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GEOREF RECORD

The geochemistry of young volcanism throughout western Panama and southeastern Costa Rica; an overview

M. J. Defant, T. E. Jackson, M. S. Drummond, J. Z. de Boer, H. Bellon, M. D. Feigenson, R. C. Maury and R. H. Stewart
The geochemistry of young volcanism throughout western Panama and southeastern Costa Rica; an overview
Journal of the Geological Society of London (August 1992) 149 (4): 569-579

Abstract

Oblique aseismic subduction below this region has produced arc- related volcanism over the last 2 m.y. The volcanism consisted of andesites to rhyolites but mainly dacites, and has geochemical characteristics suggesting a metamorphosed basaltic source. It is suggested that thesubduction of young oceanic crust set up conditions under which the slab melted rather than the overlying mantle wedge. The melts are sometimes associated with a few rare young high-Nb basalts, but there is no obvious link between them through differentiation. Numerous representative rock analyses for major, trace and REE are tabulated, together with K/Ar dates for 28 rocks. The eruption of these rocks with slab-melt compositions and high-Nb basalts was preceded by a 2-3 m.y. period of relative quiescence. Prior to this, there was a 7 m.y. period of calc- alkaline volcanism typical of the present-day magmatism (associated with a distinctive Benioff zone) found throughout the Central American arc. The abrupt transition in volcanism with time from an early calc-alkaline sequence to a later sequence of high- Nb basalt with these andesites, dacites and rhyolites resulting from slab-melt (and thereby comparable with the rocks of Adak Island, Alaska) may record a change in the tectonic setting of W Panama and SE Costa Rica over the past 12 m.y.


ISSN: 0016-7649
EISSN: 2041-479X
Coden: JGSLAS
Serial Title: Journal of the Geological Society of London
Serial Volume: 149
Serial Issue: 4
Title: The geochemistry of young volcanism throughout western Panama and southeastern Costa Rica; an overview
Affiliation: University of South Florida, Department of Geology, Tampa, FL, United States
Pages: 569-579
Published: 199208
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
References: 71
Accession Number: 2008-063292
Categories: Igneous and metamorphic petrologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
N08°00'00" - N11°15'00", W86°00'00" - W82°30'00"
N07°10'00" - N09°40'00", W83°01'60" - W77°10'00"
Secondary Affiliation: University of Alabama at Birmingham, USA, United StatesWesleyan University, USA, United StatesUniversite de Bretagne Occidentale, FRA, FranceRutgers University, USA, United States
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200814
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