Some plutonic rocks of southwestern Alaska, a data compilation

Wilson, Frederic H.

doi:10.3133/ofr77501

Cited by 11 publications

(35 citation statements)

References 5 publications

(1 reference statement)

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“…Widely dispersed latest Cretaceous and (or) early Tertiary granitic rocks intrude the Kuskokwim Group and most of the older rocks, but do not intrude the Kanektok metamorphic complex (Patton and others, 1975;Wilson, 1977;Hoare and Coonrad, 1978;Box and others, 1993). The plutons yield ages between approximately 60 and 70 Ma and show a crude compositional zoning.…”

Section: Geologic Frameworkmentioning

confidence: 99%

Reconnaissance geologic map of the Kuskokwim Bay region, southwest Alaska

Wilson¹,

Hults²,

Mohadjer³

et al. 2013

Scientific Investigations Map

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Section: Geologic Frameworkmentioning

confidence: 99%

Reconnaissance geologic map of the Kuskokwim Bay region, southwest Alaska

Wilson¹,

Hults²,

Mohadjer³

et al. 2013

Scientific Investigations Map

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“…Wallace (written commun., 2004). Also widely distributed west of the batholith are latest Cretaceous and early Tertiary granitic plutons (Wilson, 1977;Wilson and others, 2003), some of which are peralkaline.…”

Section: Geographic Geologic and Physiographic Frameworkmentioning

confidence: 99%

“…Biotite and hornblende are locally common; muscovite is uncommon. Common in the western Dillingham quadrangle (Wilson, 1977) and many are unusual in that they tend to have biotite and pyroxene, often orthopyroxene, as their mafic minerals, regardless of the overall pluton composition (see Wilson, 1977). Unit also includes fine-, medium-, and coarse-grained, light-to dark-gray, plutonic granitic rocks mixed with felsic dikes and contact metamorphosed volcanic or sedimentary rocks in the northeastern Dillingham quadrangle.…”

Section: Tvumentioning

confidence: 99%

“…data, 2006), rocks of this pluton cluster about the intersection of the quartz monzonite, monzogranite, granodiorite, and quartz monzodiorite fields of Streckeisen (1975); however, visually estimated modes place the rock unit primarily in the monzogranite field. The Tikchik Lake and Akuluktuk plutons of Wilson (1977) are also assigned to this map unit. Another relatively large granite pluton is exposed in the central Lake Clark quadrangle; biotite and hornblende are in sub-equal proportions (Nelson and others, 1983 Granodiorite-Medium-grained, hypidiomorphic granular, seriate granodiorite.…”

Section: Tvumentioning

confidence: 99%

“…Based on K-Ar dates ranging from 67.2±1.9 to 74.4±2.2 Ma (Reed and Lanphere, 1972; (Detterman and Reed, 1980;Nelson and others, 1983). Includes plutons in the Iliamna and Lake Clark quadrangles and the pluton of the Okstukuk Hills in the Dillingham quadrangle (Wilson, 1977), which consists of biotite granite or syenite having very coarse feldspar laths, medium-grained very fresh biotite, and finegrained clinopyroxene. K-Ar ages range from 75.6 to 85.5 Ma (Reed and Lanphere, 1972; Granodiorite (Late Cretaceous)-Isolated porphyritic granodiorite body having phenocrysts of quartz, plagioclase, biotite, and glomeroporphyritic clusters of pale-green amphibole in a groundmass of quartz and mostly potassic feldspar in the south-central Lake Clark quadrangle (Nelson and others, 1983) and a small granodiorite pluton in the eastern Taylor Mountains quadrangle (F.H.…”

Section: Tvumentioning

confidence: 99%

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Bedrock geologic map of the northern Alaska Peninsula area, southwestern Alaska

2017

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Relationships between plate motions and Late Cretaceous to Paleogene magmatism in southwestern Alaska

Wallace¹,

Engebretson²

1984

Tectonics

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Four major Late Cretaceous to Paleogene magmatic belts have been recognized in southwestern Alaska, and tentative boundaries have been drawn for each. The belts indicate minimum ages by which the tectonostratigraphic terranes they overprint must have been linked together, though there has been significant postmagmatic tectonism. The Kuskokwim Mountains belt (73–60 m.y. B.P.), the Alaska Range belt (74–55 m,y. B.P.), and the Gulf of Alaska belt (62–57 m.y. B.P.) all may have been related to a period of rapid north‐northeastward motion of the KuIa plate from about 74 to 56 m.y. B.P. The angle of convergence was low with respect to the present orientation of the belts, suggesting the possibility of postmagmatic rotation of the belts. A higher angle of convergence may have existed with respect to the Alaska Range belt, a probable arc, if postmagmatic rotation resulted from 300–400 km of right‐lateral displacement on the Denali fault. The Gulf of Alaska belt is in an anomalous forearc position with respect to the Alaska Range belt, but probably formed by a convergence‐related mechanism. The Kuskokwim Mountains belt is in an apparent back arc position, but the mechanism of its origin is uncertain. It may have been part of an unusually broad Alaska Range arc or, less likely, it may have been a separate arc. Magmatic quiescence occurred throughout south‐western Alaska during a period of plate reorganization from about 56 to 43 m.y. B.P., a period which began with extremely rapid northward motion of the KuIa plate. Magmatism resumed when the present period of rather slow northwestward Pacific plate motion began at about 43 m.y. B.P. The Aleutian arc probably formed at this time, and has been episodically active in about the same location ever since.

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Some plutonic rocks of southwestern Alaska, a data compilation

Cited by 11 publications

References 5 publications

Reconnaissance geologic map of the Kuskokwim Bay region, southwest Alaska

Reconnaissance geologic map of the Kuskokwim Bay region, southwest Alaska

Bedrock geologic map of the northern Alaska Peninsula area, southwestern Alaska

Relationships between plate motions and Late Cretaceous to Paleogene magmatism in southwestern Alaska

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