Map and tables showing preliminary results of potassium-argon age studies in the Circle Quadrangle, Alaska, with a compilation of earlier dating work

Wilson, Frederic H.; Shew, Nora B.

doi:10.3133/ofr81889

Cited by 4 publications

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“…This report This report Wilson and Shew (1981) Wilson and Shew (1981) This report This report This report Wilson and Shew (1981) Wilson and Shew (1981) Wilson and Shew (1981) Wilson and Shew (1981) Wilson and Shew (1981) Wilson and Shew (1981) Wilson and Shew (1981) Wilson and Shew (1981) Wilson and Shew (1981) Can. J.…”

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confidence: 90%

“…More recent mapping by Foster and Weber (Foster 1970(Foster , 1976Foster et al 1976Foster et al , 1979Weber et al 1978) and others has recognized the variety of metamorphic rocks in the region and the extent and variety of igneous rocks. Geochronological studies in the terrane have been undertaken on a piecemeal basis starting with early Pb-alpha work by Matzko et al (1958), proceeding to recent U-Th-Pb studies by Aleinikoff et al (1981 a,b), and continuing with K-Ar studies by the authors (Wilson and Shew 1981;this report). Results of most studies prior to 1980 were compiled by Dadisman (1980).…”

Section: Introductionmentioning

confidence: 97%

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Review of radiometric data from the Yukon Crystalline Terrane, Alaska and Yukon Territory

Wilson¹,

Smith²,

Shew³

1985

Can. J. Earth Sci.

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The results of more than 20 years of geochronological studies in the Yukon Crystalline Terrane in east-central Alaska and the western Yukon Territory suggest at least six igneous and thermal (metamorphic?) events. Plutonism during Mississippian, Early Jurassic, mid-Cretaceous, Late Cretaceous, and early Tertiary times is indicated. Evidence also indicates that Mississippian, Early Jurassic, late Early Cretaceous, and late Cretaceous thermal (metamorphic?) events have affected parts of the terrane. The western part of the terrane was affected by a significant regional metamorphic event in late Early Cretaceous time, followed by a terrane-wide mid-Cretaceous plutonic event. The pattern of K-Ar ages allows division of the terrane into domains, bounded by northeast-trending lineaments.L'examen des rksultats de plus de 20 annkes d'ktudes gkochronologiques de la plate-forme cristalline du Yukon rkvkle au moins la prCsence de six kvknements ignks et thermiques (mktamorphiques?). Le plutonisme fut actif durant le Mississippien, le Jurassique infkrieur, le Crktack moyen, le Crktack supkrieur et le Tertiaire infkrieur. On observe que des manifestations thermiques (mktamorphiques?) ont affectk des parties de la plate-forme cristalline du Yukon durant le Mississippien, le Jurassique infkrieur, le CrktacC tardi-infkrieur et le Crktace supkrieur. Durant le Crktack tardi-infkrieur est survenu un important kvknement de mktamorphisme regional qui a affectk la partie occidentale de la plate-forme cristalline, lequel fut suivi au CrktacC moyen par un kvknement plutonique englobant toute la largeur de la plate-forme cristalline. Le motif d'ktalement des Lges K-Ar permet de diviser la plate-forme cristalline en domaines, lesquels sont limitks par des lineaments de direction nord-est.[Traduit par le journal]Can.

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mentioning

confidence: 90%

Section: Introductionmentioning

confidence: 97%

Review of radiometric data from the Yukon Crystalline Terrane, Alaska and Yukon Territory

Wilson¹,

Smith²,

Shew³

1985

Can. J. Earth Sci.

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“…This displacement, against the backstop of the North American craton, is interpreted to have been accommodated by faults that transition from strike slip in the east to transpressional and thrust faults toward the west (Wilson & Weber, ). For example, the Wickersham unit is interpreted (Weber et al, ) to be thrust over a Paleocene‐aged (59.8 ± 1.8 Ma, Wilson et al, ) granitic pluton at Cache Mountain (Figure ), and steep, NE striking faults displace a genetically similar granitic plutons (58.0 ± 1.8 Ma, Wilson & Shew, ; Wilson et al, ) in the Mount Prindle (PR, Figure ) region (Holm, ; Wilson et al, ).…”

Section: Discussionmentioning

confidence: 99%

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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“…The time period over which the uplift took place is uncertain, because neither the granite nor the felsic dikes that are associated with the gold (Wilson and Shew, 1981). Felsic dikes and hypabyssal rocks similar to those in the Table Mountain area exist in or adjacent to other plutons in the region.…”

Section: Discussionmentioning

confidence: 99%

“…B.P. (Wilson and Shew, 1981 Both the granite and metamorphic rocks have been intruded by dikes and hypabyssal rocks which are most abundant west and southwest of the granite. Most dikes are felsic, but a few are of intermediate composition.…”

Section: Geologic Se'itingmentioning

confidence: 99%

Newly located occurrences of lode gold near Table Mountain, Circle Quadrangle, Alaska

Menzie¹,

Hua²,

Foster³

1987

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Most of the goldbearing samples are clustered in two areas.The highest concentrations of gold (2.6-140 ppm) occur, just west of Table Mountain, in black biotite schist and in quartz veins adjacent to a fault zone that is intruded by a hypabyssal felsic dike. Five kilometers to the northeast, where a small granite pluton crops out, gold was detected in lesser amounts ( 0.05-0.2 ppm) in country rocks adjacent to the granite, in the granite adjacent to dikes, and in felsic dikes. The occurrences have a simple mineralogy: pyrrhotite, arsenopyrite, minor chalcopyrite, and rare enargite and sphalerite. They formed from low-saline fluids ( 10 weight percent NaCl equivalent) whose sulfur fugacities were within the stability field of pyrrhotite. Based upon fluid-inclusion data, we infer that the occurrences formed at moderate temperatures from fluids that initially boiled, over the range 370 to 320 °C, and then gradually cooled. Field relations and estimated depths of formation of contact metamorphic effects and quartz veins indicate that the occurrences formed in an active tectonic environment.

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Map and tables showing preliminary results of potassium-argon age studies in the Circle Quadrangle, Alaska, with a compilation of earlier dating work

Cited by 4 publications

References 0 publications

Review of radiometric data from the Yukon Crystalline Terrane, Alaska and Yukon Territory

Review of radiometric data from the Yukon Crystalline Terrane, Alaska and Yukon Territory

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

Newly located occurrences of lode gold near Table Mountain, Circle Quadrangle, Alaska

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