Proceedings of the Japan Academy, Series B
Online ISSN : 1349-2896
Print ISSN : 0386-2208
ISSN-L : 0386-2208
Review
Nd-isotopic composition of Phanerozoic sediments in the Inner Zone of Southwest Japan Arc : implications on provenance characteristics and contribution to formation of mature island arc system
Hiroo KAGAMIYoshinobu KAWANOToshiyuki IKAWANaoko NISHITsuyoshi TOYOSHIMATakuji HAMAMOTOYasutaka HAYASAKAYasuo IKEDAMasaki YUHARAYoshiaki TAINOSHO
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2004 Volume 80 Issue 1 Pages 1-9

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Abstract

The Nd-isotopic data on sedimentary and metamorphic rocks of SW Japan Arc allow their discrimination into five different depleted mantle (TDM) model age clusters, 2.6-2.45 Ga, 2.3-2.05 Ga, 1.9-1.55 Ga, 1.45-1.25 Ga, 1.2-0.85 Ga. The 2.6-2.45 Ga and 1.9-1.55 Ga model ages are also coincident with U-Pb inherited zircon ages of the above two epochs as well as the major magmatic activity in the Sino-Korean Craton (SKC). The 2.3-2.05 Ga model ages can be considered as the initial formation ages for the precursors of sedimentary rocks. The Nd-isotopic data suggest that the Hida Belt was most likely formed as a part of the SKC. The mantle underlying the Ryoke Belt had continental lithospheric signature during Triassic-Jurassic period. The 1.9-1.55 Ga model ages, especially 1.8 Ga~, can be associated with the formation of this belt. The source material for the sedimentary rocks occurring in the accretionary terrane of northeastern areas in the SW Japan Arc was probably in and around the SKC of the Ryoke Belt itself. The sedimentary rocks occurring in southwestern areas of the Arc were mainly composed of materials derived from a relatively younger source (1.45-0.85 Ga).


(Communicated by Syun-iti AKIMOTO, M.J.A., Jan. 13, 2004)

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© 2004 The Japan Academy
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