Premium
Apatite fission‐track dating of fault‐related rocks along the Nojima and Kusumoto faults and its tectonic significance
Author(s) -
Ito Hisatoshi
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl020776
Subject(s) - geology , fault (geology) , fission track dating , tectonics , seismology , geochemistry , geothermal gradient , apatite , active fault , detachment fault , fault gouge , fault scarp , quaternary , geophysics , paleontology , extensional definition
The tectonic history of the Nojima fault, a ∼10 km‐long active fault whose movement caused the disastrous 1995 Kobe earthquake, was studied by the apatite fission‐track (AFT) dating method. AFT ages of 63–83 Ma from a thermally undisturbed uplifted block indicate relatively minor uplift since ∼65 Ma with an estimated total exhumation of ∼3.6 km assuming a geothermal gradient of 25°C/km. AFT ages of 44–54 Ma and the nature of the track length distribution from fault‐related rocks indicate that fault‐related hydrothermal minerals, such as laumontite and chlorite, and foliated cataclasite were formed by ancient fault activity that occurred before ∼44 Ma. It is inferred that the Quaternary fault activity of the Nojima fault is a relatively major phase in the entire tectonic history of the Nojima fault.