Archean bimodal volcanism

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Authors:Thurston, P. C.; Ayres, L. D.; Edwards, G. R.; Gélinas, L.; Ludden, J. N.; Verpaelst, P.
Author Affiliations:Primary:
Ont. Geol. Surv., Toronto, ON, Canada
Other:
Ont. Geol. Surv., Canada
Geol. Surv. Can., Canada
Manit. Dep. Energy and Mines, Geol. Serv. Branch, Canada
Univ. Manit. Dep. Earth Sci., Canada
York Univ., Dep. Earth and Atmos. Sci., Canada
Univ. Montréal, Dep. Geol., Canada
Volume Title:Evolution of Archean supracrustal sequences
Volume Authors:Ayres, L. D., editor; Thurston, P. C.; Card, K. D.; Weber, W.
Source:Special Paper - Geological Association of Canada, Vol.28, p.7-21; Annual meeting of the Geological Society of Canada, Winnipeg, MB, Canada, 1982, edited by L. D. Ayres, P. C. Thurston, K. D. Card and W. Weber. Publisher: Geological Association of Canada, Toronto, ON, Canada. ISSN: 0072-1042. ISBN: 0-919216-24-2
Publication Date:1985
Note:In English with French summary. Cent. Precambrian Stud.; Paper No. 96. 110 refs.; illus. incl. 4 tables, sketch map
Summary:Evidence from the Superior Province of Canada suggests that many Archaean volcanic successions are bimodal, involving an early tholeiitic basaltic-andesitic and a later dacitic-rhyolitic magma; also for the simultaneous existence of mafic and felsic magmas. Many Archaean volcanic successions evolved by fractional crystallization from mantle-derived, low-Fe, tholeiitic basaltic liquid to high-Fe andesite with rare dacite. Zoned felsic magma chambers, topping volcanic cycles, were produced by large-scale anatexis of older sialic crust. Bimodal volcanism is most clearly defined by major-element but sometimes only by trace-element contents. [J.M.H.]
Subjects:Andesites; Archean; Basaltic composition; Basalts; Composition; Dacites; Felsite; Geochemistry; Granites; Igneous rocks; Iron; Lanthanum; Magma chambers; Magmas; Metals; Petrography; Petrology; Phenocrysts; Plutonic rocks; Precambrian; Pumice; Pyroclastics; Rare earths; Samarium; Tholeiite; Volcanic rocks; Volcanism; Volcanology; Canada; Canadian Shield; Eastern Canada; North America; Ontario; Quebec; Superior Province; Uchi Subprovince; Abitibi Subprovince; Bimodal volcanism
Abstract Numbers:86M/3616
Record ID:1986007968
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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