Hemispherical lens-shaped joints observed in the Narukawa Andesite, Nanae, Hokkaido

• NAKAJIMA Hisashi

  Takaoka Primary School

• NIIDA Kiyoaki

  Graduate School of Science, Hokkaido University

Bibliographic Information

Other Title

• 北海道亀田郡七飯町産の鳴川安山岩にみられる「半球面レンズ状節理」
• ホッカイドウ カメダグン ナナエチョウサン ノ ナルカワ アンザンガン ニ ミラレル ハンキュウメン レンズジョウ セツリ

Abstract

Extension joints with a peculiar shape of hemispherical lens were observed in the Narukawa Andesite, Nanae, Hokkaido. The size of the joints ranges from 5 to 46cm in diameter and from 0.7 to 2.4cm in depth. The occurrence of the hemispherical joints is restricted on the surface of platy and/or columnarjoints of the andesite lavas. The joint surface morphology is characterized by a plumose pattern, which is distinctive at the joint fringes. The hackle marks are also common around plagioclase megacrysts, which can be observed on the bottom of the hemispherical lenses. In some cases the jointing stays on the half ways, where the lenses remain on the platy surface of lavas. Taking all the modes of occurrence into considerations, the hemispherical lens-shaped joints are explained as extensional cracks initiated by a residual strain within individually jointed blocks of plates and/or columns in the andesite lavas.

Journal

• Earth Science (Chikyu Kagaku)

  Earth Science (Chikyu Kagaku) 58 (3), 179-184, 2004

  The Association for the Geological Collaboration in Japan

Keywords

• extension joint
• hemispherical lens
• plumose
• hackle
• Narukawa Andesite
• Hakodate
• Nanae

Details

• CRID: 1390282679242068480
• NII Article ID: 110004860755
• NII Book ID: AN00141269
• DOI: 10.15080/agcjchikyukagaku.58.3_179
• ISSN: 21897212
• ISSN: 03666611
• NDL BIB ID: 6960762
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I6960762
• Text Lang: ja
• Data Source:
  • JaLC
  • NDL
  • CiNii Articles
  • KAKEN
  • Crossref
• Abstract License Flag: Disallowed