このエントリーをはてなブックマークに追加
ID 47115
file
title alternative
Geology of Katsuyama-Osakabe Area, Okayama Prefecture, Southwest Japan: Chaotic Rock Bodies Originated by Sedimentary and Diapiric Processes
creator
NDC
Earth sciences. Geology
abstract
On the basis of the results of field surveying and microstructural study, we describe here the occurrence of chaotic rocks formed by diapiric processes, and the structural relationships between the Ohsayama serpentinite mélange, the Permian olistostrome, and the Sangun metamorphic rocks. The Ohsayama serpentinite mélange is distributed in the Osakabe area and was defined by Tsujimori (1998) as a tectonic mélange with a serpentinite matrix. It contains blueschist-facies schists with a metamorphic age (320 Ma) older than that of the Sangun metamorphic rocks (180 Ma), and is traceable to the north of the Permian olistostrome. The Permian olistostrome is distributed in the Katsuyama area and consists of submarine sliding deposits with mudstone, sandstone, alternating beds of sandstone and mudstone, and limestone blocks. In addition to these rocks, we newly found chaotic rocks of diapiric origin. These chaotic rocks are characterized by a predominant mud matrix and non-sorted clasts with sizes ranging from 1 mm to more than 10 m. The distribution of the chaotic rock body cuts the bedding planes of the other strata at a high angle. The clasts have irregular shapes, a zigsaw-puzzle structure, and disaggregated wisps. These features indicate that the clasts were broken and driven upward by overpressured fl uids. The Sangun metamorphic rocks, which are of a high pressure type and commonly show three generations of foliation, underlie both the Ohsayama serpentinite mélange and Permian olistostrome with a fault contact and form syncline trending E-W and plunging 7°to west at the northeast part of the surveyed area.
journal title
Bulletin of the Graduate School of Integrated Arts and Sciences, Hiroshima University. II, Studies in environmental sciences
volume
Volume 13
start page
19
end page
39
date of issued
2018-12-31
publisher
広島大学大学院総合科学研究科
issn
1881-7696
ncid
language
jpn
nii type
Departmental Bulletin Paper
HU type
Departmental Bulletin Papers
DCMI type
text
format
application/pdf
text version
publisher
rights
掲載された論文,研究ノート,要旨などの出版権・著作権は広島大学大学院総合科学研究科に帰属する。
Copyright (c) 2018 Graduate School of Integrated Arts and Sciences, Hiroshima University, All rights reserved.
department
Graduate School of Integrated Arts and Sciences
他の一覧