Paleoproterozoic collisional orogen beneath the western Canada sedimentary basin imaged by Lithoprobe crustal seismic-reflection data

Ross, Gerald M.; Milkereit, B.; Eaton, David W.; White, Don; Kanasewich, E. R.; Burianyk, Michael

doi:10.1130/0091-7613(1995)023<0195:pcobtw>2.3.co;2

Cited by 72 publications

(36 citation statements)

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“…Nor does the character of the Big Sky orogen eliminate the possibility that the Vulcan structure is also a Proterozoic collision orogen. Both the Medicine Hat block and the Vulcan structure appear to have been tectonically active between 1.7 and 1.85 Ga, as revealed by crustal xenoliths and basement rocks from deep drill cores (Lemieux et al, 2000;Ross et al, 1995, and the granitoids of the Rimbey belt north of the Vulcan structure are similar in age and arc-character to juvenile plutonic rocks we suggest lie just north of the Big Sky orogen . If the Big Sky orogen was a broad accretionary orogen, comparable in across-strike width to the Mesozoic Cordillera of western Canada (see also Ross, 2002), it may have ranged from a foreland along Giletti's line, across a metamorphic belt at the collisional suture in the northern Wyoming province, to a series of accreted terranes that could include the Medicine Hat block and remaining Hearne province, with convergent belts both inboard and outboard of each collider.…”

Section: The Great Falls Tectonic Zone and The Northern Boundary Of Tmentioning

confidence: 84%

Advances in the geology of the Tobacco Root Mountains, Montana, and their implications for the history of the northern Wyoming province

Harms

Brady²,

Burger³

et al. 2004

Precambrian Geology of the Tobacco Root Mountains, Montana

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Integrated studies by Keck Geology Consortium participants have generated many new insights into the Precambrian geology of the Tobacco Root Mountains.We have clarifi ed the tectonic setting and origin of two suites of metamorphic rocks: (1) a quartzofeldspathic gneiss complex with associated metasupracrustal rocks (the combined Indian Creek and Pony-Middle Mountain Metamorphic Suites) that originated in a continental arc setting between 3.35 and 3.2 Ga with subsequent sedimentation and (2) mafi c metavolcanic rocks with intercalated metasedimentary rocks (the Spuhler Peak Metamorphic Suite) from a suprasubduction zone ophiolite or backarc basin possibly of Proterozoic age. A poorly preserved metamorphic event at 2.45 Ga affected the former but not the latter, as did the intrusion of rift-related mafi c dikes and sills at 2.06 Ga. Both suites were amalgamated, metamorphosed to at least upper amphibolite facies, subjected to simple shear strain and folded into map-and outcrop-scale sheath folds, and tectonically unroofed during the period 1.78 to 1.71 Ga. We name this event the Big Sky orogeny.The Proterozoic geology of the Tobacco Root Mountains can be integrated with coeval features of the geology of the northern Wyoming province to outline a northeast-trending, southeast-vergent belt as the Big Sky orogen. The Big Sky orogen consists of a metamorphic hinterland fl anked to the southeast by a foreland of discrete ductile shear zones cutting older basement, and to the northwest by arc-related metaplutonic bodies and the trace of a fossil subduction zone in the upper mantle. Archean blocks to the north of the Big Sky orogen may have been accreted as allochthonous terranes during collision and convergence.The remarkable synchroneity of collision along the Big Sky orogen with tectonism in the Trans-Hudson orogen along the eastern margin of the Wyoming province and in the Cheyenne belt to the south of the province raise profound but unanswered questions about the process by which the Wyoming province was added to the rest of the ancestral North American craton.

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Section: The Great Falls Tectonic Zone and The Northern Boundary Of Tmentioning

confidence: 84%

Advances in the geology of the Tobacco Root Mountains, Montana, and their implications for the history of the northern Wyoming province

Harms

Brady²,

Burger³

et al. 2004

Precambrian Geology of the Tobacco Root Mountains, Montana

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“…However, arc magmatism and deformation of about the same age or slightly older as in the LGB are found in the Taltson-Thelon magmatic zone in the Western part of the Canadian Shield (Bostock & van Breemen, 1994;Plint & McDonough, 1995;Ross et al, 1995) and in the Aldan Shield (Frost et al, 1998). In the western Canadian Shield, 2.3 − 2.0 Ga juvenile crust is present in the Wopmay orogen, which could be potential a provenance for the sedimentary protoliths of the LGB metapelites (Hoffman, 1988).…”

Section: Tectonic Consequences and Correlationmentioning

confidence: 92%

Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part II: Isotopic dating

Tuisku¹,

Huhma²

2006

Bull Geol Soc Finland

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The migmatitic metapelites of the Lapland granulite belt (LGB) in the NE part of the Fennoscandian Shield represent an arc-related greywacke basin metamorphosed in the granulite facies. Detrital zircons from migmatitic metapelites are derived from 1.94 etrital zircons from migmatitic metapelites are derived from 1.94 zircons from migmatitic metapelites are derived from 1.94 derived from 1.94 − 2.9 Ga old acid source rocks (U-Pb SIMS ages). The clustering of detrital zircon ages between 1.97 and 2.2 Ga is problematic, because abundant felsic crust of this age is absent in the shield. The metasediments are characterized by Sm-Nd model ages of ca. 2.3 Ga. A younger, 1905 − 1880 Ma population of homogeneous zircons was formed during regional metamorphism. The peak high-grade metamorphism took place at ~1900 Ma and the latest chronological record from subsequent decompression and cooling phase is from ca. 1870 Ma. The norite-enderbite series of the LGB represents arc-magmas, which were intruded into the metasediments at ~1920 − 1905 Ma ago according to zircon U-Pb ages and were probably an important heat source for metamorphism. Older, zoned zircon grains in a quartz norite vein, initial ε Nd values of 0 to +1 and the continuous spectrum of LILE enrichment in the enderbite-series probably reflect assimilation of metasediments by magmas. Monazite U-Pb ages of migmatitic metasediments in the range 1906 − 1910 ± 3 Ma overlap the late stage of enderbite intrusion and growth of early metamorphic zircons. Garnetwhole rock Sm-Nd ages from leucosomes in the range 1880 − 1886 ± 7 Ma are concurrent with the growth of the youngest metamorphic zircons and probably indicate the crystallization of leucosomes or the influence of a fluid liberated from them. Isotopic and petrologic data reveal that the evolution of Lapland Granulite belt from the erosion of source rocks to the generation of a sedimentary basin, its burial, metamorphism and exhumation took place within ca. 60 Ma.

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“…1800 Ma; Ross et al, 2000). Seismic-reflection profiles across the Hearne domain reveal a crustal-scale structural fan with reflection fabrics that verge toward the bounding orogens (Ross et al, 1995). Based on these results, Ross et al (2000) developed a tectonic model involving synchronous inward-dipping subduction zones that formed a 'tectonic vise', leading to Proterozoic thickening of the intervening lithosphere.…”

Section: Implications For the Evolution Of Cratonic Lithospherementioning

confidence: 97%

Large variations in lithospheric thickness of western Laurentia: Tectonic inheritance or collisional reworking?

Bao

Eaton

2015

Precambrian Research

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Paleoproterozoic collisional orogen beneath the western Canada sedimentary basin imaged by Lithoprobe crustal seismic-reflection data

Cited by 72 publications

References 0 publications

Advances in the geology of the Tobacco Root Mountains, Montana, and their implications for the history of the northern Wyoming province

Advances in the geology of the Tobacco Root Mountains, Montana, and their implications for the history of the northern Wyoming province

Evolution of migmatitic granulite complexes: Implications from Lapland Granulite Belt, Part II: Isotopic dating

Large variations in lithospheric thickness of western Laurentia: Tectonic inheritance or collisional reworking?

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