Late Paleozoic orogeny in Alaska's Farewell terrane

Bradley, Dwight C.; Dumoulin, Julie A.; Layer, Paul W.; Sunderlin, David; Roeske, Sarah M.; McClelland, Bill; Harris, Anita G.; Abbott, G. J.; Bundtzen, T. K.; Kusky, Timothy

doi:10.1016/s0040-1951(03)00238-5

Cited by 34 publications

(58 citation statements)

References 23 publications

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“…Instead, their early faunal and isotopic affinities are consistent with Siberia and Barentia (Bazard et al, 1995;Bradley et al, 2003;Nokleberg et al, 2000). The Arctic-Alaska terrane, although continental to pericratonic and thought to show continuity with the northernmost miogeocline (Lane, 1997), is anomalous with respect to western Laurentia (Patrick and McClelland, 1995).…”

Section: Selwynmentioning

confidence: 86%

“…In fundamental contrast to the Intermontane terranes, the Insular terranes (Wrangellia and Alexander, Insular superterrane of Monger et al, 1982; and the Peninsular terrane of southwestern Alaska; Plafker et al, 1989) and the Farewell terrane of central Alaska (Bradley et al, 2003), although in part long-lived (Precambrian to Triassic) and in part of pericratonic origin, show no evidence of early relationships to the western margin of Laurentia. Instead, their early faunal and isotopic affinities are consistent with Siberia and Barentia (Bazard et al, 1995;Bradley et al, 2003;Nokleberg et al, 2000).…”

Section: Selwynmentioning

confidence: 89%

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Northern Cordilleran terranes and their interactions through time

Colpron¹,

Nelson²,

Murphy³

2007

Gsa Today

255

210

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Section: Selwynmentioning

confidence: 86%

Section: Selwynmentioning

confidence: 89%

Northern Cordilleran terranes and their interactions through time

Colpron¹,

Nelson²,

Murphy³

2007

Gsa Today

255

210

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“…The Farewell terrane shares an endemic Silurian sponge fauna with the Craig subterrane (Soja and Antoshkina, 1997) and may have been in proximity to its Early Permian convergent margin. Bradley et al (2003) defi ned the Browns Fork orogeny as an Early Permian collisional event on the basis of metamorphic Ar-Ar mica ages of 284-285 Ma and syntectonic clastic rocks that fi lled a late Paleozoic foreland basin. The identity of the lithospheric block in the upper plate of the collision is uncertain; however, Bradley et al (2003) did recognize the similarities between the timing of the Browns Fork orogeny and the ages of PennsylvanianPermian magmatic rocks in Wrangellia.…”

mentioning

confidence: 99%

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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“…The Farewell terrane (Decker et al, 1994;Bundtzen et al, 1997;Bradley et al, 2003) consists of a Proterozoic basement complex overlain by younger Proterozoic through Mesozoic strata that have been divided into several sequences or subterranes (Fig. 3).…”

Section: Geologic Settingmentioning

confidence: 99%

“…979 and 921 Ma, and ca. 852-850 Ma granitic orthogneisses (McClelland et al, 1999;Bradley et al, 2003Bradley et al, , 2014.…”

Section: Stratigraphy and Lithologiesmentioning

confidence: 99%