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Paleostress fields from calcite twins in the Pyeongan Supergroup, South Korea
Author(s) -
Kang SeongSeung,
Kim JunMo,
Jang BoAn
Publication year - 2005
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/j.1440-1738.2005.00462.x
Subject(s) - geology , supergroup , calcite , orogeny , cretaceous , mesozoic , paleontology , paleozoic , period (music) , tectonics , physics , structural basin , acoustics
Paleostress fields of the Late Paleozoic to Early Mesozoic Pyeongan Supergroup that is distributed along the northeastern part of the Ogcheon Belt in South Korea were investigated using the calcite strain gauge (CSG) technique. Combining the results of this study with those of other studies investigating the relationship between twin strain, twin density and width, which are used as indicators of deformation conditions in the natural low‐temperature deformation of limestone, it was estimated that calcite twins in the study area were probably formed at temperatures lower than 170°C. From two samples, two different principal paleostress directions were inferred from calcite twins, while only one direction was inferred from two other samples. This result suggests that deformation occurred during two or more different tectonic events in the Pyeongan Supergroup during the Mesozoic era. The maximum shortening axis was oriented in two directions, northeast–southwest and northwest–southeast, respectively, which coincide well with the paleostress directions inferred from the stress inversion for many fault sets. Combining the results of the paleostress analysis from this and other studies, we hypothesize that the directions of the maximum shortening axis in the Pyeongan Supergroup changed from northeast–southwest during the pre‐Daebo orogeny period (Late Triassic period) to northwest–southeast during the syn‐Daebo orogeny period (Early Jurassic to Early Cretaceous period) in the Mesozoic era.