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Comparison of ^(230)Th-^(238)U disequilibrium systematics in lavas from three hot spot regions: Hawaii, Prince Edward and Samoa

Newman, S. and Finkel, R. C. and Macdougall, J. D. (1984) Comparison of ^(230)Th-^(238)U disequilibrium systematics in lavas from three hot spot regions: Hawaii, Prince Edward and Samoa. Geochimica et Cosmochimica Acta, 48 (2). pp. 315-324. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20181016-153902392

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Abstract

^(230)Th-^(238)U disequilibrium systematics reveal several important characteristics of the mantle source regions and petrogenesis of volcanic rocks in the presumed hot spots of Hawaii, Marion Island (Prince Edward hot spot), and Samoa. The (^(230)th/^(232)Th) activity ratios of lavas from these three hot spots (1.06 ± 0.07, 1.04 ± 0.08, and 0.81 ± 0.06, respectively) imply that the source regions are each nearly homogeneous with Th/U weight ratios of 2.9, 3.0, and 3.8. For Marion Island and Mauna Kea, Hawaii, negligible secular variation occurs in the (^(230)Th-^(232)Th) initial ratios. This supports other evidence for very short transfer time between source and surface. Significant residence time at depth prior to eruption cannot be ruled out for the Samoan lavas we have studied; however, the data for one of these flows deviate from the proposed ((^(230)Th-^(232)Th)-^(87)sr/^(86)Sr)- correlation (Condomineset al., 1981a) in the opposite sense from that expected for such residence. If it is assumed that the measured ((^(230)Th-^(232)Th)) ratios of the young lavas reflect Th/U in their mantle sources, then the observed variations among these three hot spots, combined with those reported by other workers for Iceland, the Azores and Tristan de Cunha, suggest that these sources are characterized by Th/U ratios ranging from values similar to that of MORB source (~2.5) to values similar to those of bulk earth (~3.8). Mixing of different proportions of depleted and enriched mantle may be responsible for the observed range.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/0016-7037(84)90253-9DOIArticle
ORCID:
AuthorORCID
Newman, S.0000-0003-0710-995X
Alternate Title:Comparison of 230Th-238U disequilibrium systematics in lavas from three hot spot regions: Hawaii, Prince Edward and Samoa
Additional Information:© 1984 Published by Elsevier. (Received July 26, 1983; accepted in revised form November 14, 1983) The authors thank the following people for providing samples: Stephen Porter, University of Washington. Seattle (Mauna Kea), David Clague. U.S. Geological Survey, Menlo Park (Loihi); Wilhelm J. Verwoerd, University of Stellenbosch, South Africa (Marion Island); James Natland and Elizabeth Wright, Scripps Institution of Oceanography, La Jolla (Savai’i, Samoa). We thank M. Hitchcox for assistance with manuscript preparation. This work was supported by NSF grants EAR8000484 and EAR8026448.
Funders:
Funding AgencyGrant Number
NSFEAR-8000484
NSFEAR-8026448
Issue or Number:2
Record Number:CaltechAUTHORS:20181016-153902392
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20181016-153902392
Official Citation:S Newman, R.C Finkel, J.D Macdougall, Comparison of 230Th-238U disequilibrium systematics in lavas from three hot spot regions: Hawaii, Prince Edward and Samoa, Geochimica et Cosmochimica Acta, Volume 48, Issue 2, 1984, Pages 315-324, ISSN 0016-7037, https://doi.org/10.1016/0016-7037(84)90253-9. (http://www.sciencedirect.com/science/article/pii/0016703784902539)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90290
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:22 Oct 2018 16:12
Last Modified:03 Oct 2019 20:23

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