    Canadian Science Publishing ; 2000
    In:  Canadian Journal of Earth Sciences Vol. 37, No. 12 ( 2000-12-01), p. 1677-1689
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 37, No. 12 ( 2000-12-01), p. 1677-1689
    Abstract: Nd and Pb isotopes from the Lake of the Woods greenstone belt indicate the presence of three distinct reservoir sources: old enriched crust ( 〉 3.0 Ga); pre-2.7 Ga, homogeneous depleted mantle; and post-2.70 Ga heterogeneous mantle. Epsilon Nd values of +1.1 to +2.3 for ultramafic to felsic metavolcanic rocks (2.742.72 Ga) indicate derivation from depleted mantle. The ε Nd value of 0.9 for younger turbidite (2.71 Ga), in conjunction with detrital zircon ages ranging from 2.72 to 3.0 Ga, indicates detritus from local greenstone belt sources (depleted mantle) mixed with an older crustal source. Post-2.70 Ga heterogeneity is demonstrated by ε Nd values ranging from 0.4 to +0.4 in shoshonitic to calc-alkaline metavolcanic rocks and +2.1 in a coeval ultrapotassic pluton. Pb isotopes from the pluton indicate derivation from a depleted mantle reservoir with an initial 207 Pb/ 204 Pb of 14.52, an initial 206 Pb/ 204 Pb of 13.29, and µ 1 of 7.86. Isotopic comparison with post-2.70 Ga potassic suites from across the Superior Province indicates widespread mixing between depleted mantle and enriched end members. The enriched end member has isotopic characteristics of rocks derived from old crustal terrains, such as the Winnipeg River and Opatica subprovinces. This type of isotopic heterogeneity could be the result of crustal contamination or derivation from metasomatized mantle. Contamination of the mantle wedge by influx of fluids derived from partial melting of isotopically evolved, subducted sediments is favoured for the Superior Province potassic suite, because elevated concentration of Sr, Nd, and Pb in conjunction with primitive Mg#s suggest only limited crustal contamination has occurred.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/e00-067
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2000
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  • 7
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    Geochemistry and Petrology of the Loon Lake Pluton, Ontario
    Canadian Science Publishing ; 1975
    In:  Canadian Journal of Earth Sciences Vol. 12, No. 8 ( 1975-08-01), p. 1331-1345
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 12, No. 8 ( 1975-08-01), p. 1331-1345
    Abstract: The Precambrian Loon Lake pluton, Ontario, consists of two main zones—a core of monzonite with a rim of younger quartz monzonite. Several isolated bodies of older diorite and syenodiorite occur within the pluton. The variations in the chemical and mineralogical composition of diorites and syenodiorites are due to both magmatic differentiation and hybridization. The trends of the variations of major elements, Rb, Tl, Sr, Ba, and rare earth elements in monzonite are consistent with fractional crystallization mainly of feldspars; this fractionation probably involved flowage differentiation. Fractional crystallization and contamination of monzonitic magma by anatectic granitic melt probably played a dominant role in the genesis of quartz monzonite. Monzonite and quartz monzonite are believed to have formed from a magma of lower crustal or upper mantle origin. While part of this magma intruded as monzonite, another part which evolved further generated quartz monzonite.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/e75-123
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 1975
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  • 8
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    Geochemical constraints on magmatic and metallogenic processes: Iskut River Formation, volcanogenic massive sulfide-hosting basalts, NW British Columbia, Canada
    Canadian Science Publishing ; 2015
    In:  Canadian Journal of Earth Sciences Vol. 52, No. 1 ( 2015-01), p. 1-20
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 52, No. 1 ( 2015-01), p. 1-20
    Abstract: Volcanic rocks of the Jurassic Iskut River Formation (IRF) in northwestern British Columbia (Canada) host several volcanogenic massive sulfide (VMS) deposits, including the exceptionally high-grade Eskay Creek Ag–Au–Cu–Pb–Zn deposit. The IRF comprises voluminous pillow basalt ( 〉 90%), minor rhyolite, and sedimentary rock of late Early to early Middle Jurassic age, filling a series of sub-basins along a 300 by 50 km north-trending belt. Two geochemically distinct types of tholeiitic basalts interfinger; both resemble back-arc basin basalts formed from the melting of asthenospheric and sub-arc mantle sources. Group 2 basalts are more enriched in light rare-earth elements, Ba, K, Sr, Th, and U, and have lower positive ε Nd values than group 1 basalts (+3.2 to +6.3 versus +6.9 to +8.4, respectively). The compositional differences between group 1 and group 2 basalts are interpreted to result from crustal contamination in group 2. Group 1 basalts are most common in the southern part of the IRF belt where they are closely associated with the Eskay Creek, Bonanza, and Hidden Creek (Anyox) VMS deposits. Group 2 basalts are most abundant in the northern half of the belt and are not associated with exploited mineral deposits. The lack of crustal contamination in group 1 basalts indicates that they formed from rapidly ascending magma in an advanced rift setting and were associated with high heat flow that drove hydrothermal circulation. Group 1 and group 2 basalts are reliably discriminated by Ta/Th 〈 2.5 in the former and 〉 2.5 in the latter. This geochemical criteria can therefore be used as an exploration tool to identify VMS permissive sub-basins and (or) stratigraphy in the IRF.
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/cjes-2014-0034
    Language: English
    Publisher: Canadian Science Publishing
    Publication Date: 2015
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  • 9
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    Tectonostratigraphic and petrogenetic setting of late Mississippian volcanism in eastern Canada
    Canadian Science Publishing ; 2018
    In:  Canadian Journal of Earth Sciences Vol. 55, No. 4 ( 2018-04), p. 356-372
    Details
    In: Canadian Journal of Earth Sciences, Canadian Science Publishing, Vol. 55, No. 4 ( 2018-04), p. 356-372
    Type of Medium: Online Resource
    ISSN: 0008-4077 , 1480-3313
    URL: Article
    DOI: 10.1139/cjes-2017-0176
    Language: French
    Publisher: Canadian Science Publishing
    Publication Date: 2018
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