Geology between Fairbanks and the Yukon River, east-central Alaska

Weber, Florence R.

doi:10.1029/ft104p0084

Cited by 2 publications

(1 citation statement)

References 12 publications

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“…Other subterranes within the Yukon-Tanana terrane have also been proposed, and the Fairbanks basalts are found in both the Fairbanks and Chena sub-terranes (Robinson and others, 1990). Recent geologic mapping (Weber, 1989) aeromagnetic and gravity studies (J.W. Cady, oral commun.,1991; D.F.…”

Section: Tectonic Settingmentioning

confidence: 99%

Short Notes on Alaskan Geology 1993

1993

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Short Notes on Alaskan Geology" is a collection of brief contributions describing recent geological investigations of limited scope. This publication is widely distributed to a state, national, and international audience that represents industry, academia, government agencies, and the general public. Manuscripts are accepted for consideration with the understanding that they have not been previously published and are not being submitted for publication elsewhere, that all persons listed as authors have given their approval for submission of the paper, and that any person cited as a source of personal communication has approved such a citation. Authors are encouraged to suggest appropriate reviewers and provide reviewer's telephone numbers.

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Section: Tectonic Settingmentioning

confidence: 99%

Short Notes on Alaskan Geology 1993

1993

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Mid‐Cretaceous extensional tectonics of the Yukon‐Tanana Terrane, Trans‐Alaska Crustal Transect (TACT), east‐central Alaska

Pavlis¹,

Sisson²,

Foster³

et al. 1993

Tectonics

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Mid‐Cretaceous crustal extension played a fundamental role in the structural evolution of the Yukon‐Tanana terrane (YTT) in the northern Cordilleran interior. In the central portion of the YTT northwest of Delta Junction, Alaska, a mylonitic shear zone juxtaposes greenschist facies rocks in the upper plate against middle to upper amphibolite facies metamorphic rocks in the lower plate, a juxtaposition suggesting elimination of as much as 10 km of crustal section. The mylonites form a partial sheath enveloping a domal footwall structure and kinematic analysis of the mylonite zone yields a uniform transport direction of hanging wall to ESE. These relations suggest analogies to the metamorphic core complexes of the southern Cordillera. However, the YTT structures are entirely ductile, suggesting either a relatively deep erosional level or relatively high geothermal gradients during extension. In the study area remnants of an older preextensional thrusting event are preserved at the highest structural levels at the base of the Seventymile terrane and the leading edge of YTT in the Wickersham terrane. However, most areas display a regional, subhorizontal fabric that is superimposed on older fabrics, and in the study area this latest fabric is subparallel to the mylonitic sheath of the apparent extensional structure. Thus the conventional viewpoint that this latest fabric is related to thrusting needs to be reevaluated and this fabric may be entirely extensional in origin. Further evidence for extension is provided by clear similarities between YTT and characteristic features of other extensional terranes. Thus we suggest that the YTT is a deeply eroded view of highly extended continental crust. The tectonic mechanism for the extensional event and the magnitude of the extension is uncertain because of complications in regional timing relationships and in alternative interpretations of the reconstruction of the crustal section. Three end‐member models based on analogies with Neogene extensional systems are presented as working models to accommodate the alternative interpretations: (1) a Jurassic collision and Cretaceous extension model based on comparisons with the Neogene history of the Mediterranean region; (2) an Early to mid‐Cretaceous syncollisional model analogous to the Carpathian Mountains of eastern Europe; and (3) a syncollisional plateau uplift model with extension driven by gravity spreading.

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Geology between Fairbanks and the Yukon River, east-central Alaska

Cited by 2 publications

References 12 publications

Short Notes on Alaskan Geology 1993

Short Notes on Alaskan Geology 1993

Mid‐Cretaceous extensional tectonics of the Yukon‐Tanana Terrane, Trans‐Alaska Crustal Transect (TACT), east‐central Alaska

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