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Please use this identifier to cite or link to this item: http://hdl.handle.net/11266/6626

Title: Petrogenesis of Plutonic Rocks in the Ryukyu Arc, Japan
Authors: Kawano, Yoshinobu
川野, 良信
Issue Date: 25-Mar-2018
Publisher: Rissho University
Abstract: The Cretaceous to Neogene plutonic rocks are distributed over the eight islands of the Ryukyu Arc, namely Amami-O-shima, Kakeroma-jima, Uke-jima, Tokuno-shima, Okinoerabu-jima, Okinawa-jima, Tonaki-jima, and Ishigaki-jima. These plutonic rocks can be categorized based on their petrological characteristics and active periods into four groups: early Cretaceous (EC), late Cretaceous (LC), Poleogene (PG), and Neogene (NG). The initial Sr isotopic ratio of the PG and NG groups increased, whereas the initial Nd isotopic ratio decreased with increasing aluminum saturation index (ASI), thereby indicating the influence of the upper crustal material. The LC group also exhibits a high initial Sr isotopic ratio, a low initial Nd isotopic ratio, and high ASI, presuming that the source magma reacted with the upper portion of the crustal material. Such reactions with the upper crustal material were observed to have occurred three times between Cretaceous and Neogene, and these events may have been caused by changes in the tectonics of the Ryukyu Arc.
URI: http://hdl.handle.net/11266/6626
ISBN: 9784582474411
Appears in Collections:Vol.1 The Academic Pilgrimage to Sustainable Social Development

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