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Title: Clinopyroxene precursors to amphibole sponge in arc crust
Authors: Smith, Daniel J.
First Published: 8-Jul-2014
Publisher: Nature Publishing Group
Citation: Nature Communications, 2014, 5 : 4329
Abstract: The formation of amphibole cumulates beneath arc volcanoes is a key control on magma geochemistry, and generates a hydrous lower crust. Despite being widely inferred from trace element geochemistry as a major lower crustal phase, amphibole is neither abundant nor common as a phenocryst phase in arc lavas and erupted pyroclasts, prompting some authors to refer to it as a “cryptic” fractionating phase. This study provides evidence that amphibole develops by evolved melts overprinting earlier clinopyroxene – a near-ubiquitous mineral in arc magmas. Reaction-replacement of clinopyroxene ultimately forms granoblastic amphibole lithologies. Reaction-replacement amphiboles have more primitive trace element chemistry (e.g. lower concentrations of incompatible Pb) than amphibole phenocrysts, but still have chemistries suitable for producing La/Yb and Dy/Yb “amphibole sponge” signatures. Amphibole can fractionate cryptically as reactions between melt and mush in lower crustal “hot zones” produce amphibole-rich assemblages, without significant nucleation and growth of amphibole phenocrysts.
DOI Link: 10.1038/ncomms5329
eISSN: 2041-1723
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit
Appears in Collections:Published Articles, Dept. of Geology

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