Skip to Main Content
GEOREF RECORD

Role of H (sub 2) O in subduction-zone magmatism; new insights from melt inclusions in high-Mg basalts from central Mexico

Pablo Cervantes and Paul J. Wallace
Role of H (sub 2) O in subduction-zone magmatism; new insights from melt inclusions in high-Mg basalts from central Mexico
Geology (Boulder) (March 2003) 31 (3): 235-238

Abstract

Although there is a growing body of data on H (sub 2) O in arc magmas, there is still considerable uncertainty about the relationship between H (sub 2) O and various incompatible elements during enrichment of the mantle wedge by subduction processes. We report data for H (sub 2) O, other volatiles (CO (sub 2) , S, Cl), and trace elements in olivine-hosted melt inclusions from high-Mg basalts in central Mexico that exhibit varying degrees of subduction-related enrichment. Most melt inclusions were trapped at low pressure, but rare inclusions (Mg 65-78, olivine hosts Fo (sub 85-90) ) trapped at upper to middle crustal pressures (1-6 kbar) contain high CO (sub 2) (250-2120 ppm). The high-pressure inclusions indicate magmatic H (sub 2) O contents from 1.3 to 5.2 wt%. Enrichment of H (sub 2) O relative to Nb correlates positively with K/Nb, Ba/Nb, and La/Nb, indicating a clear link between H (sub 2) O and trace element enrichment of the mantle wedge. Our results show that fluxing of the wedge with an H (sub 2) O-rich component from the subducted slab is important in formation of magmas that are enriched in large ion lithophile (LILE) and light rare earth (LREE) elements relative to high field strength elements (HFSE). In contrast, magmas with low LILEs and LREEs relative to HFSEs have relatively low H (sub 2) O, and must have formed largely by decompression melting of unmodified mantle. Our data for volcanoes <50 km apart show evidence of significant variability in the composition of H (sub 2) O-rich subduction components that are added to the mantle wedge beneath central Mexico.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 31
Serial Issue: 3
Title: Role of H (sub 2) O in subduction-zone magmatism; new insights from melt inclusions in high-Mg basalts from central Mexico
Affiliation: Texas A&M University, Department of Geology and Geophysics, College Station, TX, United States
Pages: 235-238
Published: 200303
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 23
Accession Number: 2003-025977
Categories: Geochemistry of rocks, soils, and sedimentsIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2003021
Illustration Description: illus. incl. 1 table
N18°40'00" - N19°19'60", W99°40'00" - W98°40'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200309
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal