doi: 10.1130/B30120.1 2010;122;1899-1911Geological Society of America Bulletin
Hadlari and Willem G. ZantvoortLuke P. Beranek, James K. Mortensen, Larry S. Lane, Tammy L. Allen, Tiffani A. Fraser, Thomas northern Cordilleran miogeoclinenorthwestern Canada: Insights on Arctic tectonics and the evolution of the Detrital zircon geochronology of the western Ellesmerian clastic wedge,
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Detrital zircon provenance investigations of mid-Paleozoic sandstone from the west-ern Ellesmerian clastic wedge and Cor di-lleran miogeocline in northern Yukon and Northwest Territories, northwestern Can-ada, provide critical new data on the source of foreland basin sedimentation attributed to terrane accretion and plate convergence along the ancestral Arctic margin of North America. Late Devonian and early Missis-sippian clastic wedge strata yield “exotic” ca. 360–390, 430–460, 530–680, and 1500–1600 Ma detrital zircon populations that are consistent with source rocks that originated near the Caledonian and Timanian orogenic belts. Specifi cally, the Pearya and Arctic Alaska–Chukotka terranes, the landmass of Crockerland, and Caledonian rocks in eastern Greenland are the inferred sources for exotic detrital zircons in clastic wedge strata. Progressive recycling of Ellesmerian foreland basin sediments into the continen-tal margin environment along northwest-ern Laurentia is indicated by the presence of ca. 360–430 Ma and 1500–1600 Ma de-trital zircons in post-tectonic, middle to late Mississippian miogeoclinal strata in Yukon . Provenance data from these Missis-sippian samples record a dramatic shift in
the source of the Cordilleran miogeocline, since Caledonian and Baltican (Timanide) detrital zircon signatures are not recognized in pre–Late Devonian sedimentary rocks in western Canada. Devonian strata of the Alexander terrane and Yreka subterrane (eastern Klamath terrane) have Caledonian and Baltican detrital zircon age signatures similar to Ellesmerian clastic wedge sand-stones, implying that several Cor di lleran terranes originated in the paleo-Arctic realm. Speculative correlations suggest that the Arctic Alaska–Chukotka terrane was located to the west of Crockerland and the Canadian Arctic Islands in pre-Cretaceous time, prior to opening of the Amer asian basin . Rifting models for the western Arctic Ocean featuring counterclockwise rotation of the Arctic Alaska–Chukotka terrane away from the Canadian Arctic Islands may need reevaluation.
INTRODUCTION
Early to mid-Paleozoic plate convergence along the length of the ancestral Arctic margin of northern Laurentia produced a southward-tapering clastic wedge that covered ~7,000,000 km2 of the North American continent, includ-ing Greenland (Fig. 1; Trettin, 1991; Patchett et al., 2004). Clastic wedge strata accumulated in the foreland of the Innuitian orogen (Fig. 1), a mountain belt characterized by growth that has been attributed to the progressive collision of allochthonous terranes against northern North America (Trettin et al., 1991; Patchett et al., 1999). The fi nal pulse of Innuitian orogenic development and sedimentation in northern Laurentia was related to the enigmatic Late Devo nian to Mississippian Ellesmerian orogeny
(Thorsteinsson and Tozer, 1970; Trettin et al., 1991; Lane, 2007).
In contrast to most foreland basin succes-sions worldwide, the detrital zircon provenance signatures of Innuitian clastic wedge strata are relatively unconstrained. Provenance analysis of foreland strata is accepted as a very useful tool in understanding orogen evolution (e.g., Ross et al., 2005). Therefore, detrital zircon age analysis of clastic wedge rocks is an excellent way to place tighter constraints on Paleozoic collisional tec-tonics, plate reconstructions, and stratigraphic correlations within the paleo-Arctic realm.
Prior study on the Innuitian foreland basin suc-cession includes 71 detrital zircon ages from fi ve samples of Ellesmerian clastic wedge sandstone (McNicoll et al., 1995; Gehrels et al., 1999). Notably, conventional isotope dilution–thermal ionization mass spectrometry (ID-TIMS) analy-ses of detrital zircons from the Late Devonian Nation River Formation of eastern Alaska (NR in Fig. 2) yielded six ages from 424 to 434 Ma (Gehrels et al., 1999). Sensitive high-resolution ion microprobe (SHRIMP) analyses on detrital zircon from the Middle Devonian Bird Fiord Formation (BF in Fig. 2) in the Canadian Arc-tic Islands also yielded a single 426 Ma grain (McNicoll et al., 1995). Silurian detrital zircons in Ellesmerian clastic wedge strata are most con-sistent with a source from the Caledonian oro-genic belt of eastern Greenland (Fig. 1) or the Pearya terrane in the Canadian Arctic Islands (Fig. 1) because ca. 430 Ma igneous rocks are not recognized on the northern Laurentian autoch thon (e.g., Gehrels et al., 1999).
Silurian to Cryogenian (ca. 430–680 Ma) detrital zircon ages are widely observed within laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) data sets from Trias-sic Cordilleran margin strata in Yukon (Beranek
1900 Geological Society of America Bulletin, November/December 2010
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PROXIMAL FORELAND DEPOSITS2–10 km original thickness
DISTAL FORELAND-CRATON DEPOSITS0–2 km original thickness
Foreland limit of orogen
Direction of Devonian sediment transport
Hypothetical southern limit of northerly derived Devonian clastic rocks
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Figure 1. Generalized distribution of Innuitian clastic wedge strata, sedimentary dispersal patterns during the Devonian, and Phanerozoic mountain belts of North America (modifi ed from Patchett et al., 1999, 2004).
Figure 2. Distribution of tectonic elements and geologic features of northern Alaska and Canada (modifi ed from Colpron and Nelson, 2009). BF indicates the location of the Middle Devonian Bird Fiord detrital zircon sample of McNicoll et al. (1995). NR represents the Late Devo-nian Nation River Formation detrital zircon sample of Gehrels et al. (1999).
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et al., 2010), Triassic sandstone in the Canadian Arctic Islands (Miller et al., 2006), and Paleo-zoic metaclastic units underlain by Ediacaran and older rocks of the Arctic Alaska–Chukotka terrane (Figs. 2 and 3) in northern Alaska (Moore et al., 2007; Amato et al., 2009). Pennsylvanian and Triassic Cordilleran margin strata in Alberta and British Columbia also contain ca. 430 Ma detrital zircons (ID-TIMS; Ross et al., 1997; Gehrels and Ross, 1998). The Nd isotopic sig-natures of Mississippian to Triassic strata of the Cordilleran miogeocline are in agreement with a source from Ellesmerian clastic wedge units, in-dicating that Innuitian foreland basin sediments were continuously cannibalized and recycled into younger rocks along the western Lauren-tian margin (Boghossian et al., 1996; Ross et al., 1997; Garzione et al., 1997; Patchett et al., 1999, 2004; Beranek et al., 2010).
Although it is generally accepted that the In-nuitian hinterland terranes originated near the Timanian orogenic belt of Baltica and the Cale-donides of northern Europe and Greenland (e.g., Trettin, 1987; Amato et al., 2009), the early to mid-Paleozoic paleogeography and confi gu-ration of these tectonic elements are not well understood (Lawver et al., 2002). This problem is exacerbated by the dismemberment of the In-nuitian hinterland during late Mesozoic opening
of the Arctic Ocean and formation of the Eur-asian and Amerasian basins (e.g., Miller et al., 2006). One tectonic argument of considerable debate features the “rotational opening model,” in which Cretaceous rifting rotated the Arctic Alaska–Chukotka terrane away from the Cana-dian Arctic Islands about a pole in the Macken-zie River delta region (e.g., Lawver and Scotese, 1990; Lane, 1997; Lawver et al., 2002; Toro et al., 2004; Miller et al., 2006). Crustal exten-sion associated with Amerasian basin formation also led to the fragmentation and foundering of continental crust, and Embry (1992) referred to one such submerged landmass as “Crocker-land.” The now-missing Crockerland, perhaps once 250,000 km2 in size, is presently overlain by continental shelf and slope deposits along the Canadian Arctic margin, but it once served as a constant source region for Carboniferous to Ju-rassic sediments in the Canadian Arctic Islands (Embry, 1992; Miller et al., 2006).
In this paper, we report >500 detrital zircon ages from Late Devonian to early Mississippian Imperial and Tuttle Formation sandstone and conglomerate of the western Ellesmerian clas-tic wedge in Yukon and Northwest Territories, northwestern Canada. The results of >200 de-trital zircon analyses from Late Devonian Earn Group and middle to late Mississippian Keno
Hill Quartzite and Tsichu formation miogeo-clinal sandstone in Yukon are also presented. Our primary objectives were to: (1) increase the number of detrital zircon ages on Ellesmerian foreland strata by utilizing LA-ICP-MS meth-ods and (2) create a new detrital zircon database for mid-Paleozoic strata of the northern Cor-dilleran miogeocline. Our results confi rm that the western Ellesmerian clastic wedge displays provenance linkages with Innuitian terranes by the presence of detrital zircons that are consis-tent with Caledonian and Timanide sources. These exotic detrital zircons were recycled into strata of the northern Cordilleran miogeocline by middle Mississippian time. Detrital zircon results allow further provenance correlations be-tween Innuitian terranes and similar Caledonian and Baltican tectonic elements now present in the North American Cordillera and provide new commentary on Arctic paleogeography prior to the Cretaceous opening of the Amerasian basin.
GEOLOGIC FRAMEWORK
The detrital zircon signature of Ellesmerian clastic wedge strata is genetically linked to source rocks involved in Innuitian orogenesis. Discrete phases of deformation, magmatism, and sedimentation in the paleo-Arctic realm are outlined next to describe the regional geologic framework and detrital zircon source areas.
Late Silurian
The Late Silurian accretion of the Pearya terrane against the ancestral Arctic margin of Laurentia by sinistral transpression was the ear-liest phase of Innuitian orogenesis (Trettin et al., 1991). Late Silurian convergence led to the formation of the Clements Markham fold-and-thrust belt and basement-cored Boothia Uplift in the Canadian Arctic Islands (Fig. 2). The timing of Pearya terrane accretion is similar to that of the Scandian phase of the Caledonian orogen, in which the continent-continent collision between Baltica and Laurentia was driven by closure of the Iapetus Ocean (Stephens and Gee, 1985; Trettin, 1991). The Pearya terrane also records a Middle Ordovician deformational event com-parable in age to the Taconic orogeny in the northern Appalachians (Trettin et al., 1991).
The Pearya terrane is composed of pre-Mesoproterozoic metasedimentary and metavol-canic rocks intruded by 1000–1100 Ma plutons (U-Pb ID-TIMS; Trettin et al., 1987) and over-lain by Neoproterozoic to early Paleozoic vol-canic and marine sedimentary rocks (Trettin, 1987). Neoproterozoic sedimentary units on northern Ellesmere Island (Fig. 2) are similar to coeval assemblages in southwestern Spitsbergen
LochkovianPragian
Emsian
Eifelian
Frasnian
Famennian
Tournaisian
Visean
Serpukhovian
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Central and Eastern Yukon
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Portrait Lake Fm.Ea
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rou
pHorn River Group
Road River Group
Keno HillQuartzite
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Middle
Late
ca. 407 Ma
ca. 397 Ma
ca. 385 Ma
ca. 374 Ma
ca. 359 Ma
ca. 345 Ma
ca. 328 Ma
ca. 311 Ma
ca. 416 Ma
ca. 392 Ma
Bashkirian
Givetian
Figure 3. Devonian and Mississippian stratigraphic and tectonic framework in Yukon and Northwest Territories (adapted from Gordey et al. [1991] using the time scale of Gradstein et al. [2004] and fossil determinations in Orchard [2006]). Abbreviations: Fm.—Formation (formal), fm.—formation (informal), N.—northern, NWT—Northwest Territories.
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1902 Geological Society of America Bulletin, November/December 2010
(Svalbard), suggesting that the Pearya terrane is genetically associated with the northern Cale-donides (Bjornerud, 1989; cf. Trettin, 1987; Mazur et al., 2009). Known and suspected arc-type felsic volcanic rocks of the Pearya terrane have been dated by U-Pb zircon at ca. 450 and 500 Ma (ID-TIMS; Trettin et al., 1987). Late Middle Ordovician granodiorite emplaced after Taconic-age deformation yields U-Pb zircon and sphene ages of ca. 460 Ma (ID-TIMS; Trettin et al., 1987). An Early Devonian (390 ± 10 Ma) pluton is also recognized to intrude the Pearya terrane (ID-TIMS; Trettin et al., 1987).
Early to Middle Devonian
The Arctic Alaska–Chukotka terrane is a large (3,000,000 km2) crustal fragment that under-lies the North Slope and Seward Peninsula of northern Alaska and the Chukotka Peninsula and Bering and Siberian continental shelves along northeastern Russia (Amato et al., 2009). Felsic metavolcanic and metaplutonic rocks of the terrane yield U-Pb zircon ages by ID-TIMS and SHRIMP methods of 540–565, 650–710, 870, and 971 Ma, which are similar in age to magmatic events documented in Svalbard, the Ediacaran Timanide orogenic belt of Baltica, and peri-Gondwanan Avalonian-Cadomian arc systems (e.g., Patrick and McClelland, 1995; Gee and Pease, 2004; Amato et al., 2009). The southern margin (present coordinates) of the Arctic Alaska–Chukotka terrane (Coldfoot and Hammond subterranes in Fig. 2) was the site of Middle Devonian (ca. 375–390 Ma), and pos-sibly Early Devonian (405 Ma), arc magma-tism of the Ambler sequence (U-Pb SHRIMP; McClelland et al., 2006; Raterman et al., 2006). Middle Devonian (ca. 390 Ma) metaplutonic rocks are also recognized on the Seward Penin-sula (Till et al., 2006; Amato et al., 2009).
Field, subsurface, and detrital zircon data demonstrate that early Paleozoic rocks of the Arctic Alaska–Chukotka terrane were affected by intense regional deformation in the Innui-tian realm after Late Silurian accretion of the Pearya terrane. In the eastern Arctic Alaska–Chukotka terrane, isoclinal folding and north-directed thrust faulting developed during the late Early Devonian to earliest Middle Devo-nian (ca. 395 Ma) Romanzof orogeny (Fig. 2; Lane, 2007). Romanzof orogenesis records an Early to Middle Devonian phase of deforma-tion related to the progressive accretion of a continent-scale terrane against the northwest-ern Laurentian margin (Lane, 2007). Roman-zof structures in northern Yukon are crosscut by Late Devonian (ca. 360–375 Ma) plutons (U-Pb ID-TIMS; Mortensen and Bell, 1991; Lane, 2007).
Mississippian conglomerate above a sub-Mississippian unconformity in the northeastern Brooks Range contains 320–390, 560–900, and 1200–1450 Ma detrital zircons that are not ob-served in a sample of the underlying Neo protero-zoic quartzite (SHRIMP and LA-ICP-MS; Moore et al., 2007). The provenance signatures of the Mississippian conglomerate are also different to those of Silurian to Mississippian rocks in the western Arctic Alaska–Chukotka terrane, which yield 390–440, 475–600, and 1500–1700 Ma detrital zircons (Moore et al., 2007; Amato et al., 2009). Moore et al. (2007) interpreted the Mississippian conglomerate as having been deposited after regional tectonism and concluded that its detrital zircons were de-rived from a source region outside of the Brooks Range. Detrital zircon results from several samples in the northeastern Brooks Range are comparable to those of autochthonous North American strata in east-central Alaska, indicat-ing that the eastern Arctic Alaska–Chukotka ter-rane was sutured against northern Laurentia in the Devonian (Moore et al., 2007; cf. Dumoulin et al., 2000; Lane, 2007).
Late Devonian to Mississippian
The Ellesmerian orogeny in its classic sense is restricted to Late Devonian to early Missis-sippian regional deformation in the Canadian Arctic Islands and northern Greenland (e.g., Trettin et al., 1991). Ellesmerian orogenesis produced a wide (>375 km) foreland fold belt and ca. 360–365 granitic intrusions (U-Pb ID-TIMS; Trettin, 1991). The cause of Late Devonian to early Mississippian deformation in the Canadian Arctic Islands remains enigmatic (e.g., Lawver et al., 2002); however, Embry (1992) suggested that the accretion of Crocker-land against northern Laurentia was responsible for Ellesmerian orogenesis. West of the Cana-dian Arctic Islands, fi eld and seismic-refl ection data indicate that south- to southeast-vergent thrust faults and folds in the Mackenzie River delta and Richardson Mountains areas of north-ern Yukon are of Ellesmerian age (Lane, 2007, and references therein).
Ellesmerian orogenesis produced an exten-sive clastic wedge sequence along the length of the entire Innuitian tectonic province (Trettin, 1991). In northern Yukon and Northwest Terri-tories, syntectonic clastic rocks of the Late De-vonian Imperial Formation and Late Devonian to early Mississippian Tuttle Formation origi-nated from nearby orogenic highlands. Seismic-refl ection data show that Imperial Formation rocks were folded by the late early Carbonifer-ous, suggesting that Ellesmerian tectonism in the Mackenzie River delta–Richardson Moun-
tains area progressed to the south (Lane, 2007). The trace of the Ellesmerian deformation front in northern Yukon has not yet been identifi ed along strike in eastern Alaska, near the Late De-vonian Nation River Formation detrital zircon sample (Fig. 2) of Gehrels et al. (1999).
METHODS AND DATA PRESENTATION
Detrital zircons in the present study were dated at the Pacifi c Centre for Isotopic and Geo-chemical Research (PCIGR) at the University of British Columbia with a New Wave UP-213 laser ablation system and Thermo-Finnigan Element2 high-resolution ICP-MS following operating parameters similar to those described by Chang et al. (2006). Line scans rather than spot analyses were employed to minimize the effects of within-run elemental fractionation. The time-integrated signals were analyzed using the GLITTER software package described by Van Achterbergh et al. (2001) and Jackson et al. (2004). Complete details of the analytical meth-ods used at the PCIGR are listed in the GSA Data Repository.1 Isotopic ratios, apparent ages, and UTM locations from each sample are also presented in Table DR1 (see footnote 1). Inter-preted ages for grains younger than 1000 Ma are based on calculated 206Pb/238U ages. For detrital zircons older than 1000 Ma, 207Pb/206Pb ages are typically used.
Detrital zircon ages are presented in relative probability and cumulative probability plots, which were prepared with Microsoft Excel macros developed by G.E. Gehrels at the Uni-versity of Arizona. Although the “height” of detrital zircon age peaks in relative probabil-ity plots indicates the frequency and analytical precision rather than the number of grains in the peak, we suggest that these graphs allow a straightforward comparison between several de-trital zircon data sets regardless of their sample size or analytical methodology (e.g., Sircombe, 2000). The number of detrital zircons in each probability age peak is noted in the sample results section. Detrital zircon age spectra are displayed in two separate plots: one from 0 to 3000 Ma to show the full distribution of detrital zircon ages, and one containing 200 or 300 Ma to 700 Ma to highlight the youngest detrital zir-con components. Detrital zircons with >10% discordance were excluded from our results and probability plots. Discordance was determined as the ratio between the 238U/206Pb age and the 207Pb/206Pb age. The total number of analyses for
1GSA Data Repository item 2010188, a descrip-tion of analytical techniques and complete U-Pb zircon analytical data, is available at http://www.geosociety.org/pubs/ft2010.htm or by request to [email protected].
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each sample is reported with the presentation of detrital zircon age results (e.g., n = 51/64 indi-cates a total of 64 analyses yielded 51 ages that were <10% discordant).
SAMPLE LOCATION GEOLOGY AND DETRITAL ZIRCON RESULTS
Late Devonian Imperial Formation
The Frasnian to Famennian Imperial For-mation consists of fi ne-grained sandstone and shale that crop out in the Richardson Mountains area of northern Yukon and eastern Mackenzie Mountains along the Yukon–Northwest Ter-ritories border (Figs. 3–5; Braman and Hills, 1992). Imperial Formation sandstone is typi-cally composed of quartz, feldspar, chert, and accessory white mica. The Imperial Formation ranges in thickness from 590 to 1690 m, with the greatest accumulation in the Peel Plateau area of northwestern Northwest Territories (Gordey et al., 1991).
The Imperial Formation at its type location in the Mackenzie Mountains consists of inter-calated sandstone lobe and lobe-fringe deposits within a submarine fan-slope complex (Hadlari et al., 2009). Southwest-dipping seismic refl ec-tors show the turbidite complex had a source from the east-northeast (Hadlari et al., 2009). Late Devonian turbiditic sandstone units in northern Yukon and Northwest Territories to the north and west of the Mackenzie Moun-tains contain fl ute casts, load casts, and tool marks that suggest a source region to the north (Gordey et al., 1991).
Four samples of Imperial Formation sand-stone were selected for detrital zircon analysis to provide new constraints on the source of the Late Devonian Ellesmerian clastic wedge. Fras-nian feldspathic sandstone of sample I1 was col-lected ~100 m above the base of the formation near the type section in the Mackenzie Moun-tains of the Northwest Territories (Fig. 5). Sam-ples I2, I3, and I4 consist of Frasnian feldspathic sandstone, chert lithic sandstone, and quartz
sandstone, respectively, selected from outcrops of the middle Imperial Formation exposed along the Dempster Highway in northern Yukon and Northwest Territories (Fig. 5).
ResultsTurbiditic sandstone of sample I1 yielded
detrital zircon age clusters (Fig. 6A) at 428–462 Ma (15%; 8 grains), 530–556 Ma (~10%; 5 grains), 640–657 Ma (~8%; 4 grains), 673–690 Ma (~8%; 4 grains), 1393–1512 Ma (13%; 7 grains), and 1570–1666 Ma (~8%; 4 grains). Overall, Silurian to Cryogenian detrital zircon ages form over 50% (26 grains) of sample I1. Detrital zircons older than 1700 Ma are rare in sample I1, even when accounting for grains with >10% discordance (only 5 of 64 analyses).
Samples I2–I4 contain Silurian and Ordo-vician (ca. 415–460 Ma) detrital zircons at a 7% level (Figs. 6B–6D). The cumulative prob-ability plot of Figure 6 illustrates that samples I2–I4 generally have overlapping age spectra. These Imperial Formation sandstones have
Area of Area of Figure 5Figure 5
Keno HillKeno HillQuartziteQuartziteKeno Hill Quartzite
Figure 4. Simplifi ed tectonic ele-ment map of the Alaskan and Ca-nadian Cordillera (modifi ed from Colpron et al., 2007) that displays the location and distribution of detrital zircon samples from this study. Abbreviations: AB—Alberta, AK—Alaska, B.C.—British Colum-bia, Fm.—Formation, fm.—forma-tion (informal), NWT—Northwest Territories, YT—Yukon.
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large amounts of ca. 1800–2000 Ma detrital zircon, including 35% and 50% of the grains in samples I3 and I4, respectively. Archean (>2500 Ma) detrital zircons occur at ~11% level in samples I2–I4. Each sample of the Im-perial Formation suite produced one to three detrital zircons of Middle to Late Devonian (ca. 360–395 Ma) age.
Late Devonian to Early Mississippian Tuttle Formation
The Famennian to Tournaisian Tuttle Forma-tion is defi ned as a package of coarse-grained clastic rocks overlying the Imperial Formation in the Richardson Mountains and Peel Plateau regions of northern Yukon (Figs. 3–5; Fraser and Allen, 2007). The Tuttle Formation con-sists of chert conglomerate, very poorly sorted quartz and chert lithic sandstone, and micaceous sandstone, siltstone, and shale at its type section (Pugh, 1983). Surface and borehole studies in-dicate that the Tuttle Formation is up to 1420 m thick (Pugh, 1983; Gordey et al., 1991).
Pugh (1983) proposed that the lowermost occurrence of coarse-grained clastic strata con-formably overlying Imperial Formation rocks represents the base of the Tuttle Formation. The transition is a facies boundary document-ing a lateral and vertical grain-size boundary that is essentially diachronous. Therefore, the terms “upper Imperial Formation” and “lower Tuttle Formation” may be somewhat ambigu-ous, and geographic location may be more im-portant than stratigraphic position. There is no consensus on the depositional setting for Tuttle Formation strata, as both marine and nonmarine alternatives have been suggested (Lutchman, 1977; Hills and Braman, 1978). South-directed paleocurrent indicators (load casts, fl ute casts, tool marks) imply that Tuttle Formation strata originated from a region to the north (Gordey et al., 1991). However, seismic-refl ection data from the Peel Plateau area display southwest-dipping clinoforms within the Tuttle Formation, indicating a source from the northeast (Osadetz et al., 2005; Hadlari et al., 2009).
Five samples of Tuttle Formation strata in the Peel Plateau area were selected for detrital zir-con analysis to determine the provenance of the uppermost Ellesmerian clastic wedge sequence in northern Yukon (see sample locations in Fig. 5). Samples T1 and T2 were collected from exposures of lower Tuttle Formation quartz sandstone along the eastern fl ank of the Richard-son Mountains described by Fraser and Allen (2007). Samples T3 and T4 were taken from outcroppings of quartz sandstone in the upper Tuttle Formation and quartz pebble conglomer-ate from an unconstrained stratigraphic position,
respectively, also observed by Fraser and Allen (2007). Chert lithic sandstone of sample T5 was collected from the lower Tuttle Formation along the Dempster Highway at Eagle Plains.
ResultsLower Tuttle Formation sandstone samples
T1 and T2 have similar cumulative probability spectra and large detrital zircon age clusters at ca. 1800–2000 Ma (>30%; >20 grains) and 2500–2700 Ma (Figs. 7A and 7B). Silurian to Cryogenian detrital zircons occur at an ~5% level, and each sandstone yielded a single age at ca. 432 Ma. Three grains of Middle to Late Devonian (ca. 370–397 Ma) detrital zircon were observed in both samples T1 and T2.
Latest Silurian to Ordovician (ca. 415–475 Ma) detrital zircons in sample T3 are observed at a 20% level (12 grains), which cul-minate in an age cluster from 431 to 438 Ma (Fig. 7C). Proterozoic age groupings are identi-fi ed in sample T3 at ca. 1000–1300 Ma (15%),
ca. 1400–1600 Ma (8%; 5 grains), and ca. 1800–2000 Ma (36%; 21 grains).
Quartz pebble conglomerate of sample T4 is dominated by ca. 1800–2000 Ma (45%; 33 grains) detrital zircons and also contains sub-ordinate amounts of ca. 1100–1200 Ma (8%; 6 grains), 1500–1639 Ma (~7%; 5 grains), and ca. 2600–2800 Ma (~11%; 8 grains) ages (Fig. 7D). Four detrital zircons in sample T4 gave Middle to Late Devonian (372–387 Ma) ages.
Chert lithic sandstone of sample T5 pro-duced a grouping of ca. 1800–2000 Ma detrital zircons at a 30% level (19 grains). Meso protero zoic ages at ca. 1000–1300 Ma (24%; 15 grains) and ca. 1500–1650 Ma (11%; 7 grains) give sample T5 a slightly different spectral profi le than the other Tuttle Forma-tion samples east of the Richardson Mountains (see Fig. 7E and cumulative probability plot). Sample T5 yielded scattered early Paleozoic to Ediacaran (ca. 387–560 Ma) ages, including a cluster of three grains at ca. 365 Ma.
ArcticArcticRed RiverRed RiverArcticRed River
Richardson Mountains
Mackenzie Mountains
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Highway
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Sample T2Sample T2
Sample T4Sample T4
Sample T1Sample T1
Sample T5Sample T5
Sample T3Sample T3
Sample I2Sample I2
Sample I3Sample I3
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68° N
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Figure 5. Distribution of Devonian and Mississippian strata and location of detrital zircon samples in the northern Richardson Mountains–Peel Plateau area of northern Yukon and Northwest Territories (NWT).
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Detrital zircon geochronology of the western Ellesmerian clastic wedge, northwestern Canada
Geological Society of America Bulletin, November/December 2010 1905
Late Devonian to Middle Mississippian Cordilleran Margin Strata
Regional extension along the northern Cor-dilleran margin during the Devonian led to the deposition of turbiditic clastic rocks assigned to the Earn Group (Gordey et al., 1991). The mid-Famennian to Tournaisian (?) Prevost Forma-tion (>900 m thick) of the upper Earn Group in eastern Yukon is composed of chert pebble con-glomerate and chert lithic sandstone deposited in a submarine-fan complex (Fig. 3; Gordey et al., 1982; Gordey and Anderson, 1993). Paleo current and petrographic data indicate that Prevost For-mation rocks were derived from uplifted blocks of Late Proterozoic to early Paleozoic sandstone and chert to the northeast (Gordey et al., 1991; Gordey and Anderson, 1993). Coarse-grained chert lithic sandstone from the Prevost Forma-tion in eastern Yukon was collected to evaluate the detrital zircon provenance signature of upper Earn Group rocks (Fig. 4).
Mississippian strata in central and eastern Yukon record stable clastic shelf sedimenta-tion along the Cordilleran margin in the time following the deposition of Earn Group rocks and Ellesmerian orogenesis (Fig. 3; Gordey and Anderson, 1993). A single sample of middle to late Mississippian quartz sandstone from Keno Hill Quartzite was collected along the Dempster Highway in the Ogilvie Mountains of west-central Yukon (Fig. 4). Two samples of middle
to late Mississippian quartz sandstone from the uppermost Tsichu formation (informal; Gordey and Anderson, 1993) were selected from adja-cent outcrops in the Selwyn Mountains of east-ernmost Yukon (Fig. 4).
ResultsLate Devonian Prevost Formation sandstone
from eastern Yukon primarily yields ca. 1750–2100 Ma detrital zircons (68%: 51 grains), and Archean groupings at ca. 2500–2600 Ma (~11%; 8 grains) and ca. 2700–2800 Ma (9%; 7 grains) form subordinate age clusters (Fig. 8A). The youngest detrital zircon ages in this sample were at 1043, 1169, and 1355 Ma.
The sample of Mississippian Keno Hill Quartz ite from west-central Yukon has dis-cernible age groupings at 430–473 Ma (11%; 7 grains), 1000–1160 Ma (18%; 11 grains), 1503–1648 Ma (16%; 10 grains), and 1801–1867 Ma (15%; 9 grains) (Fig. 8B). Three ca. 900 Ma detrital zircons represent 5% of the sample.
Nearly 40% of sample TS1 sandstone (16 grains) is composed of Silurian to Edia-caran detrital zircons, including a cluster from ca. 425 to 435 Ma (21%; 9 grains) (Fig. 8C). Minor (~10%) age occurrences from 367 to 380 Ma and ca. 1000 to 1060 Ma are also pres-ent. Sample TS2 has large age groupings at 406–428 Ma (~18%; 10 grains), 1436–1643 Ma (~18%; 10 grains), and ca. 1800–2000 Ma
(16%; 9 grains) (Fig. 8D). Populations from ca. 1000 to 1034 Ma and ca. 2600 to 2700 Ma constitute 7% of the ages in sample TS2.
DISCUSSION
Detrital zircon results from sandstone sam-ples in Yukon and Northwest Territories pro-vide new geologic constraints on Ellesmerian clastic wedge and northern Cordilleran margin strata. These data are used to evaluate: (1) the source of Imperial and Tuttle Formation rocks; (2) the composition of the northern Cor di lleran miogeocline following Ellesmerian oro genesis; (3) the mid-Paleozoic paleogeography of Cale-donian and Baltican tectonic elements in the Innuitian realm; and (4) implications for Cre-taceous tectonic reconstructions in the circum-Arctic region. Provenance correlations are made by comparing data from this study with those of prior detrital zircon investigations in western and northern North America (see Fig. 9).
Source of Ellesmerian Clastic Wedge Strata
Imperial FormationThe composite Late Devonian Imperial
For ma tion detrital zircon data set (n = 192; Fig. 9A) yields signifi cant age peak populations (>10 grains) at 428, 434, 442, 1158, 1405, 1697, 1824, 1966, 2058, 2098, and 2573 Ma. Minor (>5 grains) populations are recognized at 383, 393, 551, and ca. 670–690 Ma.
Devonian (383, 393 Ma) probability peaks in Imperial Formation sandstones roughly overlap in age with the 390 ± 10 Ma pluton emplaced into the Pearya terrane (Trettin et al., 1987) and igneous rocks in the western and southern Arc-tic Alaska–Chukotka terrane (McClelland et al., 2006; Amato et al., 2009). Silurian to Ordovi-cian age peaks (428–442 Ma) correlate with the main phase of Caledonian magmatism in eastern Greenland (e.g., Watt et al., 2000; see shaded gray bar in Fig. 9) and the 424–434 Ma detri-tal zircon occurrences in Middle to Late Devo-nian clastic wedge strata in the Canadian Arctic Islands (Fig. 9G; McNicoll et al., 1995) and eastern Alaska (Fig. 9H; Gehrels et al., 1999). Ediacaran to Cryogenian (ca. 550–680 Ma) ages, which were only observed in sample I1, suggest provenance linkages with the Arctic Alaska–Chukotka terrane (Fig. 9L; Amato et al., 2009; see shaded gray bar in Fig. 9 and later dis-cussion). Paleo proterozoic (ca. 1800–2000 Ma) detrital zircons in the Imperial Formation are comparable in age to crystalline rocks of the northwest Laurentian craton (e.g., Hoffman, 1988; see shaded gray bar in Fig. 9) and de-trital zircon occurrences in pre–Late Devonian Cordilleran margin strata in western Canada
0 500 1000 1500 2000 2500 3000 3500Age (Ma)
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(A) Sample I1 n = 51/64
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(D) Sample I4 n = 40/50
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Figure 6. Relative probability and cumulative probability plots (0–3000 Ma and 300–700 Ma) displaying detrital zircon ages from the Imperial Formation: (A) sample I1—lower Imperial Formation feldspathic sandstone; (B) sample I2—middle Imperial Formation feldspathic sandstone; (C) sample I3—middle Imperial Formation chert lithic sandstone; and (D) sample I4—middle Imperial Formation quartz sandstone.
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(Figs. 9C and 9F; Gehrels and Ross, 1998) and eastern Alaska (Fig. 9E; Gehrels et al., 1999).
Silurian to Cryogenian detrital zircon popu-lations in Late Devonian clastic wedge sand-stones are consistent with a source from allochthonous terranes involved in Innuitian orogenesis and igneous rocks produced during Caledonian magmatism in Greenland. Paleo-current and seismic-refl ection data sets, which suggest Imperial Formation rocks were derived from a region to the north-northeast, are in agreement with this hypothesis (Gordey et al., 1991; Hadlari et al., 2009). A northerly or north-easterly source is also supported by the occur-rence of Devonian detrital zircons inferred to be derived from ca. 380–390 Ma Pearya and Arctic Alaska–Chukotka terrane igneous rocks (Trettin et al., 1987; McClelland et al., 2006; Amato et al., 2009). The large amount of ca. 1800–2000 Ma detrital zircon most likely comes from early Paleozoic North American strata along the northern Laurentian margin that were uplifted during regional Innuitian deformation and re-cycled into Late Devonian rocks.
Tuttle FormationThe Late Devonian to early Mississippian
Tuttle Formation composite signature (n = 328; Fig. 9B) includes prominent (>9 grains) age peaks at 436, 1025, 1163, 1249, 1502, 1622, 1849, 1933, 2333, 2595, and 2683 Ma. Smaller
Paleozoic populations (>5 grains) also occur at 371, 381, 446, and 462 Ma.
Early to Late Devonian detrital zircon ages in the Tuttle Formation samples are consistent with a source from ca. 360–390 Ma intrusive rocks emplaced into the Arctic Alaska–Chukotka terrane (McClelland et al., 2006; Lane, 2007; Amato et al., 2009), and the Pearya terrane in the Canadian Arctic Islands (Trettin et al., 1987). Silurian to Ordovician detrital zircons overlap in age with new results from the Impe-rial Formation (Fig. 9A), Middle to Late Devo-nian clastic wedge strata in the Canadian Arctic Islands (Fig. 9G; McNicoll et al., 1995) and eastern Alaska (Fig. 9H; Gehrels et al., 1999), and Caledonian magmatism in eastern Green-land (see shaded gray bar in Fig. 9).
Mesoproterozoic (ca. 1000–1300 Ma) ages, which are more prevalent in the Tuttle Forma-tion than in the Imperial Formation, correspond to detrital zircon occurrences in Ordovician to Devonian strata along the Cordilleran mar-gin (Figs. 9E and 9F; Gehrels and Ross, 1998; Gehrels et al., 1999) and the Canadian Arctic Islands (Fig. 9G; McNicoll et al., 1995). These ca. 1000–1300 Ma “Grenville-age” detrital zir-cons have many possible sources in the paleo-Arctic realm, including the Pearya terrane and rocks of similar affi nity in Greenland and the western Baltican Shield (e.g., Trettin et al., 1987; Åhäll and Connelly, 1998) or North American
strata derived from the Grenville Province of eastern Laurentia (e.g., Rainbird et al., 1992).
Early Mesoproterozoic to late Paleo protero-zoic (1500–1630 Ma) detrital zircons, i.e., 13 grains with probability age peaks at 1502 and 1622 Ma, are not typical of northern Lau-rentian rocks but generally correspond to the 1490–1610 Ma North American magmatic gap (Van Schmus et al., 1993; see shaded gray bar in Fig. 9). Although 1430–1500 Ma anorogenic igneous rocks in the eastern Laurentian craton overlap with this magmatic gap (e.g., Ross and Villeneuve, 2003), results from the Tuttle Formation also correlate in age with rocks in northern Europe involved in Caledonian oro-genesis, such as the 1502 ± 3 Ma gabbro-granite complexes of southwestern Sweden (ID-TIMS; Åhäll and Connelly, 1998). Detrital zircon ages from ca. 1500 to 1625 Ma are also rec-ognized in Proterozoic metasedimentary rocks of Svalbard (ID-TIMS; Balashov et al., 1996; Hellman et al., 1997) and southwestern Sweden (SHRIMP; Knudsen et al., 1997; Åhäll et al., 1998). Similarly, Paleozoic metasedimentary rocks of the Arctic Alaska–Chukotka terrane in northwestern Alaska have detrital zircon prob-ability age peaks at 1495 and 1613 Ma (Fig. 9L, see later discussion; Amato et al., 2009). Paleo-proterozoic (ca. 1800–2000 Ma) and Archean (ca. 2600 Ma) ages in the Tuttle Formation are comparable to those of the Imperial Formation (Fig. 9A), pre–Late Devonian strata in west-ern Canada and eastern Alaska (Figs. 9D–9F; Gehrels and Ross, 1998; Gehrels et al., 1999), and Middle to Late Devonian Ellesmerian clas-tic wedge rocks (Figs. 9G and 9H; McNicoll et al., 1995; Gehrels et al., 1999).
The occurrences of Devonian, Silurian to Ordovician, and early Mesoproterozoic to late Paleoproterozoic detrital zircons indicate that Tuttle Formation strata were in part derived from Innuitian terrane and Caledonian rocks, in agreement with the source regions to the north-northeast determined by paleocurrent and seismic-refl ection data (Gordey et al., 1991; Hadlari et al., 2009). The Tuttle Formation sam-ples contain more Devonian (ca. 360–390 Ma) and Mesoproterozoic and late Paleoproterozoic (ca. 1000–1300, 1500–1610 Ma) detrital zir-cons, and lesser amounts of Silurian to Cryo-genian (ca. 430–680 Ma) ages, than those of the Imperial Formation suite. We speculate that this provenance shift may be attributed to the progressive unroofi ng and erosion of In-nuitian crustal blocks during Ellesmerian oro-genesis. For example, feldspathic sandstone of the Imperial Formation suite contains Silurian to Ediacaran detrital zircon likely from high level volcanic and plutonic rocks, while Devonian and Mesoproterozoic grains in the quartzose
0 500 1000 1500 2000 2500 3000 3500Age (Ma)
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(D) Sample T4 n = 73/82
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(E) Sample T5 n = 51/72
(A) Sample T1 n = 70/90
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Figure 7. Relative probability and cumulative probability plots (0–3000 Ma and 300–700 Ma) displaying detrital zircon ages from the Tuttle Formation: (A) sample T1—lower Tuttle Formation quartz sandstone; (B) sample T2—lower Tuttle Formation quartz sand-stone; (C) sample T3—upper Tuttle Formation quartz sandstone; (D) sample T4—quartz pebble conglomerate; and (E) sample T5—lower Tuttle Formation chert lithic sandstone.
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Detrital zircon geochronology of the western Ellesmerian clastic wedge, northwestern Canada
Geological Society of America Bulletin, November/December 2010 1907
Tuttle Formation samples were derived from deeply exhumed 360–390 Ma plutons and Pre-cambrian basement rocks of the Pearya terrane, Arctic Alaska–Chukotka terrane, Crockerland, Greenland, or other Arctic tectonic elements.
Late Devonian to Triassic Evolution of the Northern Cordilleran Miogeocline
Prevost Formation sandstone from eastern Yukon yields detrital zircon age peaks at 1755, 1826, 1896, and 2000 Ma that correlate with prior analyses of pre–Late Devonian Cordi lleran margin strata in western Canada (Figs. 9D and 9F; Gehrels and Ross, 1998) and eastern Alaska (Fig. 9E; Gehrels et al., 1999). These data sug-gest that upper Earn Group strata originated from uplifted blocks of Neoproterozoic to early Paleozoic Cordilleran margin rocks (cf. Gordey and Anderson, 1993).
The composite detrital zircon signature of quartzose middle to late Mississippian strata from the northern Cordilleran margin sequence (n = 158; Fig. 9C) consists of dominant (>14 grains) age peak populations at 382, 415, 431, 1033, 1139, 1499, 1702, 1783, 1824, and 1940 Ma. All of these populations are identi-fi ed as ages or probability age peaks in Late Devonian to early Mississippian clastic wedge strata located in northern Yukon and North-west Territories (Figs. 9A and 9B). Prior to these analyses on middle to late Mississippian strata, early Paleozoic detrital zircons were not
observed in the Cordilleran miogeocline until Pennsylvanian-Permian time (Gehrels and Ross, 1998; see Figs. 9D and 9F).
Triassic Cordilleran margin strata in Yukon are rich in ca. 430 Ma detrital zircons and have appreciable amounts of Middle to Late Devonian, Cambrian to Cryogenian, and early Mesoproterozoic to late Paleoproterozoic ages (Fig. 9I; Beranek et al., 2010). We interpret these data, in combination with middle to late Mis-sissippian sample results, to demonstrate that ca. 360–390, 430–680, and 1500–1600 Ma de-trital zircons in clastic wedge strata were contin-uously cannibalized and recycled into younger Cordilleran margin rocks along western Lauren-tia. Whole-rock Nd isotopic data from middle Mississippian to Triassic Cordilleran margin strata in western Canada also support the post–Late Devonian sedimentary recycling of clastic wedge strata (Boghossian et al., 1996; Garzione et al., 1997; Ross et al., 1997; Beranek et al., 2010; cf. Patchett et al., 1999, 2004).
Mid-Paleozoic Paleogeography of Arctic Terranes
Numerous multidisciplinary studies have placed constraints on the mid-Paleozoic paleo-geog raphy of Innuitian and Cordilleran terranes with Caledonian, Baltican, and Siberian affi ni-ties (e.g., Soja, 1994; Bazard et al., 1995; Patrick and McClelland, 1995; Gehrels et al., 1996; Dumoulin et al., 2000; Blodgett et al., 2002;
Amato et al., 2009; Colpron and Nelson , 2009). Detrital zircon analysis of the western Elles-merian clastic wedge also provides general insights on mid-Paleozoic Arctic paleo geog-raphy. The mid-Paleozoic plate reconstruction of Figure 10, modifi ed from that of Colpron and Nelson (2009), illustrates the conclusions listed herein.
Embry (1992) suggested that the juxtaposi-tion of Crockerland against northern Laurentia produced the Ellesmerian orogeny because a continental landmass is required as a sediment source for Carboniferous to Jurassic strata in northern Canada. The Triassic Pat Bay Forma-tion in the Canadian Arctic Islands (Fig. 9K) and the Triassic Ivishak Formation underlain by Arctic Alaska–Chukotka terrane rocks in north-ern Alaska (Fig. 9J) originated from Crockerland and yield ca. 460–590, 1000–1300, 1600–1700, and 1800–1900 Ma detrital zircons, including large probability age peaks at ca. 530–590 Ma (Miller et al., 2006). Comparison with the 500–600 Ma detrital zircons in the Imperial For-mation samples (Fig. 9A) implies that Crocker-land supplied at least part of the Late Devonian Ellesmerian clastic wedge in northern Yukon and Northwest Territories (CL in Fig. 10).
Paleozoic metaclastic rocks of Arctic Alaska–Chukotka terrane in northwestern Alaska are dominated by ca. 400–440, 545–620, and 660–700 Ma detrital zircons (Fig. 9L; Amato et al., 2009). These metasedimentary units also exhibit detrital zircon ages correlative with the 1490–1610 Ma North American magmatic gap and have a paucity of ca. 1800–2000 Ma ages that characterize northwest Laurentian strata (Fig. 9). The detrital zircon profi les of Late Devonian to Triassic rocks in the Alaskan and northern Canadian Cordillera (Figs. 9A–9C, 9H, and 9I; Gehrels et al., 1999; Beranek et al., 2010), in particular their ca. 430 and 500–700 Ma ages, correspond well with that of the composite signature of Arctic Alaska–Chukotka terrane metaclastic rocks (Fig. 9L; Amato et al., 2009). Notably, Arctic Alaska–Chukotka terrane metaigneous rocks yield U-Pb SHRIMP and ID-TIMS age ranges of ca. 360–390, 540–565, and 650–710 Ma (e.g., Patrick and McClelland , 1995; Amato et al., 2009), in agreement with several probability age peaks in clastic wedge and miogeoclinal sample suites (Fig. 9). Over-all, we infer the late Early to early Middle Devonian Romanzof orogeny allowed the Arc-tic Alaska–Chukotka terrane to be a source for Late Devonian to early Mississippian strata in northwestern Laurentia (AA in Fig. 10).
In their treatment of early to mid-Paleozoic Arctic paleogeography, Colpron and Nelson (2009) suggested the Okanagan subterrane of Quesnellia (OK in Fig. 10), Yreka and Trinity
0 500 1000 1500 2000 2500 3000 3500Age (Ma)
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(B) Keno Hill Qtze. n = 60/69
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Figure 8. Relative probability and cumulative probability plots (0–3000 Ma and 300–700 Ma) displaying detrital zircon ages from Late Devonian to middle Mississippian strata of the Cordilleran miogeocline in Yukon: (A) Late Devonian Prevost Formation chert lithic sandstone; (B) Keno Hill Quartzite quartz sandstone; (C) sample TS1—upper Tsichu for-mation quartz sandstone; and (D) sample TS2—upper Tsichu formation quartz sandstone.
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subterranes of the eastern Klamath terrane (YR in Fig. 10), and Alexander terrane (AX in Figs. 4 and 10) in the North American Cordillera originated near the Caledonian and Timanian orogenic belts of present-day northern Europe.
In their model, the Okanagan terrane and Yreka and Trinity subterranes were transported west-ward from their origin by sinistral strike-slip motion during the Silurian, were involved in Early to Middle Devonian Romanzof deforma-
tion in northwestern Laurentia, and were then translated south alongside the Cordilleran mar-gin of western North America. According to Colpron and Nelson (2009), the Late Devonian to early Mississippian accretion of the Yreka
Figure 9. Relative probability plots (0–3000 Ma and 200–700 Ma) for U-Pb detrital zir-con data from this and prior studies. Errors from all data sets are plotted at the 2σ level. (A) Composite signature for Late Devonian Imperial For-mation samples presented in Figures 6A–6D. (B) Composite signature for Late Devonian to early Mississippian Tuttle Formation samples displayed in Figures 7A–7E. (C) Com-posite signature for middle Mississippian samples of Fig-ures 8B–8D. (D) Neoprotero-zoic to Cambrian miogeoclinal strata, British Columbia and Alberta (TIMS; Gehrels and Ross, 1998). (E) Cambrian mio geo clinal sandstone, east-ern Alaska (TIMS; Gehrels et al., 1999). (F) Ordovician to Early Devonian miogeoclinal rocks, British Columbia and Alberta (TIMS; Gehrels and Ross, 1998). (G) Composite signature of Middle Devonian clastic wedge strata, Cana-dian Arctic Islands (SHRIMP; McNicoll et al., 1995). (H) Late Devonian Nation River Forma-tion, eastern Alaska (TIMS; Gehrels et al., 1999). (I) Com-posite signature of Early to Late Triassic marine strata, west-central to southeastern Yukon (LA-ICP-MS; Beranek et al., 2010). (J) Early Trias-sic Ivi shak Formation, North Slope of northern Alaska (LA-ICP-MS; Miller et al., 2006). (K) Late Triassic Pat Bay Formation, Canadian Arc-tic Islands (LA-ICP-MS; Miller et al., 2006). (L) Composite sig-nature of Paleozoic metaclastic rocks of the Arctic Alaska–Chukotka terrane, northwestern Alaska (LA-ICP-MS; Amato et al., 2009). (M) Composite signature of Ordovi-cian to Triassic strata of the Alexander terrane, southeastern Alaska (TIMS; Gehrels et al., 1996). Shaded gray bars in the 0–3000 Ma plot correspond to the North American magmatic gap (Van Schmus et al., 1993) and northwest Laurentian craton (Hoffman, 1988). Shaded gray bars in 200–700 Ma plot indicate Silurian–Ordovician magmatism in the Caledonides of Greenland (Watt et al., 2000) and Neoproterozoic magmatism in the Arctic Alaska–Chukotka terrane (Amato et al., 2009, and references therein).
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(K) Triassic Pat Bay Fm.Canadian Arctic Islands
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(A) Composite Late Devonian Imperial Fm.
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Detrital zircon geochronology of the western Ellesmerian clastic wedge, northwestern Canada
Geological Society of America Bulletin, November/December 2010 1909
and Trinity subterranes against the Cordilleran margin was responsible for Antler orogenesis in the western United States (Fig. 10). Early to Middle Devonian strata of the Yreka subter-rane yield ca. 430 Ma and 1490–1610 Ma detri-tal zircons (SHRIMP and LA-ICP-MS; Grove et al., 2008), which are consistent with Cale-donian and Timanide sources, the signatures of Ellesmerian clastic wedge (Figs. 9A and 9B), and northern Cordilleran miogeoclinal strata (Figs. 9C and 9I; Beranek et al., 2010). Holo-cene to Neogene sediments derived from rocks of the Antler alloch thon and adjacent foreland basin succession in south-central Idaho yield ca. 360–460 Ma and 1500–1600 Ma detrital zir-con ages (SHRIMP; Link et al., 2005; Beranek et al., 2006), which are also observed in Elles-merian clastic wedge and Yreka subterrane data sets, further suggesting that Antler terrane rock assem blages originated near the Caledonides.
The oldest units of the Alexander terrane (AX in Fig. 4), which underlies large portions of southeastern Alaska, northwestern British Columbia, and southwestern Yukon, include Ediacaran (554–595 Ma), Middle Ordovician (ca. 460 Ma), and Silurian (ca. 430 Ma) igne-ous rocks (U-Pb ID-TIMS; Gehrels et al., 1987;
Gehrels, 1990). Early Paleozoic detrital zircon age peaks at ca. 360, 429, 459, and 480 Ma are also ubiquitous in Ordovician to Triassic strata of the terrane in southeastern Alaska (Fig. 9M; TIMS; Gehrels et al., 1996). Detrital and igne-ous U-Pb zircon ages from Alexander terrane rocks correlate with results from the Ellesme-rian clastic wedge (Figs. 9A, 9B, 9G, and 9H; McNicoll et al., 1995; Gehrels et al., 1999), Mississippian and Triassic Cordilleran margin rocks (Figs. 9C and 9I; Beranek et al., 2010), and Arctic Alaska–Chukotka terrane metaclastic units (Fig. 9L; Amato et al., 2009). These data suggest that the Alexander terrane was located in the Innuitian realm (AX in Fig. 10) during Ellesmerian orogenesis and originated near the Caledonian and Timanide orogenic belts of northern Europe (cf. Grove et al., 2008; Colpron and Nelson, 2009).
Implications for Cretaceous Plate Reconstructions
The precise location of the Arctic Alaska–Chukotka terrane prior to the formation of the western Arctic Ocean is highly contentious, and several models have been proposed to describe
its tectonic evolution during the Cretaceous opening of the Amerasian basin (e.g., Lawver and Scotese, 1990; Lane, 1997). In the most popular model, the rotational opening model, the Arctic Alaska–Chukotka terrane rotated counterclockwise (~66°) away from northern Canada about a pole in the Mackenzie River delta region, suggesting that the present-day northern part of the terrane, shown as the east-facing margin in Figure 10, was juxtaposed with Canadian Arctic Islands (Lawver et al., 2002). Therefore, a rotational restoration requires the northern margins of Alaska and the Canadian Arctic Islands to be conjugates of comparable age and evolution (Embry, 1990).
Sandstone samples of the northerly derived Triassic Pat Bay Formation in the Canadian Arctic Islands (Fig. 9K) and the northerly de-rived (present coordinates) Triassic Ivishak Formation underlain by the northern Arctic Alaska–Chukotka terrane in northern Alaska (Fig. 9J) contain ca. 500–600 Ma detrital zircon populations interpreted to be derived from the landmass of Crockerland (Miller et al., 2006). Both of these Triassic samples yield very few ca. 360–500 Ma detrital zircons that form prob-ability age peaks in Paleozoic metaclastic rocks of the Arctic Alaska–Chukotka terrane (Fig. 9L; Amato et al., 2009). These discrepancies sug-gest that late Paleozoic and Mesozoic strata in the Canadian Arctic Islands did not receive sediment from the Arctic Alaska–Chukotka ter-rane, but sediment came only from Crockerland, the Pearya terrane, eastern Greenland, and the Laurentian craton. The southern margin of the Arctic Alaska–Chukotka terrane in Figure 10, which is the present-day eastern part of the ter-rane, was sutured to northwestern Laurentia during the Romanzof orogeny, suggesting it lay to the west of Crockerland and the Pearya terrane. These relationships imply that the Arc-tic Alaska–Chukotka terrane was not located alongside the Canadian Arctic Islands from Late Devonian to Cretaceous time (Fig. 10).
CONCLUSIONS
New provenance constraints indicate that Ellesmerian clastic wedge sandstone samples from the Imperial and Tuttle Formations in northern Yukon and Northwest Territories, northwestern Canada, contain ca. 360–390, 430–460, 530–680, and 1500–1600 Ma detrital zircons derived from allochthonous terranes that originated near the Caledonian and Timanian orogenic belts of northern Europe. Regional correlations suggest that exotic detrital zircons in Imperial and Tuttle Formation strata origi-nated from the Arctic Alaska–Chukotka terrane, Pearya terrane, the landmass of Crockerland,
Plate vector
Early and mid-Paleozoic orogeny
Terranes of Caledonian,Baltican, or Siberan affinity
Peri-Laurentian terranes
Ellesmerian sediment transport direction
Post-Ellesmerian transport of recycled clastic wedge material
Ellesmerian clastic wedge samples from this study
AAAA
CLCL
PTPT
EELLESMERIANLLESMERIAN
LLAURENTIAAURENTIA
BBALTICAALTICA
BBAR.AR.
AXAX
YTYT
OKOK
YRYR
15°N15°N
30°N30°N
45°N45°N
Post-360 MaPost-360 Maclastic wedge clastic wedge
recyclingrecycling
AANTLERNTLER
URALIAN SEAAA
CL
PT
ELLESMERIAN
LAURENTIA
BALTICA
BAR.
AX
YT
15°N
OK
YR
30°N
45°N
Innuitian hinterland realm
LATE DEVONIAN–EARLY MISSISSIPPIAN (ca. 360 Ma)
Post-360 Maclastic wedge
recycling
ANTLER
Figure 10. Late Devonian to early Mississippian (ca. 360 Ma) paleogeography (modifi ed from Colpron and Nelson, 2009) highlighting Ellesmerian and Antler orogenic development, inferred sediment dispersal patterns in northern Laurentia, and location of exotic terranes. Abbrevia-tions: AA—Arctic Alaska–Chukotka terrane, AX—Alexander terrane, Bar.—Barentsia, CL—Crockerland, OK—Okanagan subterrane, PT—Pearya terrane, YR—Yreka subterrane (including Trinity subterrane and Shoo Fly complex), YT—Yukon-Tanana terrane.
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1910 Geological Society of America Bulletin, November/December 2010
and Caledonides of eastern Greenland. Wide-spread Paleoproterozoic (ca. 1800–2000 Ma) detrital zircons in clastic wedge rocks were re-cycled from older Laurentian strata uplifted dur-ing regional deformation. These LA-ICP-MS results defi ne a robust detrital zircon provenance fi ngerprint for mid-Paleozoic foreland basin sediments that were originally characterized by smaller ID-TIMS and SHRIMP data sets.
Middle to late Mississippian miogeoclinal sandstones in Yukon demonstrate that exotic Caledonian and Baltican (Timanide) detrital zircons were cannibalized and recycled from clastic wedge strata into the continental mar-gin environment along northwestern Laurentia after Ellesmerian orogenesis. Triassic marine strata of the eastern Canadian Cordillera display ubiquitous ca. 360–390 and 430–680 Ma detri-tal zircon populations, indicating that recycled Ellesmerian clastic wedge sediment directly af-fected the source and composition of the north-ern Cordilleran miogeocline for >100 m.y.
Ellesmerian clastic wedge detrital zircon signatures correlate with provenance data from several tectonic elements now present in the North American Cordillera, such as the Yreka subterrane in the western United States and the Alexander terrane in southeastern Alaska and northwestern Canada. These data provide another line of evidence that some Cordilleran terranes originated near the Caledonian and Timanian orogens and traveled through the In-nuitan realm during early to mid-Paleozoic time.
The Arctic Alaska–Chukotka terrane was lo-cated to the west of Crockerland and the Pearya terrane along the ancestral northern margin of Laurentia from mid-Paleozoic to late Mesozoic time. Paleozoic and older rocks of the Arctic Alaska–Chukotka terrane were probably not a source for Triassic strata in the Canadian Arctic Islands region, implying that the terrane dur-ing the early Mesozoic was only juxtaposed against the North American autochthon in the Romanzof orogenic belt region of northeast-ern Alaska and northern Yukon. Regional de-trital zircon results may therefore preclude a pre-Cretaceous relationship between the Arctic Alaska–Chukotka terrane and the Canadian Arctic Islands, which should be considered in future models for Amer asian basin formation.
ACKNOWLEDGMENTS
This is a product of the Natural Resources Canada Geo-Mapping for Energy and Minerals Program, Earth Sciences Sector contribution 20090354. Detrital zircon analyses were supported by Natural Sciences and Engineering Research Council of Canada grants to J.K. Mortensen. The Yukon Geological Survey funded fi eld logistics and helicopter support for L.P. Beranek. Maurice Colpron provided electronic fi les for Figures 2, 4, and 10. Maurice Colpron, Jim Wright, Associate
Editor Margaret Thompson, and Science Editor Nancy Riggs provided thorough and constructive reviews that improved both the text and fi gures.
REFERENCES CITED
Åhäll, K.-I., and Connelly, J., 1998, Intermittent 1.53–1.13 Ga magmatism in western Baltica: Age constraints and cor-relations within a postulated supercontinent: Precam-brian Research, v. 92, p. 1–20, doi: 10.1016/S0301-9268(98)00064-3.
Åhäll, K.-I., Cornell, D.H., and Armstrong, R., 1998, Ion probe zircon dating of three metasedimentary units bordering the Oslo Rift: New constraints for early Mesoproterozoic growth of the Baltic Shield: Pre-cambrian Research, v. 87, p. 117–134, doi: 10.1016/S0301-9268(97)00059-4.
Amato, J.M., Toro, J., Miller, E.L., Gehrels, G.E., Farmer, G.L., Gottlieb, E.S., and Till, A.B., 2009, Late Proterozoic–Paleozoic evolution of the Arctic Alaska–Chukotka terrane based on U-Pb igneous and detrital zircon ages: Implications for Neoproterozoic paleogeo-graphic reconstructions: Geological Society of America Bulletin, v. 121, p. 1219–1235, doi: 10.1130/B26510.1.
Balashov, J.A., Tebenkov, A.M., Peucat, J.J., Ohta, Y., Larionov , A.N., and Sirostkin, A.N., 1996, Rb-Sr whole-rock and U-Pb zircon dating of the granitic-gabbro rocks from the Kalfjellet Subgroup, southwest Spits-bergen: Polar Research, v. 15, p. 167–181, doi: 10.1111/j.1751-8369.1996.tb00467.x.
Bazard, D.R., Butler, R.F., Gehrels, G.E., and Soja, C.M., 1995, Early Devonian paleomagnetic data from the Lower Devonian Karheen Formation suggest Laurentia-Baltica connection for the Alexander terrane: Geology, v. 23, p. 707–710, doi: 10.1130/0091-7613(1995)023<0707:EDPDFT>2.3.CO;2.
Beranek, L.P., Link, P.K., and Fanning, C.M., 2006, Mio-cene to Holocene landscape evolution of the western Snake River Plain region, Idaho: Using the SHRIMP detrital zircon provenance record to track eastward migration of the Yellowstone hotspot: Geological So-ciety of America Bulletin, v. 118, p. 1027–1050, doi: 10.1130/B25896.1.
Beranek, L.P., Mortensen, J.K., Orchard, M.J., and Ullrich , T., 2010, Provenance of North American Triassic strata from west-central and southeastern Yukon: Cor-relations with coeval strata in the Western Canada sedimentary basin and Canadian Arctic Islands: Cana-dian Journal of Earth Sciences, v. 47, p. 53–73, doi: 10.1139/E09-065.
Bjornerud, M., 1989, Structural transects in northwestern Ellesmere Island, Canadian Arctic Archipelago, in Current Research 1989-1G: Ottawa, Geological Sur-vey of Canada, p. 125–131.
Blodgett, R.B., Rohr, D.M., and Boucot, A.J., 2002, Paleo-zoic links among some Alaskan accreted terranes and Siberia based on megafossils, in Miller, E.L., Grantz, A., and Klemperer, S., eds., Tectonic Evolution of the Bering Shelf–Chukchi Sea–Arctic Margin and Adja-cent Landmasses: Geological Society of America Spe-cial Paper 360, p. 273–290.
Boghossian, N.D., Patchett, P.J., Ross, G.M., and Gehrels , G.E., 1996, Nd isotopes and the source of sediments in the miogeocline of the Canadian Cordillera: The Journal of Geology, v. 104, p. 259–277, doi: 10.1086/629824.
Braman, D.R., and Hills, L.V., 1992, Upper Devonian and Lower Carboniferous miospores, Western District of Mackenzie and Yukon Territory, Canada: Paleonto-graphica Canadiana, v. 8, 97 p.
Chang, S., Vervoort, J.D., McClelland, W.C., and Knaack, C., 2006, U-Pb dating of zircon by LA-ICP-MS: Geo-chemistry, Geophysics, Geosystems, v. 7, p. Q05009, doi: 10.1029/2005GC001100.
Colpron, M., and Nelson, J.L., 2009, A Palaeozoic North-west Passage: Incursion of Caledonian, Baltican and Siberian terranes into eastern Panthalassa, and the early evolution of the North American Cordillera, in Cawood, P.A., and Kröner, A., eds., Earth Accretionary Systems through Space and Time: Geological Society of London Special Publication 318, p. 273–307.
Colpron, M., Nelson, J.L., and Murphy, D.C., 2007, North-ern Cordilleran terranes and their interactions through time: GSA Today, v. 17, p. 4–10, doi: 10.1130/GSAT01704-5A.1.
Dumoulin, J.A., Harris, A.G., Bradley, D.C., and de Freitas, T.A., 2000, Facies patterns and conodont biogeography in Arctic Alaska and the Canadian Arctic Islands: Evi-dence against juxtaposition of these areas during early Paleozoic time: Polarforschung, v. 68, p. 257–266.
Embry, A.F., 1990, Geological and geophysical evidence in support of the hypothesis of anticlockwise rotation of northern Alaska: Marine Geology, v. 93, p. 317–329, doi: 10.1016/0025-3227(90)90090-7.
Embry, A.F., 1992, Crockerland—The northwest source area for the Sverdrup basin, Canadian Arctic Islands, in Vorren , T.O., et al., eds., Arctic Geology and Petro-leum Potential: Norwegian Petroleum Society Special Publication 2, p. 205–216.
Fraser, T.A., and Allen, T.L., 2007, Field investigations of the Upper Devonian to Lower Carboniferous Tuttle Formation, eastern Richardson Mountains, Yukon, in Emond, D.S., Lewis, L.L., and Weston, L.H., eds., Yukon Exploration and Geology 2006: Whitehorse, Yukon, Yukon Geological Survey, p. 157–173.
Garzione, C.N., Patchett, P.J., Ross, G.M., and Nelson, J.L., 1997, Provenance of Paleozoic sedimentary rocks in the Canadian Cordilleran miogeocline: A Nd iso topic study: Canadian Journal of Earth Sciences, v. 34, p. 1603–1618, doi: 10.1139/e17-129.
Gee, D.G., and Pease, V., eds., 2004, The Neoproterozoic Timanide Orogen of Eastern Baltica: Geological Soci-ety of London Memoir 30, 248 p.
Gehrels, G.E., 1990, Late Proterozoic–Cambrian metamor-phic basement to the Alexander terrane on Long and Dall Islands, southeastern Alaska: Geological Society of America Bulletin, v. 102, p. 760–767, doi: 10.1130/0016-7606(1990)102<0760:LPCMBO>2.3.CO;2.
Gehrels, G.E., and Ross, G.M., 1998, Detrital zircon geo-chronology of Neoproterozoic to Permian miogeocli-nal strata in British Columbia and Alberta: Canadian Journal of Earth Sciences, v. 35, p. 1380–1401, doi: 10.1139/cjes-35-12-1380.
Gehrels, G.E., Saleeby, J.B., and Berg, H.C., 1987, Geol-ogy of Annette, Gravina, and Duke Islands, southeast-ern Alaska: Canadian Journal of Earth Sciences, v. 24, p. 866–881.
Gehrels, G.E., Butler, R.F., and Bazard, D.R., 1996, Detrital zircon geochronology of the Alexander terrane, south-eastern Alaska: Geological Society of America Bulletin, v. 108, p. 722–734, doi: 10.1130/0016-7606(1996)108<0722:DZGOTA>2.3.CO;2.
Gehrels, G.E., Johnsson, M.J., and Howell, D.G., 1999, Detrital zircon geochronology of the Adams Argil-lite and Nation River Formation, east-central Alaska, U.S.A.: Journal of Sedimentary Research, v. 69, p. 135–144.
Gordey, S.P., and Anderson, R.G., 1993, Evolution of the Northern Cordilleran Miogeocline, Nahanni Map Area (105I), Yukon and Northwest Territories: Geological Survey of Canada Memoir 428, 214 p.
Gordey, S.P., Abbott, J.G., and Orchard, M.J., 1982, Devo-nian-Mississippian (Earn Group) and younger strata in east-central Yukon, in Current Research, Part B: Geo-logical Survey of Canada Paper 82–1B, p. 93–100.
Gordey, S.P., Geldsetzer, H.H.J., Morrow, D.W., Bamber, E.W., Henderson, C.M., Richards, B.C., McGugan, A., Gibson, D.W., and Poulton, T.P., 1991, Upper Devo-nian to Middle Jurassic assemblages: Part A. Ancestral North America, in Gabrielse, H., and Yorath, C.J., eds., Geology of the Cordilleran Orogen in Canada: Boul-der, Colorado, Geological Society of America, The Geol ogy of North America, v. G-2, p. 221–328.
Gradstein, F.M., Ogg, J.G., and Smith, A.G., eds., 2004, A Geologic time scale 2004: Cambridge, UK, Cambridge University Press, 589 p.
Grove, M., Gehrels, G.E., Cotkin, S.J., Wright, J.E., and Zou, H., 2008, Non-Laurentian cratonal provenance of Late Ordovician eastern Klamath blueschists and a link to the Alexander terrane, in Wright, J.E., and Shervais, J.W., eds., Ophiolites, Arcs, and Batholiths: A Tribute to Cliff Hopson: Geological Society of America Spe-cial Paper 438, p. 223–250.
on October 27, 2010gsabulletin.gsapubs.orgDownloaded from
Detrital zircon geochronology of the western Ellesmerian clastic wedge, northwestern Canada
Geological Society of America Bulletin, November/December 2010 1911
Hadlari, T., Tyloski, S.A., Lemieux, Y., Zantvoort, W.G., and Catuneanu, O., 2009, Slope and submarine fan turbi-dite facies of the Upper Devonian Imperial Formation, northern Mackenzie Mountains, Northwest Territo-ries: Bulletin of Canadian Petroleum Geology, v. 57, p. 192–208, doi: 10.2113/gscpgbull.57.2.192.
Hellman, F.J., Gee, D.G., Johansson, Å., and Witt-Nilsson, P., 1997, Single-zircon Pb evaporation geochronol-ogy constrains basement-cover relationships in the Lower Hecla Hoek complex of northern Ny Friesland, Svalbard: Chemical Geology, v. 137, p. 117–134, doi: 10.1016/S0009-2541(96)00152-0.
Hills, L.V., and Braman, D.R., 1978, Sedimentary structures of the Imperial Formation, in Embry, A.F., compiler, Display Summaries, Core and Field Sample Confer-ence: Calgary, Alberta, Canadian Society of Petroleum Geologists, p. 35–37.
Hoffman, P.F., 1988, United plates of America, the birth of a craton: Early Proterozoic assembly and growth of Laurentia: Annual Review of Earth and Planetary Sciences, v. 16, p. 543–603, doi: 10.1146/annurev.ea.16.050188.002551.
Jackson, S.E., Pearson, N.J., Griffi n, W.L., and Belousova, E.A., 2004, The application of laser ablation–inductively coupled plasma–mass spectrometry to in situ U-Pb zircon geochronology: Chemical Geology, v. 211, p. 47–69, doi: 10.1016/j.chemgeo.2004.06.017.
Knudsen, T.-L., Andersen, T., Whitehouse, M.J., and Vestin , J., 1997, Detrital zircon ages from southern Nor-way—Implications for the Proterozoic evolution of the southwestern Baltic Shield: Contributions to Min-eralogy and Petrology, v. 130, p. 47–58, doi: 10.1007/s004100050348.
Lane, L.S., 1997, Canada Basin, Arctic Ocean: Evidence against a rotational origin: Tectonics, v. 16, p. 363–387, doi: 10.1029/97TC00432.
Lane, L.S., 2007, Devonian-Carboniferous paleogeography and orogenesis, northern Yukon and adjacent Arctic Alaska: Canadian Journal of Earth Sciences, v. 44, p. 679–694, doi: 10.1139/E06-131.
Lawver, L.A., and Scotese, C.R., 1990, A review of tec-tonic models for the evolution of the Canada Basin, in Grantz, A., Johnson, L., and Sweeney, J.F., eds., The Arctic Ocean Region: Boulder, Colorado, Geological Society of America, The Geology of North America, v. L, p. 593–618.
Lawver, L.A., Grantz, A., and Gahagan, L.M., 2002, Plate kine matic evolution of the present Arctic region since the Ordovician, in Miller, E.L., Grantz, A., and Klemperer , S.L., eds., Tectonic Evolution of the Bering Shelf–Chukchi Sea–Arctic Margin and Adjacent Land-masses: Geological Society of America Special Paper 360, p. 333–358.
Link, P.K., Fanning, C.M., and Beranek, L.P., 2005, Reli-ability and longitudinal change of detrital-zircon age spectra in the Snake River system, Idaho and Wyo-ming: An example of reproducing the bumpy bar-code: Sedimentary Geology, v. 182, p. 101–142, doi: 10.1016/j.sedgeo.2005.07.012.
Lutchman, M., 1977, Mississippian clastic wedge in Lower Mackenzie Energy Corridor Study: Geological Com-ponent: Calgary, Alberta, Geochem Laboratories Ltd. and AGAT Consultants Ltd., p. M1–M10.
Mazur, S., Czerny, J., Majka, J., Manecki, M., Holm, D., Smyrak, A., and Wypych, A., 2009, A strike-slip boundary in Wedel Jarlsberg Land, Svalbard, and its bearing on correlations of SW Spitsbergen with the Pearya terrane and Timanide belt: Journal of the Geo-logical Society of London, v. 166, p. 529–544, doi: 10.1144/0016-76492008-106.
McClelland, W.C., Schmidt, J.M., and Till, A.B., 2006, New U-Pb SHRIMP ages from Devonian felsic volcanic and Proterozoic plutonic rocks of the southern Brooks Range, Alaska: Geological Society of America Ab-stracts with Programs, v. 38, no. 5, p. 12.
McNicoll, V.J., Harrison, J.C., Trettin, H.P., and Thorsteins-son, R., 1995, Provenance of the Devonian clastic wedge of Arctic Canada: Evidence provided by detrital zircon ages, in Dorobek, S.L., and Ross, G.M., eds., Stratigraphic Evolution of Foreland Basins: Society of Economic Paleontologists and Mineralogists Special Publication 52, p. 77–93.
Miller, E.L., Toro, J., Gehrels, G.E., Amato, J.M., Prokopiev, A., Tuchkova, M.I., Akinin, V.V., Dumitru, T.A., Moore, T.E., and Cecile, M.P., 2006, New insights into Arctic paleogeography and tectonics from U-Pb detri-tal zircon geochronology: Tectonics, v. 25, p. 1–19.
Moore, T.E., Wallace, W.K., Bird, K.J., Karl, S.M., Mull, C.G., and Dillon, J.T., 1994, Geology of northern Alaska, in Plafker, G., and Berg, H.C., eds., The Geol-ogy of Alaska: Boulder, Colorado, Geological Society of America, The Geology of North America, v. G-1, p. 49–140.
Moore, T.E., Potter, C.J., O’Sullivan, P.B., and Aleini-koff, J.N., 2007, Evidence from detrital zircon U-Pb analysis for suturing of pre-Mississippian terranes in Arctic Alaska: Eos (Transactions, American Geophysi-cal Union), v. 88, Fall Meeting supplement, abstract T13D–1570.
Mortensen, J.K., and Bell, R.T., 1991, U-Pb zircon and titanite geochronology of the Mount Sedgewick pluton , northern Yukon Territory, in Radiogenic Age and Isotope Studies, Report 4: Geological Survey of Canada Paper 90–2, p. 19–24.
Orchard, M.J., 2006, Late Paleozoic to Triassic conodont faunas of Yukon and northern British Columbia and implications for the Yukon-Tanana terrane, in Colpron, M., and Nelson, J.L., eds., Paleozoic Evolution and Metallogeny of Pericratonic Terranes at the Ancient Pacifi c Margin of North America: Geological Associa-tion of Canada Special Paper 45, p. 229–260.
Osadetz, K.G., MacLean, B.C., Morrow, D.W., Dixon, J., and Hannigan, P.K., 2005, Petroleum Resource Assess-ment, Peel Plateau and Plain, Yukon Territory, Canada: Yukon Geological Survey Open File 2005–3, and Geo-logical Survey of Canada Open File 4841, 76 p.
Pallister, J.S., Budahn, J.R., and Murchey, B.L., 1989, Pillow basalts of the Angayucham terrane: Oceanic plateau and island crust accreted to the Brooks Range: Journal of Geophysical Research, v. 94, p. 15,901–15,923, doi: 10.1029/JB094iB11p15901.
Patchett, P.J., Roth, M.A., Canale, B.S., de Freitas, T.A., Harrison, J.C., Embry, A.F., and Ross, G.M., 1999, Nd isotopes, geochemistry, and constraints on sources of sediments in the Franklinian mobile belt, Arctic Canada: Geological Society of America Bulletin, v. 111, p. 578–589, doi: 10.1130/0016-7606(1999)111<0578:NIGACO>2.3.CO;2.
Patchett, P.J., Embry, A.F., Ross, G.M., Beauchamp, B., Harrison, J.C., Mayr, U., Isachsen, C.E., Rosenberg, E.J., and Spence, G.O., 2004, Sedimentary cover of the Canadian Shield through Mesozoic time refl ected by Nd isotopic and geochemical results for the Sverdrup basin, Arctic Canada: The Journal of Geology, v. 112, p. 39–57, doi: 10.1086/379691.
Patrick, B.E., and McClelland, W.C., 1995, Late Proterozoic granitic magmatism on Seward Peninsula and a Barent-sian origin for Arctic Alaska-Chukotka: Geology, v. 23, p. 81–84, doi: 10.1130/0091-7613(1995)023<0081:LPGMOS>2.3.CO;2.
Pugh, D.C., 1983, Pre-Mesozoic Geology in the Subsurface of Peel River Map-Area, Yukon Territory and District of Mackenzie: Geological Survey of Canada Memoir 401, 61 p.
Rainbird, R.H., Heaman, L.H., and Young, G., 1992, Sam-pling Laurentia: Detrital zircon geochronology offers evidence for an extensive Neoproterozoic river sys-tem originating from the Grenville orogen: Geology, v. 20, p. 351–354, doi: 10.1130/0091-7613(1992)020<0351:SLDZGO>2.3.CO;2.
Raterman, N.S., McClelland, W.C., and Presnell, R.D., 2006, Geochronology and lithogeochemistry of vol-canic rocks of the Ambler district, southern Brooks Range, Alaska: Geological Society of America Ab-stracts with Programs, v. 38, no. 5, p. 69.
Ross, G.M., and Villeneuve, M., 2003, Provenance of the Mesoproterozoic (1.45 Ga) Belt basin (western North America): Another piece in the pre-Rodinia paleogeo-graphic puzzle: Geological Society of America Bulle-tin, v. 115, p. 1191–1217, doi: 10.1130/B25209.1.
Ross, G.M., Gehrels, G.E., and Patchett, P.J., 1997, Prove-nance of Triassic strata in the Cordilleran miogeocline, western Canada: Bulletin of Canadian Petroleum Geol-ogy, v. 45, p. 461–473.
Ross, G.M., Patchett, P.J., Hamilton, M., Heaman, L., De-Celles, P.G., Rosenberg, E., and Giovanni, M.K., 2005, Evolution of the Cordilleran orogen (southwestern Al-berta, Canada) inferred from detrital mineral geochro-nology, geochemistry, and Nd isotopes in the foreland basin: Geological Society of America Bulletin, v. 117, p. 747–763, doi: 10.1130/B25564.1.
Sircombe, K., 2000, The usefulness and limitations of binned frequency histograms and probability density distributions for displaying absolute age data, in Radio-genic Age and Isotope Studies, Report 13: Geological Survey of Canada Paper 2000–F2, p. 1–11.
Soja, C.M., 1994, Signifi cance of Silurian stromatolite-sphincto zoan reefs: Geology, v. 22, p. 355–358, doi: 10.1130/0091-7613(1994)022<0355:SOSSSR>2.3.CO;2.
Stephens, M.B., and Gee, D.G., 1985, A tectonic model for the evolution of the eugeoclinal terranes in the central Scandinavian Caledonides, in Gee, D.G., and Sturt, B.A., eds., The Caledonide Orogen—Scandinavia and Related Areas: Chichester, UK, Wiley, p. 953–978.
Thorsteinsson, R., and Tozer, E.T., 1970, Geology of the Arctic Archipelago, in Douglas, R.J.W, ed., Geology and Economic Minerals of Canada: Geological Survey of Canada Economic Geology Report 1, p. 547–590.
Till, A.B., Aleinikoff, J.N., Amato, J.M., and Harris, A.G., 2006, New paleontologic and geochronologic protolith ages for the paleo-continental margin of Arctic Alaska: Geological Society of America Abstracts with Pro-grams, v. 38, no. 5, p. 13.
Toro, J., Toro, F.C., Bird, K.J., and Harrison, C., 2004, The Arctic Alaska-Canada connection revisited: Geologi-cal Society of America Abstracts with Programs, v. 36, no. 5, p. 22.
Trettin, H.P., 1987, Pearya: A composite terrane with Cale-donian affi nities in northern Ellesmere Island: Cana-dian Journal of Earth Sciences, v. 24, p. 224–245, doi: 10.1139/e87-025.
Trettin, H.P., ed., 1991, Geology of the Innuitian Orogen and Arctic Platform of Canada and Greenland: Geological Survey of Canada, Geology of Canada, v. 3, 569 p.
Trettin, H.P., Parrish, R., and Loveridge, W.D., 1987, U-Pb age determinations on Proterozoic to Devonian rocks from northern Ellesmere Island, Arctic Canada: Cana-dian Journal of Earth Sciences, v. 24, p. 246–256, doi: 10.1139/e87-026.
Trettin, H.P., Okulitch, A.V., Harrison, J.C., Brent, T.A., Fox, F.G., Packard, J.J., Smith, G.P., and Zolnai, A.I., 1991, Silurian–early Carboniferous deformational phases and associated metamorphism and plutonism, Arctic Islands, in Trettin, H.P., ed., Geology of the Innuitian Orogen and Arctic Platform of Canada and Greenland: Geological Survey of Canada, Geology of Canada, v. 3, p. 293–341.
Van Achterbergh, E., Ryan, C.G., Jackson, S.E., and Griffi n, W.L., 2001, Data reduction software for LA-ICP-MS, in Sylvester, P.J., ed., Laser Ablation-ICP-Mass Spec-trometry in the Earth Sciences: Principles and Applica-tions: Ottawa, Canada, Mineralogical Association of Canada (MAC) Short Course Series, v. 42, p. 239–243.
Van Schmus, W.R., Bickford, M.E., Anderson, J.L., Bender, E.E., Anderson, R.R., Bauer, P.W., Robertson, J.M., Bowring, S.A., Condie, K.C., Denison, R.E., Gilbert, M.C., Grambling, J.A., Mawer, C.K., Shearer, C.K., Hinje, W.J., Karlstrom, K.E., Kisvarsanyi, E.B., Lidiak , E.G., Reed, J.C., Jr., Sims, P.K., Tweto, O., Silver, L.T., Treves, S.B., Williams, M.L., and Wooden, J.L., 1993, Transcontinental Proterozoic provinces, in Reed, J.C., Jr., et al., eds., Precambrian Conterminous U.S.: Boul-der, Colorado, Geological Society of America, The Geol ogy of North America, v. C-2, p. 171–334.
Watt, G.R., Kinny, P.D., and Friderichsen, J.D., 2000, U-Pb geochronology of Neoproterozoic and Cale-donian tectono thermal events in the East Greenland Caledonides : Journal of the Geological Society of London, v. 157, p. 1031–1048.
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