Publication Date:
2015-07-18
Description:
The Comment by Pineda-Velasco et al . [2015] examined Pb isotope data presented by Kimura et al . [2014]. The authors' points are that (1) there is uncertainty in the analytical results of Kimura et al . [2014] due to the effect of mass fractionation, and therefore, (2) the interpretations of Kimura et al . [2014] based on the extent of crustal assimilation and the estimated Pb isotopic composition of the crustal component are erroneous. In response to the Comment, we report a flaw in the original paper that the samples from the Aono, Daisen, and Kannabe regions were analyzed using conventional TIMS methods and all other samples were analyzed using thallium-spiked multi-collector inductively-coupled-plasma mass spectrometry (TS-MC-ICP-MS). We have re-analyzed the sample powders from Karasugasen, Daisen, and Aono using TS-MC-ICP-MS. Our new results showed considerable overlap with the data in Pineda-Velasco et al . [2015]. Therefore, the isotopic trends shown by the conventional TIMS in Kimura et al . [2014] were analytical artifacts from mass bias. We conclude that the crustal assimilation proposed by Kimura et al . [2014] was erroneous in terms of Pb isotopes, nevertheless some crustal assimilation in the Karasugasen lava is evident from the chemical zoning of hornblende phenocrysts. Although the original Pb isotope argument for crustal contamination was wrong, the ABS4 modeling is unaffected because of no to subtle changes in estimated mantle source compositions in their ABS4 model. This article is protected by copyright. All rights reserved.
Electronic ISSN:
1525-2027
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
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