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Excess temperatures at ocean islands; implications for mantle layering and convection

Keith Putirka
Excess temperatures at ocean islands; implications for mantle layering and convection
Geology (Boulder) (April 2008) 36 (4): 283-286

Abstract

To test for the prevalence of mantle plumes and the existence of mantle layering, temperatures (T) are estimated for 28 oceanic hotspots, using olivine-liquid equilibria (T (super ol-liq) ). There are 27 localities that have T (super ol-liq) hotter than mid-ocean ridges (MOR), by 99-233 degrees C (average = 146+ or -26 degrees C), which translates to mantle potential temperatures that exceed those of MOR by 114-290 degrees C (average = 173+ or -38 degrees C). Thermally driven mantle plumes are thus common, not rare. Moreover, mantle temperatures at ocean islands are positively correlated with buoyancy flux and (super 3) He/ (super 4) He. The correlation with buoyancy affirms that oceanic swells are thermal in origin. The positive correlation with (super 3) He/ (super 4) He is inconsistent with the notion that high (super 3) He/ (super 4) He and depleted MOR mantle derive from the same layer, but instead shows that high (super 3) He/ (super 4) He is tied to a lower thermal boundary layer, and thus that the mantle is compositionally layered. Mantle temperatures are negatively correlated with Pb isotope ratios, supporting a model by C. Class and S. L. Goldstein that this deep, high (super 3) He/ (super 4) He layer may be depleted.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 36
Serial Issue: 4
Title: Excess temperatures at ocean islands; implications for mantle layering and convection
Author(s): Putirka, Keith
Affiliation: California State University, Fresno, Department of Earth and Environmental Sciences, Fresno, CA, United States
Pages: 283-286
Published: 200804
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 45
Accession Number: 2008-082519
Categories: Solid-earth geophysicsIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2008069
Illustration Description: illus.
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200824
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