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Transition from calc-alkalic to adakitic magmatism at Cayambe Volcano, Ecuador; insights into slab melts and mantle wedge interactions

Pablo Samaniego, Herve Martin, Claude Robin and Michel Monzier
Transition from calc-alkalic to adakitic magmatism at Cayambe Volcano, Ecuador; insights into slab melts and mantle wedge interactions
Geology (Boulder) (November 2002) 30 (11): 967-970

Abstract

In volcanic arcs, two main types of magmatism are recognized: (1) widespread calc-alkalic magmatism, generated by hydrous partial melting of a metasomatized mantle wedge, and (2) less common adakitic volcanism produced by subducted-slab melting. The Cayambe volcanic complex in Ecuador shows a progressive temporal change from an older calc-alkalic volcano (Viejo Cayambe) to a younger adakitic edifice (Nevado Cayambe). This evolution may be related to the unusual geodynamic setting of the Ecuadorian Andes, controlled mainly by the subduction of the Nazca plate, including the Carnegie Ridge thickened oceanic crust. The Viejo Cayambe magmas appear to be generated from a mantle-wedge source, slightly metasomatized by slab-derived melts. Conversely, the Nevado Cayambe magmas imply either stronger and more advanced interactions between slab melts and mantle peridotite, or that adakitic magma could reach the surface due to higher degrees of slab melting. Fractional crystallization, assimilation, and mixing processes also contributed to lava diversity. We propose that the magmatic evolution of the Cayambe volcanic complex is due to increasing efficiency of interaction between slab melts and the mantle wedge, because of higher degrees of slab melting in response to the subduction of the Carnegie Ridge.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 30
Serial Issue: 11
Title: Transition from calc-alkalic to adakitic magmatism at Cayambe Volcano, Ecuador; insights into slab melts and mantle wedge interactions
Affiliation: Escuela Politecnica Nacional, Departamento de Geofisica, Quito, Ecuador
Pages: 967-970
Published: 200211
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 17
Accession Number: 2002-079170
Categories: Quaternary geologyIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2002114
Illustration Description: illus. incl. 1 table, sketch map
S00°01'60" - N00°07'00", W78°07'00" - W77°55'00"
Secondary Affiliation: Universite Blaise Pascal, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200224
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