Early Devonian paleomagnetic data from the Lower Devonian Karheen Formation suggest Laurentia-Baltica connection for the Alexander terrane

Bazard, David R.; Butler, Robert F.; Gehrels, George E.; Soja, Constance M.

doi:10.1130/0091-7613(1995)023<0707:edpdft>2.3.co;2

Cited by 42 publications

(22 citation statements)

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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: 84%

Northern Cordilleran terranes and their interactions through time

Colpron¹,

Nelson²,

Murphy³

2007

Gsa Today

255

210

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Section: Selwynmentioning

confidence: 84%

Northern Cordilleran terranes and their interactions through time

Colpron¹,

Nelson²,

Murphy³

2007

Gsa Today

255

210

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“…The displacement history of the Alexander terrane has been a matter of debate in the scientifi c literature for several decades (Churkin and Eberlein, 1977;Gehrels and Saleeby, 1987;Soja, 1994;Bazard et al, 1995;Gehrels et al, 1996;Pedder, 2006;Soja and Krutikov, 2008;Colpron and Nelson, 2009;Beranek et al, 2012Beranek et al, , 2013aBeranek et al, , 2013b. A combination of magmatic, stratigraphic, fossil, and paleomagnetic data sets currently support the Alexander terrane to have evolved in the Northern Hemisphere and proximal to the Ediacaran to Cambrian Timanian orogen of northeastern Baltica and the Arctic segment of the Silurian to Devonian Appalachian-Caledonian orogen of the supercontinent Laurussia.…”

Section: Late Paleozoic Paleogeographymentioning

confidence: 95%

“…Early Paleozoic rock units of the Craig subterrane together formed part of an arc-backarc system in proximity to the Scandinavian and Russian High Arctic regions of the paleocontinent Baltica Nelson, 2009, 2011;Beranek et al, 2012Beranek et al, , 2013a. Silurian to Devonian strata of the Karheen Formation and Icefi eld assemblage comprise now-displaced equivalents of the Old Red Sandstone that covered much of the North Atlantic region after the Scandian-Salinic phase of Appalachian-Caledonian mountain building and assembly of the supercontinent Laurussia (Bazard et al, 1995;Soja and Krutikov, 2008;Beranek et al, 2013b).…”

Section: Alexander Terranementioning

confidence: 99%

“…This orogen has been assembled primarily through the collision of lithospheric fragments, known as terranes, which now form a collage of faultbounded blocks adjacent to the western edge of the Laurentian craton (Coney et al, 1980;Saleeby, 1983;Colpron et al, 2007). The Alexander and Wrangellia terranes comprise two of the largest terranes in the North American Cordillera and have long been of interest based on their potential for reconstructing Phanerozoic plate motions and global paleogeography (Berg et al, 1972;Monger et al, 1972;Churkin and Eberlein, 1977;Schweickert and Snyder, 1981;Gehrels and Saleeby, 1987;Soja, 1994;Bazard et al, 1995;Colpron and Nelson, 2009;Beranek et al, 2012Beranek et al, , 2013aBeranek et al, , 2013b. Subjects of ongoing debate in the North American Cordillera are the precise age and tectonic signifi cance of late Paleozoic igneous rocks that occur near the major faults that separate the Alexander terrane and Wrangellia in Alaska, Yukon,and British Columbia (Figs.…”

Section: Introductionmentioning

confidence: 98%

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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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“…The eastern Klamath, northern Sierran, and Alexander terranes are commonly interpreted as exotic to Laurentia (e.g., Bazard et al, 1995;Beranek et al, 2016Beranek et al, , 2013Colpron & Nelson, 2009;Gehrels et al, 1996;Grove et al, 2008) (Figure 1). These terranes were accreted to the western Laurentian margin during Late Devonian-Early Mississippian time (eastern Klamath and northern Sierra) and mid-Jurassic time (Alexander terrane) (Colpron & Nelson, 2009).…”

Section: Initiation Of Active Plate Margin In Western Laurentiamentioning

confidence: 99%

Three‐Dimensional Evolution of the Early Paleozoic Western Laurentian Margin: New Insights From Detrital Zircon U‐Pb Geochronology and Hf Isotope Geochemistry of the Harmony Formation of Nevada

et al. 2017

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Uranium‐lead (U‐Pb) geochronology and Hafnium (Hf) isotope geochemistry of detrital zircons of the Harmony Formation of north central Nevada provide new insights into the tectonic evolution of the Late Paleozoic western Laurentian margin. Using laser‐ablation inductively coupled plasma mass spectrometry, 10 arenite samples were analyzed for U‐Pb ages, and 8 of these samples were further analyzed for Hf isotope ratios. Three of the sampled units have similar U‐Pb age peaks and Hf isotope ratios, including a 1.0–1.4 Ga peak with εHf values of +12 to −3 and a 2.5–2.7 Ga peak with εHf values of +7 to −5. The remaining seven samples differ significantly from these three, but are similar to one another; having age peaks of 1.7–1.9 Ga with εHf of +10 to −20 and age peaks of 2.3–2.7 Ga with εHf of +6 to −8. The data confirm the subdivision of the Harmony Formation into two petrofacies: quartzose (Harmony A) and feldspathic (Harmony B). The three samples with 1.0–1.4 and 2.5–2.7 Ga peaks are the Harmony A, which originated in the central Laurentian craton. The other seven samples are the Harmony B, which originated in eastern Alberta‐western Saskatchewan, north of the Harmony A source. We propose that all Harmony Formation strata were deposited near eastern Alberta and subsequently tectonically interleaved with Roberts Mountains allochthon strata. We interpret that the entire package was tectonically transported south along the western Laurentian margin and then emplaced eastward onto the craton during the Late Devonian‐Early Mississippian Antler orogeny.

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Early Devonian paleomagnetic data from the Lower Devonian Karheen Formation suggest Laurentia-Baltica connection for the Alexander terrane

Cited by 42 publications

References 0 publications

Northern Cordilleran terranes and their interactions through time

Northern Cordilleran terranes and their interactions through time

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

Three‐Dimensional Evolution of the Early Paleozoic Western Laurentian Margin: New Insights From Detrital Zircon U‐Pb Geochronology and Hf Isotope Geochemistry of the Harmony Formation of Nevada

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