Late Proterozoic granitic magmatism on Seward Peninsula and a Barentian origin for Arctic Alaska-Chukotka

Brian E Patrick; William C McClelland

doi:10.1130/0091-7613(1995)023<0081:LPGMOS>2.3.CO;2

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Late Proterozoic granitic magmatism on Seward Peninsula and a Barentian origin for Arctic Alaska-Chukotka

Journal article

Peer reviewed

Late Proterozoic granitic magmatism on Seward Peninsula and a Barentian origin for Arctic Alaska-Chukotka

Brian E Patrick and William C McClelland

Geology (Boulder), Vol.23(1), pp.81-84

01/1995

DOI: 10.1130/0091-7613(1995)023<0081:LPGMOS>2.3.CO;2

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Abstract

New U-Pb zircon age determinations of 676 + or - 15 Ma and 681 + or - 3 Ma (upper intercept ages) for two granitic orthogneiss bodies on Seward Peninsula confirm a minimum age of late Proterozoic for the lower Nome Group, a continental margin sequence in northwestern Alaska. Discordance of U-Pb data is attributed to Pb loss (lower intercepts of 117 + or - 17 Ma and 124 + or - 6Ma) induced by high-pressure, low-temperature metamorphism during the Jurassic-Cretaceous Brookian Orogeny. Age correlation of the Seward Peninsula bodies with late Proterozoic orthogneiss bodies in the Brooks Range and eastern Siberia (Chukotka) provides an early paleogeographic link between these regions and indicates the existence of a late Proterozoic magmatic belt in Arctic Alaska-Chukotka. This magmatic belt is temporally distinct from known late Proterozoic magmatism in the North American Cordillera and Canadian Arctic Islands, but it is strikingly similar inage to pre-Caledonian magmatism in eastern North America and in Svalbard. We suggest that the pre-Cretaceous Arctic Alaska-Chukotka crustal fragment restores to the Barentian continental margin and is thus exotic to western North America. Our reconstruction supports models calling for a Canadian Arctic Islands transform margin (rather than rotational models) during Cretaceous opening of the Canada Basin.

absolute age

Alaska

Arctic Ocean

Arctic region

Asia

Barentia

Canada Basin

Chukchi Peninsula

Commonwealth of Independent States

continental drift

continental margin

dates

faults

Geochronology

gneisses

granite gneiss

igneous activity

Igneous and metamorphic petrology

magmas

metamorphic rocks

Neoproterozoic

nesosilicates

orthogneiss

orthosilicates

paleogeography

Precambrian

Proterozoic

Russian Federation

Seward Peninsula

silicates

Stratigraphy

strike-slip faults

terranes

transform faults

U/Pb

United States

upper Precambrian

West-Central Alaska

zircon

zircon group

Details

Title: Subtitle: Late Proterozoic granitic magmatism on Seward Peninsula and a Barentian origin for Arctic Alaska-Chukotka
Creators: Brian E Patrick - University of California, Santa Barbara
William C McClelland - University of California, Santa Barbara
Resource Type: Journal article
Publication Details: Geology (Boulder), Vol.23(1), pp.81-84
Publisher: Geological Society of America (GSA)
DOI: 10.1130/0091-7613(1995)023<0081:LPGMOS>2.3.CO;2
ISSN: 0091-7613
eISSN: 1943-2682
Language: English
Date published: 01/1995
Academic Unit: Earth and Environmental Sciences
Record Identifier: 9984229295702771

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