Paleoproterozoic crust within the Great Falls tectonic zone: Implications for the assembly of southern Laurentia

Mueller, Paul A.; Heatherington, Ann L.; Kelly, D. M.; Wooden, Joseph L.; Mogk, David W.

doi:10.1130/0091-7613(2002)030<0127:pcwtgf>2.0.co;2

Cited by 106 publications

(65 citation statements)

References 33 publications

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“…With an intrusive age of ca. 1.86 Ga (U-Pb and Pb-Pb zircon dating by Mueller et al, 1996bMueller et al, , 2002, these rocks would have originated in an arc that was active prior to and at the inception of the Big Sky orogeny, timing that is consistent with an arc-continent collisional orogeny. On this basis, the basement of the Little Belt Mountains should be considered a suspect terrane with respect to the Big Sky orogen.…”

Section: Accreted Arcmentioning

confidence: 72%

“…If not, reinterpretation of the geophysical anomalies is required. In either case, there is remarkable synchroneity between collisional activity along the southern margin of the Wyoming province in the Cheyenne belt (Chamberlain et al, 1993;Houston, 1993;Premo and Van Schmus, 1989) and the development of the Big Sky orogen as we have documented it in the Tobacco Root Mountains (see also Mueller et al, 2002). These timing relationships constrain the process or processes by which the Precambrian basement of the North American craton was assembled, and the orchestration of those processes, and must be of fundamental importance to general models of crustal evolution.…”

Section: Implications For the Assembly Of The Northern Wyoming Provinmentioning

confidence: 88%

“…This has led some to look farther north, across the Medicine Hat block to the Vulcan structure, for the limit of the Wyoming province and to attribute the Great Falls tectonic zone to intraplate deformation (Boerner et al, 1998;Eaton et al, 1999;Buhlmann et al, 2000;Gorman et al, 2002;Lemieux et al, 2000). We know of no way other than arc-continent collision to produce a tectonic belt with the characteristics of the Big Sky orogen as we now understand them and conclude that closure of an ocean basin must have occurred (see also Mueller et al, 2002). This model does not, however, obviate the possibility that the Medicine Hat block, or perhaps all of the Hearne province, was related to the Wyoming province prior to rifting at ca.…”

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

confidence: 90%

“…Since its identifi cation, interest in the Great Falls tectonic zone has focused principally on whether it marks the northern boundary of the Wyoming province (Boerner et al, 1998;Eaton et al, 1999;Holm and Schneider, 2002;Lemieux et al, 2000;Mueller et al, 2002). In assessing the nature of the Great Falls tectonic zone, much attention has been paid to the absence of gravity or electromagnetic signatures expected for a plutonic belt or accretionary sediment wedge that would have been generated by subduction before closure along a boundary.…”

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

confidence: 98%

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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: Accreted Arcmentioning

confidence: 72%

Section: Implications For the Assembly Of The Northern Wyoming Provinmentioning

confidence: 88%

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

confidence: 90%

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

confidence: 98%

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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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“…The Great Falls tectonic zone manifests itself as a northeast-trending geophysical discontinuity that is largely buried by younger cover. Mueller et al, 2002). Ca.…”

Section: Pre-belt Basementmentioning

confidence: 99%

Provenance of the Mesoproterozoic (1.45 Ga) Belt basin (western North America): Another piece in the pre-Rodinia paleogeographic puzzle

Ross

Villeneuve

2003

Geo. Society Am. Bull.

194

149

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The Mesoproterozoic (1.47-1.40 Ga) Belt basin in western North America contains a thick succession of siliciclastic strata dominated by sediment derived from source areas that lay to the west and southwest of the present basin. The age and identity of this source area is important for reconstruction of the Mesoproterozoic history of western North America. Over 400 new SHRIMP U-Pb ages for detrital zircons, supplemented by Ar-Ar ages of detrital muscovite from sandstones within the Belt basin, document distinctive provenances of the basin fill; the predominant sediment influx came from a western craton, whereas subordinate input came from Laurentian sources to the east and south of the basin.

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The meaning of midlithospheric discontinuities: A case study in the northern U.S. craton

Hopper

Fischer

2015

Geochem Geophys Geosyst

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Converted wave imaging has revealed significant negative velocity gradients, often termed midlithospheric discontinuities, within the thick, high‐velocity mantle beneath cratons. In this study, we investigate the origins and implications of these structures with high‐resolution imaging of mantle discontinuities beneath the Archean Wyoming, Superior and Medicine Hat, and Proterozoic Yavapai and Trans‐Hudson terranes. Sp phases from 872 temporary and permanent broadband stations, including the EarthScope Transportable Array, were migrated into three‐dimensional common conversion point stacks. Four classes of discontinuities were observed. (1) A widespread, near‐flat negative velocity gradient occurs largely at 70–90 km depth beneath both Archean and Proterozoic cratons. This structure is consistent with the top of a frozen‐in layer of volatile‐rich melt. (2) Dipping negative velocity gradients are observed between 85 and 200 km depth. The clearest examples occur at the suture zones between accreted Paleoproterozoic Yavapai arc terranes and the Wyoming and Superior cratons. These interfaces could represent remnant subducting slabs, and together with eclogite in xenoliths, indicate that subduction‐related processes likely contributed to cratonic mantle growth. (3) Sporadic positive velocity gradients exist near the base of the lithospheric mantle, perhaps due to laterally variable compositional layering. (4) In contrast to off‐craton regions, clear Sp phases are typically not seen at lithosphere‐asthenosphere boundary depths beneath Archean and Proterozoic terranes, consistent with a purely thermal contrast between cratonic mantle lithosphere and asthenosphere.

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Paleoproterozoic crust within the Great Falls tectonic zone: Implications for the assembly of southern Laurentia

Cited by 106 publications

References 33 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

Provenance of the Mesoproterozoic (1.45 Ga) Belt basin (western North America): Another piece in the pre-Rodinia paleogeographic puzzle

The meaning of midlithospheric discontinuities: A case study in the northern U.S. craton

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