New ties between the Alexander terrane and Wrangellia and implications for North America Cordilleran evolution

Israel, Steve; Beranek, Luke P.; Friedman, Richard M.; Crowley, James L.

doi:10.1130/l364.1

Cited by 40 publications

(78 citation statements)

References 26 publications

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“…2) indicate that the Craig subterrane evolved in a passive-margin environment from Late Devonian to early Pennsylvanian time (Gehrels et al, 1996;Nelson et al, 2013;Israel et al, 2014). The change from an upperplate setting to a passive-margin setting following the Scandian orogeny is an important constraint concerning tectonic relationships between the Alexander terrane and Wrangellia during this period (see Wrangellia discussion in next section).…”

Section: Alexander Terranementioning

confidence: 94%

“…For example, Israel et al (2014) on October 30, 2014 gsabulletin.gsapubs.org Downloaded from of northern Wrangellia have a shared origin with Late Devonian (363.53 ± 0.12 Ma) gabbros of the adjacent Craig subterrane in southwestern Yukon (Fig. 2).…”

Section: Wrangellia (Wr Inmentioning

confidence: 94%

“…The top of the Skolai arc assemblage is generally mapped as the gradual transition from the volcanic-dominated stratigraphy of the Station Creek Formation to the sediment-dominated stratigraphy of the Hasen Creek Formation. More complex contact relationships are locally observed along the Duke River fault in Yukon, where Lower Permian conglomerates of the Hasen Creek Formation unconformably overlie the Late Devonian basement gabbros of northern Wrangellia (Sharp, 1943;Israel et al, 2014).…”

Section: Wrangellia (Wr Inmentioning

confidence: 96%

“…2). Israel et al (2014) argued for the non-arc-like compositions of the Late Devonian gabbros to represent the initiation of rifting within an arc located at the margin of the Craig subterrane, thus identifying the oldest known geological tie between Wrangellia and the Alexander terrane. The Late Devonian continental arc extended south (present coordinates) into an oceanic realm, beyond the limits of the Craig subterrane, and generated the Sicker arc system of southern Wrangellia (Nelson et al, 2013;Israel et al, 2014).…”

Section: Wrangellia (Wr Inmentioning

confidence: 98%

“…2;Smith and MacKevett, 1970;MacKevett, 1971;Read and Monger, 1976). The exposed base of the Station Creek Formation in Yukon consists of early Mississippian crystal-rich tuffs dated at 352.84 ± 0.30 Ma (zircon CA-TIMS), chert, and mafi c lavas with N-MORB to backarc basin basalt geochemical signatures (Israel et al, 2014). The Station Creek Formation at higher stratigraphic levels contains abundant mafi c to intermediate lavas with arc-type geochemical signatures (e.g., Greene et al, 2009) that are referred to as the Skolai arc.…”

Section: Wrangellia (Wr Inmentioning

confidence: 99%

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Late Paleozoic assembly of the Alexander-Wrangellia-Peninsular composite terrane, Canadian and Alaskan Cordillera

Beranek

Staal

McClelland

et al. 2014

Geological Society of America Bulletin

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Late Paleozoic assembly of the AlexanderWrangellia-Peninsular composite terrane is recorded by two phases of regional deformation, metamorphism, and magmatism within basement complexes of the Alexander (Craig and Admiralty subterranes), Wrangellia, and Peninsular terranes in the Canadian and Alaskan Cordillera. New secondary ion mass spectrometry (SIMS) and chemical abrasionisotope dilution-thermal ionization mass spectrometry (CA-ID-TIMS) zircon U-Pb ages, whole-rock major-and trace-element and Nd-Sr isotope geochemical compositions, and geological fi eld observations of late Paleozoic igneous rocks were used to identify the precise timing and signifi cance of this tectonism in the Saint Elias Mountains region of southwestern Yukon and eastern Alaska. Middle to Late Pennsylvanian (301-307 Ma) igneous rocks, herein assigned to the Barnard Glacier suite, were preferentially emplaced along the Wrangellia-Craig subterrane boundary and mainly comprise syenitic plutons that intrude Paleozoic country rocks with evidence of Pennsylvanian or older (D1) deformation. We propose that Barnard Glacier suite magmatism was produced by a slab breakoff event after the consumption of a narrow backarc ocean basin and early Pennsylvanian collision between the WrangelliaPeninsular arc and Craig subterrane passive margin. Early Permian (284-291 Ma) dioritic to granodioritic rocks, herein assigned to the Donjek Glacier suite, comprise the vestiges of an extensive magmatic system within the Craig subterrane of southwestern Yukon and southeastern Alaska. The available data suggest that the Donjek Glacier suite represents part of a short-lived, Early Permian arc that initiated along the outboard margin of the Craig subterrane-Wrangellia-Peninsular block after Pennsylvanian collision and slab breakoff. At two fi eld localities in southwestern Yukon, Paleozoic country rocks with D1 fabrics are also intruded by sills and dikes of the Donjek Glacier suite that show evidence of ca. 285 Ma regional deformation and metamorphism (D2). Field evidence for Early Permian tectonism in the Saint Elias Mountains implies direct connections with coeval deformation and metamorphism in the Admiralty subterrane, a microcontinent in the Admiralty Island region of southeastern Alaska that developed separately from the Craig subterrane prior to the Early Per mian. D2 tectonism was likely related to the entry of the Admiralty subterrane margin into the Early Permian subduction zone, which resulted in collision and fi nal amalgamation of the Alexander-Wrangellia-Peninsular composite terrane. Our tectonic scenarios require the currently accepted confi guration of the Alexander terrane (com posite of the Craig and Admiralty subterranes) to have only existed after the Early Permian collision between the Admiralty subterrane and the previously assembled Craig subterrane-Wrangellia-Peninsular terrane. Biogeographic and other geological data suggest that the two-part assembly of the AlexanderWrangellia-Peninsular composite terrane took place along a convergent margin t...

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Section: Alexander Terranementioning

confidence: 94%

Section: Wrangellia (Wr Inmentioning

confidence: 94%

Section: Wrangellia (Wr Inmentioning

confidence: 96%

Section: Wrangellia (Wr Inmentioning

confidence: 98%

Section: Wrangellia (Wr Inmentioning

confidence: 99%

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Late Paleozoic assembly of the Alexander-Wrangellia-Peninsular composite terrane, Canadian and Alaskan Cordillera

Beranek

Staal

McClelland

et al. 2014

Geological Society of America Bulletin

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Australian‐derived detrital zircons in the Permian‐Triassic Gympie terrane (eastern Australia): Evidence for an autochthonous origin

Rosenbaum

Yang

et al. 2015

Tectonics

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The Tasmanides in eastern Australia record accretionary processes along the eastern Gondwana margin during the Phanerozoic. The Gympie terrane is the easternmost segment of the Tasmanides, but whether its origin was autochthonous or allochthonous is a matter of debate. We present U-Pb ages of detrital zircons from Permian and Triassic sedimentary rocks of the Gympie terrane with the aim of tracing the source of the sediments and constraining their tectonic relationships with the Tasmanides. Our results show that the Permian stratigraphic units from the Gympie terrane mainly contain Carboniferous and Permian detrital zircons with dominant age peaks at~263 Ma,~300 Ma,~310 Ma, and~330 Ma. The provenance ages of the Triassic sedimentary units are similar (~256 Ma,~295 Ma, and~328 Ma) with an additional younger age peak of~240 Ma. This pattern of provenance ages from the Gympie terrane is correlative to episodes of magmatism in the adjacent component of the Tasmanides (New England Orogen), indicating that the detrital zircons were dominantly derived from the Australian continent. Given the widespread input of detrital zircons from the Tasmanides, we think that the sedimentary sequence of the Gympie terrane was deposited along the margin of the eastern Australian continent, possibly in association with a Permo-Triassic continental arc system. Our results do not show evidence for an exotic origin of the Gympie terrane, indicating that similarly to the vast majority of the Tasmanides, the Gympie terrane was genetically linked to the Australian continent.

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Late Jurassic flare‐up of the Coast Mountains arc system, NW Canada, and dynamic linkages across the northern Cordilleran orogen

et al. 2017

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Short‐lived, high‐volume magmatic events or flare‐ups in Cordilleran‐style accretionary systems are presumably triggered by the rapid underthrusting of melt‐fertile lithosphere beneath a continental arc during extreme retroarc shortening. New zircon U‐Pb age and trace element geochemical studies of the Coast Mountains batholith were conducted to test this hypothesis and investigate cross‐orogen linkages between the Coast Mountains arc system and adjacent retroarc elements of the Canadian Cordillera. Late Jurassic (155–147 Ma) granitoids of the Saint Elias plutonic suite in southwestern Yukon were emplaced during a widespread magmatic event and correspond to an intrusive rate of ~350 km2/Myr, analogous to the scale of 160–150 Ma flare‐up activity in the Sierra Nevada batholith. The timing of Late Jurassic high‐volume magmatism was coincident with forearc and intraarc deformation events along the length of the Coast Mountains arc from Alaska to British Columbia. Whole‐rock and zircon rare earth element geochemical results from the Saint Elias plutonic suite confirm that continental lithosphere was a key source component for Late Jurassic granitoids, which strengthens the implied relationship between high‐volume arc magmatism and crustal recycling. Well‐documented episodes of late Middle to early Late Jurassic hinterland thrusting and metamorphism in the Intermontane and Omineca belts of the Canadian Cordillera preceded this high‐volume event and therefore support the hypothesis that retroarc shortening was dynamically linked to flare‐up activity. Late Jurassic magmatism was followed by a 140–125 Ma lull in most of the Coast Mountains batholith, which may be linked to ridge subduction, lithospheric delamination, mantle cooling, or plate reorganization.

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New ties between the Alexander terrane and Wrangellia and implications for North America Cordilleran evolution

Cited by 40 publications

References 26 publications

Late Paleozoic assembly of the Alexander-Wrangellia-Peninsular composite terrane, Canadian and Alaskan Cordillera

Late Paleozoic assembly of the Alexander-Wrangellia-Peninsular composite terrane, Canadian and Alaskan Cordillera

Australian‐derived detrital zircons in the Permian‐Triassic Gympie terrane (eastern Australia): Evidence for an autochthonous origin

Late Jurassic flare‐up of the Coast Mountains arc system, NW Canada, and dynamic linkages across the northern Cordilleran orogen

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