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Microboudin structures of piemontite along the Sambagawa metamorphic belt, Japan: implications for lateral variation of differential stress during regional metamorphism
Author(s) -
Masuda T.,
Shibutani T.,
Ochiai T.,
Akagi S.,
Yamaguchi H.,
Kugimiya Y.,
Kimura N.,
Miyake T.
Publication year - 2004
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.1525-1314.2004.00507.x
Subject(s) - metamorphism , metamorphic rock , differential stress , geology , geochemistry , quartz , differential (mechanical device) , stress (linguistics) , paleontology , deformation (meteorology) , linguistics , oceanography , philosophy , aerospace engineering , engineering
Evidence is presented of a lateral variation in differential stress during metamorphism along a regional metamorphic belt on the basis of the proportion of microboudinaged piemontite grains ( p ) in a quartz matrix in metacherts. It is proposed that p is a practical indicator of relative differential stress. Analysis of 123 metacherts from the 800 km long Sambagawa metamorphic belt, Japan, reveals that p ‐values range from < 0.01 to 0.7 in this region. Most samples from Wakayama in the mid‐belt area have p ‐values of 0.4–0.6, whereas those from western Shikoku have p ‐values of < 0.1. This difference cannot be explained by variations in metamorphic temperature, and is instead attributed to a regional, lateral variation in differential stress during metamorphism.