Hornblende peridotite xenoliths from central Mexico reveal the highly oxidized nature of subarc upper mantle

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doi: 10.1130/0091-7613(1998)026<1035:HPXFCM>2.3.CO;2
Authors:Blatter, Dawnika L.; Carmichael, Ian S. E.
Author Affiliations:Primary:
University of California at Berkeley, Department of Geology and Geophysics, Berkeley, CA, United States
Volume Title:Geology (Boulder)
Source:Geology (Boulder), 26(11), p.1035-1038. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0091-7613
Publication Date:1998
Note:In English. 26 refs.; illus., incl. 1 table, geol. sketch map
Summary:Quaternary hornblende andesites have erupted along a fault zone near El Penon, central Mexico. One of these flows contains 1-2 cm xenoliths of amphibole-rich spinel lherzolite and chromite websterite. These xenoliths are rare samples of subarc upper mantle from a region of continuing subduction, and they are the most oxidized mantle peridotites yet described (fayalite-magnetite-quartz +1.5 to 2.4). The abundant amphibole and high oxygen fugacities that characterize these xenoliths are significant because they provide direct evidence for metasomatism of the mantle wedge by slab-derived fluids. Phenocrysts of hornblende and lack of plagioclase phenocrysts in the host andesite indicate that it equilibrated with high water content (>8 wt%), and the presence of xenoliths implies rapid (26 km/day) ascent.
Subsections:Igneous petrology
Subjects:Amphibole group; Andesites; Cenozoic; Chain silicates; Clinoamphibole; Concentration; Fault zones; Faults; Fugacity; Geochemistry; Hornblende; Igneous rocks; Inclusions; Lithogeochemistry; Mantle; Mineral composition; Oxygen; Peridotites; Phenocrysts; Plutonic rocks; Provenance; Quaternary; Silicates; Ultramafics; Upper mantle; Volcanic rocks; Xenoliths; Mexico; Mexico state; El Penon
Coordinates:N190000 N191500 W1000500 W1001500
Abstract Numbers:99M/2179
Record ID:1999000426
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
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