Thermochronology of the Yukon-Tanana Terrane, West-Central Yukon:                     Evidence for Jurassic Extension and Exhumation in the Northern Canadian                     Cordillera

Knight, Eleanor; Schneider, David; Ryan, J J

doi:10.1086/670721

Cited by 23 publications

(44 citation statements)

References 52 publications

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“…Continued convergence of these two plates resulted in northeast propagation of a deformation front as evinced by metamorphism in the Late Jurassic Lower Schist unit in the northwestern Selwyn basin [ Mair et al ., ]. Widespread crustal extension following tectonic thickening during accretion of Yukon‐Tanana terrane occurred in the hinterland by the Aptian/Albian, as revealed by the circa 115–100 Ma 40 Ar/ 39 Ar and (U‐Th)/He cooling ages common in the footwall of normal faults [ Dusel‐Bacon et al ., ; Mair et al ., ; Knight et al ., ]. This crustal extension is thought to drive shearing in thrust sheets in the Selwyn Basin [ Mair et al ., ].…”

Section: Discussionmentioning

confidence: 99%

Zircon (U‐Th)/He thermochronology of Neoproterozoic strata from the Mackenzie Mountains, Canada: Implications for the Phanerozoic exhumation and deformation history of the northern Canadian Cordillera

et al. 2016

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Sedimentary strata of the Neoproterozoic Mackenzie Mountains Supergroup (MMSG) and Windermere Supergroup (WSG) occupy the cores of anticlines in the Mackenzie Mountains of the Canadian Cordilleran Foreland Belt. Stratigraphic and structural evidence suggest that these rocks have undergone several episodes of burial and unroofing relatively intact. We report single‐grain detrital muscovite 40Ar/39Ar and zircon (U‐Th)/He (ZHe) data from a suite of samples across the fold‐thrust belt and the Neoproterozoic stratigraphic record. The strata have not reached high enough temperatures to reset the muscovite 40Ar/39Ar system, and instead our detrital muscovite data refine Tonian‐Cryogenian depositional ages. Single‐crystal ZHe dates range from 432 ± 35 to 46 ± 4 Ma, indicating that MMSG and WSG strata have not been heated sufficiently to fully reset the ZHe system. These factors make the Neoproterozoic strata an attractive natural laboratory to test the utility of the zircon radiation damage and annealing model on the quantification of thermal histories from detrital zircon populations that have accumulated radiation damage over long geologic timescales. Thermal modeling reveals that (1) a substantial sedimentary package was deposited following the Devonian and removed during Permo‐Triassic cooling, and (2) the Cordilleran deformation front propagated through the study area from the Albian to the Paleocene, with a moderate increase in cooling rates between 75–67 Ma in the southwest and 60–55 Ma at the deformation front. Ultimately, relationships between radiation damage and helium diffusion kinetics in zircon explain substantial ZHe date dispersion and elucidate the temperature‐time history of the northern Canadian Cordillera.

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Section: Discussionmentioning

confidence: 99%

Zircon (U‐Th)/He thermochronology of Neoproterozoic strata from the Mackenzie Mountains, Canada: Implications for the Phanerozoic exhumation and deformation history of the northern Canadian Cordillera

et al. 2016

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“…West of the Cretaceous domain, across the Australia Creek fault (Staples et al, 2013), Yukon-Tanana terrane rocks were transposed and metamorphosed in the Late Permian to Early Triassic and in the Early Jurassic Beranek and Mortensen, 2011;Fig. 2) before they were exhumed to upper crustal levels in the Early to Middle Jurassic (Johnston et al, 1996;Dusel-Bacon et al, 2002;Berman et al, 2007). Southeast of the Cretaceous domain, across the Stewart River normal fault, are sub-greenschist-facies, weakly deformed to undeformed Devonian and Mississippian volcanic and plutonic rocks that record Paleozoic and Mesozoic 40 Ar/ 39 Ar cooling ages (Knight et al, 2013). Both the Permo-Jurassic metamorphic domain to the west and the Devono-Mississippian rocks to the southeast were presumably the suprastructural "lid" from beneath which the Cretaceous metamorphic domain (essentially a core complex) was exhumed along the Australia Creek and Stewart River faults, respectively, in the mid-Cretaceous (Staples et al, 2013).…”

Section: Geologic Settingmentioning

confidence: 99%

“…This Early Jurassic burial and metamorphism followed, or was partly contemporaneous with, the emplacement of Early Jurassic (ca. 205-197 Ma;Tafti, 2005;Hood, 2012;Knight et al, 2013) land et al, 2002;Tafti, 2005). Widespread Early Jurassic K-Ar and 40 Ar/ 39 Ar ages in this same domain west of the Finlayson Lake district are interpreted to record either cooling and exhumation associated with this contraction (Dusel-Bacon et al, 2002), or exhumation accommodated by a shift to extensional tectonics Knight et al, 2013).…”

Section: Revealing a Younger More Protracted Metamorphismmentioning

confidence: 99%

“…Geochronologic investigations in the north-central part of the Yukon-Tanana terrane in Yukon indicate that the main episode of ductile deformation and amphibolite-facies metamorphism occurred in the Permo-Triassic Beranek and Mortensen, 2011). K-Ar and 40 Ar/ 39 Ar data from greenschist-and amphibolite-facies rocks of the Yukon-Tanana terrane in the Yukon and Alaskan Cordillera (referred to herein as "northern Cordillera") yield Early to Middle Jurassic cooling ages (Hansen et al, 1991;Hunt and Roddick, 1992;Stevens et al, 1993;Johnston et al, 1996;Gordey et al, 1998;Dusel-Bacon et al, 2002;Knight et al, 2013) that are interpreted to record widespread regional uplift and exhumation (Johnston et al, 1996;Berman et al, 2007;Beranek and Mortensen, 2011). The timing of such events contrasts with that documented in the southeastern Canadian Cordillera where deformation and metamorphism related to accretion of the peri-Laurentian terranes (Quesnel and Stikine terranes) and westward underthrusting of the North American plate apparently occurred in the Early Jurassic through early Paleogene (Evenchick et al, 2007, and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Middle Jurassic to earliest Cretaceous mid-crustal tectono-metamorphism in the northern Canadian Cordillera: Recording foreland-directed migration of an orogenic front

Staples

Murphy

Gibson

et al. 2014

Geological Society of America Bulletin

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In situ sensitive high-resolution ion microprobe monazite geochronology and garnet isopleth thermobarometry reveal a previously unrecognized Middle Jurassic to earliest Cretaceous mid-crustal tectonometamorphic event in the eastern part of the Yukon-Tanana terrane (Finlayson Lake district, southeast Yukon) in the northern Canadian Cordillera. Intersection of garnet end-member compositional isopleths applied to single-stage, growth-zoned garnet records progressive garnet growth from 550 °C and 6.1-6.6 kbar to 600 °C and 7.5 kbar. Monazite textures, chemical zoning, and in situ U-Pb ages record a single protracted episode of monazite growth from ca. 169 to 142 Ma coeval with the development of transposition fabrics and the late stages of garnet growth. This event post-dates widespread Early Jurassic exhumation of Yukon-Tanana terrane rocks west of the Tintina fault in west-central Yukon, which were previously ductily deformed and metamorphosed in the Permo-Triassic. The lack of evidence for Permo-Triassic ductile deformation and high-grade metamorphism within the Finlayson Lake district, and its position east of the Permian arc center and west of Permian blueschists and eclogites, suggests this eastern part of the terrane occupied the cool forearc at this time. These data indicate younger, more protracted mid-crustal orogenesis in the northern Cordillera than was previously recognized, with deformation and metamorphism migrating toward the foreland and downwards in the Middle Jurassic to Early Cretaceous, in part contemporaneous with and analogous to that in the southeastern Canadian Cordillera.

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“…Published thermochronology studies of central Yukon (Betsi et al 2012;Knight et al 2013;Joyce et al 2015;Moher et al 2016) indicate that the Klondike Plateau cooled through medium to low temperature (400-300°C) for the 40 Ar/ 39 Ar system (Knight et al 2013;Joyce et al 2015) in the Early Jurassic to Early Cretaceous. The plateau cooled through the low-temperature (U-Th)/He geochronometers (Betsi et al 2012;Moher et al 2016) in apatite and zircon (<180°C) in the Middle Jurassic to Late Cretaceous (locally) and to the Paleocene in general.…”

Section: Thermochronological Constraintsmentioning

confidence: 99%

Landscape antiquity and Cenozoic drainage development of southern Yukon, through restoration modeling of the Tintina Fault

2017

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The impact of Tintina Fault displacement on the development of the Yukon River and drainage basins of central Yukon is investigated through geophysical and hydrological modeling of digital terrain model data. Regional geological evidence suggests that the age of the planation of the Klondike Plateau is at least Late Cretaceous, rather than Neogene as previously assumed, and that surprisingly there has been little net incision in the region since the late Mesozoic. The Tintina Fault has been previously interpreted to have experienced ϳ430 km of dextral displacement, primarily during the Eocene. However, the alignment of river channels across the fault at specific displacements, coupled with recent seismic events and related fault activity, suggests that the fault may have moved in stages over a longer time span. Topographic restoration and hydrological models show that the drainage of the Yukon River northwestward into Alaska via the ancestral Kwikhpak River was only possible at restored displacements of up to ϳ50-55 km on the Tintina Fault. We interpret the published drainage reversals convincingly attributed to the effects of Pliocene glaciation as an overprint on earlier Yukon River reversals attributed to tectonic displacements along the Tintina Fault. At restored displacements between 230 and 430 km, our models illustrate that paleo-Yukon River drainage may have flowed eastward into the continental interior via an ancestral Liard River. The revised drainage evolution has wide-reaching implications for surficial geology deposits, the flow direction and channel geometries of the region's ancient rivers, and importantly, for exploration of placer gold deposits.Résumé : L'incidence du déplacement le long de la faille de Tintina sur l'évolution du fleuve Yukon et des bassins hydrographiques dans le centre du Yukon est examinée par modélisation géophysique et hydrologique de données de modèles numériques du relief. Les observations géologiques régionales donnent à penser que l'aplanissement du plateau du Klondike est au minimum d'âge crétacé tardif plutôt que néogène, comme cela était présumé auparavant, et que, étonnement, il y a eu peu d'érosion verticale nette dans la région depuis le Mésozoïque tardif. L'interprétation d'un déplacement dextre de ϳ430 km le long de la faille de Tintina, principalement durant l'Éocène, a déjà été proposée. Cependant, l'alignement des chenaux de rivières traversant la faille à des déplacements précis, jumelé à des évènements sismiques récents et à l'activité associée le long de la faille, indiquerait que le déplacement le long de cette dernière se serait opéré en différentes phases sur une longue période. La reconstitution topographique et des modèles hydrologiques montrent que l'écoulement du fleuve Yukon vers le nord-ouest jusqu'en Alaska par la rivière Kwikhpak ancestrale n'aurait été possible que pour des déplacements reconstitués de jusqu'à ϳ50-55 km le long de la faille de Tintina. Nous interprétons les inversions de l'écoulement publiées attribuées de manière convaincante a...

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Thermochronology of the Yukon-Tanana Terrane, West-Central Yukon: Evidence for Jurassic Extension and Exhumation in the Northern Canadian Cordillera

Cited by 23 publications

References 52 publications

Zircon (U‐Th)/He thermochronology of Neoproterozoic strata from the Mackenzie Mountains, Canada: Implications for the Phanerozoic exhumation and deformation history of the northern Canadian Cordillera

Zircon (U‐Th)/He thermochronology of Neoproterozoic strata from the Mackenzie Mountains, Canada: Implications for the Phanerozoic exhumation and deformation history of the northern Canadian Cordillera

Middle Jurassic to earliest Cretaceous mid-crustal tectono-metamorphism in the northern Canadian Cordillera: Recording foreland-directed migration of an orogenic front

Landscape antiquity and Cenozoic drainage development of southern Yukon, through restoration modeling of the Tintina Fault

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