Publication Date:
2013-08-17
Description:
We analysed major and trace elements and Sr–Nd–Pb isotope ratios of Himeshima, Futagoyama and Aso volcanoes, northern Kyushu, Japan. The purpose of the study was to investigate the petrogenesis of Quaternary arc magmas of the northern Kyushu arc, Japan, through along-strike variations. The northern Kyushu arc is underlain by the Philippine Sea Plate, which is divided by the Kyushu–Palau Ridge into the Palaeogene West Philippine Basin segment (60–40 Ma) and the Miocene Shikoku Basin segment (26–15 Ma). The Sr/Y ratios of the arc lavas decrease from north to south along the volcanic front. Mixing relations in Sr–Nd–Pb isotope space suggest recycling of the subducted slab materials from the Philippine Sea Plate to the arc. The 87 Sr/ 86 Sr ratios decrease with increasing Sr/Y and SiO 2 , which argues against a genetic link of fractional crystallization between adakites and basaltic magmas. The observations further suggest that partial melting of the hot and young Shikoku Basin slab produces the high Sr/Y component visible in the arc magmas in the north, whereas dehydration of the older West Philippine Basin slab produces the low Sr/Y arc magmas in the south.
Print ISSN:
0305-8719
Electronic ISSN:
2041-4927
Topics:
Geosciences
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