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Mode of occurrence and significance of jadeite in the Kamuikotan metamorphic rocks, Hokkaido, Japan
Author(s) -
TAKAYAMA MASASHI
Publication year - 1986
Publication title -
journal of metamorphic geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.639
H-Index - 114
eISSN - 1525-1314
pISSN - 0263-4929
DOI - 10.1111/j.1525-1314.1986.tb00363.x
Subject(s) - lawsonite , geology , metamorphic rock , metamorphism , geochemistry , pelite , albite , metamorphic facies , petrology , isograd , quartz , mafic , mineral , facies , eclogite , tectonics , geomorphology , paleontology , subduction , structural basin , materials science , metallurgy
In the Kamuikotan zone, jadeite occurs in pelitic rocks, in metaplagiogranites, in veins in amphibolites and mafic sedimentary rocks, and in jadeite‐albite rocks. In the first and second types, jadeite is associated with quartz, and is often in direct contact with it. However, such rock‐types never occur as part of the coherent metamorphic sequence, but are found only as exotic blocks enclosed in serpentinite. Thus, jadeite + quartz‐bearing assemblages are not regarded as representative of the Kamuikotan metamorphism. Lawsonite and aragonite, however, commonly do occur in the Kamuikotan metamorphic rocks, and this metamorphism belongs to a subfacies of the lawsonite‐albite facies, in which aragonite is stable. The serpentinite matrix which carried jadeite + quartz‐bearing pelites and metaplagiogranites into the metamorphic sequence is interpreted as a tectonic rather than a sedimentary melange.