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Crystallization temperatures of tholeiite parental liquids; implications for the existence of thermally driven mantle plumes

Trevor J. Falloon, David H. Green and Leonid V. Danyushevsky
Crystallization temperatures of tholeiite parental liquids; implications for the existence of thermally driven mantle plumes (in Plates, plumes, and planetary processes, Gillian R. Foulger (editor) and Donna M. Jurdy (editor))
Special Paper - Geological Society of America (2007) 430: 235-260

Abstract

To compare magmatic crystallization temperatures between ocean island basalt (OIB) proposed to be plume-related and normal mid-ocean ridge basalt (MORB) parental liquids, we have examined and compared in detail three representative magmatic suites from both ocean island (Hawaii, Iceland, and Reunion) and mid-ocean ridge settings (Cocos-Nazca, East Pacific Rise, and Mid-Atlantic Ridge). For each suite we have good data on both glass and olivine phenocryst compositions, including volatile (H (sub 2) O) contents. For each suite we have calculated parental liquid compositions at 0.2 GPa by incrementally adding olivine back into the glass compositions until a liquid in equilibrium with the most-magnesian olivine phenocryst composition is obtained. The results of these calculations demonstrate that there is very little difference (a maximum of approximately 20 degrees C) between the crystallization temperatures of the parental liquids (MORB 1243-1351 degrees C versus OIB 1286-1372 degrees C) when volatile contents are taken into account. To constrain the depths of origin in the mantle for the parental liquid compositions, we have performed experimental peridotite-reaction experiments at 1.8 and 2.0 GPa, using the most magnesian of the calculated parental MORB liquids (Cocos-Nazca), and compared the others with relevant experimental data utilizing projections within the normative basalt tetrahedron. The mantle depths of origin determined for both the MORB and OIB suites are similar (MORB 1-2 GPa; OIB 1-2.5 GPa) using this approach. Calculations of mantle potential temperatures (T (sub p) ) are sensitive to assumed source compositions and the consequent degree of partial melting. For fertile lherzolite sources, T (sub p) for MORB sources ranges from 1318 to 1488 degrees C, whereas T (sub p) for ocean island tholeiite sources (Hawaii, Iceland, and Reunion) ranges from 1502 degrees C (Reunion) to 1565 degrees C (Hawaii). The differences in T (sub p) values between the hottest MORB and ocean island tholeiite sources are approximately 80 degrees C, significantly less than predicted by the thermally driven mantle plume hypothesis. These differences disappear if the hotspot magmas are derived by smaller degrees of partial melting of a refertilized refractory source. Consequently the results of this study do not support the existence of thermally driven mantle plumes originating from the core-mantle boundary as the cause of ocean island magmatism.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 430
Title: Crystallization temperatures of tholeiite parental liquids; implications for the existence of thermally driven mantle plumes
Title: Plates, plumes, and planetary processes
Author(s): Falloon, Trevor J.Green, David H.Danyushevsky, Leonid V.
Author(s): Foulger, Gillian R.editor
Author(s): Jurdy, Donna M.editor
Affiliation: University of Tasmania, School of Earth Sciences and Centre for Marine Science, Tasmania, Australia
Affiliation: Durham University, Department of Earth Sciences, Durham, United Kingdom
Pages: 235-260
Published: 2007
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 80
Accession Number: 2008-045013
Categories: Solid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices and discussion
Illustration Description: illus. incl. 5 tables
N18°55'00" - N20°16'00", W156°04'60" - W154°49'60"
Secondary Affiliation: Australian National University, AUS, Australia
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200813
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