TY - JOUR
T1 - K-Ar analyses of the post-caldera lavas of Bratan volcano in Bali Island, Indonesia - Ar isotope mass fractionation to light isotope enrichment
AU - Ryu, Sunyoung
AU - Kitagawa, Hiroshi
AU - Nakamura, Eizo
AU - Itaya, Tetsumaru
AU - Watanabe, Koichiro
N1 - Funding Information:
We would like to thank Dr. A. Harijoko and Mr. T. Yamanaka for their help in field works in Bali Island. The JSPS Grant-in Aid financially supported this research (# 18404020 for K. Watanabe). We also thank Ms. Sakaguchi for her help on analyzing trace elements from the samples and Dr. C. Gouzu for his help on analyzing modal abundance of phenocrysts. The comments by the two reviewers (Karoly Nemeth and anonymous) improved the manuscript.
PY - 2013/8/15
Y1 - 2013/8/15
N2 - The post-caldera lavas of Bratan volcano in Bali Island, Indonesia were collected for whole rock chemical analyses and K-Ar analyses. Major and trace element chemistry shows that the lavas are basalts to andesites and typical of subduction-related tectonic setting. The 38Ar/36Ar ratios are 0.1851±3-0.1875±2 and the 40Ar/36Ar, 294.3±0.3-301.6±0.1, which strongly suggest that the mass fractionation to light isotope enrichment took place. The effect of the groundwater on magma is common on the basis of systematic mass fractionation of the atmospheric Ar enriched in lighter isotopes. This case was under the mass fractionation law analyzed numerically, giving the mass fractionation correction ages (14±15, 31±6, 55±22, 66±23, 94±32 and 125±51ka) consistent with the volcano stratigraphy though the magma composition that changed frequently in time.
AB - The post-caldera lavas of Bratan volcano in Bali Island, Indonesia were collected for whole rock chemical analyses and K-Ar analyses. Major and trace element chemistry shows that the lavas are basalts to andesites and typical of subduction-related tectonic setting. The 38Ar/36Ar ratios are 0.1851±3-0.1875±2 and the 40Ar/36Ar, 294.3±0.3-301.6±0.1, which strongly suggest that the mass fractionation to light isotope enrichment took place. The effect of the groundwater on magma is common on the basis of systematic mass fractionation of the atmospheric Ar enriched in lighter isotopes. This case was under the mass fractionation law analyzed numerically, giving the mass fractionation correction ages (14±15, 31±6, 55±22, 66±23, 94±32 and 125±51ka) consistent with the volcano stratigraphy though the magma composition that changed frequently in time.
KW - Ar isotope mass fractionation
KW - Bali island
KW - Bratan volcano
KW - K-Ar age
KW - Late Pleistocene volcanic rocks
KW - Sunda-Banda island arc
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U2 - 10.1016/j.jvolgeores.2013.07.002
DO - 10.1016/j.jvolgeores.2013.07.002
M3 - Article
AN - SCOPUS:84883647159
SN - 0377-0273
VL - 264
SP - 107
EP - 116
JO - Journal of Volcanology and Geothermal Research
JF - Journal of Volcanology and Geothermal Research
ER -