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Lanphere, M.A. and Dalrymple, G.B. (1980). Age and strontium isotopic composition of the Honolulu Volcanic Series, Oahu, Hawaii. American Journal of Science 280-A: 736-751. |
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K-Ar ages on basalts from 12 vents of the Honolulu Volcanic Series suggest that these post-erosional basalts were erupted less than about 0.6 m.y. ago. The reproducibility of argon measurements on basalts from 6 of the vents is poor, and for some samples the calculated ages are older than the younger age limit for the underlying Koolau Volcanic Series. These data indicate that at least some of the Honolulu basalts contain variable amounts of excess radiogenic 40Ar that probably was contributed to the basaltic liquid from ultramafic xenoliths. 87Sr/86Sr ratios for 14 basalts of the Honolulu Volcanic Series and 8 basalts of the Koolau Volcanic Series have weighted mean values of 0.70332 + or - 0.00004 and 0.70386 + or - 0.00006, respectively. These data clearly demonstrate the heterogeneity of the mantle source regions for basalt beneath Oahu and also indicate that the time-integrated Rb/Sr ratio in the source region for basalts of the Honolulu Volcanic Series is lower (that is, indicates a less differentiated source) than in the source region for basalts of the Koolau Volcanic Series. |
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Keywords
absolute age; abundance; age; alkali basalts; alkali metals;, alkaline earth metals; basalts; Cenozoic; dates; East Pacific, Ocean Islands; geochemistry; geochronology; Hawaii; Honolulu, County Hawaii; Honolulu Volcanic Series; igneous rocks; isotopes;, K/Ar; Koolau Volcanic Series; metals; Oahu; Oceania; Polynesia;, Quaternary; ratios; rubidium; Sr-87/Sr-86; stable isotopes;, strontium; tholeiite; United States; upper Quaternary; volcanic, rocks; volcanism; volcanology, 02, Geochemistry |
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Publisher
The American Journal of Science, Yale University
P.O. Box 208109
New Haven, CT 06520-8109
USA
203-432-3131
203-432-5668
ajs@yale.edu |
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