Regional cross-sections, detachment levels and origin of the Plateau Fault, central Mackenzie Mountains, Northwest Territories

Gordey, S P; MacDonald, Justin; Roots, C F; Fallas, K M; Martel, Edith

doi:10.4095/288749

Cited by 4 publications

(19 citation statements)

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“…In Figure c (Gordey et al, ) the model surface mimics the depth and northeastward shallowing (~16 to 11 km) of the predicted basal décollement. In Figure d (Gordey et al, ) the model surface shows a close correlation with the (~14 km) basal décollement to the southwest. The model surface shallows toward the northeast but does not intersect the basal décollement within the bounds of the cross section.…”

Section: Gravity Modeling and Interpretationmentioning

confidence: 84%

“…The model surface is intersected by Lithoprobe Slave and Northern Cordilleran Lithospheric Evolution (SNORCLE) seismic reflection lines 2b and 3 (Figure a) and the coincident Slave‐Northern Cordillera Refraction Experiment (SNORE) lines 22 and 31 (Cook et al, ; Creaser & Spence, ; Evenchick et al, ; Welford et al, ), in addition to several geological cross sections (e.g., Aitken & Cook, ; Cecile & Cook, ; Cecile, Cook, & Snowdon, ; Cook, ; 1982; Gordey, ; Gordey et al, ; Hall & Cook, ; MacDonald, ).…”

Section: Gravity Modeling and Interpretationmentioning

confidence: 99%

“…Vertical exaggeration = 2×. (c–f) Comparison of the model surface, shown by heavy black dashed line, with estimates of décollement depths, shown as dashed black lines, along geological cross sections of the Mackenzie Mountains fold and thrust belt, simplified from Gordey et al () and Cecile, Cook, and Snowdon (). Near‐surface geological interpretation is shown with Paleozoic rocks in light gray and Neoproterozoic rocks of the Windermere and Mackenzie Mountains Supergroups in dark gray.…”

Section: Gravity Modeling and Interpretationmentioning

confidence: 99%

“…Of the geological cross sections constructed for the Mackenzie Mountains fold and thrust belt, four (Figures a and c–f, Cecile, Cook, & Snowdon, ; Hall & Cook, ; Gordey et al, ; MacDonald, ) have included an excess‐area estimate (Mitra & Nameson, ) of the depth to the basal décollement. In Figure c (Gordey et al, ) the model surface mimics the depth and northeastward shallowing (~16 to 11 km) of the predicted basal décollement. In Figure d (Gordey et al, ) the model surface shows a close correlation with the (~14 km) basal décollement to the southwest.…”

Section: Gravity Modeling and Interpretationmentioning

confidence: 99%

“…The northern Cordillera of Canada and Alaska, and the Cordillera Oriental to Subandean zone of the Andes of Bolivia and Argentina are representative of contractional orogens with atypically (e.g., Pfiffner, ) backarc positioned fold and thrust belts that may result from flat‐slab subduction (e.g., Ramos, ; Ramos & Fulguera, ). Within the fold and thrust belts, continent‐verging, shallow‐dipping thrusts merge into regionally extensive décollements at depth (e.g., Cecile, Cook, & Snowdon, ; Elger et al, ; Gordey et al, ; von Gosen, ; Kley, ; Kley et al, ; Pfiffner, ). Accompanying backarc magmatism may result from changes in plate motions, subduction geometry, or slab failure (e.g., Hart et al, ; Mortensen & Hart, ; Rasmussen, ).…”

Section: Introductionmentioning

confidence: 99%

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The 3D Geophysical Investigation of a Middle Cretaceous to Paleocene Regional Décollement in the Cordillera of Northern Canada and Alaska

Hayward

2019

Tectonics

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A new approach to the 3D inversion and interpretation of gravity data is applied to the crustal architecture of the northern Cordillera of Canada and Alaska. The technique models the distribution and depth extent of rocks with systematic density contrasts, such as sedimentary or intrusive rocks. In the northern Cordillera, the geometry of low-density zones, primarily associated with middle to Late Cretaceous granitic intrusions, and Neoproterozoic and Cretaceous sedimentary rocks, is defined. Variation in the depth extent of these zones delimits a surface, interpreted herein as a regional décollement syntectonic with, or postdating, middle Cretaceous intrusions, but predating and displaced~430 km by the Eocene-aged Tintina fault. The décollement trends N35°E and shallows from a depth of~15-20 km beneath Selwyn basin tõ 11 km beneath the Mackenzie Mountains. Here surface faults echo the décollement geometry, linked to fold and thrust belt development between the middle Cretaceous and Paleocene. The décollement continues southward for an unknown distance into northern British Columbia, but the Liard line represents a structural discontinuity between the fold and thrust belts of the Mackenzie Mountains and northern Rocky Mountains. The décollement's northwestern extent is broadly defined by surface faults in the northern Ogilvie Mountains. However, prior to Tintina fault displacement, the décollement was likely connected to a fold and thrust belt and related décollement in east-central Alaska. Estimates of post-middle Cretaceous exhumation suggest regional tectonic modification of the décollement, possibly including the presently active detachment inferred for the weak lower crust.HAYWARD 307

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Section: Gravity Modeling and Interpretationmentioning

confidence: 84%

Section: Gravity Modeling and Interpretationmentioning

confidence: 99%

Section: Gravity Modeling and Interpretationmentioning

confidence: 99%

Section: Gravity Modeling and Interpretationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The 3D Geophysical Investigation of a Middle Cretaceous to Paleocene Regional Décollement in the Cordillera of Northern Canada and Alaska

Hayward

2019

Tectonics

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Deformation at the eastern margin of the Northern Canadian Cordillera: Potentially related to opening of the North Atlantic

2019

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The Northern Canadian Cordillera (NCC) comprises the Mackenzie Mountains, which are characterized by earthquakes occurring ~1,000 km east of the western North American margin. However, no recognized convergence has occurred in this inboard region since the Mesozoic to early Cenozoic formation of the Cordillera. This lack of an obvious driver for the modern NCC deformation has generated considerable debate and various geodynamic models. We show here thermal histories derived from (U‐Th‐Sm)/He data that are interpreted to indicate reactivated deformation and formation of the eastern deformation front beginning ~30 Ma. At that time the western margin of North America was mainly a transform boundary, which typically transmits very limited amount of stress into the continent. Along the northeastern margin of North America, however, the North Atlantic was opening and may have caused horizontal forces that drove deformation far to the west where the rigid craton encountered the weak Cordillera.

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Geophysical reassessment of the role of ancient lineaments on the development of the western Laurentian margin and its sediment-hosted Zn–Pb deposits, Yukon and Northwest Territories, Canada

Hayward

Paradis

2021

Can. J. Earth Sci.

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A new 3-D inversion strategy is applied to new compilations of gravity and magnetic data, to reassess the role of crustal lineaments in the development of the western Laurentian margin, Selwyn basin and associated sediment-hosted Zn-Pb deposits. The region’s history is obscured by multiple tectonic overprints including terrane accretion, plutonism, and thrust faulting. Regionally continuous, broadly NE-trending crustal lineaments including the Liard line, Fort Norman structure, and Leith Ridge fault, were interpreted as having had long-standing influence on craton, margin, and sedimentary basin development. An ENE-trending lineament, Mackenzie River, traced from the Misty Creek Embayment to Great Bear Lake, is interpreted as the southern edge of a cratonic promontory. The location of the Liard line, associated with a transfer fault that bounds the Macdonald Platform promontory, is refined. New geophysical results support the continuity of the Fort Norman structure below the Selwyn basin, but limited evidence exists for the Leith Ridge fault in this area. A NW-trending lineament that bounds the craton is interpreted as a crustal manifestation of lithospheric thinning of the Laurentian margin, as echoed by a change in the depth of the lithosphere-asthenosphere boundary. The structure delimits the eastern extent of mid-Late Cretaceous granitic intrusions and is straddled by Mississippi Valley-type Zn-Pb occurrences, following their palinspastic restoration. Clastic-dominated Zn-Pb occurrences are aligned along another NW-trending lineament interpreted to be associated with a shallowing of lower crustal rocks.

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Regional cross-sections, detachment levels and origin of the Plateau Fault, central Mackenzie Mountains, Northwest Territories

Cited by 4 publications

References 0 publications

The 3D Geophysical Investigation of a Middle Cretaceous to Paleocene Regional Décollement in the Cordillera of Northern Canada and Alaska

The 3D Geophysical Investigation of a Middle Cretaceous to Paleocene Regional Décollement in the Cordillera of Northern Canada and Alaska

Deformation at the eastern margin of the Northern Canadian Cordillera: Potentially related to opening of the North Atlantic

Geophysical reassessment of the role of ancient lineaments on the development of the western Laurentian margin and its sediment-hosted Zn–Pb deposits, Yukon and Northwest Territories, Canada

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