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Basalt-andesite-rhyolite-H_2O: Crystallization intervals with excess H_2O and H_2O-undersaturated liquidus surfaces to 35 kolbras, with implications for magma genesis

Stern, Charles R. and Huang, Wuu-Liang and Wyllie, Peter J. (1975) Basalt-andesite-rhyolite-H_2O: Crystallization intervals with excess H_2O and H_2O-undersaturated liquidus surfaces to 35 kolbras, with implications for magma genesis. Earth and Planetary Science Letters, 28 (2). pp. 189-196. ISSN 0012-821X. http://resolver.caltech.edu/CaltechAUTHORS:20160128-151921847

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Abstract

Three rocks representing the calc-alkaline rock series gabbro-tonalite-granite or basalt-andesite-rhyolite were reacted with varying percentages of water in sealed capsules between 600 and 1300°C and pressures to 36 kbars, corresponding to depths of more than 120 km within the earth. For each rock we present complete P-T diagrams with excess water, and the water-undersaturated liquids surface projected from P-T-X_(H_2O) space mapped with contours for constant H_2O contents and with the fields for near-liquidus minerals. All changes in liquidus and solidus slopes can be correlated with changes in mineralogy from less dense to more dense, or with expansion of crystallization fields, without appeal to changes in molar volume of H_2O in liquid and vapor phases. The results indicate that tholeiites and andesites of the calc-alkaline series with compositions similar to the rocks studied are not primary magmas from mantle peridotite at depths greater than about 50 km. Primary andesitic magmas from shallower levels would require very high water contents and we do not believe such magmas could normally reach the surface. The liquids results are consistent with the derivation of andesites with little dissolved water as primary magmas from subducted ocean crust (quartz eclogite), but multi-stage models are preferred. Temperatures required for the generation of andesites by fusion of continental crust are higher than considered reasonable. The evidence precludes the generation of primary rhyolites or granites from the mantle of subducted oceanic crust at mantle depths. Primary rhyolite or granite magmas with moderate water contents (saturated or undersaturated) can be generated in the crust at reasonable temperatures, and could reach near-surface levels before vesiculation. Water-undersaturated granite liquid with residual crustal minerals could constitute plutonic magmas of intermediate composition.


Item Type:Article
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http://dx.doi.org/10.1016/0012-821X(75)90226-5DOIArticle
http://www.sciencedirect.com/science/article/pii/0012821X75902265PublisherArticle
Alternate Title:Basalt-andesite-rhyolite-H2O: Crystallization intervals with excess H2O and H2O-undersaturated liquidus surfaces to 35 kolbras, with implications for magma genesis
Additional Information:© 1975 Published by Elsevier B.V. Revised version received September 8, 1975. This research was supported by the Earth Sciences Section, National Science Foundation, NSF Grant DES 73-00191 A01. We wish to acknowledge also the general support of the Materials Research Laboratory by the National Science Foundation. We thank P.C. Bateman and F.C. Dodge for the tonalite and granite, and analyses of the rocks, and A.T. Anderson for critical review of the manuscript.
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Funding AgencyGrant Number
NSFDES 73-00191 A01
Record Number:CaltechAUTHORS:20160128-151921847
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20160128-151921847
Official Citation:Charles R. Stern, Wuu-Liang Huang, Peter J. Wyllie, Basalt-andesite-rhyolite-H2O: Crystallization intervals with excess H2O and H2O-undersaturated liquidus surfaces to 35 kolbras, with implications for magma genesis, Earth and Planetary Science Letters, Volume 28, Issue 2, December 1975, Pages 189-196, ISSN 0012-821X, http://dx.doi.org/10.1016/0012-821X(75)90226-5. (http://www.sciencedirect.com/science/article/pii/0012821X75902265)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:64066
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:28 Jan 2016 23:24
Last Modified:28 Jan 2016 23:24

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