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Title Transcription
ゴウツ ソウグン シマ ノ ホシ ソウ ノ FT フィッション トラック ネンダイ
Title Alternative
FT age of the Shimanohoshi Formation of the Gotsu Group in the San-in district,SW Japan.
File
language
jpn
Author
Nagai, junya
Yamauchi, Seiki
Nagashima, Haruo
Description
The Plio-Pleistocene Gotsu Group is widely distributed in the Masuda to Oda districts of the coastal area of Shimane Prefecture.The Gotsu Group in the Hamada area is composed of clay,gravel and interbedded tuffs,and is divided into three formations,the Tsunozu,Shimanohoshi and Murogamiyama Formations,in ascending stratigraphic order.However,stratigraphic correlation between districts is difficult,because the tuffs in each formation are strongly weathered,vary markedly in thickness,and thus are not useful marker beds.
For this study,we carried out fission track dating of several tuffs and pyroclastic samples in the Shimanohoshi and Tsunozu Formations around the Gotsu and Ida areas,to examine the stratigraphy from a geochronological viewpoint.FT ages of zircons from the lower Shimanohoshi Formation were 1.05 to 1.24 Ma,respectively.The FT ages of the Shimanohoshi Formation(about 1.1 to 1.2 Ma)are comparable with previously reported pale magnetic data,which indicate the Jaramillo subchron(0.99~1.07 Ma).FT ages of 1 Ma from four localities in the south previously mapped as Minakami(equivalent to Tsunozu > 1.8 Ma)suggest these are actually Shimanohoshi Formation.Consequently,the distribution of this Formation may extend further south than mapped at present.
In future work,we will measure FT age from a wide area,spanning Masuda to Oda,to establish the Pliocene to Pleistocene stratigraphy of the San-in disthct.
Journal Title
島根大学地球資源環境学研究報告
Volume
22
Start Page
67
End Page
74
ISSN
13439774
Published Date
2003-12-27
NCID
AA11455176
Publisher
島根大学総合理工学部地球資源環境学教室
Publisher Aalternative
Department of Geoscience, Interdisciplinary Faculty of Science and Engineering, Shimane University
NII Type
Departmental Bulletin Paper
OAI-PMH Set
Interdisciplinary Graduate School of Science and Engineering
Remark
12-14,16+ / 1993+
飯泉滋教授・山内靖喜教授 退官記念特集号
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