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Trace-element geochemistry of metabasaltic rocks from the Yukon-Tanana Upland and implications for the origin of tectonic assemblages in East-Central Alaska

Cynthia Dusel-Bacon and Kari M. Cooper
Trace-element geochemistry of metabasaltic rocks from the Yukon-Tanana Upland and implications for the origin of tectonic assemblages in East-Central Alaska
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (October 1999) 36 (10): 1671-1695

Abstract

Major and trace-element analytical data are presented for 27 amphibolites and six greenstones from three structural assemblages in the Yukon-Tanana Upland: the Lake George assemblage (LG) of Devono-Mississippian augen gneiss, schist, quartzite and amphibolite; the Taylor Mountain assemblage (TM) of mafic schist and gneiss, marble, quartzite and metachert; and the Seventymile terrain of greenstone, serpentinized peridotite and metasedimentary rocks. Most LG amphibolites have relatively high Nb, TiO (sub 2) , Zr and LREE, indicative of an alkalic to tholeiitic, within-plate basalt origin. TM amphibolites have a tholeiitic or calc-alkaline composition, low normalized abundances of Nb and Ta relative to Th and La, and Ti/V values of < 20, all indicative of a volcanic-arc origin. Limited Seventymile greenstone data indicate a tholeiitic or calc-alkaline composition and intermediate to high Ti/V values (27-48), consistent with either a within-plate or an ocean-floor basalt origin. The implications from these results are discussed.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 36
Serial Issue: 10
Title: Trace-element geochemistry of metabasaltic rocks from the Yukon-Tanana Upland and implications for the origin of tectonic assemblages in East-Central Alaska
Affiliation: U. S. Geological Survey, Menlo Park, CA, United States
Pages: 1671-1695
Published: 199910
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 84
Accession Number: 2000-025929
Categories: Geochemistry of rocks, soils, and sedimentsIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. 3 tables, geol. sketch maps
N51°00'00" - N72°00'00", W130°00'00" - E173°00'00"
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
Update Code: 200008
Program Name: USGSOPNon-USGS publications with USGS authors
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