Internal structure of lava flows, Rishiri Volcano

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Authors:Yoshida, T.; Yamaguchi, T.; Kawasaki, Y.
Volume Title:Ganseki Kobutsu Kosho Gakkai-Shi Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Source:Ganseki Kobutsu Kosho Gakkai-Shi = Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists, 76(6), p.181-194. Publisher: Nippon Ganseki Kobutsu Kosho Gakkai, c/o: Tohoku Daigaku Rigakubu, Sendai, Japan. ISSN: 0021-4825
Publication Date:1981
Note:In Japanese with English summary. 20 refs.; illus. incl. 3 tables, geol. sketch map
Summary:Three types of vesicular segregated bodies are recognized in the Kutsugata lava flows, Rishiri Volcano, Hokkaido: 'segregation layer', 'segregation cylinder' and 'segregation stock'. In transverse section the segregation layer is a flat-lying parallel banding from several mm to more than 10 cm thick. The segregation cylinder is a slender vertical column, connected with the segregation layer at the upper end of the column. The segregation stock is defined as a pulse or plume segregated from the host lava, and is associated with the segregation layer. These segregated bodies must have formed during consolidation of the lava flows which had ceased to move on the flat ground, in the sequence: segregation layers, segregation cylinders and finally segregation stocks. It is considered that there were three mechanisms of material transport in the Kutsugata lava flows: flow of a viscous liquid in the extension fractures; volatile channelling in the three-phase fluidized system; and diapiric uprise of low density plastic masses. Eight chemical analyses of the segregated bodies were compared with six from their host rocks in a typical thick lava flow, in order to trace the fractionation trends of the magma after extrusion. [M.Ak.]
Subjects:Andesites; Basalts; Dacites; Flow structures; Igneous rocks; Lava; Lava flows; Major elements; Modal analysis; Petrology; Pyroclastics; Sedimentary structures; Soft sediment deformation; Trace elements; Volcanic rocks; Asia; Far East; Hokkaido; Japan; Rishiri Island; Rishiri Volcano
Abstract Numbers:85M/0991
Record ID:1982059947
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom, Reference includes data from PASCAL, Institute de l'Information Scientifique et Technique
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